Water-resistant and moisture-resistant paper-faced gypsum board and process for making same

Abstract

The present application relates to the technical field of gypsum board, in particular to water-resistant and moisture-proof paper-faced gypsum board and its preparation process, comprising two layers of modified facing paper and gypsum board core material between the two layers of modified facing paper, characterized in that the gypsum board core material is composed of modified core material slurry, and the raw materials of the modified core material slurry are composed of the following components: gypsum clinker, water, cement particle ball, premixed paste, alkali-free glass fiber, hydrophobic / hydrophilic mixed starch, hydroxypropyl methyl cellulose, coagulant, and silicon oil catalyst. The present application builds a micro-nano titanium dioxide / silane composite hydrophobic coating on the surface of the facing paper to form the first physical water-blocking layer, and introduces silane-modified nanocellulose and emulsified silicon oil into the core to establish a hydrophobic network inside the core material, and the two form a gradient protection structure of surface shielding and internal hydrophobicity. Even if the outer coating is partially worn, the core material can still effectively prevent water diffusion, significantly improving the water resistance reliability in long-term humid environment.

Description

Technical Field

[0001] This invention relates to the field of gypsum board technology, specifically to water-resistant and moisture-proof paper-faced gypsum board and its preparation process. Background Technology

[0002] Paper-faced gypsum board is widely used in building partitions and ceilings due to its advantages such as being lightweight, fireproof, soundproof, and easy to process. However, ordinary paper-faced gypsum board is prone to absorbing moisture in humid environments (such as bathrooms and basements), which can lead to a decrease in the strength of the core material, delamination between the facing paper and the core material, deformation of the board, and even mold growth, severely limiting its use in places with high humidity.

[0003] To improve the water resistance of gypsum board, existing technologies mainly adopt the following two approaches: one is to add hydrophobic agents such as silicone oil and paraffin emulsion to the core of the board, and use their hydrophobicity to reduce the water absorption rate of the core material; the other is to waterproof the facing paper, such as by coating it with silicone or film.

[0004] Most existing products rely solely on the hydrophobicity of the core material or the waterproofness of the facing paper. The two lack synergy, and once the facing paper is damaged or the hydrophobic agent in the core material is unevenly dispersed, moisture can quickly penetrate the entire board along capillary channels, leading to a sharp decline in water resistance. Therefore, in response to the problems mentioned above, this invention proposes a water-resistant and moisture-proof paper-faced gypsum board and its preparation process. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide water-resistant and moisture-proof paper-faced gypsum board and its preparation process to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Water-resistant and moisture-proof paper-faced gypsum board, comprising two layers of modified facing paper and a gypsum board core material between the two layers of modified facing paper; The gypsum board core material is composed of modified core slurry, and the raw materials of the modified core slurry include, by weight parts: 100 parts gypsum clinker, 60-80 parts water, 8-15 parts cement granules, 5-10 parts premixed paste, 1-3 parts alkali-free glass fiber, 0.8-2 parts hydrophobic / hydrophilic mixed starch, 0.3-0.8 parts hydroxypropyl methylcellulose, 0.1-0.4 parts accelerator, 0.1-0.2 parts silicone oil catalyst, 0.05-0.15 parts mildew inhibitor, 0.2-0.6 parts water-reducing agent, 0.3-0.7 parts crystal form modifier, 0.5-1.2 parts lime; The modified core slurry is prepared through the following steps: Gypsum clinker, water, cement granules, premixed paste, alkali-free glass fiber, hydrophobic / hydrophilic mixed starch, hydroxypropyl methylcellulose, coagulant, silicone oil catalyst, mildew inhibitor, water-reducing agent, crystal form modifier, and lime are mixed together. At the same time, 0.4-1 parts of emulsified silicone oil and 0.1-0.3 parts of foaming agent are added together and stirred for 5-10 minutes to obtain modified core slurry.

[0007] Furthermore, the modified face paper is prepared through the following steps: S1. Mix nano-titanium dioxide and micron-sized titanium dioxide to obtain a mixed powder; mix KH-550 and POTS, add anhydrous ethanol for dilution, stir at room temperature for 10-15 minutes to obtain a mixed solution, add the mixed solution dropwise to the mixed powder, stir and mix to obtain a mixture; S2. React the mixture at 80-100℃ for 1-2 hours. After the reaction is complete, grind and sieve to obtain ground powder. Mix the ground powder with water-based acrylic emulsion and add deionized water to adjust the coating viscosity to 300-500 mPa·s to obtain modified slurry. S3. Apply the modified slurry to the surface of the base paper (A 890-W type) using a roller coating method. The coating speed is controlled at 30-50 m / min, and the wet film thickness is controlled at 30-50 μm. After coating, perform three-stage drying: stage 100-120℃, stage 2 130-150℃, and stage 3 100-110℃ for cooling and shaping. The total drying time is about 2-5 minutes, resulting in the modified face paper.

[0008] Furthermore, the cement granule balls are prepared through the following steps: Silicate cement and aerogel particles are premixed for 5-10 minutes, and then polyvinyl acetate-ethylene emulsion is sprayed in while stirring. After the mixture is finished, it is rolled into granules to obtain granules. The granules are then cured at room temperature for 20-24 hours and then dried at 60-80℃ to constant weight to obtain cement granules. The premixed paste is prepared through the following steps: S101. Disperse the nanocellulose crystal powder in anhydrous ethanol and sonicate for 30-35 min to obtain a uniform ethanol dispersion; mix KH-570 and POTS, add to anhydrous ethanol, adjust the pH to 4.0-4.5 with glacial acetic acid, and stir at room temperature for 15-20 min to obtain a hydrolysate. S102. Add the hydrolysate to the alcohol dispersion and stir the reaction at 60-70℃ for 4-6 hours. After the reaction is complete, centrifuge to collect the precipitate and wash the precipitate 2-3 times each with anhydrous ethanol and deionized water to obtain modified nanocellulose. S103. Mix modified nanocellulose with deionized water, stir for 30-50 minutes, then add gypsum powder and mix to form a premixed paste.

[0009] Furthermore, in step S1, the mass ratio of nano titanium dioxide, micron titanium dioxide, KH-550, POTS, and anhydrous ethanol is 10:(5-10):(0.5-1.2):(0.3-0.8):(20-25), and the mass ratio of the mixed liquid to the mixed powder is 1:(3-5).

[0010] Furthermore, in step S2, the mass ratio of the ground powder to the aqueous acrylic emulsion is 1:(8-12), wherein the aqueous acrylic emulsion is composed of an acrylic emulsion and deionized water in a mass ratio of 1:(0.3-0.6).

[0011] Furthermore, in the preparation step of the cement granules, the mass ratio of silicate cement, aerogel particles, and polyvinyl acetate-ethylene emulsion is 100:(3-8):(5-12).

[0012] Furthermore, in step S101, the mass ratio of nanocellulose crystal powder to anhydrous ethanol is 1:(80-120), and the mass ratio of KH-570, POTS, and anhydrous ethanol is 1:(0.4-0.8):(30-50).

[0013] Furthermore, in step S102, the mass ratio of hydrolysate to alcohol dispersion is 1:(4-6).

[0014] Furthermore, in step S103, the mass ratio of modified nanocellulose, deionized water, and gypsum powder is 1:(80-120):(20-40).

[0015] Furthermore, the preparation process of the water-resistant and moisture-proof paper-faced gypsum board includes the following steps: S201, Prepare modified core slurry; S202. The modified core slurry is poured onto the upper surface of the lower facing paper. After leveling, the upper facing paper is covered on top and extruded at 30-35MPa. The molded gypsum board is left to stand for 30-35 minutes to complete the setting. After setting, it is dried in sections. It is preheated at 110-120℃ for 30-40 minutes, then dried at 140-150℃ for 40-60 minutes, and finally buffered at 60-80℃ for 15-25 minutes. After drying, the water-resistant and moisture-proof paper-faced gypsum board is obtained.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention constructs a micro-nano titanium dioxide / silane composite hydrophobic coating on the surface of the face paper to form the first physical water-blocking layer. At the same time, silane-modified nanocellulose and emulsified silicone oil are introduced into the core to establish a hydrophobic network inside the core material. The two work together to form a gradient protection structure of surface shielding and internal hydrophobicity. Even if the outer coating is locally worn, the core material can still effectively prevent moisture diffusion, which significantly improves the water resistance reliability in long-term humid environments. 2. This invention uses aerogel-coated cement granules as lightweight aggregate, significantly reducing the core density of the board. Simultaneously, modified nanocellulose forms a nano-bridging network at the gypsum grain boundaries, compensating for the strength loss caused by lightweighting. Furthermore, hydrophobic / hydrophilic mixed starch and hydroxypropyl methylcellulose synergistically thicken the slurry, improving the flowability of the slurry and the bonding force between the board and paper. This allows the board to achieve excellent dry and wet flexural strength and bonding strength while maintaining low density, resolving the technical contradiction of achieving both lightweight and high strength. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation process of the water-resistant and moisture-proof paper-faced gypsum board in this invention; Figure 2 This is a schematic diagram of the preparation process of the modified face paper in this invention; Figure 3 This is a schematic diagram of the preparation process of the premixed paste in this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figures 1-3 The present invention provides a technical solution: Example 1: Water-resistant and moisture-proof paper-faced gypsum board, comprising two layers of modified facing paper and a gypsum board core material between the two layers of modified facing paper. The gypsum board core material is composed of modified core slurry, the raw materials of which consist of the following components: 1000g gypsum clinker, 600g water, 80g cement granules, 50g premixed paste, 10g alkali-free glass fiber, 8g hydrophobic / hydrophilic mixed starch (hydrophobic starch and hydrophilic starch in a 1:1 ratio), 3g hydroxypropyl methylcellulose, 1g coagulant (potassium sulfate), 1g silicone oil catalyst (dibutyltin dilaurate), 0.5g mildew inhibitor (LD520C), 2g water-reducing agent (ViscoCrete G2-A), 3g crystal form modifier (citric acid monohydrate), 5g lime, 4g emulsified silicone oil, and 1g foaming agent (sodium dodecyl sulfate).

[0020] Preparation process of water-resistant and moisture-proof paper-faced gypsum board: I. Preparation of cement granule balls: Weigh 100g of silicate cement and 3g of aerogel particles, premix for 5 minutes, spray in 5g of polyvinyl acetate-ethylene emulsion while stirring, roll into granules, cure at room temperature for 20 hours, and dry at 60℃ to constant weight to obtain cement granule balls.

[0021] II. Preparation of premixed paste: S101. Weigh 1g of nanocellulose crystal powder and disperse it in 80g of anhydrous ethanol. Sonicate for 30min to obtain an alcohol dispersion. Weigh 1g of KH-570, 0.4g of POTS and 30g of anhydrous ethanol, mix them, adjust the pH to 4.0 with glacial acetic acid, and stir for 15min to obtain a hydrolysate.

[0022] S102. Add 10g of hydrolysate to 40g of alcohol dispersion, react at 60℃ for 4h, and centrifuge and wash the precipitate twice to obtain modified nanocellulose.

[0023] S103. Add 1g of modified nanocellulose to 80g of deionized water and stir for 30min. Then add 20g of gypsum powder and mix well to obtain a premixed paste.

[0024] III. Preparation of Modified Facing Paper: S1. Mix 10g of nano titanium dioxide and 5g of micron titanium dioxide to obtain a mixed powder; add 0.5g of KH-550 and 0.3g of POTS to 20g of anhydrous ethanol for dilution, stir for 10min to obtain a mixed solution, and add 10g of the mixed solution to 30g of the mixed powder to obtain a mixture.

[0025] S2. React the mixture at 80℃ for 1 hour, grind and sieve; mix 10g of the ground powder with 80g of water-based acrylic emulsion (composed of 61.5g of acrylic emulsion and 18.5g of deionized water), add deionized water to adjust the viscosity to 300mPa·s to obtain the modified slurry.

[0026] S3. The modified slurry is coated on the surface of the base paper of the face paper by roller coating at a speed of 30m / min and a wet film thickness of 30μm. After coating, the paper is dried in three stages: 100℃, 130℃ and 100℃, with a total drying time of 2min, to obtain the modified face paper.

[0027] IV. Preparation of Water-Resistant and Moisture-Proof Paper-Faced Gypsum Board: Mix all the main materials together, add 4g of emulsified silicone oil and 1g of foaming agent, stir for 5 minutes to obtain modified core slurry, pour the modified core slurry onto the lower facing paper, cover with the facing paper, and extrude at 30MPa to form; let the wet board stand for 30 minutes to solidify; preheat at 110℃ for 30 minutes → dry at 140℃ for 40 minutes → buffer at 60℃ for 15 minutes to obtain water-resistant and moisture-proof paper-faced gypsum board.

[0028] Example 2: Water-resistant and moisture-proof paper-faced gypsum board, comprising two layers of modified facing paper and a gypsum board core material between the two layers of modified facing paper. The gypsum board core material is composed of modified core slurry, the raw materials of which consist of the following components: 1000g gypsum clinker, 700g water, 110g cement granules, 80g premixed paste, 20g alkali-free glass fiber, 15g hydrophobic / hydrophilic mixed starch, 6g hydroxypropyl methylcellulose, 2.5g accelerator, 1.5g silicone oil catalyst, 1g mildew inhibitor, 4g water-reducing agent, 5g crystal form modifier, 8g lime, 6g emulsified silicone oil, and 2g foaming agent.

[0029] Preparation process of water-resistant and moisture-proof paper-faced gypsum board: I. Preparation of cement granule balls: Weigh 100g of silicate cement and 6g of aerogel particles, premix for 8 minutes, spray in 9g of polyvinyl acetate-ethylene emulsion while stirring, roll into granules, cure at room temperature for 22 hours, and dry at 70℃ to constant weight to obtain cement granule balls.

[0030] II. Preparation of premixed paste: S101. Weigh 1g of nanocellulose crystal powder and disperse it in 100g of anhydrous ethanol. Sonicate for 33min to obtain an alcohol dispersion. Weigh 1g of KH-570, 0.6g of POTS and 40g of anhydrous ethanol, mix them, adjust the pH to 4.3 with glacial acetic acid, and stir for 18min to obtain a hydrolysate.

[0031] S102. Add 10g of hydrolysate to 50g of alcohol dispersion, react at 65℃ for 5h, centrifuge and wash the precipitate twice to obtain modified nanocellulose.

[0032] S103. Add 1g of modified nanocellulose to 100g of deionized water and stir for 40min. Then add 30g of gypsum powder and mix well to obtain a premixed paste.

[0033] III. Preparation of Modified Facing Paper: S1. Mix 10g of nano titanium dioxide and 8g of micron titanium dioxide to obtain a mixed powder; add 0.8g of KH-550 and 0.6g of POTS to 22g of anhydrous ethanol for dilution, stir for 13min to obtain a mixed solution, and add 10g of the mixed solution to 40g of the mixed powder to obtain a mixture.

[0034] S2. React the mixture at 90℃ for 1.5h, grind and sieve; mix 10g of ground powder with 100g of water-based acrylic emulsion (composed of 66.7g of acrylic emulsion and 33.3g of deionized water), add deionized water to adjust the viscosity to 400mPa·s to obtain the modified slurry.

[0035] S3. The modified slurry is coated on the surface of the base paper of the face paper by roller coating at a speed of 40m / min and a wet film thickness of 40μm. After coating, the paper is dried in three stages: 110℃, 140℃ and 105℃, with a total drying time of 3.5min, to obtain the modified face paper.

[0036] IV. Preparation of Water-Resistant and Moisture-Proof Paper-Faced Gypsum Board: Mix all the main materials together, add 6g of emulsified silicone oil and 2g of foaming agent, stir for 8 minutes to obtain modified core slurry, pour the modified core slurry onto the lower facing paper, cover with the facing paper, and extrude at 33MPa to form; let the wet board stand for 33 minutes to solidify; preheat at 115℃ for 35 minutes → dry at 145℃ for 50 minutes → buffer at 70℃ for 20 minutes to obtain water-resistant and moisture-proof paper-faced gypsum board.

[0037] Example 3: Water-resistant and moisture-proof paper-faced gypsum board, comprising two layers of modified facing paper and a gypsum board core material between the two layers of modified facing paper. The gypsum board core material is composed of modified core slurry, the raw materials of which consist of the following components: 1000g gypsum clinker, 800g water, 150g cement granules, 100g premixed paste, 30g alkali-free glass fiber, 20g hydrophobic / hydrophilic mixed starch, 8g hydroxypropyl methylcellulose, 4g setting accelerator, 2g silicone oil catalyst, 1.5g mildew inhibitor, 6g water-reducing agent, 7g crystal form modifier, 12g lime, 10g emulsified silicone oil, and 3g foaming agent.

[0038] Preparation process of water-resistant and moisture-proof paper-faced gypsum board: I. Preparation of cement granule balls: Weigh 100g of silicate cement and 8g of aerogel particles, premix for 10 minutes, spray in 12g of polyvinyl acetate-ethylene emulsion while stirring, roll into granules, cure at room temperature for 24 hours, and dry at 80℃ to constant weight to obtain cement granule balls.

[0039] II. Preparation of premixed paste: S101. Weigh 1g of nanocellulose crystal powder and disperse it in 120g of anhydrous ethanol. Sonicate for 35min to obtain an alcohol dispersion. Weigh 1g of KH-570, 0.8g of POTS and 50g of anhydrous ethanol, mix them, adjust the pH to 4.5 with glacial acetic acid, and stir for 20min to obtain a hydrolysate.

[0040] S102. Add 10g of hydrolysate to 60g of alcohol dispersion, react at 70℃ for 6h, and centrifuge and wash the precipitate 3 times to obtain modified nanocellulose.

[0041] S103. Add 1g of modified nanocellulose to 120g of deionized water and stir for 50min. Then add 40g of gypsum powder and mix well to obtain a premixed paste.

[0042] III. Preparation of Modified Facing Paper: S1. Mix 10g of nano titanium dioxide and 10g of micron titanium dioxide to obtain a mixed powder; add 1.2g of KH-550 and 0.8g of POTS to 25g of anhydrous ethanol for dilution, stir for 15min to obtain a mixed solution, and add 10g of the mixed solution to 50g of the mixed powder to obtain a mixture.

[0043] S2. React the mixture at 100℃ for 2 hours, grind and sieve; mix 10g of the ground powder with 120g of water-based acrylic emulsion (composed of 75g of acrylic emulsion and 45g of deionized water), add deionized water to adjust the viscosity to 500mPa·s to obtain the modified slurry.

[0044] S3. The modified slurry is coated on the surface of the base paper of the face paper by roller coating at a speed of 50 m / min and a wet film thickness of 50 μm. After coating, the paper is dried in three stages: 120℃, 150℃, and 120℃, with a total drying time of 5 min, to obtain the modified face paper.

[0045] IV. Preparation of Water-Resistant and Moisture-Proof Paper-Faced Gypsum Board: Mix all the main materials together, add 10g of emulsified silicone oil and 3g of foaming agent, stir for 10 minutes to obtain modified core slurry, pour the modified core slurry onto the lower facing paper, cover with the facing paper, and extrude at 35MPa to form; let the wet board stand for 35 minutes to solidify; preheat at 120℃ for 40 minutes → dry at 150℃ for 60 minutes → buffer at 80℃ for 25 minutes to obtain water-resistant and moisture-proof paper-faced gypsum board.

[0046] Comparative Example 1: Comparative Example 1 differs from Example 1 in that no premix paste was added, and the remaining steps were exactly the same as in Example 1.

[0047] Comparative Example 2: Comparative Example 2 differs from Example 1 in that the modified core slurry is replaced with gypsum slurry (composed of gypsum clinker, water, and additives), while the remaining steps are exactly the same as in Example 1.

[0048] Comparative Example 3: Comparative Example 3 differs from Example 1 in that the modified face paper is replaced with the face paper base paper (A 890-W type), and the remaining steps are exactly the same as in Example 1.

[0049] Three test boards with dimensions of 300mm×300mm were cut from the water-resistant and moisture-proof paper-faced gypsum boards prepared in Examples 1-3 and Comparative Examples 1-3, respectively, for water absorption rate, surface water absorption and flexural strength tests. Two test boards with dimensions of 400mm×400mm were also cut for water-resistant bonding strength tests. All test boards were conditioned for 24 hours at a temperature of (23±2)℃ and a relative humidity of (50±10)% before use.

[0050] I. Core water absorption rate: Referring to GB / T9775-2008 (Determination of water absorption rate of water-resistant paper-faced gypsum board), the adjusted 300mm×300mm test board was weighed, and its mass was recorded as follows. Immerse the test plate vertically in distilled water at (20±2)℃, to a depth of 2 / 3 of the plate's height, for 2 hours. After immersion, remove the plate, absorb any excess water with a damp cloth, and weigh it immediately. Calculate the water absorption rate using the formula: II. Surface water absorption: Referring to GB / T9775-2008 (Determination of surface water absorption of paper-faced gypsum board), a circular area with a diameter of 100 mm was enclosed on the upper surface of the test board (on the modified facing paper side) using sealing tape. Distilled water at (20±2)℃ was injected into the area to a depth of 5 mm. After standing for 2 hours, the remaining water was removed, and the surface residual water was immediately gently blotted dry with filter paper. The mass difference of the circular area before and after immersion was measured and then divided by the area of ​​the circle to obtain the surface water absorption (g / m²). 2 Each test plate was tested at 3 different locations, and the average value was taken.

[0051] III. Flexural Strength: Referring to Clause 5.4 (Determination of Flexural Strength) of GB / T9775-2008, the test board was cut into strips of 300mm × 50mm. Five strips were taken from each board, with a span of 200mm. The loading speed was 10mm / min, and the failure load P (N) was recorded. The dry flexural strength was calculated according to the formula: in The span is in mm. The width of the test strip is (mm). The thickness of the test strip is in mm. Flexural strength after immersion in water: Take another 300mm×50mm test strip, immerse it in water for 2 hours, and immediately conduct a wet flexural strength test under the same conditions.

[0052] IV. Bonding strength between the facing paper and the core material: Referring to GB / T9775-2008 (Determination of Adhesion Performance of Paper-faced Gypsum Board) and the requirements for water resistance test, a 400mm×400mm test board was vertically immersed in water at (20±2)℃ for 24h (full immersion). After removal, a 50mm long opening was cut along the interface between the facing paper and the core material with a blade at a distance of 50mm from the edge. The peeled facing paper was clamped with the clamp of a tensile tester (or universal testing machine) at a 90° angle to the board surface and stretched at a speed of 50mm / min. The average peel force F (N) was recorded. Calculate the bond strength using the formula: in The peel width is in mm.

[0053] The test results obtained from the tests of core water absorption rate, surface water absorption, flexural strength, and bonding strength between the facing paper and the core material are shown in Table 1 below: Table 1: Performance Test Table for Water-Resistant and Moisture-Proof Paper-Faced Gypsum Board As can be seen from the data in Table 1, the water-resistant and moisture-proof paper-faced gypsum boards in Examples 1-3 are comprehensively superior to the comparative examples without corresponding modification measures in key performance indicators such as water absorption rate, surface water absorption, dry / wet flexural strength, and bond strength. This verifies the effectiveness and advancement of the technical solution. Example 2 is the optimal implementation scheme, with balanced performance and all indicators reaching optimal levels. It can be used as the preferred ratio and process parameter combination. The premixed paste (modified nanocellulose) plays an irreplaceable role in the hydrophobic modification of the board core, mechanical reinforcement, and board-paper interface bonding. The modified facing paper forms the first physical barrier against external moisture intrusion. Components such as cement granule balls (aerogel-coated) and emulsified silicone oil further enhance the hydrophobic structure and lightweight thermal insulation performance inside the core. The three work together to construct a water-resistant and moisture-proof system of "surface shielding - internal hydrophobicity - interface toughness". The poor results of Comparative Examples 2 and 3 (especially the serious excess of surface water absorption in Comparative Example 3) also confirm from the opposite perspective that the modification of the core material and the modification of the facing paper are indispensable. The absence of either one will lead to a significant deterioration of the overall water-resistant and moisture-proof performance.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water-resistant and moisture-proof paper-faced gypsum board, characterized in that, It includes two layers of modified facing paper and the gypsum board core material between the two layers of modified facing paper; The gypsum board core material is composed of modified core slurry, and the raw materials of the modified core slurry include, by weight parts: 100 parts gypsum clinker, 60-80 parts water, 8-15 parts cement granules, 5-10 parts premixed paste, 1-3 parts alkali-free glass fiber, 0.8-2 parts hydrophobic / hydrophilic mixed starch, 0.3-0.8 parts hydroxypropyl methylcellulose, 0.1-0.4 parts accelerator, 0.1-0.2 parts silicone oil catalyst, 0.05-0.15 parts mildew inhibitor, 0.2-0.6 parts water-reducing agent, 0.3-0.7 parts crystal form modifier, 0.5-1.2 parts lime; The modified core slurry is prepared through the following steps: Gypsum clinker, water, cement granules, premixed paste, alkali-free glass fiber, hydrophobic / hydrophilic mixed starch, hydroxypropyl methylcellulose, setting accelerator, silicone oil catalyst, mildew inhibitor, water-reducing agent, crystal form modifier, and lime are mixed together. At the same time, 0.4-1 parts of emulsified silicone oil and 0.1-0.3 parts of foaming agent are added together and stirred for 5-10 minutes to obtain modified core slurry. The modified face paper is prepared through the following steps: S1. Mix nano-titanium dioxide and micron-sized titanium dioxide to obtain a mixed powder; mix KH-550 and POTS, add anhydrous ethanol for dilution, stir at room temperature for 10-15 minutes to obtain a mixed solution, add the mixed solution dropwise to the mixed powder, stir and mix to obtain a mixture; S2. React the mixture at 80-100℃ for 1-2 hours. After the reaction is complete, grind and sieve to obtain ground powder. Mix the ground powder with water-based acrylic emulsion and add deionized water to adjust the coating viscosity to 300-500 mPa·s to obtain modified slurry. S3. Apply the modified slurry to the surface of the base paper of the face paper using a roller coating method. The coating speed is controlled at 30-50m / min, and the wet film thickness of the coating is controlled at 30-50μm. After coating, perform three-stage drying: stage 100-120℃, stage 2 130-150℃, and stage 3 100-110℃ for cooling and shaping. The total drying time is 2-5min, and the modified face paper is obtained.

2. The water-resistant and moisture-proof paper-faced gypsum board according to claim 1, characterized in that, The cement granule balls are prepared by the following steps: Silicate cement and aerogel particles are premixed for 5-10 minutes, and then polyvinyl acetate-ethylene emulsion is sprayed in while stirring. After the mixture is finished, it is rolled into granules to obtain granules. The granules are then cured at room temperature for 20-24 hours and then dried at 60-80℃ to constant weight to obtain cement granules. The premix paste is prepared through the following steps: S101. Disperse the nanocellulose crystal powder in anhydrous ethanol and sonicate for 30-35 min to obtain a uniform ethanol dispersion; mix KH-570 and POTS, add to anhydrous ethanol, adjust the pH to 4.0-4.5 with glacial acetic acid, and stir at room temperature for 15-20 min to obtain a hydrolysate. S102. Add the hydrolysate to the alcohol dispersion and stir the reaction at 60-70℃ for 4-6 hours. After the reaction is complete, centrifuge to collect the precipitate and wash the precipitate 2-3 times each with anhydrous ethanol and deionized water to obtain modified nanocellulose. S103. Mix modified nanocellulose with deionized water, stir for 30-50 minutes, then add gypsum powder and mix to form a premixed paste.

3. The water-resistant and moisture-proof paper-faced gypsum board according to claim 1, characterized in that, In step S1, the mass ratio of nano titanium dioxide, micron titanium dioxide, KH-550, POTS, and anhydrous ethanol is 10:(5-10):(0.5-1.2):(0.3-0.8):(20-25), and the mass ratio of the mixed liquid to the mixed powder is 1:(3-5).

4. The water-resistant and moisture-proof paper-faced gypsum board according to claim 1, characterized in that, In step S2, the mass ratio of the ground powder to the aqueous acrylic emulsion is 1:(8-12), wherein the aqueous acrylic emulsion is composed of an acrylic emulsion and deionized water in a mass ratio of 1:(0.3-0.6).

5. The water-resistant and moisture-proof paper-faced gypsum board according to claim 2, characterized in that, In the preparation step of the cement granules, the mass ratio of silicate cement, aerogel particles, and polyvinyl acetate-ethylene emulsion is 100:(3-8):(5-12).

6. The water-resistant and moisture-proof paper-faced gypsum board according to claim 2, characterized in that, In step S101, the mass ratio of nanocellulose crystal powder to anhydrous ethanol is 1:(80-120), and the mass ratio of KH-570, POTS, and anhydrous ethanol is 1:(0.4-0.8):(30-50).

7. The water-resistant and moisture-proof paper-faced gypsum board according to claim 2, characterized in that, In step S102, the mass ratio of hydrolysate to alcohol dispersion is 1:(4-6).

8. The water-resistant and moisture-proof paper-faced gypsum board according to claim 2, characterized in that, In step S103, the mass ratio of modified nanocellulose, deionized water, and gypsum powder is 1:(80-120):(20-40).

9. A preparation process for preparing the water-resistant and moisture-proof paper-faced gypsum board according to any one of claims 1-8, characterized in that, The preparation process includes the following steps: S201, Prepare modified core slurry; S202. The modified core slurry is poured onto the upper surface of the lower facing paper. After leveling, the upper facing paper is covered on top and extruded at 30-35MPa. The molded gypsum board is left to stand for 30-35 minutes to complete the setting. After setting, it is dried in sections. It is preheated at 110-120℃ for 30-40 minutes, then dried at 140-150℃ for 40-60 minutes, and finally buffered at 60-80℃ for 15-25 minutes. After drying, the water-resistant and moisture-proof paper-faced gypsum board is obtained.

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