Anti-stripping and anti-deformation lamp box fabric and preparation method thereof

Abstract

The invention discloses an anti-stripping and anti-deformation lamp box fabric and a preparation method thereof, and belongs to the technical field of layered products, the preparation method comprises the following steps: pre-activating a base fabric, depositing a calcium silicate nanocrystalline layer, preparing a nano reinforced phase, preparing a dynamic cross-linked PVC composite material, and performing composite molding. The method for depositing the calcium silicate nanocrystalline layer comprises the following steps: immersing pre-activated base cloth into a silane coupling agent solution, adjusting the pH value of the solution to be 8-9, treating at 55-65 DEG C for 28-32 minutes, taking out and drying, immersing the base cloth into a calcium salt solution, adjusting the pH value of the solution to be 8.5-9, reacting at 30-35 DEG C for 5-6 hours, generating calcium silicate nanocrystalline on the surface of the base cloth in situ, and drying to obtain the calcium silicate nanocrystalline layer. Deposition base cloth is obtained; the lamp box fabric prepared by the invention has stripping resistance, creep resistance and thermal stability, and can meet the strict requirements of outdoor high-durability scenes on stripping resistance, deformation resistance and high-temperature stability of materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of laminated products, and particularly relates to a peel-resistant and deformation-resistant light box cloth and a preparation method thereof. Background Art

[0002] With the rapid development of the outdoor advertising, building curtain wall and decoration industries, as the core substrate, the requirements for the peel resistance, dimensional stability and weather resistance of light box cloth are increasing day by day. Traditional light box cloth mostly adopts the structure of polyvinyl chloride (PVC) coated polyester fiber base cloth, but there are problems such as insufficient interfacial bonding force and deformation caused by the mismatch of thermal expansion coefficients. Especially in the outdoor environment with high temperature for a long time, the thermal stress between the organic layer and the inorganic base cloth is easy to cause delamination and peeling. At the same time, the rigid characteristics of the light box cloth are difficult to adapt to dynamic mechanical loads, resulting in embrittlement and shedding of the polyvinyl chloride layer. In addition, during the use of the light box cloth, it usually bears tensile stress and shows creep characteristics, which may lead to the deterioration of structural performance and even material failure in severe cases. This creep will gradually damage the bearing capacity and other mechanical properties of the structure over time, especially under high temperature and high load conditions, and the creep caused by viscoelastic deformation is more obvious.

[0003] Traditional light box cloth mostly adopts the composite structure of polyester fiber base cloth and polyvinyl chloride (PVC) coating. The interfacial bonding between the polyester fiber base cloth and the organic coating mainly relies on physical adsorption or simple chemical treatment. Due to the high inertness of the fiber surface and the insufficient density of active functional groups, it is difficult to form a stable bonding force with the polyvinyl chloride layer. Even if alkali liquor roughening treatment is adopted, there are still limitations in the etching uniformity and the controllability of the surface micro-nano structure, resulting in limited improvement in the adhesion of the polyvinyl chloride layer. In addition, in the prior art, the strength performance of the light box cloth is increased by adding fillers, but this method is prone to form stress concentration points at the interface due to the poor compatibility between the inorganic material and the organic matrix, so its strengthening effect is limited.

[0004] Aiming at the significant problems in the prior art such as poor peel resistance, low breaking strength, poor high-temperature performance and creep deformation, it is urgent to develop a light box cloth with peel resistance, creep resistance and thermal stability to meet the strict requirements for material peel resistance, deformation resistance and high-temperature stability in outdoor high-durability scenarios. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a peel-resistant and deformation-resistant light box cloth and a preparation method thereof. The prepared light box cloth has high peel strength and breaking strength, improves the peel resistance and breaking strength, has good creep resistance, and maintains good peel resistance, breaking strength and creep resistance at high temperatures.

[0006] To solve the above technical problems, the technical solutions adopted by the present invention are as follows: A preparation method of an anti-peeling and anti-deformation light box cloth, comprising the following steps: pre-activating the base cloth, depositing a calcium silicate nanocrystal layer, preparing a nano-reinforcing phase, preparing a dynamically crosslinked PVC composite material, and composite molding; The method for pre-activating the base cloth is to degrease and roughen the base cloth to increase the surface active sites, thereby obtaining a pre-activated base cloth; The base cloth is a mesh cloth composed of high-strength polyester filament yarns and has a bi-axial warp knitted fabric structure to provide good tensile strength and tear resistance; The thickness of the base cloth is 30-40 filaments, and the porosity is 25-30%; The method for roughening treatment is to treat with a 4-5% sodium hydroxide solution at 40-50 °C for 8-12 minutes, and then wash with water and dry.

[0007] The method for depositing the calcium silicate nanocrystal layer is to immerse the pre-activated base cloth in a silane coupling agent solution, then adjust the pH of the solution to 8-9, treat at 55-65 °C for 28-32 minutes, take it out and dry, then immerse the base cloth in a calcium salt solution, adjust the pH of the solution to 8.5-9, react at 30-35 °C for 5-6 hours to in-situ generate calcium silicate nanocrystals on the surface of the base cloth, and dry at 50-60 °C for 15-20 minutes to obtain a deposited base cloth; The silane coupling agent solution is prepared by dissolving silane coupling agent KH-560 in water, and the concentration of silane coupling agent KH-560 in the solution is 0.5-1 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 0.8-1.2 wt%, the concentration of sodium silicate is 0.5-0.7 wt%, the concentration of sodium polyacrylate is 0.1-0.2 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 0.6-1 wt%.

[0008] The method for preparing the nano-reinforcing phase is to disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux and react at 65-70 °C for 3-4 hours to introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO2; mix isocyanate polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO2, react at 90-110 °C for 2-3 hours, filter, wash and dry to obtain the nano-reinforcing phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:10-15:0.2-0.3; The mass ratio of the mercapto-functionalized SiO2 to the isocyanate polyhedral oligomeric silsesquioxane is 1:0.8-1.2; The structural formula of the isocyanate polyhedral oligomeric silsesquioxane is [(N=C=O-R’)SiO1.5 8, R’ is a linking group, and R’ is one of ethyl, propyl or phenyl.

[0009] The method for preparing the dynamically crosslinked PVC composite material is as follows: Stir the PVC powder and the titanate coupling agent at a speed of 400 - 600 rpm for 8 - 12 minutes, then add the nano-enhancing phase and dithiodipropionic acid, stir at a speed of 600 - 800 rpm for 20 - 30 minutes, and then melt and blend using a twin-screw extruder at 160 - 170 °C to obtain the dynamically crosslinked PVC composite material; The degree of polymerization of PVC in the PVC powder is 1600 - 1700; The mass ratio of the nano-enhancing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:15 - 20:0.5 - 0.7:0.1 - 0.12; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0010] The method for composite molding is as follows: Press the dynamically crosslinked PVC composite material into a film, and coat a layer of maleic anhydride grafted PVC on its surface to obtain a PVC composite film. Place the deposition base cloth between two layers of PVC composite films, and make the grafted surface of the PVC composite film fit with the deposition base cloth to form a "PVC / deposition base cloth / PVC" sandwich structure. First, pre-press at 150 - 155 °C and 5 - 6 MPa for 5 - 7 minutes, then raise the temperature to 175 - 180 °C and 8 - 10 MPa for hot pressing for 8 - 10 minutes to promote the dynamic crosslinking reaction and interface penetration, so that the PVC composite material melts and penetrates into the calcium silicate nanocrystal layer of the deposition base cloth to form a mechanical interlock structure. After the hot pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.2 - 0.3 mm, and the thickness of the coated maleic anhydride grafted PVC layer is 50 - 70 nm; The grafting rate of the maleic anhydride grafted PVC is 2 - 2.5%.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) For the anti-peeling and anti-deformation light box cloth of the present invention, in the step of depositing the calcium silicate nanocrystal layer, one end of the added KH-560 molecule contains a siloxy group (-OCH3), and after hydrolysis of the siloxy group (-OCH3), it condenses with the hydroxyl groups on the fiber surface to form a covalent bond anchor. The other end contains an epoxy group, which provides an active site for subsequent reactions and a nucleation site for calcium silicate nanocrystals; The ionic liquid 1-ethyl-3-methylimidazolium acetate in the calcium salt solution promotes ion migration through high polarity, accelerates the formation of crystal nuclei, improves the growth rate of calcium silicate nanocrystals, increases the surface roughness of the formed nanocrystal layer, is conducive to the formation of a mechanical interlock between the PVC matrix and the deposition base cloth, and improves the peel strength and anti-creep performance of the material.

[0012] (2) For the anti-peeling and anti-deformation light box cloth of the present invention, in the step of preparing the nano-enhanced phase, the surface hydroxyl groups of nano-SiO₂ undergo a silanization reaction with 3-mercaptopropyltrimethoxysilane to introduce mercapto groups. The isocyanate groups of isocyanate-based polyhedral oligomeric silsesquioxane react with the mercapto groups to form covalent bonds, grafting the cage-shaped silsesquioxane onto the surface of SiO₂. The rigid cage structure of polyhedral oligomeric silsesquioxane and SiO₂ form a "SiO₂-cage-shaped silsesquioxane" composite structure with a three-dimensional network structure. The rigid skeleton of the cage-shaped silsesquioxane and the polar groups (such as -Cl) of the PVC matrix act through van der Waals forces or hydrogen bonds to reduce the agglomeration between nanoparticles and improve the dispersion uniformity in PVC. The high modulus of SiO₂ grafted with cage-shaped silsesquioxane on the surface and the low modulus of the PVC matrix form a hard-soft alternating interface. When the material is subjected to peeling force or tensile force, the crack needs to change direction multiple times, thereby consuming more energy and significantly improving the peeling strength and fracture strength of the material. SiO₂ grafted with cage-shaped silsesquioxane on the surface has good thermal conductivity, which can reduce the mismatch of the thermal expansion coefficient of the PVC matrix, inhibit the interfacial stress concentration caused by temperature changes, improve the tensile strength and fracture strength of the composite material under the thermal field, and improve the creep resistance of the composite material under the thermal field.

[0013] (3) For the anti-peeling and anti-deformation light box cloth of the present invention, in the step of composite molding, a maleic anhydride-grafted PVC surface is laminated and hot-pressed with a deposited base cloth. Under the action of a thermal field at 60°C for 7 days, long-term high temperature will cause the carboxyl group of maleic anhydride to undergo an esterification reaction with the hydroxyl groups present on the surface of the calcium silicate nanocrystal layer to form chemical bonds, which can enhance the peeling strength and fracture strength of the composite material, and can offset most of the reduction in strength performance caused by the reduction in the modulus of the base cloth fibers and the PVC film due to long-term high temperature, resulting in a slight decrease in the peeling strength and fracture strength, and maintaining the peeling strength and fracture strength at a relatively high level.

[0014] (4) For the anti-peeling and anti-deformation light box cloth of the present invention, the peeling strength is 21.7 - 22.5 N, the longitudinal fracture strength is 2014 - 2043 N, and the transverse fracture strength is 1752 - 1775 N. Under the thermal field at 60°C for 7 days, the peeling strength is 21.2 - 21.8 N, the longitudinal fracture strength is 1989 - 2006 N, and the transverse fracture strength is 1734 - 1759 N; under the tension of 15% of the fracture strength, the elongation rate at 0 h reaches more than 95% of the cumulative elongation rate at 500 h, the cumulative elongation rate at 0 h reaches more than 99% of the cumulative elongation rate at 500 h, the cumulative elongation rate at 10 h reaches more than 99% of the cumulative elongation rate at 500 h, and the elongation rate from 100 h to 500 h no longer increases; under the thermal field at 60°C for 10 h, the longitudinal elongation rate of the light box cloth is 2.12 - 2.17%, and the transverse elongation rate is 4.79 - 4.91%. Detailed implementation mode

[0015] To have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention will now be described.

[0016] Example 1 A preparation method of an anti-peeling and anti-deformation light box cloth includes the following steps: (1) Substrate pre-activation The substrate with a thickness of 30 filaments and a porosity of 25% is degreased and roughened to increase the surface active sites, obtaining a pre-activated substrate; The substrate is a grid cloth composed of high-strength polyester filament yarns, having a bi-axial warp knitted fabric structure, with a warp and weft density of 47×47 per 10 cm, to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with a 4% sodium hydroxide solution at 40°C for 12 minutes, then wash with water and dry.

[0017] (2) Deposition of calcium silicate nanocrystal layer The pre-activated substrate is immersed in a silane coupling agent solution, then the pH of the solution is adjusted to 8, and it is treated at 55°C for 32 minutes. After taking it out and drying, the substrate is immersed in a calcium salt solution, and then the pH of the solution is adjusted to 8.5, and it reacts at 30°C for 6 hours to in-situ generate calcium silicate nanocrystals on the surface of the substrate. After drying at 50°C for 20 minutes, a deposited substrate is obtained; The silane coupling agent solution is prepared by dissolving silane coupling agent KH-560 in water, and the concentration of silane coupling agent KH-560 in the solution is 0.5 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate, and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 0.8 wt%, the concentration of sodium silicate is 0.5 wt%, the concentration of sodium polyacrylate is 0.1 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 0.6 wt%.

[0018] (3) Preparation of nano-reinforcing phase Nano-SiO2 is dispersed in ethyl acetate, 3-mercaptopropyltrimethoxysilane is added, and it is refluxed and reacted at 65°C for 4 hours to introduce mercapto groups through a silanization reaction, obtaining mercapto-functionalized SiO2; Isocyanate polyhedral oligomeric silsesquioxane and mercapto-functionalized SiO2 are mixed and reacted at 90°C for 3 hours, filtered, washed, and dried to obtain a nano-reinforcing phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:10:0.2; The mass ratio of the mercapto-functionalized SiO2 and isocyanate polyhedral oligomeric silsesquioxane is 1:0.8; The structural formula of the isocyanate group polyhedral oligomeric silsesquioxane is [(N=C=O-CH2CH3)SiO 1.5 8.

[0019] (4)Preparation of dynamically crosslinked PVC composite material Mix the PVC powder with a polymerization degree of 1600 and a titanate coupling agent at a rotation speed of 400 rpm for 12 minutes, then add the nano-reinforcing phase and dithiodipropionic acid, stir at a rotation speed of 600 rpm for 30 minutes, and then melt and blend using a twin-screw extruder at 160 °C to obtain a dynamically crosslinked PVC composite material; The mass ratio of the nano-reinforcing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:15:0.5:0.1; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0020] (5)Composite molding Press the dynamically crosslinked PVC composite material into a film, and coat a layer of maleic anhydride-grafted PVC on its surface to obtain a PVC composite film. Place the deposition substrate between two layers of PVC composite films, and bond the grafted surface of the PVC composite film to the deposition substrate to form a "PVC / deposition substrate / PVC" sandwich structure. First, pre-press at 150 °C and 5 MPa for 7 minutes, then raise the temperature to 175 °C and 8 MPa and hot-press for 10 minutes to promote the dynamic crosslinking reaction and interface penetration, melt the PVC composite material and penetrate it into the calcium silicate nanocrystal layer of the deposition substrate to form a mechanical interlocking structure. After the hot-pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.2 mm, and the thickness of the coated maleic anhydride-grafted PVC layer is 50 nm; The grafting rate of the maleic anhydride-grafted PVC is 2%.

[0021] Example 2 A preparation method of an anti-peeling and anti-deformation light box cloth includes the following steps: (1)Pre-activation of the substrate Degrease and roughen the substrate with a thickness of 35 filaments and a porosity of 28% to increase the surface active sites and obtain a pre-activated substrate; The substrate is a grid cloth composed of high-strength polyester filament yarns, with a bi-axial warp knitted fabric structure, and the warp and weft yarn densities are 47×47 pieces / 10 cm to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with a 4.5% sodium hydroxide solution at 45 °C for 10 minutes, then wash with water and dry.

[0022] (2)Deposition of calcium silicate nanocrystal layer The pre-activated base fabric is immersed in a silane coupling agent solution, and then the pH of the solution is adjusted to 8.5. It is treated at 58 °C for 30 minutes, taken out and dried. Then the base fabric is immersed in a calcium salt solution, and the pH of the solution is adjusted to 8.8. It reacts at 32 °C for 5.5 hours to in-situ generate calcium silicate nanocrystals on the surface of the base fabric. After drying at 55 °C for 18 minutes, a deposited base fabric is obtained; The silane coupling agent solution is prepared by dissolving silane coupling agent KH-560 in water, and the concentration of silane coupling agent KH-560 in the solution is 0.8 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 1 wt%, the concentration of sodium silicate is 0.6 wt%, the concentration of sodium polyacrylate is 0.15 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 0.8 wt%.

[0023] (3)Preparation of nano-reinforcing phase Disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux and react at 68 °C for 3.5 hours to introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO2; mix isocyanate polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO2 and react at 100 °C for 2.5 hours, filter, wash and dry to obtain a nano-reinforcing phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:12:0.25; The mass ratio of the mercapto-functionalized SiO2 to the isocyanate polyhedral oligomeric silsesquioxane is 1:1; The structural formula of the isocyanate polyhedral oligomeric silsesquioxane is [(N=C=O-CH2CH2CH3)SiO 1.5 8.

[0024] (4)Preparation of dynamically crosslinked PVC composite Stir the PVC powder with a polymerization degree of 1650 and a titanate coupling agent at a speed of 500 rpm for 10 minutes, then add the nano-reinforcing phase and dithiodipropionic acid, and stir at a speed of 700 rpm for 25 minutes. Then, melt and blend using a twin-screw extruder at 165 °C to obtain a dynamically crosslinked PVC composite; The mass ratio of the nano-reinforcing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:18:0.6:0.11; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0025] (5)Composite molding The dynamic cross-linked PVC composite material is pressed into a film, and a layer of maleic anhydride grafted PVC is coated on its surface to obtain a PVC composite film. The deposition substrate is arranged between two layers of PVC composite films, and the grafted surface of the PVC composite film is adhered to the deposition substrate to form a "PVC / deposition substrate / PVC" sandwich structure. First, it is pre-pressed at 152 °C and 5.5 MPa for 6 minutes, and then heated to 178 °C and hot-pressed at 9 MPa for 9 minutes to promote the dynamic cross-linking reaction and interface penetration, so that the PVC composite material melts and penetrates into the calcium silicate nanocrystal layer of the deposition substrate to form a mechanical interlocking structure. After the hot pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.25 mm, and the thickness of the coated maleic anhydride grafted PVC layer is 60 nm; The grafting rate of the maleic anhydride grafted PVC is 2.3%.

[0026] Example 3 A preparation method of an anti-peeling and anti-deformation light box cloth includes the following steps: (1) Substrate pre-activation The substrate with a thickness of 40 filaments and a porosity of 30% is degreased and roughened to increase the surface active sites to obtain a pre-activated substrate; The substrate is a grid cloth composed of high-strength polyester filament yarns, with a bi-axial warp knitted fabric structure, and the warp and weft yarn densities are 47×47 per 10 cm to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with 5% sodium hydroxide solution at 50 °C for 8 minutes, and then wash with water and dry.

[0027] (2) Deposition of calcium silicate nanocrystal layer The pre-activated substrate is immersed in a silane coupling agent solution, and then the pH of the solution is adjusted to 9, and treated at 65 °C for 28 minutes. After taking it out and drying, the substrate is immersed in a calcium salt solution, and then the pH of the solution is adjusted to 9, and reacted at 35 °C for 5 hours to in-situ generate calcium silicate nanocrystals on the surface of the substrate. After drying at 60 °C for 15 minutes, the deposited substrate is obtained; The silane coupling agent solution is prepared by dissolving silane coupling agent KH-560 in water, and the concentration of silane coupling agent KH-560 in the solution is 1 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 1.2 wt%, the concentration of sodium silicate is 0.7 wt%, the concentration of sodium polyacrylate is 0.2 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 1 wt%.

[0028] (3)Preparation of nano-reinforcing phase Disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux at 70 °C for 3 hours to introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO2; mix isocyanate polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO2, react at 110 °C for 2 hours, filter, wash, and dry to obtain a nano-reinforcing phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:15:0.3; The mass ratio of the mercapto-functionalized SiO2 and isocyanate polyhedral oligomeric silsesquioxane is 1:1.2; The structural formula of the isocyanate polyhedral oligomeric silsesquioxane is [(N=C=O-C6H4)SiO 1.5 8.

[0029] (4)Prepare a dynamically crosslinked PVC composite material Stir the PVC powder with a polymerization degree of 1700 and a titanate coupling agent at a speed of 600 rpm for 8 minutes, then add the nano-reinforcing phase and dithiodipropionic acid, stir at a speed of 800 rpm for 20 minutes, and then melt-blend using a twin-screw extruder at 170 °C to obtain a dynamically crosslinked PVC composite material; The mass ratio of the nano-reinforcing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:20:0.7:0.12; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0030] (5)Composite molding Press the dynamically crosslinked PVC composite material into a film, and coat a layer of maleic anhydride-grafted PVC on its surface to obtain a PVC composite film. Place the deposition base cloth between two layers of PVC composite films, and bond the grafted surface of the PVC composite film to the deposition base cloth to form a "PVC / deposition base cloth / PVC" sandwich structure. First, pre-press at 155 °C and 6 MPa for 5 minutes, then raise the temperature to 180 °C and 10 MPa and hot-press for 8 minutes to promote the dynamic crosslinking reaction and interface penetration, melt the PVC composite material and penetrate it into the calcium silicate nanocrystal layer of the deposition base cloth to form a mechanical interlocking structure. After the hot-pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.3 mm, and the thickness of the coated maleic anhydride-grafted PVC layer is 70 nm; The grafting rate of the maleic anhydride-grafted PVC is 2.5%.

[0031] Example 4 A preparation method of an anti-peeling and anti-deformation light box cloth includes the following steps: (1)Pre-activation of the base cloth The base fabric with a thickness of 35 filaments and a porosity of 28% is degreased and roughened to increase the surface active sites, obtaining a pre-activated base fabric; The base fabric is a mesh fabric composed of high-strength polyester filament yarns, with a bi-axial warp knitted fabric structure, and the warp and weft yarn densities are 47×47 per 10 cm, to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with a 4.5% sodium hydroxide solution at 45 °C for 10 minutes, and then wash with water and dry.

[0032] (2)Prepare the nano-enhanced phase Disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux and react at 68 °C for 3.5 hours. Introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO2; Mix isocyanate-functionalized polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO2, and react at 100 °C for 2.5 hours, filter, wash, and dry to obtain the nano-enhanced phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:12:0.25; The mass ratio of the mercapto-functionalized SiO2 and isocyanate-functionalized polyhedral oligomeric silsesquioxane is 1:1; The structural formula of the isocyanate-functionalized polyhedral oligomeric silsesquioxane is [(N=C=O-CH2CH2CH3)SiO 1.5 8.

[0033] (3)Prepare the dynamically crosslinked PVC composite Stir the PVC powder with a polymerization degree of 1650 and a titanate coupling agent at a speed of 500 rpm for 10 minutes, then add the nano-enhanced phase and dithiodipropionic acid, stir at a speed of 700 rpm for 25 minutes, and then melt and blend using a twin-screw extruder at 165 °C to obtain the dynamically crosslinked PVC composite; The mass ratio of the nano-enhanced phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:18:0.6:0.11; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0034] (4)Composite molding The dynamic cross-linked PVC composite material is pressed into a film, and a layer of maleic anhydride grafted PVC is coated on its surface to obtain a PVC composite film. The pre-activated substrate is arranged between two layers of PVC composite films, and the grafted surface of the PVC composite film is bonded to the pre-activated substrate to form a "PVC / pre-activated substrate / PVC" sandwich structure. First, it is pre-pressed at 152 °C and 5.5 MPa for 6 minutes, and then heated to 178 °C and hot-pressed at 9 MPa for 9 minutes to promote the dynamic cross-linking reaction and interfacial penetration, so that the PVC composite material melts and penetrates into the interior of the pre-activated substrate. After the hot pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.25 mm, and the thickness of the coated maleic anhydride grafted PVC layer is 60 nm; The grafting rate of the maleic anhydride grafted PVC is 2.3%.

[0035] Example 5 A preparation method of an anti-peeling and anti-deformation light box cloth includes the following steps: (1) Substrate pre-activation The substrate with a thickness of 35 deniers and a porosity of 28% is degreased and roughened to increase the surface active sites to obtain a pre-activated substrate; The substrate is a grid cloth composed of high-strength polyester filament yarns, with a bi-axial warp knitted fabric structure, and the warp and weft yarn densities are 47×47 per 10 cm to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with a 4.5% sodium hydroxide solution at 45 °C for 10 minutes, and then wash with water and dry.

[0036] (2) Depositing a calcium silicate nanocrystal layer The pre-activated substrate is immersed in a silane coupling agent solution, and then the pH of the solution is adjusted to 8.5 and treated at 58 °C for 30 minutes. After taking it out and drying, the substrate is immersed in a calcium salt solution, and then the pH of the solution is adjusted to 8.8 and reacted at 32 °C for 5.5 hours to in-situ generate calcium silicate nanocrystals on the surface of the substrate. After drying at 55 °C for 18 minutes, a deposited substrate is obtained; The silane coupling agent solution is prepared by dissolving the silane coupling agent KH-560 in water, and the concentration of the silane coupling agent KH-560 in the solution is 0.8 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, and sodium polyacrylate in water. The concentration of calcium chloride in the calcium salt solution is 1 wt%, the concentration of sodium silicate is 0.6 wt%, and the concentration of sodium polyacrylate is 0.15 wt%.

[0037] (3)Preparation of nano-reinforcing phase Disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux at 68 °C for 3.5 hours. Introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO2; mix isocyanate-functionalized polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO2 and react at 100 °C for 2.5 hours. Filter, wash, and dry to obtain a nano-reinforcing phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:12:0.25; The mass ratio of the mercapto-functionalized SiO2 and isocyanate-functionalized polyhedral oligomeric silsesquioxane is 1:1; The structural formula of the isocyanate-functionalized polyhedral oligomeric silsesquioxane is [(N=C=O-CH2CH2CH3)SiO 1.5 8.

[0038] (4) Prepare a dynamically crosslinked PVC composite Stir the PVC powder with a polymerization degree of 1650 and a titanate coupling agent at 500 rpm for 10 minutes, then add the nano-reinforcing phase and dithiodipropionic acid, and stir at 700 rpm for 25 minutes. Then, melt and blend using a twin-screw extruder at 165 °C to obtain a dynamically crosslinked PVC composite; The mass ratio of the nano-reinforcing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:18:0.6:0.11; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0039] (5) Composite molding Press the dynamically crosslinked PVC composite into a film, and coat a layer of maleic anhydride-grafted PVC on its surface to obtain a PVC composite film. Place the deposition substrate between two layers of PVC composite films, and bond the grafted surface of the PVC composite film to the deposition substrate to form a "PVC / deposition substrate / PVC" sandwich structure. First, pre-press at 152 °C and 5.5 MPa for 6 minutes, then raise the temperature to 178 °C and 9 MPa and hot-press for 9 minutes to promote the dynamic crosslinking reaction and interfacial penetration, melt the PVC composite and penetrate it into the calcium silicate nanocrystal layer of the deposition substrate to form a mechanical interlocking structure. After the hot-pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.25 mm, and the thickness of the coated maleic anhydride-grafted PVC layer is 60 nm; The grafting rate of the maleic anhydride-grafted PVC is 2.3%.

[0040] Example 6 A method for preparing an anti-peeling and anti-deformation light box cloth includes the following steps: (1) Substrate pre-activation The base fabric with a thickness of 35 filaments and a porosity of 28% is degreased and roughened to increase the surface active sites, obtaining a pre-activated base fabric; The base fabric is a grid fabric composed of high-strength polyester filament yarns, having a bi-axial warp knitted fabric structure, with warp and weft yarn densities of 47×47 per 10 cm, to provide good tensile strength and tear resistance; The method of the roughening treatment is to treat with a 4.5% sodium hydroxide solution at 45 °C for 10 minutes, then wash with water and dry.

[0041] (2)Depositing a calcium silicate nanocrystal layer The pre-activated base fabric is immersed in a silane coupling agent solution, then the pH of the solution is adjusted to 8.5, and treated at 58 °C for 30 minutes. After taking it out and drying, the base fabric is immersed in a calcium salt solution, and then the pH of the solution is adjusted to 8.8, and reacted at 32 °C for 5.5 hours to in-situ generate calcium silicate nanocrystals on the surface of the base fabric. After drying at 55 °C for 18 minutes, a deposited base fabric is obtained; The silane coupling agent solution is prepared by dissolving silane coupling agent KH-560 in water, and the concentration of silane coupling agent KH-560 in the solution is 0.8 wt%; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 1 wt%, the concentration of sodium silicate is 0.6 wt%, the concentration of sodium polyacrylate is 0.15 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 0.8 wt%.

[0042] (3)Preparing a nano-enhanced phase Disperse nano-SiO2 in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux and react at 68 °C for 3.5 hours to obtain a nano-enhanced phase; The mass ratio of the nano-SiO2, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:12:0.25.

[0043] (4)Preparing a dynamically crosslinked PVC composite Stir the PVC powder with a polymerization degree of 1650 and a titanate coupling agent at a rotation speed of 500 rpm for 10 minutes, then add the nano-enhanced phase and dithiodipropionic acid, and stir at a rotation speed of 700 rpm for 25 minutes, and then melt and blend using a twin-screw extruder at 165 °C to obtain a dynamically crosslinked PVC composite; The mass ratio of the nano-enhanced phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:18:0.6:0.11; The titanate coupling agent is isopropyl triisostearoyl titanate.

[0044] (5)Composite molding The dynamic cross-linked PVC composite material is pressed into a film, and a layer of maleic anhydride grafted PVC is coated on its surface to obtain a PVC composite film. The deposition base cloth is placed between two layers of PVC composite films, and the grafted surface of the PVC composite film is adhered to the deposition base cloth to form a "PVC / deposition base cloth / PVC" sandwich structure. First, it is pre-pressed at 152 °C and 5.5 MPa for 6 minutes, and then heated to 178 °C and hot-pressed at 9 MPa for 9 minutes to promote the dynamic cross-linking reaction and interfacial penetration, so that the PVC composite material melts and penetrates into the calcium silicate nanocrystal layer of the deposition base cloth to form a mechanical interlocking structure. After the hot pressing is completed, the product light box cloth is obtained; The thickness of the PVC composite film is 0.25 mm, and the thickness of the coated maleic anhydride grafted PVC layer is 60 nm; The grafting rate of the maleic anhydride grafted PVC is 2.3%.

[0045] Test Example 1 The peel strength, tensile properties, peel strength and tensile properties in the thermal field of the light box cloth prepared in Examples 1-6 were tested, and the test results are shown in Tables 1-2.

[0046] The test method for the peel strength is to conduct a peel test on the light box cloth with reference to the standard FZ / T 01010-2012. The width of the specimen is 25 mm, the length is 220 mm, it is pre-peeled by 50 mm first, the peel length is 100 mm, the clamping gauge is 30 mm, and the tensile speed is 100 mm / min; each group of specimens is subjected to 3 effective tests, and the average value is taken as the peel strength of the light box cloth.

[0047] The test method for the tensile properties is to conduct a tensile test on the light box cloth with reference to the standard GB / T 3923.1-2013. The length of the specimen is 300 mm, the width is 50 mm, the clamping distance is 200 mm, and the tensile speed is 100 mm / min; each group of specimens is tested 10 times longitudinally and transversely, and the average value is taken and the breaking strength is recorded.

[0048] For the peel strength and tensile properties in the thermal field, the prepared light box cloth is placed at 60 °C for 7 days, and the peel strength and breaking strength are detected.

[0049] Table 1 Strength Performance

[0050] Table 2 Strength Performance under Thermal Field

[0051] As can be seen from Table 1, for the light box cloth prepared in Example 4 where the step of depositing calcium silicate nanocrystal layer is omitted, both the peel strength and the breaking strength decrease, indicating that depositing the calcium silicate nanocrystal layer on the surface of the base cloth can improve the peel strength and breaking strength of the light box cloth; in the step of depositing the calcium silicate nanocrystal layer in Example 5, 1-ethyl-3-methylimidazolium acetate is omitted, and the peel strength of the prepared light box cloth is slightly higher than that of Example 4, but still lower than that of Example 2, indicating that adding 1-ethyl-3-methylimidazolium acetate to the calcium salt solution for forming the deposition layer can improve the peel strength and breaking strength.

[0052] As can be seen from Table 1-2, after the light box cloths prepared in Examples 1-3 are placed at 60 °C for 7 days, only a small performance attenuation occurs in the peel strength and breaking strength. This may be because the carboxyl groups of maleic anhydride grafted PVC on the PVC composite film and the large number of silanol groups (-SiOH) and hydroxyl groups (-OH) on the surface of the calcium silicate nanocrystal layer form ester bonds through slow condensation during long-term contact, and the PVC film and the base cloth form a chemical connection through an esterification reaction, which can effectively inhibit the interfacial slip during the peeling process, and the generated chemical bonding force can offset most of the strength performance reduction caused by the decrease in the modulus of the base cloth fibers and the PVC film due to long-term high temperature.

[0053] Test Example 2 The creep properties and the creep properties in the thermal field of the light box cloths prepared in Examples 1-6 were tested, and the test results are shown in Tables 3-6.

[0054] The test method for creep properties is as follows: Referring to Standard GB / T17637-1998, the hanging weight method is adopted. Under the standard temperature and humidity environment, the sample is suspended on the creep bracket, and the size of the tension is adjusted by the hook weight connected below. The sample length is measured by the comparison method, and the measurement method of calculating the elongation rate is adopted. The tension is set to 15% of the breaking strength of the yarn and the PVC film material tested under the standard temperature and humidity environment. The time points for recording the creep deformation amount are: 0 h, 10 h, 100 h, 200 h, and 500 h. Each group of specimens is tested 3 times, and the average value is taken. Calculate the elongation rate, and the elongation rate is the percentage of the deformation amount of the light box cloth to the original length.

[0055] For the creep properties in the thermal field, at 60 °C, the tension is set to 15% of the breaking strength of the yarn and the PVC film material tested under the standard temperature and humidity environment, record the creep deformation amount at 10 h of tension, and calculate the elongation rate.

[0056] Table 3 Creep Properties (Longitudinal)

[0057] Table 4 Creep Properties (Transverse)

[0058] Table 5 Creep properties in the thermal field (longitudinal direction)

[0059] Table 6 Creep properties in the thermal field (transverse direction)

[0060] As can be seen from Tables 3 - 4, under the tension of 15% of the breaking strength, the light box fabrics of Examples 1 - 3 mainly showed instantaneous elongation. The elongation rate at 0 h reached more than 95% of the cumulative elongation rate at 500 h, and the cumulative elongation rate at 10 h reached more than 99% of the cumulative elongation rate at 500 h. The tensile length of the light box fabric hardly increased from 100 h to 500 h, the elongation rate no longer increased, and the cumulative elongation rate from 0 h to 500 h was less than 5% of the cumulative elongation rate at 500 h, showing good anti - creep performance.

[0061] Compared with Example 2, the elongation rates of Examples 4 - 6 increased to varying degrees in each time period, and there was still an increasing phenomenon of the elongation rate between 100 h and 500 h. This indicates that depositing calcium silicate nanocrystal layers, adding 1 - ethyl - 3 - methylimidazolium acetate to the calcium salt solution for forming the deposition layer, and adding isocyanate - based polyhedral oligomeric silsesquioxane in the preparation of the nano - reinforcement phase can improve the anti - creep performance of the light box fabric.

[0062] As can be seen from Tables 5 - 6, compared with Example 2, the elongation rates of Examples 4 - 6 in the thermal field all increased to varying degrees. This indicates that depositing calcium silicate nanocrystal layers, adding 1 - ethyl - 3 - methylimidazolium acetate to the calcium salt solution for forming the deposition layer, and adding isocyanate - based polyhedral oligomeric silsesquioxane in the preparation of the nano - reinforcement phase can improve the anti - creep performance of the light box fabric under the thermal field.

[0063] Finally, it should be noted that the above - mentioned are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an anti-peeling and anti-deformation light box cloth, characterized in that, The preparation method includes the following steps: pre-activation of the base fabric, deposition of a calcium silicate nanocrystal layer, preparation of a nano-reinforcing phase, preparation of a dynamically crosslinked PVC composite material, and composite molding; The method for depositing the calcium silicate nanocrystal layer is as follows: Immerse the pre-activated base fabric in a silane coupling agent solution, then adjust the pH of the solution to 8 - 9, treat it at 55 - 65 °C for 28 - 32 minutes, take it out and dry it. Then immerse the base fabric in a calcium salt solution, and adjust the pH of the solution to 8.5 - 9, react at 30 - 35 °C for 5 - 6 hours to in-situ generate calcium silicate nanocrystals on the surface of the base fabric. After drying at 50 - 60 °C for 15 - 20 minutes, a deposited base fabric is obtained; The calcium salt solution is prepared by dissolving calcium chloride, sodium silicate, sodium polyacrylate, and 1-ethyl-3-methylimidazolium acetate in water. The concentration of calcium chloride in the calcium salt solution is 0.8 - 1.2 wt%, the concentration of sodium silicate is 0.5 - 0.7 wt%, the concentration of sodium polyacrylate is 0.1 - 0.2 wt%, and the concentration of 1-ethyl-3-methylimidazolium acetate is 0.6 - 1 wt%.

2. The preparation method of an anti-peeling and anti-deformation light box cloth according to claim 1, wherein, In the step of depositing the calcium silicate nanocrystal layer, the silane coupling agent solution is prepared by dissolving the silane coupling agent KH-560 in water, and the concentration of the silane coupling agent KH-560 in the solution is 0.5 - 1 wt%.

3. The preparation method of an anti-peeling and anti-deformation light box cloth according to claim 1, characterized in that, The method for preparing the nano-reinforcing phase is as follows: Disperse nano-SiO₂ in ethyl acetate, add 3-mercaptopropyltrimethoxysilane, and reflux and react at 65 - 70 °C for 3 - 4 hours to introduce mercapto groups through a silanization reaction to obtain mercapto-functionalized SiO₂; Mix isocyanate polyhedral oligomeric silsesquioxane with mercapto-functionalized SiO₂, react at 90 - 110 °C for 2 - 3 hours, filter, wash, and dry to obtain the nano-reinforcing phase.

4. The preparation method of a peel-resistant and deformation-proof light box cloth according to claim 3, wherein, In the step of preparing the nano-reinforcing phase, The mass ratio of the nano-SiO₂, ethyl acetate, and 3-mercaptopropyltrimethoxysilane is 1:10 - 15:0.2 - 0.3; The mass ratio of the mercapto-functionalized SiO₂ to the isocyanate polyhedral oligomeric silsesquioxane is 1:0.8 - 1.2; The structural formula of the isocyanate group polyhedral oligomeric silsesquioxane is [(N=C=O-R’)SiO 1.5 8, where R’ is a linking group and R’ is one of ethyl, propyl or phenyl.

5. The preparation method of an anti-peeling and anti-deformation light box cloth according to claim 1, characterized in that, The method for preparing the dynamically crosslinked PVC composite material is as follows: Stir the PVC powder and the titanate coupling agent at a rotation speed of 400 - 600 rpm for 8 - 12 minutes, then add the nano-reinforcing phase and dithiodipropionic acid, stir at a rotation speed of 600 - 800 rpm for 20 - 30 minutes, and then melt and blend using a twin-screw extruder at 160 - 170 °C to obtain the dynamically crosslinked PVC composite material.

6. The preparation method of a peel-resistant and deformation-proof light box cloth according to claim 5, characterized in that, In the step of preparing the dynamically crosslinked PVC composite material, The degree of polymerization of PVC in the PVC powder is 1600 - 1700; The mass ratio of the nano-reinforcing phase, PVC powder, dithiodipropionic acid, and titanate coupling agent is 1:15 - 20:0.5 - 0.7:0.1 - 0.12; The titanate coupling agent is isopropyl triisostearoyl titanate.

7. The preparation method of a peel-resistant and deformation-proof light box cloth according to claim 1, characterized in that The method of the composite molding is as follows: press the dynamically crosslinked PVC composite material into a film, and coat a layer of maleic anhydride grafted PVC on its surface to obtain a PVC composite film. Place the deposition substrate between two layers of PVC composite films, and make the grafted surface of the PVC composite film adhere to the deposition substrate to form a "PVC / deposition substrate / PVC" sandwich structure. First, pre-press at 150-155°C and 5-6 MPa for 5-7 minutes, then raise the temperature to 175-180°C and 8-10 MPa for hot pressing for 8-10 minutes to promote the dynamic crosslinking reaction and interface penetration, so that the PVC composite material melts and penetrates into the calcium silicate nanocrystal layer of the deposition substrate to form a mechanical interlocking structure. After the hot pressing is completed, the product light box cloth is obtained.

8. The preparation method of an anti-peeling and anti-deformation light box cloth according to claim 7, characterized in that, In the steps of the composite molding, the thickness of the PVC composite film is 0.2-0.3 mm, and the thickness of the coated maleic anhydride grafted PVC layer is 50-70 nm; the grafting rate of the maleic anhydride grafted PVC is 2-2.5%.

9. The preparation method of an anti-peeling and anti-deformation light box cloth according to claim 1, characterized in that, The method of pre-activating the substrate is to degrease and roughen the substrate to increase the surface active sites to obtain a pre-activated substrate; the substrate is a grid cloth composed of high-strength polyester filament yarns and has a biaxial warp knitted fabric structure; The method of the roughening treatment is to treat with a 4-5% sodium hydroxide solution at 40-50°C for 8-12 minutes, and then wash with water and dry.

10. The anti-peeling and anti-deformation light box cloth prepared by the method according to any one of claims 1-9.

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