A lightweight and tear-resistant PVC light box cloth

Abstract

The present invention discloses a lightweight tear-resistant PVC light box cloth, belonging to the technical field of laminated products. The light box cloth includes a base layer, an intermediate reinforcing layer, and a surface functional layer. The preparation method of the intermediate reinforcing layer includes the following steps: dopamine modification and dipping. The method of dopamine modification is to orthogonally weave aramid fibers and ultra-high molecular weight polyethylene fibers into a grid structure, immerse it in a dopamine solution, oscillate at room temperature for 6-8 hours, take it out and rinse it with water 2-3 times, and vacuum dry it at 60-70 °C for 1-1.5 hours to cure the polydopamine coating formed on the fiber surface, and obtain a fiber network after dopamine modification. The lightweight tear-resistant PVC light box cloth provided by the present invention realizes the mechanical optimization of the tear resistance while ensuring lightweight, improves the tensile strength, elongation at break, trapezoidal tear strength, and interlayer peel strength, and has a high tear strength recovery rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of laminated products, and particularly relates to a lightweight and tear-resistant PVC light box cloth. Background Art

[0002] With the continuous progress of society and the increasing abundance of commodities, the advertising industry has developed rapidly, which has put forward higher requirements for advertising media. The emergence of light box cloth has replaced hard materials such as neon lights, plastic films, and plexiglass that once dominated the advertising media, and has gradually become the preferred material for making light boxes. The advantages of light box cloth are manifested in that the light boxes made are brightly colored, have a long service life, are convenient for transportation, and are safe to use. Translucent instant stickers can be pasted on the light box, and heat transfer printing, super heat printing, computer photo printing, etc. can also be carried out. Moreover, large or extra-large light boxes can be made, with arbitrary shapes of flat or curved surfaces, and the application is relatively wide.

[0003] Traditional light box cloth faces many challenges during outdoor use. On the one hand, its tear resistance is insufficient. In outdoor complex environments, such as strong winds and external force collisions, tearing is likely to occur, even resulting in damage to the light box. When there is a slight tear in the light box cloth, a light-transmitting gap is formed at the tear, affecting the advertising display effect, and the exposed fibers accelerate aging, shortening the overall service life. On the other hand, traditional light box cloth is relatively heavy, which brings inconvenience to transportation and installation, increases the construction cost and difficulty. Moreover, in some large-scale outdoor advertising projects, due to the heavy weight of the light box cloth, more manpower and equipment are required for installation, and problems such as deformation caused by weight are likely to occur during the installation process.

[0004] In the prior art, although attempts have been made to improve the strength by adding calcium carbonate or fibers, problems such as an increase in grammage or poor strength improvement effect will occur, and it is difficult to balance lightweight and tear resistance. Therefore, it is of great practical significance to develop a lightweight PVC light box cloth with excellent tear resistance. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a lightweight and tear-resistant PVC light box cloth, which realizes the mechanical optimization of tear resistance while ensuring lightweight, improves the tensile strength, elongation at break, trapezoidal tear strength, and interlayer peel strength, and has a high tear strength recovery rate.

[0006] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A lightweight and tear-resistant PVC light box cloth, comprising a base layer, an intermediate reinforcing layer, and a surface functional layer;

[0008] The preparation method of the base layer is to mix hollow polyester fibers and chopped carbon fibers, impregnate with PVC emulsion after needle punching molding, and dry at 100 - 120 °C;

[0009] The basis weight of the base layer is 110-130 g / m 2 , and the porosity is 30%-40%;

[0010] The mass ratio of the hollow polyester fiber to the short carbon fiber is 10:1.5-2;

[0011] The length of the short carbon fiber is 3-6 mm.

[0012] The preparation method of the intermediate reinforcing layer includes the following steps: dopamine modification and dipping;

[0013] The method of dopamine modification is as follows: the aramid fiber and the ultra-high molecular weight polyethylene fiber are orthogonally woven into a grid structure, immersed in a dopamine solution, treated by shaking at room temperature for 6-8 hours, taken out and rinsed with water 2-3 times, and vacuum dried at 60-70 °C for 1-1.5 hours to cure the polydopamine coating formed on the fiber surface, and a fiber network modified by dopamine is obtained;

[0014] The linear density of the aramid fiber is 200-300 D;

[0015] The linear density of the ultra-high molecular weight polyethylene fiber is 150-200 D;

[0016] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:0.8-1;

[0017] The warp and weft density of the grid structure is 10×10 roots / cm - 14×14 roots / cm;

[0018] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.2-8.8, and the concentration of dopamine in the dopamine solution is 2-2.5 g / L;

[0019] The concentration of the Tris buffer solution is 12-20 mmol / L;

[0020] The method of dipping is as follows: adding oxidized micro carbon fiber into N,N-dimethylacetamide, ultrasonically treating for 20-30 min, then adding polyurethane prepolymer, stirring at a speed of 600-800 rpm for 2-3 h to obtain a glue solution, immersing the fiber network modified by dopamine into the glue solution, taking it out after dipping for 5-8 min, drying at 70-80 °C for 15-20 min to preliminarily gel the glue solution, and then thermocompression laminating with the base layer;

[0021] The mass ratio of the polyurethane prepolymer, oxidized micro carbon fiber, and N,N-dimethylacetamide is 100:5-7:20-30;

[0022] The number-average molecular weight of the polyurethane prepolymer is 500 - 1000;

[0023] The frequency of the ultrasonic wave is 50 - 70 kHz;

[0024] The preparation method of the oxidized micro carbon fiber is to disperse the micro carbon fiber in a 60 - 65 wt% nitric acid solution, reflux at 75 - 80 °C for 3 - 4 h, filter, wash, and dry to obtain oxidized short carbon fibers;

[0025] The length of the micro carbon fiber is 80 - 120 μm;

[0026] The temperature of the hot pressing composite is 150 - 170 °C, and the pressure is 4 - 6 MPa.

[0027] The preparation method of the surface functional layer is to add 5 - 8 wt% of anti-tear microcapsules to PVC resin, extrude and granulate through a twin-screw extruder, then calender into a film at 170 - 180 °C, the film thickness is 0.2 - 0.3 mm, and perform secondary hot pressing composite with the middle reinforcing layer, and wind up after cooling to obtain a PVC light box cloth;

[0028] The temperature of the hot pressing composite is 150 - 170 °C, and the pressure is 4 - 6 MPa.

[0029] The preparation method of the anti-tear microcapsules is to uniformly mix modified nano-silica and polycaprolactone prepolymer, disperse in N,N-dimethylformamide, add initiator benzoyl peroxide, react at 80 - 100 °C for 8 - 10 h, then add 4,4-dithiobutyric acid, stir and react at 60 - 70 °C for 4 - 5 h, and after the reaction, make anti-tear microcapsules by spray drying;

[0030] The number-average molecular weight of the polycaprolactone prepolymer is 500 - 1500;

[0031] The mass ratio of the modified nano-silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4-dithiobutyric acid, and N,N-dimethylformamide is 10 : 20 - 30 : 0.2 - 0.4 : 2 - 3 : 60 - 80;

[0032] During the spray drying process, the inlet air temperature is 100 - 120 °C, the outlet air temperature is 60 - 70 °C, the atomization pressure is 0.3 - 0.5 MPa, and the feeding rate is 5 - 8 mL / min;

[0033] The modified nano-silica is obtained by surface modification of nano-silica with γ-aminopropyltriethoxysilane;

[0034] The preparation method of the modified nano-silica is as follows: disperse nano-silica in a mixed solution of ethanol and water, add γ-aminopropyltriethoxysilane, react at a temperature of 75 - 85 °C for 2 - 3 h, and after the reaction, filter, wash, and dry to obtain the modified nano-silica;

[0035] The mass ratio of the nano-silica, γ-aminopropyltriethoxysilane, and the mixed solution is 10:0.4 - 0.6:100 - 150;

[0036] The mass ratio of ethanol and water in the mixed solution is 10:1 - 2;

[0037] The particle size of the nano-silica is 20 - 50 nm.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) The lightweight and tear-resistant PVC light box cloth of the present invention has a three-dimensional gradient reinforcement structure. Based on the multi-layer composite design and the directional arrangement of high-strength fibers, the mechanical optimization of the tear-resistant performance is realized;

[0040] The hollow polyester fibers in the base layer significantly reduce the material density through the internal cavity structure. The doped short carbon fibers, with their high modulus characteristics, can improve the bending stiffness of the base layer. The short carbon fibers are dispersed in the gaps between the polyester fibers, forming a "micro-pile array" at the interface, inhibiting crack propagation, and forming local reinforcement points;

[0041] The intermediate layer realizes multi-scale reinforcement through dopamine modification and micron composite dipping. The polydopamine coating is rich in catechol groups, forming strong hydrogen bonds and π-π conjugate interactions with the polyurethane solution, enhancing the interfacial bonding strength. After ultrasonic dispersion, the oxidized micron carbon fibers form an interpenetrating network with the polyurethane prepolymer. During hot pressing, the carbon fibers are oriented along the stress direction, forming a "pinning effect", increasing the strength and toughness of the adhesive layer.

[0042] (2) The lightweight and tear-resistant PVC light box cloth of the present invention has a surface layer that endows the PVC light box cloth with dynamic repair ability through dynamic bond microcapsules to inhibit the propagation of microcracks. During the preparation of the tear-resistant microcapsules, γ-aminopropyltriethoxysilane hydrolyzes in an ethanol / water mixed solution to form silanol, which condenses and dehydrates with the surface hydroxyl groups of nano-SiO2 to form Si-O-Si covalent bonds. Benzoyl peroxide thermally decomposes at 80-100 °C to generate benzoyloxy free radicals, which attack the polycaprolactone prepolymer chain segments to initiate chain growth reactions. The amino groups on the surface of the modified SiO2 react with the carboxyl groups at the ends of the polycaprolactone chains through condensation reactions. Free radical polymerization causes the polycaprolactone chains to graft and grow on the surface of SiO2. Subsequently, the added 4,4-dithiobutyric acid reacts with the polycaprolactone to form a cross-linked product of polycaprolactone and 4,4-dithiobutyric acid as the shell with SiO2 as the core, forming a core-shell microcapsule structure. When the material is torn by external force, the microcapsules rupture and release the repair agent. After treatment at 50-70 °C for 20-30 min, the polycaprolactone containing S-S bonds fills the cracks through thermoplastic flow. The S-S bonds break to generate sulfur free radicals, and the free radicals migrate to the crack interface to recombine, achieving crack interface healing. Among them, nano-SiO2 acts as a physical cross-linking point to play a supplementary strengthening role, improving the tear strength recovery rate of the light box cloth.

[0043] (3) The lightweight and tear-resistant PVC light box cloth of the present invention has a unit area weight of 418-425 g / m 2 , a radial tensile strength of 2560-2630 N / 5 cm, a weft tensile strength of 2180-2240 N / 5 cm, a radial elongation at break of 16.5-16.8%, a weft elongation at break of 22.3-23.1%, a trapezoidal tear strength of 620-650 N, an interlayer peel strength of 5.5-5.8 N / mm, and a tear strength recovery rate of 89-90% in the scratch test. Detailed implementation manners

[0044] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention are now described.

[0045] Example 1

[0046] A lightweight and tear-resistant PVC light box cloth includes a base layer, an intermediate reinforcing layer, and a surface functional layer;

[0047] A method for preparing a lightweight and tear-resistant PVC light box cloth includes the following steps:

[0048] (1) Prepare the base layer

[0049] Mix hollow polyester fibers and chopped carbon fibers in a mass ratio of 10:1.5, impregnate with PVC emulsion after needle punching molding, and dry at 100 °C;

[0050] The basis weight of the base layer is 110 g / m 2 , and the porosity is 40%;

[0051] The length of the chopped carbon fiber is 3 mm.

[0052] (2) Preparation of the intermediate reinforcing layer

[0053] A. Dopamine modification

[0054] Aramid fibers with a linear density of 200 D and ultra-high molecular weight polyethylene fibers with a linear density of 150 D are orthogonally woven into a grid structure. The warp and weft densities of the grid structure are 10×10 roots / cm. They are immersed in a dopamine solution and treated with shaking at room temperature for 6 hours. After taking out, they are rinsed with water 2 times and dried in vacuum at 60°C for 1.5 hours to cure the polydopamine coating formed on the fiber surface, obtaining a dopamine-modified fiber network;

[0055] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:0.8;

[0056] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.2. The concentration of dopamine in the dopamine solution is 2 g / L;

[0057] The concentration of the Tris buffer solution is 12 mmol / L.

[0058] B. Impregnation with glue

[0059] Oxidized micro carbon fibers are added to N,N-dimethylacetamide and ultrasonicated for 30 min. Then, a polyurethane prepolymer is added and stirred at a speed of 600 rpm for 2 h to obtain a glue solution. The dopamine-modified fiber network is immersed in the glue solution, taken out after 5 min of impregnation, and dried at 70°C for 20 min to preliminarily gel the glue solution. Then, it is hot-pressed and compounded with the base layer at 150°C and 4 MPa;

[0060] The mass ratio of the polyurethane prepolymer, oxidized micro carbon fibers, and N,N-dimethylacetamide is 100:5:20;

[0061] The number-average molecular weight of the polyurethane prepolymer is 1000;

[0062] The frequency of the ultrasonic wave is 50 kHz;

[0063] The preparation method of the oxidized micro carbon fibers is to disperse the micro carbon fibers in a 60 wt% nitric acid solution, reflux at 75°C for 4 h, filter, wash, and dry to obtain oxidized chopped carbon fibers;

[0064] The length of the micro carbon fibers is 80 μm.

[0065] (3) Preparation of the surface functional layer

[0066] Add 5 wt% of anti - tear microcapsules to PVC resin, granulate by twin - screw extrusion, then calender into a film at 170 °C. The film thickness is 0.2 mm, and it is thermocompression - laminated with the middle reinforcing layer for the second time. The temperature of thermocompression - lamination is 150 °C, the pressure is 4 MPa, and after cooling, it is wound up to obtain a PVC light - box cloth;

[0067] The preparation method of the anti - tear microcapsules is as follows: Mix modified nano - silica and polycaprolactone prepolymer evenly, disperse them in N,N - dimethylformamide, add initiator benzoyl peroxide, react at 80 °C for 10 h, then add 4,4 - dithiobutyric acid, stir and react at 60 °C for 5 h. After the reaction, anti - tear microcapsules are prepared by spray drying;

[0068] The number - average molecular weight of the polycaprolactone prepolymer is 500;

[0069] The mass ratio of the modified nano - silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4 - dithiobutyric acid, and N,N - dimethylformamide is 10:20:0.2:2:60;

[0070] During the spray - drying process, the inlet air temperature is 100 °C, the outlet air temperature is 60 °C, the atomization pressure is 0.3 MPa, and the feeding rate is 5 mL / min;

[0071] The preparation method of the modified nano - silica is as follows: Disperse nano - silica with a particle size of 20 nm in a mixed solution of ethanol and water, add γ - aminopropyltriethoxysilane, react at 75 °C for 3 h. After the reaction, filter, wash, and dry to obtain modified nano - silica;

[0072] The mass ratio of the nano - silica, γ - aminopropyltriethoxysilane, and the mixed solution is 10:0.4:100;

[0073] The mass ratio of ethanol and water in the mixed solution is 10:1.

[0074] Example 2

[0075] A lightweight anti - tear PVC light - box cloth, including a base layer, a middle reinforcing layer, and a surface functional layer;

[0076] A preparation method of a lightweight anti - tear PVC light - box cloth includes the following steps:

[0077] (1) Prepare the base layer

[0078] Mix hollow polyester fibers and chopped carbon fibers according to a mass ratio of 10:1.8, impregnate with PVC emulsion after needle punching, and dry at 110 °C;

[0079] The basis weight of the base layer is 120 g / m 2 , and the porosity is 35%;

[0080] The length of the chopped carbon fiber is 5 mm.

[0081] (2) Preparation of the intermediate reinforcing layer

[0082] A. Dopamine modification

[0083] The aramid fiber with a linear density of 250 D and the ultra-high molecular weight polyethylene fiber with a linear density of 180 D are orthogonally woven into a grid structure. The warp and weft densities of the grid structure are 12×12 roots / cm. It is impregnated in a dopamine solution, treated with oscillation at room temperature for 7 hours, taken out and rinsed with water 3 times, and vacuum dried at 65°C for 1.2 hours to cure the polydopamine coating formed on the fiber surface, obtaining the dopamine-modified fiber network;

[0084] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:0.9;

[0085] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.5. The concentration of dopamine in the dopamine solution is 2.2 g / L;

[0086] The concentration of the Tris buffer solution is 16 mmol / L.

[0087] B. Impregnation with glue

[0088] The oxidized micro carbon fiber is added to N,N-dimethylacetamide, ultrasonically treated for 25 min, the polyurethane prepolymer is added, and stirred at a speed of 700 rpm for 2.5 h to obtain a glue solution. The dopamine-modified fiber network is immersed in the glue solution, taken out after impregnation for 6 min, and dried at 75°C for 18 min to preliminarily gel the glue solution, and then hot-pressed and compounded with the base layer at 160°C and 5 MPa;

[0089] The mass ratio of the polyurethane prepolymer, the oxidized micro carbon fiber, and N,N-dimethylacetamide is 100:6:25;

[0090] The number-average molecular weight of the polyurethane prepolymer is 1200;

[0091] The frequency of the ultrasonic wave is 60 kHz;

[0092] The preparation method of the oxidized micro carbon fiber is to disperse the micro carbon fiber in a 62 wt% nitric acid solution, reflux at 78°C for 3.5 h, filter, wash, and dry to obtain the oxidized chopped carbon fiber;

[0093] The length of the micro carbon fiber is 100 μm.

[0094] (3) Preparation of the surface functional layer

[0095] Add 6 wt% of anti - tear microcapsules to PVC resin, extrude and granulate through a twin - screw extruder, then calender into a film at 175 °C with a film thickness of 0.25 mm, and perform secondary hot - pressing and compounding with the middle reinforcing layer. The temperature of the hot - pressing and compounding is 160 °C, the pressure is 5 MPa, and after cooling, wind up to obtain a PVC light - box cloth;

[0096] The preparation method of the anti - tear microcapsules is as follows: Mix modified nano - silica and polycaprolactone prepolymer evenly, disperse them in N,N - dimethylformamide, add initiator benzoyl peroxide, react at 90 °C for 9 h, then add 4,4 - dithiobutyric acid, and stir and react at 65 °C for 4.5 h. After the reaction, prepare anti - tear microcapsules by spray drying;

[0097] The number - average molecular weight of the polycaprolactone prepolymer is 1000;

[0098] The mass ratio of the modified nano - silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4 - dithiobutyric acid, and N,N - dimethylformamide is 10:25:0.3:2.5:70;

[0099] During the spray - drying process, the inlet air temperature is 110 °C, the outlet air temperature is 65 °C, the atomization pressure is 0.4 MPa, and the feeding rate is 6 mL / min;

[0100] The preparation method of the modified nano - silica is as follows: Disperse nano - silica with a particle size of 30 nm in a mixed solution of ethanol and water, add γ - aminopropyltriethoxysilane, react at 80 °C for 2.5 h, and after the reaction, filter, wash, and dry to obtain modified nano - silica;

[0101] The mass ratio of the nano - silica, γ - aminopropyltriethoxysilane, and the mixed solution is 10:0.5:120;

[0102] The mass ratio of ethanol and water in the mixed solution is 10:1.5.

[0103] Example 3

[0104] A lightweight anti - tear PVC light - box cloth, comprising a base layer, a middle reinforcing layer, and a surface functional layer;

[0105] A preparation method of a lightweight anti - tear PVC light - box cloth comprises the following steps:

[0106] (1)Preparation of the base layer

[0107] Mix hollow polyester fibers and chopped carbon fibers according to a mass ratio of 10:2, impregnate with PVC emulsion after needle punching molding, and dry at 120 °C;

[0108] The basis weight of the base layer is 130 g / m 2 , and the porosity is 30%;

[0109] The length of the chopped carbon fiber is 6 mm.

[0110] (2) Preparation of the intermediate reinforcing layer

[0111] A. Dopamine modification

[0112] Aramid fibers with a linear density of 300 D and ultra-high molecular weight polyethylene fibers with a linear density of 200 D are orthogonally woven into a grid structure. The warp and weft densities of the grid structure are 14×14 roots / cm. The fibers are immersed in a dopamine solution and treated with oscillation at room temperature for 8 hours. After taking out, they are rinsed with water 3 times and dried in vacuum at 70 °C for 1 hour to cure the polydopamine coating formed on the fiber surface, obtaining a dopamine-modified fiber network;

[0113] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:1;

[0114] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.8. The concentration of dopamine in the dopamine solution is 2.5 g / L;

[0115] The concentration of the Tris buffer solution is 20 mmol / L.

[0116] B. Impregnation with glue

[0117] Oxidized micro carbon fibers are added to N,N-dimethylacetamide and ultrasonically treated for 20 min. Then, a polyurethane prepolymer is added and stirred at a rotation speed of 800 rpm for 3 h to obtain a glue solution. The dopamine-modified fiber network is immersed in the glue solution, taken out after 8 min of impregnation, and dried at 80 °C for 15 min to preliminarily gel the glue solution. Then, it is hot-pressed and compounded with the base layer at 170 °C and 6 MPa;

[0118] The mass ratio of the polyurethane prepolymer, oxidized micro carbon fibers, and N,N-dimethylacetamide is 100:7:30;

[0119] The number-average molecular weight of the polyurethane prepolymer is 1500;

[0120] The frequency of the ultrasonic wave is 70 kHz;

[0121] The preparation method of the oxidized micro carbon fibers is as follows: The micro carbon fibers are dispersed in a 65 wt% nitric acid solution, refluxed at 80 °C for 3 h, filtered, washed, and dried to obtain oxidized chopped carbon fibers;

[0122] The length of the micro carbon fibers is 120 μm.

[0123] (3) Prepare the surface functional layer

[0124] Add 8 wt% of anti - tear microcapsules to PVC resin, granulate by twin - screw extrusion, then calender into a film at 180 °C, the film thickness is 0.3 mm, and then thermocompound with the middle reinforcing layer for the second time. The thermocompounding temperature is 170 °C, the pressure is 6 MPa, and after cooling, wind up to obtain the PVC light - box cloth;

[0125] The preparation method of the anti - tear microcapsules is as follows: Mix the modified nano - silica and polycaprolactone prepolymer evenly, disperse them in N,N - dimethylformamide, add initiator benzoyl peroxide, react at 100 °C for 8 h, then add 4,4 - dithiobutyric acid, stir and react at 70 °C for 4 h. After the reaction, make anti - tear microcapsules by spray drying;

[0126] The number - average molecular weight of the polycaprolactone prepolymer is 1500;

[0127] The mass ratio of the modified nano - silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4 - dithiobutyric acid, and N,N - dimethylformamide is 10:30:0.4:3:80;

[0128] During the spray - drying process, the inlet air temperature is 120 °C, the outlet air temperature is 70 °C, the atomization pressure is 0.5 MPa, and the feeding rate is 8 mL / min;

[0129] The preparation method of the modified nano - silica is as follows: Disperse nano - silica with a particle size of 50 nm in a mixed solution of ethanol and water, add γ - aminopropyltriethoxysilane, react at 85 °C for 2 h, and after the reaction, filter, wash, and dry to obtain the modified nano - silica;

[0130] The mass ratio of the nano - silica, γ - aminopropyltriethoxysilane, and the mixed solution is 10:0.6:150;

[0131] The mass ratio of ethanol and water in the mixed solution is 10:2.

[0132] Example 4

[0133] A lightweight anti - tear PVC light - box cloth, including a base layer, a middle reinforcing layer, and a surface functional layer;

[0134] A preparation method of a lightweight anti - tear PVC light - box cloth includes the following steps:

[0135] (1) Prepare the base layer

[0136] Mix hollow polyester fibers and chopped carbon fibers according to a mass ratio of 10:1.8, impregnate with PVC emulsion after needle punching molding, and dry at 110 °C;

[0137] The basis weight of the base layer is 120 g / m 2 , and the porosity is 35%;

[0138] The length of the chopped carbon fiber is 5 mm.

[0139] (2) Prepare the intermediate reinforcement layer

[0140] Aramid fibers with a linear density of 250 D and ultra-high molecular weight polyethylene fibers with a linear density of 180 D are orthogonally woven into a fiber network with a grid structure. The warp and weft density of the fiber network is 12×12 pieces / cm. The oxidized micro carbon fiber is added to N,N-dimethylacetamide, ultrasonically treated for 25 min, and the polyurethane prepolymer is added. Stir for 2.5 h at a rotation speed of 700 rpm to obtain a glue solution. Immerse the fiber network in the glue solution, take it out after impregnation for 6 min, and dry it at 75°C for 18 min to make the glue solution preliminarily gel. Then, thermocompression bond it with the base layer at 160°C and 5 MPa;

[0141] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:0.9;

[0142] The mass ratio of the polyurethane prepolymer, oxidized micro carbon fiber, and N,N-dimethylacetamide is 100:6:25;

[0143] The number average molecular weight of the polyurethane prepolymer is 1200;

[0144] The frequency of the ultrasonic wave is 60 kHz;

[0145] The preparation method of the oxidized micro carbon fiber is to disperse the micro carbon fiber in a 62 wt% nitric acid solution, reflux at 78°C for 3.5 h, filter, wash, and dry to obtain oxidized chopped carbon fiber;

[0146] The length of the micro carbon fiber is 100 μm.

[0147] (3) Prepare the surface functional layer

[0148] Add 6 wt% of anti-tear microcapsules to the PVC resin, extrude and pelletize through a twin-screw extruder, and then calender into a film at 175°C. The film thickness is 0.25 mm, and it is thermocompression bonded to the intermediate reinforcement layer for the second time. The temperature of the thermocompression bonding is 160°C, the pressure is 5 MPa, and it is wound up after cooling to obtain the PVC light box cloth;

[0149] The preparation method of the tear-resistant microcapsules is as follows: Mix the modified nano-silica and the polycaprolactone prepolymer evenly, disperse them in N,N-dimethylformamide, add benzoyl peroxide as the initiator, react at 90 °C for 9 h, then add 4,4-dithiobutyric acid, and stir and react at 65 °C for 4.5 h. After the reaction, the tear-resistant microcapsules are prepared by spray drying;

[0150] The number-average molecular weight of the polycaprolactone prepolymer is 1000;

[0151] The mass ratio of the modified nano-silica, the polycaprolactone prepolymer, benzoyl peroxide, 4,4-dithiobutyric acid, and N,N-dimethylformamide is 10:25:0.3:2.5:70;

[0152] During the spray drying process, the inlet air temperature is 110 °C, the outlet air temperature is 65 °C, the atomization pressure is 0.4 MPa, and the feeding rate is 6 mL / min;

[0153] The preparation method of the modified nano-silica is as follows: Disperse the nano-silica with a particle size of 30 nm in a mixed solution of ethanol and water, add γ-aminopropyltriethoxysilane, and react at 80 °C for 2.5 h. After the reaction, filter, wash, and dry to obtain the modified nano-silica;

[0154] The mass ratio of the nano-silica, γ-aminopropyltriethoxysilane, and the mixed solution is 10:0.5:120;

[0155] The mass ratio of ethanol and water in the mixed solution is 10:1.5.

[0156] Example 5

[0157] A lightweight tear-resistant PVC light box cloth, comprising a base layer, an intermediate reinforcing layer, and a surface functional layer;

[0158] The preparation method of a lightweight tear-resistant PVC light box cloth comprises the following steps:

[0159] (1) Prepare the base layer

[0160] Mix the hollow polyester fiber and the chopped carbon fiber according to a mass ratio of 10:1.8, impregnate the PVC emulsion after needle punching molding, and dry at 110 °C;

[0161] The basis weight of the base layer is 120 g / m 2 , and the porosity is 35%;

[0162] The length of the chopped carbon fiber is 5 mm.

[0163] (2) Prepare the intermediate reinforcing layer

[0164] A. Dopamine Modification

[0165] Aramid fibers with a linear density of 250 D and ultra-high molecular weight polyethylene fibers with a linear density of 180 D are orthogonally woven into a grid structure with a warp and weft density of 12×12 roots / cm. The woven structure is immersed in a dopamine solution and subjected to oscillating treatment at room temperature for 7 hours. After taking it out, it is rinsed with water 3 times and dried in vacuum at 65 °C for 1.2 hours to cure the polydopamine coating formed on the fiber surface, obtaining a dopamine-modified fiber network;

[0166] The mass ratio of the aramid fibers to the ultra-high molecular weight polyethylene fibers is 1:0.9;

[0167] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.5, and the concentration of dopamine in the dopamine solution is 2.2 g / L;

[0168] The concentration of the Tris buffer solution is 16 mmol / L.

[0169] B. Impregnation with Glue

[0170] The polyurethane prepolymer and N,N-dimethylacetamide are mixed and stirred at a speed of 700 rpm for 2.5 h to obtain a glue solution. The dopamine-modified fiber network is immersed in the glue solution, taken out after 6 min of impregnation, and dried at 75 °C for 18 min to preliminarily gel the glue solution, and then hot-pressed and compounded with the base layer at 160 °C and 5 MPa;

[0171] The mass ratio of the polyurethane prepolymer to N,N-dimethylacetamide is 100:25;

[0172] The number-average molecular weight of the polyurethane prepolymer is 1200;

[0173] The frequency of the ultrasonic wave is 60 kHz.

[0174] (3) Preparation of the surface functional layer

[0175] 6 wt% of anti-tear microcapsules are added to the PVC resin, and granulated by twin-screw extrusion. Then it is calendered into a film at 175 °C with a film thickness of 0.25 mm, and hot-pressed and compounded with the middle reinforcing layer for the second time. The temperature of the hot-pressing and compounding is 160 °C and the pressure is 5 MPa. After cooling, it is wound up to obtain the PVC light box cloth;

[0176] The preparation method of the anti-tear microcapsules is as follows: Modified nano-silica and polycaprolactone prepolymer are mixed evenly, dispersed in N,N-dimethylformamide, initiator benzoyl peroxide is added, and the reaction is carried out at 90 °C for 9 h. Then 4,4-dithiobutyric acid is added, and the reaction is stirred at 65 °C for 4.5 h. After the reaction is completed, it is made into anti-tear microcapsules by spray drying;

[0177] The number-average molecular weight of the polycaprolactone prepolymer is 1000;

[0178] The mass ratio of the modified nano-silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4'-dithiobutyric acid, and N,N-dimethylformamide is 10:25:0.3:2.5:70;

[0179] During the spray drying process, the inlet air temperature is 110 °C, the outlet air temperature is 65 °C, the atomization pressure is 0.4 MPa, and the feeding rate is 6 mL / min;

[0180] The preparation method of the modified nano-silica is to disperse nano-silica with a particle size of 30 nm in a mixed solution of ethanol and water, add γ-aminopropyltriethoxysilane, and react at 80 °C for 2.5 h. After the reaction, filter, wash, and dry to obtain the modified nano-silica;

[0181] The mass ratio of the nano-silica, γ-aminopropyltriethoxysilane, and the mixed solution is 10:0.5:120;

[0182] The mass ratio of ethanol and water in the mixed solution is 10:1.5.

[0183] Example 6

[0184] A lightweight and tear-resistant PVC light box cloth, including a base layer, an intermediate reinforcing layer, and a surface layer;

[0185] A preparation method of a lightweight and tear-resistant PVC light box cloth includes the following steps:

[0186] (1) Prepare the base layer

[0187] Mix hollow polyester fibers and chopped carbon fibers according to a mass ratio of 10:1.8, impregnate with PVC emulsion after needle punching molding, and dry at 110 °C;

[0188] The basis weight of the base layer is 120 g / m 2 , and the porosity is 35%;

[0189] The length of the chopped carbon fibers is 5 mm.

[0190] (2) Prepare the intermediate reinforcing layer

[0191] A. Dopamine modification

[0192] The aramid fiber with a linear density of 250 D and the ultra-high molecular weight polyethylene fiber with a linear density of 180 D are orthogonally woven into a grid structure. The warp and weft density of the grid structure is 12×12 roots / cm. It is impregnated in a dopamine solution, oscillated at room temperature for 7 hours, taken out and rinsed with water 3 times, and vacuum dried at 65 °C for 1.2 hours to cure the polydopamine coating formed on the fiber surface, obtaining a dopamine-modified fiber network;

[0193] The mass ratio of the aramid fiber to the ultra-high molecular weight polyethylene fiber is 1:0.9;

[0194] The dopamine solution is prepared by dissolving dopamine hydrochloride in a Tris buffer solution with a pH of 8.5, and the concentration of dopamine in the dopamine solution is 2.2 g / L;

[0195] The concentration of the Tris buffer solution is 16 mmol / L.

[0196] B. Impregnation with glue

[0197] The oxidized micro carbon fiber is added to N,N-dimethylacetamide, ultrasonically treated for 25 min, and the polyurethane prepolymer is added. It is stirred at a rotation speed of 700 rpm for 2.5 h to obtain a glue solution. The dopamine-modified fiber network is immersed in the glue solution, taken out after 6 min of impregnation, and dried at 75 °C for 18 min to preliminarily gel the glue solution, and then hot-pressed and compounded with the base layer at 160 °C and 5 MPa;

[0198] The mass ratio of the polyurethane prepolymer, the oxidized micro carbon fiber, and N,N-dimethylacetamide is 100:6:25;

[0199] The number average molecular weight of the polyurethane prepolymer is 1200;

[0200] The frequency of the ultrasonic wave is 60 kHz;

[0201] The preparation method of the oxidized micro carbon fiber is to disperse the micro carbon fiber in a 62 wt% nitric acid solution, reflux at 78 °C for 3.5 h, filter, wash, and dry to obtain oxidized short carbon fiber;

[0202] The length of the micro carbon fiber is 100 μm.

[0203] (3) Preparation of the surface layer

[0204] The PVC resin is calendered into a film at 175 °C, the film thickness is 0.25 mm, and it is hot-pressed and compounded with the middle reinforcing layer for the second time. The temperature of the hot-pressing and compounding is 160 °C, the pressure is 5 MPa, and it is wound up after cooling to obtain the PVC light box cloth.

[0205] Test Example 1

[0206] The PVC light box fabrics prepared in Examples 1-6 were tested for tensile strength, trapezoidal tear strength and interlayer peel strength, and the test results are shown in Table 1.

[0207] Table 1 Strength performance

[0208]

[0209] As can be seen from Table 1, in Example 4, when preparing the middle reinforcing layer, the fibers were directly impregnated with glue, and the dopamine modification layer was omitted. The tensile strength, elongation at break, trapezoidal tear strength and interlayer peel strength all decreased, indicating that the dopamine modification layer in the middle reinforcing layer can enhance the tensile strength, elongation at break, trapezoidal tear strength and interlayer peel strength of the light box fabric; in Example 5, in the impregnation step during the preparation of the middle reinforcing layer, the glue solution used was a mixed solution of polyurethane prepolymer and N,N-dimethylacetamide. Compared with Example 2, the oxidized micro carbon fiber was omitted, indicating that in the step of preparing the middle reinforcing layer, the oxidized micro carbon fiber in the glue solution has the effect of enhancing the tensile strength, elongation at break, trapezoidal tear strength and interlayer peel strength of the light box fabric.

[0210] Test Example 2

[0211] The tear strength recovery performance of the PVC light box fabrics prepared in Examples 1-3 and Example 6 was tested. The test method was as follows: A standard crack with a length of 5 mm and a depth of 0.1 mm was made using a micro scratch tester, heated at 60 °C for 30 minutes, the trapezoidal tear strength before and after repair was compared, the tear strength recovery rate was calculated, and the crack closure situation was observed. The test results are shown in Table 2.

[0212] Table 2 Tear strength recovery performance

[0213]

[0214] As can be seen from Table 2, the tear strength recovery rate of Example 6 was significantly lower than that of Example 2, and the crack closure effect was also poor. For the PVC light box fabric prepared in Example 6, the surface layer did not add anti-tear microcapsules, indicating that the anti-tear microcapsules added to the surface layer can significantly improve the tear strength recovery performance of the PVC light box fabric.

[0215] Test Example 3

[0216] The weight per unit area of the PVC light box fabrics prepared in Examples 1-6 was tested, and the test results are shown in Table 3.

[0217] Table 3 Weight per unit area

[0218]

[0219] As can be seen from Table 3, the weight per unit area of the PVC light box fabrics prepared in Examples 1-6 was all less than 430 g / m2 , the lightweight of the light box cloth is achieved.

[0220] Finally, it should be noted that the above 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, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightweight and tear-resistant PVC light box cloth, characterized in that, The light box cloth includes a base layer, an intermediate reinforcing layer, and a surface functional layer; The preparation method of the intermediate reinforcing layer includes the following steps: dopamine modification and dipping; The method of dopamine modification is to orthogonally weave aramid fibers and ultra-high molecular weight polyethylene fibers into a grid structure, immerse it in a dopamine solution, perform oscillating treatment at room temperature for 6 - 8 hours, take it out and rinse it with water 2 - 3 times, and dry it in vacuum at 60 - 70 °C for 1 - 1.5 hours to cure the polydopamine coating formed on the fiber surface, obtaining a fiber network modified with dopamine; The method of dipping is to add oxidized micro carbon fibers to N,N-dimethylacetamide, perform ultrasonic treatment for 20 - 30 min, then add a polyurethane prepolymer, stir at a rotation speed of 600 - 800 rpm for 2 - 3 h to obtain a glue solution, immerse the fiber network modified with dopamine in the glue solution, take it out after dipping for 5 - 8 min, and dry it at 70 - 80 °C for 15 - 20 min to preliminarily gel the glue solution, and then thermocompression laminate it with the base layer; The preparation method of the surface functional layer is to add 5 - 8 wt% of anti-tear microcapsules to PVC resin, extrude and granulate it through a twin-screw extruder, and then calender it into a film at 170 - 180 °C, with the film thickness of 0.2 - 0.3 mm, perform secondary thermocompression lamination with the intermediate reinforcing layer, cool it and then wind it up to obtain a PVC light box cloth; The preparation method of the anti-tear microcapsules is to uniformly mix modified nano-silica and a polycaprolactone prepolymer, disperse it in N,N-dimethylformamide, add an initiator benzoyl peroxide, react at 80 - 100 °C for 8 - 10 h, then add 4,4-dithiobutyric acid, stir and react at 60 - 70 °C for 4 - 5 h, and after the reaction, make anti-tear microcapsules through spray drying.

2. The lightweight anti-tear PVC light box cloth according to claim 1, wherein In the step of dopamine modification, the dopamine solution is prepared by dissolving dopamine hydrochloride in Tris buffer solution with a pH of 8.2 - 8.8, the concentration of dopamine in the dopamine solution is 2 - 2.5 g / L; the concentration of Tris buffer solution is 12 - 20 mmol / L.

3. A lightweight and tear-resistant PVC light box cloth according to claim 2, characterized in that, In the step of dopamine modification, The linear density of the aramid fiber is 200 - 300 D; The linear density of the ultra-high molecular weight polyethylene fiber is 150 - 200 D; The mass ratio of aramid fiber to ultra-high molecular weight polyethylene fiber is 1:0.8 - 1; The warp and weft density of the grid structure is 10×10 roots / cm - 14×14 roots / cm.

4. A lightweight tear-resistant PVC light box cloth according to claim 1, characterized in that In the step of dipping, The mass ratio of the polyurethane prepolymer, oxidized micro carbon fibers, and N,N-dimethylacetamide is 100:5 - 7:20 - 30; The number average molecular weight of the polyurethane prepolymer is 500 - 1000.

5. A lightweight anti-tear PVC light box cloth according to claim 1, characterized in that, In the step of dipping, the preparation method of the oxidized micro carbon fibers is to disperse the micro carbon fibers in a 60 - 65 wt% nitric acid solution, reflux at 75 - 80 °C for 3 - 4 h, filter, wash, and dry to obtain oxidized short-cut carbon fibers; The length of the micro carbon fibers is 80 - 120 μm.

6. The lightweight tear-resistant PVC light box cloth according to claim 1, characterized in that, In the preparation step of the anti-tear microcapsules, The number average molecular weight of the polycaprolactone prepolymer is 500 - 1500; The mass ratio of the modified nano-silica, polycaprolactone prepolymer, benzoyl peroxide, 4,4'-dithiobutyric acid, and N,N-dimethylformamide is 10:20 - 30:0.2 - 0.4:2 - 3:60 - 80; The modified nano-silica is obtained by surface modification of nano-silica with γ-aminopropyltriethoxysilane.

7. The lightweight tear-resistant PVC light box cloth according to claim 1, characterized in that, In the preparation step of the tear-resistant microcapsules, during the spray drying process, the inlet air temperature is 100 - 120 °C, the outlet air temperature is 60 - 70 °C, the atomization pressure is 0.3 - 0.5 MPa, and the feeding rate is 5 - 8 mL / min.

8. A lightweight and tear-resistant PVC light box cloth according to claim 1, characterized in that The preparation method of the base layer is to mix hollow polyester fibers and short carbon fibers, impregnate with PVC emulsion after needle punching molding, and dry at 100 - 120 °C. The mass ratio of the hollow polyester fibers to the short carbon fibers is 10:1.5 - 2; The length of the short carbon fibers is 3 - 6 mm.

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