Curtain fabric and production process thereof

Abstract

The invention discloses curtain cloth and a production process thereof, and aims to solve the problems that the conventional curtain cloth is inflammable and the conventional flame-retardant treatment method has defects. The curtain cloth comprises base cloth and a flame-retardant layer which coats and permeates the base cloth, and the flame-retardant layer contains raw materials such as a composite resin matrix and flame-retardant filler. The composite resin matrix is composed of a waterborne epoxy emulsion and UV-cured epoxy acrylate, and the flame-retardant filler contains phosphorus-nitrogen hybridized sodium alginate and nano-grafted lignin microspheres. The production process comprises the steps of base cloth activation, flame-retardant coating preparation, electrostatic-high-pressure double spraying, gradient curing and after-finishing strengthening. Through unique raw material compounding, the limit oxygen index of the curtain cloth is increased, combustion is delayed, and smoke is reduced; the washing resistance is improved by the amphiphilic film-forming agent; the production process ensures the performance of the base cloth, reduces energy consumption and VOC emission, and meets multiple requirements of modern buildings on safety, durability, comfort and green production of the curtain cloth.

Description

Technical Field

[0001] The present invention relates to the technical field of curtain fabrics, and particularly relates to a curtain fabric and its production process. Background Art

[0002] With the improvement of people's living standards and the increasing requirements for residential safety and environmental beauty, curtains, as important decorative materials connecting the indoor and outdoor environments, play an increasingly important role in modern architecture and home environments. Traditional curtain fabrics, such as cotton, linen, polyester, chemical fiber, silk, and non-woven fabrics, mainly function as aesthetics, light blocking, and breathability. However, they generally have potential safety hazards such as flammability, fast burning speed, and rapid fire spread.

[0003] Especially in public buildings, hotels, cinemas and other places, curtains, as large-area textile decorations, once a fire occurs, are extremely likely to become an important medium for fire spread due to their flammability, increasing the difficulty of personnel evacuation and causing huge losses of life and property. Therefore, currently, the flame retardancy of curtain fabrics is also crucial.

[0004] The main methods for improving the flame retardancy of existing curtain fabrics include the flame retardant impregnation method and the surface coating method; among them, the flame retardant impregnation method is to soak the finished fabric in a flame retardant solution and improve the flame retardancy by adsorbing flame retardant components. However, this method has problems such as uneven distribution of flame retardants and limited absorption of internal fibers, and after multiple washes, the flame retardancy decreases significantly; The surface coating method is to form a flame retardant coating on the fabric surface to improve the flame retardant effect. However, since most of these flame retardant coatings are physically attached, they are easily peeled off during use, have insufficient durability, and the coating may cause the hand feeling to become hard, affecting the softness and breathability of the fabric. Summary of the Invention

[0005] The main purpose of the present invention is to provide a curtain fabric and its production process, aiming to solve the problems of flammability of traditional curtain fabrics, uneven distribution of flame retardants, easy peeling of coatings, hard hand feeling, etc. existing in existing flame retardant treatment methods.

[0006] To achieve the above object, the present invention provides a curtain fabric, including a base fabric and a flame retardant layer coated on the surface of the base fabric and penetrating into the fiber gaps; the flame retardant layer includes the following raw materials in parts by mass: 30 - 50 parts of a composite resin matrix, 40 - 60 parts of a flame retardant filler, 150 - 300 parts of an amphiphilic film-forming agent, 10 - 15 parts of ammonium polyphosphate, and 2 - 4 parts of a dispersant.

[0007] In a possible implementation manner, the composite resin matrix includes 10 - 15 parts of an aqueous epoxy emulsion and 20 - 35 parts of a UV-curable epoxy acrylate; The flame retardant filler includes 15-25 parts of phosphorus-nitrogen hybrid sodium alginate and 25-35 parts of nano-grafted lignin microspheres; The amphiphilic film-forming agent is double-crosslinked modified soy protein powder, which is prepared by alkali hydrolysis, glutaraldehyde crosslinking and hydrophobic modification with methyl methacrylate.

[0008] In a possible implementation manner, the phosphorus-nitrogen hybrid sodium alginate contains 3-5 parts of sodium alginate, 1-2 parts of melamine and 0.5-1 part of ammonium dihydrogen phosphate. The three are copolymerized for 1-3 hours under the conditions of pH value of 8-10 and temperature of 70-90 °C to obtain phosphorus-nitrogen hybrid sodium alginate.

[0009] In a possible implementation manner, the average particle size of the nano-grafted lignin microspheres is 50-80 nanometers; based on the mass of lignin, the grafting rate of hydroxyacrylate grafted on its surface is 18%-22%.

[0010] In a possible implementation manner, the dispersant is a bio-based dispersant, and preferably oleic acid amide or castor oil polyoxyethylene ether.

[0011] In a possible implementation manner, 1-3 parts of nano-titanium dioxide are further added to the flame retardant layer.

[0012] A production process of a curtain fabric, which is used to prepare the curtain fabric, includes the following steps: S1. Activation treatment of the base fabric: Immerse the base fabric in a quaternary ammonium salt cation solution with a concentration of 0.8%-1.2%, control the pick-up rate at 70%-80% by roller extrusion, and then dry it at 100-120 °C to make the Zeta potential on the surface of the base fabric reach +15 mV to +20 mV; S2. Preparation of the flame retardant coating: Add the composite resin matrix, flame retardant filler, amphiphilic film-forming agent, ammonium polyphosphate and bio-based dispersant into a sand mill and grind until the particle size is less than 1 micron to obtain a water-based flame retardant coating with a solid content of 58%-62%; S3. Electrostatic-high pressure double spraying: First, use an electrostatic spray gun to spray the flame retardant coating prepared in S2 on the surface of the activated base fabric to make the coating penetrate into the fiber gaps of the base fabric, and the penetration depth reaches 70%-80% of the thickness of the base fabric; then after 12 hours, change to a high-pressure airless spray gun to perform secondary spraying on the surface of the base fabric to form a dense flame retardant coating, and the single spraying amount is controlled at 150-200 g / m²; S4. Gradient curing: First, irradiate the base fabric with ultraviolet light with a wavelength of 365 nm, control the ultraviolet light energy at 900-1000 mJ / cm² to make the crosslinking degree of the acrylate double bond in the resin matrix reach more than 85%; Then transfer the base fabric to a heat pump oven and keep it at a temperature of 120°C - 130°C for 15 - 20 minutes to promote the cross-linking reaction between the waterborne epoxy emulsion and the hydroxyl groups on the surface of the base fabric fibers; S5. Post-treatment strengthening: Wash the cured base fabric with warm water at 50°C to remove the surface floating materials, then immerse it in an N-methylolacrylamide solution with a concentration of 2% - 3%. After being extruded by a roller, keep the liquor pickup rate at 60% - 80%. Then conduct thermal cross-linking at 150°C for 10 minutes. Finally, perform a leveling treatment through a stenter to obtain the finished curtain fabric.

[0013] In a possible implementation manner, in step S2, the preparation steps of the flame retardant filler are as follows: A1. Preparation of phosphazene hybrid sodium alginate: The specific steps are as follows: a1: Add sodium alginate, melamine, and ammonium dihydrogen phosphate to deionized water according to a mass ratio of (3 - 5):(1 - 2):(0.5 - 1), and stir at 50 - 60°C until completely dissolved to form a mixed solution; a2: Adjust the pH of the mixed solution to 8.5 - 9.5 with sodium hydroxide solution, transfer it to a reaction vessel under nitrogen protection, and mechanically stir and react at 80 - 90°C for 2 - 3 hours to dehydrate and condense the carboxyl group of sodium alginate and the amino group of melamine to form an amide bond, and esterify with ammonium dihydrogen phosphate to generate a P - O - C bond; a3: Dialyze the reacted solution for 48 hours to remove small molecule impurities, and then obtain a white powder through spray drying. Its phosphorus content is 9% - 11%, nitrogen content is 11% - 13%, the char residue rate at 500°C is ≥35%, and the molecular structure contains a flame retardant active group formed by a P - O - C bond and a C - N bond; A2. Preparation of nano-grafted lignin microspheres: The specific steps are as follows: b1: Lignin nano-treatment: Mix industrial lignin and sulfuric acid solution according to a mass ratio of 1:(8 - 10), and crush it under ultrasonic power of 500 - 800W and frequency of 40kHz for 2 - 3 hours until the average particle size of lignin particles reaches 50 - 80 nanometers; b2: Surface grafting reaction: Add 10% - 15% of hydroxyacrylate and 1% - 2% of potassium persulfate initiator based on the mass of lignin to the nano-lignin suspension, and stir and react in a water bath at 60 - 70°C for 3 - 4 hours to make the hydroxyl groups on the surface of lignin and the double bonds of hydroxyacrylate undergo a grafting reaction to form a modified layer containing acrylate active groups; b3: Solid-liquid separation and drying: After the reaction, separate the solid particles by centrifugation, wash them 3 times with deionized water to remove unreacted reagents, and finally obtain surface-grafted nano-lignin microspheres through spray drying.

[0014] In a possible implementation, in step S3, the nozzle aperture of the electrostatic spray gun is 0.4 - 0.5 mm, and the spraying distance is 12 - 15 cm; the nozzle aperture of the high-pressure airless spray gun is 0.9 - 1.0 mm, and the spraying distance is 18 - 20 cm.

[0015] In a possible implementation, in the preparation step of the S2 flame retardant coating, a photoinitiator is further added. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone, and its addition amount is 2% - 3% of the composite resin matrix.

[0016] In summary, the beneficial effects of the present invention are as follows: Compared with the prior art, in the present invention, a phosphorus-nitrogen hybrid sodium alginate and nano-grafted lignin microspheres are compounded in the flame retardant layer. By the synergistic effect that the former decomposes to generate non-combustible gases to cool down and catalyze carbonization, and the latter forms a dense expanded carbon layer to isolate oxygen, the limiting oxygen index of the curtain fabric is increased to more than 45, significantly delaying the combustion rate and reducing smoke generation, effectively reducing the risk of fire spread; the double-crosslinked modified soy protein powder is used as an amphiphilic film-forming agent. By the hydrophilic group anchoring the base fabric fibers and the hydrophobic group protecting the coating, a chemical bond is formed between the flame retardant layer and the base fabric. After 20 times of washing, the loss rate of the flame retardant filler is ≤10%, and the washing resistance performance is improved by more than 3 times compared with the traditional coating method, and a stable flame retardant effect is still maintained after long-term use.

[0017] In the production process, the electrostatic-assisted spraying process enables the flame retardant coating to uniformly penetrate the gaps between the base fabric fibers and form a dense coating on the surface. Combining with the gradient curing technology to avoid high-temperature damage to the base fabric, the obtained curtain fabric has an elongation at break of ≥30%, a soft hand feeling and a wear resistance performance improved by 40%, solving the problems of hard brittleness and easy peeling of the traditional flame retardant coating; at the same time, the UV curing and heat pump low-temperature crosslinking process reduces the production energy consumption by 50% compared with the traditional method, and realizes low VOC emissions through bio-based raw materials and environmental protection processes, meeting the multiple requirements of modern buildings for the safety, durability, comfort and green production of curtain fabrics. Specific embodiments

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the following further describes the present application in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] The present invention provides a curtain fabric, which includes a base fabric and a flame retardant layer coated on the surface of the base fabric and penetrating into the fiber gaps; the flame retardant layer uses a composite resin matrix as a film-forming skeleton, loads functional fillers such as phosphorus-nitrogen hybrid sodium alginate and nano-grafted lignin microspheres, and realizes a firm combination with the base fabric through an amphiphilic film-forming agent.

[0020] Among them, there are 30 - 50 parts of composite resin matrix, 40 - 60 parts of flame retardant filler, 150 - 300 parts of amphiphilic film-forming agent, 10 - 15 parts of ammonium polyphosphate, and 2 - 4 parts of dispersant.

[0021] The composite resin matrix includes 10 - 15 parts of waterborne epoxy emulsion and 20 - 35 parts of UV-curable epoxy acrylate; The flame retardant filler includes 15 - 25 parts of phosphorus-nitrogen hybrid sodium alginate and 25 - 35 parts of nano-grafted lignin microspheres; The amphiphilic film-forming agent is double-crosslinked modified soy protein powder, and the double-crosslinked modified soy protein powder is prepared by alkali hydrolysis, glutaraldehyde crosslinking and hydrophobic modification with methyl methacrylate.

[0022] Preferably, the phosphorus-nitrogen hybrid sodium alginate contains 3 - 5 parts of sodium alginate, 1 - 2 parts of melamine and 0.5 - 1 part of ammonium dihydrogen phosphate, and the three are copolymerized under the conditions of pH value of 8 - 10 and temperature of 70 - 90 °C for 1 - 3 hours to obtain phosphorus-nitrogen hybrid sodium alginate.

[0023] Preferably, the average particle size of the nano-grafted lignin microspheres is 50 - 80 nanometers; based on the mass of lignin, the grafting rate of hydroxyacrylate grafted on its surface is 18% - 22%.

[0024] Preferably, the dispersant is a bio-based dispersant, and preferably oleic acid amide or castor oil polyoxyethylene ether.

[0025] Preferably, 1 - 3 parts of nano-titanium dioxide are further added to the flame retardant layer.

[0026] Specifically, the composite resin matrix is composed of waterborne epoxy emulsion and UV-curable epoxy acrylate. The waterborne epoxy emulsion contains a large number of hydroxyl groups, which can form hydrogen bonds and covalent bonds with the hydroxyl groups of base cloth fibers, such as cotton fibers, and the ester groups of polyester, enhancing the adhesion between the flame retardant layer and the base cloth; the UV-curable epoxy acrylate contains double bonds and is rapidly crosslinked under 365 nm ultraviolet light through a photoinitiator, such as 1-hydroxycyclohexyl phenyl ketone, to form a flexible network structure, avoiding the hard and brittle defects of traditional epoxy resin coatings. After the two are compounded, they can not only anchor the base cloth through the hydrophilic groups of the waterborne emulsion, but also form a weather-resistant film layer through UV curing, so that the elongation at break of the coating can reach more than 30%, with a soft hand feeling and fold resistance.

[0027] The flame retardant filler includes phosphorus-nitrogen hybrid sodium alginate and nano-grafted lignin microspheres. Among them, the phosphorus-nitrogen hybrid sodium alginate is prepared by copolymerizing sodium alginate, melamine and ammonium dihydrogen phosphate under specific conditions. The specific steps are as follows: a1: First, sodium alginate, melamine, and ammonium dihydrogen phosphate are added to deionized water according to a mass ratio of (3 - 5):(1 - 2):(0.5 - 1), and stirred at 50 - 60 °C until completely dissolved to form a mixed solution; Among them, when the amount of melamine exceeds 2 parts, the nitrogen content reaches 14%, but the char residue rate no longer increases significantly, and the solution viscosity surges, resulting in uneven reaction; When the amount of ammonium dihydrogen phosphate is less than 0.5 part, the formation rate of P - O - C bonds drops to 70%, the flame - retardant active groups decrease, and the LOI drops to 42%.

[0028] a2: The pH of the mixed solution is adjusted to 8.5 - 9.5 with sodium hydroxide solution, transferred to a reaction vessel under nitrogen protection, and mechanically stirred and reacted at 80 - 90 °C for 2 - 3 hours to dehydrate and condense the carboxyl group of sodium alginate with the amino group of melamine to form an amide bond, and esterify with ammonium dihydrogen phosphate to generate P - O - C bonds; a3: The solution after the reaction is dialyzed for 48 hours to remove small - molecule impurities, and then spray - dried to obtain white powdery phosphorus - nitrogen hybrid sodium alginate. The phosphorus content in this white powder is 9% - 11%, the nitrogen content is 11% - 13%, the char residue rate at 500 °C ≥ 35%, and the molecular structure contains flame - retardant active groups formed by P - O - C bonds and C - N bonds.

[0029] Among them, for solution dialysis, a dialysis bag with a cut - off molecular weight of 10 kDa is used, continuously stirred and dialyzed in deionized water, and the dialysis solution is changed every 6 hours. After 48 hours, the residual amount of melamine in the filtrate is detected to be < 0.1%, ensuring that the removal rate of small - molecule impurities ≥ 95%.

[0030] The phosphorus - nitrogen hybrid sodium alginate prepared by the above method steps has a char residue rate at 500 °C ≥ 35%, can significantly increase the limiting oxygen index of curtain fabric to above 45, and greatly delays the burning speed. Specifically, sodium alginate itself is a natural polymer compound, and its molecule contains a large number of hydroxyl and carboxyl groups. During the combustion process, the carboxyl group will undergo a decarboxylation reaction to produce carbon dioxide gas. Carbon dioxide is a non - combustible gas, which can dilute the oxygen concentration around, reducing the intensity of combustion. At the same time, the hydroxyl group will undergo a dehydration reaction to generate water. Water will absorb a large amount of heat during the vaporization process, thus reducing the temperature on the surface of the curtain fabric and playing a role in cooling.

[0031] The addition of melamine and ammonium dihydrogen phosphate introduces special groups such as phosphoryl groups and nitrogen heterocycles into the phosphorus - nitrogen hybrid sodium alginate. Under high - temperature conditions, these phosphorus - nitrogen groups will play a catalytic role, promoting the carbonization reaction of organic substances such as lignin. The carbonization reaction will form a phosphorus - containing expanded carbon layer, which has good heat - insulation and oxygen - isolation properties. It is like a protective film, which can isolate the entry of oxygen and prevent the diffusion of combustible gases, thus effectively inhibiting the continuation of combustion.

[0032] In addition, the nano-grafted lignin microspheres are obtained by specially treating industrial lignin, and the specific steps are as follows: b1: Lignin nano-treatment: Mix industrial lignin with sulfuric acid solution at a mass ratio of 1:(8 - 10), and crush it for 2 - 3 hours under the conditions of ultrasonic power of 500 - 800W and frequency of 40kHz until the average particle size of lignin particles reaches 50 - 80 nanometers; b2: Surface grafting reaction: Add 10% - 15% of hydroxyacrylate and 1% - 2% of potassium persulfate initiator based on the mass of lignin to the nano-lignin suspension, and stir and react in a water bath at 60 - 70°C for 3 - 4 hours to cause the grafting reaction between the hydroxyl groups on the lignin surface and the double bonds of hydroxyacrylate, forming a modified layer containing acrylate active groups; b3: Solid-liquid separation and drying: After the reaction, centrifuge to separate solid particles, wash 3 times with deionized water to remove unreacted reagents, and finally obtain surface-grafted nano-lignin microspheres by spray drying.

[0033] The nano-grafted lignin microspheres prepared by the above method have unique advantages. The fiber gaps of base fabrics such as high-density knitted fabrics are about 100 - 200 nanometers, and the nano-grafted lignin microspheres can be evenly filled into these fiber gaps, avoiding the problem that micron-sized lignin is prone to agglomeration. This uniform filling can enhance the adhesion between fibers and improve the overall strength of the curtain fabric. At the same time, the acrylate groups grafted on the lignin surface have high reactivity, and they can undergo an esterification reaction with epoxy acrylate in the resin matrix to form a covalent bond connection. This covalent bond connection is like a strong rivet, tightly binding the nano-grafted lignin microspheres and the resin matrix together, enhancing the compatibility between the filler and the resin.

[0034] Lignin itself contains a rich aromatic ring structure. When heated, a series of chemical reactions will occur in these aromatic ring structures, and rapid carbonization will form a dense carbon layer. The thickness of this carbon layer is about 0.05 - 0.1mm, and it cooperates with the expanded carbon layer formed by phosphorus-nitrogen hybrid sodium alginate to form a "double carbon layer" protection structure. The "double carbon layer" structure can more effectively isolate oxygen, and the oxygen isolation efficiency is increased by 40% compared with a single carbon layer. In addition, the nano-treatment increases the specific surface area of lignin by 3 times, which means that more lignin surfaces can participate in the carbonization reaction, thus accelerating the formation speed of the carbon layer by 20%.

[0035] In addition, the amphiphilic film-forming agent is double-crosslinked modified soy protein powder, and the double-crosslinked modified soy protein powder is prepared by alkali hydrolysis, glutaraldehyde crosslinking and hydrophobic modification with methyl methacrylate; specifically, the preparation method of the double-crosslinked modified soy protein powder is as follows: Alkaline hydrolysis treatment: The soy protein powder was mixed with a 10% sodium hydroxide solution by mass ratio of 1:5 and stirred and reacted in a 55°C water bath for 1.5 hours to break the disulfide bonds of protein molecules. The degree of hydrolysis reached 25%, and the free amino group content was detected by the ninhydrin method, which exposed a large number of amino and carboxyl groups.

[0036] Glutaraldehyde cross-linking: An aqueous glutaraldehyde solution with a concentration of 25% and accounting for 6% of the mass of the soy protein powder was added, and the cross-linking reaction was carried out at 40°C for 2 hours. The average molecular weight was increased from 30 kDa to 150 kDa measured by gel permeation chromatography, and the cross-linking degree (covalent bond binding rate) ≥ 60%, forming a -C-N- network structure.

[0037] Hydrophobic modification: Methyl methacrylate was added to the system at 35% of the mass of the soy protein powder, and under the action of 0.5% ammonium persulfate as an initiator, emulsion polymerization reaction was carried out at 60°C for 3 hours. The grafting rate of methacrylate was detected by infrared spectroscopy to reach 38%, and the hydrophobic angle of the modified protein film was measured by a contact angle measuring instrument to be 98°±2°.

[0038] First, the soy protein was treated by alkaline hydrolysis with sodium hydroxide. Sodium hydroxide can open the disulfide bonds in the soy protein molecules, making the structure of the protein molecules more loose and exposing more active groups. Then, glutaraldehyde was used for cross-linking treatment. The aldehyde groups in the glutaraldehyde molecules can react with the amino groups in the soy protein molecules to form a -C-N- network structure, so that the soy protein molecules are connected to each other to form a larger molecular network. Finally, methyl methacrylate was used for hydrophobic modification. The hydrophobic chain segments of methyl methacrylate will be grafted onto the soy protein molecules, making the soy protein have hydrophobic properties.

[0039] The double-crosslinked modified soy protein powder has the characteristics of amphiphilicity. The hydrophilic groups in its molecules, such as amino groups, can form hydrogen bonds with the hydroxyl groups on the surface of the base fabric fibers and fix the soy protein on the base fabric like small hooks. The hydrophobic chain segments, that is, methacrylate, will wrap around the resin and fillers to form a hydrophobic protective film. This "hydrophilic anchoring-hydrophobic protection" amphiphilic film layer structure has many advantages.

[0040] Glutaraldehyde crosslinking increases the molecular weight of soy protein from the original 30 kDa to 150 kDa, forming a high-strength elastic film. This elastic film has good tear resistance, and after testing, its tensile strength ≥ 15 MPa. Hydrophobic modification gives the surface of the soy protein film a certain degree of hydrophobicity, with the contact angle reaching 95° - 105°. This hydrophobicity can reduce the penetration of water molecules and lower the possibility of the flame retardant filler being washed away by water. After 20 washes, the loss rate of the flame retardant filler ≤ 10%, and the water wash resistance is more than 3 times higher than that of traditional physically attached coatings. In addition, soy protein molecules also have shear thickening characteristics, that is, under the action of high shear force, their viscosity will decrease. During electrostatic spraying, this characteristic enables the coating to flow smoothly through the spray gun without clogging the spray gun, ensuring the uniformity of the coating, and the error of the coating thickness ≤ 5%.

[0041] At the same time, auxiliary components are also added to the flame retardant layer, such as ammonium polyphosphate and bio-based dispersant; ammonium polyphosphate is a common phosphorus-based flame retardant. At high temperatures, ammonium polyphosphate will undergo a decomposition reaction to decompose into polyphosphoric acid. Polyphosphoric acid has strong acidity, and it can catalyze the dehydration carbonization reaction of organic substances such as cellulose to form a glassy protective layer. This glassy protective layer will cover the fiber surface and can inhibit the release of combustible gases. Ammonium polyphosphate, phosphorus-nitrogen hybrid sodium alginate, and lignin jointly form a "phosphorus-nitrogen-carbon" ternary flame retardant system, and they cooperate with each other to significantly improve the charring efficiency and further enhance the flame retardant performance of the curtain fabric.

[0042] The role of the bio-based dispersant is to reduce the surface tension on the surface of the nano-fillers. In the coating system, the particle size of phosphorus-nitrogen hybrid sodium alginate is about 5 - 10 μm, and the particle size of nano-lignin microspheres is 50 - 80 nm. Without the presence of a dispersant, these nano-fillers are easily agglomerated together, resulting in uneven distribution of the fillers in the coating, thus affecting the consistency of the flame retardant performance. The lipophilic group in the oleic acid amide molecule can adsorb on the surface of the nano-fillers, while the hydrophilic group faces the surrounding medium, forming an adsorption layer. This adsorption layer can reduce the attraction between the nano-fillers, enabling them to be evenly dispersed in the resin matrix. After dispersion treatment, the particle size D90 of the nano-fillers in the coating ≤ 1 μm, ensuring that the fluctuation of the limiting oxygen index in each area of the coating ≤ 1%, guaranteeing the uniformity of the flame retardant performance.

[0043] In summary, in terms of flame retardancy, the synergistic effect of phosphorus-nitrogen hybrid sodium alginate and nano-grafted lignin microspheres plays a key role. The "double carbon layer" structure formed by them can effectively isolate oxygen and reduce the burning rate. After testing, the limiting oxygen index of the curtain fabric reaches over 45, which means that in a general environment, it is very difficult to ignite the curtain fabric. At the same time, the smoke density during combustion is reduced by 25%, and the smoldering time is shortened from 25 s of traditional curtain fabric to 7 s, greatly reducing the generation of smoke and the smoldering time in a fire, effectively suppressing the spread of fire, and winning precious time for personnel evacuation and fire fighting.

[0044] In terms of durability, the chemical bonding formed between the double-crosslinked modified soy protein powder and the resin matrix enables the coating to be tightly bonded to the base fabric. After 20 washes, the flame retardancy retention rate ≥ 92%, which indicates that the flame retardancy of the curtain fabric can still be well maintained during long-term use and washing. At the same time, the wear resistance has also been significantly improved. Through the Martindale test, the number of wear-resistant times reaches over 5000, which means that during daily friction and use, the coating of the curtain fabric is not easy to fall off, and it can maintain good appearance and performance.

[0045] In terms of the use experience, the combination of the flexible resin matrix and the amphiphilic protein film layer endows the curtain fabric with good flexibility and a soft handfeel. Its elongation at break ≥ 30%, which means that the curtain fabric can have a certain deformation without breaking when being stretched, making it more comfortable to use. In addition, the nano-fillers are filled into the fiber gaps, not only enhancing the strength of the curtain fabric, but also improving the light-shielding property and the fineness of the touch, making the curtain fabric perform excellently both in terms of beauty and practicality.

[0046] In addition, in this technical solution, nano-titanium dioxide is added to the flame retardant layer. When preparing the flame retardant coating, it is added to the sand mill together with the composite resin matrix, flame retardant filler, amphiphilic film-forming agent, ammonium polyphosphate and bio-based dispersant for grinding. Under the mechanical action of the sand mill, nano-titanium dioxide is uniformly dispersed in the coating system, and finally becomes a part of the flame retardant layer as the coating is sprayed on the base fabric.

[0047] Among them, nano-titanium dioxide has photocatalytic activity. When irradiated by light of a certain wavelength, it can generate electron-hole pairs. These electrons and holes can react with the surrounding oxygen and water to generate highly oxidizing hydroxyl radicals and superoxide anion radicals. When the curtain fabric burns, these radicals can react with the combustible gases generated by combustion, oxidize and decompose them, thereby inhibiting the combustion process and assisting in improving the flame retardancy of the curtain fabric. At the same time, the presence of nano-titanium dioxide can also promote other flame retardant components to play a better role, synergize with phosphorus-nitrogen hybrid sodium alginate, nano-grafted lignin microspheres, etc., to enhance the overall flame retardant effect; at the same time, in daily use, the photocatalytic properties of nano-titanium dioxide endow it with self-cleaning ability. It can decompose organic pollutants adsorbed on the surface of the curtain fabric, such as dust, oil stains, etc. Under light irradiation, the radicals generated by nano-titanium dioxide undergo redox reactions with organic pollutants, converting them into harmless carbon dioxide and water, keeping the curtain fabric clean, extending its service life, and enhancing the user experience; moreover, nano-titanium dioxide has good absorption and scattering effects on ultraviolet rays. It can effectively block the irradiation of ultraviolet rays on the curtain fabric, reduce the damage of ultraviolet rays to the base fabric fibers and the components of the flame retardant layer, prevent the curtain fabric from aging and fading due to long-term light irradiation, protect the appearance and performance of the curtain fabric, and improve its weather resistance.

[0048] Based on the above formula materials, the present application also improves the production process, including the following steps: S1. Activation treatment of the base fabric: Immerse the base fabric in a quaternary ammonium salt cation solution with a concentration of 0.8%-1.2%. The cations in the quaternary ammonium salt cation solution will adsorb on the surface of the base fabric, making the surface of the base fabric carry a positive charge. Then, by controlling the extrusion degree of the rolling mill, after the base fabric is extruded by the rolling mill, the pick-up rate is controlled at 70%-80%, and then dried at 100-120°C to make the Zeta potential on the surface of the base fabric reach +15mV to +20mV.

[0049] Among them, components such as phosphorus-nitrogen hybrid sodium alginate and soy protein powder in the flame retardant coating carry a negative charge. According to the principle of electrostatic attraction between opposite charges, the positively charged surface of the base fabric will form an electrostatic adsorption effect with the negatively charged flame retardant coating. This electrostatic adsorption effect can promote the directional penetration of the flame retardant coating into the gaps between the base fabric fibers, enabling the coating to penetrate deeper into the interior of the base fabric, and the penetration depth can reach 70%-80% of the thickness of the base fabric. Compared with the traditional dipping method, this method solves the problem of limited absorption of internal fibers, enables the flame retardant to be more evenly distributed in the base fabric, and improves the flame retardant effect.

[0050] S2. Preparation of the flame retardant coating: Add the composite resin matrix, flame retardant filler, amphiphilic film-forming agent, ammonium polyphosphate, and bio-based dispersant into a sand mill, grind until the particle size is less than 1 micron, and obtain a water-based flame retardant coating with a solid content of 58%-62%.

[0051] Among them, the core of coating preparation is to achieve nano-scale dispersion and functional synergy of multiple components through grinding with a sand mill. The waterborne epoxy emulsion and UV-curable epoxy acrylate in the composite resin matrix act as the continuous phase, first providing a film-forming skeleton: the hydroxyl groups of the waterborne epoxy emulsion can form hydrogen bonds with the base fabric fibers, and the double bonds of the UV-curable epoxy acrylate provide reaction sites for subsequent UV crosslinking. The phosphorus-nitrogen hybrid sodium alginate and nano-grafted lignin microspheres in the flame-retardant filler need to be ground with a sand mill to a particle size D90 ≤ 1 μm to ensure the uniform dispersion of the nano-lignin microspheres and hybrid sodium alginate in the resin and avoid uneven flame-retardant performance caused by agglomeration. The bio-based dispersant, such as oleic acid amide, adsorbs on the surface of the filler, reduces the surface tension, increases the repulsive force between the fillers, and improves the dispersion stability to no precipitation in 72 h.

[0052] The control of the solid content at 58% - 62% is crucial: if it is lower than 58%, the coating will be too thin and the flame-retardant components will be insufficient; if it is higher than 62%, the viscosity will increase sharply, affecting the spraying fluidity. For example, when the solid content is 60%, the coating exhibits shear thickening characteristics during electrostatic spraying, that is, the viscosity drops from 5000 mPa・s to 2000 mPa・s at a high shear rate, which not only ensures that the fillers do not settle statically but also ensures that the nozzle is not blocked during high-pressure spraying, laying a foundation for subsequent uniform film formation.

[0053] S3. Electrostatic-high pressure double spraying: First, use an electrostatic spray gun to spray the flame-retardant coating prepared in S2 on the surface of the activated base fabric, so that the coating penetrates into the gaps between the base fabric fibers, and the penetration depth reaches 70% - 80% of the base fabric thickness; then, after an interval of 12 hours, switch to a high-pressure airless spray gun to perform secondary spraying on the surface of the base fabric to form a dense flame-retardant coating, and the single spraying amount is controlled at 150 - 200 g / m².

[0054] Specifically, electrostatic spraying is the first process. Use an electrostatic spray gun, set the nozzle aperture to 0.4 - 0.5 mm, and control the spraying distance at 12 - 15 cm. During electrostatic spraying, the spray gun charges the coating particles, making the coating particles carry charges opposite to those of the base fabric surface. Due to the action of electrostatic attraction, the coating particles will be quickly attracted to the surface of the base fabric and penetrate into the gaps between the base fabric fibers. This electrostatic attraction is like a powerful force that can accurately introduce the coating into the deep part of the fibers, ensuring the uniform distribution of the coating inside the base fabric.

[0055] After a 12-hour interval, high-pressure airless spraying is carried out. The nozzle aperture of the high-pressure airless spray gun is set to 0.9 - 1.0 mm, and the spraying distance is controlled within 18 - 20 cm. High-pressure airless spraying can generate a relatively high pressure (18 Pa - 20 Pa), causing the coating to be sprayed onto the surface of the base fabric at a high speed. Under the action of high pressure, the coating will form a dense film layer on the surface of the base fabric. This dense film layer can further enhance the integrity and sealing of the flame retardant layer, preventing the intrusion of flames and oxygen. Through electrostatic-high pressure dual spraying, the flame retardant layer has a dual structure of "internal filling" and "surface covering". The internally filled coating enhances the adhesion between fibers and improves the overall strength of the curtain fabric; the dense film layer on the surface can quickly block the flame, playing a good flame retardant role.

[0056] S4. Gradient curing: First, irradiate the base fabric with ultraviolet light with a wavelength of 365 nm, control the ultraviolet light energy to be 900 - 1000 millijoules per square centimeter, so that the crosslinking degree of acrylate double bonds in the resin matrix reaches more than 85%; Then transfer the base fabric to a heat pump oven and keep it at a temperature of 120°C - 130°C for 15 - 20 minutes to promote the crosslinking reaction between the waterborne epoxy emulsion and the hydroxyl groups on the surface of the base fabric fibers.

[0057] Specifically, the gradient curing process is divided into two stages. The first stage is ultraviolet light curing. The base fabric is irradiated with ultraviolet light with a wavelength of 365 nm, and the energy of the ultraviolet light is controlled to be 900 - 1000 millijoules per square centimeter. In this stage, the double bonds in the UV-cured epoxy acrylate will rapidly undergo a crosslinking reaction under the action of ultraviolet light and photoinitiator, making the crosslinking degree reach more than 85%. This rapid crosslinking reaction can form an initial protective film in a short time and fix the structure of the flame retardant layer.

[0058] The second stage is heat pump low-temperature crosslinking. Transfer the base fabric cured by ultraviolet light into a heat pump oven and keep it at a temperature of 120°C - 130°C for 15 - 20 minutes. Within this temperature range, the epoxy groups in the waterborne epoxy emulsion will react with the hydroxyl groups on the surface of the base fabric fibers to form stronger chemical bond connections. At the same time, heat pump low-temperature crosslinking can also make the hydrophobic segments in the double-crosslinked modified soy protein powder align directionally, further improving the water resistance of the coating. The gradient curing process avoids damage to the base fabric caused by high temperature. For example, for cotton fiber base fabrics, if high-temperature curing is used, the cotton fibers may carbonize, resulting in a decrease in the strength and feel of the base fabric. The gradient curing process of the present invention protects the original properties of the base fabric while ensuring the curing effect of the flame retardant layer.

[0059] Further refinement, in the ultraviolet rapid curing stage, the power density of the ultraviolet lamp group is 120 W / cm, the wavelength is 365 nm, the base fabric passes through the tunnel furnace at a speed of 2.5 m / min, and the cumulative ultraviolet light energy is 950 mJ / cm², and the energy can be monitored in real time by an ultraviolet energy meter, so that the double bond crosslinking degree of the UV-cured epoxy acrylate reaches 88% through infrared spectrum detection.

[0060] In the heat pump low-temperature crosslinking stage, after ultraviolet curing, the temperature of the base fabric drops below 80 °C, and it is transferred to a heat pump type oven with an energy efficiency ratio of 3.5. It is heated to 125 °C at a rate of 10 °C / min and kept warm for 18 minutes, and then cooled to room temperature at a gradient of 5 °C / min. The internal stress in the coating is measured by laser light scattering method and is reduced by 60% compared with traditional high-temperature curing.

[0061] S5. Post-treatment strengthening: Wash the cured base fabric with warm water at 50 °C to remove surface floating materials, then immerse it in an N-methylol acrylamide solution with a concentration of 2%-3%, and keep the liquor ratio at 60%-80% through roll extrusion. Then, perform thermal crosslinking at 150 °C for 10 minutes, and finally perform a leveling treatment through a stenter to obtain the finished curtain fabric.

[0062] Furthermore, in step S2, the preparation steps of the flame retardant filler are as follows: A1. Preparation of phosphorus-nitrogen hybrid sodium alginate: The specific steps are as follows: a1: Add sodium alginate, melamine, and ammonium dihydrogen phosphate to deionized water according to the mass ratio of (3-5):(1-2):(0.5-1), and stir at 50-60 °C until completely dissolved to form a mixed solution; a2: Adjust the pH of the mixed solution to 8.5-9.5 with sodium hydroxide solution, transfer it to a reaction vessel under nitrogen protection, and mechanically stir and react at 80-90 °C for 2-3 hours, so that the carboxyl group of sodium alginate and the amino group of melamine undergo dehydration condensation to form an amide bond, and esterify with ammonium dihydrogen phosphate to generate a P-O-C bond; a3: Dialyze the reacted solution for 48 hours to remove small molecule impurities, and then spray-dry to obtain a white powder with a phosphorus content of 9%-11%, a nitrogen content of 11%-13%, a char residue rate at 500 °C ≥ 35%, and a flame retardant active group formed by P-O-C bonds and C-N bonds in the molecular structure.

[0063] Through the above steps, melamine and ammonium dihydrogen phosphate undergo an amidation + esterification reaction with sodium alginate under alkaline conditions, and a nitrogen heterocycle and a phosphoryl group are introduced into the molecular chain, so that the char residue rate at 500 °C is increased from 22% to more than 35%. During combustion, the nitrogen heterocycle decomposes to produce non-combustible gases such as ammonia and nitrogen, diluting the oxygen concentration; the phosphoryl group catalyzes the carbonization of organic substances such as lignin to form a phosphorus-containing expanded carbon layer, realizing the synergy of "gas-phase dilution + condensed-phase barrier", and the flame retardant efficiency is increased by 40% compared with single sodium alginate.

[0064] A2. Preparation of nano-grafted lignin microspheres: The specific steps are as follows: b1: Nanonization of lignin: Mix industrial lignin with sulfuric acid solution at a mass ratio of 1:(8 - 10), and crush for 2 - 3 hours under the conditions of ultrasonic power of 500 - 800W and frequency of 40kHz until the average particle size of lignin particles reaches 50 - 80 nanometers; b2: Surface grafting reaction: Add 10% - 15% of hydroxyacrylate and 1% - 2% of potassium persulfate initiator based on the mass of lignin to the nanonized lignin suspension, and stir and react in a water bath at 60 - 70°C for 3 - 4 hours to cause the grafting reaction between the hydroxyl groups on the lignin surface and the double bonds of hydroxyacrylate, forming a modified layer containing acrylate active groups; b3: Solid - liquid separation and drying: After the reaction, separate the solid particles by centrifugation, wash 3 times with deionized water to remove unreacted reagents, and finally obtain surface - grafted nano - lignin microspheres by spray drying.

[0065] Through the above process, ultrasonic crushing refines lignin from the micron level to 50 - 80nm, the specific surface area increases from 20m² / g to 85m² / g, and the reaction activity increases significantly; the grafting of hydroxyacrylate balances the hydrophilic - hydrophobic properties of the lignin surface, which can form hydrogen bonds with the hydroxyl groups of the water - based epoxy emulsion and can also undergo esterification reactions with the double bonds of UV - curable epoxy acrylate, increasing the interfacial adhesion by 60%. The dual treatment of nanonization and grafting makes lignin disperse evenly in the resin, the carbon layer continuity increases from 60% to 95%, and the oxygen isolation efficiency increases by 40%.

[0066] In a possible implementation manner, in step S3, the nozzle aperture of the electrostatic spray gun is 0.4 - 0.5mm, and the spraying distance is 12 - 15cm; the nozzle aperture of the high - pressure airless spray gun is 0.9 - 1.0mm, and the spraying distance is 18 - 20cm.

[0067] Furthermore, in the preparation step of the S2 flame - retardant coating, a photo - initiator is also added. The photo - initiator is 1 - hydroxycyclohexyl phenyl ketone, and its addition amount is 2% - 3% of the composite resin matrix. 1 - hydroxycyclohexyl phenyl ketone decomposes under ultraviolet light to generate benzoyl radicals, initiating a chain cross - linking reaction, with the curing efficiency being more than 3 times higher than that of traditional thermal curing, and the curing temperature is only 60°C, far lower than 210°C of epoxy resin, protecting the base fabric fibers from high - temperature damage.

[0068] Example 1 The raw material ratio of the flame - retardant layer is as follows: 42 parts of composite resin matrix, including 12 parts of water - based epoxy emulsion and 30 parts of UV - curable epoxy acrylate; 50 parts of flame retardant filler, including 20 parts of phosphorus-nitrogen hybrid sodium alginate and 30 parts of nano-grafted lignin microspheres; 200 parts of amphiphilic film-forming agent; 12 parts of ammonium polyphosphate; 3 parts of oleic acid amide dispersant; 2 parts of nano-titanium dioxide.

[0069] On the basis of the above raw material ratio in the flame retardant layer, the production process of the curtain fabric is as follows: S1. Activation treatment of the base fabric: Select a polyester high-density knitted fabric, immerse it in a 1.0% cetyltrimethylammonium chloride solution, and use a rolling mill to extrude to a liquor pickup rate of 75%. Dry it in an oven at 110°C for 20 minutes, and detect the surface potential of the base fabric with a Zeta potentiometer to +18 mV to ensure that it is positively charged to adsorb the negatively charged flame retardant coating.

[0070] S2. Preparation of the flame retardant coating: Put the composite resin matrix, flame retardant filler, amphiphilic film-forming agent, ammonium polyphosphate, oleic acid amide and nano-titanium dioxide into a sand mill, add zirconium beads with a diameter of 0.3 mm, and grind at 1500 revolutions per minute for 3 hours until the particle size D90 detected by a laser particle size analyzer is 0.8 μm to obtain an aqueous coating with a solid content of 60%, and adjust the pH value to 7.8.

[0071] S3. Electrostatic-high pressure double spraying: Primary electrostatic spraying: Use an electrostatic spray gun with a nozzle aperture of 0.45 mm, spraying voltage of 9 kV, pressure of 7 Pa, and spraying distance of 13 cm, so that the coating penetrates the fiber gaps of the base fabric directionally under the action of the electrostatic field. Observe the penetration depth through a scanning electron microscope to reach 75% of the base fabric thickness, and let it stand for 12 hours to allow the coating to be preliminarily adsorbed.

[0072] Secondary high-pressure spraying: Replace it with a high-pressure airless spray gun with a nozzle aperture of 1.0 mm, pressure of 19 Pa, spraying distance of 19 cm, and control the single spraying amount to 180 g / m² to form a dense coating with a thickness of 0.12 mm on the surface of the base fabric to ensure uniform distribution of the flame retardant components in the inner and outer layers.

[0073] S4. Gradient curing treatment: UV rapid curing: Pass the sprayed base fabric through an ultraviolet tunnel furnace, use a 365 nm ultraviolet lamp group, control the conveyor belt speed at 2.5 m / min, so that the cumulative ultraviolet light energy reaches 950 mJ / cm², and the double bond crosslinking degree of epoxy acrylate reaches 88% detected by infrared spectroscopy to form an initial protective film.

[0074] Heat pump low-temperature crosslinking: Transfer it to a heat pump oven, keep it warm at 125°C and a humidity of 25% for 18 minutes to promote the reaction between the water-based epoxy emulsion and the hydroxyl groups of the base fabric fibers. When cooling, cool it down to room temperature at a gradient of 5°C / min to reduce the internal stress in the coating.

[0075] S5. Post-treatment strengthening: The solidified base fabric is washed with warm water at 50 °C for 5 minutes, with a bath ratio of 1:15 to remove the surface floating materials, immersed in an N-methylolacrylamide solution with a concentration of 2.5%, the nip ratio is controlled at 70%, and heat cross-linked in an oven at 150 °C for 10 minutes to form covalent bonds between the amide groups and the amino groups of soy protein and the carboxyl groups of sodium alginate; finally, it is leveled by a stenter setting machine at a set temperature of 150 °C and a vehicle speed of 10 m / min to obtain the finished product.

[0076] Example 2 On the basis of Example 1, the dosage of nano-titanium dioxide is increased to 3 parts, and the rest of the formula and process are the same as in Example 1.

[0077] Comparative Example 1 On the basis of Example 1, in the raw material ratio of the flame-retardant layer, 20 parts of ordinary sodium alginate are used to replace the phosphorus-nitrogen hybrid sodium alginate, and the other components and the production process remain unchanged.

[0078] Comparative Example 2 On the basis of Example 1, the nano-grafted lignin microspheres in the flame-retardant filler are replaced with ordinary lignin, and the other components and the production process remain unchanged.

[0079] Comparative Example 3 The curtain fabric is produced by the traditional flame-retardant impregnation method, and its raw material composition is as follows: 42 parts of epoxy resin; 50 parts of flame-retardant filler, including 20 parts of sodium alginate and 30 parts of micronized lignin; 200 parts of unmodified soy protein powder; 5 parts of polyvinyl alcohol as a traditional dispersant; 12 parts of triphenyl phosphate as a phosphorus-based flame retardant; Its production process is as follows: Base fabric treatment: The polyester high-density knitted fabric is directly immersed in an aqueous solution containing a common flame retardant (solid content 30%, containing 20 parts of sodium alginate, 30 parts of micronized lignin, 42 parts of epoxy resin, and 5 parts of polyvinyl alcohol), the soaking time is 30 minutes, there is no nip roll extrusion control, and the nip ratio is about 60% after natural draining.

[0080] Primary drying: Put it into an electrically heated oven and dry it at 150 °C for 30 minutes without activation treatment. There is no charge induction on the surface of the base fabric, and the flame retardant is only physically adsorbed through the pores of the fiber, and the penetration depth is only 30%-50%.

[0081] Post-treatment: There is no spraying, cross-linking, and setting process, and the finished product is directly cut.

[0082] By testing various indicators of the curtain fabrics produced in Example 1, Example 2, and Comparative Examples 1, 2, and 3, the following data result comparison table was obtained: Among them, the experimental methods and steps are as follows: I. Limiting Oxygen Index (LOI) Test Standard basis: GB / T5454-1997 "Textiles - Burning performance - Oxygen index method" Purpose: To determine the minimum oxygen concentration required for the curtain fabric to maintain combustion and evaluate the flame retardant performance.

[0083] Steps: Specimen preparation: Cut 5 specimens with dimensions of 100mm×6mm from the finished curtain fabric, fix both ends with metal clips to ensure no wrinkles when vertically suspended.

[0084] Instrument setting: Use an oxygen index tester to adjust the total flow rate of the oxygen-nitrogen mixed gas to 10L / min, and set the initial oxygen concentration to 30% (volume ratio).

[0085] Ignition and observation: Ignite the top end of the specimen with an igniter for 10 seconds, and observe the combustion phenomenon. If the specimen burns continuously for 3 minutes or the burning length exceeds 50mm, reduce the oxygen concentration by 5%; if it does not burn continuously, increase the oxygen concentration by 5% until the minimum oxygen concentration (accuracy 0.1%) to maintain combustion is found.

[0086] Data processing: Take the average value of 5 tests and calculate the limiting oxygen index (LOI). The formula is: LOI = oxygen flow rate / (oxygen flow rate + nitrogen flow rate) * 100%.

[0087] II. Washability Performance Test Standard basis: AATCC135-2020 "Dimensional changes of home textiles after home laundering" Purpose: To evaluate the ability of the curtain fabric to maintain its flame retardant performance after multiple washes.

[0088] Steps: Washing conditions: Use a household washing machine (load 5kg), the washing liquid is warm water at 40°C, add 0.5% neutral detergent (such as AATCC standard detergent WOB), and the bath ratio is 1:30 (specimen mass: washing liquid volume).

[0089] Washing process: Wash 20 times, and each washing program is: pre-wash for 10 minutes → main wash for 30 minutes → rinse 2 times (15 minutes each time) → dehydration (rotation speed 800 revolutions per minute, 5 minutes).

[0090] Performance detection: After each wash, the specimen is naturally dried at room temperature for 24 hours, and the LOI after washing is detected according to the above LOI test method, and the retention rate is calculated: LOI retention rate = LOI after washing / initial LOI * %.

[0091] III. Tensile Elongation at Break Test Standard basis: GB / T 3923.1 - 2013 "Textiles - Tensile properties of fabrics - Part 1: Determination of maximum force and elongation at break (strip method)" Purpose: To evaluate the flexibility and mechanical properties of the curtain fabric coating.

[0092] Steps: Specimen preparation: Cut 5 specimens with dimensions of 200 mm × 50 mm, gauge length 100 mm, and mark the clamping area with a marker pen.

[0093] Instrument settings: Use a universal material testing machine, with a distance between clamps of 100 mm, a tensile speed of 50 mm / min, and a pre - tension of 2 N.

[0094] Testing process: Start the testing machine, record the maximum tensile force and elongation at the moment of specimen fracture, and calculate the tensile elongation at break: Tensile elongation at break = (gauge length at break - initial gauge length) / initial gauge length × 100%.

[0095] Data processing: Take the average of 5 tests, accurate to 1%.

[0096] IV. Analysis of Carbon Layer Morphology and Thickness Instrument: Scanning electron microscope; Purpose: To observe the continuity, thickness, and filler distribution of the carbon layer after combustion.

[0097] Steps: Specimen preparation: Cut a 10 mm × 10 mm cross - section of the carbon layer from the burned curtain fabric, fix it on the sample stage with conductive adhesive, and spray gold on the surface (thickness about 10 nm) to enhance conductivity.

[0098] Observation parameters: Accelerating voltage 15 kV, magnification 5000 times, observe 5 different fields of view (each field of view area is 0.1 mm²).

[0099] Data recording: Carbon layer thickness: Measure the distance between the thinnest part of the carbon layer and the surface of the base fabric in each field of view, and take the average value (accuracy 1 μm).

[0100] Carbon layer continuity: Calculate the percentage of the area of the continuous carbon layer in the total observed area (continuous is defined as no fracture of the carbon layer and thickness ≥ 5 μm).

[0101] V. Energy Consumption Calculation Method Purpose: To quantify the energy consumption in the production process and compare the energy - saving effects of different processes.

[0102] Steps: Process power consumption record: Base fabric activation: Record the power (kW) and time (h) of the drying oven, e.g., drying at 110°C for 20 minutes with a power of 10 kW.

[0103] Coating preparation: The power of the sand mill is 50 kW and the grinding time is 3 hours.

[0104] Dual spraying: The total running time of the electrostatic spray gun (10 kW) and the high-pressure spray gun (20 kW) is 1 hour.

[0105] Gradient curing: UV curing machine power 80 kW (running for 0.5 hours) + heat pump oven power 50 kW (running for 0.33 hours).

[0106] Post-treatment: The power of the stentering and setting machine is 100 kW and it runs for 0.25 hours.

[0107] Calculation of energy consumption per square meter: Energy consumption per square meter = total power consumption of each process / production area per batch.

[0108] Note: The traditional dipping method only records the electrothermal drying process (150°C, 30 minutes, power 150 kW).

[0109] VI. VOC Emission Detection Standard basis: HJ / T400 - 2007 "Sampling and Determination Methods for Volatile Organic Compounds and Aldehydes and Ketones in Motor Vehicles" Purpose: To detect the content of volatile organic compounds (VOC) in the coating.

[0110] Steps: Specimen treatment: Take 10 g of curtain fabric, cut it into pieces, put it into a headspace vial, and equilibrate at 60°C for 30 minutes.

[0111] Instrumental analysis: Use a gas chromatography - mass spectrometry (GC - MS) instrument, capillary column (DB - 5MS, 30 m × 0.25 mm × 0.25 μm), programmed temperature rise (hold at 40°C for 5 minutes, rise to 250°C at 10°C / min), and detect the total amount of VOC (calculated as toluene).

[0112] VII. Dispersion Stability Test Purpose: To evaluate the dispersion uniformity of nano - fillers in the flame - retardant coating.

[0113] Steps: Specimen preparation: Pour the coating into a 100 - ml graduated cylinder, seal it, and let it stand at a constant temperature of 25°C for 72 hours.

[0114] Observation and record: Visually observe whether there is stratification. Take 50 ml of the supernatant with a pipette, detect the remaining filler particle size through a laser particle size analyzer, and calculate the precipitation rate: Precipitation rate = precipitation mass / total coating mass * 100%.

[0115] The above experimental methods strictly follow national standards and industry norms. Through quantitative testing (such as LOI, elongation at break), microscopic analysis (SEM), and energy consumption calculation, the flame retardancy, durability, mechanical properties, and environmental protection indicators of the curtain fabric are comprehensively evaluated. Each test step is repeatable and corresponds one by one to the raw material formula and process parameters of the examples and comparative examples, ensuring the scientificity and comparability of the experimental data and providing direct evidence for the effectiveness of the technical solution.

[0116] It can be seen from the comparison of the experimental data in the following table: By comparing Example 1 with Comparative Example 1, it is obtained that the LOI of Example 1 is increased by 7.4 percentage points compared with Comparative Example 1, and the char residue rate is increased by 64.7%, which proves that the phosphorus-nitrogen groups in the phosphorus-nitrogen hybrid sodium alginate significantly enhance the flame retardancy through the dual mechanisms of "gas-phase dilution + condensed-phase carbonization". In particular, the smoldering time is shortened from 18 s to 7 s, and the smoke release amount is reduced by 25%.

[0117] By comparing Example 1 with Comparative Example 2, it is obtained that the carbon layer thickness and continuity of Example 1 are increased by 45.5% and 46.2% respectively compared with Comparative Example 2, and the elongation at break is increased by 59%, indicating that nanosizing (50 - 80 nm) and surface grafting (grafting rate of 20%) solve the problems of lignin agglomeration and embrittlement, enabling the filler and resin to form chemical bonding (ester bond), and the interfacial adhesion force is increased by 60%.

[0118] By comparing Example 1 with Comparative Example 3, it is obtained that the wash retention rate of Example 1 reaches 92%, far exceeding 65% of Comparative Example 3, attributed to the directional penetration of electrostatic spraying (depth of 75%) and post-crosslinking treatment (formation of covalent bonds by N-methylolacrylamide), and the filler loss rate is reduced from 30% to 8%. At the same time, the energy consumption is reduced by 51.7% compared with the traditional process, proving the high efficiency and energy saving of the UV curing + heat pump technology.

[0119] By comparing Example 1 with Example 2, it is obtained that the LOI of Example 2 slightly increases to 45.8%, the carbon layer thickness increases by 2.5%, and the color difference ΔE = 1.3 after 1000 h of xenon lamp aging (ΔE of Example 1 is 1.5), indicating that nano-titanium dioxide enhances flame retardancy through photocatalytic free radical assistance and improves weather resistance at the same time, and the self-cleaning ability improves the decomposition efficiency of surface pollutants by 20%.

[0120] Test items Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Limiting oxygen index (LOI) 45.2% 45.8% 37.8% 39.5% 32.0% Residual carbon rate at 500 °C 38.7% 39.2% 23.5% 28.0% 18.5% LOI retention rate after 20 times of water washing 92% 93% 75% 80% 65% Elongation at break 35% 34% 28% 22% 18% Char layer thickness (μm) 8.0 8.2 5.0 5.5 3.0 Char layer continuity 95% 96% 60% 65% 40% VOC emission (g / L) 45 44 46 47 120 Energy consumption per square meter (kWh) 0.58 0.59 0.58 0.58 1.20

[0121] In this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, it is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship are only for illustrative purposes and cannot be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0122] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application. In this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, it is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship are only for illustrative purposes and cannot be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0123] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A curtain fabric, characterized in that, It includes a base fabric and a flame retardant layer coated on the surface of the base fabric and penetrating into the fiber gaps; the flame retardant layer includes raw materials in the following parts by mass: 30 - 50 parts of a composite resin matrix, 40 - 60 parts of a flame retardant filler, 150 - 300 parts of an amphiphilic film-forming agent, 10 - 15 parts of ammonium polyphosphate, and 2 - 4 parts of a dispersant.

2. A curtain fabric according to claim 1, characterized in that, The composite resin matrix includes 10 - 15 parts of an aqueous epoxy emulsion and 20 - 35 parts of a UV-curable epoxy acrylate; The flame retardant filler includes 15 - 25 parts of a phosphorus-nitrogen hybrid sodium alginate and 25 - 35 parts of nano-grafted lignin microspheres; The amphiphilic film-forming agent is a double-crosslinked modified soy protein powder, and the double-crosslinked modified soy protein powder is prepared by alkali hydrolysis, glutaraldehyde crosslinking, and hydrophobic modification with methyl methacrylate.

3. A curtain fabric according to claim 2, characterized in that, The phosphorus-nitrogen hybrid sodium alginate contains 3 - 5 parts of sodium alginate, 1 - 2 parts of melamine, and 0.5 - 1 part of ammonium dihydrogen phosphate. The three are copolymerized for 1 - 3 hours under the conditions of a pH value of 8 - 10 and a temperature of 70 - 90 °C to obtain the phosphorus-nitrogen hybrid sodium alginate.

4. A curtain fabric according to claim 2, wherein, The average particle size of the nano-grafted lignin microspheres is 50 - 80 nanometers; based on the mass of lignin, the grafting rate of the hydroxyacrylate grafted on its surface is 18% - 22%.

5. A curtain fabric according to claim 1, wherein, The dispersant is a bio-based dispersant, and preferably oleic acid amide or castor oil polyoxyethylene ether.

6. A curtain fabric according to claim 1, wherein, 1 - 3 parts of nano-titanium dioxide are also added to the flame retardant layer.

7. A production process of a curtain fabric, which is used to prepare the curtain fabric described in any one of claims 1-6, characterized in that, It includes the following steps: S1. Activation treatment of the base fabric: Immerse the base fabric in a quaternary ammonium salt cation solution with a concentration of 0.8% - 1.2%, control the pick-up rate at 70% - 80% by roller extrusion, and then dry it at 100 - 120 °C to make the Zeta potential on the surface of the base fabric reach +15 mV to +20 mV; S2. Preparation of the flame retardant coating: Add the composite resin matrix, the flame retardant filler, the amphiphilic film-forming agent, ammonium polyphosphate, and the bio-based dispersant into a sand mill and grind until the particle size is less than 1 micron to obtain an aqueous flame retardant coating with a solid content of 58% - 62%; S3. Electrostatic-high pressure double spraying: First, use an electrostatic spray gun to spray the flame retardant coating prepared in S2 on the surface of the activated base fabric to make the coating penetrate into the fiber gaps of the base fabric, and the penetration depth reaches 70% - 80% of the thickness of the base fabric; then, after an interval of 12 hours, change to a high-pressure airless spray gun to perform secondary spraying on the surface of the base fabric to form a dense flame retardant coating, and the single spraying amount is controlled at 150 - 200 g / m²; S4. Gradient curing: First, irradiate the base fabric with ultraviolet light with a wavelength of 365 nm, control the ultraviolet light energy at 900 - 1000 mJ / cm² to make the crosslinking degree of the acrylate double bond in the resin matrix reach more than 85%; Then transfer the base fabric to a heat pump oven and keep it warm at 120 °C - 130 °C for 15 - 20 minutes to promote the crosslinking reaction between the aqueous epoxy emulsion and the hydroxyl groups on the surface of the base fabric fibers; S5. Post-treatment enhancement: Wash the solidified base fabric with warm water at 50 °C to remove surface floating materials, then immerse it in an N-methylolacrylamide solution with a concentration of 2%-3%. After squeezing with a roller to keep the pick-up rate at 60%-80%, heat crosslink it at 150 °C for 10 minutes, and finally perform a leveling treatment through a stentering machine to obtain the finished curtain fabric.

8. The production process of a curtain fabric according to claim 7, characterized in that, In step S2, the preparation steps of the flame retardant filler are as follows: A1. Preparation of phosphazene hybrid sodium alginate: The specific steps are as follows: a1: Add sodium alginate, melamine, and ammonium dihydrogen phosphate to deionized water according to the mass ratio of (3-5):(1-2):(0.5-1), and stir at 50-60 °C until completely dissolved to form a mixed solution; a2: Adjust the pH of the mixed solution to 8.5-9.5 with sodium hydroxide solution, transfer it to a reaction vessel protected by nitrogen, and mechanically stir and react at 80-90 °C for 2-3 hours to dehydrate and condense the carboxyl group of sodium alginate and the amino group of melamine to form an amide bond, and esterify with ammonium dihydrogen phosphate to generate a P-O-C bond; a3: Dialyze the reacted solution for 48 hours to remove small molecule impurities, and then obtain a white powder by spray drying. Its phosphorus content is 9%-11%, nitrogen content is 11%-13%, the char residue rate at 500 °C ≥ 35%, and the molecular structure contains a flame retardant active group formed by a P-O-C bond and a C-N bond; A2. Preparation of nano-grafted lignin microspheres: The specific steps are as follows: b1: Lignin nano-treatment: Mix industrial lignin and sulfuric acid solution according to the mass ratio of 1:(8-10), and crush it under the conditions of ultrasonic power of 500-800 W and frequency of 40 kHz for 2-3 hours until the average particle size of lignin particles reaches 50-80 nanometers; b2: Surface grafting reaction: Add 10%-15% of hydroxyacrylate and 1%-2% of potassium persulfate initiator based on the mass of lignin to the nano-lignin suspension, and stir and react in a water bath at 60-70 °C for 3-4 hours to graft the hydroxyl group on the surface of lignin and the double bond of hydroxyacrylate to form a modified layer containing acrylate active groups; b3: Solid-liquid separation and drying: After the reaction, centrifuge to separate solid particles, wash with deionized water 3 times to remove unreacted reagents, and finally obtain surface-grafted nano-lignin microspheres by spray drying.

9. The production process of a curtain fabric according to claim 7, characterized in that, In step S3, the nozzle aperture of the electrostatic spray gun is 0.4-0.5 mm, and the spraying distance is 12-15 cm; the nozzle aperture of the high-pressure airless spray gun is 0.9-1.0 mm, and the spraying distance is 18-20 cm.

10. A production process of a curtain fabric according to claim 7, characterized in that, In the preparation steps of the flame retardant coating in S2, a photoinitiator is also added. The photoinitiator is 1-hydroxycyclohexyl phenyl ketone, and its addition amount is 2%-3% of the composite resin matrix.