Preparation process of tritium-proof composite fabric

Abstract

The application discloses a preparation process of a tritium-proof composite fabric, and relates to the field of fabric preparation. In the preparation process of the tritium-proof composite fabric, non-woven fabric is used as an intermediate layer, polyvinylidene chloride film layers and modified chlorinated polyethylene film layers are sequentially covered on two surfaces of the intermediate layer, and the layers are bonded through modified adhesive film hot rolling; the modified chlorinated polyethylene film is prepared by the following steps: in-situ grafting 2-chloro-6-vinylpyridine on a polyethylene film surface, reacting with resorcinol, and then reacting with aminomethyltrimethylsilane; the modified adhesive film is prepared by the following steps: copolymerizing vinyl acetate, ethylene and a vinyl quaternary ammonium salt, then reacting with 2-tert-butylphenol, and then granulating and molding into a film; and the tritium-proof composite fabric prepared by the application has excellent anti-aging performance, mechanical properties and tritium-proof performance.

Description

Technical Field

[0001] This invention relates to the field of fabric preparation technology, specifically to a preparation process for a tritium-resistant composite fabric. Background Technology

[0002] With the increasing prevalence of tritium in both military and civilian applications, the development of tritium-proof materials has become a hot research topic in the field of tritium protection. Tritium gas and tritium water easily adsorb onto the surface of materials and then penetrate into the human body. Current tritium-proof materials have gradually shifted from materials such as natural rubber and neoprene rubber towards polymer materials. However, single polymer materials have limited performance, so researchers have focused their research on composite materials composed of polymer materials.

[0003] In personal tritium protective materials such as gloves and protective clothing, the fabric is the main component. Traditional single-component fabrics have poor tritium protection performance and cannot meet the protection requirements. The tritium protection performance of the fabric can be improved by compounding it with other polymer materials. However, the fabric is prone to aging during long-term use, which leads to a decline in protective performance and mechanical properties. Therefore, improving the anti-aging performance of the fabric while ensuring its anti-permeability is an important issue in the research and development of tritium protective fabrics. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a preparation process for tritium-resistant composite fabric.

[0005] The technical solution of this invention to solve the aforementioned technical problem is to provide a preparation process for a tritium-resistant composite fabric, comprising the following preparation steps: (1) Immerse the polyethylene film in 2-chloro-6-vinylpyridine-acetone solution, let it stand for 3 hours and then take it out. Place the polyethylene film under a UV lamp with a power of 8W and a light source distance of 10cm. After passing chlorine gas at a flow rate of 0.5mL / s for 5-10 minutes, raise the temperature to 80℃ and react for 2-3 hours. Then raise the temperature to 120℃ and continue to react for 3 hours. After the reaction is completed, remove the UV lamp, stop passing chlorine gas and use a vacuum pump to evacuate for 30-40 minutes. After cooling to 100℃, pass air and use a vacuum pump to evacuate for 50-60 minutes. After cooling to room temperature, take out the film and wash it with acetone 3-4 times to obtain pyridine-chlorinated polyethylene film. (2) Resorcinol, pyridyl chlorinated polyethylene film, anhydrous aluminum trichloride, and acetone were mixed in a mass ratio of 1:(10-12):(1.2-1.3):(12-15) and reacted at 70-80℃ for 5-6 hours. The mixture was filtered and washed 3-4 times with pure water and dried at room temperature for 24 hours to obtain a pre-modified chlorinated polyethylene film. Paraformaldehyde and chloroform were mixed evenly and heated to 40℃. Calcium hydride was added and the temperature was raised to 70℃. Under nitrogen protection, aminomethyltrimethylsilane was added and the temperature was raised to 80℃. The pre-modified chlorinated polyethylene film was added and reacted for 20 hours. The mixture was then removed, washed 3 times with pure water, and dried at room temperature for 24 hours to obtain a modified chlorinated polyethylene film. (3) Mix vinyl acetate, vinyl quaternary ammonium salt, methanol, and azobisisobutyronitrile in a mass ratio of 1:(0.2-0.3):(0.7-0.8):(0.01-0.02) and put them into a high-pressure reactor. After ethylene is introduced for 5-10 min, the pressure of ethylene in the high-pressure reactor is set to 4.0 MPa. The temperature is raised to 55-60℃ and reacted at a speed of 150-200 r / min for 4-5 h. After the reaction is completed, the temperature is lowered to room temperature and the product is discharged. The product is precipitated with methanol aqueous solution, filtered and washed with pure water 3-4 times, and dried at 70℃ for 24 h to obtain quaternary ammonium salt-ethylene-vinyl acetate copolymer. (4) Mix paraformaldehyde and N,N-dimethylformamide evenly and heat to 40°C. Add calcium hydride and heat to 70°C. Then, introduce nitrogen gas and add 2-tert-butylphenol. Heat to 80°C and add quaternary ammonium salt-ethylene-vinyl acetate copolymer. After reacting for 20 hours, filter and retain the filtrate. Remove N,N-dimethylformamide by rotary evaporation under reduced pressure to obtain modified ethylene-vinyl acetate copolymer. Granulate the modified ethylene-vinyl acetate copolymer using a granulator. Use a flat vulcanizing machine to mold the granules at 90°C to obtain modified film. (5) Sand one side of the nonwoven fabric with sandpaper, cover it with a modified adhesive film, then cover it with a polyvinylidene chloride film, then cover it with a modified adhesive film, then cover it with a modified chlorinated polyethylene film. Repeat the above sanding-covering operation on the other side of the nonwoven fabric. Hot roll it twice on a hot rolling mill. The hot rolling mill pressure is 0.3MPa, the temperature is 140-150℃, and the time is 3min. After hot rolling, tritium-proof composite fabric is obtained.

[0006] As an optimization, the 2-chloro-6-vinylpyridine-acetone solution in step (1) is prepared by mixing 2-chloro-6-vinylpyridine and acetone in a mass ratio of 1:(5-6); the polyethylene film is of model 6098.

[0007] As an optimization, the mass ratio of paraformaldehyde, aminomethyltrimethylsilane, pre-modified chlorinated polyethylene film, calcium hydride and chloroform in step (2) is 1:(1.6-1.8):(10-12):(0.7-0.8):(20-30).

[0008] As an optimization, the preparation process of the vinyl quaternary ammonium salt in step (3) is as follows: at 0°C, N,N-dimethylethylenediamine, ditert-butyl dicarbonate, and dichloromethane are mixed at a mass ratio of 1:(0.6-0.7):(20-30) for 10-15 min, stirred at 20°C for 24 h, and pure water of equal volume to dichloromethane is added. The mixture is separated and the organic phase is retained. In the organic phase, 0.9-1.0 times the mass of N,N-dimethylethylenediamine and 0.2-0.3 times the mass of N,N-dimethylethylenediamine potassium carbonate are added, and the temperature is raised. The mixture was refluxed at 70-80℃ for 10-12 hours. After the reaction was completed, dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt precursor. The vinyl quaternary ammonium salt precursor and dichloromethane were mixed at a mass ratio of 1:(10-12) at 0-4℃. Trifluoroacetic acid, which was 5-7 times the mass of the vinyl quaternary ammonium salt precursor, was added dropwise at a rate of 1 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction was continued for 3-4 hours. After the reaction was completed, saturated sodium carbonate solution was added to adjust the pH to 9-10. Dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt.

[0009] As an optimization, the methanol-water solution in step (3) is made by mixing methanol and water in a mass ratio of 3:1.

[0010] As an optimization, the mass ratio of paraformaldehyde, 2-tert-butylphenol, quaternary ammonium salt-ethylene-vinyl acetate copolymer, calcium hydride, and N,N-dimethylformamide in step (4) is 1:(3.4-3.5):(0.2-0.3):(0.7-0.8):(20-30).

[0011] As an optimization, the thickness of the modified film in step (4) is 0.5 mm.

[0012] As an optimization, the nonwoven fabric in step (5) is model 1473R; the polyvinylidene chloride film is model VSL-4603.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: In preparing the tritium-resistant composite fabric, the present invention firstly grafts 2-chloro-6-vinylpyridine onto the surface of a polyethylene film in situ with chlorination, reacts it with resorcinol, and then reacts it with aminomethyltrimethylsilane to obtain a modified chlorinated polyethylene film; secondly, N,N-dimethylethylenediamine protected by di-tert-butyl dicarbonate is reacted with vinyl chloride, and then deprotected by trifluoroacetic acid to obtain a vinyl quaternary ammonium salt, which is then copolymerized with vinyl acetate, ethylene, and the vinyl quaternary ammonium salt and reacted with 2-tert-butylphenol, and then granulated and molded into a film to obtain a modified adhesive film; finally, using nonwoven fabric as the intermediate layer, polyvinylidene chloride film layers and modified chlorinated polyethylene film layers are sequentially covered on both sides, and the layers are bonded together by hot rolling with the modified adhesive film to obtain the tritium-resistant composite fabric; First, 2-chloro-6-vinylpyridine is grafted onto the surface of a polyethylene film in situ with chlorination, then reacted with resorcinol, and finally with aminomethyltrimethylsilane to obtain a modified chlorinated polyethylene film. Upon thermal decomposition, chlorine gas generates chlorine free radicals, which attack the molecular chains of the polyethylene film and abstract hydrogen atoms from the tertiary carbon atoms, producing macromolecular free radicals and hydrogen chloride. The carbon-carbon double bond on 2-chloro-6-vinylpyridine can react with the macromolecular free radicals. Simultaneously with chlorination, 2-chloro-6-vinylpyridine is grafted onto the surface of the polyethylene film. 2-chloro-6-vinylpyridine undergoes a Friedel-Crafts alkylation reaction with resorcinol, forming an intramolecular chelate ring between the nitrogen atom on the pyridine and the phenolic hydroxyl group at the ortho position. This ring can convert light energy into heat energy and exhibits good absorption of ultraviolet light, providing excellent UV aging resistance for tritium-resistant fabrics. Finally, the film reacts with aminomethyltrimethylsilane in the presence of paraformaldehyde to generate benzoxazine, which is then grafted with trimethylsilane. Trimethoxysilane can further improve the hydrophobicity and heat resistance of the fabric.

[0014] Secondly, N,N-dimethylethylenediamine protected by di-tert-butyl dicarbonate is reacted with vinyl chloride, and then deprotected by trifluoroacetic acid to obtain a vinyl quaternary ammonium salt. Vinyl acetate, ethylene, and the vinyl quaternary ammonium salt are copolymerized and reacted with 2-tert-butylphenol, and then granulated and molded into a film to obtain a modified adhesive film. The primary amino group on N,N-dimethylethylenediamine is protected by di-tert-butyl dicarbonate, and the tert-amino group on N,N-dimethylethylenediamine reacts with vinyl chloride to generate a vinyl-containing quaternary ammonium salt. The quaternary ammonium salt can give the fabric good antibacterial properties. Then, the protection is removed by trifluoroacetic acid to re-expose the primary amino group. The vinyl quaternary ammonium salt, ethylene, and vinyl acetate are copolymerized to form a polymer with heat melt properties. The primary amino group and 2-tert-butylphenol on the side chain of the polymer form benzoxazine functional groups in the presence of paraformaldehyde.

[0015] Finally, using nonwoven fabric as the intermediate layer, polyvinylidene chloride (PVDC) film layers and modified chlorinated polyethylene (CPE) film layers are sequentially covered on both sides. The layers are then bonded together by hot rolling with a modified adhesive film to obtain a tritium-resistant composite fabric. The modified adhesive film melts at high temperatures, increasing its fluidity and allowing it to penetrate and wet the surfaces of the nonwoven fabric, PVDC film layer, and modified CPE film layer, thus achieving adhesion between the layers. For the interlayer between the nonwoven fabric and the PVDC film layer, the benzoxazine on the side chain of the modified adhesive film undergoes ring-opening and self-crosslinking at high temperatures, forming a three-dimensional network structure. Increasing the crosslinking density further enhances the protective effect. For the PVDC film layer and the modified CPE film layer, the benzoxazine on the modified CPE undergoes ring-opening and crosslinking with the modified adhesive film at high temperatures, increasing adhesion and improving the protective effect. The benzoxazine on the modified adhesive film undergoes ring-opening to form a crosslinked structure, with one crosslinking point located on the N atom and the other crosslinked at the para position of the phenolic hydroxyl group on 2-tert-butylphenol, which can form a hindered phenolic structure, thereby endowing the fabric with resistance to thermo-oxidative aging. Detailed Implementation

[0016] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0017] The polyethylene film used in the following comparative examples is model 6098; the methanol aqueous solution used is a mixture of methanol and water in a mass ratio of 3:1; the nonwoven fabric used is model 1473R; and the polyvinylidene chloride film used is model VSL-4603.

[0018] Example 1: A tritium-resistant composite fabric includes the following preparation steps: (1) 2-chloro-6-vinylpyridine and acetone were mixed at a mass ratio of 1:5 to obtain a 2-chloro-6-vinylpyridine-acetone solution; a polyethylene film was immersed in the 2-chloro-6-vinylpyridine-acetone solution and left to stand for 3 hours before being taken out. The polyethylene film was placed under an ultraviolet lamp with a power of 8W and a light source distance of 10cm. Chlorine gas with a flow rate of 0.5mL / s was introduced for 10 minutes, and the temperature was raised to 80℃. After reacting for 3 hours, the temperature was raised to 120℃ and the reaction was continued for 3 hours. After the reaction was completed, the ultraviolet lamp was removed, the chlorine gas was stopped and a vacuum pump was used to evacuate the gas for 40 minutes. After cooling to 100℃, air was introduced and a vacuum pump was used to evacuate the gas for 60 minutes. After cooling to room temperature, the film was taken out and washed with acetone 4 times to obtain a pyridine-based chlorinated polyethylene film. (2) Resorcinol, pyridyl chlorinated polyethylene film, anhydrous aluminum trichloride, and acetone were mixed in a mass ratio of 1:10:1.2:12 and reacted at 80°C for 6 hours. The mixture was filtered and washed four times with pure water. It was then dried at room temperature for 24 hours to obtain a pre-modified chlorinated polyethylene film. Paraformaldehyde, aminomethyltrimethylsilane, pre-modified chlorinated polyethylene film, calcium hydride, and chloroform were weighed in a mass ratio of 1:1.6:10:0.7:20. Paraformaldehyde and chloroform were mixed evenly and heated to 40°C. Calcium hydride was added and the temperature was raised to 70°C. Under nitrogen protection, aminomethyltrimethylsilane was added and the temperature was raised to 80°C. The pre-modified chlorinated polyethylene film was added and reacted for 20 hours. The mixture was then removed, washed three times with pure water, and dried at room temperature for 24 hours to obtain a modified chlorinated polyethylene film. (3) At 0℃, N,N-dimethylethylenediamine, ditert-butyl dicarbonate and dichloromethane were mixed at a mass ratio of 1:0.6:20 for 15 min, stirred at 20℃ for 24 h, and pure water of equal volume to dichloromethane was added. The mixture was separated and the organic phase was retained. Vinyl chloride of 0.9 times the mass of N,N-dimethylethylenediamine and potassium carbonate of 0.2 times the mass of N,N-dimethylethylenediamine were added to the organic phase. The mixture was heated to 80℃ and refluxed for 12 h. After the reaction was completed, dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt precursor. At 4℃, the vinyl quaternary ammonium salt precursor and dichloromethane were mixed at a mass ratio of 1:10, and trifluoroacetic acid of 5 times the mass of the vinyl quaternary ammonium salt precursor was added dropwise at a rate of 1 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 hours. After the reaction was completed, saturated sodium carbonate solution was added to adjust the pH to 10, and dichloromethane was removed by rotary evaporation under reduced pressure to obtain vinyl quaternary ammonium salt. Vinyl acetate, vinyl quaternary ammonium salt, methanol, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.2:0.7:0.01 and added to a high-pressure reactor. After ethylene was introduced for 10 minutes, the pressure of ethylene in the high-pressure reactor was set to 4.0 MPa, the temperature was raised to 60°C, and the reaction was carried out at a speed of 200 r / min for 5 hours. After the reaction was completed, the temperature was lowered to room temperature and the product was discharged. Precipitation was carried out using methanol aqueous solution, filtered and washed 4 times with pure water, and dried at 70°C for 24 hours to obtain quaternary ammonium salt-ethylene-vinyl acetate copolymer. (4) Weigh out paraformaldehyde, 2-tert-butylphenol, quaternary ammonium salt-ethylene-vinyl acetate copolymer, calcium hydride, and N,N-dimethylformamide in a mass ratio of 1:3.4:0.2:0.7:20. Mix paraformaldehyde and N,N-dimethylformamide evenly and heat to 40°C. Add calcium hydride and heat to 70°C. Then, introduce nitrogen gas and add 2-tert-butylphenol. Heat to 80°C and add quaternary ammonium salt-ethylene-vinyl acetate copolymer. After reacting for 20 hours, filter and retain the filtrate. Remove N,N-dimethylformamide by rotary evaporation under reduced pressure to obtain modified ethylene-vinyl acetate copolymer. Granulate the modified ethylene-vinyl acetate copolymer using a granulator. Use a flat vulcanizing machine to mold the granules at 90°C to obtain a modified film with a thickness of 0.5 mm. (5) Sand one side of the nonwoven fabric with sandpaper, cover it with a modified adhesive film, then cover it with a polyvinylidene chloride film, then cover it with a modified adhesive film, then cover it with a modified chlorinated polyethylene film. Repeat the above sanding-covering operation on the other side of the nonwoven fabric. Hot roll it twice on a hot rolling mill. The hot rolling mill pressure is 0.3MPa, the temperature is 150℃, and the time is 3min. After hot rolling, tritium-proof composite fabric is obtained.

[0019] Example 2: A tritium-resistant composite fabric includes the following preparation steps: (1) 2-chloro-6-vinylpyridine and acetone were mixed at a mass ratio of 1:5.5 to obtain a 2-chloro-6-vinylpyridine-acetone solution; a polyethylene film was immersed in the 2-chloro-6-vinylpyridine-acetone solution and left to stand for 3 hours before being taken out. The polyethylene film was placed under an ultraviolet lamp with a power of 8W and a light source distance of 10cm. Chlorine gas with a flow rate of 0.5mL / s was introduced for 7 minutes, and the temperature was raised to 80℃. After reacting for 2.5 hours, the temperature was raised to 120℃ and the reaction was continued for 3 hours. After the reaction was completed, the ultraviolet lamp was removed, the chlorine gas was stopped and the vacuum pump was used to evacuate the air for 35 minutes. After cooling to 100℃, air was introduced and the vacuum pump was used to evacuate the air for 55 minutes. After cooling to room temperature, the film was taken out and washed three times with acetone to obtain a pyridine-based chlorinated polyethylene film. (2) Resorcinol, pyridyl chlorinated polyethylene film, anhydrous aluminum trichloride, and acetone were mixed in a mass ratio of 1:11:1.25:13 and reacted at 75°C for 5.5 h. The mixture was filtered and washed three times with pure water and dried at room temperature for 24 h to obtain a pre-modified chlorinated polyethylene film. Paraformaldehyde, aminomethyltrimethylsilane, pre-modified chlorinated polyethylene film, calcium hydride, and chloroform were weighed in a mass ratio of 1:1.5:11:0.75:25. Paraformaldehyde and chloroform were mixed evenly and heated to 40°C. Calcium hydride was added and the temperature was raised to 70°C. Under nitrogen protection, aminomethyltrimethylsilane was added and the temperature was raised to 80°C. The pre-modified chlorinated polyethylene film was added and reacted for 20 h. The mixture was then removed, washed three times with pure water, and dried at room temperature for 24 h to obtain a modified chlorinated polyethylene film. (3) At 0℃, N,N-dimethylethylenediamine, ditert-butyl dicarbonate, and dichloromethane were mixed at a mass ratio of 1:0.65:25 for 13 min, stirred at 20℃ for 24 h, and pure water of equal volume to dichloromethane was added. The mixture was separated and the organic phase was retained. Vinyl chloride (0.95 times the mass of N,N-dimethylethylenediamine) and potassium carbonate (0.25 times the mass of N,N-dimethylethylenediamine) were added to the organic phase. The mixture was heated to 75℃ and refluxed for 11 h. After the reaction was completed, dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt precursor. At 3℃, the vinyl quaternary ammonium salt precursor and dichloromethane were mixed at a mass ratio of 1:11, and trifluoroacetic acid (6 times the mass of the vinyl quaternary ammonium salt precursor) was added dropwise at a rate of 1 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 3.5 hours. After the reaction was completed, saturated sodium carbonate solution was added to adjust the pH to 9.5, and dichloromethane was removed by rotary evaporation under reduced pressure to obtain vinyl quaternary ammonium salt. Vinyl acetate, vinyl quaternary ammonium salt, methanol, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.25:0.75:0.015 and added to a high-pressure reactor. After ethylene was introduced for 7 minutes, the pressure of ethylene in the high-pressure reactor was set to 4.0 MPa, the temperature was raised to 57°C, and the reaction was carried out at a speed of 170 r / min for 4.5 hours. After the reaction was completed, the temperature was lowered to room temperature and the product was discharged. Precipitation was carried out using methanol aqueous solution, filtered and washed three times with pure water, and dried at 70°C for 24 hours to obtain quaternary ammonium salt-ethylene-vinyl acetate copolymer. (4) Weigh out paraformaldehyde, 2-tert-butylphenol, quaternary ammonium salt-ethylene-vinyl acetate copolymer, calcium hydride, and N,N-dimethylformamide in a mass ratio of 1:3.45:0.25:0.75:25. Mix paraformaldehyde and N,N-dimethylformamide evenly and heat to 40°C. Add calcium hydride and heat to 70°C. Then, introduce nitrogen gas and add 2-tert-butylphenol. Heat to 80°C and add quaternary ammonium salt-ethylene-vinyl acetate copolymer. After reacting for 20 hours, filter and retain the filtrate. Remove N,N-dimethylformamide by rotary evaporation under reduced pressure to obtain modified ethylene-vinyl acetate copolymer. Granulate the modified ethylene-vinyl acetate copolymer using a granulator. Use a flat vulcanizing machine to mold the granules at 90°C to obtain a modified film with a thickness of 0.5 mm. (5) Sand one side of the nonwoven fabric with sandpaper, cover it with a modified adhesive film, then cover it with a polyvinylidene chloride film, then cover it with a modified adhesive film, then cover it with a modified chlorinated polyethylene film. Repeat the above sanding-covering operation on the other side of the nonwoven fabric. Hot roll it three times on a hot rolling mill. The hot rolling mill pressure is 0.3MPa, the temperature is 145℃, and the time is 3min. After hot rolling, tritium-proof composite fabric is obtained.

[0020] Example 3: A tritium-resistant composite fabric includes the following preparation steps: (1) 2-chloro-6-vinylpyridine and acetone were mixed at a mass ratio of 1:6 to obtain a 2-chloro-6-vinylpyridine-acetone solution; a polyethylene film was immersed in the 2-chloro-6-vinylpyridine-acetone solution and left to stand for 3 hours before being taken out. The polyethylene film was placed under an ultraviolet lamp with a power of 8W and a light source distance of 10cm. Chlorine gas with a flow rate of 0.5mL / s was introduced for 5 minutes, and the temperature was raised to 80℃. After reacting for 2 hours, the temperature was raised to 120℃ and the reaction was continued for 3 hours. After the reaction was completed, the ultraviolet lamp was removed, the chlorine gas was stopped, and a vacuum pump was used to evacuate the air for 30 minutes. After cooling to 100℃, air was introduced and a vacuum pump was used to evacuate the air for 50 minutes. After cooling to room temperature, the film was taken out and washed three times with acetone to obtain a pyridine-based chlorinated polyethylene film. (2) Resorcinol, pyridyl chlorinated polyethylene film, anhydrous aluminum trichloride, and acetone were mixed in a mass ratio of 1:12:1.3:15 and reacted at 70°C for 5 hours. The mixture was filtered and washed three times with pure water. It was then dried at room temperature for 24 hours to obtain a pre-modified chlorinated polyethylene film. Paraformaldehyde, aminomethyltrimethylsilane, pre-modified chlorinated polyethylene film, calcium hydride, and chloroform were weighed in a mass ratio of 1:1.8:12:0.8:30. Paraformaldehyde and chloroform were mixed evenly and heated to 40°C. Calcium hydride was added and the temperature was raised to 70°C. Under nitrogen protection, aminomethyltrimethylsilane was added and the temperature was raised to 80°C. The pre-modified chlorinated polyethylene film was added and reacted for 20 hours. The mixture was then removed, washed three times with pure water, and dried at room temperature for 24 hours to obtain a modified chlorinated polyethylene film. (3) At 0℃, N,N-dimethylethylenediamine, ditert-butyl dicarbonate, and dichloromethane were mixed at a mass ratio of 1:0.7:30 for 10 min, stirred at 20℃ for 24 h, and pure water of equal volume to dichloromethane was added. The mixture was separated and the organic phase was retained. Vinyl chloride of 1.0 times the mass of N,N-dimethylethylenediamine and potassium carbonate of 0.3 times the mass of N,N-dimethylethylenediamine were added to the organic phase. The mixture was heated to 70℃ and refluxed for 10 h. After the reaction was completed, dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt precursor. At 0℃, the vinyl quaternary ammonium salt precursor and dichloromethane were mixed at a mass ratio of 1:12, and trifluoroacetic acid of 7 times the mass of the vinyl quaternary ammonium salt precursor was added dropwise at a rate of 1 mL / min. After the addition of n, the temperature was raised to room temperature and the reaction continued for 3 hours. After the reaction was completed, saturated sodium carbonate solution was added to adjust the pH to 9, and dichloromethane was removed by rotary evaporation under reduced pressure to obtain vinyl quaternary ammonium salt. Vinyl acetate, vinyl quaternary ammonium salt, methanol, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.3:0.8:0.02 and put into a high-pressure reactor. After ethylene was introduced for 5 minutes, the pressure of ethylene in the high-pressure reactor was set to 4.0 MPa, the temperature was raised to 55°C, and the reaction was carried out at a speed of 150 r / min for 4 hours. After the reaction was completed, the temperature was lowered to room temperature and the product was discharged. Precipitation was carried out using methanol aqueous solution, filtered and washed 3 times with pure water, and dried at 70°C for 24 hours to obtain quaternary ammonium salt-ethylene-vinyl acetate copolymer. (4) Weigh out paraformaldehyde, 2-tert-butylphenol, quaternary ammonium salt-ethylene-vinyl acetate copolymer, calcium hydride, and N,N-dimethylformamide in a mass ratio of 1:3.5:0.3:0.8:30. Mix paraformaldehyde and N,N-dimethylformamide evenly and heat to 40°C. Add calcium hydride and heat to 70°C. Then, introduce nitrogen gas and add 2-tert-butylphenol. Heat to 80°C and add quaternary ammonium salt-ethylene-vinyl acetate copolymer. After reacting for 20 hours, filter and retain the filtrate. Remove N,N-dimethylformamide by rotary evaporation under reduced pressure to obtain modified ethylene-vinyl acetate copolymer. Granulate the modified ethylene-vinyl acetate copolymer using a granulator. Use a flat vulcanizing machine to mold the granules at 90°C to obtain a modified film with a thickness of 0.5 mm. (5) Sand one side of the nonwoven fabric with sandpaper, cover it with a modified adhesive film, then cover it with a polyvinylidene chloride film, then cover it with a modified adhesive film, then cover it with a modified chlorinated polyethylene film. Repeat the above sanding-covering operation on the other side of the nonwoven fabric. Hot roll it twice on a hot rolling mill. The hot rolling mill pressure is 0.3MPa, the temperature is 140℃, and the time is 3min. After hot rolling, tritium-proof composite fabric is obtained.

[0021] Comparative Example 1: The difference between the preparation process of the tritium-resistant composite fabric in Comparative Example 1 and Example 2 is that step (2) is omitted. Step (1) is modified as follows: 2-chloro-6-vinylpyridine and acetone are mixed at a mass ratio of 1:5.5 to obtain a 2-chloro-6-vinylpyridine-acetone solution; a polyethylene film is immersed in the 2-chloro-6-vinylpyridine-acetone solution, left to stand for 3 hours, and then removed. The removed polyethylene film is placed under an ultraviolet lamp with a power of 8W and a light source distance of 10cm. Chlorine gas with a flow rate of 0.5mL / s is introduced for 7 minutes, and then the temperature is raised to 80℃. After reacting for 2.5 hours, the temperature is raised to 120℃ and the reaction continues for 3 hours. After the reaction is completed, the ultraviolet lamp is removed, the chlorine gas is stopped, and a vacuum pump is used to evacuate the air for 35 minutes. After cooling to 100℃, air is introduced and a vacuum pump is used to evacuate the air for 55 minutes. After cooling to room temperature, the film is removed and washed three times with acetone to obtain a modified chlorinated polyethylene film.

[0022] Comparative Example 2: The difference between the preparation process of the tritium-resistant composite fabric in Comparative Example 2 and Example 2 is that step (2) is modified as follows: resorcinol, pyridyl chloride polyethylene film, anhydrous aluminum trichloride and acetone are mixed in a mass ratio of 1:11:1.25:13, reacted at 75°C for 5.5 h, filtered and washed 3 times with pure water, and dried at room temperature for 24 h to obtain modified chlorinated polyethylene film.

[0023] Comparative Example 3: The difference between the preparation process of the tritium-resistant composite fabric in Comparative Example 3 and Example 2 is that step (4) is modified to use a granulator to granulate the quaternary ammonium salt-ethylene-vinyl acetate copolymer, and use a flat vulcanizing machine to mold the granules at 90°C to obtain a modified film with a thickness of 0.5 mm.

[0024] Test Example 1: Mechanical property testing: Test Method: Standard samples of the tritium-resistant composite fabrics prepared in the examples and comparative examples were made according to standard GB / T 3923.1. The breaking strength of the samples was determined using a YG(B)026HC-500 fabric tensile testing machine. The clamping distance was 200 mm, the speed was 100 mm / min, the sample width was 50.00 mm, the ambient temperature was (20±3)℃, and the relative humidity was (65±5)%. The peel strength between the polyvinylidene chloride film and the modified chlorinated polyethylene layer of the tritium-resistant fabrics prepared in the examples and comparative examples was tested using a YG(B)026HC-500 fabric tensile testing machine according to standard FZ / T 01085-2009. The results are shown in Table 1.

[0025] Table 1

[0026] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 1 reveals that the tritium-resistant composite fabric prepared by this invention has excellent mechanical properties.

[0027] By comparison, the tensile strength of Examples 1-3 is greater than that of Comparative Examples 1-3, and the peel strength between the polyvinylidene chloride film and the modified chlorinated polyethylene layer in Examples 1-3 is greater than that in Comparative Examples 1-3. This indicates that a tritium-resistant composite fabric is obtained by using nonwoven fabric as the intermediate layer, with polyvinylidene chloride film layer and modified chlorinated polyethylene film layer successively covered on both sides, and the layers are bonded together by hot rolling with modified adhesive film. The modified adhesive film melts at high temperature, increases fluidity, and can penetrate and wet the surfaces of nonwoven fabric, polyvinylidene chloride film layer and modified chlorinated polyethylene film layer, thereby enabling adhesion between layers. For the interlayer between nonwoven fabric and polyvinylidene chloride film layer, the benzoxazine on the side chain of the modified adhesive film undergoes ring opening and self-crosslinking at high temperature, forming a three-dimensional network structure and increasing the crosslinking density.

[0028] Test Example 2: Testing for UV aging resistance: Test method: All tritium-resistant composite fabrics prepared in the examples and comparative examples were laid flat on a sample holder, which was placed parallel to the ultraviolet lamp tube inside the ultraviolet lamp box with a radiation intensity of 1100 W / m. 2The chamber temperature was 60℃, the humidity was 60%, the fabric was 10cm away from the lamp, and the irradiation time was 60h. After irradiation, the breaking strength was tested according to the mechanical property testing method, and the breaking strength retention rate was calculated. The results are shown in Table 2.

[0029] Tests on resistance to thermo-oxidative aging: Test method: All tritium-resistant composite fabrics prepared in the examples and comparative examples were laid flat on a sample holder and then placed in an aging chamber. The aging temperature was 50℃, the relative humidity was 55%, the ozone concentration was 450pphm, and the aging time was 360h. After aging, the breaking strength was tested according to the mechanical property test method, and the breaking strength retention rate was calculated. The results are shown in Table 2.

[0030] Table 2

[0031] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 2 reveals that the tritium-resistant composite fabric prepared by this invention has excellent anti-aging properties.

[0032] By comparison, the tensile strength retention rate after UV irradiation of Examples 1-3 is greater than that of Comparative Example 1, and the tensile strength retention rate after thermo-oxidative aging of Examples 1-3 is greater than that of Comparative Example 3. This indicates that, firstly, after in-situ chlorination grafting of 2-chloro-6-vinylpyridine onto the surface of the polyethylene film, the reaction with resorcinol results in an intramolecular chelate ring formed between the N atom on the pyridine and the phenolic hydroxyl group at the ortho position. This ring can convert light energy into heat energy and has a good absorption effect on ultraviolet rays, thus providing good UV aging resistance for the tritium-resistant fabric. Secondly, the benzoxazine on the modified film undergoes ring-opening to form a cross-linked structure. One end of the cross-linking point is located on the N atom, and the other end is cross-linked at the para position of the phenolic hydroxyl group on 2-tert-butylphenol, which can form a hindered phenolic structure, thereby endowing the fabric with thermo-oxidative aging resistance.

[0033] Test Example 3: Gas permeability testing: Test method: The gas permeability of the tritium-resistant composite fabrics prepared in all examples and comparative examples was tested according to standard GB / T1038-2000. Hydrogen gas was used, and the test temperature was 23℃. The results are shown in Table 3.

[0034] Table 3

[0035] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-3 in Table 3 reveals that the tritium-resistant composite fabric prepared by this invention has excellent gas permeability resistance.

[0036] By comparison, the gas permeability of Examples 1-3 is lower than that of Comparative Examples 1-3, indicating that a tritium-resistant composite fabric is obtained by using nonwoven fabric as the intermediate layer, with polyvinylidene chloride film layer and modified chlorinated polyethylene film layer successively covered on both sides, and the layers are bonded together by hot rolling with modified adhesive film. The modified adhesive film melts at high temperature, increasing its fluidity, and can penetrate and wet the surfaces of the nonwoven fabric, polyvinylidene chloride film layer and modified chlorinated polyethylene film layer, thereby achieving adhesion between the layers. For the layer between the nonwoven fabric and the polyvinylidene chloride film layer, the benzoxazine on the side chain of the modified adhesive film undergoes ring-opening and self-crosslinking at high temperature, forming a three-dimensional network structure. Increasing the crosslinking density can further improve the protective effect. For the polyvinylidene chloride film layer and the modified chlorinated polyethylene film layer, the benzoxazine on the modified chlorinated polyethylene undergoes ring-opening and crosslinking with the modified adhesive film at high temperature, increasing the adhesion and improving the protective effect.

[0037] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A preparation process for a tritium-resistant composite fabric, characterized in that, The preparation steps include the following: (1) Immerse the polyethylene film in 2-chloro-6-vinylpyridine-acetone solution, let it stand for 3 hours and then take it out. Place the polyethylene film under a UV lamp with a power of 8W and a light source distance of 10cm. After passing chlorine gas at a flow rate of 0.5mL / s for 5-10 minutes, raise the temperature to 80℃ and react for 2-3 hours. Then raise the temperature to 120℃ and continue to react for 3 hours. After the reaction is completed, remove the UV lamp, stop passing chlorine gas and use a vacuum pump to evacuate for 30-40 minutes. After cooling to 100℃, pass air and use a vacuum pump to evacuate for 50-60 minutes. After cooling to room temperature, take out the film and wash it with acetone 3-4 times to obtain pyridine-chlorinated polyethylene film. (2) Resorcinol, pyridyl chlorinated polyethylene film, anhydrous aluminum trichloride, and acetone were mixed in a mass ratio of 1:(10-12):(1.2-1.3):(12-15) and reacted at 70-80℃ for 5-6 hours. The mixture was filtered and washed 3-4 times with pure water and dried at room temperature for 24 hours to obtain a pre-modified chlorinated polyethylene film. Paraformaldehyde and chloroform were mixed evenly and heated to 40℃. Calcium hydride was added and the temperature was raised to 70℃. Under nitrogen protection, aminomethyltrimethylsilane was added and the temperature was raised to 80℃. The pre-modified chlorinated polyethylene film was added and reacted for 20 hours. The mixture was then removed, washed 3 times with pure water, and dried at room temperature for 24 hours to obtain a modified chlorinated polyethylene film. (3) Mix vinyl acetate, vinyl quaternary ammonium salt, methanol, and azobisisobutyronitrile in a mass ratio of 1:(0.2-0.3):(0.7-0.8):(0.01-0.02) and put them into a high-pressure reactor. After ethylene is introduced for 5-10 min, the pressure of ethylene in the high-pressure reactor is set to 4.0 MPa. The temperature is raised to 55-60℃ and reacted at a speed of 150-200 r / min for 4-5 h. After the reaction is completed, the temperature is lowered to room temperature and the product is discharged. The product is precipitated with methanol aqueous solution, filtered and washed with pure water 3-4 times, and dried at 70℃ for 24 h to obtain quaternary ammonium salt-ethylene-vinyl acetate copolymer. The preparation process of the vinyl quaternary ammonium salt is as follows: At 0°C, N,N-dimethylethylenediamine, di-tert-butyl dicarbonate, and dichloromethane are mixed at a mass ratio of 1:(0.6-0.7):(20-30) for 10-15 min, stirred at 20°C for 24 h, and an equal volume of pure water is added. The mixture is separated, and the organic phase is retained. 0.9-1.0 times the mass of N,N-dimethylethylenediamine (ethylene chloride) and 0.2-0.3 times the mass of N,N-dimethylethylenediamine (potassium carbonate) are added to the organic phase. The temperature is then raised to 70-80°C. The mixture was refluxed at 0℃ for 10-12 h. After the reaction was completed, dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt precursor. The vinyl quaternary ammonium salt precursor and dichloromethane were mixed at a mass ratio of 1:(10-12) at 0-4℃. Trifluoroacetic acid, which was 5-7 times the mass of the vinyl quaternary ammonium salt precursor, was added dropwise at a rate of 1 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction was continued for 3-4 h. After the reaction was completed, saturated sodium carbonate solution was added to adjust the pH to 9-10. Dichloromethane was removed by rotary evaporation under reduced pressure to obtain the vinyl quaternary ammonium salt. (4) Mix paraformaldehyde and N,N-dimethylformamide evenly and heat to 40°C. Add calcium hydride and heat to 70°C. Then, introduce nitrogen gas and add 2-tert-butylphenol. Heat to 80°C and add quaternary ammonium salt-ethylene-vinyl acetate copolymer. After reacting for 20 hours, filter and retain the filtrate. Remove N,N-dimethylformamide by rotary evaporation under reduced pressure to obtain modified ethylene-vinyl acetate copolymer. Granulate the modified ethylene-vinyl acetate copolymer using a granulator. Use a flat vulcanizing machine to mold the granules at 90°C to obtain modified film. (5) Sand one side of the nonwoven fabric with sandpaper, cover it with a modified adhesive film, then cover it with a polyvinylidene chloride film, then cover it with a modified adhesive film, then cover it with a modified chlorinated polyethylene film. Repeat the above sanding-covering operation on the other side of the nonwoven fabric. Hot roll it twice on a hot rolling mill. The hot rolling mill pressure is 0.3MPa, the temperature is 140-150℃, and the time is 3min. After hot rolling, tritium-proof composite fabric is obtained.

2. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The 2-chloro-6-vinylpyridine-acetone solution in step (1) is prepared by mixing 2-chloro-6-vinylpyridine and acetone in a mass ratio of 1:(5-6); the polyethylene film is of model 6098.

3. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The mass ratio of paraformaldehyde, aminomethyltrimethylsilane, pre-modified chlorinated polyethylene film, calcium hydride and chloroform in step (2) is 1:(1.6-1.8):(10-12):(0.7-0.8):(20-30).

4. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The methanol-water solution in step (3) is made by mixing methanol and water in a mass ratio of 3:

1.

5. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The mass ratio of paraformaldehyde, 2-tert-butylphenol, quaternary ammonium salt-ethylene-vinyl acetate copolymer, calcium hydride, and N,N-dimethylformamide in step (4) is 1:(3.4-3.5):(0.2-0.3):(0.7-0.8):(20-30).

6. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The thickness of the modified film in step (4) is 0.5 mm.

7. The preparation process of a tritium-resistant composite fabric according to claim 1, characterized in that, The nonwoven fabric in step (5) is model 1473R; the polyvinylidene chloride film is model VSL-4603.

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