A method for flame retardant finishing of nylon 6 fabric using a halogen-free and phosphorus-free flame retardant system

Abstract

The invention belongs to the technical field of flame-retardant fabrics, and relates to a method for flame-retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame-retardant system. The method is specifically as follows: firstly, waste wool is treated with a tannic acid solution, then the waste wool is treated with a sodium silicate solution to obtain a wool dissolving solution, and finally the nylon 6 fabric is treated with the wool dissolving solution to obtain a flame-retardant nylon 6 fabric. The flame retardant system of the invention belongs to an environmentally friendly flame retardant system, and the obtained flame-retardant nylon 6 fabric has excellent flame retardant properties.

Description

Technical Field

[0001] The invention belongs to the technical field of flame-retardant fabrics, and in particular relates to a method for flame-retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame-retardant system. Background Art

[0002] Nylon 6 fabric is a synthetic fiber with the advantages of good wear resistance, high resilience and high breaking strength. It is widely used in clothing, home textiles and industrial products. However, nylon 6 fiber is a flammable fiber that is easy to burn and produce molten droplets, posing a potential fire hazard. Improving the flame retardant properties of nylon 6 fabric is of great significance. As the concept of environmental protection becomes more and more popular, some environmentally unfriendly nylon 6 fabric flame retardant finishing methods are gradually abandoned, and the development of green and sustainable flame retardants has become a new goal. Protein has a unique chemical structure and is rich in nitrogen, sulfur and other elements, which gives it potential flame retardant ability. Therefore, environmentally friendly biomass flame retardants such as protein have gradually become the focus of research.

[0003] Patent application CN105603742A discloses a method for flame-retardantly modifying synthetic fabrics with protein, wherein soybean protein, polyphosphate and sulfonate flame retardants are dissolved in distilled water to form a composite flame retardant system, and then the synthetic fabrics are post-finished using a double-dipping and double-rolling method, including synthetic fibers such as nylon and polyester. However, the modified synthetic fiber fabrics all have a melting droplet phenomenon, and the flame retardant properties need to be further improved.

[0004] Keratin is a protein widely found in the epidermal structures of animals such as hair, nails, and feathers. It has unique advantages over ordinary proteins in the field of flame retardancy. Its high content of nitrogen and sulfur gives it excellent carbon-forming properties, making keratin an ideal material for flame retardant finishing. Wool fiber is a rich keratin resource, but a large amount of waste wool is produced every year around the world, and these waste wools are directly discarded in landfills. If these waste wools can be effectively utilized and their application rate in the field of flame retardancy of nylon 6 fabrics is increased, environmental pollution and resource waste will be significantly reduced.

[0005] Therefore, it is particularly necessary to propose a new method for flame retardant finishing of nylon 6 fabric by utilizing keratin in waste wool. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems in the prior art and provide a method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system comprises the following steps:

[0009] (1) Soak the waste wool in tannic acid solution at a temperature above 85°C;

[0010] In this process, tannic acid is rich in phenolic hydroxyl groups and has a strong binding ability with wool protein. Its phenolic hydroxyl groups can undergo complex covalent cross-linking reactions with amino groups, thereby fixing on waste wool fibers.

[0011] The treatment temperature is controlled to be above 85℃ in this stage because the surface of waste wool fiber is rich in scale layer. Raising the temperature helps to open the scale layer of waste wool fiber and helps to increase the diffusion of tannic acid into the waste wool fiber.

[0012] (2) immersing the waste wool treated in step (1) in a sodium silicate solution at a temperature above 85° C. to obtain a waste wool solution;

[0013] During this process, the following reactions occur simultaneously:

[0014] Sodium silicate is hydrolyzed on the surface and inside of waste wool fibers to generate poorly water-soluble silicic acid and sodium hydroxide. The silicate colloid has strong adsorption properties and can be adsorbed and combined with tannic acid to generate insoluble tannic acid-silicate complex salt.

[0015] Wool keratin is a macromolecular long-chain structure, rich in amino and carboxyl groups, and has strong ionic bonding and chelating effects with tannic acid and silicic acid in insoluble tannic acid-silicate complex salts, playing the role of dispersing insoluble tannic acid-silicate complex salts;

[0016] Sodium hydroxide produced by the hydrolysis of sodium silicate destroys the hydrogen bonds and hydrophobic interactions within the protein molecules, leading to the decomposition and dissolution of keratin;

[0017] The treatment temperature is controlled to be above 85℃ in this stage because the surface of waste wool fiber is rich in scale layer. Raising the temperature helps to open the scale layer of waste wool fiber, so that sodium silicate can diffuse into the interior of waste wool fiber and help dissolve waste wool.

[0018] (3) Nylon 6 fabric was treated with waste wool dissolving liquid to obtain flame retardant nylon 6 fabric.

[0019] As the preferred technical solution:

[0020] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (1), the concentration of the tannic acid solution is 70-100 g / L, and the mass ratio of the waste wool to the tannic acid solution is 1:30-40.

[0021] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (1), the treatment temperature is 85-95° C. and the treatment time is 40-60 min.

[0022] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (2), the concentration of the sodium silicate solution is 40-60 g / L, and the mass ratio of the waste wool to the sodium silicate solution is 1:20-30.

[0023] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (2), the treatment temperature is 85-95° C. and the treatment time is 60-90 min.

[0024] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (3), the finishing is to immerse the nylon 6 fabric in a waste wool solution at a temperature above 80° C. and then dry it, and the mass ratio of the nylon 6 fabric to the waste wool solution is 1:30-40.

[0025] In the method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described above, in step (3), the treatment temperature is 80-90°C and the treatment time is 50-70 minutes. The higher the treatment temperature and the longer the treatment time, the more conducive it is to the adsorption of the flame retardant on the nylon 6 fabric.

[0026] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system as described in any of the above items, wherein the limiting oxygen index of the flame retardant nylon 6 fabric is ≥28.5%, the damaged length is ≤10.8 cm, no molten droplets are generated, and the residual carbon content after calcination at 700°C is ≥18.1%; since the tannic acid structure and silicate in the waste wool solution have the performance of catalyzing carbonization and can act as an acid source, the tannic acid structure and wool keratin act as a carbon source, and the nitrogen-containing groups of wool keratin act as a gas source, an intumescent flame retardant system can be constructed with high carbonization efficiency, and silicate helps to further improve the thermal stability and residual carbon content of the residual carbon, so the flame retardant nylon 6 fabric has excellent flame retardant properties. Beneficial Effects

[0027] The present invention uses tannic acid and sodium silicate to treat waste wool to obtain waste wool dissolving liquid, and the system belongs to an environmentally friendly halogen-free and phosphorus-free flame retardant system;

[0028] In the waste wool dissolving solution of the present invention, the tannic acid structure and silicate have the performance of catalyzing carbonization and can be used as an acid source; the tannic acid structure and wool keratin act together as a carbon source; and the nitrogen-containing groups in the wool keratin act as a gas source. The three synergistically act to construct an efficient expansion flame retardant system. This system not only has a high carbonization efficiency, but also the addition of silicate can further improve the thermal stability of the residual carbon and increase the residual carbon amount. The nylon 6 fabric treated with this flame retardant system has excellent flame retardant properties. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0030] Testing methods for relevant performance indicators:

[0031] Limiting oxygen index: measured according to GB / T 5454-1997 using FTT0080 oxygen index instrument;

[0032] Damage length and presence of molten droplets: According to GB / T 5455-2014, the damage length is tested using an M233M vertical combustion test machine, and the presence of molten droplets is observed during the test;

[0033] Carbon residue: The sample was calcined at 700°C for 3 min in a LH-T-30 muffle furnace and then its carbon residue was tested.

[0034] Example 1

[0035] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system, the specific steps are as follows:

[0036] (1) Raw material preparation:

[0037] waste wool;

[0038] Tannic acid solution: the solvent is water;

[0039] Sodium silicate solution: the solvent is water;

[0040] Nylon 6 fabric: The limiting oxygen index is 20.1%, the damaged length is 30 cm, and the carbon residue after calcination at 700°C is 0%.

[0041] (2) Preparation of waste wool solution:

[0042] (2.1) Soak the waste wool in tannic acid solution at 85°C for 60 minutes;

[0043] The concentration of the tannic acid solution is 70 g / L, and the mass ratio of the waste wool to the tannic acid solution is 1:30;

[0044] (2.2) immersing the waste wool treated in step (2.1) in a sodium silicate solution at 85° C. for 90 minutes to obtain a waste wool solution;

[0045] The concentration of the sodium silicate solution is 40 g / L, and the mass ratio of waste wool to the sodium silicate solution is 1:30;

[0046] (3) Flame retardant finishing of nylon 6 fabric:

[0047] The nylon 6 fabric is immersed in waste wool solution and treated at 80°C for 70 minutes, and then dried to obtain a flame retardant nylon 6 fabric;

[0048] Among them, the mass ratio of nylon 6 fabric to waste wool solution is 1:30.

[0049] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 28.5%, a damaged length of 10.8 cm, no molten droplets were generated, and the residual carbon content after calcination at 700°C was 18.1%.

[0050] Comparative Example 1

[0051] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system is basically the same as Example 1, except that the same mass of deionized water is used in this comparative example to replace the tannic acid in the original Example 1, and the other conditions remain unchanged.

[0052] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 22.5%, a damaged length of 30 cm, molten droplets, and a carbon residue of 2.9% after calcination at 700°C.

[0053] Compared with Example 1, the flame retardant effect of the flame retardant nylon 6 fabric prepared in Comparative Example 1 is poor, and there is a droplet phenomenon. This is because tannic acid is the main acid source, and the flame retardant efficiency of the flame retardant system is poor when tannic acid is not added.

[0054] Comparative Example 2

[0055] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system is basically the same as Example 1, except that the treatment temperature in step (2.1) of this comparative example is 50°C.

[0056] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 25.3%, a damaged length of 30 cm, molten droplets, and a carbon residue of 3.5% after calcination at 700°C.

[0057] Compared with Example 1, the flame retardant performance of the flame retardant nylon 6 fabric prepared in Comparative Example 1 deteriorates, and molten droplets are generated. This is because there is a scale layer on the surface of the wool fiber. When the temperature is low, the flame retardant cannot enter the interior of the wool fiber and is only adsorbed on the surface of the wool fiber. It cannot fully combine with the subsequent wool keratin, resulting in a low content of flame retardant on the wool keratin and a poor flame retardant effect.

[0058] Example 2

[0059] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system, the specific steps are as follows:

[0060] (1) Raw material preparation:

[0061] waste wool;

[0062] Tannic acid solution: the solvent is water;

[0063] Sodium silicate solution: the solvent is water;

[0064] Nylon 6 fabric: The limiting oxygen index is 20.1%, the damaged length is 30 cm, and the carbon residue after calcination at 700°C is 0%.

[0065] (2) Preparation of waste wool solution:

[0066] (2.1) Soak the waste wool in tannic acid solution at 88°C for 50 minutes;

[0067] The concentration of the tannic acid solution is 80 g / L, and the mass ratio of the waste wool to the tannic acid solution is 1:35;

[0068] (2.2) immersing the waste wool treated in step (2.1) in a sodium silicate solution at 88° C. for 80 minutes to obtain a waste wool solution;

[0069] The concentration of the sodium silicate solution is 45 g / L, and the mass ratio of waste wool to the sodium silicate solution is 1:25;

[0070] (3) Flame retardant finishing of nylon 6 fabric:

[0071] The nylon 6 fabric was immersed in waste wool solution and treated at 83°C for 60 minutes, and then dried to obtain the flame retardant nylon 6 fabric.

[0072] Among them, the mass ratio of nylon 6 fabric to waste wool solution is 1:35.

[0073] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 29.4%, a damaged length of 10.1 cm, no droplets were generated, and the residual carbon content after calcination at 700°C was 19.2%.

[0074] Example 3

[0075] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system, the specific steps are as follows:

[0076] (1) Raw material preparation:

[0077] waste wool;

[0078] Tannic acid solution: the solvent is water;

[0079] Sodium silicate solution: the solvent is water;

[0080] Nylon 6 fabric: The limiting oxygen index is 20.1%, the damaged length is 30 cm, and the carbon residue after calcination at 700°C is 0%.

[0081] (2) Preparation of waste wool solution:

[0082] (2.1) Soak the waste wool in tannic acid solution at 92°C for 45 minutes;

[0083] The concentration of the tannic acid solution was 90 g / L, and the mass ratio of the waste wool to the tannic acid solution was 1:35;

[0084] (2.2) immersing the waste wool treated in step (2.1) in a sodium silicate solution at 93° C. for 70 minutes to obtain a waste wool solution;

[0085] The concentration of the sodium silicate solution is 50 g / L, and the mass ratio of waste wool to the sodium silicate solution is 1:25;

[0086] (3) Flame retardant finishing of nylon 6 fabric:

[0087] The nylon 6 fabric was immersed in waste wool solution and treated at 87°C for 55 minutes, and then dried to obtain the flame retardant nylon 6 fabric.

[0088] Among them, the mass ratio of nylon 6 fabric to waste wool solution is 1:35.

[0089] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 29.9%, a damaged length of 9.5 cm, no molten droplets, and a carbon residue of 19.8% after calcination at 700°C.

[0090] Example 4

[0091] A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system, the specific steps are as follows:

[0092] (1) Raw material preparation:

[0093] waste wool;

[0094] Tannic acid solution: the solvent is water;

[0095] Sodium silicate solution: the solvent is water;

[0096] Nylon 6 fabric: The limiting oxygen index is 20.1%, the damaged length is 30 cm, and the carbon residue after calcination at 700°C is 0%.

[0097] (2) Preparation of waste wool solution:

[0098] (2.1) Soak the waste wool in tannic acid solution at 95°C for 40 minutes;

[0099] The concentration of the tannic acid solution is 100 g / L, and the mass ratio of waste wool to the tannic acid solution is 1:40;

[0100] (2.2) immersing the waste wool treated in step (2.1) in a sodium silicate solution at 95° C. for 60 minutes to obtain a waste wool solution;

[0101] The concentration of the sodium silicate solution is 60 g / L, and the mass ratio of waste wool to the sodium silicate solution is 1:20;

[0102] (3) Flame retardant finishing of nylon 6 fabric:

[0103] The nylon 6 fabric is immersed in waste wool solution and treated at 90°C for 50 minutes, and then dried to obtain a flame retardant nylon 6 fabric;

[0104] Among them, the mass ratio of nylon 6 fabric to waste wool solution is 1:40.

[0105] The final flame-retardant nylon 6 fabric had a limiting oxygen index of 30.2%, a damaged length of 9.2 cm, no droplets were generated, and the residual carbon content after calcination at 700°C was 20.3%.

Claims

1. A method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system, characterized in that: The following steps are involved: (1) Immerse the waste wool in a tannic acid solution at a temperature above 85°C; (2) immersing the waste wool treated in step (1) in a sodium silicate solution at a temperature above 85° C. to obtain a waste wool solution; (3) The nylon 6 fabric is immersed in a waste wool solution at a mass ratio of 1:30-40, treated at above 80°C, and then dried to obtain a flame-retardant nylon 6 fabric.

2. The method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system according to claim 1, characterized in that: In step (1), the concentration of the tannic acid solution is 70-100 g / L, and the mass ratio of the waste wool to the tannic acid solution is 1:30-40.

3. The method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system according to claim 2, characterized in that: In step (1), the treatment temperature is 85 to 95° C. and the treatment time is 40 to 60 min.

4. The method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system according to claim 1, characterized in that: In step (2), the concentration of the sodium silicate solution is 40-60 g / L, and the mass ratio of the waste wool to the sodium silicate solution is 1:20-30.

5. The method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system according to claim 4, characterized in that: In step (2), the treatment temperature is 85 to 95° C. and the treatment time is 60 to 90 min.

6. The method for flame retardant finishing of nylon 6 fabric with a halogen-free and phosphorus-free flame retardant system according to claim 1, characterized in that: In step (3), the treatment temperature is 80-90° C. and the treatment time is 50-70 min.

7. The method for flame retardant finishing of nylon 6 fabric using a halogen-free and phosphorus-free flame retardant system according to any one of claims 1 to 6, characterized in that: The limiting oxygen index of the flame retardant nylon 6 fabric is ≥28.5%, the damaged length is ≤10.8cm, no molten droplets are generated, and the residual carbon content after calcination at 700℃ is ≥18.1%.