A graphite-based flame retardant, a graphite-based flame retardant finishing liquid, and a preparation method and application thereof

Abstract

The invention belongs to the field of flame retardant technology, and specifically relates to a graphite-based flame retardant, a graphite-based flame retardant finishing liquid, and a preparation method and application thereof. The preparation method of the graphite-based flame retardant finishing liquid is as follows: firstly prepare a reaction system a containing expandable graphite, dopamine hydrochloride, hydrogen peroxide and a solvent and having a pH value of more than 7, and then react at 70-80°C for 1-2h; then add glucose to the reaction system a to obtain a reaction system b, and then react at 80-90°C to obtain a graphite-based flame retardant finishing liquid; the graphite-based flame retardant finishing liquid can be purified to obtain a graphite-based flame retardant; the application is to use the graphite-based flame retardant finishing liquid and nylon 6 fabric to react at 80-90°C, and obtain a halogen-free and phosphorus-free flame-retardant nylon 6 fabric through post-treatment. The halogen-free and phosphorus-free flame-retardant nylon 6 fabric prepared by the invention has a good flame retardant effect, and still has a good flame retardant effect after 20 water washings.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardancy, and in particular relates to a graphite-based flame retardant, a graphite-based flame retardant finishing liquid, and a preparation method and application thereof. Background Art

[0002] Nylon 6 fabric is light, soft, strong and wear-resistant, and is widely used in textiles, clothing, aerospace, construction and other fields. However, nylon 6 fabric has obvious flammability defects, fast burning speed and severe dripping behavior. Improving the flame retardant and anti-drip properties of nylon 6 fabric is of great significance.

[0003] Conventional flame retardants for fabrics include halogen flame retardants and phosphorus-containing flame retardants, etc. However, due to the increasing environmental protection requirements, the use of halogen flame retardants has been gradually banned. Phosphorus-containing flame retardants are prone to cause eutrophication of water bodies, and their application in printing and dyeing enterprises is also greatly restricted. In order to address this problem, a halogen-free and phosphorus-free flame retardant system has been developed.

[0004] Expandable graphite is a common halogen-free and phosphorus-free flame retardant. The initial expansion temperature of expandable graphite is 290~300℃, and the expansion volume is ≥230ml / g. When the expandable graphite is exposed to high temperature, the volume can be instantly expanded by 150~300 times, and the flake shape changes to the worm shape, so that the structure becomes loose, porous and curved, and the surface area is also expanded. This special structure has a good effect of hindering combustion. However, due to its poor water solubility, expandable graphite has poor dispersibility in aqueous solution, which in turn affects its affinity with composite materials and textiles. This poor affinity directly leads to the lack of flame retardancy and water washability of expandable graphite modified textiles. Therefore, this characteristic has become a major obstacle to the application of expandable graphite in flame retardant modification of composite materials and textiles.

[0005] Patent application CN111675881A discloses a method for preparing a flame-retardant epoxy resin with dopamine surface functionalized expandable graphite, wherein the expandable graphite is surface functionalized by dopamine oxidation self-polymerization technology to obtain dopamine surface functionalized expandable graphite, which is then applied to epoxy resin. The active groups of the dopamine surface functionalized expandable graphite can chemically bond with the epoxy groups of the epoxy resin, thereby improving the stability and compatibility of the expandable graphite in the epoxy resin. If the dopamine surface functionalized expandable graphite in the patent is applied to the flame-retardant finishing of nylon 6 fabric, the performance of the nylon 6 fabric after the flame-retardant finishing is still unsatisfactory because the water solubility of the dopamine surface functionalized expandable graphite is still poor, the dispersibility in aqueous solution is poor, and the affinity with nylon 6 fabric is low.

[0006] Therefore, it is urgent to develop a graphite-based flame retardant with good water solubility and use it for flame retardant finishing of nylon 6 fabric. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and to provide a graphite-based flame retardant, a graphite-based flame retardant finishing liquid and a preparation method and application thereof.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a graphite-based flame retardant finishing liquid, comprising the following steps:

[0010] (1) preparing a reaction system a containing expandable graphite, dopamine hydrochloride, hydrogen peroxide and a solvent and having a pH value > 7 (which can be adjusted by adding sodium hydroxide), and reacting at 70-80°C for 1-2 hours;

[0011] (2) Glucose is added to reaction system a to obtain reaction system b, and then the reaction is carried out at 80-90° C. to obtain a graphite-based flame retardant finishing liquid.

[0012] In step (1), under alkaline conditions (pH value>7), catalyst (hydrogen peroxide), high temperature (70-80°C), and short time (1-2h), only a portion of the dopamine hydrochloride in the reaction system a self-polymerizes to form polydopamine, which is coated on the surface of the expandable graphite, and the other portion of the dopamine hydrochloride is in a free state;

[0013] In step (2), at 80-90°C, a Maillard reaction occurs between glucose and polydopamine, a Maillard reaction occurs between glucose and unreacted dopamine hydrochloride, dopamine hydrochloride self-polymerizes, and a polymerization reaction occurs between polydopamine and dopamine hydrochloride. This process simultaneously generates Maillard products and polydopamine, so that the chain segments of polydopamine and Maillard products are interlaced and cross-linked with each other, tightly combined, and have no obvious interface problems.

[0014] If the dopamine hydrochloride is completely polymerized in step (1) and then the Maillard reaction is carried out in step (2), the expandable graphite can also be coated and modified. However, the binding force between the Maillard product and polydopamine is weak, which will cause the water washing resistance of the flame retardant finished textile to deteriorate.

[0015] Polydopamine has high adhesion and can be used to modify the adhesion of any substance. However, although polydopamine has a certain water solubility, it cannot solve the problem of poor water solubility of expandable graphite. Maillard product is a substance with high water solubility and can improve the water solubility of expandable graphite. However, the adhesion performance of Maillard product to expandable graphite is slightly poor, resulting in poor effect of directly modifying expandable graphite. Therefore, the present invention uses polydopamine and Maillard product to modify expandable graphite at the same time.

[0016] As the preferred technical solution:

[0017] In the method for preparing a graphite-based flame retardant finishing liquid as described above, in step (1), the weight ratio of expandable graphite, dopamine hydrochloride, and glucose is 10-20:2-4:5-10; and in the reaction system a, the content of expandable graphite is 10-20 g / L.

[0018] In the method for preparing a graphite-based flame retardant finishing liquid as described above, in step (1), the pH value of the reaction system a is 10-11.

[0019] In the method for preparing a graphite-based flame retardant finishing liquid as described above, in step (2), the content of glucose in the reaction system b is 5-10 g / L; and the reaction time is 2-3 h.

[0020] A graphite-based flame retardant finishing liquid is prepared by using the preparation method of a graphite-based flame retardant finishing liquid as described in any one of the above items.

[0021] A method for preparing a graphite-based flame retardant is provided, wherein the graphite-based flame retardant finishing liquid as described above is purified to obtain the graphite-based flame retardant.

[0022] A graphite-based flame retardant is prepared by using the above-mentioned method for preparing a graphite-based flame retardant.

[0023] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric comprises adding the nylon 6 fabric into a graphite-based flame retardant finishing liquid as described above, reacting at 80-90°C, and obtaining the halogen-free and phosphorus-free flame-retardant nylon 6 fabric through post-treatment (taking out, washing, and drying); in this process, polydopamine and Maillard products in the graphite-based flame retardant finishing liquid adhere to the nylon 6 fabric by virtue of their own high adhesion properties, and on the other hand, they react covalently with the amino groups of polyamide 6 fibers and are grafted onto the nylon 6 fabric.

[0024] As the preferred technical solution:

[0025] In the method for preparing the halogen-free and phosphorus-free flame-retardant nylon 6 fabric as described above, the bath ratio of the nylon 6 fabric to the graphite-based flame retardant finishing liquid is 1:30-50, and the reaction time is 1.5-2 hours.

[0026] A halogen-free and phosphorus-free flame-retardant nylon 6 fabric is prepared by using the preparation method of a halogen-free and phosphorus-free flame-retardant nylon 6 fabric as described in any one of the above items.

[0027] The halogen-free and phosphorus-free flame-retardant nylon 6 fabric as described above has a limiting oxygen index of not less than 28.3%, a damaged length of not more than 12.3 cm, no molten droplets are generated, and after 20 washes, the damaged length is still less than 14.5 cm, no molten droplets are generated, and has good flame retardant and anti-molten droplet properties and water washability. This is because the polysaccharide rings of the Maillard product decompose into carbon at a lower temperature, which helps to inhibit the molten droplets of the nylon 6 fabric, but the stability of the residual carbon is poor; the expandable graphite has a strong expansion ability, which improves the thermal stability and strength of the residual carbon produced by the Maillard product, thereby effectively inhibiting the molten droplets of the nylon 6 fabric and achieving a flame retardant effect.

[0028] Beneficial effects:

[0029] (1) The present invention simultaneously uses polydopamine and Maillard products to modify expandable graphite, thereby improving the water solubility of expandable graphite, so that expandable graphite can be evenly dispersed on the surface of nylon 6 fabric. The Maillard products on the surface of the modified expandable graphite contain active groups such as aldehyde groups and carboxyl groups, which can be covalently bonded and ionically bonded to nylon 6 fabric, so that the modified nylon 6 fabric has good water washability and durable flame retardant function.

[0030] (2) The present invention uses expandable graphite, which has a strong expansion ability, and improves the thermal stability and strength of the residual carbon produced by the Maillard product, thereby effectively inhibiting the molten droplet of nylon 6 fabric and achieving a good flame retardant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a surface morphology of the halogen-free and phosphorus-free flame-retardant nylon 6 fabric prepared in Example 8 of the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] The following are the methods for testing the relevant performance indicators in the embodiments and comparative examples:

[0034] Limiting oxygen index of fabric: Tested in accordance with GB / T 5454-1997 "Oxygen Index Method for Textile Combustion Performance Test".

[0035] Damage length and the presence of molten droplets: Determine the damage length, smoldering and afterflaming time in the vertical direction of the combustion performance of textiles according to GB / T 5455-2014. Observe the presence of molten droplets during the test.

[0036] Damaged length and presence of molten droplets after 20 washes: First wash the fabric 20 times with water according to AATCC 61-2013 "Accelerated test for color fastness to household and commercial washing" standard, and then test the damaged length of the fabric with reference to GB / T 5455-2014 "Determination of vertical direction damage length, smoldering and afterflaming time of textile combustion performance" standard, and observe whether there are molten droplets during the test.

[0037] Example 1

[0038] A method for preparing a graphite-based flame retardant finishing liquid, the specific steps are as follows:

[0039] (1) Raw material preparation:

[0040] Expandable graphite: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., the model is E477901, and the initial expansion temperature is 290~300℃;

[0041] Dopamine hydrochloride;

[0042] Hydrogen peroxide;

[0043] Sodium hydroxide;

[0044] Solvent: water;

[0045] glucose;

[0046] (2) Preparation of graphite-based flame retardant finishing liquid:

[0047] (2.1) preparing a reaction system a consisting of expandable graphite, dopamine hydrochloride, hydrogen peroxide, sodium hydroxide and a solvent, and reacting at 70°C for 2 hours;

[0048] In reaction system a, the pH value is 10, the weight ratio of expandable graphite, dopamine hydrochloride and glucose is 10:2:05, and the content of expandable graphite is 10 g / L;

[0049] (2.2) Glucose is added to reaction system a to obtain reaction system b having a glucose content of 5 g / L, and the reaction is carried out at 80° C. for 3 h to obtain a graphite-based flame retardant finishing liquid. The graphite-based flame retardant finishing liquid is purified to obtain a graphite-based flame retardant.

[0050] Example 2

[0051] A method for preparing a graphite-based flame retardant finishing liquid, the specific steps are as follows:

[0052] (1) Raw material preparation:

[0053] Expandable graphite: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., the model is E477901, and the initial expansion temperature is 290~300℃;

[0054] Dopamine hydrochloride;

[0055] Hydrogen peroxide;

[0056] Sodium hydroxide;

[0057] Solvent: water;

[0058] glucose;

[0059] (2) Preparation of graphite-based flame retardant finishing liquid:

[0060] (2.1) preparing a reaction system a consisting of expandable graphite, dopamine hydrochloride, hydrogen peroxide, sodium hydroxide and a solvent, and reacting at 72°C for 1.8 hours;

[0061] In reaction system a, the pH value is 10.5, the weight ratio of expandable graphite, dopamine hydrochloride, and glucose is 13:2.5:7, and the content of expandable graphite is 13 g / L;

[0062] (2.2) Glucose is added to reaction system a to obtain reaction system b having a glucose content of 6 g / L, and the reaction is carried out at 83° C. for 2.7 h to obtain a graphite-based flame retardant finishing liquid. The graphite-based flame retardant finishing liquid is purified to obtain a graphite-based flame retardant.

[0063] Example 3

[0064] A method for preparing a graphite-based flame retardant finishing liquid, the specific steps are as follows:

[0065] (1) Raw material preparation:

[0066] Expandable graphite: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., the model is E477901, and the initial expansion temperature is 290~300℃;

[0067] Dopamine hydrochloride;

[0068] Hydrogen peroxide;

[0069] Sodium hydroxide;

[0070] Solvent: water;

[0071] glucose;

[0072] (2) Preparation of graphite-based flame retardant finishing liquid:

[0073] (2.1) preparing a reaction system a consisting of expandable graphite, dopamine hydrochloride, hydrogen peroxide, sodium hydroxide and a solvent, and reacting at 75°C for 1.5 hours;

[0074] In reaction system a, the pH value is 11, the weight ratio of expandable graphite, dopamine hydrochloride, and glucose is 15:4:8, and the content of expandable graphite is 15 g / L;

[0075] (2.2) Glucose is added to reaction system a to obtain reaction system b having a glucose content of 7 g / L, and the reaction is carried out at 85° C. for 2.5 h to obtain a graphite-based flame retardant finishing liquid. The graphite-based flame retardant finishing liquid is purified to obtain a graphite-based flame retardant.

[0076] Example 4

[0077] A method for preparing a graphite-based flame retardant finishing liquid, the specific steps are as follows:

[0078] (1) Raw material preparation:

[0079] Expandable graphite: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., the model is E477901, and the initial expansion temperature is 290~300℃;

[0080] Dopamine hydrochloride;

[0081] Hydrogen peroxide;

[0082] Sodium hydroxide;

[0083] Solvent: water;

[0084] glucose;

[0085] (2) Preparation of graphite-based flame retardant finishing liquid:

[0086] (2.1) preparing a reaction system a consisting of expandable graphite, dopamine hydrochloride, hydrogen peroxide, sodium hydroxide and a solvent, and reacting at 77°C for 1.3 hours;

[0087] In reaction system a, the pH value is 10.5, the weight ratio of expandable graphite, dopamine hydrochloride and glucose is 18:3:8, and the content of expandable graphite is 18 g / L;

[0088] (2.2) Glucose is added to reaction system a to obtain reaction system b having a glucose content of 9 g / L, and the reaction is carried out at 88° C. for 2.3 h to obtain a graphite-based flame retardant finishing liquid. The graphite-based flame retardant finishing liquid is purified to obtain a graphite-based flame retardant.

[0089] Example 5

[0090] A method for preparing a graphite-based flame retardant finishing liquid, the specific steps are as follows:

[0091] (1) Raw material preparation:

[0092] Expandable graphite: The manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., the model is E477901, and the initial expansion temperature is 290~300℃;

[0093] Dopamine hydrochloride;

[0094] Hydrogen peroxide;

[0095] Sodium hydroxide;

[0096] Solvent: water;

[0097] glucose;

[0098] (2) Preparation of graphite-based flame retardant finishing liquid:

[0099] (2.1) preparing a reaction system a consisting of expandable graphite, dopamine hydrochloride, hydrogen peroxide, sodium hydroxide and a solvent, and reacting at 80°C for 1 hour;

[0100] In reaction system a, the pH value is 10, the weight ratio of expandable graphite, dopamine hydrochloride and glucose is 20:3:10, and the content of expandable graphite is 20 g / L;

[0101] (2.2) Glucose is added to reaction system a to obtain reaction system b having a glucose content of 10 g / L, and the reaction is carried out at 90° C. for 2 h to obtain a graphite-based flame retardant finishing liquid. The graphite-based flame retardant finishing liquid is purified to obtain a graphite-based flame retardant.

[0102] Comparative Example 1

[0103] A method for preparing a graphite-based flame retardant finishing liquid is basically the same as Example 5, except that: in step (2.1), the reaction temperature is 90° C. and the reaction time is 5 h. In this comparative example, due to the excessively high reaction temperature and the excessively long reaction time, the dopamine hydrochloride in system a is completely polymerized.

[0104] Example 6

[0105] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, the specific steps are as follows:

[0106] (1) Raw material preparation:

[0107] Nylon 6 fabric: Limiting oxygen index is 20.1%, and the damaged length is 30cm;

[0108] The graphite-based flame retardant finishing liquid prepared in Example 1;

[0109] (2) Preparation of flame-retardant nylon 6 fabric:

[0110] Nylon 6 fabric was added into the graphite-based flame retardant finishing liquid at a bath ratio of 1:30, reacted at 80°C for 2 hours, and then taken out, washed and dried to obtain the halogen-free and phosphorus-free flame retardant nylon 6 fabric.

[0111] The final halogen-free and phosphorus-free flame-retardant nylon 6 fabric had a limiting oxygen index of 28.3%, a damaged length of 12.3 cm, and no molten droplets were produced. After 20 washes, the damaged length was 14.5 cm, and no molten droplets were produced.

[0112] Example 7

[0113] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, the specific steps are as follows:

[0114] (1) Raw material preparation:

[0115] Nylon 6 fabric: Limiting oxygen index is 20.1%, and the damaged length is 30cm;

[0116] The graphite-based flame retardant finishing liquid prepared in Example 2;

[0117] (2) Preparation of flame-retardant nylon 6 fabric:

[0118] Nylon 6 fabric was added into the graphite-based flame retardant finishing liquid at a bath ratio of 1:50, and reacted at 82°C for 1.8 hours. After being taken out, washed and dried, the halogen-free and phosphorus-free flame retardant nylon 6 fabric was obtained.

[0119] The final halogen-free and phosphorus-free flame-retardant nylon 6 fabric had a limiting oxygen index of 29.5%, a damaged length of 11.2 cm, and no molten droplets were produced. After 20 washes, the damaged length was 13.9 cm, and no molten droplets were produced.

[0120] Example 8

[0121] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, the specific steps are as follows:

[0122] (1) Raw material preparation:

[0123] Nylon 6 fabric: Limiting oxygen index is 20.1%, and the damaged length is 30cm;

[0124] The graphite-based flame retardant finishing liquid prepared in Example 3;

[0125] (2) Preparation of flame-retardant nylon 6 fabric:

[0126] Nylon 6 fabric was added into the graphite-based flame retardant finishing liquid at a bath ratio of 1:40, and reacted at 85°C for 1.5 hours. After being taken out, washed and dried, the halogen-free and phosphorus-free flame retardant nylon 6 fabric was obtained.

[0127] The surface morphology of the final halogen-free and phosphorus-free flame-retardant nylon 6 fabric is as follows: Figure 1As shown, the limiting oxygen index of the halogen-free and phosphorus-free flame-retardant nylon 6 fabric is 30.3%, the damaged length is 10.3 cm, and no molten droplets are generated. After 20 washes, the damaged length is 13.3 cm, and no molten droplets are generated.

[0128] Example 9

[0129] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, the specific steps are as follows:

[0130] (1) Raw material preparation:

[0131] Nylon 6 fabric: Limiting oxygen index is 20.1%, and the damaged length is 30cm;

[0132] The graphite-based flame retardant finishing liquid prepared in Example 4;

[0133] (2) Preparation of flame-retardant nylon 6 fabric:

[0134] Nylon 6 fabric was added into the graphite-based flame retardant finishing liquid at a bath ratio of 1:50, and reacted at 87°C for 1.2 hours. After being taken out, washed and dried, the halogen-free and phosphorus-free flame retardant nylon 6 fabric was obtained.

[0135] The final halogen-free and phosphorus-free flame-retardant nylon 6 fabric had a limiting oxygen index of 31.2%, a damaged length of 9.5 cm, and no molten droplets were produced. After 20 washes, the damaged length was 12.7 cm, and no molten droplets were produced.

[0136] Example 10

[0137] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, the specific steps are as follows:

[0138] (1) Raw material preparation:

[0139] Nylon 6 fabric: Limiting oxygen index is 20.1%, and the damaged length is 30cm;

[0140] The graphite-based flame retardant finishing liquid prepared in Example 5;

[0141] (2) Preparation of flame-retardant nylon 6 fabric:

[0142] Nylon 6 fabric was added into the graphite-based flame retardant finishing liquid at a bath ratio of 1:50, reacted at 90°C for 1 hour, and then taken out, washed and dried to obtain the halogen-free and phosphorus-free flame retardant nylon 6 fabric.

[0143] The final halogen-free and phosphorus-free flame-retardant nylon 6 fabric had a limiting oxygen index of 32%, a damaged length of 9.1 cm, and no molten droplets were produced. After 20 washes, the damaged length was 12.4 cm, and no molten droplets were produced.

[0144] Comparative Example 2

[0145] A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric is basically the same as Example 10, except that the graphite-based flame retardant finishing liquid used in this comparative example is prepared from Comparative Example 1.

[0146] The final halogen-free and phosphorus-free flame-retardant nylon 6 fabric had a limiting oxygen index of 30.5%, a damaged length of 10.3 cm, and no molten droplets were produced. After 20 washes, the damaged length was 30 cm, and molten droplets were produced.

[0147] Compared with Example 10, the flame retardant properties of the halogen-free and phosphorus-free flame-retardant nylon 6 fabric prepared in Comparative Example 2 before washing are slightly worse than those of Example 10, and the flame retardant properties are significantly deteriorated after 20 washings. This is because in the preparation process of the graphite-based flame retardant finishing liquid prepared in Comparative Example 1 used in Comparative Example 2, dopamine hydrochloride is completely polymerized before the Maillard reaction. Although it can also coat and modify expandable graphite, the binding force between the Maillard product and polydopamine is weak, resulting in poor water washing resistance of the textile after flame retardant finishing.

Claims

1. A method for preparing a graphite-based flame retardant finishing liquid, characterized in that: Here are the steps: (1) preparing a reaction system a containing expandable graphite, dopamine hydrochloride, hydrogen peroxide and a solvent and having a pH value of 10 to 11, and reacting at 70 to 80° C. for 1 to 2 hours; (2) Glucose is added to reaction system a to obtain reaction system b, and then the reaction is carried out at 80 to 90° C. to obtain a graphite-based flame retardant finishing liquid.

2. The method for preparing a graphite-based flame retardant finishing liquid according to claim 1, characterized in that: In step (1), the weight ratio of expandable graphite, dopamine hydrochloride and glucose is 10-20:2-4:5-10; and in reaction system a, the content of expandable graphite is 10-20 g / L.

3. The method for preparing a graphite-based flame retardant finishing liquid according to claim 1, characterized in that: In step (2), the content of glucose in the reaction system b is 5 to 10 g / L; and the reaction time is 2 to 3 h.

4. A graphite-based flame retardant finishing liquid, characterized in that: The method for preparing a graphite-based flame retardant finishing liquid is adopted as claimed in any one of claims 1 to 3.

5. A method for preparing a graphite-based flame retardant, characterized in that: The graphite-based flame retardant finishing liquid as claimed in claim 4 is purified to obtain the graphite-based flame retardant.

6. A graphite-based flame retardant, characterized in that: The method for preparing a graphite-based flame retardant is used as claimed in claim 5.

7. A method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric, characterized in that: The nylon 6 fabric is added into the graphite-based flame retardant finishing liquid as claimed in claim 4, reacted at 80-90° C., and post-treated to obtain the halogen-free and phosphorus-free flame retardant nylon 6 fabric.

8. The method for preparing a halogen-free and phosphorus-free flame-retardant nylon 6 fabric according to claim 7, characterized in that: The bath ratio of nylon 6 fabric and graphite-based flame retardant finishing liquid is 1:30-50, and the reaction time is 1.5-2h.

9. A halogen-free and phosphorus-free flame-retardant nylon 6 fabric, characterized in that: The halogen-free and phosphorus-free flame-retardant nylon 6 fabric is prepared by the preparation method of claim 7 or 8; the limiting oxygen index of the halogen-free and phosphorus-free flame-retardant nylon 6 fabric is not less than 28.3%, the damaged length is not higher than 12.3 cm, no molten droplets are generated, and after 20 washes, the damaged length is still less than 14.5 cm, and no molten droplets are generated.

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