Intumescent flame retardant, intumescent flame retardant finishing liquid, preparation method and application thereof

Abstract

The present invention belongs to the technical field of flame retardants, and relates to an intumescent flame retardant, an intumescent flame retardant finishing liquid, and a preparation method and application thereof. The preparation method of the intumescent flame retardant finishing liquid is: a reaction system a with a pH value of ≤7 is obtained by mixing hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, an acid binding agent and a solvent a, and a reaction is carried out to obtain a modified cyclotriphosphazene; a reaction system b containing modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, hydrogen peroxide and a pH value of >7 is reacted to obtain an intumescent flame retardant finishing liquid; the intumescent flame retardant finishing liquid is purified to obtain an intumescent flame retardant. The application is to add polyamide 6 fabric into the intumescent flame retardant finishing liquid for reaction to obtain a durable flame retardant polyamide 6 fabric. The durable flame retardant polyamide 6 fabric prepared by the intumescent flame retardant of the present invention has excellent flame retardant properties and water washability.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants, and relates to an intumescent flame retardant, an intumescent flame retardant finishing liquid, and a preparation method and application thereof. Background Art

[0002] Polyamide 6 fabrics are lightweight, soft, strong and wear-resistant, and are widely used in textiles, clothing, aerospace, construction and other fields. However, polyamide 6 fabrics have obvious flammability defects, fast burning speed and severe dripping behavior, which poses a great fire hazard. Improving the flame retardant and dripping resistance of polyamide 6 fabrics is of great significance.

[0003] Hexachlorocyclotriphosphazene is a cyclotriphosphazene with a skeleton of phosphorus and nitrogen elements. It has high phosphorus and nitrogen elements and high flame retardant efficiency, but its water solubility is poor, and its phosphorus-chlorine bond is very active, easily reacting with nucleophilic reagents and also easily hydrolyzing with water. It cannot be directly used for flame retardancy of textiles such as polyamide 6 fabrics. Therefore, it is necessary to modify hexachlorocyclotriphosphazene for use in flame retardancy of polyamide 6 fabrics.

[0004] Reference 1 (Lv Meixiang et al., Preparation and Application of Melamine-Cyclotriphosphazene Flame Retardant, Journal of South China Normal University (Natural Science Edition), 2015, 47(2):78-83) uses hexahydroxymethylmelamine and hexachlorocyclotriphosphazene as raw materials to synthesize a water-soluble and alcohol-soluble halogen-free phosphazene flame retardant by a two-step method of nucleophilic substitution and etherification, and is used to prepare flame-retardant fabrics, such as medical pure cotton gauze and chemical fiber curtain fabrics. However, the flame retardant cannot form a strong bond with textiles such as polyamide 6 fabrics, resulting in poor flame retardancy and water washability of the modified polyamide 6 fabrics.

[0005] Reference 2 (Deng Jiyong et al., Preparation of a new nitrogen-phosphorus flame retardant and its flame retardant properties on cotton fabrics, Journal of Textile Research, 2017, 38(11):97-101) A new type of nitrogen-phosphorus halogen-free flame retardant was prepared using hexachlorocyclotriphosphazene and pentaerythritol phosphate as raw materials. When the flame retardant was used to prepare modified polyamide 6 fabric, the flame retardant could not form a strong bond with the polyamide 6 fabric, and the flame retardant and water washability of the modified polyamide 6 fabric were still poor.

[0006] Reference 3 (Fan Gongting, Preparation and Structural Properties of Flame-Retardant and Anti-Droplet PET Fibers and Fabrics, Master's Thesis, Donghua University, 2023) The flame retardant HBCP was synthesized using hexachlorocyclotriphosphazene and p-hydroxybenzaldehyde, and then the flame-retardant polyester fiber was prepared by melt blending and addition. However, when the flame retardant HBCP was used to prepare modified polyamide 6 fabric, due to the small number of active groups in polyamide 6 fabric, the bonding force between the flame retardant HBCP and the polyamide 6 fabric was weak, resulting in the modified polyamide 6 fabric still having poor flame retardancy and water washability.

[0007] The modified cyclotriphosphazene flame retardants disclosed in the above three documents generally have the disadvantage of weak bonding between the flame retardant and polyamide 6 fabric. In order to increase the bonding between the modified cyclotriphosphazene flame retardant and polyamide 6 fabric, the prior art uses polydopamine to modify the cyclotriphosphazene. For example, patent application CN113801472A discloses a method for preparing a novel halogen-free phosphorus-nitrogen flame retardant and a method for preparing a flame-retardant composite material thereof. The method uses dopamine and hexachlorocyclotriphosphazene to prepare a polydopamine-modified cyclotriphosphazene flame retardant. Since polydopamine has adhesion ability, the bonding between the polydopamine-modified cyclotriphosphazene flame retardant and polyamide 6 fabric is improved. However, the carbonization performance of polyamide 6 fiber is poor. The modified polyamide 6 fabric prepared by using the polydopamine-modified cyclotriphosphazene flame retardant still has a molten drop phenomenon, and the flame retardant efficiency still needs to be improved.

[0008] Therefore, there is an urgent need to develop an intumescent flame retardant that can improve the flame retardancy and washability of polyamide 6 fabrics. Summary of the invention

[0009] The purpose of the present invention is to solve the problems existing in the prior art and to provide an intumescent flame retardant, an intumescent flame retardant finishing liquid and a preparation method and application thereof.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing an intumescent flame retardant finishing liquid, comprising the following steps:

[0012] (1) Hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, an acid-binding agent (triethylamine, which is conducive to the full modification reaction) and solvent a (tetrahydrofuran) are mixed to obtain a reaction system a with a pH value of ≤7 (hexachlorocyclotriphosphazene and dopamine hydrochloride are slightly acidic, so that the pH value of the reaction system a is ≤7), reacting at 55-65°C for 2-3h, and post-processing (cooling, filtering, removing the solvent, washing with distilled water and ethanol) to obtain a modified cyclotriphosphazene;

[0013] The possible reactions between hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose are: ① the active chlorine of hexachlorocyclotriphosphazene reacts with the amino group of dopamine hydrochloride and the hydroxyl group of glucose respectively to undergo nucleophilic substitution reaction; ② glucose self-polymerizes; ③ dopamine hydrochloride self-polymerizes; wherein, reaction ① has low requirements on conditions and is very easy to occur; reaction ② needs to be carried out under alkaline conditions, and the pH value of the reaction system a of the present invention is ≤7, so reaction ② will not occur; reaction ③ requires a catalyst, high temperature or long time, and the reaction system a of the present invention does not contain a catalyst, the temperature is low, and the time is short, so reaction ③ can be almost omitted;

[0014] (2) preparing a reaction system b containing modified cyclotriphosphazene, solvent b (a mixed solution of tetrahydrofuran and water, wherein the volume proportion of tetrahydrofuran in solvent b is 30-40%), dopamine hydrochloride, glucose, hydrogen peroxide, and a pH value > 7 (which can be adjusted by adding sodium hydroxide), and reacting at 75-85°C to obtain an intumescent flame retardant finishing liquid;

[0015] Under alkaline conditions (pH>7), catalyst (hydrogen peroxide), and high temperature (75~85℃), the modified cyclotriphosphazene in reaction system b will undergo the following changes:

[0016] a) The dopamine hydrochloride structure on the modified cyclotriphosphazene undergoes a Maillard reaction with glucose to generate a Maillard product;

[0017] b) The dopamine hydrochloride structure on the modified cyclotriphosphazene reacts with the catechol structure on the dopamine hydrochloride to form polydopamine;

[0018] c) The glucose structure on the modified cyclotriphosphazene undergoes a Maillard reaction with dopamine hydrochloride to generate a Maillard product;

[0019] d) the glucose structure on the modified cyclotriphosphazene undergoes polymerization reaction with glucose;

[0020] e) further polymerization reaction occurs between polydopamine, Maillard product, dopamine hydrochloride and glucose;

[0021] In this way, the modified cyclotriphosphazene has both polydopamine segments and Maillard product segments, and the two segments are interspersed and tightly combined.

[0022] As the preferred technical solution:

[0023] The method for preparing an intumescent flame retardant finishing liquid as described above, in step (1), the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:3~4:3.5~2.5. Theoretically, six active chlorine groups per mole of hexachlorocyclotriphosphazene can undergo nucleophilic substitution reaction with active hydroxyl groups of dopamine hydrochloride and glucose, and keeping the total molar amount of dopamine hydrochloride and glucose in excess is conducive to complete modification of hexachlorocyclotriphosphazene; the molar ratio of hexachlorocyclotriphosphazene to acid binding agent is 1:6~7; and the dosage ratio of hexachlorocyclotriphosphazene to solvent a is 1g:40~50mL.

[0024] In the method for preparing an intumescent flame retardant finishing liquid as described above, in step (2), the molar ratio of modified cyclotriphosphazene, dopamine hydrochloride and glucose is 1:2~2.5:2~2.5; in the reaction system b, the content of modified cyclotriphosphazene is 35~50 g / L, and the content of hydrogen peroxide is 5~10 g / L; the pH value of the reaction system b is 10~11; and the reaction time is 3~4 h.

[0025] The present invention also provides an intumescent flame retardant finishing liquid, which is prepared by the preparation method of an intumescent flame retardant finishing liquid as described in any one of the above items.

[0026] The present invention also provides a method for preparing an intumescent flame retardant, and the intumescent flame retardant is obtained by purifying the intumescent flame retardant finishing liquid as described above.

[0027] The present invention also provides an intumescent flame retardant, which is prepared by the preparation method of the intumescent flame retardant as described above; in the structure of the intumescent flame retardant, the cyclotriphosphazene structure serves as an acid source and a gas source, the polydopamine structure serves as a gas source, and the Maillard product structure serves as a carbon source. Multiple components are organically combined to construct an intumescent flame retardant system with strong carbonization performance and high flame retardant efficiency.

[0028] The present invention also provides a method for preparing a durable flame-retardant polyamide 6 fabric, comprising adding the polyamide 6 fabric into an intumescent flame retardant finishing liquid as described above, reacting at 75-85°C, and obtaining the durable flame-retardant polyamide 6 fabric through post-treatment (taking out, washing, and drying); in this process, polydopamine and Maillard products in the intumescent flame retardant finishing liquid adhere to the polyamide 6 fabric by virtue of their own high adhesion properties, and on the other hand, covalently react with the amino groups of the polyamide 6 fibers and are grafted onto the polyamide 6 fabric.

[0029] As the preferred technical solution:

[0030] In the method for preparing a durable flame-retardant polyamide 6 fabric as described above, the bath ratio of the polyamide 6 fabric to the intumescent flame retardant finishing liquid is 1:40-50, and the reaction time is 2-3 hours.

[0031] The present invention also provides a durable flame retardant polyamide 6 fabric, which is prepared by the method for preparing the durable flame retardant polyamide 6 fabric as described above.

[0032] As the preferred technical solution:

[0033] The durable flame retardant polyamide 6 fabric as described above has a limiting oxygen index of not less than 29.5%, a damaged length of not more than 11.5 cm, no molten droplets are generated, and after 40 times of washing, the damaged length is still less than 14.7 cm, no molten droplets are generated, and has excellent flame retardant and anti-molten droplet properties and water washing resistance.

[0034] Beneficial effects:

[0035] (1) The intumescent flame retardant structure of the present invention contains both polydopamine segments and Maillard product segments, which are interlaced and tightly combined with each other. On the one hand, polydopamine and Maillard have a high adhesion to polyamide 6 fabric, which helps to improve the adsorption of the flame retardant system on the polyamide 6 fabric. On the other hand, the two are firmly combined and remain combined with each other under the action of water washing, thereby providing high water washing resistance.

[0036] (2) In the structure of the intumescent flame retardant of the present invention, the cyclotriphosphazene structure acts as an acid source and a gas source, the polydopamine structure acts as a gas source, and the Maillard product structure acts as a carbon source. The various components are organically combined to construct an intumescent flame retardant system, which has strong carbonization performance, high flame retardant efficiency, and excellent flame retardant performance; the polydopamine structure and the Maillard product structure, on the one hand, rely on their own high adhesion properties to adhere to the polyamide 6 fabric, and on the other hand, react with the amino group of the polyamide 6 fiber and are grafted onto the polyamide 6 fabric through covalent bonds, so that the intumescent flame retardant and the polyamide 6 fabric are firmly combined, and have excellent water wash resistance.

[0037] (3) The preparation method of the present invention has mild conditions, readily available raw materials, and is suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the SEM image of the durable flame retardant polyamide 6 fabric of Example 1. DETAILED DESCRIPTION

[0039] 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.

[0040] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0041] Limiting oxygen index: Tested in accordance with GB / T 5454-1997 "Oxygen Index Method for Textile Combustion Performance Test".

[0042] 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.

[0043] Damaged length and presence of droplets after 40 washes: First wash the fabric 40 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 droplets during the test.

[0044] The unmodified polyamide 6 fabric used in the following examples and comparative examples had a damaged length of 30 cm and a limiting oxygen index of 20.1%.

[0045] Example 1

[0046] A method for preparing an intumescent flame retardant finishing liquid, the specific steps are as follows:

[0047] (1) Hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, triethylamine and solvent a are mixed to obtain reaction system a, wherein solvent a is tetrahydrofuran, the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:3:2.5, the molar ratio of hexachlorocyclotriphosphazene to triethylamine is 1:6.5, and the amount ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 1 g:47 mL, reaction system a is reacted at 65° C. for 2 h, cooled, filtered, the solvent is removed, and washed with distilled water and ethanol to obtain modified cyclotriphosphazene;

[0048] (2) A reaction system b with a pH value of 11 consisting of modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, hydrogen peroxide and sodium hydroxide was prepared. The solvent b was a mixed solution of tetrahydrofuran and water. The volume proportion of tetrahydrofuran in the solvent b was 37%. The molar ratio of the modified cyclotriphosphazene, dopamine hydrochloride and glucose was 1:2.5:2.5. The content of the modified cyclotriphosphazene in the reaction system b was 45 g / L. The content of the hydrogen peroxide in the reaction system b was 9 g / L. The reaction system b was reacted at 85° C. for 3 h to obtain an intumescent flame retardant finishing liquid. The intumescent flame retardant finishing liquid was purified to obtain an intumescent flame retardant.

[0049] A method for preparing a durable flame-retardant polyamide 6 fabric comprises the following specific steps: adding unmodified polyamide 6 fabric into the above-mentioned intumescent flame retardant finishing liquid, wherein the bath ratio of the unmodified polyamide 6 fabric to the intumescent flame retardant finishing liquid is 1:50, reacting at 85°C for 2.6 hours, taking out, washing and drying, and obtaining the durable flame-retardant polyamide 6 fabric.

[0050] The final durable flame retardant polyamide 6 fabric (such as Figure 1 The limiting oxygen index of the steel sheet (as shown) was 31.3%, the damaged length was 9.6 cm, and no molten droplets were produced. After 40 water washes, the damaged length was 13.4 cm, and no molten droplets were produced.

[0051] Example 2

[0052] A method for preparing an intumescent flame retardant finishing liquid, the specific steps are as follows:

[0053] (1) Hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, triethylamine and solvent a are mixed to obtain reaction system a, wherein solvent a is tetrahydrofuran, the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:4:3.5, the molar ratio of hexachlorocyclotriphosphazene to triethylamine is 1:6.3, and the amount ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 1 g:43 mL. Reaction system a is reacted at 60° C. for 2.5 h, cooled, filtered, the solvent is removed, and washed with distilled water and ethanol to obtain modified cyclotriphosphazene;

[0054] (2) A reaction system b with a pH value of 10.5 consisting of modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, hydrogen peroxide and sodium hydroxide was prepared. The solvent b was a mixed solution of tetrahydrofuran and water. The volume proportion of tetrahydrofuran in the solvent b was 34%. The molar ratio of the modified cyclotriphosphazene, dopamine hydrochloride and glucose was 1:2.5:2. The content of the modified cyclotriphosphazene in the reaction system b was 40 g / L. The content of the hydrogen peroxide in the reaction system b was 6 g / L. The reaction system b was reacted at 80° C. for 3.5 h to obtain an intumescent flame retardant finishing liquid. The intumescent flame retardant finishing liquid was purified to obtain an intumescent flame retardant.

[0055] A method for preparing a durable flame-retardant polyamide 6 fabric comprises the following specific steps: adding unmodified polyamide 6 fabric into the above-mentioned intumescent flame retardant finishing liquid, wherein the bath ratio of the unmodified polyamide 6 fabric to the intumescent flame retardant finishing liquid is 1:45, reacting at 80°C for 2.3h, taking out, washing and drying, and obtaining the durable flame-retardant polyamide 6 fabric.

[0056] The final durable flame retardant polyamide 6 fabric had a limiting oxygen index of 30.6%, a damaged length of 10.4 cm, and no molten droplets were generated. After 40 washes, the damaged length was 13.9 cm, and no molten droplets were generated.

[0057] Example 3

[0058] A method for preparing an intumescent flame retardant finishing liquid, the specific steps are as follows:

[0059] (1) Hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, triethylamine and solvent a are mixed to obtain reaction system a, wherein solvent a is tetrahydrofuran, the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:3:3.5, the molar ratio of hexachlorocyclotriphosphazene to triethylamine is 1:6, and the amount ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 1 g:40 mL, reaction system a is reacted at 55° C. for 3 h, cooled, filtered, the solvent is removed, and washed with distilled water and ethanol to obtain modified cyclotriphosphazene;

[0060] (2) A reaction system b with a pH value of 10 consisting of modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, hydrogen peroxide, and sodium hydroxide is prepared. The solvent b is a mixed solution of tetrahydrofuran and water. The volume proportion of tetrahydrofuran in the solvent b is 30%. The molar ratio of the modified cyclotriphosphazene, dopamine hydrochloride, and glucose is 1:2:2. The content of the modified cyclotriphosphazene in the reaction system b is 35 g / L. The content of the hydrogen peroxide in the reaction system b is 5 g / L. The reaction system b is reacted at 75° C. for 4 h to obtain an intumescent flame retardant finishing liquid. The intumescent flame retardant finishing liquid is purified to obtain an intumescent flame retardant.

[0061] A method for preparing a durable flame-retardant polyamide 6 fabric comprises the following specific steps: adding unmodified polyamide 6 fabric into the above-mentioned intumescent flame retardant finishing liquid, wherein the bath ratio of the unmodified polyamide 6 fabric to the intumescent flame retardant finishing liquid is 1:40, reacting at 75°C for 2h, taking out, washing and drying, and obtaining the durable flame-retardant polyamide 6 fabric.

[0062] The final durable flame retardant polyamide 6 fabric had a limiting oxygen index of 29.5%, a damaged length of 11.5 cm, and no molten droplets were generated. After 40 washes, the damaged length was 14.7 cm, and no molten droplets were generated.

[0063] Comparative Example 1

[0064] A method for preparing a flame retardant finishing liquid is basically the same as that of Example 3, except that in step (1) and step (2), dopamine hydrochloride is replaced by an equimolar amount of glucose.

[0065] A method for preparing a flame retardant polyamide 6 fabric is basically the same as the method for preparing a durable flame retardant polyamide 6 fabric in Example 3, except that the flame retardant finishing liquid prepared in this comparative example is used to replace the intumescent flame retardant finishing liquid in Example 3.

[0066] The final flame retardant polyamide 6 fabric had a limiting oxygen index of 28.3%, a damaged length of 11.9 cm, and no molten droplets were generated. After 40 washes, the damaged length was 30 cm, and molten droplets were generated.

[0067] Compared with Example 3, the flame retardant properties of the flame retardant polyamide 6 fabric prepared in Comparative Example 1 are reduced, and its water washing resistance is reduced. This is because polydopamine can provide a gas source, and the absence of polydopamine causes the flame retardant performance of the flame retardant system to be reduced, and single glucose is polymerized into caramel, and its adhesion to the polyamide 6 fabric is reduced. The Maillard product formed with the participation of polydopamine has a higher adhesion to the polyamide 6 fabric, which is beneficial to improving the flame retardant properties and water washing resistance.

[0068] Comparative Example 2

[0069] A method for preparing a flame retardant finishing liquid is basically the same as that of Example 3, except that in step (1) and step (2), glucose is replaced by an equimolar amount of dopamine hydrochloride.

[0070] A method for preparing a flame retardant polyamide 6 fabric is basically the same as the method for preparing a durable flame retardant polyamide 6 fabric in Example 3, except that the flame retardant finishing liquid prepared in this comparative example is used to replace the intumescent flame retardant finishing liquid in Example 3.

[0071] The final flame retardant polyamide 6 fabric had a limiting oxygen index of 27.3%, a damaged length of 12.8 cm, and molten droplets were generated. After 40 washes, the damaged length was 30 cm, and molten droplets were generated.

[0072] Compared with Example 3, the limiting oxygen index of the flame-retardant polyamide 6 fabric prepared in Comparative Example 2 is significantly reduced, the damaged length is significantly increased, and its flame retardant performance and water wash resistance are poor. This is because the unmodified polyamide 6 fiber has poor charring performance. Glucose, as a charring agent, can be charred under the catalysis of a phosphorus-containing flame retardant. Failure to add a charring agent results in poor charring performance of the flame-retardant polyamide 6 fabric prepared in Comparative Example 2, and the droplet phenomenon still exists.

[0073] Example 4

[0074] A method for preparing an intumescent flame retardant finishing liquid, the specific steps are as follows:

[0075] (1) Hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, triethylamine and solvent a are mixed to obtain reaction system a, wherein solvent a is tetrahydrofuran, the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:3.5:3, the molar ratio of hexachlorocyclotriphosphazene to triethylamine is 1:7, and the amount ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 1 g:50 mL. Reaction system a is reacted at 58° C. for 2.4 h, cooled, filtered, the solvent is removed, and washed with distilled water and ethanol to obtain modified cyclotriphosphazene;

[0076] (2) A reaction system b with a pH value of 10.5 consisting of modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, hydrogen peroxide and sodium hydroxide was prepared. The solvent b was a mixed solution of tetrahydrofuran and water. The volume proportion of tetrahydrofuran in the solvent b was 40%. The molar ratio of the modified cyclotriphosphazene, dopamine hydrochloride and glucose was 1:2.3:2.4. The content of the modified cyclotriphosphazene in the reaction system b was 50 g / L. The content of the hydrogen peroxide in the reaction system b was 10 g / L. The reaction system b was reacted at 82° C. for 3.2 h to obtain an intumescent flame retardant finishing liquid. The intumescent flame retardant finishing liquid was purified to obtain an intumescent flame retardant.

[0077] A method for preparing a durable flame-retardant polyamide 6 fabric comprises the following specific steps: adding unmodified polyamide 6 fabric into the above-mentioned intumescent flame retardant finishing liquid, wherein the bath ratio of the unmodified polyamide 6 fabric to the intumescent flame retardant finishing liquid is 1:45, reacting at 82°C for 3h, taking out, washing and drying, and obtaining the durable flame-retardant polyamide 6 fabric.

[0078] The final durable flame-retardant polyamide 6 fabric had a limiting oxygen index of 32.2%, a damaged length of 8.9 cm, and no molten droplets were generated. After 40 washes, the damaged length was 13.1 cm, and no molten droplets were generated.

Claims

1. A method for preparing an intumescent flame retardant finishing liquid, It is characterized in that Here are the steps: (1) mixing hexachlorocyclotriphosphazene, dopamine hydrochloride, glucose, an acid-binding agent and a solvent a to obtain a reaction system a with a pH value of ≤7, reacting at 55 to 65°C for 2 to 3 hours, and obtaining a modified cyclotriphosphazene through post-treatment; (2) preparing a reaction system b containing modified cyclotriphosphazene, solvent b, dopamine hydrochloride, glucose, and hydrogen peroxide with a pH value greater than 7, and reacting at 75 to 85° C. to obtain an intumescent flame retardant finishing liquid.

2. A method for preparing an intumescent flame retardant finishing liquid according to claim 1, It is characterized in that In step (1), the molar ratio of hexachlorocyclotriphosphazene, dopamine hydrochloride and glucose is 1:3-4:2.5-3.5; the molar ratio of hexachlorocyclotriphosphazene to the acid binding agent is 1:6-7; and the dosage ratio of hexachlorocyclotriphosphazene to solvent a is 1 g:40-50 mL.

3. A method for preparing an intumescent flame retardant finishing liquid according to claim 1, It is characterized in that In step (2), the molar ratio of modified cyclotriphosphazene, dopamine hydrochloride and glucose is 1:2-2.5:2-2.5; in reaction system b, the content of modified cyclotriphosphazene is 35-50 g / L, and the content of hydrogen peroxide is 5-10 g / L; the pH value of reaction system b is 10-11; The reaction time is 3 to 4 hours.

4. An intumescent flame retardant finishing liquid, It is characterized in that The invention is prepared by the method for preparing an intumescent flame retardant finishing liquid as described in any one of claims 1 to 3.

5. A method for preparing an intumescent flame retardant, It is characterized in that The intumescent flame retardant finishing liquid as claimed in claim 4 is purified to obtain the intumescent flame retardant.

6. An intumescent flame retardant, It is characterized in that The intumescent flame retardant is prepared by the method for preparing an intumescent flame retardant as claimed in claim 5.

7. A method for preparing a durable flame retardant polyamide 6 fabric, It is characterized in that The polyamide 6 fabric is added into the intumescent flame retardant finishing liquid as claimed in claim 4, reacted at 75-85° C., and post-treated to obtain the durable flame retardant polyamide 6 fabric.

8. The method for preparing a durable flame retardant polyamide 6 fabric according to claim 7, It is characterized in that The bath ratio of polyamide 6 fabric to intumescent flame retardant finishing liquid is 1:40-50, and the reaction time is 2-3 hours.

9. A durable flame retardant polyamide 6 fabric, It is characterized in that The fabric is prepared by the method for preparing a durable flame retardant polyamide 6 fabric as described in claim 7 or 8.

10. A durable flame retardant polyamide 6 fabric according to claim 9, It is characterized in that The limiting oxygen index of the durable flame retardant polyamide 6 fabric is not less than 29.5%, the damaged length is not higher than 11.5 cm, no molten droplets are generated, and after 40 times of washing, the damaged length is still less than 14.7 cm, and no molten droplets are generated.

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