Flame-retardant coating and flame-retardant coating forming process of flame-retardant chemical fiber rope

Abstract

The invention provides a flame-retardant coating and a chemical fiber rope coating forming process. The coating is prepared from 50 to 70 parts of PTFE (Polytetrafluoroethylene) base material, 1 to 2 parts of amino modified nano silicon dioxide, 4 to 8 parts of ammonium polyphosphate, 3 to 6 parts of melamino-formaldehyde resin, a dispersing agent and a curing regulator. Wherein the amino modified nano silicon dioxide is prepared through KH550 grafting, and forms ionic bonding with ammonium polyphosphate to solve the dispersion problem; the melamine formaldehyde resin and ammonium polyphosphate synergistically construct a flame-retardant system. The process comprises the steps of base material pretreatment, step-by-step dispersion, dip coating and step curing (80-180 DEG C segmented temperature control). The dispersion is enhanced through chemical bonding, the carbon layer is formed, the breakthrough of efficient flame retardance and wear resistance is synchronously achieved, and the problem that the mechanical performance of the flame-retardant chemical fiber is degraded is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flame-retardant coating, and particularly relates to a flame-retardant coating and a flame-retardant coating forming process for flame-retardant chemical fiber ropes. BACKGROUND

[0002] At present, the field of flame-retardant chemical fibers generally faces the technical bottleneck that flame retardancy and mechanical properties (especially wear resistance) are difficult to be optimized simultaneously. The traditional solution mainly relies on flame retardant compounding or surface modification. The synergistic system of ammonium polyphosphate and silicon dioxide is widely used because it has both gas-phase flame retardation and condensed-phase carbonization: ammonium polyphosphate acts as an acid source and a gas source, and releases polyphosphoric acid and inert gas upon heating; silicon dioxide improves the flame-retardant efficiency by promoting the formation of a dense carbon layer, insulating heat and oxygen diffusion. However, this system still has a significant defect - the wear resistance is severely deteriorated. The root cause is that ammonium polyphosphate and silicon dioxide are mainly physically mixed, and the two lack chemical bonding, resulting in uneven dispersion and weak interfacial bonding. Under frictional stress, ammonium polyphosphate particles are easily peeled off from the polymer matrix, forming stress concentration points and accelerating the wear of the coating. Experiments show that the wear resistance test of a typical ammonium polyphosphate / silicon dioxide physical mixing system treated chemical fiber rope is only about 3600r or so.

[0003] Although the compatibility can be improved by microencapsulation technology (such as silicon sol coated ammonium polyphosphate), such process needs precise control of the sol-gel process, and has problems such as complicated steps, high cost, and insufficient stability in large-scale production.

[0004] Therefore, how to simultaneously have the flame retardancy and mechanical wear resistance of the ammonium polyphosphate flame-retardant system is still a technical problem worthy of study in the field. SUMMARY

[0005] The flame-retardant coating and the flame-retardant coating forming process for flame-retardant chemical fiber ropes provided by the present application adopt the following technical solutions:

[0006] Firstly, the present application provides a flame-retardant coating, which adopts the following technical solutions:

[0007] A flame-retardant coating, comprising the following components by weight:

[0008] 50-70 parts of PTFE substrate, 1-2 parts of amino-modified nano-silicon dioxide, 4-8 parts of ammonium polyphosphate, 3-6 parts of melamine formaldehyde resin, 0.4-0.6 parts of dispersing agent, and 0.2-0.3 parts of curing regulator.

[0009] In one specific embodiment, the preparation method of the amino-modified nanosilica comprises the following steps: taking 20 parts of deionized water, 20 parts of KH550, and 160 parts of ethanol, and stirring to mix thoroughly; taking 2 parts of silica, heating to 80 DEG C, and then slowly adding the solution mixed with KH550 into the silica-containing suspension; after the addition is completed, filtering and drying to obtain the amino-modified nanosilica.

[0010] In one specific embodiment, the dispersant is sodium hexametaphosphate.

[0011] In one specific embodiment, the curing regulator is propargyl alcohol.

[0012] Secondly, based on the above flame-retardant coating, the application provides a flame-retardant coating forming process for flame-retardant chemical fiber ropes, which adopts the following technical scheme:

[0013] A flame-retardant coating forming process for flame-retardant chemical fiber ropes, comprising the following steps:

[0014] S1, substrate pretreatment: the chemical fiber rope is soaked in a 5% NaOH solution at 60 DEG C for 10 min; and hot air drying at 80 DEG C for 30 min to ensure that the water content of the substrate is less than 0.5%.

[0015] S2, coating pre-dispersion: the PTFE substrate, deionized water, and dispersant are added into a high-speed shearing emulsifier at a weight percentage of 3000 rpm; the amino-modified nanosilica is slowly added at a weight percentage of 40 kHz, and ultrasonic treatment is performed for 20 min to destroy the agglomerates; the ammonium polyphosphate is added at a weight percentage, and the temperature is controlled to be less than or equal to 40 DEG C, and the shearing is continued for 30 min; the temperature is lowered to 25 DEG C, and the melamine formaldehyde resin and the curing regulator are added at a weight percentage, and low-speed stirring is performed at 500 rpm for 10 min;

[0016] S3, coating process: the pretreated rope passes through the coating tank at a speed of 2 m / min, and the immersion time is 30 s; the wet film thickness is controlled to be 150 microns by the extrusion roller; and hot air circulation is performed at 60 DEG C for 5 min to remove the bubbles in the coating;

[0017] S4, curing and crosslinking;

[0018] S5, cooling and shaping: air cooling to below 50 DEG C at room temperature.

[0019] In one specific embodiment, the curing and crosslinking process of S4 comprises three stages: in the first stage, the hot air circulation is controlled, the wind speed is 5 m / s, the temperature is 80-100 DEG C, and the time is 10 min; in the second stage, the heating is maintained, the temperature control accuracy is ± 2 DEG C, the temperature is 120-140 DEG C, and the time is 15 min; and in the third stage, the temperature is controlled to be 160-180 DEG C under nitrogen protection, and the time is 20 min.

[0020] The present application has the following beneficial effects:

[0021] Flame-retardant performance is improved: the dense carbon layer formed by ammonium polyphosphate and melamine formaldehyde resin has the functions of gas-phase flame retardation, condensed-phase heat insulation and free radical quenching, so that the rope has zero after-flame after leaving the flame, and the burning speed tends to zero; at the same time, the ionically bonded ammonium polyphosphate and melamine formaldehyde resin form a crosslinked network through the pre-fixing of amino-modified nano-silicon dioxide, and the wear resistance reaches 5842 turns, which solves the contradiction between the flame-retardant performance and the wear resistance of the ammonium polyphosphate flame-retardant system applied in the field of chemical fiber ropes. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flame-retardant test result graph of Comparative Example 1;

[0023] Figure 2 is a flame-retardant test result graph of Comparative Example 2;

[0024] Figure 3 is a flame-retardant test result graph of Comparative Example 3;

[0025] Figure 4 is a flame-retardant test result graph of Example 4 and Example 6;

[0026] Figure 5 is a flame-retardant test result graph of Example 5;

[0027] Figure 6 is a micro-characterization graph of the burning part of the rope surface coating of Example 5. DETAILED DESCRIPTION

[0028] The present application will be further described in detail below in combination with specific embodiments.

[0029] The flame-retardant chemical fibers widely used in the market have various problems, and the most important problem is that it is difficult to reconcile the loss of flame-retardant performance and wear resistance. The applicant combines his own experience and searches and finds that the synergistic effect of ammonium polyphosphate and silicon dioxide in widely used flame retardants can achieve relatively good flame-retardant effect, but there is still a technical problem of loss of mechanical properties (such as wear rate), and even if there are microcapsules, crosslinking and other methods to improve, it is difficult to implement in the industry. For example, the microcapsule has the technical problem of too complex technical scheme and difficult mass production, and is still at the laboratory stage or small test stage; if a new crosslinking material is used, there is no crosslinked network system with good flame-retardant performance and good wear resistance in the market, which is a difficult problem in the industry.

[0030] The applicant, from the perspective of the industry, deeply cultivates the innovation of the cross-linking network, and intends to find a brand-new cross-linking system that can increase the flame retardancy of the chemical fiber rope and maintain its wear resistance, so that the chemical fiber rope can be more widely applied to the market.

[0031] In the applicant's research and development process, it was found that it was difficult to combine ammonium polyphosphate and silicon dioxide, and they were basically physically mixed, because silicon dioxide itself is relatively stable in nature and does not have a bonding effect with ammonium polyphosphate. Therefore, the applicant performed an amino functionalization treatment on the silicon dioxide, so that the silicon dioxide was grafted with amino groups, thereby using the amino-functionalized silicon dioxide and ammonium polyphosphate to bond and solve the problem of dispersion.

[0032] Further, the applicant continues to find a resin that can cross-link with ammonium polyphosphate and can be industrialized. First, ammonium polyphosphate itself as a flame retardant substance has the following defects: 1. Hydrophilicity. Ammonium polyphosphate is prone to moisture absorption, resulting in the failure of the flame-retardant coating, with a solubility of up to 0.2 g / 100 g of water. 2. Poor compatibility. The dispersion of ammonium polyphosphate in the polymer is slightly uneven, affecting the mechanical properties. 3. The strength of the char layer formed by ammonium polyphosphate alone is very low, making the wear resistance of the flame-retardant coating poor and unable to be applied to high-wear-strength environments. Therefore, it is particularly important to find a cross-linking network. After a large number of experiments and theoretical verification, the applicant found that in the field of flame-retardant coatings for chemical fibers, the cross-linking network system formed by ammonium polyphosphate and melamine formaldehyde resin has outstanding substantive characteristics, can maintain good wear resistance of chemical fibers while providing excellent flame retardancy, and its core lies in the ingenious component ratio design, efficient flame-retardant synergistic mechanism, and the irreplaceability brought by the unique chemical properties of melamine formaldehyde resin. The cross-linking network formed by ammonium polyphosphate and melamine formaldehyde resin will be described in detail below in combination with the mechanism.

[0033] The ammonium polyphosphate and melamine formaldehyde resin system is essentially a high-efficiency gas / condensed phase synergistic flame-retardant system, with three key synergistic effects: first, ammonium polyphosphate acts as an acid source and releases dehydrating inorganic acids such as polyphosphoric acid upon heating. Second, melamine formaldehyde resin acts as a carbon source and contains a large amount of carbon and nitrogen, and most importantly, under the catalysis of the acid released by polyphosphoric acid upon heating, the active groups such as hydroxymethyl in melamine formaldehyde resin participate in the reaction, ultimately forming an aromatic carbon structure rich in nitrogen elements, forming the basic skeleton of the carbon layer. Third, from the perspective of flame-retardant gases, ammonium polyphosphate releases ammonia and water vapor upon heating, and melamine formaldehyde resin can also release ammonia, nitrogen, carbon dioxide, and other flame-retardant gases upon heating, further optimizing the flame retardancy of the system.

[0034] Based on the above mechanism and experiments, the following flame-retardant process can be inferred: when the coating is heated to the decomposition temperature, ammonium polyphosphate decomposes first to release polyphosphoric acid and ammonia. Polyphosphoric acid catalyzes the dehydration, crosslinking and carbonization of melamine formaldehyde resin. This process rapidly aromatizes and crosslinks the carbon skeleton that may have been decomposed into combustible small molecules in the melamine formaldehyde resin under acid catalysis, forming a preliminary nitrogen-rich viscous carbonaceous melt. At the same time, a large amount of inert gas generated by the decomposition of ammonium polyphosphate and melamine formaldehyde resin is wrapped in the viscous carbonizing melt. The gas expands under heat, pushing the melt to expand and foam. As the reaction proceeds, the melt forms a dense and solid carbon layer under the action of gas expansion. The carbon layer is finally solidified and covers the surface of the protected synthetic fiber substrate.

[0035] The application will be further described in detail below in conjunction with examples and experimental results.

[0036] Preparation Example: Preparation of amino-modified nanosilica

[0037] Take 200g of deionized water, 200g of KH550, and 1600g of ethanol, and mix them thoroughly under stirring. Take 20g of silica, heat it to 80℃, and then slowly add the solution containing KH550 to the silica suspension. After the addition is complete, filter and dry to obtain the amino-modified nanosilica.

[0038] Example 1

[0039] This example provides a coating for forming a flame-retardant coating of synthetic fiber, which includes the following components by weight:

[0040] PTFE substrate: DuPont polytetrafluoroethylene 851G coating is selected as the base, accounting for 50 parts; amino-modified nanosilica: 1 part; ammonium polyphosphate: 4 parts; melamine formaldehyde resin: 3 parts; dispersant: sodium hexametaphosphate, 0.4 parts; curing regulator: propargyl alcohol, 0.2 parts.

[0041] The amino-modified nanosilica is prepared by the preparation example.

[0042] Example 2

[0043] This example provides a coating for forming a flame-retardant coating of synthetic fiber, which includes the following components by weight:

[0044] PTFE substrate: DuPont polytetrafluoroethylene 851G coating is selected as the base, accounting for 60 parts; amino-modified nanosilica: 1.5 parts; ammonium polyphosphate: 6 parts; melamine formaldehyde resin: 5 parts; dispersant: sodium hexametaphosphate, 0.5 parts; curing regulator: propargyl alcohol, 0.25 parts.

[0045] The amino-modified nanosilica is prepared by the preparation example.

[0046] Example 3

[0047] The present example provides a coating for forming a flame-retardant coating of chemical fiber, comprising the following components by weight:

[0048] PTFE substrate: DuPont polytetrafluoroethylene 851G coating is selected as the matrix, 70 parts; amino-modified nano-silica: 2 parts; ammonium polyphosphate: 8 parts; melamine formaldehyde resin: 6 parts; dispersant: sodium hexametaphosphate, 0.6 parts; curing regulator: propargyl alcohol, 0.3 parts.

[0049] The amino-modified nano-silica is prepared by the preparation example.

[0050] Example 4

[0051] The present example provides a flame-retardant coating forming process for flame-retardant chemical fiber ropes, the weight percentage of the coating uses the ratio disclosed in Example 1, comprising the following steps:

[0052] S1, substrate pretreatment

[0053] The chemical fiber rope is soaked in a 5% concentration NaOH solution at 60°C for 10 minutes to remove surface oil and increase roughness;

[0054] Drying: hot air drying at 80°C for 30 minutes to ensure that the water content of the substrate is <0.5%.

[0055] S2, coating pre-dispersion

[0056] The PTFE substrate, deionized water, and sodium hexametaphosphate dispersant are added to a high-speed shearing emulsifier at a weight percentage of 3000 rpm;

[0057] Slowly add the amino-modified nano-silica at a weight percentage, and treat with ultrasound at 40 kHz for 20 minutes to break up the agglomerates;

[0058] Add ammonium polyphosphate at a weight percentage, control the temperature ≤40°C, and continue shearing for 30 minutes to achieve pre-fixing by forming ionic bonds between the amino groups of the amino-modified nano-silica and the phosphate groups of the ammonium polyphosphate;

[0059] Cool to 25°C, add melamine formaldehyde resin and propargyl alcohol at a weight percentage, and stir at 500 rpm for 10 minutes at low speed to avoid premature crosslinking;

[0060] S3, coating process

[0061] The pretreated rope passes through the coating tank at a speed of 2 m / min, with an immersion time of 30 seconds;

[0062] The wet film thickness is controlled by the extrusion roller to be 150 microns;

[0063] 60℃ hot air circulation 5min, remove bubbles in the coating.

[0064] S4, stepwise curing crosslinking

[0065]

[0066] S5, post-processing

[0067] Cooling and shaping: air cooling at room temperature to below 50℃ to avoid thermal stress cracking of the coating.

[0068] Example 5

[0069] The present example provides a flame-retardant coating forming process for flame-retardant chemical fiber rope, the weight percentage of the coating uses the ratio disclosed in Example 2, including the following steps:

[0070] S1, substrate pretreatment

[0071] The chemical fiber rope is soaked in a 5% concentration NaOH solution at 60℃ for 10min to remove surface oil and increase roughness;

[0072] Drying: hot air drying at 80℃ for 30min to ensure that the moisture content of the substrate is <0.5%.

[0073] S2, coating pre-dispersion

[0074] PTFE substrate, deionized water, and sodium hexametaphosphate dispersant are added to a high-speed shearing emulsifier at a weight percentage of 3000rpm;

[0075] Slowly add amino-modified nano-silicon dioxide at a weight percentage, and treat with ultrasound at 40kHz for 20min to break up agglomerates;

[0076] Add ammonium polyphosphate at a weight percentage, control the temperature ≤40℃, continue shearing for 30min, and use the amino groups of the amino-modified nano-silicon dioxide to form ionic bonds with the phosphate groups of the ammonium polyphosphate to achieve pre-fixing;

[0077] Cool to 25℃, add melamine formaldehyde resin and propargyl alcohol at a weight percentage, stir at 500rpm for 10min at low speed to avoid premature crosslinking;

[0078] S3, coating process

[0079] The pretreated rope passes through the coating tank at a speed of 2m / min, with an immersion time of 30s;

[0080] Control the wet film thickness to be 180 microns by using an extrusion roller;

[0081] 60℃ hot air circulation 5min, remove bubbles in the coating.

[0082] S4, stepwise curing crosslinking

[0083]

[0084] S5, post-processing

[0085] Cooling and setting: air cooling at room temperature to below 50°C to avoid thermal stress cracking of the coating.

[0086] Example 6

[0087] The present example provides a flame-retardant coating forming process for flame-retardant chemical fiber ropes, the weight percentage of the coating uses the ratio disclosed in Example 3, including the following steps:

[0088] S1, substrate pretreatment

[0089] The chemical fiber rope is soaked in a 5% concentration NaOH solution at 60°C for 10 minutes to remove surface oil and increase roughness;

[0090] Drying: hot air drying at 80°C for 30 minutes to ensure that the moisture content of the substrate is <0.5%.

[0091] S2, coating pre-dispersion

[0092] PTFE substrate, deionized water, and sodium hexametaphosphate dispersant are added to a high-speed shearing emulsifier at a weight percentage of 3000 rpm;

[0093] Slowly add amino-modified nano-silicon dioxide at a weight percentage, and treat with ultrasound at 40 kHz for 20 minutes to break up agglomerates;

[0094] Add ammonium polyphosphate at a weight percentage, control the temperature to be ≤40°C, and continue shearing for 30 minutes to form ionic bonds between the amino groups of the amino-modified nano-silicon dioxide and the phosphate groups of the ammonium polyphosphate, achieving pre-fixing;

[0095] Cool to 25°C, add melamine formaldehyde resin and propargyl alcohol at a weight percentage, and stir at 500 rpm for 10 minutes at low speed to avoid premature crosslinking;

[0096] S3, coating process

[0097] The pretreated rope passes through the coating tank at a speed of 2 m / min, with an immersion time of 30 seconds;

[0098] Control the wet film thickness to be 200 microns by using an extrusion roller;

[0099] Hot air circulation at 60°C for 5 minutes to remove bubbles in the coating.

[0100] S4, stepwise curing crosslinking

[0101]

[0102] S5, post-processing

[0103] Cooling and setting: air cooling at room temperature to below 50°C to avoid thermal stress cracking of the coating.

[0104] Comparative Example 1

[0105] This comparative example is a blank control group, and the chemical fiber rope is not subjected to any flame-retardant treatment.

[0106] Comparative Example 2

[0107] This comparative example is compared with Example 5, and the difference is that there is no melamine formaldehyde resin in the components of the coating, and the missing melamine formaldehyde resin is supplemented with ammonium polyphosphate.

[0108] Comparative Example 3

[0109] This comparative example is compared with Example 5, and the difference is that the silica in the components of the coating is not aminated.

[0110] Performance detection experiment

[0111] The performance detection experiment is performed on the above examples and comparative examples, and part of the detection process and detection results are as follows:

[0112] Flame-retardant performance: the horizontal and vertical combustion instrument is used to test the flame-retardant effect, and the horizontal method is used for testing. The testing method is as follows:

[0113] 1. Cut the coated rope sample about 13 cm, and mark at 2.5 cm and 10 cm.

[0114] 2. Clamping the sample on the horizontal operating rod, and supporting the sample with the horizontal support frame.

[0115] 3. Ignite the bunsen burner, adjust the liquefied gas flow, so that the yellow flame of the bunsen burner is 2 cm high, and the inclination is 45°.

[0116] 4. Set the ignition time to 20 s, and ignite the flame near 1 cm of the rope end.

[0117] 5. Test at least 3 samples for each group. There are three phenomena:

[0118] 5.1 The rope stops burning after leaving the flame, or stops burning before reaching the 2.5 cm mark.

[0119] 5.2 Continue to burn after leaving the flame, reach the 10 cm mark, and use a stopwatch to test the continuous burning time from 2.5 cm to 10 cm to determine the burning speed.

[0120] 5.3 After leaving the flame, the rope sample is extinguished between the 2.5-10 cm marks, the burning time is tested by a stopwatch, the burning length is measured, and the burning speed is calculated. The test results are shown in Table 1.

[0121] Table 1: Flame retardant test results

[0122]

[0123] Abrasion resistance: The experimental conditions are shown in Table 2, and the results are shown in Table 3.

[0124] Table 2: Experimental conditions for abrasion resistance

[0125]

[0126] Table 3: Experimental results for abrasion resistance

[0127]

[0128] From the above experimental results, it can be seen that the flame retardant performance and abrasion resistance of Example 5 are excellent, so the SEM microcharacterization of the fiber rope coating of Example 5 is carried out, and the results are shown in Figure 6 . Figure 6 In the SEM, the accelerating voltage is 3.0 kV, the field width x magnification is 4.4 mm x 4.00 k, and the lower right corner is the scale with a unit scale of 10 microns. It can be clearly seen that the microstructure of the dense carbon layer.

[0129] The possible mechanism analysis is combined with the experimental results below.

[0130] From Table 1 and Table 3, it can be seen that the flame retardant effect of Example 5 is the best (completely non-combustible after leaving the flame), and the abrasion resistance is also the most outstanding (5842 turns). The data of Comparative Examples 1-3 are significantly worse.

[0131] The formula of Example 5 contains four key components: PTFE matrix, amino-modified nano-silicon dioxide, ammonium polyphosphate, and melamine formaldehyde resin. The core of excellent flame retardancy lies in the dense carbon layer formed by ammonium polyphosphate and melamine formaldehyde resin. During preparation, the polyphosphoric acid produced by the decomposition of ammonium polyphosphate catalyzes the dehydration and carbonization of melamine formaldehyde resin, and at the same time, the inert gas produced by the decomposition of the two expands to form a dense carbon layer covering the substrate. This carbon layer has three major flame retardant effects: oxygen isolation, heat blocking, and combustible gas dilution. The high nitrogen content of melamine formaldehyde resin may also enhance the flame retardant effect through gas-phase free radical quenching.

[0132] In terms of wear resistance, the amino-modified nano-silica plays a key role. The surface amino groups form ionic bonds with the phosphate groups of the ammonium polyphosphate, solving the problem of agglomeration of inorganic particles. The uniformly dispersed nano-silica strengthens the coating. PTFE itself has lubricity, and in combination with the rigidity of silica, the coating is not easily damaged when rubbed.

[0133] Looking at the comparative examples, Comparative Example 1 is the blank group without any protection, and the chemical fiber directly melts and burns when encountering fire, and the wear resistance is also the worst. Comparative Example 2 lacks melamine formaldehyde resin and only has ammonium polyphosphate and silica. Without melamine formaldehyde resin, a dense carbon layer cannot be formed, and when ammonium polyphosphate acts alone, only a thin and brittle phosphoric acid layer can be generated on the surface, which is easily detached by rubbing. The melting and dripping phenomenon is obvious in the flame retardant test, which is because of the lack of carbon skeleton. Comparative Example 3 uses unaminoated silica. Due to the lack of amino bonding, the silica agglomerates in the coating, forming stress concentration points. When rubbed, these agglomerates are the first to fall off. In terms of flame retardancy, agglomeration leads to uneven dispersion of ammonium polyphosphate, and a complete carbon layer cannot be formed in local areas.

[0134] As can be seen, combining Example 5 and Comparative Example 3, the amino-modified nano-silica solves the dispersion problem of industrialization (Comparative Example 3); combining Example 5 and Comparative Examples 1-2, the ammonium polyphosphate / melamine formaldehyde resin synergistic system has a leap in performance compared to traditional flame retardants. The wear resistance of 5842 revolutions, the flame retardant effect of "extinguishing as soon as leaving the flame", and the dense carbon layer structure in the microscopic characterization fully support the above conclusion.

Claims

1. A flame-retardant coating, characterized in that, It includes the following components in parts by weight: 50-70 parts of PTFE substrate, 1-2 parts of amino-modified nano-silica, 4-8 parts of ammonium polyphosphate, 3-6 parts of melamine-formaldehyde resin, 0.4-0.6 parts of dispersant, and 0.2-0.3 parts of curing regulator.

2. The flame-retardant coating according to claim 1, characterized in that, The preparation method of the amino-modified nano silica includes the following steps: take 20 parts of deionized water, 20 parts of KH550 and 160 parts of ethanol, and stir to mix thoroughly; take 2 parts of silica, heat to 80°C, and then slowly add the solution mixed with KH550 to the suspension containing silica; after the addition is complete, filter and dry to obtain amino-modified nano silica.

3. The flame-retardant coating according to claim 1, characterized in that: The dispersant used is sodium hexametaphosphate.

4. The flame-retardant coating according to claim 1, characterized in that: The curing regulator is propargyl alcohol.

5. A flame-retardant coating molding process for flame-retardant synthetic fiber ropes, based on a flame-retardant coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Substrate pretreatment: The chemical fiber rope is soaked in a 5% NaOH solution at 60°C for 10 minutes; then dried with hot air at 80°C for 30 minutes to ensure that the moisture content of the substrate is <0.5%. S2. Coating pre-dispersion: Add PTFE substrate, deionized water, and dispersant to a high-speed shear emulsifier at 3000 rpm according to weight percentage; slowly add amino-modified nano-silica according to weight percentage, and sonicate at 40 kHz for 20 min to break up agglomerates; add ammonium polyphosphate according to weight percentage, and continue shearing at ≤40℃ for 30 min; cool down to 25℃, add melamine-formaldehyde resin and curing regulator according to weight percentage, and stir at low speed at 500 rpm for 10 min; S3. Coating process: The pre-treated rope passes through the coating tank at a speed of 2m / min and is immersed for 30s. The wet film thickness is controlled to 150 micrometers by extrusion rollers; hot air circulation at 60℃ for 5 minutes removes air bubbles from the coating. S4, Curing and cross-linking; S5. Cooling and shaping: Air cooling at room temperature to below 50℃.

6. The flame-retardant coating molding process for a flame-retardant synthetic fiber rope according to claim 5, characterized in that, The curing and crosslinking process of S4 consists of three stages: the first stage involves controlling the hot air circulation at a speed of 5 m / s, a temperature of 80~100℃, and a time of 10 min; the second stage involves maintaining heating with a temperature control accuracy of ±2℃, a temperature of 120~140℃, and a time of 15 min; and the third stage involves controlling the temperature at 160~180℃ under nitrogen protection for a time of 20 min.

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