Preparation method of tear-resistant flame-retardant polyester fabric

Abstract

The invention relates to the technical field of functional textiles, and discloses a tear-resistant flame-retardant polyester fabric preparation method, which comprises: carrying out surface activation pretreatment on a fabric by using a swelling agent; then, hexaallyl amino cyclotriphosphazene, sulfydryl-terminated hyperbranched polysiloxane, diallyl terephthalate and triallyl borate are adopted to prepare a finishing solution; a thiol-ene click reaction is initiated through padding and ultraviolet light, and a boron-silicon-phosphorus-nitrogen synergistic cross-linked network is constructed on the surface of the fiber in situ. By utilizing the interface anchoring of the diallyl terephthalate and the flexible toughening effect of the hyperbranched polysiloxane, the problems that the tearing strength of the fabric is greatly damaged, the washability is poor and the hand feeling is stiff due to the traditional flame-retardant finishing are effectively solved. The prepared fabric has excellent flame-retardant and anti-dripping performance, high strength retention rate and washing fastness.

Description

Technical Field

[0001] This invention relates to the field of functional textile technology, specifically to a method for preparing a tear-resistant and flame-retardant polyester fabric. Background Technology

[0002] Polyethylene terephthalate (PET) fiber is widely used in the textile, apparel, and industrial sectors due to its excellent tensile strength, abrasion resistance, and chemical stability. However, PET is a flammable polymer that releases a large amount of heat and produces severe dripping during combustion, limiting its application in high-safety applications such as protective clothing and decorative fabrics. To impart flame-retardant properties to polyester fabrics, finishing coating technologies are widely adopted due to their high process adaptability.

[0003] Although finishing processes are well-established, the high crystallinity of polyester fibers and their chemical inertness due to the lack of active polar functional groups on their surface constitute the core technological barrier to flame-retardant finishing. In existing technologies, flame-retardant agents often struggle to penetrate the fiber interior or form strong chemical bonds with the fiber surface, relying primarily on the physical adhesion of resin adhesives to adhere to the fabric surface. This interfacial bonding, based on van der Waals forces or physical-mechanical interlocking, is weak and extremely vulnerable to water shear and mechanical friction.

[0004] This results in the common defect of poor washability in existing flame-retardant polyester fabrics. After repeated washing, the flame-retardant coating that is only attached to the surface is very easy to peel off, causing the flame-retardant performance of the fabric to drop sharply or even become completely ineffective.

[0005] To compensate for this deficiency, existing technologies often use methods such as increasing the amount of crosslinking agent or increasing the coating thickness. However, this not only fails to fundamentally solve the problem of missing interface anchoring, but also causes a serious deterioration in the fabric's hand feel due to excessive coating thickness. Furthermore, the introduction of rigid coatings restricts yarn movement, thereby damaging the fabric's tear strength. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing tear-resistant and flame-retardant polyester fabric, solving the problem of easy peeling off of the surface coating of existing fabrics.

[0007] The first aspect of the present invention provides a method for preparing a tear-resistant and flame-retardant polyester fabric, the method comprising the following steps:

[0008] Step 1: Prepare an aqueous solution of N-methylpyrrolidone or benzyl alcohol with a concentration of 10-30 g / L as a treatment solution. Immerse the polyester fabric in the treatment solution and treat it at a constant temperature of 60-70°C for 10-15 minutes. Then wash it with water and keep the fabric wet.

[0009] Step 2: Using a mixed solution of anhydrous ethanol and acetone (volume ratio 7:3) as a solvent, add the reactants and photoinitiator to prepare a finishing solution with a total solids content of 15%–35%. The reactants and their mass fractions are as follows: Component A: 40–55 parts hexallylaminocyclotriphosphazene; Component B: 30–45 parts mercapto-terminated hyperbranched polysiloxane; Component C: 5–10 parts diallyl terephthalate; Component D: 5–12 parts triallyl borate. The proportions of each component are adjusted based on their functional group equivalents to control the molar ratio of mercapto functional groups to carbon-carbon double bond functional groups in the system to be 1.0:1–1.1:1. The amount of photoinitiator is 1.0%–3.0% of the total mass of the reactants.

[0010] Step 3: Immerse the wet polyester fabric treated in Step 1 into the finishing solution prepared in Step 2, and let it stand at room temperature of 20-25°C for 5-10 minutes to absorb the solution. Then, perform a two-dip and two-nip process, controlling the nip rate to be 75%-85%.

[0011] Step 4: Place the fabric impregnated in Step 3 into an ultraviolet curing device for irradiation in an air atmosphere. Use a light source with a main wavelength of 365±5nm or 395±5nm, and control the light intensity between 150 and 300mW / cm². 2 The effective irradiation time on one side is 10 to 30 seconds, which causes the reactive monomers to undergo a thiol-olefin click reaction on the fabric surface to form a cross-linked network.

[0012] Step 5: Wash the cured fabric with water to remove unreacted monomers and solvents, and then dry it to obtain the final product.

[0013] The technical effects and mechanisms of action of each step and component in the above preparation method are as follows:

[0014] In step one, the surface of the polyester fiber is micro-swelled using N-methylpyrrolidone or benzyl alcohol. This treatment increases the free volume of the polyethylene terephthalate molecular chain segments, providing space for the subsequent adsorption and intercalation of component C at the interface.

[0015] In steps two and three, component C, diallyl terephthalate, has a benzene ring structure similar to that of the polyester substrate. During static adsorption, component C preferentially adsorbs and aligns on the surface of the polyester fibers through π-π electron interactions, forming an interfacial bonding layer. Component A, hexamylaminocyclotriphosphazene, provides phosphorus and nitrogen flame-retardant elements as rigid nodes. Component B, mercapto-terminated hyperbranched polysiloxane, serves as a flexible crosslinking component, utilizing the low rotational energy barrier of silicon-oxygen bonds to impart deformation capability to the cured crosslinked network. Component D, triallyl borate, introduces boron as a char-forming aid. Controlling the molar ratio of mercapto groups to double bonds to be close to 1:1 ensures high conversion rate and crosslinking density of the reaction network.

[0016] In step four, under ultraviolet light excitation, the photoinitiator generates free radicals, initiating a thiol-olefin click reaction between the thiol group at the end of component B and the allyl double bonds on components A, C, and D. This reaction is unaffected by oxygen inhibition and rapidly forms a carbon-sulfur-carbon covalent network in air. The double bonds on component C participate in the reaction, chemically bonding the crosslinked network to component C enriched on the fiber surface, achieving a stable bond between the coating and the substrate.

[0017] A second aspect of the present invention provides a tear-resistant and flame-retardant polyester fabric, which is prepared by the preparation method described in the first aspect. The fabric comprises a polyester fiber substrate and a cross-linked coating covalently bonded to the surface of the substrate.

[0018] The crosslinked coating has a gradient structure, wherein component C-diallyl terephthalate is enriched at the interface between the polyester fiber substrate and the coating. The crosslinked coating contains a carbon-sulfur-carbon sulfide bond network generated through a thiol-ene click reaction.

[0019] The mechanism of action of this fabric during the thermal decomposition process is as follows:

[0020] When the fabric is exposed to high temperatures or flames, component A in the cross-linked coating decomposes to produce phosphoric acid derivatives, promoting polymer dehydration and carbonization; component D decomposes to generate boron oxide; and component B oxidizes to generate silicon dioxide. Boron oxide exists in a molten glassy state at high temperatures, enabling liquid-phase sintering of the phosphorus-based carbon layer with silicon dioxide particles to form a dense borosilicate ceramic carbon layer. This carbon layer structure blocks the transfer of heat and oxygen, inhibiting further decomposition of the substrate.

[0021] Meanwhile, when the fabric is subjected to external tearing, the flexible polysiloxane segments and carbon-sulfur-carbon sulfide bonds derived from component B in the cross-linked coating allow the yarn to slip relative to each other within a certain range, increasing the area of ​​the stress triangle, thereby dispersing stress and maintaining the tear resistance of the fabric.

[0022] This invention provides a method for preparing a tear-resistant and flame-retardant polyester fabric. It has the following beneficial effects:

[0023] 1. This invention solves the technical problem of weak interfacial adhesion between the flame-retardant coating and the polyester substrate by combining fabric surface activation pretreatment with component C, diallyl terephthalate. Utilizing the micro-swelling effect of the swelling agent on the fiber surface and the benzene ring structure similar to polyethylene terephthalate (PET), component C is directionally enriched at the fiber interface through π-π electron interactions. Subsequently, the cross-linked coating is chemically bonded to component C through a thiol-olefin click reaction, achieving stable anchoring of the coating on the substrate surface and improving the fabric's wash resistance.

[0024] 2. This invention utilizes mercapto-terminated hyperbranched polysiloxanes and thiol-olefin click chemistry to construct a flexible crosslinking network, solving the problem of reduced fabric tear strength caused by traditional rigid flame-retardant coatings. The carbon-sulfur-carbon sulfide bonds generated in the reaction have flexibility, and combined with the low rotational energy barrier characteristics of the hyperbranched polysiloxane segments, rigid adhesion at yarn crossover points is avoided. This allows the yarns to slip relative to each other when torn by external force, forming a stress triangle, thereby dispersing stress and maintaining the tear resistance of the fabric while imparting flame retardancy.

[0025] 3. This invention constructs a synergistic flame retardant system, overcoming the defects of loose char in single phosphorus-nitrogen systems and brittle char in single silicon systems. During high-temperature thermal degradation, the borosilicate glass phase generated by the decomposition of component D acts as a flux to perform liquid-phase sintering on the phosphorus-based char layer derived from component A and the silica particles generated by component B, thereby generating a dense and continuous borosilicate ceramic char layer in situ, effectively blocking heat transfer and oxygen diffusion, and inhibiting the generation of molten droplets in the substrate. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation process steps of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0029] The polyester fabric is made of 100% polyethylene terephthalate woven material, which has been scouring and bleached. The fabric has a plain weave, a warp and weft density of 210×190 threads / 10cm, and a weight of 120g / m². 2 .

[0030] The chemical name of hexakis(allylamino)cyclotriphosphazene is Hexakis(allylamino)cyclotriphosphazene, CAS number is 1636-14-2, and the purity is ≥98%.

[0031] The thiol-terminated hyperbranched polysiloxane is a hyperbranched organosilicon polymer with thiol functional groups at the ends. Its weight-average molecular weight (Mw) is 4000 g / mol and its thiol equivalent is 2.0 mmol / g.

[0032] Diallyl terephthalate, CAS No. 1026-92-2, purity ≥98% (GC grade).

[0033] Triallyl borate, CAS No. 1693-71-6, purity ≥97%.

[0034] The photoinitiator used is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure819), CAS number 162881-26-7, with a purity ≥99%.

[0035] Solvents and additives include: N-methylpyrrolidone (NMP), CAS No. 872-50-4, analytical grade; benzyl alcohol, CAS No. 100-51-6, analytical grade; anhydrous ethanol, CAS No. 64-17-5, purity ≥99.7%; acetone, CAS No. 67-64-1, analytical grade; and the nonionic surfactant is polyethylene glycol tert-octylphenyl ether (Triton X-100), CAS No. 9002-93-1, biochemical grade.

[0036] Example 1: This example provides a method for preparing a tear-resistant and flame-retardant polyester fabric. Please refer to the appendix. Figure 1 The specific steps are as follows:

[0037] Step 1: Fabric Surface Activation Pretreatment: Prepare a 20 g / L N-methylpyrrolidone aqueous solution as the treatment solution. Immerse the polyester fabric in the treatment solution at a liquor ratio of 1:50, heat to 65°C, and maintain the temperature for 12 minutes. After treatment, remove the fabric, wash it twice with deionized water, and remove excess water by squeezing with a roller to keep the fabric moist, controlling the liquid retention rate at 65%.

[0038] Step 2: Preparation of the finishing solution: A mixture of anhydrous ethanol and acetone (7:3 volume ratio) was used as the solvent. 7 parts (by weight, same below) of diallyl terephthalate component C were added to the solvent and magnetically stirred until dissolved. Then, 48 parts of hexamethylene aminocyclotriphosphazene component A and 8 parts of triallyl borate component D were added and stirred until completely dissolved. Finally, 38 parts of mercapto-terminated hyperbranched polysiloxane component B and 2 parts of the photoinitiator phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819) were added. The total solid content of the finishing solution was prepared to be 25%. Based on the functional group equivalent of each component, the molar ratio of mercapto functional groups to carbon-carbon double bond functional groups in this formulation system was controlled at 1.05:1. The entire preparation process was carried out under light-protected conditions, with magnetic stirring for 25 minutes, followed by ultrasonic degassing for 5 minutes.

[0039] Step 3, Padding and Directional Adsorption: The wet polyester fabric treated in Step 1 is immersed in the finishing solution prepared in Step 2 and allowed to stand for 8 minutes at room temperature (25°C) without mechanical stirring. Then, a two-dip, two-padding process is performed, with the roll pressure set at 0.3 MPa and the machine speed at 1.5 m / min, controlling the final padding rate to 80%.

[0040] Step 4: In-situ UV Click Curing: The fabric impregnated in Step 3 is placed into a UV-LED curing device for double-sided irradiation in an air atmosphere. A light source with a dominant wavelength of 365nm is selected, and the light intensity is set to 200mW / cm². 2 The effective irradiation time on one side is 20 seconds, which causes the reactive monomers to undergo a thiol-olefin click reaction on the fabric surface to form a cross-linked network.

[0041] Step 5, Post-treatment: Place the cured fabric in 55℃ warm water, add 1.5g / L of nonionic surfactant and wash for 12 minutes. After rinsing with cold water, dry in a 90℃ oven for 4 minutes to obtain the finished fabric.

[0042] Example 2: The preparation method of this example is basically the same as that of Example 1, except that the mass ratio of each reactant in the finishing solution in step two is different.

[0043] The specific formulation adjustments are as follows: 55 parts of hexamethylene aminocyclotriphosphazene component A, 30 parts of mercapto-terminated hyperbranched polysiloxane component B, 5 parts of diallyl terephthalate component C, and 12 parts of triallyl borate component D. The amount of photoinitiator and the total solid content of the finishing solution remain unchanged. The molar ratio of mercapto functional groups to carbon-carbon double bond functional groups is fine-tuned to 1.0:1 by adjusting the specific amount of component B added. The process parameters for steps one, three, four, and five are consistent with those in Example 1.

[0044] Example 3: The preparation method of this example is basically the same as that of Example 1, except that the mass ratio of each reactant in the finishing solution in step two is different.

[0045] The specific formulation adjustments are as follows: 40 parts of hexamethylene aminocyclotriphosphazene component A, 45 parts of mercapto-terminated hyperbranched polysiloxane component B, 10 parts of diallyl terephthalate component C, and 5 parts of triallyl borate component D. The amount of photoinitiator and the total solid content of the finishing solution remain unchanged, and the molar ratio of mercapto functional groups to carbon-carbon double bond functional groups is controlled at 1.1:1. The process parameters for steps one, three, four, and five are consistent with those in Example 1.

[0046] Example 4: The preparation method of this example is basically the same as that of Example 1, except for the photocuring process parameters in step four.

[0047] The specific adjustments are as follows: a UV-LED light source with a main wavelength of 395nm is selected, the light intensity is set to 300mW / cm2, and the effective irradiation time on one side is 10 seconds. The remaining formula and process steps are completely consistent with Example 1.

[0048] Example 5: This example aims to verify the applicability of different types of swelling agents and photoinitiators.

[0049] The preparation method is basically the same as in Example 1, with the only difference being:

[0050] In the fabric surface activation pretreatment in step one, an aqueous solution of benzyl alcohol of equal concentration was used instead of the N-methylpyrrolidone solution;

[0051] In the preparation of the finishing solution in step two, an equal mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide was used to replace the photoinitiator Irgacure 819, and in step four, a light source with a dominant wavelength of 395 nm was selected for curing to match the absorption spectrum of TPO. The remaining formulation components and process parameters are completely consistent with those in Example 1.

[0052] Comparative Example 1: Compared with Example 1, the difference is that component C diallyl terephthalate is not added in the preparation of the finishing solution in step two, and the amount of solvent is increased accordingly to maintain the consistency of total solid content. The specifications of other raw materials and preparation process parameters are the same as those in Example 1.

[0053] Comparative Example 2: Compared with Example 1, the difference is that in step two, pentaerythritol tetra-3-mercaptopropionate with an equal amount of mercapto equivalents was used to replace component B mercapto-terminated hyperbranched polysiloxane, while the specifications of other raw materials and preparation process parameters were the same as in Example 1.

[0054] Comparative Example 3: Compared with Example 1, the difference is that component D, triallyl borate, is not added during the preparation of the finishing solution in step two, and the amount of solvent is increased accordingly to maintain the consistency of total solid content. The specifications of other raw materials and preparation process parameters are the same as those in Example 1.

[0055] Comparative Example 4: Compared with Example 1, the difference is that the fabric surface activation pretreatment in step one is omitted, and the untreated dry polyester fabric is directly immersed in the finishing solution prepared in step two for subsequent operations. The other raw material specifications and preparation process parameters are the same as those in Example 1.

[0056] Test Example 1: This test example is used to determine the flame retardant properties, mechanical properties, washability, and hand stiffness of the polyester fabrics prepared in Examples 1-5 and Comparative Examples 1-4. The specific test methods and steps are as follows:

[0057] The test was conducted according to GB / T5455-2014, "Test for Burning Performance of Textiles - Oxygen Index Method". The fabric to be tested was cut into rectangular specimens of 150mm × 58mm and conditioned for 24 hours under standard atmospheric conditions. The specimen was vertically fixed in the specimen clamp inside the combustion chamber, and the oxygen-nitrogen mixture ratio was adjusted. The specimen was ignited from the top using an igniter, and the combustion behavior was observed. The percentage of oxygen concentration when the specimen maintained combustion for exactly 3 minutes or when the burning length was exactly 50mm was recorded; this percentage is the limiting oxygen index.

[0058] The test was conducted according to GB / T5455-2014, "Vertical Method for Testing the Burning Performance of Textiles". The fabric to be tested was cut into 300mm × 89mm samples and fixed in the sample holder of the vertical burner. A standard ignition source was applied to the lower end of the sample for 12 seconds, after which the ignition source was removed. The damaged length and charred length of the sample were measured and recorded, and it was observed whether molten drips were produced during combustion, and whether the drips ignited the absorbent cotton below.

[0059] The tear strength was determined according to GB / T3917.1-2009 "Textiles - Tear Properties of Fabrics - Part 1: Impact Pendulum Test". Samples were cut along both the warp and weft directions of the fabric, and the tear strength was measured using an Elmandorf tear strength tester. Each sample was tested five times, and the average value was taken to obtain the warp and weft tear strengths. The arithmetic mean of these two values ​​was used as the final tear strength data. The strength retention rate was obtained by calculating the ratio of the tear strength of the treated fabric to that of the untreated polyester fabric.

[0060] The procedure was performed according to AATCC 135 standard procedures. The sample was placed in a standard shrinkage washing machine, the washing temperature was set to 49°C, a standard detergent was used, and the sample was dried in a standard tumble dryer. The wash-dry cycle was repeated 30 times. After washing, the sample was conditioned under standard atmospheric conditions, and its limiting oxygen index was determined again according to the method in step 1 to characterize the wash fastness of the flame-retardant coating.

[0061] The test was conducted according to GB / T18318.1-2009, "Determination of bending properties of textiles—Part 1: Inclined plane method". The sample was cut into strips of 25mm × 200mm and placed on an inclined plane tester platform with an inclination angle of 41.5°. The sample was pushed out at a constant speed until the front end bent and touched the inclined plane, and the length extending beyond the platform was measured as the bending resistance length. Five tests were performed in both the warp and weft directions, and the average value was taken. A smaller value indicates a weaker resistance to bending, meaning a softer hand feel.

[0062] Table 1. Test data on flame retardancy and mechanical properties of polyester fabrics.

[0063]

[0064] Test data show that the synergistic effect of solvent micro-swelling pretreatment and diallyl terephthalate can significantly improve the interfacial bonding stability of the flame-retardant coating. After 30 water washing cycles, the limiting oxygen index (LOI) of Examples 1 to 5 remained above 28%, with a relatively small decrease compared to before washing. In contrast, Comparative Example 1 (without diallyl terephthalate) and Comparative Example 4 (without swelling pretreatment) showed a significant decrease in LIO after washing, down to approximately 24%. This is because the swelling agent (N-methylpyrrolidone or benzyl alcohol) acts on the surface of polyethylene terephthalate fibers, increasing the free volume of the amorphous regions and promoting the diffusion of diallyl terephthalate molecules with similar benzene ring structures to the fiber interface and the occurrence of pipi-π stacking physical adsorption.

[0065] Subsequently, through a thiol-olefin click reaction, the mercapto groups in the coating system form covalent bonds with the allyl double bonds of diallyl terephthalate, thereby constructing a chemically bonded interface resistant to water flow shear on the fiber surface.

[0066] Thiol-terminated hyperbranched polysiloxanes play a decisive role in constructing flexible crosslinking networks and maintaining the mechanical properties of fabrics. A comparison of data from Example 1 and Comparative Example 2 shows that, under similar flame-retardant properties, the system using hyperbranched polysiloxanes retains 88.3% of the tear strength and 5.2 cm of bending length; while Comparative Example 2, using linear pentaerythritol tetra-3-mercaptopropionate, shows a tear strength retention rate reduced to 45.1% and a bending length increased to 8.1 cm. This difference stems from the low rotational energy barrier of the Si-O-Si bonds in hyperbranched polysiloxanes and the large free volume of the hyperbranched topology. This structure reduces the rigidity modulus of the crosslinking network, allowing the yarns to slip relative to each other under tearing forces, thus forming a stress triangle to disperse stress. Conversely, short-chain rigid crosslinking agents restrict the relative movement between fibers, leading to stress concentration, thereby reducing tear strength and increasing fabric stiffness.

[0067] The synergistic carbonization mechanism formed by borate ester components with phosphorus and silicon is crucial for suppressing dripping and improving thermal insulation efficiency at high temperatures. Data from Example 1 and Comparative Example 3 show that the loss length of the sample increased from 86 mm to 148 mm after the absence of triallyl borate ester, accompanied by a small amount of dripping. During thermal degradation, the borosilicate glass phase generated by the decomposition of triallyl borate ester has a low softening temperature and can act as a flux to promote the liquid-phase sintering of the phosphorus-nitrogen carbon layer generated by the pyrolysis of hexallylaminocyclotriphosphazene and the silica particles generated by the decomposition of hyperbranched polysiloxane. This process forms a dense, continuous, and thermally stable borosilicate ceramic carbon layer in situ. This carbon layer effectively blocks the transfer of oxygen and heat to the interior of the substrate and seals the surface of the polymer melt to prevent dripping.

[0068] Test Example 2: This test example is used to determine the heat release behavior and char formation properties of the polyester fabrics prepared in Examples 1-5 and Comparative Examples 1-4 under forced combustion conditions. The specific test methods and steps are as follows:

[0069] The determination was conducted according to ISO 5660-1 "Tests for reaction to fire—Heat release, smoke production and mass loss rate—Part 1: Heat release rate (cone calorimeter method)". A cone calorimeter was used as the testing equipment, which mainly consists of a conical radiant heater, a weighing sensor, a spark igniter, and a flue gas analysis system.

[0070] The testing steps are as follows:

[0071] Sample preparation: Cut the fabric to be tested into 100mm × 100mm square samples. To prevent molten drips from damaging the equipment and to ensure unidirectional heating, wrap the bottom and sides of the sample with aluminum foil, then place it horizontally on the heat insulation pad inside the stainless steel sample holder, and press down the metal mesh to fix the sample surface.

[0072] Parameter settings: Adjust the height of the conical radiant heater and set the radiant heat flux to 35 kW / m². 2 Start the smoke extraction system and calibrate the oxygen analyzer and laser smoke measurement system.

[0073] Data Acquisition: Push the sample holder containing the sample into the center of the weighing sensor platform below the heater, and simultaneously start the spark igniter and data acquisition system. The system records the heat release rate, total heat release, and sample mass change every second.

[0074] Test termination: Data acquisition stops when the sample is completely extinguished and its mass no longer changes, or when the test time reaches the preset 1200 seconds. Record the peak heat release rate, total heat release, and char residue after combustion.

[0075] Table 2 Summary of cone calorimetry test data.

[0076]

[0077]

[0078] Test data show that the multi-component flame-retardant system constructed in this invention significantly reduces the heat release intensity of the polyester substrate. Compared with the original polyester, the peak heat release rate of Example 1 is reduced from 645.3 kW / m². 2 Reduced to 185.4 kW / m 2 The total heat release is 12.8 MJ / m 2 Reduced to 4.9 MJ / m 2This result is mainly attributed to the pyrolysis products of hexaallylaminocyclotriphosphazene. Under high-temperature radiation, the phosphazene ring decomposes to produce phosphate segregates and non-combustible gases. The former promotes polymer dehydration and char formation in the condensed phase, while the latter dilutes the oxygen concentration in the gas phase and captures active free radicals in the combustion chain reaction, thereby inhibiting the rapid increase in flame intensity.

[0079] The synergistic effect of boron and silicon plays a crucial role in improving the high-temperature char residue and char layer stability. Comparing Example 1 and Comparative Example 3, data without the addition of triallyl borate show that the absence of the borate component leads to an increase in the peak heat release rate to 289.4 kW / m³. 2 Furthermore, the residual char rate was only 14.2%, far lower than the 24.6% in Example 1. Under continuous thermal radiation, the boron oxide melt generated by the decomposition of triallyl boronate has fluxing properties, reducing the sintering temperature of silicon oxide and phosphorus-based carbon layers and promoting the liquid-phase sintering process. This process fills the pores inside the carbon layer, transforming the loose carbon slag into a dense borosilicate ceramic structure, thereby improving the carbon layer's barrier efficiency against heat flow and volatile degradation products.

[0080] Furthermore, the molecular structure of the organosilicon components has a specific influence on the heat release behavior. Although the linear mercapto compound in Comparative Example 2 and Example 1 show little difference in peak heat release rate, indicating that their chemical contributions to reducing the heat release rate are comparable, the mechanical data from Test Example 1 shows that the hyperbranched polysiloxane used in Example 1 avoids the brittleness problem of traditional inorganic ceramic layers while ensuring high flame retardant efficiency. The inorganic framework generated in situ on the combustion surface by the nanoscale silica precursor in the hyperbranched structure cross-links with the glassy melt formed by phosphorus and boron elements, constructing a multidimensional barrier network with both physical strength and thermal stability, thus macroscopically exhibiting low heat release and high char residue.

[0081] Test Example 3: This test example is used to determine the thermogravimetric behavior and high-temperature thermal oxidation stability of the polyester fabrics prepared in Examples 1-5 and Comparative Examples 1-4. The specific test methods and steps are as follows:

[0082] The thermogravimetric analysis (TGA) method was used according to GB / T2951.32-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 32: Test Methods for Polyvinyl Chloride Blends - Weight Loss Test - Thermal Stability Test". A thermogravimetric analyzer was used as the testing equipment, and the test atmosphere was set to air with a gas flow rate controlled at 50 mL / min to simulate the thermal oxidation degradation process of the material in a real fire.

[0083] The testing steps are as follows: Sample preparation: The fabric to be tested is cut into tiny fragments with a diameter of less than 2 mm and dried to constant weight under standard conditions.

[0084] Weighing and loading: Take 5 mg to 10 mg of sample and place it in an alumina crucible. Accurately weigh the initial mass of the sample.

[0085] Program heating: Start the heating program, set the temperature range to room temperature to 700℃, and set the heating rate to 20℃ / min.

[0086] Data recording: The instrument automatically and continuously records the curve of sample mass change with temperature and time.

[0087] Parameter extraction: The initial decomposition temperature, i.e. the temperature at which the mass loss is 5%, is extracted from the thermogravimetric curve and the derivative thermogravimetric curve, denoted as T5%, the maximum thermogravimetric rate temperature, i.e. the temperature at which the degradation rate is the fastest, is denoted as Tmax, and the char residue at 700℃.

[0088] Table 3. Fabric thermogravimetric analysis test data

[0089]

[0090] Thermogravimetric analysis (TGA) data revealed the regulatory mechanism of the flame-retardant coating on the thermal degradation process of the polyester substrate. Compared with the original polyester, the initial decomposition temperature (T5%) of Examples 1 to 5 was advanced by approximately 50°C to 60°C, mainly distributed between 338°C and 346°C. This phenomenon confirms that hexaallylaminocyclotriphosphazene and phosphorus-containing components played a catalytic role in char formation in the early stage of heating, changing the original random breakage mode of polyester segments by promoting the dehydration and cyclization reaction of the polymer matrix. Although this led to mass loss in the low-temperature stage, this prior chemical evolution provided the material basis for the construction of a stable char layer skeleton in the subsequent high-temperature stage, thereby delaying the maximum thermal weight loss rate temperature (Tmax) and increasing the peak temperature of main chain degradation of the substrate from 435.2°C to over 450°C.

[0091] The char stabilizing effect of triallyl borate ester under high-temperature oxidation conditions was verified by char residue data. Comparing the data of Example 1 and Comparative Example 3, the char residue at 700°C decreased significantly from 28.4% to 15.6% in the absence of the borate ester component. In high-temperature regions exceeding 500°C, a single phosphorus-nitrogen char layer is prone to thermal oxidative decomposition, leading to mass loss. Boron oxide produced by the decomposition of triallyl borate ester can form a glassy liquid film on the char layer surface. This liquid film seals the micropores on the char layer surface, effectively blocking the contact between external oxygen and the internal carbon skeleton, inhibiting further oxidation and ablation of the char layer, thereby significantly improving the final char residue retention.

[0092] The contribution of the inorganic silicon framework introduced into the thiol-terminated hyperbranched polysiloxane to its thermal stability is evident in the comparison with Comparative Example 2. The char residue of Example 1 is significantly higher than that of Comparative Example 2, which uses an organic polythiol compound, and its Tmax is also higher. This is mainly attributed to the fact that the bond energy of the Si-O bond (460 kJ / mol) is higher than that of the C-C bond (347 kJ / mol) and the CO bond (358 kJ / mol), making the hyperbranched polysiloxane less prone to main chain breakage at high temperatures. During thermal degradation, the organosilicon component is converted in situ into silica microparticles. These microparticles act as physical crosslinking points embedded in the phosphorus-nitrogen-carbon layer, enhancing the structural integrity of the residue and reducing the release of volatile products.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of a tear resistant flame retardant polyester fabric, characterized by, The method comprises the following steps: Step one, preparing a water solution of N-methyl pyrrolidone or benzyl alcohol with a concentration of 10-30 g / L as a treatment solution, and immersing the polyester fabric in the treatment solution, and treating the fabric at a constant temperature of 60-70℃ for 10-15 minutes, and then washing and keeping the fabric wet; Step two, preparing a finishing solution with a total solid content of 15%-35% by using a mixed solution of anhydrous ethanol and acetone with a volume ratio of 7:3 as a solvent, and adding reaction monomers and a photoinitiator; the reaction monomers and their mass fractions are as follows: component A: hexaallylaminocyclotriphosphazene 40-55 parts; component B: thiol-terminated hyperbranched polysiloxane 30-45 parts; component C: diallyl terephthalate 5-10 parts; component D: triallyl borate 5-12 parts; wherein, the proportions of the components are adjusted based on the functional group equivalent weight of each component, and the molar ratio of thiol functional groups to carbon-carbon double bond functional groups in the system is controlled to be 1.0:1-1.1:1; the amount of the photoinitiator is 1.0%-3.0% of the total mass of the reaction monomers; Step three, immersing the wet polyester fabric treated in step one in the finishing solution prepared in step two, and standing for 5-10 minutes for adsorption at room temperature of 20-25℃, and performing a two-dip-two-roll process, and controlling the roll-up rate to be 75%-85%; Step four, the fabric after padding in step three is sent into ultraviolet light curing equipment, and irradiation is carried out in an air atmosphere, a light source with a main wavelength of 365±5nm or 395±5nm is selected, the light intensity is controlled to be 150-300mW / cm 2 , and the effective irradiation time of a single side is 10-30 seconds; Step five, washing the cured fabric to remove unreacted monomers and solvents, and drying to obtain the fabric.

2. The preparation method of the tear-resistant flame-retardant polyester fabric according to claim 1, characterized in that: The thiol-terminated hyperbranched polysiloxane in step two has a thiol equivalent weight of 1.5-2.5 mmol / g, and a weight average molecular weight Mw of 3000-5000 g / mol.

3. The method for preparing the tear-resistant flame-retardant polyester fabric according to claim 1, characterized in that: The photoinitiator in step two is selected from one or a mixture of both of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide or 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide.

4. The method for preparing the tear-resistant flame-retardant polyester fabric according to claim 1, characterized in that: The preparation process of the finishing solution in step two is as follows: first, component C is dissolved in the mixed solvent, and after uniform stirring, component A and component D are added in sequence, and after complete dissolution, component B and the photoinitiator are added, and the whole process is carried out in the dark, and magnetic stirring is performed for 20-30 minutes.

5. The method for preparing a tear-resistant and flame-retardant polyester fabric according to claim 1, characterized in that: In step three, the standing and adsorption process is carried out without mechanical stirring.

6. The method for preparing a tear-resistant and flame-retardant polyester fabric according to claim 1, characterized in that: In step three, the roll pressure of the two-dip-two-roll process is controlled to be 0.2-0.4 MPa, and the line speed is controlled to be 1-2 m / min.

7. The method for preparing a tear-resistant and flame-retardant polyester fabric according to claim 1, characterized in that: The post-treatment in step five is as follows: placing the cured fabric in warm water at 50-60℃, adding 1-2 g / L of a non-ionic surfactant, and washing for 10-15 minutes, and then cold water rinsing, and drying at 80-100℃ for 3-5 minutes.

8. A tear resistant flame resistant polyester fabric prepared by the method of any one of claims 1-7. The fabric comprises a polyester fiber base material and a crosslinked coating layer covalently bonded to the surface of the base material.

9. The tear resistant flame resistant polyester fabric of claim 8, wherein: The crosslinked coating layer has a gradient structure, wherein component C, diallyl terephthalate, is enriched at the interface between the polyester fiber base material and the coating layer.

10. The tear resistant flame resistant polyester fabric of claim 8, wherein: The crosslinked coating layer contains a carbon-sulfur-carbon sulfide network generated by thiol-ene click reaction.

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