A polyester / cotton blended fabric flame-retarded by an intumescent flame retardant and its preparation method

Abstract

The present invention relates to a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant and a preparation method thereof. The surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame-retardant film, and the network flame-retardant film is bridged with the polyester / cotton blended fabric through a covalent bond; the network flame-retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through the action of a crosslinking agent; the structural formula of the intumescent flame retardant is The preparation method is as follows: dissolve the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide in a mixed solution of water and acetone, adjust the pH value of the solution to 6-7 with ammonia water to obtain a flame-retardant finishing solution, immerse the polyester / cotton blended fabric in the flame-retardant finishing solution, and treat the polyester / cotton blended fabric by the method of padding-baking to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant. The polyester / cotton blended fabric flame-retarded by the intumescent flame retardant of the present invention has excellent flame-retardant effect and good flame-retardant durability.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardant modification of polyester / cotton blended fabrics, and relates to a polyester / cotton blended fabric flame retarded by an intumescent flame retardant and a preparation method thereof. Background Art

[0002] With the development of society, people's living standards have been continuously improved, and the awareness of safety protection has gradually increased. The social demand for textile materials with flame retardant protection functions has been expanding day by day. Polyester / cotton blended fabrics have the characteristics of being crisp, smooth, quick-drying, and durable, and are widely used in civil and industrial fields such as indoor and vehicle interiors, and protective clothing. However, polyester / cotton blended fabrics have a special "wick effect" during the combustion process, and their flame retardant properties are different from those of polyester and cotton fabrics, resulting in poor flame retardant properties of polyester / cotton blended fabrics and difficulty in meeting the requirements of strict textile flame retardant standards. Therefore, flame retardant modification of polyester / cotton blended fabrics helps to improve their safety protection performance and expand their application fields.

[0003] Intumescent flame retardants are flame retardant systems mainly based on phosphorus and nitrogen, and have the characteristics of low smoke, non-toxic, high efficiency, and anti-melting dripping compared with traditional halogen flame retardants, becoming an important development direction in the science of flame retardant materials. Chinese invention patent CN106436285A discloses the preparation and application of an intumescent flame retardant system doped with silica sol. An intumescent flame retardant system is formed by mixing three components of an acid source, a carbon source, and a gas source, and then doped with silica sol to improve the flame retardant properties of polyester, cotton, or polyester / cotton blended fabrics. However, this intumescent flame retardant system has a complex composition, and the intumescent flame retardant coating cannot form a strong chemical bond with the polyester / cotton blended fabric, resulting in poor durability of the flame retarded polyester / cotton blended fabric.

[0004] Chinese invention patent CN104846639A discloses a method for flame retardant finishing of cotton fabrics with a reactive intumescent flame retardant. During the curing process, the chloro-s-triazine active group crosslinks with the hydroxyl group of cotton fibers. However, the flame retardant has poor water solubility, and a mixed system of ethanol and water is used as a solvent. The reactive intumescent flame retardant is more likely to chemically react with the hydroxyl group of ethanol, thus losing its activity, resulting in poor durability of the finished cotton fabric.

[0005] The literature ("Flame Retardant Finishing of Polyester / Cotton Blended Fabrics with Phosphorus / Nitrogen Flame Retardants" [J]. Journal of Textile Research, 2022, 43(6): 94-99, 106) uses phytic acid and urea to synthesize ammonium phytate, and conducts formaldehyde-free flame retardant finishing on polyester / cotton blended fabrics through a pad-dry-cure process. Ammonium phytate can form a covalent bond crosslink with cotton fibers under the catalysis of dicyandiamide. However, during the high-temperature curing process, the ammonium phosphate group is prone to decomposition to generate phosphate and ammonia, resulting in the inability to construct a phosphorus / nitrogen synergistic flame retardant effect, a decrease in the flame retardant efficiency of the flame retardant, and poor water wash resistance of the finished polyester / cotton blended fabric. After washing, the flame retardant effect is lost.

[0006] Therefore, it is necessary to develop an intumescent flame retardant that combines acid source, carbon source and gas source, and graft the intumescent flame retardant onto the polyester / cotton blended fabric through covalent bonds, so as to provide an efficient and durable flame retardant function. Summary of the Invention

[0007] The object of the present invention is to solve the above problems existing in the prior art, and provide a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant and a preparation method thereof. The present invention synthesizes an intumescent flame retardant, which simultaneously contains an acid source, a gas source and a carbon source. The combination of the three can effectively construct an intumescent flame retardant, solve the problem of nitrogen element loss during high-temperature baking, and has high flame retardant performance; the intumescent flame retardant forms a flame retardant network structure on the surface of the polyester / cotton blended fabric under the action of a cross-linking agent tris(epoxypropyl)isocyanurate, and is cross-linked and deposited on the surface of the polyester / cotton blended fabric through a variety of covalent bonds, so as to achieve a durable flame retardant effect.

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

[0009] A polyester / cotton blended fabric flame-retarded by an intumescent flame retardant, the surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film, and the network flame retardant film is bridged with the polyester / cotton blended fabric through covalent bonds, generating a stable bond with the polyester / cotton blended fabric, thereby endowing the polyester / cotton blended fabric with an efficient and durable flame retardant function;

[0010] The network flame retardant film is formed by connecting an intumescent flame retardant to the surface of the polyester / cotton blended fabric through a cross-linking agent tris(epoxypropyl)isocyanurate;

[0011] The structural formula of the intumescent flame retardant is

[0012] As a preferred technical scheme:

[0013] For the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant as described above, the flame retardant performance of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant is: the limiting oxygen index (LOI) is 29.8% - 33.5%, the damage length is 11.9 - 8.3 cm, no molten droplets are generated, and the maximum heat release rate is 121.3 - 139.2 W / g (the LOI of the unmodified polyester / cotton blended fabric is 17.3%, the damage length is 30 cm, and the maximum heat release rate is 213.5 W / g); after 30 washes, the damage length is not higher than 14.6 cm, indicating that the modified polyester / cotton blended fabric has an efficient and durable flame retardant function.

[0014] The present invention also provides a method for preparing a polyester / cotton blended fabric flame-retarded by the intumescent flame retardant as described above. The polyester / cotton blended fabric is immersed in a flame-retardant finishing solution, and the polyester / cotton blended fabric is treated by the method of padding-drying-baking to obtain a polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0015] The flame-retardant finishing solution is obtained by dissolving an intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide in a mixed solution of water and acetone, and adjusting the pH value of the solution to 6-7 with ammonia water. Under this pH condition, the phosphate groups are converted into ammonium phosphate groups, which helps to form covalent bond cross-linking with cotton fibers.

[0016] As a preferred technical solution:

[0017] In the method for preparing a polyester / cotton blended fabric flame-retarded by the intumescent flame retardant as described above, the concentration of the intumescent flame retardant in the flame-retardant finishing solution is 100-200 g / L. Increasing the amount of the flame retardant helps to improve the flame retardancy of the polyester / cotton blended fabric, but the content of the flame retardant on the polyester / cotton blended fabric will reach saturation, and excessive amount will cause waste.

[0018] In the method for preparing a polyester / cotton blended fabric flame-retarded by the intumescent flame retardant as described above, tris(epoxypropyl)isocyanurate acts as a network cross-linking agent. The three epoxy groups of tris(epoxypropyl)isocyanurate can undergo cross-linking reactions with the phosphate groups and hydroxyl groups of the intumescent flame retardant, so that the intumescent flame retardants are interconnected on the surface of the polyester / cotton blended fabric to form a network structure; tris(epoxypropyl)isocyanurate can also react with the hydroxyl groups on the fabric surface. As a cross-linking agent between the flame retardant and the polyester / cotton blended fabric, the flame retardant network coating is grafted onto the surface of the polyester / cotton blended fabric through covalent bonds, thereby providing an efficient and durable flame retardant function. The molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant is 2-3:1. Increasing the amount of tris(epoxypropyl)isocyanurate helps to form the network structure and the grafting of the flame retardant on the fabric, but excessive amount will cause waste; acetone is the solvent of tris(epoxypropyl)isocyanurate, and acetone accounts for 20%-30% of the total volume of water and acetone; sodium thiosulfate is used as a catalyst to promote the reaction of the epoxy groups of tris(epoxypropyl)isocyanurate with the hydroxyl groups of cotton fibers and the intumescent flame retardant, and the mass of sodium thiosulfate is 3-5% of that of tris(epoxypropyl)isocyanurate; the ammonium phosphate groups of the intumescent flame retardant can undergo esterification cross-linking reactions with the hydroxyl groups of cotton fibers under the catalysis of dicyandiamide, and the mass of dicyandiamide is 5-7% of that of the intumescent flame retardant.

[0019] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant as described above. The process parameters of padding-drying-baking are as follows: the liquor pick-up rate is 100-110%; the pre-drying temperature is 70-80 °C, and the pre-drying time is 2-4 min; the baking temperature is 160-170 °C, and the baking time is 5-8 min. The higher the liquor pick-up rate, the higher the liquid content of the polyester / cotton blended fabric, which helps to improve the flame retardancy. However, when the flame retardant content on the fabric is too high, it will reach saturation, resulting in waste. The increase in the baking temperature helps to promote the reaction of tris(epoxypropyl)isocyanurate with the intumescent flame retardant and the polyester / cotton blended fabric. However, if it is too high, it will cause waste and easily damage the physical properties of the fabric.

[0020] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant as described above. The polyester / cotton blended fabric is a 35 / 65, 40 / 60 or 45 / 55 polyester / cotton blended fabric.

[0021] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant as described above. The preparation method of the intumescent flame retardant is as follows: tris(epoxypropyl)isocyanurate is heated to 140-150 °C and then pentaerythritol is added for reaction for 3-4 h (140-150 °C is higher than the melting point of tris(epoxypropyl)isocyanurate. Under this temperature condition, tris(epoxypropyl)isocyanurate is in a liquid state, which helps the reaction to proceed; the reaction time is 3-4 h. The increase in the reaction temperature and the extension of the time help the synthesis reaction to proceed, but if it is too high, it will cause waste), and then phosphoric acid is added and the reaction continues at 105-115 °C for 3-4 h (the increase in the reaction temperature and the extension of the time help the synthesis reaction to proceed, but if it is too high, it will cause waste). After drying and purification, the intumescent flame retardant is obtained.

[0022] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant as described above. The molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol is 2-2.2:1. The epoxy groups of two moles of tris(epoxypropyl)isocyanurate and two hydroxyl groups of pentaerythritol undergo epoxy ring-opening addition reaction; the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate is 2-2.3:1. The remaining two epoxy groups of tris(epoxypropyl)isocyanurate and phosphate radicals can undergo epoxy ring-opening addition reaction. A slightly excessive amount of phosphoric acid helps to improve the reaction efficiency, but if it is too high, it will cause waste.

[0023] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant as described above. After the reaction, the product is first dried under vacuum to remove moisture, and then purified with methanol and toluene. The yield of the intumescent flame retardant is 75-79%.

[0024] The principle of the present invention is as follows:

[0025] The present invention synthesizes an intumescent flame retardant which contains an acid source, a gas source and a carbon source at the same time. The combination of the three can effectively construct the intumescent flame retardant, solve the problem of nitrogen element loss during high-temperature baking, and has high flame retardancy. Tris(epoxypropyl)isocyanurate contains three epoxy groups and can be used as a network crosslinking agent. During the baking process, it undergoes a crosslinking reaction with the phosphate group and hydroxyl group of the intumescent flame retardant, causing the intumescent flame retardants to be interconnected on the surface of the polyester / cotton blended fabric to form a network film structure. Tris(epoxypropyl)isocyanurate can also react with the hydroxyl group of cotton fibers and serve as a crosslinking agent between the flame retardant and the polyester / cotton blended fabric, grafting the flame retardant network structure onto the surface of the polyester / cotton blended fabric through covalent bonds. In addition, the ammonium phosphate group of the intumescent flame retardant undergoes an esterification reaction with the hydroxyl group of cotton fibers under the action of dicyandiamide catalyst and high temperature. Therefore, the present invention provides an efficient and durable flame retardant function by constructing a network structure on the fabric surface and fixing it on the surface of the polyester / cotton blended fabric through various crosslinking methods.

[0026] Advantages:

[0027] (1) The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant of the present invention. The phosphorus-containing flame retardant group, nitrogen-containing heterocycle and polyol group are combined by covalent bonds to synthesize a flame retardant integrating three groups, and nitrogen element loss will not be caused by baking. The phosphate group in the intumescent flame retardant acts as an acid source, the nitrogen-containing heterocycle acts as a gas source, and the polyol acts as a carbon source. The combination of the three can effectively construct the intumescent flame retardant. During the combustion process, the intumescent flame retardant helps to form an intumescent char on the surface of the polyester / cotton blended fabric, playing the role of isolating heat, oxygen and combustible gases, and having excellent flame retardancy.

[0028] (2) The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant of the present invention provides an efficient and durable flame retardant function by constructing a network structure on the fabric surface and fixing it on the surface of the polyester / cotton blended fabric through various crosslinking methods.

[0029] (3) A polyester / cotton blended fabric flame-retarded by an intumescent flame retardant of the present invention has excellent flame retardant effect and good flame retardant durability. Description of the Drawings

[0030] Figure 1 For the 13 C nuclear magnetic resonance spectrum of the intumescent flame retardant in Example 1;

[0031] Figure 2 It is a schematic diagram of the crosslinking mechanism of the intumescent flame retardant on the polyester / cotton blended fabric, where IFR represents the intumescent flame retardant and Fabric represents the polyester / cotton blended fabric. Detailed Embodiments

[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not 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 also fall within the scope defined by the appended claims of this application.

[0033] The present invention washes the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant with reference to AATCC 61-2006 "Accelerated Test for Colorfastness to Laundering of Home and Commercial Textiles".

[0034] The test method adopted by the present invention is as follows:

[0035] (1) Limiting oxygen index: Determined in accordance with the standard of GB / T 5454-1997 "Textiles - Burning Performance - Oxygen Index Method".

[0036] (2) Damaged length: Determined in accordance with the standard of GB / T 5455-2014 "Textiles - Burning Performance - Determination of Damaged Length, Afterflame and Afterglow Time in the Vertical Direction".

[0037] (3) Maximum heat release rate: Tested with reference to ASTM D7309-21a.

[0038] Example 1

[0039] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0040] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol of 2:1, tris(epoxypropyl)isocyanurate is heated to 140 °C and then pentaerythritol is added for reaction for 4 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate of 2:1, phosphoric acid is added and the reaction is continued at 110 °C for 3 h. After the reaction, the product is first dried under vacuum to remove water, and then purified with methanol and toluene to obtain the intumescent flame retardant. The yield of the intumescent flame retardant is 75%, and its structural formula is

[0041]

[0042] (2) According to the ratio of the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant of 2.3:1, the mass of sodium thiosulfate is 3% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide is 6% of the intumescent flame retardant. The intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide obtained in step (1) are dissolved in a mixed solution of water and acetone (acetone accounts for 25% of the total volume of water and acetone), and the pH value of the solution is adjusted to 6 with ammonia water to obtain a flame retardant finishing solution. The concentration of the intumescent flame retardant in the flame retardant finishing solution is 100 g / L;

[0043] (3) Immerse the 35 / 65 polyester / cotton blended fabric into the flame retardant finishing solution obtained in step (2) (the crosslinking mechanism is as Figure 2 shown), and treat the polyester / cotton blended fabric by the method of padding-drying-baking. Control the liquor ratio to be 100%, the pre-drying temperature to be 80 °C, the pre-drying time to be 2 min, the baking temperature to be 170 °C, and the baking time to be 5 min to obtain a polyester / cotton blended fabric flame retarded by the intumescent flame retardant.

[0044] The surface of the obtained polyester / cotton blended fabric flame retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged by covalent bonds;

[0045] The flame retardant properties of the polyester / cotton blended fabric flame retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 29.8%, the char length is 11.9 cm, there is no melt dripping, and the maximum heat release rate is 139.2 W / g; the char length after 30 washes is 14.6 cm.

[0046] The 13 13C nuclear magnetic resonance spectrum of the intumescent flame retardant is as Figure 1 shown. It can be seen from Figure 1 that the chemical shift at 150.6 ppm is caused by the carbon atom of the C=O structure on the nitrogen heterocycle, the chemical shifts at 59.2 and 46.2 ppm are caused by the carbon atoms of the C-OH structure and the central carbon atom of pentaerythritol, and the chemical shifts at 45.7 and 45.2 ppm are caused by the carbon atoms of the C-N structure connected to the epoxy group; the chemical shifts at 67.0 ppm and 63.9 ppm are caused by the carbon atoms of the C-O-P and C-OH structures generated after the reaction of the epoxy group in the structure of the intumescent flame retardant, indicating that the epoxy group reacts with the phosphate group. The chemical shifts at 74.8 and 69.7 ppm are caused by the carbon atom after the ring opening of the epoxy group in the C-O structure and the pentaerythritol carbon atom after the reaction of the epoxy group with the hydroxyl group of pentaerythritol, respectively. The above results indicate that the intumescent flame retardant is successfully synthesized.

[0047] Comparative Example 1

[0048] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is basically the same as that of the example. The difference lies in that the flame retardant solution in step (2) is obtained by dissolving the intumescent flame retardant, sodium thiosulfate, and dicyandiamide obtained in step (1) in a mixed solution of water and acetone (acetone accounts for 25% of the total volume of water and acetone), and adjusting the pH value of the solution to 6 with ammonia water. The dosage ratio relationship among the intumescent flame retardant, sodium thiosulfate, and dicyandiamide, the ratio relationship between water and acetone, and the concentration of the flame retardant solution are the same as those in Example 1. The flame retardant properties of the finally prepared polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 29.3%, the char length is 12.1 cm, no melting drops are generated, and the maximum heat release rate is 142.3 W / g; the char length after 5 washes is 30 cm.

[0049] Comparing Example 1 with Comparative Example 1, it can be seen that the flame retardant properties of the flame-retarded polyester / cotton blended fabric prepared in Comparative Example 1 are slightly lower than those of the flame-retarded polyester / cotton blended fabric prepared in Example 1, and the water wash resistance of the flame-retarded polyester / cotton blended fabric prepared in Comparative Example 1 is significantly worse. This is because in Comparative Example 1, the intumescent flame retardant is only simply deposited on the polyester / cotton blended fabric, unable to form a covalent bond with the fabric, nor can it combine with each other on the surface of the polyester / cotton blended fabric to form a network flame retardant film. During the water wash process, the intumescent flame retardant is easily washed off, thus losing the flame retardant effect.

[0050] Example 2

[0051] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0052] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol of 2.1:1, tris(epoxypropyl)isocyanurate is heated to 145 °C and then pentaerythritol is added for reaction for 3 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate of 2.1:1, phosphoric acid is added and the reaction continues at 115 °C for 3 h. After the reaction ends, the product is first dried under vacuum to remove moisture, and then purified with methanol and toluene to obtain an intumescent flame retardant. The yield of the intumescent flame retardant is 76%, and its structural formula is

[0053] (2) According to the ratio of the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant of 3:1, the mass of sodium thiosulfate is 3.5% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide is 7% of the intumescent flame retardant, the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate, and dicyandiamide obtained in step (1) are dissolved in a mixed solution of water and acetone (acetone accounts for 30% of the total volume of water and acetone), and the pH value of the solution is adjusted to 6.2 with ammonia water to obtain a flame retardant finishing solution. The concentration of the intumescent flame retardant in the flame retardant finishing solution is 200 g / L;

[0054] (3) Immerse the 40 / 60 polyester / cotton blended fabric into the flame retardant finishing liquid obtained in step (2), and treat the polyester / cotton blended fabric by the method of padding-baking-curing. Control the liquor pickup rate at 110%, the pre-baking temperature at 78 °C, the pre-baking time at 3 min, the curing temperature at 160 °C, and the curing time at 8 min to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0055] The surface of the obtained polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged by covalent bonds;

[0056] The flame retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 33.5%, the char length is 8.3 cm, no melt dripping occurs, and the maximum heat release rate is 121.3 W / g; the char length after 30 washes is 12.5 cm.

[0057] Example 3

[0058] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0059] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol of 2.1:1, heat tris(epoxypropyl)isocyanurate to 150 °C and then add pentaerythritol and react for 3.5 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate of 2.2:1, add phosphoric acid and continue to react at 105 °C for 4 h. After the reaction ends, the product is first dried under vacuum to remove moisture, and then purified by methanol and toluene to obtain the intumescent flame retardant. The yield of the intumescent flame retardant is 76%, and its structural formula is

[0060] (2) According to the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant of 2:1, the mass of sodium thiosulfate is 4% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide is 5% of the intumescent flame retardant, dissolve the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide obtained in step (1) in a mixed solution of water and acetone (acetone accounts for 20% of the total volume of water and acetone), and adjust the pH value of the solution to 6.5 with ammonia water to obtain the flame retardant finishing liquid. The concentration of the intumescent flame retardant in the flame retardant finishing liquid is 120 g / L;

[0061] (3) Immerse the 45 / 55 polyester / cotton blended fabric into the flame retardant finishing liquor obtained in step (2), and treat the polyester / cotton blended fabric by the method of padding-drying-baking. Control the liquor pickup rate at 105%, the pre-drying temperature at 76 °C, the pre-drying time at 4 min, the baking temperature at 165 °C, and the baking time at 6 min to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0062] The surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged by covalent bonds;

[0063] The flame retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 30.5%, the char length is 11.1 cm, there is no melt dripping, and the maximum heat release rate is 133 W / g; the char length after 30 washes is 14 cm.

[0064] Example 4

[0065] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0066] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol of 2.2:1, heat tris(epoxypropyl)isocyanurate to 145 °C and then add pentaerythritol and react for 3.5 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate of 2.2:1, add phosphoric acid and continue to react at 108 °C for 4 h. After the reaction is completed, the product is first dried under vacuum to remove moisture, and then purified with methanol and toluene to obtain the intumescent flame retardant. The yield of the intumescent flame retardant is 76%, and its structural formula is

[0067] (2) According to the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant of 2.8:1, the mass of sodium thiosulfate is 4.5% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide is 5.5% of the intumescent flame retardant, dissolve the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide obtained in step (1) in a mixed solution of water and acetone (acetone accounts for 22% of the total volume of water and acetone), and adjust the pH value of the solution to 6.8 with ammonia water to obtain the flame retardant finishing liquor. The concentration of the intumescent flame retardant in the flame retardant finishing liquor is 180 g / L;

[0068] (3) Immerse the 35 / 65 polyester / cotton blended fabric into the flame retardant finishing liquor obtained in step (2), and treat the polyester / cotton blended fabric by the method of padding-drying-baking. Control the liquor pickup rate to be 105%, the pre-drying temperature to be 75 °C, the pre-drying time to be 4 min, the baking temperature to be 168 °C, and the baking time to be 7 min to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0069] The surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged by covalent bonds;

[0070] The flame retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 32.8%, the char length is 8.9 cm, no melt dripping occurs, and the maximum heat release rate is 124.1 W / g; the char length after 30 washes is 12.8 cm.

[0071] Example 5

[0072] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0073] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol being 2.2:1, heat tris(epoxypropyl)isocyanurate to 145 °C and then add pentaerythritol and react for 4 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate being 2.3:1, add phosphoric acid and continue to react at 110 °C for 3.5 h. After the reaction ends, first remove the moisture from the product by vacuum drying, and then purify it with methanol and toluene to obtain the intumescent flame retardant. The yield of the intumescent flame retardant is 79%, and its structural formula is

[0074] (2) According to the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant being 2.6:1, the mass of sodium thiosulfate being 4.8% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide being 6% of the intumescent flame retardant, dissolve the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate, and dicyandiamide obtained in step (1) in a mixed solution of water and acetone (acetone accounts for 25% of the total volume of water and acetone), and adjust the pH value of the solution to 6.6 with ammonia water to obtain the flame retardant finishing liquor. The concentration of the intumescent flame retardant in the flame retardant finishing liquor is 150 g / L;

[0075] (3) Immerse the 40 / 60 polyester / cotton blended fabric into the flame retardant finishing liquid obtained in step (2), and treat the polyester / cotton blended fabric by the method of padding-drying-baking. Control the liquor pickup rate to be 108%, the pre-drying temperature to be 72 °C, the pre-drying time to be 2 min, the baking temperature to be 165 °C, and the baking time to be 6 min to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0076] The surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged through covalent bonds;

[0077] The flame retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 31.4%, the char length is 10.5 cm, no melt dripping occurs, and the maximum heat release rate is 128.3 W / g; the char length after 30 washes is 13.2 cm.

[0078] Example 6

[0079] A preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant is as follows:

[0080] (1) According to the molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol being 2.2:1, heat tris(epoxypropyl)isocyanurate to 145 °C and then add pentaerythritol and react for 3 h. Then, according to the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate being 2.3:1, add phosphoric acid and continue to react at 112 °C for 3.5 h. After the reaction ends, the product is first dried under vacuum to remove moisture, and then purified with methanol and toluene to obtain the intumescent flame retardant. The yield of the intumescent flame retardant is 78%, and its structural formula is

[0081] (2) According to the molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant being 2.5:1, the mass of sodium thiosulfate being 5% of tris(epoxypropyl)isocyanurate, and the mass of dicyandiamide being 6.5% of the intumescent flame retardant, dissolve the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate, and dicyandiamide obtained in step (1) in a mixed solution of water and acetone (acetone accounts for 28% of the total volume of water and acetone), and adjust the pH value of the solution to 7 with ammonia water to obtain the flame retardant finishing liquid. The concentration of the intumescent flame retardant in the flame retardant finishing liquid is 160 g / L;

[0082] (3) Immerse the 45 / 55 polyester / cotton blended fabric into the flame retardant finishing solution obtained in step (2), and treat the polyester / cotton blended fabric by the method of padding-baking-curing. Control the liquor pickup rate at 102%, the pre-drying temperature at 70 °C, the pre-drying time at 3 min, the curing temperature at 162 °C, and the curing time at 6 min to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant.

[0083] The surface of the obtained polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame retardant film. The network flame retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate, and the network flame retardant film and the polyester / cotton blended fabric are bridged by covalent bonds;

[0084] The flame retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 31.9%, the damage length is 9.9 cm, no melt dripping occurs, and the maximum heat release rate is 126.8 W / g; the damage length is 13.1 cm after 30 washes.

Claims

1. A polyester / cotton blended fabric flame-retarded by an intumescent flame retardant, characterized in that: The surface of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant has a network flame-retardant film, and the network flame-retardant film is bridged with the polyester / cotton blended fabric through covalent bonds; The network flame-retardant film is formed by connecting the intumescent flame retardant to the surface of the polyester / cotton blended fabric through tris(epoxypropyl)isocyanurate; The structural formula of the intumescent flame retardant is 2. The polyester / cotton blended fabric flame-retarded by the intumescent flame retardant according to claim 1, wherein The flame-retardant properties of the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant are as follows: the limiting oxygen index is 29.8% - 33.5%, the char length is 11.9 - 8.3 cm, there is no melt dripping, and the maximum heat release rate is 121.3 - 139.2 W / g; after 30 washes, the char length is not higher than 14.6 cm.

3. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 1 or 2, characterized in that: The polyester / cotton blended fabric is immersed in the flame-retardant finishing solution, and the polyester / cotton blended fabric is treated by the pad-dry-cure method to obtain the polyester / cotton blended fabric flame-retarded by the intumescent flame retardant; The flame-retardant finishing solution is obtained by dissolving the intumescent flame retardant, tris(epoxypropyl)isocyanurate, sodium thiosulfate and dicyandiamide in a mixed solution of water and acetone, and adjusting the pH value of the solution to 6 - 7 with ammonia water.

4. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 3, characterized in that, The concentration of the intumescent flame retardant in the flame-retardant finishing solution is 100 - 200 g / L.

5. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 4, characterized in that, The molar ratio of tris(epoxypropyl)isocyanurate to the intumescent flame retardant is 2 - 3:1; acetone accounts for 20% - 30% of the total volume of water and acetone; the mass of sodium thiosulfate is 3 - 5% of tris(epoxypropyl)isocyanurate; the mass of dicyandiamide is 5 - 7% of the intumescent flame retardant.

6. A method for preparing a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 5, characterized in that The process parameters of pad-dry-cure are: the liquor ratio is 100 - 110%; the pre-drying temperature is 70 - 80 °C, and the pre-drying time is 2 - 4 min; The curing temperature is 160 - 170 °C, and the curing time is 5 - 8 min.

7. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 6, characterized in that, The polyester / cotton blended fabric is a 35 / 65, 40 / 60 or 45 / 55 polyester / cotton blended fabric.

8. The preparation method of a polyester / cotton blended fabric flame-retarded by the intumescent flame retardant according to claim 3, characterized in that, The preparation method of the intumescent flame retardant is: heating tris(epoxypropyl)isocyanurate to 140 - 150 °C, adding pentaerythritol and reacting for 3 - 4 h, then adding phosphoric acid and continuing to react at 105 - 115 °C for 3 - 4 h, and obtaining the intumescent flame retardant after drying and purification.

9. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 8, characterized in that, The molar ratio of tris(epoxypropyl)isocyanurate to pentaerythritol is 2 - 2.2:1; the molar ratio of phosphoric acid to tris(epoxypropyl)isocyanurate is 2 - 2.3:

1.

10. The preparation method of a polyester / cotton blended fabric flame-retarded by an intumescent flame retardant according to claim 8, characterized in that, The yield of the intumescent flame retardant is 75 - 79%.

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