CN116397438B - Durable flame-retardant polyester/cotton blended fabric and preparation method thereof - Google Patents

Abstract

The invention relates to a durable flame-retardant polyester/cotton blended fabric and a preparation method thereof, belonging to the technical field of textile finishing. The preparation method comprises the following steps that (1) tris (epoxypropyl) isocyanurate reacts with pentaerythritol for 3 to 4 hours at 140 to 150 ℃, and then phosphoric acid is added to continue to react for 3 to 4 hours at 115 to 125 ℃ to obtain a reactive flame retardant; (2) Dissolving a reactive flame retardant, polycarboxylic acid, sodium hypophosphite and dicyandiamide in water, and regulating the pH to 7-8 to obtain a flame retardant finishing liquid; (3) And (3) dipping the polyester/cotton blended fabric into the flame-retardant finishing liquid, and performing padding, pre-baking and baking treatment to obtain the durable flame-retardant polyester/cotton blended fabric. The reactive flame retardant is favorable for forming expanded carbon residue on the surface of the polyester/cotton blended fabric, and has the effect of isolating heat, oxygen and combustible gas. The reactive flame retardant is grafted on the polyester/cotton blended fabric in a plurality of crosslinking modes, so that the flame retardant polyester/cotton blended fabric has higher durable flame retardant property.

Description

A durable flame-retardant polyester/cotton blended fabric and its preparation method

Technical field

The invention belongs to the technical field of textile finishing, and in particular relates to a durable flame-retardant polyester/cotton blended fabric and a preparation method thereof.

Background technique

Polyester/cotton blended fabrics have very excellent properties. They have the hygroscopicity and heat resistance of pure cotton fabrics, as well as the high elasticity, wear resistance, and stiffness of polyester fabrics. They are widely used in clothing, indoor home furnishings, decoration, and transportation. It is widely used in tool decoration and other fields. However, due to the "candle wick effect" of polyester/cotton blended fabrics, they are highly flammable. Once they catch fire, they can easily spread and cause fires. The difficulty of flame-retardant finishing is much greater than that of pure cotton and pure polyester fabrics. So far, a lot of research has been done on the flame-retardant finishing of polyester/cotton blended fabrics at home and abroad, but there is still no mature commercialized durable flame-retardant finishing process.

Reference 1 (Research on flame retardant finishing of polyester-cotton blended curtain fabrics [J]. Journal of Chengdu Textile College, 2016, 33(3):94-97.) The phosphorus-nitrogen composite flame retardant NHPT, Resin, etc. for durable finishing of polyester-cotton blended fabrics; Reference 2 (Application of new flame retardants in polyester-cotton blended fabrics [J]. Dyeing and Finishing Technology, 2021, 43(10):25-28.) Polyester is used The combination of flame retardants and cotton flame retardants improves the flame retardant properties of two-component fabrics such as polyester/cotton blended fabrics; Chinese invention patent CN104746338A discloses a flame retardant working fluid and pure cotton using the flame retardant working fluid. A flame-retardant finishing method for fabrics and/or polyester-cotton blended fabrics, which uses flame retardants for cotton and polyester fabrics to prepare a flame-retardant finishing liquid, and uses an N-hydroxymethyl cross-linking agent to improve the flame retardancy of pure cotton fabrics and polyester/cotton blends. The washing resistance of the fabric. Covalent cross-linking of flame retardants with polyester/cotton blended fabrics can help improve the durable flame retardant properties of flame-retardant polyester/cotton blended fabrics. However, the N-hydroxymethyl cross-linking agent used in flame-retardant polyester/cotton blended fabrics caused by this method causes formaldehyde release problems during the finishing and application process.

Reference 3 (Flame-retardant finishing of polyester/cotton blended fabrics with phosphorus/nitrogen flame retardants [J]. Acta Textile Sinica, 2022, 43(6):94-99,106) uses phytic acid and urea to synthesize ammonium phytate. The rolling-baking-baking process performs formaldehyde-free flame retardant finishing on polyester/cotton blended fabrics. Ammonium phytate can produce covalent cross-linking with cotton fibers under the catalysis of dicyandiamide. However, during the high-temperature baking process, phosphoric acid The ammonium group easily decomposes to generate phosphate and ammonia, which results in the inability to build the phosphorus/nitrogen synergistic flame retardant effect, reducing the flame retardant efficiency of the flame retardant. The finished polyester/cotton blended fabric has poor water resistance and loses flame retardancy after washing. Effect.

Therefore, it is of great significance to develop a high-efficiency reactive phosphorus/nitrogen synergistic flame retardant and use it to prepare polyester/cotton blended fabrics with excellent flame retardant and durable properties, and without the problem of formaldehyde release during finishing and application. .

Contents of the invention

In order to solve the above technical problems, the present invention provides a durable flame-retardant polyester/cotton blended fabric and a preparation method thereof. Polyester/cotton blended fabrics have less cotton fiber components than pure cotton fabrics. Therefore, how to efficiently graft flame retardants onto the cotton fiber components to give polyester/cotton blended fabrics durable flame retardant properties is a difficult point. . Synthesis integrates multiple flame retardant groups and multiple reactive groups to develop efficient reactive flame retardants. At the same time, the flame retardants are efficiently grafted onto polyester/cotton blended fabrics through multiple cross-linking methods. Helps improve its durable flame retardant properties. In addition, the reaction conditions of different reactive groups, such as reaction temperature and pH, are quite different. The compatibility between flame retardant groups is also a difficulty in preparing multi-reactive group flame retardants.

The first object of the present invention is to provide a preparation method of durable flame-retardant polyester/cotton blended fabric, which includes the following steps:

(1) Tris(epoxypropyl)isocyanurate and pentaerythritol react at 140℃-150℃ for 3h-4h, then add phosphoric acid and continue the reaction at 115℃-125℃ for 3h-4h to obtain reactive flame retardant agent;

(2) Dissolve the reactive flame retardant, polycarboxylic acid, sodium hypophosphite and dicyandiamide described in step (1) in water, adjust the pH to 7-8, and obtain a flame retardant finishing liquid;

(3) Dip the polyester/cotton blended fabric into the flame-retardant finishing liquid described in step (2), and undergo padding-prebaking-baking treatment to obtain a durable flame-retardant polyester/cotton blended fabric.

In one embodiment of the present invention, in step (1), the reactive flame retardant contains an acid source, a gas source and a carbon source at the same time. The combination of the three can effectively construct an intumescent flame retardant with higher Flame retardant properties; in addition, the flame retardant has a variety of reactive groups, which can be cross-linked with polyester/cotton blended fabrics through multiple cross-linking methods at the same time to solve the problem of poor grafting efficiency of a single active group and flame retardant durability. Bad question. The structure of reactive flame retardants is as follows:

In one embodiment of the present invention, in step (1), the molar ratio of tris(epoxypropyl)isocyanurate, pentaerythritol and phosphoric acid is 1:1-1.3:2-2.3. The molar ratio of tris(epoxypropyl)isocyanurate and pentaerythritol is 1:1-1.3, which is the epoxy opening of the epoxy group of tris(epoxypropyl)isocyanurate and the hydroxyl group of pentaerythritol. In the cycloaddition reaction, a slight excess of pentaerythritol will help improve the reaction efficiency, but too much will be wasteful. The molar ratio of tris(epoxypropyl)isocyanurate and phosphoric acid is 1:2-2.3, which is the remaining two epoxy groups and phosphate groups of tris(epoxypropyl)isocyanurate. In the epoxy ring-opening addition reaction, a slight excess of phosphoric acid will help improve the reaction efficiency, but too much will be wasteful.

In one embodiment of the present invention, in step (1), the reaction is performed at 140°C-150°C for 3h-4h, and 140°C-150°C is higher than the melting point of tris(epoxypropyl)isocyanurate. Under this temperature condition, tris(epoxypropyl)isocyanurate is liquid, which is helpful for the reaction; the reaction time is 3h-4h, and the increase in reaction temperature and the extension of time are helpful for the synthesis reaction. But too high is a waste.

In one embodiment of the present invention, in step (1), the reaction is continued for 3h-4h at 115°C-125°C. The increase in reaction temperature and the extension of time are helpful for the synthesis reaction, but if it is too high, it will be wasteful. .

In one embodiment of the present invention, step (1) also includes the step of purifying the reactive flame retardant, which specifically includes: vacuum drying the phosphate ester flame retardant first, and then using Methanol and toluene are used for purification, and the yield of reactive flame retardant is 74%-77%.

In one embodiment of the present invention, in step (2), the polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid and/or citric acid.

In one embodiment of the present invention, in step (2), the concentration of the reactive flame retardant in the flame retardant finishing liquid is 100g/L-200g/L. Increasing the dosage of reactive flame retardants will help improve the flame retardant properties of polyester/cotton blended fabrics, but the content of flame retardants on polyester/cotton blended fabrics will reach saturation, and excessive amounts will be wasted.

In one embodiment of the present invention, in step (2), the molar ratio of the reactive flame retardant and the polycarboxylic acid is 1:1.3-1.5; the mass of dicyandiamide is 5 times that of the reactive flame retardant. %-10%; the quality of sodium hypophosphite is 40%-50% of polycarboxylic acid.

In one embodiment of the present invention, in step (2), the pH adjuster is ammonia water. Under this pH condition, the phosphate group is converted into an ammonium phosphate group, which is helpful for covalent bonding with the cotton fiber. Union.

In one embodiment of the present invention, in step (3), the rolling residue rate after padding is 100%-110%. The higher the residual rate, the higher the liquid content of the polyester/cotton blended fabric, which helps to improve the flame retardant performance. However, if the flame retardant content on the fabric is too high, it will reach saturation, causing waste.

In one embodiment of the present invention, in step (3), the pre-baking temperature is 70°C-80°C and the time is 2min-4min; the baking temperature is 160°C-170°C and the time is 3min-5min. The increase in baking temperature will help promote the esterification cross-linking reaction between the ammonium phosphate group of the reactive flame retardant and the hydroxyl group of the cotton fiber, and will also help the esterification of the polycarboxylic acid, the reactive flame retardant, and the cotton fiber. Cross-linking reaction, but if it is too high, it will be wasteful and may easily cause damage to the physical properties of the fabric.

In one embodiment of the present invention, in step (3), the polyester/cotton blended fabric is a 35/65, 40/60 or 45/55 polyester/cotton blended fabric.

In one embodiment of the present invention, the ammonium phosphate group of the reactive flame retardant can undergo an esterification cross-linking reaction with the hydroxyl group of the cotton fiber under the catalysis of dicyandiamide; polycarboxylic acid as a cross-linking agent can react with the reactive flame retardant The esterification reaction of the hydroxyl group of the flame retardant and the hydroxyl group of the cotton fiber helps to graft the reactive flame retardant onto the polyester/cotton blended fabric through covalent bonds; a slight excess of polycarboxylic acid helps to increase cross-linking If the efficiency is too high, it will be wasted; sodium hypophosphite acts as a catalyst to promote the esterification and cross-linking reaction between the carboxyl groups of polycarboxylic acids and the reactive flame retardants and the hydroxyl groups of cotton fibers.

The second object of the present invention is to provide a durable flame-retardant polyester/cotton blended fabric prepared by the method.

In one embodiment of the present invention, the flame retardant properties of the durable flame-retardant polyester/cotton blended fabric are: the limiting oxygen index (LOI) is 29.5%-32.8%, the damage length is 11.5-8.9cm, and no melt droplets are generated (not yet The LOI of the modified polyester/cotton blended fabric is 17.3%, and the damage length is 30cm); the polyester/cotton blended fabric treated with 200g/L flame retardant can withstand 40 times of washing, indicating that the modified polyester fabric has efficient and durable flame retardancy. Function.

The principle of the present invention is as follows:

The invention uses tris(epoxypropyl)isocyanurate as an intermediate to combine active hydroxyl groups and phosphate groups into one body. It also contains nitrogen-containing heterocyclic flame retardant groups and is organically combined with phosphorus-containing flame retardant groups to construct a structure. Phosphorus/nitrogen synergistic flame retardant effect, with high flame retardant efficiency. Dicyandiamide is used to catalyze the esterification reaction between ammonium phosphate radicals and the hydroxyl groups of cotton fibers to generate phosphate ester bonds; at the same time, polycarboxylic acids are used as cross-linking agents, and the polycarboxylic acids react with the hydroxyl groups of the flame retardant and the hydroxyl groups of the cotton fibers. The flame retardant is fixed on the polyester/cotton blended fabric through covalent bonds through various cross-linking methods to achieve a durable flame retardant effect. The reaction conditions of the two reactive groups, active hydroxyl group and phosphate group, are similar, and both can produce cross-linking with polyester/cotton blended fabrics under high-temperature baking conditions. The ammonium phosphate radical of the present invention can undergo an esterification reaction with the hydroxyl group of cotton fiber under the catalysis of dicyandiamide. In addition, the polycarboxylic acid serves as a cross-linking agent between the flame retardant and the cotton fiber, which also helps to further connect the flame retardant. On polyester/cotton blended fabrics, neither cross-linking method will produce formaldehyde.

However, when polyester/cotton blended fabrics are grafted using the hydroxyl and ammonium phosphate groups of flame retardants alone, the flame retardant durability is poor. This is because when the flame retardant ammonium phosphate and hydroxyl/polycarboxylic acid are used alone for cross-linking, the saturation degree of the flame retardant participating in the cross-linking is low, and a sufficient amount of flame retardant cannot be grafted on the polyester through covalent bonds. /cotton blend fabric. The saturation degree of the cross-linked flame retardant can be increased through double cross-linking, so that more hydroxyl groups on the cotton fiber participate in the reaction. At the same time, the durability of double-crosslinked flame retardants on polyester/cotton blended fabrics is better because the conditions required to break the covalent bonds of phosphate esters and carboxylate esters simultaneously are more stringent.

The technical solution of the present invention has the following advantages compared with the existing technology:

(1) The preparation method of the present invention combines phosphorus-containing flame retardant groups, nitrogen-containing heterocycles, and polyol groups through covalent bonds to synthesize a reactive flame retardant containing the three groups as one body. Baking leads to the loss of nitrogen; the phosphate in the reactive 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 an intumescent flame retardant; during the combustion process , the reactive flame retardant helps to form expanded carbon residue on the surface of the polyester/cotton blended fabric, which can insulate heat, oxygen and flammable gases, and has excellent flame retardant properties.

(2) In the preparation method of the present invention, the reactive flame retardant reacts with ammonia to form an ammonium phosphate salt through an ionic bond reaction. Under the action of the dicyandiamide catalyst and high temperature, an esterification reaction occurs between the ammonium phosphate root and the hydroxyl group of the cotton fiber; Reactive flame retardants have two phosphate active sites and have high reactivity with cotton fibers. Reactive flame retardants react with cotton fibers in polyester/cotton blended fabrics through covalent bonds; in addition, polycarboxylic acids Under this condition, esterification cross-linking reaction can also occur with reactive flame retardants and cotton fibers. The reactive flame retardants can be grafted onto polyester/cotton blended fabrics through various cross-linking methods. Therefore, flame retardant polyester/cotton blended fabrics Blended fabrics have higher wash resistance.

Description of the drawings

In order to make the content of the present invention easier to understand clearly, the present invention will be further described in detail below based on specific embodiments of the present invention and in conjunction with the accompanying drawings, wherein:

Figure 1 is the ¹³ C nuclear magnetic resonance spectrum of the reactive flame retardant in Example 1 of the present invention.

Figure 2 is a vertical burning test chart of the polyester/cotton blended fabric without flame retardant modification of the present invention and the durable flame retardant polyester/cotton blended fabric of Example 1 after 0 and 40 times of washing.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples, so that those skilled in the art can better understand and implement the present invention, but the examples are not intended to limit the present invention.

Example 1

A durable flame-retardant polyester/cotton blended fabric and its preparation method, specifically including the following steps:

(1) Add 0.1 mol of tris(epoxypropyl) isocyanurate into a three-necked flask, heat to 145°C, add 0.12 mol of pentaerythritol and react for 3.5 hours, then add 0.22 mol of phosphoric acid and continue the reaction at 120°C for 3.5 hours. After vacuum drying, methanol and toluene were used for purification to obtain a reactive flame retardant with a yield of 76%.

(2) Dissolve the reactive flame retardant, 1,2,3,4-butanetetracarboxylic acid, sodium hypophosphite and dicyandiamide in water, add ammonia water to adjust the solution to adjust the pH to 8, and obtain a flame retardant finishing liquid ; The concentration of reactive flame retardant in the flame retardant finishing liquid is 200g/L; the molar ratio of reactive flame retardant and 1,2,3,4-butanetetracarboxylic acid is 1:1.5; the mass of dicyandiamide It is 8% of reactive flame retardant; the mass of sodium hypophosphite is 50% of 1,2,3,4-butanetetracarboxylic acid.

(3) Dip the 45/55 polyester/cotton blended fabric into the flame-retardant finishing liquid. After padding, the padding rate is 105%; then pre-dry the polyester/cotton blended fabric at 75°C for 3 minutes, and finally After baking at 165°C for 4 minutes, a durable flame-retardant polyester/cotton blended fabric was obtained.

Comparative example 1

It is basically the same as Example 1, except that step (2) does not add dicyandiamide and performs single cross-linking through 1,2,3,4-butanetetracarboxylic acid.

Comparative example 2

It is basically the same as Example 1, except that step (2) does not add 1,2,3,4-butanetetracarboxylic acid and performs single cross-linking through dicyandiamide.

Example 2

(1) Add 0.1 mol of tris(epoxypropyl) isocyanurate into a three-necked flask, heat to 140°C, then add 0.1 mol of pentaerythritol to react for 4 hours, then add 0.2 mol of phosphoric acid and continue the reaction for 4 hours at 115°C, then vacuum After drying, methanol and toluene are used for purification to obtain a reactive flame retardant with a yield of 75%.

(2) Dissolve the reactive flame retardant, 1,2,3,4-butanetetracarboxylic acid, sodium hypophosphite and dicyandiamide in water, add ammonia water to adjust the solution to adjust the pH to 7, and obtain a flame retardant finishing liquid ; The concentration of the reactive flame retardant in the flame retardant finishing liquid is 170g/L; the molar ratio of the reactive flame retardant and 1,2,3,4-butanetetracarboxylic acid is 1:1.3; the mass of dicyandiamide It is 6% of the reactive flame retardant; the mass of sodium hypophosphite is 40% of 1,2,3,4-butanetetracarboxylic acid.

(3) Dip the 40/60 polyester/cotton blended fabric into the flame-retardant finishing solution. After padding, the padding rate is 110%; then pre-dry the polyester/cotton blended fabric at 70°C for 4 minutes, and finally Bake at 160°C for 5 minutes to obtain durable flame-retardant polyester/cotton blended fabric.

Example 3

(1) Add 0.1 mol of tris(epoxypropyl) isocyanurate into a three-necked flask, heat to 150°C, then add 0.13 mol of pentaerythritol to react for 3 hours, then add 0.23 mol of phosphoric acid and continue the reaction for 3 hours at 125°C, then vacuum After drying, methanol and toluene are used for purification to obtain a reactive flame retardant with a yield of 77%.

(2) Dissolve the reactive flame retardant, citric acid, sodium hypophosphite and dicyandiamide in water, add ammonia to adjust the solution to adjust the pH to 7.5, and obtain a flame retardant finishing liquid; the reactive flame retardant in the flame retardant finishing liquid The concentration is 125g/L; the molar ratio of reactive flame retardant and citric acid is 1:1.5; the mass of dicyandiamide is 10% of the reactive flame retardant; the mass of sodium hypophosphite is 45% of the citric acid .

(3) Dip the 35/65 polyester/cotton blended fabric into the flame-retardant finishing solution. After padding, the padding rate is 100%; then pre-dry the polyester/cotton blended fabric at 80°C for 2 minutes, and finally After baking for 3 minutes at 170°C, a durable flame-retardant polyester/cotton blended fabric was obtained.

Example 4

(1) Add 0.1 mol of tris(epoxypropyl) isocyanurate into a three-necked flask, heat to 147°C, add 0.12 mol of pentaerythritol and react for 3.5 hours, then add 0.21 mol of phosphoric acid and continue the reaction at 122°C for 3.6 hours. After vacuum drying, methanol and toluene were used for purification to obtain a reactive flame retardant with a yield of 74%.

(2) Dissolve the reactive flame retardant, citric acid, sodium hypophosphite and dicyandiamide in water, add ammonia to adjust the solution to adjust the pH to 7, and obtain a flame retardant finishing liquid; the reactive flame retardant in the flame retardant finishing liquid The concentration is 100g/L; the molar ratio of reactive flame retardant and citric acid is 1:1.4; the mass of dicyandiamide is 5% of the reactive flame retardant; the mass of sodium hypophosphite is 43% of the citric acid .

(3) Dip the 40/60 polyester/cotton blended fabric into the flame-retardant finishing liquid. After padding, the padding rate is 105%; then pre-dry the polyester/cotton blended fabric at 75°C for 3 minutes, and finally After baking at 165°C for 4 minutes, a durable flame-retardant polyester/cotton blended fabric was obtained.

Test example 1

The reactive flame retardant prepared in Example 1 was characterized, and the results are shown in Figure 1. It can be seen from Figure 1 that the chemical shifts at 151.7 and 150.5 ppm are caused by the carbon atoms of the C=O structure on the nitrogen heterocycle, and the chemical shifts at 57.4 and 48.0 ppm are caused by the carbon atoms of the C-OH structure of pentaerythritol and Caused by the central carbon atom, the chemical shift at 45.1ppm is caused by the carbon atoms of the C-N structure connected to the epoxy group; the chemical shifts at 66.9ppm and 63.5ppm are caused by the epoxy group in the reactive flame retardant structure It is caused by the carbon atoms of the C-O-P and C-OH structures generated after the group reaction, indicating that the epoxy group reacted with the phosphate group. The chemical shift at 74.8 ppm is caused by the carbon atoms in the C-O structure after the epoxy group reacted with the pentaerythritol hydroxyl group. The above structure shows that the reactive flame retardant was successfully synthesized.

Test example 2

The flame retardant properties of the unfinished polyester/cotton blended fabrics, the finished polyester/cotton blended fabrics of Examples 1-4 and Comparative Examples 1-2 were tested.

The limiting oxygen index (LOI) of the fabric is measured according to the standard GB/T5454-1997 "Textile Combustion Performance Experimental Oxygen Index Method".

The thermal analysis test method was used to test the carbon residue amount of flame-retardant polyester/cotton blended fabrics and unfinished polyester/cotton blended fabrics under nitrogen conditions.

The damage length of the fabric is measured in accordance with the standard GB/T5455-2014 "Determination of smoldering and afterburning time of vertical damage length of textile combustion properties".

The burning performance of the fabric is evaluated in accordance with the GB/T17591-2006 "Flame Retardant Fabrics" standard.

The washing method refers to AATCC61-2006 "Accelerated Test of Color Fastness to Washing for Household and Commercial Use".

Figure 2 is a vertical burning test chart of the polyester/cotton blended fabric without flame retardant modification and the durable flame retardant polyester/cotton blended fabric of Example 1 after 0 and 40 times of washing:

Table 1 shows the final measured relevant performance parameters of polyester/cotton blended fabrics:

Table 1

sample LOI/% Carbon residue/% at 700℃ Damaged length/cm Washing resistance Unfinished polyester/cotton blended fabric 17.3% 8.3 30 0 Example 1 32.8 35.3 8.9 40 Comparative example 1 32.4 34.1 9.2 10 Comparative example 2 32.6 34.5 9.0 15 Example 2 31.9 30.9 9.7 35 Example 3 30.7 26.2 10.8 30 Example 4 29.5 22.7 11.5 25

As can be seen from Table 1 and Figure 2, the flame retardant properties of durable flame-retardant polyester/cotton blended fabrics are: limiting oxygen index (LOI) is 29.5%-32.8%, damage length is 11.5-8.9cm, and no melt droplets are generated ( The LOI of the unmodified polyester/cotton blended fabric is 17.3% and the damaged length is 30cm); the polyester/cotton blended fabric treated with 200g/L flame retardant can withstand 40 times of washing, indicating that the modified polyester/cotton blended fabric has high efficiency Durable flame retardant feature. Comparative Example 1 can withstand 10 times of water washing, and Comparative Example 2 can withstand 15 times of water washing, indicating that the single cross-linking and reactive flame retardant phosphate groups produced by the reactive flame retardant through polycarboxylic acid and polyester/cotton blended fabrics are Polyester/cotton blended fabrics produced by single cross-linking have poor water-washing resistance. Double cross-linking in the embodiments can give polyester/cotton blended fabrics excellent water-washing resistance.

Obviously, the above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other changes or modifications may be made based on the above description. An exhaustive list of all implementations is neither necessary nor possible. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims (9)

1. A method for preparing durable flame-retardant polyester/cotton blended fabric, which is characterized by comprising the following steps: (1) Tris(epoxypropyl)isocyanurate and pentaerythritol react at 140℃-150℃ for 3h-4h, then add phosphoric acid and continue the reaction at 115℃-125℃ for 3h-4h to obtain reactive flame retardant agent; the structure of the reactive flame retardant is as follows: ; (2) Dissolve the reactive flame retardant, polycarboxylic acid, sodium hypophosphite and dicyandiamide described in step (1) in water, adjust the pH to 7-8, and obtain a flame retardant finishing liquid; (3) Dip the polyester/cotton blended fabric into the flame-retardant finishing liquid described in step (2), and undergo padding-prebaking-baking treatment to obtain a durable flame-retardant polyester/cotton blended fabric. 2. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that, in step (1), the tris(epoxypropyl)isocyanurate, pentaerythritol and phosphoric acid The molar ratio is 1:1-1.3:2-2.3. 3. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that, in step (2), the polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid. acid and/or citric acid. 4. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that, in step (2), the concentration of the reactive flame retardant in the flame-retardant finishing liquid is 100g/L -200g/L. 5. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that, in step (2), the molar ratio of the reactive flame retardant and the polycarboxylic acid is 1:1.3 -1.5; the mass of dicyandiamide is 5%-10% of the reactive flame retardant; the mass of sodium hypophosphite is 40%-50% of the polycarboxylic acid. 6. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that in step (3), the padding rate after padding is 100%-110%. 7. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that in step (3), the pre-baking temperature is 70°C-80°C and the time is 2min-4min ; The baking temperature is 160℃-170℃, and the baking time is 3min-5min. 8. The preparation method of durable flame-retardant polyester/cotton blended fabric according to claim 1, characterized in that in step (3), the polyester/cotton blended fabric is 35/65, 40/60 or 45/ 55% polyester/cotton blended fabric. 9. A durable flame-retardant polyester/cotton blended fabric prepared by the method of any one of claims 1-8.