Preparation method of polyester / cotton blended fabric with lasting flame-retardant and smoke-suppressing functions

Abstract

The invention relates to a preparation method of a polyester / cotton blended fabric with lasting flame-retardant and smoke-suppressing functions, the polyester / cotton blended fabric is immersed in a flame-retardant finishing liquid, the polyester / cotton blended fabric with lasting flame-retardant and smoke-suppressing functions is prepared through a rolling and baking process, and the flame-retardant finishing liquid is obtained by adding dicyandiamide into a phosphorus / nitrogen / silicon flame retardant solution; the preparation method of the phosphorus / nitrogen / silicon flame retardant solution comprises the following steps: dissolving diethylenetriaminepenta (methylene phosphonic acid) and polyvinyl alcohol in water, adding ammonia water to adjust the pH value of the solution to 6-8 to obtain a mixed solution, dropwise adding an ethanol solution of tetraethyl orthosilicate into the mixed solution at the rate of 0.5-1mL / min, and reacting to obtain the phosphorus / nitrogen / silicon flame retardant solution. The phosphorus / nitrogen / silicon flame retardant is firmly grafted on the polyester / cotton blended fabric through the adhesion capacity of the polyvinyl alcohol film and the covalent bond reaction of the polyvinyl alcohol film and the cotton fiber, and the prepared product has excellent flame retardance and smoke suppression performance.

Description

Technical Field

[0001] The invention belongs to the technical field of flame-retardant polyester / cotton blended fabrics and relates to a method for preparing a polyester / cotton blended fabric with durable flame-retardant and smoke-suppressing functions. Background Art

[0002] Polyester / cotton blended fabric is a kind of fabric blended from polyester and cotton fibers. It combines the advantages of polyester and cotton fibers. It not only has good elasticity and wear resistance, but also has the characteristics of dimensional stability, small shrinkage, bright luster, smooth and crisp feel. Polyester / cotton blended fabrics are widely used in home textiles, bedding, work clothes in the fields of fire protection, petroleum, electricity, natural gas, etc., so the flame retardant properties of polyester / cotton blended fabrics are required to be more stringent. However, polyester / cotton blended fabrics have a "bracket effect" during the combustion process, resulting in high flammability and combustibility, so there is a high demand for flame retardant finishing.

[0003] In response to the flame retardant finishing needs of polyester / cotton blended fabrics, a variety of methods have been proposed. Reference 1 (Application of new flame retardants in polyester-cotton blended fabrics [J]. Dyeing and Finishing Technology, 2021, 43(10): 25-28) uses polyester and cotton flame retardant / crosslinking agent systems to modify polyester / cotton blended fabrics to make them flame retardant; in this technical solution, the cotton flame retardant is cross-linked with the cotton fiber, and the polyester flame retardant is combined with the polyester fabric through the principle of similar dissolution, so the modified polyester / cotton blended fabric can withstand 20 washes. However, the flame retardant efficiency of the two flame retardants acting alone is low, and the degree of grafting is limited, so its water washing resistance needs to be further improved.

[0004] Reference 2 (Research and Development of Flame-Retardant Polyester Fabrics Based on Phosphate Ester [J]. Modern Silk Science and Technology, 2020, 35(3): 4-6, 40.) uses phytic acid and polyvinyl alcohol to synthesize a linear phosphate ester flame retardant through an esterification reaction (i.e., phytic acid is grafted onto polyvinyl alcohol as a flame retardant). However, when the phosphate ester flame retardant is coated on the surface of the fabric, the polyvinyl alcohol therein forms a film and is physically adhered to the fabric, resulting in poor water wash resistance, which still needs to be further improved.

[0005] In addition, Chinese invention patent CN117364487A discloses a method for preparing a polyester / cotton blended fabric with a durable flame retardant coating, wherein polyvinyl alcohol, N-(phosphonomethyl)iminodiacetic acid, diethyl hydroxymethylphosphonate, sodium hypophosphite and triethanolamine are dissolved in distilled water to prepare a flame retardant finishing liquid, and then the polyester / cotton blended fabric is treated by a padding-baking method to obtain a polyester / cotton blended fabric with a durable flame retardant coating; however, the flame retardant efficiency of the flame retardant system is poor, and a high amount of flame retardant is required.

[0006] Therefore, it is of great significance to study a method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function to solve the problems existing in the prior art. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a polyester / cotton blended fabric with durable flame retardant and smoke suppression functions.

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

[0009] A method for preparing a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function, comprising immersing the polyester / cotton blended fabric in a flame retardant finishing liquid, and performing a rolling and baking process to obtain the polyester / cotton blended fabric with a durable flame retardant and smoke suppression function, wherein the flame retardant finishing liquid is obtained by adding dicyandiamide to a phosphorus / nitrogen / silicon flame retardant solution;

[0010] The preparation method of the phosphorus / nitrogen / silicon flame retardant solution is as follows: firstly, diethylenetriaminepenta(methylenephosphonic acid) and polyvinyl alcohol are dissolved in water, and ammonia water is added to adjust the pH value of the solution to 6-8 to obtain a mixed solution, so that part of the phosphate groups of the diethylenetriaminepenta(methylenephosphonic acid) are converted into ammonium phosphate groups, which is helpful for the subsequent tetraethyl orthosilicate to generate silica sol and is helpful for the subsequent covalent bond grafting reaction; then, an ethanol solution of tetraethyl orthosilicate is added dropwise to the mixed solution at a rate of 0.5-1 mL / min, and the dropwise addition is helpful to promote the hydrolysis and condensation reaction of tetraethyl orthosilicate after contact with water to generate silica sol, and the phosphorus / nitrogen / silicon flame retardant solution is obtained by reaction.

[0011] As the preferred technical solution:

[0012] The preparation method of a durable flame retardant and smoke suppression functional polyester / cotton blended fabric as described above, the specific rolling and baking process is: a two-immersion and two-rolling method is adopted, and the rolling rate is 90~110%; the pre-baking temperature is 70~90℃, the time is 2~3min, and the baking temperature is 160~170℃, and the time is 3~4min; a higher baking temperature helps to promote the covalent bond grafting reaction between the ammonium phosphate root of diethylenetriaminepenta(methylenephosphonic acid) and the hydroxyl groups of cotton fibers and polyvinyl alcohol, but too high a temperature will cause greater damage to the physical properties of the fabric.

[0013] The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function as described above, wherein the content of polyester in the polyester / cotton blended fabric is 20-80%.

[0014] In the preparation method of a durable flame retardant and smoke suppression polyester / cotton blended fabric as described above, the content of dicyandiamide in the flame retardant finishing liquid is 30-50 g / L, and dicyandiamide can be used as a catalyst to promote the covalent bond grafting reaction between the phosphate group of diethylenetriamine penta(methylenephosphonic acid) in the mixed solution and the hydroxyl groups of cotton fibers and polyvinyl alcohol.

[0015] As described above, in the preparation method of a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function, the content of diethylenetriaminepenta(methylenephosphonic acid) in the mixed solution is 75-100 g / L, and diethylenetriaminepenta(methylenephosphonic acid) is the main flame retardant component. The higher the amount used, the better the flame retardant performance, but too high a content is wasteful; the content of polyvinyl alcohol is 30-60 g / L.

[0016] In the method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function as described above, the content of tetraethyl orthosilicate in the phosphorus / nitrogen / silicon flame retardant solution is 20-40 g / L.

[0017] In the method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function as described above, in the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 1-2:1.

[0018] In the method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function as described above, the ethanol solution of tetraethyl orthosilicate is added at a rate of 0.5-1 mL / min, and the reaction is continued for 2-3 hours after the addition is completed.

[0019] The method for preparing a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function as described above, wherein the limiting oxygen index of the polyester / cotton blended fabric with a durable flame retardant and smoke suppression function is not less than 31.5%, the damaged length is not higher than 8.9 cm, and the total amount of smoke released is not higher than 0.48 m 2 After 40 washes, the damaged length is still no more than 14.5cm, meeting the B1 standard (the limiting oxygen index of unmodified polyester / cotton blended fabric is 19.2%, the damaged length is 30cm, and the total smoke release is 0.74m 2 ).

[0020] The principle of the present invention is:

[0021] The phosphate group of diethylenetriamine penta(methylenephosphonic acid) can undergo an esterification cross-linking reaction with the hydroxyl group of cotton fiber under the catalysis of dicyandiamide, thereby grafting the phosphorus-containing flame retardant group onto the cotton fiber. However, the cotton fiber component content in polyester / cotton blended fabrics is limited, and it is difficult to graft a sufficient amount of phosphorus-containing flame retardant onto the polyester / cotton blended fabric, and it is impossible to provide lasting flame retardant properties. In addition, the phosphorus-containing flame retardant alone causes the smoke release of polyester / cotton blended fabrics to increase, thereby increasing the fire hazard.

[0022] In the present invention, the silanol groups formed by hydrolysis of the siloxane structure of tetraethyl orthosilicate undergo hydrolysis and condensation in an aqueous solution to generate a network-like silica sol, and the silanol groups can react with the phosphate groups of diethylenetriaminepenta(methylenephosphonic acid) and the hydroxyl groups of polyvinyl alcohol after hydrolysis, so that a new network-like phosphorus / nitrogen / silicon flame retardant is formed between the silicon-containing network, diethylenetriaminepenta(methylenephosphonic acid) (including a part of ammonium diethylenetriaminepenta(methylenephosphonic acid) converted from diethylenetriaminepenta(methylenephosphonic acid), and polyvinyl alcohol;

[0023] like Figure 1 As shown, under the catalysis of dicyandiamide, the phosphate in the network phosphorus / nitrogen / silicon flame retardant can undergo esterification cross-linking reaction with the hydroxyl group of cotton fiber and the hydroxyl group of polyvinyl alcohol (polyvinyl alcohol includes both the polyvinyl alcohol molecular chain of the network phosphorus / nitrogen / silicon flame retardant itself and the polyvinyl alcohol that may not have reacted before) in the polyester / cotton blended fabric, and the polyvinyl alcohol can form a film on the surface of the polyester / cotton blended fabric. Under the baking conditions, the hydroxyl group in the polyvinyl alcohol molecule is dehydrated to form an ether bond structure, and the adhesion to the polyester / cotton blended fabric is enhanced. Therefore, the network phosphorus / nitrogen / silicon flame retardant is firmly grafted on the polyester / cotton blended fabric through the adhesion ability of the polyvinyl alcohol film itself and the covalent bond reaction with the cotton fiber, thereby providing durable flame retardant performance;

[0024] In addition, the phosphate group in the network phosphorus / nitrogen / silicon flame retardant acts as an acid source, the ammonium group acts as a gas source, and the polyvinyl alcohol acts as a carbon source, which organically combine to construct an expansion flame retardant system with high flame retardant efficiency. The silicon-containing flame retardant group helps to further improve the flame retardant properties and has the ability to inhibit smoke release. Therefore, the coating-modified polyester / cotton blended fabric has excellent flame retardant and smoke suppression properties.

[0025] Beneficial effects:

[0026] (1) The present invention provides a method for preparing a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function. The silanol groups formed by hydrolysis of the siloxane structure of tetraethyl orthosilicate undergo hydrolysis and condensation in an aqueous solution to generate a network-like silica sol. The silanol groups, after hydrolysis, can react with the phosphate groups of diethylenetriaminepenta(methylenephosphonic acid) and the hydroxyl groups of polyvinyl alcohol to form a new network-like phosphorus / nitrogen / silicon flame retardant. The network-like phosphorus / nitrogen / silicon flame retardant is firmly grafted onto the polyester / cotton blended fabric through the adhesion ability of the polyvinyl alcohol film itself and the covalent bond reaction with the cotton fiber, thereby providing durable flame retardant properties.

[0027] (2) The present invention provides a method for preparing a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function. The phosphate group in the network phosphorus / nitrogen / silicon flame retardant acts as an acid source, the ammonium group acts as a gas source, and the polyvinyl alcohol acts as a carbon source, which are organically combined to construct an intumescent flame retardant system with high flame retardant efficiency. The silicon-containing flame retardant group helps to further improve the flame retardant performance and has the ability to suppress smoke release. Therefore, the polyester / cotton blended fabric after coating modification has excellent flame retardant and smoke suppression properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the cross-linking mechanism of network-like phosphorus / nitrogen / silicon flame retardant and polyester / cotton blended fabric;

[0029] Figure 2It is a comparison chart of smoke release curves of polyester / cotton blended fabric and polyester / cotton blended fabric with durable flame retardant and smoke suppression function in Example 3 (i.e., the coated polyester / cotton blended fabric in the figure). DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0031] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0032] Damage length: measured in accordance with GB / T 5455-2014 "Determination of smoldering and afterflaming time of damage length in vertical direction of burning performance of textiles".

[0033] Total smoke release: The total smoke release of the sample was tested and characterized using a VOUCH 6810 cone calorimeter in accordance with ISO 5660-1 standard.

[0034] Damage length after 40 washes: First wash the fabric 40 times with water according to AATCC 61-2013 "Accelerated test for color fastness to household and commercial washing" standard, and then test the damage length of the fabric with reference to GB / T 5455-2014 "Determination of damage length in vertical direction, smoldering and afterflaming time of textile combustion performance" standard.

[0035] Example 1

[0036] A method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function, the specific steps are as follows:

[0037] (1) First, diethylenetriamine penta (methylenephosphonic acid) and 1788 type polyvinyl alcohol are dissolved in water, and ammonia water is added to adjust the pH value of the solution to 6 to obtain a mixed solution, and then an ethanol solution of tetraethyl orthosilicate is added dropwise at a rate of 0.5 mL / min to the mixed solution. After the addition is completed, the reaction is continued for 2 hours to obtain a phosphorus / nitrogen / silicon flame retardant solution;

[0038] Among them, in the mixed solution, the content of diethylenetriaminepenta(methylenephosphonic acid) is 75g / L, and the content of polyvinyl alcohol is 30g / L; in the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 1:1; in the phosphorus / nitrogen / silicon flame retardant solution, the content of tetraethyl orthosilicate is 20g / L;

[0039] (2) adding dicyandiamide to the phosphorus / nitrogen / silicon flame retardant solution to obtain a flame retardant finishing liquid; the content of dicyandiamide in the flame retardant finishing liquid is 30 g / L;

[0040] (3) immersing a polyester / cotton blended fabric with a polyester content of 20 wt% in a flame retardant finishing liquid, and sequentially performing two immersion and two rolling and baking treatments to obtain a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function;

[0041] Among them, the rolling rate is 90%; the baking process parameters are as follows: pre-baking temperature is 70℃, time is 3min, baking temperature is 170℃, time is 3min.

[0042] The resulting polyester / cotton blended fabric with durable flame retardancy and smoke suppression has a limiting oxygen index of 31.5%, a damaged length of 8.9 cm, and a total smoke release of 0.48 m 2 After 40 washes, the damaged length was 14.5 cm.

[0043] Comparative Example 1

[0044] A method for preparing a modified polyester / cotton blended fabric is basically the same as that of Example 1, except that polyvinyl alcohol is not added in step (1).

[0045] The final modified polyester / cotton blended fabric has a limiting oxygen index of 29.9%, a damaged length of 9.5 cm, and a total smoke release of 0.55 m 2 After 20 washes, the damaged length is 30cm.

[0046] By comparing Comparative Example 1 with Example 1, it can be found that when polyvinyl alcohol is not added, the flame retardant properties and water wash resistance of the modified polyester / cotton blended fabric are reduced. This is because the cotton fiber component content in the polyester / cotton blended fabric is limited, and it is difficult to graft a sufficient amount of phosphorus-containing flame retardant onto the polyester / cotton blended fabric, and it is impossible to provide lasting flame retardant properties.

[0047] Comparative Example 2

[0048] A method for preparing a modified polyester / cotton blended fabric is basically the same as that of Example 1, except that the ethanol solution of tetraethyl orthosilicate is not added in step (1).

[0049] The final modified polyester / cotton blended fabric had a limiting oxygen index of 30.8%, a damaged length of 9.1 cm, and a total smoke release of 0.81 m 2 After 30 washes, the damaged length is 30cm.

[0050] By comparing Comparative Example 2 with Example 1, it can be found that when the ethanol solution of tetraethyl orthosilicate is not added, the flame retardant properties and water washability of the modified polyester / cotton blended fabric are reduced, and the smoke release is significantly increased. This is because the silicon-containing network not only helps to form a synergistic flame retardant effect of phosphorus / nitrogen / silicon, further improving the flame retardant efficiency, but also forms inorganic oxides to inhibit smoke release.

[0051] Example 2

[0052] A method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function, the specific steps are as follows:

[0053] (1) First, diethylenetriamine penta (methylenephosphonic acid) and 1788 type polyvinyl alcohol were dissolved in water, and ammonia water was added to adjust the pH value of the solution to 6.5 to obtain a mixed solution, and then an ethanol solution of tetraethyl orthosilicate was added dropwise at a rate of 0.7 mL / min to the mixed solution. After the addition was completed, the reaction was continued for 2.5 h to obtain a phosphorus / nitrogen / silicon flame retardant solution;

[0054] Among them, in the mixed solution, the content of diethylenetriaminepenta(methylenephosphonic acid) is 80g / L, and the content of polyvinyl alcohol is 40g / L; in the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 1.3:1; in the phosphorus / nitrogen / silicon flame retardant solution, the content of tetraethyl orthosilicate is 25g / L;

[0055] (2) adding dicyandiamide to the phosphorus / nitrogen / silicon flame retardant solution to obtain a flame retardant finishing liquid; the content of dicyandiamide in the flame retardant finishing liquid is 35 g / L;

[0056] (3) immersing a polyester / cotton blended fabric with a polyester content of 35 wt% in a flame retardant finishing liquid, and sequentially performing two immersion and two rolling and baking treatments to obtain a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function;

[0057] Among them, the rolling rate is 95%; the baking process parameters are as follows: pre-baking temperature is 75℃, time is 2.8min, baking temperature is 160℃, time is 4min.

[0058] The resulting polyester / cotton blended fabric with long-lasting flame retardancy and smoke suppression had a limiting oxygen index of 32.8%, a damaged length of 8.5 cm, and a total smoke release of 0.41 m 2 After 40 washes, the damaged length was 13.6 cm.

[0059] Example 3

[0060] A method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function, the specific steps are as follows:

[0061] (1) First, diethylenetriamine penta (methylenephosphonic acid) and 1788 type polyvinyl alcohol were dissolved in water, and ammonia water was added to adjust the pH value of the solution to 7 to obtain a mixed solution, and then an ethanol solution of tetraethyl orthosilicate was added dropwise at a rate of 0.85 mL / min to the mixed solution. After the addition was completed, the reaction was continued for 2.75 h to obtain a phosphorus / nitrogen / silicon flame retardant solution;

[0062] Among them, in the mixed solution, the content of diethylenetriaminepenta(methylenephosphonic acid) is 90g / L, and the content of polyvinyl alcohol is 50g / L; in the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 1.7:1; in the phosphorus / nitrogen / silicon flame retardant solution, the content of tetraethyl orthosilicate is 30g / L;

[0063] (2) adding dicyandiamide to the phosphorus / nitrogen / silicon flame retardant solution to obtain a flame retardant finishing liquid; the content of dicyandiamide in the flame retardant finishing liquid is 40 g / L;

[0064] (3) immersing a polyester / cotton blended fabric with a polyester content of 50 wt% in a flame retardant finishing liquid, and sequentially performing two immersion and two rolling and baking treatments to obtain a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function;

[0065] Among them, the rolling rate is 100%; the baking process parameters are as follows: pre-baking temperature is 80℃, time is 2.5min, baking temperature is 165℃, time is 3.5min.

[0066] The resulting polyester / cotton blended fabric with durable flame retardant and smoke suppression function has a limiting oxygen index of 33.6% and a damaged length of 8.2 cm. After 40 washes, the damaged length is 13.1 cm. Figure 2 As shown in the figure, the total smoke release of polyester / cotton blended fabric is 0.74m 2 The total smoke release of polyester / cotton blended fabric with long-lasting flame retardancy and smoke suppression is 0.40m 2 .

[0067] Example 4

[0068] A method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function, the specific steps are as follows:

[0069] (1) First, diethylenetriamine penta (methylenephosphonic acid) and 1788 type polyvinyl alcohol are dissolved in water, and ammonia water is added to adjust the pH value of the solution to 8 to obtain a mixed solution, and then an ethanol solution of tetraethyl orthosilicate is added dropwise at a rate of 1 mL / min to the mixed solution. After the addition is completed, the reaction is continued for 3 hours to obtain a phosphorus / nitrogen / silicon flame retardant solution;

[0070] Among them, in the mixed solution, the content of diethylenetriaminepenta(methylenephosphonic acid) is 100g / L, and the content of polyvinyl alcohol is 60g / L; in the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 2:1; in the phosphorus / nitrogen / silicon flame retardant solution, the content of tetraethyl orthosilicate is 40g / L;

[0071] (2) adding dicyandiamide to the phosphorus / nitrogen / silicon flame retardant solution to obtain a flame retardant finishing liquid; the content of dicyandiamide in the flame retardant finishing liquid is 50 g / L;

[0072] (3) immersing a polyester / cotton blended fabric with a polyester content of 80% in a flame retardant finishing liquid, and sequentially performing two immersion and two rolling and baking treatments to obtain a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function;

[0073] Among them, the rolling rate is 105%; the baking process parameters are as follows: pre-baking temperature is 90℃, time is 2min, baking temperature is 170℃, time is 3.2min.

[0074] The resulting polyester / cotton blended fabric with long-lasting flame retardancy and smoke suppression had a limiting oxygen index of 34.1%, a damaged length of 7.9 cm, and a total smoke release of 0.33 m 2 After 40 washes, the damaged length was 12.8 cm.

Claims

1. A method for preparing a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function, comprising immersing the polyester / cotton blended fabric in a flame retardant finishing liquid, and performing a rolling and baking process to obtain a polyester / cotton blended fabric with a durable flame retardant and smoke suppression function, wherein: The flame retardant finishing liquid is obtained by adding dicyandiamide to a phosphorus / nitrogen / silicon flame retardant solution; The preparation method of the phosphorus / nitrogen / silicon flame retardant solution is as follows: firstly, diethylenetriaminepenta(methylenephosphonic acid) and polyvinyl alcohol are dissolved in water, and ammonia water is added to adjust the pH value of the solution to 6-8 to obtain a mixed solution, and then an ethanol solution of tetraethyl orthosilicate is added dropwise to the mixed solution at a rate of 0.5-1 mL / min to react and obtain the phosphorus / nitrogen / silicon flame retardant solution.

2. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 1, characterized in that: The specific rolling and baking process is: adopting a two-immersion and two-rolling method, with a rolling rate of 90~110%; the pre-baking temperature is 70~90℃, the time is 2~3min, and the baking temperature is 160~170℃, and the time is 3~4min.

3. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 1, characterized in that: The polyester content in polyester / cotton blended fabrics is 20~80%.

4. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 1, characterized in that: The content of dicyandiamide in the flame retardant finishing liquid is 30~50g / L.

5. The method for preparing a polyester / cotton blended fabric with durable flame retardant and smoke suppression function according to claim 4, characterized in that: In the mixed solution, the content of diethylenetriaminepenta(methylenephosphonic acid) is 75-100 g / L, and the content of polyvinyl alcohol is 30-60 g / L.

6. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 5, characterized in that: In the phosphorus / nitrogen / silicon flame retardant solution, the content of tetraethyl orthosilicate is 20~40g / L.

7. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 6, characterized in that: In the ethanol solution of tetraethyl orthosilicate, the mass ratio of tetraethyl orthosilicate to ethanol is 1-2:

1.

8. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 1, characterized in that: The ethanol solution of tetraethyl orthosilicate is added at a rate of 0.5-1 mL / min, and the reaction is continued for 2-3 hours after the addition is completed.

9. The method for preparing a polyester / cotton blended fabric with durable flame retardancy and smoke suppression function according to claim 1, characterized in that: The limiting oxygen index of polyester / cotton blended fabric with long-lasting flame retardancy and smoke suppression is not less than 31.5%, the damaged length is not higher than 8.9cm, and the total smoke release is not higher than 0.48m 2 After 40 washes, the damaged length is still no more than 14.5cm.

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