Preparation method of phosphorus-nitrogen intumescent flame retardant and flame-retardant cotton fabric

Abstract

The invention relates to a preparation method of a phosphorus-nitrogen intumescent flame retardant and a flame-retardant cotton fabric. According to the invention, erythritol and phosphoric acid are used as raw materials to prepare erythritol phosphate through esterification reaction, and then the prepared erythritol phosphate reacts with urea to prepare the phosphorus-nitrogen intumescent flame retardant. The flame retardant prepared by the invention is a water-soluble flame retardant, after the flame-retardant finishing liquid is prepared, the fabric is treated by a rolling-drying-baking process, and then the fabric is dried in a water system to obtain the flame-retardant cotton fabric. The flame retardant prepared by the method contains phosphorus and nitrogen, the synergistic flame retardant effect of the phosphorus / nitrogen can be exerted, the flame retardant property of the finished cotton fabric is greatly improved, the cotton fabric has self-extinguishing capacity, and the LOI value reaches 41.4%.

Description

Technical Field

[0001] The invention relates to a preparation method of a phosphorus-nitrogen expansion type flame retardant and flame-retardant cotton fabric, belonging to the field of flame-retardant finishing of textiles. Background Art

[0002] As a natural fiber fabric, cotton fabric has been widely used in clothing, home textiles, industrial production, biomedicine and other fields due to its comfort, breathability, skin-friendly and environmentally friendly characteristics. However, the limiting oxygen index (LOI) of cotton fabric is only about 18%, which is very flammable. Once exposed to open flames, cotton fabrics will burn rapidly, causing the fire to spread. In addition, the main components of cotton fabrics are carbon, hydrogen and oxygen, which will release carbon monoxide and carbon dioxide gases when burned, causing people to suffocate and lack of oxygen. Therefore, flame retardant finishing of cotton fabrics is of practical significance, which can improve its safety and broaden its application areas.

[0003] In the past few decades, halogen flame retardants have been widely used due to their excellent flame retardant effect. However, the hydrogen halide gas released during combustion can cause secondary hazards and has been banned in many countries. Since then, people have also been committed to developing halogen-free and environmentally friendly flame retardants. Among them, phosphorus-based flame retardants have the best effect and are regarded as the best substitute for halogen-based flame retardants. However, the two commercial halogen-free flame retardants THPC and Pyrovatex CP currently have formaldehyde release problems. Other halogen-free flame retardants have poor effects when used alone. Therefore, it is urgent to develop halogen-free, formaldehyde-free environmentally friendly flame retardants for flame retardant finishing of cotton fabrics. Summary of the invention

[0004] [Technical issues]

[0005] At present, there are problems such as poor flame retardant effect, low flame retardant efficiency and environmental pollution when flame retardant finishing is performed on cotton fabrics.

[0006] [Technical solution]

[0007] In order to solve the above problems, the present invention aims to provide a method for preparing a phosphorus-nitrogen intumescent flame retardant. The flame retardant uses water as a solvent when used. The flame retardant performance of the cotton fabric after finishing is greatly improved, the LOI value can reach 40.1%, and it can be self-extinguishing.

[0008] To achieve the above-mentioned purpose, the present invention provides a method for preparing a phosphorus-nitrogen intumescent flame retardant, which specifically comprises the following steps: mixing erythritol with phosphoric acid, heating and reacting to prepare erythritol phosphate; mixing erythritol phosphate with urea, heating and reacting to prepare a phosphorus-nitrogen intumescent flame retardant.

[0009] The method for preparing a phosphorus-nitrogen intumescent flame retardant comprises mixing erythritol with phosphoric acid, and heating the mixture to prepare erythritol phosphate, comprising: adding erythritol and phosphoric acid into a three-necked flask, placing the three-necked flask into a constant temperature magnetic stirring heater for fixing, and setting up a condensation reflux device; and obtaining erythritol phosphate after heating the mixture.

[0010] The reaction equation of the preparation method of the present invention is as follows:

[0011]

[0012] In the preparation method of the phosphorus-nitrogen intumescent flame retardant, the reaction temperature of erythritol and phosphoric acid is 120-140° C., and the reaction time is 3-5 hours.

[0013] In the preparation method of the phosphorus-nitrogen intumescent flame retardant, the molar ratio of the erythritol to the phosphoric acid is 1:4-5.

[0014] The method for preparing a phosphorus-nitrogen intumescent flame retardant comprises: mixing erythritol phosphate with urea, heating for reaction, and obtaining the phosphorus-nitrogen intumescent flame retardant, comprising: mixing erythritol phosphate with urea, heating for reaction; washing with anhydrous ethanol and then drying to obtain the phosphorus-nitrogen intumescent flame retardant.

[0015] In the preparation method of the phosphorus-nitrogen intumescent flame retardant, the reaction temperature of the erythritol phosphate and urea is 110-130° C., and the reaction time is 2-4 hours.

[0016] In the preparation method of the phosphorus-nitrogen intumescent flame retardant, the molar ratio of the erythritol phosphate to the urea is 1:4-8.

[0017] The invention provides a phosphorus-nitrogen intumescent flame retardant prepared by the method.

[0018] The invention provides application of the phosphorus-nitrogen intumescent flame retardant in cotton fabric finishing.

[0019] The method for finishing cotton fabric with phosphorus-nitrogen intumescent flame retardant of the present invention comprises the following steps: placing the cotton fabric in a finishing solution of the flame retardant for padding treatment, then pre-baking the cotton fabric at 80°C for 10 minutes and then baking the cotton fabric, followed by washing and drying to obtain the flame-retardant cotton fabric: the baking temperature is 160-180°C, and the baking time is 2-5 minutes.

[0020] [Beneficial Effects]

[0021] The flame retardant provided by the present invention uses water as a solvent when used, and does not need to use an organic solvent.

[0022] The flame retardant provided by the present invention contains phosphorus and nitrogen. The phosphorus can play a role by capturing free radicals and promoting dehydration and carbonization of fabrics, while the nitrogen can produce non-combustible gas and reduce the concentration of oxygen and combustible gas. When the two elements work synergistically, an expanded carbon layer can be formed to play a highly efficient flame retardant role.

[0023] The raw materials used in the flame retardant provided by the present invention are environmentally friendly, widely available, low-priced and easy to produce; the finishing process is simple to operate; the flame retardant performance is highly effective, and the flame retardant performance of the cotton fabric after finishing is greatly improved, the LOI value can reach 41.4%, and the fabric can be self-extinguished; after the flame retardant finishing, the strength and whiteness of the fabric are well retained. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flame retardant performance test comparison chart of the flame retardant fabrics obtained in Example 4 and Comparative Example 1. DETAILED DESCRIPTION

[0025] [Test method]

[0026] Test of limiting oxygen index: According to GB / T 5454-1997 "Textile Combustion Performance Test Oxygen Index Method", 5 pieces of flame retardant cotton fabrics are prepared. The test sample size is about 250×60mm. In the oxygen-nitrogen mixed gas flow, the percentage is used to express the minimum oxygen concentration required to maintain its combustion.

[0027] Flame retardant performance (afterflame time, smoldering time, char length) test: According to GB / T5455 1997 "Vertical method for testing the burning performance of textiles", the fabric was tested vertically on the YG815 vertical method fabric burning performance tester. The standard sample size was 300×80mm. (The results are shown in the figure below.) Figure 1 (shown)

[0028] The phosphorus-nitrogen intumescent flame retardant provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1

[0030] Add 6.106 g (0.05 mol) of erythritol and 23.059 g (0.20 mol) of phosphoric acid into a three-necked flask, place the three-necked flask into a constant temperature magnetic stirring heater, and set up a condensing reflux device; heat to 120° C., stir and react for 5 hours, and then cool to obtain erythritol phosphate.

[0031] 22.898 g (0.05 mol) of erythritol phosphate and 24.024 g (0.40 mol) of urea were mixed, heated to 110° C. and reacted for 4 h; washed with anhydrous ethanol and dried to obtain a phosphorus-nitrogen intumescent flame retardant.

[0032] Example 2

[0033] Add 6.106 g (0.05 mol) of erythritol and 28.823 g (0.25 mol) of phosphoric acid into a three-necked flask, place the three-necked flask into a constant temperature magnetic stirring heater, and set up a condensing reflux device; heat to 140° C., stir and react for 3 hours, and then cool to obtain erythritol phosphate.

[0034] 22.898 g (0.05 mol) of erythritol phosphate and 12.012 g (0.20 mol) of urea were mixed, heated to 130° C. and reacted for 2 h; washed with anhydrous ethanol and dried to obtain a phosphorus-nitrogen intumescent flame retardant.

[0035] Example 3

[0036] Add 6.106 g (0.05 mol) of erythritol and 25.363 g (0.22 mol) of phosphoric acid into a three-necked flask, place the three-necked flask into a constant temperature magnetic stirring heater, and set up a condensing reflux device; heat to 130° C., stir and react for 4 hours, and then cool to obtain erythritol phosphate.

[0037] 22.90 g (0.05 mol) of erythritol phosphate and 18.018 g (0.3 mol) of urea were mixed, heated to 120° C. and reacted for 3 h; washed with anhydrous ethanol and dried to obtain a phosphorus-nitrogen intumescent flame retardant.

[0038] Example 4

[0039] The phosphorus-nitrogen intumescent flame retardant prepared in Example 1 was dissolved in deionized water, and 60 g / L of dicyandiamide was added as a catalyst. The mixture was heated in a water bath at 60° C. with stirring until the catalyst was dissolved, to prepare 200 g / L of a flame retardant finishing liquid.

[0040] The cotton fabric was placed in a flame retardant finishing liquid and finished with a two-immersion and two-rolling process, with the rolling rate controlled at 100%. The fabric was then dried at 80°C for 10 minutes and baked at 160°C for 2 minutes.

[0041] The baked fabric is washed with water and then dried at 70°C to obtain the flame retardant cotton fabric.

[0042] Example 5

[0043] The difference from Example 4 is that the flame retardant concentration is 100, 300, and 400 g / L, and the others are the same as Example 4.

[0044] The flame retardant cotton fabric obtained was subjected to a flame retardant performance test, and the test results are as follows:

[0045] Table 1

[0046]

[0047] Example 6

[0048] The difference from Example 4 is that the phosphorus-nitrogen intumescent flame retardant prepared in Example 2 is used, and the rest is the same as Example 4.

[0049] Example 7

[0050] The difference from Example 6 is that the baking temperature is adjusted to 165°C, 170°C, and 180°C, and the rest is the same as Example 6.

[0051] The flame retardant cotton fabric obtained was subjected to a flame retardant performance test, and the test results are as follows:

[0052] Table 2

[0053]

[0054]

[0055] Example 8

[0056] The difference from Example 4 is that the phosphorus-nitrogen intumescent flame retardant prepared in Example 3 is used, and the rest is the same as Example 4.

[0057] Example 9

[0058] The difference from Example 8 is that the baking time is adjusted to 3, 4, and 5 minutes, and the rest is the same as Example 4.

[0059] The flame retardant cotton fabric obtained was subjected to a flame retardant performance test, and the test results are as follows:

[0060] Table 3

[0061]

[0062] Comparative Example 1

[0063] The difference from Example 4 is that no dicyandiamide catalyst is added to the aqueous solution, but urea in the same amount is used instead. Other operations are the same as those in Example 4.

[0064] Comparative Example 2

[0065] The difference from Example 4 is that no phosphorus-nitrogen flame retardant is added to the aqueous solution, and only dicyandiamide catalyst is added. Other operations are the same as those in Example 4.

[0066] Comparative Example 3

[0067] The difference from Example 4 is that after being immersed in the flame retardant finishing liquid, the fabric is taken out, washed and dried, and no other operations are performed.

[0068] The flame retardant cotton fabric obtained was subjected to a flame retardant performance test, and the test results are as follows:

[0069] Table 4

[0070]

[0071] It can be seen from the results in Table 4 that replacement of the various raw materials and process flows used in the present invention will have an impact on the flame retardant properties of the final finished fabric.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a phosphorus-nitrogen intumescent flame retardant, characterized in that: The following steps are involved: Mixing erythritol and phosphoric acid, heating and reacting, to prepare erythritol phosphate; Erythritol phosphate and urea are mixed and heated to react to obtain a phosphorus-nitrogen intumescent flame retardant.

2. The preparation method according to claim 1, characterized in that: The step of mixing erythritol and phosphoric acid and heating them for reaction to prepare erythritol phosphate comprises: Add erythritol and phosphoric acid into a three-necked flask, place the three-necked flask into a constant temperature magnetic stirring heater, and set up a condensation reflux device; after heating reaction, erythritol phosphate is obtained.

3. The preparation method according to claim 2, characterized in that: The reaction temperature is 120-140° C., and the reaction time is 3-5 hours.

4. The preparation method according to claim 2, characterized in that: The molar ratio of erythritol to phosphoric acid is 1:4-5.

5. The preparation method according to claim 1, characterized in that: The erythritol phosphate is mixed with urea, and heated to react to obtain a phosphorus-nitrogen intumescent flame retardant, comprising: Erythritol phosphate and urea are mixed and heated for reaction; the mixture is washed with anhydrous ethanol and then dried to obtain a phosphorus-nitrogen intumescent flame retardant.

6. The preparation method according to claim 5, characterized in that: The reaction temperature is 110-130°C, and the reaction time is 2-4h.

7. The preparation method according to claim 5, characterized in that: The molar ratio of the erythritol phosphate to urea is 1:4-8.

8. A phosphorus-nitrogen intumescent flame retardant, characterized in that: The phosphorus-nitrogen intumescent flame retardant is prepared by the preparation method described in any one of claims 1 or 5 to 7.

9. Use of the phosphorus-nitrogen intumescent flame retardant according to claim 8 in finishing of cotton fabrics.

10. The use according to claim 9, characterized in that: The method for finishing cotton fabric comprises the following steps: The cotton fabric is placed in the finishing liquid of the flame retardant for padding treatment, and then the cotton fabric is pre-baked at 80°C for 10 minutes and then baked, and then washed and dried to obtain the flame retardant cotton fabric: the baking temperature is 160-180°C, and the baking time is 2-5 minutes.

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