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

Abstract

The invention relates to a preparation method of a phosphorus-boron-nitrogen flame retardant and a flame-retardant cotton fabric. According to the preparation method, erythritol phosphate is prepared by taking erythritol and phosphoric acid as raw materials through esterification reaction, and then the prepared erythritol phosphate reacts with boric acid and urea to prepare the erythritol ammonium phosphate borate. The prepared flame retardant can react with the cotton fabric under the action of a catalyst to form a P-O-C covalent bond, the flame retardance of the finished cotton fabric is greatly improved, and the LOI value can reach 42.5%. After the flame retardant prepared by the invention is used for finishing the cotton fabric, the physical and mechanical properties of the fabric are kept at a relatively high level.

Description

Technical Field

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

[0002] As a natural fiber fabric with a long history of use, cotton fabric has the characteristics of fast moisture absorption, good mechanical properties, breathability, softness, comfort and biodegradability, so it has a broad prospect for use. In recent years, the average output of cotton fiber in the world is about 25 million tons, accounting for 28% of the total global fiber output. With the improvement of living standards, people pay more attention to the safety of textiles. However, cotton fabric itself is very easy to burn, and the limiting oxygen index value is only about 18%, which limits its application to a certain extent. In the event of a fire, the flammability of cotton fabric will cause the fire to spread, and a large amount of CO and CO2 gas will be produced during combustion. Therefore, flame retardant modification of cotton fabric can not only improve its own safety, but also broaden its application field, which has practical guiding significance.

[0003] There are many flame retardant finishing processes for cotton fabrics, most of which use a flame retardant coating on the surface of the fabric to perform flame retardant finishing on the fabric. This type of finishing process has the problems of poor durability, cumbersome process, and poor fabric feel. While the fabric acquires flame retardant properties, it will affect the processing and application of the fabric. Therefore, when performing flame retardant finishing on cotton fabrics, making the fabric have flame retardant properties while maintaining the original properties of the fabric has become a difficult problem in flame retardant finishing of fabrics. Summary of the invention

[0004] Technical issues

[0005] The flame retardant finishing of cotton fabrics has problems such as complicated process, poor finishing effect and damage to the fabric.

[0006] Technical Solution

[0007] In order to solve the above-mentioned problems, the purpose of the present invention is to provide a method for preparing a phosphorus / boron / nitrogen type flame retardant, which adopts a rolling-baking-baking process during finishing, is easy to operate, has high performance of the flame retardant, and can achieve good flame retardant effect at a low concentration of the flame retardant.

[0008] The first object of the present invention is to provide a method for preparing a phosphorus / boron / nitrogen flame retardant, which specifically comprises the following steps:

[0009] Step 1. Add erythritol and phosphoric acid into a three-necked flask, fix the three-necked flask in a constant temperature magnetic stirring heater, and install a condensation reflux device and a thermometer, and heat to react to obtain erythritol phosphate;

[0010] Step 2. Dissolve boric acid in DMF (NN dimethylformamide), add it into a three-necked flask, and add erythritol phosphate. Heat the reaction to remove DMF to obtain a colorless oily product.

[0011] Step 3. Mix the colorless oily product obtained in Step 2 with urea, add them into a three-necked flask, heat and react to obtain a crude product, wash the product with anhydrous ethanol, and dry it at 70°C to obtain a phosphorus / boron / nitrogen flame retardant.

[0012] The reaction equation of the preparation method of the present invention is as follows:

[0013]

[0014] In one embodiment of the present invention, the reaction temperature of Step 1 is 120-140° C., and the reaction time is 3-5 hours.

[0015] In one embodiment of the present invention, the molar ratio of erythritol to phosphoric acid in Step 1 is 1:4-5.

[0016] In one embodiment of the present invention, the reaction temperature of Step 2 is 110-130° C., and the reaction time is 1-3 hours.

[0017] In one embodiment of the present invention, the ratio of the amount of erythritol phosphate to the amount of boric acid in Step 2 is 1:2-3.

[0018] In one embodiment of the present invention, the reaction temperature of Step 3 is 110-130° C., and the reaction time is 2-4 hours.

[0019] In one embodiment of the present invention, in Step 3, the molar ratio of the colorless oily product obtained in Step 2 to urea is 1:4-6.

[0020] The second object of the present invention is to provide a phosphorus / boron / nitrogen flame retardant based on the above method.

[0021] The second object of the present invention is to provide an application of the above-mentioned phosphorus / boron / nitrogen flame retardant in flame retardant finishing of cotton fabrics, the method comprising: placing the cotton fabric in a finishing solution of the flame retardant for padding treatment, 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.

[0022] In one embodiment of the present invention, the baking time is 2 to 5 minutes.

[0023] Beneficial Effects

[0024] The flame retardant provided by the present invention contains phosphorus, boron and nitrogen elements. The phosphorus and boron components can promote the dehydration and carbonization process of the fabric to form a dense carbon layer to isolate heat and oxygen. The nitrogen-containing component can produce non-combustible gases such as nitrogen and ammonia to reduce the concentration of oxygen and combustible gases. The flame retardant can play a role in the gas phase and the condensed phase, and has high flame retardant performance.

[0025] The raw materials used in the flame retardant provided by the present invention are environmentally friendly, widely available, low in price and easy to produce; the finishing process is simple to operate and can be mass-produced; the flame retardant of the flame retardant is highly effective, and the flame retardant of the cotton fabric after finishing is greatly improved, the LOI value can reach 42.5%, and the fabric can be self-extinguished; after the flame retardant finishing, the physical and mechanical properties of the fabric are maintained at a relatively high level. DETAILED DESCRIPTION

[0026] Test Method

[0027] 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.

[0028] Breaking strength test: According to GB / T3923-2013 "Strip method for determination of breaking strength and breaking elongation of fabric tensile properties", the fabric is tested using an electronic fabric strength tester. Three pieces are taken in each of the warp and weft directions. The test sample size is 50mm×200mm.

[0029] Whiteness test: According to AATCC 110-2000 standard, the whiteness of the sample was tested using Datacolor Spectravision colorimeter (Datacolor USA). Three tests were performed at different locations on each sample to obtain the average value.

[0030] The phosphorus / boron / nitrogen 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 understood as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] Step 1. Add 6.106 g (0.05 mol) of erythritol and 23.059 g (0.20 mol) of phosphoric acid into a three-necked flask, fix the three-necked flask in a constant temperature magnetic stirring heater, and install a condensation reflux device and a thermometer, heat to 120 ° C, stir and react for 4 hours, and remove water to obtain erythritol phosphate.

[0033] Step 2. Dissolve 9.282 g (0.15 mol) of boric acid in DMF (NN dimethylformamide), add it into a three-necked flask, and add 22.898 g (0.05 mol) of erythritol phosphate. After reacting at 110°C for 3 h, remove DMF to obtain a colorless oily product.

[0034] Step 3. Mix 26.497 g (0.05 mol) of the colorless oily product obtained in Step 2 with 15.015 g (0.25 mol) of urea, add them into a three-necked flask, react at 130° C. for 4 h to obtain a crude product, wash the product with anhydrous ethanol, and dry it at 70° C. to obtain a phosphorus / boron / nitrogen flame retardant.

[0035] Example 2

[0036] Step 1. Add 6.106 g (0.05 mol) of erythritol and 25.364 g (0.22 mol) of phosphoric acid into a three-necked flask, fix the three-necked flask in a constant temperature magnetic stirring heater, and install a condensation reflux device and a thermometer, heat to 130 ° C, stir and react for 5 hours, and remove water to obtain erythritol phosphate.

[0037] Step 2. Dissolve 6.183 g (0.10 mol) of boric acid in DMF (NN dimethylformamide), add it into a three-necked flask, and add 22.898 g (0.05 mol) of erythritol phosphate. After reacting at 130°C for 4 hours, remove DMF to obtain a colorless oily product.

[0038] Step 3. Mix 26.497 g (0.05 mol) of the colorless oily product obtained in Step 2 with 12.012 g (0.20 mol) of urea, add them into a three-necked flask, react at 110° C. for 2 h to obtain a crude product, wash the product with anhydrous ethanol, and dry it at 70° C. to obtain a phosphorus / boron / nitrogen flame retardant.

[0039] Example 3

[0040] Step 1. Add 6.106 g (0.05 mol) of erythritol and 28.824 g (0.25 mol) of phosphoric acid into a three-necked flask, fix the three-necked flask in a constant temperature magnetic stirring heater, and install a condensation reflux device and a thermometer, heat to 140 ° C, stir and react for 3 hours, and remove water to obtain erythritol phosphate.

[0041] Step 2. Dissolve 7.729 g (0.15 mol) of boric acid in DMF (NN dimethylformamide), add it into a three-necked flask, and add 22.898 g (0.05 mol) of erythritol phosphate. After reacting at 120°C for 2 h, remove DMF to obtain a colorless oily product.

[0042] Step 3. Mix 26.497 g (0.05 mol) of the colorless oily product obtained in Step 2 with 18.018 g (0.25 mol) of urea, add them into a three-necked flask, react at 120° C. for 3 h to obtain a crude product, wash the product with anhydrous ethanol, and dry it at 70° C. to obtain a phosphorus / boron / nitrogen flame retardant.

[0043] Example 4

[0044] The phosphorus / boron / nitrogen 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.

[0045] 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 170°C for 3 minutes.

[0046] The baked fabric is washed with water and then dried at 70°C to obtain the flame retardant cotton fabric.

[0047] Example 5

[0048] 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.

[0049] The flame retardant cotton fabric obtained was tested for flame retardancy, breaking strength and whiteness, and the test results are as follows:

[0050] Table 1

[0051]

[0052]

[0053] Example 6

[0054] The difference from Example 4 is that the phosphorus / boron / nitrogen flame retardant prepared in Example 2 is used, and the other operations are the same as Example 4.

[0055] Example 7

[0056] The difference from Example 6 is that the baking temperature is adjusted to 160°C, 175°C, and 180°C, and the rest is the same as Example 6.

[0057] The flame retardant cotton fabric obtained was tested for flame retardancy, breaking strength and whiteness, and the test results are as follows:

[0058] Table 2

[0059]

[0060] Example 8

[0061] The difference from Example 4 is that the phosphorus / boron / nitrogen flame retardant prepared in Example 3 is used, and the other operations are the same as Example 4.

[0062] Example 9

[0063] The difference from Example 8 is that the baking time is adjusted to 2, 4, and 5 minutes, and the rest is the same as Example 4.

[0064] The flame retardant cotton fabric obtained was subjected to a flame retardant performance test, and the test results are as follows:

[0065] Table 3

[0066]

[0067] Comparative Example 1

[0068] It is cotton fabric without flame retardant finishing.

[0069] Comparative Example 2

[0070] The difference from Example 4 is that no phosphorus / boron / nitrogen flame retardant is added to the aqueous solution, and only dicyandiamide catalyst is added. Other operations are the same as Example 4.

[0071] Comparative Example 3

[0072] The difference from Example 4 is that no dicyandiamide catalyst is added, and other operations are the same as Example 4.

[0073] Comparative Example 4

[0074] The difference from Example 4 is that no pre-baking and baking treatment is performed after the fabric is padded. Other operations are the same as those in Example 4.

[0075] The obtained cotton fabric was subjected to flame retardant performance test, and the test results are as follows:

[0076] Table 4

[0077]

[0078] It can be seen from Table 4 that any random changes to the raw materials and operating procedures used in the present invention will affect the flame retardant properties of the fabric and ultimately fail to achieve the desired flame retardant effect.

[0079] 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 / boron / nitrogen flame retardant, characterized in that: The following steps are involved: Step 1. Add erythritol and phosphoric acid into a three-necked flask, fix the three-necked flask in a constant temperature magnetic stirring heater, and install a condensation reflux device and a thermometer, and heat to react to obtain erythritol phosphate; Step 2. Dissolve boric acid in DMF (NN dimethylformamide), add it into a three-necked flask, and add erythritol phosphate. Heat the reaction to remove DMF to obtain a colorless oily product. Step 3. Mix the colorless oily product obtained in Step 2 with urea, add them into a three-necked flask, heat and react to obtain a crude product, wash the product with anhydrous ethanol, and dry it at 70°C to obtain a phosphorus / boron / nitrogen flame retardant.

2. The preparation method according to claim 1, characterized in that: The reaction temperature of Step 1 is 120-140°C, and the reaction time is 3-5h.

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

4. The preparation method according to claim 1, characterized in that: The reaction temperature of Step 2 is 110-130°C, and the reaction time is 1-3h.

5. The preparation method according to claim 1, characterized in that: The molar ratio of erythritol phosphate and boric acid in Step 2 is 1:2-3.

6. The preparation method according to claim 1, characterized in that: The reaction temperature of Step 3 is 110-130°C, and the reaction time is 2-4h.

7. The preparation method according to claim 1, characterized in that: In Step 3, the molar ratio of the colorless oily product obtained in Step 2 to urea is 1:4-6.

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

9. Use of the phosphorus / boron / nitrogen flame retardant according to claim 8 in flame retardant 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.

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