Flame-retardant lyocell fabric and preparation method thereof

Abstract

The present invention relates to a flame-retardant lyocell fabric and a preparation method thereof, characterized in that the fabric can be prepared by the following method: using melamine and chloropropyl-POSS as main raw materials to react to prepare a substitution product of melamine and chloropropyl-POSS; then, reacting formaldehyde, the substitution product and lyocell fabric to prepare the flame-retardant lyocell fabric. The initial limiting oxygen index of the flame-retardant lyocell fabric prepared by the present invention reaches more than 30%, which belongs to the range of flame-retardant materials; after being washed with water five times, the limiting oxygen index does not decrease significantly and still reaches more than 28%; in addition, after being washed with water five times, the flame retardant performance of the flame-retardant lyocell fabric prepared by the present invention slightly exceeds the flame retardant performance of purchased flame-retardant lyocell fabric.

Description

Technical Field

[0001] The invention belongs to the technical field of fabric preparation, and particularly relates to a flame-retardant lyocell fabric and a preparation method thereof. Background Art

[0002] The booming development of synthetic fiber materials and textile products has rapidly replaced traditional materials, finding widespread application across various sectors of the national economy, including industry, agriculture, and the military, and becoming integral to people's daily lives. However, most of these textiles are flammable and combustible. When burned, they release heat at high rates, have high calorific values, spread rapidly, and are difficult to extinguish. They also sometimes produce thick smoke and toxic gases, harming the environment and endangering human life. Therefore, improving the flame retardancy of textiles has become an urgent issue.

[0003] Lyocell fabric is made from lyocell fibers, known as green fibers. Its stable and excellent performance, made from non-toxic, readily available raw materials, surpasses synthetic and natural fibers in performance. The entire production process is pollution-free and chemically reactive. It also boasts high dry and wet strength, a high swelling ratio, unique fibrillation properties, and excellent spinnability. Lyocell fabric has a wide range of applications, from clothing to textiles used in industry, agriculture, and the military. However, like other synthetic fibers, lyocell is flammable, significantly limiting its application. Therefore, imparting excellent flame retardancy to lyocell fabrics is a key area of ​​focus.

[0004] Literature research shows that the flame retardant properties of lyocell fabrics have received widespread attention. For example, Chinese invention patent application No. 201811247384.1 discloses a method for preparing flame-retardant lyocell fibers, which are prepared by dissolving the flame retardant tris(2,3-dibromopropyl) phosphate and cellulose in the organic solvent NMMO simultaneously, and then spinning them to prepare flame-retardant lyocell fibers. The lyocell fibers prepared by this method have strong flame retardancy, a simple production process, and low cost. However, the flame retardant structure used is relatively simple and cannot achieve a synergistic flame retardant effect. Therefore, the modification process for the flame retardant properties of lyocell fabrics needs to be further improved. Summary of the Invention

[0005] In view of the above-mentioned drawbacks in the prior art, the present invention aims to provide a flame-retardant lyocell fabric and a preparation method thereof.

[0006] The present invention aims to provide a flame-retardant lyocell fabric. The fabric can be prepared by the following method: melamine and chloropropyl-POSS are reacted as main raw materials to prepare a substitution product of melamine and chloropropyl-POSS; then, formaldehyde, the substitution product and lyocell fabric are reacted to prepare the flame-retardant lyocell fabric.

[0007] Another object of the present invention is to provide a method for preparing a flame retardant lyocell fabric, the specific method comprising the following steps:

[0008] (1) In a four-necked flask, 5-7 g of chloropropyl-POSS and 1-2 g of triethylamine were dissolved in 150 mL of tetrahydrofuran, stirred in an ice bath and protected with N2. 4-6 g of melamine was dissolved in 100 mL of tetrahydrofuran. Under stirring, the tetrahydrofuran containing melamine and triethylamine was added dropwise to the tetrahydrofuran containing chloropropyl-POSS at a dropping rate of 1-3 drops / second. After the dropwise addition was completed, the reaction was carried out at a constant temperature in an ice bath. After the reaction was completed, the reaction was filtered under reduced pressure, rotary evaporated, and dried to obtain a substitution product of the reaction of chloropropyl-POSS and melamine.

[0009] Preferably, the reaction time is 5 to 9 hours.

[0010] (2) Add 10-15 mL of formaldehyde aqueous solution, 1-2 g of boric acid, 1-2 g of the substitution product obtained in step (1) and 150-200 mL of tap water into a three-necked flask and stir evenly to obtain a reaction solution; immerse the lyocell fabric in the reaction solution, control the temperature of the reaction solution to 40-50° C., and immerse for 10-15 minutes; after the reaction is completed, take out the lyocell fabric, wash it with tap water, and dry the lyocell fabric when the pH of the washing solution is 6-7 to obtain a flame-retardant lyocell fabric.

[0011] Preferably, the mass fraction of the formaldehyde aqueous solution is 10-20%.

[0012] Preferably, the ratio of the lyocell fabric (g) to the reaction solution (mL) is 1:50-150.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present invention realizes the grafting of nitrogen-containing and organosilicon-containing compounds on the surface of lyocell fabric, and this method significantly improves the flame retardant properties of lyocell fabric.

[0015] (2) The inventors of the present application unexpectedly discovered that the initial limiting oxygen index of the flame-retardant lyocell fabric prepared by the present invention reached more than 30%, which falls within the range of flame-retardant materials; after five water washings, its limiting oxygen index did not decrease significantly, and still reached more than 28%; in addition, after five water washings, the flame retardant properties of the flame-retardant lyocell fabric prepared by the present invention slightly exceeded the flame retardant properties of the purchased flame-retardant lyocell fabric.

[0016] (3) The present invention produces nitrogen- and organosilicon-containing compounds, which are excellent flame-retardant materials. Thus, the prepared lyocell fabric also has excellent flame-retardant properties.

[0017] (4) The inventors of the present application unexpectedly discovered that a chemical reaction between a nitrogen- and silicone-containing compound and Lyocell fabric can achieve a strong bond between the two. They further discovered that the flame retardant properties of Lyocell fabric remain unchanged after multiple washings.

[0018] (5) The flame-retardant lyocell fabric prepared by the method of the present invention has strong flame retardancy, the entire production process is simple, the price is low, and the production process has little pollution to the environment. DETAILED DESCRIPTION

[0019] The following examples and comparative examples illustrate the present invention in detail.

[0020] Sources of main raw materials: Flame-retardant lyocell fabric was purchased from Xinxiang Zhuocheng Special Textile Co., Ltd. Chloropropyl-POSS was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. Its molecular structure is as follows:

[0021]

[0022] Example 1

[0023] The present embodiment provides a method for preparing a flame-retardant lyocell fabric, the method comprising the following steps:

[0024] (1) In a four-necked flask, 6 g of chloropropyl-POSS and 1.5 g of triethylamine were dissolved in 150 mL of tetrahydrofuran, stirred in an ice bath and protected with N2. 5 g of melamine was dissolved in 100 mL of tetrahydrofuran. Under stirring, the tetrahydrofuran containing melamine and triethylamine was added dropwise to the tetrahydrofuran containing chloropropyl-POSS at a rate of 2 drops / second. After the addition was completed, the reaction was carried out at a constant temperature in an ice bath for 7 h. After the reaction was completed, the reaction was filtered under reduced pressure, rotary evaporated, and dried to obtain the substitution product of the reaction of chloropropyl-POSS and melamine.

[0025] (2) Add 12 mL of 15% formaldehyde aqueous solution, 1.5 g of boric acid, 1.5 g of the substitution product obtained in step (1) and 175 mL of tap water into a three-necked flask and stir evenly to obtain a reaction solution; immerse the lyocell fabric in the reaction solution, wherein the ratio of the lyocell fabric (g) to the reaction solution (mL) is 1:100, the temperature of the reaction solution is controlled to 45° C., and the immersion time is 13 minutes; after the reaction is completed, take out the lyocell fabric, wash it with tap water, and dry the lyocell fabric when the pH of the wash solution is 6.5 to obtain a flame-retardant lyocell fabric.

[0026] Example 2

[0027] The present embodiment provides a method for preparing a flame-retardant lyocell fabric, the method comprising the following steps:

[0028] (1) In a four-necked flask, 5 g of chloropropyl-POSS and 1 g of triethylamine were dissolved in 150 mL of tetrahydrofuran, stirred in an ice bath and protected with N2. 4 g of melamine was dissolved in 100 mL of tetrahydrofuran. Under stirring, the tetrahydrofuran containing melamine and triethylamine was added dropwise to the tetrahydrofuran containing chloropropyl-POSS at a dropping rate of 1 drop / second. After the addition was completed, the reaction was carried out at a constant temperature in an ice bath for 5 h. After the reaction was completed, the reaction was filtered under reduced pressure, rotary evaporated, and dried to obtain the substitution product of the reaction of chloropropyl-POSS and melamine.

[0029] (2) Add 10 mL of 10% formaldehyde aqueous solution, 1 g of boric acid, 1 g of the substitution product obtained in step (1) and 150 mL of tap water into a three-necked flask and stir evenly to obtain a reaction solution; immerse the lyocell fabric in the reaction solution, wherein the ratio of the lyocell fabric (g) to the reaction solution (mL) is 1:50, the temperature of the reaction solution is controlled to 40° C., and the immersion time is 10 minutes; after the reaction is completed, take out the lyocell fabric, wash it with tap water, and dry the lyocell fabric when the pH of the washing solution is 6 to obtain a flame-retardant lyocell fabric.

[0030] Example 3

[0031] The present embodiment provides a method for preparing a flame-retardant lyocell fabric, the method comprising the following steps:

[0032] (1) In a four-necked flask, 7 g of chloropropyl-POSS and 2 g of triethylamine were dissolved in 150 mL of tetrahydrofuran, stirred in an ice bath and protected with N2. 6 g of melamine was dissolved in 100 mL of tetrahydrofuran. Under stirring, the tetrahydrofuran containing melamine and triethylamine was added dropwise to the tetrahydrofuran containing chloropropyl-POSS at a dropping rate of 3 drops / second. After the dropwise addition was completed, the reaction was carried out at a constant temperature in an ice bath for 9 h. After the reaction was completed, the reaction was filtered under reduced pressure, rotary evaporated, and dried to obtain a substitution product of the reaction of chloropropyl-POSS and melamine.

[0033] (2) Add 15 mL of 20% formaldehyde aqueous solution, 2 g of boric acid, 2 g of the substitution product obtained in step (1) and 200 mL of tap water into a three-necked flask and stir evenly to obtain a reaction solution; immerse the lyocell fabric in the reaction solution, wherein the ratio of the lyocell fabric (g) to the reaction solution (mL) is 1:150, the temperature of the reaction solution is controlled to 50°C, and the immersion time is 15 minutes; after the reaction is completed, take out the lyocell fabric, wash it with tap water, and dry the lyocell fabric when the pH of the washing solution is 7 to obtain a flame-retardant lyocell fabric.

[0034] Comparative Example A

[0035] Taking Example 1 as a comparison, in this comparative example, the "6 g of chloropropyl-POSS" in step (1) was reduced to "0.6 g of chloropropyl-POSS", and the other preparation methods were implemented according to the preparation method of Example 1.

[0036] Comparative Example B

[0037] Taking Example 1 as a comparison, in this comparative example, the "5 g melamine" in step (1) was reduced to "0.5 g melamine", and the other preparation methods were implemented according to the preparation method of Example 1.

[0038] Comparative Example C

[0039] Taking Example 1 as a comparison, in this comparative example, in step (2), "12 mL of 15% formaldehyde aqueous solution by mass" is reduced to "1.2 mL of 15% formaldehyde aqueous solution by mass", and the other preparation methods are implemented according to the preparation method of Example 1.

[0040] Comparative Example D

[0041] Taking Example 1 as a comparison, in this comparative example, in step (2), "12 mL of 15% formaldehyde aqueous solution by mass" was increased to "120 mL of 15% formaldehyde aqueous solution by mass", and the other preparation methods were implemented according to the preparation method of Example 1.

[0042] Comparative Example E

[0043] Taking Example 1 as a comparison, in this comparative example, in step (2), "the usage ratio of the lyocell fabric (g) to the reaction liquid (mL) is: 1:100" is changed to "the usage ratio of the lyocell fabric (g) to the reaction liquid (mL) is: 1:1000", and the other preparation methods are implemented according to the preparation method of Example 1.

[0044] Comparative Example F

[0045] Taking Example 1 as a comparison, in this comparative example, in step (2), "the usage ratio of the lyocell fabric (g) to the reaction liquid (mL) is: 1:100" is changed to "the usage ratio of the lyocell fabric (g) to the reaction liquid (mL) is: 1:10", and the other preparation methods are implemented according to the preparation method of Example 1.

[0046] Performance evaluation example:

[0047] To better examine the flame retardancy of the lyocell fabrics prepared in the present invention, the flame retardancy of the lyocell fabrics prepared in Examples 1-3 and Comparative Examples A-F, as well as purchased flame-retardant lyocell fabrics, was tested using the oxygen index test method. The lyocell fabrics were subjected to a standard wash cycle according to GB / T 5454-1997, "Textiles - Test Method for Burning Behavior - Oxygen Index," and referenced to the machine wash procedure in GB / T 20944.1-2007, "Color Fastness to Washing Tester." The test results are shown in Table 1.

[0048] Table 1 Flame retardant test results of the lyocell fabrics prepared in Examples 1 to 3 and Comparative Examples A to F and the purchased lyocell fabrics before washing and after washing 5 times

[0049]

[0050]

[0051] The Limiting Oxygen Index (LOI) is a key indicator of flame-retardant materials. Generally, materials with an LOI greater than 28% are considered flame-retardant. As shown in Table 1, the initial LOI of the flame-retardant lyocell fabric prepared by the present invention reached over 30%, placing it within the range of flame-retardant materials. After five washes, the LOI did not significantly decrease, remaining above 28%. Before washing, the flame-retardant performance of the flame-retardant lyocell fabric prepared by the present invention was very close to that of a purchased flame-retardant lyocell fabric. After five washes, the flame-retardant performance of the flame-retardant lyocell fabric prepared by the present invention slightly exceeded that of the purchased flame-retardant lyocell fabric. Furthermore, the inventors of the present application further discovered that the LOIs of the lyocell fabrics prepared in Comparative Examples AF were all lower, indicating that the amount of chloropropyl-POSS, the amount of melamine, the amount of formaldehyde solution, and the ratio of fabric to reaction solution all have a significant impact on the flame-retardant properties of the lyocell fabric. The flame retardant performance test shows that the flame retardant lyocell fabric prepared by the present invention has a good flame retardant effect and is a qualified flame retardant lyocell fabric.

Claims

1. A method for preparing a flame retardant lyocell fabric, characterized in that: The preparation method is as follows: The method comprises immersing a lyocell fabric in a reaction solution, controlling the temperature of the reaction solution to be 40-50° C., and immersing the fabric for 10-15 minutes. After the reaction is completed, the lyocell fabric is taken out and washed with tap water. When the pH value of the washed solution reaches 6-7, the lyocell fabric is dried to obtain a flame-retardant lyocell fabric. The flame-retardant lyocell fabric has an initial limiting oxygen index greater than 30%, and after five washes, the limiting oxygen index is greater than 28%. The reaction solution is prepared by adding 10-15 mL of formaldehyde aqueous solution, 1-2 g of boric acid, 1-2 g of a substitution product of the reaction of chloropropyl-POSS and melamine, and 150-200 mL of tap water into a three-necked flask, and uniformly stirring to obtain the reaction solution.

2. The method for preparing a flame retardant lyocell fabric according to claim 1, wherein: The usage ratio of the lyocell fabric to the reaction solution is: 1g: (50-150)mL.

3. The method for preparing a flame retardant lyocell fabric according to claim 1, wherein: The mass fraction of the formaldehyde aqueous solution is 10-20%.

4. The method for preparing a flame retardant lyocell fabric according to claim 1, wherein: The preparation method of the substitution product of the reaction of chloropropyl-POSS and melamine comprises the following steps: dissolving 5-7 g of chloropropyl-POSS and 1-2 g of triethylamine in 150 mL of tetrahydrofuran in a four-necked flask, stirring in an ice bath and passing N2 protection, dissolving 4-6 g of melamine in 100 mL of tetrahydrofuran, and dropwise adding the melamine and triethylamine-dissolved tetrahydrofuran to the chloropropyl-POSS-dissolved tetrahydrofuran under stirring at a dropping rate of 1-3 drops / second. After the dropwise addition is completed, reacting in an ice bath at a constant temperature. After the reaction is completed, filtering under reduced pressure, rotary evaporation, and drying to obtain the substitution product of the reaction of chloropropyl-POSS and melamine.

5. The method for preparing a flame retardant lyocell fabric according to claim 4, wherein: The reaction time of the ice bath constant temperature reaction is 5 to 9 hours.

6. A flame retardant lyocell fabric, characterized in that: The flame-retardant lyocell fabric is prepared by the preparation method of any one of claims 1 to 5.

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