Flame-retardant lyocell fabric and method for producing the same

Abstract

This invention relates to a flame-retardant lyocell fabric and its preparation method. The fabric is characterized by being prepared by the following method: grinding zinc oxide (ZnO) powder to obtain nano-sized ZnO particles; reacting KH-570 with the ZnO particles to obtain a cross-linked modified nano-sized ZnO solution; and finally, reacting formaldehyde, the cross-linked modified nano-sized ZnO solution, and lyocell fabric to obtain the flame-retardant lyocell fabric. The flame-retardant lyocell fabric prepared by this invention has an initial limiting oxygen index (LOI) of over 31%, falling within the range of flame-retardant materials. After five washes, its LIO does not decrease significantly, remaining above 29%.

Description

Technical Field

[0001] This invention belongs to the field of fabric preparation technology, specifically relating to a flame-retardant lyocell fabric and its preparation method. Background Technology

[0002] With the gradual improvement of people's living standards, the booming of international exchanges and tourism, and the continuous expansion of transportation routes such as automobiles, ships, and airplanes, a wide range of applications are being provided for textiles. However, textiles are extremely flammable, and fires caused by them account for more than half of all fires each year. Therefore, how to reduce fires caused by textiles, explore flame-retardant textile technologies, and develop flame-retardant textiles has become an important current issue.

[0003] Lyocell fiber is a fiber produced using an organic solvent spinning method. In its manufacturing process, the organic solvent recovery rate reaches 99.7%. The chemical reactions during production are non-toxic, energy-saving, and environmentally friendly. Furthermore, the byproducts and waste generated during production can be directly utilized for biodegradation. The production process is very simple and does not require a large amount of energy. Lyocell fiber is generally divided into two types: one is fibrillated, which easily produces fibrillated fabrics; simply put, this characteristic can be used to create soft-touch imitations. The other is non-fibrillated, which is a fabric made by treating the fibrillated type to prevent the fibers from splitting into small fibers.

[0004] Lyocell fabric is made from lyocell fiber, a natural and eco-friendly fiber produced from pulp formed by crushing renewable bamboo and wood. It boasts a high organic solvent recovery rate, contributing to sustainable ecological development. Garments made from lyocell fiber not only have a natural luster, smooth feel, high strength, and minimal shrinkage, but also excellent moisture permeability and breathability, making it a good blend material with wool. The various properties of lyocell fiber make it particularly suitable for home textiles, high-end clothing sets, toys, and accessories. However, lyocell fiber remains a flammable textile material. Therefore, imparting excellent flame-retardant properties to lyocell fiber is an important research direction.

[0005] Literature review indicates that the flame-retardant properties of lyocell fabrics have received considerable attention both domestically and internationally. For example, Chinese invention patent application No. 201880064950.7 discloses a flame-retardant lyocell filament prepared by mixing a flame retardant containing nitrogen and phosphorus compounds with a fiber-free spinning solution, filtering the spinning solution, extruding it using a wet-dry method, and finally obtaining the desired flame-retardant lyocell filament through precipitation, washing, and drying. Chinese invention patent application No. 201811247384.1 discloses a method for preparing flame-retardant lyocell fibers, which involves dissolving the flame retardant tris(2,3-dibromopropyl) phosphate and cellulose simultaneously in the organic solvent NMMO, followed by spinning to prepare flame-retardant lyocell fibers. However, the flame retardant structures used in the above methods are relatively simple and cannot achieve a highly efficient synergistic flame-retardant effect. Therefore, it is necessary to improve the existing flame-retardant process for lyocell fabrics and develop a low-cost and simple preparation method to obtain lyocell fabrics with excellent flame-retardant properties. Summary of the Invention

[0006] In view of the above-mentioned drawbacks of the existing technology, the purpose of this invention is to provide a flame-retardant lyocell fabric and its preparation method.

[0007] The purpose of this invention is to provide a flame-retardant lyocell fabric, which can be prepared by the following method: grinding zinc oxide (ZnO) powder to obtain ZnO particles with a particle size of nanoscale; reacting KH-570 with ZnO particles to obtain a cross-linked modified nanoscale ZnO solution; and finally, reacting formaldehyde, the cross-linked modified nanoscale ZnO solution and lyocell fabric to obtain the flame-retardant lyocell fabric.

[0008] Another object of the present invention is to provide a method for preparing flame-retardant Lyocell fabric, the specific method comprising the following steps:

[0009] (1) ZnO powder is ground to obtain ZnO particles with a particle size of nanometers.

[0010] Preferably, the particle size range is 500–2000 nanometers.

[0011] (2) Dissolve KH-570 crosslinking agent in dimethylformamide; add the nano-sized ZnO obtained in step (1) to the dimethylformamide solution containing KH-570 crosslinking agent, stir and react, the reaction temperature is 60~80℃, the reaction time is 3~5h, and crosslinked modified nano-sized ZnO solution is obtained.

[0012] Preferably, the ratio of the amount of KH-570 crosslinking agent (g) to dimethylformamide (mL) is 1:100-200; the ratio of the amount of nano-sized ZnO (g) to dimethylformamide solution (mL) containing KH-570 crosslinking agent is 1:100-200.

[0013] (3) Dissolve the cross-linked modified nano-sized ZnO solution and azobisisobutyronitrile obtained in step (2) in an organic solvent and stir to prepare a finishing solution; heat the finishing solution to 90-100°C and immerse the Lyocell fabric in the finishing solution for 1-2 hours; take out the immersed Lyocell fabric, wash it with a large amount of tap water, and dry it to obtain flame-retardant Lyocell fabric.

[0014] Preferably, the organic solvent is dimethylformamide.

[0015] Preferably, the ratio of the amount of the cross-linked modified nano-sized ZnO solution (mL), azobisisobutyronitrile (g), and organic solvent (mL) obtained in step (2) is 1:0.01-0.02:10-20.

[0016] Preferably, the ratio of the Lyocell fabric (g) to the finishing solution (mL) is 1:20-40.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention realizes the grafting of ZnO nanoparticles on the surface of Lyocell fabric, which significantly improves the flame retardant properties of Lyocell fabric.

[0019] (2) The inventors of this application unexpectedly discovered that the initial limiting oxygen index of the flame-retardant Lyocell fabric prepared by the present invention reached more than 31%, which is within the range of flame-retardant materials; after 5 washes, its limiting oxygen index did not decrease significantly and still reached more than 29%; in addition, 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.

[0020] (3) The present invention prepared cross-linked modified nano-sized ZnO, and reacted it with Lyocell fabric through a chemical reaction; nano-sized ZnO is an excellent flame retardant material, thus the prepared Lyocell fabric also has excellent flame retardant properties.

[0021] (4) The inventors of this application unexpectedly discovered that the present invention can achieve a strong bond between the cross-linked modified nano-sized ZnO and Lyocell fabric by chemically reacting the two; further discovered that the flame retardant properties of Lyocell fabric are not weakened after multiple washes.

[0022] (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 environmental pollution. Detailed Implementation

[0023] Main raw material sources: KH-570 crosslinking agent (chemical name: γ-methacryloyloxypropyltrimethoxysilane) was purchased from Wuhan Hualun Organosilicon Co., Ltd.; flame-retardant Lyocell fabric was purchased from Xinxiang Zhuocheng Special Textile Co., Ltd.

[0024] The present invention is described in detail below with reference to the embodiments and comparative examples.

[0025] Example 1

[0026] This embodiment discloses a method for preparing flame-retardant Lyocell fabric, the method comprising the following steps:

[0027] (1) ZnO powder is ground to obtain ZnO particles with a particle size of 900 to 1500 nanometers.

[0028] (2) Dissolve 1g of KH-570 crosslinking agent in 150mL of dimethylformamide; add 1g of nano-sized ZnO obtained in step (1) to 150mL of dimethylformamide solution containing KH-570 crosslinking agent, stir and react, the reaction temperature is 70℃, the reaction time is 4h, and crosslinked modified nano-sized ZnO solution is obtained.

[0029] (3) Dissolve 100 mL of the cross-linked modified nano-sized ZnO solution obtained in step (2) and 1.5 g of azobisisobutyronitrile in 1500 mL of dimethylformamide and stir to prepare a finishing solution; heat the finishing solution to 95 °C and immerse the Lyocell fabric in the finishing solution for 1.5 hours. The ratio of Lyocell fabric (g) to finishing solution (mL) is 1:30; take out the immersed Lyocell fabric, wash it with a large amount of tap water, and dry it to obtain flame-retardant Lyocell fabric.

[0030] Example 2

[0031] This embodiment discloses a method for preparing flame-retardant Lyocell fabric, the method comprising the following steps:

[0032] (1) ZnO powder is ground to obtain ZnO particles with a particle size of 500 to 1000 nanometers.

[0033] (2) Dissolve 1g of KH-570 crosslinking agent in 150mL of dimethylformamide; add 1g of nano-sized ZnO obtained in step (1) to 100mL of dimethylformamide solution containing KH-570 crosslinking agent, stir and react, the reaction temperature is 60℃, the reaction time is 3h, and crosslinked modified nano-sized ZnO solution is obtained.

[0034] (3) Dissolve 100 mL of the cross-linked modified nano-sized ZnO solution obtained in step (2) and 1 g of azobisisobutyronitrile in 1000 mL of dimethylformamide and stir to prepare a finishing solution; heat the finishing solution to 90 °C and immerse the Lyocell fabric in the finishing solution for 1 hour. The ratio of Lyocell fabric (g) to finishing solution (mL) is 1:20; take out the immersed Lyocell fabric, wash it with a large amount of tap water, and dry it to obtain flame-retardant Lyocell fabric.

[0035] Example 3

[0036] This embodiment discloses a method for preparing flame-retardant Lyocell fabric, the method comprising the following steps:

[0037] (1) ZnO powder is ground to obtain ZnO particles with a particle size of nanometers, wherein the particle size range is 1500-2000 nanometers.

[0038] (2) Dissolve 1g of KH-570 crosslinking agent in 100mL of dimethylformamide; add 1g of nano-sized ZnO obtained in step (1) to 100mL of dimethylformamide solution containing KH-570 crosslinking agent, stir and react, the reaction temperature is 80℃, the reaction time is 5h, and crosslinked modified nano-sized ZnO solution is obtained.

[0039] (3) Dissolve 100 mL of the cross-linked modified nano-sized ZnO solution obtained in step (2) and 1 g of azobisisobutyronitrile in 2000 mL of dimethylformamide and stir to prepare a finishing solution; heat the finishing solution to 100 °C and immerse the Lyocell fabric in the finishing solution for 2 hours. The ratio of Lyocell fabric (g) to finishing solution (mL) is 1:40; take out the immersed Lyocell fabric, wash it with a large amount of tap water, and dry it to obtain flame-retardant Lyocell fabric.

[0040] Comparative Example A

[0041] Compared with Example 1, in this comparative example, the "1g KH-570 crosslinking agent" in step (2) was reduced to "0.1g KH-570 crosslinking agent", and other preparation methods were carried out according to the preparation method of Example 1.

[0042] Comparative Example B

[0043] Compared with Example 1, in this comparative example, the "1g KH-570 crosslinking agent" in step (2) was increased to "5g KH-570 crosslinking agent", and other preparation methods were carried out according to the preparation method of Example 1.

[0044] Comparative Example C

[0045] Compared with Example 1, in this comparative example, in step (2), "1g of nano-sized ZnO obtained in step (1)" was reduced to "0.1g of nano-sized ZnO obtained in step (1)", and other preparation methods were carried out according to the preparation method of Example 1.

[0046] Comparative Example D

[0047] Compared with Example 1, in this comparative example, in step (2), "1g of nano-sized ZnO obtained in step (1)" was increased to "5g of nano-sized ZnO obtained in step (1)," and other preparation methods were carried out according to the preparation method of Example 1.

[0048] Comparative Example E

[0049] Compared with Example 1, in this comparative example, in step (3), the ratio of the amount of Lyocell fabric (g) to the finishing solution (mL) is changed to the ratio of the amount of Lyocell fabric (g) to the finishing solution (mL) is 1:400, and the other preparation methods are carried out according to the preparation method of Example 1.

[0050] Comparative Example F

[0051] Compared with Example 1, in this comparative example, in step (2), the ratio of the amount of Lyocell fabric (g) to the finishing solution (mL) is changed to "the ratio of the amount of Lyocell fabric (g) to the finishing solution (mL) is 1:40", and the other preparation methods are carried out according to the preparation method of Example 1.

[0052] Performance evaluation example:

[0053] To better test the flame retardancy of the lyocell fabric prepared in this invention, the flame retardant properties of the lyocell fabrics prepared in the specific embodiments 1-3 and comparative examples A-F of this invention, as well as the purchased flame-retardant lyocell fabrics, were tested. The test method adopted was the oxygen index test method, that is, according to GB / T 5454-1997 "Textiles - Test for Burning Performance - Oxygen Index Method", the lyocell fabric was subjected to standard washing according to the washing method of GB / T 20944.1-2007 "Test for Color Fastness to Wash". The test results are shown in Table 1.

[0054] Table 1. Flame retardancy test results of Lyocell fabrics prepared in Examples 1-3 and Comparative Examples A-F, and purchased Lyocell fabrics after unwashed and after 5 washes.

[0055]

[0056] Limiting Oxygen Index (LOI) is one of the important indicators 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 this invention reached over 31%, falling within the range of flame-retardant materials. After five washes, its LOI did not decrease significantly, remaining above 29%. Whether unwashed or after five washes, the flame-retardant performance of the flame-retardant Lyocell fabric prepared by this invention was slightly higher than that of purchased flame-retardant Lyocell fabric. Furthermore, the inventors of this application further discovered that the LOI of the Lyocell fabric prepared in Comparative Example AF was relatively low, indicating that the amount of KH-570 crosslinking agent, the amount of nano-sized ZnO, and the ratio of Lyocell fabric to finishing liquid all have a significant impact on the flame-retardant performance of the Lyocell fabric. Flame-retardant performance tests show that the flame-retardant Lyocell fabric prepared by this invention has excellent flame-retardant effects and is a qualified flame-retardant Lyocell fabric.

Claims

1. A method for preparing flame-retardant Lyocell fabric, characterized in that, The preparation method is as follows: A finishing solution was prepared by dissolving cross-linked modified nano-sized ZnO solution and azobisisobutyronitrile in an organic solvent and stirring. The finishing solution was heated to 90-100°C, and lyocell fabric was immersed in the finishing solution for 1-2 hours. The immersed lyocell fabric was then removed, washed with plenty of tap water, and dried to obtain flame-retardant lyocell fabric. The initial limiting oxygen index of the flame-retardant lyocell fabric was higher than 31%, and after five washes, its limiting oxygen index was higher than 29%. The ratio of Lyocell fabric to finishing solution is 1g:(20-40)mL; The preparation method of the crosslinked modified nano-sized ZnO solution is as follows: KH-570 crosslinking agent is dissolved in dimethylformamide; nano-sized ZnO is added to the dimethylformamide solution containing KH-570 crosslinking agent, and the mixture is stirred and reacted. The reaction temperature is 60-80℃ and the reaction time is 3-5h to obtain the crosslinked modified nano-sized ZnO solution. The ratio of KH-570 crosslinking agent to dimethylformamide is 1g:(100-200)mL.

2. The method for preparing a flame-retardant Lyocell fabric according to claim 1, characterized in that, The organic solvent is dimethylformamide.

3. The method for preparing a flame-retardant Lyocell fabric according to claim 1, characterized in that, The ratio of the cross-linked modified nano-sized ZnO solution, azobisisobutyronitrile, and organic solvent is 1 mL : (0.01-0.02) g : (10-20) mL.

4. The method for preparing a flame-retardant Lyocell fabric according to claim 1, characterized in that, The ratio of the amount of nano-sized ZnO to the dimethylformamide solution containing KH-570 crosslinking agent is 1 g : (100-200) mL.

5. The method for preparing a flame-retardant Lyocell fabric according to claim 1, characterized in that, The method for preparing the nano-sized ZnO is as follows: ZnO powder is ground to obtain ZnO particles with a particle size of nanometers.

6. The method for preparing a flame-retardant Lyocell fabric according to claim 5, characterized in that, The particle size range is 500–2000 nanometers.

7. A flame-retardant Lyocell fabric, characterized in that, It is prepared by the method of any one of claims 1 to 6 for preparing a flame-retardant lyocell fabric.

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