Preparation method of an antibacterial lyocell fiber

Abstract

The present invention discloses a preparation method of antibacterial lyocell fiber, belonging to the field of functional cellulose fibers, and comprising the following steps: dissolution of cellulose quaternary ammonium salt, premixing of cellulose pulp raw materials, preparation of spinning dope, and preparation of lyocell antibacterial fiber. In the present invention, cellulose quaternary ammonium salt is first added to the NMMO solvent for dissolution, and then cellulose pulp is dissolved. This not only does not affect the dissolution of cellulose itself, but also ensures that a spinning dope with uniform, stable and good spinnability can be obtained, which is beneficial to the subsequent spinning process. The method of the present invention can effectively improve the antibacterial property of lyocell fiber and can also reduce the fibrillation degree of lyocell fiber to a certain extent; the method of the present invention is to add an antibacterial agent to the spinning dope, so the antibacterial agent will be uniformly dispersed inside and on the surface of the fiber, and long-term antibacterial can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional cellulose fibers, and particularly to a preparation method of antibacterial Lyocell fibers. Background Art

[0002] Lyocell fibers are regenerated cellulose fibers prepared by dissolving cellulose with an aqueous solution of N-methylmorpholine-N-oxide (NMMO) and then through a dry-jet wet spinning process. Compared with traditional cellulose fibers such as viscose fibers, the production process of Lyocell fibers is green and environmentally friendly, without any toxic chemical reactions occurring, and the fibers have more excellent mechanical properties. In recent years, the global market demand for Lyocell fibers has been increasing year by year.

[0003] In order to further expand the application fields of Lyocell fibers in downstream industries, the development of differentiated and functional Lyocell fibers has received extensive attention. Since Lyocell fibers, like ordinary viscose fibers, are composed of cellulose, they are also prone to bacterial growth, which greatly limits the application of Lyocell fibers in the field of back-end clothing fabrics. Therefore, endowing Lyocell fibers with excellent antibacterial properties is one of the key points that people widely focus on.

[0004] Currently, there are mainly two methods for preparing antibacterial cellulose regenerated fibers:

[0005] One is: adding an antibacterial agent to the spinning dope, and antibacterial fibers can be obtained simultaneously during the spinning and forming process. For example, in Chinese Patent Application CN114134597A, a modified latex is added to the spinning dope to endow the fibers with the natural antibacterial properties and high elasticity of the latex, and it can also reduce the fibrillation degree of Lyocell fibers. Another example is Chinese Patent Application CN115787120A, where a phosphorylated soy protein solution is added to the spinning solution of Lyocell fiber raw materials to endow the Lyocell fibers with better antibacterial properties and mechanical properties. Another example is CN105177746A, where nano-ZnO is used as an antibacterial agent, which is surface-modified and then mixed with the NMMO solution, and then cellulose pulp is dissolved, and finally antibacterial Lyocell fibers are prepared by spinning. However, the addition of nano-ZnO may affect the uniformity of the spinning dope, resulting in easy blockage during the subsequent filtration of the spinning dope. In addition, ZnO may also catalyze the decomposition of cellulose and NMMO, leading to risks such as explosion.

[0006] Second: After the fiber is formed, it is subjected to antibacterial post-treatment, and an antibacterial agent is adsorbed or wrapped on the surface of the fiber, such as Chinese patent applications CN114790656A, CN115142260A, CN114150505A, etc. However, the antibacterial effect imparted to the fiber by the post-treatment method often cannot be maintained for a long time (for example, after washing 20 times in CN114790656A and 10 times in CN115142260A, the antibacterial performance gradually decreases); another example is CN109983172A, where the cellulose solution is spun into a regeneration bath through a spinneret to obtain regenerated cellulose fibers. After washing the cellulose fibers, they are treated with a quaternary ammonium compound solution to obtain antibacterial Lyocell fibers. However, the inventors of this application found through experiments that the method of this patent is to wrap the quaternary ammonium compound on the fiber surface, which will lead to a decrease in the biocompatibility of the fiber and damage its original biological properties; moreover, the antibacterial component in the antibacterial Lyocell fibers prepared by the above method is combined on the surface of the fiber and is easily shed during washing. Therefore, a long-term antibacterial effect cannot be achieved after multiple washes, and the post-treatment process will greatly increase the production cost and production cycle. Therefore, the best way to achieve long-term antibacterial is to add an antibacterial agent to the spinning dope to prepare antibacterial fibers.

[0007] However, directly adding an antibacterial agent to the spinning dope may affect the dissolution of cellulose in NMMO, thereby affecting the uniformity and spinnability of the spinning dope, causing difficulties in subsequent spinning, and even possibly exacerbating the decomposition of NMMO and cellulose. Summary of the Invention

[0008] The object of the present invention is to provide a method for preparing antibacterial Lyocell fibers to solve the above problems.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing antibacterial Lyocell fibers, comprising the following steps:

[0010] (1) Dissolution of cellulose quaternary ammonium salt

[0011] Mix the cellulose quaternary ammonium salt with an NMMO aqueous solution having a concentration of 70-78 wt% and stir to dissolve.

[0012] (2) Premixing of cellulose pulp raw materials

[0013] Premix the pretreated cellulose pulp raw materials with the NMMO aqueous solution in which the cellulose quaternary ammonium salt is dissolved in step (1) to obtain a premixed pulp porridge.

[0014] (3) Preparation of spinning dope

[0015] Transfer the premixed slurry in step (2) to a dissolving device for vacuum dehydration and dissolution to obtain a solution with a cellulose concentration of 12-13 wt%.

[0016] (4) Preparation of Lyocell antibacterial fiber

[0017] After the spinning dope is spun and formed through a coagulation bath, Lyocell antibacterial fiber is obtained.

[0018] In the preparation process of the spinning dope of the present invention, a cellulose quaternary ammonium salt is added. The cellulose quaternary ammonium salt of this application belongs to a natural modified antibacterial agent, and its addition will not affect the biocompatibility of the fiber itself. The cellulose quaternary ammonium salt used in the present invention is a derivative after chemical modification of cellulose, and quaternary ammonium groups are grafted onto the cellulose molecular chain by the existing technology. Therefore, it itself has characteristics such as natural biocompatibility like cellulose. Introducing it into Lyocell fiber will not affect the biocompatibility of the fiber and will not affect the biological properties of the fiber itself.

[0019] As a preferred technical solution:

[0020] In step (1), the cellulose quaternary ammonium salt is 2-hydroxy-3-(trimethylammonio)propyl poly(ethylene oxide) cellulose chloride. 2-hydroxy-3-(trimethylammonio)propyl poly(ethylene oxide) cellulose chloride has a relatively high synthesis yield and low cost. It is also a commercially available cellulose quaternary ammonium salt and is easily obtained.

[0021] As a further preferred technical solution:

[0022] The addition amount of the cellulose quaternary ammonium salt is 0.01-0.2 wt%.

[0023] As a preferred technical solution:

[0024] In step (1), the dissolution temperature is 70-100 °C.

[0025] As a preferred technical solution:

[0026] In step (2), the addition amount of the cellulose pulp raw material is 10-11.5 wt% of the NMMO aqueous solution in which the cellulose quaternary ammonium salt is dissolved in step (1).

[0027] As a preferred technical solution:

[0028] In step (2), the premixing temperature is 70-80 °C.

[0029] As a preferred technical solution:

[0030] In step (4), the coagulation bath is a 15-20 wt% NMMO solution, and the coagulation bath temperature is 20-30 °C.

[0031] As a preferred technical solution:

[0032] In step (4), the spinning speed is 30 - 40 m / min.

[0033] As a preferred technical solution:

[0034] In step (4), during the spinning process, the air gap of the spinneret is 15 - 30 mm, the side blow air speed is 10 - 15 m / s, the humidity is 5 - 20 g / kg (water / air), and the temperature is 15 - 20 °C.

[0035] Compared with the prior art, the advantages of the present invention are as follows:

[0036] (1) In the present invention, cellulose quaternary ammonium salt is first added to the NMMO solvent for dissolution, and then the cellulose pulp is dissolved. This not only does not affect the dissolution of cellulose itself, but also can ensure that a spinning dope with good uniformity, stability and spinnability is obtained. As shown in Table 2 below, the better the spinnability, the better the quality of the spinning solution, which also indicates that the spinning solution is uniform and stable, facilitating the subsequent spinning process;

[0037] (2) The method of the present invention can effectively improve the antibacterial property of Lyocell fiber, and can also reduce the fibrillation degree of Lyocell fiber to a certain extent, improving the anti-fibrillation effect of the fiber;

[0038] (3) The method of the present invention adds an antibacterial agent to the spinning dope. Therefore, the antibacterial agent will be uniformly dispersed inside and on the surface of the fiber, achieving long-term antibacterial. Specific embodiments

[0039] The present invention will be further described below in conjunction with embodiments.

[0040] Embodiment 1

[0041] This embodiment provides a method for preparing antibacterial Lyocell fiber, including the following steps:

[0042] (1) Dissolution of cellulose quaternary ammonium salt

[0043] The cellulose quaternary ammonium salt is mixed with an NMMO aqueous solution with a concentration of 75 wt% and stirred for dissolution.

[0044] The addition amount of the cellulose quaternary ammonium salt is 0.05 wt%, and the dissolution temperature is 80 °C.

[0045] (2) Premixing of cellulose pulp raw materials

[0046] The pretreated cellulose pulp raw materials are premixed with the NMMO aqueous solution in which the cellulose quaternary ammonium salt is dissolved in step (1) to obtain a premixed pulp porridge.

[0047] The addition amount of the cellulose pulp raw material is 10.8 wt%, and the premixing temperature is 80 °C.

[0048] (3) Preparation of spinning dope

[0049] The premixed pulp slurry in step (2) is transported to a dissolving device for vacuum dehydration and dissolution to obtain a solution with a cellulose concentration of 12.3 wt%.

[0050] (4) Preparation of Lyocell antibacterial fiber

[0051] After the spinning dope is finally formed in a coagulation bath by dry-jet wet spinning, it is then washed, cut, oiled, and dried to obtain Lyocell antibacterial fiber;

[0052] Among them, the air gap of the spinneret is 20 mm, the side blow air velocity is 15 m / s, the humidity is 15 g / kg (water / air), and the temperature is 20 °C;

[0053] The coagulation bath is a 18 wt% NMMO solution, the coagulation bath temperature is 22 °C, and the spinning speed is 34 m / min.

[0054] Example 2

[0055] Based on Example 1, the difference between this example and Example 1 is that the addition amount of the cellulose quaternary ammonium salt is 0.1 wt%. Other process conditions and equipment used are the same as those in Example 1 and will not be elaborated here.

[0056] Example 3

[0057] Based on Example 1, the difference between this example and Example 1 is that the addition amount of the cellulose quaternary ammonium salt is 0.2 wt%. Other process conditions and equipment used are the same as those in Example 1 and will not be elaborated here.

[0058] Comparative Example 1

[0059] Based on Example 1, the difference between this comparative example and Example 1 is that the cellulose quaternary ammonium salt is not added to the spinning dope. Other process conditions and equipment used are the same as those in Example 1 and will not be elaborated here.

[0060] Comparative Example 2

[0061] Based on Example 1, the difference between this comparative example and Example 1 is that the cellulose quaternary ammonium salt is not pre-dissolved in a 75 wt% NMMO aqueous solution, but is added to the NMMO aqueous solution together with the cellulose pulp raw material for premixing, and the addition amounts of the cellulose quaternary ammonium salt and the cellulose pulp raw material remain unchanged. Other process conditions and equipment used are the same as those in Example 1 and will not be elaborated here.

[0062] Comparative Example 3

[0063] On the basis of Example 3, the difference between this comparative example and Example 3 is that the cellulose quaternary ammonium salt was not dissolved in the 75 wt% NMMO aqueous solution in advance, but was added together with the cellulose pulp raw material into the NMMO aqueous solution for premixing, and the addition amounts of the cellulose quaternary ammonium salt and the cellulose pulp raw material remained unchanged. Other process conditions and equipment used were the same as those in Example 1 and will not be elaborated here.

[0064] Comparative Example 4

[0065] On the basis of Comparative Example 1, the difference between this comparative example and Comparative Example 1 is that the washed Lyocell fiber was treated with a 0.05 wt% aqueous solution of cellulose quaternary ammonium salt by padding, the padding time was 15 min, and the temperature of the cellulose quaternary ammonium salt aqueous solution was 25 °C. Finally, the Lyocell antibacterial fiber was obtained after cutting, oiling, and drying.

[0066] The antibacterial properties and wet abrasion values of the Lyocell fibers prepared in the above different examples and comparative examples were tested.

[0067] Among them, the test method for the antibacterial properties referred to FZ / T 73023-2006;

[0068] The test method for the wet abrasion value was determined by using a DELTA 100 wet abrasion tester (for this equipment, see http: / / 16812585.s21d-16.faiusrd.com / 61 / ABUIABA9GAAgp56Z8gUo-Kne5wY.pdf);

[0069] The results are shown in Table 1.

[0070] Table 1 Test results of antibacterial properties and wet abrasion values of Lyocell fibers in different examples and comparative examples

[0071]

[0072]

[0073] The spinnability of the Lyocell fibers prepared in the above different examples and comparative examples was evaluated and the relevant mechanical property indexes were tested, and the results are shown in Table 2.

[0074] Table 2 Test results of spinnability and finished fiber properties of Lyocell fibers in different examples and comparative examples

[0075]

[0076] The prepared Lyocell fibers in the above different examples and comparative examples were washed 10 times and 20 times respectively, and then redried, and the antibacterial properties were tested according to the same method. The results are shown in Table 3.

[0077] Table 3 Antibacterial property test results of Lyocell fibers in different examples and comparative examples after being washed 10 times and 20 times

[0078]

[0079]

[0080] The following conclusions can be drawn from the above results:

[0081] (1) By comparing Examples 1-3 and Comparative Example 1, it can be seen that: ① The addition of cellulose quaternary ammonium salt can effectively improve the antibacterial property of the fiber, and the higher the addition amount of cellulose quaternary ammonium salt, the better the antibacterial property of the finally obtained fiber; ② The addition of cellulose quaternary ammonium salt can effectively improve the fibrillation resistance effect of the fiber, and the higher the addition amount of cellulose quaternary ammonium salt, the better the fibrillation resistance effect of the finally obtained fiber; ③ The addition of cellulose quaternary ammonium salt will cause the dry breaking strength, wet breaking strength and dry breaking elongation of the fiber to decrease, and the higher the addition amount of cellulose quaternary ammonium salt, the more the dry breaking strength, wet breaking strength and dry breaking elongation of the fiber decrease. When the addition amount of cellulose quaternary ammonium salt is 0.2 wt%, the dry breaking strength of the Lyocell antibacterial fiber is 3.51 cN / dtex, and the wet breaking strength is 3.04 cN / dtex, both of which are higher than the standard of qualified products in the Lyocell staple fiber industry standard (FZT 52019-2018).

[0082] (2) By comparing Examples 1, 3 and Comparative Examples 2, 3, it can be seen that: Compared with adding cellulose quaternary ammonium salt and cellulose pulp raw materials together to the NMMO aqueous solution for premixing to prepare the spinning solution, it is better to dissolve the cellulose quaternary ammonium salt in the NMMO aqueous solution first and then add the cellulose pulp raw materials for premixing to prepare the spinning solution with better quality. During the spinning process, it is not easy to occur filament splitting and filament breaking, and it has better spinnability. The greater the addition amount of cellulose quaternary ammonium salt, the greater the impact on spinnability. This is because when cellulose quaternary ammonium salt and cellulose pulp raw materials are added to the NMMO aqueous solution together, the cellulose quaternary ammonium salt will dissolve first, and the dissolved cellulose quaternary ammonium salt will wrap on the surface of the cellulose pulp, thus hindering the penetration of the solvent and affecting the swelling and dissolution of the cellulose pulp.

[0083] (3) It can be seen from the comparison between Example 1 and Comparative Example 4 that: ① The antibacterial effect of the antibacterial fiber prepared by adding cellulose quaternary ammonium salt to the spinning solution is better than that of introducing cellulose quaternary ammonium salt during the post-treatment process. This is because adding cellulose quaternary ammonium salt to the spinning solution can make the cellulose quaternary ammonium salt evenly disperse inside and on the surface of the formed fiber, without causing waste of cellulose quaternary ammonium salt. However, when introducing quaternary ammonium salt during the post-treatment process, the cellulose quaternary ammonium salt can only be dispersed on the surface of the formed fiber, and the cellulose quaternary ammonium salt cannot be fully adsorbed / adhered to the fiber surface, resulting in low utilization rate of fiber quaternary ammonium salt and thus reducing the antibacterial effect; ② The antibacterial effect of the antibacterial fiber prepared by adding cellulose quaternary ammonium salt to the spinning solution can be maintained for a long time. After being washed many times with water, it still has good antibacterial properties. However, for the antibacterial fiber prepared by introducing cellulose quaternary ammonium salt through post-treatment, the antibacterial property decreases significantly after being washed many times with water and cannot be maintained for a long time. This is because the cellulose quaternary ammonium salt adhered to the fiber surface during the post-treatment will continuously fall off during the water washing process, resulting in a decrease in the antibacterial effect.

[0084] The above are the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of antibacterial Lyocell fiber, characterized in that, It includes the following steps: (1) Dissolution of cellulose quaternary ammonium salt Mix the cellulose quaternary ammonium salt with an NMMO aqueous solution with a concentration of 70 - 78 wt% and stir to dissolve; (2) Premixing of cellulose pulp raw materials Premix the pretreated cellulose pulp raw materials with the NMMO aqueous solution in which the cellulose quaternary ammonium salt is dissolved in step (1) to obtain a premixed pulp porridge; (3) Preparation of spinning dope Transport the premixed pulp porridge in step (2) to a dissolution device for vacuum dehydration and dissolution to obtain a solution with a cellulose concentration of 12 - 13 wt%; (4) Preparation of Lyocell antibacterial fiber After the spinning dope is spun and formed through a coagulation bath, Lyocell antibacterial fiber is obtained; In step (1), the cellulose quaternary ammonium salt is 2 - hydroxy - 3 - (trimethylammonio)propyl cellulose ether chloride; In step (1), the dissolution temperature is 70 - 100 °C; In step (2), the premixing temperature is 70 - 80 °C.

2. The preparation method of the antibacterial lyocell fiber according to claim 1, characterized in that: The addition amount of the cellulose quaternary ammonium salt is 0.01 - 0.2 wt%.

3. The method for preparing antibacterial Lyocell fiber according to claim 1, wherein: In step (2), the addition amount of the cellulose pulp raw materials is 10 - 11.5 wt% of the NMMO water solution in which the cellulose quaternary ammonium salt is dissolved in step (1).

4. The method for preparing antibacterial Lyocell fiber according to claim 1, wherein: In step (4), the coagulation bath is a 15 - 20 wt% NMMO solution, and the coagulation bath temperature is 20 - 30 °C.

5. The method for preparing antibacterial Lyocell fiber according to claim 1, wherein: In step (4), the spinning speed is 30 - 40 m / min.

6. The method for preparing antibacterial Lyocell fiber according to claim 1, wherein: In step (4), during the spinning process, the air gap of the spinneret is 15 - 30 mm, the side blowing wind speed is 10 - 15 m / s, the humidity is 5 - 20 g / kg, and the temperature is 15 - 20 °C.

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