Method for preparing lyocell fibrillated fibers and use thereof

Abstract

The application provides a preparation method of lyocell fibrillated fiber, and specifically comprises the following steps: S1, adding lyocell cut fibers into water to control the concentration to be 2-4%, and dispersing the lyocell cut fibers by using a pulper; S2, filtering water from the dispersed pulp by using a filter press to obtain 10-30% high-concentration pulp, and conveying the high-concentration pulp to a group of high-concentration pulping machines by using a screw feeder to perform pulping, so as to obtain pulp 1 with a beating degree of 40-50°SR; S3, diluting the pulp 1 to a concentration of 1-3% by adding water, and performing beating and defibration by using a high-frequency defibrator, and repeatedly performing beating and defibration by using the high-speed hydraulic shearing effect of the high-frequency defibrator, so as to obtain lyocell fibrillated fiber with a beating degree of 75-95°SR. The lyocell fibrillated fiber can obtain a larger length and a lower fine fiber component by fully utilizing the friction force between fibers and the hydraulic shearing effect, a large number of fibrils can be obtained, and the lyocell fiber can be fully fibrillated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulp and papermaking, and in particular to a preparation method of Tencel fibrillated fiber and application thereof. BACKGROUND

[0002] Tencel fiber is extremely sensitive to water, and water can reduce the density of the amorphous region of Tencel fiber, providing space for polymer chain segment movement. A large number of fibrils can be obtained under water wetting and lower mechanical action. The diameter of Tencel fibrillated fiber is mainly several hundred nanometers, and the cross section of the fibril is circular, so that the prepared membrane has smaller pore size and higher porosity, and has excellent isolation performance and fast ion transmission performance, and is an optimal fiber material for battery and capacitor separators. The fibrillation process of Tencel fiber is a process in which fibrils are continuously peeled off from the main fiber. In order to obtain fibers with high fibrillation degree, it is necessary to use strong external force to make the fibrils peel off from the main fiber.

[0003] A Chinese patent with publication number CN101381898A proposes a method of using a pretreatment agent to pretreat cut fibers, and then using a grinding equipment to grind the fibers to obtain fibrillated fibers, which can be used for battery separators. This method increases the swelling degree of Tencel fiber, and the Tencel fiber is fibrillated under relatively low mechanical shear force. The patent with publication number CN109267415A proposes using a non-metal double-disc grinder to beat the Tencel fiber, and the mechanical shear force of the non-metal grinding plate is weak, which can reduce fiber cutting and improve the strength of the supercapacitor separator paper. However, in the above-mentioned patents, the Tencel fiber is ground at a relatively low concentration, and the mechanical shear of the grinding plate directly acts on the fiber, which is easy to cut the fiber, reduce the length of the fiber, increase the proportion of fine fiber components, and the strength of the obtained separator is low, and it is difficult to achieve sufficient fibrillation. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a preparation method of Tencel fibrillated fiber, which fully utilizes the friction between fibers and the hydrodynamic shear effect under high concentration, and avoids cutting the fibers as much as possible, so that the Tencel fibrillated fiber can have a larger length and a lower fine fiber component, and then a high-speed hydrodynamic shear effect of a high-frequency defibrator can be used to obtain a large amount of fibrils, and achieve sufficient fibrillation of Tencel fiber.

[0005] To achieve the above technical solutions, the present application provides a preparation method of Tencel fibrillated fiber, which specifically includes the following steps:

[0006] S1, adding Tencel cut fibers into water to control the concentration to be 2-4%, and dispersing the Tencel cut fibers by using a pulper;

[0007] S2, the dispersed pulp is pressed out of water by a filter press to obtain a high consistency pulp of 10-30%, and the high consistency pulp is conveyed to a group of high consistency refiners by a screw feeder to be refined, to obtain a pulp 1 with a beating degree of 40-50°SR;

[0008] S3, the pulp 1 is diluted to a consistency of 1-3% by adding water, and is subjected to low consistency beating and defibration by a high frequency defibrator, and is repeatedly beaten and defibrated by high speed hydrodynamic shearing of the high frequency defibrator to obtain a tencel fibrillated fiber with a beating degree of 75-95°SR.

[0009] In the above technical solution, the tencel fiber is first refined at a high consistency of 10-30%, the high consistency refining can fully utilize the friction between fibers to realize internal fibrillation of the fiber, and the fiber length is appropriately reduced to obtain the pulp 1. Under the action of the friction between fibers, the fiber of the pulp 1 mainly undergoes internal fibrillation, and the structure between the internal macrofibrils becomes loose. Then, the pulp 1 is subjected to high speed hydrodynamic shearing of the high frequency defibrator to fully shear and peel off the internal fibrillation of the fiber, and a large amount of fibrils can be obtained.

[0010] Preferably, the tencel short-cut fiber is a solvent-spun regenerated cellulose fiber, which is extremely sensitive to water, and high consistency refining after full swelling is more likely to realize internal fibrillation of the fiber, and more fibrils can be obtained through high speed hydrodynamic shearing of the high frequency defibrator.

[0011] Preferably, the high consistency refining equipment is one of a disc refiner, a conical refiner and a cylindrical refiner.

[0012] Preferably, the high frequency defibrator is adjustable in speed, and different degrees of hydrodynamic shearing force can be obtained between two refining plates by changing the speed, to facilitate adjustment of the hydrodynamic shearing force and obtain more shearing effect.

[0013] The application also provides an application of the tencel fibrillated fiber, and the fibrillated fiber prepared by the method is applied to a battery separator or a capacitor separator.

[0014] The tencel fibrillated fiber preparation method and device provided by the application have the beneficial effects that the application fully utilizes the friction between fibers and hydrodynamic shearing, high consistency refining can fully utilize the friction between fibers to realize internal fibrillation of the fiber, and cutting treatment of the fiber is avoided as much as possible, so that the tencel fibrillated fiber can have a larger length and a lower fine fiber component, and then high speed hydrodynamic shearing of the high frequency defibrator can obtain a large amount of fibrils to realize sufficient fibrillation of the tencel fiber. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a process flow diagram of the application. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0017] Embodiment 1

[0018] A fibrillated fiber is prepared by the following operation steps:

[0019] (1) Cut Tencel fibers (regenerated cellulose fibers produced by solvent spinning, length 4 mm, diameter 12 μm) are added into water to control the concentration to be 3%, and the cut Tencel fibers are dispersed by a pulper for 10 min. The dispersed pulp is pressed by a filter press to remove water to obtain a high-concentration pulp of 10%, and the high-concentration pulp is conveyed by a screw feeder to a group of high-concentration pulping machines for pulping, with a pulping power of 150 kW, to obtain pulp 1 with a beating degree of 40°SR.

[0020] (2) The pulp 1 is diluted with water to a concentration of 2%, and is subjected to high-frequency defibration at a high speed of 3000 r / min by a high-frequency defibrator to obtain Tencel fibrillated fibers with a beating degree of 75°SR.

[0021] Embodiment 2

[0022] A fibrillated fiber is prepared by the following operation steps:

[0023] (1) Cut Tencel fibers (regenerated cellulose fibers produced by solvent spinning, length 4 mm, diameter 12 μm) are added into water to control the concentration to be 3%, and the cut Tencel fibers are dispersed by a pulper for 10 min. The dispersed pulp is pressed by a filter press to remove water to obtain a high-concentration pulp of 20%, and the high-concentration pulp is conveyed by a screw feeder to a group of high-concentration pulping machines for pulping, with a pulping power of 150 kW, to obtain pulp 1 with a beating degree of 45°SR.

[0024] (2) The pulp 1 is diluted with water to a concentration of 2%, and is subjected to high-frequency defibration at a high speed of 3000 r / min by a high-frequency defibrator to obtain Tencel fibrillated fibers with a beating degree of 85°SR.

[0025] Embodiment 3

[0026] A fibrillated fiber is prepared by the following operation steps:

[0027] (1) The Tencel short-cut fibers (length 4 mm, diameter 12 μm) were added into water to control the concentration to be 3%, and the Tencel short-cut fibers were dispersed for 10 min by using a pulper. The dispersed pulp was pressed to remove water by a filter press to obtain a high consistency pulp with a consistency of 30%. The high consistency pulp was conveyed to a group of high consistency refiners by a screw feeder, and was refined at a refining power of 150 kW to obtain a pulp 1 with a beating degree of 50°SR.

[0028] (2) The pulp 1 was diluted to a consistency of 2% by adding water, and was treated by high frequency defibrator at a speed of 3000 r / min to obtain Tencel fibrillated fibers with a beating degree of 95°SR.

[0029] Comparative Example 1

[0030] A kind of fibrillated fiber was prepared by the following method:

[0031] The Tencel short-cut fibers (length 4 mm, diameter 12 μm) were added into water to control the concentration to be 4%, and were refined by a group of disc refiner at a refining power of 350 kW to obtain fibrillated fibers with a beating degree of 85°SR.

[0032] Performance test of fibrillated fibers

[0033] The fibrillated fibers prepared in Examples 1-3 and Comparative Example 1 were tested for performance, and the test items and methods were as follows:

[0034] 1. Fiber length: 300 mg of absolute dry fibers were added to 10 L of water for stirring, and 1 L of the above pulp was used to measure the fiber length of the Tencel fibrillated fibers by using a Morfi fiber analyzer.

[0035] 2. Fine fiber component: 0.5 g of absolute dry fibers were added to 500 ml of water, and after dilution, the pulp was stirred at a speed of 750 rpm for 30 s and then filtered. The fibers retained on a 200 mesh screen were dried and weighed as G. The fine fiber component was calculated according to the formula (0.5-G) / 0.5x100%.

[0036] Table 1 Performance test parameters of Tencel fibrillated fibers of the present application

[0037] Number Fiber length mmm Fine fiber component % Example 1 1.37 24 Example 2 1.45 22 Example 3 1.51 19 Comparative Example 1 0.76 32

[0038] As shown in Table 1, the length of the Tencel fibrillated fiber obtained after the Tencel short-cut fiber is treated by high consistency refining and high frequency defibrator in Examples 1-3 of the present application is above 1.3 mm, and the fine fiber component is below 24%. In Comparative Example 1, only refining is used, the length of the Tencel fibrillated fiber is 0.76 mm, and the fine fiber component is 32%. From the above experimental data, it can be seen that high consistency refining can make full use of the friction between fibers to realize the fibrillation of the fibers inside, and avoid cutting the fibers as much as possible, so that the Tencel fibrillated fiber can obtain a larger length and a lower fine fiber component. Then, by using the high-speed hydrodynamic shearing action of the high frequency defibrator, a large number of fibrils can be obtained, and the Tencel fiber can be fully fibrillated.

[0039] The above description is only the preferred embodiment of the present application, but the present application should not be limited to the embodiment and the disclosure of the drawings, so any equivalent or modification made without departing from the disclosed spirit of the present application falls within the scope of the present application.

Claims

1. A method of making a lyocell fibril, characterized by, The method comprises the following steps: S1, adding Tencel short fibers into water to control the concentration to be 2-4%, and dispersing the Tencel short fibers by a pulper; S2, filtering water from the dispersed pulp by a filter press to obtain high-concentration pulp with a concentration of 10-30%, and conveying the high-concentration pulp to a group of high-concentration refiners by a screw feeder to be refined, thereby obtaining pulp 1 with a beating degree of 40-50°SR; S3, diluting the pulp 1 to a concentration of 1-3% by adding water, and beating and defibrating the pulp by a high-frequency defibrator, and repeatedly beating and defibrating the pulp by high-speed hydraulic shearing of the high-frequency defibrator, thereby obtaining Tencel fibrillated fibers with a beating degree of 75-95°SR; the rotation speed of the high-frequency defibrator is adjustable, and different degrees of hydraulic shearing force can be obtained between two refiner plates by changing the rotation speed.

2. The method of claim 1, wherein the lyocell fibrillation is performed by a method comprising: The Tencel short fibers are regenerated cellulose fibers produced by solvent spinning.

3. The method of claim 1, wherein the lyocell fibrillation is performed by a method comprising: The high-concentration refining equipment is one of a disc refiner, a conical refiner, and a cylindrical refiner.

4. Use of fluff pulp fibers, characterized in that The fibrillated fibers prepared by the method of any one of claims 1-3 are applied to battery separators or capacitor separators.

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