Method for preparing cellulose diacetate fiber by using waste filter stick as raw material

Abstract

The invention relates to a method for preparing cellulose diacetate fibers by using waste filter sticks as raw materials. The method comprises the steps of quantitative humidification, low-cutting-rate paper squeezing, rubbing and stripping, forming paper separation, vacuumizing and drying to remove glyceryl triacetate, dissolution, graded filtration and spinning. The method has the advantages that by means of the pretreatment technology of quantitative humidification and low-cutting-rate paper squeezing, rubbing and stripping, the integrity rate of the formed paper is effectively increased, and the generation amount of small-size fragments is reduced; and vacuum drying is combined to replace hot water washing, so that micron-sized fragment dissociation is avoided, the slurry filtering flux is stably improved, meanwhile, the replacement period of a filter material is prolonged, and the core bottleneck that the filtering flux is quickly attenuated in a traditional process is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of recycling technology for waste tobacco filter rods, and in particular to a method for preparing cellulose diacetate fiber using waste tobacco acetate filter rods as raw material. Background Technology

[0002] The recycling of waste cellulose acetate filter rods for tobacco is an important research direction in the fields of resource recycling and environmental protection. Its core value lies in regenerating cellulose diacetate (hereinafter referred to as "cellulose acetate") in waste filter rods into usable fibers, thereby reducing resource waste and environmental pollution.

[0003] Traditional recycling processes typically follow a route of "soaking → paper stripping → hot water washing → drying," but they suffer from the following core problems: 1) Severe contamination from formed paper fragments: Prolonged soaking leads to excessively low tensile strength of the formed paper, and high-speed tearing peeling generates a large number of small-sized formed paper fragments; 2) Rapid decay of filtration flux: During the hot water washing process, the paper fragments are further disintegrated into micron-sized particles, which clog fine filtration equipment (such as 1-10μm filter press) during subsequent pulp filtration, resulting in a rapid decay of filtration flux; 3) High cost and difficulty in mass production: The filter material consumption is large, the wastewater discharge is large, the recycling efficiency is low, and it is difficult to achieve industrial-scale mass production.

[0004] Therefore, in summary, there is an urgent need for a method to prepare cellulose diacetate fibers that can solve the problems of excessive paper fragments, rapid filtration flux decay, high cost, and difficulty in mass production in traditional waste filter rod recycling processes. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a method for preparing cellulose diacetate fiber using waste filter rods as raw materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing cellulose diacetate fiber from waste filter rods includes the following steps: S1, quantitative humidification waste filter rod; S2. The humidified waste filter rods are subjected to low-cutting-rate extrusion and paper stripping. S3, Separate the forming paper; S4. Vacuum dry the waste filter rods after separating the forming paper to remove triglycerides; S5. Dissolve the dried waste filter rods in acetone to form a slurry; S6. The slurry formed in step S5 is subjected to graded filtration, with the final filtration accuracy being 1-10μm. S7. Spin the filtered slurry from step S6 to obtain cellulose diacetate fibers.

[0007] Preferably, the quantitative humidification is performed by treating the waste filter rods with quantitative spraying of deionized water. After treatment, the moisture content of the waste filter rods is 40%-80%, and the forming paper on the surface of the waste filter rods maintains a tensile strength of more than 30%.

[0008] Preferably, the low-shear rate extrusion peeling is performed using an extrusion peeling machine with a shear rate of 100-2000 s. -1 This is to maintain the shape and integrity of the paper after peeling.

[0009] Preferably, the method of separating the formed paper is selected from one or more combinations of centrifugal separation, pneumatic separation, and negative pressure adsorption.

[0010] Preferably, in step S4, the conditions for vacuum drying are: temperature 110-160℃, pressure 0.3-10kPa; the vacuum drying equipment is selected from a double cone rotary vacuum dryer, a rake vacuum dryer, a square vacuum dryer, a cylindrical vacuum dryer, or a vacuum drying oven.

[0011] Preferably, in step S5, the concentration of the slurry is 26.5%-28.5%.

[0012] Preferably, in step S7, the spinning process is a dry spinning process, in which the filtered slurry is extruded through the fiber holes and the solvent evaporates in the spinning channel to form cellulose diacetate fibers.

[0013] Due to the adoption of the above technical solution, the beneficial effects obtained by the present invention include: 1. This invention improves the integrity of the formed paper and reduces the amount of small-sized fragments by using a pretreatment process of quantitative humidification and low-shear-rate extrusion and peeling. It also combines vacuum drying with hot water washing to avoid the dissociation of micron-sized fragments, stabilizes the slurry filtration flux, and extends the filter material replacement cycle, thus solving the core bottleneck of rapid filtration flux decay in traditional processes from the root. 2. This invention can eliminate wastewater pollution generated by hot water washing, significantly reduce environmental pressure, realize a green production model of resource recycling, and take into account both economic value and ecological benefits. 3. This invention can reduce the content of micron-level impurities, improve filtration performance, promote the mass production and application of waste filter rod recycling technology, meet the standards for tobacco tow, fill the technological gap in the industrial application of waste filter rod recycling, and provide a feasible solution for the efficient regeneration of waste tobacco filter rods. Attached Figure Description

[0014] Figure 1 This is a structural flow diagram of an embodiment of the method for preparing cellulose diacetate fiber using waste filter rods as raw materials according to the present invention. Detailed Implementation

[0015] Please see Figure 1 As shown, this invention mainly provides a highly efficient, environmentally friendly, and industrially scalable waste filter rod recycling process to solve problems such as excessive paper fragments, rapid filtration flux decline, high cost, and difficulty in large-scale production. Based on this, this invention optimizes the pretreatment process (quantitative humidification and low-cut paper stripping) and replaces hot water washing (vacuum drying), reducing impurity generation at the source, breaking through technical bottlenecks, and providing a feasible solution for the industrial application of waste filter rod recycling. Specifically, it includes the following steps: S1. Quantitative humidification of waste filter rods: Waste filter rods are treated by quantitative spraying of deionized water. After treatment, the moisture content of the waste filter rods is 40%-80%, and the forming paper on the surface of the waste filter rods maintains a tensile strength of more than 30%.

[0016] S2. Low-shear rate extrusion paper removal from the humidified waste filter rods: This is done using an extrusion paper removal machine with a shear rate of 100-2000 s. -1 To maintain the integrity of the shaped paper after peeling and avoid the formation of small fragments by high shear; S3. Separating the formed paper: The formed paper can be separated by centrifugal separation, pneumatic separation, negative pressure adsorption and other methods; S4. Vacuum drying is performed on the waste filter rods after separation and forming to remove triacetylglycerol; wherein, the vacuum drying conditions are: temperature 110-160℃, pressure 0.3-10kPa; the vacuum drying equipment includes, but is not limited to, the following types: double cone rotary vacuum dryer, rake vacuum dryer, square vacuum dryer, cylindrical vacuum dryer or vacuum drying box, preferably a double cone rotary vacuum dryer; S5. Dissolve the dried waste filter rods in acetone to form a slurry; using acetone as a solvent, control the slurry concentration to 26.5%-28.5% to form a cellulose diacetate acetone slurry; S6. The slurry formed in step S5 is subjected to graded filtration, with the final filtration accuracy being 1-10μm; the slurry is then filtered through a 1-10μm precision filter press to obtain pure spinning slurry. S7. Spinning the filtered slurry from step S6 to obtain cellulose diacetate fibers: Using a dry spinning process, the filtered slurry is extruded through the fiber holes and the solvent evaporates in the spinning tunnel to form cellulose diacetate fibers.

[0017] The following examples illustrate this point: Example 1

[0018] The specific implementation steps of this embodiment are as follows: 1. Quantitative humidification: Waste filter rods are humidified by quantitative spraying of deionized water, resulting in a moisture content of 80% for the treated waste filter rods; the tensile strength of the formed paper remains at 35%. 2. Low-shear rate extrusion paper stripping: An extrusion paper stripping machine is used to strip the paper from the humidified waste filter rods at a shear rate of 100s. -1 The integrity rate of the formed paper after peeling is 98%. 3. Separate the formed paper by using centrifugal separation equipment to separate the formed paper from the material flow; 4. Vacuum drying to remove triglycerides: Vacuum drying equipment is used to remove triglycerides from the waste filter rods after spraying and paper removal. The drying temperature is 110℃ and the pressure is 0.3kPa. 5. Dissolving: With a target concentration of 26.5%, use a horizontal dissolving kettle to dissolve the waste filter rod vinegar sheets in acetone and stir thoroughly to form a cellulose diacetate acetone slurry. 6. Filtration: The slurry is filtered through a filter press with a filtration accuracy of 1-10 μm to obtain the spinning slurry. 7. Spinning: The filtered slurry is pumped to the spinning machine to spin cellulose diacetate fibers, resulting in fibers with a linear density of 3.3 dtex and a breaking strength of 0.9 cN / dtex. Example 2

[0019] The specific implementation steps of this embodiment are as follows: 1. Quantitative humidification: Waste filter rods are humidified by quantitative spraying of deionized water, resulting in a moisture content of 40% for the treated waste filter rods; the tensile strength of the formed paper remains at 32%. 2. Low-shear rate extrusion paper stripping: An extrusion paper stripping machine is used to strip the paper from the humidified waste filter rods at a shear rate of 2000 s. -1 The integrity rate of the formed paper after peeling was 92%. 3. Separate the formed paper: Use negative pressure adsorption separation equipment to separate the formed paper from the material flow; 4. Vacuum drying to remove triglycerides: Vacuum drying equipment is used to remove triglycerides from the waste filter rods after spraying and paper removal. The drying temperature is 160℃ and the pressure is 10kPa.

[0020] 5. Dissolving: With a target concentration of 28.5%, use a horizontal dissolving kettle to dissolve the waste filter rod vinegar sheets in acetone and stir thoroughly to form a cellulose diacetate acetone slurry. 6. Filtration: The slurry is filtered through a filter press with a filtration accuracy of 1-10 μm to obtain the spinning slurry. 7. Spinning: The filtered slurry is pumped to the spinning machine by the slurry pump to spin cellulose diacetate fibers, resulting in fibers with a linear density of 2.7 dtex and a breaking strength of 0.8 cN / dtex.

[0021] Experimental Results: The fiber properties produced in both examples met expectations; the filtration flux was stable, and the filter media replacement cycle was extended by 3 times. It should be noted that this invention, through quantitative spray humidification and a low-shear-rate extrusion peeling process, reduces the strength of the formed paper while maintaining a certain tensile strength, improving the morphological integrity of the peeled paper. This avoids the low tensile strength and high shear force resulting in numerous small-sized paper fragments caused by prolonged soaking and high-speed tearing peeling under conventional processes. Simultaneously, a vacuum drying process is used to remove triacetylglycerol from the waste filter rods, replacing the conventional hot water washing method. This prevents the paper fragments from further disintegrating into even smaller micron-sized fragments during hot water washing. These fragments clog the filter media of the fine filtration equipment during subsequent recycling of the waste filter rods, leading to a rapid decrease in filtration flux. In addition, the present invention uses a vacuum drying process to remove triacetyl esters from waste filter rod vinegar sheets, which reduces the amount of deionized water used and wastewater discharge compared with conventional hot water washing and drying processes. At the same time, by reducing the content of micron-sized forming paper impurities in waste filter rod vinegar sheets, its filtration performance is improved, making it suitable for mass application in the production process of diacetate cellulose fiber to produce diacetate cellulose fiber.

[0022] The foregoing descriptions and embodiments are provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these contents, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the foregoing descriptions and embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from its scope should be within the protection scope of the present invention.

Claims

1. A method for preparing cellulose diacetate fibers from waste filter rods, characterized in that, The steps are as follows: S1, quantitative humidification waste filter rod; S2. The humidified waste filter rods are subjected to low-cutting-rate extrusion and paper stripping. S3, Separate the forming paper; S4. Vacuum dry the waste filter rods after separating the formed paper to remove triglycerides; S5. Dissolve the dried waste filter rods in acetone to form a slurry; S6. The slurry formed in step S5 is subjected to graded filtration, with the final filtration accuracy being 1-10μm. S7. Spin the filtered slurry from step S6 to obtain cellulose diacetate fibers.

2. The method according to claim 1, characterized in that, In step S1, the quantitative humidification is to treat the waste filter rod by quantitative spraying of deionized water. After treatment, the moisture content of the waste filter rod is 40%-80%, and the forming paper on the surface of the waste filter rod maintains a tensile strength of more than 30%.

3. The method according to claim 1, characterized in that, In step S2, the low-shear rate extrusion paper peeling is performed using an extrusion paper peeling machine with a shear rate of 100-2000 s. -1 This is to maintain the shape and integrity of the paper after peeling.

4. The method according to claim 1, characterized in that, In step S3, the method of separating the formed paper is selected from one or more combinations of centrifugal separation, pneumatic separation, and negative pressure adsorption.

5. The method according to claim 1, characterized in that, In step S4, the conditions for vacuum drying are: temperature 110-160℃, pressure 0.3-10kPa; the vacuum drying equipment includes, but is not limited to, the following types: double cone rotary vacuum dryer, rake vacuum dryer, square vacuum dryer, cylindrical vacuum dryer or vacuum drying box.

6. The method according to claim 1, characterized in that, In step S5, the concentration of the slurry is 26.5%-28.5%.

7. The method according to claim 1, characterized in that, In step S7, the spinning process adopts a dry spinning process, in which the filtered slurry is extruded through the fiber holes and the solvent evaporates in the spinning channel to form cellulose diacetate fibers.

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