A plant fiber foam filter rod and a preparation method thereof

Abstract

The application discloses a plant fiber foam filter rod and a preparation method thereof. The preparation method comprises the following steps: crushing, soaking and dispersing a plant fiber pulp board, filtering and concentrating the pulp, and then performing beating treatment on the pulp to obtain microfibrillated cellulose fibers with a beating degree of 50°SR-70°SR and a fiber length of 0.5mm-2.0mm; the microfibrillated cellulose fibers are mixed into a fiber suspension, dodecyl dimethyl betaine is added, and continuous stirring is performed to make the system volume expand to 2.0-2.5 times of the original volume, so that the fiber foam pulp is obtained; the fiber foam pulp is drained in a mold for 3-6 hours, and then air blowing drying is performed at 50-60 DEG C to obtain a fiber foam product; and the fiber foam product is made into a filter rod. The application uses natural commercial pulp board fibers as the main raw material, performs beating treatment, performs surfactant assisted foaming, performs wet forming and drying and shaping, constructs a fiber-based porous foam, and prepares a filter rod for cigarettes, and the filter rod has the advantages of stable structure, renewability, rich raw materials and green environmental protection.

Description

Technical Field

[0001] This invention relates to the field of cigarette filter rods, and more specifically, to a plant fiber foam filter rod and its preparation method. Background Technology

[0002] The mainstream filter material for cigarette filters is cellulose acetate. Cellulose acetate has the advantages of strong filtration capacity and a rigid texture, preventing the filter from "softening" during smoking, thus maintaining its performance and satisfying the consumer's taste. However, the decomposition of cellulose acetate is highly dependent on environmental conditions.

[0003] Biodegradable filter rods mainly include paper filter rods and polylactic acid (PLA) filter rods. Paper filter rods have low raw material costs and are biodegradable, but they easily absorb moisture from cigarette smoke, resulting in a dry taste and a "paper flavor" when smoking cigarettes. PLA filter rods can effectively filter harmful components in cigarette smoke and are completely degradable, but they have poor heat resistance and are prone to collapse and deformation.

[0004] Plant fibers are abundant, renewable, and biodegradable. Foamed materials made from plant fibers possess a natural porous structure and a certain adsorption capacity, and are rich in active groups such as hydroxyl groups, allowing for further modification and functionalization, thus providing broad prospects for the development of novel green filter rod materials. However, the process of preparing filter rods from plant fibers suffers from structural instability, hindering their commercial application.

[0005] Therefore, how to provide a plant fiber filter rod with a stable structure that is conducive to commercial application has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] One objective of this invention is to provide a new technical solution for preparing plant fiber foam filter rods that are structurally stable and conducive to commercial applications.

[0007] According to a first aspect of the present invention, a method for preparing plant fiber foam filter rods is provided.

[0008] The preparation method of this plant fiber foam filter rod includes the following steps:

[0009] Step (1): After crushing, impregnating and dispersing the plant fiber pulp board, filter and concentrate the pulp to a mass concentration of 5%-15%, and then beat the pulp at 20℃-30℃ to obtain microfibrillated cellulose fibers with a freeness of 50°SR-70°SR and a fiber length of 0.5mm-2.0mm.

[0010] Step (2): Prepare a fiber suspension with an oven-dry fiber concentration of 3g / 150-250mL by microfibrillated cellulose fibers, add dodecyl dimethyl betaine at 0.3%-0.8% of the oven-dry fiber mass, and stir continuously at a speed of 4000rpm-5000rpm to expand the system volume to 2.0-2.5 times the original volume to obtain fiber foam slurry;

[0011] Step (3): Drain the fiber foam slurry in the mold for 3-6 hours, and then dry it in a forced-air dryer at 50℃-60℃ for 6-12 hours until the moisture content is less than 5% to obtain the finished fiber foam product;

[0012] Step (4): The finished fiber foam is made into filter rods.

[0013] Optionally, the plant fiber pulp board in step (1) includes at least one of hardwood pulp board, softwood pulp board, or bamboo pulp board.

[0014] Optionally, the plant fiber pulp board in step (1) includes hardwood pulp board, softwood pulp board and bamboo pulp board in a mass ratio of 2:2:1.

[0015] Optionally, the pulping time in step (1) is 20-30 minutes.

[0016] Optionally, in step (2), the fiber suspension is stirred at a speed of 500 rpm to 1000 rpm for 5 to 10 minutes.

[0017] Optionally, the continuous stirring time in step (2) is 3 to 5 minutes.

[0018] Optionally, the draining in step (3) is at room temperature.

[0019] According to a second aspect of the present invention, a plant fiber foam filter rod is provided.

[0020] The plant fiber foam filter rod is prepared by the preparation method described in this invention.

[0021] Optionally, the plant fiber foam filter rod has a three-dimensional porous network structure inside, with an average pore size of 50μm-300μm.

[0022] This invention uses natural commercial pulp fiber as the main raw material. After pulping, surfactant-assisted foaming, wet molding and drying, fiber-based porous foam is constructed and prepared into a cigarette filter rod. It has the advantages of stable structure, renewability, abundant raw materials and green environmental protection.

[0023] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0025] Figure 1 The image shows a physical picture of the plant fiber foam product prepared for this example.

[0026] Figure 2 Scanning electron microscope image of the plant fiber foam product prepared for the example.

[0027] Figure 3 A comparison chart of the particle permeability of solid particles in plant fiber foam filter rods and cellulose acetate filter rods prepared for the example. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0029] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0030] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0031] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0032] The method for preparing plant fiber foam filter rods provided by the present invention includes the following steps:

[0033] Step (1): After crushing, impregnating and dispersing the plant fiber pulp board, filter and concentrate the pulp to a mass concentration of 5%-15%. Then, beat the pulp at 20℃-30℃ to obtain microfibrillated cellulose fibers with a freeness of 50°SR-70°SR and a fiber length of 0.5mm-2.0mm.

[0034] The plant fiber pulp board in step (1) may include at least one of hardwood pulp board, softwood pulp board, or bamboo pulp board. Hardwood pulp board, softwood pulp board, and bamboo pulp board are all commercially available plant fiber pulp boards that can be easily commercialized.

[0035] The plant fiber pulp board in step (1) may include hardwood pulp board, softwood pulp board, and bamboo pulp board in a mass ratio of 2:2:1. Hardwood pulp board fibers are characterized by short and wide fibers, softwood pulp board fibers are characterized by long and thick fibers, and bamboo pulp board fibers are characterized by slender fibers. Using hardwood pulp board, softwood pulp board, and bamboo pulp board in a certain mass ratio can take into account both the needs of building the frame and filling the gaps in the frame, which is beneficial to improving the structural stability of the filter rod.

[0036] The pulping time in step (1) can be 20-30 minutes.

[0037] In step (1) of this application, the moderate microfibrillation treatment of the plant fiber board is a fundamental step in constructing the fiber foam structure. By controlling the beating degree, beating time, and fiber length, the fibers can undergo moderate fibrillation while maintaining a certain skeleton length, thereby significantly improving the degree of hydroxyl exposure on the fiber surface, specific surface area, and interweaving ability between fibers, thus providing a good fiber network foundation for the formation and stability of the subsequent foam structure.

[0038] Step (2): Prepare a fiber suspension with an oven-dry fiber concentration of 3g / 150-250mL by microfibrillated cellulose fibers. Add dodecyl dimethyl betaine at 0.3%-0.8% of the oven-dry fiber mass and stir continuously at 4000rpm-5000rpm until the system volume expands to 2.0-2.5 times the original volume to obtain fiber foam slurry.

[0039] In step (2), when preparing the fiber suspension, the mixture can be stirred at a speed of 500 rpm to 1000 rpm for 5 to 10 minutes.

[0040] The stirring time in step (2) can be 3 to 5 minutes.

[0041] Step (2) of this application can introduce more uniform bubbles into the fiber suspension system by controlling the amount of foaming agent added and the stirring intensity, so that the volume of the slurry expands to a suitable multiple, and improves the foam stability by means of the adsorption and support of the fiber on the gas-liquid interface.

[0042] Step (3): Drain the fiber foam slurry in the mold for 3-6 hours, and then dry it in a forced-air dryer at 50℃-60℃ for 6-12 hours until the moisture content is less than 5%, to obtain the finished fiber foam product.

[0043] The draining in step (3) can be done at room temperature.

[0044] In this application, the wet molding and dewatering process of the foam slurry is a crucial step in fixing the foam structure. It is essential to ensure the gradual drainage of free water while minimizing cell collapse, in order to initially construct a three-dimensional network structure with a certain porosity and shape retention. The subsequent low-temperature drying and setting process has a significant impact on the final morphology and properties of the fiber foam. Milder drying conditions are beneficial for enhancing the inter-fiber bonding while preserving the pore structure, ultimately resulting in a fiber foam material that is lightweight, porous, and possesses a certain level of mechanical strength.

[0045] Step (4): The finished fiber foam is made into filter rods.

[0046] The plant fiber foam filter rod of the present invention is prepared by the preparation method of the present invention.

[0047] The plant fiber foam filter rod has a three-dimensional porous network structure inside, with an average pore size of 50μm-300μm.

[0048] This application uses natural commercial pulp board as the base material, and improves the specific surface area, surface activity and interweaving ability of the fibers through controllable microfibrillation treatment. Combined with surfactant-assisted foaming, wet molding and drying, a bio-based foam filter rod material with a stable three-dimensional network structure is constructed, which can be used on a large scale and commercially.

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available. Unless otherwise specified, the equipment used in the experiments is well known to those skilled in the art.

[0050] Example

[0051] (1) Weigh 30g of hardwood pulp board, softwood pulp board and bamboo pulp board with a mass ratio of 2:2:1 (based on oven-dry weight), break them into small pieces of less than 2×2cm, soak them in water for 8-12 hours to allow the fibers to fully swell, then dilute with water and disperse them using a fiber dissociator. Filter the dispersed pulp water using a Buchner funnel and concentrate it to a mass concentration of 5%-15%. Weigh 30g of pulp, adjust the pulp temperature to 25℃, and control the beating time to 25 minutes to obtain microfibrillated cellulose fibers with a freeness of 60°SR and a fiber length of 0.5mm-2.0mm.

[0052] (2) Weigh 3g of microfibrillated cellulose fiber according to the dry weight of the fiber, prepare a fiber slurry with a mass fraction of 1.5wt%, add water to a total volume of 200mL, and then pour it into a stirrer and stir at 500rpm for 5 minutes to fully disperse it and obtain a uniform fiber suspension.

[0053] Weigh 0.015g of dodecyl dimethyl betaine and add it to the fiber suspension. Stir at 4000rpm for 3 minutes to expand the system volume to 2.0 times the original volume, and obtain a fiber foam slurry with relatively uniform foam and relatively stable structure.

[0054] The foamed fiber slurry is quickly poured into a mold for molding, and then allowed to drain naturally for 5 hours to remove some of the free water and initially fix the foam structure. The drained sample is then placed in a 50-60℃ forced-air oven to dry for 7-8 hours until the moisture is basically removed and the structure is stable, finally obtaining the finished fiber foam product.

[0055] The finished fiber foam is processed into complete plant fiber foam filter rods using a molding device.

[0056] Figure 1 This is a photograph of the finished plant fiber foam product prepared for this example. The finished foam product is white and can be made into various shapes.

[0057] Figure 2 Scanning electron microscope (SEM) image of the plant fiber foam product prepared for this example. Figure 2 It is evident that the finished foam product has a rich pore structure, which can achieve a good filtration effect.

[0058] Figure 3 A comparison chart of particle permeability of solid particles between plant fiber foam filter rods and cellulose acetate filter rods prepared for the examples. Figure 3 It is evident that plant fiber foam filters have a significant particulate matter (PM1) blocking capacity and can effectively filter cigarette smoke.

[0059] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for preparing plant fiber foam filter rods, characterized in that, Includes the following steps: Step (1): After crushing, impregnating and dispersing the plant fiber pulp board, filter and concentrate the pulp to a mass concentration of 5%-15%, and then beat the pulp at 20℃-30℃ to obtain microfibrillated cellulose fibers with a freeness of 50°SR-70°SR and a fiber length of 0.5mm-2.0mm. Step (2): Prepare a fiber suspension with an oven-dry fiber concentration of 3g / 150-250mL by microfibrillated cellulose fibers, add dodecyl dimethyl betaine at 0.3%-0.8% of the oven-dry fiber mass, and stir continuously at a speed of 4000rpm-5000rpm to expand the system volume to 2.0-2.5 times the original volume to obtain fiber foam slurry; Step (3): Drain the fiber foam slurry in the mold for 3-6 hours, and then dry it in a forced-air dryer at 50℃-60℃ for 6-12 hours until the moisture content is less than 5% to obtain the finished fiber foam product; Step (4): The finished fiber foam is made into filter rods.

2. The method for preparing plant fiber foam filter rods according to claim 1, characterized in that, The plant fiber pulp board in step (1) includes at least one of hardwood pulp board, softwood pulp board, or bamboo pulp board.

3. The method for preparing plant fiber foam filter rods according to claim 2, characterized in that, The plant fiber pulp board in step (1) includes hardwood pulp board, softwood pulp board and bamboo pulp board in a mass ratio of 2:2:

1.

4. The method for preparing plant fiber foam filter rods according to claim 1, characterized in that, The pulping time in step (1) is 20-30 minutes.

5. The method for preparing plant fiber foam filter rods according to claim 1, characterized in that, In step (2), the fiber suspension is stirred at a speed of 500 rpm to 1000 rpm for 5 to 10 minutes.

6. The method for preparing plant fiber foam filter rods according to claim 1, characterized in that, The continuous stirring time in step (2) is 3 to 5 minutes.

7. The method for preparing plant fiber foam filter rods according to claim 1, characterized in that, The draining in step (3) is at room temperature.

8. A plant fiber foam filter rod, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

9. The plant fiber foam filter rod according to claim 8, characterized in that, The plant fiber foam filter rod has a three-dimensional porous network structure inside, with an average pore size of 50μm-300μm.

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