Blended paperless cigarette filter stick and preparation method thereof

Abstract

The invention belongs to the technical field of cigarette filter tips, and particularly discloses a blended paperless cigarette filter stick and a preparation method thereof.The filter stick is composed of a paperless wrapped blended fiber layer and comprises degradable plant-based fibers, modified synthetic fibers and functional adsorption microfibers, gradient pore channels are formed in the filter stick in the smoke flowing direction, and the functional adsorption microfibers are formed in the filter stick. And the biting end is provided with a micro-nano topological texture. The preparation method comprises the steps of fiber pretreatment, gradient lapping hot press molding, texture laser etching and paperless rolling curing. The problems that an existing filter stick is insufficient in mechanical strength, poor in filtering effect, residual in paper smell, difficult to degrade, poor in forming adaptability and the like are solved, collaborative optimization of the filtering performance, the mechanical performance, the smoking experience and the environmental protection performance is achieved, and the filter stick is adaptive to existing cigarette production equipment and has good industrial application value.

Description

A blended paperless cigarette filter rod and its preparation method Technical Field

[0001] This invention relates to the field of cigarette filter technology, and in particular to a blended paperless cigarette filter rod and its preparation method. Background Technology

[0002] Cigarette filters, as one of the core components of cigarettes, are mainly used to trap harmful substances such as tar and nicotine in cigarette smoke, improving the smoking experience. Currently, the mainstream cigarette filters on the market are mainly divided into four categories: traditional paper-based filters, cellulose acetate tow filters, polypropylene tow filters, and paperless filters. However, existing filters all have technical shortcomings that are difficult to address simultaneously, as detailed below:

[0003] 1) Traditional paper-based filter rods: Made primarily from wood pulp fiber, these filter rods possess some biodegradability but suffer from thermal collapse and a strong dry, prickly feel. Furthermore, they have low retention efficiency for tar and phenolic substances in cigarette smoke, making it difficult to meet the quality requirements of mid- to high-end cigarettes. Additionally, the production of paper-based filter rods requires multiple layers of paper wrapping, resulting in high raw material costs. The multi-layered structure also easily leads to residual paper flavor in the smoke, affecting the smoking experience.

[0004] 2) Fiber acetate tow filter rods: As the most widely used filter rod material, they have good overall performance, but the production process is complex and energy-intensive. Furthermore, cellulose acetate is difficult to biodegrade, easily causing secondary environmental pollution. In addition, the filtration channels of cellulose acetate filter rods are mostly linear, resulting in insufficient filtration of flue gas. It is also difficult to uniformly add functional tar-reducing and harm-reducing substances during the molding process, and the addition of fillers such as activated carbon presents problems of poor dispersibility and easy detachment.

[0005] 3) Polypropylene tow filter rods: They are inexpensive, but their adsorption capacity and filtration effect are far lower than those of cellulose acetate tow filter rods. When smoking, they are prone to defects such as diluted tobacco aroma and irritation, which limits their application range.

[0006] 4) Existing paperless filter rods: Although they eliminate the need for multiple layers of paper wrapping and solve the problem of strong paper odor, they still have significant shortcomings. On the one hand, existing paperless filter rods are mostly made of single fibers or simple blended fibers, resulting in poor compatibility between fibers, insufficient mechanical strength of the filter rods, and susceptibility to deformation and breakage. On the other hand, the pore structure of paperless filter rods is mostly uniformly distributed, making it impossible to achieve gradient filtration of flue gas, resulting in a trade-off between the efficiency of harmful substance retention and the smoothness of suction. At the same time, the existing paperless filter rod molding process relies on the compaction of cloth tape, which easily forms cloth tape indentations on the filter rod surface, affecting the appearance quality. Furthermore, the molding equipment is difficult to modify and cannot be compatible with the production of ordinary filter rods. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a blended paperless cigarette filter rod and its preparation method. By combining biodegradable plant-based fibers, modified synthetic fibers, and functional adsorption microfibers, along with gradient pore structure design and paperless molding process, the filter rod's degradability, filtration performance, mechanical strength, and smoking experience are synergistically optimized.

[0008] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0009] One objective of this invention is to provide a blended paperless cigarette filter rod, comprising a filter rod body composed of several blended fiber layers. The blended fiber layers, by mass percentage, comprise the following components: 40%-60% biodegradable plant-based fibers, 20%-40% modified synthetic fibers, and 5%-15% functional adsorbent microfibers. The biodegradable plant-based fibers are a composite of bamboo pulp fiber and hemp fiber; the modified synthetic fibers are polylactic acid fiber grafted with acrylate copolymer; and the functional adsorbent microfibers are cellulose nanofibers / graphene composite microfibers prepared by electrospinning. The filter rod body has continuous gradient channels extending from the upper part near the tobacco end to the top of the bite end. The outer circumferential surface of the bite end of the filter rod is provided with micro-nano-level topological textures, which are a composite structure of micron-level grooves and nano-level micropores, with groove depths of 5-10 μm and micropore diameters of 1-3 μm.

[0010] Furthermore, the mass ratio of bamboo pulp fiber to hemp fiber is 3:1-2:1; the grafting rate of polylactic acid fiber grafted acrylate copolymer is 8%-15%; and the mass percentage of graphene in the cellulose nanofiber / graphene composite microfiber is 3%-8%.

[0011] Furthermore, the pore size of the continuous gradient channel gradually changes from 10-20 μm to 30-50 μm from near the tobacco end to the bite end.

[0012] Furthermore, the areal density of the blended fiber layer is 80-120 g / m², the average fiber length is 20-35 mm, and the thickness of each blended fiber layer is 0.8-1.2 mm.

[0013] The second objective of this invention is to provide a method for preparing a blended paperless cigarette filter rod, comprising the following steps:

[0014] S1. Fiber pretreatment: Degradable plant-based fibers are sequentially degummed and loosened to obtain pretreated plant-based fibers; modified synthetic fibers are opened to obtain pretreated synthetic fibers; functional adsorbent microfibers are dispersed to obtain dispersed microfiber slurry.

[0015] S2. Preparation of blended fiber layer: After mixing pretreated plant-based fibers, pretreated synthetic fibers and dispersible microfiber slurry according to the specified ratio, a gradient web laying process is adopted to form a blended fiber web with gradually changing pore size along the flue gas flow direction by an airflow web forming machine. Then, it is subjected to hot pressing and shaping treatment. The hot pressing temperature is 120-150℃, the hot pressing pressure is 2-4 MPa, and the holding time is 1-3 min to obtain the blended fiber layer.

[0016] S3. Molding process: The prepared blended fiber layer is laid layer by layer and then cured. The curing agent is polyethylene glycol glycerol ester, the curing temperature is 80-100℃, and the curing time is 2-4 min to obtain the blended paperless cigarette filter rod.

[0017] S4. Preparation of topological texture: Micro-nano-level topological textures are prepared on the outer peripheral surface of the bite end of the blended paperless cigarette filter rod using laser etching process. The laser power is 8-15 W, the scanning speed is 500-1000 mm / s, and the number of etching times is 1-2.

[0018] Furthermore, in step S1, the degumming treatment adopts the alkaline boiling method, the alkaline solution is a sodium carbonate solution with a concentration of 5%-8%, the boiling temperature is 90-100℃, and the boiling time is 1-2 h; the loosening treatment adopts a high-frequency loosening machine, the loosening speed is 2000-3000 r / min, and the loosening time is 5-10 min.

[0019] Furthermore, in step S2, the web laying speed of the gradient web laying process is 10-20 m / min, and the mixing uniformity of plant-based fibers and synthetic fibers is ≥95%.

[0020] Furthermore, in step S3, the amount of curing agent applied is 3%-5% of the filter rod mass.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Significantly improved filtration performance: Through the synergy of "gradient pore structure + functional adsorption microfiber", the flue gas first passes through the small-diameter end to efficiently intercept harmful substances such as tar and nicotine, and then passes through the gradually changing pore size to ensure smooth suction. The tar rejection rate reaches 35.2%-42.1% and the nicotine rejection rate reaches 32.8%-40.5%, which is significantly better than existing cellulose acetate filter rods and paperless filter rods.

[0023] 2. Optimized mechanical strength and molding stability: The filter rod adopts a ternary compound of "degradable plant-based fiber + modified synthetic fiber" and is combined with hot pressing and paperless curing process. The axial mechanical strength of the filter rod reaches 12.5-18.7 N, avoiding the problems of easy deformation and breakage of existing paperless filter rods. The paperless molding process combined with high-precision mandrel control has no cloth tape indentation, uniform size, and is compatible with existing cigarette production equipment.

[0024] 3. Significantly improved suction experience: The filter stick is free of paper wrapping, completely eliminating paper smell residue; the micro-nano-level topological texture (micron grooves + nano-micropores) at the bite end increases friction and improves bite comfort, preventing slippage during suction, while plant-based fibers reduce dryness and prickliness, resulting in a sensory experience superior to existing filter sticks.

[0025] 4. Excellent environmental performance and degradability: The three-component fiber is composed of degradable materials (bamboo pulp / hemp fiber, modified PLA, cellulose nanofibers), with a biodegradability rate of over 85% in 90 days, which is far higher than that of existing cellulose acetate filter rods, blended filter rods and paperless filter rods, effectively reducing secondary environmental pollution.

[0026] 5. High overall cost-effectiveness and great industrial application value: No paper wrapping is required, reducing raw material costs; the process combination is reasonable, requiring no large-scale modification of existing equipment, balancing performance, environmental protection and production costs, and can meet the quality requirements of medium and high-end cigarettes, with broad prospects for industrial promotion. Attached Figure Description

[0027] Figure 1 is a cross-sectional view of the filter rod of the present invention.

[0028] Figure 2 is a schematic diagram of an exemplary topological texture. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0030] Example 1

[0031] As shown in Figure 1, this embodiment exemplarily demonstrates a blended paperless cigarette filter rod, comprising a filter rod body 1. By mass percentage, the blended fiber layer comprises: 40% biodegradable plant-based fiber (bamboo pulp fiber to hemp fiber mass ratio 3:1), 40% modified synthetic fiber (polylactic acid fiber grafted acrylate copolymer, grafting rate 8%), and 20% functional adsorbent microfiber (cellulose nanofibers / graphene composite microfibers, graphene mass percentage 3%). A continuous gradient channel 2 is formed inside the filter rod body 1, with the pore size gradually changing from 10 μm near the tobacco end to 30 μm towards the bite end. The bite end surface is provided with micro-nano-level topological textures, with a groove depth of 5 μm and a micropore diameter of 1 μm. The areal density of the blended fiber layer is 80 g / m², the average fiber length is 20 mm, and the thickness of the blended fiber layer is 0.8 mm. The filter rod diameter is 7.0 mm and the length is 20 mm.

[0032] The preparation method of the blended paperless cigarette filter rod in this embodiment includes the following steps: (1) Fiber pretreatment: Degumming of biodegradable plant-based fibers by alkaline boiling, sodium carbonate solution concentration 5%, boiling temperature 90℃, boiling time 1 h, and then debonding by high frequency debonding machine (speed 2000 r / min, time 5 min) to obtain pretreated plant-based fibers; opening treatment of modified synthetic fibers to obtain pretreated synthetic fibers; dispersion of functional adsorbent microfibers by ultrasonic dispersion to obtain dispersible microfiber slurry; (2) Preparation of blended fiber layer: using gradient web laying process, pretreated plant-based fibers, pretreated synthetic fibers and dispersible microfiber slurry are mixed according to the ratio, web laying speed 10 m / min, mixing uniformity 95%, and forming a blended fiber web with gradually changing pore size along the direction of smoke flow by airflow web forming machine, and then hot pressing (temperature 120℃, pressure 2) MPa, holding time 1min), to obtain the blended fiber layer; (3) after the prepared blended fiber layer is laid layer by layer and then cured, the curing agent is polyethylene glycol glycerol ester, the coating amount is 3% of the filter rod mass, the curing temperature is 80℃, the curing time is 2 min, to obtain the blended paperless cigarette filter rod; (4) topological texture preparation: the micro-nano-level topological texture shown in Figure 2 is prepared on the outer peripheral surface of the bite end of the blended fiber layer by laser etching process, the laser power is 8 W, the scanning speed is 500 mm / s, the number of etching times is 1, the topological texture is a composite structure of micron-level groove 3 and nano-level micropore 4, the groove depth is 7μm, and the micropore diameter is 1μm.

[0033] Example 2

[0034] As shown in Figure 1, this embodiment exemplarily demonstrates a blended paperless cigarette filter rod, comprising a filter rod body 1. By mass percentage, the blended fiber layer comprises: 50% biodegradable plant-based fiber (bamboo pulp fiber to hemp fiber mass ratio 5:3), 30% modified synthetic fiber (polylactic acid fiber grafted acrylate copolymer, grafting rate 12%), and 10% functional adsorbent microfiber (cellulose nanofibers / graphene composite microfibers, graphene mass percentage 5%). The filter rod body 1 has a continuous gradient pore structure inside, with the pore diameter gradually changing from 15μm near the tobacco end to 40μm towards the bite end; the bite end surface has a micro-nano-level topological texture with a groove depth of 8μm and a micropore diameter of 2μm. The areal density of the blended fiber layer is 100g / m³. 2 The average fiber length is 28 mm, and the thickness of the blended fiber layer is 1.0 mm; the filter rod diameter is 7.5 mm and the length is 22 mm.

[0035] The preparation method of the blended paperless cigarette filter rod in this embodiment includes the following steps: (1) Fiber pretreatment: plant-based fiber degumming alkali concentration 6%, boiling temperature 95℃, boiling time 1.5 h; loosening speed 2500 r / min, time 8 min; the rest of the pretreatment steps are the same as in Example 1; (2) Blended fiber layer preparation: gradient web laying process web laying speed 15 m / min, mixing uniformity 97%; hot pressing setting temperature 135℃, pressure 3MPa, holding time 2 min; the rest of the steps are the same as in Example 1; (3) Molding treatment: curing agent coating amount is 4% of the filter rod mass, curing temperature 90℃, curing time 3 min; (4) Topological texture preparation: laser power 12 W, scanning speed 800 mm / s, etching times 2 times; the rest of the steps are the same as in Example 1.

[0036] Example 3

[0037] As shown in Figure 1, this embodiment exemplarily demonstrates a blended paperless cigarette filter rod, comprising a filter rod body 1. By mass percentage, the blended fiber layer comprises: 60% biodegradable plant-based fiber (bamboo pulp fiber to hemp fiber mass ratio 2:1), 20% modified synthetic fiber (polylactic acid fiber grafted acrylate copolymer, grafting rate 15%), and 5% functional adsorbent microfiber (cellulose nanofibers / graphene composite microfibers, graphene mass percentage 8%). The filter rod body 1 has a continuous gradient pore structure internally, with the pore diameter gradually changing from 20 μm near the tobacco end to 50 μm towards the bite end; the bite end surface has a micro-nano-level topological texture with a groove depth of 10 μm and a micropore diameter of 3 μm. The areal density of the blended fiber layer is 120 g / m², the average fiber length is 35 mm, and the thickness of the blended fiber layer is 1.2 mm; the filter rod diameter is 8.0 mm and the length is 25 mm.

[0038] The preparation method of the blended paperless cigarette filter rod in this embodiment includes the following steps: (1) Fiber pretreatment: the concentration of the degummed alkali solution of the plant-based fiber is 8%, the boiling temperature is 100℃, and the boiling time is 2 h; the loosening speed is 3000 r / min, and the time is 10 min; the remaining pretreatment steps are the same as in Example 1; (2) Preparation of blended fiber layer: the gradient web laying process has a web laying speed of 20 m / min and a mixing uniformity of 98%; the hot pressing and shaping temperature is 150℃, the pressure is 4 MPa, and the holding time is 3 min; the remaining steps are the same as in Example 1; (3) Molding treatment: the amount of curing agent coating is 5% of the filter rod mass, the curing temperature is 100℃, and the curing time is 4 min; (4) Preparation of topological texture: the laser power is 15W, the scanning speed is 1000mm / s, and the number of etching times is 2; the remaining steps are the same as in Example 1.

[0039] Performance testing

[0040] The performance of the blended paperless cigarette filter rods prepared in Examples 1-3 was tested according to conventional methods in the art, and the test results are shown in Table 1 below.

[0041] Table 1

[0042] Performance Indicators Example 1 Example 2 Example 3 Tar Retention Rate (%) 35.2 38.6 42.1 Nicotine Retention Rate (%) 32.8 36.4 40.5 Mechanical Strength (N) 12.5 15.3 18.7 Biodegradation Rate (%, 90 days) 85.6 89.2 92.5 Paper Odor Residue Score (1-5 points) 1.2 1.0 0.8 surface

[0043] Note: The paper odor residue score is based on sensory evaluation (a conventional method in the existing technology), with 5 points indicating severe paper odor residue and 1 point indicating no paper odor residue; the mechanical strength test is the axial compressive strength of the filter rod.

[0044] As shown in Table 1, the test results of the blended paperless cigarette filter rods prepared in Examples 1-3 of the present invention have significantly improved tar retention rate and nicotine retention rate compared with the control group, and the biodegradation rate is much higher than that of the control group. They also have no papery smell residue and their mechanical strength meets the requirements of cigarette production and use. This achieves synergistic optimization of filtration performance, degradability and smoking experience.

[0045] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A blended paperless cigarette filter rod, comprising a filter rod body, characterized in that: The filter rod body is composed of several layers of blended fiber, which include the following components by mass percentage: 40%-60% biodegradable plant-based fiber, 20%-40% modified synthetic fiber, and 5%-15% functional adsorption microfiber; the biodegradable plant-based fiber is a composite fiber of bamboo pulp fiber and hemp fiber, the modified synthetic fiber is polylactic acid fiber grafted acrylate copolymer, and the functional adsorption microfiber is cellulose nanofiber / graphene composite microfiber prepared by electrospinning; the filter rod body has continuous gradient channels inside, which extend from the upper part near the tobacco end to the top of the bite end; the outer peripheral surface of the bite end of the filter rod is provided with micro-nano-level topological texture, which is a composite structure of micron-level grooves and nano-level micropores, with a groove depth of 5-10μm and a micropore diameter of 1-3μm.

2. The blended paperless cigarette filter rod according to claim 1, characterized in that: The mass ratio of bamboo pulp fiber to hemp fiber is 3:1-2:1; the grafting rate of polylactic acid fiber grafted acrylate copolymer is 8%-15%; and the mass percentage of graphene in the cellulose nanofiber / graphene composite microfiber is 3%-8%.

3. The blended paperless cigarette filter rod according to claim 1, characterized in that: The pore size of the continuous gradient channel gradually changes from 10-20μm to 30-50μm from near the tobacco end to the bite end.

4. The blended paperless cigarette filter rod according to claim 1, characterized in that: The areal density of the blended fiber layer is 80-120 g / m², the average fiber length is 20-35 mm, and the thickness of each blended fiber layer is 0.8-1.2 mm.

5. A method for preparing a blended paperless cigarette filter rod as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Fiber Pretreatment: Degumming and loosening of biodegradable plant-based fibers are performed sequentially to obtain pretreated plant-based fibers; opening treatment is performed on modified synthetic fibers to obtain pretreated synthetic fibers; dispersion treatment is performed on functional adsorbent microfibers to obtain dispersed microfiber slurry. S2. Preparation of Blended Fiber Layer: Pretreated plant-based fibers, pretreated synthetic fibers, and dispersed microfiber slurry are mixed according to a specified ratio. A gradient web-forming process is used to form a blended fiber web with gradually changing pore sizes along the flue gas flow direction using an air-jet web forming machine. This is followed by hot-pressing and setting treatment at 120-150℃, 2-4 MPa, and 1-3 min to obtain the blended fiber layer. S3. Molding Treatment: The prepared blended fiber layer is layered and then cured. Polyethylene glycol glycerol is used as the curing agent, and the curing temperature is 80-100℃ for 2-4 minutes. min, to obtain a blended paperless cigarette filter rod; S4, preparation of topological texture: micro-nano-level topological texture is prepared on the outer peripheral surface of the bite end of the blended paperless cigarette filter rod by laser etching process, with laser power of 8-15 W, scanning speed of 500-1000 mm / s, and etching times of 1-2 times.

6. The method for preparing the blended paperless cigarette filter rod according to claim 5, characterized in that, In step S1, the degumming treatment adopts the alkaline boiling method, the alkaline solution is a sodium carbonate solution with a concentration of 5%-8%, the boiling temperature is 90-100℃, and the boiling time is 1-2 h; the loosening treatment adopts a high-frequency loosening machine, the loosening speed is 2000-3000 r / min, and the loosening time is 5-10 min.

7. The method for preparing the blended paperless cigarette filter rod according to claim 5, characterized in that, In step S2, the web laying speed of the gradient web laying process is 10-20 m / min, and the mixing uniformity of plant-based fibers and synthetic fibers is ≥95%.

8. The method for preparing the blended paperless cigarette filter rod according to claim 5, characterized in that, In step S3, the amount of curing agent applied is 3%-5% of the filter rod mass.

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