A paper filter material, its preparation method and application

Abstract

This invention relates to a paper filter material, its preparation method, and its application. The preparation method of the paper filter material includes the following steps: S1. Preparing flash-dried pulp, mercerized pulp, cylinder-dried pulp, and water into a slurry; S2. Applying internal sizing to the slurry obtained in step S1, followed by molding, dewatering, and drying to obtain a base paper; S3. Applying surface sizing to the base paper obtained in step S2 using starch, followed by drying to obtain the paper filter material. The paper filter material obtained by this preparation method maintains good air permeability and high bulk. When used as a filter element, it forms a paper filter rod with low suction resistance and good suction resistance stability, which can replace current cellulose acetate filter rods, balancing production cost, environmental protection, and suction experience.

Description

Technical Field

[0001] This invention relates to the field of paper technology for cigarette filters, and more specifically, to a paper filter material, its preparation method, and its application. Background Technology

[0002] Currently, cigarette filters are generally made of cellulose acetate, meaning the filter element is made of cellulose acetate. Fiber acetate has a complex production process, high production costs, and is not easily degraded. Furthermore, it has a relatively low efficiency in retaining tar and nicotine in cigarette smoke at the same filtration pressure drop. Therefore, in recent years, especially since the "paper-for-plastic" policy was introduced, paper filters have regained attention from research institutions and cigarette manufacturers due to their outstanding advantages in reducing tar and harm, environmental protection, and economic cost.

[0003] Paper filter rods use paper made from plant fibers as their filter material, offering significant advantages in terms of environmental protection and cost-effectiveness. However, compared to cellulose acetate filter rods, paper filter rods suffer from higher draw resistance and poorer draw resistance stability. The poor draw resistance stability is primarily manifested in the large variations in draw resistance between different filter rods within a batch, resulting in a poor smoking experience. Analyzing the manufacturing processes of cellulose acetate and paper filter rods reveals that while both are formed by assembling the filter elements, their initial shapes differ. Cellulose acetate filter rods use cellulose acetate filaments assembled together, while paper filter rods use embossed paper strips of a certain width assembled together. Although the paper strips adhere tightly after assembly, noticeable gaps of varying sizes still exist, directly contributing to the lower draw resistance stability of paper filter rods compared to cellulose acetate filter rods. Summary of the Invention

[0004] The primary objective of this invention is to overcome the problem that paper filter rods made from the aforementioned paper materials have poor suction resistance stability, making them difficult to replace cellulose acetate filter rods. This invention provides a method for preparing paper filter materials. The paper filter material prepared by this invention maintains good air permeability and high bulk. Paper filter rods made from this material, as filter elements, have low suction resistance and good suction resistance stability, and can replace current cellulose acetate filter rods, balancing production costs, environmental friendliness, and suction experience.

[0005] A further object of the present invention is to provide a paper filter material.

[0006] A further object of the present invention is to provide the application of the above-mentioned paper filter material in the preparation of paper filter rods.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] A method for preparing a paper filter material includes the following steps:

[0009] S1. Prepare a pulp by combining flash-dried pulp, mercerized pulp, oven-dried pulp, and water;

[0010] S2. The pulp described in step S1 is sized internally, and then the pulp is formed, dehydrated and dried to obtain the base paper;

[0011] S3. Apply starch to the surface of the base paper described in step S2, and dry it to obtain the paper filter material;

[0012] The mass ratio of flash-dried pulp, mercerized pulp and oven-dried pulp in step S1 is (17-54):(46-83):(0-25);

[0013] The sizing agent selected for the sizing process in step S2 is a reactive sizing agent.

[0014] The plant fibers used in existing paper filter media are mainly dried pulp. Studies have found that paper filter rods made from paper filter media have poor suction resistance stability, which is not only related to the varying sizes of gaps after agglomeration and molding, but also to the relatively dense micropores of the paper filter media itself.

[0015] The inventors of this invention discovered through research that by compounding a certain amount of flash-dried pulp and mercerized pulp, and utilizing the high torsion index of both, the bulk of the paper filter material can be increased, thereby improving the micropores of the paper filter material and enhancing the suction resistance stability of the paper filter rod made from the paper filter material as a filter element. Too much flash-dried pulp will significantly reduce the air permeability of the paper filter material, resulting in high suction resistance and a poor suction experience. Conversely, too little flash-dried pulp will lead to poor dispersibility of the mercerized pulp, resulting in numerous flocculent fiber clusters and poor uniformity in the paper filter material, thus failing to improve suction resistance stability.

[0016] Furthermore, the paper filter material prepared from flash-dried pulp and mercerized pulp using the dosage ratio of the present invention has insufficient strength, thus requiring internal sizing and surface sizing. For internal sizing, a reactive internal sizing agent must be selected to provide sufficient wet strength. For surface sizing, starch must be selected as the sizing agent, which not only imparts a certain strength to the paper filter material but also maintains good flexibility, thereby reducing the formation of voids of varying sizes during agglomeration and improving the suction resistance stability of the paper filter rod made from the paper filter material as a filter element.

[0017] If starch is not used, and other surface sizing agents (such as polyethylene glycol, polyvinyl alcohol, acrylate, phenolic resin, etc.) are used instead, the suction resistance stability of paper filter rods made from paper filter media as filter elements cannot be effectively improved.

[0018] It should be understood that the cylinder-dried pulp of the present invention refers to pulp obtained after wet pulp has been dehydrated by pressing and then dried in a cylinder. Cylinder drying is a conventional method for drying pulp. The flash-dried pulp of the present invention refers to pulp obtained after wet pulp has undergone flash drying treatment.

[0019] In this invention, the mass ratio of flash-dried pulp to mercerized pulp in step S1 can be 17:83, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50 or 53:47.

[0020] Preferably, the mass ratio of flash-dried pulp, mercerized pulp, and cylinder-dried pulp in step S1 is (17-35):(65-83). Under this condition, the paper filter rod made from paper filter material as the filter element has lower suction resistance and better suction resistance stability.

[0021] Optionally, the torsion index of the flash-dried pulp in step S1 is 20% to 30%; specifically, it can be 20%, 23%, 25%, 28%, or 30%.

[0022] Optionally, the average fiber length of the flash-dried pulp in step S1 is 1.0 to 1.6 mm, the average width is 20 to 25 μm, and the average coarseness is 0.10 to 0.15 mg / m.

[0023] Optionally, the torsion index of the mercerized paste in step S1 is 20% to 35%; specifically, it can be 20%, 23%, 25%, 28%, 30%, 32%, or 35%.

[0024] Optionally, the average fiber length of the mercerized pulp in step S1 is 2.5–3.0 mm, the average width is 25–30 μm, and the average coarseness is 0.12–0.18 mg / m.

[0025] Optionally, the pulp dried in the drying cylinder in step S1 is at least one of hardwood pulp, softwood pulp, bagasse pulp, hemp pulp, straw pulp, or bamboo pulp.

[0026] Optionally, the average fiber length of the pulp dried in the drying cylinder in step S1 is 2.5-3.0 mm, the average width is 25-30 μm, and the average coarseness is 0.10-0.15 mg / m.

[0027] Optionally, the torsion index of the pulp dried in the drying cylinder in step S1 is 10% to 14%.

[0028] Preferably, the process parameters for preparing the slurry in step S1 are: slurry concentration of 3.0-5.0% and slurrying time of 25-60 min.

[0029] Preferably, the beating degree of the slurry in step S1 is 12-20°SR.

[0030] Optionally, the mass ratio of the sizing agent in the slurry to the fiber in the slurry in step S2 is (2-5):(95-98).

[0031] Optionally, the reactive sizing agent is at least one of polyamide epichlorohydrin resin or polyethyleneimine resin.

[0032] Optionally, the starch in step S3 is at least one of esterified starch, hydroxyethyl starch, or hydroxypropyl starch.

[0033] Preferably, the esterified starch is at least one of phosphate starch, acetate starch, or succinate starch.

[0034] Optionally, the mass ratio of starch to base paper in step S3 is (0.5-7):(93-99.5); preferably (3-5):(95-97).

[0035] Optionally, the drying process described in step S3 may further include slitting, embossing, and agglomeration.

[0036] Through slitting, embossing, and coalescing, it becomes a filter element.

[0037] A paper filter material is prepared by the above-described method.

[0038] The application of the aforementioned paper filter material in the preparation of paper filter rods is also within the scope of protection of this invention.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] The paper filter material prepared by the method of the present invention maintains good air permeability and high bulk. The paper filter rod made from it as a filter element has low suction resistance and good suction resistance stability, and can replace the current cellulose acetate filter rod, taking into account production cost, environmental protection and suction experience. Detailed Implementation

[0041] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0042] Example 1

[0043] This embodiment provides a method for preparing paper filter material, including the following steps:

[0044] 1) Flash-dried pulp (fiber average length 1.5 mm, average width 23.5 μm, average thickness 0.14 mg / m, twist index 24.1%), mercerized pulp (fiber average length 2.6 mm, average width 29.2 μm, average thickness 0.17 mg / m, twist index 32.6%), and water were mixed evenly at a mass ratio of 17:83:2400 to prepare the pulp.

[0045] 2) Add a 15wt% polyamide epichlorohydrin resin solution to the pulp obtained in step 1), mix evenly, and then form, press, dewater and dry on a paper machine to obtain the base paper; wherein, the mass ratio of polyamide epichlorohydrin resin in the polyamide epichlorohydrin resin solution to fiber in the pulp is 4:96.

[0046] 3) The base paper obtained in step 2) is surface-sized with a 3% aqueous solution of esterified starch (phosphate starch), dried, wound, and then slit into rolls with a width of 130 mm using a slitting machine to obtain the paper filter material. The mass ratio of esterified starch in the aqueous solution to base paper is 3:97.

[0047] Example 2

[0048] This embodiment provides a method for preparing paper filter material, which differs from Embodiment 1 in that: in step 1), flash-dried pulp, mercerized pulp and water are mixed evenly at a mass ratio of 53:47:2400 to obtain slurry.

[0049] Example 3

[0050] This embodiment provides a method for preparing paper filter material, which differs from Embodiment 1 in that: Step 1) specifically involves mixing flash-dried pulp (flash-dried pulp with an average fiber length of 1.2 mm, an average width of 22.5 μm, an average coarseness of 0.11 mg / m, and a torsion index of 28.2%), mercerized pulp (mercerized pulp with an average fiber length of 2.7 mm, an average width of 27.3 μm, an average coarseness of 0.13 mg / m, and a torsion index of 20.9%), cork pulp (with an average fiber length of 2.3 mm, an average width of 26.4 μm, an average coarseness of 0.11 mg / m, and a torsion index of 13.9%) and water at a mass ratio of 32:47:21:2400 to obtain a pulp material.

[0051] Example 4

[0052] This embodiment provides a method for preparing paper filter material, which differs from Embodiment 1 in that: flash-dried pulp, mercerized pulp and water are mixed evenly at a mass ratio of 35:65:2400 to obtain a pulp.

[0053] Example 5

[0054] This embodiment provides a method for preparing paper filter material, which differs from Embodiment 1 in that the reactive sizing agent is replaced by polyamide epichlorohydrin resin with polyethyleneimine resin.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing paper filter material, which differs from Example 1 in that: in step 1), flash-dried pulp, mercerized pulp and water are mixed evenly in a mass ratio of 10:83:2232 to obtain a slurry.

[0057] Comparative Example 2

[0058] This comparative example provides a method for preparing paper filter material, which differs from Example 1 in that: in step 1), flash-dried pulp, mercerized pulp and water are mixed evenly at a mass ratio of 63:47:2640 to obtain slurry.

[0059] Comparative Example 3

[0060] This comparative example provides a method for preparing paper filter material, which differs from Example 1 in that: in step 1), the flash-dried pulp and mercerized pulp are replaced with an equal amount of cork pulp (cylinder-dried pulp), and the cork pulp and water are mixed evenly at a mass ratio of 100:2400 to obtain the pulp.

[0061] Comparative Example 4

[0062] This comparative example provides a method for preparing paper filter material, which differs from Example 1 in that: in step 2), the reactive sizing agent is replaced with polyvinyl alcohol.

[0063] Comparative Example 5

[0064] This comparative example provides a method for preparing paper filter material, which differs from Example 1 in that: in step 3), esterified starch is replaced with polyethylene glycol.

[0065] Performance testing

[0066] The paper filter media of each embodiment and comparative example were tested:

[0067] (1) Paper filter material performance test: The basis weight of paper is determined according to GB / T 451.2-2023, the air permeability of paper is determined according to GB / T23227-2018, the tensile strength of paper is determined according to GB / T 12914-2018, and the thickness of paper is determined according to GB / T 451.3-2002.

[0068] The bulk thickness is calculated based on the thickness and basis weight using the following formula: Bulk thickness = Thickness * 1000 / Basis Weight. The unit for bulk thickness is cm. 3 / g; thickness is in mm; quantitative unit is g / m 2 .

[0069] (2) Performance test of paper filter rods

[0070] The paper filter materials of each embodiment and comparative example were unrolled, embossed, and formed into filter elements. These filter elements were then used in a filter rod forming machine to produce paper filter rods with the same process parameters. The filter rod specifications were 120 × 19.85 mm. The draw resistance and standard deviation were then measured using a filter rod draw resistance tester according to GB / T 22838-2009 "Determination of Physical Properties of Cigarettes and Filter Rods Part 5: Cigarette Draw Resistance and Filter Rod Pressure Drop". The data are shown in Table 1 below.

[0071] Table 1

[0072]

[0073] As can be seen from Table 1:

[0074] The paper filter media in Examples 1-5 all have an air permeability of over 13100 CU and a bulk thickness of 2.75 cm. 3 The paper filter rods made with a weight of 255 mmWG or less have a draw resistance of less than 255 mmWG and a draw resistance standard deviation of less than 13.1, indicating that the paper filter material of the present invention has good air permeability, and the paper filter rods made with it have low draw resistance and good draw resistance stability.

[0075] In Comparative Example 1, too little flash-dried pulp was added, resulting in poor suction resistance stability of the paper filter rods made from the resulting paper filter material. In Comparative Example 2, too much flash-dried pulp was added, leading to poor air permeability of the paper filter material and high suction resistance in the resulting paper filter rods. In Comparative Example 3, cylinder-dried pulp (softwood pulp) was used, resulting in low air permeability of the resulting paper filter material, high suction resistance, and poor suction resistance stability. In Comparative Example 4, a non-reactive in-pulp sizing agent was used, causing paper breakage during the papermaking process. In Comparative Example 5, polyethylene glycol was used as a surface sizing agent, resulting in poor suction resistance stability of the paper filter rods made from the resulting paper filter material.

[0076] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a paper filter material, characterized in that, Includes the following steps: S1. Prepare a pulp by combining flash-dried pulp, mercerized pulp, oven-dried pulp, and water; S2. The pulp described in step S1 is sized internally, and then the pulp is formed, dehydrated and dried to obtain the base paper; S3. Apply starch to the surface of the base paper described in step S2, and dry it to obtain the paper filter material; The mass ratio of flash-dried pulp, mercerized pulp and oven-dried pulp in step S1 is (17~54):(46~83):(0~25). The sizing agent used in step S2 is a reactive sizing agent. The torsion index of the flash-dried pulp in step S1 is 20%~30%; The torsion index of the mercerized paste described in step S1 is 20%~35%; The reactive sizing agent is at least one of polyamide epichlorohydrin resin or polyethyleneimine resin. The starch mentioned in step S3 is at least one of esterified starch, hydroxyethyl starch, or hydroxypropyl starch; In step S2, the mass ratio of the sizing agent in the slurry to the fiber in the slurry is (2~5):(95~98). In step S3, the mass ratio of starch to the base paper is (0.5~7):(93~99.5). The flash-dried pulp described in step S1 has an average fiber length of 1.0~1.6 mm, an average width of 20~25 μm, and an average coarseness of 0.10~0.15 mg / m. The average fiber length of the mercerized pulp in step S1 is 2.5~3.0 mm, the average width is 25~30 μm, and the average coarseness is 0.12~0.18 mg / m; The pulp dried in the drying cylinder in step S1 is at least one of hardwood pulp, softwood pulp, bagasse pulp, hemp pulp, straw pulp, or bamboo pulp; The average fiber length of the pulp dried in the drying cylinder in step S1 is 2.5~3.0 mm, the average width is 25~30 μm, and the average coarseness is 0.10~0.15 mg / m; The torsion index of the pulp dried in the drying cylinder in step S1 is 10%~14%; The process parameters for preparing the slurry in step S1 are: slurry concentration 3.0~5.0%, slurrying time 25~60min; The beating degree of the slurry in step S1 is 12~20°SR.

2. The preparation method according to claim 1, characterized in that, Step S3, after drying, also includes steps of slitting, embossing, and gathering and shaping.

3. A paper filter material, characterized in that, It is prepared by any of the preparation methods described in claims 1 to 2.

4. The use of the paper filter material according to claim 3 in the preparation of paper filter rods.

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