Paper filter material as well as preparation method and application thereof

Abstract

The invention relates to a paper filter material as well as a preparation method and application thereof. The preparation method of the paper filter material comprises the following steps: S1, preparing flash drying pulp, mercerizing pulp, paper pulp dried in a drying cylinder and water into pulp; s2, carrying out in-pulp sizing on the pulp obtained in the step S1, and then forming, dehydrating and drying to obtain raw paper; and S3, carrying out surface sizing on the raw paper in the step S2 by adopting starch, and drying to obtain the paper filter material. The paper filter material obtained through the preparation method keeps good air permeability and has high bulk, a paper filter tip rod made of the paper filter material serving as a filter element has low suction resistance and good suction resistance stability, an existing cellulose acetate fiber filter tip rod can be replaced, and production cost, environmental protection and suction experience are all considered.

Description

Technical Field

[0001] The present invention relates to the technical field of cigarette filter paper, and more specifically, to a paper filter material and a preparation method and application thereof. Background Art

[0002] At present, the filter rods used in cigarettes are generally acetate filter rods, that is, the filter element material of the filter rod is acetate. The production process of acetate fiber is complex, the production cost is high, it is not easy to degrade, and the interception efficiency of tar and nicotine in smoke is low when the filtration pressure drop is the same. Therefore, in recent years, especially since the release of the "paper instead of plastic" policy, paper filter rods have once again attracted the attention of scientific research institutions and cigarette companies due to their outstanding advantages in reducing tar and harm, environmental protection and economic costs.

[0003] The filter element material of the paper filter rod is paper made of plant fiber, which has obvious advantages in terms of environmental protection and economic cost. However, compared with the acetate filter rod, the paper filter rod has the problems of large suction resistance and poor suction resistance stability. Among them, the poor suction resistance stability is mainly reflected in the large difference in suction resistance between different filter rods within the batch, which leads to poor smoking experience of cigarettes. Regarding the problem of poor suction resistance stability, it is not difficult to find out from the preparation process of the filter element of the acetate filter rod and the paper filter rod that the filter element of the acetate filter rod and the paper filter rod are both formed by gathering, but the shapes of the two before gathering are different. The filter element of the acetate filter rod is formed by gathering acetate filaments, while the filter element of the paper filter rod is formed by embossing paper strips with a certain width. Although the interfaces of the paper strips after gathering are tightly fitted, there are still obvious gaps of different sizes, which directly leads to the poor suction resistance stability of the paper filter rod than that of the acetate filter rod. Summary of the invention

[0004] The primary purpose of the present invention is to overcome the problem that the paper filter tip made of the above-mentioned paper material has poor suction resistance stability, which makes it difficult to replace acetate fiber, and to provide a method for preparing a paper filter material. The paper filter material obtained by the preparation method of the present invention maintains good air permeability and has high bulk. The paper filter tip made of it as a filter element has low suction resistance and good suction resistance stability, and can replace the current acetate fiber filter tip, taking into account production cost, environmental protection 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 use of the above-mentioned paper filter material in the preparation of a paper filter rod.

[0007] The above-mentioned object of the present invention is achieved by the following technical solutions:

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

[0009] S1. Flash dried pulp, mercerized pulp, cylinder dried pulp and water are made into a slurry;

[0010] S2. performing internal sizing on the slurry in step S1, and then obtaining base paper after forming, dehydrating and drying;

[0011] S3. sizing the base paper in step S2 with starch and drying the base paper to obtain the paper filter material;

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

[0013] The internal sizing agent used in the internal sizing in step S2 is a reactive internal sizing agent.

[0014] The plant fiber used in existing paper filter materials is mainly dryer-dried pulp. Studies have found that the paper filter rods made of paper filter materials have poor absorption resistance stability, which is not only related to the gaps of different sizes after gathering and forming, but also related to the dense microscopic pores of the paper filter material itself.

[0015] The inventors of the present invention have found through research that by compounding a certain amount of flash dried pulp and mercerized pulp, and utilizing the high torsion index characteristics of both, the bulk of the paper filter material can be increased, thereby improving the microscopic pores of the paper filter material and enhancing the suction resistance stability of the paper filter rod made of the paper filter material as a filter element. The amount of flash dried pulp should not be too much, otherwise it will cause a significant decrease in the air permeability of the paper filter material, resulting in a large suction resistance of the paper filter rod and a poor suction experience; the amount of flash dried pulp should not be too little, otherwise the poor dispersibility of the mercerized pulp will cause the paper filter material to have many flocculated fiber clusters and poor uniformity, resulting in the inability to improve the suction resistance stability.

[0016] In addition, the strength of the paper filter material made of flash-dried pulp and mercerized pulp under the dosage ratio of the present invention is insufficient, so it is necessary to perform internal sizing and surface sizing. Among them, the internal sizing needs to use a reactive internal sizing agent to provide sufficient wet strength. The sizing agent for surface sizing needs to use starch, which can not only give the paper filter material a certain strength, but also enable the paper filter material to maintain good softness, thereby reducing the formation of gaps of different sizes during gathering and forming, and improving the suction resistance stability of the paper filter rod made of the paper filter material as a filter element.

[0017] If starch is not used but other surface sizing agents (such as polyethylene glycol, polyvinyl alcohol, acrylate, phenolic resin, etc.) are used, the suction resistance stability of the paper filter rod made of paper filter material as the filter element cannot be effectively improved.

[0018] It should be understood that the cylinder dried pulp of the present invention refers to the pulp obtained after wet pulp is squeezed and dehydrated and then dried by cylinder drying, which is a conventional drying method for pulp. The flash dried pulp of the present invention refers to the pulp obtained after wet pulp is flash dried.

[0019] In the present invention, the mass ratio of the flash dried pulp to the 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 of paper filter material as filter element has lower suction resistance and better suction resistance stability.

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

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

[0023] Optionally, the twist index of the mercerized pulp in step S1 is 20% to 35%, and specifically can be 20%, 23%, 25%, 28%, 30%, 32% or 35%.

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

[0025] Optionally, the cylinder dried pulp 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 by the cylinder in step S1 is 2.5-3.0 mm, the average fiber width is 25-30 μm, and the average fiber thickness is 0.10-0.15 mg / m.

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

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

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

[0030] Optionally, in step S2, the mass ratio of the sizing agent in the slurry to the fibers in the slurry 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, in step S3, the mass ratio of the starch to the base paper is (0.5-7):(93-99.5); preferably (3-5):(95-97).

[0035] Optionally, after drying in step S3, the steps of slitting, embossing and gathering are further included.

[0036] It is formed into a filter element through slitting, embossing and gathering.

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

[0038] The use of the above-mentioned paper filter material in the preparation of paper filter rods is also within the protection scope of the present invention.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The paper filter material obtained by the preparation method of the present invention maintains good air permeability and has high bulk. The paper filter rod made of the paper filter material as a filter element has low suction resistance and good suction resistance stability, and can replace the current acetate fiber filter rod, taking into account production cost, environmental protection and smoking experience. DETAILED DESCRIPTION

[0041] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0042] Example 1

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

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

[0045] 2) adding a polyamide epichlorohydrin resin solution having a concentration of 15 wt % to the slurry obtained in step 1), mixing them evenly, and then forming the paper on a paper machine, pressing and dehydrating the paper, and drying the paper to obtain base paper; wherein the mass ratio of the polyamide epichlorohydrin resin in the polyamide epichlorohydrin resin solution to the fiber in the slurry is 4:96;

[0046] 3) The base paper obtained in step 2) is subjected to surface sizing treatment with a 3% esterified starch (phosphate starch) aqueous solution, dried, rolled up, and then cut into coils with a width of 130 mm using a slitting machine to obtain a paper filter material. The mass ratio of the esterified starch in the esterified starch aqueous solution to the base paper is 3:97.

[0047] Example 2

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

[0049] Example 3

[0050] The present embodiment provides a method for preparing a paper filter material, which is different from the embodiment 1 in that: step 1) is specifically: flash dried pulp (the average fiber length of the flash dried pulp is 1.2 mm, the average width is 22.5 μm, the average thickness is 0.11 mg / m, and the twist index is 28.2%), mercerized pulp (the average fiber length of the mercerized pulp is 2.7 mm, the average width is 27.3 μm, the average thickness is 0.13 mg / m, and the twist index is 20.9%), softwood pulp (the average fiber length is 2.3 mm, the average width is 26.4 μm, the average thickness is 0.11 mg / m, and the twist index is 13.9%) and water are uniformly mixed in a mass ratio of 32:47:21:2400 to obtain a slurry.

[0051] Example 4

[0052] This embodiment provides a method for preparing a paper filter material, which is different from Embodiment 1 in that flash dried pulp, mercerized pulp and water are uniformly mixed in a mass ratio of 35:65:2400 to prepare a slurry.

[0053] Example 5

[0054] This embodiment provides a method for preparing a paper filter material, which is different from the first embodiment in that the reactive sizing agent in the pulp is replaced by a polyethyleneimine resin instead of a polyamide epichlorohydrin resin.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing a paper filter material, which is different from Example 1 in that: in step 1), flash dried pulp, mercerized pulp and water are uniformly mixed 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 a paper filter material, which is different from Example 1 in that: in step 1), flash dried pulp, mercerized pulp and water are uniformly mixed in a mass ratio of 63:47:2640 to prepare a slurry.

[0059] Comparative Example 3

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

[0061] Comparative Example 4

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

[0063] Comparative Example 5

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

[0065] Performance Testing

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

[0067] (1) Performance test of paper filter material The basis weight of paper is determined according to GB / T 451.2-2023, the air permeability of paper is determined according to GB / T 23227-2018, 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 is calculated based on the thickness and basis weight according to the following formula: bulk = thickness * 1000 / basis weight. In the formula, the unit of bulk is cm 3 / g; the unit of thickness is mm; the unit of quantity is g / m 2 .

[0069] (2) Paper filter rod performance test

[0070] The paper filter materials of each embodiment and comparative example were unrolled, embossed and gathered to form a filter element, and the filter element was made into a paper filter rod on a filter rod forming machine using the same process parameters, and the filter rod specification was: 120×19.85 mm. Then, the filter rod draw resistance tester was used to test the draw resistance and draw resistance standard deviation 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, and the data obtained were shown in the following Table 1.

[0071] Table 1

[0072]

[0073] From Table 1, we can see that:

[0074] The air permeability of the paper filter materials in Examples 1 to 5 is all above 13100 CU, and the bulk thickness is all 2.75 cm 3 / g or more, the absorption resistance of the prepared paper filter rods is all below 255mmWG, and the standard deviation of absorption resistance is all below 13.1, indicating that the paper filter material of the present invention has good air permeability, the prepared paper filter rods have small absorption resistance and good absorption resistance stability.

[0075] In Comparative Example 1, too little flash-dried pulp was added, and the paper filter rod made of the obtained paper filter material had poor absorption resistance stability. In Comparative Example 2, more flash-dried pulp was added, and the air permeability of the paper filter material was poor, and the absorption resistance of the obtained paper filter rod was large. In Comparative Example 3, cylinder-dried pulp (cork pulp) was used, and the air permeability of the obtained paper filter material was low, and the absorption resistance of the obtained paper filter rod was large and the absorption resistance stability was poor. In Comparative Example 4, the sizing agent in the pulp was non-reactive, and paper breakage occurred during the papermaking process. In Comparative Example 5, polyethylene glycol was used as the surface sizing agent, and the absorption resistance stability of the paper filter rod made of the paper filter material was poor.

[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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a paper filter material, characterized in that: The steps include: S1. Flash dried pulp, mercerized pulp, cylinder dried pulp and water are made into a slurry; S2. performing internal sizing on the slurry in step S1, and then obtaining base paper after forming, dehydrating and drying; S3. sizing the base paper in step S2 with starch and drying the base paper to obtain the paper filter material; The mass ratio of the flash dried pulp, mercerized pulp and cylinder dried pulp in step S1 is (17-54): (46-83): (0-25); The internal sizing agent used in the internal sizing in step S2 is a reactive internal sizing agent.

2. The preparation method according to claim 1, characterized in that: The torsion index of the flash dried pulp in step S1 is 20% to 30%.

3. The preparation method according to claim 1, characterized in that: The twist index of the mercerized pulp in step S1 is 20% to 35%.

4. The preparation method according to claim 1, characterized in that: The reactive internal sizing agent is at least one of polyamide epichlorohydrin resin and polyethyleneimine resin.

5. The preparation method according to claim 1, characterized in that: The starch in step S3 is at least one of esterified starch, hydroxyethyl starch or hydroxypropyl starch.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the sizing agent in the slurry to the fibers in the slurry in step S2 is (2-5):(95-98).

7. The preparation method according to claim 1, characterized in that: The mass ratio of the starch to the base paper in step S3 is (0.5-7): (93-99.5).

8. The preparation method according to claim 1, characterized in that: After drying, step S3 further includes the steps of slitting, embossing and gathering to form.

9. A paper filter material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the paper filter material according to claim 9 in preparing a paper filter rod.

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