A method for producing a fine cut rolling paper

Abstract

The application belongs to the technical field of cigarette materials, and particularly relates to a preparation method of a fine cigarette paper; the method comprises the following steps: (1) selecting long needle-leaf wood fibers and short broad-leaf wood fibers as papermaking fibers; respectively crushing needle-leaf wood pulp plates and broad-leaf wood pulp plates, and then performing disc grinding and beating; mixing the two kinds of pulp according to a certain proportion, adding calcium carbonate, uniformly mixing, and then removing slag to obtain pulp; (2) performing dehydration, molding, pressing, and wet paper forming on the pulp in step (1), and then performing drying; during the drying process, an additive is added into the paper through sizing; after drying, the paper is wound, rewound, and cut to obtain the cigarette paper; by increasing the ratio of long fibers to short fibers, the proportion of long fibers is increased, which is helpful to improve the stiffness and physical indexes of the cigarette paper.

Description

Technical Field

[0001] This invention belongs to the field of cigarette material technology, specifically relating to a method for preparing slim cigarette paper. Background Technology

[0002] Cigarette paper is the special paper used to wrap tobacco shreds to make cigarettes. It is mainly composed of plant fibers, inorganic fillers, and papermaking additives. Cigarette papers made from different fiber types have different microscopic physical structures, which may lead to differences in cigarette paper strength, coefficient of variation of air permeability, and diffusion rate, thus potentially affecting the sensory quality and other indicators of cigarettes. Regular cigarette paper accounts for 3-5% of the cigarette's weight, while slim cigarette paper accounts for 8-10%. Because slim cigarettes are thinner, they have less tobacco filling than medium and regular cigarettes, resulting in a lower degree of stiffness. Summary of the Invention

[0003] This invention addresses the technical problem of reduced stiffness in slim cigarettes due to lower tobacco content, by providing a method for preparing slim cigarette paper. This method improves the stiffness of the slim cigarette paper without affecting its basis weight or air permeability.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing slim cigarette paper, comprising the following steps:

[0005] (1) Select long softwood fibers and short hardwood fibers as papermaking fibers; crush softwood pulp board and hardwood pulp board separately and then grind them into pulp; mix the two pulps in a certain proportion and add calcium carbonate, mix evenly and remove residue to obtain pulp;

[0006] (2) The pulp from step (1) is dehydrated, formed, pressed, and shaped into wet paper and then dried. During the drying process, sizing agents are added into the paper. After drying, the paper is rolled, rewound, and cut to obtain cigarette paper.

[0007] Furthermore, the mass ratio of the long coniferous fibers to the short broadleaf fibers in step (1) is 4:6.

[0008] Furthermore, the amount of fiber added in step (1) accounts for 65%-70% of the weight of the cigarette paper.

[0009] Furthermore, the calcium carbonate mentioned in step (1) is light calcium carbonate with a pH value of 7-10, and the particle size D(4,3) and D(50) values ​​of the calcium carbonate are adjusted to 4.1 and 3.3 respectively; the amount of calcium carbonate added accounts for 20%-30% of the weight of cigarette paper.

[0010] Furthermore, in step (1), the long fiber was pulped 5 times, with the power maintained at 165kw, and the pressure from the first to the fifth time was 1.9bar, 3.3bar, 2.7bar, 3.1bar, and 3.6bar respectively.

[0011] Furthermore, the amount of the additives added in step (2) is 0.5%-3.0% of the weight of the cigarette paper.

[0012] Furthermore, the additive mentioned in step (2) is a mixture of potassium citrate, potassium malate, and sodium citrate, wherein the molar ratio of K to Na in the additive is 1.2:1. The combustion improver is used to enhance combustion.

[0013] Furthermore, in step (2), the papermaking process of the screen section is improved by extending the water line of the screen section and moving it back by 40 cm.

[0014] Furthermore, in step (2) during the pressing process, the paper machine parameters are controlled, the roll speed ratio is adjusted to 0.15%, the first pressing pressure is 46 bar, the second pressing pressure is 46 bar, and the engraving pressure is 47 bar.

[0015] The cigarette paper prepared using the above process has enhanced stiffness, thus improving the stiffness of slim cigarette paper.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This invention utilizes a combination of long and short fibers. The long fibers from coniferous trees have an average length of 2.5-3.5 mm and are prone to fibrillation, acting as a skeleton and support in cigarette paper, directly influencing its various strength properties. The short fibers from broadleaf trees have an average length of 0.5-1.0 mm, providing reinforcement and filling, helping to improve the uniformity, opacity, and air permeability of the cigarette paper. By increasing the ratio of long to short fibers, the proportion of long fibers is increased, which helps to improve the stiffness and physical properties of the cigarette paper.

[0018] This invention uses lightweight calcium carbonate, which has several advantages: it increases the refractive index of cigarette paper, making it impossible to see tobacco shreds when looking from the outside of the cigarette, thus preventing "background exposure" and increasing opacity; during cigarette combustion, the calcium carbonate decomposes into carbon dioxide upon heating, regulating the combustion process and preventing the cigarette from going out, thus controlling the combustion speed; it increases the whiteness of the cigarette paper, as calcium carbonate has a higher whiteness than wood pulp, with imported calcium carbonate reaching 95% whiteness and domestically produced calcium carbonate exceeding 92%; it increases the paper's air permeability, thereby reducing the tar content of cigarettes and minimizing harmful substances; and the price of calcium carbonate is lower than that of pulp, saving valuable fiber raw materials and achieving better paper quality at a lower cost. Furthermore, the lightweight calcium carbonate used in this invention has a pH value between 7 and 10, resulting in larger particle sizes D(4,3) and D(50) values, but a smaller difference between them, leading to a more concentrated particle size distribution, which is beneficial for enhancing the stiffness of the paper. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Example

[0021] A method for preparing slim cigarette paper includes the following steps:

[0022] (1) Softwood long fibers and hardwood short fibers were selected as papermaking fibers. Softwood pulp boards and hardwood pulp boards were crushed and then milled. The two pulps were mixed in a certain proportion, and calcium carbonate was added. After mixing evenly, the residue was removed. The mixture of softwood long fibers and hardwood short fibers accounted for 68% of the mass of cigarette paper, with a ratio of 4:6. Light calcium carbonate with a pH of 7-10 was selected. The particle size D(4,3) and D(50) values ​​of the calcium carbonate were adjusted to increase to 4.1 and 3.3 respectively, but the difference between the two values ​​was smaller, resulting in a more concentrated particle size distribution. The mass of calcium carbonate accounted for 30% of the mass of cigarette paper.

[0023] The long fiber was pulped five times, with the power maintained at 165kw. The pressure from the first to the fifth time was 1.9 bar, 3.3 bar, 2.7 bar, 3.1 bar, and 3.6 bar, respectively.

[0024] (2) The pulp obtained in step (1) is dehydrated, shaped, pressed, and formed into wet paper, then dried. During the drying process, sizing agents are added to the paper. After drying, the paper is rolled, rewound, and slit to obtain cigarette paper. The sizing agent is a mixture of potassium citrate, potassium malate, and sodium citrate, with a K:Na ratio of 1.2:1. The mass of the sizing agent accounts for 2% of the mass of the cigarette paper.

[0025] The wire section papermaking process further improves paper uniformity and reduces the loss of fine fibers and filler CaCO3 by extending the water line of the pulp wire section by 40 cm.

[0026] The paper machine control process adjusts the roll speed ratio to 0.15%, the primary pressure transmission pressure to 46 bar, the secondary pressure transmission pressure to 46 bar, and the engraving pressure transmission pressure to 47 bar to ensure production stability.

[0027] Comparative Example

[0028] The detailed steps are the same as in the embodiment, the only difference being the specific parameters in the tables below (Tables 1-1, 1-2, 1-2, 1-4).

[0029] Table 1-1 Physical properties of light calcium carbonate in the examples and comparative examples

[0030]

[0031] Note: D(4,3) is the volume average particle size, D(50) is the particle size smaller than this value that accounts for 50% of the total volume, and D(4,3)-D(50) is the difference between the two.

[0032] Table 1-2 Long fiber pulping process parameters for the examples and comparative examples

[0033]

[0034] Table 1-3 Mesh process parameters of the examples and comparative examples

[0035] Parameter Sample Comparative Example Example <![CDATA[CaCO 3 flow rate (L / min)]]> 21 28 <![CDATA[CaCO3 pH value]]> 7.80 8.17 Sizing concentration (%) 1.2 1.2 <![CDATA[1# Suction box (-mmH2O)]]> 344 311 <![CDATA[2# Suction box (-mmH2O)]]> 80 71 <![CDATA[3# Suction box (-mmH2O)]]> 70 50 <![CDATA[4# Suction box (-mmH2O)]]> 68 53 <![CDATA[5# Suction box (-mmH2O)]]> 55 40 <![CDATA[6# Suction box (-mmH2O)]]> 58 38 <![CDATA[7# Suction box (-mmH2O)]]> 60 42 <![CDATA[8# Suction box (-mmH2O)]]> 50 45 <![CDATA[9# Suction box (-mmH2O)]]> 55 40 <![CDATA[10# Suction box (-mmH2O)]]> 52 35

[0036] Table 1-4 Paper machine control process parameters for the examples and comparative examples

[0037] Parameter Sample Comparative Example Example Roller speed ratio (%) 0.80 0.15 One-pressure operation transmits pressure (bar). 48 46 Two-bar pressure transmission 48 46 Engraving and printing pressure (bar) 49 47

[0038] The physical properties of the cigarette paper prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 2.

[0039] Table 2 Comparison of Physical Properties of Cigarette Paper

[0040]

[0041] The physical properties of the embodiments of the present invention are all within the normal range, but the tensile energy absorption value is significantly enhanced, indicating that the physical strength of the cigarette paper has increased under the premise of the same basis weight and air permeability.

[0042] The stiffness of the cigarette paper samples from the examples and comparative examples was tested using a Swedish Model 160 bending stiffness tester. The test results are shown in Table 3 below.

[0043] Table 3. Results of cigarette paper stiffness test (unit: mN)

[0044] Test sample 5mm bending moment 10mm bending moment 15mm bending moment 20mm bending moment 25mm bending moment Comparative Example 364.0 128.5 59.6 35.2 23.0 Example 389.6 143.8 61.8 38.0 25.7

[0045] Analysis of the data in Table 3 shows that optimizing the raw materials and production process parameters of cigarette paper improves the stiffness of the cigarette paper. This invention improves the stiffness of cigarette paper by screening fiber raw materials and fillers, and by changing the fiber structure and fiber ratio, thereby meeting the stiffness requirements of slim cigarettes.

Claims

1. A method for preparing slim cigarette paper, characterized in that, Includes the following steps: (1) Select softwood long fibers and hardwood short fibers as papermaking fibers; break up softwood pulp boards and hardwood pulp boards respectively and then grind them in a disc mill, pulp them, and pulp the medium and long fibers 5 times, with the power maintained at 165kw and the pressure from the first to the fifth time being 1.9bar, 3.3bar, 2.7bar, 3.1bar and 3.6bar respectively; mix the two pulps in a certain proportion and add calcium carbonate, mix evenly and remove slag to obtain pulp; the mass ratio of softwood long fibers to hardwood short fibers is 4:6; the calcium carbonate is light calcium carbonate with a pH value of 7-10, and the particle size D(4,3) and D(50) values ​​of calcium carbonate are adjusted to 4.1 and 3.3 respectively; the amount of calcium carbonate added accounts for 20%-30% of the weight of cigarette paper; (2) The pulp from step (1) is dewatered, formed, pressed, and formed into a wet paper shape and then dried. During the drying process, sizing agents are added into the paper. After drying, the paper is rolled, rewound, and cut to obtain cigarette paper. The amount of the added agent accounts for 0.5%-3.0% of the weight of the cigarette paper. The added agent is a mixture of potassium citrate, potassium malate, and sodium citrate. The molar ratio of K to Na in the added agent is 1.2:

1. In the wire forming process, the water line of the pulp wire section is extended and moved back by 40 cm. In the pressing process, the paper machine parameters are controlled, and the roll speed ratio is adjusted to 0.15%, the first pressing pressure is 46 bar, the second pressing pressure is 46 bar, and the engraving pressure is 47 bar.

2. The method for preparing a slim cigarette paper according to claim 1, characterized in that, The amount of fiber added in step (1) accounts for 65%-70% of the weight of cigarette paper.

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