Method for preparing high-strength and high-uniformity tobacco sheets by roller pressing

Abstract

The present invention relates to the technical field of tobacco sheets, and is mainly a method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method. The method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method of the present invention comprises the following steps: 1) mixing tobacco powder with an adhesive to obtain a dry material; 2) adding water to an external fiber, and pulping the mixture to obtain an external fiber slurry; 3) mixing an atomizer with the adhesive and the external fiber slurry to obtain a wet material; 4) mixing the dry material and the wet material to obtain a mixed material; the mixed material is a semi-dry solid bulk material or a semi-dry solid agglomerate material; 5) rolling and forming the mixed material, and drying the mixed material to obtain tobacco sheets. By adding adhesives separately during the preparation of dry and wet materials, and pulping the external fibers, it is beneficial for the external fibers to be evenly dispersed in the tobacco sheets, effectively reducing the number of white spots on the surface of the sheets, and improving the strength and uniformity of the rolled tobacco sheets, which is of great significance to promoting the application of domestically produced new rolled tobacco sheets in heat-not-burn tobacco products.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco sheets, in particular to a method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method. Background Art

[0002] In recent years, with the increasing global efforts to ban smoking in public places and the growing demand for health and fashion, sales of traditional tobacco products have shown a downward trend. New tobacco products, such as heat-not-burn (HNB) cigarettes and e-cigarettes, are rapidly emerging. These new tobacco products do not require combustion, significantly reducing the tar and other harmful components produced by traditional cigarettes. They are less harmful and do not produce secondhand smoke, thus minimizing the impact on the public environment. The core technology of HNB cigarettes primarily focuses on the cartridges and heating methods used in smoking devices. Tobacco flakes are currently the primary raw material for HNB cigarette cartridges, as they not only retain the active ingredients of natural tobacco leaves but also exhibit strong plasticity and a high degree of controllability.

[0003] New roller-pressed tobacco sheets are widely used in heat-not-burn cigarettes due to their shortened forming and drying time, minimal aroma and nicotine loss, and effective retention of tobacco's natural flavor components. They also offer excellent smoke generation, high density, and strong carrying capacity. The process primarily involves mixing tobacco powder, atomizer, binder, and water in a specific proportion, stirring them uniformly, rolling them, drying them, and then cutting them into shredded pieces. Because the roller-pressing process involves crushing and reshaping the tobacco raw material, the production formula requires the addition of adhesives and other additives to enhance strength and flexibility and reduce the breakage rate during processing. However, the addition of adhesives can easily cause problems such as sticking to the rollers, impacting production, and can also produce odors that affect the taste of the product, limiting the amount of adhesive that can be added. Therefore, additives are still needed to enhance the performance of the sheet. However, excessive additions result in poor dispersion uniformity and are prone to flocculation, resulting in white spots in the finished product. This not only affects the appearance of the sheet but also the smoke quality of the cigarette. Lower additions, however, yield less improvement in sheet performance. How to ensure uniform dispersion of added fibers while effectively improving sheet performance is an important issue that manufacturers urgently need to address. Summary of the Invention

[0004] In view of the problem in the prior art that the added fibers have poor dispersion and uniformity during the preparation of tobacco sheets by the roller pressing method, white spots are easily generated in the product, thereby affecting the strength of the product, the purpose of the present invention is to provide a method for preparing high-strength and high-uniformity tobacco sheets by the roller pressing method. The added fibers are evenly dispersed in the liquid material part through the techniques of ingredient sequence and preparation of the liquid material part, thereby solving the problem of uniform dispersion of the added fibers during the sheet preparation process, effectively reducing the number of "white spots" on the surface of the sheet product, enhancing the tensile strength of the new roller pressing method tobacco sheet while ensuring the stability of the product quality, and the method is simple to operate and low in cost.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0007] 1) mixing tobacco powder with an adhesive to obtain a dry material;

[0008] 2) adding water to the added fiber and performing pulping treatment to obtain an added fiber slurry;

[0009] 3) mixing the atomizer, the adhesive, and the added fiber slurry to obtain a wet material;

[0010] 4) mixing the dry material and the wet material to obtain a mixed material; the mixed material is a semi-dry solid bulk material or a semi-dry solid agglomerate material;

[0011] 5) The mixed material is rolled and formed, and dried to obtain tobacco sheets.

[0012] In some embodiments of the present invention, the weight of the adhesive in step 1) is 0-10% of the weight of the tobacco powder, and is greater than 0, preferably 4%-6%.

[0013] In some embodiments of the present invention, the adhesive is selected from one or a combination of sodium alginate, sodium carboxymethyl cellulose, chitosan, guar gum, etc.

[0014] In some embodiments of the present invention, the adhesive in step 1) is selected from sodium carboxymethyl cellulose, having a viscosity ranging from 2800 to 4000 mPa·s and a degree of substitution of 0.8 to 1.1; and / or, the adhesive in step 3) is selected from sodium carboxymethyl cellulose, having a viscosity ranging from 1000 to 1300 mPa·s and a degree of substitution of 0.9 to 1.0.

[0015] In some embodiments of the present invention, the added fiber is selected from coniferous wood pulp, preferably sulfate coniferous wood pulp or sulfite coniferous wood pulp.

[0016] In some embodiments of the present invention, the weight proportion of the added fiber in the added fiber slurry is 2% to 6%, preferably 3% to 5%.

[0017] In some embodiments of the present invention, the pulping process is specifically refining with a refiner.

[0018] In some embodiments of the present invention, the beating degree of the added fiber slurry ranges from 20 to 40°SR, preferably from 25 to 35°SR.

[0019] In some embodiments of the present invention, the wet weight of the added fiber slurry ranges from 5 to 20 g, preferably from 9 to 15 g.

[0020] In some embodiments of the present invention, the weight proportion of the atomizer in the wet material is 35% to 50%, the weight proportion of the adhesive is 0.1% to 3%, and the weight proportion of the added fiber slurry is 50% to 62%. Preferably, the weight proportion of the atomizer in the wet material is 38% to 48%, the weight proportion of the adhesive is 0.2% to 2%, and the weight proportion of the added fiber slurry is 50% to 60%.

[0021] In some embodiments of the present invention, the wet material is maintained at a temperature of 40 to 80°C, preferably 50 to 70°C.

[0022] In some embodiments of the present invention, step 3) further includes other auxiliary materials, and the order of adding the other auxiliary materials is after adding the fiber slurry.

[0023] In some embodiments of the present invention, the mixing order in step 3) is atomizer, adhesive, and additional fiber slurry, and stirring is performed after each mixing.

[0024] In some embodiments of the present invention, the stirring speed is 150-300 rpm; and / or the stirring time is 5-20 min.

[0025] In some embodiments of the present invention, the weight ratio of dry material to wet material in step 4) is 5:2-4.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The method for preparing high-strength and high-uniformity tobacco sheets by the roller pressing method provided by the present invention adds adhesives respectively during the preparation of dry and wet materials, and pulps the added fibers, thereby facilitating the uniform dispersion of the added fibers in the tobacco sheets, effectively reducing the number of white spots on the surface of the sheets, thereby improving the strength and uniformity of the tobacco sheets prepared by the roller pressing method, and enhancing the quality stability of the tobacco sheets prepared by the roller pressing method.

[0028] 2. The method for preparing high-strength and high-uniformity tobacco sheets by the roller pressing method provided by the present invention is simple to operate and can be achieved using existing equipment. The added fibers are evenly dispersed during the preparation of the tobacco sheets. The resulting product has high tensile strength and no obvious "white spots" on the surface. This is of great significance for promoting the application of domestically produced new roller-pressed tobacco sheets in heat-not-burn tobacco products. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figures show the dispersion of the added fibers in the wet materials obtained from the examples and comparative examples of the present invention, wherein a represents Example 1, b represents Example 2, c represents Example 3, d represents Example 4, and e represents Comparative Example 1.

[0030] Figure 2The uniformity characterization results of the products obtained from the examples and comparative examples of the present invention are shown in FIG. 1 , where a represents Example 1, b represents Example 2, c represents Example 3, d represents Example 4, and e represents Comparative Example 1. DETAILED DESCRIPTION

[0031] The method for preparing high-strength and high-uniformity tobacco sheets by the roller pressing method of the present invention is described in detail below.

[0032] In order to improve the strength and uniformity of tobacco sheets prepared by the roller pressing method, the inventors added the adhesive in two steps: mixing the adhesive with tobacco powder to prepare a dry material, and mixing the adhesive with an atomizer and an external fiber slurry to prepare a wet material. The inventors also synergistically improved the dispersion uniformity of the added fibers through the external fiber pulping process and a specific ingredient sequence, thereby making the tobacco sheets prepared by the roller pressing method have high strength and high uniformity.

[0033] The present invention provides a method for preparing high-strength and high-uniformity tobacco sheets by roller pressing, and the specific technical scheme is as follows:

[0034] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0035] 1) mixing tobacco powder with an adhesive to obtain a dry material;

[0036] 2) adding water to the added fiber and performing pulping treatment to obtain an added fiber slurry;

[0037] 3) mixing the atomizer, the adhesive, and the added fiber slurry to obtain a wet material;

[0038] 4) mixing the dry material and the wet material to obtain a mixed material; the mixed material is a semi-dry solid bulk material or a semi-dry solid agglomerate material;

[0039] 5) The mixed material is rolled and formed, and dried to obtain tobacco sheets.

[0040] In the present invention, steps 1) and 2) are performed in any order and can be adjusted. The method for preparing tobacco powder comprises: uniformly mixing tobacco raw materials according to a formula, and then pulverizing the mixture into tobacco powder having a desired particle size. Preferably, the particle size of the tobacco powder is 200-400 mesh. In the present invention, the added fiber raw materials are not particularly limited and can be any commonly used fiber in the papermaking field or in the production of paper-based tobacco sheets. The atomizer is not particularly limited and can be any commonly used atomizer in the art, such as 1,3-butanediol, or a combination of propylene glycol and / or glycerol with 1,3-butanediol. The adhesive added to the wet material in step 3) of the present invention primarily serves to disperse and thicken the material, promoting uniform dispersion of the added fibers and preventing agglomeration or precipitation of the added fibers. The resulting mixture in step 4) of the present invention is a semi-dry solid bulk or a semi-dry solid agglomerate, facilitating subsequent roll-forming.

[0041] In some embodiments of the present invention, the weight of the adhesive in step 1) is 0-10% of the weight of the tobacco powder, and is greater than 0, and can be 0-2%, 2%-4%, 4%-6%, 6%-8% or 8%-10%, preferably 4%-6%.

[0042] In some embodiments of the present invention, the adhesive is selected from one or a combination of sodium alginate, sodium carboxymethyl cellulose, chitosan, guar gum, etc.

[0043] In some preferred embodiments of the present invention, the adhesive in step 1) is selected from sodium carboxymethyl cellulose, having a viscosity range of 2800 to 4000 mPa·s and a degree of substitution of 0.8 to 1.1; and / or, the adhesive in step 3) is selected from sodium carboxymethyl cellulose, having a viscosity range of 1000 to 1300 mPa·s and a degree of substitution of 0.9 to 1.0.

[0044] In some embodiments of the present invention, the added fiber is selected from coniferous wood pulp, preferably sulfate coniferous wood pulp or sulfite coniferous wood pulp.

[0045] In some embodiments of the present invention, the weight proportion of the added fiber in the added fiber slurry is 2% to 6%, which can be 2% to 3%, 3% to 4%, 4% to 5%, 5% to 6%, or 2% to 4%, 3% to 5%, 4% to 6%, preferably 3% to 5%.

[0046] In some embodiments of the present invention, the pulping process is specifically refining with a refiner.

[0047] In some embodiments of the present invention, the beating degree of the added fiber slurry ranges from 20 to 40°SR, which can be 20 to 25°SR, 25 to 30°SR, 30 to 35°SR, 35 to 40°SR, or 20 to 30°SR, 25 to 35°SR, 30 to 40°SR, preferably 25 to 35°SR.

[0048] In some embodiments of the present invention, the wet weight range of the added fiber slurry is 5-20g, which can be 5-10g, 10-15g, 15-20g, or 5-11g, 6-12g, 7-13g, 8-14g, 9-15g, 10-16g, 11-17g, 12-18g, 13-19g, 14-20g, and preferably 9-15g.

[0049] In some embodiments of the present invention, the weight proportion of the atomizer in the wet material is 35% to 50%, the weight proportion of the adhesive is 0.1% to 3%, and the weight proportion of the added fiber slurry is 50% to 62%. Preferably, the weight proportion of the atomizer in the wet material is 38% to 48%, the weight proportion of the adhesive is 0.2% to 2%, and the weight proportion of the added fiber slurry is 50% to 60%.

[0050] In some embodiments of the present invention, the wet material is maintained at a temperature of 40-80°C, which may be 40-50°C, 50-60°C, 60-70°C, 70-80°C, or 40-60°C, 50-70°C, 60-80°C, preferably 50-70°C.

[0051] In some embodiments of the present invention, step 3) further includes other auxiliary materials, which are added after the fiber slurry is added. In the present invention, the other auxiliary materials include one or more of flavors, spices, combustion aids, calcium carbonate, preservatives, etc.

[0052] In some embodiments of the present invention, in step 3), the mixing order is atomizer, adhesive, and additional fiber slurry, and stirring is performed after each mixing. The present invention first mixes the atomizer with the adhesive to promote uniform distribution of adhesive particles, and then mixes with the additional fiber slurry. The water molecules in the atomizer and the slurry form strong hydration short chains through hydrogen bonds, and the strong hydration short chains are attached to the evenly distributed adhesive molecular chains through hydrogen bonds or van der Waals forces, so that a branch-like structure is formed on the adhesive molecular chain, and the molecular chain space density is increased, so that the dispersed state of the additional fiber is maintained, and the additional fiber flocculation or precipitation is prevented, which is conducive to the uniform dispersion of the additional fiber. The uniform dispersion of the additional fiber in the wet material is also conducive to the additional fiber in the subsequent mixed material to maintain a dispersed state, so that the strength and uniformity of the tobacco sheet prepared by the roller pressing method are improved.

[0053] In some embodiments of the present invention, the stirring speed is 150-300 rpm, which can be 150-200 rpm, 200-250 rpm, 250-300 rpm, and preferably 200-250 rpm. In some embodiments of the present invention, the stirring time is 5-20 min, which can be 5-10 min, 10-15 min, or 15-20 min.

[0054] In some embodiments of the present invention, the weight ratio of dry material to wet material in step 4) is 5:2-4, or can be 5:2-2.5, 5:2.5-3 or 5:3.5-4, which is conducive to forming semi-dry solid bulk material or semi-dry solid agglomerate material after mixing.

[0055] In some embodiments of the present invention, the roll forming comprises multi-stage roll forming, preferably 4 to 6 stages.

[0056] Below in conjunction with preferred embodiment, the specific embodiment of the present invention is described in further detail.When embodiment provides numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected.Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art.Except the specific method, equipment, material used in the embodiment, as those skilled in the art grasp the prior art and record of the present invention, any method, equipment and material of the prior art similar or equivalent to the method, equipment, material in the embodiments of the present invention can also be used to realize the present invention.

[0057] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, "the method includes steps 1) and 2)" means that the method may include steps 1) and 2) performed sequentially, or may include steps 2) and 1) performed sequentially.

[0058] In the following examples and comparative examples, the testing methods for various properties are as follows:

[0059] The viscosity of the adhesive is tested in accordance with GB1886.232-2016 "National Food Safety Standard Food Additive Sodium Carboxymethyl Cellulose". The larger the value, the higher the viscosity.

[0060] The tensile strength test of the product is carried out in accordance with GB / T12914 "Paper and board - Determination of tensile strength - Constant rate of tension method". The larger the value, the better the rigidity (tensile strength).

[0061] The characterization of product uniformity is carried out in accordance with YC / T16-2014 "Reconstituted Tobacco Leaves". Ten 100×100mm thin slice samples are randomly selected, and the number of white spots with a diameter greater than 2.0mm on the samples is measured and counted with a ruler. The arithmetic mean of the number of white spots on the 10 samples is rounded to an integer to represent the number of white spots in the batch of reconstituted tobacco leaves. The smaller the value, the higher the uniformity.

[0062] Example 1

[0063] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0064] S1. After crushing tobacco raw material, adding adhesive, mixing and stirring uniformly to prepare dry material; wherein the weight of adhesive is 4% of the weight of tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 2800 mPa·s and a degree of substitution of 0.8.

[0065] S2. The added fiber is mixed with water to form a slurry, and the added fiber slurry is obtained by pulping; wherein, the weight of the added fiber in the added fiber slurry accounts for 3%, the added fiber is coniferous wood pulp, and the pulping process adopts a pulping machine to refine the pulp. The added fiber slurry obtained by pulping has a beating degree of 25°SR and a wet weight of 9 g.

[0066] S3, the atomizer, adhesive, and added fiber slurry are mixed in proportion and order, and stirred evenly to obtain a wet material (such as Figure 1 (shown in a); the wet material comprises 38% by weight of atomizer, 2% by weight of adhesive, and 60% by weight of added fiber slurry. The wet material is maintained at 50°C. The materials are added in the following order: atomizer, adhesive, and added fiber slurry. Each material is stirred for 5 minutes before adding the next. The adhesive used is sodium carboxymethyl cellulose with a viscosity of 1000 mPa·s and a degree of substitution of 0.9.

[0067] S4. The dry material and the wet material are mixed in a weight ratio of 5:2 to prepare a mixed material, wherein the mixed material is a semi-dry solid bulk material.

[0068] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0069] Example 2

[0070] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0071] S1. After crushing tobacco raw material, adding adhesive, mixing and stirring uniformly to prepare dry material; wherein the weight of adhesive is 5% of the weight of tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 3400 mPa·s and a degree of substitution of 0.95.

[0072] S2. The added fiber is mixed with water to form a slurry, and the added fiber slurry is obtained by pulping; wherein, the weight of the added fiber in the added fiber slurry accounts for 4%, the added fiber is coniferous wood pulp, and the pulping process adopts a pulping machine to refine the pulp. The added fiber slurry obtained by pulping has a beating degree of 30°SR and a wet weight of 12 g.

[0073] S3, the atomizer, adhesive, and added fiber slurry are mixed in proportion and order, and stirred evenly to obtain a wet material (such as Figure 1 (shown in b); the wet material comprises 43% by weight of atomizer, 1% by weight of adhesive, and 56% by weight of added fiber slurry. The wet material is maintained at 60°C. The materials are added in the following order: atomizer, adhesive, and added fiber slurry. Each material is stirred for 15 minutes before the next addition. The adhesive used is sodium carboxymethyl cellulose, with a viscosity of 1150 mPa·s and a degree of substitution of 0.95.

[0074] S4. The dry material and the wet material are mixed in a weight ratio of 5:3 to prepare a mixed material, wherein the mixed material is a semi-dry solid mass material.

[0075] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0076] Example 3

[0077] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0078] S1. After crushing the tobacco raw material, adding an adhesive, mixing and stirring uniformly to prepare a dry material; wherein the weight of the adhesive is 6% of the weight of the tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 4000 mPa·s and a degree of substitution of 1.1.

[0079] S2. The added fiber is mixed with water to form a slurry, and the added fiber slurry is obtained by pulping; wherein, the weight of the added fiber in the added fiber slurry accounts for 5%, the added fiber is coniferous wood pulp, and the pulping process adopts a pulping machine to refine the pulp. The added fiber slurry obtained by pulping has a beating degree of 35°SR and a wet weight of 15g.

[0080] S3, the atomizer, adhesive, and added fiber slurry are mixed in proportion and order, and stirred evenly to obtain a wet material (such as Figure 1 (c in the figure); the wet material comprises 48% by weight of atomizer, 0.2% by weight of adhesive, and 51.8% by weight of added fiber slurry. The wet material is maintained at 70°C. The materials are added in the following order: atomizer, adhesive, and added fiber slurry. Each material is stirred for 20 minutes before the next addition. The adhesive used is sodium carboxymethyl cellulose with a viscosity of 1300 mPa·s and a degree of substitution of 1.0.

[0081] S4. The dry material and the wet material are mixed in a weight ratio of 5:4 to prepare a mixed material, wherein the mixed material is a semi-dry solid mass material.

[0082] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0083] Example 4

[0084] A method for preparing high-strength and high-uniformity tobacco sheets by a roller pressing method comprises the following steps:

[0085] S1. After crushing tobacco raw material, adding adhesive, mixing and stirring uniformly to prepare dry material; wherein the weight of adhesive is 5% of the weight of tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 3400 mPa·s and a degree of substitution of 0.95.

[0086] S2. The added fiber is mixed with water to form a slurry, and the added fiber slurry is obtained by pulping; wherein, the weight of the added fiber in the added fiber slurry accounts for 4%, the added fiber is coniferous wood pulp, and the pulping process adopts a pulping machine to refine the pulp. The added fiber slurry obtained by pulping has a beating degree of 30°SR and a wet weight of 12 g.

[0087] S3, the atomizer, the added fiber slurry, and the adhesive are mixed in proportion and order, and stirred evenly to obtain a wet material (such as Figure 1 (shown in d); the wet material comprises 43% by weight of atomizer, 1% by weight of adhesive, and 56% by weight of added fiber slurry. The wet material is maintained at 60°C. The materials are added in the following order: atomizer, added fiber slurry, and adhesive. Each material is stirred for 50 minutes before the next addition. The adhesive used is sodium carboxymethyl cellulose, with a viscosity of 1150 mPa·s and a degree of substitution of 0.95.

[0088] S4. The dry material and the wet material are mixed in a weight ratio of 5:3 to prepare a mixed material, wherein the mixed material is a semi-dry solid mass material.

[0089] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0090] Comparative Example 1

[0091] A method for preparing high-strength and high-uniformity tobacco sheets by roller pressing is the same as in Example 2 except that no adhesive is added in step S3, and comprises the following steps:

[0092] S1. After crushing tobacco raw material, adding adhesive, mixing and stirring uniformly to prepare dry material; wherein the weight of adhesive is 5% of the weight of tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 3400 mPa·s and a degree of substitution of 0.95.

[0093] S2. The added fiber is mixed with water to form a slurry, and the added fiber slurry is obtained by pulping; wherein, the weight of the added fiber in the added fiber slurry accounts for 4%, the added fiber is coniferous wood pulp, and the pulping process adopts a pulping machine to refine the pulp. The added fiber slurry obtained by pulping has a beating degree of 30°SR and a wet weight of 12 g.

[0094] S3, the atomizer and the added fiber slurry are mixed in proportion and order, and stirred evenly to obtain a wet material (such as Figure 1 (e) The weight proportion of the atomizer in the wet material was 43.43%, and the weight proportion of the added fiber slurry was 56.57%. The wet material temperature was maintained at 60°C. The order of adding the materials was atomizer, then the added fiber slurry. Each material was stirred for 15 minutes before adding the next material.

[0095] S4. The dry material and the wet material are mixed in a weight ratio of 5:3 to prepare a mixed material, wherein the mixed material is a semi-dry solid mass material.

[0096] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0097] Comparative Example 2

[0098] A method for preparing high-strength and high-uniformity tobacco sheets by roller pressing is the same as in Example 2 except that no external fiber slurry is added in step S3, and includes the following steps:

[0099] S1. After crushing tobacco raw material, adding adhesive, mixing and stirring uniformly to prepare dry material; wherein the weight of adhesive is 5% of the weight of tobacco raw material, and the adhesive used is sodium carboxymethyl cellulose, with a viscosity of 3400 mPa·s and a degree of substitution of 0.95.

[0100] S3. Mix the atomizer and adhesive in the correct proportions and order, stirring thoroughly to prepare a wet material. The atomizer accounts for 97.73% by weight of the wet material, and the adhesive accounts for 2.27% by weight. Maintain the wet material at 60°C. Add the materials in the order of atomizer, then adhesive. Stir each material for 15 minutes before adding the next. The adhesive used is sodium carboxymethyl cellulose, with a viscosity of 1150 mPa·s and a degree of substitution of 0.95.

[0101] S4. The dry material and the wet material are mixed in a weight ratio of 5:3 to prepare a mixed material, wherein the mixed material is a semi-dry solid mass material.

[0102] S5. Roll-forming and drying the mixture to obtain tobacco sheets.

[0103] Evaluation results

[0104] The tobacco sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to tensile strength testing and uniformity characterization. The tensile strength test structure is shown in Table 1 below:

[0105] Table 1 Evaluation results of tensile strength of products obtained from Examples 1 to 4 and Comparative Examples 1 to 2

[0106] Evaluation Project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Tensile strength KN / m 0.21 0.22 0.20 0.19 0.19 0.14

[0107] As shown in Table 1, the tobacco sheet products obtained in Examples 1 to 4 have good tensile strength. The tensile strength of the tobacco sheet prepared by the roller pressing method after adding the additional fiber slurry is significantly improved compared to the tobacco sheet without the addition of the additional fiber, by about 50%. The tensile strength of Example 4 and Comparative Example 1 is slightly lower than that of Examples 1 to 3. It is speculated that the reason may be that the tensile strength of Example 4 is slightly reduced after the addition order is changed (adding the additional fiber slurry first, then adding the adhesive). This may be because the addition order affects the dispersibility of the additional fiber, which in turn affects the strength of the tobacco sheet. Comparative Example 1 is caused by the lack of adhesive in the wet material. Comparative Example 2 has a significantly lower tensile strength due to the lack of the addition of the additional fiber slurry.

[0108] Depend on Figure 1 The dispersion uniformity of the added fibers in the wet materials prepared in Examples 1 to 4 and Comparative Example 1 shows that the added fibers in the wet materials prepared in Examples 1 to 3 are evenly dispersed ( Figure 1 a~c), there is no obvious flocculation; while in Example 4, after changing the addition order (adding the additional fiber slurry first, then adding the adhesive), Figure 1 In the example d, it can be seen that the added fiber aggregates significantly in the wet material, and the stirring time is extended to more than 3 times that of Example 2; in the comparative example 1, no adhesive is added to the wet material. Figure 1 In figure e, it can be seen that the added fibers are obviously aggregated. Figure 2 The surface "white spots" of the tobacco sheet products prepared in Examples 1 to 4 and Comparative Example 1 show that the surface of the products obtained in Examples 1 to 3 has no obvious flocculation "white spots" ( Figure 2 a~c); and after changing the order of addition in Example 4 (adding the additional fiber slurry first, then adding the adhesive), Figure 2 In the middle, we can see that there are obvious "white spots" in the wet material, about 7 / 100cm 2 The surface of the sheet of Comparative Example 1 has fiber flocculation phenomenon, and the density of "white spots" is about 5 / 100cm 2 The results show that adding adhesives with a viscosity of 1000-1300 mPa·s in a certain order during the preparation of the wet material can improve the dispersion uniformity of the external fibers in the wet material, thereby improving the dispersion uniformity of the added fibers in the roller-pressed tobacco sheets and improving the strength and quality stability of the finished sheets.

[0109] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing high-strength and high-uniformity tobacco sheets by roller pressing, characterized in that: The following steps are involved: 1) mixing tobacco powder and an adhesive to obtain a dry material; the weight of the adhesive is 0-10% of the weight of the tobacco powder and is greater than 0; the adhesive is selected from sodium carboxymethyl cellulose, has a viscosity range of 2800-4000 mPa·s, and a degree of substitution of 0.8-1.1; 2) adding water to the added fiber and performing pulping treatment to obtain an added fiber slurry; 3) mixing an atomizer with an adhesive and an additional fiber slurry to obtain a wet material; the adhesive is selected from sodium carboxymethyl cellulose, having a viscosity range of 1000-1300 mPa·s and a degree of substitution of 0.9-1.0; the mixing order is atomizer, adhesive, and additional fiber slurry, and stirring is performed after each mixing; 4) Mixing the dry material and the wet material to obtain a mixed material; the mixed material is a semi-dry solid bulk material or a semi-dry solid agglomerate material; 5) The mixed material is rolled and formed, and dried to obtain tobacco sheets.

2. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, characterized in that: In step 1), the weight of the adhesive is 4% to 6% of the weight of the tobacco powder.

3. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, characterized in that: Include one or more of the following characteristics: (1) The added fiber is selected from softwood pulp; (2) The weight proportion of the added fiber in the added fiber slurry is 2% to 6%; (3) The pulping process specifically comprises refining the pulp using a refiner; (4) The beating degree of the added fiber slurry is in the range of 20 to 40°SR; (5) The wet weight of the added fiber slurry ranges from 5 to 20 g.

4. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, wherein: Include one or more of the following characteristics: (a) The weight proportion of the atomizer in the wet material is 35% to 50%, the weight proportion of the adhesive is 0.1% to 3%, and the weight proportion of the added fiber slurry is 50% to 62%; (b) The wet material is maintained at a temperature of 40-80°C.

5. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, characterized in that: Step 3) also includes other auxiliary materials, which are added after the fiber slurry.

6. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, characterized in that: In step 3), the stirring speed is 150-300 rpm; and / or the stirring time is 5-20 min.

7. The method for preparing high-strength and high-uniformity tobacco sheets by roller pressing according to claim 1, characterized in that: In step 4), the weight ratio of dry material to wet material is 5:2~4.

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