Traditional Lanpavilion cocoon paper and preparation method thereof

Abstract

The invention relates to the technical field of pulping and papermaking, in particular to traditional Lanpavilion cocoon paper and a preparation method thereof. The preparation method of the traditional Lanting cocoon paper comprises the following steps: pretreating and selecting raw materials; carrying out two-stage chemical cooking; washing and fiber decomposition; pulping and preparing pulp; and performing papermaking and drying to obtain the traditional Lanpavilion cocoon paper. The traditional Lanting cocoon paper (mulberry paper) prepared by adopting the technical scheme is excellent in fiber purity, ageing resistance, mechanical strength and the like, the whiteness is greater than or equal to 60%, the ageing-resistant whiteness is reduced by less than or equal to 0.5%, the tearability is greater than or equal to 1560 mN, and the dust degree is less than or equal to 50 pieces / m < 2 >; the style and appearance of traditional famous paper are restored, and a feasible process path is provided for modern production of high-quality handmade paper.

Description

Technical Field

[0001] This invention relates to the field of pulp and paper technology, and more specifically, to a traditional Lanting cocoon paper and its preparation method. Background Technology

[0002] Lanting Cocoon Paper (Mulberry Bark Paper) is one of the representative famous papers of ancient China, highly praised by scholars for its delicate texture and strong toughness. However, the traditional production process of Lanting Cocoon Paper (Mulberry Bark Paper) is extremely complex. Mulberry bark paper is a traditional handmade product made from the bark of the mulberry tree, through processes such as felling, soaking, peeling, boiling, filtering, pounding, fermentation, and papermaking. It is highly dependent on experience in raw material processing and papermaking techniques, resulting in a long production cycle and poor quality stability.

[0003] Patent 201710438964.8 discloses a type of mulberry bark paper made from mugwort leaves, its preparation process, and its uses. The process involves soaking and steaming dried mulberry bark, then soaking it in lime water with a mass concentration of 15% to 40% for 3 to 14 days, followed by steaming, washing, pressing, pulping, and filtering to obtain mulberry bark fibers. The mulberry bark fibers, mugwort powder, adhesive, and water are then mixed and stirred for 15 to 20 minutes before papermaking.

[0004] Meanwhile, existing commercially available mulberry bark paper products generally suffer from high dust content due to insufficient fiber purification and limitations in papermaking processes, which directly affects the paper's appearance quality and writing performance. Summary of the Invention

[0005] To overcome the deficiencies of the prior art described above, the present invention provides a method for preparing traditional Lanting cocoon paper.

[0006] The present invention also provides a traditional Lanting cocoon paper.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A traditional method for preparing Lanting cocoon paper includes the following steps: Step (1) Raw material pretreatment and selection: Take mulberry branches, peel off the mulberry bark, dry it, soak it to extract the innermost fiber, wash it, and obtain mulberry bark raw material; Step (2) Two-stage chemical cooking: First stage of cooking: The mulberry bark raw material is placed into a cooking pot, and a mixed cooking liquid is added at a ratio of 1 kg: 20~25 L; 0.9%~1.1% magnesium sulfate is added to the cooking system, the temperature is raised to 90℃~100℃ and kept at that temperature for 1.9~2.1 hours, then the temperature is lowered to 80℃~95℃ and kept at that temperature for 6~8 hours to complete the first stage of cooking; the mixed cooking liquid contains 5~6 g / L sodium carbonate and 4%~5% hydrogen peroxide. Second stage cooking: The waste liquid from the first stage cooking is discharged. The mulberry bark after the first stage cooking is refilled with a low-concentration cooking liquid containing 0.9%~1.1% magnesium sulfate at a ratio of 1:20~25. The temperature is raised to 90℃~95℃ and maintained at 90℃~95℃ for 6~8 hours to complete the second stage cooking. The low-concentration cooking liquid contains 3~4 g / L sodium carbonate and 2~3% hydrogen peroxide. Step (3) Washing and fiber decomposition: After steaming, rinse the steamed mulberry bark with water; then drain, dehydrate, remove impurities, and pound. Step (4) Pulping and mixing: After washing the mulberry bark fibers with clean water, add a dispersant and then pulp; before papermaking, add a composite dispersant to the pulp and mix evenly; Step (5) Papermaking and drying: The papermaking process is carried out by a single person using a hanging curtain. The pulp is scooped four times in a row on the same paper curtain. After the papermaking is completed, the pulp is pressed and dehydrated. After drying, the traditional Lanting cocoon paper is obtained.

[0008] Preferably, the mulberry branch is a one-year-old mulberry branch with a diameter of 2-3 cm.

[0009] Preferably, the soaking process to obtain the innermost fiber includes scraping off the outer black shell and the second yellow shell to obtain the innermost fiber.

[0010] Preferably, the rinsing process includes rinsing in hot water at 70°C and then rinsing in cold water.

[0011] Preferably, the physical hammering time is 7 to 9 minutes.

[0012] Preferably, the dispersant includes PEO, and the amount added is 0.028~0.032% by oven-dry pulp weight.

[0013] Preferably, the pulping conditions are 400~600 r / min for 20~30 min.

[0014] Preferably, the pulp concentration is 9% to 11%.

[0015] Preferably, the amount of the composite dispersant added is 0.03% to 0.05% of the oven-dry slurry mass.

[0016] More preferably, the amount of the composite dispersant added is 0.05% of the oven-dry slurry mass.

[0017] Preferably, the composite dispersant comprises PEO, okra gum, and guar gum.

[0018] Preferably, the mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): (1~2): (1~3).

[0019] More preferably, the mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): 1: (1~2).

[0020] More preferably, the mass ratio of PEO, okra gum, and guar gum in the composite dispersant is 1:1:2.

[0021] In this invention, the mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): 1: (1~2), and the preferred mass ratio is 1:1:2, which results in a product with better overall performance.

[0022] Preferably, the composite dispersant is prepared by mixing PEO, okra gum and guar gum evenly to obtain the composite dispersant.

[0023] Preferably, the quantitative amount of the four consecutive scoops of slurry is 24~26 g / m³. 2 More preferably, the quantitative amount is 26 g / m 2 .

[0024] A traditional Lanting cocoon paper is prepared by the preparation method described in this invention.

[0025] In this invention, a complete method for preparing Lanting cocoon paper has been creatively completed. This method forms a systematic solution from the pretreatment of raw materials, two-stage cooking, application of composite dispersant and "four-curtain water" papermaking technology.

[0026] In this invention, the traditional Lanting cocoon paper (mulberry bark paper) prepared using the technical solution of this invention exhibits excellent performance in terms of fiber purity, paper uniformity, and mechanical strength. It not only restores the appearance of traditional famous paper, but also provides a feasible process path for the modern production of high-quality handmade paper.

[0027] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention improves the purity of fiber raw materials and reduces impurities in paper by scraping off the outer black shell and the second yellow shell of mulberry bark, resulting in superior paper gloss and texture. The preparation process employs a two-stage cooking process using sodium carbonate and hydrogen peroxide, efficiently and gently separating and purifying the fibers, resulting in high pulp strength and paper with excellent anti-aging properties, a whiteness of ≥60%, and a whiteness decrease of ≤0.5% with aging resistance. Simultaneously, the composite dispersant (PEO, okra, guar gum) combines the advantages of synthetic and natural plant gums, effectively improving fiber dispersion and simultaneously enhancing paper uniformity and strength. Furthermore, the innovative "four-curtain water" papermaking method increases the residence time of the pulp on the curtains and the amount of water filtered, promoting tighter fiber interweaving, thus producing paper with a denser structure and superior physical properties, a tear strength ≥1560 mN, and a dust content ≤50 particles / m². 2 . Attached Figure Description

[0028] Figure 1 The image shows the actual product of the prepared traditional Lanting cocoon paper. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0030] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0031] Sodium carbonate, S818014 anhydrous sodium carbonate, ≥99.5%, Maclean's.

[0032] 27.5% hydrogen peroxide, hydrogen peroxide mass fraction 27.5 wt%, Hangzhou Mingxin Hydrogen Peroxide Co., Ltd.

[0033] Magnesium sulfate, M813991 Anhydrous magnesium sulfate, 99.99% metals basis.

[0034] Dispersant: Polyethylene oxide (PEO), P697836, average molecular weight 12000, Maclean.

[0035] Okra gum, food grade, 99%, Wuhan Wanrong Technology Development Co., Ltd.

[0036] Guar gum (guar bean gum), CAS No. 9000-30-0, 5000-5500 cps, 200 mesh, Shanghai Yuanye Biotechnology Co., Ltd.

[0037] The present invention will now be described in detail: A traditional method for preparing Lanting cocoon paper includes the following steps: Step (1) Raw material pretreatment and selection: Take mulberry branches, peel off the mulberry bark, dry it, soak it to extract the innermost fiber, wash it, and obtain mulberry bark raw material; In a preferred embodiment, the mulberry branch is a one-year-old mulberry branch with a diameter of 2-3 cm; In a preferred embodiment, the soaking process to obtain the innermost fiber involves scraping off the outer black shell and the second yellow shell to obtain the innermost fiber.

[0038] Step (2) Two-stage chemical cooking: First stage of cooking: The mulberry bark raw material is placed into a cooking pot, and a mixed cooking liquid is added at a ratio of 1 kg: 20~25 L; 0.9%~1.1% magnesium sulfate is added to the cooking system, the temperature is raised to 90℃~100℃ and kept at that temperature for 1.9~2.1 hours, then the temperature is lowered to 80℃~95℃ and kept at that temperature for 6~8 hours to complete the first stage of cooking; the mixed cooking liquid contains 5~6 g / L sodium carbonate and 4%~5% hydrogen peroxide. Second stage cooking: The waste liquid from the first stage cooking is discharged. The mulberry bark after the first stage cooking is refilled with a low-concentration cooking liquid containing 0.9%~1.1% magnesium sulfate at a ratio of 1:20~25. The temperature is raised to 90℃~95℃ and maintained at 90℃~95℃ for 6~8 hours to complete the second stage cooking. The low-concentration cooking liquid contains 3~4 g / L sodium carbonate and 2~3% hydrogen peroxide. In a preferred embodiment, the amount of hydrogen peroxide used is a percentage of the mass relative to the weight of the oven-dried mulberry bark.

[0039] In a preferred embodiment, the amount of magnesium sulfate used is a percentage of the mass relative to the weight of the oven-dried mulberry bark.

[0040] In a preferred embodiment, the heating rate is 1.5~2.5℃ / min.

[0041] Step (3) Washing and fiber decomposition: After steaming, rinse the steamed mulberry bark with water; then drain, dehydrate, remove impurities, and pound. In a preferred embodiment, the rinsing process includes rinsing in hot water at 70°C and then rinsing in cold water. In a preferred embodiment, the physical hammering time is 7-9 minutes; Step (4) Pulping and mixing: After washing the pounded mulberry bark fibers with clean water, add a dispersant; The pulp was then beaten using a curved blade Wali beater; before papermaking, a composite dispersant was added to the pulp and mixed thoroughly. In a preferred embodiment, the dispersant includes PEO, and the amount added is 0.028~0.032% by oven-dry pulp weight.

[0042] In a preferred embodiment, the pulping conditions are 400~600 r / min for 20~30 min.

[0043] In a preferred embodiment, the pulp consistency is 9%~11%. In a preferred embodiment, the amount of the composite dispersant added is 0.03% to 0.05% of the oven-dry slurry mass.

[0044] In a preferred embodiment, the composite dispersant comprises PEO, okra gum, and guar gum.

[0045] In a preferred embodiment, the mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): (1~2): (1~3).

[0046] In a preferred embodiment, the composite dispersant is prepared by mixing PEO, okra gum and guar gum evenly to obtain the composite dispersant.

[0047] Step (5) Papermaking and drying: The papermaking process is carried out by a single person using a hanging curtain. The pulp is scooped four times in a row on the same paper curtain. After the papermaking is completed, the pulp is pressed and dehydrated. After drying, the traditional Lanting cocoon paper is obtained.

[0048] In this invention, the traditional Lanting cocoon paper (mulberry bark paper) prepared using the technical solution of this invention exhibits excellent performance in terms of fiber purity, paper uniformity, and mechanical strength. It not only restores the appearance of traditional famous paper, but also provides a feasible process path for the modern production of high-quality handmade paper.

[0049] The present invention will now be described in detail with reference to embodiments and comparative examples: The liquid ratio in the examples and comparative examples is: the ratio of the mass (kg) of the oven-dried raw material to the mass-volume (L) of the mixed cooking liquor (kg / L); the amount of sodium carbonate used is the concentration of sodium carbonate in the mixed cooking liquor; the amounts of hydrogen peroxide and magnesium sulfate used are percentages relative to the mass of the oven-dried raw material.

[0050] Example 1 A traditional method for preparing Lanting cocoon paper includes the following steps: Step (1) Raw material pretreatment and selection: Take one-year-old mulberry branches with a diameter of 2-3 cm, peel off the mulberry bark and dry it in the sun; then soak the dried mulberry bark until it is soft, then scrape off the outer black shell and the second yellow shell to obtain the innermost fiber, clean it, and obtain the mulberry bark raw material.

[0051] Step (2) Two-stage chemical cooking: First stage of cooking: The mulberry bark raw material is put into a cooking pot, and a mixed cooking liquid containing 6 g / L sodium carbonate and 5% hydrogen peroxide (based on the weight of the oven-dried mulberry bark) is added. The liquid ratio is controlled at 1 kg:25 L (the ratio of the weight of the oven-dried mulberry bark to the volume of the mixed cooking liquid, kg / kg). When the temperature is increased to 80℃ at a heating rate of 2℃ / min, 1% magnesium sulfate (based on the weight of the oven-dried mulberry bark) is added to the cooking system. The temperature is continued to be increased to 100℃ at a heating rate of 2℃ / min and held for 2 hours. Then the temperature is reduced to 95℃ and held for 6 hours to complete the first stage of cooking. Second stage of cooking: The waste liquid from the first stage of cooking is discharged. The mulberry bark after the first stage of cooking is then refilled with a low-concentration cooking liquid containing 4 g / L sodium carbonate, 3% hydrogen peroxide (based on the weight of the oven-dried mulberry bark), and 1% magnesium sulfate (based on the weight of the oven-dried mulberry bark). The liquid-to-liquid ratio is 1:25 (the ratio of the weight of the oven-dried mulberry bark to the volume of the cooking liquid, kg / L). The temperature is increased to 90℃ at a rate of 2℃ / min and held at 90℃ for 7 hours to complete the second stage of cooking.

[0052] Step (3) Washing and fiber decomposition: After steaming, the steamed mulberry bark is first rinsed in 70℃ hot water, and then rinsed clean in cold water; after draining, it is dehydrated by centrifugal dehydrator; visible yellow and black impurities are manually removed; the mulberry bark after impurity removal is sent to a beating machine for physical hammering for 8 minutes to achieve initial dissociation of fiber bundles.

[0053] Step (4) Pulping and mixing: Wash the pounded mulberry bark fibers with clean water at 25°C until no visible debris is visible, and add dispersant polyethylene oxide (PEO) at 0.03% of the oven-dry pulp weight; The pulp was then beaten in two stages using a curved-blade Wali beater: the first stage at 400 r / min for 30 min, and the second stage at 600 r / min for 20 min. The pulp consistency was controlled at 10% and the freeness at 37°SR throughout the process. Before papermaking, a composite dispersant was added to the pulp and mixed evenly. The composite dispersant was prepared by mixing PEO, okra gum, and guar gum in a mass ratio of 1:1:2, and the amount added was 0.05% of the oven-dry pulp mass.

[0054] The composite dispersant is prepared by mixing PEO, okra gum and guar gum evenly to obtain the composite dispersant.

[0055] Step (5) Papermaking and Drying: Single-person hanging curtain handmade papermaking is adopted, and the "four-curtain water scooping" technique is used to increase the paper density, that is, the pulp is scooped four times in a row on the same paper curtain to make the basis weight of the wet paper sheet 26 g / m³. 2After papermaking, a 50-ton hydraulic jack is used to forcefully press and dehydrate the wet paper stacks. Finally, after sun-drying, the traditional Lanting cocoon paper is obtained. (See...) Figure 1 .

[0056] Example 2 A traditional method for preparing Lanting cocoon paper includes the following steps: Step (1) Raw material pretreatment and selection: Take one-year-old mulberry branches with a diameter of 2-3 cm, peel off the mulberry bark and dry it in the sun; then soak the dried mulberry bark until it is soft, then scrape off the outer black shell and the second yellow shell to obtain the innermost fiber, clean it, and obtain the mulberry bark raw material.

[0057] Step (2) Two-stage chemical cooking: First stage of cooking: The mulberry bark raw material is put into a cooking pot, and a mixed cooking liquid containing 5 g / L sodium carbonate and 4% hydrogen peroxide (based on the weight of the oven-dried mulberry bark) is added. The liquid ratio is controlled at 1 kg:20 L (the ratio of the weight of the oven-dried mulberry bark to the volume of the mixed cooking liquid, kg / L). When the temperature is increased to 80℃ at a heating rate of 2℃ / min, 1% magnesium sulfate (based on the weight of the oven-dried mulberry bark) is added to the cooking system. The temperature is continued to be increased to 90℃ at a heating rate of 2℃ / min and held for 2 hours. Then the temperature is reduced to 80℃ and held for 8 hours to complete the first stage of cooking. Second stage of cooking: The waste liquid from the first stage of cooking is discharged. The mulberry bark after the first stage of cooking is then refilled with a low-concentration cooking liquid containing 3 g / L sodium carbonate, 2% hydrogen peroxide (based on the weight of the oven-dried mulberry bark), and 1% magnesium sulfate (based on the weight of the oven-dried mulberry bark). The liquid-to-liquid ratio is 1:20 (the ratio of the weight of the oven-dried mulberry bark to the volume of the cooking liquid, kg / L). The temperature is increased to 95℃ at a rate of 2℃ / min and held at 95℃ for 7 hours to complete the second stage of cooking.

[0058] Step (3) Washing and fiber decomposition: After steaming, the steamed mulberry bark is first rinsed in 70℃ hot water, and then rinsed clean in cold water; after draining, it is dehydrated by centrifugal dehydrator; visible yellow and black impurities are manually removed; the mulberry bark after impurity removal is sent to a beating machine for physical hammering for 8 minutes to achieve initial dissociation of fiber bundles.

[0059] Step (4) Pulping and mixing: Wash the pounded mulberry bark fibers with clean water at 25°C until no visible debris is visible, and add dispersant polyethylene oxide (PEO) at 0.03% of the oven-dry pulp weight; The pulp was then beaten in two stages using a curved-blade Wali beater: the first stage at 400 r / min for 30 min, and the second stage at 600 r / min for 20 min. The pulp consistency was controlled at 10% and the freeness at 37°SR throughout the process. Before papermaking, a composite dispersant was added to the pulp and mixed evenly. The composite dispersant was prepared by mixing PEO, okra gum, and guar gum in a mass ratio of 1:1:2, and the amount added was 0.03% of the oven-dry pulp mass.

[0060] The composite dispersant is prepared by mixing PEO, okra gum and guar gum evenly to obtain the composite dispersant.

[0061] Step (5) Papermaking and Drying: Single-person hanging curtain handmade papermaking is adopted, and the "four-curtain water scooping" technique is used to increase the paper density, that is, the pulp is scooped four times in a row on the same paper curtain to make the basis weight of the wet paper sheet 24 g / m³. 2 After the papermaking process is completed, a 50-ton hydraulic jack is used to forcefully press and dehydrate the wet paper stacks. Finally, after drying, the traditional Lanting cocoon paper is obtained.

[0062] Example 3 This embodiment is similar to Embodiment 1, except that in step (4), the ratio of the composite dispersant is adjusted to PEO, okra gum and guar gum in a mass ratio of 1:2:1, and the amount added is still 0.05% of the dry pulp mass.

[0063] Example 4 This embodiment is similar to Embodiment 1, except that in step (4), the ratio of the composite dispersant is adjusted to PEO, okra gum and guar gum in a mass ratio of 2:1:1, and the amount added is still 0.05% of the dry pulp mass.

[0064] Example 5 This embodiment is similar to Embodiment 1, except that in step (4), the ratio of the composite dispersant is adjusted to PEO, okra gum and guar gum in a mass ratio of 2:1:3, and the amount added is still 0.05% of the dry pulp mass.

[0065] Example 6 This embodiment is similar to Embodiment 1, except that in step (4), the ratio of the composite dispersant is adjusted to PEO, okra gum and guar gum in a mass ratio of 1:1:1, and the amount added is still 0.05% of the dry pulp mass.

[0066] Comparative Example 1 Comparative Example 1 presents data on mulberry bark paper sold in a certain city.

[0067] Comparative Example 2 This comparative example is similar to Example 1, except that no composite dispersant is added in step (4).

[0068] Comparative Example 3 This comparative example is similar to Example 1, except that okra gum is not added to the composite dispersant in step (4).

[0069] Comparative Example 4 This comparative example is similar to Example 1, except that step (5) uses the "three-screen scooping" technique, that is, scooping pulp three times consecutively on the same paper screen, with a quantitative amount of 26 g / m³. 2 .

[0070] Analysis and detection Whiteness was determined according to GB / T 7974-2013 Determination of Blue Light Diffuse Reflectance Factor D65 Brightness of Paper, Paperboard and Pulp (Diffuse / Vertical Method, Outdoor Daylight Conditions); Aging Resistance Whiteness was determined according to GB / T 464-2008 Accelerated Dry Heat Aging of Paper and Paperboard; Tear Resistance was determined according to GB / T 455-2002 Tear Resistance of Paper and Paperboard; Dust Content was determined according to GB / T 1541-2013 Dust Content of Paper and Paperboard. The test results are shown in the table below: Table 1. Results of Data from Examples and Comparative Cases

[0071] Results analysis: The results of Examples 1-6 show that the traditional Lanting cocoon paper prepared using the technical solution of this invention maintains high whiteness (≥60%) and a decrease in whiteness due to aging (≤0.5%), which is significantly better than commercially available mulberry bark paper (Comparative Example 1: whiteness 50.9%, whiteness decreased by 2.62% due to aging). Meanwhile, the tear strength of the traditional Lanting cocoon paper prepared using the technical solution of this invention is ≥1560 mN, and the dust content is ≤50 particles / m. 2 .

[0072] Comparative Example 2 (without composite dispersant): the whiteness of the fiber decreased by 1.1% due to aging, the tear strength decreased to 1210 mN, and the dust content increased to 85 particles / m². This indicates that the dispersant helps to disperse the fiber, improve mechanical properties, and reduce dust content.

[0073] Comparative Example 3, without added okra gum, had a tear strength of 1339 mN and a dust density of 72 particles / m. 2 The overall performance decreased compared to the previous example, indicating that okra gum enhances fiber bonding and improves impurity removal.

[0074] Comparative Example 4, using the "three-curtain water scooping" technique, showed a 0.7% decrease in whiteness due to aging, a tear strength of 1487 mN, and a dust content of 68 particles / m². 2 This illustrates the crucial role of the "scooping four curtains of water" papermaking technique in improving the density and durability of paper.

[0075] 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 traditional Lanting cocoon paper, characterized in that, Includes the following steps: Step (1) Raw material pretreatment and selection: Take mulberry branches, peel off the mulberry bark, dry it, soak it to extract the innermost fiber, wash it, and obtain mulberry bark raw material; Step (2) Two-stage chemical cooking: First stage of cooking: The mulberry bark raw material is placed into a cooking pot, and a mixed cooking liquid is added at a ratio of 1 kg : 20~25 L; 0.9%~1.1% magnesium sulfate is added to the cooking system, the temperature is raised to 90℃~100℃ and kept at that temperature for 1.9~2.1 hours, then the temperature is lowered to 80℃~95℃ and kept at that temperature for 6~8 hours to complete the first stage of cooking; the mixed cooking liquid contains 5~6 g / L sodium carbonate and 4%~5% hydrogen peroxide. Second stage cooking: The waste liquid from the first stage cooking is discharged. The mulberry bark after the first stage cooking is refilled with a low-concentration cooking liquid containing 0.9%~1.1% magnesium sulfate at a ratio of 1 kg : 20~25 L. The temperature is raised to 90℃~95℃ and maintained at 90℃~95℃ for 6~8 hours to complete the second stage cooking. The low-concentration cooking liquid contains 3~4 g / L sodium carbonate and 2~3% hydrogen peroxide. Step (3) Washing and fiber decomposition: After steaming, rinse the steamed mulberry bark with water; then drain, dehydrate, remove impurities, and pound. Step (4) Pulping and mixing: After washing the mulberry bark fibers with clean water, add a dispersant and then pulp; before papermaking, add a composite dispersant to the pulp and mix evenly; Step (5) Papermaking and drying: The papermaking process is carried out by a single person using a hanging curtain. The pulp is scooped four times in a row on the same paper curtain. After the papermaking is completed, the pulp is pressed and dehydrated. After drying, the traditional Lanting cocoon paper is obtained.

2. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The soaking process involves removing the innermost layer of fiber, including scraping off the outer black shell and the second yellow shell, to obtain the innermost layer of fiber.

3. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The dispersant includes polyethylene oxide (PEO), and the amount added is 0.028~0.032% by oven-dry slurry weight.

4. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The amount of the composite dispersant added is 0.03% to 0.05% of the oven-dry slurry mass.

5. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The composite dispersant comprises PEO, okra gum, and guar gum.

6. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): (1~2): (1~3).

7. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The mass ratio of PEO, okra gum and guar gum in the composite dispersant is (1~2): 1: (1~2).

8. The method for preparing traditional Lanting cocoon paper according to claim 1, characterized in that, The quantitative amount of the four consecutive scoops is 24~26 g / m³. 2 .

9. A traditional Lanting cocoon paper, characterized in that, It is prepared by the preparation method described in claims 1 to 8.

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