Coating-free high-speed calligraphy and painting printing paper added with ancient straw and preparation method of coating-free high-speed calligraphy and painting printing paper

Abstract

The invention discloses coating-free high-speed calligraphy and painting printing paper added with ancient straw and a preparation method of the coating-free high-speed calligraphy and painting printing paper, and belongs to the technical field of papermaking, the calligraphy and painting printing paper is composed of a pulp component and an auxiliary material component, and the pulp component comprises 50-70 parts of bamboo pulp, 20-35 parts of white leaf wood pulp, 10-20 parts of Chinese alpine rush pulp, 5-15 parts of wingceltis leather and 0.05-0.2 part of special fiber; the auxiliary material components comprise cationic lake glue, a brightening agent, a thickening agent, a retention aid and a pigment, and the bamboo pulp is subjected to straw burning treatment by an ancient method. According to the invention, a quaternary composite slurry system is adopted to realize fiber length gradient distribution, and an ancient straw burning treatment process and a multifunctional additive synergistic system are combined, so that the uncoated paper for painting and calligraphy printing, which is low in tightness, high in bulk, long in fracture and good in water absorption, is prepared, and the uncoated paper is suitable for high-speed printing at 80-150m / min, does not fall powder and hair, is not broken, and is bright in ink color and good in retentivity.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and in particular to an uncoated high-speed calligraphy and painting printing paper with added traditional straw, and its preparation method. Background Technology

[0002] Painting and calligraphy paper is an important carrier of traditional Chinese culture and art, and one of the Four Treasures of the Study. Its quality directly affects the expressive effect and long-term preservation of paintings and calligraphy works. High-quality painting and calligraphy paper should have good ink absorption, color absorption, and absorbency, and should also have certain quality indicators such as whiteness, strength, stiffness, bulk, and water absorption.

[0003] With the rapid development of printing technology, the modern calligraphy and painting market has placed new demands on the paper used for calligraphy and painting. On the one hand, although traditional handmade calligraphy and painting paper is of excellent quality, its low production efficiency and high cost make it difficult to meet the needs of large-scale cultural dissemination. On the other hand, although ordinary printing paper can achieve high-speed production, its ink absorption and ink-wetting properties are poor, and it often uses a coating process, which can lead to problems such as coating peeling and poor adhesion of calligraphy and painting. Therefore, developing an uncoated calligraphy and painting printing paper that can adapt to high-speed printing production while maintaining the excellent properties of traditional calligraphy and painting paper is of great practical significance.

[0004] Currently, the main raw materials for calligraphy and painting paper fall into two categories: bark (such as bark of the Qingtan tree, mulberry bark, and paper mulberry bark) and grass (such as rice straw and dragon's beard grass). Traditional Xuan paper uses Qingtan bark and mulberry grass as its main raw materials, and is made through a complex pulping and papermaking process, earning it the reputation of possessing a thousand-year-old ink-like beauty. Sichuan Jiajiang calligraphy and painting paper uses tender bamboo as its main material and employs a bamboo-based handmade papermaking technique, which has a long history and is a national intangible cultural heritage. However, the production cycle of traditional calligraphy and painting paper is long, the process is complex, and the output is limited, making it difficult to meet the needs of modern large-scale production.

[0005] Chinese patent CN104963233A discloses a type of calligraphy and painting paper with added bleached bamboo pulp and fiber grafting agent, and its preparation method. The formula consists of 20-90% bleached bamboo pulp and 10-80% bleached bamboo pulp meal, with auxiliary materials including 0.5-1.5% talc, 0.05-1.0% fiber grafting agent, and 0.1-1.0% oleander gum. While this technology solves the raw material source problem to some extent, improves the absorption performance of the calligraphy and painting paper, and reduces yellowing, it still has the following shortcomings: the raw material composition is relatively simple, using only bamboo pulp and bamboo pulp meal fibers, resulting in a narrow fiber length distribution and insufficient uniformity of transverse and longitudinal strength; it does not consider adaptability to high-speed printing, easily leading to problems such as powdering, lint shedding, and paper breakage on high-speed printing presses; and the traditional auxiliary agent system is poorly matched with high-speed printing processes, affecting printing efficiency and print quality.

[0006] In addition, existing calligraphy and painting papers generally suffer from the following technical problems: high cost of secondary soaking for improvement process and short retention time; easy to lose paper liquid and low paperboard efficiency during high-speed printing; uneven tensile strength in the transverse and longitudinal directions of the paper, making it easy to break; paper that is too rigid or too soft, lacking the ideal feel of being both hard and soft; poor ink retention, and easy to fade after long-term storage; poor whiteness stability, with large differences in whiteness between different batches of products.

[0007] To address the aforementioned technical issues, it is necessary to develop a new type of paper for calligraphy and painting printing that can inherit the excellent characteristics of traditional calligraphy and painting paper while also meeting the requirements of modern high-speed printing production, thus achieving an organic integration of traditional craftsmanship and modern technology. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an uncoated high-speed calligraphy and painting printing paper with added traditional straw processing techniques and its preparation method. This invention employs a quaternary composite pulp system, scientifically proportioning bamboo pulp, white leaf wood pulp, dragon's beard grass pulp, and sandalwood bark pulp in specific ratios. Combined with the traditional straw processing technique and a multifunctional additive synergistic system, this results in an uncoated calligraphy and painting printing paper suitable for high-speed printing production.

[0009] The first objective of this invention is to provide an uncoated high-speed calligraphy and painting printing paper with added traditional straw processing techniques. The paper comprises a pulp component and auxiliary components. The pulp component, by weight, includes: 50-70 parts bamboo pulp, 20-35 parts white leaf wood pulp, 10-20 parts dragon's beard grass pulp, 5-15 parts sandalwood bark pulp, and 0.05-0.2 parts special fibers. The auxiliary components, by total weight of the pulp component, include: 1-3% cationic starch, 0.05-0.2% brightening agent, 0.05-0.2% thickener, 0.3-0.8% retention aid, and 0.1-0.5% colorant. The bamboo pulp is treated with traditional straw processing techniques.

[0010] Furthermore, the pulp components, by weight, include: 55-65 parts bamboo pulp, 25-32 parts white leaf wood pulp, 12-18 parts dragon's beard grass pulp, 8-12 parts sandalwood bark pulp, and 0.08-0.15 parts special fibers. This preferred ratio achieves a gradient distribution of fiber length, resulting in paper with excellent overall performance.

[0011] Furthermore, based on the total weight of the pulp components, the auxiliary components include: 1.5-2.5% cationic starch, 0.08-0.15% brightener, 0.08-0.15% thickener, 0.4-0.6% retention aid, and 0.2-0.4% pigment. The preferred auxiliary component ratio can achieve synergistic effects of the additives, improving the printability and calligraphy / painting properties of the paper.

[0012] Furthermore, the bamboo pulp is selected from one or more of the following: bamboo pulp, moso bamboo pulp, and green bamboo pulp; the beating degree of the bamboo pulp is 35-50°SR, and the average fiber length is 1.5-2.8 mm. Bamboo pulp fibers have a moderate length and a high cellulose content, making them an ideal main fiber for calligraphy and painting paper.

[0013] Furthermore, the white wood pulp is selected from hardwood pulp or a mixture of softwood and hardwood pulp, with a freeness of 30-45°SR and an average fiber length of 0.8-1.2 mm. Wood pulp fibers have good uniformity properties, which can improve the surface smoothness and printability of paper.

[0014] Furthermore, the beard grass pulp has a freeness of 40-55°SR and an average fiber length of 0.6-1.0 mm. The beard grass pulp undergoes natural bleaching treatment through sun exposure and rain, with a treatment cycle of 3-6 months. Beard grass pulp is a short-fiber pulp; after natural bleaching, its lignin content decreases and its whiteness increases, effectively regulating the ink absorption and ink absorption properties of paper.

[0015] Furthermore, the bark material is selected from the bark of *Pterocarya stenoptera* or *Pterocarya stenoptera*, with a beating degree of 25-40°SR and an average fiber length of 2.5-5.0 mm. Bark fiber is a core raw material for traditional Xuan paper, possessing ultra-long fiber characteristics that can significantly improve the tensile strength and tear strength of the paper.

[0016] Furthermore, the special fiber is selected from one or more combinations of lotus fiber, mulberry bark fiber, silk fiber, and bamboo fiber, and the average length of the special fiber is 3-8 mm. The addition of a small amount of special fiber can enhance the interlacing strength of the fiber network and improve the toughness and folding endurance of the paper.

[0017] Furthermore, the cationic starch is a complex of cationic starch and plant gum, wherein the weight ratio of cationic starch to plant gum is 3-5:1; the plant gum is selected from one or more of astragalus gum, gum arabic, and guar gum. Cationic starch can enhance the bonding force between fibers, improve the dry and wet strength and surface strength of paper, and simultaneously improve the adhesion and retention of ink.

[0018] The second objective of this invention is to provide a method for preparing the above-mentioned uncoated high-speed calligraphy and painting printing paper, comprising the following steps: Step 1: Traditional Singing Treatment: Soak the bamboo pulp in clean water for 15-30 days, turning it every 3-5 days to ensure even water absorption and expansion. After soaking, drain and bleach under natural sunlight and rain for 60-120 days, turning it regularly to ensure even bleaching. This process yields bamboo pulp treated with the traditional singing method. This method fully utilizes sunlight, rainwater, and ozone in the air for bleaching, while simultaneously removing impurities such as lignin, hemicellulose, and other cells from the bamboo pulp, resulting in improved fiber purity, stable whiteness, and reduced yellowing.

[0019] Step 2, Pulp Debonding: The bamboo pulp, white leaf wood pulp, dragon beard grass pulp, and sandalwood bark pulp, after being processed using the traditional method of burning straw, are separately debonded for 15-30 minutes at a speed of 800-1200 rpm to obtain individual pulps of each component. Debonding treatment can fully disperse and moderately fluff the fibers, increase the specific surface area and the number of surface hydroxyl groups, and promote the formation of hydrogen bonds between fibers.

[0020] Step 3: Pulp Mixing: Weigh out 50-70 parts bamboo pulp, 20-35 parts white leaf wood pulp, 10-20 parts dragon beard grass pulp, 5-15 parts sandalwood bark pulp, and 0.05-0.2 parts special fibers according to their weight proportions. Add these components sequentially to the pulp mixing tank, dilute with water to a pulp concentration of 2-4%, and stir for 20-40 minutes to obtain the mixed pulp. Controlling the pulp mixing sequence and time ensures that the various fibers are evenly dispersed, forming an ideal fiber length gradient distribution.

[0021] Step 4: Adding excipients: Add cationic starch, brightener, thinner, retention aid, and colorant to the mixed slurry in sequence. Stir for 5-15 minutes after adding each excipient. After all excipients have been added, continue stirring for 30-60 minutes to obtain the finished slurry. The order of excipient addition and stirring time have been optimized to ensure that various additives are fully dispersed and exert a synergistic effect.

[0022] Step 5, Paper Forming: The finished pulp is diluted to a concentration of 0.05-0.15% and fed to the paper machine for paper forming at a speed of 80-150 m / min. The wet paper web is dewatered under vacuum to a dryness of 35-50%, and then pressed in the press section to a dryness of 40-55%. Optimizing high-speed paper forming conditions ensures uniform paper web formation and smooth dewatering, meeting the requirements of high-speed printing production.

[0023] Step Six: Drying and Finishing: The pressed paper web is sequentially dried through multiple drying cylinders. The temperature of the first drying cylinder is 75-95℃, the temperature of the middle drying cylinder is 95-115℃, and the temperature of the last drying cylinder is 85-100℃, until the paper moisture content is 5-8%. After calendering, slitting, and winding, uncoated high-speed calligraphy and painting printing paper is obtained. The segmented drying process can control the uniformity of paper shrinkage, avoid warping and wrinkling, and improve the flatness and dimensional stability of the paper.

[0024] Compared with the prior art, the present invention has the following beneficial effects: I. Achieving Gradient Distribution of Fiber Length in a Quaternary Composite Slurry System This invention employs a scientifically proportioned blend of four raw materials with different fiber lengths: bamboo pulp, white leaf wood pulp, dragon's beard grass pulp, and sandalwood bark pulp. This creates a gradient distribution of fibers, from short fibers (dragon's beard grass pulp, 0.6-1.0 mm) to medium-short fibers (wood pulp, 0.8-1.2 mm), medium-long fibers (bamboo pulp, 1.5-2.8 mm), and finally to ultra-long fibers (sandalwood bark pulp, 2.5-5.0 mm). This gradient fiber length distribution offers the following advantages: short fibers fill the gaps between fibers, improving paper uniformity and smoothness; medium-long fibers form the paper's skeleton, providing basic strength; and ultra-long fibers form a reinforcing network, significantly improving tensile and tear strength. The quaternary composite pulp system ensures balanced longitudinal and transverse strength, reducing paper breakage and solving the problem of uneven paper strength in existing technologies. Experimental results show that the longitudinal breaking length of the calligraphy and painting printing paper prepared by this invention reaches 3.2-3.8 km, the transverse breaking length reaches 2.0-2.5 km, and the longitudinal-to-transverse strength ratio is 1.3-1.6, significantly superior to existing calligraphy and painting paper products.

[0025] II. Traditional straw burning treatment process improves fiber purity and whiteness stability. This invention applies the traditional intangible cultural heritage technique of burning straw to the pretreatment of bamboo pulp. Through prolonged soaking in clean water and natural bleaching by sun and rain, it fully utilizes ultraviolet rays from sunlight, dissolved oxygen in rainwater, and ozone in the air for gentle bleaching. This traditional straw-burning treatment effectively removes impurities such as lignin, hemicellulose, and other cells from the bamboo pulp, resulting in a more refined product. - The cellulose content is increased from 75-80% in ordinary bamboo pulp to 90-95%, and the ash content is reduced from 1.5-2.0% to 0.3-0.5%. The treated bamboo pulp fibers have high purity, stable whiteness, and are less prone to yellowing, with the yellowing value decreasing from 6-8% in ordinary bamboo pulp calligraphy and painting paper to 2-4%. At the same time, the traditional straw burning treatment increases the number of hydroxyl groups on the fiber surface, which is conducive to the formation of hydrogen bonds between fibers and the binding with additives, improving the internal bonding strength of the paper and ink adhesion.

[0026] III. Multifunctional additive synergistic system improves printing adaptability This invention employs a synergistic system composed of five additives: cationic starch, brightener, thinner, retention aid, and pigment. These additives work together to enhance each other's effectiveness. Cationic starch is a complex of cationic starch and plant gum. The positively charged cationic starch can electrostatically attract negatively charged fibers and fillers, improving the paper's wet and dry strength and surface strength. Plant gum possesses excellent film-forming and water-retention properties, improving ink adhesion and retention. Brighteners enhance the paper's optical whiteness and gloss, resulting in more vibrant prints. Thinners adjust pulp viscosity, improving its flowability and dispersibility. Retention aids increase the retention rate of fine fibers and fillers, reduce white water concentration, and improve papermaking efficiency. The synergistic effect of these five additives gives the paper excellent adaptability to high-speed printing, preventing dusting, lint, and paper breakage at papermaking speeds of 80-150 m / min, while increasing printing efficiency by 30-50%.

[0027] IV. Uncoated design avoids coating peeling issues This invention employs an uncoated design, optimizing the pulp ratio and additive system to give the paper excellent printability and calligraphy / painting properties, meeting the requirements of high-speed printing without the need for a coating. The uncoated design offers the following advantages: it avoids the problem of poor adhesion of calligraphy and paintings caused by coating peeling; it maintains the natural fibrous texture and ink absorption properties of the paper; it simplifies the production process and reduces production costs; and it improves the environmental performance of the paper, facilitating recycling. Experimental results show that the uncoated calligraphy and painting printing paper prepared by this invention has an absorbency (average in both directions) of 20-30 mm / 60 s, excellent ink absorption performance, and good ink color retention, fully meeting the requirements of calligraphy and painting printing.

[0028] 5. The paper has a firm yet soft feel and stable whiteness. This invention optimizes the fiber length gradient ratio and the synergistic system of additives to achieve a paper with an ideal balance of firmness and softness. The paper possesses moderate stiffness, providing sufficient rigidity to support high-speed printing while maintaining good softness for calligraphy and painting creation and mounting. Experimental results show that the density of the calligraphy and painting printing paper prepared by this invention is 0.30-0.40. The porosity is 2.5-3.3 mm. The paper is within the ideal range for hand feel. Furthermore, through traditional straw burning treatment and precise control of pigments, this invention ensures that the paper's whiteness remains stable within the 50-60% ISO range, with batch-to-batch whiteness differences controlled within ±2%, making it particularly suitable for student practice and calligraphy / painting enthusiasts. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0030] The sources and specifications of the raw materials used in this invention are as follows: Bamboo pulp: Selected from Ci bamboo pulp produced in Jiajiang, Sichuan, with a freeness of 38-45°SR, brightness of 65-75%ISO, and an average fiber length of 1.8-2.2mm. - The cellulose content reaches 92-95% after being processed using the traditional burning method.

[0031] White leaf wood pulp: bleached hardwood pulp (eucalyptus pulp) is selected, with a beating degree of 35-42°SR, a whiteness of 85-88%ISO, and an average fiber length of 0.9-1.1mm.

[0032] Dragon Beard Grass Pulp: Selected from dragon beard grass pulp produced in Hubei Province, which is naturally bleached by sun and rain for 4-5 months, with a freeness of 45-52°SR, a brightness of 70-78%ISO, and an average fiber length of 0.7-0.9mm.

[0033] Sandalwood bark: Selected from Qingtan (Pterocarpus santalinus) bark from Jingxian County, Anhui Province, with a pulping degree of 30-38°SR and an average fiber length of 3.0-4.5mm. - Cellulose content is over 95%.

[0034] Special fiber: A mixture of lotus fiber and mulberry bark fiber (weight ratio 1:1) with an average length of 4-6 mm.

[0035] Cationic starch: a complex of cationic starch (degree of substitution 0.03-0.05) and astragalus gum, with a weight ratio of 4:1 and a solid content of 25-30%.

[0036] Brightening agent: Fluorescent whitening agent VBL, effective content ≥98%.

[0037] Thickener: Sodium carboxymethyl cellulose (CMC), degree of substitution 0.6-0.8, viscosity 300-500 mPa·s.

[0038] Retention aid: cationic polyacrylamide (CPAM), molecular weight 8-12 million, degree of ionization 15-20%.

[0039] Pigment: Natural plant pigments (a mixture of gardenia yellow and madder red), used to adjust the paper tone to antique yellow or off-white.

[0040] Example 1 This embodiment provides an uncoated high-speed calligraphy and painting printing paper with added traditional burning grass and its preparation method. The specific steps are as follows: Step 1: Traditional Scorching Treatment: Take 100kg of dry bamboo pulp boards and soak them in a soaking pool containing 5000L of clean water for 20 days, turning them over every 4 days. After soaking, remove and drain them, then lay them flat in an open area for sun and rain bleaching treatment for 90 days, turning them over every 7 days. This yields bamboo pulp treated using the traditional scorching method. - The cellulose content increased from 78% to 93%, the ash content decreased from 1.8% to 0.4%, and the whiteness increased from 68% ISO to 75% ISO.

[0041] Step 2, Pulp Decomposition: The bamboo pulp, white leaf wood pulp, dragon beard grass pulp, and sandalwood bark pulp processed by the traditional burning method are placed in a decomposition machine for decomposition treatment. Water is added to dilute the pulp to a pulp concentration of 3.5%, the decomposition time is 20 minutes, and the decomposition speed is 1000 rpm to obtain the individual pulps of each component.

[0042] Step 3: Mixing the slurry: Weigh each component according to the following formula: Add the above raw materials to the mixing tank in sequence, dilute with water to a slurry concentration of 3% (i.e., a total slurry volume of about 3837L), turn on the agitator and mix for 30 minutes at a stirring speed of 60 rpm to obtain the mixed slurry.

[0043] Step 4: Add auxiliary materials: Based on a total dry weight of 115.1 kg for the slurry components, add the auxiliary materials according to the following formula: Cationic starch, brightener, thinner, retention aid and colorant are added to the mixed slurry in sequence. Stir for 10 minutes after each addition. After all the additives are added, continue stirring for 45 minutes to obtain the finished slurry.

[0044] Step 5, Paper Forming: Dilute the finished pulp to a concentration of 0.08%, and convey it to the wire paper machine for paper forming. The paper forming speed is 100m / min. The wet paper web is dewatered under vacuum to a dryness of 42%, and then enters the three-roll press section to press to a dryness of 48%.

[0045] Step Six: Drying and Finishing: The pressed paper web is sequentially dried through 18 drying cylinders. The temperature of the first 6 drying cylinders is 85℃, the temperature of the middle 6 drying cylinders is 105℃, and the temperature of the last 6 drying cylinders is 92℃. The paper is dried until the moisture content is 6.5%. After soft calendering (linear pressure 30kN / m), it is slit into single sheets with a specification of 787mm×1092mm to obtain uncoated high-speed calligraphy and painting printing paper.

[0046] The performance indicators of the calligraphy and painting printing paper prepared in Example 1 are shown in Table 1.

[0047] Example 2 This embodiment provides an uncoated high-speed calligraphy and painting printing paper with added traditional burning straw and its preparation method. The difference between this embodiment and Embodiment 1 lies in the different pulp and auxiliary material formulations, as detailed below: Pulp formula: 55 parts bamboo pulp, 32 parts white leaf wood pulp, 18 parts dragon beard grass pulp, 12 parts sandalwood bark pulp, and 0.15 parts special fiber.

[0048] Auxiliary material formulation (based on total dry weight of slurry): cationic starch 2.5%, brightener 0.12%, thinner 0.15%, retention aid 0.6%, colorant 0.35%.

[0049] The other steps are the same as in Example 1, and uncoated high-speed calligraphy and painting printing paper is obtained.

[0050] Example 3 This embodiment provides an uncoated high-speed calligraphy and painting printing paper with added traditional burning straw and its preparation method. The difference between this embodiment and Embodiment 1 lies in the different pulp and auxiliary material formulations, as detailed below: Pulp formula: 65 parts bamboo pulp, 25 parts white leaf wood pulp, 12 parts dragon beard grass pulp, 8 parts sandalwood bark pulp, and 0.08 parts special fiber.

[0051] Auxiliary material formulation (based on total dry weight of slurry): cationic starch 1.5%, brightener 0.08%, thinner 0.08%, retention aid 0.4%, colorant 0.2%.

[0052] The other steps are the same as in Example 1, and uncoated high-speed calligraphy and painting printing paper is obtained.

[0053] Example 4 This embodiment provides an uncoated high-speed calligraphy and painting printing paper with added traditional straw processing and its preparation method. The difference between this embodiment and Embodiment 1 lies in the different processing time of the traditional straw processing, as detailed below: Traditional straw processing: Soak in clean water for 25 days (turning it over every 5 days); then bleach by sun and rain for 120 days (turning it over every 10 days).

[0054] The pulp formula and auxiliary material formula are the same as in Example 1, and the other steps are the same as in Example 1, to obtain uncoated high-speed calligraphy and painting printing paper.

[0055] Example 5 This embodiment provides an uncoated high-speed calligraphy and painting printing paper with added traditional straw and its preparation method. The difference between this embodiment and Embodiment 1 lies in the papermaking speed and drying temperature, as detailed below: Paper forming: Paper machine speed 120m / min, wet paper web vacuum dewatering to 45% dryness, pressing to 50% dryness.

[0056] Drying and finishing: The temperature of the first 6 drying cylinders is 90℃, the temperature of the middle 6 drying cylinders is 110℃, and the temperature of the last 6 drying cylinders is 95℃.

[0057] The pulp formula and auxiliary material formula are the same as in Example 1, and the other steps are the same as in Example 1, to obtain uncoated high-speed calligraphy and painting printing paper.

[0058] Comparative Example 1 This comparative example uses the formula and method of Chinese Patent CN104963233A to prepare calligraphy and painting paper, as detailed below: Pulp formulation: 40% bleached bamboo pulp, 60% bleached bamboo pulp meal.

[0059] Auxiliary material formula (by weight of slurry): 1% talc, 0.4% fiber grafting agent, and 0.5% oleander gum.

[0060] Preparation method: Add bleached bamboo pulp and bleached bamboo pulp residue to the pulp mixing tank and mix evenly for 1 hour; add talc powder, fiber grafting agent and oleander gum, and stir for 0.5 hours; dilute the pulp to a concentration of 0.1% and send it to a single-wire single-cylinder cylinder paper machine for papermaking to obtain calligraphy and painting paper.

[0061] Comparative Example 2 This comparative example uses ordinary bamboo pulp (without the traditional straw burning treatment) combined with other raw materials and processes from Example 1 to prepare calligraphy and painting paper, as detailed below: Pulp formulation: 60 parts ordinary bamboo pulp, 30 parts white leaf wood pulp, 15 parts dragon beard grass pulp, 10 parts sandalwood bark pulp, and 0.1 parts special fiber. The ordinary bamboo pulp is not treated with the traditional straw burning process and is directly made from commercially bleached bamboo pulp.

[0062] The auxiliary material formula and preparation method are the same as in Example 1, and the calligraphy and painting paper is obtained.

[0063] Comparative Example 3 This comparative example uses a single bamboo pulp (without other fiber blends) combined with the additive system and process of Example 1 to prepare calligraphy and painting paper, as detailed below: Pulp formula: 100 parts of bamboo pulp processed using traditional straw burning techniques.

[0064] The auxiliary material formula and preparation method are the same as in Example 1, and the calligraphy and painting paper is obtained.

[0065] The performance of the calligraphy and painting paper samples of each embodiment and comparative example was tested according to the following national and industry standards: Basis weight: GB / T 451.2-2002 "Determination of basis weight of paper and paperboard"; Density and bulk: GB / T 451.3-2002 "Determination of thickness of paper and paperboard"; Whiteness: GB / T 7974-2013 "Determination of brightness (whiteness) of paper, paperboard and pulp - Diffuse / vertical method"; Yellowing value: GB / T 7974-2013 tests the change in whiteness before and after aging, with aging conditions being dry heat aging at 105℃ for 72 hours; Breaking length: GB / T 12914-2018 "Determination of tensile strength of paper and paperboard"; Tear strength: GB / T 455-2002 "Determination of tear strength of paper and paperboard"; Wet tensile strength: GB / T 465.2-2008 "Determination of tensile strength of paper and paperboard after immersion in water"; Water absorption: GB / T 461.1-2002 "Determination of capillary liquid rise height in paper and paperboard"; Expansion and shrinkage: GB / T 457-2008 "Determination of longitudinal and transverse wet expansion of paper and paperboard after water absorption"; Flexibility, ink absorption, and uniformity: Sensory evaluation, scored by an evaluation panel consisting of 5 professional calligraphers and painters and 3 paper engineers (1-5 points, with 5 points being the best).

[0066] Table 1. Performance test results of the calligraphy and painting paper in each embodiment and comparative example. Table 2 Results of High-Speed ​​Printing Adaptability Test The test results in Tables 1 and 2 show that: The performance indicators of the calligraphy and painting printing paper prepared in Examples 1-5 all met or exceeded the requirements of the national standard for bark calligraphy and painting paper (GB / T 22828-2008). Among them, Example 4, due to its long traditional straw burning treatment time (120 days), had the highest fiber purity, the lowest yellowing value (2.2%), and the best whiteness stability; Example 2, due to its high amount of sandalwood bark (12 parts), had the best tear strength and breaking length; Example 5, due to its high papermaking speed (120m / min), verified the high-speed printing adaptability of the calligraphy and painting paper of this invention.

[0067] Comparative Example 1 (formulation CN104963233A) has a high wet tensile strength (530 mN), but its density is too high (0.43 g / cm³). 3 The porosity is too low (2.33cm). 3 The paper has a stiff feel and a flexibility score of only 3.8; it has a high yellowing rate (6.7%) and poor long-term storage stability; the maximum papermaking speed is only 60m / min, making it unsuitable for high-speed printing.

[0068] The yellowing value (5.8%) of Comparative Example 2 (without traditional straw burning treatment) was significantly higher than that of Example 1 (2.8%), indicating poor whiteness stability. The water absorption (18mm / 60s) and ink absorption score (3.8 points) were both lower than those of Example 1, indicating that traditional straw burning treatment plays an important role in improving fiber purity and ink absorption performance.

[0069] The tear strength (185mN) and breaking length (1.98km) of Comparative Example 3 (single bamboo pulp) were significantly lower than those of Example 1, while the longitudinal and transverse strength ratio (1.63) was higher, indicating that the quaternary composite pulp system has a significant effect on improving the uniformity of paper strength and overall performance.

[0070] This invention achieves a perfect balance between the excellent properties of traditional calligraphy and painting paper and its adaptability to modern high-speed printing by organically combining a quaternary composite pulp system, a traditional straw-burning treatment process, and a multifunctional additive synergistic system. The synergistic mechanism is analyzed as follows: From a fiber perspective, the bamboo pulp undergoes a traditional straw-burning process, which effectively removes impurities such as lignin and hemicellulose. The significantly increased cellulose content and the increased number of hydroxyl groups on the fiber surface promote the formation of hydrogen bonds between fibers. Four different fiber lengths form a gradient distribution: short fibers (grass pulp) fill the gaps between fibers to improve uniformity; medium-length fibers (wood pulp, bamboo pulp) form the paper skeleton to provide basic strength; extra-long fibers (bark pulp) form a reinforcing network to improve tear strength; and special fibers enhance the interlacing strength of the fiber network. This gradient distribution of fiber length makes the paper's longitudinal and transverse strength more balanced, reducing the likelihood of paper breakage during high-speed printing.

[0071] From the perspective of additives, cationic starch in cationic starch carries a positive charge, which can form electrostatic adsorption with negatively charged fibers and fine molecules, enhancing the bonding force between fibers. Plant gums have excellent film-forming properties, forming a uniform film on the fiber surface, improving the surface strength and ink adhesion of paper. Brighteners improve the optical properties of paper, thinners improve the fluidity and dispersion uniformity of the pulp, and retention aids improve the retention rate of fine fibers and fillers. The synergistic effect of these five additives gives the paper excellent physical strength, optical properties, and printability.

[0072] From a technological perspective, the traditional straw burning process uses a gentle, natural bleaching method, avoiding damage to the fibers caused by strong chemical treatments and maintaining the natural flexibility of the fibers; the segmented drying process controls the uniformity of paper shrinkage, improving the paper's flatness and dimensional stability; and the soft calendering process gives the paper a moderate gloss and smoothness, while maintaining the paper's bulk and ink absorption.

[0073] Compared with existing technologies, the differentiated technical features of this invention are as follows: the raw material system is expanded from a binary (bamboo pulp + bamboo pulp residue) to a quaternary (bamboo pulp + wood pulp + dragon's beard grass + sandalwood bark) system, achieving a gradient distribution of fiber length; the traditional straw burning process is introduced to improve fiber purity and whiteness stability; a cationic starch synergistic additive system is used to replace the fiber grafting agent system, improving adaptability to high-speed printing; and the uncoated design maintains the natural fiber texture of the paper and avoids coating peeling problems. The organic combination of these differentiated technical features enables the calligraphy and painting printing paper of this invention to maintain the excellent characteristics of traditional calligraphy and painting paper while significantly improving high-speed printing adaptability and production efficiency.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the inventive concept of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A type of uncoated high-speed calligraphy and painting printing paper with added traditional straw, characterized in that: The paper used for calligraphy and painting printing is composed of pulp components and auxiliary components. The pulp components, by weight, include: 50-70 parts bamboo pulp, 20-35 parts white leaf wood pulp, 10-20 parts dragon beard grass pulp, 5-15 parts sandalwood bark pulp, and 0.05-0.2 parts special fibers. The auxiliary components, by total weight of the pulp components, include: 1-3% cationic starch, 0.05-0.2% brightening agent, 0.05-0.2% thickening agent, 0.3-0.8% retention aid, and 0.1-0.5% colorant. The bamboo pulp is treated with traditional straw burning.

2. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The pulp components, by weight, include: 55-65 parts bamboo pulp, 25-32 parts white leaf wood pulp, 12-18 parts dragon beard grass pulp, 8-12 parts sandalwood bark pulp, and 0.08-0.15 parts special fibers.

3. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: Based on the total weight of the slurry components, the auxiliary components include: 1.5-2.5% cationic starch, 0.08-0.15% brightener, 0.08-0.15% thickener, 0.4-0.6% retention aid, and 0.2-0.4% colorant.

4. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The bamboo pulp is selected from one or more of the following: bamboo pulp, moso bamboo pulp, and green bamboo pulp; the beating degree of the bamboo pulp is 35-50°SR, and the average fiber length is 1.5-2.8mm.

5. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The white leaf wood pulp is selected from broadleaf wood pulp or mixed softwood and broadleaf wood pulp, with a beating degree of 30-45°SR and an average fiber length of 0.8-1.2mm.

6. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The beating degree of the grass pulp is 40-55°SR, and the average fiber length is 0.6-1.0mm. The grass pulp is naturally bleached by sun exposure and rain, and the treatment cycle is 3-6 months.

7. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The bark material is selected from the bark of *Pterocarya stenoptera* or *Pterocarya stenoptera*, with a beating degree of 25-40°SR and an average fiber length of 2.5-5.0 mm.

8. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The special fiber is selected from one or more combinations of lotus fiber, mulberry bark fiber, silk fiber, and bamboo fiber, and the average length of the special fiber is 3-8 mm.

9. The uncoated high-speed calligraphy and painting printing paper according to claim 1, characterized in that: The cationic starch is a complex of cationic starch and plant gum, wherein the weight ratio of cationic starch to plant gum is 3-5:1; the plant gum is selected from one or more of astragalus gum, gum arabic, and guar gum.

10. A method for preparing uncoated high-speed calligraphy and painting printing paper as described in any one of claims 1-9, characterized in that: Includes the following steps: Step 1, Traditional Burning Treatment: Soak the bamboo pulp in clean water for 15-30 days, turning it over every 3-5 days during this period. After soaking, take it out and drain it. Then, bleach it under natural light conditions for 60-120 days by sun exposure and rain to obtain bamboo pulp treated with traditional burning. Step 2, Pulp Decomposition: The bamboo pulp, white leaf wood pulp, dragon beard grass pulp, and sandalwood bark pulp after the traditional burning process are decomposed separately for 15-30 minutes at a speed of 800-1200 rpm to obtain individual pulps of each component. Step 3: Pulp preparation and mixing: Weigh out 50-70 parts bamboo pulp, 20-35 parts white leaf wood pulp, 10-20 parts dragon beard grass pulp, 5-15 parts sandalwood bark, and 0.05-0.2 parts special fiber according to the following weight proportions, and add them to the pulp preparation tank in sequence. Add water to dilute to a pulp concentration of 2-4%, and stir and mix for 20-40 minutes to obtain the mixed pulp. Step 4: Add auxiliary materials: Add cationic starch, brightener, thickener, retention aid and colorant to the mixed slurry in sequence. Stir for 5-15 minutes after each auxiliary material is added. After all the auxiliary materials are added, continue stirring for 30-60 minutes to obtain the finished slurry. Step 5, Paper Forming: Dilute the finished pulp to a concentration of 0.05-0.15%, and feed it to the paper machine for papermaking at a speed of 80-150 m / min. The wet paper web is dewatered under vacuum to a dryness of 35-50%, and then pressed in the press section to a dryness of 40-55%. Step Six: Drying and Finishing: The pressed paper web is sequentially dried through multiple drying cylinders. The temperature of the first drying cylinder is 75-95℃, the temperature of the middle drying cylinder is 95-115℃, and the temperature of the last drying cylinder is 85-100℃. The paper is dried until the moisture content is 5-8%. After calendering, slitting, and winding, uncoated high-speed calligraphy and painting printing paper is obtained.

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