Environment-friendly degradable high-toughness paper and preparation method thereof

Abstract

The invention relates to the industrial field, in particular to environment-friendly degradable high-toughness paper and a preparation method thereof, which are characterized in that the paper not only retains the natural color and texture of medicago sativa, but also has excellent strength and durability, the uniformity and fine touch of the paper are ensured through fine crushing and proportioning, and meanwhile, the paper is not easy to be damaged. The unique preparation process effectively protects the nutritional ingredients and environmental friendliness in medicago sativa, so that the paper shows good ecological value while meeting the daily writing and printing requirements, and the paper taking the medicago sativa stubbles as the raw material is completely prepared from natural raw materials, is low in cost and wide in source, can be naturally degraded, and has a good application prospect. The strength and toughness of the paper are improved by utilizing the characteristic that the alfalfa stubbles are high in fiber content, and in addition, the preparation method is simple in process, convenient to operate and easy to popularize and apply on a large scale.

Description

Technical Field

[0001] The present invention relates to the field of industrial technology, and in particular to an environmentally friendly and degradable high-toughness paper and a preparation method thereof. Background Art

[0002] At present, the paper used in domestic publishing and printing is basically divided into two categories: 1. Coated cultural paper and uncoated cultural paper; coated cultural paper is generally traditional coated paper. The coating layer of this type of paper has been super-calendered, with extremely high gloss and good printing effect, but the visual reflection of this type of paper is glaring and not soft; 2. Uncoated paper is generally offset paper, pure paper and light paper. If these papers are printed in color, the color reproduction is poor and the printing effect cannot be achieved.

[0003] In the current paper manufacturing industry, most products use traditional wood pulp or waste paper pulp as raw materials. These materials are not only limited in source but also easily burden the environment during production and disposal. Alfalfa, a widely cultivated forage grass, often has its residues treated as waste, wasting resources and increasing environmental pressure.

[0004] Based on this, an environmentally friendly and degradable high-toughness paper and a preparation method thereof are proposed. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In order to solve the above technical problems, the present invention provides an environmentally friendly and degradable high-toughness paper and a preparation method thereof.

[0007] (2) Technical solution

[0008] Based on this, the present invention provides the following technical solution: an environmentally friendly, degradable, high-toughness paper, comprising the following components in mass percentage: 60% of the whole plant of alfalfa (dry material), 25% of softwood pulp (NBKP), 15% of waste paper pulp (office waste paper), and a pretreatment reagent: a NaOH solution (food grade) with a mass fraction of 10%, and the amount of the NaOH solution (food grade) is 2.5 times the weight of the alfalfa dry material.

[0009] Preferably, the whole alfalfa plant is a whole alfalfa plant that has been stubbled, or it can be alfalfa stubble. The source of the alfalfa stubble can be obtained by collecting the alfalfa stubble remaining after harvesting, or it can be obtained by collecting the remaining materials in the alfalfa processing enterprise. Post-harvest residue: After the alfalfa is normally harvested for use as forage, the part left in the field is the stubble, which can usually be collected directly from the alfalfa field after harvest. Generally, during the growing season of alfalfa, after multiple harvests, a certain height of stubble will be left after each harvest, which can be collected in time after harvesting as needed;

[0010] Processing residues: If it is an alfalfa processing enterprise, during the processing of alfalfa, such as making alfalfa hay, alfalfa pellets, etc., there will be some residual parts that do not meet the product quality standards or are generated during the processing process. These can also be collected as stubble.

[0011] The present invention provides another technical solution as follows: a method for preparing environmentally friendly and degradable high-toughness paper, comprising the following steps:

[0012] Step S1: cutting the pretreated alfalfa stalks into small segments of 1-2 cm, and soaking them in clean water at room temperature for 4-6 hours to fully soften the fibers, thereby effectively reducing energy consumption in the subsequent cooking process;

[0013] Step S2: After soaking, the alfalfa is placed in a vertical cooking pot and cooked with a 10% NaOH solution by weight. The liquid ratio is controlled at 1:4 (alfalfa to alkali solution by weight) and kept at 130°C for 90 minutes. At the same time, 0.05% ethylenediaminetetraacetic acid (EDTA) is added to prevent metal ions from interfering with the cooking process. The main purpose of the cooking process is to extract effective fiber. Through the action of the sodium hydroxide solution, the lignin removal rate reaches over 85%.

[0014] Step S3: After the cooking is completed, the material is mechanically disintegrated using a disc grinder. The first disc grinding gap is set to 0.8mm, and the second disc grinding gap is set to 0.3mm, and the fiber length is processed to 0.8-1.2mm;

[0015] Step S4: further purifying the fiber through screening operation, with the screening pressure set at 0.25 MPa, removing more than 85% of the coarse residue, and using a screen to remove impurities to ensure a pure and uniform fiber raw material;

[0016] Step S5: Chemical cooking: using sodium hydroxide solution for cooking, with a liquid ratio of 1:10, a temperature of 160-170°C, a pressure of 0.6-0.8 MPa, and a time of 90-120 minutes, to achieve a lignin removal rate of more than 85%;

[0017] Step S6: The fiber is washed in a countercurrent washing process using warm water (temperature controlled at 40-50°C) three times the weight of the raw material until the pH value of the wastewater is close to neutral;

[0018] Step S7: Bleaching with hydrogen peroxide, controlling the hydrogen peroxide concentration to be 3%-5%, setting the temperature to be 60-70°C, and the bleaching time to be 120 minutes;

[0019] Step S8: beating and papermaking, the bleached fiber raw material is put into the pulper, 100% of the fiber raw material is used for pulping and mixing, and then the high-quality pulp is obtained through the headbox, and then the papermaking operation is carried out;

[0020] Step S9: The paper is processed through a film transfer sizer, followed by post-baking surface treatment, and sent to a calender for treatment to improve the smoothness and glossiness of the paper, and finally formed into base paper and wound onto a paper reel.

[0021] Preferably, in step S6 as described above, the washing times are 3-4 times, and the pH value of the waste liquid is maintained in the range of 6.5-7.5.

[0022] Preferably, as described above in step S7, 0.5% magnesium sulfate is added during the bleaching process, and after the bleaching treatment, the whiteness of the paper can reach 65-70% ISO.

[0023] Preferably, as described above in step S8, the beating process adopts a low-concentration beating method, and the pulp concentration is controlled at 3%-4%. By gradually extending the beating time (about 60 minutes), the beating degree is controlled at 45-50°SR to avoid excessive fiber cutting, so as to ensure the strength and toughness of the paper.

[0024] Preferably, in step S8, the papermaking process uses a laboratory paper former to adjust the pulp concentration to 0.5%, and after vacuum dehydration, it is dried at 105°C for 30 minutes to form a paper with a basis weight of 80g / m 2 of paper.

[0025] (3) Beneficial effects

[0026] Compared with the prior art, the present invention provides an environmentally friendly and degradable high-toughness paper and a preparation method thereof, which has the following beneficial effects:

[0027] 1. This is an environmentally friendly, degradable, high-toughness paper. The alfalfa paper is environmentally friendly, non-toxic, and degradable; it has high color reproduction, reduces ink usage, and has low printing costs; it protects eyesight, has low light source reflection, and has no fluorescence; the paper is suitable for OID printing paper.

[0028] 2. This method for producing environmentally friendly, biodegradable, high-toughness paper preserves the natural color and texture of alfalfa, providing excellent strength and durability. Through fine grinding and proportioning, the paper is uniform and fine, while effectively protecting the nutrients and environmentally friendly properties of alfalfa. This paper utilizes the high fiber content of alfalfa residue to enhance its strength and toughness. It is also rich in nutrients and easily decomposes after disposal, reducing environmental pollution. The simple preparation process facilitates large-scale adoption. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] Example 1

[0031] The present invention provides the following technical solution: an environmentally friendly and degradable high-toughness paper, comprising the following components in mass percentage: 60% of alfalfa whole plant (dry material), 25% of softwood pulp (NBKP), 15% of waste paper pulp (office waste paper), and a pretreatment reagent: a NaOH solution (food grade) with a mass fraction of 10%, wherein the amount of the NaOH solution (food grade) is 2.5 times the weight of the alfalfa dry material.

[0032] In some embodiments, the whole alfalfa plant is a whole alfalfa plant that has been stubble-killed, or it can be alfalfa stubble. The source of the alfalfa stubble can be obtained by collecting the alfalfa stubble remaining after harvesting, or it can be obtained by collecting the remaining materials in the alfalfa processing enterprise. Post-harvest residue: After the alfalfa is normally harvested for forage and other purposes, the part left in the field is the stubble, which can usually be collected directly from the alfalfa field after harvest. Generally, during the growing season of alfalfa, after multiple harvests, a certain height of stubble will be left after each harvest, which can be collected in time after harvesting as needed;

[0033] Processing residues: If it is an alfalfa processing enterprise, during the processing of alfalfa, such as making alfalfa hay, alfalfa pellets, etc., there will be some residual parts that do not meet the product quality standards or are generated during the processing process. These can also be collected as stubble.

[0034] The present invention provides another technical solution as follows: a method for preparing environmentally friendly and degradable high-toughness paper, comprising the following steps:

[0035] Step S1: cutting the pretreated alfalfa stalks into small segments of 1-2 cm, and soaking them in clean water at room temperature for 4-6 hours to fully soften the fibers, thereby effectively reducing energy consumption in the subsequent cooking process;

[0036] Step S2: After soaking, the alfalfa is placed in a vertical cooking pot and cooked with a 10% NaOH solution by weight. The liquid ratio is controlled at 1:4 (alfalfa to alkali solution by weight) and kept at 130°C for 90 minutes. At the same time, 0.05% ethylenediaminetetraacetic acid (EDTA) is added to prevent metal ions from interfering with the cooking process. The main purpose of the cooking process is to extract effective fiber. Through the action of the sodium hydroxide solution, the lignin removal rate reaches over 85%.

[0037] Step S3: After the cooking is completed, the material is mechanically disintegrated using a disc grinder. The first disc grinding gap is set to 0.8mm, and the second disc grinding gap is set to 0.3mm, and the fiber length is processed to 0.8-1.2mm;

[0038] Step S4: further purifying the fiber through screening operation, with the screening pressure set at 0.25 MPa, removing more than 85% of the coarse residue, and using a screen to remove impurities to ensure a pure and uniform fiber raw material;

[0039] Step S5: Chemical cooking: using sodium hydroxide solution for cooking, with a liquid ratio of 1:10, a temperature of 160-170°C, a pressure of 0.6-0.8 MPa, and a time of 90-120 minutes, to achieve a lignin removal rate of more than 85%;

[0040] Step S6: The fiber is washed in a countercurrent washing process using warm water (temperature controlled at 40-50°C) three times the weight of the raw material until the pH value of the wastewater is close to neutral;

[0041] Step S7: Bleaching with hydrogen peroxide, controlling the hydrogen peroxide concentration to be 3%-5%, setting the temperature to be 60-70°C, and the bleaching time to be 120 minutes;

[0042] Step S8: beating and papermaking, the bleached fiber raw material is put into the pulper, 100% of the fiber raw material is used for pulping and mixing, and then the high-quality pulp is obtained through the headbox, and then the papermaking operation is carried out;

[0043] Step S9: The paper is processed through a film transfer sizer, followed by post-baking surface treatment, and sent to a calender for treatment to improve the smoothness and glossiness of the paper, and finally formed into base paper and wound onto a paper reel.

[0044] In some embodiments, in step S6 as described above, the number of washing times is 3-4 times, and the pH value of the waste liquid is maintained in the range of 6.5-7.5. In step S7 as described above, 0.5% magnesium sulfate is added during the bleaching process. After bleaching, the whiteness of the paper can reach 65-70% ISO. In step S8 as described above, the beating process adopts a low-concentration beating method to control the pulp concentration at 3%-4%. By gradually extending the beating time (about 60 minutes), the beating degree is controlled at 45-50°SR to avoid excessive fiber cutting to ensure the strength and toughness of the paper. In step S8 as described above, a laboratory paper sheet former is used in the papermaking process to adjust the pulp concentration to 0.5%. After vacuum dehydration, it is dried at 105°C for 30 minutes to make a paper with a basis weight of 80g / m 2 of paper.

[0045] In this application, the pulper is used to disintegrate pulp board, waste paper and fiber raw materials, and realize fiber separation through mechanical shearing and hydraulic impact, and has the function of mixing chemicals or removing impurities. The headbox can evenly distribute the pulp: evenly distribute the pulp along the transverse direction of the paper machine, ensure the consistency of pressure, flow, concentration and fiber orientation, and eliminate transverse pulp flow or longitudinal strip flow; fiber dispersion and anti-flocculation: high-intensity micro-turbulence is generated by the turbulence generator to effectively disperse the fibers, prevent precipitation and re-flocculation, and improve the strength of the paper sheet. Spraying stability control: precise Accurately adjust the pulp speed to match the wire speed (pulp-to-wire speed ratio), control the spraying angle, landing point and pulp drop position, and ensure the longitudinal quantitative stability of the paper web. The film transfer sizing machine has a film transfer mechanism. The sizing liquid is accurately pre-coated on the surface of the sizing roller through the metering rod to form a uniform film. When the paper web passes through the double-roller pressure area, the film is directly transferred to the paper surface, which significantly reduces the hydraulic impact of traditional sizing, reduces the paper breakage rate and improves the operating stability. The disc grinder continuously beats the pulp through the rotating grinding disc to achieve fiber decomposition, filament separation and brooming, and improve the strength of the paper.

[0046] In summary, the environmentally friendly, biodegradable, high-toughness paper and its preparation method proposed in this invention demonstrate significant advantages and potential in terms of raw material selection, process innovation, product performance, and environmental benefits. This invention not only provides a new green production model for the paper industry but also offers a high-quality solution to meet the diverse needs of paper in various fields. It has broad market prospects and significant social benefits, and is expected to promote the development of the paper industry towards a more environmentally friendly, efficient, and sustainable direction.

[0047] Example 2

[0048] Taking alfalfa fiber as an auxiliary material added to the production of rice paper to improve the performance of rice paper as an example, the preparation method for achieving the above purpose includes the following steps:

[0049] (1) Preparation of Chinese cedar bark and rice straw: Prepare high-quality Chinese cedar bark and rice straw as the main raw materials for making Xuan paper, and process them according to traditional methods such as soaking, steaming, and drying to make bark slurry and straw slurry.

[0050] (2) Alfalfa fiber extraction, cutting and crushing: The harvested alfalfa is removed from the roots and impurities, cut into 1-2 cm small segments, and then placed in a grinder for crushing to make it into smaller fiber fragments for subsequent processing.

[0051] (3) Chemical treatment: The crushed alfalfa fiber is placed in a reactor and an appropriate amount of chemical agents, such as sodium hydroxide and hydrogen peroxide, are added for steaming and bleaching. Chemical treatment can remove impurities such as lignin and pectin from the alfalfa fiber, improve the purity and whiteness of the fiber, and make the fiber softer and easier to disperse. The mixture is kept at 130°C for 90 minutes. At the same time, 0.05% ethylenediaminetetraacetic acid (EDTA) is added to prevent metal ions from interfering with the steaming process.

[0052] (4) Mechanical beating: After chemical treatment, the alfalfa fiber is placed in a pulping machine for mechanical beating to further refine the fiber to a length and fineness suitable for papermaking and increase the bonding strength between the fibers.

[0053] (5) Mixing papermaking pulp: Mix the extracted alfalfa fiber with the cinnamon bark pulp and the rice straw pulp in a certain proportion. Generally, the proportion of alfalfa fiber can be adjusted between 10% and 30% as needed. During the mixing process, add appropriate amount of water and paper medicine (such as kiwi vine juice) to make the pulp reach the appropriate concentration and fluidity.

[0054] (6) Papermaking: Using traditional bamboo screen papermaking or modern papermaking equipment, the mixed pulp is evenly spread on a bamboo screen or papermaking net to form a wet paper sheet. Then, through processes such as pressing and drying, the moisture in the wet paper sheet is removed, and the paper is dried and shaped, finally making Xuan paper containing alfalfa fiber.

[0055] The Xuan paper containing alfalfa fiber obtained by the above method is a specialty paper made by adding alfalfa fiber as an auxiliary raw material to traditional Xuan paper (the main raw materials are celtis bark and paddy straw). Its advantages are mainly reflected in the raw material characteristics, paper performance, environmental value, etc., as follows:

[0056] Alfalfa Xuan paper incorporates alfalfa fiber into traditional Xuan paper raw materials. The addition of alfalfa fiber broadens the raw material source, alleviating the pressure on the supply of traditional raw materials to a certain extent, while also bringing some new changes to the performance of Xuan paper. In areas where the resources of celtis sinensis bark are scarce, the addition of alfalfa fiber can reduce dependence on a single raw material and maintain the stability of Xuan paper production. Alfalfa fiber contains a high cellulose content (approximately 30% to 40%) and has a moderate fiber length (approximately 1 to 2 mm). When mixed with celtis sinensis bark fibers (long and flexible) and rice straw fibers (short and loose), it can form a more uniform fiber network, improving the overall performance of the paper. This makes Xuan paper more durable and more suitable for the creation and long-term preservation of large-scale works.

[0057] Alfalfa fiber is highly resilient and can improve the physical strength of Xuan paper. For example, adding 10% to 20% alfalfa fiber to traditional Xuan paper can increase its tensile strength by 10% to 15%, making it more suitable for large-scale artwork or long-term preservation.

[0058] Application scenarios: Suitable for long scrolls of calligraphy, Chinese ink paintings, and other scenes that require paper to be resistant to folding and pulling.

[0059] The pore structure of alfalfa fiber differs from that of traditional raw materials, allowing the paper's ink absorption rate to be controlled by adjusting the mixing ratio. Low-ratio addition (5% to 10%) allows the paper to retain the ink-absorbing properties of traditional rice paper, making it suitable for freehand Chinese painting, with distinct layers of ink.

[0060] Adding in medium to high proportions (20% to 30%): The ink absorption speed is slightly faster, which is more suitable for fine brushwork or small calligraphy, and the ink color is stable and not easy to spread.

[0061] Chemical treatment of alfalfa fiber reduces its lignin content (one of the main causes of yellowing and brittleness in paper), slowing down paper aging. Studies have shown that in light aging tests, rice paper containing alfalfa fiber retains 5% to 8% more whiteness than traditional rice paper, making it more suitable for the long-term preservation of archival documents or artwork.

[0062] It can also reduce deforestation and protect the ecosystem. Pterocarpus chinensis has a long growth cycle (it takes more than 10 years to mature), and large-scale deforestation could damage mountain ecosystems. Alfalfa is an annual herb with a short growing cycle (it can be harvested three to four times a year). Its nitrogen-fixing ability improves soil fertility, aligning with the concept of sustainable development.

[0063] At the same time, each acre of alfalfa can fix about 10 kilograms of nitrogen each year, which is equivalent to reducing the use of chemical fertilizers by 15 to 20 kilograms and reducing agricultural non-point source pollution.

[0064] It is also conducive to the reuse of agricultural waste. The stems of alfalfa after harvest (traditionally used as feed or directly discarded) can be used to extract fiber, realizing the "resourceization of agricultural waste", reducing air pollution caused by incineration, and at the same time increasing additional income for farmers (the stem recycling price is about 200 to 300 yuan / ton).

[0065] With unique texture and artistic effects, the irregular distribution of alfalfa fibers can form a subtle texture on the surface of the paper, creating a texture similar to "antique paper", which is suitable for expressing the vicissitudes of life or special brushstroke effects in traditional calligraphy and painting, providing artists with more creative possibilities.

[0066] Some modern ink painters may try to create with alfalfa rice paper, using its texture to enhance the layering and visual impact of the picture. In addition to traditional calligraphy and painting, alfalfa rice paper can also be used for: handmade book binding: as cover or inner page due to its high strength and uniform ink absorption.

[0067] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly and degradable high-toughness paper, characterized by: The method comprises the following components in percentage by mass: 60% of whole alfalfa plant (dry material), 25% of softwood pulp (NBKP), 15% of waste paper pulp (office waste paper), and a pretreatment reagent: a NaOH solution (food grade) with a mass fraction of 10%, wherein the amount of the NaOH solution (food grade) is 2.5 times the weight of the alfalfa dry material.

2. The environmentally friendly, biodegradable, high-toughness paper according to claim 1, characterized in that: The whole alfalfa plant is a whole alfalfa plant that has been subjected to stubble removal treatment.

3. A method for preparing environmentally friendly and degradable high-toughness paper, characterized by: The following steps are involved: Step S1: cutting the pretreated alfalfa stems into small segments of 1-2 cm and soaking them in clean water at room temperature for 4-6 hours; Step S2: After soaking, the alfalfa is placed in a vertical cooking pot and steamed with a 10% by mass NaOH solution at a liquid ratio of 1:4 (weight ratio of alfalfa to alkali solution). The alfalfa is kept warm at 130° C. for 90 minutes, and 0.05% ethylenediaminetetraacetic acid (EDTA) is added. Step S3: After the cooking is completed, the material is mechanically disintegrated using a disc grinder. The first disc grinding gap is set to 0.8mm, and the second disc grinding gap is set to 0.3mm, and the fiber length is processed to 0.8-1.2mm; Step S4: further purifying the fibers through a screening operation, with the screening pressure set at 0.25 MPa, removing more than 85% of the coarse residue, and using a screen to remove impurities; Step S5: Chemical cooking: using sodium hydroxide solution for cooking, with a liquid ratio of 1:10, a temperature of 160-170°C, a pressure of 0.6-0.8 MPa, and a time of 90-120 minutes, to achieve a lignin removal rate of more than 85%; Step S6: The fiber is washed in a countercurrent washing process using warm water (temperature controlled at 40-50°C) three times the weight of the raw material until the pH value of the wastewater is close to neutral; Step S7: Bleaching with hydrogen peroxide, controlling the hydrogen peroxide concentration to be 3%-5%, setting the temperature to be 60-70°C, and the bleaching time to be 120 minutes; Step S8: beating and papermaking, putting the bleached fiber raw material into a pulper, using 100% of the fiber raw material for pulping and mixing operations, and then passing through a headbox to obtain pulp, and then proceeding to papermaking operations; Step S9: The paper after papermaking is processed by a film transfer sizer, followed by post-baking surface treatment, and sent to a calender for further processing, finally forming base paper and winding it to a paper reel.

4. The method for preparing environmentally friendly and degradable high-toughness paper according to claim 3, characterized in that: As described above in step S6, the washing times are 3-4 times, and the pH value of the waste liquid is maintained in the range of 6.5-7.

5.

5. The method for preparing environmentally friendly and degradable high-toughness paper according to claim 3, characterized in that: As described above in step S7, 0.5% magnesium sulfate is added during the bleaching process. After the bleaching process, the whiteness of the paper can reach 65-70% ISO.

6. The method for preparing environmentally friendly and degradable high-toughness paper according to claim 3, characterized in that: As described above in step S8, the beating process adopts a low-concentration beating method to control the pulp concentration at 3%-4%. By gradually extending the beating time (about 60 minutes), the beating degree is controlled at 45-50°SR to avoid excessive fiber cutting to ensure the strength and toughness of the paper.

7. The method for preparing environmentally friendly and degradable high-toughness paper according to claim 3, characterized in that: In step S8, the papermaking process uses a laboratory paper former to adjust the pulp concentration to 0.5%, and after vacuum dehydration, it is dried at 105°C for 30 minutes to form a paper with a basis weight of 80g / m 2 of paper.