Preparation method of zero-quantification VOCs (volatile organic compounds) degradable seedling raising paper

Abstract

The invention discloses a preparation method of degradable seedling raising paper with zero quantification of VOCs (volatile organic compounds). The preparation method comprises the following operation steps: S1, raw material selection: fiber raw materials comprise 75-85% by mass of typha angustifolia and 15-25% by mass of reeds; s2, the fiber raw materials in S1 are subjected to the following procedures in sequence; the preparation method comprises the following steps: preparing typha angustifolia and reeds, stewing in a vertical pot, sealing and screening, washing pulp, carrying out oxygen delignification, concentrating the pulp, preparing unbleached chemical straw pulp, preparing into a pulp storage tower, preparing into a pulp extruding machine, carrying out high-concentration grinding, preparing into a latency tank, preparing into a conical pulping machine, preparing into a pulp preparing tank, preparing into a pulp forming tank, desanding, screening, forming on a net, squeezing, pre-drying, carrying out surface sizing, post-drying and calendering. The seedling raising paper meeting the requirements of ecological agricultural paper is prepared. The seedling raising paper obtained by the invention has good paper air permeability and high dry and wet strength, has weather resistance of wind and rain wash resistance and treading resistance, can realize natural degradation of microorganisms in soil, has the characteristics of zero quantity of VOCs (Volatile Organic Compounds) degradability and sustainable circulation of all raw materials, and is green, environment-friendly and pollution-free to soil.

Description

Technical Field

[0001] The invention relates to the technical field of seedling-growing paper, and in particular to a method for preparing zero-quantity VOCs degradable seedling-growing paper. Background Art

[0002] With the advancement of agricultural production technology and the continuous development of ecological agriculture, the planting technology of grain and cash crops has also undergone fundamental changes. Agricultural mechanization is gradually replacing traditional manual operations, and production efficiency has increased several times. In order to cooperate with agricultural mechanization operations, factory-based seedling cultivation has been widely promoted and used. The traditional seedling containers are mainly made of plastic, non-woven fabrics and paper; plastic containers and non-woven seedlings are not only prone to root nesting, but also slow to root after transplanting, and have a long seedling period, which affects growth or yield. In addition, plastics are not easy to degrade, and microplastic particles after degradation will affect the survival of organisms and humans. At the same time, various VOCs are easily produced during the degradation process, polluting the ecological environment. Paper seedling containers are made of paper, which is breathable and water-permeable, conducive to air rooting, and forming a developed capillary root system. They are easy to degrade after transplanting, and plants root quickly, without restricting root growth. They are environmentally friendly and do not form pollution. Efficient seedling paper plays a positive role in forming a good food ecological chain to assist the greening of agricultural products and meet people's requirements for trace elements in green agricultural products. It is a good choice for seedling containers. However, the seedling process requires a higher wet strength, which is difficult for ordinary paper to meet.

[0003] Therefore, how to provide an efficient seedling paper with high dry strength and appropriate wet strength, good air permeability, water permeability, seedling lateral root penetration and soil holding ability, which can be completely degraded within 45-60 days, meets the growth requirements of crops, and is suitable for paper tube seedling transplanting and cultivation methods is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing zero-VOCs degradable seedling paper. The preparation method of the present invention is suitable for completing the production of seedling paper in a paper tube seedling transplanting and cultivation method in one step on a papermaking machine. The papermaking process is dry and energy-efficient. The obtained seedling paper has good paper air permeability and high dry and wet strength, weather resistance against wind, rain erosion and trampling, can achieve natural degradation by microorganisms in the soil, and all raw materials are characterized by zero-VOCs degradable and sustainable circulation, which is green and environmentally friendly and harmless to the soil.

[0005] The technical solution provided by the present invention is as follows: A method for preparing zero-quantitative VOCs degradable seedling paper comprises the following steps: S1. Raw material selection: The fiber raw materials include 75-85% cattail and 15-25% reed by mass fraction; S2. The fiber raw materials described in S1 are sequentially subjected to the following processes: cattail + reed → vertical pot cooking → closed screening → pulp washing → oxygen delignification → pulp concentration → unbleached chemical straw pulp → pulp storage tower → pulp squeezer → high-concentration mill → latent force elimination tank → conical pulp refiner → pulp blending tank → pulping tank → sand removal → screening → forming on the net → pressing → pre-drying → surface sizing → post-drying → calendering, so as to obtain seedling paper that meets the requirements of ecological agricultural paper.

[0006] The above-mentioned seedling paper is prepared with preferred raw and auxiliary materials and high-efficiency chemical additives, and is made of natural cattail and reed mixed pulp prepared by sulfur-free caustic soda method. The water-soluble sulfate and water-soluble chloride of the paper are ≤200mg / L, the density is ≥0.55g / cm3, the longitudinal tensile strength index is ≥75.0N·m / g, the longitudinal wet tensile index is ≥22N·m / g, and the bursting index is ≥3.2 kPa.m 2 / g, sizing degree ≥10s, air permeability ≥6.0μm / (Pa·s), front smoothness ≥20s. The natural chemical straw pulp prepared by caustic soda method has excellent physical properties and is the best among grass fibers. The reasonable combination of fiber raw materials and the full combination of the advantages of the two types of fiber raw materials are suitable for the production of zero-quantity VOCs degradable sustainable recycling efficient seedling paper, which conforms to the characteristics of green ecological agriculture and environmental protection seedling cultivation.

[0007] Preferably, the caloric value of the pulp formed by cattail + reed in step S2 is 33±3, the pulp whiteness is 29±1%ISO, the fiber length is ≥1.69mm, the width is ≥13.2μm, the aspect ratio reaches 128, the breaking length is ≥10.25km, and the tear index is ≥12.3mN.m 2 / g, bulk ≥2.12cm3 / g, air permeability ≥5.6µm / (Pa.s).

[0008] Preferably, in step S2, during vertical pot cooking, caustic soda is added into the pot, the amount of caustic soda used accounts for 15-25% of the total cooking liquid volume, the material-liquid ratio is 1:(4-6), the cooking temperature is 100-160° C., and the cooking time is 180-300 minutes.

[0009] Preferably, the oxygen delignification process in step S2 ensures that the mixed pulp does not contain toxic and harmful substances such as elemental chlorine and dioxins, and has the characteristics of high fiber bulk, fast moisture absorption and release speed, excellent air permeability, and green environmental protection.

[0010] Preferably, in the high-concentration grinding process in step S2, the refining current used is 2000-2200A, the refining concentration is 25-30%, the beating degree of the pulp after grinding is about 25-28°SR, and the wet weight of the pulp is 13-18g.

[0011] Preferably, in step S2, the cone refiner uses a cone refiner with a conical pulping current of 150 to 200 A, a low-concentration pulping concentration of 4.0 to 5.5%, a pulping degree of 28 to 35° SR, and a wet weight of the pulp of 10 to 15 g.

[0012] According to the use scenarios and environments of seedling paper, it is not only necessary to have high dry strength and high wet strength to ensure that the paper tube is not broken or trampled during 35-60 days of seedling raising or transplanting, but also to have certain air permeability to adapt to the root development during the growth of crop seedlings. To this end, the present invention adopts a two-stage mixed pulping method of high-concentration pulping + low-concentration pulping for the selected fiber raw materials; that is, the mixed pulp according to the process ratio is first subjected to high-concentration pulping, and then subjected to cone mill low-concentration pulping treatment. Because of its long fiber and high strength, the natural chemical cattail pulp can be made flexible after being filamented and broomed by the high-temperature and high-pressure kneading through high-concentration pulping, and then subjected to cone mill debonding treatment to obtain a pulp with a SR of 28 to 35°, which is beneficial to ensure the uniformity of the paper. Therefore, the pulping method of high-concentration pulping + low-concentration pulping can not only reflect the complementary advantages of high-concentration pulping to achieve a good pulping effect, but also improve the strength, air permeability and thickness of the seedling paper.

[0013] Preferably, in the step S2, chemical additives are added to the pulp preparation tank in the following order: barrier material P-V8→SPC508 cationic rosin glue→PAC→defoaming agent, wherein the barrier material P-V8 is used in an amount of 10.0-15.0% per ton of paper, the amount of SPC508 cationic rosin glue per ton of paper is 0.5-1.0%, SPC508 cationic rosin glue is a product produced by Arakawa Chemicals Co., Ltd., SPC cationic rosin glue with a solid content of 35±1% is added to the pulp preparation tank, the amount of PAC per ton of paper is 1.0-1.5%, and the amount of defoaming agent per ton of paper is 0.05-0.2%, and the added chemical additives are added by weight ratio to the absolute dry pulp amount.

[0014] Cationic rosin glue mechanism: Cationic rosin glue has a certain charge density (Zeta potential of about +20mv), and can stay on the negatively charged fiber surface by itself. Through the effective flocculation of aluminum sulfate, a hydrophobic layer is formed on the fiber surface, making it water-resistant. The SPC508 cationic rosin glue selected in the present invention is a positively charged emulsion made of rosin and cationic polymer surfactants. It has low dependence on aluminum sulfate, can adapt to a wide pH range, and can reduce the brittleness of paper.

[0015] Preferably, the barrier material P-V8 in step S2 is a nanoscale water-based narrow molecular weight distribution acrylic copolyester. The "nanoscale water-based narrow molecular weight distribution acrylic copolyester" selected in the present invention is a pure water-based linear functional resin material with a special molecular structure, a solid content of 40±1.0%, and a viscosity of 200±50 mPa·s; its main characteristics are nanoscale, narrow bandwidth and normal molecular weight distribution characteristics, and a linear main structure. While ensuring the stability of the material, it has excellent microbial degradation performance, environmentally friendly waterproof and oil-proof properties, process adaptability, greatly reduces the use of additives, and greatly improves the performance of seedling paper. The mechanism of action of nano-scale water-based narrow molecular weight distribution acrylic copolyester: with the homopolymer structure of the functional groups inside the molecule plus its nano characteristics, and the monodispersity and dispersibility of the linear functional copolyester, it has chemical functionality and physical methods to improve the adhesion to the fiber surface, and forms self-crosslinking between acrylic copolyesters and co-crosslinking between acrylic copolyesters and fibers at the fiber interface. The self-crosslinking effect is that the acrylic copolyester produces a staggered chain structure around the fiber, which limits the swelling of the fiber to a certain extent and thus increases the wet strength; the co-crosslinking effect is that the acrylic copolyester forms new bonds with some hydroxyl groups on adjacent fibers, especially the formation of a water-resistant covalent bond crosslinking network is the most critical to improving the waterproofness and strength of paper. The formulated seedling paper is sustainable, recyclable and degradable.

[0016] PAC with a solid content of 12.5±1% is added before the slurry pump. Its main function is to adjust the pH value and PCD of the system, react with cationic rosin glue to form a water-resistant layer on the fiber surface, and improve the Zeta potential of the slurry system.

[0017] Preferably, the concentration of the slurry during the net forming in step S2 is 0.3-0.35%.

[0018] Preferably, in step S2, after the wet paper is further squeezed and dehydrated in the pressing section, it is pre-dried to a dryness of 93-96%, and then a membrane transfer surface sizing machine is used to treat the front surface of the paper. After surface sizing, the paper is post-dried and then soft calendered for paper surface finishing, and then the paper is rolled up, and finally rewound and cut into seedling paper rolls of the specifications required by the customer; the surface sizing solution is prepared with cassava starch, nano antibacterial agent, and water repellent TF-535C, and has water-resistant, antibacterial, and reinforcing effects; the metering rod model is 1#, and the metering rod pressure is 100kpa; the paper tension before the sizing machine is 220N / m 2 , the paper tension after gluing is 200N / m 2 Water repellent TF-535C is a translucent liquid, cationic, with a solid content of 25±1% and a pH of 4-7. It is water and oil resistant, and has excellent water resistance for the finished paper. It has the advantages of small dosage, no effect on air permeability, and can improve the strength of the finished paper.

[0019] Preferably, the sizing concentration of the surface sizing solution in step S2 is controlled at 8.0-10.0%, and the double-sided sizing amount is controlled at 2.0-4.0 g / m 2 ; The amount of nano antibacterial agent in the surface sizing solution is controlled at 5.0-10.0 kg / ton of paper; The amount of water repellent TF-535C in the surface sizing solution is controlled at 5.0-10.0 kg / ton of paper. Nano antibacterial agent is a new type of multifunctional environmentally friendly inorganic antibacterial agent material with nano active oxide as the main effective ingredient. The product has high activity and has the function of inhibiting Escherichia coli AS 1.90, Staphylococcus aureus AS 1.89, Candida albicans ATCC 10231, and other strains. It has unique advantages in antibacterial and mildew resistance. The addition of nano antibacterial agent makes the seedling paper itself have the performance of highly efficient and continuous inhibition of various common bacteria, fungi, molds and viruses, and purifies the soil environment.

[0020] The present invention has the following advantages over the prior art: (1) The papermaking raw materials of the present invention are non-wood plant fibers, and the chemical additives are preferably nano-scale pure water-based linear functional resin materials, long-lasting odor-free, antibacterial and self-cleaning nano-antibacterial agents, high-efficiency water-repellent agents, etc. The products are green and environmentally friendly products, do not contain any halogen, have zero VOC, and significantly reduce energy consumption and carbon emissions; (2) The present invention uses pure plant fiber as the main material, preferably non-wood fiber medium and long fiber cattail and reed, and uses the caustic soda method to prepare paper pulp. The fiber raw material is artificially planted, highly renewable, easy to obtain, saving limited wood resources and protecting the ecological environment; (3) The bio-non-toxic design of the constituent materials of the preparation method of the present invention adopts sulfur-free and low-toxic pulping technology, and preferably uses nano-level pure water-based resin and nano-level antibacterial agent to assist in enhancing water resistance, mildew resistance and antibacterial properties, has high efficiency in enhancing water resistance and antibacterial properties, zero quantitative VOCs, and does not use urea-formaldehyde resin and melamine-formaldehyde resin that have a negative impact on fiber degradation; (4) The preparation method of the present invention adopts a gas permeability control method, and the application of high-concentration pulping technology reduces the cutting of fibers and reduces the influence of fine components on air permeability; at the same time, the nano-scale water-based narrow molecular weight distribution acrylic copolyester has the characteristics of nano-scale, narrow bandwidth and normal molecular weight distribution, and the intermolecular van der Waals force is enhanced, so it has the characteristics of good adsorption performance, large inter-fiber pores and fast drying speed; (5) The preparation method of the present invention adopts a degradable composition design. The fiber quality of cattail pulp in non-wood fiber is the best among grass plants. Nano-scale water-based narrow molecular weight distribution acrylic copolyester material is used for water resistance enhancement. Copolyester fiber is carried on paper fiber and entangled to form a mesh structure. There is no need for physical re-pulping by separation (process water is recycled). DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0022] Example 1: 60 g / m 2 Zero quantitative VOCs biodegradable sustainable recycling efficient seedling paper The natural chemical straw pulp with a calorific value of 31 prepared by caustic soda method with 75% cattail + 25% reed is pumped to the pulp storage tower of the pulping section of the papermaking workshop, and then pumped to the double-roll pulping machine to extrude the pulp concentration to a high-concentration pulp of about 29%. The high-concentration pulp is crushed by a crushing screw and then fed into a high-concentration pulping machine for high-concentration refining. The power of the high-concentration pulping machine is 2050A. The pulp after high-concentration refining has a beating degree of 28ºSR and a wet weight of 15 grams. At this time, the pulp is not suitable for direct online papermaking. It needs to be diluted and de-latched with warm white water at 45°C for 35 minutes. The pulp is diluted and de-latched to a low-concentration pulp of 4.5%, and then pumped to a cone mill for two mills in series to de-lamination and pulping. The beating currents of the two cone mills are 160A and 180A respectively, and the beating degree is 32ºSR and the wet weight is 12 grams; in the beating In the back pool, 85kg / ton of P-V8 (nano-grade water-based narrow molecular weight distribution acrylic copolyester) and 15kg / ton of PAC are added in sequence. The pulp is fully mixed and stirred to a concentration of 0.3%, and then sent to a sand remover to remove impurities through a pulp flushing pump. The good pulp after sand removal is sent to a pressure screen, and cationic rosin glue is added at 8.0kg / t of pulp at the inlet of the pressure screen. The mixed pulp is dispersed through the pressure screen and enters the front box for homogenization and then goes online for dehydration and forming; after the wet paper sheet passes through the first, second and third pressing zones, the wet paper web is dried to a dryness of 96% and enters the surface sizing machine. The paper is surface sizing treated by membrane transfer. The surface sizing solution is prepared with cassava starch, Asahikawa nano antibacterial agent and water repellent TF-535C. The sizing concentration is controlled at 10%, and the single-sided sizing amount is 2.0g / m 2 The dosage of nano antibacterial agent is controlled at 8.0kg / t paper, and the dosage of water repellent agent is controlled at 8.0kg / t paper; the wet paper sheets after surface sizing are dried by post-drying cylinder and then soft calendered for surface finishing. After soft calendering, the paper sheets with a dryness of 91.5% are rolled into mother rolls and then rewound and slit to obtain a basis weight of 60g / m 2 Highly efficient seedling paper.

[0023] Example 2: 58 g / m 2Zero quantitative VOCs biodegradable sustainable recycling efficient seedling paper The natural chemical straw pulp with a calorific value of 33 prepared by caustic soda method with 85% cattail + 15% reed is pumped to the pulp storage tower of the pulping section of the papermaking workshop, and then pumped to the double-roll pulping machine to extrude the pulp concentration to a high-concentration pulp of about 29%. The high-concentration pulp is crushed by a crushing screw and then fed into a high-concentration pulping machine for high-concentration refining. The power of the high-concentration pulping machine is 2050A. The pulp beating degree after high-concentration refining is 29ºSR, and the wet weight is 15.0 grams. At this time, the pulp is not suitable for direct online papermaking. It needs to be diluted and de-latched with warm white water at 45°C for 35 minutes. The pulp is diluted and de-latched to a low-concentration pulp of 5.0%, and then pumped to a cone mill for two mills to be connected in series for delamination and pulping. The beating currents of the two cone mills are 170A and 200A, respectively, and the beating degree is 35ºSR, and the wet weight is 10.5 grams; in the post-beating pool 90.0kg / ton of P-V8 (nano-grade water-based narrow molecular weight distribution acrylic copolyester) and 12.0kg / ton of PAC are added in sequence. The pulp is fully mixed and stirred to a concentration of 0.32%. It is sent to a sand remover to remove impurities through a pulp pump. The good pulp after sand removal is sent to a pressure screen, and cationic rosin glue is added at 8.0kg / t of pulp at the inlet of the pressure screen. The mixed pulp is dispersed through the pressure screen and then enters the head box for homogenization and then goes online for dehydration and forming; after the wet paper sheet passes through the first, second and third pressing zones, the wet paper web is dried to a dryness of 95.0% and enters the surface sizing machine. The paper is surface sizing treated by membrane transfer. The surface sizing solution is prepared with cassava starch, Asahikawa nano antibacterial agent and water repellent TF-535C. The sizing concentration is controlled at 10%, and the single-sided sizing amount is 2.0g / m 2 The dosage of nano antibacterial agent is controlled at 10.0kg / t paper, and the dosage of water repellent agent is controlled at 8.0kg / t paper; the wet paper sheet after surface sizing is dried by the post-drying cylinder and then soft calendered for surface finishing. The paper sheet with a dryness of 91.70% after soft calendering is rolled into a mother roll and then rewound and slit to obtain a basis weight of 58.0g / m 2 Highly efficient seedling paper.

[0024] The indexes of the seedling-raising paper in the above-mentioned embodiments 1-2 are shown in Table 1 below: Table 1 Index of seedling paper in Example 1-2

[0025] It can be seen from Table 1 above that the seedling paper tube made by processing the zero-quantity VOCs degradable sustainable circulation high-efficiency seedling paper produced by the present invention has obvious faster soil filling and higher efficiency compared with plastic nutrient pot seedlings. According to the observation of the seedling staff during the seedling period, the paper bag is well maintained after 30 days of seedling cultivation, and the seedlings do not fall apart when they are lifted. When transplanting, seedlings grown in paper bags can be directly planted, the seedling return period is short, the plant root system is not damaged, which is conducive to plant growth, and the growth of crops is better than that of plastic nutrient pot seedlings, which meets the requirements of large ecological agriculture pollution-free economic crop planting.

[0026] The following are several reports related to the preparation method of this embodiment: 1. Experimental research report on natural reed pulp mixed with kraft paper 1. Experimental plan 1.1 Natural chemical straw pulp + reed pulp is provided by MCC Galaxy Paper, with a raw pulp beating degree of 28.0SR; semi-chemical bamboo pulp, with a raw pulp beating degree of 14.5SR.

[0027] 1.2 Pulp ratio: Natural chemical grass pulp (mixed cooking of cattail and reed) and semi-chemical bamboo pulp are pulped separately by PFI disc grinding. The grass pulp is lightly pulped and then mixed with semi-chemical bamboo pulp with a beating degree of 30-35SR.

[0028] 1.3 According to the ratio requirements, add 10%, 20%, 30%, and 40% semi-chemical bamboo pulp to the straw pulp respectively. After the pulp is prepared, make sheets, squeeze and dry them. Finally, the sheets are treated with constant temperature and humidity balance to test the relevant performance indicators.

[0029] 2. Experimental results Table 2 Strength performance of sheet

[0030] Table 3 Whiteness and hue of the sheets

[0031] It can be seen from Tables 2 and 3 that semi-chemical bamboo pulp has more dust in its fiber bundles and lower strength, and is not suitable for papermaking of seedling paper with high strength requirements. Compared with semi-chemical bamboo pulp after tapping, natural cattail pulp has higher whiteness, strength and bulk. With the increase of the proportion of natural cattail pulp, the strength and whiteness of the paper sheets increase significantly, and pilot production is recommended.

[0032] 2. Experimental report on the effects of different chemical additives on water resistance of seedling paper In order to develop and produce high-efficiency ecological seedling paper that can meet the market shortage, product developers conducted experimental research on water resistance and enhanced papermaking.

[0033] 1. Purpose The main purpose of the experiment: to obtain the process of improving the wet strength and water resistance of paper through experiments; that is, wet tensile strength ≥ 1.5kN / m, water absorption ≤ 10.0g / m 2 .

[0034] 2 Experimental plan (1) Pulp: chemical cattail pulp by caustic soda process, semi-chemical bamboo pulp; (2) Beating degree: semi-chemical bamboo pulp 28-32°SR, chemical straw pulp 30-33°SR; use PFI disc grinding to 3500r and 5000r respectively, and the beating concentration is 10%; (3) Fiber ratio: semi-chemical bamboo pulp 25-30%, natural chemical cattail pulp 75-85%; (54) Sizing agent: AKD (YZ-A03, solid content 18±1%), cationic rosin glue HZ-218 (solid content 35±1%); (5) Aluminum sulfate: solid, effective content 25±1%; (6) Reinforcement agent: XY-3155 (PAE, solid content 20.5±1%), P-V8 (nano-grade water-based narrow molecular weight distribution acrylic copolyester, solid content 40.0±1%); (7) Basis weight of sheet: 60g / m 2 .

[0035] (8) Method: Take the beaten pulp, prepare it according to the process requirements, add a certain amount of acrylic copolyester, wet strength agent, cationic rosin glue, and AKD respectively, mix them evenly with the pulp, and then use a sheet making machine to make sheets, press, dry, and bake. Finally, put the hand-made sheets in an oven for 15 minutes, and then test the wet strength and water absorption value.

[0036] 3 Experimental results and analysis Table 4 Wet strength and water absorption test results

[0037] From Table 4, we can see that: 3.1 When the AKD dosage is 27.5kg / t pulp, the Cobb value of the hand sheet is only 17.4g / m2 and 17.8g / m 2 ; less than 10g / m 2 Require.

[0038] 3.2 When the dosage of cationic rosin size is 14.5kg / t pulp, the Cobb value of the hand sheet is 9.5g / m 2 , can reach less than 10g / m 2 Require.

[0039] 3.3 When the dosage of reinforcing agent PAE reaches 60kg / t pulp, the wet strength is only 1.54kN / m; while when the dosage of acrylic copolyester P-V8 reaches 50kg / t pulp, the wet strength is 2.5kN / m, which exceeds the expected target.

[0040] 4 Conclusions and Recommendations In the laboratory, AKD was compared with cationic rosin glue. The sizing effect and cost of cationic rosin glue were better. When PAE wet strength agent was compared with acrylic copolyester P-V8, when the dosage of PAE wet strength agent reached 60kg / t pulp, the wet strength was only 1.54kN / m, and when the dosage of acrylic copolyester P-V8 reached 50kg / t pulp, the wet strength could reach 2.5kN / m. The wet strength of the hand-sheets could meet the requirements of seedling paper. However, from the perspective of product quality and performance, acrylic copolyester P-V8 had better cost performance. It is recommended to use cationic rosin glue and acrylic copolyester P-V8 enhancer for pilot production.

[0041] 3. Test report of renewable packaging materials The linear polymer material researched and produced by Shanghai Xianke Chemical Co., Ltd. (a research and development and production base for water-based materials) - nano-scale water-based narrow molecular weight distribution acrylic copolyester, when coated on the surface of paper, can have the effects of oil-proof, waterproof, heat-sealed, and renewable and recyclable.

[0042] The current focus is on testing the recyclability of paper that has been impregnated and coated with linear polymer materials produced by Shanghai Xianke Chemical Co., Ltd. (a water-based material research and development and production base).

[0043] Test method: Weigh a certain amount of coated paper, tear it into pieces, soak it in water for 10 minutes, completely dissociate the paper into single fibers in a fiber dissociator, make sheets of the disintegrated pulp in a paper copyer, dry it, and obtain recycled paper samples. Weigh the paper samples re-copied after dissociation. The ratio of the weight of the copied paper sample to the weight of the paper before shredding is used to obtain the recycling rate of paper fiber.

[0044] Table 5 Test results

[0045] As can be seen from Table 5, after impregnation and coating with the linear polymer material - nano-scale water-based narrow molecular weight distribution acrylic copolyester, the paper has a pulp recycling rate of more than 95%, and after impregnation and coating, the dried linear polymer material and pulp fiber are recycled and utilized at the same time.

[0046] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing zero-quantity VOCs degradable seedling paper, characterized in that: The steps are as follows: S1. Raw material selection: The fiber raw materials include 75-85% cattail and 15-25% reed by mass fraction; S2. The fiber raw materials described in S1 are sequentially subjected to the following processes: cattail + reed → vertical pot cooking → closed screening → pulp washing → oxygen delignification → pulp concentration → unbleached chemical straw pulp → pulp storage tower → pulp squeezer → high-concentration mill → latent force elimination tank → conical pulp refiner → pulp blending tank → pulping tank → sand removal → screening → forming on the net → pressing → pre-drying → surface sizing → post-drying → calendering, so as to obtain seedling paper that meets the requirements of ecological agricultural paper.

2. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 1, characterized in that: The caloric value of the pulp formed by cattail and reed in step S2 is 33±3, the pulp whiteness is 29±1%ISO, the fiber length is ≥1.69mm, the width is ≥13.2μm, the aspect ratio reaches 128, the breaking length is ≥10.25km, and the tear index is ≥12.3mN.m 2 / g, bulk ≥2.12cm3 / g, air permeability ≥5.6µm / (Pa.s).

3. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 1, characterized in that: In step S2, during vertical pot cooking, caustic soda is added into the pot, the amount of caustic soda used accounts for 15-25% of the total cooking liquid volume, the material-liquid ratio is 1:(4-6), the cooking temperature is 100-160° C., and the cooking time is 180-300 minutes.

4. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 1, characterized in that: In the high-concentration grinding process in step S2, the grinding current used is 2000-2200A, the grinding concentration is 25-30%, the beating degree of the pulp after grinding is about 25-28°SR, and the wet weight of the pulp is 13-18g.

5. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 1, characterized in that: In the step S2, the cone refiner uses a cone refiner with a pulping current of 150-200A, a low-concentration pulping concentration of 4.0-5.5%, a pulping degree of 28-35°SR, and a wet weight of the pulp of 10-15g.

6. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 1, characterized in that: In the step S2, chemical additives are added to the pulp mixing tank in the following order: barrier material P-V8→SPC508 cationic rosin glue→PAC→defoaming agent, wherein the amount of barrier material P-V8 per ton of paper is 10.0-15.0%, the amount of SPC508 cationic rosin glue per ton of paper is 0.5-1.0%, the amount of PAC per ton of paper is 1.0-1.5%, and the amount of defoaming agent per ton of paper is 0.05-0.2%.

7. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 6, characterized in that: The barrier material P-V8 in step S2 is a nano-scale water-based narrow molecular weight distribution acrylic copolyester.

8. The method for preparing zero-quantity VOCs degradable seedling paper according to any one of claims 1 to 7, characterized in that: The concentration of the slurry during the online forming in step S2 is 0.3-0.35%.

9. The method for preparing zero-quantitative VOCs degradable seedling paper according to any one of claims 1 to 7, characterized in that: In step S2, the wet paper sheets are further squeezed and dehydrated in the squeezing section, and then pre-dried to a dryness of 93-96%, and then the front surface of the paper is treated with a membrane transfer surface sizing machine; the surface sizing solution is prepared with cassava starch, nano antibacterial agent, and water repellent TF-535C.

10. The method for preparing zero-quantity VOCs degradable seedling paper according to claim 9, characterized in that: The sizing concentration of the surface sizing solution in step S2 is controlled at 8.0-10.0%, and the double-sided sizing amount is 2.0-4.0 g / m 2 ; The dosage of nano antibacterial agent in the surface sizing solution is controlled at 5.0-10.0 kg / ton of paper; The amount of water repellent TF-535C in the surface sizing solution is controlled at 5.0-10.0 kg / ton of paper.

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