A method for preparing a zero-VOCs degradable seedling paper

Abstract

This invention discloses a method for preparing zero-VOCs degradable seedling paper, comprising the following steps: S1, raw material selection: the fiber raw material includes 75-85% cattail and 15-25% reed by mass fraction; S2, the fiber raw material described in S1 is sequentially processed through the following steps: cattail + reed → vertical cooking → closed screening → pulp washing → oxygen delignification → pulp concentration → unbleached chemical straw pulp → storage tower → extruder → high-consistency mill → anti-fouling tank → conical refiner → pulp mixing tank → pulp forming tank → sand removal → screening → wire forming → pressing → pre-drying → surface sizing → post-drying → calendering, to obtain seedling paper that meets the requirements for ecological agricultural paper. The seedling paper obtained by this invention has good air permeability and high dry and wet strength, weather resistance to wind and rain erosion and trampling, can achieve natural microbial degradation in soil, and all raw materials are zero-VOCs degradable and sustainable, making it green, environmentally friendly and harmless to the soil.

Description

Technical Field

[0001] This invention relates to the field of seedling paper technology, and in particular to a method for preparing a zero-VOCs degradable seedling paper. Background Technology

[0002] With the advancement of agricultural production technology and the continuous development of ecological agriculture, the planting techniques for grain and cash crops have undergone fundamental changes. Agricultural mechanization is gradually replacing traditional manual labor, increasing production efficiency several times over. To support mechanized agricultural operations, factory-style seedling cultivation has been widely promoted and used. Traditionally, seedling containers are mainly made of plastic, non-woven fabric, and paper. Plastic containers and non-woven fabric seedling cultivation not only easily lead to root entrapment, slow root development after transplanting, and a long recovery period, affecting growth or yield, but also plastics are not easily degraded, and the microplastic particles after degradation can affect the survival of organisms and humans. Furthermore, the degradation process easily generates various VOCs, polluting the ecological environment. Paper seedling containers, made of paper, are breathable and permeable, facilitating air-root pruning and the formation of a well-developed capillary root system. They are also easily degraded after transplanting, allowing plants to develop roots quickly without restricting root growth. They are environmentally friendly and do not cause pollution. High-efficiency seedling paper plays a positive role in forming a good food ecological chain, supporting the greening of agricultural products, and meeting people's requirements for trace elements in green agricultural products, making it a good choice for seedling containers. However, the seedling process requires high wet strength, which ordinary paper cannot meet.

[0003] Therefore, how to provide a high-efficiency seedling base paper with high dry strength and suitable wet strength, good air permeability, water permeability, seedling lateral root penetration and soil holding ability, and complete degradation within 45-60 days, which meets the growth requirements of crops and is suitable for paper tube seedling transplanting cultivation is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing zero-VOCs degradable seedling paper. This method is applicable to seedling paper produced in a single step on a papermaking machine for seedling transplanting. The papermaking process is dry and energy-efficient, resulting in seedling paper with good air permeability and high dry and wet strength. It also exhibits weather resistance against wind, rain, and trampling, and can undergo natural microbial degradation in soil. Furthermore, all raw materials are zero-VOCs degradable and sustainably recyclable, making it green, environmentally friendly, and harmless to the soil.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for preparing a zero-VOCs degradable seedling paper includes the following steps:

[0007] S1. Raw material selection: The fiber raw materials include 75-85% cattail and 15-25% reed by mass fraction;

[0008] S2. The fiber raw materials described in S1 are processed sequentially through the following steps: cattail + reed → vertical cooking → closed screening → pulp washing → oxygen delignification → pulp concentration → unbleached chemical straw pulp → storage tower → extruder → high-consistency mill → de-saturation tank → conical refiner → pulp mixing tank → pulp forming tank → sand removal → screening → wire forming → pressing → pre-drying → surface sizing → post-drying → calendering, to obtain seedling paper that meets the requirements for ecological agricultural paper.

[0009] The above-mentioned seedling paper is prepared using high-quality raw and auxiliary materials and efficient chemical additives. It is made from a natural-colored cattail and reed mixed pulp prepared using a sulfur-free caustic soda method. The paper has water-soluble sulfate and chloride content ≤200mg / L, density ≥0.55g / cm³, longitudinal tensile strength index ≥75.0N·m / g, longitudinal wet tensile index ≥22N·m / g, and burst strength index ≥3.2 kPa. 2 The unbleached chemical straw pulp prepared by the caustic soda method has excellent physical properties, ranking among the best in grass fibers. The reasonable combination of fiber raw materials, fully leveraging the advantages of both types of fiber raw materials, makes it suitable for producing zero-VOCs, biodegradable, sustainable, and high-efficiency seedling paper, aligning with the characteristics of green ecological agriculture and environmentally friendly seedling cultivation. (Sizes: ≥10s, air permeability ≥6.0μm / (Pa·s), surface smoothness ≥20s).

[0010] Preferably, in step S2, the pulp formed from cattail and reed has a caloric value of 33±3, a pulp brightness of 29±1% ISO, a fiber length ≥1.69mm, a width ≥13.2μm, an aspect ratio of 128, a breaking length ≥10.25km, and a tear index ≥12.3mN. 2 / g, bulk thickness ≥2.12cm3 / g, air permeability ≥5.6µm / (Pa.s).

[0011] Preferably, in step S2, when the vertical pot is steamed, caustic soda is added to the pot, the amount of caustic soda accounts for 15-25% of the total volume of the steaming liquid, the material-to-liquid ratio is 1:(4-6), the steaming temperature is 100-160℃, and the steaming time is 180-300 minutes.

[0012] Preferably, the oxygen delignification process in step S2 ensures that the mixed pulp is free of toxic and harmful substances such as elemental chlorine and dioxins, and has the characteristics of high fiber bulk, fast moisture absorption and release, excellent air permeability, and green environmental protection.

[0013] Preferably, in the high-consistency grinding process of step S2, the grinding current is 2000-2200A, the grinding concentration is 25-30%, the freeness of the ground slurry is about 25-28°SR, and the wet weight of the slurry is 13-18g.

[0014] Preferably, in step S2, the conical refiner uses a conical mill with a refining current of 150–200 A, a low-consistency pulping concentration of 4.0–5.5%, a freeness of 28–35°SR, and a wet weight of 10–15 g.

[0015] Based on the application scenarios and environments of seedling paper, it not only needs high dry strength and high wet strength to ensure that the paper tubes do not break or collapse during seedling cultivation or transplanting at 35-60 days, but also needs a certain degree of air permeability to accommodate root development during crop seedling growth. Therefore, this invention employs a two-stage mixed pulping method of high-consistency refining followed by low-consistency beating on the selected fiber raw materials. Specifically, the mixed pulp, prepared according to the process ratio, is first subjected to high-consistency refining, and then to low-consistency beating via conical milling. Natural chemical cattail pulp, due to its long fibers and high strength, undergoes high-consistency refining and high-temperature, high-pressure kneading to achieve fiberization and flexibility. The subsequent conical milling process yields a beating pulp with a 28-35°SR, which helps ensure the uniformity of the finished paper. Therefore, the high-consistency refining + low-consistency beating method leverages the complementary advantages of high-consistency beating to achieve good pulping results, thereby improving the strength, air permeability, and thickness of the seedling paper.

[0016] Preferably, in step S2, chemical additives are added to the pulp mixing tank in the following order: barrier material P-V8 → SPC508 cationic rosin glue → PAC → defoamer. 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 SPC508 cationic rosin glue is a product manufactured by Arakawa Chemical Co., Ltd., and a solid content of 35±1% is added to the pulp mixing tank. The amount of PAC per ton of paper is 1.0-1.5%, and the amount of defoamer per ton of paper is 0.05-0.2%. The added chemical additives are added according to the weight ratio of the oven-dry pulp.

[0017] Mechanism of action of cationic rosin: Cationic rosin carries a certain charge density (Zeta potential of approximately +20mV), allowing it to remain on the surface of negatively charged fibers. Through the effective flocculation effect of aluminum sulfate, a hydrophobic layer is formed on the fiber surface, thus providing water resistance. The SPC508 cationic rosin used in this invention is a positively charged emulsion made from rosin and cationic polymeric surfactants. It has low dependence on aluminum sulfate, can adapt to a wide pH range, and can reduce paper brittleness.

[0018] Preferably, the barrier material P-V8 in step S2 is a nano-scale water-based narrow molecular weight distribution acrylic copolyester. The "nano-scale water-based narrow molecular weight distribution acrylic copolyester" selected in this 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 include nano-scale, narrow bandwidth, and normal molecular weight distribution. The linearized main structure ensures the stability of the material and gives it excellent microbial degradation performance. It also has environmentally friendly and harmless 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 nanoscale water-based narrow molecular weight distribution acrylic copolyester: Utilizing the homopolymer structure of functional groups within the molecule and its nanoscale properties, the linear functional copolyester exhibits monodispersity and co-dispersibility, enhancing adhesion to the fiber surface through chemical functionality and physical means. This results in self-crosslinking between acrylic copolyesters and co-crosslinking between the acrylic copolyester and the fiber at the fiber interface. Self-crosslinking creates an interlaced chain structure around the fiber, limiting fiber swelling and increasing wet strength to some extent. Co-crosslinking involves the acrylic copolyester forming new bonds with some hydroxyl groups on adjacent fibers. The formation of a crosslinked network of water-resistant covalent bonds is particularly crucial for improving the paper's water resistance and strength. The resulting seedling paper is sustainable, recyclable, and biodegradable.

[0019] Adding PAC with a solid content of 12.5±1% before the slurry pump mainly serves to adjust the pH and PCD of the system, react with cationic rosin to form a water-resistant layer on the fiber surface, and improve the zeta potential of the slurry system.

[0020] Preferably, the concentration of the slurry during web forming in step S2 is 0.3-0.35%.

[0021] Preferably, in step S2, after the wet paper sheet is further pressed and dehydrated in the press section, it undergoes pre-drying treatment to a dryness of 93-96%. Then, a film transfer surface sizing machine is used to treat the front surface of the paper. After surface sizing, the paper sheet is post-dried and then undergoes soft calendering for paper surface finishing treatment. The paper is then wound up and finally rewound and slit into seedling paper rolls of the specifications required by the customer. The surface sizing solution is formulated with cassava starch, nano antibacterial agent, and water-resistant agent TF-535C, and has water-resistant, antibacterial, and reinforcing effects. The metering rod model is 1#, and the metering rod pressure is 100 kPa. The paper sheet tension before the sizing machine is 220 N / m. 2 The paper tension after sizing is 200 N / m. 2 Water-resistant agent TF-535C is a semi-transparent liquid, cationic, with a solid content of 25±1% and a pH of 4 to 7. It has the advantages of being water-resistant and oil-resistant, producing paper with excellent water resistance, requiring only a small amount, not affecting air permeability, and improving paper strength.

[0022] Preferably, in step S2, the concentration of the surface sizing solution is controlled at 8.0–10.0%, and the double-sided sizing amount is 2.0–4.0 g / m². 2 The dosage of nano-antibacterial agent in the surface sizing solution is controlled at 5.0–10.0 kg / ton of paper; the dosage of water-resistant agent TF-535C in the surface sizing solution is controlled at 5.0–10.0 kg / ton of paper. The nano-antibacterial agent is a novel, multifunctional, environmentally friendly inorganic antibacterial material with nano-active oxides as the main active ingredient. The product has high activity and inhibits multiple bacterial species, including Escherichia coli AS 1.90, Staphylococcus aureus AS 1.89, and Candida albicans ATCC 10231. It has unique advantages in antibacterial and antifungal properties. The addition of nano-antibacterial agent enables the seedling paper to effectively and continuously inhibit various common bacteria, fungi, molds, and viruses, thus purifying the soil environment.

[0023] The present invention has the following advantages over the prior art:

[0024] (1) The papermaking raw materials of the present invention are non-wood plant fibers, and the chemical additives are preferably nano-level pure water linear functional resin materials, long-lasting deodorizing antibacterial self-cleaning nano antibacterial agents, high-efficiency water-resistant agents, etc. These products are green and environmentally friendly products, do not contain any halogens, have zero VOCs, and significantly reduce energy consumption and carbon emissions.

[0025] (2) The present invention uses pure plant fiber as the main material, preferably non-wood fiber medium long fiber cattail and reed to prepare paper pulp by caustic soda method. The fiber raw material is artificially planted, has strong renewability, is easy to obtain, saves limited wood resources, and protects the ecological environment.

[0026] (3) The bio-nontoxic 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 enhance water resistance, mildew prevention and antibacterial effect, which has a high efficiency in enhancing water resistance and antibacterial effect, zero VOCs, and does not use urea-formaldehyde resin and melamine-formaldehyde resin that have a negative impact on fiber degradation.

[0027] (4) The preparation method of the present invention adopts the gas permeability control method. The application of high-concentration pulping technology reduces fiber cutting and reduces the influence of fine components on air permeability. At the same time, the nanoscale water-based narrow molecular weight distribution acrylic copolyester has nanoscale, narrow bandwidth and normal molecular weight distribution characteristics, and the intermolecular van der Waals forces are enhanced. Therefore, it has the characteristics of good adsorption performance, large inter-fiber pores and fast drying speed.

[0028] (5) The preparation method of the present invention adopts a biodegradable composition design. The calamus pulp in the non-wood fiber has the best fiber quality among grass plants. It uses nano-level water-based narrow molecular weight distribution acrylic copolyester material to enhance water resistance. The paper fiber carries the copolyester fiber and uses entanglement to form a network structure. It does not require separation and is re-pulped by physical method (process water is recycled). Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] Example 1: 60g / m 2 Zero-VOCs biodegradable sustainable recyclable high-efficiency seedling paper

[0031] A natural chemical pulp with a carboxylic acid price of 31, prepared from 75% cattail and 25% reed using the caustic soda method, is pumped to the pulp storage tower in the pulping section of the paper mill. It is then pumped to a two-roll press to achieve a high-concentration pulp of approximately 29%. This high-concentration pulp is then crushed by a screw press and fed into a high-consistency refiner (2050A). The resulting pulp has a beat ratio of 28ºSR and a wet weight of 15g. At this stage, the pulp is not suitable for direct papermaking and requires 35 minutes of dilution and de-foaming with 45°C warm water to achieve a low-concentration pulp of 4.5%. This pulp is then pumped to two conical mills connected in series for refining and refining. The refining currents of the two conical mills are 160A and 180A respectively, achieving a beat ratio of 32ºSR and a wet weight of 12g. In the rear tank, 85 kg / ton of P-V8 (nano-grade water-based narrow molecular weight acrylic copolyester) and 15 kg / ton of PAC are added sequentially. The pulp is thoroughly mixed and stirred to a concentration of 0.3%. It is then pumped to a sand remover to remove impurities. The sand-removed pulp is sent to a pressure screen, where cationic rosin is added at 8.0 kg / ton of pulp at the pressure screen inlet. The mixed pulp is dispersed through the pressure screen and then fed into the pre-wire box for homogenization before being dewatered and formed. After passing through the first, second, and third press zones, the wet paper web is pre-dried to 96% dryness before entering the surface sizing machine. Surface sizing is performed using a film transfer method. The surface sizing solution is formulated with cassava starch, Asahikawa nano antibacterial agent, and water-resistant agent TF-535C. The sizing concentration is controlled at 10%, and the single-sided sizing amount is 2.0 g / m². 2The dosage of nano-antibacterial agent is controlled at 8.0 kg / t of paper, and the dosage of water-resistant agent is controlled at 8.0 kg / t of paper. After surface sizing, the wet paper sheets are dried in a post-drying cylinder and then subjected to a soft calendering process for surface finishing. After soft calendering, the paper sheets with a dryness of 91.5% are rolled into master rolls, then rewound and slit to obtain a basis weight of 60 g / m³. 2 High-efficiency seedling paper.

[0032] Example 2: 58g / m 2 Zero-VOCs biodegradable sustainable recyclable high-efficiency seedling paper

[0033] A natural chemical straw pulp with a carboxylic acid price of 33, prepared from 85% cattail and 15% reed using the caustic soda method, is pumped to the pulp storage tower in the pulping section of the paper mill. It is then pumped to a two-roll press to achieve a high-concentration pulp of approximately 29%. This high-concentration pulp is then crushed by a screw press and fed into a high-consistency refiner (2050A). The resulting pulp has a beating degree of 29ºSR and a wet weight of 15.0 g / L. At this stage, the pulp is not suitable for direct papermaking and requires 35 minutes of dilution and de-foaming with 45°C warm water to a low-consistency pulp of 5.0%. This pulp is then pumped to a conical mill for refining and refining in series. The refining currents of the two conical mills are 170A and 200A respectively, with a freeness of 35ºSR and a wet weight of 10.5 g / L. After beating, the pulp is further refined in the beating tank. In the first step, 90.0 kg / ton of P-V8 (nano-grade water-based narrow molecular weight acrylic copolyester) and 12.0 kg / ton of PAC are added sequentially. The pulp is thoroughly mixed and stirred to a concentration of 0.32%. The pulp is then pumped to a sand remover to remove impurities. The sand-removed pulp is sent to a pressure screen, where cationic rosin is added at 8.0 kg / ton of pulp at the pressure screen inlet. After the mixed pulp is dispersed through the pressure screen, it enters the pre-wire box for homogenization and then is dewatered and formed on the wire. After passing through the first, second, and third press zones, the wet paper web is pre-dried to a dryness of 95.0% and then enters the surface sizing machine. Surface sizing is performed using a film transfer method. The surface sizing solution is formulated with cassava starch, Asahikawa nano antibacterial agent, and water-resistant agent TF-535C. The sizing concentration is controlled at 10%, and the sizing amount on one side is 2.0 g / m². 2 The dosage of nano-antibacterial agent is controlled at 10.0 kg / t of paper, and the dosage of water-resistant agent is controlled at 8.0 kg / t of paper. After surface sizing, the wet paper sheets are dried in a post-drying cylinder and then subjected to a soft calendering process for surface finishing. The paper sheets with a dryness of 91.70% after soft calendering are rolled into master rolls, then rewound and slit to obtain a basis weight of 58.0 g / m³. 2 High-efficiency seedling paper.

[0034] The performance indicators of the seedling paper in Examples 1-2 above are shown in Table 1 below:

[0035] Table 1. Indicators of seedling paper in Examples 1-2

[0036]

[0037] As shown in Table 1 above, the seedling tubes made from the zero-VOCs degradable, sustainable, and efficient seedling paper produced by this invention have significantly faster soil filling and higher efficiency compared to seedlings grown in plastic nutrient pots. Observations by seedling workers during the seedling stage show that the paper bags maintain their shape well after 30 days of cultivation and do not crumble when transplanting. During transplanting, seedlings grown in paper bags can be directly planted, resulting in a shorter recovery period, less damage to the plant roots, and improved plant growth. The resulting crops exhibit better growth than those grown in plastic nutrient pots, meeting the requirements for pollution-free economic crop cultivation in large-scale ecological agriculture.

[0038] The following are several reports related to the preparation method of this embodiment:

[0039] I. Experimental Study Report on the Formation of Kraft Paper from Unbleached Reed Pulp

[0040] 1. Experimental Design

[0041] 1.1 The unbleached chemical straw pulp + reed pulp is supplied by MCC Galaxy Paper, with a freeness of 28.0SR; the semi-chemical bamboo and wood pulp has a freeness of 14.5SR.

[0042] 1.2 Pulp ratio: The unbleached chemical grass pulp (cattail and reed mixed and boiled) and semi-chemical bamboo and wood pulp are respectively pulped using PFI disc mills. After the grass pulp is lightly pulped, it is then mixed with semi-chemical bamboo and wood pulp with a freeness of 30-35SR.

[0043] 1.3 According to the required proportions, 10%, 20%, 30%, and 40% semi-chemical bamboo pulp were added to the straw pulp, respectively. After preparing the pulp, it was sheeted, pressed, and dried. Finally, the sheeted material was subjected to constant temperature and humidity equilibrium treatment to test relevant performance indicators.

[0044] 2. Experimental Results

[0045] Table 2 Strength performance of the transected film

[0046]

[0047] Table 3. Whiteness and Hue of the Translated Films

[0048]

[0049] As can be seen from Tables 2 and 3, semi-chemical bamboo pulp has more dust in its fiber bundles and lower strength, making it unsuitable for producing seedling paper with high strength requirements. Compared with semi-chemical bamboo pulp, unbleached cattail pulp has higher whiteness, strength, and bulk. As the proportion of unbleached cattail pulp increases, the sheet strength and whiteness increase significantly. Pilot production is recommended.

[0050] II. Experimental Report on the Effects of Different Chemical Additives on the Water Resistance of Seedling Paper

[0051] In order to develop and produce high-efficiency ecological seedling paper that can meet the market shortage, product R&D personnel conducted water-resistant and enhanced papermaking experiments.

[0052] 1. Experimental Objective

[0053] The main objective of the experiment was to determine the process for improving the wet strength and water resistance of paper; specifically, wet tensile strength ≥ 1.5 kN / m and water absorption ≤ 10.0 g / m². 2 .

[0054] 2 Experimental Design

[0055] (1) Pulp: caustic soda chemical cattail pulp, semi-chemical bamboo pulp;

[0056] (2) Freezing degree: 28-32°SR for semi-chemical bamboo pulp and 30-33°SR for chemical straw pulp; use PFI disc mill to beat to 3500r and 5000r respectively, with a pulping concentration of 10%;

[0057] (3) Fiber ratio: 25-30% semi-chemical bamboo pulp, 75-85% natural chemical cattail pulp;

[0058] (54) Sizing agents: AKD (YZ-A03, solid content 18±1%), cationic rosin gum HZ-218 (solid content 35±1%).

[0059] (5) Aluminum sulfate: solid, effective content 25±1%;

[0060] (6) Reinforcing agents: XY-3155 (PAE, solid content 20.5±1%), P-V8 (nanoscale waterborne narrow molecular weight distribution acrylic copolyester, solid content 40.0±1%).

[0061] (7) Quantitative amount of paper slices: 60g / m 2 .

[0062] (8) Method: Take the prepared slurry, prepare it according to the process requirements, add a certain amount of acrylic copolyester, wet strength agent, cationic rosin gum and AKD, mix them evenly with the slurry, then use a sheeter to sheet, press, dry and bake, and finally, after the sheet is hand-made, put it in the oven to bake for 15 minutes, and test the wet strength and water absorption value.

[0063] 3. Experimental Results and Analysis

[0064] Table 4. Results of wet strength and water absorption test

[0065]

[0066] As shown in Table 4:

[0067] 3.1 When the AKD dosage is 27.5 kg / t pulp, the Cobb value of hand-made sheets is only 17.4 g / m² and 17.8 g / m². 2 ; does not reach 10g / m 2 Require.

[0068] 3.2 When the cationic rosin gum dosage is 14.5 kg / t pulp, the Cobb value of the hand-made sheets is 9.5 g / m³. 2 It can reach less than 10g / m 2 Require.

[0069] 3.3 When the dosage of reinforcing agent PAE reaches 60 kg / t of pulp, the wet strength is only 1.54 kN / m; while when the dosage of acrylic copolyester P-V8 reaches 50 kg / t of pulp, the wet strength is 2.5 kN / m, exceeding the expected target.

[0070] 4. Conclusions and Recommendations

[0071] In a laboratory comparison of sizing with AKD and cationic rosin, cationic rosin showed superior sizing effect and cost. A comparison of PAE wet-strength agent and acrylic copolyester P-V8 showed that when PAE wet-strength agent dosage reached 60 kg / t pulp, the wet strength was only 1.54 kN / m, while when acrylic copolyester P-V8 dosage reached 50 kg / t pulp, the wet strength reached 2.5 kN / m. The wet strength of both hand-made sheets met the requirements for seedling paper; however, considering product quality and performance, acrylic copolyester P-V8 offered better cost-effectiveness. It is recommended that cationic rosin and acrylic copolyester P-V8 reinforcing agents be used for pilot production.

[0072] III. Test Report on Renewable Packaging Materials

[0073] Shanghai Xianke Chemical Co., Ltd. (a water-based materials R&D and production base) researches and produces a linear polymer material—nanoscale water-based narrow molecular weight distribution acrylic copolyester. When coated onto the surface of paper, it can achieve the effects of oil and water resistance, heat sealing, and recyclability.

[0074] The current research focuses on the recyclability of paper coated with linear polymer materials from Shanghai Xianke Chemical Co., Ltd. (a water-based materials R&D and production base).

[0075] Test method: A certain amount of coated paper was weighed, torn into pieces, and soaked in water for 10 minutes. The paper pieces were then completely separated into individual fibers in a fiber dissociator. The dissociated pulp was then formed into sheets in a paper forming machine, dried, and recycled paper samples were obtained. The re-formed paper samples were weighed. The ratio of the weight of the re-formed paper samples to the weight of the paper before dissociation was used to obtain the paper fiber recycling rate.

[0076] Table 5 Test Results

[0077]

[0078] As can be seen from Table 5, the paper after impregnation and coating with linear polymer material - nanoscale water-based narrow molecular weight distribution acrylic copolyester has a pulp recycling rate of over 95%, and the dried linear polymer material and pulp fiber are simultaneously recycled after impregnation and coating.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a zero-VOCs degradable seedling paper, characterized in that, The following steps are included: 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 processed sequentially through the following steps: cattail + reed → vertical cooking → closed screening → pulp washing → oxygen delignification → pulp concentration → unbleached chemical straw pulp → pulp storage tower → extruder → high-consistency mill → de-saturation tank → conical refiner → pulp mixing tank → pulp forming tank → sand removal → screening → wire forming → pressing → pre-drying → surface sizing → post-drying → calendering, to obtain seedling paper that meets the requirements for ecological agricultural paper. The pulp formed from cattail and reed has a caloric value of 33±3, a pulp brightness of 29±1% ISO, a fiber length ≥1.69mm, a width ≥13.2μm, an aspect ratio of 128, a breaking length ≥10.25km, and a tear index ≥12.3mN·m. 2 / g, bulk thickness ≥2.12cm 3 / g, air permeability ≥5.6µm / (Pa.s); When cooking in a vertical pot, caustic soda is added to the pot. The amount of caustic soda is 15-25% of the total volume of the cooking liquid. The material-to-liquid ratio is 1:(4-6). The cooking temperature is 100-160℃ and the cooking time is 180-300 minutes. In the high-consistency grinding process, the pulp concentration is 25-30%, and the freeness of the pulp after grinding is 25-28°SR. The low-consistency pulping concentration of the cone refiner is 4.0–5.5%, and the freeness is 28–35°SR. Chemical additives are added to the mixing tank in the following order: barrier material P-V8 → SPC508 cationic rosin glue → PAC → defoamer. The barrier material P-V8 is a nano-sized water-based narrow molecular weight distribution acrylic copolyester. The surface sizing solution is formulated with cassava starch, nano antibacterial agent, and water-resistant agent TF-535C.

2. The method for preparing zero-VOCs degradable seedling paper according to claim 1, characterized in that, In the high-consistency grinding process of step S2, the grinding current used is 2000-2200A, and the wet weight of the slurry is 13-18g.

3. The method for preparing zero-VOCs degradable seedling paper according to claim 1, characterized in that, In step S2, the cone mill used in the conical refiner has a current of 150-200A and a wet weight of 10-15g for the pulp.

4. The method for preparing zero-VOCs degradable seedling paper according to claim 1, characterized in that, In step S2, the amount of barrier material P-V8 per ton of paper is 10.0-15.0%, the amount of SPC508 cationic rosin adhesive 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 defoamer per ton of paper is 0.05-0.2%.

5. The method for preparing zero-VOCs degradable seedling paper according to any one of claims 1-4, characterized in that, In step S2, the concentration of the slurry during the web forming process is 0.3-0.35%.

6. The method for preparing zero-VOCs degradable seedling paper according to any one of claims 1-4, characterized in that, In step S2, after the wet paper is further pressed and dehydrated in the press section, it undergoes a pre-drying treatment to a dryness of 93-96%, and then the front surface of the paper is treated using a film transfer surface sizing machine.

7. The method for preparing zero-VOCs degradable seedling paper according to claim 1, characterized in that, In step S2, the concentration of the surface sizing solution is controlled at 8.0–10.0%, and the amount of sizing applied to both sides is 2.0–4.0 g / m³. 2 The dosage of nano-antibacterial agent in the surface sizing solution is controlled at 5.0–10.0 kg / ton of paper. The dosage of water-resistant agent TF-535C in the surface sizing solution is controlled at 5.0-10.0 kg / ton of paper.

Images