A method for preparing a high-strength antibacterial ecological paper

Abstract

This invention relates to the field of papermaking technology, specifically disclosing a method for preparing high-strength antibacterial eco-paper. The method comprises bleached hardwood pulp, bleached softwood pulp, biodegradable polyester fiber powder, inorganic silver ion antibacterial agent, and water. The steps include: S1 preparing an intermediate by reacting 2,6-diaminopimelic acid with a silane coupling agent HK-560, then esterifying and polycondensing it with prepolymer PLA and prepolymer PBAT, followed by melt spinning to obtain biodegradable polyester fiber; S2 soaking and mixing bleached hardwood pulp and bleached softwood pulp to obtain mixed pulp; S3 subjecting the mixed pulp to descaling treatment; S4 obtaining a finely ground mixed pulp via a disc mill; S5 adding biodegradable polyester fiber powder, followed by paper forming, pressing, dewatering, and two-stage drying to obtain eco-paper. This invention introduces chemically cross-linkable biodegradable polyester fiber powder into the paper, forming a composite cross-linked structure of hydrogen bonds and covalent bonds. This improves the mechanical properties and structural stability of the paper while also providing biodegradability, combining practicality and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, specifically to a method for preparing high-strength antibacterial eco-paper. Background Technology

[0002] In the preparation of eco-paper, during the processing of eco-paper, in order to increase its structural strength, the fibers are reinforced. A common method is to add synthetic fibers to the pulp to improve the mechanical properties of the paper. However, the bonding force between unmodified synthetic fibers and wood pulp fibers is weak, and they are only connected by hydrogen bonds. After the paper is made, it is easy to have problems such as insufficient strength and uneven fiber dispersion, making it difficult to meet the requirements of environmental degradation and mechanical properties at the same time.

[0003] To address the aforementioned issues, an environmentally friendly eco-paper and its preparation method are disclosed in the prior art (CN201710542601.9). The pulp components of this eco-paper include bleached softwood pulp, chemimechanical pulp, poplar wood flour, and polyester fiber. The chemimechanical pulp and poplar wood flour are treated with hydrogen peroxide and then subjected to high-frequency descaling; the bleached softwood pulp is separately pulped; then the two pulps are mixed, and titanium dioxide sludge is added as a filler in the mixing tank; finally, polyester fiber is uniformly added in the pre-papering tank. The addition of modified polyester fiber (containing a large number of hydrophilic carboxyl and hydroxyl groups) increases the interweaving force between fibers, improves fiber bonding strength, thereby enhancing the tensile strength of the paper and improving the surface smoothness of the paper.

[0004] The aforementioned existing technologies improve paper strength to some extent through polyester fibers, but the polyester fibers used are not modified and are mostly bonded to wood pulp fibers by hydrogen bonds, which means there is still room for improvement in paper strength. In addition, ordinary polyester fibers have poor degradation performance and cannot meet the requirements for environmentally friendly and degradable use of eco-paper throughout its entire life cycle. Summary of the Invention

[0005] To address the technical deficiencies in the background art, this invention proposes a method for preparing high-strength antibacterial eco-paper, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows: A high-strength antibacterial eco-paper, comprising the following components by weight percentage: 60-65% bleached hardwood pulp; 20-28% bleached softwood pulp; Biodegradable polyester fiber powder 5.0-8.5%; And an inorganic silver ion antibacterial agent comprising 0.1-1.0% of the total dry fiber mass; The remainder is moisture; The biodegradable polyester fiber powder is obtained by pulverizing biodegradable polyester fibers. The biodegradable polyester fibers are copolymerized from intermediates, prepolymer PLA and prepolymer PBAT. The intermediates are prepared by reacting 2,6-diaminopimelic acid with silane coupling agent HK-560.

[0006] As a further technical solution of the present invention, the biodegradable polyester fiber powder has a diameter of 5-10 μm and a length of 0.2-0.4 mm; A method for preparing high-strength antibacterial eco-paper includes the following steps: The amino group of S1,2,6-diaminopimelic acid undergoes ring-opening with the epoxy group of HK-560 under anhydrous conditions to obtain an intermediate. The intermediate is mixed with prepolymer PLA and prepolymer PBAT for esterification polycondensation reaction to obtain polyester. The polyester is dried and melt-spun to obtain biodegradable polyester fiber. S2. After soaking bleached hardwood pulp and bleached softwood pulp separately, they are mixed and then mixed at an oven-dry mass ratio of (7-10):(3-5) to obtain mixed pulp. S3. Adjust the concentration of the mixed pulp obtained in step S2, and decompose it in a decomposition machine to obtain decomposed pulp; S4. The slurry obtained in step S3 is ground using a disc mill until the set beating degree is reached to obtain a finely ground mixed slurry. S5. Crush the biodegradable polyester fiber and add it to the finely ground mixed pulp obtained in step S4 at a ratio of 5-10% of the total dry pulp mass. At the same time, add inorganic silver ion antibacterial agent at a ratio of 0.1-1.0% of the total dry pulp mass. After stirring evenly, adjust the pulp concentration, form it on a paper machine, and after pressing and dewatering, perform two-stage drying to obtain eco-paper.

[0007] As a further technical solution of the present invention, in step S1, the preparation of the biodegradable polyester fiber includes the following steps: (1) Preparation of intermediate: 2,6-diaminopimelic acid and HK-560 were mixed at a molar ratio of 1:2, DMF solvent was added, and the mixture was stirred at 85-95℃ for 5-7 h under protective gas. The intermediate was then obtained after post-treatment. (2) Preparation of prepolymer PLA: After drying lactic acid, a catalyst is added, and the temperature is raised to 135-145℃ under a protective atmosphere. The prepolymer reaction is carried out for 3-5 hours to obtain prepolymer PLA. (3) Preparation of prepolymer PBAT: Terephthalic acid, adipic acid and 1,4-butanediol are mixed in a molar ratio of 1:1:(2.1-2.5), a catalyst is added, and the mixture is heated to 175-185℃ under protective gas for 2-4 hours. Then, the mixture undergoes polycondensation under high temperature and high vacuum conditions to obtain prepolymer PBAT. (4) Synthesis of copolyester: The intermediate obtained in step (1) is mixed with prepolymer PLA and prepolymer PBAT at a mass ratio of (1-2):8:4, and esterification polycondensation reaction is carried out in a polycondensation reactor under high temperature and high vacuum conditions to obtain polyester. (5) Melt spinning: After drying the above polyester, melt spinning and drawing are performed to obtain biodegradable polyester fibers.

[0008] As a further technical solution of the present invention, in step (4), the temperature of the esterification polycondensation reaction is 215-225℃, the vacuum degree is 25-35Pa, and the reaction time is 5-7h; in step (5), the spinning temperature of the melt spinning is 210-225℃, the winding speed is 1150-1250m / min, and the draw ratio is 3-5 times.

[0009] As a further technical solution of the present invention, in step S2, the soaking is to soak bleached hardwood pulp and bleached softwood pulp in water at 25-35℃ for 5-7 hours respectively; in step S3, the concentration of the mixed pulp in the defrosting treatment is 3-5%, the defrosting speed is 4000-5000 rpm, and the defrosting time is 8-12 minutes.

[0010] As a further technical solution of the present invention, in step S4, the pulp concentration of the pulping treatment is 3-5%, the pulping gap is 0.2-0.4 mm, and the freeness is controlled at 38-42°SR; in step S5, the pulp concentration of the papermaking process is 0.8-1.2%, and the paper basis weight is 50-60 g / m³. 2 .

[0011] As a further technical solution of the present invention, in step S5, the two-stage drying is specifically as follows: the first-stage drying temperature is 115-125℃, and the paper is dried until the moisture content is 24-26%; the second-stage drying temperature is 55-65℃, and the paper is dried until the final moisture content is 4.5-5.5%.

[0012] The beneficial effects of this invention are as follows: This invention utilizes an intermediate obtained by reacting 2,6-diaminopimelic acid with the silane coupling agent HK-560, which is then esterified and copolymerized with prepolymer PLA and prepolymer PBAT to prepare biodegradable copolyester fibers. These fibers are then added to pulp formulated from bleached hardwood pulp and bleached softwood pulp for papermaking. The hydrolyzable silanoxy groups on the polyester fibers hydrolyze to form silanol groups, which then condense with the hydroxyl groups in the pulp fibers, forming a complex cross-linked structure of hydrogen bonds and chemical bonds within the paper. This effectively improves the mechanical strength of the paper. Furthermore, the polyester component used is a biodegradable system, and combined with the pulp base material, the resulting eco-paper can naturally degrade after use, causing no environmental pollution. The addition of inorganic silver ion antibacterial agents gives the eco-paper excellent antibacterial properties, good paper forming uniformity, stable physical properties, and a combination of high strength and environmentally friendly biodegradability. Detailed Implementation

[0013] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to those described below, and the present invention relates to necessary knowledge in this technical field. It should be considered as well-known technology in this technical field, and is known and mastered by those skilled in the art. Experimental methods in the following examples that do not specify specific conditions are generally performed under conventional conditions in the art or according to the manufacturer's recommendations. Unless otherwise specified, the raw materials and reagents used are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0014] A high-strength antibacterial eco-paper, comprising the following components by weight percentage: 60-65% bleached hardwood pulp; 20-28% bleached softwood pulp; Biodegradable polyester fiber powder 5.0-8.5%; And an inorganic silver ion antibacterial agent comprising 0.1-1.0% of the total dry fiber mass; The remainder is moisture; The biodegradable polyester fiber powder is obtained by pulverizing biodegradable polyester fibers. The biodegradable polyester fibers are copolymerized from intermediates, prepolymer PLA and prepolymer PBAT. The intermediates are prepared by reacting 2,6-diaminopimelic acid with silane coupling agent HK-560.

[0015] This invention utilizes bleached hardwood pulp, bleached softwood pulp, and self-made biodegradable polyester fiber powder in a compound molding process. This improves the overall structural stability and degradation performance while ensuring the basic usability of the paper. The biodegradable polyester fiber powder is obtained by copolymerizing an intermediate with prepolymer PLA and prepolymer PBAT, playing a crucial role in crosslinking and reinforcement within the system. The intermediate is generated by reacting 2,6-diaminopimelic acid with the silane coupling agent HK-560. Its molecular structure contains functional groups that can participate in copolymerization, as well as hydrolyzable siloxane groups. The hydrolyzable siloxane groups enable good bonding between the copolyester fiber and the plant fiber.

[0016] When biodegradable polyester fiber powder is added to pulp, the hydrolyzable silanoxy groups on the fiber surface are converted into silanol groups, which undergo a condensation reaction with the hydroxyl groups on the plant fibers. This transforms the paper's internal structure from simple hydrogen bonding to a composite cross-linked structure with both hydrogen bonds and covalent bonds, thereby improving the paper's tensile strength, burst strength, and other mechanical properties, and reducing problems such as dusting and breakage during use.

[0017] The biodegradable polyester fibers used are mainly PLA and PBAT polymers, which can be gradually decomposed by microorganisms in the natural environment. Combined with the biodegradable characteristics of plant fibers themselves, the resulting eco-paper is biodegradable after disposal and will not produce long-term residual plastic pollutants. Through the combination of components, the mechanical properties of the paper are improved, and the product is guaranteed to meet environmental protection requirements. Overall, it is both practical and eco-friendly.

[0018] In this invention, the added inorganic silver ion antibacterial agent enables the eco-paper to achieve excellent antibacterial properties. The inorganic silver ion antibacterial agent possesses excellent thermal stability, is compatible with two-stage drying processes in papermaking, exhibits good compatibility with pulp fibers and biodegradable polyester fiber powder, does not interfere with fiber cross-linking reactions, and can broadly inhibit common pathogenic bacteria. It also has good long-lasting antibacterial effects, meeting the hygiene and safety requirements of various scenarios.

[0019] Furthermore, the eco-paper of this invention has a wide range of applications and can be used in conventional fields such as packaging paper and cultural paper. In particular, it can be used as a base paper for release paper. Its good mechanical properties can withstand the processing of release agent coating, die cutting and other processes, and its good biodegradability can improve the environmental performance of release paper, making it suitable for release paper application scenarios with high environmental protection requirements, such as green packaging.

[0020] In one preferred embodiment of the present invention, the biodegradable polyester fiber powder has a diameter of 5-10 μm and a length of 0.2-0.4 mm; Specifically, by controlling the diameter of the biodegradable polyester fiber powder to 5-10μm and the length to 0.2-0.4mm, it can be evenly dispersed in the finely ground mixed pulp. This allows the silanol groups on the surface of the fiber powder to fully contact and undergo a condensation reaction with the hydroxyl groups of the pulp fibers, effectively enhancing the internal cross-linking strength of the paper and ensuring stable mechanical properties. At the same time, it avoids defects on the paper surface and loose fiber bonding due to excessively large particles, or agglomeration due to excessively small particles, which would affect the cross-linking effect.

[0021] A method for preparing high-strength antibacterial eco-paper includes the following steps: The amino group of S1,2,6-diaminopimelic acid undergoes ring-opening with the epoxy group of HK-560 under anhydrous conditions to obtain an intermediate. The intermediate is mixed with prepolymer PLA and prepolymer PBAT for esterification polycondensation reaction to obtain polyester. The polyester is dried and melt-spun to obtain biodegradable polyester fiber. S2. After soaking bleached hardwood pulp and bleached softwood pulp separately, they are mixed and then mixed at an oven-dry mass ratio of (7-10):(3-5) to obtain mixed pulp. S3. Adjust the concentration of the mixed pulp obtained in step S2, and decompose it in a decomposition machine to obtain decomposed pulp; S4. The slurry obtained in step S3 is ground using a disc mill until the set beating degree is reached to obtain a finely ground mixed slurry. S5. Crush the biodegradable polyester fiber and add it to the finely ground mixed pulp obtained in step S4 at a ratio of 5-10% of the total dry pulp mass. At the same time, add inorganic silver ion antibacterial agent at a ratio of 0.1-1.0% of the total dry pulp mass. After stirring evenly, adjust the pulp concentration, form it on a paper machine, and after pressing and dewatering, perform two-stage drying to obtain eco-paper.

[0022] In the preparation method of this invention, the biodegradable polyester fiber prepared in step S1 undergoes copolymerization with intermediates and prepolymer PLA and PBAT, followed by melt spinning. This results in a uniform fiber structure with hydrolyzable silane groups on the surface, allowing for crosslinking with pulp fibers. Step S2 involves soaking and mixing bleached hardwood pulp and softwood pulp in a specific ratio to ensure thorough wetting of the two pulp fibers, guaranteeing the uniformity of the mixed pulp and avoiding performance limitations associated with single pulp types. This provides high-quality raw materials for subsequent refining and papermaking. Step S3, the debonding treatment, breaks down the pulp fiber bundles, resulting in more uniform fiber dispersion. Step S4, the refining treatment, controls a specific freeness, refining the fibers, increasing their specific surface area, enhancing inter-fiber bonding, and reducing delamination and breakage issues after paper forming. Step S5 involves adding biodegradable polyester fiber powder and inorganic silver ion antibacterial agent to the refined pulp in a certain proportion. After papermaking, the pulp undergoes two-stage drying treatment. This ensures that the fiber powder is evenly dispersed and fully condenses with the pulp fibers to form a stable composite cross-linked structure. Gradient drying also prevents the paper from warping or cracking due to excessively rapid drying. Ultimately, this improves the tensile strength, bursting strength, stiffness, and antibacterial properties of the paper, while ensuring good paper forming quality and stable performance.

[0023] As one of the preferred embodiments of the present invention, in step S1, the preparation of the biodegradable polyester fiber includes the following steps: (1) Preparation of intermediate: 2,6-diaminopimelic acid and HK-560 were mixed at a molar ratio of 1:2, DMF solvent was added, and the mixture was stirred at 85-95℃ for 5-7 h under protective gas. The intermediate was then obtained after post-treatment. (2) Preparation of prepolymer PLA: After drying lactic acid, a catalyst is added, and the temperature is raised to 135-145℃ under a protective atmosphere. The prepolymer reaction is carried out for 3-5 hours to obtain prepolymer PLA. (3) Preparation of prepolymer PBAT: Terephthalic acid, adipic acid and 1,4-butanediol are mixed in a molar ratio of 1:1:(2.1-2.5), a catalyst is added, and the mixture is heated to 175-185℃ under protective gas for 2-4 hours. Then, the mixture undergoes polycondensation under high temperature and high vacuum conditions to obtain prepolymer PBAT. (4) Synthesis of copolyester: The intermediate obtained in step (1) is mixed with prepolymer PLA and prepolymer PBAT at a mass ratio of (1-2):8:4, and esterification polycondensation reaction is carried out in a polycondensation reactor under high temperature and high vacuum conditions to obtain polyester. (5) Melt spinning: After drying the above polyester, melt spinning and drawing are performed to obtain biodegradable polyester fibers.

[0024] Specifically, in the preparation of the intermediate, 2,6-diaminopimelic acid and HK-560 are mixed in a 1:2 molar ratio and reacted in DMF solvent, under a protective gas and at 85-95℃ for 5-7 hours. This reaction causes the amino and epoxy groups to open the ring, generating an intermediate containing carboxyl, secondary hydroxyl and silaneoxy groups, which provides active functional groups for subsequent copolymerization and crosslinking with wood pulp fibers.

[0025] Prepolymer PLA and prepolymer PBAT are prepolymerized separately at corresponding temperatures, under protective gas conditions, and with corresponding reaction times to ensure that carboxyl and hydroxyl groups are formed at both ends of the two prepolymers, and that the molecular weight is uniform, enabling them to copolymerize smoothly with the intermediate. During copolyester synthesis, the intermediate, prepolymer PLA, and prepolymer PBAT are mixed in a specific mass ratio and subjected to esterification polycondensation under high temperature and high vacuum conditions. This allows the functional groups of the three components to react fully, forming a structurally stable copolyester. If necessary, a catalyst can be added to promote the copolymerization reaction.

[0026] Finally, through melt spinning and stretching, the fibers are formed uniformly and have a dense structure. The resulting biodegradable polyester fibers not only have good biodegradability, but also effectively improve the mechanical properties of paper through the condensation of surface silanoxy groups with the hydroxyl groups of pulp fibers.

[0027] Further, in step (4), the temperature of the esterification polycondensation reaction is 215-225℃, the vacuum degree is 25-35Pa, and the reaction time is 5-7h; in step (5), the spinning temperature of the melt spinning is 210-225℃, the winding speed is 1150-1250m / min, and the draw ratio is 3-5 times.

[0028] Specifically, the esterification polycondensation reaction in step (4) allows the intermediate to fully react with prepolymer PLA and prepolymer PBAT to form a structurally stable copolyester. This reaction needs to be achieved through esterification dehydration and polycondensation chain extension. With a temperature of 215-225℃, a vacuum of 25-35Pa, and a reaction time of 5-7h, it is possible to ensure that the carboxyl and hydroxyl groups in the reaction system can fully undergo esterification reaction, and to promptly remove the small molecule substances generated by the reaction, thereby promoting the polycondensation reaction in the forward direction and avoiding side reactions. At the same time, it controls the molecular weight distribution of the copolyester to be uniform, ensuring that it has good melt spinning performance.

[0029] Step (5) uses a spinning temperature of 210-225℃ to completely melt the copolyester without degradation. Combined with a winding speed of 1150-1250m / min and a draw ratio of 3-5 times, the molten copolyester can form uniform and fine fiber filaments. At the same time, the crystallinity and mechanical strength of the fiber are improved by drawing, so that the resulting biodegradable polyester fiber has a dense structure and uniform size.

[0030] As one of the preferred embodiments of the present invention, in step S2, the soaking involves soaking bleached hardwood pulp and bleached softwood pulp in water at 25-35°C for 5-7 hours respectively; in step S3, the concentration of the mixed pulp in the defrosting treatment is 3-5%, the defrosting speed is 4000-5000 rpm, and the defrosting time is 8-12 minutes.

[0031] Specifically, in step S2, the two types of pulp are soaked separately at a water temperature of 25-35℃ for 57 hours, allowing the hardwood pulp and softwood pulp to fully absorb water and swell, thus expanding the internal structure of the fibers and reducing fiber damage during subsequent processing. Soaking the two pulps separately also ensures that they reach a similar wetting state, providing stable conditions for subsequent mixing. In step S3, the concentration of the mixed pulp is controlled at 35%, and a debonding speed of 4000-5000 rpm and a debonding time of 812 minutes are used to fully disperse the wetted pulp fiber bundles, ensuring uniform fiber dispersion without excessive cutting or excessive filamentation.

[0032] In one preferred embodiment of the present invention, in step S4, the pulp concentration of the pulping process is 3-5%, the pulping gap is 0.2-0.4 mm, and the freeness is controlled at 38-42°SR; in step S5, the pulp concentration of the papermaking process is 0.8-1.2%, and the paper basis weight is 50-60 g / m³. 2 .

[0033] Specifically, in step S4, by controlling the pulp concentration, pulping gap and beating degree, the pulp fibers are moderately fractured under gentle mechanical treatment, increasing the exposure of hydroxyl groups on the fiber surface, providing conditions for subsequent chemical crosslinking with biodegradable polyester fiber powder, while ensuring that the fiber length and strength are not excessively damaged.

[0034] In step S5, after adding the biodegradable polyester fiber powder and inorganic silver ion antibacterial agent, the pulp concentration is adjusted to ensure uniform dispersion and reduced flocculation during the forming process, resulting in a smoother and denser paper structure. This enhances the binding capacity of the plant fibers themselves and provides a stable dispersion environment for the biodegradable polyester fiber powder, allowing for a more complete condensation reaction between silanol and cellulose hydroxyl groups, a more uniform internal cross-linking structure in the paper, and ultimately, a simultaneous improvement in the paper's mechanical strength and forming stability.

[0035] As one of the preferred embodiments of the present invention, in step S5, the two-stage drying is specifically as follows: the first-stage drying temperature is 115-125℃, and the paper is dried until the moisture content is 24-26%; the second-stage drying temperature is 55-65℃, and the paper is dried until the final moisture content is 4.5-5.5%.

[0036] Specifically, step S5 employs a two-stage drying process. The first stage, at a temperature of 115-125℃, dries the paper to a moisture content of 24-26%, quickly removing most of the free moisture while preventing uneven evaporation that could lead to warping and cracking. It also promotes the stable formation of the cross-linked structure. The subsequent second stage, at a lower temperature of 55-65℃, dries the paper to a final moisture content of 4.5-5.5%, removing residual moisture and controlling the final moisture content within a reasonable range. This ensures both effective drying and a stable internal cross-linked structure, guaranteeing the paper's mechanical properties and stability in use.

[0037] The present invention will be further described below through examples and comparative examples. Example 1

[0038] S1. Preparation of intermediate: 2,6-Diaminopimelic acid and silane coupling agent HK-560 were mixed at a molar ratio of 1:2, DMF solvent was added, and the mixture was stirred at 90°C for 6 hours under nitrogen protection. The intermediate was then obtained after post-treatment. Prepolymer PLA preparation: After drying lactic acid, a catalyst was added, and the temperature was raised to 140℃ under nitrogen protection. The prepolymer reaction was carried out for 4 hours to obtain prepolymer PLA. Preparation of prepolymer PBAT: Terephthalic acid, adipic acid and 1,4-butanediol were mixed in a molar ratio of 1:1:2.3, a catalyst was added, and the mixture was heated to 180°C for 3 hours under nitrogen protection. Then, the mixture was polycondensed under high temperature and high vacuum to obtain prepolymer PBAT. Copolyester synthesis: The intermediate, prepolymer PLA and prepolymer PBAT were mixed in a mass ratio of 1.5:8:4 and esterified and polycondensed at 220°C and 30 Pa vacuum for 6 h to obtain the copolyester. Melt spinning: After drying the copolyester, melt spinning is carried out at 217.5℃, a winding speed of 1200m / min, and a draw ratio of 4 times to obtain biodegradable polyester fibers.

[0039] S2. Soak bleached hardwood pulp and bleached softwood pulp separately in water at 30℃ for 6 hours, and mix them at an oven-dry mass ratio of 8.5:4.5 to obtain mixed pulp.

[0040] S3. Adjust the concentration of the mixed pulp to 4%, and decompose it in a decomposer at 4500 rpm for 10 minutes to obtain decomposed pulp.

[0041] S4. The slurry is ground in a disc at a pulping concentration of 4% and a pulping gap of 0.3mm, and the beating degree is controlled at 40°SR to obtain a finely ground mixed pulp.

[0042] S5. Crush biodegradable polyester fibers into fiber powder with a diameter of 5-10μm and a length of 0.2-0.4mm, and add it to the refined mixed pulp at 8% of the total dry pulp mass. At the same time, add inorganic silver ion antibacterial agent at 0.5% of the total dry pulp mass, adjust the pulp concentration to 1.0%, and form the paper on a paper machine. The paper basis weight is 55g / m³. 2 After pressing and dehydration, the paper undergoes two stages of drying: the first stage is dried at 120℃ to a moisture content of 25%, and the second stage is dried at 60℃ to a final moisture content of 5.0%, resulting in eco-friendly paper.

[0043] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no biodegradable polyester fiber powder was added, while the rest of the preparation process was the same as in Example 1.

[0044] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that: commercially available ordinary PLA / PBAT copolyester fiber powder was used, which was not modified by 2,6-diaminopimelic acid and HK-560, and did not contain hydrolyzable silaneoxy structures. The addition ratio and other preparation processes were the same as those in Example 1.

[0045] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the particle size of the biodegradable polyester fiber powder is controlled to be 20 μm in diameter and 1.0 mm in length, while the rest of the formulation and preparation process are the same as in Example 1.

[0046] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 uses a one-stage drying method, directly drying at 120°C to the final moisture content of the paper at 5.0%, without using two-stage drying. The rest of the formula and preparation process are the same as in Example 1.

[0047] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the pulping degree is controlled at 25°SR, while the rest of the formulation and preparation process are the same as in Example 1.

[0048] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that in the S1 copolyester synthesis step, the mass ratio of intermediate, prepolymer PLA, and prepolymer PBAT is adjusted to 0.1:8:4, while the rest of the formulation and preparation process are the same as in Example 1.

[0049] Performance testing Tear index testing shall be conducted in accordance with GB / T455, tensile index testing shall be conducted in accordance with GB / T12914, internal bond strength testing method shall refer to standard GB / T26203, porosity shall be measured by mercury porosimeter, and biodegradation percentage shall be determined in accordance with GB / T19277.1.

[0050] The performance test data of the above embodiments and comparative examples are shown in the table below:

[0051] Comparing the test data of Example 1 and Comparative Example 1, it can be seen that Comparative Example 1, without the addition of biodegradable polyester fiber powder, has significantly lower tensile index, tear index, and internal bond strength than Example 1, while its porosity is significantly higher. This indicates that relying solely on hydrogen bonding between plant fibers is insufficient to achieve a high-strength structure. The addition of biodegradable polyester fiber powder can form covalent crosslinks with pulp fibers, significantly improving the mechanical properties and density of the paper. Comparative Example 2 uses commercially available ordinary PLA / PBAT copolyester fiber powder, without modification treatment with 2,6-diaminopimelic acid and HK-560. Although its mechanical properties are better than Comparative Example 1, they are still significantly lower than those of Example 1, and its porosity is also higher than that of Example 1. This indicates that the silaneoxy structure introduced by the intermediate can achieve chemical bonding between the fiber powder and plant fibers, and the same reinforcing effect cannot be achieved by the physical filling of the polyester itself alone.

[0052] Comparative Example 3 increased the particle size of the biodegradable polyester fiber powder to 20 μm and the length to 1.0 mm. Its tensile index, tear index, and internal bond strength were significantly lower than in Example 1, while its porosity increased. This indicates that excessively large fiber particles are difficult to disperse uniformly, hindering the sufficient contact and condensation of silanol groups with pulp hydroxyl groups, thus affecting the integrity of the crosslinked network. Comparative Example 4 used a one-stage high-temperature drying process to the final moisture content, without using a two-stage gradient drying. The mechanical properties were slightly lower than in Example 1, and the porosity also increased. This indicates that two-stage drying can effectively avoid internal stress and microcracks caused by excessively rapid moisture evaporation, which is beneficial for stabilizing the formed crosslinked structure. Comparative Example 5 controlled the freeness at 25°SR, lower than the preferred range of 38-42°SR. Insufficient fiber fissuring resulted in a small specific surface area and fewer reaction sites with the fiber powder, leading to significantly weaker mechanical properties and higher porosity than in Example 1.

[0053] Comparative Example 6 significantly reduced the intermediate feed ratio (0.1:8:4) in the copolyester synthesis, almost eliminating the crosslinking bridging effect. Its mechanical properties were close to those of Comparative Example 2, but far lower than those of Example 1, further verifying that the side chain secondary hydroxyl and silaneoxy groups introduced by the intermediate can achieve covalent reinforcement.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength antibacterial eco-paper, characterized in that, The eco-paper comprises the following components by weight percentage: 60-65% bleached hardwood pulp; 20-28% bleached softwood pulp; Biodegradable polyester fiber powder 5.0-8.5%; And an inorganic silver ion antibacterial agent comprising 0.1-1.0% of the total dry fiber mass; The remainder is moisture; The biodegradable polyester fiber powder is obtained by pulverizing biodegradable polyester fibers. The biodegradable polyester fibers are copolymerized from intermediates, prepolymer PLA and prepolymer PBAT. The intermediates are prepared by reacting 2,6-diaminopimelic acid with silane coupling agent HK-560.

2. The high-strength antibacterial eco-paper according to claim 1, characterized in that, The biodegradable polyester fiber powder has a diameter of 5-10 μm and a length of 0.2-0.4 mm.

3. The method for preparing high-strength antibacterial ecological paper according to any one of claims 1 to 2, characterized in that, Includes the following steps: The amino group of S1,2,6-diaminopimelic acid undergoes ring-opening with the epoxy group of HK-560 under anhydrous conditions to obtain an intermediate. The intermediate is mixed with prepolymer PLA and prepolymer PBAT for esterification polycondensation reaction to obtain polyester. The polyester is dried and melt-spun to obtain biodegradable polyester fiber. S2. After soaking bleached hardwood pulp and bleached softwood pulp separately, they are mixed and then mixed at an oven-dry mass ratio of (7-10):(3-5) to obtain mixed pulp. S3. Adjust the concentration of the mixed pulp obtained in step S2, and decompose it in a decomposition machine to obtain decomposed pulp; S4. The slurry obtained in step S3 is ground using a disc mill until the set beating degree is reached to obtain a finely ground mixed slurry. S5. Crush the biodegradable polyester fiber and add it to the finely ground mixed pulp obtained in step S4 at a ratio of 5-10% of the total dry pulp mass. At the same time, add inorganic silver ion antibacterial agent at a ratio of 0.1-1.0% of the total dry pulp mass. After stirring evenly, adjust the pulp concentration, form it on a paper machine, and after pressing and dewatering, perform two-stage drying to obtain eco-paper.

4. The method for preparing high-strength antibacterial ecological paper according to claim 3, characterized in that, In step S1, the preparation of the biodegradable polyester fiber includes the following steps: (1) Preparation of intermediate: 2,6-diaminopimelic acid and HK-560 were mixed at a molar ratio of 1:2, DMF solvent was added, and the mixture was stirred at 85-95℃ for 5-7 h under protective gas. The intermediate was then obtained after post-treatment. (2) Preparation of prepolymer PLA: After drying lactic acid, a catalyst is added, and the temperature is raised to 135-145℃ under a protective atmosphere. The prepolymer reaction is carried out for 3-5 hours to obtain prepolymer PLA. (3) Preparation of prepolymer PBAT: Terephthalic acid, adipic acid and 1,4-butanediol are mixed in a molar ratio of 1:1:(2.1-2.5), a catalyst is added, and the mixture is heated to 175-185℃ under protective gas for 2-4 hours. Then, the mixture undergoes polycondensation under high temperature and high vacuum conditions to obtain prepolymer PBAT. (4) Synthesis of copolyester: The intermediate obtained in step (1) is mixed with prepolymer PLA and prepolymer PBAT at a mass ratio of (1-2):8:4, and esterification polycondensation reaction is carried out in a polycondensation reactor under high temperature and high vacuum conditions to obtain polyester. (5) Melt spinning: After drying the above polyester, melt spinning and drawing are performed to obtain biodegradable polyester fibers.

5. The method for preparing high-strength antibacterial ecological paper according to claim 4, characterized in that, In step (4), the temperature of the esterification polycondensation reaction is 215-225℃, the vacuum degree is 25-35Pa, and the reaction time is 5-7h; in step (5), the spinning temperature of the melt spinning is 210-225℃, the winding speed is 1150-1250m / min, and the draw ratio is 3-5 times.

6. The method for preparing high-strength antibacterial ecological paper according to claim 3, characterized in that, In step S2, the soaking involves immersing bleached hardwood pulp and bleached softwood pulp in water at 25-35℃ for 5-7 hours respectively; in step S3, the concentration of the mixed pulp in the defrosting treatment is 3-5%, the defrosting speed is 4000-5000 rpm, and the defrosting time is 8-12 minutes.

7. The method for preparing high-strength antibacterial ecological paper according to claim 3, characterized in that, In step S4, the pulp concentration of the pulping process is 3-5%, the pulping gap is 0.2-0.4 mm, and the freeness is controlled at 38-42°SR; in step S5, the pulp concentration of the papermaking process is 0.8-1.2%, and the paper basis weight is 50-60 g / m³. 2 .

8. The method for preparing high-strength antibacterial ecological paper according to claim 3, characterized in that, In step S5, the two-stage drying process is as follows: the first stage drying temperature is 115-125℃, drying until the paper moisture content is 24-26%; the second stage drying temperature is 55-65℃, drying until the final paper moisture content is 4.5-5.5%.

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