Environment-friendly ecological paper and preparation method thereof

Abstract

The invention discloses environment-friendly ecological paper and a preparation method thereof.The environment-friendly ecological paper comprises a paper base layer and a bio-based barrier coating compounded on the surface of the paper base layer, and the paper base layer is prepared by compounding raw materials such as regenerated plant fibers, agricultural waste fibers, modified nanocellulose and a biological modifier; the bio-based barrier coating is prepared from environment-friendly raw materials such as modified lignin, polyhydroxyalkanoate and natural plant essential oil; the preparation method comprises the steps of raw material pretreatment, paper base slurry preparation, paper base forming, in-machine coating compounding and post-treatment, and the regenerated fiber and agricultural waste fiber compound pretreatment, nano cellulose plasma modification and biological modifier synergistic effect are matched with the bio-based coating optimization and in-machine coating process, so that the regenerated fiber and agricultural waste fiber composite paper is obtained. Renewable resources and agricultural wastes are combined and utilized, and the formed environment-friendly paper has relatively good mechanical strength, antibacterial property and barrier property.

Description

Technical Field

[0001] This invention relates to the field of paper preparation technology, specifically to an environmentally friendly eco-paper and its preparation method. Background Technology

[0002] With the tightening of environmental protection policies and the popularization of the concept of global sustainable development, the traditional paper industry faces problems such as reliance on wood as raw materials, high energy consumption in production, large amounts of wastewater discharge, and difficulty in degrading finished products. At the same time, existing environmentally friendly packaging paper and eco-paper generally have defects such as insufficient mechanical strength, poor barrier properties, limited water and oil resistance, or complex preparation processes, high costs, and excessively long degradation cycles, making it difficult to meet the dual needs of environmental protection and practicality. Currently, the vast majority of packaging materials for hygiene products and medical supplies are made of plastic. These can be categorized by material: PP synthetic film, PE synthetic film, PET synthetic film, PS synthetic film, and ABS synthetic film. All of these are difficult-to-degrade plastic products, leading to a series of microplastic hazards (microplastics ≤5mm), namely plastic fragments and particles with a diameter less than 5mm. Therefore, a biodegradable eco-paper alternative to plastic packaging is needed to solve these problems. Currently, the main plastic substitutes on the market are polylactic acid (PLA) products, but due to their high price, high cost, and inability to meet strength and other requirements, they are not suitable.

[0003] Wood pulp paper, as a product made from natural raw materials, is a relatively ideal packaging material. It is completely biodegradable. Through microbial degradation and the action of the natural environment, it will be decomposed into cellulose. Then, through acid degradation, oxidative degradation, microbial degradation, and photodegradation, it will form water, carbon dioxide, and inorganic matter. These components will enter the normal natural cycle, be absorbed and solidified by plants, and enter a new resource cycle process.

[0004] In some existing technologies, eco-paper uses plant fibers as the main raw material and adds modified fillers to improve performance. However, the pretreatment of agricultural waste fibers is not refined enough, resulting in insufficient fiber bonding strength. The application of bio-modification technology is not mature enough, making it difficult to balance fiber strength and degradation performance. Barrier coatings mostly use chemically synthesized materials, which pose environmental risks, and the large-scale application of in-machine coating technology is still limited. Summary of the Invention

[0005] To address the technical deficiencies in the background technology, this invention proposes an environmentally friendly eco-paper and its preparation method, solving the aforementioned technical problems and meeting practical needs. The specific technical solution is as follows: An environmentally friendly eco-paper, comprising a paper base and a bio-based barrier coating composited on the surface of the paper base, wherein the paper base is made of the following raw materials in parts by weight: 40-60 parts of recycled plant fiber, 20-35 parts of agricultural waste fiber, 5-12 parts of nanocellulose, 3-8 parts of biomodifier, 1-4 parts of environmentally friendly retention aid, and 80-120 parts of softened water. The regenerated plant fiber includes at least one of regenerated wood pulp and regenerated bamboo pulp, and the fiber brooming rate is ≥85% after bio-enzymatic deinking treatment; The agricultural waste fiber is a compound of at least two kinds of agricultural straw and fruit shell fiber, which is pretreated by steam explosion. The nanocellulose is modified by plasma grafting, and the biomodifier is a compound formed by combining white rot fungus inoculant and laccase, with a mass ratio of 2:1-3:1. The bio-based barrier coating is made from the following raw materials in parts by weight: 10-20 parts modified lignin, 5-12 parts polyhydroxyalkanoate (PHA), 1-3 parts plant essential oil, 0.5-2 parts water-based dispersant, and 30-50 parts deionized water. The modified lignin is subjected to aldehyde-assisted separation treatment, and the plant essential oil is a natural antibacterial essential oil.

[0006] A method for preparing environmentally friendly eco-paper, characterized in that, Step 1: Raw material pretreatment, including bio-enzymatic deinking of regenerated plant fibers, steam explosion pretreatment of agricultural waste fibers, plasma grafting modification of nanocellulose, and preparation of bio-based barrier coating slurry. Step 2: Preparation of paper-based pulp. The pretreated recycled plant fibers and agricultural waste fibers are mixed with a biomodifier and fermented for modification. Modified nanocellulose and environmentally friendly retention aids are then added and mixed to obtain paper-based pulp. Step 3: Paper base forming. The paper base pulp is formed by wire forming, pressing and dewatering, and drying in sections to obtain the paper base layer. Step 4: Coating lamination, using an in-machine coating process to apply the bio-based barrier coating slurry to the surface of the paper base layer and then drying and curing it; Step 5: Post-processing. The coated paper is calendered, slit, and rolled to obtain environmentally friendly eco-paper.

[0007] As an improvement to the above scheme, the agricultural waste fiber is selected from at least two of sugarcane bagasse fiber, wheat straw fiber, and banana peel fiber; the environmentally friendly retention aid is selected from at least one of chitosan and starch-grafted acrylamide; and the aqueous dispersant is selected from at least one of polyethylene glycol and polyvinyl alcohol.

[0008] As an improvement to the above scheme, the diameter of the nanocellulose is 20-50nm and the length is 100-500nm; the conditions for plasma grafting modification are Ar gas pressure 0.1mbar, power 150W, and processing time 10-20min; the thickness of the bio-based barrier coating is 5-15μm and the contact angle is >115°.

[0009] As an improvement to the above solution, step 1 specifically includes: Step 1.1: Pretreatment of regenerated plant fiber: Add the regenerated plant fiber to softened water, add bio-enzyme deinking agent, control the temperature at 45-55℃, pH value at 6.5-7.5, stirring speed at 300-500r / min, deinking for 20-30min, while using ultrasonic-assisted deinking at an ultrasonic frequency of 40-50KHz, then filter, wash until neutral, pulp and control the fiber length at 0.8-2.5mm, fiber fibrillation rate ≥85%, to obtain pretreated regenerated plant fiber; Step 1.2: Agricultural waste fiber pretreatment: crush agricultural waste fiber to 20-40 mesh, wash with deionized water 2-3 times, steam explosion treatment, steam pressure 3.2-3.8MPa, treatment time 3-6min, cool and crush and screen to obtain pretreated agricultural waste fiber; Step 1.3: Nanocellulose modification: Nanocellulose is added to deionized water and dispersed evenly. It is then subjected to plasma grafting modification treatment. The modification conditions are Ar gas pressure 0.1 mbar, power 150W, and treatment time 10-20 min to obtain modified nanocellulose. Step 1.4: Coating raw material pretreatment: Add modified lignin and polyhydroxy fatty acid ester to deionized water, add water-based dispersant, control the temperature at 60-70℃, stir at 600-800r / min, disperse for 30-40min, add plant essential oil and continue stirring for 15-25min, cool to room temperature to obtain bio-based barrier coating slurry.

[0010] As an improvement to the above scheme, in step 2, pretreated regenerated plant fibers and pretreated agricultural waste fibers are added to softened water, the solid-liquid ratio is controlled at 1:1.2-1:1.8, a biological modifier is added, the temperature is controlled at 28-32℃, fermentation modification is carried out for 12-24 hours, and stirring is performed for 10-15 minutes every 4-6 hours; modified nanocellulose and environmentally friendly retention aid are added, the temperature is raised to 40-50℃, and the mixture is mixed evenly at 400-600 r / min, and kept warm and stirred for 20-30 minutes to obtain paper-based pulp; As an improvement to the above scheme, in step 3, the paper base pulp is fed into the paper machine, formed in the wire section, pressed and dewatered, and dried in stages. The pressing pressure is 0.3-0.6MPa, the drying temperature is 80-110℃, and the drying time is 15-25min. The moisture content of the paper base is controlled to be ≤8% to obtain the paper base. In the segmented drying process, the temperature of the first section of the drying section is 80-90℃, the temperature of the middle section is 90-100℃, and the temperature of the last section is 100-110℃.

[0011] As an improvement to the above scheme, in step 4, an in-machine coating process is used to coat the bio-based barrier coating slurry onto at least one side of the paper substrate, with a coating amount of 8-15 g / m². 2 Control the drying temperature to 70-90℃, the drying time to 10-15 minutes, and control the coating moisture content to ≤5%. As an improvement to the above scheme, in step 5, the coated paper is calendered at a temperature of 50-70℃, a pressure of 0.2-0.4MPa, and a linear speed of 10-15m / min. Then it is slit, wound, and after passing inspection, environmentally friendly ecological paper is obtained.

[0012] The beneficial effects of this invention are as follows: In this technical solution, the pretreatment of recycled plant fiber and agricultural waste fiber combines recycled resources with agricultural waste at the raw material level. The synergistic effect of nanocellulose plasma modification and biological modifier, combined with bio-based barrier coating, is optimized to give the eco-paper strong mechanical strength, antibacterial properties, water resistance and barrier properties. This solves the problems of easy breakage and single function of existing eco-paper. At the environmental level, it can achieve high degradation and reduce residual pollution. At the production level, it can significantly reduce energy consumption and wastewater discharge. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the interlayer structure of the environmentally friendly eco-paper of the present invention.

[0014] Figure 2 This is a schematic diagram illustrating the preparation method of the environmentally friendly eco-paper of the present invention.

[0015] Among them: paper base layer 1, bio-based barrier coating 2. Detailed Implementation

[0016] The embodiments of the present invention will be described below with reference to the accompanying drawings and related examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to the relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0017] An environmentally friendly eco-paper, comprising a paper base layer 1 and a bio-based barrier coating 2 composited on the surface of the paper base layer 1, wherein the paper base layer 1 is made of the following raw materials in parts by weight: 40-60 parts of recycled plant fiber, 20-35 parts of agricultural waste fiber, 5-12 parts of nanocellulose, 3-8 parts of biomodifier, 1-4 parts of environmentally friendly retention aid, and 80-120 parts of softened water. In the aforementioned regenerated plant fiber solution, the regenerated plant fiber includes at least one of regenerated wood pulp and regenerated bamboo pulp. After being treated with bio-enzymatic deinking, the fiber fibrillation rate is ≥85%, wherein the fiber length is controlled between 0.8-2.5 mm, which improves the bonding force between fibers and simultaneously achieves resource recycling and reduces dependence on virgin wood.

[0018] Furthermore, the agricultural waste fiber is a compound of at least two kinds of agricultural straw and fruit shell fiber, which has been pretreated by steam explosion. The agricultural waste fiber can be selected from at least two of sugarcane bagasse fiber, wheat straw fiber, and banana peel fiber, and pretreated with steam explosion at a pressure controlled at 3.2-3.8 MPa for 3-6 minutes. This process increases the specific surface area of ​​the fiber by 3.0-3.5 times, removes impurities and some hemicellulose from the fiber surface, and improves the compatibility of the fiber with other components. Using at least two agricultural waste fibers in combination can compensate for the performance defects of using a single agricultural waste fiber and optimize the mechanical strength and air permeability of the paper base layer 1.

[0019] In the aforementioned nanocellulose technical solution, the nanocellulose has a diameter of 20-50 nm and a length of 100-500 nm, is selected from plant-derived nanocellulose, and undergoes plasma grafting modification treatment (Ar gas pressure 0.1 mbar, power 150 W) to construct a nanoscale microporous structure on the fiber surface, thereby improving the binding efficiency between the fiber and the biomodifier, and simultaneously enhancing the tensile strength and folding resistance of the paper base layer 1, with a tensile strength reaching 6.0-7.5 GPa; Furthermore, the nanocellulose is subjected to plasma grafting modification treatment. The biomodifier is a compound formed by combining white rot fungus agent and laccase, with a mass ratio of 2:1 to 3:1. The white rot fungus agent can directionally degrade lignin in the fiber, reducing the use of chemical delignification reagents, reducing environmental pollution and production energy consumption. Laccase can selectively oxidize hydroxyl groups on the fiber surface to form carbonyl groups, thereby improving the interfacial bonding strength between the fiber and nanocellulose.

[0020] The environmentally friendly retention aid is selected from at least one of chitosan and starch-grafted acrylamide. It has no chemical residue, can improve the retention rate of fibers and fillers, reduce wastewater discharge, and at the same time help improve the strength and forming effect of the paper base layer 1, so that the fiber retention rate is ≥92%, reduce the raw material loss in the production process, and further reduce the loss of recycled resources.

[0021] In the embodiment of the bio-based barrier coating 2, the bio-based barrier coating 2 is made from the following raw materials in parts by weight: 10-20 parts modified lignin, 5-12 parts polyhydroxyalkanoate (PHA), 1-3 parts plant essential oil, 0.5-2 parts aqueous dispersant, and 30-50 parts deionized water, wherein the plant essential oil is a natural antibacterial essential oil.

[0022] The modified lignin, after sequential aldehyde-assisted separation treatment, can remove impurities and reduce color depth, improving the appearance of the coating while retaining its adhesive properties. It replaces traditional chemical coating raw materials and reduces toxicity, with a toxicity level 2-4 orders of magnitude lower than that of traditional bisphenol A (BPA) coatings. The plant essential oil is selected from at least one of tea tree oil and lemon oil, which can not only improve the antibacterial properties of the coating but also accelerate the degradation rate after product disposal and shorten the degradation cycle. The aqueous dispersant is selected from at least one of polyethylene glycol and polyvinyl alcohol. When used, it can make the components of the bio-based barrier coating 2 evenly dispersed, improve the adhesion between the coating and the paper base layer 1, prevent the coating from falling off, and at the same time ensure the air permeability of the coating to prevent the paper base layer 1 from absorbing moisture and deforming. The coating thickness is controlled at 5-15μm, the contact angle is >115°, and the barrier performance is better than the traditional PE coating process.

[0023] A method for preparing environmentally friendly eco-paper includes the following steps; Step 1: Raw material pretreatment, including bio-enzymatic deinking of regenerated plant fibers, steam explosion pretreatment of agricultural waste fibers, plasma grafting modification of nanocellulose, and preparation of bio-based barrier coating slurry 2. Step 2: Preparation of paper-based pulp. The pretreated recycled plant fibers and agricultural waste fibers are mixed with a biomodifier and fermented for modification. Modified nanocellulose and environmentally friendly retention aids are then added and mixed to obtain paper-based pulp. Step 3: Paper base forming. The paper base pulp is formed by wire forming, press dewatering, and segmented drying to obtain paper base layer 1; Step 4: Coating lamination. The bio-based barrier coating 2 slurry is applied to the surface of the paper base layer 1 using an in-machine coating process and then dried and cured. Step 5: Post-processing. The coated paper is calendered, slit, and rolled to obtain environmentally friendly eco-paper.

[0024] Furthermore, in the above scheme, the agricultural waste fiber is selected from at least two of sugarcane bagasse fiber, wheat straw fiber, and banana peel fiber; the environmentally friendly retention aid is selected from at least one of chitosan and starch-grafted acrylamide; and the aqueous dispersant is selected from at least one of polyethylene glycol and polyvinyl alcohol.

[0025] Furthermore, in the above scheme, the diameter of the nanocellulose is 20-50nm and the length is 100-500nm; the conditions for plasma grafting modification are Ar gas pressure 0.1mbar, power 150W, and processing time 10-20min; the thickness of the bio-based barrier coating 2 is 5-15μm and the contact angle is >115°.

[0026] Step 1 of this method specifically includes pretreatment of regenerated plant fibers, pretreatment of agricultural waste fibers, pretreatment of raw materials such as nanocellulose modification and bio-based barrier coating. In step 1.1: Pretreatment of regenerated plant fibers: Add regenerated plant fibers to softened water, add bio-enzyme deinking agent, control the temperature at 45-55℃, pH value at 6.5-7.5, stirring speed at 300-500r / min, deinking treatment for 20-30min, and simultaneously use ultrasonic-assisted deinking with an ultrasonic frequency of 40-50KHz. Then filter, wash until neutral, pulp and control the fiber length at 0.8-2.5mm, fiber fibrillation rate ≥85%, to obtain pretreated regenerated plant fibers; In step 1.2: Agricultural waste fiber pretreatment: agricultural waste fiber is crushed to 20-40 mesh, washed with deionized water 2-3 times, steam explosion treatment, steam pressure 3.2-3.8MPa, treatment time 3-6min, cooled, crushed and sieved to obtain pretreated agricultural waste fiber; In step 1.3: Nanocellulose modification: Nanocellulose is added to deionized water and dispersed evenly, and then subjected to plasma grafting modification treatment. The modification conditions are Ar gas pressure 0.1 mbar, power 150W, and treatment time 10-20 min to obtain modified nanocellulose. In step 1.4: Coating raw material pretreatment: Modified lignin and polyhydroxy fatty acid ester are added to deionized water, water-based dispersant is added, temperature is controlled at 60-70℃, stirring speed is 600-800r / min, dispersion is carried out for 30-40min, plant essential oil is added and stirring is continued for 15-25min, and cooled to room temperature to obtain bio-based barrier coating 2 slurry.

[0027] In step 2 of this technical solution, pretreated regenerated plant fibers and pretreated agricultural waste fibers are added to softened water, with a solid-liquid ratio controlled at 1:1.2-1:1.8. A biomodifier is added, and the temperature is controlled at 28-32℃. Fermentation modification is carried out for 12-24 hours, with stirring for 10-15 minutes every 4-6 hours. Modified nanocellulose and environmentally friendly retention aids are added, and the temperature is raised to 40-50℃. The mixture is stirred evenly at 400-600 r / min and kept warm for 20-30 minutes to obtain paper-based pulp. The concentration of the paper-based pulp is controlled at 10%-18%.

[0028] In step 3 of this technical solution, the paper base pulp is fed into the paper machine, formed in the wire section, dewatered by pressing, and dried in stages. The pressing pressure is 0.3-0.6MPa, the drying temperature is 80-110℃, and the drying time is 15-25min. The moisture content of the paper base layer 1 is controlled to be ≤8%, and the paper base layer 1 is obtained. During the segmented drying process, the temperature of the first section of the drying stage is 80-90℃, the temperature of the middle section is 90-100℃, and the temperature of the last section is 100-110℃, in order to avoid localized excessively rapid drying that could cause cracking or deformation of the paper base layer 1.

[0029] In step 4 of this technical solution, an in-machine coating process is used to coat the bio-based barrier coating 2 slurry onto one or both sides of the paper base layer 1, with a coating amount of 8-15 g / m². 2 The paper is then fed into a dryer, where the drying temperature is controlled at 70-90℃ and the drying time is 10-15 minutes to ensure that the coating is cured and formed. The moisture content of the coating is controlled to be ≤5%. Compared with external coating, this method can reduce the cost of transporting raw paper, the energy consumption of secondary coating, and paper loss. It can save a lot of production costs per ton of paper and is suitable for large-scale production.

[0030] In step 5 of this technical solution, the coated paper is calendered at a temperature of 50-70℃, a pressure of 0.2-0.4MPa, and a linear speed of 10-15m / min. After calendering and winding, environmentally friendly eco-paper is obtained after passing inspection. Calendering can improve the smoothness of the paper surface and reduce the surface roughness to 0.5-0.7μm, which can meet the needs of high-end packaging.

[0031] In a first preferred embodiment of the present invention, the proportion of environmentally friendly eco-paper raw materials is as follows: The paper base layer 1 comprises: 45 parts recycled wood pulp, 12 parts sugarcane bagasse fiber, 10 parts wheat straw fiber, 8 parts nanocellulose, 5 parts biological modifier (white rot fungus inoculant: laccase = 2:1), 2 parts chitosan, and 100 parts softened water. The bio-based barrier coating 2 comprises: 15 parts modified lignin, 8 parts PHA, 2 parts tea tree oil, 1 part polyethylene glycol, and 40 parts deionized water.

[0032] The method for preparing the environmentally friendly eco-paper in this embodiment is as follows: Step 1: Raw material pretreatment Pretreatment of regenerated plant fibers: Add regenerated wood pulp to softened water, add bio-enzyme deinking agent, control the temperature at 48℃, pH=7.0, and stirring speed at 350r / min for 25min for deinking treatment, use ultrasonic frequency at 45KHz to assist deinking, filter and wash until neutral, control the fiber length at 1.0-2.2mm after pulping, and the fiber fibrillation rate at 86%; Agricultural waste fiber pretreatment: Sugarcane bagasse fiber and wheat straw fiber are crushed to 30 mesh, washed three times with deionized water, treated with steam pressure of 3.5MPa for 4 minutes, cooled, crushed and screened. Nanocellulose modification: Nanocellulose (diameter 30-40nm, length 200-400nm) was dispersed in deionized water and plasma grafting modified (Ar pressure 0.1mbar, power 150W, 15min). Coating raw material pretreatment: Modified lignin and PHA are added to deionized water, polyethylene glycol is added, the temperature is controlled at 65℃ and the stirring speed is 700r / min for 35min, tea tree oil is added and stirred for 20min, and then cooled for later use.

[0033] Step 2: Preparation of paper-based pulp: Add pretreated recycled wood pulp, bagasse fiber, and wheat straw fiber to softened water at a solid-liquid ratio of 1:1.5. Add a biomodifier and ferment at 30°C for 18 hours, stirring for 12 minutes every 5 hours. Add modified nanocellulose and chitosan, heat to 45°C, mix at 500 rpm, and keep warm while stirring for 25 minutes. The pulp concentration is 14%.

[0034] Step 3: Paper base forming: The pulp is fed into the paper machine, the wire section is formed, the pressure is controlled at 0.4MPa for pressing and dewatering, and the paper is dried in stages (front section 85℃, middle section 95℃, rear section 105℃) for 20 minutes. The moisture content of the paper base layer 1 is 7%.

[0035] Step 4: Coating Lamination: In-machine coating, coating amount 12g / m² 2 Dry at 80℃ for 12 minutes, the coating moisture content is 4%.

[0036] Step 5: Post-processing: Calender at 60℃ and 0.3MPa, with a linear speed of 12m / min, then slit and roll to obtain environmentally friendly eco-paper.

[0037] In this embodiment, the basis weight of the environmentally friendly eco-paper is 100 g / m³. 2 Tensile strength 55 N / m, tear strength 4.8 kN / m 2 It has a folding endurance (longitudinal) of 20 times, a water absorption rate (24h) of 7%, an antibacterial rate of 92% against Escherichia coli and Staphylococcus aureus, and a complete degradation cycle of 75 days, meeting the preset standards for environmentally friendly and ecological packaging paper.

[0038] In a second preferred embodiment of the present invention, the proportion of environmentally friendly eco-paper raw materials is as follows: The paper base layer 1 comprises: 55 parts recycled bamboo pulp, 15 parts sugarcane bagasse fiber, 8 parts banana peel fiber, 10 parts nanocellulose, 6 parts biological modifier (white rot fungus inoculant: laccase = 3:1), 3 parts starch-grafted acrylamide, and 110 parts softened water. The bio-based barrier coating 2 comprises: 18 parts modified lignin, 10 parts PHA, 2.5 parts lemon essential oil, 1.5 parts polyvinyl alcohol, and 45 parts deionized water.

[0039] The method for preparing the environmentally friendly eco-paper in this embodiment is as follows: Step 1: Raw material pretreatment Pretreatment of regenerated plant fibers: Softened water and bio-enzyme deinking agent are added to regenerated bamboo pulp. The deinking process is carried out for 28 minutes at a controlled temperature of 52℃, pH=7.2, and stirring speed of 450r / min, assisted by ultrasonic waves at a frequency of 48KHz. The pulp is then filtered and washed until neutral. After beating, the fiber length is 1.2-2.4mm and the fibrillation rate is 88%. Agricultural waste fiber pretreatment: sugarcane bagasse fiber and banana peel fiber are crushed to 35 mesh, washed 3 times with deionized water, treated with steam pressure of 3.7MPa for 5 minutes, cooled, crushed and screened. Nanocellulose modification: Plasma grafting modification of nanocellulose (diameter 25-45nm, length 250-450nm) (Ar gas pressure 0.1mbar, power 150W, 18min). Coating material pretreatment: Modified lignin and PHA are added to deionized water and polyvinyl alcohol, and dispersed at a controlled temperature of 68℃ and a stirring speed of 750r / min for 38min. Lemon essential oil is added and stirred for 22min. The mixture is then cooled and set aside.

[0040] Step 2: Paper-based pulp preparation: Add softened water to the pretreated raw materials, with a solid-liquid ratio of 1:1.6, add biological modifier, and ferment at 31℃ for 22 hours, stirring for 14 minutes every 4 hours; add modified nanocellulose and starch-grafted acrylamide, mix at 48℃ and 550 r / min, keep warm and stir for 28 minutes, and the pulp concentration is 16%.

[0041] Step 3: Paper base forming: Pressing pressure controlled at 0.5MPa for dehydration, segmented drying (front section 88℃, middle section 98℃, rear section 108℃), drying for 22min, the moisture content of paper base layer 1 is 6%.

[0042] Step 4: Coating Lamination: In-machine coating, coating amount 14g / m² 2 Dry at 85℃ for 13 minutes, the coating moisture content is 3.5%.

[0043] Step 5: Post-processing: Calendering temperature is 65℃, pressure is controlled at 0.35MPa, linear speed is 14m / min, and then slitting and winding.

[0044] In this embodiment, the basis weight of the environmentally friendly eco-paper is 130 g / m³. 2 Tensile strength 62 N / m, tear strength 5.3 kN / m2 It has a folding endurance (longitudinal) of 23 times, a water absorption rate (24h) of 6.5%, an antibacterial rate of 94%, and a complete degradation cycle of 68 days, meeting the preset standards for environmentally friendly and eco-friendly packaging paper.

[0045] 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. An environmentally friendly eco-paper, characterized in that, The eco-paper includes a paper base (1) and a bio-based barrier coating (2) composited on the surface of the paper base (1). The paper base (1) is made of the following raw materials in parts by weight: 40-60 parts of regenerated plant fiber, 20-35 parts of agricultural waste fiber, 5-12 parts of nanocellulose, 3-8 parts of biomodifier, 1-4 parts of environmentally friendly retention aid, and 80-120 parts of softened water. The regenerated plant fiber includes at least one of regenerated wood pulp and regenerated bamboo pulp, and the fiber brooming rate is ≥85% after bio-enzymatic deinking treatment; The agricultural waste fiber is a compound of at least two kinds of agricultural straw and fruit shell fiber, which is pretreated by steam explosion. The nanocellulose is modified by plasma grafting, and the biomodifier is a compound formed by combining white rot fungus inoculant and laccase, with a mass ratio of 2:1-3:

1. The bio-based barrier coating (2) is made from the following raw materials in parts by weight: 10-20 parts modified lignin, 5-12 parts polyhydroxy fatty acid ester (PHA), 1-3 parts plant essential oil, 0.5-2 parts water-based dispersant, and 30-50 parts deionized water. The modified lignin is subjected to aldehyde-assisted separation treatment, and the plant essential oil is a natural antibacterial essential oil.

2. A method for preparing environmentally friendly eco-paper as described in claim 1, characterized in that, Step 1: Raw material pretreatment, bio-enzyme deinking treatment of regenerated plant fiber, steam explosion pretreatment of agricultural waste fiber; plasma grafting modification treatment of nanocellulose, and preparation of bio-based barrier coating (2) slurry. Step 2: Preparation of paper-based pulp. The pretreated recycled plant fibers and agricultural waste fibers are mixed with a biomodifier and fermented for modification. Modified nanocellulose and environmentally friendly retention aids are then added and mixed to obtain paper-based pulp. Step 3: Paper base forming. The paper base pulp is formed by wire forming, pressing and dewatering, and drying in sections to obtain the paper base layer (1). Step 4: Coating composite, the bio-based barrier coating (2) slurry is coated onto the surface of the paper base layer (1) using an in-machine coating process and then dried and cured; Step 5: Post-processing. The coated paper is calendered, slit, and rolled to obtain environmentally friendly eco-paper.

3. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, The agricultural waste fiber is selected from at least two of sugarcane bagasse fiber, wheat straw fiber, and banana peel fiber; the environmentally friendly retention aid is selected from at least one of chitosan and starch-grafted acrylamide; and the aqueous dispersant is selected from at least one of polyethylene glycol and polyvinyl alcohol.

4. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, The nanocellulose has a diameter of 20-50 nm and a length of 100-500 nm; the plasma grafting modification conditions are Ar pressure of 0.1 mbar, power of 150 W, and processing time of 10-20 min; the bio-based barrier coating (2) has a thickness of 5-15 μm and a contact angle of >115°.

5. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, Step 1 specifically includes: Step 1.1: Pretreatment of regenerated plant fiber: Add the regenerated plant fiber to softened water, add bio-enzyme deinking agent, control the temperature at 45-55℃, pH value at 6.5-7.5, stirring speed at 300-500r / min, deinking for 20-30min, while using ultrasonic-assisted deinking at an ultrasonic frequency of 40-50KHz, then filter, wash until neutral, pulp and control the fiber length at 0.8-2.5mm, fiber fibrillation rate ≥85%, to obtain pretreated regenerated plant fiber; Step 1.2: Agricultural waste fiber pretreatment: crush agricultural waste fiber to 20-40 mesh, wash with deionized water 2-3 times, steam explosion treatment, steam pressure 3.2-3.8MPa, treatment time 3-6min, cool and crush and screen to obtain pretreated agricultural waste fiber; Step 1.3: Nanocellulose modification: Nanocellulose is added to deionized water and dispersed evenly. It is then subjected to plasma grafting modification treatment. The modification conditions are Ar gas pressure 0.1 mbar, power 150W, and treatment time 10-20 min to obtain modified nanocellulose. Step 1.4: Pretreatment of coating raw materials: Add modified lignin and polyhydroxy fatty acid ester to deionized water, add water-based dispersant, control the temperature at 60-70℃, stir at 600-800r / min, disperse for 30-40min, add plant essential oil and continue stirring for 15-25min, cool to room temperature, and obtain bio-based barrier coating (2) slurry.

6. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, In step 2, pretreated regenerated plant fibers and pretreated agricultural waste fibers are added to softened water, with a solid-liquid ratio of 1:1.2-1:1.

8. A biomodifier is added, and the temperature is controlled at 28-32℃. Fermentation modification is carried out for 12-24 hours, with stirring for 10-15 minutes every 4-6 hours. Modified nanocellulose and environmentally friendly retention aid are added, and the temperature is raised to 40-50℃. The mixture is stirred evenly at 400-600 r / min and kept warm for 20-30 minutes to obtain paper-based pulp.

7. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, In step 3, the paper base pulp is fed into the paper machine, formed on the wire section, pressed and dewatered, and dried in stages. The pressing pressure is 0.3-0.6MPa, the drying temperature is 80-110℃, and the drying time is 15-25min. The moisture content of the paper base (1) is controlled to be ≤8%, and the paper base (1) is obtained. In the segmented drying process, the temperature of the first section of the drying section is 80-90℃, the temperature of the middle section of the drying section is 90-100℃, and the temperature of the last section of the drying section is 100-110℃.

8. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, In step 4, an in-machine coating process is used to coat the bio-based barrier coating (2) slurry onto at least one side of the paper base layer (1), with a coating amount of 8-15 g / m². 2 Control the drying temperature to 70-90℃, the drying time to 10-15 minutes, and control the coating moisture content to ≤5%.

9. The method for preparing environmentally friendly ecological paper according to claim 2, characterized in that, In step 5, the coated paper is calendered at a temperature of 50-70℃, a pressure of 0.2-0.4MPa, and a linear speed of 10-15m / min. After calendering and winding, environmentally friendly eco-paper is obtained after passing inspection.

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