A readily degradable transparent paper and a method for producing the same

Abstract

The application provides a kind of easily degradable transparent paper and its preparation method, utilize selective wood pulp, cotton pulp, sugarcane pulp and regenerated fiber as raw material, after beating machine, mill machine processing, prepare small fiber, then adopt wet type fiber forming technology and copy out low gram weight paper, and prepare through impregnation, light curing, high temperature calendaring process, have the advantages such as easily degradable, low cost, high transparency, good mechanical properties and hydrophobic performance, and almost no VOC emission in the preparation process, also need not consume a large amount of water resources, raw material and low production cost.The application of low-cost easily degradable high-transparency paper can replace ordinary plastic film used in various types of outer packaging to a great extent, reduce white pollution, achieve environmental protection and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of novel environmentally friendly materials technology, and in particular to a biodegradable transparent paper and its preparation method. Background Technology

[0002] With rapid social and economic development, various plastic products have been widely used due to their lightweight, convenience, and low price, permeating all aspects of human life. Statistics show that global annual consumption of plastic products surged from approximately 2 million tons in 1950 to over 300 million tons in 2015. Of these consumed plastic products, 50% are used for single-use packaging and consumer goods; this portion is quickly discarded and ultimately ends up in the ocean in large quantities. In response, organizations such as the United Nations and the European Union, as well as governments worldwide, have successively introduced a series of policies to restrict or prohibit the production and use of certain plastic products in order to mitigate their environmental pollution.

[0003] In the packaging industry, plastic film is widely used for the outer packaging of food, pharmaceuticals, daily chemicals, and electronic products due to its advantages such as light weight, low price, high transparency, heat and cold resistance, and good sealing properties. These outer packaging plastic films are mainly made of materials such as BOPP and PET. Statistics show that my country's annual consumption of BOPP film exceeds 3 million tons. However, these plastic films are not easily degradable, and most of them are ultimately disposed of through stockpiling or incineration, causing secondary pollution to the environment.

[0004] At the same time, some biodegradable packaging film materials also have certain problems: (1) PLA film: PLA is derived from biomass and can be completely degraded. However, the light transmittance of PLA film is low, generally only about 80%, which cannot be compared with the light transmittance of PET film of more than 90%. In addition, the mechanical properties of PLA film are poor, the impact resistance and tear resistance are weak, and the service life is short. At the same time, the price of PLA film is also high, which is 2-4 times higher than that of ordinary plastic films such as PET and BOPP, and there is cost pressure for large-scale replacement applications. (2) Cellophane: Cellophane can be rapidly degraded in the natural environment, but its preparation process requires a large amount of strong acid and strong alkali, and at the same time, it will produce toxic hydrogen sulfide gas emissions, causing serious pollution to the environment. In addition, the price of cellophane is high, about 3-6 times that of ordinary plastic film, which limits its large-scale replacement applications. Moreover, the above two materials themselves do not have hydrophobic properties and cannot meet the needs of some oil-proof and moisture-proof packaging.

[0005] Furthermore, as disclosed in patent number CN201610954052.1, a method for preparing easily degradable and preservative-resistant food packaging paper, the method involves using palm leaves as raw material. After alkali washing and acid soaking, the leaves are bleached to obtain bleached mixed fibers. Montmorillonite and silica are then mixed and modified with castor oil under the action of microorganisms to obtain a UV absorber. Finally, the two are mixed with other raw materials, pulped, and paper-made to obtain easily degradable and preservative-resistant food packaging paper. Palm fiber is used as the papermaking matrix, modified with cranberry juice rich in antioxidants to increase the fiber's antioxidant effect. Utilizing the UV-shielding properties of montmorillonite and the UV-absorbing properties of silica, the two are mixed and modified with castor oil rich in hydrophobic ester groups to increase the hydrophobicity of the mixture. Finally, the hydrophobic mixture and antioxidant fibers are compounded to produce packaging paper. Although the material is naturally degradable, it is difficult to achieve widespread replacement of ordinary plastic film in terms of both price and performance.

[0006] In view of this, there is an urgent need to develop a new type of biodegradable packaging film material that combines excellent properties such as easy degradation, low cost, high transparency, good mechanical properties and hydrophobic properties. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention provides a biodegradable transparent paper and its preparation method, which can solve the problems of performance defects and high price of existing biodegradable packaging film materials, and can fundamentally solve environmental problems such as white pollution, which has important practical significance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing easily degradable transparent paper, characterized by comprising the following steps:

[0010] S1. Select wood pulp, cotton pulp, sugarcane pulp and recycled fiber as raw materials, process them through a pulping machine and a refining machine to prepare fine fibers, and then use wet fiber forming technology to produce low-grammage paper with fluffy fibers, good moisture absorption and a grammage of 15-40 g / m2. The low-grammage paper is then dried and wound into shape.

[0011] S2. Low-grammage paper at the unwinding point is conveyed into the impregnation station by the feed roller at a speed of 6-12m / min. The light-curable impregnation liquid in the impregnation tank is fully absorbed by the satellite pressure roller. After impregnation, PET film is used for single-sided roll-to-roll lamination at the last satellite roller. Then, the upper and lower limit pressure rollers squeeze out excess impregnation liquid while controlling the thickness of the impregnated paper to 15-40 micrometers to form single-sided laminated paper.

[0012] S3. The single-sided coated paper is conveyed to the photocuring station at a conveying speed of 6-12m / min for curing. After curing, the single-sided PET film is peeled off to form transparent paper. The peeled single-sided PET film is then rolled up and recycled. After cleaning and drying, it can be reused.

[0013] S4. The cured transparent paper is conveyed to a high-temperature calendering device, and after multiple high-temperature rolling processes, the transparent paper is trimmed and cut. After passing the inspection, it is rolled up to obtain easily degradable transparent paper.

[0014] Preferably, in the method for preparing the biodegradable transparent paper, the step S1 of preparing fine fibers after processing with a pulper and refiner specifically includes:

[0015] S11. Soak the raw materials in a certain amount of water and disperse the fibers using a high-speed descaling machine;

[0016] S12. Adjust the slurry concentration to 2-5%, and send it into the slurry tank of the pulping machine through the slurry supply pump. Pulping at a speed of 1500-2000 rpm for 10-30 minutes, then discharge the pulped slurry.

[0017] S13. Adjust the concentration of the pulp after beating to 0.5-3% and feed it into a disc refiner. Use a cooling water temperature control system to grind the pulp in a temperature range of 20-25℃, with a rotation speed of 2000-4000 rpm and a grinding time of 2 hours per cycle. The resulting fiber suspension is circulated and ground multiple times according to the fiber size requirements.

[0018] S14. The finely ground cellulose suspension is uniformly dispersed in a high-shear homogenizer at a speed of 6000-10000 rpm for 10-40 minutes. Polyvinyl alcohol is added as a dispersant and wet strength agent at a concentration of 0.05-0.5%; or polyurethane is added as a wet strength agent at a concentration of 0.5-2%.

[0019] Preferably, in the method for preparing the biodegradable transparent paper, the wet fiber forming technology used in step S1 for papermaking, drying, and winding specifically includes:

[0020] S15. Dilute the pulp with water to a concentration of 0.1-2%, and use a pulp supply pump to deliver the pulp to the head box of the paper machine to ensure smooth pulp flow and avoid sedimentation and accumulation;

[0021] S16. The slurry is evenly dispersed in the head box and quantitatively and continuously supplied to the screen surface by the slurry feeder, wherein the screen mesh number is above 80 mesh and the screen speed is 10-50m / min;

[0022] S17. After the paper wire is wiped and cut, it is wet-pressed by multiple press rollers, and excess water is quickly removed by the vacuum section. The pressing pressure is set to 500-2000 kPa to maintain the loose structure of the paper.

[0023] S18. The wet paper wire is sent into an oven consisting of multiple sets of heating drying cylinders for hot air drying, and the moisture content is controlled within the range of 5-12%. After trimming, it is wound up.

[0024] Preferably, in the method for preparing the biodegradable transparent paper, the preparation method of the photocurable impregnation liquid in step S2 is as follows: First, photopolymerizable monomers are mixed in a certain proportion; then, additives such as photoinitiators, crosslinking agents, surfactants, inorganic fillers, and natural polymer fillers are added and stirred evenly; finally, the mixed liquid is transported to a high-speed centrifugal degasser for degassing.

[0025] The photopolymerizable monomer is one or more of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, isooctyl acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polydipentaerythritol hexaacrylate, allyl cellulose, polyethylene glycol diacrylate, ethylene glycol methacrylate, and polycaprolactone acrylate.

[0026] The photoinitiator is one or more of phenylphosphine dioxide, 2-hydroxy-2-methylphenylacetone, benzoyl peroxide, and diphenylphosphine oxide, with an addition amount of 0.1-3% by mass; the crosslinking agent is one or more of tripropylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate, with an addition amount of 0-2% by mass.

[0027] The surfactant is one or more of sorbitol, cetyl alcohol, polyethylene glycol laurate, polydimethylsiloxane, and polyether-modified silicone oil, and the amount added is 0-2% by mass.

[0028] The inorganic filler is one or more of silica nanoparticles, alumina nanoparticles, zinc dioxide, and montmorillonite nanosheets, and the amount added is 0-2% by mass.

[0029] Preferably, in the method for preparing the biodegradable transparent paper, the photopolymerizable monomer has a low viscosity, good wettability to paper fibers, high photocuring efficiency, and good hydrophobicity after curing.

[0030] Preferably, in the method for preparing the biodegradable transparent paper, the photopolymerizable monomer is a composite of soft and hard monomers, and the mixing ratio is adjusted according to the type and performance requirements of the monomers to meet the requirements of the transparent paper's strength, flexibility, and mechanical strength.

[0031] Preferably, in the method for preparing the biodegradable transparent paper, in step S2, an impregnation liquid recovery device is provided below the limiting pressure roller, and the liquid is recycled back into the impregnation tank after filtration.

[0032] Preferably, in the method for preparing the biodegradable transparent paper, the photocuring station in step S3 is a transparent quartz roller, which is equipped with a curing light source with a matching wavelength. The uncoated side of the single-sided coated paper is tightly attached to the quartz roller after impregnation, so as to achieve oxygen-free curing conditions while ensuring the flatness of the paper surface.

[0033] Preferably, in the method for preparing the biodegradable transparent paper, the satellite pressure roller in step S2 consists of a main roller and multiple satellite rollers, which is used to prevent the paper from breaking due to excessive tension after being wetted; the unwinding point is equipped with a non-stop roll changing device and multiple guide rollers for adjusting tension and offset.

[0034] A biodegradable transparent paper, wherein it is prepared by the above-described preparation method.

[0035] Compared to existing technologies, this invention provides a biodegradable transparent paper and its preparation method. Using wood pulp, cotton pulp, sugarcane pulp, and recycled fibers as raw materials, the paper is processed through a pulper and refiner to produce fine fibers. These fibers are then formed using wet fiber forming technology to create low-grammage paper, which is then processed through impregnation, photocuring, and high-temperature calendering. This paper offers advantages such as easy degradation, low cost, high transparency, good mechanical properties, and hydrophobicity. Furthermore, the preparation process involves almost no VOC emissions and requires minimal water consumption, resulting in low raw material and production costs. The application of this low-cost, biodegradable, highly transparent paper can largely replace ordinary plastic films currently used in various types of outer packaging, reducing white pollution and achieving environmental protection and sustainable development. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0037] Figure 1 A flowchart illustrating the preparation method of the biodegradable transparent paper provided by this invention.

[0038] Figure 2 This is a schematic diagram of the structure of the satellite pressure roller in a preferred embodiment of the method for preparing easily degradable transparent paper provided by the present invention.

[0039] Figure 3 This is a schematic diagram of the mechanical structure of the impregnation process in a preferred embodiment of the method for preparing easily degradable transparent paper provided by the present invention.

[0040] Figure 4 This is a schematic diagram of the mechanical structure of the photocuring process in a preferred embodiment of the method for preparing easily degradable transparent paper provided by the present invention.

[0041] Explanation of reference numerals in the attached diagram:

[0042] 10. Main roller; 20. Satellite roller; 30. Paper; 40. Photocurable impregnation solution; 50. PET film; 60. Pressure roller; 70. Impregnation solution recovery device; 80. Transparent quartz roller; 81. Curing light source tube; 90. Single-sided PET film peeling device. Detailed Implementation

[0043] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0045] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may have other meanings besides indicating orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0046] Furthermore, the terms “first” and “second” as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another. When used herein, the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having” specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof.

[0047] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0048] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0049] With the rapid development of society and the economy, plastic products have been widely used in various fields due to their lightweight, convenience, and low price. However, the large-scale use of plastic products has also brought serious environmental problems. Especially in the packaging industry, plastic films such as BOPP and PET are widely used for the outer packaging of food, pharmaceuticals, daily chemicals, and electronic products due to their excellent properties. These plastic films are not easily degraded, and after being discarded, they are often disposed of through stockpiling or incineration, causing secondary pollution to the environment.

[0050] Faced with this problem, researchers began searching for biodegradable alternatives. However, existing biodegradable packaging materials such as PLA film and cellophane also have some limitations. While PLA film is completely biodegradable, it has low light transmittance, poor mechanical properties, and is expensive. Cellophane, although it can degrade rapidly in natural environments, its manufacturing process pollutes the environment and is also costly. Furthermore, these materials suffer from insufficient hydrophobicity, making them unsuitable for certain specialized packaging needs.

[0051] Against this backdrop, developing a novel packaging material that combines easy degradation, low cost, high transparency, good mechanical properties, and hydrophobicity has become particularly important. This application proposes an innovative method for preparing easily degradable transparent paper, aiming to solve the aforementioned problems.

[0052] The core idea of ​​this application is to utilize natural fiber raw materials and a special processing technique to produce highly transparent paper. The key to this method lies in how to improve the paper's transparency and mechanical properties while maintaining its biodegradability. To this end, this application employs a series of innovative technical means.

[0053] First, this application selects readily biodegradable natural fibers such as wood pulp, cotton pulp, sugarcane pulp, and recycled fibers as raw materials. These raw materials have good biodegradability, which can effectively solve the problem of the difficulty in degrading traditional plastic films. However, how to improve the transparency of paper made from these natural fibers is a technical challenge.

[0054] To address this issue, this application employs a special fiber processing technique. The raw material fibers are processed into fine fibers using a pulper and refiner. During this process, the fibers are fully dispersed and refined, which helps improve the transparency of the final paper. Simultaneously, the use of wet fiber-forming technology to produce low-basis-weight paper further increases the paper's transparency.

[0055] In the paper manufacturing process, this application innovatively introduces a photocurable impregnation solution treatment step. The purpose of this step is to further improve the transparency and mechanical properties of the paper. The use of the photocurable impregnation solution not only fills the gaps between fibers and reduces light scattering, but also forms a network structure after photocuring, enhancing the mechanical properties of the paper.

[0056] To ensure the uniformity and controllability of the impregnation process, this application employs satellite-type pressure roller technology. This technology allows the paper to fully absorb the impregnation solution while preventing paper breakage due to excessive tension. Furthermore, by controlling the single-sided lamination of the PET film and the upper and lower limit pressure rollers, the thickness of the paper after impregnation can be precisely controlled, ensuring consistent product quality.

[0057] In the photocuring process, this application employs a precisely controlled curing technique. By controlling the conveyor speed and light intensity, the impregnating liquid can be fully cured to form a stable network structure. This process not only improves the paper's transparency but also enhances its mechanical properties.

[0058] Finally, this application further improves the paper's transparency and smoothness through high-temperature calendering. Multiple high-temperature rolling processes not only make the paper surface smoother but also further reduce the gaps between fibers, thus increasing transparency.

[0059] A key advantage of this preparation method is its cost-effectiveness. Compared to traditional plastic films or other biodegradable materials, the raw materials and processes used in this application are relatively simple, which helps reduce production costs. Furthermore, the recycling of PET film further reduces costs.

[0060] In summary, such as Figure 1 As shown, the present invention provides a method for preparing easily degradable transparent paper, comprising the following steps:

[0061] S1. Select wood pulp, cotton pulp, sugarcane pulp and recycled fiber as raw materials, process them through a pulping machine and a refining machine to prepare fine fibers, and then use wet fiber forming technology to produce low-grammage paper with fluffy fibers, good moisture absorption and a grammage of 15-40 g / m2. The low-grammage paper is then dried and wound into shape.

[0062] S2. Low-grammage paper at the unwinding point is conveyed into the impregnation station by the feed roller at a speed of 6-12m / min. The light-curable impregnation liquid in the impregnation tank is fully absorbed by the satellite pressure roller. After impregnation, PET film is used for single-sided roll-to-roll lamination at the last satellite roller. Then, the upper and lower limit pressure rollers squeeze out excess impregnation liquid while controlling the thickness of the impregnated paper to 15-40 micrometers to form single-sided laminated paper.

[0063] S3. The single-sided coated paper is conveyed to the photocuring station at a conveying speed of 6-12m / min for curing. After curing, the single-sided PET film is peeled off to form transparent paper. The peeled single-sided PET film is then rolled up and recycled. After cleaning and drying, it can be reused.

[0064] S4. The cured transparent paper is conveyed to a high-temperature calendering device, and after multiple high-temperature rolling processes, the transparent paper is trimmed and cut. After passing the inspection, it is rolled up to obtain easily degradable transparent paper.

[0065] The method described in this application not only solves the problem of the difficulty in degrading traditional plastic films, but also overcomes the deficiency of insufficient transparency in existing biodegradable materials. Through a special fiber treatment process and the use of a photocurable impregnating solution, this application successfully prepared biodegradable paper with high transparency.

[0066] In its implementation, this application overcame several technical challenges. The first challenge was improving the transparency of paper made from natural fibers. By refining the fibers, using low-basis-weight papermaking, and employing a photocurable impregnating solution, this application successfully improved the paper's transparency. The second challenge was maintaining the paper's mechanical properties while improving transparency. Through the network structure of the photocurable impregnating solution and high-temperature calendering, this application successfully enhanced the paper's mechanical properties.

[0067] Compared with existing technologies, the method of this application has significant advantages. Compared with traditional plastic films, the transparent paper prepared by this application has good biodegradability. Compared with PLA film, the product of this application has higher transparency and better mechanical properties. Compared with cellophane, the preparation process of this application is more environmentally friendly and has lower costs.

[0068] The method described in this application also offers good flexibility and adjustability. For example, the properties of the final product can be altered by adjusting the type and proportion of raw materials. Wood pulp can provide good strength, cotton pulp can increase flexibility, sugarcane pulp can improve transparency, and the use of recycled fibers can further reduce costs and improve environmental friendliness.

[0069] During fiber processing, the fineness and dispersion of fibers can be controlled by adjusting pulping and refining parameters, thereby affecting the transparency and strength of the final paper. For example, finer fibers can be obtained by extending the refining time or increasing the refining intensity, thus improving transparency.

[0070] During the impregnation process, the properties of the final product can be altered by adjusting the formulation of the photocurable impregnation solution. For example, increasing the proportion of crosslinking agents can improve the strength and water resistance of the paper, or adding specific functional monomers can impart special properties to the paper, such as antibacterial or oil-resistant properties.

[0071] The method described in this application can also be adjusted to meet different application requirements. For example, for applications requiring higher transparency, the amount of impregnating liquid can be increased or the photocuring time can be extended. For applications requiring better mechanical properties, this can be achieved by adjusting the parameters of the high-temperature calendering process.

[0072] The technical advantages of this application are mainly reflected in the following aspects:

[0073] First, the transparent paper prepared in this application has excellent biodegradability. Because it uses natural fibers as raw materials, this transparent paper can degrade rapidly in the natural environment, greatly reducing environmental pollution.

[0074] Secondly, the transparent paper prepared in this application has high transparency. Through a special fiber treatment process and the use of a photocurable impregnating solution, this application successfully improves the transparency of the paper, achieving a level comparable to that of traditional plastic films.

[0075] Third, the transparent paper prepared in this application has good mechanical properties. Through the network structure formed by the photocurable impregnating liquid and the high-temperature calendering treatment, the transparent paper prepared in this application has good strength and toughness, which can meet the needs of various packaging applications.

[0076] Fourth, the preparation method of this application has good cost-effectiveness. Compared with other biodegradable materials, the raw materials and processes used in this application are relatively simple, which can effectively reduce production costs.

[0077] Fifth, the method of this application has good environmental protection properties. Not only is the final product biodegradable, but the entire preparation process is also more environmentally friendly, avoiding the pollution problems in the traditional plastic film production process.

[0078] Sixth, the method of this application has good adjustability. By adjusting the raw material ratio, process parameters, and impregnation solution formulation, the performance of the final product can be flexibly adjusted to meet the needs of different applications.

[0079] The following nine specific examples illustrate this:

[0080] Example A

[0081] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to the disc refiner at 3000 rpm. The pulp is ground at 25°C for 2 hours. The pulp is diluted with water. The pulp is diluted to a concentration of 0.5% and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a basis weight of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0082] (2) Impregnation process: Low-grammage paper, after tension and offset adjustments by a non-stop roll changing device and multiple guide rollers, is conveyed into the impregnation station by the feed rollers at a speed of 10 m / min. Figure 2 and Figure 3 As shown, the photocurable impregnation liquid 40 in the impregnation tank is fully absorbed by the satellite pressure rollers (a main roller 10 with a diameter of 2m above the paper 30 and seven satellite rollers 20 with a diameter of 20cm below). After impregnation, a 50-micron PET film 50 (the side in contact with the paper is a release layer) is used at the last satellite roller for single-sided roll-to-roll lamination. Then, the excess impregnation liquid squeezed out by the pressure rollers 60 with upper and lower limits of 80 mm passes through the impregnation liquid recovery device 70 set below, and is recycled back into the impregnation tank for reuse after filtration.

[0083] The preparation method of the photocurable impregnation solution is as follows:

[0084] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0085] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0086] (3) Photocuring process:

[0087] like Figure 4 As shown, the impregnated single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller 80 with an internal curing light source tube 81 (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off by a single-sided PET film peeling device 90 and then wound up and recycled. After cleaning and drying, it can be reused.

[0088] (4) Post-processing and winding process:

[0089] The cured transparent paper is fed to a high-temperature calendering machine 100. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0090] Example B

[0091] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to the disc refiner at 3000 rpm. The pulp is ground at 25°C for 2 hours. The pulp is diluted with water. The pulp is diluted to a concentration of 0.5% and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a basis weight of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0092] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0093] The preparation method of the photocurable impregnation solution is as follows:

[0094] Photopolymerizable monomers hydroxyethyl acrylate and dipropylene glycol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0095] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0096] (3) Photocuring process:

[0097] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0098] (4) Post-processing and winding process:

[0099] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0100] Example C

[0101] (1) Papermaking process: Select 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp as raw materials. Soak the pulp board in a certain amount of water and disperse the fibers through a high-speed desiccant. Adjust the pulp concentration to 3% and send it into the pulp tank of the beater through a pulp supply pump. Beat the pulp at 2000 rpm for 30 minutes and then discharge the beaten pulp. Adjust the pulp concentration to 1% and send it to the disc refiner at 3000 rpm. Grind the pulp at 25°C for 2 hours as one cycle, and grind for 5 cycles. The pulp is diluted with water to a concentration of 0.5%, and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a rate of 20 g / m² by a pulp feeder. The wire mesh is 500 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, with the moisture content controlled at 8%. After trimming, it is wound up.

[0102] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0103] The preparation method of the photocurable impregnation solution is as follows:

[0104] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0105] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0106] (3) Photocuring process:

[0107] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0108] (4) Post-processing and winding process:

[0109] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0110] Example D

[0111] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed desiccant. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 30 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to a disc refiner at 3000 rpm. The pulp is ground at 25°C for 10 cycles of 2 hours each. The finely ground cellulose suspension is uniformly dispersed in a high-shear homogenizer, where the pulp is transferred... After dispersing for 30 minutes at a speed of 10,000 rpm, add 0.2% polyvinyl alcohol. Dilute the pulp with water to a concentration of 0.5%, and use a pulp pump to deliver the pulp to the headbox of the paper machine. After the pulp is evenly dispersed in the headbox, it is continuously supplied to the wire surface at a basis weight of 20 g / m2 by a pulp feeder. The wire surface has a mesh count of 8,000 mesh and a wire speed of 40 m / min. After the paper wire is wiped and cut, it is wet-pressed by press rollers at a pressing pressure of 1000 kPa, and excess water is removed by a vacuum section. Then, the pressed wet paper wire is sent to an oven consisting of multiple sets of heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0112] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0113] The preparation method of the photocurable impregnation solution is as follows:

[0114] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0115] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0116] (3) Photocuring process:

[0117] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0118] (4) Post-processing and winding process:

[0119] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0120] Example E

[0121] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to the disc refiner at 3000 rpm. The pulp is ground at 25°C for 2 hours. The pulp is diluted with water. The pulp is diluted to a concentration of 0.5% and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a basis weight of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0122] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0123] The preparation method of the photocurable impregnation solution is as follows:

[0124] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed in a mass ratio of 2:1, and then 1 wt% of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and 2 wt% of trimethylolpropane triacrylate are added and stirred until homogeneous.

[0125] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0126] (3) Photocuring process:

[0127] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0128] (4) Post-processing and winding process:

[0129] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0130] Example F

[0131] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to the disc refiner at 3000 rpm. The pulp is ground at 25°C for 2 hours. The pulp is diluted with water. The pulp is diluted to a concentration of 0.5% and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a basis weight of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0132] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0133] The preparation method of the photocurable impregnation solution is as follows:

[0134] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed in a mass ratio of 2:1, and then 1 wt% of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and 0.5 wt% of polydimethylsiloxane are added and stirred until homogeneous.

[0135] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0136] (3) Photocuring process:

[0137] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0138] (4) Post-processing and winding process:

[0139] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0140] Example G

[0141] (1) Papermaking process: 50% recycled fiber pulp, 30% softwood fiber pulp, and 20% sugarcane pulp are selected as raw materials. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to the disc refiner at 3000 rpm. The pulp is ground at 25°C for 2 hours. The pulp is diluted with water. The pulp is diluted to a concentration of 0.5% and then pumped to the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a basis weight of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content at 8%. After trimming, it is wound up.

[0142] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0143] The preparation method of the photocurable impregnation solution is as follows:

[0144] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed in a mass ratio of 2:1, and then 1 wt% of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and 0.5 wt% of silica nanoparticles are added and stirred until homogeneous.

[0145] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0146] (3) Photocuring process:

[0147] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0148] (4) Post-processing and winding process:

[0149] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0150] Example H

[0151] (1) Papermaking process: 100% softwood fiber pulp is selected as raw material. The pulp board is soaked in a certain amount of water and the fibers are dispersed by a high-speed de-fiber machine. The pulp concentration is adjusted to 3% and sent to the pulp tank of the beater by a pulp pump. After beating at 2000 rpm for 10 minutes, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1% and sent to a disc refiner at 3000 rpm. The pulp is then ground at 25°C for 2 hours. The pulp is diluted with water to a concentration of 0.5%. The pulp is pumped into the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a rate of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content to 8%. After trimming, it is wound up.

[0152] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0153] The preparation method of the photocurable impregnation solution is as follows:

[0154] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0155] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0156] (3) Photocuring process:

[0157] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0158] (4) Post-processing and winding process:

[0159] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0160] Example I

[0161] (1) Papermaking process: 100% sugarcane pulp is selected as raw material. The pulp board is soaked in a certain amount of water, and the fibers are dispersed by a high-speed desiccant. The pulp concentration is adjusted to 3%, and the pulp is pumped into the pulp tank of the beater. After beating for 10 minutes at 2000 rpm, the beaten pulp is discharged. The pulp concentration after beating is adjusted to 1%, and the pulp is sent to a disc refiner at 3000 rpm. The pulp is then ground at 25°C for 2 hours. The pulp is diluted with water to a concentration of 0.5%. The pulp is pumped into the headbox of the paper machine. After being evenly dispersed in the headbox, the pulp is continuously supplied to the wire at a rate of 20 g / m² by a pulp feeder. The wire mesh is 100 mesh and the wire speed is 40 m / min. After the wire is wiped and cut, it is wet-pressed by press rollers at a pressure of 1000 kPa, and excess water is removed by a vacuum section. The pressed wet wire is then sent to an oven consisting of multiple heated drying cylinders for hot air drying, controlling the moisture content to 8%. After trimming, it is wound up.

[0162] (2) Impregnation process: Low-grammage paper, after tension and offset adjustment by multiple guide rollers, is conveyed into the impregnation station by the feed roller at a conveying speed of 10m / min through the non-stop roll changing device. The paper is fully absorbed by the light-curable impregnation liquid in the impregnation tank by the satellite pressure rollers (the main roller with a diameter of 2m is above the paper, and there are 7 satellite rollers with a diameter of 20cm below). After impregnation, a 50-micron PET film (the side in contact with the paper is the release layer) is used at the last satellite roller for single-sided roll-to-roll film covering. Then, the excess impregnation liquid squeezed out by the pressure roller with upper and lower limits of 80 mm is filtered and recycled back into the impregnation tank for reuse.

[0163] The preparation method of the photocurable impregnation solution is as follows:

[0164] Photopolymerizable monomers isooctyl acrylate and 1,6-hexanediol diacrylate are mixed at a mass ratio of 2:1, and 1 wt% phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred until homogeneous.

[0165] The mixed liquid is then transported to a high-speed centrifugal degasser for degassing.

[0166] (3) Photocuring process:

[0167] After impregnation, the single-sided coated paper is conveyed to the photocuring station at a conveying speed of 10m / min. It passes through a transparent quartz roller with an internal curing light source (the quartz roller presses the upper surface of the paper, which is equivalent to oxygen-free curing). After curing, the single-sided PET film is peeled off and the paper is wound up and recycled. After cleaning and drying, it can be reused.

[0168] (4) Post-processing and winding process:

[0169] The cured transparent paper is conveyed to a high-temperature calendering device. After five high-temperature roller presses, the transparent paper roll is trimmed and cut. Then, it is inspected online to check the paper's thickness uniformity, transparency uniformity, moisture content, etc. If the inspection is qualified, it is rolled up. If the inspection is unqualified, the machine automatically cuts and rewinds it.

[0170] The biodegradable transparent paper prepared according to the nine AI embodiments described above was tested, and the following data were obtained (see Tables 1, 2, and 3):

[0171]

[0172]

[0173] Table 1. Tensile strength of the transparent paper prepared by AI in Example 1

[0174] transparency(%) Haze (%) Example A 89.38 23.58 Example B 88.91 22.64 Example C 91.71 8.71 Example D 92.78 2.17 Example E 88.43 22.98 Example F 87.09 24.33 Example G 90.02 17.63 Example H 90.12 31.18 Example I 85.69 22.05

[0175] Table 2. Transparency and haze of the transparent paper prepared by AI in the examples.

[0176]

[0177]

[0178] Table 3. Transparency and haze of the transparent paper prepared by AI in Example 3

[0179] Weight loss (%) PET transparent film 0.9 (virtually no degradation) base paper Complete degradation Transparent paper 60.0

[0180] Table 4 shows the weight loss of PET transparent film, base paper prepared in Example B, and transparent paper after 83 days of degradation in the natural environment, buried at a depth of 10 cm in soil.

[0181] As can be seen from the test data above, the product obtained by this invention has advantages such as easy degradation, high transparency, and good mechanical properties.

[0182] This application's fiber preparation method successfully solves the technical problem of how to prepare fine fibers for the production of biodegradable transparent paper through multiple precisely controlled steps. By employing high-speed pulping, precisely controlled beating and refining processes, and a final high-shear homogenization treatment, this application can obtain fine fibers with uniform size and good dispersibility. These fibers are key raw materials for preparing high-transparency, biodegradable paper.

[0183] The innovations of this application are as follows: First, a multi-step fiber processing procedure is employed, with each step specifically addressing different aspects of fiber dispersion and refinement. Second, precise parameter control is used in each step, such as slurry concentration, processing temperature, rotation speed, and time, ensuring the controllability and repeatability of the processing. Finally, the introduction of high-shear homogenizers and dispersants further improves the uniformity of fiber dispersion.

[0184] The main advantages of this method include: it can produce finer and more uniform fibers, thereby significantly improving the transparency of the final paper; it avoids high temperatures and strong chemical treatments during the process, maintaining the biodegradability of the fibers; it can be adapted to different raw materials and application requirements through flexible adjustment of parameters; and the equipment and raw materials used in the whole process are relatively simple, which helps to reduce production costs.

[0185] In summary, this application provides an efficient, controllable, and flexible fiber preparation method, laying the foundation for the production of high-performance, easily degradable transparent paper. It is expected to find wide applications in packaging, printing, and other fields, and offers new possibilities for solving the problem of plastic pollution.

[0186] In the preparation of biodegradable transparent paper, the preparation of the photocurable impregnating solution is a crucial step. Traditional impregnating solution formulations often suffer from problems such as poor photocuring effect, poor compatibility with fibers, and inability to impart the desired properties to the paper. To address these issues, this application proposes an innovative method for preparing a photocurable impregnating solution.

[0187] The technical solution of this application successfully solves the problem of improving the transparency and mechanical properties of biodegradable transparent paper by adding a specific crosslinking agent to the photocurable impregnation solution. The crosslinking agent forms chemical crosslinks between fibers, reducing interfiber voids, increasing light transmittance, and simultaneously strengthening the overall structure of the paper, thus improving its mechanical properties. By controlling the type and amount of crosslinking agent added, the performance of the final product can be flexibly adjusted to meet the needs of different applications.

[0188] The main advantages of this method are: First, it significantly improves transparency and mechanical properties while maintaining the paper's biodegradability. Second, performance can be precisely controlled by selecting different combinations of crosslinking agents. Third, because the amount of crosslinking agent added is small, it does not significantly increase production costs, maintaining good cost-effectiveness. Finally, this method can be seamlessly integrated with existing production processes, facilitating practical application.

[0189] In summary, the method for preparing easily degradable transparent paper proposed in this application not only solves key problems in existing technologies but also provides new ideas for developing high-performance, environmentally friendly packaging materials. The application of this method is expected to drive the packaging industry towards a more environmentally friendly and sustainable direction, making a significant contribution to solving the problem of plastic pollution.

[0190] In the biodegradable transparent paper preparation method of this application, the formulation of the photocurable impregnating solution plays a crucial role in the performance of the final product. To further optimize the performance of the impregnating solution, this application innovatively introduces a surfactant as an additive. The addition of surfactants can significantly improve the performance of the impregnating solution, thereby enhancing the quality of the transparent paper.

[0191] This application selects sorbitol, cetyl alcohol, polyethylene glycol laurate, polydimethylsiloxane, and polyether-modified silicone oil as optional surfactants. These surfactants each have their own characteristics and can be selected and combined according to specific needs. Nonionic surfactants such as sorbitol, cetyl alcohol, and polyethylene glycol laurate can effectively reduce the surface tension of the impregnation solution, improving its wettability and penetration into the paper. This helps the impregnation solution to be more evenly distributed on the surface and inside of the paper, thereby improving the transparency and uniformity of the final product. Silicon-based surfactants such as polydimethylsiloxane and polyether-modified silicone oil can impart certain hydrophobic properties to transparent paper, which is very valuable for some special packaging applications.

[0192] This application controls the amount of surfactant added within the range of 0-2% by mass. This range was chosen after careful consideration. Adding an appropriate amount of surfactant can significantly improve the performance of the impregnation solution, but excessive addition may affect other properties of the impregnation solution or lead to increased costs. By controlling the addition amount within the range of 0-2%, the impregnation effect can be effectively optimized without significantly affecting other properties of the impregnation solution.

[0193] The addition of surfactants not only improves the performance of the impregnation solution but also indirectly enhances the quality of the transparency paper. By reducing the surface tension of the impregnation solution, surfactants can promote deeper penetration into the fiber network, thereby more effectively filling the gaps between fibers. This not only improves the transparency of the final product but also enhances the mechanical properties of the paper. Furthermore, some surfactants can form a thin film on the paper surface, further improving the gloss and smoothness of the transparency paper.

[0194] In practical applications, one or more surfactants can be selected based on specific needs. For example, for applications requiring high transparency, nonionic surfactants such as sorbitol or polyethylene glycol laurate can be chosen. These surfactants can significantly reduce the surface tension of the impregnation solution, promoting a more uniform distribution of the impregnation solution within the paper, thereby improving transparency. For applications requiring a certain degree of hydrophobicity, silicone-based surfactants such as polydimethylsiloxane or polyether-modified silicone oil can be selected. These surfactants can form a hydrophobic film on the paper surface, improving the water resistance of transparent paper.

[0195] The amount of surfactant added can also be adjusted according to specific needs. For example, for applications requiring higher transparency, the amount of surfactant added can be increased appropriately, but not exceeding 2%. For general applications, the amount added can be controlled within the range of 0.5-1%, which can effectively improve the performance of the impregnation solution while controlling costs.

[0196] This application also discovered that different types of surfactants can produce synergistic effects. For example, the simultaneous addition of nonionic surfactants and silicone-based surfactants can improve the wettability and penetration of the impregnation solution while also imparting certain hydrophobic properties to the transparent paper. This combination can meet a wider range of application needs.

[0197] In the preparation of biodegradable transparent paper, the impregnation step is crucial for improving the paper's transparency and mechanical properties. However, traditional impregnation methods often face several technical challenges. First, once the paper is wetted, its strength decreases significantly, making it prone to breakage due to excessive tension. Second, maintaining stable paper tension and preventing misalignment during continuous production is also a significant issue. These problems not only affect product quality but may also lead to reduced production efficiency.

[0198] To address these issues, this application proposes an improved impregnation method. Specifically, in step S2, a satellite-type pressure roller structure consisting of a main roller and multiple satellite rollers is employed, such as... Figure 2 As shown. The core idea of ​​this design is to reduce the risk of excessive tension on the paper at a single point by distributing the stress points. The main roller 10 serves as the center, with multiple satellite rollers 20 distributed around it, forming a uniformly stressed system. When the paper 30 passes through this system, the tension is distributed to multiple contact points, greatly reducing the possibility of paper breakage.

[0199] Furthermore, this application also incorporates a non-stop roll changing device at the unwinding point, equipped with multiple guide rollers. The introduction of the non-stop roll changing device solves the problem of requiring machine downtime during traditional roll changing processes, significantly improving production continuity and efficiency. The multiple guide rollers enable precise adjustment of paper tension and position. By adjusting the position and tension of the guide rollers, the paper's transport path can be corrected in real time, effectively preventing deviation problems.

[0200] The combined application of these technical features not only solves the problem of paper easily breaking after being wetted, but also improves the stability and efficiency of the production process. The satellite roll structure can be designed according to actual needs; for example, the number and distribution of satellite rolls 20 can be adjusted to accommodate paper of different thicknesses and strengths. The non-stop roll changing device can take various forms, such as a flying shear type or a double-arm type, to adapt to different production line layouts. The multi-guide roll system can be automatically adjusted through motor control, further improving production accuracy and efficiency.

[0201] In practical applications, the implementation of these technical features has proven highly effective. For example... Figure 2 As shown, in one embodiment, a satellite-type pressure roll structure consisting of one main roll 10 and seven satellite rolls 20 is employed. The main roll has a diameter of 2m, and the satellite rolls have a diameter of 20cm. This configuration ensures uniform stress on the paper during impregnation, preventing breakage even when the paper's moisture content reaches 60%. Simultaneously, the non-stop roll changing device employs a double-arm design, coupled with four adjustable guide rolls, enabling continuous 24-hour uninterrupted production and improving production efficiency.

[0202] The technical solution presented in this application excels in addressing issues such as paper's susceptibility to breakage, unstable tension, and misalignment after wetting. The satellite roller structure effectively prevents paper breakage due to excessive localized tension while wetted by distributing the stress points. The main roller, acting as the central support point, provides stability to the entire system, while multiple satellite rollers ensure sufficient contact between the paper and the impregnation solution, while uniformly distributing tension. This design is particularly suitable for processing paper whose strength decreases after wetting, minimizing the risk of breakage while maintaining effective impregnation.

[0203] The introduction of a non-stop roll changing device solves the problem of machine downtime required during traditional roll changing, significantly improving production continuity. This not only increases production efficiency but also reduces paper quality fluctuations that may occur due to machine restarts after shutdowns. In continuous production, paper tension and position control are crucial. The multi-guide roller system provides strong support for this control. By adjusting the position and tension of the guide rollers, the paper's transport path can be corrected in real time, effectively avoiding misalignment. This precise control not only ensures consistent product quality but also reduces waste that may result from paper misalignment.

[0204] In practice, the satellite roll system works as follows: the paper first contacts the main roll and then passes through each satellite roll in sequence. Each satellite roll applies a certain pressure to the paper, but because the pressure is distributed, the pressure at a single point is greatly reduced. This design allows the paper to be fully impregnated in the impregnation solution while avoiding breakage caused by excessive local tension. The non-stop roll changing device achieves seamless connection between the almost-used roll and the new roll through precise timing control. During the roll changing process, the multi-guide roll system plays a crucial role, ensuring the stability of paper tension and position through real-time adjustments.

[0205] In summary, the technical solution proposed in this application effectively solves key technical problems in the preparation of biodegradable transparent paper by innovatively combining satellite pressure rollers, non-stop roll changing devices, and a multi-guide roller system. This method not only improves production efficiency and product quality but also enhances the stability and controllability of the entire production process. Through these improvements, this application provides reliable technical support for the large-scale production of biodegradable transparent paper and makes a significant contribution to the development of environmentally friendly packaging materials.

[0206] In summary, the biodegradable transparent paper and its preparation method provided by this invention utilize wood pulp, cotton pulp, sugarcane pulp, and recycled fibers as raw materials. These materials are processed using a pulper and refiner to produce fine fibers, which are then formed into low-grammage paper using wet fiber forming technology. The paper is then processed through impregnation, photocuring, and high-temperature calendering. It possesses advantages such as easy degradation, low cost, high transparency, good mechanical properties, and hydrophobicity. Furthermore, the preparation process involves almost no VOC emissions and requires minimal water consumption, resulting in low raw material and production costs. The application of this low-cost, biodegradable, highly transparent paper can largely replace ordinary plastic films currently used in various types of outer packaging, reducing white pollution and achieving environmental protection and sustainable development.

[0207] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the scope of protection of the present invention.

Claims

1. A method for preparing easily degradable transparent paper, characterized in that, Includes the following steps: S1. Using a mixture of wood pulp, sugarcane pulp, and regenerated fiber as raw materials, fine fibers are prepared after processing with a pulping machine and a refiner. These fibers are then produced using wet fiber forming technology, resulting in fluffy fibers with good moisture absorption and a basis weight of 15-40 g / m². 2 Low-grammage paper, and the low-grammage paper is dried and wound into shape; S2. Low-grammage paper at the unwinding point is conveyed into the impregnation station by the feed roller at a speed of 6-12 m / min. The light-curable impregnation liquid in the impregnation tank is fully absorbed by the satellite pressure roller. After impregnation, PET film is used for single-sided roll-to-roll lamination at the last satellite roller. Then, the upper and lower limit pressure rollers squeeze out excess impregnation liquid while controlling the thickness of the impregnated paper to 15-40 micrometers to form single-sided laminated paper. S3. The single-sided coated paper is conveyed to the photocuring station at a conveying speed of 6-12 m / min for curing. After curing, the single-sided PET film is peeled off to form transparent paper. The peeled single-sided PET film is then rolled up, cleaned, dried, and reused. S4. The cured transparent paper is conveyed to a high-temperature calendering equipment. After multiple high-temperature rolling processes, the transparent paper is trimmed and cut. After passing the inspection, it is rolled up to obtain easily degradable transparent paper. Specifically, step S1, which involves processing the pulper and refiner to produce fine fibers, includes: S11. Soak the raw materials in a certain amount of water and disperse the fibers using a high-speed descaling machine; S12. Adjust the slurry concentration to 2-5%, and send it into the slurry tank of the pulping machine through the slurry supply pump. Pulping at a speed of 1500-2000 rpm for 10-30 minutes, then discharge the pulped slurry. S13. Adjust the pulp concentration after beating to 0.5-3% and feed it into a disc refiner. Use a cooling water temperature control system to grind the pulp in a temperature range of 20-25°C. The rotation speed is 2000-4000 rpm and the grinding time is 2 hours per cycle. The resulting fiber suspension is circulated and ground multiple times according to the fiber size requirements. S14. The finely ground cellulose suspension is uniformly dispersed in a high-shear homogenizer at a speed of 6000-10000 rpm for 10-40 minutes. Polyvinyl alcohol is added as a dispersant and wet strength agent at a concentration of 0.05-0.5%. The wet fiber forming technology papermaking, drying, and winding process in step S1 specifically includes: S15. Dilute the pulp with water to a concentration of 0.1-2%, and use a pulp supply pump to deliver the pulp to the head box of the paper machine to ensure smooth pulp flow and avoid sedimentation and accumulation. S16. The slurry is evenly dispersed in the head box and quantitatively and continuously supplied to the screen surface by the slurry feeder, wherein the screen mesh number is above 80 mesh and the screen speed is 10-50 m / min; S17. After the paper wire is wiped and cut, it is wet-pressed by multiple press rollers, and excess water is quickly removed by the vacuum section. The pressing pressure is set to 500-2000 kPa to maintain the loose structure of the paper. S18. The wet paper wire is sent into an oven consisting of multiple sets of heated drying cylinders for hot air drying, and the moisture content is controlled within the range of 5-12%. After trimming the edges, it is wound up. The preparation method of the photocurable impregnation liquid in step S2 is as follows: First, the photopolymerizable monomers are mixed in a certain proportion; then, photoinitiator, crosslinking agent, surfactant, inorganic filler, and natural polymer filler additive are added and stirred evenly; finally, the mixed liquid is transported to a high-speed centrifugal degasser for degassing. The photopolymerizable monomer is one or more of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, isooctyl acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polydipentaerythritol hexaacrylate, allyl cellulose, polyethylene glycol diacrylate, ethylene glycol methacrylate, and polycaprolactone acrylate. The photoinitiator is one or more of phenylphosphine dioxide, 2-hydroxy-2-methylphenylacetone, benzoyl peroxide, and diphenylphosphine oxide, with an addition amount of 0.1-3% by mass; the crosslinking agent is one or more of tripropylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate, with an addition amount of 0-2% by mass. The surfactant is one or more of cetyl alcohol, polyethylene glycol laurate, polydimethylsiloxane, and polyether-modified silicone oil, and the amount added is 0-2% by mass. The inorganic filler is one or more of silica nanoparticles, alumina nanoparticles, zinc dioxide, and montmorillonite nanosheets, and the amount added is 0-2% by mass.

2. The method for preparing easily degradable transparent paper according to claim 1, characterized in that, The photopolymerizable monomer is a composite of soft and hard monomers, and the mixing ratio is adjusted according to the type and performance requirements of the monomers to meet the requirements of the transparent paper's strength, flexibility, and mechanical strength.

3. The method for preparing easily degradable transparent paper according to claim 1, characterized in that, In step S2, an impregnation liquid recovery device is installed below the limiting pressure roller. After filtration, the liquid is recycled back into the impregnation tank for reuse.

4. The method for preparing easily degradable transparent paper according to claim 1, characterized in that, The light curing station in step S3 is a transparent quartz roller, which is equipped with a curing light source with a matching wavelength. The uncoated side of the single-sided coated paper is tightly attached to the quartz roller after impregnation, so as to achieve oxygen-free curing conditions while ensuring the flatness of the paper surface.

5. The method for preparing easily degradable transparent paper according to claim 1, characterized in that, The satellite pressure roller in step S2 consists of a main roller and multiple satellite rollers, which is used to prevent the paper from breaking due to excessive tension after it is wetted; the unwinding point is equipped with a non-stop roll changing device and multiple guide rollers for adjusting tension and offset.

6. A biodegradable transparent paper, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 5.

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