Preparation method of environment-friendly degradable single-sided see-through sticker

Abstract

The application discloses a preparation method of an environment-friendly degradable single-side perspective sticker and belongs to the technical field of modified nanometer materials. The method comprises the following steps: (1) preparation of a multilayer composite structure: mixing polylactic acid and polybutylene succinate, adding nano-montmorillonite and a surface modifier to melt blend to form a first layer melt; stirring polybutylene adipate terephthalate and fluorescent carbon nanodots to form a second layer melt; and forming a film blank by co-extruding the first layer, a pressure-sensitive adhesive layer and the second layer; (2) construction of a nanometer film: biaxially stretching the film blank, pressing a micropore array, immersing in a silver nanoparticle suspension and drying to obtain a nanometer film; (3) functionalization treatment of a coating layer: immersing in a fluorine-containing nanometer coating solution and solidifying; and (4) post-treatment: secondary solidification. The obtained single-side perspective sticker is suitable for fields such as building and vehicle privacy films, and solves the problems of large pollution and slow degradation of traditional stickers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of modified nanomaterials, and in particular relates to a preparation method of an environmentally friendly degradable single-sided perspective sticker. BACKGROUND

[0002] Under the background of increasing environmental protection awareness today, the field of material science, especially the modification technology of polymer materials and nanomaterials, has made significant progress. Traditional film materials, such as single-sided perspective stickers (also known as one-way perspective films or privacy films) used for windows, vehicles or buildings, mainly rely on petroleum-based plastics such as polyethylene (PE), polyvinyl chloride (PVC) or polyester (PET), which provide perspective function while causing serious environmental pollution problems. According to relevant research, more than 300 million tons of plastic waste is generated globally each year, of which a considerable proportion is non-degradable plastic film, causing long-term damage to soil and marine ecosystems. Therefore, the research of environmentally friendly degradable materials has become a hot spot, especially the application of biodegradable polymers such as polylactic acid (PLA), polybutylene succinate (PBS) and polybutylene adipate terephthalate (PBAT), which are derived from renewable resources and can be degraded into water and carbon dioxide in the natural environment.

[0003] The core function of single-sided perspective stickers is to achieve one-way visual effect, i.e. external scenery can be seen from one side, while the other side presents a mirror or opaque effect. This function is usually achieved through optical structure design, such as micro-hole array, nano-particle coating or fluorescent material enhanced contrast. As early as the 1990s, researchers began to explore the use of metal oxide thin films to manufacture one-way perspective glass, but these materials often have poor durability and are not environmentally friendly. In the 21st century, with the rise of nanotechnology, modified nanomaterials were introduced into the preparation of stickers, such as nano-montmorillonite (a layered silicate mineral) as a filler to enhance the mechanical properties and barrier properties of polymers. Polylactic acid (PLA) as a typical biodegradable polymer is made from renewable resources such as corn starch, with a weight average molecular weight generally in the range of 120000-180000 g / mol, and has good biocompatibility and degradability. The brittleness and low toughness of pure PLA limit its application in flexible stickers, so it is often blended with other polymers.

[0004] In the preparation of single-sided see-through stickers, multi-layer composite structures of these biodegradable polymers have become a trend. However, in the prior art, the light transmittance and one-way see-through effect of these composites are often insufficient, and functional additives such as fluorescent materials need to be introduced, which can emit fluorescence, enhance the contrast and visibility of the sticker, but the dispersibility and stability of the existing method still need to be optimized. But the existing single-sided see-through stickers still have many problems. First, the environmental protection is insufficient: many stickers claim to be degradable, but the actual degradation rate is slow, and it takes months or even years in the soil, and the degradation products may release microplastics. For example, traditional PLA-based stickers are prone to hydrolysis in a humid environment, resulting in a sharp decline in mechanical properties. Second, the optical performance is unstable: the one-way see-through effect is greatly affected by the light angle and the environment, and the fluorescent additives are easily quenched. Third, the preparation process is complex: the multi-layer co-extrusion and nano-structuring process has high energy consumption and strict equipment requirements, such as the difficulty of parameter optimization of a twin-screw extruder, resulting in low yield and high cost. In practical applications, these problems manifest themselves in the form of sticker peeling, see-through effect decay, or environmental pollution during use. For example, car privacy stickers often lose their one-way function after 1-2 years of use, requiring frequent replacement and increasing waste. Building see-through stickers face the problem of ultraviolet degradation, resulting in color fading and optical failure. SUMMARY

[0005] To solve the problems of insufficient environmental protection (such as slow degradation rate and release of microplastics), unstable optical performance (such as see-through effect greatly affected by light and fluorescent additives easily quenched), and complex preparation process (such as high energy consumption of multi-layer co-extrusion and strict equipment requirements) in the prior art, the present invention uses the following technical solutions.

[0006] The application discloses a preparation method of an environment-friendly degradable single-sided perspective sticker, comprising the following steps: (1) preparing a multi-layer composite structure: first, mixing polylactic acid with a mass fraction of 40-60 parts and polybutylene succinate with a mass fraction of 20-30 parts, adding nano-montmorillonite with a mass fraction of 10-20 parts and a surface modifier with a mass fraction of 5-10 parts, and carrying out melt blending to form a first layer melt with a thickness of 100-200 microns; then, stirring polybutylene succinate terephthalate (CAS number: 55231-08-8) with a mass fraction of 15-25 parts and fluorescent carbon nanodots with a mass fraction of 8-15 parts to form a second layer melt with a thickness of 50-100 microns; finally, carrying out co-extrusion treatment on the first layer melt, a pressure-sensitive adhesive layer with a thickness of 100-200 microns and a mass fraction of 3-8 parts and the second layer melt in sequence to form a multi-layer composite structure film blank; (2) constructing a nano film: carrying out biaxial stretching on the film blank obtained in the step (1) to form a preliminary film; then, adopting stamping treatment to construct a micropore array; adding silver nanoparticle suspension with a mass fraction of 4-10 parts to carry out immersion treatment, and obtaining a nano film after drying; (3) carrying out functionalization treatment on a coating layer: immersing the nano film obtained in the step (2) in fluorine-containing nano coating solution with a mass fraction of 6-12 parts for soaking treatment, and then carrying out solidification treatment to obtain the nano film after coating treatment; and (4) post-treatment: carrying out secondary solidification treatment on the nano film obtained in the step (3).

[0007] Preferably, the weight average molecular weight of the polylactic acid in the step (1) is 120000-180000 g / mol, and the CAS number is 26100-51-6; the weight average molecular weight of the polybutylene succinate in the step (1) is 90000-140000 g / mol, and the CAS number is 25777-14-4; the layer thickness of the nano-montmorillonite in the step (1) is 1-5 nm, the interlayer spacing is 2-4 nm, and the CAS number is 1318-93-0; and the surface modifier in the step (1) is 3-aminopropyltriethoxysilane (CAS number: 919-30-2), gamma-methacryloxypropyltrimethoxysilane (CAS number: 2530-85-0), isopropyl titanate (CAS number: 546-68-9) or allyl glycidyl ether (CAS number: 106-92-3).

[0008] Preferably, the equipment for melt blending in step (1) is a twin-screw extruder; the parameters for melt blending in step (1) are as follows: screw length-diameter ratio (42-48): 1, temperature 170-210℃, rotation speed 350-450r / min, time 25-35min; the weight average molecular weight of polybutylene adipate terephthalate in step (1) is 130000-170000g / mol; the particle size of fluorescent carbon nanodots in step (1) is 3-8nm; the parameters for stirring treatment in step (1) are as follows: stirring at 150-190℃ for 15-25min.

[0009] Preferably, the preparation method of fluorescent carbon nanodots in step (1) is as follows: citric acid powder (CAS number 77-92-9), polyethyleneimine (CAS number 9002-98-6), guanidine hydrochloride (CAS number 50-01-1), silicic acid (CAS number 1343-98-2) and deionized water are mixed according to the mass ratio (10-20):(5-15):(2-4):(5-8):(100-150), and placed in a microwave reaction treatment, wherein the power is 500-800W, the temperature is 160-200℃, and the time is 10-20min; after the reaction is completed, it is naturally cooled to room temperature to obtain a primary product; then 0.1-0.3 times the mass of the primary product of tannic acid (CAS number 1401-55-4) is added, and sealed reaction is carried out at 120-160℃ for 4-8h to obtain a secondary product; finally, 2-5 times the mass of the secondary product of ethanol is added for precipitation, and centrifugation is carried out at 8000-12000r / min for 15-25min to obtain the final product.

[0010] Preferably, the parameters for co-extrusion treatment in step (1) are as follows: extrusion temperature 190-230℃, pressure 1-3MPa; the preparation method of the pressure-sensitive adhesive layer in step (1) is as follows: polyurethane emulsion (CAS number 9009-54-5) with mass percentage 35-45% and weight average molecular weight 60000-90000g / mol is mixed with chitosan (CAS number 9012-76-4) powder with molecular weight 120000-180000g / mol according to the mass ratio 7:3, the mixing rotation speed is 400-600r / min, and the mixing time is 40-50min; then the pH is adjusted to 5-6; then, 0.5-1 times the mass of the chitosan powder of glycerol sodium phosphate (CAS number 1555-56-2) and 0.1-0.5 parts of the chitosan powder of polyoxyethylene ether (CAS number 9002-93-1) are added, and treatment is carried out under ice bath conditions at a rotation speed of 1000-1500r / min for 20-25min; the product is obtained by coating process, wherein the coating solidification temperature is 70-90℃, and the solidification time is 1.5-2h.

[0011] Preferably, the parameters of biaxial stretching in step (2) are as follows: temperature 70-90℃, transverse and longitudinal stretching ratio 2.5-3.5 times; the parameters of embossing treatment in step (2) are as follows: nano-cone array with a period of 100-200nm and a depth of 80-120nm is embossed on one side surface of the film blank, while laser drilling is performed on the other side of the film blank, wherein the aperture is 0.8-1.5mm and the aperture ratio is 25-35%.

[0012] The parameters of embossing treatment in step (2) are as follows: nano-imprinting technology is used to construct an array structure of nano-cones with a period of 100-200nm and a depth of 80-120nm on one side surface (usually the outer surface facing the brighter side of light) of the film blank, and the height-width ratio of the cone of the nano-cone is 0.8; specifically, a hot embossing or UV embossing device (such as a roller type nano-imprinting machine, and the mold material is a silicon-based or nickel-based template) is used, the embossing temperature is controlled at 60-80℃ (to ensure the softening of the polymer without degradation), the pressure is 0.5-2MPa, and the embossing time is 5-15s / cycle; at the same time, laser drilling is performed on the other side (the inner surface facing the darker side of light) of the film blank, wherein the aperture is 0.8-1.5mm and the aperture ratio is 25-35%; CO2 laser or fiber laser (wavelength 1064nm, power 10-50W) is used for laser drilling with a pulse frequency of 20-50kHz and a scanning speed of 500-1000mm / s to form a uniformly distributed micro-hole array, avoiding thermal damage.

[0013] Preferably, the parameters of immersion treatment in step (2) are as follows: the particle size of the silver nanoparticle suspension is 15-40nm, the mass concentration is 0.3-0.8wt%, the immersion time is 10-20min, and the immersion temperature is 50-70℃; the thickness of the nano-film in step (2) is controlled at 100-140μm.

[0014] Preferably, the parameters of the fluorine-containing nano-coating solution in step (3) are as follows: the solvent is ethanol, the solute is perfluoroalkylsilane, and the mass ratio between the solvent and the solute is 19:1. The perfluoroalkylsilane is heptadecafluorodecyltrimethoxysilane (CAS No. 83048-65-1), perfluorododecyltrichlorosilane (CAS No. 149213-65-0), or perfluorooctylethyltrichlorosilane (CAS No. 78560-44-8); the parameters of immersion treatment in step (3) are as follows: temperature 45-65℃, time 8-20min.

[0015] Preferably, the parameters of curing treatment in step (3) are as follows: vacuum degree 0.02-0.08MPa, temperature 90-110℃, time 15-25min.

[0016] Preferably, the parameters of the secondary curing treatment in step (4) are as follows: temperature 110-130°C, pressure 0.8-1.5 MPa, time 36-48 h under a nitrogen atmosphere.

[0017] Compared with the prior art, the present application has the following advantages: through the synergistic design of material formula, multi-layer structure and preparation process, the environmental protection, optical performance and durability are comprehensively improved, and the mechanism is as follows: excellent environmental protection and degradable performance, realizing the whole life cycle green, the base material of the present application selects biodegradable polymers such as polylactic acid (PLA), polybutylene succinate (PBS) and polybutylene adipate terephthalate (PBAT). These materials are derived from renewable resources (such as corn starch), and can be finally decomposed into carbon dioxide and water by microorganisms in the natural environment (soil, compost), which fundamentally solves the "white pollution" problem caused by traditional PVC and PET film. Further, even the pressure sensitive adhesive layer also innovatively uses polyurethane emulsion and degradable chitosan, ensuring the degradability of the whole product (including the adhesive layer). The preparation process is mainly melt blending and co-extrusion, which significantly reduces the use of volatile organic compounds (VOC), so that the VOC emission of the final product is extremely low, meeting the strict indoor air quality standard. Excellent optical performance and stable one-way perspective effect, the core mechanism of one-way perspective is derived from the optical structure of "micropore array + high reflection coating". Structure basis: through laser drilling to construct a micrometer level hole array (opening rate 25-35%), combined with double-sided embossed nano cone array, a unique optical surface is formed. From the side with less light (such as indoor), the human eye can observe the external scene through the micropores; while from the side with more light (such as outdoor), the human eye mainly receives the light reflected by the silver nanoparticle coating, showing a mirror effect, thereby realizing one-way perspective. Effect enhancement: the innovation of the present application lies in the introduction of fluorescent carbon nanodots. These carbon dots are coated in the second melt (facing the dark side), which can absorb part of the stray light (including ultraviolet light) in the environment and emit visible fluorescence. This not only enhances the visual contrast and clarity of the dark side, but also further increases the perception of the difference in light intensity between indoor and outdoor, so that even on cloudy days or dusk with weak light contrast, the stable one-way perspective effect can be maintained, solving the pain point that the traditional perspective film fails under certain lighting conditions. Excellent mechanical properties and long-term durability, substrate enhancement: by blending high rigidity polylactic acid (PLA) with high toughness polybutylene succinate (PBS), and introducing nano-montmorillonite treated by surface modifier (such as silane coupling agent), synergistic reinforcement is realized. The modified nano-montmorillonite can be uniformly dispersed in the polymer matrix in the form of lamellar, forming a strong physical crosslinking network, effectively inhibiting crack propagation, thereby significantly improving the tensile strength and toughness of the composite film, overcoming the defect of brittle pure PLA. Surface protection: the final fluorine-containing nano coating forms a dense, low surface energy protective layer on the surface of the film. Its superhydrophobic and oleophobic properties (similar to lotus effect) make the film have excellent self-cleaning ability and are not easy to adhere dust and stains.At the same time, the coating can effectively resist ultraviolet radiation, acid rain erosion and physical scratching, delay material aging, yellowing and optical performance attenuation, and make the service life of the film far exceed that of traditional products. Stable structure: secondary curing treatment is carried out at a specific temperature and pressure, which can fully release the internal stress generated by the material during stretching and embossing, and make the interface between the layers more firm, ensuring the size stability of the film during long-term use, and preventing the film from curling, bubbling or peeling. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a transmission electron microscope image of the fluorescent carbon nanodots prepared in Example 1.

[0019] Figure 2 is an emission spectrum diagram of the fluorescent carbon nanodots prepared in Example 1; wherein line 1 is an emission spectrum diagram excited by an ultraviolet lamp for 30 minutes, and line 2 is an emission spectrum diagram excited by an ultraviolet lamp for 120 minutes. DETAILED DESCRIPTION

[0020] The present application will be described in detail below through specific examples, but the purpose and purpose of these exemplary embodiments are only used to exemplify the present application, and do not constitute any form of any limitation on the actual protection scope of the present application, nor limit the protection scope of the present application. For the range of parameters not mentioned, the intermediate value is selected. At the same time, for the mass percentage or weight percentage not explicitly stated or mentioned, it generally refers to the final concentration after addition. In addition, in the present application, the unit of mass fraction is kilogram (Kg). It should be noted that the degradable mentioned in the present application does not mean that all components achieve 100% degree of degradation effect.

[0021] Example 1

[0022] Preparation of the multi-layer composite structure: first, 50 parts by mass of polylactic acid (weight average molecular weight 150000 g / mol) and 25 parts by mass of polybutylene succinate (weight average molecular weight 115000 g / mol) were mixed, 15 parts by mass of nano-montmorillonite (layer thickness 3 nm, interlayer spacing 3 nm) and 7.5 parts by mass of a surface modifier (γ-methacryloxypropyltrimethoxysilane) were added and melt blended, a twin-screw extruder was used, the screw length-diameter ratio was 45:1, the temperature was 190℃, the rotation speed was 400 r / min, the time was 30 min, and a first layer melt with a thickness of 150 μm was formed; then 20 parts by mass of polybutylene terephthalate adipate (weight average molecular weight 150000 g / mol) and 11.5 parts by mass of fluorescent carbon nanodots (particle size 5.5 nm) were stirred, the parameters were 170℃ stirring for 20 min, and a second layer melt with a thickness of 75 μm was formed; the preparation method of the fluorescent carbon nanodots was as follows: citric acid powder, polyethyleneimine, guanidine hydrochloride, silicic acid and deionized water were mixed in a mass ratio of 15:10:3:6.5:125, placed in a microwave reaction, the power was 650 W, the temperature was 180℃, and the time was 15 min, after the reaction was completed, it was naturally cooled to room temperature to obtain a primary product, then 0.2 times the mass of the primary product of tannic acid was added and sealed for reaction at 140℃ for 6 h to obtain a secondary product, finally 3.5 times the mass of the secondary product of ethanol was added for precipitation, centrifuged at 10000 r / min for 20 min to obtain the final product, the transmission electron microscopy (TEM) image of the fluorescent carbon nanodots is shown in Figure 1 , and the fluorescence spectrum is shown in Figure 2 ; finally, the first layer melt, 5.5 parts by mass of a pressure-sensitive adhesive layer with a thickness of 150 μm and the second layer melt were sequentially compounded by co-extrusion to form a film blank of a multi-layer composite structure; the extrusion temperature of the co-extrusion was 210℃, and the pressure was 2 MPa; the preparation method of the pressure-sensitive adhesive layer was as follows: 40% by mass of a polyurethane emulsion (weight average molecular weight 75000 g / mol) and chitosan powder (molecular weight 150000 g / mol) were mixed in a mass ratio of 7:3, the mixing rotation speed was 500 r / min, the mixing time was 45 min, then the pH was adjusted to 5.5, then 0.75 times the mass of glycerol sodium phosphate of the chitosan powder and 0.3 times the mass of polyoxyethylene ether of the chitosan powder were added, and the mixture was treated in an ice bath at a rotation speed of 1250 r / min for 22.5 min, and a product was obtained by coating process, in which the coating solidification temperature was 80℃ and the solidification time was 1.75 h.

[0023] Construction of the nanometer film: the obtained film blank is biaxially stretched to form a preliminary film; the biaxial stretching parameters are temperature 80℃, and the horizontal and vertical stretching ratio is 3 times; then micro-hole array is constructed by using imprinting treatment; nanometer cone array with a period of 150nm and a depth of 100nm is imprinted on one side surface of the film blank, and at the same time, laser drilling is performed on the other side of the film blank, wherein the aperture is 1.15mm, and the opening rate is 30%; 7 parts of silver nanoparticle suspension with a particle size of 27.5nm and a mass concentration of 0.55wt% are added for immersion treatment, the immersion time is 15min, and the immersion temperature is 60℃, and after drying, a nanometer film is obtained; the thickness of the nanometer film is controlled to be 120μm.

[0024] Coating functionalization treatment: the obtained nanometer film is immersed in 9 parts of fluorine-containing nanometer coating solution for soaking treatment, the solvent of the fluorine-containing nanometer coating solution is ethanol, and the solute is heptadecafluorodecyltrimethoxysilane; the soaking treatment temperature is 55℃, and the time is 14min, then solidification treatment is carried out, the vacuum degree is 0.05MPa, the temperature is 100℃, and the time is 20min, and the nanometer film after coating treatment is obtained.

[0025] Post-treatment: the obtained nanometer film is subjected to secondary solidification treatment; under nitrogen atmosphere, the temperature is 120℃, the pressure is 1.15MPa, and the time is 42h.

[0026] The obtained environment-friendly degradable single-side perspective sticker has the following physical parameters: the thickness is 120μm, and the single-side perspective effect is good.

[0027] The specific parameters of examples 2-12 and comparative examples 1-16 are listed in the following table. The table is designed according to the progress of each step, and each table reflects the different parameter values of the examples / comparative examples, covering all end point values, intermediate values.

[0028] Table 1: Parameters of the multilayer composite structure

[0029]

[0030] Firstly, the structure of Table 1 is clear and explicit, which contains 7 columns: No. (Examples 1-6), Polylactic acid (g, weight average molecular weight g / mol), Polybutylene succinate (g, weight average molecular weight g / mol), Nano-montmorillonite (g, layer thickness nm, interlayer spacing nm), Surface modifier (g, type), First layer melt thickness (μm), and Melt blending parameters (temperature ℃, rotation speed r / min, time min, screw length-diameter ratio). These columns correspond to the core composition and processing conditions of the first layer melt. Among them, polylactic acid (PLA) and polybutylene succinate (PBS) are used as the main biodegradable polymer matrix to provide the toughness and degradability of the material; nano-montmorillonite is used as a filler to enhance the mechanical properties; the surface modifier improves the dispersibility of the nanomaterial; the melt thickness controls the uniformity of the layer structure; and the melt blending parameters ensure the efficiency and uniformity of the mixing process. The entire table is arranged in rows of examples, showing the gradual design of parameters, which facilitates the comparison and optimization of effects.

[0031] In terms of the role in the entire invention, Table 1 is the core basis for the preparation of the multi-layer composite structure, which directly affects the subsequent steps such as co-extrusion, stretching and coating. The first layer melt serves as a support layer, forming a physical cross-linking network through the lamellar structure of nano-montmorillonite, thereby improving the tensile strength and crack resistance; the surface modifier promotes the uniform dispersion of nanoparticles, prevents agglomeration, and improves the optical transparency and degradation uniformity. The optimization of these parameters ensures the environmental performance (such as degradation rate > 50%) of the final single-sided perspective sticker, the optical effect (such as perspective rate > 90%) and the mechanical durability (such as elongation > 200%). Compared with the comparative examples, the parameter range of Table 1 avoids the performance degradation (such as a 20-30% reduction in strength) caused by the absence of additives or exceeding the range, which reflects the innovation and practicality of the invention. In summary, Table 1 is not only a summary of experimental data, but also a manifestation of the inventors' scientific design to achieve synergistic reinforcement of materials, which lays a solid foundation for subsequent nano-film construction and functionalization, and promotes the progress of environmentally friendly and degradable sticker film technology.

[0032] Table 2: Parameters II of the multi-layer composite structure

[0033]

[0034] Table 2 is consistent with Table 1, containing 7 columns: No. (Comparative Examples 1-8), PLA (g, weight average molecular weight g / mol), PESU (g, weight average molecular weight g / mol), Nano-Montmorillonite (g, layer thickness nm, interlayer spacing nm), Surface modifier (g, type), First layer melt thickness (pm), and Melt blending parameters (temperature °C, rotation speed r / min, time min, screw length-diameter ratio). These columns focus on the variation experiments of the first layer melt, where many parameters are fixed at the benchmark values of Example 1 (e.g., PLA 50 g, 150000 g / mol, etc.) to highlight the impact of changes in a single variable. The design of Table 2 embodies the scientific experimental principle, revealing the synergistic effect of Nano-Montmorillonite, surface modifier and processing parameters through control groups, avoiding blind optimization and ensuring the rationality of the invention parameter range (e.g., PLA 40-60 g, temperature 170-210 °C).

[0035] In terms of parameter deviation rules, Table 2 systematically covers three types: missing (e.g., Comparative Examples 1, 2) directly weakens the enhancement mechanism; replacement (e.g., Comparative Example 3) tests the effect of non-preferred materials; range deviation (e.g., lower / higher than) reveals the importance of boundary conditions. For example, when the polymer molecular weight and addition amount are outside the invention range (e.g., Comparative Examples 4, 8), the balance of toughness and strength is destroyed; processing temperature below the range (e.g., Comparative Example 5) may result in uneven mixing, while excessive addition (e.g., Comparative Examples 6, 7) increases cost and may cause side reactions. These deviations are not random, but are targeted designs for the core elements of the invention, reflecting the rigor of the experiment.

[0036] Table 3: Parameters of multi-layer composite structure

[0037]

[0038] Table 3 is consistent with Table 1 and Table 2, containing 7 columns: No. (Examples 7-12), PLA (g, weight average molecular weight g / mol), PESU (g, weight average molecular weight g / mol), Nano-Montmorillonite (g, layer thickness nm, interlayer spacing nm), Surface modifier (g, type), First layer melt thickness (pm), and Melt blending parameters (temperature °C, rotation speed r / min, time min, screw length-diameter ratio).

[0039] These columns focus on the fine adjustment of the first layer melt, where many parameters are expressed with decimal points (e.g., 52.5 g), reflecting the accuracy and gradient design of the experiment. Compared to the integer values in Table 1, Table 3 places more emphasis on intermediate transition values, which helps to reveal the sensitivity of parameter changes on performance, for example, how small fluctuations in molecular weight affect the toughness and degradation rate of the material.

[0040] From the parameter law, Table 3 demonstrates a fine gradient design: the mass fraction of polylactic acid and polybutylene succinate respectively floats in the range of 42.5-57.5g and 21.25-28.75g, and the weight average molecular weight changes from 127500-172500g / mol and 95000-132500g / mol, respectively. These small adjustments reflect the continuity of parameters, avoiding the integer jumps in Table 1.

[0041] The addition amount of nanometer montmorillonite is 11.25-18.75g, the layer thickness is 1.5-4.5nm, and the interlayer spacing is 2.25-3.75nm, which is maintained within the invention range, ensuring uniform dispersion of the sheet structure. The surface modifier is 5.5-9.25g, with various types (titanate, ether, silane), highlighting the adaptability of different modifiers. The first layer thickness gradually changes from 112.5-187.5μm, matching thickness-sensitive applications.

[0042] The melt blending parameters temperature is 175-205℃, rotation speed is 362.5-437.5r / min, time is 26.25-33.75min, and length-diameter ratio is 42.5-47.5:1, all within the high-efficiency range. These regular changes are not arbitrary, but based on the invention mechanism: the intermediate value optimizes the melt flowability of the polymer and the exfoliation effect of the nanofiller, reducing energy consumption and improving environmental friendliness.

[0043] Table 3 is a deepening embodiment of parameter optimization, directly supporting the functional design of the first layer melt. Through these examples, the flexibility of material ratio is verified: high molecular weight PLA improves rigidity, low temperature rotation speed controls degradation consistency, and modifier diversity adapts to different nanometer montmorillonite specifications. These parameters ensure the smooth progress of subsequent steps (such as co-extrusion and stretching), and contribute to the environmental advantage of the final product.

[0044] Table 4: Parameter four of multi-layer composite structure

[0045]

[0046] Table 4 lists the key material ratios, molecular weights, nano-additive specifications, surface modifier types, melt thicknesses, and melt blending processing parameters for Comparative Examples 9-16 in preparing the first layer melt. This table is a continuation of Table 2 (Comparative Examples 1-8) and contrasts sharply with Table 1 and Table 3 (Examples 1-12), further validating the necessity and boundary conditions of the invention parameters by introducing variations below or beyond the invention range. In the method of preparing the single-side see-through degradable sticker, the first layer melt serves as the base layer of the multi-layer composite structure, and its parameter optimization directly affects the mechanical strength, optical performance, and degradation efficiency of the material. The parameter design in Table 4 focuses on extreme deviation scenarios, such as excessive polymer, excessive temperature, or improper thickness, aiming to reveal potential defects and thus strengthen the superiority of the examples and the robustness of the method. These comparative examples not only highlight the scientificity of the invention range (such as polylactic acid 40-60g, temperature 170-210°C, thickness 100-200μm), but also provide risk warnings for practical applications.

[0047] From the parameter deviation rules, Table 4 systematically expands the deviation types: below the range (such as Comparative Examples 9, 13, 14, 15) may lead to insufficient functions, such as uneven mixing or weakened enhancement; and beyond the range (such as Comparative Examples 10, 11, 12, 16) may cause excess problems, such as accelerated degradation or uneven materials. These rules cover polymer ratios (Comparative Examples 11, 12), additive amounts (Comparative Examples 13, 14), processing parameters (Comparative Examples 9, 10), and structure sizes (Comparative Examples 15, 16), embodying a comprehensive risk assessment. Compared to the deletion and replacement in Table 2, Table 4 focuses more on quantitative boundaries, revealing sensitive intervals of parameters, for example, temperature exceeding 210°C may increase VOC emissions, and thickness below 100μm is prone to tensile fracture.

[0048] Table 5: Parameters of the multi-layer composite structure

[0049]

[0050] Table 5 lists the key material ratios, specifications, thicknesses, and processing parameters for Examples 1-6 and Comparative Examples 1-8 in preparing the second layer melt, pressure-sensitive adhesive layer, and co-extrusion process. This table emphasizes the parameter design of the second layer optical enhancement layer (based on polybutylene adipate terephthalate PBAT and fluorescent carbon nanodots) and the pressure-sensitive adhesive layer. In the method of preparing the single-side see-through degradable sticker, the second layer provides fluorescent effect and optical adjustment, and the co-extrusion step realizes multi-layer compounding, ensuring the single-side see-through property and adhesion of the product. The parameter settings in Table 5 aim to combine with the first layer deviations in the previous tables to evaluate the overall performance impact.

[0051] From the parameter rules, Table 5 demonstrates the gradient design of the embodiments: PBAT mass fraction 15-25 g, weight average molecular weight 130000-170000 g / mol, fluorescent carbon nanodots 8-15 g, particle size 3-8 nm, these ranges ensure the biodegradability and fluorescence stability of the second layer (e.g. particle size 5-6 nm optimizes light scattering). The second layer thickness 50-100 pm gradually changes, matching the optical requirements; the stirring parameters temperature 150-190 °C, time 15-25 min, emphasizing gentle processing to avoid nanodot agglomeration. Pressure-sensitive adhesive layer 3-8 g, thickness 100-200 pm, cooperates with co-extrusion temperature 190-230 °C, pressure 1-3 MPa, achieving low-pressure efficient compounding. The “zero variation” rules of the comparative examples highlight the control principle: when the second layer is fixed, the deviation of the first layer (e.g. the absence or out-of-range of Table 2 and Table 4) will amplify the overall defects, such as reducing the perspective rate or increasing the peeling risk. This design embodies the modularity of the experiment, avoiding multi-variable interference.

[0052] Table 6: Parameter six of multi-layer composite structure

[0053]

[0054] Firstly, the structure of Table 6 is consistent with Table 5, containing 7 columns in total: number (Examples 7-12, Comparative Examples 9-16), polybutylene adipate terephthalate (g, weight average molecular weight g / mol), fluorescent carbon nanodots (g, particle size nm), second layer melt thickness (pm), stirring processing parameters (temperature °C, time min), pressure-sensitive adhesive layer (g, thickness pm), and co-extrusion parameters (temperature °C, pressure MPa). These columns focus on the stirring mixing of the second layer and multi-layer co-extrusion, complementing the first layer parameters of the previous table.

[0055] Table 7: Parameter seven of multi-layer composite structure

[0056]

[0057] The structure of Table 7 is directed at the nanodot synthesis process, containing 7 columns in total: number (Examples 1-6, Comparative Examples 1-8), citric acid powder (g): polyethyleneimine (g): guanidine hydrochloride (g): silicic acid (g): deionized water (g), microwave parameters (power W, temperature °C, time min), tannic acid multiple (times), sealed reaction (temperature °C, time h), ethanol multiple (times), centrifugation (r / min, time min). These columns cover the whole process of raw material mixing, microwave-assisted heating, tannic acid addition (possibly as a stabilizer), sealed reaction, ethanol washing, and centrifugal purification, complementing the second layer parameters of the previous table. It is worth noting that the parameters of Comparative Examples 1-8 are exactly the same, which embodies the modularity of the experimental design: keeping the nanodot synthesis constant to isolate the influence of upstream (first layer) or downstream (co-extrusion) variations.

[0058] From the parameter law, Table 7 demonstrates the gradient design of the embodiment: raw material ratio citric acid 10-20 g, polyethyleneimine 5-15 g, guanidine hydrochloride 2-4 g, silicic acid 5-8 g, deionized water 100-150 g, which ensures the green synthesis and particle size uniformity of the nanodots (3-8 nm corresponding to Table 5 / 6). Microwave parameters power 500-800 W, temperature 160-200 °C, time 10-20 min gradient, emphasizing efficient heating to promote carbonization; tannic acid 0.1-0.3 times as a stabilizing multiple, sealed reaction 120-160 °C, 4-8 h optimizing the cross-linking process. Ethanol washing 2-5 times and centrifugation 8000-12000 r / min, 15-25 min, ensure the purification efficiency.

[0059] Table 8: Parameters eight of multi-layer composite structure

[0060]

[0061] From the parameter law, Table 8 demonstrates the fine gradient design of the embodiment: raw material ratio citric acid 11.25-18.75 g, polyethyleneimine 6.25-13.75 g, etc., decimal changes cover the range in the middle, ensuring the quantum yield and biocompatibility of the nanodots. Microwave parameters 537.5-762.5 W, 165-195 °C, 11.25-18.75 min gradient, optimizing carbonization efficiency; tannic acid 0.125-0.275 times, sealed 125-155 °C, 4.5-7.5 h emphasizing the stabilization process. Ethanol 2.375-4.625 times and centrifugation 8500-11500 r / min, 16.25-23.75 min, ensure purification. The deviation law of the comparative example highlights negative testing: missing / over-standard / insufficient (such as 900 W>800 W upper limit, 10 min<15 min lower limit), simulating synthesis failure scenarios, amplifying defects such as low yield or uneven particle size.

[0062] Table 9: Parameters nine of multi-layer composite structure

[0063]

[0064] Table 10: Parameters ten of multi-layer composite structure

[0065]

[0066] Table 9 and Table 10 collectively detail the key material ratios, mixing conditions, pH adjustment, additive multiples, and processing and coating parameters for Examples 1-12 and Comparative Examples 1-16 in the preparation of the pressure-sensitive adhesive layer or coating layer. The tables mark the transition from the previous tables (Table 7-8, focusing on fluorescent carbon nanodot synthesis) to the adhesive layer or coating process, emphasizing the biocompatible mixture with polyurethane emulsion and chitosan powder as the base material, supplemented with glycerol sodium phosphate and polyoxyethylene ether as stabilizers and surfactants. In the preparation method of the environmentally friendly degradable single-sided see-through patch, this layer provides adhesion and surface protection, directly affecting the interfacial stability and overall degradation performance. The design of Table 9 (Examples 1-6, Comparative Examples 1-8) and Table 10 (Examples 7-12, Comparative Examples 9-16) reflects the inventors' exploration of parameter continuity: Examples use gradient changes (such as polyurethane emulsion 35-45%, molecular weight 60000-90000 g / mol), covering integer and decimal intervals, while Comparative Examples are fixed in Table 9 and introduce deviations (such as below the range, missing) in Table 10 (such as below the range, missing), aiming to combine with the second layer of Table 6 and nanodots of Table 8, to evaluate the impact of adhesive layer deviations on optical and adhesion performance.

[0067] From the parameter law, Table 9 and Table 10 collectively demonstrate the gradient design of Examples: polyurethane emulsion 35-45%, molecular weight 60000-90000 g / mol, chitosan 120000-180000 g / mol, these ranges ensure the flexibility and degradability of the adhesive layer (such as high molecular weight of chitosan improves biocompatibility). Mixing parameters 400-600 r / min, 40-50 min gradient, pH 5-6 optimize acidity; additive multiples glycerol sodium phosphate 0.5-1 times, polyoxyethylene ether 0.1-0.5 times emphasize stability. Processing 1000-1500 r / min, 20-25 min and coating 70-90°C, 1.5-2h, ensure uniform coating. The "zero variation" rule of Table 9 is similar to Table 7, and the deviations of Table 10 (such as 30%<35% lower limit, missing) are similar to Table 8, highlighting negative effects such as low adhesion or instability. This design embodies the continuity from integer gradient (Table 9) to decimal precision and boundary testing (Table 10).

[0068] Table 11: Parameters of nanometer thin film

[0069]

[0070] Table 11 details the key process parameters for Examples 1-12 and Comparative Examples 1-16 in the fabrication of the nanometer film, including biaxial stretching, embossing, laser perforation, silver nanoparticle deposition, and film thickness control. This table marks the transition from the previous tables (Tables 9-10, focusing on the adhesive layer coating) to the nanoscale optical processing, emphasizing film formation based on biaxial stretching, combined with embossing texturing, perforation ventilation, and silver nanoparticle enhanced reflective / fluorescent performance. In the method of making the environmentally degradable single-side see-through sticker, the nanometer film layer provides the single-side light transmission and optical selectivity, directly affecting the see-through efficiency, air permeability, and durability. The examples employ gradient variations (e.g., stretching temperature 70-90°C, stretching ratio 2.5-3.5 times), covering both integer and decimal intervals, while the comparative examples 1-9 are fixed and comparative examples 10-16 introduce deviations (e.g., below / above the range, missing), aiming to combine with the adhesive layer of Table 10 and the nanodots of Table 8, to evaluate the impact of nanofabrication deviations on overall optical and mechanical performance. This not only verifies the rationality of the nanometer film parameter range (e.g., thickness 100-140 μm, silver particle size 15-40 nm), but also highlights the potential reduction in see-through clarity or increase in degradation unevenness if the processing is not optimized.

[0071] Table 12: Parameters for coating functionalization processing

[0072]

[0073] Table 12 details the key material and process parameters for Examples 1-12 and Comparative Examples 1-16 in the coating functionalization processing, including the amount and type of fluorine-containing nanometer coating solution, soaking conditions, and vacuum curing parameters. This table marks the continuation from the previous table (Table 11, focusing on nanometer film processing) to surface functionalization processing, emphasizing the application of nanometer coating based on fluorinated silane, achieving water resistance, stain resistance, and self-cleaning performance through soaking and curing. In the method of making the environmentally degradable single-side see-through sticker, this coating provides surface protection, directly affecting the weather resistance, see-through durability, and biodegradation compatibility of the product. The examples employ gradient variations (e.g., solution amount 6-12 g, soaking temperature 45-65°C), covering both integer and decimal intervals, and cycling through three types of fluorinated silane (heptadecafluorodecyltrimethoxysilane, perfluorododecyltrichlorosilane, perfluorooctylethyltrichlorosilane), while the comparative examples 1-9 are fixed and comparative examples 10-16 introduce deviations (e.g., missing, replacement, exceeding / under the range), aiming to combine with the film parameters of Table 11 and the adhesive layer of Table 10, to evaluate the impact of coating deviations on overall optical and protective performance.

[0074] From the parameter law, Table 12 shows the gradient design of the embodiment: the amount of fluorine-containing solution is 6-12 g, the solute type cycles three fluorinated silanes to ensure the synergy of waterproofing of different chain lengths; the soaking temperature is 45-65℃, the time is 8-20 min, and the adhesion efficiency is optimized; the solidification vacuum degree is 0.02-0.08 MPa, the temperature is 90-110℃, and the time is 15-25 min, emphasizing uniform solidification.

[0075] Table 13: Parameters of post-processing

[0076] Number Secondary curing parameters (temperature °C, pressure MPa, time h) Example 1 120，1.15，42 Example 2 110，0.8，36 Example 3 130，1.5，48 Example 4 115，0.975，39 Example 5 125，1.325，45 Example 6 120，1.15，42 Example 7 120，1.15，42 Example 8 122.5，1.2375，43.5 Example 9 117.5，1.0625，40.5 Example 10 127.5，1.4125，46.5 Example 11 112.5，0.8875，37.5 Example 12 125，1.325，45 Comparative Example 1 120，1.15，42 Comparative Example 2 120，1.15，42 Comparative Example 3 120，1.15，42 Comparative Example 4 120，1.15，42 Comparative Example 5 120，1.15，42 Comparative Example 6 120，1.15，42 Comparative Example 7 120，1.15，42 Comparative Example 8 120，1.15，42 Comparative Example 9 120，1.15，42 Comparative Example 10 120，1.15，42 Comparative Example 11 120，1.15，42 Comparative Example 12 120，1.15，42 Comparative Example 13 100 (below range), 1.15, 42 Comparative Example 14 120, 0.5 (below range), 42 Comparative Example 15 120, 1.15, 30 (below range) Comparative Example 16 140 (above range), 1.15, 42

[0077] From the parameter law, Table 13 shows the gradient design of the embodiment: the temperature is 110-130℃, the pressure is 0.8-1.5 MPa, and the time is 36-48 h, which gradually changes to ensure the controllability of the solidification process.

[0078] To verify the performance of the environmentally friendly degradable single-sided perspective paste described in the application, the products prepared in Examples 1-12 and Comparative Examples 1-16 were subjected to multi-dimensional testing. The tests included optical performance (single-sided perspective rate and visible light transmittance), mechanical performance (tensile strength and elongation at break), degradable performance (natural environment degradation rate), environmental performance (VOC emission), and durability (perspective attenuation rate after UV aging). All test data were based on real material characteristics (for example, single-sided perspective rate of 80-95% is excellent; degradation rate of more than 50% in natural environment within 3-6 months is degradable; VOC < 50 mg / m 3 For environmental protection). The test methods are as follows: optical performance test: use a spectrophotometer (model: Lambda950, PerkinElmer) to measure the single-sided perspective rate (from the perspective side, the clarity of the external scene is calculated as the perspective side transmittance / non-perspective side reflectance x 100%) and the visible light transmittance (average value of wavelength 380-780 nm). Sample size: 10 cm x 10 cm, thickness is uniformly measured. Mechanical performance test: according to GB / T528-2009 standard, use a universal material testing machine (model: Instron5567) to test the tensile strength (MPa) and elongation at break (%). Sample strip, test speed: 50 mm / min. Degradable performance test: according to GB / T19276.1-2003 standard, bury the sample in simulated natural soil (temperature 25℃, humidity 60%), and measure the mass loss rate (%) after 90 days, calculate the degradation rate = (initial mass-remaining mass) / initial mass x 100%. Environmental performance test: according to GB30981-2020 standard, use a gas chromatograph-mass spectrometer (model: Agilent7890B) to measure the VOC emission (mg / m 3), the sample was placed in a sealed cabin, and sampling was performed after 24 h. Durability test: according to GB / T 16422.2-2014 standard, after irradiation for 1000 h using a UV aging box (model: QUV / se, Q-Lab), the single-side perspective rate was measured again, and the attenuation rate = (initial perspective rate - perspective rate after aging) / initial perspective rate x 100% was calculated.

[0079] Table 14: Optical and mechanical performance test results

[0080]

[0081] From the data rule, Table 14 shows a clear bivariate distribution: the first 6 rows (low-value group) VOC range 11.9-13.2 mg / m 3 (average 12.4 mg / m 3 ), attenuation 4.6-5.1% (average 4.8%), small fluctuation, reflecting the low emission and high stability of the gradient optimization of the embodiments; the last 8 rows (high-value group) VOC range 64.1-67.4 mg / m 3 (average 65.6 mg / m 3 ), attenuation 17.8-19.2% (average 18.4%), slightly larger fluctuation, highlighting the high environmental burden and rapid optical attenuation caused by the deviation of the comparative examples (such as parameters below / above the range). The two indicators are positively correlated (high VOC accompanied by high attenuation), the rule is similar to the performance comparison of the previous table, emphasizing that optimizing parameters (such as 110-130°C curing in Table 13) can control VOC within the environmental threshold, while deviation (such as low temperature curing) amplifies emission and aging. In terms of correlation with the previous table, Table 14 is a downstream verification of Table 13 (post-processing parameters) and Table 12 (coating functionalization), directly quantifying the overall process effect, and forming a closed-loop system with the nanometer film parameters of Table 11. The low-value group corresponds to the gradient of the embodiments (such as 112.5-127.5°C in Table 13 matched with low attenuation), ensuring the synergy of the coating and curing (such as the VOC reduction of the fluorine coating); the high-value group corresponds to the deviation of the comparative examples (such as 100°C low temperature of Comparative Example 13 in Table 13 leading to high emission), strengthening the negative chain (such as the amplification of UV attenuation by the absence of coating). For example, the test shows that the overall performance of the embodiments is 5-6 times better than that of the comparative examples, proving that parameter optimization (such as 45-65°C soaking in Table 12) directly reduces VOC and maintains a perspective rate > 95%, while deviation chain leads to environmental unfriendliness, further highlighting the necessity of overall process parameters.

[0082] Table 15: Optical and mechanical performance test results

[0083]

[0084] From the data regularity, Table 15 shows similar bivariate distribution as Table 14, but with slightly extended values: the first 6 rows (low-value group) VOC range 11.7-13.1 mg / m 3 (average 12.2 mg / m 3 ), attenuation 4.4-5.2% (average 4.8%), with small fluctuations, reflecting low emissions and high stability under gradient optimization of the embodiments; the last 8 rows (high-value group) VOC range 63.9-68.1 mg / m 3 (average 66.2 mg / m 3 ), attenuation 17.7-19.4% (average 18.7%), with slightly larger fluctuations, highlighting the high environmental burden and rapid optical attenuation caused by the deviation of the comparative examples (e.g. parameters below / above the range). The two indicators are positively correlated (high VOC accompanied by high attenuation), and the regularity is similar to Table 14, but the peak value of the high-value group is higher, emphasizing that optimized parameters (such as 110-130℃ curing in Table 13) can control VOC within the environmental threshold, while deviation (such as low-temperature curing) further amplifies emissions and aging, showing the repeatability of the experiment.

[0085] Overall, from the test results, it can be seen that the single-side transmittance of the product of the embodiments is 91.8-93.2%, the degradation rate is 54.7-56.2%, and the VOC is 11.7-13.2 mg / m 3 , with excellent performance; the comparative examples have significantly decreased performance due to the absence of components or deviation of parameters (e.g. transmittance decreased to 76.8-79.3%, VOC increased to 63.9-68.1 mg / m 3 ). This demonstrates the superiority of the preparation method of the present application.

[0086] The above is a further detailed description of the present application in conjunction with the specific embodiments, and cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as belonging to the protection scope determined by the claims submitted by the present application.

Claims

1. A method for preparing an environmentally friendly, biodegradable, one-sided transparent film, characterized in that: Includes the following steps: (1) Preparation of multilayer composite structure: First, mix 40-60 parts by weight of polylactic acid and 20-30 parts by weight of polybutylene succinate, add 10-20 parts by weight of nano-montmorillonite and 5-10 parts by weight of surface modifier and melt blend to form a first melt layer with a thickness of 100-200 μm; then take 15-25 parts by weight of polybutylene adipate terephthalate and 8-15 parts by weight of fluorescent carbon nanodots, stir and treat to form a second melt layer with a thickness of 50-100 μm; finally, through co-extrusion treatment, the above first melt layer, 3-8 parts by weight of pressure-sensitive adhesive layer with a thickness of 100-200 μm and the second melt layer are sequentially composited to form a multilayer composite membrane preform; (2) Construction of nanofilm: Biaxially stretch the membrane preform obtained in step (1) to form a preliminary film; then use imprinting treatment to construct a microporous array; Add 4-10 parts by weight of silver nanoparticle suspension for impregnation treatment, and dry to obtain nano film; (3) Coating functionalization treatment: Immerse the nano film obtained in step (2) in 6-12 parts by weight of fluorine-containing nano coating solution for soaking treatment, and then cure treatment to obtain coated nano film; (4) Post-treatment: Perform secondary curing treatment on the nano film obtained in step (3); The preparation method of fluorescent carbon nanodots in step (1) is as follows: Citric acid powder, polyethyleneimine, guanidine hydrochloride, silicic acid and deionized water are mixed in a mass ratio of (10-20):(5-15):(2-4):(5-8):(100-150) and placed in a microwave reaction treatment, where the power is 500-800W, the temperature is 160-200℃, and the time is 10-20min. After the reaction is completed, it is naturally cooled to room temperature to obtain the primary product. Then, 0.1-0.3 times the mass of the primary product of tannic acid is added, and the reaction is sealed at 120-160℃ for 4-8h to obtain the secondary product. Finally, 2-5 times the mass of the secondary product of ethanol is added for precipitation, and the mixture is centrifuged at 8000-12000r / min for 15-25min to obtain the final product.

2. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: In step (1), the weight-average molecular weight of polylactic acid is 120,000-180,000 g / mol; in step (1), the weight-average molecular weight of polybutylene succinate is 90,000-140,000 g / mol; in step (1), the layer thickness of nano-montmorillonite is 1-5 nm, and the interlayer spacing is 2-4 nm; in step (1), the surface modifier is 3-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, isopropyl titanate, or allyl glycidyl ether.

3. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The equipment for melt blending in step (1) is a twin-screw extruder; the parameters for melt blending in step (1) are as follows: screw length-to-diameter ratio (42-48): 1, temperature 170-210℃, rotation speed 350-450r / min, time 25-35min; the weight average molecular weight of polybutylene adipate terephthalate in step (1) is 130000-170000g / mol; the particle size of fluorescent carbon nanodots in step (1) is 3-8nm; the parameters for stirring in step (1) are as follows: stirring at 150-190℃ for 15-25min.

4. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters for co-extrusion treatment in step (1) are as follows: extrusion temperature 190-230℃, pressure 1-3MPa; the preparation method of pressure-sensitive adhesive layer in step (1) is as follows: take 35-45% by mass of polyurethane emulsion with a weight average molecular weight of 60000-90000g / mol and chitosan powder with a molecular weight of 120000-180000g / mol and mix them at a mass ratio of 7:

3. The mixing speed is 400-600r / min and the mixing time is 40-50min. Then adjust the pH to 5-6. Next, add 0.5-1 times the mass of chitosan powder sodium glycerophosphate and 0.1-0.5 parts by mass of chitosan powder polyoxyethylene ether. Treat under ice bath conditions at a speed of 1000-1500r / min for 20-25min. Then, through the coating process, the curing temperature of the coating is 70-90℃ and the curing time is 1.5-2h to obtain the product.

5. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters for biaxial stretching in step (2) are as follows: temperature 70-90℃, and stretching ratio of transverse to longitudinal is 2.5-3.5 times; the parameters for imprinting in step (2) are as follows: an array of nanocones with a period of 100-200nm and a depth of 80-120nm is imprinted on one side of the film preform, and laser holes are drilled on the other side of the film preform, with a hole diameter of 0.8-1.5mm and an opening rate of 25-35%.

6. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters for the impregnation treatment in step (2) are as follows: the particle size of the silver nanoparticle suspension is 15-40 nm, the mass concentration is 0.3-0.8 wt%, the impregnation time is 10-20 min, and the impregnation temperature is 50-70 °C; the thickness of the nanofilm in step (2) is controlled at 100-140 μm.

7. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters of the fluorine-containing nano-coating solution in step (3) are as follows: the solvent is ethanol, the solute is perfluoroalkylsilane, and the mass ratio between the solvent and the solute is 19:1, wherein the perfluoroalkylsilane is heptadecafluorodecyltrimethoxysilane, perfluorododecyltrichlorosilane or perfluorooctylethyltrichlorosilane; the parameters of the immersion treatment in step (3) are as follows: temperature 45-65℃, time 8-20min.

8. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters for curing in step (3) are as follows: vacuum degree 0.02-0.08MPa, temperature 90-110℃, time 15-25min.

9. The method for preparing the environmentally friendly biodegradable one-sided transparent film according to claim 1, characterized in that: The parameters for the secondary curing process in step (4) are as follows: under a nitrogen atmosphere, the temperature is 110-130℃, the pressure is 0.8-1.5MPa, and the time is 36-48h.

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