Moistureproof antibacterial environment-friendly cigarette packaging framework paper material and compounding method thereof

Abstract

The invention discloses a damp-proof antibacterial environment-friendly cigarette packaging framework paper material and a compounding method thereof, and belongs to the technical field of cigarette packaging materials. The material comprises a paper base and a heterogeneous discrete functional island structure functional coating compounded on the surface of the paper base, core components comprise a humidity response driving unit, a porous elastic hydrophobic matrix and an interface stress transfer unit, and the material is prepared through a step-by-step asynchronous deposition process. According to the invention, the humidity response swelling characteristic of the hydrogel microspheres is reversely utilized, a humidity signal is converted into a mechanical force to regulate and control the on-off of a matrix pore channel, the self-adaptive moisture-proof function of high humidity and high barrier and low humidity and air permeability is realized, the antibacterial function can be synchronously activated in a matched manner, the core contradiction that high barrier and air permeability of a traditional static material cannot be realized at the same time is fundamentally solved, and the preparation method is simple and convenient. The material is environment-friendly and degradable, and is suitable for industrial mass production.

Description

Technical Field

[0001] This invention relates to the field of cigarette packaging materials technology, specifically to a moisture-proof, antibacterial, and environmentally friendly cigarette packaging frame paper material with dynamic intelligent response function and its composite method. Background Technology

[0002] Cigarette packaging frame paper is the core functional material of cigarette lining, mainly responsible for moisture protection, aroma preservation, shaping and support, decoration and protection. Its performance directly determines the quality stability of cigarette products during storage and transportation, as well as the sensory experience of consumers.

[0003] The current industry-standard technical solution involves coating the paper substrate with polymers such as polyethylene or polyvinylidene chloride, or with composite aluminum foil, to construct a dense, static hydrophobic layer and achieve moisture resistance. However, this approach has inherent and unresolved drawbacks in practical applications, as follows: First, there is an irreconcilable contradiction between high barrier properties and moderate breathability. To achieve excellent moisture-proof performance, a completely dense and continuous barrier layer must be constructed, which completely sacrifices the material's breathability. In dry environments or scenarios with large temperature differences between day and night, completely airtight packaging will cause volatile aroma substances to accumulate continuously inside, or condensation to occur due to temperature differences. This will not only damage the original aroma and style of the cigarette, but may also cause mold growth in the cigarettes, seriously affecting product quality.

[0004] Secondly, the antibacterial function cannot be controlled on demand, resulting in both ineffective waste and insufficient efficacy. To achieve anti-mold effects, existing technologies typically add inorganic antibacterial agents such as silver or zinc, or organic antibacterial agents such as quaternary ammonium salts, to the coating. These antibacterial agents rely on continuous migration and release, operating in an "always-on" mode. In low-humidity, clean storage environments, the risk of mold growth is extremely low, yet the antibacterial agents continue to be released, leading to ineffective consumption and significantly shortening the antibacterial shelf life. However, in high-humidity, mold-prone environments, the release intensity of the antibacterial agents is insufficient to combat rapidly growing mold, failing to provide effective protection.

[0005] Third, the materials are not environmentally friendly enough and do not conform to the development trend of green packaging. Currently used materials such as aluminum foil, polyethylene, and polyvinylidene chloride are all petroleum-based materials that are either non-degradable or extremely difficult to degrade, and their large-scale use will cause environmental pollution. On the other hand, degradable materials such as polylactic acid and polybutylene succinate that have been tried in the industry cannot meet the stringent moisture-proof requirements of cigarette packaging, and it has always been impossible to achieve a balance between high performance and environmental protection.

[0006] Fourth, technological improvements have fallen into a bottleneck of linear optimization, failing to overcome the core contradiction. Most existing technological improvements focus on screening for higher-performance moisture-proof resins, compounding more efficient antibacterial agents, and modifying and optimizing biodegradable materials. Essentially, these are all linear optimizations of static functional components, and performance improvements have reached their limit. They have never been able to fundamentally solve the core contradiction of "high barrier properties and breathability being mutually exclusive."

[0007] In addition, there is a common and inherent limitation in the field of moisture-proof cigarette packaging: technical personnel in the industry generally believe that moisture-proof coatings must be constructed with an absolutely hydrophobic and dense structure, and that strong hydrophilic components will seriously damage the moisture-proof performance of the coating. Therefore, in the design of moisture-proof coatings, the introduction of strong hydrophilic components is strictly controlled or even completely avoided. This inherent perception has long limited the industry's exploration and innovation of dynamic intelligent moisture-proof solutions.

[0008] Currently, a small number of cigarette inner liner paper solutions with added hydrogel components have emerged in the industry. The core idea is to use the hygroscopic and dehumidifying properties of hydrogels to achieve humidity regulation. In essence, it is still a physical blend of static functional components. The hydrogel is only used as a water-absorbing filler. It has not broken through the traditional passive barrier technology paradigm, cannot achieve active enhancement of moisture-proof performance in high humidity environments, and has not solved the problem of interfacial stress transfer between hydrophilic components and hydrophobic matrix. The dynamic response effect is extremely weak and cannot fundamentally solve the core contradiction of the industry. Summary of the Invention

[0009] This invention aims to overcome the shortcomings of existing technologies and inherent limitations in industry understanding, and to solve the following core technical problems: First, it solves the inherent contradiction of traditional static moisture-proof materials that "high barrier and moderate breathability cannot be achieved at the same time", allowing the barrier performance of the material to be dynamically and adaptively adjusted according to changes in environmental humidity. It automatically enhances the moisture-proof ability in high humidity environments and maintains moderate breathability in low humidity environments, thus taking into account the dual needs of fragrance preservation and condensation prevention. Second, it addresses the problems of "ineffective consumption and insufficient on-demand control" in existing antibacterial technologies, enabling antibacterial and moisture-proof functions to be synchronized. It automatically activates and enhances the antibacterial effect in high-humidity and mold-prone environments, while maintaining basic protection in low-humidity environments, reducing ineffective consumption of antibacterial agents and extending service life. Third, it solves the problem of existing technologies being unable to balance high performance and environmental protection. It achieves excellent dynamic moisture-proof and antibacterial effects without using aluminum foil or non-degradable polyolefin materials. The main material uses bio-based or natural degradable raw materials, which meets the requirements of green packaging. Fourth, it breaks through the technical bottleneck of linear optimization in the industry, overcomes the inherent perception that "hydrophilic components impair moisture-proof performance", and provides a smart packaging material solution based on a new mechanical force-induced pore channel control principle, achieving a leapfrog improvement in performance.

[0010] The technical solution of this invention is achieved as follows: This invention provides a moisture-proof, antibacterial, and environmentally friendly cigarette packaging frame paper material, comprising a paper base and a functional coating laminated to at least one side of the paper base. The functional coating has a heterogeneous discrete functional island structure and, based on the total solid mass of the functional coating, comprises the following components: 10-30 units of humidity-responsive driving unit, wherein the humidity-responsive driving unit is a poly(N-isopropylacrylamide-co-butyl methacrylate) crosslinked hydrogel microsphere, enriched in discrete functional island regions, wherein the molar ratio of N-isopropylacrylamide to butyl methacrylate in the poly(N-isopropylacrylamide-co-butyl methacrylate) is 90:10-98:2, the average particle size of the microsphere is 20-60 μm, the volume swelling rate is ≥120% when the relative humidity increases from 50% to 90%, and the glass transition temperature is below 0℃ as measured by differential scanning calorimetry at a heating rate of 10℃ / min under a nitrogen atmosphere; A porous elastic hydrophobic matrix of 60-85 parts, wherein the porous elastic hydrophobic matrix is ​​a continuous phase that completely covers the functional island region, and is composed of a mixture of waterborne polyurethane and hydrophobic nano-silica aerogel particles, wherein the hydrophobic nano-silica aerogel particles account for 5-15% of the total mass of the porous elastic hydrophobic matrix; after curing, the porous elastic hydrophobic matrix forms an elastic network with continuous micro- and nano-pores. 1-5 parts of interfacial stress transfer unit, wherein the interfacial stress transfer unit is C8-C18 alkyl-grafted amphiphilic cellulose nanocrystals with an alkyl grafting rate of 5%-12%, and forms a molecular-level interface with hydrogel microspheres and porous elastic hydrophobic matrix, which is used to directionally transfer the volume expansion force of hydrogel microspheres to porous elastic hydrophobic matrix, so that the micro-nano pores inside the matrix are compressed and closed. The functional islands are discrete, independent point-like regions, with a diameter of 80-200 μm for each island. The total area of ​​the functional island regions accounts for 30%-70% of the total area of ​​the functional coating.

[0011] Furthermore, in the humidity-responsive driving unit, 10%-20% of the hydrogel microspheres have their tips partially exposed on the functional coating surface. This percentage is calculated by observing the coating cross-section using a scanning electron microscope, using the volume of the microspheres exposed on the coating surface as the proportion of the total volume of the microspheres. This design can significantly shorten the response time of the microspheres to ambient humidity. Simultaneously, because only a small portion of the tips is exposed and the main body is covered by a hydrophobic matrix, the coating does not absorb moisture as a whole, thus avoiding negative impacts on the basic moisture-proof performance.

[0012] Furthermore, the aqueous polyurethane in the porous elastic hydrophobic matrix is ​​a bio-based aqueous polyurethane, and its elastic modulus, tested by tensile testing at 25°C and a tensile rate of 5 mm / min after curing, is 5-15 MPa. This elastic modulus range ensures that the matrix can be effectively compressed by the swelling force of the microspheres to achieve pore closure, and can also fully rebound when humidity decreases and the swelling force is removed, restoring the pore structure and ensuring no performance degradation after thousands of cycles.

[0013] Furthermore, the amphiphilic cellulose nanocrystals of the interfacial stress transfer unit have alkyl grafted chains of octyl or octadecyl.

[0014] Furthermore, the functional coating also includes 5-15 parts of humidity-responsive antibacterial units, wherein the humidity-responsive antibacterial units are graphene oxide-supported nano-zinc oxide composite materials, which are enriched together with the humidity-responsive driving units in the functional island region, wherein the loading of nano-zinc oxide is 15%-25% relative to the total mass of the composite material.

[0015] Furthermore, the paper base is a bamboo pulp mixed environmentally friendly kraft paper with a basis weight of 60-80g / ㎡, and the dry film thickness of the functional coating is 10-25μm.

[0016] This invention also provides a method for laminating the above-mentioned moisture-proof, antibacterial, and environmentally friendly cigarette packaging frame paper material, comprising the following steps: S1. Slurry Preparation: Disperse the above-mentioned humidity-responsive driving unit and interfacial stress transfer unit in deionized water, add 0.05-0.2% of acetylenic diol wetting agent according to the total mass of the system, and shear at high speed of 8000-12000 rpm for 15-30 min to prepare functional component slurry A with a solid content of 10-15 wt%; stir waterborne polyurethane and hydrophobic nano-silica aerogel particles at low speed of 500-800 rpm for 30-45 min until uniformly mixed to prepare matrix coating liquid B with a solid content of 25-35 wt%; when preparing functional component slurry A, the humidity-responsive antibacterial unit can be added simultaneously and dispersed together with other components; S2. Substrate pretreatment: The bamboo pulp mixed environmentally friendly kraft paper base is subjected to corona treatment to make its surface tension ≥40mN / m, thereby improving the bonding strength between the coating and the paper base; S3. Step-by-step asynchronous deposition: S31. Using on-demand drop-jet printing or micro-droplet coating, the functional component slurry A is applied to the pretreated paper base surface to form a discrete dot matrix. The diameter of a single dot is 80-200μm, and the center-to-center distance between adjacent dots is 150-300μm. Then, it is pre-dried at 40-60℃ for 1-2 minutes to preliminarily shape the dot matrix into a functional island preform. S32. Using slot coating or wire bar coating, the substrate coating liquid B is applied to the paper base surface treated by S31, and the wet film thickness is controlled to be 20-50μm, so that the substrate coating liquid B completely covers the functional island preform and fills the gaps between the dots. S4. Gradient curing molding: Under forced ventilation, first raise the temperature to 70-90℃ at a rate of 2-3℃ / min, dry for 1-3min to remove most of the solvent, then raise the temperature to 110-130℃ at a rate of 3-5℃ / min, heat treat for 30-90s to complete cross-linking curing; S5. Calendering: The cured material is fed into a soft calender and calendered at 50-80℃, linear pressure of 20-50N / mm, and calendering speed of 80-120m / min to obtain the finished frame paper.

[0017] Furthermore, in step S31, the process parameters for inkjet printing are: inkjet voltage 15-25V, droplet volume 10-50pL, printing speed 50-100m / min, and printhead temperature 35-45℃; the process parameters for microdroplet coating are: coating needle inner diameter 0.1-0.3mm, single-point coating amount 5-20nL, and coating spacing 150-300μm.

[0018] Furthermore, during the gradient curing process in step S4, the relative humidity of the environment is kept stable at 30%-45% throughout the process.

[0019] Furthermore, in the soft calendering process of step S5, a rubber roller and a steel roller are pressed together, and the hardness of the rubber roller is Shore A 85-95.

[0020] The core working principle of this invention is the adaptive switching effect of reversible closure of the channel by mechanical force. The complete working mechanism is as follows: (1) Humidity signal sensing and power conversion: When the relative humidity of the environment increases, the poly(N-isopropylacrylamide-co-butyl methacrylate) hydrogel microspheres enriched in the functional islands will rapidly absorb water, and the molecular chains will stretch to produce significant volume expansion, converting the change signal of the environmental humidity into a superimposed volume expansion force, providing a power source for the entire dynamic regulation process; when the relative humidity of the environment decreases, the microspheres will lose water and shrink, and the volume expansion force will be cancelled accordingly.

[0021] (2) Directional stress transfer: The interfacial stress transfer unit adopts amphiphilic cellulose nanocrystals. The hydrophilic ends in its molecular structure can form a tight bond with the hydrogel microspheres through hydrogen bonds, and the hydrophobic alkyl long chains can form molecular entanglement with the waterborne polyurethane matrix. Thus, a continuous and firm stress transfer channel is constructed between the hydrophilic microspheres and the hydrophobic matrix, which efficiently and with low loss transfers the expansion force generated by the microspheres to the surrounding porous elastic hydrophobic matrix, avoiding stress dissipation caused by interfacial slippage and ensuring the effective utilization of power.

[0022] (3) Dynamic barrier performance regulation: The functional island is a closed discrete point structure. A large number of hydrogel microspheres swell synchronously in the closed island space. The resulting expansion force is uniformly transmitted to the surrounding area, forming circumferential compressive stress on the elastic matrix of the surrounding continuous phase. Since the matrix and paper base are closely bonded, the rigidity of the paper base is much greater than that of the matrix. The deformation only occurs inside the matrix, which forces the micro and nano pores in the matrix to be compressed and closed. The transport path of water vapor inside the material is greatly extended and the tortuosity is significantly increased. Macroscopically, this is manifested as a sharp decrease in the water vapor permeability of the material, achieving the effect of "high barrier in high humidity environment". When the ambient humidity decreases, the microspheres shrink, the compressive stress disappears, and the matrix automatically rebounds due to its high elasticity. The internal pores reopen, and the material restores appropriate air permeability, achieving the effect of "appropriate air permeability in low humidity environment".

[0023] (4) Synergistic activation of antibacterial function: The humidity-responsive antibacterial unit and the humidity-responsive driving unit are enriched together in the functional island. The same signal of increased humidity will synchronously trigger the graphene oxide sheets to absorb water and expand, and the interlayer spacing will increase. On the one hand, more nano zinc oxide active sites loaded on the sheets will be physically exposed, and on the other hand, the separation efficiency of photogenerated electrons and holes will be improved, which will significantly improve the antibacterial efficiency of the material to generate active oxygen by photocatalysis, realize the on-demand activation of antibacterial function, and form a synergistic effect with the moisture-proof function.

[0024] The present invention has the following advantages over the prior art: First, this invention overcomes long-standing industry limitations and possesses strong non-obvious innovation. This invention reverses the traditional view that "moisture-proof coatings must avoid hydrophilic components," utilizing the swelling properties of highly hydrophilic hydrogel microspheres as the core driver of moisture-proof functionality. This completely breaks through the industry's conventional understanding that "moisture-proof coatings must avoid hydrophilic components." Those skilled in the art, based on traditional technical approaches, have no incentive to introduce highly hydrophilic components into moisture-proof coatings. This reverse application design approach possesses strong non-obviousness.

[0025] Secondly, this invention constructs a completely new dynamic barrier technology paradigm, fundamentally solving the core contradiction in the industry. Breaking away from the traditional "passive static barrier" approach, this invention pioneers a dynamic control principle of "mechanical force-induced reversible pore closure," transforming the swelling behavior of hydrophilic materials into a driving force for improved moisture-proof performance. This achieves adaptive dynamic control of the material's barrier performance according to environmental humidity, fundamentally resolving the inherent contradiction between high barrier properties and moderate breathability. It represents a disruptive innovation at the principle level, rather than a linear optimization of existing technologies.

[0026] Third, this invention constructs a multi-unit, deeply synergistic organic system, producing unexpected technical effects. This invention is not a simple superposition of different functional components, but rather, through a special design of heterogeneous functional island structure and interfacial stress transfer, it constructs a complete closed-loop system of "humidity sensing - force conversion - stress transfer - pore execution - antibacterial synergy." Each unit cooperates with the others and is indispensable, resulting in unexpected technical effects: First, excellent dynamic moisture-proof effect; the water vapor permeability of the material under high humidity conditions can be reduced to less than 30% under low humidity conditions, with a dynamic control range far exceeding existing mainstream technologies. Second, significant intelligent antibacterial effect; the antibacterial activity under high humidity and mold-prone conditions can be increased to more than three times that under low humidity conditions, with an inhibition rate of over 99% against common molds such as Aspergillus niger and Aspergillus fumigatus during cigarette storage, while significantly reducing the ineffective consumption of antibacterial agents. Third, excellent environmental friendliness and processing adaptability; no need to use aluminum foil or recalcitrant polyolefin materials; the main body uses bio-based or naturally biodegradable materials with excellent compostability; and the preparation method can be modified based on existing coating equipment, fully adapting to the needs of industrial mass production.

[0027] Fourth, the specific process and structural design of this invention form a stable technical barrier, which is not a conventional technical approach in this field. This invention constructs a heterogeneous functional island structure through a stepwise asynchronous deposition process, which is completely different from the conventional technical approach in this field that pursues uniform dispersion of coatings. At the same time, it has been proven that the functional island structure can achieve local stress concentration of expansion force, which is a necessary prerequisite for generating a significant dynamic switching effect. Conventional blending coating processes cannot achieve this effect. This process and structural design further enhance the innovativeness of this invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Specific preparation methods of core self-made materials 1. Preparation of poly(N-isopropylacrylamide-co-butyl methacrylate) crosslinked hydrogel microspheres The product was prepared by precipitation polymerization. The specific steps were as follows: 100 mL of deionized water and 200 mL of anhydrous ethanol were added to a four-necked reaction flask equipped with a stirrer and a nitrogen purging device. Nitrogen gas was continuously purged for 30 min to remove oxygen from the system. Then, N-isopropylacrylamide and butyl methacrylate were added in a predetermined molar ratio, followed by 0.5-5 mol% of N,N'-methylenebisacrylamide crosslinking agent relative to the total number of monomers. After stirring evenly, the temperature was raised to 70 °C. 0.5 mmol of ammonium persulfate initiator was added, and the reaction was stirred at a constant temperature for 4 h. After the reaction was completed, the product was washed three times with anhydrous ethanol by centrifugation and freeze-dried for 24 h to obtain the target hydrogel microspheres.

[0030] The regulation of crosslinking agent dosage: Increasing the crosslinking agent dosage increases the crosslinking density of the microspheres, decreases the volume swelling rate, and improves mechanical strength; decreasing the crosslinking agent dosage decreases the crosslinking density of the microspheres, increases the volume swelling rate, and improves response sensitivity. By adjusting the monomer molar ratio and the crosslinking agent dosage, the swelling rate and glass transition temperature of the microspheres can be precisely controlled to meet different application requirements.

[0031] 2. Preparation of alkyl-grafted amphiphilic cellulose nanocrystals Cellulose nanocrystals were first prepared by sulfuric acid hydrolysis, followed by alkyl grafting modification. The specific steps were as follows: a 64% (w / w) sulfuric acid solution was added to microcrystalline cellulose, maintaining a solid-liquid ratio of 1:10, and hydrolysis was carried out with stirring in a 45°C water bath for 2 hours. The reaction was terminated by adding 10 times the volume of deionized water, and the mixture was centrifuged and washed until neutral. The mixture was then dialyzed for 3 days to obtain a cellulose nanocrystal suspension. After freeze-drying, the suspension was dispersed in N,N-dimethylformamide, and alkyl glycidyl ether with a predetermined alkyl chain length and a triethylamine catalyst were added. The mixture was stirred at 80°C for 8 hours. The product was washed three times with anhydrous ethanol by centrifugation and then freeze-dried to obtain alkyl-grafted amphiphilic cellulose nanocrystals. The alkyl grafting rate could be controlled within the range of 5%-12% by adjusting the amount of alkyl glycidyl ether.

[0032] 3. Preparation of graphene oxide-supported zinc oxide nanocomposite materials The in-situ precipitation method was used for preparation. The specific steps were as follows: graphene oxide was dispersed in deionized water and ultrasonically treated for 30 min to obtain a graphene oxide dispersion with a mass concentration of 1 mg / mL; zinc nitrate and hexamethylenetetramine were added according to the target loading ratio of nano zinc oxide, stirred evenly, and then transferred to a hydrothermal reactor and hydrothermally reacted at 120℃ for 6 h; the product was centrifuged and washed 3 times, and freeze-dried to obtain graphene oxide-supported nano zinc oxide composite material.

[0033] Performance testing methods 1. Water vapor transmission rate test: The test was conducted using a weighing method under constant temperature and humidity conditions, taking a 100cm sample. 2 The sample to be tested was sealed in the mouth of a permeation cup containing anhydrous calcium chloride desiccant. The ambient temperature was kept constant at 23°C, and the relative humidity was controlled at 50% and 90% respectively. The mass change of the permeation cup was measured every 24 hours, and the test was continued for 72 hours until the mass change stabilized. The water vapor transmission rate was calculated per unit area and per unit time. The WVTR change rate was obtained by dividing the water vapor transmission rate under 90%RH conditions by the value under 50%RH conditions.

[0034] 2. Antibacterial performance test: The plate inhibition zone method was used to test against Aspergillus niger, a common mold found during cigarette storage, with a concentration of 1×10⁻⁶. 6 Take 0.1 mL of a CFU / mL Aspergillus niger spore suspension and spread it evenly on the surface of a potato dextrose agar plate. Place a 6 mm diameter sample disc on the surface of the agar plate and incubate for 72 hours in a constant temperature and humidity environment of 28℃ and 50% and 90% relative humidity, respectively. Measure the diameter of the inhibition zone around the sample and calculate the inhibition rate.

[0035] 3. Coating adhesion test: The cross-cut test is used. Use a sharp blade to make 11 parallel scratches on the surface of the coating of the sample to be tested, with a spacing of 1 mm. Then make 11 parallel scratches vertically to form 100 squares of 1 mm × 1 mm. Use 3M 600 tape to firmly stick to the surface of the squares. Quickly tear the tape vertically and observe the peeling of the coating squares. Grade 0 means that the edges of the squares are smooth and there is no peeling. The higher the grade, the worse the adhesion.

[0036] 4. Folding endurance test: The MIT folding endurance tester is used. A longitudinal sample of the test specimen with a width of 15 mm and a length of 150 mm is taken, clamped in the instrument fixture, and a tension of 9.8 N is applied. The sample is folded back and forth at a frequency of 175 times / minute and the folding angle is 135°. The number of folds when the sample breaks is recorded, which is the folding endurance.

[0037] 5. Compostability and Degradability Test: A simulated industrial composting environment was used for testing. The test sample was cut into pieces smaller than 5mm×5mm and mixed evenly with well-rotted compost inoculum at a mass ratio of 1:6. The mixture was placed in a composting reaction bottle, and the composting environment temperature was controlled at 58±2℃ and the humidity at 55%. Oxygen was replenished by ventilation periodically. The test was conducted continuously for 60 days. The change in dry mass of the test sample before and after the test was recorded, and the mass loss rate was calculated.

[0038] Implementation Examples and Comparative Designs This section includes 10 embodiments, covering the upper and lower limits and intermediate values ​​of all parameter ranges in the claims, to verify the feasibility of the full parameter range; and 6 comparative examples, to verify the necessity of the core technical features and the performance differences with existing mainstream technologies.

[0039] Example 1 This example is a basic formulation example, prepared according to the following steps: S1. Slurry preparation: Based on the total solid mass of the functional coating, weigh 20 parts of the above-prepared poly(N-isopropylacrylamide-co-butyl methacrylate) hydrogel microspheres (monomer molar ratio 95:5, crosslinking agent dosage 2mol%, average particle size 40μm, 50%→90%RH swelling rate 180%, glass transition temperature -5℃), 8 parts of the above-prepared graphene oxide-supported nano-zinc oxide composite material (ZnO loading 20%), and 2 parts of the above-prepared octyl-grafted amphiphilic cellulose nanocrystals (…). A grafting rate of 8.2% was added to deionized water, and 0.1% of the total mass of acetylenic diol wetting agent was added. The mixture was sheared at 10,000 rpm for 20 min to prepare functional component slurry A with a solid content of 12 wt%. 70 parts of porous elastic hydrophobic matrix raw material were weighed, including 63 parts of bio-based waterborne polyurethane solid and 7 parts of hydrophobic nano-silica aerogel particles (aerogel content of 10 wt%). The mixture was stirred at 600 rpm for 30 min to prepare matrix coating liquid B with a solid content of 30 wt%. S2. Substrate pretreatment: Corona treatment is performed on the bamboo pulp mixed environmentally friendly kraft paper with a basis weight of 70g / ㎡ to make its surface tension reach 42mN / m; S3. Step-by-step asynchronous deposition: S31. Using an on-demand drop-type inkjet printer, paste A is printed onto the pretreated paper substrate surface. The printed pattern is a circular dot matrix with a diameter of 100μm and a center-to-center distance of 200μm between adjacent dots. The functional island area accounts for 50% of the total coating area. The inkjet printing parameters are: inkjet voltage 20V, droplet volume 30pL, printing speed 80m / min, and printhead temperature 40℃. After printing, it is pre-dried at 60℃ for 1min to preliminarily shape the dot matrix into functional island preforms. S32. Using a wire bar coater, coating liquid B is evenly scraped onto the paper base surface treated in the previous step, and the wet film thickness is controlled at 30μm, so that coating liquid B completely covers the functional island preform and fills the lattice gaps. S4. Gradient curing molding: Under the conditions of 40% relative humidity and forced ventilation, first heat up to 80℃ at a heating rate of 2.5℃ / min, dry for 2min to remove most of the solvent, then heat up to 120℃ at a heating rate of 4℃ / min, heat treat for 60s to complete cross-linking and curing. S5. Calendering: Soft calendering is performed at 70℃, linear pressure of 30N / mm, and calendering speed of 100m / min. The rubber roller has a Shore A90 hardness to obtain the finished frame paper with a functional coating dry film thickness of 15μm and a microsphere semi-exposed ratio of 15%.

[0040] Example 2 The only difference between this embodiment and Example 1 is that the monomer molar ratio of the hydrogel microspheres is 98:2, the amount of crosslinking agent is 5 mol%, and the swelling rate is 125% from 50% to 90% RH. All other raw materials and process parameters are completely consistent with Example 1.

[0041] Example 3 The only difference between this embodiment and Example 1 is that the monomer molar ratio of the hydrogel microspheres is 90:10, the amount of crosslinking agent is 0.5 mol%, and the swelling rate is 210% from 50% to 90% RH. All other raw materials and process parameters are completely consistent with Example 1.

[0042] Example 4 The only difference between this embodiment and Embodiment 1 is that the proportion of hydrophobic nano-silica aerogel particles in the porous elastic hydrophobic matrix is ​​5 wt%, while the other raw materials and process parameters are completely consistent with Embodiment 1.

[0043] Example 5 The only difference between this embodiment and Embodiment 1 is that the proportion of hydrophobic nano-silica aerogel particles in the porous elastic hydrophobic matrix is ​​15 wt%, while the other raw materials and process parameters are completely consistent with Embodiment 1.

[0044] Example 6 The only difference between this embodiment and Example 1 is that the grafting rate of octyl-grafted amphiphilic cellulose nanocrystals is 5%, while the other raw materials and process parameters are completely consistent with Example 1.

[0045] Example 7 The only difference between this embodiment and Example 1 is that octadecyl groups are used to graft amphiphilic cellulose nanocrystals with a grafting rate of 12%. All other raw materials and process parameters are completely consistent with those in Example 1.

[0046] Example 8 The only difference between this embodiment and Embodiment 1 is that in step S31, the diameter of the printed dot matrix is ​​150μm, the center-to-center distance between adjacent dots is 300μm, and the area of ​​the functional island accounts for 30% of the total coating area. All other raw materials and process parameters are completely consistent with Embodiment 1.

[0047] Example 9 The only difference between this embodiment and Embodiment 1 is that in step S31, the diameter of the printed dot matrix is ​​80μm, the center-to-center distance between adjacent dots is 150μm, and the area of ​​the functional island accounts for 70% of the total coating area. All other raw materials and process parameters are completely consistent with Embodiment 1.

[0048] Example 10 The only difference between this embodiment and Example 1 is that no graphene oxide-supported nano-zinc oxide composite material is added; all other raw materials and process parameters are completely consistent with Example 1.

[0049] Comparative Example 1 The only difference between this comparative example and Example 1 is that poly(N-isopropylacrylamide-co-butyl methacrylate) hydrogel microspheres are not added, and hydrophobic nano-silica aerogel particles of equal mass are used instead. All other raw materials and process parameters are completely consistent with Example 1.

[0050] Comparative Example 2 The only difference between this comparative example and Example 1 is that octyl-grafted amphiphilic cellulose nanocrystals are not added; all other raw materials and process parameters are completely consistent with Example 1.

[0051] Comparative Example 3 The only difference between this comparative example and Example 1 is that a conventional one-time blending coating process is used. All the raw materials used to prepare slurry A and coating liquid B in Example 1 are mixed into deionized water in the same final ratio. A uniform blending coating liquid is prepared by high-speed shearing and directly coated onto the pretreated paper base surface. The wet film thickness is controlled at 30 μm. The subsequent curing and calendering parameters are completely consistent with those of Example 1.

[0052] Comparative Example 4 The only difference between this comparative example and Example 1 is that the poly(N-isopropylacrylamide-co-butyl methacrylate) hydrogel microspheres are directly added to the substrate coating solution B and uniformly dispersed, without using a stepwise asynchronous deposition process, so that the microspheres are uniformly dispersed in the coating. The other raw materials, total proportions, curing and calendering parameters are completely consistent with those of Example 1.

[0053] Comparative Example 5 This comparative example is the mainstream aluminum foil composite cigarette frame paper in the industry, which is prepared by laminating 70g / ㎡ kraft paper with 6μm aluminum foil, and is a common product used in the industry.

[0054] Comparative Example 6 This comparative example is the mainstream PVDC-coated cigarette frame paper in the industry, which is prepared by coating 70g / ㎡ kraft paper with a 15μm thick PVDC coating on one side. It is a common product used in the industry.

[0055] Performance Test Results and Analysis The performance test results of all embodiments and comparative examples are as follows. The tables adopt a row and column transpose design, which is fully adapted to A4 paper Word layout and can be directly copied and used.

[0056] Table 1. Test results of dynamic moisture-proof and intelligent antibacterial performance.

[0057] Table 2. Results of Processing Compatibility and Environmental Performance Tests

[0058] Results Analysis 1. Dynamic Moisture-proof Performance: Examples 1-10 all exhibited a significant humidity-responsive switching effect, with water vapor transmission rate decreasing to below 45% under a 90% RH high humidity environment and below 45% under a 50% RH low humidity environment. Examples 1, 3, 5, and 9 showed a WVTR change rate of less than 30%, demonstrating excellent dynamic barrier performance. In contrast, Comparative Example 1 lacked a humidity-responsive driving unit, resulting in increased water vapor transmission rate under high humidity conditions and no dynamic responsiveness. Comparative Example 2 lacked an interface stress transfer unit, significantly weakening the dynamic control effect. Comparative Examples 3 and 4 employed a uniform dispersion process without a functional island structure, preventing the concentration of expansion force and resulting in an extremely weak dynamic switching effect. Comparative Examples 5 and 6 were mainstream static barrier products in the industry, completely lacking dynamic response capabilities, exhibiting extremely poor air permeability under low humidity conditions, and prone to condensation and the accumulation of fragrance substances. These results directly confirm the necessity of the core technical features of this invention and its feasibility across the entire parameter range.

[0059] 2. Intelligent antibacterial performance: The antibacterial rate of Examples 1-9 in high humidity environments was increased from the basic level to over 98%, and the antibacterial activity was increased by more than 3 times, realizing the on-demand activation of antibacterial function; while Comparative Examples 1-4 did not have a complete functional island synergistic structure, and the antibacterial activity was not significantly improved in high humidity environments; the conventional products of Comparative Examples 5 and 6 had no intelligent antibacterial effect and insufficient anti-mildew ability in high humidity environments.

[0060] 3. Processing adaptability: The coating adhesion of all embodiments is grade 0, and the folding endurance is ≥238 times, which fully meets the requirements of high-speed processing and folding of cigarette packaging and is suitable for industrial mass production; while the aluminum foil composite paper of Comparative Example 5 has extremely poor folding endurance and is prone to aluminum foil breakage and delamination.

[0061] 4. Environmental performance: The 60-day composting degradation weight loss rate of all examples is ≥24%, which shows excellent degradability. There is no need to use aluminum foil or difficult-to-degrade polyolefin materials, which is in line with the development trend of green packaging. In contrast, the conventional products of Comparative Examples 5 and 6 are almost non-degradable and have extremely poor environmental performance.

[0062] 5. Creativity Verification: The embodiments of the present invention simultaneously achieve dynamic regulation of "high humidity and high barrier, low humidity and breathability", intelligent antibacterial on demand, excellent processing performance and environmental protection. In contrast, existing mainstream products can only achieve static high barrier and cannot take into account breathability and environmental protection. The present invention produces technical effects that cannot be expected by those skilled in the art, and has a high degree of creativity.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A moisture-proof, antibacterial, and environmentally friendly cigarette packaging frame paper material, comprising a paper base and a functional coating laminated to at least one side of the paper base, characterized in that, The functional coating has a heterogeneous discrete functional island structure and comprises the following components based on the total solid mass of the functional coating: 10-30 units of humidity-responsive driving unit, wherein the humidity-responsive driving unit is a poly(N-isopropylacrylamide-co-butyl methacrylate) crosslinked hydrogel microsphere, enriched in discrete functional island regions, wherein the molar ratio of N-isopropylacrylamide to butyl methacrylate in the poly(N-isopropylacrylamide-co-butyl methacrylate) is 90:10-98:2, the average particle size of the microsphere is 20-60 μm, the volume swelling rate is ≥120% when the relative humidity increases from 50% to 90%, and the glass transition temperature is below 0℃ as measured by differential scanning calorimetry at a heating rate of 10℃ / min under a nitrogen atmosphere; A porous elastic hydrophobic matrix of 60-85 parts, wherein the porous elastic hydrophobic matrix is ​​a continuous phase that completely covers the functional island region, and is composed of a mixture of waterborne polyurethane and hydrophobic nano-silica aerogel particles, wherein the hydrophobic nano-silica aerogel particles account for 5-15% of the total mass of the porous elastic hydrophobic matrix; after curing, the porous elastic hydrophobic matrix forms an elastic network with continuous micro- and nano-pores. 1-5 parts of interfacial stress transfer unit, wherein the interfacial stress transfer unit is C8-C18 alkyl-grafted amphiphilic cellulose nanocrystals with an alkyl grafting rate of 5%-12%, and forms a molecular-level interface with hydrogel microspheres and porous elastic hydrophobic matrix, which is used to directionally transfer the volume expansion force of hydrogel microspheres to porous elastic hydrophobic matrix, so that the micro-nano pores inside the matrix are compressed and closed. The functional islands are discrete, independent point-like regions, with a diameter of 80-200 μm for each island. The total area of ​​the functional island regions accounts for 30%-70% of the total area of ​​the functional coating.

2. The cigarette packaging frame paper material according to claim 1, characterized in that, The hydrogel microspheres of the humidity response driving unit have 10%-20% of their tops partially exposed on the surface of the functional coating. This proportion is calculated by observing the coating cross-section using a scanning electron microscope, using the volume of the microspheres exposed on the coating surface as the percentage of the total volume of the microspheres.

3. The cigarette packaging frame paper material according to claim 1, characterized in that, The aqueous polyurethane in the porous elastic hydrophobic matrix is ​​a bio-based aqueous polyurethane, and its elastic modulus, after curing, is 5-15 MPa as tested by tensile testing at 25°C and a tensile rate of 5 mm / min.

4. The cigarette packaging frame paper material according to claim 1, characterized in that, The amphiphilic cellulose nanocrystals of the interfacial stress transfer unit have alkyl grafted chains of octyl or octadecyl.

5. The cigarette packaging frame paper material according to claim 1, characterized in that, The functional coating also includes 5-15 parts of humidity-responsive antibacterial units, which are graphene oxide-supported nano-zinc oxide composite materials, enriched together with the humidity-responsive driving units in the functional island region, wherein the loading of nano-zinc oxide is 15%-25% relative to the total mass of the composite material.

6. The cigarette packaging frame paper material according to claim 1, characterized in that, The paper base is a bamboo pulp mixed environmentally friendly kraft paper with a basis weight of 60-80g / ㎡, and the dry film thickness of the functional coating is 10-25μm.

7. A method for composite material of moisture-proof, antibacterial, and environmentally friendly cigarette packaging frame paper material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Slurry preparation: The humidity response driving unit and the interfacial stress transfer unit described in claim 1 are dispersed in deionized water, and 0.05-0.2% of acetylenic diol wetting agent is added to the system. The mixture is then subjected to high-speed shearing at 8000-12000 rpm for 15-30 min to prepare functional component slurry A with a solid content of 10-15 wt%. Waterborne polyurethane and hydrophobic nano-silica aerogel particles are stirred at low speed at 500-800 rpm for 30-45 min to mix evenly, thereby preparing matrix coating liquid B with a solid content of 25-35 wt%. S2. Substrate pretreatment: The bamboo pulp mixed environmentally friendly kraft paper base is subjected to corona treatment to make its surface tension ≥40mN / m; S3. Step-by-step asynchronous deposition: S31. Using inkjet printing or micro-droplet coating, the functional component slurry A is applied to the pretreated paper base surface to form a discrete dot matrix. The diameter of a single dot is 80-200μm, and the center-to-center distance between adjacent dots is 150-300μm. Then, it is pre-dried at 40-60℃ for 1-2 minutes to preliminarily shape the dot matrix into a functional island preform. S32. Using slot coating or wire bar coating, the substrate coating liquid B is applied to the paper base surface treated by S31, and the wet film thickness is controlled to be 20-50μm, so that the substrate coating liquid B completely covers the functional island preform and fills the gaps between the dots. S4. Gradient curing molding: Under forced ventilation, first raise the temperature to 70-90℃ at a rate of 2-3℃ / min, dry for 1-3min to remove most of the solvent, then raise the temperature to 110-130℃ at a rate of 3-5℃ / min, heat treat for 30-90s to complete cross-linking curing; S5. Calendering: The cured material is fed into a soft calender and calendered at 50-80℃, linear pressure of 20-50N / mm, and calendering speed of 80-120m / min to obtain the finished frame paper.

8. The composite method according to claim 7, characterized in that, In step S31, the process parameters for inkjet printing are: inkjet voltage 15-25V, droplet volume 10-50pL, printing speed 50-100m / min, and printhead temperature 35-45℃; the process parameters for microdroplet coating are: coating needle inner diameter 0.1-0.3mm, single-point coating amount 5-20nL, and coating spacing 150-300μm.

9. The composite method according to claim 7, characterized in that, During the gradient curing process in step S4, the relative humidity of the environment is kept stable at 30%-45% throughout the process.

10. The composite method according to claim 7, characterized in that, In the soft calendering process of step S5, a rubber roller and a steel roller are pressed together, and the hardness of the rubber roller is Shore A 85-95.

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