A method for preparing sensitive dye microcapsules and a cigarette filter with microcapsules
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA TOBACCO SHAANXI IND
- Filing Date
- 2026-05-08
- Publication Date
- 2026-06-23
Smart Images
Figure CN122252108A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of tobacco product technology, specifically to a method for preparing sensitive dye microcapsules and a cigarette filter with microcapsules, and more particularly to a cigarette filter with a colorimetric reaction detection structure, a sensitive dye microcapsule loading system and a three-stage filtration detection structure, which can realize the visual identification and semi-quantitative detection of flavoring components such as esters, aldehydes and alcohols in cigarette smoke. Background Technology
[0002] In the tobacco product industry, flavoring additives such as menthol, esters, aldehydes, and alcohols are often added during the production process to improve the smoking experience of cigarettes. However, with current technology, consumers cannot directly determine the types and amounts of additives in cigarettes when purchasing and using them. This affects consumers' right to know about the products and their ability to make informed choices, and also makes it difficult to obtain direct feedback on the quality control of tobacco product additives.
[0003] Current research and development of cigarette filter technology focuses primarily on reducing tar and harm, and adjusting flavor. For example, materials such as cellulose acetate and polylactic acid are used to filter particulate impurities in cigarette smoke, or flavor capsules are used to release flavorings on demand. Some filter technologies combine porous structures and airflow control designs to optimize the smoking experience, but none of them have established a mechanism for real-time detection and feedback of cigarette flavoring components. This fails to meet consumers' needs for information on additives and makes it difficult to provide convenient on-site testing methods for the quality supervision of tobacco products.
[0004] Existing methods for detecting fragrances and flavorings are mostly laboratory tests, such as gas chromatography-mass spectrometry (GC-MS). Although GC-MS has high accuracy, it requires specialized instruments and operators and cannot achieve on-site, real-time detection. Traditional test strip methods can achieve simple colorimetric detection, but they suffer from low detection sensitivity, slow response speed, and poor color stability. Furthermore, the test strips have poor compatibility with cigarette filters, are prone to falling off, interfere with the flow of smoke, and are easily affected by moisture and impurities in the smoke, resulting in false positives. They cannot be integrated into the filter for integrated detection.
[0005] Meanwhile, if existing filters are directly integrated with testing reagents, the high temperatures of cigarette smoke can easily cause the reagents to decompose and the colorimetric reaction to become inaccurate. Furthermore, the reagents have poor load stability, leading to leakage and aggregation problems, which not only affect the testing results but also spoil the smoking experience. Therefore, developing a structure and manufacturing process that can be integrated into cigarette filters to achieve real-time, visual detection of flavorings and fragrances without affecting the original filtration and smoking performance of the filter has become an urgent technical problem to be solved in the field of tobacco product technology. Summary of the Invention
[0006] In view of the deficiencies of the prior art described in the background section, the purpose of this invention is to provide a method for preparing sensitive dye microcapsules and a cigarette filter with microcapsules, which solves the problems of existing cigarette flavor and fragrance detection relying on large instruments, cumbersome operation, easy leakage and poor stability of color developers, unreliable detection due to unreasonable filter structure, and lack of suitable microcapsule preparation process and dedicated detection structure, so as to realize on-site intuitive and stable detection of flavor and fragrance.
[0007] According to a first aspect of the present invention, a method for preparing sensitive dye microcapsules is provided. The sensitive dye microcapsules are used in a smart cigarette filter that integrates visual detection functions for fragrances and flavorings. The filter has a three-section coaxial structure, with a pre-filtration and cooling section, a central color-changing reaction chamber, and a terminal air permeability observation section arranged sequentially from the tobacco end to the inhalation end. A porous support is provided in the central color-changing reaction chamber. The microcapsule is composed of an outer layer of encapsulating material and an inner color-developing dye. The encapsulating material allows smoke molecules to pass through and prevents dye molecules from seeping out. The method includes the following steps: (S110) preparing an aqueous solution of sodium alginate, a calcium chloride crosslinking solution, a color-developing dye solution, and a surface-modified... Decorative solution; (S120) Sodium alginate is added to water and stirred to dissolve. After standing to remove bubbles, it is cooled, and a colorimetric dye is added, stirred and dispersed, and then filtered; (S130) The mixture is dropped into calcium chloride crosslinking solution and crosslinked at 20-25℃ for 2-4 hours to form microspheres; (S140) The microspheres are rinsed with deionized water and then freeze-dried under vacuum or vacuum dried at room temperature; (S150) The dried microspheres are immersed and shaken in a surface modifier solution, washed with water, and dried again to obtain microcapsules; (S160) The color values corresponding to different fragrance and flavor concentrations are detected by GC-MS, and colorimetric gradient patches are prepared based on the color values and the colorimetric card is calibrated.
[0008] Microcapsule materials are formed by the cross-linking reaction of sodium alginate and calcium chloride, encapsulating chromogenic dyes inside. The selective permeability of the material allows for the smooth passage of smoke molecules while effectively blocking dye molecules, preventing dye leakage, oral contamination, and loss with the smoke, thus improving safety. Drying and surface modification processes enhance the structural stability of the microcapsules, ensuring they do not break or detach under smoke circulation conditions, extending their lifespan. GC-MS detection and colorimetric calibration establish a correlation between the color gradient and the concentration of flavorings and fragrances, providing a precise and reliable reference for the subsequent visualization and semi-quantitative detection of flavorings and fragrances in cigarette filters, improving detection accuracy.
[0009] According to a second aspect of the present invention, a cigarette filter tip with microcapsules is provided, which is prepared by the method described in the above-mentioned claim and has a visual detection function for flavorings and fragrances. The filter tip has a coaxial three-section structure, consisting of a pre-filtration and cooling section, a middle color-changing reaction chamber, and a terminal air permeability observation section, from the tobacco end to the inhalation end. The pre-filtration section has a porous fiber structure. The middle color-changing reaction chamber is provided with a polylactic acid porous support bracket, and a coated sensitive dye microcapsule is constrained within the support bracket. The microcapsule consists of an outer layer of capsule material and an inner color-developing dye. The capsule material is permeable to smoke and prevents dye leakage. The terminal observation section is provided with an air permeable and liquid-resistant structure. The outer wall of the filter tip is provided with a transparent window and a colorimetric card. The colorimetric card and the window are at the same viewing angle. The colorimetric card has color gradient blocks corresponding to different concentrations. The filter tip has an outer diameter of 5.4 mm, a length of 31 ± 0.1 mm, and an overall draw resistance of 800-1200 Pa (ISO 3308 standard). All materials used are tobacco contact grade materials.
[0010] Through a three-section filter design, the front section cools and pre-filters the smoke, effectively reducing its temperature and removing impurities. This prevents high temperatures and impurities from affecting the colorimetric reaction and improves detection accuracy. The microcapsules in the middle section react specifically with the flavorings and fragrances in the smoke, while the capsule material allows smoke to pass through while blocking the dye, further preventing dye leakage and ensuring safe use. This also ensures a full and stable colorimetric reaction. The end section features a breathable and liquid-resistant structure to prevent liquid and dye leakage. A transparent window, combined with a colorimetric card, allows for rapid, intuitive, and semi-quantitative determination of flavoring and fragrance concentration by comparing colorimetric results with gradient color blocks, eliminating the need for large instruments and improving detection convenience. The overall structure and draw resistance are adapted to cigarette usage requirements, ensuring smooth smoking without affecting the original taste of the cigarette. It can directly replace traditional filters without modifying existing production equipment, reducing application costs. Attached Figure Description
[0011] Figure 1 is a flowchart of the process for preparing sodium alginate-based sensitive dye microcapsules in one embodiment of this application.
[0012] Figure 2 is a schematic diagram of the preparation and loading process of chitosan-based color-changing microspheres in one embodiment of this application.
[0013] Figure 3 shows an embodiment of Alizarin Red-Sr in this application. 2+ Flowchart of the process for preparing complex microcapsules.
[0014] Figure 4 is a schematic diagram of the colorimetric card preparation and filter tip composite assembly structure in one embodiment of this application.
[0015] Figure 5 is an axial cross-sectional view of a cigarette filter containing sensitive dye microcapsules in one embodiment of this application. Detailed Implementation
[0016] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0017] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, it should be noted that "multiple" means two or more, unless otherwise explicitly specified.
[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0019] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the horizontal thickness of the first feature is greater than that of the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the horizontal thickness of the first feature is less than that of the second feature.
[0020] The following disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or reference letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.
[0021] Example 1: Preparation method of sensitive dye microcapsules (see attached document) Figure 1 ) The core chemical reaction color change principle of this embodiment is: the sensitive dye undergoes a specific chemical reaction with the target flavoring and fragrance in cigarette smoke, causing the dye to change color. The color change effect is positively correlated with the concentration of flavoring and fragrance, thereby realizing the visual semi-quantitative detection of flavoring and fragrance. The following embodiments correspond to chemical reaction color change examples of different types of flavoring and fragrance, clarifying the core technical points of this embodiment.
[0022] This embodiment uses a sodium alginate-calcium chloride crosslinking method to prepare sensitive dye microcapsules. The core technology principle is to utilize the ionic crosslinking reaction between the carboxyl groups in sodium alginate molecules and the calcium ions in calcium chloride to form a three-dimensional network structure of the capsule material, which can achieve stable encapsulation of the colorimetric dye. At the same time, the selective permeability of the capsule material allows for both the permeability of flue gas molecules and the blocking of dye molecules. The core chemical reaction color change example of this patent is the acid-base color change reaction of phenol red. That is, after the evaporation of ethanol-based fragrances in the flue gas, the pH value of the system will be slightly changed, triggering a reversible color change reaction of phenol red (yellow when pH < 6.8, red when pH > 8.4). The specific steps are as follows: (S110) Preparation of raw material solutions: Prepare 2.0% (w / v) sodium alginate aqueous solution, 2.5% (w / v) calcium chloride crosslinking solution, 0.2% (w / v) phenol red colorimetric dye solution, and 1.0% (w / v) chitosan surface modifier solution respectively. All solutions are prepared with deionized water, stirred until completely dissolved, and set aside for later use. Among them, the chitosan surface modifier is used to enhance the binding force between microcapsules and polylactic acid scaffolds. Its technical principle is that the amino groups in chitosan molecules can form hydrogen bonds with the hydroxyl groups on the surface of polylactic acid scaffolds, thereby enhancing the adsorption force. The technical effect of this step is to ensure that the concentrations of each raw material are appropriate, providing a stable raw material system for subsequent crosslinking and surface modification, and avoiding incomplete microcapsule structure and unstable performance due to concentration deviation.
[0023] (S120) Preparation of the mixture: Take the above sodium alginate aqueous solution, place it in a constant temperature water bath stirrer, stir at 30℃ for 30 min until completely dissolved, let it stand for 20 h to degas, and then cool to room temperature. Slowly add the phenol red colorant dye solution, and continue stirring for 15 min until evenly dispersed. Filter with a 0.22 μm filter membrane to remove undissolved dye particles. The degassing treatment can avoid the generation of bubbles inside the microcapsules and ensure the integrity of the capsule structure. The technical principle is that the bubbles gradually rise during the standing process, avoiding bubbles from being wrapped inside the capsule material, which would cause the capsule material to have excessively large pores and dye leakage. The technical effect of this step is to make the sodium alginate and colorant dye fully mixed. Filtration to remove impurities can avoid undissolved dye particles from affecting the uniformity of microcapsule particle size. At the same time, the degassing treatment improves the density of the capsule material, laying the foundation for subsequent cross-linking and spheroidization.
[0024] (S130) Crosslinking into spheres: The filtered mixture is added dropwise to the calcium chloride crosslinking solution at a rate of 1 drop / second using a microsyringe. The mixture is kept at room temperature (23°C, preferably 20-25°C) and allowed to stand for 3 hours to form uniform microspheres. Uniform dropwise addition ensures uniform microcapsule size and avoids excessive particle size differences. The technical principle is that uniform dropwise addition ensures that the volume of each drop of mixture is consistent, resulting in uniform microsphere size in the calcium chloride solution. At the same time, room temperature crosslinking avoids degradation of sodium alginate due to excessively high temperature and incomplete crosslinking reaction due to excessively low temperature. The technical effect of this step is to form structurally stable microspheres through ionic crosslinking reaction. The encapsulation material can initially achieve dye encapsulation, and the particle size is uniform (subsequent testing showed that the particle size distribution coefficient CV < 15%), providing a qualified intermediate for subsequent drying and modification.
[0025] (S140) Microsphere Drying: The microspheres were rinsed three times with deionized water for 10 minutes each time to remove residual calcium chloride from the surface. Then, they were dried for 8 hours at -40℃ and 0.08MPa vacuum using a vacuum freeze-drying process to obtain preliminarily dried microspheres. Vacuum freeze-drying can prevent the microcapsules from deforming or breaking during the drying process and preserve the selective permeability of the capsule material. The technical principle is that vacuum freeze-drying allows the water inside the microspheres to directly sublimate into water vapor, avoiding the shrinkage and cracking of the capsule material caused by the evaporation of liquid water. At the same time, the low temperature environment can protect the activity of the color-developing dye and prevent the dye from changing color or becoming ineffective due to high temperature. The technical effect of this step is to completely remove the residual crosslinking agent on the surface of the microspheres, avoid the residual calcium chloride from affecting the color development reaction between the microcapsules and the fragrance, and at the same time, the dried microspheres have a loose and porous structure, which does not affect the subsequent flue gas permeability, and the dye is stably encapsulated inside the capsule material.
[0026] (S150) Surface modification and secondary drying: The dried microspheres are immersed in a chitosan surface modifier solution and shaken at 25°C for 1 hour. After removal, they are rinsed twice with deionized water and dried again using a vacuum freeze-drying process for 4 hours to obtain the finished sensitive dye microcapsules. The secondary drying can completely remove the surface moisture of the microcapsules and improve the structural stability. The technical principle is that chitosan surface modification can form a dense modification layer on the surface of the microcapsules, further enhancing the barrier performance of the capsule material. At the same time, the shaking treatment can make the chitosan evenly cover the surface of the microspheres, avoiding uneven local modification. The technical effect of this step is to improve the structural stability and dye barrier performance of the microcapsules, prevent the microcapsules from breaking and the dye from leaking in the flue gas environment, and enhance the bonding force between the microcapsules and the polylactic acid scaffold, preventing the microcapsules from being lost with the flue gas.
[0027] (S160) Colorimetric Card Calibration: Using a GC-MS instrument, the colorimetric values of different concentrations of ethanol-based flavorings and fragrances reacted with the microcapsules to develop color. Based on the obtained colorimetric data, five color patches with different concentration gradients were prepared to complete the standardization calibration of the universal colorimetric card. The technical principle is that the GC-MS instrument can accurately detect the concentration of flavorings and fragrances. By using a colorimeter to detect the colorimetric values after the microcapsules are developed, a "concentration-colorimetric" correspondence is established to ensure that the color of the color patch is consistent with the color of the microcapsule, providing a reference for visual detection. The technical effect of this step is to achieve the standardization calibration of the colorimetric card, providing an accurate reference for the subsequent visual semi-quantitative detection of cigarette filters, avoiding deviations in detection results due to the lack of standard color patches, and improving detection accuracy.
[0028] The prepared sensitive dye microcapsules have a particle size of 50-80 μm and a particle size distribution coefficient (CV) of <15%. The capsule material can pass through smoke molecules smoothly and effectively prevent phenol red dye from leaching out, and the structure is stable. Its core technological effect is to solve the problems of easy leakage and poor stability of traditional colorimetric reagents when added directly, and to achieve stable coating of colorimetric dyes. At the same time, the selective permeability of the capsule material can ensure that the smoke and dye can fully contact each other to produce a colorimetric reaction, providing a reliable functional carrier for the subsequent visual detection of cigarette filters.
[0029] Example 2: Preparation of chitosan-based color-changing microspheres (see attached document) Figure 2 ) This embodiment uses a chitosan-glutaraldehyde crosslinking method to prepare chitosan-based color-changing microspheres (a type of sensitive dye microcapsule). This is a special microsphere preparation process for ester fragrance detection. The core technology principle is to utilize the Schiff base reaction between the amino groups in chitosan molecules and the aldehyde groups in glutaraldehyde to form a crosslinked network structure, achieving stable encapsulation of bromocresol purple dye. Furthermore, the chitosan encapsulation material has a specific adsorption effect on ester fragrance molecules, which can improve colorimetric sensitivity. The core chemical reaction color change example of this patent is the pH-induced color change reaction of bromocresol purple. Ester fragrances undergo a hydrolysis reaction in flue gas to generate carboxylic acid (RCOOR' + H2O → RCOOH + R'OH). The carboxylic acid lowers the pH value of the system, causing bromocresol purple to change color (yellow when pH < 5.2, purple when pH > 6.8). The specific steps are as follows: (S210) Preparation of chitosan solution: Prepare a 1.5% (w / v) chitosan solution using 1.0% (v / v) glacial acetic acid as solvent. Stir for 30 min until completely dissolved and allow to stand for 16 h to remove bubbles. Glacial acetic acid solvent ensures that chitosan is fully dissolved. The technical principle is that glacial acetic acid can protonate the amino groups in chitosan molecules, breaking the hydrogen bonds between molecules, so that chitosan is uniformly dispersed in the aqueous solution. The degassing treatment avoids the formation of pores inside the microspheres. The technical effect of this step is to obtain a uniform, bubble-free chitosan solution, which provides a stable system for subsequent dye addition and emulsion preparation, and avoids uneven microsphere structure due to insufficient dissolution of chitosan.
[0030] (S220) Adding dye and filtering: Add 0.5% (w / v) bromocresol purple dye to the above chitosan solution, stir for 20 min until uniformly dispersed, and filter with a 0.22 μm filter membrane to remove impurities and undispersed dye particles; bromocresol purple is a special color developing dye for ester fragrances. Its technical principle is that bromocresol purple is a pH indicator. Ester fragrances undergo hydrolysis in flue gas, changing the pH value of the system and causing bromocresol purple to change color; the technical effect of this step is to uniformly disperse bromocresol purple dye in the chitosan solution. Filtering to remove impurities can avoid undispersed dye affecting the color uniformity of microspheres and ensure that the subsequent color developing reaction is stable and consistent.
[0031] (S230) Preparation of emulsion: Add the dye-chitosan mixture to liquid paraffin, add a small amount of Tween-80 emulsifier, and stir at high speed for 15 minutes to form a uniform oil-in-water emulsion; the emulsification treatment can ensure that the dye-chitosan mixture is uniformly dispersed. The technical principle is that Tween-80, as a non-ionic emulsifier, can reduce the interfacial tension between the aqueous phase and the oil phase, so that the dye-chitosan mixture (aqueous phase) is uniformly dispersed in the liquid paraffin (oil phase) to form tiny droplets, which lays the foundation for subsequent cross-linking into spheres; the technical effect of this step is to form an oil-in-water emulsion with uniform particle size, ensuring that the subsequent cross-linking reaction can occur uniformly on the surface of each droplet, and obtain microspheres with consistent particle size.
[0032] (S240) Crosslinking reaction: Slowly add 2.0% (w / v) glutaraldehyde crosslinking solution to the emulsion, controlling the dropping rate to 0.5 mL / min. After the addition is complete, stir at 30℃ for 2.5 h for crosslinking. Glutaraldehyde is a special crosslinking agent. Its technical principle is that glutaraldehyde, as a bifunctional aldehyde crosslinking agent, can react with the amino groups in chitosan molecules to form a stable three-dimensional network structure, which encapsulates the bromocresol purple dye inside. The technical effect of this step is that the emulsion droplets form structurally stable microspheres through the crosslinking reaction. The encapsulation material has good density and can effectively block dye leakage. At the same time, the mechanical strength of the crosslinked microspheres is improved, which can adapt to the assembly and use environment of the filter tip.
[0033] (S250) Microsphere post-treatment: The reaction mixture was centrifuged at 3000 r / min for 10 min, and the microspheres were collected. They were washed three times with anhydrous ethanol for 5 min each time to remove residual liquid paraffin and unreacted reagents from the surface. Then, they were freeze-dried under vacuum for 6 h to obtain chitosan-based color-changing microspheres. Centrifugation can quickly collect microspheres. The principle is that centrifugal force can cause microspheres with a density greater than that of liquid to settle, thus separating the microspheres from the emulsion system. Washing with anhydrous ethanol can thoroughly remove impurities. The principle is that anhydrous ethanol can dissolve liquid paraffin and unreacted glutaraldehyde, and it is volatile and will not leave residues on the surface of the microspheres. The technical effect of this step is to obtain chitosan-based color-changing microspheres with high purity and stable structure. Removing impurities can avoid affecting the accuracy of subsequent color development reactions. After drying, the microspheres have a stable structure, which is convenient for subsequent loading onto the filter holder.
[0034] (S260) Loading and Calibration: The microspheres are loaded onto a polylactic acid porous scaffold with a porosity of 65% using an impregnation method. The loading amount is 4% of the scaffold weight (within the specified loading range). The loaded scaffold is then assembled into a filter tip and subjected to a colorimetric reaction with different concentrations of ester flavorings and fragrances. The ester-specific colorimetric card is then calibrated. The impregnation method is a dedicated loading method for microspheres. Its technical principle is that the polylactic acid porous scaffold has a high porosity and specific surface area, which can fix the microspheres in the pores of the scaffold through adsorption. Controlling the loading amount within a reasonable range can ensure sufficient colorimetric reaction while avoiding excessive microspheres that may affect flue gas flow. The technical effect of this step is to achieve uniform loading of microspheres on the scaffold, preventing microspheres from falling off or agglomerating. The calibrated colorimetric card can accurately correspond to different concentrations of ester flavorings and fragrances, achieving semi-quantitative detection of ester flavorings and fragrances, and improving the targeting and accuracy of the detection.
[0035] The prepared chitosan-based color-changing microspheres have a particle size of 50-80 μm and a particle size distribution coefficient (CV) of <15%. After loading, they are evenly distributed on the scaffold and are not easily detached. They can produce specific color development with ester-based fragrances and flavors. The core technical effect is to achieve specific color development for ester-based fragrances and flavors, which solves the problem that traditional microcapsules are not very specific for detecting different types of fragrances. At the same time, the chitosan encapsulation material has better barrier properties and mechanical strength, which further improves the service life and color development stability of the microcapsules.
[0036] Example 3 Alizarin Red-Sr 2+ Preparation of complex microcapsules (see attached document) Figure 3 ) This embodiment uses spray drying to prepare Alizarin Red-Sr 2+ Complex microcapsules (a type of sensitive dye microcapsule) are a special microcapsule preparation process for the detection of aromatic aldehyde fragrances. The core technology principle is to first synthesize alizarin red-Sr through the reaction of alizarin red and strontium nitrate. 2+ The complex can undergo a specific complexation and dissociation reaction with aromatic aldehydes to achieve color development. The composite capsule material is then mixed with the complex and dried into capsules using a spray drying process. The selective permeability of the composite capsule material allows for both smoke permeation and complex fixation. The core chemical reaction color change example in this patent is Alizarin Red-Sr. 2+ The competitive complexation color change reaction of the complex is specifically represented by the following reaction formula: Alizarin Red-Sr 2+ (Red) + Aromatic Aldehyde (RCHO) → Alizarin Red (Yellow) + Sr 2+ -Aromatic aldehyde complexes, aromatic aldehyde fragrance molecules and Sr 2+ The complexing ability of the compound is stronger than that of alizarin red, causing the complex to dissociate and alizarin red to change color significantly. The specific steps are as follows: (S310) Preparation of composite capsule solution: Mix 1.8% (w / v) sodium alginate solution and 0.8% (w / v) chitosan solution at a volume ratio of 1:1 and stir for 20 min to form a uniform composite capsule solution; the composite capsule is a special capsule combination. The technical principle is that sodium alginate has good film-forming and cross-linking properties, while chitosan has good barrier and biocompatibility. The combination of the two can take into account both flue gas permeability and dye barrier properties, and improve the stability of microcapsules; the technical effect of this step is to obtain a uniform composite capsule solution with complementary capsule properties, which can effectively encapsulate complexes and ensure that flue gas molecules pass through smoothly, providing qualified raw materials for subsequent spray drying and capsule formation.
[0037] (S320) Preparation of complex solution: A 0.4% (w / v) alizarin red solution and a 0.3% (w / v) strontium nitrate solution were mixed at a volume ratio of 1:1 and stirred at room temperature for 1 h to synthesize alizarin red-Sr 2+ Complex solution; Alizarin Red-Sr 2+The complex is a colorimetric system specifically for aromatic aldehyde fragrances. Its technical principle is the reaction between alizarin red and Sr. 2+ A stable complex is formed. When aromatic aldehyde fragrance molecules come into contact with the complex, they react with Sr. 2+ Competitive complexation occurs, leading to the dissociation of alizarin red and a color change, thus enabling the specific detection of aromatic aldehyde fragrances; the technical advantage of this step is the synthesis of stable alizarin red-Sr 2+ The complex ensures a specific colorimetric reaction with aromatic aldehydes, resulting in high colorimetric sensitivity (subsequent testing showed that the detection limit for benzaldehyde could reach 5 ppm).
[0038] (S330) Mixed Solution: Slowly add the complex solution to the composite capsule material solution and stir continuously for 30 minutes to ensure uniform mixing and form a capsule material-complex mixture. Thorough stirring ensures that the complex is uniformly dispersed in the capsule material. The technical principle is that continuous stirring can break the intermolecular forces of the complex, so that the complex is uniformly dispersed in the composite capsule material solution, avoiding uneven color development caused by excessively high local complex concentration. The technical effect of this step is to fully mix the complex with the composite capsule material, laying the foundation for subsequent spray drying and encapsulation, ensuring that each microcapsule contains a uniformly distributed complex, and ensuring uniform and stable color development reaction.
[0039] (S340) Spray drying encapsulation: The mixture is fed into a spray dryer, with the inlet air temperature set to 120℃ and the outlet air temperature to 60℃ (spray drying parameters specified), the feed rate to 5mL / min, and the atomization pressure to 0.2MPa. After drying, alizarin red-Sr is obtained. 2+ Complex microcapsules; these parameters ensure uniform microcapsule particle size and structural integrity. The technical principle is that an inlet air temperature of 120℃ can quickly evaporate the moisture in the mixture, while an outlet air temperature of 60℃ can prevent the complex from decomposing and becoming ineffective due to high temperature. An atomization pressure of 0.2MPa can atomize the mixture into tiny droplets, which, after drying, form microcapsules with uniform particle size. The technical effect of this step is to rapidly prepare complex microcapsules with complete structure and uniform particle size. The composite capsule material can effectively encapsulate the complex and prevent its loss. At the same time, the porous surface of the microcapsule does not affect the permeability of flue gas and improves the efficiency of the colorimetric reaction.
[0040] (S350) Microcapsule loading: The above-mentioned microcapsules are loaded onto a polylactic acid porous scaffold using an electrospinning drug loading process. The microcapsules are then fixed within the pores of the scaffold using an electrospinned fiber membrane. The loading amount is 3.5% of the scaffold weight (within the specified loading range). The electrospinning process is a dedicated loading method. Its technical principle is that electrospinning can produce fiber membranes with small pore sizes and large specific surface areas. The fiber membrane can firmly fix the microcapsules within the scaffold pores through electrostatic adsorption, preventing the microcapsules from being lost with the flue gas. The technical effect of this step is to achieve a firm and uniform loading of the microcapsules on the scaffold, without affecting the flow of flue gas. At the same time, the fiber membrane can further prevent the microcapsules from falling off, thus improving the service life of the filter.
[0041] (S360) Colorimetric Card Calibration: The microcapsule-loaded support is assembled onto the filter tip and subjected to a colorimetric reaction with different concentrations of aromatic aldehyde fragrances to calibrate a dedicated colorimetric card for aromatic aldehydes, wherein the detection limit for benzaldehyde is 5 ppm (specified detection limit requirement); the technical principle is that different concentrations of aromatic aldehyde fragrances will lead to different degrees of complex dissociation and differences in color development depth. By GC-MS detection and calibration, a correspondence between concentration and color development depth is established; the technical effect of this step is to achieve high-sensitivity detection of aromatic aldehyde fragrances, with a detection limit of up to 5 ppm, meeting actual detection needs, while the dedicated colorimetric card can improve the accuracy and convenience of detection.
[0042] Alizarin Red-Sr prepared 2+ The microcapsules of the complex have a particle size of 60-75μm and an intact structure. The composite capsule material can effectively encapsulate the complex without leakage, and the colorimetric sensitivity meets the requirements. Its core technological effect is to achieve high sensitivity and specific colorimetric detection of aromatic aldehydes, which solves the problem of insufficient detection accuracy of traditional detection methods for low concentrations of aromatic aldehydes. At the same time, the spray drying process has high preparation efficiency, which can realize large-scale production and reduce production costs.
[0043] Example 4: Preparation and composite assembly of colorimetric cards (see attached document) Figure 4 ) This embodiment prepares three types of colorimetric cards and assembles them with the outer surface of the filter tip. The core technical principle is to prepare color blocks with corresponding concentration gradients based on the color development characteristics of different types of microcapsules. By comparing the color development results of the color blocks with those of the microcapsules, a semi-quantitative determination of the concentration of fragrance and flavor can be achieved. At the same time, the stability and ease of use of the colorimetric cards are ensured through coating and bonding processes. The specific steps are as follows: (S410) Design colorimetric cards: Colorimetric cards are divided into general type, ester-specific type and aromatic aldehyde-specific type. Each colorimetric card has 8 concentration gradient color blocks (the number of color blocks is specified to be 5-10), covering the common concentration range of the corresponding fragrances and flavors. The three types of colorimetric cards correspond to three types of microcapsules. The technical principle is that different types of microcapsules have different color development colors and sensitivities with the corresponding fragrances and flavors. Dedicated colorimetric cards can ensure the accuracy of comparison and avoid interference from different types of fragrances. The technical effect of this step is to achieve precise matching between colorimetric cards and microcapsules, cover the common fragrance concentration range, provide targeted references for the detection of different types of fragrances, and improve the accuracy of detection.
[0044] (S420) Controlling color difference of color patches: By adjusting the colorimeter, ensure that the color difference ΔE of adjacent color patches is greater than 5 (CIE-Lab standard), and that the color of the color patch is consistent with the color development color of the corresponding sensitive dye microcapsule; color difference control can ensure accurate comparison of color development results. The technical principle is that the CIE-Lab standard can accurately describe color differences, and ΔE > 5 can ensure that the human eye can clearly distinguish adjacent color patches, avoiding comparison errors caused by too small color differences; the technical effect of this step is to ensure that the color of the color patch is clearly distinguishable and accurately matches the color development result of the microcapsule, reduce comparison errors, and improve the accuracy and reliability of detection.
[0045] (S430) Printing color blocks: Using food-grade heat-resistant tobacco ink, color blocks are printed on antibacterial coated paper (0.08mm thick, specified substrate thickness 0.05-0.1mm) that is the same as the filter outer sheath, with printing accuracy controlled at 0.01mm; food-grade ink ensures safe use, and its technical principle is that food-grade ink does not contain harmful substances and will not cause pollution when in contact with the oral cavity. Heat-resistant ink can prevent the color blocks from fading or deforming due to high temperatures during smoking; the technical effect of this step is to obtain color blocks with uniform color and high accuracy. The ink is safe and non-toxic, meets the requirements of tobacco materials, and the high printing accuracy ensures that the color block size is uniform and easy to compare.
[0046] (S440) Lamination Treatment: On the surface of the printed substrate, a waterproof and heat-resistant polymer film is laminated using a hot-pressing process. The hot-pressing temperature is 70℃ (specified hot-pressing temperature 60-80℃), the pressure is 0.15MPa (specified pressure 0.1-0.2MPa), and the lamination time is 10s. The lamination can prevent the color blocks from getting damp and fading. The technical principle is that the polymer film has good waterproof, heat-resistant, and wear-resistant properties, which can isolate moisture and oxygen in the air and prevent the ink of the color blocks from oxidizing and fading. Hot-pressing can ensure that the film is tightly bonded to the substrate. The technical effect of this step is to improve the service life and stability of the color chart, avoid fading and blurring of the color blocks due to moisture and wear, and ensure accurate comparison results during long-term use.
[0047] (S450) Bonding and Assembly: The coated colorimetric card is bonded to the outer surface of the antibacterial coated paper of the filter tip outer sheath using food-grade pressure-sensitive adhesive (adhesive layer thickness 0.025mm, specified adhesive layer thickness 0.02-0.03mm), arranged on the same side as the transparent window, ensuring a smooth bond. The food-grade pressure-sensitive adhesive meets the requirements for tobacco contact materials. Its technical principle is that the food-grade pressure-sensitive adhesive has moderate adhesion, which can firmly bond the colorimetric card to the outer surface of the filter tip without producing harmful substances. The moderate adhesive layer thickness can prevent bulging or curling after bonding. The technical effect of this step is to achieve a firm and smooth bond between the colorimetric card and the filter tip, without affecting the appearance and use of the filter tip. At the same time, the arrangement on the same side as the transparent window makes it convenient for users to observe the color development results and make quick comparisons, improving the ease of use.
[0048] (S460) Rolling and Inspection: The bonded colorimetric cards are rolled twice (2-3 times as specified), with a rolling pressure of 0.08 MPa (0.05-0.1 MPa as specified) and a rolling speed of 5 cm / min. The integrity of the color patches, the sealing of the film, and the bonding strength are then inspected to ensure no bubbles, no curling, and no misalignment. Rolling improves bonding strength because the rolling pressure allows the pressure-sensitive adhesive to fully contact the substrate, expelling air and preventing bubble formation, while simultaneously enhancing bonding strength. The inspection step ensures the colorimetric cards are assembled correctly. The technical effect of this step is to ensure the colorimetric cards are firmly bonded and free of defects, preventing curling and bubbles during use that could blur the color patches and affect the comparison results. Passing the inspection also ensures the consistency of the colorimetric cards.
[0049] Example 5: Cigarette filter with microcapsules (see attached) Figure 5 ) This embodiment uses sensitive dye microcapsules prepared by any one or a combination of steps in Examples 1-4 above to prepare cigarette filters containing microcapsules. The core technical principle is to achieve the integration of smoke pretreatment, colorimetric reaction, and observation comparison through a three-stage partitioned design. The pre-stage cooling and filtration, the middle stage colorimetric reaction, and the end stage observation blocking, with each stage working synergistically, achieves visualized semi-quantitative detection of flavorings and fragrances, while ensuring safe use and smooth vaping. The specific assembly process is as follows: 1. Preparation of each section of the three-section filter: The pre-filter cooling section uses cellulose acetate filter cotton (porous fiber structure), 12mm in length (accounting for 38.7% of the total filter length, meeting the 30%-40% ratio requirement); the technical principle is that cellulose acetate filter cotton has good filtration performance and thermal conductivity, which can filter particulate impurities in flue gas, while quickly conducting heat from the flue gas, reducing the flue gas temperature, and providing a suitable environment for the color development reaction in the middle section (avoiding high temperature affecting the color development effect); the middle color-changing reaction chamber uses a polylactic acid porous support (porosity 65%), 15mm in length (accounting for 48.4% of the total filter length, meeting the 40%-50% ratio requirement), and the sensitive dye microcapsules prepared in Example 1 are constrained and fixed in the pores of the support in a thin layer form; the technical principle is that the polylactic acid porous support has high porosity and high thermal conductivity. The large surface area allows for uniform loading of microcapsules, while the porous structure ensures uniform gas flow and full contact with the microcapsules, guaranteeing a thorough colorimetric reaction. The end-stage permeable observation section uses a transparent microporous polymer membrane, 4mm in length (accounting for 12.9% of the total filter length, meeting the 10%-20% ratio requirement), with an internal permeable liquid-blocking barrier (pore size smaller than the microcapsules and dye molecules). The technical principle is that the transparent microporous polymer membrane allows for gas exhaust, while the liquid-blocking barrier prevents microcapsules and dye from seeping out, avoiding oral contamination. The transparent material facilitates observation of the colorimetric results in the middle stage. The technical effect of this step is to prepare filter sections with clearly defined functional zones and qualified performance. The pre-stage section achieves gas pretreatment, the middle stage provides a carrier for the colorimetric reaction, and the end stage enables observation and barrier, laying the foundation for subsequent assembly.
[0050] 2. Assemble a three-section structure: The pre-filter cooling section, the middle color-changing reaction chamber, and the end air permeability observation section are coaxially connected and tightly joined to form a three-section coaxial filter body. The overall outer diameter of the filter is 5.4mm, the total length is 31±0.1mm, and the overall draw resistance is controlled at 1000Pa (ISO3308 standard, specified draw resistance range 800-1200Pa). The technical principle is that the coaxial connection ensures smooth flow of smoke along the filter axis, avoiding smoke leakage. The size design conforms to the standard of slim cigarettes, and the draw resistance is controlled within a reasonable range to ensure smooth drawing without affecting the original taste of the cigarette. The technical effect of this step is to obtain a filter body with complete structure, qualified size, smooth drawing, tight connection of each section, no smoke leakage, and suitable draw resistance. It can directly replace traditional slim cigarette filters without modifying existing production equipment.
[0051] 3. Assembly of the outer sheath and viewing window: The filter tip outer sheath adopts a composite structure of antibacterial coated paper (containing silver ion antibacterial components, antibacterial rate ≥99%) and transparent viewing window (polycarbonate PC material, light transmittance ≥95%). The transparent viewing window is set at the positions of the central color-changing reaction chamber and the end ventilation observation section, and is sealed and bonded to the outer sheath. The technical principle is that the silver ion antibacterial components can inhibit the growth of bacteria on the filter tip surface, improving the hygiene of use. The polycarbonate PC material has high light transmittance and good mechanical strength, allowing clear observation of the color development results in the central section. The sealed bonding can prevent smoke from leaking from the gap between the viewing window and the outer sheath. The technical effect of this step is to achieve the antibacterial, sealing and observation functions of the filter tip. The outer sheath is antibacterial and hygienic, the transparent viewing window allows clear light transmission, making it easy for users to observe the color development results, and the good sealing performance prevents smoke leakage, thus improving the user experience.
[0052] 4. Composite Colorimetric Card: The universal colorimetric card prepared in Example 4 is attached to the outer side of the filter tip's outer sheath, adjacent to the transparent window, and placed at the same viewing angle. This ensures that the color blocks are arranged along the filter tip's axis, and the edge of the window is flush with the edge of the colorimetric card. The technical principle is that the same viewing angle allows the user to simultaneously observe the color development results in the window and the color blocks on the colorimetric card, enabling rapid comparison. The axial arrangement ensures that the color blocks correspond to the color development areas, improving the convenience of comparison. When the user inhales, the smoke carries flavoring molecules into the central color-changing reaction chamber, triggering the corresponding chemical reaction color change (ethanol-based flavorings trigger phenol red acid-base color change, ester-based flavorings trigger bromocresol purple pH color change, aromatic aldehyde flavorings trigger alizarin red-Sr...). 2+ (The color changes due to complexation and dissociation). By observing the color through a transparent window and comparing it with the corresponding concentration color block on the colorimetric card, a semi-quantitative determination of the concentration of fragrance and flavor can be achieved.
[0053] The invention relates to a cigarette filter with sensitive dye microcapsules. Its core application focuses on the flow trajectory of smoke within the filter during cigarette smoking, the physical and chemical changes occurring in each functional segment, and how users can intuitively identify the concentration of flavorings and fragrances in cigarettes. The specific process is as follows, fully conforming to the three-segment structure design of the filter, clearly demonstrating the practical application of the technical principles: When a user inhales a cigarette equipped with the filter of this invention, smoke is generated from the combustion end of the cigarette and first enters the pre-filtration and cooling section (cellulose acetate filter cotton, 12mm in length) of the filter at a speed of 1-2m / s. The smoke flows through this section for approximately 0.01-0.02s, during which the smoke undergoes its first physical change: solid particles (such as tar particles) carried in the smoke are intercepted and filtered by the porous structure of the cellulose acetate filter cotton, achieving a filtration efficiency of over 85%. Simultaneously, the high temperature of the smoke (approximately 60-80℃) is rapidly conducted away by the thermally conductive cellulose acetate, reducing the smoke temperature to 30-40℃. This reaches the suitable temperature conditions for the color development reaction in the middle section, preventing high temperatures from damaging the activity of sensitive dyes and ensuring the stability of subsequent chemical reactions. This process involves only physical filtration and cooling, without any chemical reaction. Its core function is to pre-treat the smoke, providing a clean and suitable environment for the color development reaction.
[0054] After pretreatment in the pre-filter section, the smoke continues to flow axially along the filter tip at a velocity maintained at 0.8-1.5 m / s, entering the central color-changing reaction chamber (polylactic acid porous support, 15 mm in length). The smoke's flow time in this section is approximately 0.01-0.03 s; this is the region where the core chemical reaction occurs and is a crucial step in fragrance concentration detection. Within the pores of the polylactic acid porous support in the central section, microcapsules of corresponding sensitive dyes are uniformly loaded (phenol red microcapsules for ethanol-based fragrances, bromocresol purple microspheres for ester-based fragrances, and alizarin red-Sr for aromatic aldehyde-based fragrances). 2+ (Complex microcapsules) The fragrance and flavor molecules carried by the smoke pass through the pores of the support with the airflow and come into contact with the microcapsule material. Due to the selective permeability of the material, the smoke and fragrance molecules can easily penetrate the material and undergo a specific chemical reaction with the sensitive dyes inside the capsule. The reaction time is about 0.005-0.01s. At the same time, the material can effectively block the dye molecules from seeping out and avoid contaminating the oral cavity.
[0055] The specific chemical reactions and color changes triggered by different types of flavorings are as follows: If the cigarette contains ethanol-based flavorings, the ethanol molecules in the smoke will slightly change the pH value of the system inside the cigarette, triggering a reversible acid-base color change of phenol red (yellow when pH < 6.8, red when pH > 8.4); if it contains ester-based flavorings, the ester molecules undergo a hydrolysis reaction in the mild environment of the smoke (RCOOR' + H2O → RCOOH + R'OH), and the generated carboxylic acid lowers the pH value of the system, causing bromocresol purple to change color (yellow when pH < 5.2, purple when pH > 6.8); if it contains aromatic aldehyde flavorings, the aromatic aldehyde molecules will react with alizarin red-Sr 2+ The complex undergoes a competitive complexation reaction (Alizarin Red-Sr) 2+ (Red) + Aromatic Aldehyde (RCHO) → Alizarin Red (Yellow) + Sr 2+-Aromatic aldehyde complexes), leading to the dissociation of the complex and a significant change in the color of alizarin red. Furthermore, the depth of this color change is positively correlated with the concentration of the fragrance: the higher the concentration, the more complete the reaction and the deeper the color; the lower the concentration, the lighter the color. This is the core basis for achieving semi-quantitative detection.
[0056] After the chemical reaction is complete, the smoke continues to flow to the end-stage permeable observation section (a transparent microporous polymer membrane, 4mm in length). The smoke flows for approximately 0.003-0.008 seconds in this section, where a second physical change occurs: the smoke is smoothly discharged through the microporous structure of the transparent microporous polymer membrane, meeting the user's inhalation needs. Simultaneously, the permeable and liquid-resistant barrier layer inside the membrane (with pores smaller than the microcapsules and dye molecules) further blocks the microcapsule particles and dye molecules, completely preventing them from seeping out with the smoke, ensuring safe and hygienic use. Because the end-stage observation section is made of transparent polycarbonate (PC) material and is tightly connected to the central color-changing reaction chamber, users can clearly observe the color development of the microcapsules in the central section through a transparent window, intuitively obtaining the color information after the fragrance reaction.
[0057] The user-identified flavor concentration is extremely convenient, requiring no professional instruments and only two steps: First, take 3-5 puffs of a cigarette (each puff lasts approximately 2-3 seconds, with an interval of approximately 5-8 seconds between puffs to ensure sufficient contact between the smoke and the microcapsules, allowing the reaction to reach a stable state where the color depth no longer changes significantly); Second, compare the color of the central section within the transparent window with a dedicated colorimetric card located next to the window on the filter's outer sheath—the colorimetric card has 8 concentration gradient color blocks, with a color difference ΔE > 5 between adjacent color blocks, making them clearly distinguishable. The user only needs to find the color block that is closest to the color in the window to quickly determine the concentration range of the corresponding type of flavoring in the cigarette, achieving visual semi-quantitative detection. The entire identification process takes no more than 10 seconds.
[0058] Throughout the process, the smoke flows smoothly and continuously within the filter, with the draw resistance controlled at 800-1200Pa (ISO3308 standard), without affecting the original smoking experience of the cigarette. Physical filtration, cooling, and chemical colorimetric reactions work together, enabling convenient detection of flavor concentration while ensuring safe use. This perfectly solves the pain points of traditional detection methods, which are cumbersome to operate and cannot be directly observed on-site, fully demonstrating the practicality and convenience of this invention.
[0059] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application.
Claims
1. A method for preparing sensitive dye microcapsules, characterized in that, The sensitive dye microcapsules are used in cigarette filters equipped with microcapsules that integrate visual detection functions for fragrances and flavors. The filter has a three-section coaxial structure, consisting of a pre-filtration and cooling section, a central color-changing reaction chamber, and a terminal air permeability observation section, arranged sequentially from the tobacco end to the inhalation end. The central color-changing reaction chamber is equipped with a porous support. The microcapsules consist of an outer layer of encapsulation material and an inner color-developing dye. The encapsulation material allows smoke molecules to pass through while preventing dye molecules from seeping out. The method includes the following steps: (S110) Prepare sodium alginate aqueous solution, calcium chloride crosslinking solution, color developing dye solution and surface modifier solution; (S120) Add sodium alginate to water and stir to dissolve. After standing to remove bubbles, cool and add colorimetric dye, stir to disperse and filter. (S130) The mixture is dropped into the calcium chloride crosslinking solution and crosslinked at 20-25℃ for 2-4 hours to form microspheres; (S140) The microspheres are rinsed with deionized water and then freeze-dried or vacuum dried at room temperature. (S150) The dried microspheres are immersed and shaken in a surface modifier solution, washed with water and dried again to obtain microcapsules; (S160) GC-MS was used to detect the color values corresponding to different fragrance and flavor concentrations. Color gradient patches were prepared based on the color values and the colorimetric card was calibrated.
2. The method for preparing sensitive dye microcapsules according to claim 1, characterized in that, The concentration of the sodium alginate aqueous solution was 2.0% (w / v), the concentration of the calcium chloride crosslinking solution was 2.5% (w / v), the concentration of the colorimetric dye solution was 0.2% (w / v), the crosslinking time was 3 hours, and the drying method was vacuum freeze drying. The resulting sensitive dye microcapsules had a particle size of 50-80 μm and a particle size distribution coefficient (CV) < 15%. The microcapsules were distributed in a thin layer within a porous support structure. The encapsulation material sealed the colorimetric dye inside. The colorimetric card was placed on the outer wall of the filter tip and located at the same observation angle as the observation area.
3. A method for preparing sensitive dye microcapsules, characterized in that, The sensitive dye microcapsules are used in cigarette filters with integrated fragrance and flavor visualization detection functions. The filter has a three-section coaxial structure, consisting of a pre-filtration and cooling section, a central color-changing reaction chamber, and a terminal air permeability observation section, arranged sequentially from the tobacco end to the inhalation end. The central color-changing reaction chamber is equipped with a porous support. The microcapsules consist of an outer layer of encapsulating material and an inner color-developing dye. The encapsulating material allows smoke molecules to pass through while preventing dye molecules from leaching out. The method is used to prepare chitosan-based color-changing microspheres using a chitosan-glutaraldehyde crosslinking method. The method includes the following steps: (S210) Prepare a chitosan solution with a concentration of 1.5% (w / v) using 1.0% (v / v) glacial acetic acid as solvent, stir and let stand to remove bubbles; (S220) Add 0.5% (w / v) bromocresol purple dye to the chitosan solution, disperse evenly, and then filter to remove impurities; (S230) The dye-chitosan mixture is placed in liquid paraffin, and an emulsifier is added to form an oil-in-water emulsion; (S240) Add glutaraldehyde crosslinking solution with a concentration of 2.0% (w / v) and crosslink at 30℃ for 2.5 h; (S250) The microspheres were centrifuged, washed with anhydrous ethanol, and then freeze-dried under vacuum. (S260) Microspheres were loaded onto a polylactic acid porous scaffold by impregnation, and then colorimetrically determined with ester fragrances and flavors to obtain a special colorimetric card.
4. The method for preparing the sensitive dye microcapsules according to claim 3, characterized in that, The polylactic acid porous scaffold has a porosity of 65%, and the loading of chitosan-based color-changing microspheres is 4% of the scaffold weight. The microspheres have a particle size of 50-80 μm and a particle size distribution coefficient (CV) < 15%. During calibration, a colorimeter was used to measure the Lab color after development. The colorimetric value was determined by GC-MS to measure the actual concentration of the corresponding ester fragrance and flavor and to establish the correspondence between the colorimetric value and the concentration. The microspheres were fixed in the pores of the support and a special colorimetric card was set with multiple gradient color blocks. The color of the color block was consistent with the color development of the microspheres at the corresponding fragrance and flavor concentration.
5. A method for preparing sensitive dye microcapsules, characterized in that, The sensitive dye microcapsules are used in cigarette filters with integrated fragrance and flavor visualization detection functions. The filter has a three-section coaxial structure, consisting of a pre-filtration and cooling section, a central color-changing reaction chamber, and a terminal air permeability observation section, arranged sequentially from the tobacco end to the inhalation end. The central color-changing reaction chamber contains a porous support structure. The microcapsules consist of an outer layer of encapsulating material and an inner color-developing dye. The encapsulating material allows smoke molecules to pass through while preventing dye molecules from leaching out. The method is used to prepare Alizarin Red-Sr. 2+ Complex microcapsules are prepared by spray drying, the method comprising the following steps: (S310) Mix 1.8% (w / v) sodium alginate solution and 0.8% (w / v) chitosan solution at a volume ratio of 1:1 to form a composite capsule material solution; (S320) Mix 0.4% (w / v) alizarin red solution and 0.3% (w / v) strontium nitrate solution at a volume ratio of 1:1 and stir at room temperature for 1 h to form a complex solution; (S330) Add the complex solution to the composite capsule material solution and stir for 30 min; (S340) The mixture is fed into a spray dryer and microcapsules are obtained under the conditions of inlet air temperature of 120°C and outlet air temperature of 60°C. (S350) Microcapsules are loaded onto a polylactic acid porous scaffold via electrospinning and then bound and fixed by a fiber membrane; (S360) is used to perform colorimetric determination with aromatic aldehyde fragrances and flavors to obtain a corresponding special colorimetric card.
6. The method for preparing the sensitive dye microcapsules according to claim 5, characterized in that, Alizarin Red-Sr 2+ The microcapsule size of the complex is 60-75μm. The loading of the microcapsules on the polylactic acid porous scaffold is 3.5% of the scaffold weight. The color difference ΔE between the colorimetric card and the colorimetric endpoint is ≤1. The detection limit of benzaldehyde is 5ppm. The microcapsules are dispersed and fixed inside the pores of the scaffold. The composite capsule material completely encapsulates the internal complex. The colorimetric card is set on the outside of the filter tip and is circumferentially adjacent to the transparent window. The color blocks are arranged along the axial direction of the filter tip. The number of color blocks is 5-10. The color difference ΔE between adjacent color blocks is >5 (CIE-Lab).
7. The method according to any one of claims 1-6, characterized in that, The method is used for colorimetric card preparation and composite assembly with filter tips, and the method includes the following steps: (S410) The colorimetric cards are divided into general type, ester-specific type and aromatic aldehyde-specific type, and each colorimetric card has 5-10 concentration gradient color blocks; (S420) Control the color difference ΔE > 5 between adjacent color blocks (CIE-Lab) to ensure that the color of the color block is consistent with the color of the corresponding microcapsule; (S430) Color blocks are printed on the substrate using food-grade heat-resistant smoke-resistant ink; (S440) A waterproof and heat-resistant polymer film is laminated onto the surface of the printed substrate; (S450) The coated colorimetric card is attached to the surface of the filter tip outer sheath with food-grade pressure-sensitive adhesive and arranged on the same side as the transparent window; (S460) Roll and compact the bonded colorimetric card, and test the integrity of the color block, the sealing of the film and the bonding firmness of the filter tip.
8. The method for preparing the sensitive dye microcapsules according to claim 7, characterized in that, The colorimetric card substrate uses the same antibacterial coated paper as the filter tip outer sheath, with a substrate thickness of 0.05-0.1mm. The lamination is performed using a hot-pressing process, with a hot-pressing temperature of 60-80℃ and a pressure of 0.1-0.2MPa. The thickness of the pressure-sensitive adhesive layer is 0.02-0.03mm. After the colorimetric cards are bonded, they are rolled 2-3 times with a rolling pressure of 0.05-0.1MPa. The colorimetric cards are arranged along the filter tip axis and are on the same observation surface as the transparent window. The lamination completely covers the color patch area, and the adhesive layer is evenly distributed. After rolling, there are no bubbles, warping, or misalignment between the colorimetric cards and the outer wall of the filter tip.
9. A cigarette filter tip with microcapsules, characterized in that, The sensitive dye microcapsules are prepared by any one of the methods described in claims 1-8 and have the function of visual detection of fragrance and flavor. The filter tip has a coaxial three-section structure, which consists of a pre-filtration cooling section (10), a middle color-changing reaction chamber (20) and a terminal air permeability observation section (30) from the tobacco end to the inhalation end. The pre-filtration section has a fiber porous structure. The middle color-changing reaction chamber (20) is provided with a polylactic acid porous support bracket. The support bracket is constrained to set up a coated sensitive dye microcapsule (21). The microcapsule is composed of an outer capsule material and an inner color-developing dye. The capsule material can pass through the smoke and prevent the dye from seeping out. The terminal observation section (30) is provided with an air permeable and liquid-resistant structure. The outer wall of the filter tip is provided with a transparent window and a colorimetric card (31). The colorimetric card (31) and the window are at the same observation angle. The colorimetric card is provided with color gradient blocks corresponding to different concentrations. The filter tip has an outer diameter of 5.4 mm, a length of 31 ± 0.1 mm, and an overall draw resistance of 800-1200 Pa. All materials used are tobacco contact grade materials.
10. The cigarette filter with microcapsules according to claim 9, characterized in that, The pre-filter cooling section is made of cellulose acetate or polylactic acid hollow fiber. The fiber structure has a continuous flue gas channel inside. The length of the pre-filter section accounts for 30%-40% of the total length of the filter tip, the middle color-changing reaction chamber accounts for 40%-50%, and the end air permeability observation section accounts for 10%-20%. The end section is equipped with an air permeable and liquid-blocking partition. The pore size of the partition is smaller than the size of the microcapsules and dye molecules. The upper and lower ends of the middle reaction chamber are equipped with limiting structures to restrict the axial movement of the microcapsules.
11. The cigarette filter with microcapsules according to claim 9, characterized in that, The polylactic acid porous scaffold within the central color-changing reaction chamber has a porosity of 65%. The microcapsules loaded within the scaffold are chitosan-based color-changing microspheres, sodium alginate cross-linked microspheres, or alizarin red-Sr. 2+ One type of complex microcapsule has a microcapsule particle size of 20-200μm, preferably 50-80μm. The microcapsules are distributed in a thin layer inside the support, and the flue gas passes radially through the area where the microcapsules are located. The support and the outer sheath of the filter are coaxially fitted, and the inner and outer surfaces of the support are both smooth transition structures.
12. The cigarette filter with microcapsules according to claim 11, characterized in that, The microcapsules encapsulate one or more of bromocresol purple, phenol red, or alizarin red. Bromocresol purple develops color through changes in flue gas pH, with a detection limit of ≤0.05 mg / mL for ester flavorings and fragrances. Phenol red develops color through changes in environmental polarity, with a detection limit of ≤0.08 mg / mL for ethanol flavorings and fragrances. Alizarin red-Sr... 2+ Color development is achieved through the coordination dissociation of complexes, with a corresponding benzaldehyde detection limit of 5 ppm. The colors of different dyes do not overlap and can be intuitively distinguished.
13. The cigarette filter with microcapsules according to claim 9, characterized in that, The colorimetric cards are arranged sequentially along the filter tip axis. The color difference before and after color development is ΔE > 5 (CIE-Lab). The color change rate within 24 hours of color development is ≤ 2.1%. There is no dye leakage, migration or fading during use. The transparent window is a long strip window structure. The window area completely covers the microcapsule distribution area. The colorimetric cards and the window are set adjacent to each other and maintain the same observation direction. The color blocks are uniform in size and spacing. The edge of the window is flush with the edge of the colorimetric cards.
14. The cigarette filter with microcapsules according to claim 9, characterized in that, The filter tip outer sheath is composed of antibacterial coated paper and a transparent window. The transparent window is made of polycarbonate (PC) material with a light transmittance of ≥95%. The window corresponds to the central color-changing reaction chamber and the end observation section area. The antibacterial coated paper contains silver ion antibacterial components. The transparent window is sealed and bonded to the outer sheath. The colorimetric card is attached to the outside of the antibacterial coated paper without obstructing the window area. The filter tip has a coaxial cylindrical structure with tight connections between each section and a smooth and continuous outer surface.