A method of making a gelled plant powder porous plug

Abstract

The present invention relates to a gelated plant powder porous filter rod and its preparation method, which comprises the steps of preparing mixed sol, gelating the mixed sol, pre-freezing and vacuum drying. The gelated plant powder porous filter rod has good permeability, high porosity, low density and low thermal conductivity, and can effectively reduce harmful substances in cigarette smoke, and has remarkable effect of reducing tar and reducing harm.

Description

[Technical Field]

[0001] This invention belongs to the field of tobacco processing technology. More specifically, this invention relates to a porous filter rod made of gelled plant powder, and also to a method for preparing the porous filter rod made of said gelled plant powder. [Background Technology]

[0002] In recent years, with increasing public awareness of the health risks of smoking, low-harm cigarettes have become the preferred choice for consumers and a future trend in the tobacco industry. Current low-harm cigarette product development typically employs methods such as perforated filter rods for ventilation and dilution, adding adsorbent materials to the filter rods, and replacing highly permeable cigarette paper and filter rod raw materials to achieve tar reduction and harm reduction. As a crucial component of cigarettes, the filter rod significantly impacts the taste and tar reduction of cigarette smoke, and 80% of technological innovation in existing cigarette products stems from filter rod technology innovation. Currently, filter rods are binary and ternary composite filter rods, with biomass materials being the most prevalent. These not only offer the advantages of tar reduction and harm reduction but also facilitate biodegradation; therefore, porous biomass filter rods are widely used in the tobacco industry.

[0003] Currently, paper filter materials and cellulose acetate filter materials are widely used as cigarette filter rods. Paper filter rods have a good tar trapping effect and a moderate price, but due to their strong hydrophilicity, they have more residual lignin, which makes the smoke dry and affects the smoking experience. cellulose acetate filter rods have good elasticity, good thermal stability, are non-toxic and odorless, have low draw resistance and significant filtration effect. However, cellulose acetate filter rods have high production costs, complex production processes, and limited adsorption capacity. Furthermore, both of these materials have poor biodegradability.

[0004] Plant microstructures exhibit a natural hierarchical structure, possessing excellent self-adaptability, widespread availability, and renewability. Porous biomass is a rich and renewable resource and material with advantages such as high biocompatibility, safety, non-toxicity, and biodegradability. Furthermore, its lower thermal conductivity, lower density, and lighter weight make it suitable for use in filter rods. In addition, porous biomass retains the bioactivity and good biocompatibility of biomass precursors, giving it broader application prospects in the food, pharmaceutical, and tobacco industries.

[0005] However, these existing technologies still have some technical defects. Based on the summary of existing technologies, the inventors have finally completed this invention through a large number of experimental studies and analyses. [Summary of the Invention]

[0006] [Technical problem to be solved]

[0007] The purpose of this invention is to provide a porous filter rod made of gelled plant powder.

[0008] Another object of the present invention is to provide a method for preparing the gelled plant powder porous filter rod.

[0009] [Technical Solution]

[0010] The present invention is achieved through the following technical solution.

[0011] This invention relates to a method for preparing a porous filter rod made of gelled plant powder.

[0012] The preparation steps of this method are as follows:

[0013] A. Preparation of mixed sol

[0014] Plant powder and isomaltooligosaccharide solution were mixed at a weight ratio of 5.0–8.0:80–100 at 70–90°C for 10–30 min. Then, 2.0–3.0 parts by weight of plant polysaccharide, 2.5–3.5 parts by weight of auxiliary gum, 0.9–1.5 parts by weight of natural antioxidant, 1.0–3.0 parts by weight of glycerol, and 0.5–0.8 parts by weight of adsorbent were added to 85.0–108.0 parts by weight of the resulting mixture. The mixture was then stirred at 70–90°C and 9000–11000 rpm for 30–60 min to obtain a sol.

[0015] 0.8 to 2.0 parts by weight of a divalent cationic compound were added to the sol, and the mixture was ultrasonically treated at a temperature of 80 to 90°C and an ultrasonic power of 300 to 400 W for 30 to 60 minutes to obtain a mixed sol containing divalent cationic compounds.

[0016] B. Mixed Sol-Gel Formation

[0017] The mixed sol obtained in step A is allowed to stand and gel at a temperature of 20-40℃ for 30-60 minutes, and then allowed to stand and gel at a temperature of 4-20℃ for 3-6 hours. The resulting cold gel is directly packed into a porous filter rod mold with a diameter of 3-10 mm.

[0018] C. Pre-freezing

[0019] Place the porous filter rod mold containing the cryogel from step B in an environment with a temperature of -40 to -20°C, and allow the cryogel to be pre-frozen and aged for 6 to 10 hours to obtain an aged cryogel.

[0020] D. Vacuum drying

[0021] The cold trap temperature of the microwave freeze dryer is adjusted to -80 to -40°C. The aged cryogel from step C is then placed in the microwave freeze dryer and freeze-dried for 4.0 to 7.0 hours under conditions of vacuum of -0.09 to -0.06 MPa, microwave power of 100 to 500 W, and temperature of -70 to -40°C, thus obtaining the gelled plant powder porous filter rod.

[0022] According to a preferred embodiment of the present invention, in step A, the plant powder is one or more plant powders selected from okra, Malabar spinach, sage, poria cocos, lotus root powder, quercetin, sage, tannin, or konjac, and the particle size of such plant powder is 80-150 mesh.

[0023] According to another preferred embodiment of the present invention, in step A, the plant polysaccharide is one or more plant polysaccharides selected from sodium alginate, konjac glucoside, or mannose.

[0024] According to another preferred embodiment of the present invention, in step A, the auxiliary adhesive is one or more auxiliary adhesives selected from gelatin, guar gum or xanthan gum.

[0025] According to another preferred embodiment of the present invention, in step A, the natural antioxidant is one or more natural antioxidants selected from plant-based active selenium, squalene, or tea powder.

[0026] According to another preferred embodiment of the present invention, in step A, the adsorbent is one or more adsorbents selected from activated carbon, bentonite or montmorillonite.

[0027] According to another preferred embodiment of the present invention, in step A, the divalent cation compound is one or more selected from Ca 2+ Mg 2+ or Zn 2+ Divalent cationic compounds, including sulfates, nitrates, phosphates, or carbonates.

[0028] According to another preferred embodiment of the present invention, in step B, the porous filter rod mold is a non-microwave-absorbing porous filter rod mold made of non-metals selected from polytetrafluoroethylene, PFA, quartz or glass.

[0029] The present invention also relates to a porous filter rod of gelled plant powder prepared by the aforementioned preparation method.

[0030] According to a preferred embodiment of the present invention, the gelled plant powder porous filter rod has the following physical properties:

[0031] Density 0.02~0.06g / cm³ 3Porosity 88%–96%, thermal conductivity 0.01–0.06 W / m·K, pressure drop 3200–3400 Pa, and filter rod length 30–144 mm.

[0032] The invention will now be described in more detail.

[0033] This invention relates to a method for preparing a porous filter rod made of gelled plant powder.

[0034] The preparation steps of this method are as follows:

[0035] A. Preparation of mixed sol

[0036] Plant powder and isomaltooligosaccharide solution were mixed at a weight ratio of 5.0–8.0:80–100 at 70–90°C for 10–30 min. Then, 2.0–3.0 parts by weight of plant polysaccharide, 2.5–3.5 parts by weight of auxiliary gum, 0.9–1.5 parts by weight of natural antioxidant, 1.0–3.0 parts by weight of glycerol, and 0.5–0.8 parts by weight of adsorbent were added to 85.0–108.0 parts by weight of the resulting mixture. The mixture was then stirred at 70–90°C and 9000–11000 rpm for 30–60 min to obtain a sol.

[0037] 0.8 to 2.0 parts by weight of a divalent cationic compound were added to the sol, and the mixture was ultrasonically treated at a temperature of 80 to 90°C and an ultrasonic power of 300 to 400 W for 30 to 60 minutes to obtain a mixed sol containing divalent cationic compounds.

[0038] In this invention, the basic role of the mixed sol in preparing the porous filter rod of the gelled plant powder is that it serves as a scaffold material for gelation, forming a three-dimensional network gel structure.

[0039] According to the present invention, plant powder should be understood as a type of plant powder rich in cellulose, hemicellulose, lignin, plant gums, starch, etc. Because these plant molecules possess a large number of reactive functional groups, they exhibit good synergistic effects with other components of the mixed sol of the present invention, thereby enabling the preparation of a multifunctional gelled composite material with good biocompatibility, biodegradability, and environmental friendliness. The plant powder used in the present invention is one or more plant powders selected from okra, Malabar spinach, tamarisk, Poria cocos, lotus root powder, quercetin, tamarisk, tannin, or konjac. The particle size of these plant powders is 80-150 mesh. These are all commercially available products, such as okra concentrated powder sold by Lanzhou Waterles Biotechnology Co., Ltd. under the trade name Okra, Malabar spinach extract sold by Xi'an Zhanxun Biotechnology Co., Ltd. under the trade name Malabar spinach extract, and tamarisk powder sold by Shaanxi Snowt Biotechnology Co., Ltd. under the trade name Tamarisk powder.

[0040] In this invention, the main role of isomaltooligosaccharide in the preparation of the mixed sol is to dehydrate the mixed sol. The basic mechanism of isomaltooligosaccharide dehydration is to place the material in a solution with high osmotic pressure. Based on the semi-permeability of the cell membrane, water is removed from the material, reducing the time and cost of subsequent drying. For details, please refer to the literature: Jiang Jiahui, thesis titled "Research on Microwave Freeze-Drying Process and Quality Control of Strawberries", Master's Thesis, Jiangnan University, 2021.

[0041] The isomaltooligosaccharide solution used in this invention is a solution of isomaltooligosaccharide sold by Jiangxi Baiying Biotechnology Co., Ltd. under the trade name "Isomaltooligosaccharide" in distilled water, with a concentration of 6.25-8.0% by weight.

[0042] In this invention, the basic role of plant polysaccharides in the preparation of mixed sols is that they crosslink with divalent cations to form hydrogels, giving the resulting gels good permeability, transparency, and tensile strength.

[0043] The plant polysaccharides used in this invention are one or more plant polysaccharides selected from sodium alginate, konjac glucoside, or mannose. These are all products currently sold on the market, such as sodium alginate sold by Guangzhou Guanyu Chemical Co., Ltd. under the trade name sodium alginate, and konjac glucoside sold by Lanzhou Waterles Biotechnology Co., Ltd. under the trade name konjac glucoside.

[0044] In this invention, the auxiliary adhesive should be understood as a macromolecular adhesive with hydrophilicity and thickening, stabilizing and emulsifying effects on the sol. Its basic role in the preparation of mixed sol is to act as a thickener, stabilizer and emulsifier, that is, to thicken the mixed sol, to stabilize the mixed sol, and to emulsify the mixed sol.

[0045] The auxiliary adhesives used in this invention are gelatin, xanthan gum, and kerogen gum, all of which are currently commercially available products. For example, gelatin sold by Guangzhou Huayu Biotechnology Co., Ltd. under the trade name Gelatin, and kerogen gum sold by Jiangsu Yiming Biotechnology Co., Ltd. under the trade name Kerogen gum.

[0046] In this invention, natural antioxidants should be understood as antioxidants that exist in natural plants.

[0047] The basic function of natural antioxidants in the gelled plant powder porous filter rod of this invention is to enable the filter rod to reduce the content of harmful substances and free radicals in flue gas.

[0048] The natural antioxidants used in this invention are plant-based active selenium, squalene, or tea dust, all of which are currently available on the market. For example, plant-based active selenium is sold by Xi'an Darwen Biotechnology Co., Ltd. under the trade name "Plant-based Active Selenium," and tea dust is sold by Yunnan Manyouwei Tea Co., Ltd. under the trade name "Pu'er Tea Dust."

[0049] In this invention, the primary function of glycerol in the gelled plant powder porous filter rod is as a plasticizer, enhancing the plasticity of the mixed sol. The glycerol used in this invention is a commercially available product, such as the one sold by Shanghai Better Chemical Co., Ltd. under the trade name "glycerol".

[0050] In this invention, the adsorbent should be understood as a substance that has the property of adsorbing substances such as nicotine and tar.

[0051] The main function of the adsorbent in the gelled plant powder porous filter rod of this invention is to adsorb harmful substances such as nicotine, tar, phenol, and carbon monoxide produced when cigarettes are smoked, and to remove the smell of smoke, thereby purifying the air.

[0052] The adsorbent used in this invention is one or more adsorbents selected from activated carbon, bentonite, or montmorillonite, all of which are currently commercially available products, such as activated carbon sold by Henan Haoqing Water Purification Materials Co., Ltd. under the trade name activated carbon, and bentonite sold by Guangxi Junle Technology Co., Ltd. under the trade name sodium-based bentonite.

[0053] In this invention, divalent cationic compounds should be understood to contain some Ca. 2+ Mg 2+ or Zn 2+ Compounds with divalent cations.

[0054] The fundamental role of divalent cationic compounds in the preparation of porous filter rods made from gelled plant powder is to induce the gelation of the sol solution.

[0055] The divalent cationic compound used in this invention is one or more selected from Ca 2+ Mg 2+ or Zn 2+ Divalent cationic compounds such as sulfates, nitrates, phosphates, or carbonates are all products currently available on the market.

[0056] As mentioned above, the raw materials used in the preparation of the mixed sol in this invention are plant powder, isomaltooligosaccharide, plant polysaccharide, auxiliary gum, natural antioxidant, glycerol, adsorbent and divalent cationic compound. In the following discussion, for example when discussing the effect of the amount of plant powder, the other raw materials should be understood to be other raw materials such as isomaltooligosaccharide other than plant powder, and the rest of the raw materials are understood in the same way.

[0057] First, plant powder and isomaltooligosaccharide solution are mixed at a weight ratio of 5.0–8.0:80–100 at 70–90°C for 10–30 minutes. When the amount of isomaltooligosaccharide solution is 80–100, if the amount of plant powder is less than 5.0, the prepared sol will have lower viscosity and hardness; if the amount of plant powder is greater than 8.0, a large number of lumps will appear on the surface of the prepared sol, and the viscosity will be higher. Therefore, an amount of plant powder of 5.0–8.0 is reasonable. Similarly, when the amount of plant powder is 5.0–8.0, if the amount of isomaltooligosaccharide solution is less than 80, the prepared sol will not dissolve completely, resulting in lumps; if the amount of isomaltooligosaccharide solution is greater than 100, the prepared sol will have lower viscosity. Therefore, an amount of isomaltooligosaccharide solution of 80–100 is reasonable.

[0058] When the mixing time of plant powder and isomaltooligosaccharide solution is within the aforementioned range, if the mixing temperature is below 70°C, the mixed sol will be unevenly mixed; if the mixing temperature is above 90°C, it will lead to combustion of the mixed sol or release of volatiles. Therefore, a mixing temperature of 70–90°C is suitable. When the mixing temperature of plant powder and isomaltooligosaccharide solution is within the aforementioned range, if the mixing time is less than 10 minutes, irregular aggregates will appear in the mixed sol; if the mixing time is longer than 30 minutes, the reaction time of the mixed sol is too long, resulting in aging. Therefore, a mixing time of 10–30 minutes is appropriate.

[0059] In this invention, when the amounts of other raw materials are within the aforementioned range, if the amount of plant polysaccharide is less than 2.0 parts by weight, the prepared sol will form a loose three-dimensional network structure; if the amount of plant polysaccharide is greater than 3.0 parts by weight, some lumps will appear on the surface of the prepared sol; therefore, an amount of 2.0 to 3.0 parts by weight of plant polysaccharide is reasonable, and preferably 2.2 to 2.8 parts by weight.

[0060] When the amounts of other raw materials are within the range described, if the amount of auxiliary adhesive is less than 2.5 parts by weight, the prepared mixed sol will have poor emulsification and stability; if the amount of auxiliary adhesive is more than 3.5 parts by weight, the prepared mixed sol will have poor flowability and elasticity. Therefore, the amount of auxiliary adhesive is suitable at 2.5 to 3.5 parts by weight, preferably 2.8 to 3.2 parts by weight.

[0061] When the amounts of other raw materials are within the range described, if the amount of natural antioxidant is less than 0.9 parts by weight, the ability to scavenge free radicals is weak; if the amount of natural antioxidant is more than 1.5 parts by weight, it will inhibit other biochemical reactions in the sol. Therefore, the amount of natural antioxidant is appropriate at 0.9 to 1.5 parts by weight, preferably 1.1 to 1.3 parts by weight.

[0062] When the amounts of other raw materials are within the range described, if the amount of glycerol is less than 1.0 parts by weight, the prepared mixed sol will have poor elasticity; if the amount of glycerol is more than 3.0 parts by weight, the prepared mixed sol will be too hard. Therefore, the amount of glycerol is preferably 1.0 to 3.0 parts by weight, and more preferably 1.6 to 2.4 parts by weight.

[0063] When the amounts of other raw materials are within the range described, if the amount of adsorbent is less than 0.5 parts by weight, the adsorption capacity for harmful substances in the flue gas is poor; if the amount of adsorbent is greater than 0.8 parts by weight, the adsorption capacity for flue gas and aroma substances is strong, affecting the smoking experience; therefore, the amount of adsorbent is suitable at 0.5 to 0.8 parts by weight, preferably 0.6 to 0.7 parts by weight.

[0064] When the amounts of other raw materials are within the aforementioned range, if the amount of the divalent cationic compound is less than 0.8 parts by weight, the sol exhibits a loose, porous network structure with poor stability; if the amount of the divalent cationic compound is greater than 2.0 parts by weight, the sol will undergo strong aggregation, forming a large number of irregular aggregates. Therefore, the amount of the divalent cationic compound is appropriate at 0.8 to 2.0 parts by weight, preferably 1.1 to 1.7 parts by weight.

[0065] A sol is obtained by mixing plant powder with isomaltooligosaccharide solution, plant polysaccharides, auxiliary gums, natural antioxidants, glycerol, and adsorbent at a temperature of 70–90°C and a speed of 9000–11000 rpm for 30–60 minutes. When the speed and mixing time are within the specified range, if the mixing temperature is below 70°C, the sol will be unevenly mixed and lumps will appear; if the mixing temperature is above 90°C, it will lead to combustion of the sol or the release of volatiles. Therefore, a mixing temperature of 70–90°C is appropriate. When the speed and mixing temperature are within the specified range, if the mixing time is less than 30 minutes, irregular aggregates will appear in the sol; if the mixing time is longer than 60 minutes, the reaction time of the sol is too long, resulting in aging. Therefore, a mixing time of 30–60 minutes is suitable. When the mixing temperature and mixing time are within the specified range, if the rotation speed is below 9000 rpm, the sol mixture will be uneven; if the rotation speed is above 11000 rpm, the sol mixture will be uneven and aggregates will appear. Therefore, a rotation speed of 9000–11000 rpm is appropriate. The mixing equipment used in this invention is a commonly used mixing equipment in this technical field, such as the mixing equipment sold by Shanghai Ouhe Machinery Equipment Co., Ltd. under the trade name A120Pro Intelligent Digital Display Timed Mixer.

[0066] After adding a divalent cationic compound to the sol, the mixture is ultrasonically treated at 80–90°C and 300–400W for 30–60 minutes to obtain a mixed sol containing divalent cationic compounds. When the ultrasonic treatment time and power are within the specified range, if the ultrasonic treatment temperature is below 80°C, small bubbles in the mixed sol will not be completely eliminated; if the ultrasonic treatment temperature is above 90°C, the mixed sol is easily combustible. Therefore, an ultrasonic treatment temperature of 80–90°C is suitable. When the ultrasonic treatment temperature and power are within the specified range, if the ultrasonic treatment time is less than 30 minutes, small bubbles in the mixed sol will not be completely eliminated; if the ultrasonic treatment temperature is above 90°C, the mixed sol will be easily combustible. If the ultrasonic treatment time exceeds 60 minutes, the mixed sol is prone to dehydration and hardening; therefore, an ultrasonic treatment time of 30–60 minutes is appropriate. When the ultrasonic treatment temperature and time are within the aforementioned range, if the ultrasonic power is below 300W, small air bubbles in the mixed sol will not be completely eliminated; if the ultrasonic power is above 400W, the mixed sol is prone to dehydration and hardening; therefore, an ultrasonic power of 300–400W is appropriate. The ultrasonic equipment used in this invention is the commonly used ultrasonic equipment in this technical field, such as the ultrasonic equipment sold by Guangdong Blue Whale Ultrasonic Cleaning Technology Co., Ltd. under the trade name "Tabletop Digital Dual-Frequency Ultrasonic Cleaning Machine".

[0067] B. Mixed Sol-Gel Formation

[0068] The mixed sol obtained in step A is allowed to stand and gel at a temperature of 20-40℃ for 30-60 minutes, and then allowed to stand and gel at a temperature of 4-20℃ for 3-6 hours. The resulting cold gel is directly packed into a porous filter rod mold with a diameter of 3-10 mm.

[0069] In this invention, the gelation of the mixed sol obtained in step A should be understood as the sol gradually becoming viscous upon cooling, eventually losing its fluidity and becoming an elastic gel.

[0070] The mixed sol obtained in step A needs to undergo cold gelation treatment under a suitable temperature gradient. The mixed sol only needs 30–60 minutes to gel at a temperature of 20–40°C. Without this gelation treatment, the subsequent pre-freezing time needs to be extended, by several times. If the mixed sol is only allowed to gel at a temperature of 4–20°C, the sol will clump together due to the rapid temperature drop, resulting in very uneven gelation.

[0071] The cold gel obtained by testing using the standard method for determining the strength of plant gels meets the gel standard stipulated by the State Administration for Quality Supervision, Inspection and Quarantine (GB / T41811-2022).

[0072] The refrigeration equipment used in this invention is the refrigeration equipment commonly used in this technical field, such as the refrigeration equipment sold by Shanghai Suying Instrument Co., Ltd. under the trade name High and Low Temperature Test Chamber.

[0073] The aforementioned porous filter rod mold with a diameter of 3-10mm is a non-microwave-absorbing filter rod mold made of non-metallic materials such as tetrafluoroethylene, PFA, quartz, or glass, with a large compression ratio and porous structure. See the attached document for details. Figure 1 .

[0074] C. Pre-freezing

[0075] Place the porous filter rod mold containing the cryogel from step B in an environment with a temperature of -40 to -20°C, and allow the gel to be pre-frozen and aged for 6 to 10 hours to obtain an aged cryogel.

[0076] According to the present invention, the main purpose of pre-freezing the cryogel is to fix the product and form crystals that are easy to sublimate.

[0077] In this gel pre-freezing aging step, if the pre-freezing time is within the specified range and the pre-freezing temperature is below -40°C, the degree of gelation inside the gel will be uneven; if the pre-freezing temperature is above -20°C, the drying time of the subsequent microwave vacuum drying stage will be significantly prolonged, and the microwave power consumption will be excessive.

[0078] When the pre-freezing temperature is within the specified range, if the pre-freezing time is less than 6 hours, the gel aging time is insufficient, and the gel pre-freezing aging is incomplete; if the pre-freezing time is longer than 10 hours, the gel pre-freezing aging time is too long, resulting in excessive power consumption. Therefore, pre-freezing aging of the cold gel at a temperature of -40 to -20°C for 6 to 10 hours is suitable.

[0079] The aged cold gel obtained by testing using the standard method for plant gel strength meets the gel standard stipulated by the State Administration for Quality Supervision, Inspection and Quarantine of China (GB / T41811-2022).

[0080] D. Vacuum drying

[0081] The cold trap temperature of the microwave freeze dryer is adjusted to -40 to -80°C. The aged cryogel from step C is then placed in the microwave freeze dryer and freeze-dried for 4.0 to 7.0 hours under conditions of vacuum of -0.09 to -0.06 MPa, microwave power of 100 to 500 W, and temperature of -70 to -40°C, thus obtaining the gelled plant powder porous filter rod.

[0082] Microwave freeze-drying technology uses a microwave generator instead of a traditional heating plate to provide latent heat of sublimation to frozen materials for dehydration and drying. The advantage of this technology is that within the microwave energy penetration depth range, the material itself converts energy, allowing the entire material to be heated without direct contact with the energy source. This results in high thermal efficiency and effectively shortens drying time.

[0083] During microwave freeze-drying, when the microwave power, freeze-drying temperature, and freeze-drying time are within the specified ranges, if the freeze-drying vacuum degree is below -0.09 MPa, the microwave frequency becomes too low, and the freeze-drying time becomes excessively long. If the freeze-drying vacuum degree is above -0.06 MPa, microwave energy consumption increases, resulting in significant microwave reflection, discharge breakdown, and damage to components and the sol. Therefore, a freeze-drying vacuum degree of -0.09 to -0.06 MPa is suitable.

[0084] When the vacuum level, freeze-drying temperature, and freeze-drying time are within the specified ranges, if the microwave power is below 100W, the moisture contained in the gel cannot be effectively and quickly evaporated, prolonging the freeze-drying time; if the microwave power is above 500W, the microwave energy consumption is high, which may damage the components and the sol. Therefore, a microwave power of 100–500W is suitable for microwave freeze-drying, preferably 200–500W.

[0085] When the vacuum level, microwave power, and freeze-drying time are within the specified ranges, if the freeze-drying temperature is below -70°C, the energy consumption for gel freeze-drying increases; if the freeze-drying temperature is above -40°C, the gel freeze-drying time is prolonged, and the gel cannot be completely freeze-dried. Therefore, a microwave freeze-drying temperature of -70 to -40°C is suitable.

[0086] When the vacuum level, microwave power, and freeze-drying temperature are within the specified ranges, if the freeze-drying time is less than 4.0 hours, the gel freeze-drying will be incomplete; if the freeze-drying time is longer than 7.0 hours, it will consume excessive freeze-drying power. Therefore, a microwave freeze-drying time of 4.0 to 7.0 hours is suitable.

[0087] The microwave freeze dryer used in this invention is a commonly used freeze drying equipment in this technical field, such as the microwave freeze dryer sold by Shandong Shengxiangshun Machinery Equipment Co., Ltd. under the trade name Microwave Large Electric Heating Vacuum Dryer.

[0088] The present invention also relates to a porous filter rod of gelled plant powder prepared by the aforementioned preparation method.

[0089] According to the test method specified in GB / T 16447-2004, the density of the porous filter rod made of gelled plant powder of the present invention is 0.02-0.06 g / cm³. 3 ;

[0090] According to the test method specified in GB / T 22838.14-2009 "Determination of physical properties of cigarettes and filter rods - Part 14: Appearance of filter rods", the length of the gelled plant powder porous filter rod of the present invention is 30-144 mm, the pressure drop is 3200-3400 Pa, and the porosity is 88%-96%.

[0091] The thermal conductivity of the porous filter rod made of gelled plant powder of the present invention was determined to be 0.01 to 0.06 W / m·K using a thermal conductivity meter sold by Shanghai Luozhong Technology Development Co., Ltd. under the trade name TCI-3-A.

[0092] The total particulate matter content was determined using a smoking machine sold by Shenzhen Xingyi Electronic Equipment Co., Ltd. under the trade name SM400 smoking machine, to replace the existing cellulose acetate filter rod in ordinary cigarettes with the gelled plant powder porous filter rod prepared in this invention.

[0093] The results of the physical properties of the filter rod are shown in Table 1, and the results of the total particulate matter detection in the flue gas are shown in Table 2.

[0094] [Beneficial Effects]

[0095] The beneficial effects of this invention are:

[0096] The raw materials used in this invention are abundant and renewable resources and materials, possessing high biocompatibility, safety, and non-toxicity. The used filter rods are biodegradable, and the preparation method is simple, with low production costs, meeting the environmental protection requirements of modern industrial production. Compared to traditional filter rods, the gelled plant powder porous filter rods of this invention exhibit excellent permeability, high porosity, low density, and low thermal conductivity. Furthermore, they effectively eliminate free radicals and reduce the volatilization of aroma substances. Microwave freeze-drying technology shortens processing time and energy consumption, resulting in low production costs. [Attached Image Description]

[0097] Figure 1 This is a schematic diagram of the porous filter rod mold structure of the present invention.

[0098] In the diagram: a - filter rod holes; b - glass material mold;

Detailed Implementation Methods

[0099] The invention will be better understood through the following examples.

[0100] Example 1: Preparation of porous filter rods made from gelled plant powder according to the present invention

[0101] The implementation steps of this embodiment are as follows:

[0102] A. Preparation of mixed sol

[0103] Tofu powder with a particle size of 100 mesh and isomaltooligosaccharide solution were mixed at a weight ratio of 5.0:80 and stirred at 80°C for 30 min. Then, 2.0 parts by weight of sodium alginate, 2.5 parts by weight of guar gum, 0.9 parts by weight of plant active selenium, 1.5 parts by weight of glycerol and 0.6 parts by weight of activated carbon were added. The mixture was then stirred at 80°C and 10,000 rpm for 60 min to obtain a sol.

[0104] 1.5 parts by weight of calcium carbonate compound were added to the sol and ultrasonically treated for 30 minutes at 80°C and 350W to obtain a mixed sol containing divalent cations.

[0105] B. Mixed Sol-Gel Formation

[0106] The mixed sol obtained in step A was allowed to stand and gel at 30°C for 30 minutes, and then allowed to stand and gel at 4°C for 3 hours. The resulting cold gel was extruded into a ceramic non-metallic cylindrical porous filter rod mold with a diameter of 7.5 mm by continuous extrusion.

[0107] C. Pre-freezing

[0108] Place the porous filter rod mold containing the cryogel from step B in an environment at -20°C and allow the cryogel to pre-freeze and age for 6 hours to obtain an aged cryogel.

[0109] D. Vacuum drying

[0110] The cold trap temperature of the microwave freeze dryer was adjusted to -40°C, and the aged cryogel from step C was placed in the microwave freeze dryer and freeze-dried for 5.0 h under the conditions of vacuum degree -0.09MPa, microwave power 300W and temperature -60°C, thus obtaining the gelled plant powder porous filter rod.

[0111] The gelled plant powder porous filter rod prepared in this embodiment was tested according to the testing method described in this application specification. The test results of its physical properties are listed in Table 1, and the test results of its total particulate matter in the flue gas are listed in Table 2. The test results of the total particulate matter in the flue gas of the conventional ordinary cigarette acetate fiber filter rod used as a comparison are also listed in Table 2.

[0112] Example 2: Preparation of porous filter rods made from gelled plant powder according to the present invention

[0113] The implementation steps of this embodiment are as follows:

[0114] A. Preparation of mixed sol

[0115] Poria cocos powder with a particle size of 120 mesh and isomaltooligosaccharide solution were mixed at a weight ratio of 6.0:85 at 80°C for 20 minutes. Then, 2.3 parts by weight of sodium alginate, 2.8 parts by weight of gelatin, 1.0 part by weight of tea powder, 1.5 parts by weight of glycerin and 0.6 parts by weight of bentonite were added. The mixture was then stirred at 80°C and 10,000 rpm for 30 minutes to obtain a sol.

[0116] 1.0 part by weight of magnesium sulfate compound was added to the sol and ultrasonically treated for 30 min at 80°C and 400W to obtain a mixed sol containing divalent cations.

[0117] B. Mixed Sol-Gel Formation

[0118] The mixed sol obtained in step A was allowed to stand and gel at 35°C for 40 minutes, and then allowed to stand and gel at 10°C for 5 hours. The resulting cold gel was extruded into a ceramic non-metallic cylindrical porous filter rod mold with a diameter of 7.5 mm that does not absorb microwaves by continuous extrusion.

[0119] C. Pre-freezing

[0120] The porous filter rod mold containing the cryogel in step B is placed in an environment with a temperature of -40°C to allow the cryogel to be pre-frozen and aged for 7 hours, thereby obtaining an aged cryogel.

[0121] D. Vacuum drying

[0122] The cold trap temperature of the microwave freeze dryer was adjusted to -50°C, and the aged cryogel from step C was placed in the microwave freeze dryer and freeze-dried for 6.0 h under the conditions of vacuum degree -0.08MPa, microwave power 250W and temperature -50°C, thus obtaining the gelled plant powder porous filter rod.

[0123] The gelled plant powder porous filter rod prepared in this embodiment was tested according to the test method described in this application specification. The test results of its physical properties are listed in Table 1, and the test results of its total particulate matter in flue gas are listed in Table 2.

[0124] Example 3: Preparation of porous filter rods made from gelled plant powder according to the present invention

[0125] The implementation steps of this embodiment are as follows:

[0126] A. Preparation of mixed sol

[0127] Konjac powder with a particle size of 80 mesh and isomaltooligosaccharide solution were mixed at a weight ratio of 7.0:90 at 75°C for 30 min. Then, 2.5 parts by weight of mannose, 3.0 parts by weight of xanthan gum, 1.3 parts by weight of squalene, 2.0 parts by weight of glycerol and 0.7 parts by weight of montmorillonite were added. The mixture was then stirred at 75°C and 10,000 rpm for 40 min to obtain a sol.

[0128] 1.5 parts by weight of zinc nitrate compound were added to the sol and ultrasonically treated for 40 minutes at a temperature of 75°C and an ultrasonic power of 300W to obtain a mixed sol containing divalent cations.

[0129] B. Mixed Sol-Gel Formation

[0130] The mixed sol obtained in step A was allowed to stand and gel at 40°C for 30 minutes, and then allowed to stand and gel at 15°C for 3 hours. The resulting cold gel was then extruded into a ceramic non-metallic cylindrical porous filter rod mold with a diameter of 7.5 mm that does not absorb microwaves by continuous extrusion.

[0131] C. Pre-freezing

[0132] Place the porous filter rod mold containing the cryogel from step B in an environment at -30°C and allow the cryogel to pre-freeze and age for 6 hours to obtain an aged cryogel.

[0133] D. Vacuum drying

[0134] The cold trap temperature of the microwave freeze dryer was adjusted to -60°C, and the aged cryogel from step C was placed in the microwave freeze dryer and freeze-dried for 4.0 h under the conditions of vacuum degree -0.08MPa, microwave power 400W and temperature -60°C, thus obtaining the gelled plant powder porous filter rod.

[0135] The gelled plant powder porous filter rod prepared in this embodiment was tested according to the test method described in this application specification. The test results of its physical properties are listed in Table 1, and the test results of its total particulate matter in flue gas are listed in Table 2.

[0136] Example 4: Preparation of porous filter rods made from gelled plant powder according to the present invention

[0137] The implementation steps of this embodiment are as follows:

[0138] A. Preparation of mixed sol

[0139] Okra powder with a particle size of 150 mesh and isomaltooligosaccharide solution were mixed at a weight ratio of 8.0:100 at 90°C for 20 min. Then, 2.8 parts by weight of konjac glucopolysaccharide, 3.0 parts by weight of guar gum, 1.3 parts by weight of squalene, 2.3 parts by weight of glycerol and 0.7 parts by weight of activated carbon were added. The mixture was then stirred at 90°C and 11,000 rpm for 30 min to obtain a sol.

[0140] 1.8 parts by weight of calcium phosphate were added to the sol and ultrasonically treated for 30 minutes at a temperature of 90°C and an ultrasonic power of 350W to obtain a mixed sol containing divalent cations.

[0141] B. Mixed Sol-Gel Formation

[0142] The mixed sol obtained in step A was allowed to stand and gel at 30°C for 40 minutes, and then allowed to stand and gel at 4°C for 5 hours. The resulting cold gel was extruded into a ceramic non-metallic cylindrical porous filter rod mold with a diameter of 7.5 mm that does not absorb microwaves by continuous extrusion.

[0143] C. Pre-freezing

[0144] The porous filter rod mold containing the cryogel in step B is placed in an environment with a temperature of -40°C to allow the cryogel to be pre-frozen and aged for 8 hours, thereby obtaining an aged cryogel.

[0145] D. Vacuum drying

[0146] The cold trap temperature of the microwave freeze dryer was adjusted to -70°C. The aged cryogel from step C was then placed in the microwave freeze dryer and freeze-dried for 5.0 h under the conditions of vacuum degree -0.07MPa, microwave power 500W and temperature -70°C, thus obtaining the gelled plant powder porous filter rod.

[0147] The gelled plant powder porous filter rod prepared in this embodiment was tested according to the test method described in this application specification. The test results of its physical properties are listed in Table 1, and the test results of its total particulate matter in flue gas are listed in Table 2.

[0148] Example 5: Preparation of porous filter rods made from gelled plant powder according to the present invention

[0149] The implementation steps of this embodiment are as follows:

[0150] A. Preparation of mixed sol

[0151] Fox shrub powder with a particle size of 130 mesh and isomaltooligosaccharide solution were mixed at a weight ratio of 8.0:95 at 90°C for 30 min. Then, 2.5 parts by weight of sodium alginate, 2.8 parts by weight of xanthan gum, 1.0 part by weight of plant active selenium, 2.0 parts by weight of glycerol and 0.6 parts by weight of activated carbon were added. The mixture was then stirred at 90°C and 9000 rpm for 30 min to obtain a sol.

[0152] 1.2 parts by weight of magnesium nitrate were added to the sol and ultrasonically treated for 60 minutes at a temperature of 70°C and an ultrasonic power of 500W to obtain a mixed sol containing divalent cations.

[0153] B. Mixed Sol-Gel Formation

[0154] The mixed sol obtained in step A was allowed to stand and gel at 20°C for 60 min, and then allowed to stand and gel at 4°C for 3 h. The resulting cold gel was extruded into a ceramic non-metallic cylindrical porous filter rod mold with a diameter of 7.5 mm that does not absorb microwaves by continuous extrusion.

[0155] C. Pre-freezing

[0156] Place the porous filter rod mold containing the cryogel from step B in an environment at -35°C and allow the cryogel to pre-freeze and age for 5 hours to obtain an aged cryogel.

[0157] D. Vacuum drying

[0158] The cold trap temperature of the microwave freeze dryer was adjusted to -40°C, and the aged cryogel from step C was placed in the microwave freeze dryer and freeze-dried for 4.5 hours under conditions of vacuum of -0.08MPa, microwave power of 300W and temperature of -60°C, thus obtaining the gelled plant powder porous filter rod.

[0159] The gelled plant powder porous filter rod prepared in this embodiment was tested according to the test method described in this application specification. The test results of its physical properties are listed in Table 1, and the test results of its total particulate matter in flue gas are listed in Table 2.

[0160] Table 1: Test results of physical properties of the porous filter rod made from gelled plant powder of the present invention

[0161]

[0162] Table 2: Detection results of total particulate matter in the porous filter rod of gelled plant powder of the present invention

[0163]

[0164] The test results listed in Tables 1 and 2 show that the gelled plant powder porous filter rod of the present invention has good permeability, high porosity, low density and low thermal conductivity. The comparative test results of these examples show that the gelled plant powder porous filter rod prepared by the preparation method of the present invention can effectively reduce harmful substances in cigarette smoke and has a significant tar reduction and harm reduction effect.

Claims

1. A method for preparing a porous filter rod made of gelled plant powder, characterized in that... The preparation steps of this method are as follows: A. Preparation of mixed sol Plant powder and isomaltooligosaccharide solution are mixed at a weight ratio of 5.0–8.0:80–100 at 70–90°C for 10–30 minutes. The plant powder is one or more plant powders selected from okra, Malabar spinach, sagebrush, poria cocos, lotus root powder, quercetin, sagebrush, tannin, or konjac. To the mixture obtained (85.0–108.0 parts by weight), 2.0–3.0 parts by weight of plant polysaccharide, 2.5–3.5 parts by weight of auxiliary gum, 0.9–1.5 parts by weight of natural antioxidant, 1.0–3.0 parts by weight of glycerol, and 0.5–0.8 parts by weight of adsorbent are added. The mixture is then stirred at 70–90°C and 9000–11000 rpm for 30–60 minutes to obtain a sol. The natural antioxidant is one or more natural antioxidants selected from plant-active selenium, squalene, or tea powder. 0.8 to 2.0 parts by weight of a divalent cationic compound were added to the sol, and the mixture was ultrasonically treated at a temperature of 80 to 90°C and an ultrasonic power of 300 to 400 W for 30 to 60 minutes to obtain a mixed sol containing divalent cationic compounds. B. Mixed Sol-Gel Formation The mixed sol obtained in step A is allowed to stand and gel at a temperature of 20-40℃ for 30-60 minutes, and then allowed to stand and gel at a temperature of 4-20℃ for 3-6 hours. The resulting cold gel is directly packed into a porous filter rod mold with a diameter of 3-10 mm. C. Pre-freezing Place the porous filter rod mold containing the cryogel from step B in an environment with a temperature of -40 to -20°C, and allow the cryogel to be pre-frozen and aged for 6 to 10 hours to obtain an aged cryogel. D. Vacuum drying The cold trap temperature of the microwave freeze dryer is adjusted to -80 to -40°C. The aged cryogel from step C is then placed in the microwave freeze dryer and freeze-dried for 4.0 to 7.0 hours under conditions of vacuum of -0.09 to -0.06 MPa, microwave power of 100 to 500 W, and temperature of -70 to -40°C, thus obtaining the gelled plant powder porous filter rod.

2. The preparation method according to claim 1, characterized in that... In step A, the particle size of the plant powder is 80-150 mesh.

3. The preparation method according to claim 1, characterized in that... In step A, the plant polysaccharide is one or more plant polysaccharides selected from sodium alginate, konjac glucoside, or mannose.

4. The preparation method according to claim 1, characterized in that... In step A, the auxiliary adhesive is one or more adhesives selected from gelatin, guar gum, or xanthan gum.

5. The preparation method according to claim 1, characterized in that... In step A, the adsorbent is one or more adsorbents selected from activated carbon, bentonite, or montmorillonite.

6. The preparation method according to claim 1, characterized in that... In step A, the divalent cation compound is one or more selected from Ca 2+ Mg 2+ or Zn 2+ Divalent cationic compounds, including sulfates, nitrates, phosphates, or carbonates.

7. The preparation method according to claim 1, characterized in that... In step B, the porous filter rod mold is a non-microwave-absorbing porous filter rod mold made of non-metallic materials selected from polytetrafluoroethylene, PFA, quartz, or glass.

8. A porous filter rod made of gelled plant powder prepared by the preparation method according to any one of claims 1-7.

9. The porous filter rod of gelled plant powder according to claim 8, characterized in that... It has the following physical properties: Density 0.02~0.06g / cm³ 3 Porosity 88%–96%, thermal conductivity 0.01–0.06 W / m·K, pressure drop 3200–3400 Pa, and filter rod length 30–144 mm.

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