Preparation method for microcellular foamed composite material, and microcellular foamed silica gel filter rod prepared from the composite material

Abstract

Provided in the present invention is a preparation method for a microcellular foamed composite material, comprising: mixing a porous skeleton material wetted by silicone oil spray with a food-grade foaming agent, so as to obtain a porous skeleton foaming agent; and then mixing same with internally-mixed silica gel and a vulcanizing agent, so as to obtain the microcellular foamed composite material. Also provided in the present invention is a microcellular foamed silica gel filter rod prepared from the microcellular foamed composite material. The microcellular foamed silica gel filter rod in the present invention has good stiffness and rebound rate, and thus can adapt to shape and structure design requirements on more refined and more complex smoke pathways, thus helping to obtain filter rods having more complex cross-section hollowed-out patterns, and further enhancing effects of cooling smoke and adsorbing harmful substances. In addition, the microcellular foamed composite material has a stable outer wall friction force, so that the blade wear of devices in a following cutting step is reduced, which is manifested as products being not prone to adhesion to blades and materials being not prone to jamming, thereby delaying the time to replace blades of cutting devices, improving durability of devices, and lowering the maintenance requirement of the cutting devices.

Description

A method for preparing a micro-foamed composite material and a micro-foamed silica gel filter rod prepared using the composite material

[0001] This invention claims a domestic priority, with priority number CN 202410301400X and priority date March 15, 2024. Technical Field

[0002] The present invention relates to the technical field of filter rods for cigarettes, in particular to a micro-foam composite material that can be used to prepare the filter rod, and also to a micro-foam silica gel filter rod obtained by using the micro-foam composite material. Background Art

[0003] Traditional cigarette filter rods utilize a large amount of diacetate fiber tow as the filter rod material. However, using acetate fiber to produce filter rods with a hollow structure presents technical drawbacks. This is because acetate fiber tow is a high-density tow. When the hollow structure is constructed by pressing and forming in a filter rod machine containing a mold, the amount of tow used is 2 to 4 times that of ordinary acetate fiber filter rods without a hollow structure. This results in high manufacturing costs for hollow acetate fiber filter rods. Furthermore, because acetate fiber filter rods are formed and pressed by tow, their strength is relatively low, making it impossible to produce intricate hollow patterns. This makes it difficult to improve the cooling effect of the filter rod on the flue gas by designing a well-shaped flue gas flow channel. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a new micro-foam composite material. This micro-foam composite material can be used to prepare micro-foam silicone cigarette filter rods, so as to obtain better smoke cooling effect, and at the same time should have the physical properties that cigarette filter rods should have.

[0005] Based on this, a method for preparing a micro-foamed composite material is provided, the preparation method comprising the following steps:

[0006] (1) Preparation of porous skeleton foaming agent

[0007] (1.1) A porous skeleton material having a particle size of 58 to 180 μm is prepared, wherein the porous skeleton material is selected from porous hydroxyapatite, perlite and / or porous silicon;

[0008] (1.2) spraying the porous skeleton material obtained in step (1.1) with silicone oil to obtain a wetted material;

[0009] (1.3) Weighing a wetting material and a food-grade foaming agent in a mass ratio of 50-100:6-15, mixing them evenly, and then passing them through a 200-mesh sieve to remove excess foaming agent on the surface of the material to obtain a porous skeleton foaming agent, wherein the food-grade foaming agent is sodium carbonate and / or sodium bicarbonate;

[0010] (2) Preparation of mixed silica gel

[0011] Weigh silica gel, white carbon black and calcium carbonate in a mass ratio of 50-100:10-30:10-30, and mix them in an internal mixer to obtain internally mixed silica gel;

[0012] (3) Preparation of micro-foamed composite materials

[0013] A porous skeleton foaming agent, internal mixing silica gel and a vulcanizing agent are weighed in a mass ratio of 1-10:100-900:1-5, and mixed in an internal mixer to obtain a micro-foamed composite material.

[0014] In step (1.1) of the above preparation method, the porous skeleton material is passed through an 80-mesh sieve to obtain the undersize material, and the obtained product is then passed through a 200-mesh sieve to obtain the oversize material, thereby obtaining a powdered material with a particle size of 58 to 180 μm.

[0015] The porous framework material can be pre-dried, for example, by drying at 100-150°C for 2-8 hours, or by other conventional drying methods. Drying allows the silicone oil to better wet the porous framework material in subsequent steps, but it is generally not necessary to limit the water content of the porous framework material after drying.

[0016] According to a preferred embodiment, the specific surface area of ​​the porous hydroxyapatite, perlite or porous silicon in step (1.1) is 20-1000 m 2 / g, the specific surface area is determined by gas adsorption BET method. Porous hydroxyapatite, perlite and porous silicon are all commercially available materials. These materials all have porous structures and their specific surface areas are usually 20-1000m 2 / g, can meet the requirements of the present invention.

[0017] As porous materials, porous hydroxyapatite, perlite and porous silicon can be used alone or in combination. When mixed, their proportions are usually arbitrary and have little effect on the properties of the final product.

[0018] Typically, the mass ratio of the porous skeleton material to the silicone oil in step (1.2) is 5 to 20:100. Wetting the porous skeleton material with silicone oil allows the foaming agent in subsequent steps to be evenly attached to the porous skeleton material. Therefore, commercially available silicone oil generally meets the requirements of the present invention, such as the food-grade silicone oil 350cs product produced and sold by Foshan Guirunbao Biotechnology Co., Ltd. To achieve the desired effect of wetting the porous skeleton material, if the amount of silicone oil used is too low (less than 5% of the mass of the porous skeleton material), the porous skeleton material will not be completely wetted, resulting in uneven adhesion of the foaming agent. If the amount of silicone oil used is higher than 20%, the porous skeleton material will become overly moist, and the porous skeleton foaming agent may experience severe agglomeration, which is inconvenient for subsequent steps.

[0019] As a particularly preferred embodiment, the food-grade foaming agent in step (1.3) is a mixture of sodium carbonate and sodium bicarbonate, and the mass ratio of the wetting material, sodium carbonate, and sodium bicarbonate is 50-100:1-5:5-10, so as to obtain a better foaming effect and be more suitable for the physical property requirements of the filter rod product.

[0020] In the present invention, the silica gel in step (2) can be food grade silica gel purchased on the market. The density of such products is usually 1.0-1.5 g / cm 3 , hardness of 60-80 Shore A, tensile strength greater than 7MPa, can all achieve the technical solution of the present invention. For example, Nanjing Luoen Silicon Material Co., Ltd. produces and sells food-grade silica gel RBB-2030-80.

[0021] According to an optional embodiment, step (3) also contains food coloring. The addition amount of food coloring can refer to the coloring agent recorded in " National Food Safety Standard Food Additives Usage Standard" (GB 2760-2014), such as brilliant blue, lemon yellow, sunset yellow, temptation red, etc. are all commonly used edible coloring agents, which can be used alone or in combination, and the amount of brilliant blue is usually not more than 0.025‰ of the gross weight, while the amount of lemon yellow, sunset yellow or temptation red is usually not more than 0.1‰ of the gross weight. Those skilled in the art can, by controlling the addition ratio and addition opportunity of the pigment, to obtain a micro-foamed composite material with different colors or patterns.

[0022] In the present invention, the vulcanizing agent is usually a platinum vulcanizing agent.

[0023] Furthermore, the present invention also provides the use of the micro-foamed composite material obtained by the above preparation method in a filter rod.

[0024] In the present invention, the term "filter rod" may be a filter rod used in heat-not-burn cigarettes or combustion-type cigarettes.

[0025] Based on this, the present invention also provides a method for preparing a micro-foamed silica gel filter rod, the preparation method comprising the following steps:

[0026] (1) putting a micro-foam composite material into a silicone extruder with a rotating inner mold to rotate and extrude a rod-shaped material, wherein the micro-foam composite material is the micro-foam composite material obtained by the above-mentioned preparation method;

[0027] (2) the obtained rod-shaped material is heated and vulcanized at 160-250° C. for 10-20 seconds;

[0028] (3) The material obtained in step (2) is naturally cooled and then cut to obtain a micro-foamed silica gel filter rod.

[0029] In the present invention, the silicone extruder with an inner mold rotation adopts, for example, the 80 silicone tube extrusion equipment product produced and sold by Hebei Xulang Machinery Manufacturing Co., Ltd. When in use, the operating parameters of the extruder can be adjusted to control the extrusion stroke of the inner mold to 10 to 50 mm per rotation to obtain flue gas flow channels of different shapes. By replacing the inner die head with different material flow channel distributions (for example, the extrusion molding die head disclosed in CN 215750663U), filter rods with different flue gas flow channel shapes or structures can be obtained. These flue gas flow channels can have different cross-sectional hollow shapes to enrich the appearance shape selection of the filter rod end. These cross-sectional hollow shapes, such as symmetrical set shapes such as triangles, regular five-pointed stars, etc., can also be prepared into asymmetrical pattern shapes, such as cloud shapes, flame shapes, etc.

[0030] In step (2), the heating and vulcanization time generally depends on the heating temperature. The higher the heating temperature, the shorter the heating time can be. If the heating temperature is low, the longer the heating time should be, to ensure that the heated micro-foamed silicone filter rod is fully vulcanized and does not deform. The control of the heating temperature and time is a technical means that can be adjusted by those skilled in the art according to actual conditions and will not be elaborated here.

[0031] In the present invention, the porosity of the obtained micro-foamed silica gel filter rod is 10% to 40%, which can be obtained by testing with a porosity detector.

[0032] Compared with the hollow filter rod made of acetate fiber tow, the micro-foamed silicone filter rod of the present invention has good hardness and resilience, and therefore has better deformation resistance. It can adapt to finer and more complex hollow patterns to meet the requirements of the shape and structure design of the flue gas flow duct, further enhancing the flue gas cooling and harmful substance adsorption effects in terms of function, and allowing the filter rod designer to adopt more industrial aesthetic designs in terms of appearance.

[0033] On the other hand, the present invention improves the formula and preparation method of the micro-foamed composite material by adding a porous skeleton foaming agent, so that the outer wall friction of the micro-foamed silicone filter rod is more stable, thereby reducing blade wear in the subsequent slitting step, which is manifested in that the product is not easy to stick to the knife or get stuck, extending the tool change cycle of the slitting equipment, improving the durability of the equipment, and reducing the maintenance requirements of the slitting equipment. DETAILED DESCRIPTION

[0034] The following examples are used to illustrate the technical solutions of the present invention in a non-limiting manner.

[0035] In the present invention, unless otherwise specified, "%" used to explain product concentrations refers to mass ratio, ":" refers to mass ratio, and "parts" refers to parts by mass.

[0036] Example 1 Preparation of micro-foamed silica gel filter rod with inner spiral structure

[0037] (1) Preparation of micro-foamed composite materials

[0038] The parameter is that the specific surface area is 26m 2 / g porous hydroxyapatite is dried at 100°C for 8h, and after drying, the sieve is passed through an 80-mesh sieve to obtain the undersize, and the sieve is passed through a 200-mesh sieve to obtain the oversize. The sieved porous hydroxyapatite is sprayed with silicone oil, and the amount of silicone oil sprayed is 5% of the weight of the porous hydroxyapatite. After wetting, the mixture is sealed and balanced for 24h. After balance, the balanced porous hydroxyapatite, food-grade sodium carbonate and food-grade sodium bicarbonate are taken in a mass ratio of 100:5:10 and mixed thoroughly until uniform, and then passed through a 200-mesh sieve to remove excess foaming agent powder to obtain a porous skeleton foaming agent.

[0039] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 100:30:30, and mixed in an internal mixer to obtain white internal mixer silica gel.

[0040] Then, a porous skeleton foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 10:900:5 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0041] (2) Preparation of foamed silica gel filter rod

[0042] The silicone extruder uses an equilateral triangle inner die. A white micro-foam composite material is fed into the extruder, and the extrusion speed is set so that the inner die achieves a stroke of 50 mm per revolution. The extruded material is heated at 250°C to produce a filter rod with a circumference of 22 mm. The heating vulcanizes the composite material and fully pyrolyzes the foaming agent in the porous material, resulting in a uniform porous structure.

[0043] The filter rod was thoroughly cooled until the material was solidified, resulting in a white, elastic, and strong cylinder. The filter rod was then cut into 100 mm pieces using a filter rod cutter, designated as Sample 1.

[0044] Example 2 Preparation of micro-foamed silica gel filter rod with inner spiral structure

[0045] (1) Preparation of micro-foamed composite materials

[0046] The parameter is a specific surface area of ​​30m 2 / g porous hydroxyapatite is dried at 120℃ for 4h. After drying, it is passed through an 80-mesh sieve to take the undersize material, and through a 200-mesh sieve to take the oversize material. The sieved porous hydroxyapatite is sprayed with silicone oil, and the amount of silicone oil sprayed is 7% of the weight of the porous hydroxyapatite. After wetting, it is sealed and balanced for 24h. After balance, the balanced porous hydroxyapatite, food-grade sodium carbonate and food-grade sodium bicarbonate are taken in a mass ratio of 90:4:8 and mixed thoroughly until uniform, and then passed through a 200-mesh sieve to remove excess foaming agent powder to obtain a porous skeleton foaming agent.

[0047] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 90:25:20 and mixed in an internal mixer to obtain white internal mixer silica gel.

[0048] Then, a porous skeleton foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 9:800:3 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0049] (2) Preparation of foamed silica gel filter rod

[0050] The inner die of the silicone extruder was an equilateral triangle. A white micro-foam composite material was placed into the extruder. The extrusion speed was set so that the inner die produced a stroke of 40 mm per revolution. The extruded material was heated at 230°C to produce a filter rod with a circumference of 22 mm.

[0051] After cooling and shaping, the sample was cut into 100 mm pieces and recorded as sample 2.

[0052] Example 3 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0053] (1) Preparation of micro-foamed composite materials

[0054] The parameter is taken as specific surface area 28m 2 / g porous hydroxyapatite is dried at 110℃ for 3h. After drying, it is passed through an 80-mesh sieve to take the undersize material, and through a 200-mesh sieve to take the oversize material. The sieved porous hydroxyapatite is sprayed with silicone oil, and the amount of silicone oil sprayed is 10% of the weight of the porous hydroxyapatite. After wetting, it is sealed and balanced for 18h. After balance, the balanced porous hydroxyapatite, food-grade sodium carbonate and food-grade sodium bicarbonate are taken in a mass ratio of 80:3:7 and mixed thoroughly until uniform. Then, it is passed through a 200-mesh sieve to remove excess foaming agent powder to obtain a porous skeleton foaming agent.

[0055] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 80:20:15 and mixed in an internal mixer to obtain white internal mixer silica gel.

[0056] Then, a porous skeleton foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 7:750:2 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0057] (2) Preparation of foamed silica gel filter rod

[0058] The inner die of the silicone extruder was an equilateral triangle. A white micro-foam composite material was placed into the extruder. The extrusion speed was set so that the inner die had an extrusion stroke of 30 mm per revolution. The extruded material was heated at 200°C to produce a filter rod with a circumference of 22 mm.

[0059] After cooling and shaping, the sample was cut into 100 mm pieces and recorded as sample 3.

[0060] Example 4 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0061] (1) Preparation of micro-foamed composite materials

[0062] The parameter is a specific surface area of ​​35m 2 / g porous hydroxyapatite is dried at 105°C for 2.5 hours. After drying, it is passed through an 80-mesh sieve to take the undersize material, and through a 200-mesh sieve to take the oversize material. The sieved porous hydroxyapatite is sprayed with silicone oil, and the amount of silicone oil sprayed is 15% of the weight of the porous hydroxyapatite. After wetting, it is sealed and balanced for 6 hours. After balance, the balanced porous hydroxyapatite, food-grade sodium carbonate and food-grade sodium bicarbonate are taken in a mass ratio of 60:2:6 and mixed thoroughly until uniform, and then passed through a 200-mesh sieve to remove excess foaming agent powder to obtain a porous skeleton foaming agent.

[0063] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 60:15:15, and mixed in an internal mixer to obtain white internal mixer silica gel.

[0064] Then, a porous skeleton foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 3:200:1 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0065] (2) Preparation of foamed silica gel filter rod

[0066] The inner die of the silicone extruder was an equilateral triangle. A white micro-foam composite material was placed into the extruder. The extrusion speed was set so that the inner die had an extrusion stroke of 20 mm per revolution. The extruded material was heated at 180°C to produce a filter rod with a circumference of 22 mm.

[0067] After cooling and shaping, the sample was cut into 100 mm pieces and recorded as sample 4.

[0068] Example 5 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0069] (1) Preparation of micro-foamed composite materials

[0070] The parameter is surface area 26m 2 / g porous hydroxyapatite is dried at 100°C for 2h. After drying, it is passed through an 80-mesh sieve to take the undersize material, and through a 200-mesh sieve to take the oversize material. The sieved porous hydroxyapatite is sprayed with silicone oil, and the amount of silicone oil sprayed is 17% of the weight of the porous hydroxyapatite. After wetting, it is sealed and balanced for 2h. After balance, the balanced porous hydroxyapatite, food-grade sodium carbonate and food-grade sodium bicarbonate are taken in a mass ratio of 50:1:5 and mixed thoroughly until uniform, and then passed through a 200-mesh sieve to remove excess foaming agent powder to obtain a porous skeleton foaming agent.

[0071] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 50:10:10, and mixed in an internal mixer to obtain white internally mixed silica gel.

[0072] Then, a porous skeleton foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 1:100:1 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0073] (2) Preparation of foamed silica gel filter rod

[0074] The inner die of the silicone extruder was an equilateral triangle. A white micro-foam composite material was placed into the extruder. The extrusion speed was set so that the inner die produced a stroke of 10 mm per revolution. The extruded material was heated at 260°C to produce a filter rod with a circumference of 22 mm.

[0075] After cooling and shaping, the sample was cut into 100 mm pieces and recorded as sample 5.

[0076] Example 6

[0077] Investigate the consequences of using too low a dosage of porous skeleton foaming agent.

[0078] The same procedure as in Example 1 was followed, except that the amount of the porous skeleton foaming agent was reduced: when preparing the micro-foamed composite material, the porous skeleton foaming agent, the internal mixing silica gel, and the platinum vulcanizing agent were weighed in a mass ratio of 0.5:900:5, and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0079] The remaining steps, operations and parameters were the same as those in Example 1, and the obtained product was recorded as Sample 6.

[0080] Example 7

[0081] Investigate the consequences of using too high a dosage of porous skeleton foaming agent.

[0082] The same procedure as in Example 1 was followed, except that the amount of the porous skeleton foaming agent was increased: when preparing the micro-foamed composite material, the porous skeleton foaming agent, the internal mixing silica gel, and the platinum vulcanizing agent were weighed in a mass ratio of 15:900:5, and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0083] The remaining steps, operations and parameters were the same as those in Example 1, and the obtained product was recorded as Sample 7.

[0084] In addition, the following comparative examples respectively examine the effects of a porous skeleton foaming agent, a porous skeleton material, and a composite foaming agent on the final filter rod.

[0085] Comparative Example 1 Preparation of Micro-foamed Silica Gel Filter Rods without Porous Skeleton Foaming Agent

[0086] (1) Preparation of foamed composite materials without porous skeleton foaming agent

[0087] The steps, operations and parameters similar to those in Example 1 were used, except that no porous skeleton foaming agent (equivalent to a conventional silica gel filter rod) was used, namely:

[0088] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 100:30:30, and mixed in an internal mixer to obtain white internal mixer silica gel.

[0089] Internal mixing silica gel and platinum vulcanizer were weighed in a mass ratio of 900:5 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0090] (2) Preparation of micro-foamed silica gel filter rods

[0091] The same procedure as in Example 1 was followed, except that the inner die of the silicone extruder was an equilateral triangular die. The composite material was placed into the extruder, and the extrusion speed was set so that the extrusion stroke per rotation of the inner die was 50 mm. The extruded material was heated at 250°C to obtain a filter rod with a circumference of 22 mm.

[0092] The filter rod was thoroughly cooled until the material was solidified, resulting in a white, elastic, and strong cylinder. The filter rod was then cut into 100 mm pieces using a filter rod cutter, designated as Sample 8.

[0093] Comparative Example 2 Preparation of Micro-foamed Silica Gel Filter Rods without Food-grade Foaming Agent

[0094] (1) Preparation of composite materials without food-grade foaming agent

[0095] The same steps, operations and parameters as in Example 1 were used, except that no food-grade foaming agent was used, namely:

[0096] The parameter is that the specific surface area is 26m 2 / g porous hydroxyapatite was dried at 100°C for 8 hours. After drying, the sieve was passed through an 80-mesh sieve to remove the undersize fraction, and the sieve was passed through a 200-mesh sieve to remove the oversize fraction. The sieved porous hydroxyapatite was sprayed with silicone oil at a rate of 5% by weight of the porous hydroxyapatite. After wetting, the porous framework was sealed and equilibrated for 24 hours to obtain the porous framework.

[0097] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 100:30:30, and mixed in an internal mixer to obtain white internal mixer silica gel.

[0098] Then, the porous skeleton material, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 10:900:5 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0099] (2) Preparation of foamed silica gel filter rod

[0100] The same procedure as in Example 1 was followed, except that the inner die of the silicone extruder was an equilateral triangular die. The composite material was placed into the extruder, and the extrusion speed was set so that the extrusion stroke per rotation of the inner die was 50 mm. The extruded material was heated at 250°C to obtain a filter rod with a circumference of 22 mm.

[0101] The filter rod was cooled thoroughly until the material was solidified, resulting in a white, elastic, and strong cylinder. The filter rod was then cut into 100 mm pieces using a filter rod cutter, designated as Sample 9.

[0102] Comparative Example 3 Preparation of Micro-foamed Silica Gel Filter Rods Containing No Porous Skeleton Material

[0103] (1) Preparation of composite materials without porous skeleton materials

[0104] The steps, operations and parameters similar to those in Example 1 were used, except that no porous skeleton material was used, namely:

[0105] Food-grade sodium carbonate and food-grade sodium bicarbonate were weighed in a mass ratio of 5:10, and the mixture was thoroughly mixed to obtain a composite foaming agent.

[0106] Silica gel, white carbon black and calcium carbonate were weighed as raw materials in a mass ratio of 100:30:30, and mixed in an internal mixer to obtain white internal mixer silica gel.

[0107] Then, a multi-composite foaming agent, internal mixing silica gel and platinum vulcanizing agent were weighed in a mass ratio of 10:900:5 and mixed in an internal mixer to obtain a white micro-foamed composite material.

[0108] (2) Preparation of foamed silica gel filter rod

[0109] The same procedure as in Example 1 was followed, except that the inner die of the silicone extruder was an equilateral triangular die. The composite material was placed into the extruder, and the extrusion speed was set so that the extrusion stroke per rotation of the inner die was 50 mm. The extruded material was heated at 250°C to obtain a filter rod with a circumference of 22 mm.

[0110] The filter rod was thoroughly cooled until the material was solidified, resulting in a white, elastic, and strong cylinder. The filter rod was then cut into 100 mm pieces using a filter rod cutter, designated as Sample 10.

[0111] The main material differences of the above embodiments are shown in Table 1:

[0112] Table 1 Main material dosage of Examples 1-7

[0113] The appearance characteristics of the above 10 samples were examined, with traditional acetate fiber tow filter rods used as a control, as shown in Table 2.

[0114] Table 2 Comparison of appearance of samples in various embodiments

[0115] The results in Table 2 show that compared to conventional acetate filter rods, all silicone filter rods exhibit sharp, regular triangular edges. Even when the amount of porous skeleton foaming agent used in Examples 6 and 7 exceeded the design range, the edges remained relatively sharp, while the acetate filter rods exhibited less sharp edges. This difference is a product characteristic of the different primary materials (acetate and silicone). In Example 7, the excessive amount of porous skeleton foaming agent used also resulted in product deformation and burrs on the edges, resulting in poor hand feel and aesthetics.

[0116] As can be seen from Comparative Examples 1-3, the micro-foamed silica gel filter rod without a porous skeleton foaming agent (Comparative Example 1) can still maintain a good product appearance, consistent with the performance of Examples 1-5. This shows that the use of a porous skeleton foaming agent is not intended to improve the product appearance. However, the porous skeleton foaming agent should be understood as a group of material compositions with the significance of being used in combination. If only a porous skeleton material is used alone, or only a composite foaming agent is used (Comparative Examples 2 or 3), the product appearance will be affected, manifested as an unsmooth edge or burrs. It can be seen that the porous skeleton material should not be used alone.

[0117] Therefore, considering only the product appearance, the micro-foamed silica gel filter rod of the present invention and the silica gel filter rod without a porous skeleton foaming agent both have good appearance and are significantly better than the acetate fiber tow filter rod.

[0118] Furthermore, the performance of the above 10 samples was tested, and the results are shown in Table 3, including:

[0119] Porosity: According to the test method of GB / T 34709-2017 "General test method for silica gel - Determination of pore volume", the test was carried out using the BSD-TD fully automatic true density and porosity analyzer manufactured by Best Instrument Technology Co., Ltd.

[0120] Blade Replacement Frequency: Blade replacement frequency is defined as the number of filter rods that can be cut using conventional slitting equipment after the filter rods have been finalized. The average value is calculated based on 10 blade replacements. As is common knowledge in the field, blades in slitting equipment wear out with normal use. If the cut surface of a filter rod is uneven or burrs appear on the edges after slitting, the blade should be replaced to ensure a good product appearance.

[0121] Smoke Temperature: Smoke temperature is measured at the lip end of the heated cigarette. Puffs were conducted using a single-channel smoking machine in HCI mode, with a puff volume of 55 mL, a puff duration of 3 seconds, a puff interval of 30 seconds, and 10 puffs. After the start of the puff, the gas phase temperature at the center of the smoke outlet near the lip end of the heated cigarette was measured using a UT3208+ multi-channel temperature tester sold by Uni-Tec (China) Co., Ltd., and the average smoke temperature at each completed puff was measured.

[0122] Filter rod hardness: The filter rod hardness is tested according to the test method of GB / T 22838.6-2009 "Determination of physical properties of cigarettes and filter rods Part 6: Hardness" using the SHG-E cigarette and filter rod hardness tester manufactured by Chengdu Ruituo Technology Co., Ltd.

[0123] Rebound resilience: The rebound resilience is tested according to the test method of GB / T 1681-2009 "Determination of rebound resilience of vulcanized rubber" using the ZY-1011C touch screen rubber impact rebound testing machine manufactured by Yangzhou Zhengyi Testing Machinery Co., Ltd.

[0124] Sliding friction coefficient: The sliding friction coefficient is tested according to the test method of GB / T 10006-2021 "Plastics, films and sheets - Determination of coefficient of friction" using the MXD-02 friction coefficient meter manufactured by Jinan Saicheng Electronic Technology Co., Ltd.

[0125] Table 3 Comparison of filter rod performance

[0126] The results in Table 3 show that:

[0127] 1. Compared to conventional acetate filter rods, all silicone filter rods except those in Example 7 exhibited superior hardness and resilience, exhibited good deformation resistance, and were able to better maintain their appearance quality, meeting the physical performance requirements of cigarettes and filter rods. However, the sample in Example 7, due to its excessive porous material content, exhibited a higher degree of foaming, resulting in more pores in the filter rod, resulting in decreased hardness and resilience, making it unsuitable for use as a cigarette filter rod.

[0128] 2. Compared with the existing conventional acetate fiber filter rods, all silicone filter rods have better cooling effects, which may be related to the increase in the flue gas flow duct space inside the filter rod and the improvement of the flue gas flow duct shape and structure.

[0129] 3. Compared to conventional silica gel filter rods (Comparative Example 1), the micro-foamed silica gel filter rods of Examples 1-5, which added an appropriate amount of porous aggregate foaming agent, all exhibited a lower coefficient of sliding friction. This lower coefficient of sliding friction facilitates direct use of the filter rods on conventional cigarette-making machines, preventing the sticking of the silica gel product in cigarette-making equipment due to its inherent viscosity or high coefficient of sliding friction. This performance facilitates the compatibility of silica gel filter rods with conventional cigarette making equipment. However, the sample of Example 6, due to its low amount of porous aggregate foaming agent, exhibited a high coefficient of sliding friction, similar to conventional filter rods, and was therefore unsuitable for use.

[0130] 4. Compared to conventional acetate filter rods, the silicone material, due to its viscosity, causes greater wear on the blades of the slitting equipment, resulting in generally poor blade durability and a smaller number of products that can be cut with each new blade. Compared to a silicone filter rod without a porous aggregate foaming agent (Comparative Example 1), the present invention found that adding an appropriate proportion of a porous aggregate foaming agent can improve the blade durability of the slitting equipment, overcoming the poor blade durability of silicone filter rods. For example, in Example 1, the optimal solution, the blade durability is close to that of a conventional acetate filter rod.

[0131] 5. Compared with existing conventional silica gel filter rods (i.e., the product without a porous skeleton foaming agent in Comparative Example 1), although the use of a porous skeleton foaming agent leads to a slight decrease in hardness and rebound rate, the performance still meets the physical performance requirements of cigarettes and filter rods. Its higher porosity further improves the cooling performance of mainstream smoke, which is of great significance for improving the comfort of cigarette smoking.

[0132] In summary, the micro-foamed composite material of the present invention can be used to prepare a micro-foamed silica gel filter rod with an internal spiral structure. By adding an appropriate amount of porous skeleton foaming agent, on the one hand, the physical properties of the filter rod material are improved to enrich the appearance selectivity, which is conducive to obtaining a filter rod with a more complex cross-sectional hollow pattern. While further improving the flue gas cooling effect, the present invention found that the appropriate use of the porous skeleton foaming agent can also reduce the wear of the blade when the filter rod is subsequently cut using a cutting equipment, thereby reducing the frequency of blade replacement, thereby improving the durability of the equipment, and has good application prospects.

Claims

1. A method for preparing a micro-foamed composite material, comprising the following steps: (1) Preparation of porous skeleton foaming agent (1.1) A porous skeleton material having a particle size of 58 to 180 μm is prepared, wherein the porous skeleton material is selected from porous hydroxyapatite, perlite and / or porous silicon; (1.2) spraying the porous skeleton material obtained in step (1.1) with silicone oil to obtain a wetted material; (1.3) Weighing a wetting material and a food-grade foaming agent in a mass ratio of 50-100:6-15, mixing them evenly, and then passing them through a 200-mesh sieve to remove excess foaming agent on the surface of the material to obtain a porous skeleton foaming agent, wherein the food-grade foaming agent is sodium carbonate and / or sodium bicarbonate; (2) Preparation of mixed silica gel Weigh silica gel, white carbon black and calcium carbonate in a mass ratio of 50-100:10-30:10-30, and mix them in an internal mixer to obtain internally mixed silica gel; (3) Preparation of micro-foamed composite materials A porous skeleton foaming agent, internal mixing silica gel and a vulcanizing agent are weighed in a mass ratio of 1-10:100-900:1-5, and mixed in an internal mixer to obtain a micro-foamed composite material.

2. The preparation method according to claim 1, wherein The porous skeleton material of step (1.1) is obtained by drying at a temperature of 100-150°C for 2-8 hours. The specific surface area of ​​the porous hydroxyapatite, perlite and / or porous silicon of step (1.1) is 20-1000m 2 / g.

3. The preparation method according to claim 1, wherein In step (1.2), the mass ratio of silicone oil to porous framework material is 5 to 20:

100.

4. The preparation method according to claim 1, characterized in that In step (1.3), the wetting material, sodium carbonate and sodium bicarbonate are weighed in a mass ratio of 50-100:1-5:5-10 and mixed evenly.

5. The preparation method according to claim 1, characterized in that Step (3) also contains food coloring.

6. The preparation method according to claim 1, characterized in that The vulcanizing agent in step (3) is a platinum vulcanizing agent.

7. Use of the micro-foamed composite material obtained by the preparation method according to any one of claims 1 to 6 in a filter rod.

8. The use according to claim 7, characterized in that The filter rod is a heat-not-burn cigarette filter rod or a combustion-type cigarette filter rod.

9. A method for preparing a micro-foamed silica gel filter rod, the method comprising the following steps: (1) putting a micro-foam composite material into a silicone extruder with a rotating inner mold, and rotating to extrude a rod-shaped material, wherein the micro-foam composite material is a micro-foam composite material obtained by the preparation method according to any one of claims 1 to 5; (2) the obtained rod-shaped material is heated and vulcanized at 160-250° C. for 10-20 seconds; (3) The material obtained in step (2) is naturally cooled and then cut to obtain a micro-foamed silica gel filter rod.

10. The preparation method according to claim 9, characterized in that The porosity of the micro-foamed silica gel filter rod is 10% to 40%.

Images