Method for preparing degradable composite silica gel material and filter rod having microporous structure and prepared by using material

Abstract

The present invention provides a method for preparing a degradable composite silica gel material. The method comprises: preparing a silica gel matrix from a raw rubber, a reinforcing filler, and silicone oil, and then mixing a filling agent and the silica gel matrix to obtain a rubber compound, putting the rubber compound, a vulcanizing agent, a food-grade composite foaming agent, and plant fibers into a two-roll mill for open milling to obtain the degradable composite silica gel material. The composite silica gel material can be applied to a filter rod. The present invention further provides a cigarette filter rod having a microporous structure and prepared from the composite silica gel material. The filter rod having the microporous structure of the present invention can achieve lower draw resistance and better vapor cooling effect. The filter rod has relatively high hardness and rebound rate and relatively good deformation resistance and can maintain good appearance quality. It is ensured that the quality of the filter rod is stable, and the application requirements of traditional cigarettes and heat-not-burn cigarettes are met.

Description

A method for preparing a degradable composite silica gel material and a filter rod with a microporous structure prepared using the material

[0001] This invention claims a domestic priority, with priority number CN 2024103609195 and priority date March 27, 2024. Technical Field

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

[0003] Traditional cigarette filter rods largely utilize diacetate fiber tow as the filter rod material. However, because diacetate fiber filter rods are formed and pressed together from tow, their strength is relatively low, making it difficult to create intricate hollow patterns. This makes it difficult to improve the cooling effect of the filter rod on the smoke by designing a well-shaped smoke flow channel.

[0004] Chinese invention patent application CN 112273740A discloses a silicone cooling section for heat-not-burn products. This section is hollow and tubular, prefabricated from silicone using a conventional high-temperature curing method. The silicone in this section is made of food-grade silicone rubber, such as methyl silicone rubber, methyl vinyl silicone rubber, methyl vinyl phenyl silicone rubber, nitrile silicone rubber, or fluorosilicone rubber. However, this silicone cooling section is not porous, resulting in poor cooling performance. The smoke temperature is 41.3-43.5°C, making the smoke experience still quite hot.

[0005] Chinese invention patent application CN 104177831A discloses a food-grade silicone rubber foam product and its production method. The raw materials include fumed silicone rubber, precipitated silicone rubber, hollow glass microspheres, hydroxy silicone oil, platinum vulcanizer B, and platinum vulcanizer A. However, testing revealed that the cooling performance of the foam product did not meet the requirements for cigarette filter rods.

[0006] Several silicone rubbers are currently available, such as Chinese invention patent application CN105419341A, which discloses a low compression set silicone rubber. Its components include raw rubber with a vinyl content of 0.18% by molar, raw rubber with a vinyl content of 0.30% by molar, precipitated silica, hydroxyl silicone oil, hydrogenated silicone oil, and stearic acid. However, because this material is not a foamable material and lacks cooling properties, it does not meet the requirements for cigarette filter rods. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a new composite silica gel material. This composite silica gel material can be used to prepare a cigarette filter rod with a microporous structure, so as to obtain better smoke cooling effect and filter rod processing performance, and at the same time, it should have the physical properties that a cigarette filter rod should have.

[0008] Based on this, a method for preparing a degradable composite silica gel material is provided, the preparation method comprising the following steps:

[0009] (1) Preparation of silica gel matrix

[0010] Weighing 8 to 12 parts of raw rubber, 0.5 to 2 parts of reinforcing filler, and silicone oil in a mass ratio of 0.2 to 1 parts and mixing them evenly to obtain a silicone rubber composite; the raw rubber is selected from one or more of methyl vinyl silicone, dimethyl silicone, and / or methyl phenyl vinyl silicone, and the Shore hardness of the raw rubber is 10 to 30;

[0011] (2) Secret refining

[0012] Weighing 0.8-1.3 parts of the filler and the silica gel matrix in a mass ratio of 2-5 parts, placing them in an internal mixer and mixing them at 120° C. to 180° C. to obtain an internal mixer;

[0013] (3) Opening of Refining

[0014] 80-100 parts of internal mixing rubber, a vulcanizing agent, a food-grade composite foaming agent and plant fibers are weighed in a mass ratio of 0.1-1:0.1-2:3-15 parts, wherein the plant fibers have an average fiber length of 0.5-6 mm, and the mixture is placed in a double-roll mill for refining to obtain a degradable composite silica gel material.

[0015] In the present invention, the reinforcing filler in step (1) is selected from white carbon black and / or titanium dioxide; and the silicone oil is selected from hydroxy silicone oil and / or methoxy silicone oil. Generally, when the reinforcing filler is a mixture of white carbon black and titanium dioxide, their ratio is not particularly limited. When the silicone oil is a mixture of hydroxy silicone oil and methoxy silicone oil, their ratio is also generally not particularly limited.

[0016] The internal mixing in step (2) is known to those skilled in the art and is typically performed using an internal mixer at a speed of 20 to 50 r / min and a temperature of 120° C. to 180° C. for 10 to 20 minutes. The temperature, speed, and mixing time are conventionally selected in the art, and those skilled in the art may also appropriately adjust the operating parameters of the internal mixing equipment according to the operating conditions and environmental conditions.

[0017] According to a preferred embodiment, the filler used in step (3) is selected from one or more fillers selected from calcium carbonate, white carbon black, quartz powder, and / or wollastonite powder. The filler used in this step can be the same material as the reinforcing filler used in step (1) (e.g., white carbon black), or different materials can be used.

[0018] Particularly preferably, the food-grade composite foaming agent in the above step (3) contains, in parts by mass:

[0019] 80-120 parts of sodium bicarbonate

[0020] 40-60 parts of food grade modifier

[0021] 30-50 parts of raw rubber

[0022] Wherein, the modifier is selected from one or more modifiers of anhydrous citric acid, stearic acid, glyceryl monostearate, and erucamide;

[0023] The preparation method of the food-grade composite foaming agent is:

[0024] A food-grade modifier is dissolved in 2.5 to 6 times the mass of anhydrous ethanol, and sodium bicarbonate is added after being mixed evenly. The evenly mixed materials are continuously stirred at a speed of 300 to 600 rpm and a temperature of 15 to 20° C. until the ethanol is completely volatilized. The resulting product is dried at 40 to 60° C. for 10 to 20 minutes to obtain dried modified sodium bicarbonate. The modified sodium bicarbonate is ground in a grinder and then sieved through a 100-mesh sieve to obtain modified sodium bicarbonate powder, which is evenly mixed with raw rubber and then sealed and stored at room temperature for 12 to 24 hours to obtain a food-grade composite foaming agent.

[0025] Unlike the prior art, which uses a single sodium bicarbonate as a food foaming agent, the food-grade composite foaming agent of the present invention contains a modifier that increases the decomposition temperature of sodium bicarbonate, narrows the decomposition temperature range, and increases the decomposition rate, thereby preventing the sodium bicarbonate from being prematurely decomposed and lost during the plasticating or pre-molding steps, which would result in a poor foaming effect, thereby ensuring that the foaming effect of the material is sufficient and stable. In addition, when preparing the composite foaming agent, raw rubber is added as a skeleton material, and the resulting composite foaming agent is added to the silica gel matrix during the refining step, which facilitates mixing of the foaming agent and the silica gel matrix during the refining process, ensuring sufficient foaming, and different batches of products have a stable and uniform effect.

[0026] In this invention, the amount of food-grade composite foaming agent added is within the optimal range confirmed through extensive experimentation. If the amount of composite foaming agent is insufficient, the resulting filter rod will have a low porosity, resulting in extremely high draw resistance and poor flue gas cooling. If the composite foaming agent is excessive, the filter rod will have low hardness and rebound rate, a soft and collapsed appearance, unstable quality, and may even fail to meet the physical performance requirements.

[0027] Compared with conventional food-grade foaming agents (for example, using a single sodium bicarbonate), the composite foaming agent of the present invention has better performance, which is manifested as a more suitable draw resistance and a better smoke cooling effect. If only a modifier is used as a foaming agent, since the modifier does not have a foaming effect, the cooling and draw resistance reducing effects of the filter rod of the present invention cannot be achieved. If only sodium bicarbonate is used as a foaming agent, the foaming effect is poor, the foaming is uneven, the uniformity between different product batches is poor, and it is easy to cause the porosity of the filter rod to be low, making it difficult to play the role of cooling the smoke and reducing the draw resistance. If only a food-grade modifier is added to sodium bicarbonate but no silica gel is added, there are also problems of uneven foaming effect and poor uniformity between different product batches, and the product quality is unstable. If only raw rubber is added to sodium bicarbonate, the foaming effect is still poor, and the smoke cooling effect is insufficient. Therefore, food-grade modifiers and raw rubber need to be used in combination with sodium bicarbonate to achieve the best filter rod performance.

[0028] In step (3), the plant fibers are selected from one or more fibers selected from flax, jute, sisal, ramie, and abaca. In the present invention, using plant fibers as the skeleton support material of the silica gel system can improve the strength and performance of the silica gel rod and reduce the deformation of the product. In addition, the addition of plant fibers can accelerate the degradation rate of the product, thereby improving the environmental performance of the product. Therefore, these plant fibers can be used individually or in combination. When used in combination, their proportions are generally not limited.

[0029] Based on this, the present invention also provides the use of the degradable composite silica gel material obtained by the above preparation method in a filter rod.

[0030] In the present invention, the filter rod can be a heat-not-burn cigarette filter rod or a combustion-type cigarette filter rod. The filter rod of the present invention can replace traditional filter rods (such as acetate fiber tow filter rods) to achieve the effects of cooling smoke and adsorbing harmful substances.

[0031] Furthermore, the present invention also provides a method for preparing a degradable filter rod having a microporous structure, the preparation method comprising the following steps:

[0032] The biodegradable composite silica gel material obtained by the above preparation method is placed in an extruder, preformed at 25-85°C for 1-5 minutes, then cross-linked and foamed at 120-180°C and extruded, and cooled to obtain a rod-shaped material;

[0033] The obtained rod-shaped material is cut into composite silica gel material strips;

[0034] The composite silica gel material strip is treated at 150-200 DEG C for 6-12 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0035] The purpose of preforming the composite silicone material at a relatively low temperature is to properly condition the composite silicone material to facilitate subsequent foaming and extrusion at a higher temperature. Both preforming and cross-linking and foaming are performed in an extruder. Those skilled in the art can adjust the preforming temperature and time appropriately based on the specific state of the composite silicone material to ensure that the extruded material is fully cross-linked and foamed, resulting in a rod-shaped shape after cooling.

[0036] In the present invention, the silicone extruder, for example, the 80 silicone tube extrusion equipment product produced and sold by Hebei Xulang Machinery Manufacturing Co., Ltd., can be used. During use, the operating parameters of the extruder can be adjusted to control the ratio of the rotation speed of the inner mold to the extrusion speed 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 options of the filter rod end.

[0037] The density of the filter rod obtained by the present invention is usually 0.2 to 0.8 g / cm 3 The porosity is 20-50%, which can be obtained by testing with a porosity detector. Those skilled in the art can adjust the foaming time to control the foaming degree, thereby adjusting the density of the obtained product.

[0038] The degradable composite silica gel material of the present invention can be used to prepare special-shaped filter rods. Compared with conventional acetate fiber filter rods, the degradable filter rod with a microporous structure of the present invention can achieve lower suction resistance and better smoke cooling effect. In addition, the filter rod has high hardness and rebound rate, good deformation resistance, can maintain good appearance quality, ensure the stability of the filter rod quality, and meet the application requirements of traditional cigarettes and heat-not-burn cigarettes.

[0039] The present invention further improves the cooling performance of the microporous filter rod by improving the formula of the foaming agent, appropriately reduces the suction resistance of the filter rod, and thus achieves a better suction experience. DETAILED DESCRIPTION

[0040] The following examples are used to illustrate the technical solutions of the present invention in a non-limiting manner.

[0041] 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.

[0042] Example 1 Preparation of micro-foamed silica gel filter rod with inner spiral structure

[0043] Preparation of internal compound:

[0044] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 8:0.5:0.2 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were weighed in a ratio of 1:2 and mixed in an internal mixer at 150°C to obtain an internal compound.

[0045] Preparation of food-grade composite foaming agent:

[0046] Weigh 80:40:30 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 300 rpm and 20°C until the ethanol evaporates completely. Dry the resulting product at 60°C for 20 minutes to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0047] Preparation of composite silicone materials:

[0048] Internal mixing rubber, platinum vulcanizing agent, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) were weighed in a ratio of 80:0.2:0.2:3, and the mixture was placed on a double-roll mill for refining to obtain a biodegradable composite silica gel material.

[0049] Prepare filter sticks:

[0050] The composite silicone material was placed in an extruder (with a regular hexagonal die) and heated at 60°C for 3 minutes. The extruder was then heated to 160°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with a hexagonal hollow channel was obtained. The composite silicone material was then cut into 120 mm lengths to obtain strips.

[0051] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0052] Example 2 Preparation of micro-foamed silica gel filter rod with inner spiral structure

[0053] Preparation of internal compound:

[0054] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 8:0.5:0.5 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were weighed and mixed in a ratio of 0.8:2 to obtain a silica gel matrix. The mixture was then mixed in an internal mixer at 155° C. to obtain an internal compound.

[0055] Preparation of food-grade composite foaming agent:

[0056] Weigh 80:50:40 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 400 rpm until the ethanol evaporates completely. Dry the resulting product at 65°C to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate the mixture in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0057] Preparation of composite silicone materials:

[0058] Weigh 80:0.5:0.5:5 parts of internal mixing rubber, platinum vulcanizer, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) and place them in a double-roll mill for refining to obtain a degradable composite silica gel material.

[0059] Prepare filter sticks:

[0060] The composite silicone material was placed in an extruder at 55°C for 3 minutes, then heated to 170°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with hexagonal hollow channels was obtained. The composite silicone material was then cut into 120mm lengths to obtain strips.

[0061] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0062] Example 3 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0063] Preparation of internal compound:

[0064] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 8:1:1 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were weighed in a ratio of 1.2:2 and mixed in an internal mixer at 155° C. to obtain an internal compound.

[0065] Preparation of food-grade composite foaming agent:

[0066] Weigh 100:40:30 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 400 rpm until the ethanol evaporates completely. Dry the resulting product at 65°C to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate the mixture in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0067] Preparation of composite silicone materials:

[0068] Internal mixing rubber, platinum vulcanizing agent, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) were weighed in a ratio of 90:0.5:1:6, and the mixture was placed on a double-roll mill for refining to obtain a biodegradable composite silica gel material.

[0069] Prepare filter sticks:

[0070] The composite silicone material was placed in an extruder at 55°C for 5 minutes, then heated to 170°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with hexagonal hollow channels was obtained. The composite silicone material was then cut into 120mm lengths to obtain strips.

[0071] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0072] Example 4 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0073] Preparation of internal compound:

[0074] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 10:1:1 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were then weighed and mixed in a ratio of 1:3 and mixed in an internal mixer at 155° C. to obtain an internal compound.

[0075] Preparation of food-grade composite foaming agent:

[0076] Weigh 100:50:50 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 400 rpm until the ethanol evaporates completely. Dry the resulting product at 65°C to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate the mixture in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0077] Preparation of composite silicone materials:

[0078] Internal mixing rubber, platinum vulcanizing agent, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) were weighed in a ratio of 90:0.8:1:6, and the mixture was placed on a double-roll mill for refining to obtain a biodegradable composite silica gel material.

[0079] Prepare filter sticks:

[0080] The composite silicone material was placed in an extruder at 55°C for 5 minutes, then heated to 170°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with hexagonal hollow channels was obtained. The composite silicone material was then cut into 120mm lengths to obtain strips.

[0081] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0082] Example 5 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0083] Preparation of internal compound:

[0084] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 12:1:1 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were weighed in a ratio of 1.2:3 and mixed in an internal mixer at 155° C. to obtain an internal compound.

[0085] Preparation of food-grade composite foaming agent:

[0086] Weigh 120:60:40 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 400 rpm until the ethanol evaporates completely. Dry the resulting product at 65°C to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate the mixture in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0087] Preparation of composite silicone materials:

[0088] Internal mixing rubber, platinum vulcanizing agent, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) were weighed in a ratio of 95:1:1.5:10, and the mixture was placed on a double-roll mill for refining to obtain a biodegradable composite silica gel material.

[0089] Prepare filter sticks:

[0090] The composite silicone material was placed in an extruder at 55°C for 5 minutes, then heated to 170°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with hexagonal hollow channels was obtained. The composite silicone material was then cut into 120mm lengths to obtain strips.

[0091] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0092] Example 6 Preparation of Micro-foamed Silica Gel Filter Rod with Inner Helical Structure

[0093] Preparation of internal compound:

[0094] Methyl vinyl silica gel, white carbon black, and titanium dioxide were weighed and mixed in a ratio of 12:2:1 to obtain a silica gel matrix. Calcium carbonate and the silica gel matrix were weighed and mixed in a ratio of 1.3:5 to obtain a silica gel matrix. The mixture was then mixed in an internal mixer at 155°C to obtain an internal mixer rubber.

[0095] Preparation of food-grade composite foaming agent:

[0096] Weigh 120:60:50 parts of sodium bicarbonate, stearic acid, and methyl vinyl silica gel. Dissolve the stearic acid in 5 times the weight of anhydrous ethanol, mix thoroughly, then add the sodium bicarbonate. After mixing thoroughly, continue stirring at 400 rpm until the ethanol evaporates completely. Dry the resulting product at 65°C to obtain dry modified sodium bicarbonate. Grind the modified sodium bicarbonate in a grinder and pass it through a 100-mesh sieve to obtain modified sodium bicarbonate powder. Mix the powder with methyl vinyl silica gel and equilibrate the mixture in a sealed container at room temperature for one day to obtain a food-grade composite foaming agent.

[0097] Preparation of composite silicone materials:

[0098] 100:1:2:15 parts of internal mixing rubber, platinum vulcanizing agent, food-grade composite foaming agent and flax fiber (average fiber length of 3 mm) were weighed and placed on a double-roll mill for refining to obtain a biodegradable composite silica gel material.

[0099] Prepare filter sticks:

[0100] The composite silicone material was placed in an extruder at 55°C for 5 minutes, then heated to 170°C for high-temperature crosslinking and foaming, followed by extrusion. After natural cooling, a rod-shaped material with hexagonal hollow channels was obtained. The composite silicone material was then cut into 120mm lengths to obtain strips.

[0101] The composite silica gel material strip is treated at 180° C. for 8 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

[0102] Comparative Example 1: Insufficient dosage of food-grade composite foaming agent

[0103] The same process as in Example 2 was carried out, except that when preparing the composite silicone material, the mass ratio of the internal mixing rubber, the platinum vulcanizing agent, the food-grade composite foaming agent and the flax fiber was 80:0.5:0.01:5.

[0104] Comparative Example 2: Excessive use of food-grade composite foaming agent

[0105] The same process as in Example 2 was carried out, except that when preparing the composite silicone material, the mass ratio of the internal mixing rubber, the platinum vulcanizing agent, the food-grade composite foaming agent and the flax fiber was 80:0.5.5:5.

[0106] Comparative Example 3: Substituting Sodium Bicarbonate for Food-Grade Composite Foaming Agent

[0107] Sodium bicarbonate, a commonly used food-grade foaming agent, can also produce bubbles under heating conditions. Sodium bicarbonate was used to replace the composite foaming agent of the present invention to examine the effects of different foaming agents on product performance.

[0108] The same process as in Example 2 was carried out, except that when preparing the composite silica gel material, the mass ratio of sodium bicarbonate, stearic acid, and methyl vinyl silica gel was 80:0:0.

[0109] Comparative Example 4: Using Sodium Bicarbonate + Modifier to Replace Food-Grade Composite Foaming Agent

[0110] Food-grade foaming agents also contain raw rubber, and the impact of this raw rubber on product performance is examined.

[0111] The same process as in Example 2 was carried out, except that when preparing the composite silica gel material, the mass ratio of sodium bicarbonate, stearic acid, and methyl vinyl silica gel was 80:50:0.

[0112] Comparative Example 5: Using Sodium Bicarbonate + Raw Rubber to Replace Food-Grade Composite Foaming Agent

[0113] Investigate the effect of modifiers in food-grade composite foaming agents on product performance.

[0114] The same process as in Example 2 was carried out, except that when preparing the composite silica gel material, the mass ratio of sodium bicarbonate, stearic acid, and methyl vinyl silica gel was 80:0:50.

[0115] The main material differences of the above embodiments are shown in Table 1:

[0116] Table 1 Main material usage of each embodiment

[0117] The appearance characteristics of the above 11 samples were examined, with traditional acetate fiber tow filter rods used as a control, as shown in Table 2.

[0118] Table 2 Comparison of appearance of samples in various embodiments

[0119] The results in Table 2 show that compared with the existing conventional acetate filter rods, which have less sharp edges in appearance, all silicone filter rods have the characteristic of sharp edges. This difference is a product characteristic brought about by the different main materials (i.e., acetate and silicone).

[0120] In Comparative Example 1, insufficient use of the composite foaming agent did not affect the product appearance. Comparative Examples 3-5, using sodium bicarbonate as the primary composite foaming agent, also maintained a good product appearance. However, in Comparative Example 2, excessive use of the composite foaming agent caused the product to become soft and collapse, failing to maintain its appearance quality.

[0121] From this, it can be seen that the purpose of using a composite foaming agent is not to further improve the product appearance. When sodium bicarbonate is used alone to replace the composite foaming agent, a good product appearance can still be achieved.

[0122] The special-shaped filter rods prepared using the degradable microporous material of the present invention have the characteristics of smooth and sharp special-shaped edges and uniform shape. Compared with conventional acetate fiber filter rods, the silicone filter rods greatly improve the fineness and complexity of the hollow pattern, making the filter rods more diversified, and their appearance quality is stable, with broad application prospects.

[0123] Furthermore, the performance of the above samples was tested. The results are shown in Table 3. The test items include:

[0124] 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.

[0125] Rebound rate: The rebound rate is tested according to the test method of GB / T 1681-2009 "Determination of the rebound elasticity of vulcanized rubber" using a CREE-7006D compression rebound testing machine manufactured by Dongguan Cree Instrument Technology Co., Ltd.

[0126] 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.

[0127] 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 HX-TB open and closed porosity tester manufactured by Shandong Haixi Instrument Co., Ltd.

[0128] Draw resistance: According to the test method of GB / T 22838.5-2009 "Determination of physical properties of cigarettes and filter rods Part 5: Cigarette draw resistance and filter rod pressure drop", the test was conducted using the AT-XZC draw resistance tester manufactured by Shandong Animeite Instrument Co., Ltd.

[0129] Density: Density is tested according to GB / T 533-2008 “Determination of density of vulcanized rubber or thermoplastic rubber” using a silicone rubber density meter manufactured by Hangzhou Jinmai Instrument Co., Ltd.

[0130] Table 3 Comparison of filter rod performance

[0131] The filter rod performance comparison results listed in Table 3 show that:

[0132] 1. Compared to conventional acetate filter rods, all silicone filter rods except those in Comparative Example 2 exhibited excellent hardness and resilience, meaning they exhibited excellent deformation resistance, better maintaining their appearance quality, and meeting the physical performance requirements of cigarettes and filter rods. However, the sample in Comparative Example 2, due to the excessive amount of composite foaming agent, exhibited a higher degree of foaming, resulting in more pores in the filter rod and excessive porosity, leading to decreased hardness and resilience, making it unsuitable for use as a cigarette filter rod.

[0133] 2. Compared with conventional acetate filter rods, all filter rods of the present invention exhibit superior cooling performance. In Example 1, the insufficient amount of composite foaming agent resulted in a low degree of foaming, resulting in low porosity, high density, and poor cooling performance. This indicates that the specific amount of composite foaming agent used not only affects product strength but also the cooling performance of the filter rod.

[0134] 3. The choice of foaming agent has a significant impact on the cooling performance of the filter rod. Comparative Example 3 uses conventional sodium bicarbonate as the foaming agent. Although the cooling performance of the resulting product is slightly better than that of the conventional acetate fiber filter rod, it is not as good as the filter rod of the present invention using the composite foaming agent.

[0135] 4. In Comparative Examples 4 and 5, the raw rubber and modifier were removed from the composite foaming agent, respectively. Comparing Comparative Example 3 with Example 2, it can be seen that the addition of the modifier improves the foaming performance of sodium bicarbonate, resulting in slightly better foaming and cooling performance than in Comparative Example 3. However, the lack of raw rubber may make it more difficult to mix the foaming agent with the other materials in the subsequent open milling step, resulting in inferior foaming and cooling performance compared to Example 2.

[0136] In summary, the special-shaped filter rod prepared using the degradable microporous material of the present invention has good application performance. Compared with conventional acetate fiber filter rods, the degradable filter rod with a microporous structure of the present invention has lower suction resistance and better smoke cooling effect, and its hardness and rebound rate are high, and it has good deformation resistance, can maintain good appearance quality, ensure the stability of the filter rod quality, and meet the application requirements of traditional cigarettes and heat-not-burn cigarettes.

[0137] The present invention further improves the cooling performance of the silica gel filter rod by improving the formula of the foaming agent, appropriately reduces the suction resistance of the filter rod, and thus achieves a better suction experience.

[0138] In summary, the degradable microporous material of the present invention not only solves the problem of using ordinary silicone materials in cigarette filters, but also improves the degradability of silicone materials, increases the material selection and pattern richness of hollow filter rods, has a good cooling effect, and has good application prospects.

Claims

1. A method for preparing a degradable composite silica gel material, the method comprising the following steps: (1) Preparation of silica gel matrix Weighing 8 to 12 parts of raw rubber, 0.5 to 2 parts of reinforcing filler, and silicone oil in a mass ratio of 0.2 to 1 parts and mixing them evenly to obtain a silicone matrix; the raw rubber is selected from one or more of methyl vinyl silicone, dimethyl silicone, and methylphenyl vinyl silicone, and the Shore hardness of the raw rubber is 10 to 30; (2) Secret refining Weighing 0.8-1.3 parts of the filler and the silica gel matrix in a mass ratio of 2-5 parts, placing them in an internal mixer and mixing them at 120° C. to 180° C. to obtain an internal mixer; (3) Opening of Refining 80-100 parts of internal mixing rubber, a vulcanizing agent, a food-grade composite foaming agent and plant fibers are weighed in a mass ratio of 0.1-1:0.1-2:3-15 parts, wherein the plant fibers have an average fiber length of 0.5-6 mm, and the mixture is placed in a double-roll mill for refining to obtain a degradable composite silica gel material.

2. The preparation method according to claim 1, wherein In step (1), the reinforcing filler is selected from white carbon black and / or titanium dioxide; and the silicone oil is selected from hydroxy silicone oil and / or methoxy silicone oil.

3. The preparation method according to claim 1, wherein In step (3), the filler is selected from one or more fillers selected from calcium carbonate, white carbon black, quartz powder and / or wollastonite powder.

4. The preparation method according to claim 1, characterized in that In step (3), the food-grade composite foaming agent contains, by mass: 80-120 parts of sodium bicarbonate 40-60 parts of food-grade modifier 30-50 parts of raw rubber Wherein, the modifier is selected from one or more modifiers of anhydrous citric acid, stearic acid, glyceryl monostearate, and erucamide; The preparation method of the food-grade composite foaming agent is: A food-grade modifier is dissolved in 2.5 to 6 times the mass of anhydrous ethanol, mixed evenly, and then sodium bicarbonate is added. After mixing evenly, stirring is continued at a speed of 300 to 600 rpm and a temperature of 15 to 20° C. until the ethanol is completely volatilized. The resulting product is dried at 40 to 60° C. for 10 to 20 minutes to obtain dried modified sodium bicarbonate; the modified sodium bicarbonate is placed in a grinder for grinding and then sieved through a 100-mesh sieve to obtain modified sodium bicarbonate powder, which is mixed evenly with raw rubber and then sealed and placed at room temperature for 12 to 24 hours to obtain a food-grade composite foaming agent.

5. The preparation method according to claim 1, characterized in that In step (3), the plant fiber is selected from one or more fibers of flax, jute, sisal, ramie and abaca.

6. Use of the degradable composite silica gel material obtained by the preparation method according to any one of claims 1 to 5 in a filter rod.

7. The use according to claim 6, characterized in that The filter rod is a heat-not-burn cigarette filter rod or a combustion-type cigarette filter rod.

8. A method for preparing a degradable filter rod having a microporous structure, characterized in that The preparation method comprises the following steps: The degradable composite silica gel material obtained by the preparation method according to any one of claims 1 to 5 is placed in an extruder, preformed at 25 to 85° C. for 1 to 5 minutes, cross-linked and foamed at 120 to 180° C. and extruded, and cooled to obtain a rod-shaped material; The obtained rod-shaped material is cut into composite silica gel material strips; The composite silica gel material strip is treated at 150-200 DEG C for 6-12 hours, and a degradable filter rod with a microporous structure is obtained after heat setting.

9. The preparation method according to claim 8, characterized in that The density of the filter rod is 0.2-0.8 g / cm 3 , the porosity is 20-50%.

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