Phenol-reduced paper composite filter material as well as preparation method and application thereof

Abstract

The invention discloses a phenol-reducing paper composite filter material as well as a preparation method and application thereof, and the preparation method comprises the following steps: adding a compound A and triethylamine into water to prepare a solution A; metal salt is dissolved in water, and a solution B is prepared; quantitatively transferring the solution A to the surface of a paper base material, and after the surface tension of a liquid film is balanced for 10-30 seconds, coating the solution B in a stacked manner by the same process; the coated paper base material passes through a low-temperature tunnel with the temperature ranging from-5 DEG C to 10 DEG C in a continuous conveying mode; and guiding the self-assembled paper base material into a multi-section drying cylinder drying system, and drying to obtain the phenol-reduced paper composite filter material. The prepared paper composite filter material has a micro-nano composite structure, can increase the specific surface area in contact with smoke, can be in full contact with the smoke in the process that the smoke passes through a filter stick, improves the interception capacity of a paper filter stick to phenol in mainstream smoke of cigarettes by utilizing amino groups and ester groups on the surfaces of nanofibers, and improves the cigarette quality. And the sensory quality of the paper filter stick cigarette can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of cigarette filter rods, and more particularly to a phenol-reducing paper composite filter material, a preparation method thereof, and applications thereof. Background Art

[0002] In recent years, with growing public health awareness and the advancement of tobacco control policies, the cigarette industry has accelerated its research and development of low-tar products. Innovation in filter rod materials has attracted considerable attention in the design and development of low-tar, low-harm cigarettes.

[0003] Paper filter rods are made from creped paper primarily composed of plant fibers through embossing and bunching processes. They offer advantages such as low raw material costs, biodegradability, and environmental friendliness. Research has found that, at the same pressure drop, paper filter rods retain tar and nicotine more efficiently than acetate filter rods.

[0004] However, the filter material and physical structure of paper filter rods differ significantly from those of acetate filter rods. Consumers generally perceive paper filter rods as causing negative sensory issues, such as a "papery" smell and a strong, pungent, and irritating smoke. This negatively impacts their acceptance. This issue with paper filter rods may be primarily due to two factors: first, plant fibers primarily have hydroxyl groups, while acetate fiber primarily has acetyl groups. These two functional groups exhibit significant differences in their adsorption properties and effectiveness for ammonia and phenol in mainstream smoke. Second, acetate filter rods incorporate triacetin as a plasticizer during processing, while paper filter rods do not, being formed solely through embossing and bunching. Triacetin interacts strongly with phenols, resulting in better retention of these compounds. For these two reasons, paper filter rods are less effective than acetate filter rods in retaining harmful phenolic compounds in smoke. Furthermore, due to the difference in polarity of the main functional groups between plant fibers and acetate fibers, the selectivity and effectiveness of adsorption of other chemicals in the flue gas will also be affected, which may also lead to the "paper smell" of paper filter rods. From the above, it can be seen that the "paper smell" is caused by the inherent chemical structure and properties of plant fibers, and is not emitted by the paper filter rod itself.

[0005] Therefore, how to improve the retention capacity of paper filter rods for phenolic substances and improve the sensory quality of paper filter rods is of great significance for the development of low-tar cigarettes and the work of reducing tar and reducing harm of cigarettes. Summary of the Invention

[0006] One object of the present invention is to provide a new technical solution for paper filter material which can effectively improve the retention capacity of paper filter rods for phenolic substances and improve the sensory quality of paper filter rods.

[0007] According to a first aspect of the present invention, there is provided a method for preparing a phenol-reducing paper composite filter material, comprising the following steps:

[0008] Step (1): Add compound A containing a purine skeleton and triethylamine to water at a molar ratio of 1:(0.5-2), and stir at a constant temperature of 60-90°C for 30-120 minutes to prepare a solution A with a concentration of 0.1mM-1.5mM; dissolve the metal salt in water, and stir and dissolve at 25-40°C to prepare a solution B with a concentration of 0.3mM-1.5mM;

[0009] Step (2): respectively transferring solution A and solution B to the liquid reservoir A and liquid reservoir B of a dual-reservoir gravure printing device, using a ceramic anilox roller with a line count of 100-300 lines per inch and a groove depth of 20-50 μm, first quantitatively transferring solution A to the surface of the paper substrate at a coating speed of 0.5-2.0 m / min, and after the surface tension of the liquid film is balanced for 10-30 seconds, coating solution B in the same manner;

[0010] Step (3): The coated paper substrate is continuously conveyed through a low-temperature tunnel at -5-10°C and maintained at a relative humidity of 40-60% for 10-20 minutes to in situ self-assemble into a three-dimensional nanofiber network with a diameter of 10-100 nm inside and on the surface of the paper substrate;

[0011] Step (4): The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C and 90°C. The residence time ratio of each temperature zone is 1:2:1, so that the coating amount is 0.01-0.50g / m 2 Phenol-reducing paper composite filter material.

[0012] Optionally, the compound A in step (1) is selected from at least one of xanthine, adenine, guanine, caffeine, theophylline, and theobromine.

[0013] Optionally, the metal salt in step (1) is selected from at least one of ferric chloride, zinc nitrate, copper chloride, copper nitrate, cobalt nitrate, and nickel nitrate.

[0014] Optionally, in step (2), the molar ratio of compound A coated on the surface of the paper substrate to the metal salt is 1:(1-3).

[0015] Optionally, a gradient cooling zone is provided in the low-temperature tunnel in step (3), and the gradient cooling zone is specifically as follows:

[0016] First temperature zone: 10±2℃, residence time is 3-5 minutes;

[0017] Second temperature zone: 5±1℃, residence time is 6-10 minutes;

[0018] The third temperature zone: 0±1℃, residence time is 3-5 minutes.

[0019] According to a second aspect of the present invention, a phenol-reducing paper composite filter material is provided, which is prepared by the preparation method of the present invention.

[0020] According to a third aspect of the present invention, there is provided an application of the phenol reduction paper composite filter material described in the present invention, which is used for cigarette filter rods.

[0021] Optionally, the cigarette filter rod comprises an acetate segment and a paper segment, the filter material in the paper segment is a phenol-reducing paper composite filter material, and the paper segment is located at the end of the cigarette filter rod near the tobacco shreds.

[0022] Beneficial effects of the present invention:

[0023] 1. Metal-organic compounds synergistically reduce the release of phenol in mainstream cigarette smoke: Transition metal ions are used to induce small organic molecules rich in amino, ester, and aldehyde groups to self-assemble under low temperature conditions, forming nanofibers on the surface and inside of paper filter materials, which can significantly enhance the paper filter material's ability to retain phenol in mainstream cigarette smoke.

[0024] 2. Process Breakthrough: A dual-reservoir gravure printing process is introduced during the coating and modification of paper filter media. Organic compound solutions and metal salt solutions are transferred to the surface of the paper filter media via gradient printing. This process, induced by transition metal ions, forms self-assembled nanofibers at low temperatures. This proposed process overcomes the limitations of traditional impregnation methods and provides a new approach to the coating and modification of paper filter media.

[0025] 3. Cost and environmental advantages: The coating amount of the functional material with the ability to selectively reduce phenol release is low (0.05~1g / m 2 ), and the coating liquid is all aqueous solution, no organic solvent is used, and the wastewater treatment burden during the production process is low.

[0026] 4. Optimization of the sensory quality of cigarettes: The paper composite filter material prepared by the present invention has a micro-nano composite structure, which can increase the specific surface area in contact with the smoke. During the process of the smoke passing through the filter rod, it can fully contact with the smoke. The amino and ester groups on the surface of the nanofibers are used to improve the paper filter rod's ability to retain phenol in the mainstream cigarette smoke, which can effectively improve the sensory quality of paper filter rod cigarettes. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0028] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0029] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0030] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0031] The preparation method of the phenol reduction paper composite filter material provided by the present invention comprises the following steps:

[0032] Step (1): Add compound A containing a purine skeleton and triethylamine to water at a molar ratio of 1:(0.5-2), and stir at a constant temperature of 60-90°C for 30-120 minutes to prepare a solution A with a concentration of 0.1mM-1.5mM. Dissolve the metal salt in water and stir at 25-40°C to dissolve to prepare a solution B with a concentration of 0.3mM-1.5mM.

[0033] The compound A in step (1) is selected from at least one of xanthine, adenine, guanine, caffeine, theophylline, and theobromine. The molecular structure of the organic compound comprises: (a) two or more metal coordination active sites selected from amino, imino, or carbonyl groups; and (b) at least one aromatic ring structure having a conjugated electron cloud.

[0034] The metal salt in step (1) is selected from at least one of ferric chloride, zinc nitrate, copper chloride, copper nitrate, cobalt nitrate, and nickel nitrate. The metal ion valence in the metal salt is +2 or +3.

[0035] Step (2): Solution A and solution B are transferred to the liquid reservoir A and liquid reservoir B of the double-reservoir gravure printing device respectively, and a ceramic anilox roller with a line count of 100-300 lines / inch and a groove depth of 20-50 μm is used to quantitatively transfer solution A to the surface of the paper substrate at a coating speed of 0.5-2.0 m / min. After the surface tension of the liquid film is balanced for 10-30 seconds, solution B is overcoated using the same process.

[0036] The molar ratio of compound A coated on the surface of the paper substrate in step (2) to the metal salt is 1:(1-3).

[0037] Step (3): The coated paper substrate is continuously conveyed through a low-temperature tunnel at -5-10°C and treated for 10-20 minutes while maintaining a relative humidity of 40-60%. By utilizing the coordination bonding effect between the metal ions and compound A and the π-π stacking effect of the aromatic ring system, a three-dimensional nanofiber network with a diameter of 10-100 nm is in situ self-assembled inside and on the surface of the paper substrate.

[0038] The low-temperature tunnel in step (3) is provided with a gradient cooling zone, and the gradient cooling zone is specifically as follows:

[0039] First temperature zone: 10±2℃, residence time is 3-5 minutes;

[0040] Second temperature zone: 5±1℃, residence time is 6-10 minutes;

[0041] The third temperature zone: 0±1℃, residence time is 3-5 minutes.

[0042] Step (4): The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C and 90°C. The residence time ratio of each temperature zone is 1:2:1, so that the coating amount is 0.01-0.50g / m 2 Phenol-reducing paper composite filter material.

[0043] The phenol-reducing paper composite filter material provided by the present invention can be used for cigarette filter rods.

[0044] The cigarette filter rod comprises an acetate fiber section and a paper section. The filter material in the paper section is a phenol-reducing paper composite filter material, and the paper section is located at the end of the cigarette filter rod near the tobacco shreds.

[0045] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. The materials and reagents used are all commercially available unless otherwise specified. The equipment used in the experiments are all well known to those skilled in the art unless otherwise specified.

[0046] Example 1

[0047] (1) Preparation of functional solution: Add xanthine and triethylamine to water at a molar ratio of 1:1, heat and stir at 60°C for 30 min until completely dissolved, to obtain 0.5 mM solution A. Add copper nitrate to water to form 0.5 mM solution B.

[0048] (2) Gradient coating: Using a dual-reservoir gravure printing device, solution A and solution B were transferred to reservoir A and reservoir B, respectively. A ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to first transfer solution A to the surface of the paper substrate at a coating speed of 2.0 m / min. After the surface tension of the liquid film was balanced for 30 seconds, a ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to overcoat solution B at a coating speed of 2.0 m / min. After gradient coating, the molar ratio of compound A to copper nitrate in the paper filter material was 1:1.

[0049] (3) Dynamic self-assembly: The coated paper substrate was continuously conveyed through a low-temperature tunnel at -5-10°C (first temperature zone: +10±2°C, residence time 5 minutes; second temperature zone: +5±1°C, residence time 10 minutes; third temperature zone: 0±1°C, residence time 5 minutes), and treated for 20 minutes while maintaining a relative humidity of 60%. A three-dimensional nanofiber network with an average diameter of 60 nm was in situ self-assembled inside and on the surface of the paper substrate.

[0050] (4) Gradient drying: The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C, and 90°C. The residence time ratio of each temperature zone is 1:2:1, and the final coating amount is 0.12g / m 2 Phenol-reducing paper composite filter material.

[0051] (5) Preparation of paper composite filter rods: The paper composite filter material was cut into 90 mm filter materials, and after embossing and bundling, a paper filter rod with a length of 120 mm and a pressure drop of 4200 Pa was obtained. A 120 mm long acetate filter rod with a pressure drop of 4200 Pa was prepared using 7.5Y / 16000 tow. The above two filter rods were combined to obtain a composite filter rod S1. The filter rod structure of the composite filter rod was 15 mm acetate segment (near the lip segment) + 15 mm paper segment (near the tobacco end). The pressure drop design value of the composite filter rod S1 was 4600 Pa.

[0052] Example 2

[0053] (1) Preparation of functional solution: Add adenine and triethylamine to water at a molar ratio of 1:1.5, heat and stir at 60°C for 30 min until completely dissolved, to form a 1 mM solution A. Add zinc nitrate to water to form a 0.5 mM solution B.

[0054] (2) Gradient coating: Using a dual-reservoir gravure printing device, the prepared solutions A and B were transferred to reservoirs A and B, respectively. A ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to first transfer solution A to the surface of the paper substrate at a coating speed of 2.0 m / min. After the surface tension of the liquid film was balanced for 30 seconds, a ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to overcoat solution B at a coating speed of 1.5 m / min. After gradient coating, the molar ratio of compound A to zinc nitrate in the paper filter material was 1:1.

[0055] (3) Dynamic self-assembly: The coated paper substrate was continuously conveyed through a low-temperature tunnel at -5-10°C (first temperature zone: +10±2°C, residence time 8 minutes; second temperature zone: +5±1°C, residence time 7 minutes; third temperature zone: 0±1°C, residence time 5 minutes), and treated for 20 minutes while maintaining a relative humidity of 60%. A three-dimensional nanofiber network with an average diameter of 95 nm was in situ self-assembled inside and on the surface of the paper substrate.

[0056] (4) Gradient drying: The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C, and 90°C. The residence time ratio of each temperature zone is 1:2:1, and the final coating amount is 0.25g / m 2 Phenol-reducing paper composite filter material.

[0057] (5) Preparation of paper composite filter rods: The paper composite filter material was cut into 90 mm filter materials, and after embossing and bundling, a paper filter rod with a length of 120 mm and a pressure drop of 4200 Pa was obtained. A 120 mm long acetate filter rod with a pressure drop of 4200 Pa was prepared using a 7.5Y / 16000 tow. The above two filter rods were combined to obtain a composite filter rod S2. The filter rod structure of the composite filter rod was 15 mm acetate segment (near the lip segment) + 15 mm paper segment (near the tobacco end). The pressure drop design value of the composite filter rod S2 was 4600 Pa.

[0058] Example 3

[0059] (1) Preparation of functional solution: Add xanthine, guanine (molar ratio 1:1) and triethylamine to water and heat with stirring at 60°C for 30 min until completely dissolved to form a 1.5 mM solution A. The molar ratio of (xanthine + guanine) to triethylamine is 1:1. Add copper nitrate to water to form a 1.5 mM solution B.

[0060] (2) Gradient coating: Using a dual-reservoir gravure printing device, solution A and solution B were transferred to reservoir A and reservoir B, respectively. A ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to first transfer solution A to the surface of the paper substrate at a coating speed of 2.0 m / min. After the surface tension of the liquid film was balanced for 30 seconds, a ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 20 μm was used to overcoat solution B at a coating speed of 2.0 m / min. After gradient coating, the molar ratio of compound A to copper nitrate in the paper filter material was 1:2.

[0061] (3) Dynamic self-assembly: The coated paper substrate was continuously conveyed through a low-temperature tunnel at -5-10°C (first temperature zone: +10±2°C, residence time 5 minutes; second temperature zone: +5±1°C, residence time 5 minutes; third temperature zone: 0±1°C, residence time 5 minutes), and treated for 15 minutes while maintaining a relative humidity of 60%. A three-dimensional nanofiber network with an average diameter of 100 nm was in situ self-assembled inside and on the surface of the paper substrate.

[0062] (4) Gradient drying: The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C, and 90°C. The residence time ratio of each temperature zone is 1:2:1, and the final coating amount is 0.27g / m 2 Phenol-reducing paper composite filter material.

[0063] (5) Preparation of paper composite filter rods: The paper composite filter material was cut into 90 mm filter materials, and after embossing and bundling, a paper filter rod with a length of 120 mm and a pressure drop of 4200 Pa was obtained. A 120 mm long acetate filter rod with a pressure drop of 4200 Pa was prepared using 7.5Y / 16000 tow. The above two filter rods were combined to obtain a composite filter rod S3. The filter rod structure of the composite filter rod was 15 mm acetate segment (near the lip segment) + 15 mm paper segment (near the tobacco end). The pressure drop design value of the composite filter rod S3 was 4600 Pa.

[0064] Example 4

[0065] (1) Preparation of functional solution: Caffeine and triethylamine were added to water at a molar ratio of 1:1, and heated and stirred at 80°C for 30 min until completely dissolved to form a 1 mM solution A. Cobalt nitrate was added to water to form a 1 mM solution B.

[0066] (2) Gradient coating: Using a dual-reservoir gravure printing device, solution A and solution B were transferred to reservoir A and reservoir B, respectively. A ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to first transfer solution A to the surface of the paper substrate at a coating speed of 2.0 m / min. After the surface tension of the liquid film was balanced for 30 seconds, a ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to overcoat solution B at a coating speed of 2.0 m / min. After gradient coating, the molar ratio of compound A to cobalt nitrate in the paper filter material was 1:1.

[0067] (3) Dynamic self-assembly: The coated paper substrate was continuously conveyed through a low-temperature tunnel at -5-10°C (first temperature zone: +10±2°C, residence time 5 minutes; second temperature zone: +5±1°C, residence time 10 minutes; third temperature zone: 0±1°C, residence time 5 minutes), and treated for 20 minutes while maintaining a relative humidity of 60%. A three-dimensional nanofiber network with an average diameter of 40 nm was in situ self-assembled inside and on the surface of the paper substrate.

[0068] (4) Gradient drying: The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C, and 90°C. The residence time ratio of each temperature zone is 1:2:1, and the final coating amount is 0.09g / m 2 Phenol-reducing paper composite filter material.

[0069] (5) Preparation of paper composite filter rods: The paper composite filter material was cut into 90 mm filter materials, and after embossing and bundling, a paper filter rod with a length of 120 mm and a pressure drop of 4200 Pa was obtained. A 120 mm long acetate filter rod with a pressure drop of 4200 Pa was prepared using 7.5Y / 16000 tow. The above two filter rods were combined to obtain a composite filter rod S4. The filter rod structure of the composite filter rod was 15 mm acetate segment (near the lip segment) + 15 mm paper segment (near the tobacco end). The pressure drop design value of the composite filter rod S4 was 4600 Pa.

[0070] Example 5

[0071] (1) Preparation of functional solution: Add xanthine, theobromine (molar ratio 1:1), and triethylamine to water and heat with stirring at 60°C for 30 min until completely dissolved to form a 1.5 mM solution A. The molar ratio of (xanthine + theobromine) to triethylamine is 1:1. Add nickel nitrate to water to form a 1.0 mM solution B.

[0072] (2) Gradient coating: Using a dual-reservoir gravure printing device, solution A and solution B were transferred to reservoir A and reservoir B, respectively. A ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 50 μm was used to first transfer solution A to the surface of the paper substrate at a coating speed of 2.0 m / min. After the surface tension of the liquid film was balanced for 20 seconds, a ceramic anilox roller with a line count of 300 lines / inch and a groove depth of 30 μm was used to overcoat solution B at a coating speed of 2.0 m / min. After gradient coating, the molar ratio of compound A to nickel nitrate in the paper filter material was 1:3.

[0073] (3) Dynamic self-assembly: The coated paper substrate was continuously conveyed through a low-temperature tunnel at -5-10°C (first temperature zone: +10±2°C, residence time 5 minutes; second temperature zone: +5±1°C, residence time 10 minutes; third temperature zone: 0±1°C, residence time 5 minutes), and treated for 20 minutes while maintaining a relative humidity of 60%. A three-dimensional nanofiber network with an average diameter of 60 nm was in situ self-assembled inside and on the surface of the paper substrate.

[0074] (4) Gradient drying: The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C, and 90°C. The residence time ratio of each temperature zone is 1:2:1, and the final coating amount is 0.2g / m 2 Phenol-reducing paper composite filter material.

[0075] (5) Preparation of paper composite filter rods: The paper composite filter material was cut into 90 mm filter materials, and after embossing and bundling, a paper filter rod with a length of 120 mm and a pressure drop of 4200 Pa was obtained. A 120 mm long acetate filter rod with a pressure drop of 4200 Pa was prepared using 7.5Y / 16000 tow. The above two filter rods were combined to obtain a composite filter rod S5. The filter rod structure of the composite filter rod was 15 mm acetate segment (near the lip segment) + 15 mm paper segment (near the tobacco end). The pressure drop design value of the composite filter rod S5 was 4600 Pa.

[0076] Comparative Example 1

[0077] Uncoated paper filter rod base paper was embossed and bundled to produce a 120 mm long paper filter rod with a pressure drop of 4200 Pa. A 120 mm long acetate filter rod with a pressure drop of 4600 Pa was prepared using 7.5Y / 16000 tow. The two filter rods were combined to create a composite filter rod S0. The composite filter rod structure consisted of a 15 mm acetate segment (near the lip) and a 15 mm paper segment (near the tobacco end). The design pressure drop of composite filter rod S0 was 4600 Pa.

[0078] The prepared composite filter rods S0-S6 were used to replace the acetate filter rod of a finished cigarette to roll sample cigarettes. The obtained sample cigarettes were marked as T0-T6.

[0079] The release of hydrocyanic acid in the mainstream smoke of the sample cigarettes was determined according to the method specified in "YC / T 253-2008 Determination of Hydrogen Cyanide in Mainstream Cigarette Smoke - Continuous Flow Method", and the release of crotonaldehyde in the sample cigarettes was determined according to the method specified in "YC / T 254-2008 Determination of Major Carbonyl Compounds in Mainstream Cigarette Smoke - High Performance Liquid Chromatography Method". Nine professional sensory quality judges were randomly selected to evaluate and score the sensory quality of the sample cigarettes according to the method specified in "Cigarettes - Part 4: Sensory Technical Requirements".

[0080] The results are shown in Table 1.

[0081] Table 1 Phenol release in mainstream cigarette smoke and sensory quality evaluation results

[0082]

[0083] As can be seen from Table 1, the paper composite filter material prepared by the present invention can effectively reduce the release of phenol in mainstream cigarette smoke and improve the smoking quality of cigarettes.

[0084] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for preparing a phenol-reducing paper composite filter material, characterized in that: The following steps are involved: Step (1): Add compound A containing a purine skeleton and triethylamine to water at a molar ratio of 1:(0.5-2), and stir at a constant temperature of 60-90°C for 30-120 minutes to prepare a solution A with a concentration of 0.1mM-1.5mM; dissolve the metal salt in water, and stir and dissolve at 25-40°C to prepare a solution B with a concentration of 0.3mM-1.5mM; Step (2): respectively transferring solution A and solution B to the liquid reservoir A and liquid reservoir B of a dual-reservoir gravure printing device, using a ceramic anilox roller with a line count of 100-300 lines per inch and a groove depth of 20-50 μm, first quantitatively transferring solution A to the surface of the paper substrate at a coating speed of 0.5-2.0 m / min, and after the surface tension of the liquid film is balanced for 10-30 seconds, coating solution B in the same manner; Step (3): The coated paper substrate is continuously conveyed through a low-temperature tunnel at -5-10°C and maintained at a relative humidity of 40-60% for 10-20 minutes to in situ self-assemble into a three-dimensional nanofiber network with a diameter of 10-100 nm inside and on the surface of the paper substrate; Step (4): The self-assembled paper substrate is introduced into a multi-stage drying system and sequentially dried in three temperature zones of 70°C, 80°C and 90°C. The residence time ratio of each temperature zone is 1:2:1, so that the coating amount is 0.01-0.50g / m 2 Phenol-reducing paper composite filter material.

2. The preparation method according to claim 1, characterized in that The compound A in step (1) is selected from at least one of xanthine, adenine, guanine, caffeine, theophylline and theobromine.

3. The preparation method according to claim 1, characterized in that The metal salt in step (1) is selected from at least one of ferric chloride, zinc nitrate, copper chloride, copper nitrate, cobalt nitrate and nickel nitrate.

4. The preparation method according to claim 1, characterized in that In the step (2), the molar ratio of the compound A coated on the surface of the paper substrate to the metal salt is 1:(1-3).

5. The preparation method according to claim 1, characterized in that In step (3), a gradient cooling zone is provided in the low-temperature tunnel, and the gradient cooling zone is specifically as follows: First temperature zone: 10±2℃, residence time is 3-5 minutes; Second temperature zone: 5±1℃, residence time is 6-10 minutes; The third temperature zone: 0±1℃, residence time is 3-5 minutes.

6. A phenol-reducing paper composite filter material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 5.

7. An application of the phenol reduction paper composite filter material according to claim 6, characterized in that: Used for cigarette filter rods.

8. The use according to claim 7, characterized in that The cigarette filter rod comprises an acetate fiber segment and a paper segment. The filter material in the paper segment is a phenol-reducing paper composite filter material, and the paper segment is located at the end of the cigarette filter rod near the tobacco shreds.

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