Aluminum-free moisture-regulating lining paper for cigarette and preparation method therefor

Abstract

Aluminum-free moisture-regulating lining paper for cigarettes and a preparation method therefor. The aluminum-free moisture-regulating lining paper for cigarettes comprises a base paper layer (1), a d

Description

Aluminum-free humidity-regulating lining paper for cigarettes and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 4, 2023, with application number CN202311132224.3 and invention name “A new type of aluminum-free humidity-regulating lining paper for cigarettes and its preparation method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of paper-based materials, and specifically relates to a cigarette lining paper with a humidity regulating function for cigarette packaging and a preparation method thereof. Background Art

[0003] Tobacco and its products are hygroscopic, and their moisture content has a certain impact on the storage, transportation, processing, and inherent quality of tobacco products. Currently, cigarettes are the primary tobacco product produced in my country. Due to regional and seasonal variations in humidity, the moisture content of cigarettes varies significantly. The moisture content of cigarettes directly affects the smoking quality. Excessive moisture content in cigarettes can lead to incomplete combustion of the tobacco, resulting in a loss of aroma. High moisture content can also cause the tobacco to mold, significantly reducing the smoking quality. Conversely, low moisture content in cigarettes can cause the tobacco to burn too quickly and the smoke temperature to be too high, resulting in a strong, dry, acrid, and throat-irritating smoke. Therefore, an appropriate moisture content plays a crucial role in the smoking quality of cigarettes.

[0004] For cigarettes, moisture content is closely related to their moisturizing properties, which are influenced by factors such as tobacco characteristics, humectants, and packaging materials. In recent years, the cigarette industry has utilized smoke moisturization or hydration to improve smoking comfort. One approach involves adding polyol humectants to tobacco. While this method can maintain the moisture content of tobacco during processing and improve its processing resistance, the additives are added directly to the tobacco and participate in combustion during smoking, introducing other impurities into the smoke, affecting the sensory quality of the cigarette. Another approach involves embedding explosive beads within filter rods. These beads are then pressed and ruptured during use, increasing smoke humidity and improving the filter rod's ability to capture aroma. However, this approach significantly increases production costs. Given the challenges associated with these methods of imparting moisturizing properties to cigarette packaging, researchers are considering using environmentally friendly treatment processes to impart moisture-retaining and humidity-regulating properties to cigarette packaging materials, addressing the issue of maintaining constant humidity even after unpacking.

[0005] Cigarette lining paper, serving as the paper-based material between the cigarette pack and the cigarettes, comes into direct contact with the cigarettes and is an important cigarette packaging material. Generally speaking, cigarette lining paper primarily serves to preserve aroma, block air and moisture, and shield light. However, traditional cigarette lining paper lacks dynamic humidity control. In recent years, a number of cigarette lining papers with different preparation processes have emerged, along with several authorized patents, such as those with authorization announcement numbers CN110696514B, CN114775331B, CN114086429B, CN111676729B, and CN106868933B. However, the cigarette lining papers covered by these preparation processes and patents either lack dynamic humidity control or utilize metal layers, such as aluminum or titanium, to achieve this barrier function. The prior art lacks environmentally friendly cigarette lining paper with excellent barrier properties and dynamic humidity control.

[0006] Summary of the Invention

[0007] In view of the defects and shortcomings of the existing technology, the present application provides an aluminum-free humidity-regulating lining paper for cigarettes. The product uses biomass-based degradable polymers and the good film-forming properties of polyvinyl alcohol to form a dense barrier layer on the surface of the base paper; at the same time, it uses calcium stearate (containing stearic acid long carbon chain hydrophobic groups, Ca 2+ The synergistic effect between the small molecule free ions), silane coupling agent (hydrophobic group, organic-inorganic bridging agent), nanocellulose (high aspect ratio, high specific surface area, rich in active groups) and carboxymethyl cellulose (film-forming, rich in carboxyl groups) forms a hydrophobic functional layer outside the dense barrier layer, thereby giving the lining paper excellent barrier properties and good formability. On the other hand, natural polymers and inorganic particles are used to utilize the organic-inorganic physical cross-linking effect and water absorption-drainage-slow-release effect between sodium alginate (film-forming and water-retention properties), nanoporous calcium silicate (water absorption-drainage function and sustained-release properties) and hyaluronic acid (hygroscopicity, excellent water retention) to form a dynamic composite humidity-regulating functional layer, giving the lining paper good dynamic humidity-regulating function. In addition, another object of the present application is to provide a preparation method for the aluminum-free humidity-regulating lining paper for cigarettes.

[0008] To achieve the above objectives, this application adopts the following technical solutions:

[0009] The present application provides an aluminum-free humidity-control lining paper for cigarettes, comprising a base paper layer, a dense barrier layer, a hydrophobic functional layer, and a dynamic composite humidity-control functional layer. The dense barrier layer and the hydrophobic functional layer are sequentially arranged on the outer surface of the base paper layer from the inside out, while the dynamic composite humidity-control functional layer is arranged on the inner surface of the base paper layer. The dense barrier layer comprises polyvinyl alcohol and glycerol, the hydrophobic functional layer comprises calcium stearate, a silane coupling agent, nanocellulose, and carboxymethyl cellulose, and the dynamic composite humidity-control functional layer comprises sodium alginate, nanoporous calcium silicate, glycerol, and hyaluronic acid.

[0010] This application addresses the technical issues of poor barrier properties and high degree of forming in existing aluminum-free liner paper. It creatively proposes the use of a dense barrier layer and a hydrophobic functional layer to form a dual-effect barrier. The excellent film-forming properties of polyvinyl alcohol and the dense structure formed after film formation are utilized to effectively finish, physically cover, and fill the porous structure on the surface of the base paper layer. However, because polyvinyl alcohol is rich in hydroxyl groups, under high humidity conditions, the hydroxyl groups in polyvinyl alcohol will combine with the hydroxyl groups of water molecules in humid air to form hydrogen bonds, thereby negatively affecting the dense structure of the polyvinyl alcohol coating, causing the polyvinyl alcohol coating to gradually swell and dissolve, greatly reducing its barrier properties. Therefore, a single polyvinyl alcohol coating cannot meet the barrier requirements under high humidity conditions. In this application, a hydrophobic functional layer is coated on the outside of the dense polyvinyl alcohol barrier layer, which can effectively prevent water molecules in the air from damaging the polyvinyl alcohol coating. The hydrophobic functional layer is composed of calcium stearate, silane coupling agent, nanocellulose and carboxymethyl cellulose. The C18 hydrophobic long carbon chain in calcium stearate and the hydrophobic long carbon chain in the silane coupling agent are used to give the coating system a high level of hydrophobicity. In addition, the abundant hydroxyl groups on nanocellulose are very easy to combine with the carboxylic acid groups in calcium stearate and carboxymethyl cellulose. Nanocellulose is easy to combine with silane coupling agent due to its high aspect ratio, high specific surface area and nano-size effect. In the hydrophobic functional layer, carboxymethyl cellulose uses its good film-forming properties to form the matrix of the hydrophobic functional layer; the hydrophobic long carbon chain in calcium stearate and silane coupling agent hydrophobically modifies the coating system; the Ca in nanocellulose and calcium stearate 2+ Acts as a physical crosslinker in the coating system, Ca 2+ Due to its small ionic size, it can be freely and flexibly dispersed in the molecular structure of carboxymethyl cellulose and nanocellulose. In summary, due to the synergistic effect of calcium stearate, silane coupling agent, nanocellulose and carboxymethyl cellulose in terms of hydrophobicity, film-forming properties and dispersion uniformity, the hydrophobic functional layer has good hydrophobicity and certain barrier capacity.

[0011] In this application, the natural moisturizing factor - hyaluronic acid is applied to the dynamic humidity control performance of paper-based materials for the first time. Hyaluronic acid, which is rich in carboxylic acid, acetylamino and hydroxyl groups, has a special water-retaining effect. It is the best moisturizing substance found in nature so far and can carry more than 500 times its own weight in water. Although hyaluronic acid has a good water-locking and water-retaining effect, after hyaluronic acid absorbs water, it is difficult for water molecules to be removed from the hyaluronic acid molecular structure even in a dry environment. Therefore, this application creatively combines the organic moisturizing factor - hyaluronic acid with inorganic particles - nanoporous calcium silicate to achieve the dynamic humidity control function of locking water and moisturizing - draining and releasing moisture. Nanoporous calcium silicate can freely enter the long-chain multi-level structure of hyaluronic acid due to the nano-size effect, and utilizes Si-O - Negative ions and H in water molecules + The electrostatic binding effect draws water adsorbed from the long-chain multi-level structure of the hyaluronic acid polymer into the nanoscale multi-level pore structure of the nano-calcium silicate particles. As the mass of the introduced water increases, the water molecules in the nano-calcium silicate are primarily present through physical adsorption. Because the energy barrier for adsorption-desorption in physical adsorption is low, water molecules undergo an adsorption-desorption process within the nano-scale pore structure of the nano-calcium silicate, influenced by the partial pressure of water vapor in the surrounding environment. This allows the particles to dynamically respond to changes in ambient humidity, achieving dynamic humidity control.

[0012] Due to the large difference in temperature and humidity between the north and south of my country, the aluminum-free humidity-regulating lining paper for cigarettes provided in this application gives the local microenvironment of the packaging in the cigarette box a certain dynamic humidity-regulating function. It can independently regulate the humidity of the microenvironment in the cigarette packaging box through the functions of locking water, absorbing moisture and draining moisture according to the humidity changes in the storage environment, thereby achieving the purpose of constant humidity preservation of cigarettes after the packaging is unpacked.

[0013] The preparation method of the aluminum-free humidity-control lining paper for cigarettes comprises the following steps:

[0014] S1: Preparation of dense barrier coating: First, prepare a polyvinyl alcohol solution of a certain mass concentration, then mix polyvinyl alcohol and glycerin in a mass percentage of (70-95)%: (5-30)%, add water to adjust the viscosity of the coating solution to 100-500cp, and set aside;

[0015] S2: Preparation of hydrophobic functional layer coating: First, a carboxymethyl cellulose aqueous solution of a certain mass concentration is prepared, and commercially available calcium stearate emulsion and nanocellulose hydrogel are selected. The hydrophobic functional layer coating is prepared according to the mass fraction of calcium stearate in the coating liquid being 2-15%, the mass fraction of silane coupling agent being 0.5-2%, the mass fraction of nanocellulose being 5-25%, and the mass fraction of carboxymethyl cellulose being 60-90%. Water is then added to adjust the viscosity of the coating liquid to 200-800cp and set aside.

[0016] S3: Preparation of dynamic composite humidity control functional layer coating: First, prepare a sodium alginate aqueous solution of a certain mass concentration, add a certain amount of hyaluronic acid and mix well, then add nanoporous calcium silicate and glycerol in sequence, and prepare a dynamic composite humidity control functional layer coating according to the mass fraction of each component in the coating liquid: sodium alginate 50-80%, nanoporous calcium silicate 10-30%, glycerol 5-20%, hyaluronic acid 0.5-2%, and add water to adjust the viscosity of the coating liquid to 300-900cp, and set aside;

[0017] S4: Using any coating process such as blade coating, curtain coating or rod coating, the prepared dense barrier layer coating is transferred to one side of the cigarette liner base paper (base paper layer), and non-contact hot air drying is performed at a drying temperature of 80-120° C. for 5-20 minutes to obtain coated paper with a dense barrier layer coated on one side;

[0018] S5: Using any coating process such as blade coating, curtain coating, or bar coating, the prepared hydrophobic functional layer coating is transferred to the side of the coated paper obtained in step S4 that is coated with a dense barrier layer on one side, and subjected to non-contact hot air drying at a drying temperature of 100-120° C. for a drying time of 5-20 minutes to obtain a coated paper that is sequentially coated with a dense barrier layer and a hydrophobic functional layer on one side;

[0019] S6: Select any coating process such as doctor blade, curtain coating or doctor rod coating, transfer the prepared dynamic composite humidity-controlling functional layer coating to the coated paper obtained in step S5, which is coated with a dense barrier layer and a hydrophobic functional layer on one side in sequence, and coat the dynamic composite humidity-controlling functional layer coating on the uncoated surface of the coated paper (that is, the dense barrier layer and the hydrophobic functional layer are coated on the outer surface of the cigarette lining paper, and the dynamic composite humidity-controlling functional layer is coated on the inner surface of the cigarette lining paper), and perform non-contact hot air drying at a drying temperature of 100-120°C and a drying time of 10-30 minutes to obtain the aluminum-free humidity-controlling lining paper for cigarettes.

[0020] Preferably, in the dense barrier layer of the aluminum-free humidity-regulating lining paper for cigarettes, the mass percentages of the polyvinyl alcohol and glycerol are (70-95)%: (5-30)%, and the coating amount of the coating liquid formed by polyvinyl alcohol, glycerol and water is 0.5-1 g / m 2 .

[0021] Preferably, the molecular weight of the polyvinyl alcohol is 120,000 to 250,000, and the alcoholysis degree is 78 to 88%.

[0022] Preferably, the mass fraction of calcium stearate in the hydrophobic functional layer coating is 2-15%, the mass fraction of silane coupling agent is 0.5-2%, the mass fraction of nanocellulose is 5-25%, and the mass fraction of carboxymethyl cellulose is 60-80%. The coating amount of the coating liquid of the hydrophobic functional layer coating is 1-3 g / m 2 .

[0023] Preferably, the silane coupling agent is selected from KH550, KH560, KH580, A-151 or A-171, the diameter of the nanocellulose is 10 to 100 nm, the length is 1 to 30 μm, and the molecular weight of the carboxymethyl cellulose is 150,000 to 300,000.

[0024] Preferably, the coating amount of the dynamic composite humidity control functional layer coating is 2 to 5 g / m 2 .

[0025] Preferably, the molecular weight dispersity index (Mw / Mn) of the sodium alginate is 1.9-2.3, the M / G monosaccharide ratio is 0.5-1, the particle size of the nanoporous calcium silicate is 5-100 nm, and the molecular weight of the hyaluronic acid is 500,000-3,000,000.

[0026] The aluminum-free humidity-regulating lining paper for cigarettes provided by the present application and its preparation method utilize the good film-forming and barrier properties of polyvinyl alcohol and the plasticizing properties of glycerol to first form a dense and well-ductile barrier layer on the surface of the cigarette lining base paper. In order to solve the problem of reduced barrier properties of polyvinyl alcohol coating under high humidity conditions, the hydrophobic synergistic effect of hydrophobic substances - calcium stearate and silane coupling agent is utilized, and with the help of nanocellulose physical cross-linking agent, a hydrophobic functional layer with hydrophobicity and certain barrier ability is formed in the carboxymethyl cellulose matrix. Under the action of the double-layer functional coating layer of dense barrier layer and hydrophobic functional layer, the aluminum-free lining paper for cigarettes is given good barrier properties (low air permeability and low water vapor permeability) under high humidity conditions. In addition, in response to the technical problems and practical needs of dynamic humidity control of cigarette lining paper, the present application utilizes the good water-locking and moisturizing effect of natural moisturizing factor - hyaluronic acid and the moisture absorption-drainage-slow-release effect of nanoporous calcium silicate to achieve dynamic response to changes in environmental humidity. At the same time, the Ca in nanoporous calcium silicate 2+It can promote the cross-linking of sodium alginate to form a complex gel structure, thereby forming a stable three-dimensional network structure through extension and dehydration in the aqueous phase, which is beneficial to the structural uniformity and stability of the sodium alginate-based dynamic composite humidity-control functional layer. Since the selected biomass polymer material has good ductility, the prepared coating has a low degree of forming, which can well meet the subsequent processing requirements of the aluminum-free lining paper for cigarettes. Therefore, the aluminum-free humidity-control lining paper for cigarettes provided by the present application has obvious beneficial effects: first, it has good softness, a dense surface structure, and a low degree of forming, thereby overcoming the defects of the existing aluminum-free lining paper for cigarettes in the above aspects; secondly, by absorbing water to retain moisture and draining water to release moisture, it realizes a dynamic response to changes in the humidity of the local microenvironment, thereby controlling the humidity changes of the local microenvironment within an acceptable range; finally, the production process of the aluminum-free humidity-control lining paper for cigarettes provided by the present application is green and environmentally friendly, and the materials used are biomass degradable materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 shows a schematic structural diagram of the aluminum-free humidity-control liner paper for cigarettes described in the present application;

[0028] In the figure, 1-base paper layer, 2-dense barrier layer, 3-hydrophobic functional layer, 4-dynamic composite humidity control functional layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and beneficial effects of this application clearer, the preferred embodiments of this application will be described in detail below with reference to the accompanying drawings to facilitate understanding by technical personnel.

[0030] As shown in Figure 1, the aluminum-free humidity-regulating lining paper for cigarettes described in this application includes a base paper layer 1, the upper surface of the base paper layer is composed of a dense barrier layer 2 and a hydrophobic functional layer 3 from the inside to the outside, and the lower surface of the base paper layer is provided with a dynamic composite humidity-regulating functional layer 4.

[0031] Specifically, in the present application, the base paper layer 1 can adopt commercially available cigarette lining base paper, the dense barrier layer 2 includes polyvinyl alcohol and glycerol, the hydrophobic functional layer 3 includes calcium stearate, silane coupling agent, nanocellulose and carboxymethyl cellulose, and the dynamic composite humidity regulating functional layer 4 includes sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid.

[0032] In the present application, in the dense barrier layer 2 of the aluminum-free humidity-regulating lining paper for cigarettes, the mass percentage of the polyvinyl alcohol and glycerol is preferably (70-95)%: (5-30)%, the viscosity of the coating liquid formed by polyvinyl alcohol, glycerol and water is preferably 100-500cp, and the coating amount is preferably 0.5-1g / m 2 .

[0033] In the present application, in the dense barrier layer 2 of the aluminum-free humidity-control liner paper for cigarettes, the molecular weight of the polyvinyl alcohol is preferably 120,000 to 250,000, and the alcoholysis degree is preferably 78 to 88%.

[0034] In the present application, in the hydrophobic functional layer 3 of the aluminum-free humidity-conditioning lining paper for cigarettes, the mass fraction of calcium stearate in the liquid for preparing the hydrophobic functional layer is preferably 2-15%, the mass fraction of the silane coupling agent is preferably 0.5-2%, the mass fraction of nanocellulose is preferably 5-25%, and the mass fraction of carboxymethyl cellulose is preferably 60-80%. The viscosity of the coating liquid is preferably 200-800cp, and the coating amount is preferably 1-3g / m 2 .

[0035] In the present application, in the hydrophobic functional layer 3 of the aluminum-free humidity-regulating lining paper for cigarettes, calcium stearate in the coating for preparing the hydrophobic functional layer is preferably selected from commercially available calcium stearate emulsion, the silane coupling agent is preferably selected from KH550, KH560, KH580, A-151 or A-171, the diameter of the nanocellulose is preferably 10 to 100 nm, the length is preferably 1 to 30 μm, and the molecular weight of the carboxymethyl cellulose is preferably 150,000 to 300,000.

[0036] In the present application, in the dynamic composite humidity-controlling functional layer 4 of the aluminum-free humidity-controlling inner lining paper for cigarettes, the material liquid for preparing the dynamic composite humidity-controlling functional layer preferably includes the following raw materials in mass percentage: sodium alginate 50-80%, nanoporous calcium silicate 10-30%, glycerol 5-20%, hyaluronic acid 0.5-2%, the coating material liquid viscosity is preferably 300-900cp, and the coating amount is preferably 2-5g / m 2 .

[0037] In the present application, in the dynamic composite humidity-regulating functional layer 4 of the aluminum-free humidity-regulating lining paper for cigarettes, the molecular weight dispersion index (Mw / Mn) of the sodium alginate is preferably 1.9 to 2.3, the M / G monosaccharide ratio is 0.5 to 1, the particle size of the nanoporous calcium silicate is 5 to 100 nm, and the molecular weight of the hyaluronic acid is 500,000 to 3 million.

[0038] In order to further illustrate the present application, the aluminum-free humidity-regulating lining paper for cigarettes and its preparation method provided by the present application are described in detail below with reference to examples, but they should not be understood as limiting the scope of protection of the present application.

[0039] Example 1

[0040] S1: Preparation of dense barrier coating: Commercially available polyvinyl alcohol with a molecular weight of 120,000 and a degree of alcoholysis of 78% was used to prepare a polyvinyl alcohol aqueous solution with a mass concentration of 2%. The mass percentage of polyvinyl alcohol to glycerol was 70%:30%, and a polyvinyl alcohol / glycerol / water mixed coating solution with a coating viscosity of 100 cp was prepared for later use;

[0041] S2: Preparation of hydrophobic functional layer coating: commercially available carboxymethyl cellulose with a molecular weight of 200,000 was used to prepare a carboxymethyl cellulose aqueous solution with a mass concentration of 1%, commercially available calcium stearate emulsion and nanocellulose hydrogel (diameter of 20 nm, length of 4 μm) were selected, and KH550 was selected as a silane coupling agent. The hydrophobic functional layer coating was prepared according to the mass fraction of calcium stearate of 2%, the mass fraction of silane coupling agent of 1.5%, the mass fraction of nanocellulose of 10% and the mass fraction of carboxymethyl cellulose of 86.5% in the coating liquid. Then, an appropriate amount of water was added to adjust the viscosity of the coating liquid to 300 cp for standby use;

[0042] S3: Preparation of dynamic composite humidity control functional layer coating: A sodium alginate aqueous solution with a mass concentration of 2% was prepared by selecting commercially available sodium alginate with a molecular weight dispersion index (Mw / Mn) of 1.9 and an M / G monosaccharide ratio of 0.5, and commercially available hyaluronic acid with a molecular weight of 1 million was added. Then, commercially available nanoporous calcium silicate with a particle size of 5 nm and glycerol were added in sequence. The dynamic composite humidity control functional layer coating was prepared according to the mass fractions of the components in the coating solution: 69.5% sodium alginate, 20% nanoporous calcium silicate, 10% glycerol, and 0.5% hyaluronic acid. Finally, water was added to adjust the viscosity of the coating solution to 300 cp for standby use;

[0043] S4: Use a doctor bar to transfer the prepared dense barrier coating to one side of the cigarette lining paper, with a coating amount of 0.5g / m 2 , non-contact hot air drying was performed at a drying temperature of 80°C and a drying time of 20 minutes to obtain coated paper with a dense barrier layer coated on one side;

[0044] S5: Use a doctor bar to transfer the prepared hydrophobic functional layer coating to the side of the paper coated with a dense barrier layer on one side obtained in step S4, with a coating amount of 1 g / m 2 , performing non-contact hot air drying at a drying temperature of 100° C. and a drying time of 20 min to obtain a coated paper having a dense barrier layer and a hydrophobic functional layer sequentially coated on one side;

[0045] S6: Use a doctor bar to transfer the prepared dynamic composite humidity control functional layer coating to the coated paper obtained in step S5, which is coated with a dense barrier layer and a hydrophobic functional layer on one side. The dynamic composite humidity control functional layer coating is coated on the uncoated side of the cigarette liner paper with a coating amount of 2g / m 2, non-contact hot air drying was carried out at a drying temperature of 120°C and a drying time of 10 min to obtain aluminum-free humidity-regulating lining paper for cigarettes.

[0046] Example 2

[0047] The same as Example 1, except that A-151 is selected as the silane coupling agent in step S2, a hydrophobic functional layer coating is prepared according to the mass fraction of calcium stearate of 15%, the mass fraction of silane coupling agent of 0.5%, the mass fraction of nanocellulose of 5% and the mass fraction of carboxymethyl cellulose of 79.5% in the coating liquid, and then an appropriate amount of water is added to adjust the viscosity of the coating liquid to 200cp for standby use; a doctor blade coating is selected in step S4; and the coating amount in step S5 is 1.5g / m 2 , the drying temperature is 110°C; the coating amount in step S6 is 3g / m 2 , drying time is 15min.

[0048] Example 3

[0049] The same as Example 1, except that in step S1, a polyvinyl alcohol / glycerol / water mixed coating solution with a coating liquid viscosity of 500cp is prepared according to the mass percentage of polyvinyl alcohol and glycerol of 95%:5%; in step S2, KH560 is selected as the silane coupling agent, and the mass fraction of calcium stearate in the coating liquid is 5%, the mass fraction of the silane coupling agent is 2%, the mass fraction of nanocellulose is 10%, and the mass fraction of carboxymethyl cellulose is 83% to prepare a hydrophobic functional layer coating; in step S3, commercially available sodium alginate with a molecular weight dispersity index (Mw / Mn) of 2.3 and an M / G monosaccharide ratio of 1 is selected, and the mass fractions of each component in the coating liquid are: 53% sodium alginate, 30% nanoporous calcium silicate, 15% glycerol, and 2% hyaluronic acid to prepare a dynamic composite humidity control functional layer coating, and finally water is added to adjust the coating liquid viscosity to 500cp for standby use; in step S4, the coating amount is 1g / m 2 ; The coating amount in step S6 is 3.5g / m 2 , drying time is 15min.

[0050] Example 4

[0051] The same as Example 1, except that in step S2, a hydrophobic functional layer coating is prepared according to the coating liquid having a mass fraction of 3% calcium stearate, a mass fraction of 1% silane coupling agent, a mass fraction of 15% nanocellulose, and a mass fraction of 81% carboxymethyl cellulose.

[0052] Example 5

[0053] The same as Example 1, except that the mass fractions of the components in the coating liquid in step S3 are: 63.5% sodium alginate, 15% nanoporous calcium silicate, 20% glycerol, and 1.5% hyaluronic acid to prepare a dynamic composite humidity control functional layer coating, and finally water is added to adjust the viscosity of the coating liquid to 900cp for standby use; in step S6, a doctor blade coating is selected, and the coating amount is 5g / m 2 , drying time is 30min.

[0054] Example 6

[0055] The same as Example 1, except that in step S1, a polyvinyl alcohol / glycerol / water mixed coating solution with a coating liquid viscosity of 300cp is prepared according to the mass percentage of polyvinyl alcohol and glycerol of 80%:20%; in step S2, A-171 is selected as the silane coupling agent, and the mass fraction of calcium stearate in the coating liquid is 10%, the mass fraction of the silane coupling agent is 1.8%, the mass fraction of nanocellulose is 15%, and the mass fraction of carboxymethyl cellulose is 86.7% to prepare a hydrophobic functional layer coating; in step S3, commercially available sodium alginate with a molecular weight dispersity index (Mw / Mn) of 2.2 and an M / G monosaccharide ratio of 0.8 is selected, and the mass fractions of each component in the coating liquid are: sodium alginate 70.3%, nanoporous calcium silicate 19%, glycerol 10%, and hyaluronic acid 0.7% to prepare a dynamic composite humidity control functional layer coating, and finally water is added to adjust the coating liquid viscosity to 700cp for standby use; in step S4, the coating amount is 1.5g / m 2 .

[0056] Example 7

[0057] The same as Example 1, except that in step S2, a hydrophobic functional layer coating is prepared according to the coating liquid having a mass fraction of calcium stearate of 12%, a mass fraction of silane coupling agent of 0.6%, a mass fraction of nanocellulose of 19% and a mass fraction of carboxymethyl cellulose of 68.4%.

[0058] Example 8

[0059] Same as Example 1, except that KH580 is used as the silane coupling agent in step S2; curtain coating is used in step S4, and the coating amount is 0.8 g / m 2 In step S5, curtain coating is used and the coating amount is 2.5g / m 2 , the drying temperature is 120°C; the coating amount in step S6 is 4g / m 2 , drying time is 22 minutes.

[0060] Table 1 shows a comparison of barrier properties, such as air permeability and water vapor transmission rate, between the aluminum-free humidity-control liner paper prepared in Examples 1-8 and commercially available composite aluminum foil liner paper samples. Furthermore, to verify that the aluminum-free humidity-control liner paper used in this application can dynamically control the humidity of cut tobacco in an open environment, thereby maintaining the moisture content of the cigarettes within a narrow range, eight samples of aluminum-free humidity-control liner paper and composite aluminum foil liner paper were placed in cigarette boxes (containing 20 cigarettes) according to cigarette production patterns. The packs were then placed in a constant temperature and humidity chamber to test the humidity-control performance of the aluminum-free humidity-control liner paper. The moisture content (%) of the cigarettes was compared 48 hours after unpacking in a high-temperature, high-humidity environment (38°C, 80% RH), a dry environment (38°C, 30% RH), and a normal humidity environment (38°C, 50% RH).

[0061] Table 1. Barrier performance indicators of aluminum-free humidity-conditioning liner paper for cigarettes

[0062] As can be seen in Table 1, in terms of barrier performance, the air permeability and water vapor transmission rate test data for Examples 1-8 are comparable to those of the control sample (commercially available composite aluminum foil liner paper). Examples 2, 3, 5, and 8 exhibit relatively good barrier performance due to the larger coating amounts of the hydrophobic functional layer and the dynamic composite humidity-control functional layer. The air permeability and water vapor transmission rate test data indicate that the barrier performance of the aluminum-free humidity-control liner paper for cigarettes prepared in Examples 1-8 is comparable to that of commercially available composite aluminum foil liner paper, demonstrating that the aluminum-free humidity-control liner paper for cigarettes prepared in accordance with this application can meet the barrier performance requirements for cigarette liner paper in practical applications.

[0063] In addition, from the changes in the moisture content of cigarettes under different temperature and humidity conditions in Table 1, it can be seen that although the composite aluminum foil lining paper has good barrier properties, it does not have dynamic humidity control properties, resulting in large fluctuations in the moisture content of the cigarettes wrapped therein after unpacking under different temperature and humidity conditions (the moisture content of the cigarettes increased by 25.8% under high temperature and high humidity conditions; the moisture content of the cigarettes decreased by 20.0% under dry conditions). By comparison, it was found that after the aluminum-free humidity-controlling lining paper for cigarettes in Examples 1 to 8 of this application was placed in the cigarette packaging according to the cigarette production model, the fluctuation range of the moisture content of the cigarettes after unpacking under different temperature and humidity conditions was very small. This shows that the aluminum-free humidity-controlling lining paper for cigarettes prepared in Examples 1 to 8 has good dynamic humidity control properties. In a high temperature and high humidity environment, it can reduce the humidity of the local microenvironment where the cigarettes are located by absorbing water, thereby maintaining the moisture content of the cigarettes at a normal level; in a dry environment, it can increase the humidity of the local microenvironment where the cigarettes are located by draining water, thereby maintaining the moisture content of the cigarettes at a normal level. In summary, the storage environment has little effect on the moisture content of cigarettes wrapped with aluminum-free humidity-control liner paper for cigarettes, indicating that the aluminum-free humidity-control liner paper for cigarettes provided in this application has good environmental humidity response capability and sensitive dynamic humidity control performance.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present application and are not limiting. Although the present application has been described in detail through the above embodiments, those skilled in the art should understand that various changes can be made to the content of the present application in details and form without departing from the scope defined by the claims of the present application; in addition, the dimensions of the drawings are not related to the specific objects, and the dimensions of the objects can be changed arbitrarily.

Claims

1. A non-aluminum humidity-controlling lining paper for cigarettes, characterized in that: The aluminum-free humidity-control lining paper for cigarettes comprises a base paper layer, a dense barrier layer and a hydrophobic functional layer arranged in sequence from the inside to the outside on the outer surface of the base paper layer, and a dynamic composite humidity-control functional layer arranged on the inner surface of the base paper layer; the components of the dense barrier layer include polyvinyl alcohol and glycerol, the components of the hydrophobic functional layer include calcium stearate, a silane coupling agent, nanocellulose and carboxymethyl cellulose, and the components of the dynamic composite humidity-control functional layer include sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid.

2. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: The preparation method of the aluminum-free humidity-controlling lining paper for cigarettes comprises the following steps: S1: preparing a dense barrier layer coating: preparing a polyvinyl alcohol solution of a certain mass concentration, then mixing polyvinyl alcohol and glycerol in a mass percentage of (70-95)%:(5-30)%, adding water to adjust the viscosity of the coating liquid to 100-500cp, and setting aside; S2: preparing a hydrophobic functional layer coating: preparing a carboxymethyl cellulose aqueous solution of a certain mass concentration, selecting commercially available calcium stearate emulsion and nanocellulose hydrogel, and preparing a hydrophobic functional layer coating according to the mass fraction of calcium stearate of 2-15%, the mass fraction of silane coupling agent of 0.5-2%, the mass fraction of nanocellulose of 5-25% and the mass fraction of carboxymethyl cellulose of 60-90% in the coating liquid, and then adding water to adjust the viscosity of the coating liquid to 200-800cp for standby use; S3: preparing a dynamic composite humidity-controlling functional layer coating: preparing a sodium alginate aqueous solution of a certain mass concentration, adding a certain amount of hyaluronic acid and mixing, then sequentially adding nanoporous calcium silicate and glycerol, preparing a dynamic composite humidity-controlling functional layer coating according to the mass fractions of the components in the coating liquid: 50-80% sodium alginate, 10-30% nanoporous calcium silicate, 5-20% glycerol, 0.5-2% hyaluronic acid, adding water to adjust the coating liquid viscosity to 300-900cp, and set aside; S4: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared dense barrier layer coating to one side of the base paper layer, and performing non-contact hot air drying at a drying temperature of 80 to 120° C. for a drying time of 5 to 20 min to obtain coated paper with a dense barrier layer coated on one side; S5: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared hydrophobic functional layer coating to the side of the coated paper obtained in step S4 coated with a dense barrier layer on one side, and performing non-contact hot air drying at a drying temperature of 100 to 120° C. for a drying time of 5 to 20 min, to obtain a coated paper coated with a dense barrier layer and a hydrophobic functional layer on one side in sequence; S6: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared dynamic composite humidity control functional layer coating to the coated paper obtained in step S5, which is coated with a dense barrier layer and a hydrophobic functional layer on one side in sequence, and coating the dynamic composite humidity control functional layer coating on the uncoated side of the coated paper, and performing non-contact The aluminum-free humidity-regulating lining paper for cigarettes is obtained by contact hot air drying at a drying temperature of 100 to 120° C. and a drying time of 10 to 30 minutes.

3. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: In the dense barrier layer of the aluminum-free humidity-regulating lining paper for cigarettes, the mass percentages of the polyvinyl alcohol and glycerol are (70-95)%: (5-30)%.

4. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 3, characterized in that: In the dense barrier layer of the aluminum-free humidity-regulating lining paper for cigarettes, the mass percentages of the polyvinyl alcohol and glycerol are 70%:30%, 95%:5% or 80%:20%.

5. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The coating amount of the coating liquid formed by polyvinyl alcohol, glycerin and water is 0.5 to 1 g / m 2 .

6. The aluminum-free humidity-controlling lining paper for cigarettes according to any one of claims 1 to 5, characterized in that: The molecular weight of the polyvinyl alcohol is 120,000 to 250,000, and the alcoholysis degree is 78 to 88%.

7. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 2-15%, the mass fraction of silane coupling agent is 0.5-2%, the mass fraction of nanocellulose is 5-25% and the mass fraction of carboxymethyl cellulose is 60-80%. The coating amount of the coating liquid of the hydrophobic functional layer coating is 1-3 g / m 2 .

8. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 2%, the mass fraction of the silane coupling agent is 1.5%, the mass fraction of nanocellulose is 10% and the mass fraction of carboxymethyl cellulose is 86.5%.

9. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 15%, the mass fraction of silane coupling agent is 0.5%, the mass fraction of nano cellulose is 5% and the mass fraction of carboxymethyl cellulose is 79.5%.

10. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 5%, the mass fraction of silane coupling agent is 2%, the mass fraction of nano cellulose is 10% and the mass fraction of carboxymethyl cellulose is 83%.

11. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 3%, the mass fraction of silane coupling agent is 1%, the mass fraction of nano cellulose is 15% and the mass fraction of carboxymethyl cellulose is 81%.

12. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 10%, the mass fraction of silane coupling agent is 1.8%, the mass fraction of nano cellulose is 15% and the mass fraction of carboxymethyl cellulose is 86.7%.

13. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of calcium stearate in the hydrophobic functional layer coating is 12%, the mass fraction of the silane coupling agent is 0.6%, the mass fraction of nanocellulose is 19% and the mass fraction of carboxymethyl cellulose is 68.4%.

14. The aluminum-free humidity-controlling lining paper for cigarettes according to any one of claims 1, 2, 7 to 13, characterized in that: The silane coupling agent is selected from KH550, KH560, KH580, A-151 or A-171, the diameter of the nanocellulose is 10-100 nm, the length is 1-30 μm, and the molecular weight of the carboxymethyl cellulose is 150,000-300,000.

15. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of sodium alginate in the dynamic composite humidity-adjusting functional layer coating is 69.5%, the mass fraction of nanoporous calcium silicate is 20%, the mass fraction of glycerol is 10%, and the mass fraction of hyaluronic acid is 0.5%.

16. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of sodium alginate in the dynamic composite humidity-adjusting functional layer coating is 53%, the mass fraction of nanoporous calcium silicate is 30%, the mass fraction of glycerol is 15%, and the mass fraction of hyaluronic acid is 2%.

17. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of sodium alginate in the dynamic composite humidity-adjusting functional layer coating is 63.5%, the mass fraction of nanoporous calcium silicate is 15%, the mass fraction of glycerol is 20%, and the mass fraction of hyaluronic acid is 1.5%.

18. The aluminum-free humidity-controlling lining paper for cigarettes according to claim 2, characterized in that: The mass fraction of sodium alginate in the dynamic composite humidity-adjusting functional layer coating is 70.3%, the mass fraction of nanoporous calcium silicate is 19%, the mass fraction of glycerol is 10%, and the mass fraction of hyaluronic acid is 0.7%.

19. The aluminum-free humidity-controlling lining paper for cigarettes according to any one of claims 2, 15 to 18, characterized in that: The coating amount of the coating liquid of the dynamic composite humidity control functional layer coating is 2 to 5 g / m 2 .

20. The aluminum-free humidity-controlling lining paper for cigarettes according to any one of claims 1, 2, 15 to 18, characterized in that: The molecular weight dispersity index of the sodium alginate is 1.9-2.3, the M / G monosaccharide ratio is 0.5-1, the particle size of the nanoporous calcium silicate is 5-100 nm, and the molecular weight of the hyaluronic acid is 500,000-3,000,000.

21. The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes according to any one of claims 1 to 20, characterized in that: The following steps are involved: S1: preparing a dense barrier layer coating: preparing a polyvinyl alcohol solution of a certain mass concentration, then mixing polyvinyl alcohol and glycerol in a mass percentage of (70-95)%:(5-30)%, adding water to adjust the viscosity of the coating liquid to 100-500cp, and setting aside; S2: Preparation of hydrophobic functional layer coating: Prepare a carboxymethyl cellulose aqueous solution of a certain mass concentration, select commercially available calcium stearate emulsion and nanocellulose hydrogel, and adjust the concentration of calcium stearate in the coating liquid according to the concentration of calcium stearate in the coating liquid. The mass fraction of the hydrophobic functional layer coating is 2-15%, the mass fraction of the silane coupling agent is 0.5-2%, the mass fraction of the nanocellulose is 5-25% and the mass fraction of the carboxymethyl cellulose is 60-90%, and then water is added to adjust the viscosity of the coating liquid to 200-800cp for standby use; S3: preparing a dynamic composite humidity-controlling functional layer coating: preparing a sodium alginate aqueous solution of a certain mass concentration, adding a certain amount of hyaluronic acid and mixing, then sequentially adding nanoporous calcium silicate and glycerol, preparing a dynamic composite humidity-controlling functional layer coating according to the mass fractions of the components in the coating liquid: 50-80% sodium alginate, 10-30% nanoporous calcium silicate, 5-20% glycerol, 0.5-2% hyaluronic acid, adding water to adjust the coating liquid viscosity to 300-900cp, and set aside; S4: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared dense barrier layer coating to one side of the base paper layer, and performing non-contact hot air drying at a drying temperature of 80 to 120° C. for a drying time of 5 to 20 min to obtain coated paper with a dense barrier layer coated on one side; S5: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared hydrophobic functional layer coating to the side of the coated paper obtained in step S4 coated with a dense barrier layer on one side, and performing non-contact hot air drying at a drying temperature of 100 to 120° C. for a drying time of 5 to 20 min, to obtain a coated paper coated with a dense barrier layer and a hydrophobic functional layer on one side in sequence; S6: Use any coating process such as blade coating, curtain coating or rod coating to transfer the prepared dynamic composite humidity-controlling functional layer coating to the coated paper obtained in step S5, which is coated with a dense barrier layer and a hydrophobic functional layer on one side in sequence, and apply the dynamic composite humidity-controlling functional layer coating to the uncoated surface of the coated paper, and perform non-contact hot air drying at a drying temperature of 100 to 120°C and a drying time of 10 to 30 minutes to obtain the aluminum-free humidity-controlling lining paper for cigarettes.

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