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

Abstract

The present invention provides a novel aluminum-free humidity-regulating lining paper for cigarettes and a preparation method thereof, which comprises a base paper layer, a dense barrier layer, a hydrophobic functional layer and a composite humidity-regulating 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 composite humidity-regulating layer comprises sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid. The present invention utilizes the hydrophobic synergistic effect of hydrophobic substances-calcium stearate and silane coupling agents, and with the help of the effect of nanocellulose physical cross-linking agents in a carboxymethyl cellulose matrix, forms a hydrophobic functional layer with hydrophobicity and certain barrier capacity, so as to solve the problem of reduced barrier properties of the dense barrier layer of polyvinyl alcohol under high humidity conditions. In addition, the present invention 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 carbonate to achieve the dynamic humidity-regulating performance of the lining paper.

Description

Technical Field

[0001] The invention belongs to the technical field of paper-based materials, and in particular relates to a cigarette lining paper with a humidity regulating function and used for cigarette packaging. Background Art

[0002] Tobacco plays an increasingly important role in the global economy. Tobacco and its products have a certain degree of hygroscopicity, and their moisture content has a certain impact on the storage, transportation, processing and intrinsic quality of tobacco products. At present, the main tobacco products produced in my country are cigarettes. Due to different regions and seasons, the environmental humidity in various places varies greatly, which makes the moisture content in cigarettes also vary to a certain extent. The moisture content in cigarettes will directly affect the smoking quality of cigarettes. When the moisture content of cigarettes is too high, it will cause incomplete combustion of tobacco, resulting in the loss of cigarette aroma. At the same time, high moisture content will also cause tobacco to mold, and the smoking quality will drop sharply; on the contrary, when the moisture content in cigarettes is too low, it will cause the cigarette to burn too fast and the burning smoke temperature to be too high, resulting in strong, dry, spicy and throat-piercing smoke. Therefore, the appropriate moisture content plays a very important role in the smoking quality of cigarettes.

[0003] For cigarette products, their moisture content is closely related to the moisturizing performance of cigarettes, and their moisturizing performance is affected by tobacco characteristics, moisturizers, packaging materials and other aspects. In recent years, the cigarette industry has used smoke moisturizing or hydrating to improve its smoking comfort. One is to add polyol moisturizers to tobacco. Although this method can maintain the moisture content of tobacco during processing and improve the processing resistance of tobacco, the added additives are directly added to the tobacco and participate in combustion during smoking, causing other impurities to be introduced into the smoke, affecting the sensory quality of cigarettes. Another method is to implant burst beads through the technology of embedded glue beads in the filter rod, and press them to break them when used, so as to increase the humidity of the smoke and improve the effect of intercepting the aroma of the filter rod, but this method greatly increases the production cost. In view of the problems with the above methods of imparting moisturizing properties to cigarettes, people began to consider giving cigarette packaging materials certain moisturizing and humidifying properties from the perspective of cigarette packaging materials with green and environmentally friendly processing processes to solve the problem of continuous constant humidity after the cigarette box packaging is unpacked.

[0004] Cigarette lining paper is a paper-based material between cigarette packs and cigarettes, which is in direct contact with cigarettes and is an important cigarette packaging material. Generally speaking, cigarette lining paper mainly plays the role of preserving fragrance, blocking air, blocking moisture, and shading. However, traditional cigarette lining paper does not have a dynamic humidity control function. In recent years, some cigarette lining papers with different preparation processes have emerged, and some authorized patents have also emerged, such as patents with patent numbers CN110696514B, CN114775331B, CN114086429B, CN111676729B, CN106868933B and other authorized patents. However, the cigarette lining papers involved in these preparation processes and patents either do not have a dynamic humidity control function, or use metal layers such as aluminum or titanium to achieve a barrier function. The prior art lacks green and environmentally friendly cigarette lining papers with excellent barrier properties and dynamic humidity control functions. In particular, due to the large temperature and humidity differences between the north and south of my country, the local microenvironment in the cigarette box packaging is given a certain dynamic humidity control function. It can independently adjust the humidity of the microenvironment in the cigarette packaging box through water locking and moisture absorption and drainage and moisturizing functions according to the humidity changes in the storage environment, thereby achieving the purpose of constant humidity preservation of cigarettes after the packaging is unpacked. This is a key technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] In view of the defects and shortcomings of the prior art, the present invention provides a novel aluminum-free humidity-regulating lining paper for cigarettes. The product uses biomass-based degradable polymers and polyvinyl alcohol's good film-forming properties to form a dense barrier layer on the surface of the base paper; at the same time, 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 molding degree. 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), nanoporous calcium silicate (water absorption-drainage function and sustained release) and hyaluronic acid (hygroscopicity, excellent water retention) to form a dynamic composite humidity control functional layer, giving the lining paper good dynamic humidity control function. In addition, another object of the present invention is to provide a method for preparing the novel aluminum-free humidity control lining paper for cigarettes.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A novel aluminum-free humidity-control lining paper for cigarettes, comprising a base paper layer, a dense barrier layer, a hydrophobic functional layer and a composite humidity-control layer; the dense barrier layer and the hydrophobic functional layer are sequentially arranged on the outer surface of the base paper layer from bottom to top, and the composite humidity-control 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, silane coupling agent, nanocellulose and carboxymethyl cellulose, and the composite humidity-control layer comprises sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid.

[0008] In view of the technical problems that the existing aluminum-free liner paper has poor barrier properties and a high degree of forming, the present invention creatively proposes to form a dual-effect barrier by using a dense barrier layer and a hydrophobic functional layer, and utilizes the good film-forming property of polyvinyl alcohol and the dense structure formed after film formation to effectively finish, physically cover and fill the porous structure on the surface of the base paper layer. However, since 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 having a negative impact on the dense structure of the polyvinyl alcohol coating, causing the polyvinyl alcohol coating to gradually swell and dissolve, greatly reducing its barrier performance. Therefore, a single polyvinyl alcohol coating cannot meet the barrier requirements under high humidity conditions. In the present invention, a hydrophobic functional layer is coated on the outside of the dense barrier layer of polyvinyl alcohol, 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 agents 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 the 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 volume, 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 property and uniform dispersion, the hydrophobic functional layer has good hydrophobicity and certain barrier capacity.

[0009] In the present invention, 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, the present invention creatively combines the organic moisturizing factor-hyaluronic acid with the inorganic particles-nanoporous calcium silicate to achieve the dynamic humidity control function of water-locking and moisturizing-draining and dehumidifying. Nanoporous calcium silicate can freely enter the long-chain multi-level structure of hyaluronic acid due to the nano-size effect, using Si-O - Negative ions and H + The electrostatic binding effect introduces the water adsorbed in the long-chain multi-level structure of the hyaluronic acid polymer into the nano-multi-level pore structure of the nano-calcium silicate particles. As the mass of the introduced water increases, the existence of water molecules in the nano-calcium silicate is mainly in the form of physical adsorption. Since the energy barrier of adsorption-desorption in physical adsorption is low, water molecules in the multi-level nano-pore structure of nano-calcium silicate undergo an adsorption-desorption process due to the influence of the partial pressure of water vapor in the surrounding environment, thereby being able to dynamically respond to changes in the humidity of the surrounding environment and realize the dynamic humidity control function.

[0010] Preferably, in the dense barrier layer of the novel aluminum-free humidity-regulating lining paper for cigarettes, the mass percentage of polyvinyl alcohol and glycerol can be (70-95)%: (5-30)%, the coating liquid formed by polyvinyl alcohol, glycerol and water has a viscosity of 100-500cp, and the coating amount is 0.5-1g / m 2 .

[0011] Preferably, in the dense barrier layer of the novel aluminum-free humidity-regulating lining paper for cigarettes, the molecular weight of the polyvinyl alcohol in the coating of the coating is 120,000 to 250,000, and the alcoholysis degree is 78 to 88%.

[0012] Preferably, in the hydrophobic functional layer of the novel aluminum-free humidity-regulating lining paper for cigarettes, the mass fraction of calcium stearate in the coating liquid 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 liquid viscosity is 200-800cp, and the coating amount is 1-3g / m 2 .

[0013] Preferably, in the hydrophobic functional layer of the novel aluminum-free humidity-regulating lining paper for cigarettes, the calcium stearate in the coating of the coating is selected from commercially available calcium stearate emulsion, the silane coupling agent is selected from one of KH550, KH560, KH580, A-151 or A-171, the nanocellulose has a diameter of 10 to 100 nm and a length of 1 to 30 μm, and the molecular weight of the carboxymethyl cellulose is 150,000 to 300,000.

[0014] Preferably, in the novel aluminum-free humidity-conditioning lining paper composite humidity-conditioning layer for cigarettes, the coating liquid 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 liquid viscosity is 300-900cp, and the coating amount is 2-5g / m 2 .

[0015] Preferably, in the novel aluminum-free humidity-control lining paper composite humidity-control layer for cigarettes, the molecular weight dispersion 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.

[0016] A method for preparing a novel aluminum-free humidity-conditioning lining paper for cigarettes comprises the following steps:

[0017] S1: preparing a dense barrier layer coating: first 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;

[0018] S2: Preparation of hydrophobic functional layer coating: firstly prepare a carboxymethyl cellulose aqueous solution of a certain mass concentration, select commercially available calcium stearate emulsion and nanocellulose hydrogel, and prepare 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 add water to adjust the viscosity of the coating liquid to 200-800cp for standby use;

[0019] S3: Preparation of composite humidity-control 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 composite humidity-control layer coating according to the mass fraction of each component in the coating liquid: 50-80% sodium alginate, 10-30% nanoporous calcium silicate, 5-20% glycerol, 0.5-2% hyaluronic acid, add water to adjust the viscosity of the coating liquid to 300-900cp, and set aside;

[0020] S4: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared dense barrier layer coating to a single side of the cigarette liner base paper, 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 single-side dense barrier layer coating;

[0021] 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 coated with the 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;

[0022] S6: using any coating process of blade coating, curtain coating or rod coating, transferring the prepared composite humidity-controlling layer coating to the coated paper with dense barrier layer and hydrophobic functional layer coated on one side in sequence, coating the composite humidity-controlling layer coating on the uncoated surface of the cigarette inner lining paper (i.e., the dense barrier layer and the hydrophobic functional layer are coated on the outer surface of the cigarette inner lining paper, and the composite humidity-controlling layer is coated on the inner surface of the cigarette inner lining paper), performing non-contact hot air drying at a drying temperature of 100 to 120° C. and a drying time of 10 to 30 min, to obtain a novel aluminum-free humidity-controlling inner lining paper for cigarettes;

[0023] The novel aluminum-free humidity-regulating lining paper for cigarettes and its preparation method provided by the present invention 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 view of the problem that the barrier property of the polyvinyl alcohol coating is reduced under high humidity conditions, the hydrophobic synergistic effect of the hydrophobic substance-calcium stearate and the silane coupling agent is utilized, and with the help of the action of the nanocellulose physical cross-linking agent in the carboxymethyl cellulose matrix, a hydrophobic functional layer with hydrophobicity and certain barrier capacity is formed. Under the action of the double-layer functional coating layer of the dense barrier layer and the hydrophobic functional layer, the aluminum-free lining paper for cigarettes is endowed with good barrier properties (low air permeability and low water vapor permeability) under high humidity conditions. In addition, in view of the technical problems and practical needs of the dynamic humidity control of cigarette lining paper, the present invention utilizes the good water-locking and moisturizing effect of the natural moisturizing factor-hyaluronic acid and the moisture absorption-drainage-slow-release effect of nanoporous calcium carbonate to achieve a dynamic response to changes in environmental humidity. At the same time, the Ca in the nanoporous calcium silicate 2+It can promote the cross-linking of sodium alginate to form a complex gel structure, so that it can form a stable three-dimensional network structure after extension and dehydration in the aqueous phase, which is beneficial to the structural uniformity and stability of the sodium alginate-based composite humidity-control layer. Since the selected biomass polymer material has good ductility, the prepared coating has a lower degree of forming, which can well meet the subsequent processing technology requirements of the aluminum-free lining paper for cigarettes. Therefore, the new aluminum-free humidity-control lining paper for cigarettes provided by the present invention has obvious beneficial effects: first, it has good softness, a dense surface structure, and a lower 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 keep moisture and draining water to release moisture, a dynamic response to changes in the humidity of the local microenvironment is achieved, thereby controlling the humidity changes of the local microenvironment within an acceptable range; finally, the production process of the new aluminum-free humidity-control lining paper for cigarettes provided by the present invention is green and environmentally friendly, and the materials used are biomass degradable materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The schematic diagram of the structure of the novel aluminum-free humidity-controlling liner paper for cigarettes of the present invention is shown;

[0025] In the figure, 1-base paper layer, 2-dense barrier layer, 3-hydrophobic functional layer, 4-composite humidity control layer

[0026] The components of the hydrophobic functional layer include calcium stearate, silane coupling agent, nano cellulose and carboxymethyl cellulose, and the components of the composite humidity regulating layer include sodium alginate, nano porous calcium silicate, glycerol and hyaluronic acid. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and beneficial effects of the present invention more clear, preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings to facilitate understanding by technical personnel.

[0028] like Figure 1 As shown, the novel aluminum-free humidity-regulating lining paper for cigarettes described in the present invention comprises a base paper layer 1, the upper surface of the base paper layer is provided with 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 composite humidity-regulating layer 4.

[0029] Specifically, in the present invention, 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 composite humidity regulating layer 4 includes sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid.

[0030] Preferably, in the dense barrier layer 2 of the novel aluminum-free humidity-regulating lining paper for cigarettes, the mass percentage of the polyvinyl alcohol and glycerol can be (70-95)%: (5-30)%, the coating liquid formed by the polyvinyl alcohol, glycerol and water has a viscosity of 100-500cp, and the coating amount is 0.5-1g / m 2 .

[0031] Preferably, in the dense barrier layer 2 of the novel aluminum-free humidity-regulating lining paper for cigarettes, the molecular weight of the polyvinyl alcohol in the coating of the coating is 120,000 to 250,000, and the alcoholysis degree is 78 to 88%.

[0032] Preferably, in the hydrophobic functional layer 3 of the novel aluminum-free humidity-regulating lining paper for cigarettes, the mass fraction of calcium stearate in the coating liquid 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 liquid viscosity is 200-800cp, and the coating amount is 1-3g / m 2 .

[0033] Preferably, in the hydrophobic functional layer 3 of the novel aluminum-free humidity-regulating lining paper for cigarettes, the calcium stearate in the coating of the coating is selected from commercially available calcium stearate emulsion, the silane coupling agent is selected from any one of KH550, KH560, KH580, A-151 or A-171, the nanocellulose has a diameter of 10 to 100 nm and a length of 1 to 30 μm, and the molecular weight of the carboxymethyl cellulose is 150,000 to 300,000.

[0034] Preferably, in the novel aluminum-free humidity-conditioning lining paper composite humidity-conditioning layer 4 for cigarettes, the coating liquid 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 liquid viscosity is 300-900cp, and the coating amount is 2-5g / m 2 .

[0035] Preferably, in the novel aluminum-free humidity-regulating lining paper composite humidity-regulating layer 4 for cigarettes, the molecular weight dispersion 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.

[0036] A preparation method of a novel aluminum-free humidity-regulating lining paper for cigarettes:

[0037] Example 1

[0038] S1: preparing a dense barrier coating: using commercially available polyvinyl alcohol with a molecular weight of 120,000 and a degree of alcoholysis of 78% to prepare a polyvinyl alcohol aqueous solution with a mass concentration of 2%, and preparing a polyvinyl alcohol / glycerol / water mixed coating solution with a coating liquid viscosity of 100cp according to a mass percentage of polyvinyl alcohol and glycerol of 70%:30% for standby use;

[0039] S2: Preparation of hydrophobic functional layer coating: Select commercially available carboxymethyl cellulose with a molecular weight of 200,000 to prepare a carboxymethyl cellulose aqueous solution with a mass concentration of 1%, select commercially available calcium stearate emulsion and nanocellulose hydrogel (diameter of 20nm, length of 4μm), select KH550 as silane coupling agent, and prepare a hydrophobic functional layer coating 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, and then add appropriate amount of water to adjust the viscosity of the coating liquid to 300cp for standby use;

[0040] S3: Preparation of composite humidity-control coating: Select commercially available sodium alginate with a molecular weight dispersion index (Mw / Mn) of 1.9 and an M / G monosaccharide ratio of 0.5 to prepare a sodium alginate aqueous solution with a mass concentration of 2%, add commercially available hyaluronic acid with a molecular weight of 1 million, and then add commercially available nanoporous calcium silicate and glycerol with a particle size of 5 nm in sequence, and prepare a composite humidity-control layer coating according to the mass fractions of each component in the coating liquid: 69.5% sodium alginate, 20% nanoporous calcium silicate, 10% glycerol, and 0.5% hyaluronic acid, and finally add water to adjust the coating liquid viscosity to 300cp for standby use;

[0041] 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 is 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;

[0042] S5: Use a doctor bar to transfer the prepared hydrophobic functional layer coating to the side of the above-mentioned single-sided dense barrier layer coated paper coated with a dense barrier layer, and the coating amount is 1g / m 2 , performing non-contact hot air drying at a drying temperature of 100° C. for a drying time of 20 min, and obtaining coated paper having a dense barrier layer and a hydrophobic functional layer sequentially coated on one side;

[0043] S6: Use a doctor bar to transfer the prepared composite humidity-controlling layer coating to the coated paper with a dense barrier layer and a hydrophobic functional layer coated on one side. Apply the composite humidity-controlling layer coating to the uncoated surface of the cigarette liner paper. The coating amount is 2 g / m 2, non-contact hot air drying was carried out, the drying temperature was 120°C, and the drying time was 10 min to obtain a new type of aluminum-free humidity-regulating lining paper for cigarettes.

[0044] Example 2

[0045] The same as Example 1, except that A-151 is selected as the silane coupling agent in step S2, and the 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; scraper coating is selected in step S4; 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.

[0046] Example 3

[0047] 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% for standby use; in step S2, KH560 is selected as the silane coupling agent, and a hydrophobic functional layer coating is prepared according to the mass fraction of calcium stearate of 5%, the mass fraction of silane coupling agent of 2%, the mass fraction of nanocellulose of 10% and the mass fraction of carboxymethyl cellulose of 83% in the coating liquid; in step S3, commercially available sodium alginate with a molecular weight dispersibility index (Mw / Mn) of 2.3 and an M / G monosaccharide ratio of 1 is selected, and a composite humidity-adjusting layer coating is prepared according to the mass fractions of each component in the coating liquid: 53% sodium alginate, 30% nanoporous calcium silicate, 15% glycerol, and 2% hyaluronic acid, 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.

[0048] Example 4

[0049] 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, 1% silane coupling agent, 15% nanocellulose and 81% carboxymethyl cellulose.

[0050] Example 5

[0051] 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, 1.5% hyaluronic acid to prepare the composite humidity-conditioning layer coating, and finally water is added to adjust the viscosity of the coating liquid to 900cp for standby use; in step S6, scraper coating is selected, and the coating amount is 5g / m 2 , drying time is 30min.

[0052] Example 6

[0053] 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% for standby use; in step S2, A-171 is selected as the silane coupling agent, and a hydrophobic functional layer coating is prepared according to the mass fraction of calcium stearate of 10%, the mass fraction of silane coupling agent of 1.8%, the mass fraction of nanocellulose of 15% and the mass fraction of carboxymethyl cellulose of 86.7% in the coating liquid; in step S3, commercially available sodium alginate with a molecular weight dispersibility index (Mw / Mn) of 2.2 and an M / G monosaccharide ratio of 0.8 is selected, and a composite humidity-adjusting layer coating is prepared according to the mass fractions of each component in the coating liquid: 70.3% sodium alginate, 19% nanoporous calcium silicate, 10% glycerol, and 0.7% hyaluronic acid, 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 .

[0054] Example 7

[0055] 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 12% calcium stearate, a mass fraction of 0.6% silane coupling agent, a mass fraction of 19% nanocellulose and a mass fraction of 68.4% carboxymethyl cellulose.

[0056] Example 8

[0057] The same as Example 1, except that the silane coupling agent selected in step S2 is KH580; the curtain coating is selected 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 22min.

[0058] The comparison of the barrier properties of the novel aluminum-free humidity-controlling lining paper for cigarettes prepared in the above-mentioned Examples 1 to 8 and the commercially available composite aluminum foil lining paper samples in terms of air permeability, water vapor permeability, etc. is shown in Table 1. In addition, in order to verify that the novel aluminum-free humidity-controlling lining paper for cigarettes of the present invention can dynamically control the humidity of the open environment in which the cigarette tobacco is located when used for cigarette packaging, so as to maintain the moisture content of the cigarettes within a small range. The eight novel aluminum-free humidity-controlling lining paper samples for cigarettes and the composite aluminum foil lining paper samples were placed in a cigarette box (containing 20 cigarettes) according to the cigarette production mode, and then placed in a constant temperature and humidity chamber to test the humidity control performance of the novel aluminum-free humidity-controlling lining paper for cigarettes. The comparison of the moisture content (%) of the cigarettes after unpacking for 48 hours in a high temperature and high humidity environment (38°C, 80%RH), a dry environment (38°C, 30%RH) and a normal humidity environment (38°C, 50%RH) was used to characterize.

[0059] Table 1. Barrier performance indicators of new aluminum-free humidity-regulating liner paper for cigarettes

[0060]

[0061] As can be seen from Table 1, in terms of barrier performance, the test data of air permeability and water vapor transmission rate of Examples 1 to 8 are similar to those of the control sample (commercially available composite aluminum foil lining paper). Examples 2, 3, 5, and 8 exhibit relatively good barrier performance due to the large coating amount of the hydrophobic functional layer and the composite humidity-controlling layer. The test data of air permeability and water vapor transmission rate show that the barrier performance of the novel aluminum-free humidity-controlling lining paper for cigarettes prepared in Examples 1 to 8 is comparable to that of the commercially available composite aluminum foil lining paper, indicating that the novel aluminum-free humidity-controlling lining paper for cigarettes prepared according to the present invention can meet the requirements of cigarette packaging for the barrier performance of cigarette lining paper in practical applications.

[0062] In addition, it can be seen from the changes in the moisture content of cigarettes under different temperature and humidity conditions in Table 1 that although the composite aluminum foil lining paper has good barrier properties, it does not have dynamic humidity control performance, 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 under high temperature and high humidity environments increases by 25.8%; the moisture content of the cigarettes under dry environments decreases by 20.0%). By comparison, it is found that after the new aluminum-free humidity-controlling lining paper for cigarettes in Examples 1 to 8 of the present invention is placed in the cigarette packaging according to the cigarette production mode, the fluctuation range of the moisture content of the cigarettes after unpacking is very small under different temperature and humidity conditions. It shows that the new aluminum-free humidity-controlling lining paper for cigarettes prepared in Examples 1 to 8 has good dynamic humidity control performance. Under high temperature and high humidity environments, 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; under dry environments, 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 the novel aluminum-free humidity-controlling liner paper for cigarettes, indicating that the novel aluminum-free humidity-controlling liner paper for cigarettes provided by the present invention has good environmental humidity response capability and sensitive dynamic humidity control performance.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention rather than to limit them. Although the present invention has been described in detail through the above embodiments, those skilled in the art should understand that various changes can be made to the contents of the present invention in details and forms without departing from the scope defined by the claims of the present invention; 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 method for preparing aluminum-free humidity-controlling lining paper for cigarettes, characterized in that: The aluminum-free humidity-control lining paper for cigarettes comprises a base paper layer and a composite humidity-control layer; a dense barrier layer and a hydrophobic functional layer are sequentially arranged on the outer surface of the base paper layer from bottom to top, and the composite humidity-control layer is arranged on the inner surface of the base paper layer; wherein the dense barrier layer comprises polyvinyl alcohol and glycerol, the hydrophobic functional layer comprises calcium stearate, silane coupling agent, nanocellulose and carboxymethyl cellulose, and the composite humidity-control layer comprises sodium alginate, nanoporous calcium silicate, glycerol and hyaluronic acid; The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes comprises the following steps: S1: preparing a dense barrier layer coating: firstly 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: firstly prepare a carboxymethyl cellulose aqueous solution of a certain mass concentration, select commercially available calcium stearate emulsion and nanocellulose hydrogel, and prepare 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 add water to adjust the viscosity of the coating liquid to 200-800cp for standby use; S3: Preparation of composite humidity-control 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 composite humidity-control layer coating according to the mass fraction of each component in the coating liquid: 50-80% sodium alginate, 10-30% nanoporous calcium silicate, 5-20% glycerol, 0.5-2% hyaluronic acid, add water to adjust the viscosity of the coating liquid 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 a single side of the cigarette liner base paper, 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 single-side dense barrier layer coating; 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 coated with the 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 composite humidity-controlling layer coating to the coated paper with dense barrier layer and hydrophobic functional layer coated on one side in sequence, and coat the composite humidity-controlling layer coating on the uncoated surface of the cigarette lining paper, that is, the dense barrier layer and the hydrophobic functional layer are coated on the outer surface of the cigarette lining paper, and then coat the composite humidity-controlling layer 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 aluminum-free humidity-controlling cigarette lining paper.

2. The method for preparing 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 can be (70-95)%: (5-30)%, the viscosity of the coating liquid formed by the polyvinyl alcohol, glycerol and water is 100-500cp, and the coating amount is 0.5-1g / m 2 .

3. The method for preparing 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 molecular weight of the polyvinyl alcohol in the coating of the coating layer is 120,000 to 250,000, and the alcoholysis degree is 78 to 88%.

4. The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: In the hydrophobic functional layer of the aluminum-free humidity-regulating lining paper for cigarettes, the mass fraction of calcium stearate in the coating liquid is 2-15%, the mass fraction of the 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 liquid viscosity is 200-800cp, and the coating amount is 1-3g / m 2 .

5. The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: In the hydrophobic functional layer of the aluminum-free humidity-regulating lining paper for cigarettes, the calcium stearate in the coating of the coating is selected from commercially available calcium stearate emulsion, the silane coupling agent is selected from one of KH550, KH560, KH580, A-151 or A-171, the nanocellulose has a diameter of 10 to 100 nm and a length of 1 to 30 μm, and the molecular weight of the carboxymethyl cellulose is 150,000 to 300,000.

6. The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: In the composite humidity-conditioning layer of the aluminum-free humidity-conditioning lining paper for cigarettes, the coating liquid includes the following raw materials in mass percentage: 50-80% sodium alginate, 10-30% nanoporous calcium silicate, 5-20% glycerol, 0.5-2% hyaluronic acid, the coating liquid viscosity is 300-900cp, and the coating amount is 2-5g / m 2 .

7. The method for preparing the aluminum-free humidity-controlling lining paper for cigarettes according to claim 1, characterized in that: In the aluminum-free humidity-control lining paper composite humidity-control layer for cigarettes, the molecular weight dispersion 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.

8. Aluminum-free humidity-conditioning lining paper for cigarettes prepared by the method according to any one of claims 1 to 7.

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