CN118216698A - Preparation method of reconstituted tobacco modified by ethylated nanocellulose and reconstituted tobacco - Google Patents

Abstract

The present invention provides a preparation method of ethylated nanocellulose modified reconstituted tobacco and the reconstituted tobacco, belonging to the technical field of reconstituted tobacco in the tobacco industry, including: using a low eutectic solvent to purify and pretreat pulp fibers; then sequentially performing an alkalization reaction and an etherification reaction, and then performing solid-liquid separation, washing and drying to obtain ethylated cellulose fibers; dispersing the ethylated cellulose fibers in water, and treating them by a high-pressure homogenization method combined with an ultrasonic crushing method to obtain an ethylated nanocellulose dispersion; using a pulp addition or coating method to uniformly apply the ethylated nanocellulose dispersion to the inside or surface of the reconstituted tobacco to obtain ethylated nanocellulose modified reconstituted tobacco. The reconstituted tobacco prepared by the method has excellent hydrophobicity, surface strength and tensile strength, improves the comprehensive quality of the reconstituted tobacco, and solves the problems of easy moisture absorption, poor surface strength and low tensile strength in the production and use of existing reconstituted tobacco.

Description

A preparation method of reconstituted tobacco leaves modified with ethylated nanocellulose and reconstituted tobacco leaves

Technical Field

The invention belongs to the technical field of reconstituted tobacco in the tobacco industry, and particularly relates to a preparation method of ethylated nanocellulose-modified reconstituted tobacco and the reconstituted tobacco.

Background technique

Reconstituted tobacco, also known as tobacco flakes or reconstituted tobacco, is an important raw material for traditional combustion cigarettes and new heating cigarettes. There are four main methods for manufacturing reconstituted tobacco, depending on the processing technology, namely, roller pressing, thick slurry method, wet papermaking method and dry papermaking method. At present, the main problems existing in the production and use of the four types of reconstituted tobacco include three aspects: (1) excessive hygroscopicity, easy to absorb moisture, resulting in poor adaptability to the machine, adhesion, mold, short storage cycle, and affecting consumer experience during the silk making and rolling process; (2) low surface strength, easy to fall off or break, low silk yield, serious raw material loss and waste, and low processing resistance in subsequent processing; (3) low tensile strength, easy to break during the rolling process, affecting the continuous stability of processing and production. Solving these defects and problems existing in existing reconstituted tobacco is an important topic in the field of reconstituted tobacco.

Summary of the invention

In order to fundamentally solve the problems of easy moisture absorption, poor surface strength and low tensile strength in the production and use of reconstituted tobacco leaves, the present invention provides a method for preparing reconstituted tobacco leaves modified with ethylated nanocellulose. The reconstituted tobacco leaves prepared by the method have excellent hydrophobic properties, surface strength and tensile strength, improve the comprehensive performance and quality of the reconstituted tobacco leaves, and solve the problems of easy moisture absorption, poor surface strength and low tensile strength in the production and use of existing reconstituted tobacco leaves.

The invention also provides a reconstituted tobacco leaf modified with ethylated nanocellulose.

The present invention is achieved through the following technical solutions:

The present invention provides a method for preparing reconstituted tobacco leaves modified with ethylated nanocellulose, the preparation method comprising:

Purifying and pretreating pulp fibers with a low eutectic solvent to remove hemicellulose and lignin from the pulp fibers to obtain purified pulp fibers;

Adding concentrated alkali solution to the purified pulp fiber for alkalization reaction, then adding ethyl chloride for etherification reaction, and obtaining ethylated cellulose fiber through solid-liquid separation, washing and drying;

The ethylated cellulose fibers are dispersed in water to obtain a fiber suspension, and then the fiber suspension is treated by a high-pressure homogenization method combined with an ultrasonic pulverization method to obtain ethylated nanocellulose;

mixing the ethylated nanocellulose with water to obtain an ethylated nanocellulose dispersion;

The ethylated nanocellulose dispersion is uniformly applied to the interior or surface of reconstituted tobacco leaves by adding or coating the ethylated nanocellulose in the pulp, and then low-temperature drying is performed to obtain reconstituted tobacco leaves modified with the ethylated nanocellulose.

Furthermore, the method of purifying the pulp fibers by using a low eutectic solvent to remove hemicellulose and lignin in the pulp fibers to obtain purified pulp fibers specifically includes:

The pulp fibers are immersed in a low eutectic solvent for purification pretreatment for 60 to 180 minutes to remove hemicellulose and lignin in the pulp fibers and retain cellulose to obtain purified pulp fibers;

Wherein, the pulp fiber comprises at least one of cotton pulp, wood pulp, bamboo pulp, flax pulp and bagasse pulp;

The hydrogen bond donor of the deep eutectic solvent includes at least one of carboxylic acid, polyol, urea and amide, the hydrogen bond acceptor of the deep eutectic solvent includes at least one of choline chloride, betaine, benzyltriethylammonium chloride and benzyltrimethylammonium chloride, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-20);

The content of α-cellulose in the purified pulp fibers is ≥90wt%.

Furthermore, the step of adding concentrated alkali solution to the purified pulp fiber for alkalization reaction, then adding ethyl chloride for etherification reaction, and obtaining ethylated cellulose fiber through solid-liquid separation, washing and drying specifically comprises:

Add concentrated alkali solution to the purified pulp fiber, perform alkalization reaction for 40 to 120 minutes, then add ethyl chloride at 45 to 100° C. and pressure of 3.5×10 ⁵ Pa to 1.8×10 ⁶ Pa, perform etherification reaction for 1 to 2 hours, and obtain ethylated cellulose fiber through solid-liquid separation, washing and drying;

Wherein, the concentration of the concentrated alkali solution is 15-50wt%, and the solute of the concentrated alkali solution includes sodium hydroxide or potassium hydroxide;

In the ethylated cellulose fiber, the content of ethoxy groups is 10 to 35 wt % and the degree of substitution is 0.8 to 2.6.

Furthermore, the mass ratio of the pulp fiber, sodium hydroxide and ethyl chloride is 1:(0.35-0.85):(0.2-0.4).

Furthermore, the concentration of the fiber suspension is ≤6wt%, and in the ethylated nanocellulose dispersion, the length of the ethylated nanocellulose is 1 to 100 μm and the diameter is 1 to 100 nm.

Furthermore, the ethylated nanocellulose dispersion is uniformly applied to the interior or surface of reconstituted tobacco leaves by adding or coating the ethylated nanocellulose in the pulp, and then low-temperature drying is performed to obtain reconstituted tobacco leaves modified with ethylated nanocellulose, which specifically includes:

In the processing technology of reconstituted tobacco leaves, the ethylated nanocellulose dispersion is uniformly applied to the interior of the reconstituted tobacco leaves by adding the ethylated nanocellulose in the pulp, and then low-temperature drying is performed to obtain the ethylated nanocellulose modified reconstituted tobacco leaves, wherein the addition amount of the ethylated nanocellulose is 0.5-5% of the mass of the ethylated nanocellulose modified reconstituted tobacco leaves;

Alternatively, in the processing of reconstituted tobacco leaves, the ethylated nanocellulose dispersion is evenly applied to the surface of the reconstituted tobacco leaves by coating, and then low-temperature drying is performed to obtain ethylated nanocellulose-modified reconstituted tobacco leaves, wherein the added amount of the ethylated nanocellulose is 0.5 to 5% of the mass of the ethylated nanocellulose-modified reconstituted tobacco leaves.

Furthermore, the processing technology of the reconstituted tobacco includes any one of a rolling method, a thick pulp method, a papermaking method and a dry method.

Based on the same inventive concept, the present invention provides a reconstituted tobacco leaf modified with ethylated nanocellulose, and the reconstituted tobacco leaf is prepared by the above-mentioned method for preparing a reconstituted tobacco leaf modified with ethylated nanocellulose.

Furthermore, the surface contact angle of the reconstituted tobacco leaf is 90° to 130°, the moisture absorption rate is ≤5%, the moisture release rate is ≤3%, the tensile index is ≥4.5 N·m·g ^-1 , and the shredded powder loss rate is ≤1%.

Preferably, the surface contact angle of the reconstituted tobacco leaf is 90° to 110°, the moisture absorption rate is ≤3%, the moisture release rate is ≤2%, the tensile index is ≥5.5 N·m·g ^-1 , and the shredded powder loss rate is ≤0.8%.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

1. The present invention discloses a method for preparing reconstituted tobacco leaves modified with ethylated nanocellulose. The method comprises the following steps: ethylating pulp fibers to obtain ethylated cellulose fibers; and then subjecting the fibers to a high-pressure homogenization method combined with ultrasonic pulverization to obtain ethylated nanocellulose; and finally, transferring the ethylated nanocellulose to the interior or surface of the reconstituted tobacco leaves by adding the ethylated nanocellulose in the pulp or applying the ethylated nanocellulose on the surface of the reconstituted tobacco leaves to obtain the ethylated nanocellulose-modified reconstituted tobacco leaves. Compared with unmodified reconstituted tobacco leaves, the modified reconstituted tobacco leaves have significantly improved properties such as hydrophobicity, surface strength and tensile strength.

2. The ethylated nanocellulose-modified reconstituted tobacco of the present invention has improved hydrophobicity and hygroscopicity, reduced moisture absorption and release rates compared with unmodified reconstituted tobacco. The moisture content of the modified reconstituted tobacco shows good stability during the processes of shredding, cutting, adding materials and flavoring, rolling and forming, packaging and storage. This effectively solves the technical problems of the existing reconstituted tobacco, such as poor adaptability to machines, adhesion, mildew, short storage period, and impact on consumer experience, due to its excessive hygroscopicity and easy moisture absorption during shredding and rolling. The storage period and shelf life of the reconstituted tobacco products are extended, the product quality stability is guaranteed, and the consumer experience is guaranteed.

3. The ethylated nanocellulose-modified reconstituted tobacco of the present invention enhances the surface strength of the reconstituted tobacco, reduces the powder and slag falling rate, and improves the silk-forming rate by applying ethylated nanocellulose, thereby solving the problems of low surface strength, easy powder and slag falling or breaking, low silk-forming rate, and serious loss and waste of raw materials, and overcomes the defects and shortcomings of low processing resistance in subsequent processing; at the same time, the tensile strength of the reconstituted tobacco is also improved, solving the problem of easy breakage during the winding process due to low tensile strength, thereby improving the continuous stability of the processing and production of the reconstituted tobacco, and the adaptability to machines is significantly enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

Figure 1 shows the surface contact angle of the modified roller-pressed reconstituted tobacco leaves.

Figure 2 shows the surface contact angle of modified thick pulp reconstituted tobacco leaves.

FIG. 3 shows the surface contact angle of the modified papermaking process reconstituted tobacco leaves.

FIG. 4 shows the surface contact angle of the modified dry-process reconstituted tobacco leaf.

Detailed ways

The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

The overall idea of the present invention is as follows:

Nanocellulose (NCC) is a rigid rod-shaped polymer with a diameter of 1 to 100 nm and a length of tens to hundreds of nanometers, which can be obtained from cheap and renewable cellulose by acid hydrolysis or enzymatic hydrolysis to remove the amorphous region in cellulose. It not only has the basic structure and good properties of cellulose, but also has the characteristics of nanoparticles, such as large specific surface area, high elastic modulus and reactivity. There are a large number of hydroxyl groups on the surface of NCC, which can form strong hydrogen bonds, and hydrogen bonds determine the various properties of cellulose. The nano-size effect of cellulose gives it excellent mechanical properties. It can be used as a reinforcing agent for polymer materials, significantly improving the thermal stability, mechanical strength, hardness, rigidity and flexibility of polymers, thereby producing polymer composite materials with high strength, high thermal stability and high mechanical properties.

Ethyl cellulose is a compound derived from cellulose. A part of the hydroxyl groups in its molecular structure is replaced by ethoxy groups. It has the characteristics of adhesion, hydrophobicity, and film-forming properties. Ethyl cellulose is soluble in many organic solvents. The viscosity of its solution depends on the type of alcohol used and the content of alcohol in the solvent. It is widely used in food, pharmaceuticals, and cosmetics. In the food industry, ethyl cellulose is often used as a thickener, stabilizer, and gelling agent to improve the texture and taste of food. In the pharmaceutical industry, ethyl cellulose can be used as a sustained-release agent to control the release rate of drugs and improve the bioavailability of drugs. In the cosmetics field, ethyl cellulose can increase the viscosity and consistency of the product, improve the texture and application performance. In the textile industry, ethyl cellulose can be used as a printing and dyeing auxiliary and textile thickener to improve the adhesion of dyes and the softness of textiles. Ethyl cellulose is a multifunctional compound with broad application prospects. Its special solution properties and ability to regulate viscosity make it an ideal choice for many industries.

In view of the defects and deficiencies in the production and use of reconstituted tobacco leaves, such as easy moisture absorption, poor surface strength, and low tensile strength, the present invention proposes a reconstituted tobacco leaf modified with ethylated nanocellulose from the perspective of purification, ethylation, and nano-crystallization of cellulose pulp fibers. The present invention is the first to apply ethyl cellulose to the modification of reconstituted tobacco leaves, and the obtained modified reconstituted tobacco leaves have excellent hydrophobic properties, surface strength, and tensile strength, which improves the comprehensive performance and quality of reconstituted tobacco leaves and solves the problems of easy moisture absorption, poor surface strength, and low tensile strength in the production and use of existing reconstituted tobacco leaves.

Specifically, in the preparation of the modified reconstituted tobacco leaves of the present invention, firstly, cellulose pulp fibers are purified by using a low eutectic solvent to remove hemicellulose and lignin in the fibers to obtain purified pulp fibers; secondly, the purified pulp fibers are ethylated to obtain ethylated cellulose fibers; thirdly, the ethylated cellulose fibers are subjected to a high-pressure homogenization method combined with an ultrasonic pulverization treatment to obtain ethylated nanocellulose; finally, the ethylated nanocellulose is transferred and applied to the interior or surface of the reconstituted tobacco leaves by adding into the pulp or coating processing to obtain reconstituted tobacco leaves modified with ethylated nanocellulose. Compared with unmodified reconstituted tobacco leaves, the hydrophobic properties, mechanical properties, surface strength and other properties of the modified reconstituted tobacco leaves are significantly improved.

Among them, deep eutectic solvent (DES) is an emerging green solvent, which is a mixture of hydrogen bond donors and hydrogen bond acceptors in a certain molar ratio, and a eutectic mixture with a melting point lower than its original components formed by hydrogen bonding. It has the advantages of easy synthesis, strong stability, good biocompatibility, strong selectivity, and recyclability. DES not only has the advantages of low melting point, low vapor pressure, high thermal stability and easy recycling of imidazole ionic liquids, but also has a simple preparation process, low price, low toxicity, and biodegradability, which meets the 12 principles of green chemistry. Using DES to extract lignin and hemicellulose can overcome the technical difficulties of low treatment efficiency, large solvent loss, and severe lignin degradation in traditional pretreatment technology, and is an effective method to achieve green, efficient, and high-value utilization of plant fiber components.

Specifically, the present invention provides a method for preparing reconstituted tobacco leaves modified with ethylated nanocellulose, the preparation method comprising:

S1. Purifying and pretreating the pulp fiber using a low eutectic solvent to remove hemicellulose and lignin in the pulp fiber to obtain purified pulp fiber;

S2. Adding concentrated alkali solution to the purified pulp fiber for alkalization reaction, adding ethyl chloride for etherification reaction, and obtaining ethylated cellulose fiber by solid-liquid separation, washing and drying;

S3. dispersing the ethylated cellulose fibers in water to obtain a fiber suspension, and then treating the fiber suspension by high pressure homogenization combined with ultrasonic pulverization to obtain ethylated nanocellulose, and dissolving the ethylated nanocellulose in water to obtain an ethylated nanocellulose dispersion;

S4. The ethylated nanocellulose dispersion is uniformly applied to the interior or surface of reconstituted tobacco leaves by adding or coating the dispersion in the pulp, and then low-temperature drying is performed to obtain reconstituted tobacco leaves modified with ethylated nanocellulose.

In step S1, the advantage of the α-cellulose content in the purified pulp fibers being ≥ 90 wt% is that the fiber purity can be improved and the tensile strength of the reconstituted tobacco leaves can be enhanced.

In step S2, concentrated alkali solution is added to the purified pulp fiber for alkalization reaction, and then ethyl chloride is added for etherification reaction, and solid-liquid separation, washing and drying are performed to obtain ethylated cellulose fiber, which specifically includes:

Add concentrated alkali solution to the purified pulp fiber, perform alkalization reaction for 40 to 120 minutes, then add ethyl chloride at 45 to 100° C. and pressure of 3.5×10 ⁵ Pa to 1.8×10 ⁶ Pa, perform etherification reaction for 4 to 10 hours, and obtain ethylated cellulose fiber through solid-liquid separation, washing and drying;

Wherein, the concentration of the concentrated alkali solution is 15-50wt%, and the solute of the concentrated alkali solution includes sodium hydroxide or potassium hydroxide;

In the ethylated cellulose fiber, the content of ethoxy groups is 10 to 35 wt % and the degree of substitution is 0.8 to 2.6.

Furthermore, the mass ratio of the pulp fiber, sodium hydroxide and ethyl chloride is 1:(0.35-0.85):(0.2-0.4).

The preparation method of the ethylated nanocellulose-modified reconstituted tobacco and the reconstituted tobacco of the present application will be described in detail below in combination with examples and experimental data.

Example 1

The preparation of a roller-pressed reconstituted tobacco leaf modified with ethylated nanocellulose in this embodiment comprises:

1) Obtaining cellulose fiber raw material: weighing 13.20 g of bamboo pulp (containing 10% water);

200 mL of ChCl/formic acid low eutectic solvent was added for purification for 120 min to remove residual hemicellulose and lignin in the bamboo pulp fiber to obtain purified bamboo pulp;

2) Determine the feed ratio of cellulose, concentrated alkali solution, and ethyl chloride solution: feed the purified bamboo pulp, sodium hydroxide, and ethyl chloride in a mass ratio of 1:0.75:0.2;

3) Soaking the fiber raw material in the reaction solvent: Soak the weighed bamboo pulp in water and stir it continuously to make it evenly dispersed;

4) adding concentrated alkali solution to the dispersion obtained in step 3) for alkalization reaction, wherein the NaOH concentration is 35%, the reaction temperature is 55°C, the pressure in the autoclave is 4.5×10 ⁵ Pa, and the reaction time is 1 hour, then adding ethyl chloride solution, heating to 80°C for etherification reaction, and the reaction time is 1 hour;

5) After the reaction is completed, solid-liquid separation is performed, and the precipitate is washed with a 70% volume concentration ethanol aqueous solution and then dried to obtain purified ethylated cellulose fibers;

6) dispersing the purified ethylated cellulose fibers in an aqueous solution to prepare a fiber suspension having a mass concentration of 2.5%;

7) firstly pre-treating the obtained suspension using an ultrasonic crusher, the ultrasonic crusher parameters are 1200Wt, the crushing time is 10 minutes, and then further treating it using a high-pressure homogenizer to obtain ethylated nanocellulose. After testing, the ethylated nanocellulose has a length of 1 to 100 μm and a diameter of 1 to 100 nm;

8) Weigh 2 parts of ethylated nanocellulose with a degree of substitution of 1.2 (the content of ethoxy groups is 18.4 wt%) and add them into a beaker containing 98 parts of water to prepare a 2% paste-like ethylated nanocellulose dispersion;

9) In the roller pressing process, the prepared ethylated nanocellulose dispersion is mixed with tobacco powder and other materials (the amount of ethylated nanocellulose added is 3 wt%), and after multi-stage roller pressing and multi-stage drying processes, a modified roller-pressed papermaking tobacco leaf is obtained.

Example 2

The present embodiment provides a method for preparing a thick pulp method reconstituted tobacco leaf modified with ethylated nanocellulose, comprising:

1) Obtaining cellulose fiber raw material: weighing 27 g of eucalyptus pulp (containing 10% water);

200 mL of benzyl dimethyl ammonium chloride/lactic acid low eutectic solvent was added for purification treatment for 150 min to remove residual hemicellulose and lignin in the eucalyptus pulp to obtain purified pulp fiber;

2) Determine the feed ratio of cellulose, alkali solution and ethyl chloride solution: feed the purified eucalyptus pulp, sodium hydroxide and ethyl chloride in a mass ratio of 1:0.85:0.4;

3) Soaking the fiber raw material in the reaction solvent: Soak the weighed bamboo pulp powder in water and stir it continuously to make it evenly dispersed;

4) adding alkaline solution to the dispersion obtained in step 3) for alkalization reaction, wherein the NaOH concentration is 40%, the reaction temperature is 45°C, the pressure in the autoclave is 5.5×10 ⁵ Pa, and the reaction time is 2 hours, and then adding ethyl chloride solution, heating to 85°C for etherification reaction, and the reaction time is 2 hours;

5) After the reaction is completed, solid-liquid separation is performed, and the precipitate is washed with a 75% volume concentration ethanol aqueous solution and then dried to obtain purified ethylated cellulose fibers;

6) dispersing the purified ethylated cellulose fibers in an aqueous solution to prepare a fiber suspension having a mass concentration of 4.5%;

7) firstly pre-treating the obtained suspension using an ultrasonic crusher, the ultrasonic crusher parameter is 1200Wt, the crushing time is 12 minutes, and then further treating it using a high-pressure homogenizer to obtain ethylated nanocellulose;

8) Weigh 1 part of ethylated nanocellulose with a degree of substitution of 1.2 (the content of ethoxy groups is 21.8 wt%) and add it to a beaker containing 99 parts of water to prepare a 1% paste-like ethylated nanocellulose dispersion;

9) In the process of preparing thick pulp reconstituted tobacco, the prepared ethylated nanocellulose dispersion is mixed with tobacco powder and other materials (the amount of ethylated nanocellulose added is 4wt%), and after the slurry is spread by casting method and multi-stage drying process, the modified thick pulp papermaking tobacco is obtained.

Example 3

The preparation of a papermaking process reconstituted tobacco leaf modified with ethylated nanocellulose in this embodiment comprises:

1) Obtaining cellulose fiber raw material: weighing 32 g of cotton stalk pulp (containing 10% water);

200 mL of ChCl/glycerol/AlCl3 ternary low eutectic solvent was added for purification for 100 min to remove residual hemicellulose and lignin in the cotton stalk pulp to obtain purified pulp fiber;

2) Determine the feed ratio of cellulose, alkali solution and ethyl chloride solution: feed the purified cotton stalk pulp, sodium hydroxide and ethyl chloride in a mass ratio of 1:0.35:0.3;

3) Soaking the fiber raw material in the reaction solvent: Soak the weighed bamboo pulp powder in water and stir it continuously to make it evenly dispersed;

4) adding alkaline solution to the dispersion obtained in step 3) for alkalization reaction, wherein the NaOH concentration is 41%, the reaction temperature is 55° C., the pressure in the autoclave is 1.5×10 ⁶ Pa, and the reaction time is 1 hour, and then adding ethyl chloride solution, heating to 85° C. for etherification reaction, and the reaction time is 1.5 hours;

5) After the reaction is completed, solid-liquid separation is performed, and the precipitate is washed with a 70% volume concentration ethanol aqueous solution and then dried to obtain purified ethylated cellulose fibers;

6) dispersing the purified ethylated cellulose fibers in an aqueous solution to prepare a fiber suspension having a mass concentration of 5%;

7) firstly pre-treating the obtained suspension using an ultrasonic crusher, the ultrasonic crusher parameter is 1200Wt, the crushing time is 10 minutes, and then further treating it using a high-pressure homogenizer to obtain ethylated nanocellulose;

8) Weigh 0.8 parts of ethylated nanocellulose with a degree of substitution of 0.8 (the content of ethoxy groups is 30.4 wt%) and add it to a beaker containing 99.2 parts of water to prepare a 0.8% paste-like ethylated nanocellulose dispersion;

9) In the process of preparing papermaking tobacco leaves, the prepared ethylated nanocellulose dispersion is transferred to the surface of the reconstituted tobacco leaves by spray coating (the amount of ethylated nanocellulose added is 3wt%), and after a low-temperature drying process, a modified papermaking tobacco leaf is obtained.

Example 4

The preparation of dry-process reconstituted tobacco leaves modified with ethylated nanocellulose in this embodiment includes:

1) Obtaining cellulose fiber raw material: weighing 32 g of cotton stalk pulp (containing 10% water);

200 mL of ChCl/propylene glycol/AlCl3 ternary low eutectic solvent was added for purification for 180 min to remove residual hemicellulose and lignin in the cotton stalk pulp to obtain purified pulp fiber;

2) Determine the feed ratio of cellulose, alkali solution and ethyl chloride solution: feed the purified cotton stalk pulp, sodium hydroxide and ethyl chloride in a mass ratio of 1:0.55:0.25.

3) Soaking the fiber raw material in the reaction solvent: Soak the weighed bamboo pulp powder in water and stir it continuously to make it evenly dispersed;

4) adding alkaline solution to the dispersion obtained in step 3) for alkalization reaction, wherein the NaOH concentration is 23%, the reaction temperature is 65°C, the pressure in the autoclave is 1.7×10 ⁶ Pa, and the reaction time is 1 hour, then adding ethyl chloride solution, heating to 85°C for etherification reaction, and the reaction time is 2 hours;

5) After the reaction is completed, solid-liquid separation is performed, and the precipitate is washed with a 70% volume concentration ethanol aqueous solution and then dried to obtain purified ethylated cellulose fibers;

6) dispersing the purified ethylated cellulose fibers in an aqueous solution to prepare a fiber suspension having a mass concentration of 4.5%;

7) firstly pre-treating the obtained suspension using an ultrasonic crusher, the ultrasonic crusher parameter is 1200Wt, the crushing time is 10 minutes, and then further treating it using a high-pressure homogenizer to obtain ethylated nanocellulose;

8) Weigh 0.8 parts of ethylated nanocellulose with a degree of substitution of 0.9 (the content of ethoxy groups is 25.6 wt%) and add it to a beaker containing 99.2 parts of water to prepare a 0.8% paste-like ethylated nanocellulose dispersion;

9) During the preparation of dry-process reconstituted tobacco leaves, the prepared ethylated nanocellulose dispersion is transferred to the surface of the reconstituted tobacco leaves by spray coating (the amount of ethylated nanocellulose added is 4 wt%), and after a low-temperature drying process, a modified dry-process papermaking tobacco leaf is obtained.

The test results of various performance indicators of the modified reconstituted tobacco leaves of the four embodiments are shown in Table 1, and the contact angles of the modified reconstituted tobacco leaves of the four embodiments are shown in Figures 1 to 4.

Table 1 Various test indicators of modified reconstituted tobacco leaves

In Table 1, the four control samples are respectively the reconstituted tobacco leaves that have not been treated with the ethylated nanocellulose dispersion in step 9) of Examples 1 to 4.

As can be seen from Table 1 above, compared with the unmodified control sample, the tensile index of the four modified reconstituted tobacco leaves increased significantly, indicating that the tensile strength increased significantly. The contact angles all increased significantly, indicating that the hydrophobicity of the reconstituted tobacco leaves was improved, and the moisture absorption rate and moisture release rate were greatly reduced, showing that the reconstituted tobacco leaves had good moisture absorption and desorption resistance, and the stability of the moisture content with the change of ambient temperature and humidity increased. In addition, the powder loss rate of the shredded reconstituted tobacco leaves was significantly reduced, indicating that its surface strength was enhanced, the powder loss rate was reduced, and the processing resistance was improved. In short, the comprehensive performance of the reconstituted tobacco leaves modified by ethylated nanocellulose has been significantly improved.

The processes for preparing reconstituted tobacco leaves by the rolling method, thick pulp method, papermaking method and dry method involved in Examples 1-4 of the present invention all adopt existing processes, and their specific process steps are not described in detail here.

Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. The preparation method of the ethylated nanocellulose modified reconstituted tobacco is characterized by comprising the following steps of:

purifying and pre-treating the pulp fiber by adopting a eutectic solvent to remove hemicellulose and lignin in the pulp fiber, so as to obtain purified pulp fiber;

Adding concentrated alkali liquor into the purified pulp fibers for alkalization reaction, then adding chloroethane for etherification reaction, and obtaining ethylated cellulose fibers through solid-liquid separation, washing and drying;

Dispersing the ethylated cellulose fibers in water to obtain a fiber suspension, and then treating the fiber suspension by adopting a high-pressure homogenization method and an ultrasonic crushing method to obtain ethylated nanocellulose;

Mixing the ethylated nanocellulose with water to obtain ethylated nanocellulose dispersion liquid;

and uniformly applying the ethylated nanocellulose dispersion liquid to the inside or the surface of the reconstituted tobacco by adopting a processing mode of adding or coating in pulp, and then drying at a low temperature to obtain the ethylated nanocellulose modified reconstituted tobacco.

2. The method for preparing the reconstituted tobacco modified by ethylated nanocellulose as claimed in claim 1, wherein the method comprises the steps of purifying and pre-treating pulp fiber by adopting eutectic solvent to remove hemicellulose and lignin in the pulp fiber, and obtaining purified pulp fiber, and specifically comprises the following steps:

Soaking paper pulp fibers in a eutectic solvent for purification pretreatment for 60-180 min to remove hemicellulose and lignin in the paper pulp fibers, and retaining cellulose to obtain purified paper pulp fibers;

wherein the pulp fiber comprises at least one of cotton pulp, wood pulp, bamboo pulp, flax pulp and bagasse pulp;

The hydrogen bond donor of the eutectic solvent comprises at least one of carboxylic acid, polyalcohol, urea and amide, the hydrogen bond acceptor of the eutectic solvent comprises at least one of choline chloride, betaine, benzyl triethyl ammonium chloride and benzyl trimethyl ammonium chloride, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1 (1-20);

The content of alpha-cellulose in the purified pulp fiber is more than or equal to 90wt%.

3. The method for preparing the ethylated nanocellulose modified reconstituted tobacco according to claim 1, wherein the steps of adding concentrated alkali liquor into the purified pulp fiber for alkalization reaction, adding chloroethane for etherification reaction, and carrying out solid-liquid separation, washing and drying are carried out to obtain the ethylated cellulose fiber, and specifically comprise the following steps:

Adding concentrated alkali liquor into the purified pulp fiber, alkalizing for 40-120 min, adding chloroethane under the conditions of 45-100 ℃ and 3.5 multiplied by 10 ⁵ Pa-1.8 multiplied by 106Pa, etherification for 1-2 h, and carrying out solid-liquid separation, washing and drying to obtain the ethylated cellulose fiber;

Wherein the concentration of the concentrated alkali liquor is 15-50wt%, and the solute of the concentrated alkali liquor comprises sodium hydroxide or potassium hydroxide;

The content of ethoxy is 10-35 wt% and the substitution degree is 0.8-2.6.

4. The method for preparing the ethylated nanocellulose modified reconstituted tobacco according to claim 3, wherein the mass ratio of the pulp fiber to the sodium hydroxide to the chloroethane is 1 (0.35-0.85) (0.2-0.4).

5. The method for preparing reconstituted tobacco modified by ethylated nanocellulose as claimed in claim 1, wherein the concentration of the fiber suspension is less than or equal to 6wt%, and the length of ethylated nanocellulose in the ethylated nanocellulose dispersion is 1-100 μm and the diameter is 1-100 nm.

6. The method for preparing the reconstituted tobacco modified by the ethylated nanocellulose as claimed in claim 1, wherein the method for preparing the reconstituted tobacco modified by the ethylated nanocellulose by the method of adding or coating in slurry is characterized by uniformly applying the ethylated nanocellulose dispersion liquid to the inside or the surface of the reconstituted tobacco, and then drying at a low temperature to obtain the reconstituted tobacco modified by the ethylated nanocellulose, and specifically comprises the following steps:

In the processing technology of reconstituted tobacco, the ethylated nanocellulose dispersion liquid is uniformly applied to the inside of the reconstituted tobacco in a mode of adding in pulp, and then the reconstituted tobacco is dried at a low temperature to obtain ethylated nanocellulose modified reconstituted tobacco, wherein the adding amount of the ethylated nanocellulose is 0.5-5% of the mass of the ethylated nanocellulose modified reconstituted tobacco;

or in the processing technology of the reconstituted tobacco, the ethylated nanocellulose dispersion liquid is uniformly applied to the surface of the reconstituted tobacco in a coating mode, and then the reconstituted tobacco modified by the ethylated nanocellulose is obtained through low-temperature drying, wherein the addition amount of the ethylated nanocellulose is 0.5-5% of the mass of the reconstituted tobacco modified by the ethylated nanocellulose.

7. The method for preparing the reconstituted tobacco modified by ethylated nanocellulose as claimed in claim 6, wherein the processing technology of the reconstituted tobacco comprises any one of a rolling method, a thick slurry method, a papermaking method and a dry method.

8. An ethylated nanocellulose modified reconstituted tobacco characterized in that the reconstituted tobacco is prepared by the preparation method of the ethylated nanocellulose modified reconstituted tobacco described in any one of claims 1-8.

9. The reconstituted tobacco modified by ethylated nanocellulose as claimed in claim 8, wherein the surface contact angle of the reconstituted tobacco is 90-130 degrees, the moisture absorption rate is less than or equal to 5%, the moisture release rate is less than or equal to 3%, the tensile index is more than or equal to 4.5 n.m.g ^-1, and the shredding and powder dropping rate is less than or equal to 1%.

10. The reconstituted tobacco modified by ethylated nanocellulose as claimed in claim 9, wherein the surface contact angle of the reconstituted tobacco is 90-110 degrees, the moisture absorption rate is less than or equal to 3%, the moisture release rate is less than or equal to 2%, the tensile index is more than or equal to 5.5 n.m.g ^-1, and the shredding and powder dropping rate is less than or equal to 0.8%.