Method for preparing tobacco sheet by using tobacco-based cellulose nanofibrils

Abstract

The invention discloses a method for preparing tobacco sheets by utilizing tobacco-based cellulose nanofibrils, which comprises the following steps of: 1, putting tobacco stem pulp into a conical flask, adding biological enzyme into the tobacco stem pulp for pretreatment, and after the pretreatment is finished, carrying out inactivation treatment and removing residual enzyme liquid in the tobacco stem pulp; 2, pulping the tobacco stem pulp through a PFI pulping machine, and performing high-pressure homogenization treatment to obtain tobacco-based cellulose nanofibrils; 3, wood pulp is selected and compounded with mechanical pulp, lignin rosin sizing agent emulsion, tobacco pulp, PCC and guar gum are added, the tobacco-based cellulose nanofibrils are added into the pulp, sheet making is conducted on a rapid sheet forming device, and the tobacco sheets are obtained. According to the method, the tobacco-based cellulose nanofibrils are efficiently and safely separated from the tobacco stem pulp through a feruloyl esterase / cellulase combined mechanical method for the first time, the tobacco sheets are prepared, and the method has the advantages of being environmentally friendly in product, simple in process, high in production efficiency and the like.

Description

Technical Field

[0001] The invention relates to the field of nano materials, and in particular to a method for preparing tobacco sheets by utilizing tobacco-based cellulose nanofibrils. Background Art

[0002] Tobacco stems, as one of the important agricultural wastes in the tobacco industry, are often used to prepare tobacco flakes. Since tobacco stems, tobacco leaves and other lignocellulose resources have similar chemical compositions, tobacco stems have also been used as a sustainable resource for CNF separation and preparation in recent years. Tobacco-based cellulose nanofibers (TCNF) prepared from tobacco stems can have the same composition as tobacco stems and tobacco leaves, which is beneficial to improving the smoking quality and flavor quality of tobacco flakes. Luo et al. obtained tobacco stem-based cellulose nanofibers by cationic modification / homogenization of tobacco stem pulp, and applied them to replace part of the wood pulp in the preparation process of tobacco flake base. The study found that the addition of TCNF can reduce the amount of wood pulp and wood gas, and can improve the physical properties of tobacco flake base materials to maintain a high level.

[0003] However, the arabinoxylan in tobacco cell walls (such as tobacco) usually contains a large amount of arabinoxylan containing ferulic acid ester, which accounts for about 20% to 40% and 40% to 50% of the primary wall and secondary wall of grasses. The presence of lignin-ferulic acid-arabinoxylan complexes will block the attack of hydrolytic enzymes and seriously reduce the enzymatic hydrolysis efficiency of tobacco stems. The present invention prepares TCNF by pretreating tobacco stem pulp with different enzymes and combining mechanical treatment separation. The treatment effects of different enzymes, the performance of different types of TCNF and the influence of different types of TCNF on the performance of tobacco sheet base are compared.

[0004] The present invention provides a new method for the efficient separation of TCNF from tobacco stem pulp, which will further promote the sustainable development and utilization of waste tobacco stems in the tobacco industry. Summary of the invention

[0005] In view of this, the present invention provides a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for preparing tobacco sheets using tobacco-based cellulose nanofibrils comprises the following steps:

[0008] Step 1: taking tobacco stem pulp and placing it in a conical flask, adding biological enzymes into the tobacco stem pulp for pretreatment, and after the pretreatment, performing inactivation treatment and removing residual enzyme liquid therein;

[0009] Step 2: The tobacco stem pulp is beaten by a PFI refiner and subjected to high pressure homogenization to obtain tobacco-based cellulose nanofibrils;

[0010] Step 3: Select wood pulp and compound it with mechanical pulp, add lignin rosin sizing agent emulsion, tobacco pulp, PCC and guar gum, and add tobacco-based cellulose nanofibrils to the above pulp, and make sheets on a rapid paper former to obtain tobacco sheets.

[0011] Preferably, in step 1, the amount of tobacco stem pulp added is 50 g, and the volume of the conical flask is 2 L.

[0012] Preferably, in step 1, the biological enzyme is cellulase, cellulase or ferulic acid esterase complex enzyme, and the concentration of the biological enzyme is 10 to 50 U / mL.

[0013] Preferably, in step 1, the amount of biological enzyme added is 0.1% to 0.5%, and the concentration of tobacco stem pulp is 1% to 5%.

[0014] Preferably, in step 1, the treatment time is 1 to 4 hours; the treatment temperature is 40 to 60° C.; and the treatment pH is 6 to 8.

[0015] Preferably, in step 2, the high-pressure homogenization treatment time is 10 to 30 minutes, and the high-pressure homogenization treatment temperature is 6°C.

[0016] Preferably, in step 2, the high-pressure homogenization treatment method is: firstly stabilize the pulp suspension at a pressure of 600 bar, and then gradually increase the pressure to 1200 bar.

[0017] Preferably, in step 3, the beating degree of the wood pulp is 30°SR, and the wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, wherein the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1.

[0018] Preferably, in step 3, the mass concentration of tobacco-based cellulose nanofibrils is 0-5%, the mass percentage of PCC is 15wt%, and the mass percentage of guar gum is 0.18wt%.

[0019] Preferably, in step 3, the basis weight of the tobacco sheet base is 50 to 70 g / m2.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] (1) The ferulic acid esterase used in the present invention can improve the accessibility of tobacco stem pulp cellulose, thereby improving the efficiency of cellulase hydrolysis;

[0022] (2) The enzymatic mechanical preparation of nanocellulose in the present invention is simple in preparation process, the reaction conditions are mild and controllable, easy to operate, suitable for large-scale production, and has broad application prospects;

[0023] (3) The present invention provides a new idea for the resource utilization of tobacco stems. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 TEM images of tobacco-based cellulose nanofibrils prepared in Examples 1 and 2 and Comparative Examples 1 and 2 of a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils of the present invention;

[0025] Figure 2 A comparison diagram of particle sizes of different tobacco-based cellulose nanofibrils in a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils of the present invention;

[0026] Figure 3 This is a comparison diagram of the Zeta potential of different tobacco-based cellulose nanofibrils in a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils of the present invention;

[0027] Figure 4 This is a comparison chart of the sheet base tensile index of Examples 1 and 2 and Comparative Examples 1 and 2 of a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils of the present invention;

[0028] Figure 5 This is a comparison chart of the sheet base bursting index of Examples 1 and 2 and Comparative Examples 1 and 2 of a method for preparing tobacco sheets using tobacco-based cellulose nanofibrils of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention discloses a method for preparing tobacco sheets by using tobacco-based cellulose nanofibrils, comprising the following steps:

[0031] Step 1: 50 g of tobacco stem pulp is placed in a 2L conical flask, and a biological enzyme with a concentration of 10-50 U / mL is added to the tobacco stem pulp with a concentration of 1%-5% at a dosage of 0.1%-0.5%, and the treatment time is 1-4 hours; the treatment temperature is 40-60° C.; the treatment pH is 6-8; after the pretreatment is completed, an inactivation treatment is performed and the residual enzyme solution is removed;

[0032] Step 2: The tobacco stem pulp is subjected to a PFI pulping machine and high-pressure homogenization treatment to obtain tobacco-based cellulose nanofibrils. The high-pressure homogenization treatment time is 10 to 30 minutes, the high-pressure homogenization treatment temperature is 6° C. The high-pressure homogenization treatment method is: first, the pulp suspension is stabilized under a pressure of 600 bar, and then the pressure is gradually increased to 1200 bar;

[0033] Step 3: Select wood pulp with a beating degree of 30°SR and compound it with mechanical pulp, add lignin rosin sizing agent emulsion, tobacco pulp, 15wt% PCC and 0.18wt% guar gum, and add tobacco-based cellulose nanofibrils with a mass concentration of 0-5% to the above pulp, and make sheets on a rapid paper sheet former to obtain tobacco sheets.

[0034] Wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, wherein the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1.

[0035] The basis weight of the tobacco sheet base is 50 to 70 g / m2.

[0036] Example 1

[0037] Step 1: 50 g of tobacco stem pulp was placed in a 2 L conical flask, and reacted at a constant speed (300 rpm) for 3 h under the conditions of 40 U / mL of cellulase, pH 7.0, temperature 50° C. and concentration 5 wt%. At the end of the pretreatment, an inactivation treatment was performed and the residual enzyme solution was removed;

[0038] Step 2: After the pretreated tobacco stem pulp is cut through a PFI mill, the pulp is treated with a high-pressure homogenizer at 6° C. (concentration is 1.0 wt%); the pulp suspension is first stabilized at a relatively low pressure of 600 bar, and then gradually pressurized to 1200 bar, and samples are collected after 30 cycles;

[0039] Step 3: Select softwood with a beating degree of 30°SR and compound it with mechanical pulp at a mass ratio of 1:2; adjust the pulp pH to 5.5 with aluminum sulfate, add lignin rosin sizing agent emulsion, tobacco pulp, 15wt% PCC and 0.18wt% guar gum, and add tobacco-based cellulose nanofibrils with a mass concentration of 0-5% to the above pulp, and make sheets on a rapid paper former to obtain tobacco sheets. The basis weight of the liquid packaging paperboard base paper is 160g / ㎡.

[0040] The wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, and the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1; the freeness of tobacco pulp and wood pulp is 600mLCSF and 500mLCSF respectively; the tobacco sheet base (RTS-25 / 0) prepared by 25% wood pulp, 75% tobacco pulp, 15wt% PCC and 0.18wt% guar gum is used as the control group. The tobacco sheet base (RTS-18 / 0) prepared by adding 15wt% PCC and 0.18wt% guar gum filler after mixing tobacco pulp and 18wt% wood pulp is used as the experimental control group. On the basis of the experimental control group, a certain amount of TCNF is added to dilute to a concentration of 0.55wt%, and the pulp is stirred at a speed of 500rpm for 8min. Then, a tobacco sheet base material with a weight of about 60g / m2 is copied using a fast paper sheet former.

[0041] Example 2

[0042] Step 1: 50 g of tobacco stem pulp was placed in a 2 L conical flask, and reacted at a constant speed (300 rpm) for 3 h under the conditions of 20 U / mL cellulase, 10 U / mL ferulic acid esterase, pH 7.0, temperature 50° C. and concentration 5 wt%. At the end of the pretreatment, an inactivation treatment was performed and the residual enzyme solution was removed;

[0043] Step 2: After the pretreated tobacco stem pulp is cut through a PFI mill, the pulp is treated with a high-pressure homogenizer at 6° C. (concentration is 1.0 wt%); the pulp suspension is first stabilized at a relatively low pressure of 600 bar, and then gradually pressurized to 1200 bar, and samples are collected after 30 cycles;

[0044] Step 3: Select 30°SR softwood, mix it with mechanical pulp at a mass ratio of 1:2, adjust the pulp pH to 5.5 with aluminum sulfate, add lignin rosin sizing agent emulsion, tobacco pulp, 15wt% PCC and 0.18wt% guar gum, and add 0-5% tobacco-based cellulose nanofibrils to the pulp, and make a sheet on a rapid paper former to obtain tobacco sheets. The basis weight of the liquid packaging paperboard is 160g / ㎡.

[0045] The wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, and the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1. The freeness of tobacco pulp and wood pulp is 600mLCSF and 500mLCSF respectively. A tobacco sheet base (RTS-25 / 0) prepared by 25% wood pulp, 75% tobacco pulp, 15wt% PCC and 0.18wt% guar gum was used as a control group. After the tobacco pulp and 18wt% wood pulp were mixed, a tobacco sheet base (RTS-18 / 0) prepared by adding 15wt% PCC and 0.18wt% guar gum filler was used as an experimental control group. On the basis of the experimental control group, a certain amount of TCNF was added to dilute to a concentration of 0.55wt%, and the pulp was stirred at a speed of 500rpm for 8min. Then, a tobacco sheet base material with a weight of about 60g / ㎡ was copied using a fast paper sheet former.

[0046] like Figure 1 and 2 It can be seen that the diameter of TCNF in Example 2 is smaller and the distribution range is narrower, and its average diameter is lower than that of Comparative Examples 1 and 2. Figure 3 As shown in the Zeta potential diagram of different TCNFs, the absolute values ​​of Zeta potential in Examples 1 and 2 are higher. This is because tobacco stem fibers have many negatively charged functional groups. After enzymatic hydrolysis and homogenization, a large number of polar hydroxyl groups are exposed on the surface of TCNF, making Examples 1 and 2 more negatively charged. Therefore, both have higher stability and better dispersibility, which can meet the requirements of mechanical properties of tobacco sheets.

[0047] The strength index of the film base is as follows Figure 4 and Figure 5 As shown. The sheet base strength in Examples 1 and 2 is better than that in Comparative Examples 1 and 2. When the TCNF addition amount in Example 2 is 0.5%, the tensile and bursting indices of the sheet base are 15.383N·m / g and 0.692kPa·㎡ / g, respectively, which are similar to the data of the control group (RTS-25 / 0). Therefore, adding 0.5wt% TCNF can replace 7wt% of wood pulp (from 25wt% to 18wt%), while having little effect on the strength performance of the tobacco sheet base. By adding a small amount of CNF to reduce the amount of wood pulp added in the tobacco sheet base, the flavor of the tobacco sheet base can be greatly improved, thereby improving the smoking quality of the tobacco sheet.

[0048] In summary, the present invention discloses a method for preparing tobacco-based cellulose nanofibrils. The prepared tobacco-based cellulose nanofibrils not only have excellent size uniformity and dispersibility, but also have great potential to replace wood pulp to improve the performance of tobacco sheet base. The preparation process is green and efficient, and can be applied to papermaking tobacco sheets.

[0049] Comparative Example 1 (blank control)

[0050] Step 1: Take 50g of tobacco stem pulp and place it in a 2L conical flask, and react at a constant speed (300rpm) for 3h under the conditions of pH 7.0, temperature 50℃ and concentration 5wt%. After the pretreated tobacco stem pulp is cut by PFI mill, the pulp is treated with a high-pressure homogenizer at 6℃ (concentration 1.0wt%); first stabilize the paper pulp suspension under a relatively low pressure (600bar), then gradually pressurize to 1200bar, and collect samples after 30 cycles;

[0051] Step 2: Select softwood with a beating degree of 30°SR, mix it with mechanical pulp at a mass ratio of 1:2, adjust the pulp pH to 5.5 with aluminum sulfate, add lignin rosin sizing agent emulsion, tobacco pulp, 15wt% PCC and 0.18wt% guar gum, and add tobacco-based cellulose nanofibrils with a mass concentration of 0-5% to the above pulp, and make sheets on a rapid paper former to obtain tobacco sheets. The basis weight of the liquid packaging paperboard base paper is 160g / ㎡.

[0052] The wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, and the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1; the freeness of tobacco pulp and wood pulp is 600mLCSF and 500mLCSF respectively. The tobacco sheet base (RTS-25 / 0) prepared by 25% wood pulp, 75% tobacco pulp, 15wt% PCC and 0.18wt% guar gum was used as the control group. The tobacco sheet base (RTS-18 / 0) prepared by adding 15wt% PCC and 0.18wt% guar gum filler after mixing tobacco pulp and 18wt% wood pulp was used as the experimental control group. On the basis of the experimental control group, a certain amount of TCNF was added to dilute to a concentration of 0.55wt%, and the pulp was stirred at a speed of 500rpm for 8min. Then, a tobacco sheet base material with a weight of about 60g / ㎡ was copied using a fast paper sheet former.

[0053] Comparative Example 2 (Tempo oxidation treatment group)

[0054] Step 1: Add tobacco stem pulp to deionized water, and then add 1.6wt% TEMPO and 10wt% NaBr, with a solid-liquid ratio of 1:100 (g / mL). Add NaClO solution (20mmol / g) at 25°C for TEMPO oxidation reaction. Continuously add 0.5mol / LNaOH solution to the reaction solution to control its pH value at 10.5. After the reaction is completed, add ethanol to terminate the reaction, wash with deionized water, and name the obtained tobacco stem pulp TCT. Then, the obtained tobacco stem pulp is subjected to high-pressure homogenization with an equipment pressure of 650bar, and finally the obtained TCNF sample is stored at 4°C.

[0055] Step 2: Select softwood with a beating degree of 30°SR and compound it with mechanical pulp at a mass ratio of 1:2. Use aluminum sulfate to adjust the pulp pH to 5.5, add lignin rosin sizing agent emulsion, tobacco pulp, 15wt% PCC and 0.18wt% guar gum, and add tobacco-based cellulose nanofibrils with a mass concentration of 0-5% to the above pulp, and make sheets on a rapid paper former to obtain tobacco sheets. The basis weight of liquid packaging board base paper is 160g / ㎡.

[0056] The wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, and the ratio of coniferous wood pulp to broadleaf wood pulp is 10:1; the freeness of tobacco pulp and wood pulp is 600mLCSF and 500mLCSF respectively. The tobacco sheet base (RTS-25 / 0) prepared by 25% wood pulp, 75% tobacco pulp, 15wt% PCC and 0.18wt% guar gum was used as the control group. The tobacco sheet base (RTS-18 / 0) prepared by adding 15wt% PCC and 0.18wt% guar gum filler after mixing tobacco pulp and 18wt% wood pulp was used as the experimental control group. On the basis of the experimental control group, a certain amount of TCNF was added to dilute to a concentration of 0.55wt%, and the pulp was stirred at a speed of 500rpm for 8min. Then, a tobacco sheet base material with a weight of about 60g / ㎡ was copied using a fast paper sheet former.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing tobacco sheets using tobacco-based cellulose nanofibrils, characterized in that: The steps include: Step 1: taking tobacco stem pulp and placing it in a conical flask, adding biological enzymes into the tobacco stem pulp for pretreatment, and after the pretreatment, performing inactivation treatment and removing residual enzyme liquid therein; Step 2: The tobacco stem pulp is beaten by a PFI refiner and subjected to high pressure homogenization to obtain tobacco-based cellulose nanofibrils; Step 3: Select wood pulp and compound it with mechanical pulp, add lignin rosin sizing agent emulsion, tobacco pulp, PCC and guar gum, and add tobacco-based cellulose nanofibrils to the above pulp, and make sheets on a rapid paper former to obtain tobacco sheets.

2. A method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 1, the amount of tobacco stem pulp added is 50 g, and the volume of the conical flask is 2 L.

3. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 1, the biological enzyme is cellulase, cellulase or ferulic acid esterase complex enzyme, and the concentration of the biological enzyme is 10-50 U / mL.

4. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 1, the amount of biological enzyme added is 0.1% to 0.5%, and the concentration of tobacco stem pulp is 1% to 5%.

5. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 1, the treatment time is 1 to 4 hours; the treatment temperature is 40 to 60° C.; and the treatment pH is 6 to 8.

6. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 2, the high pressure homogenization treatment time is 10 to 30 minutes, and the high pressure homogenization treatment temperature is 6°C.

7. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In step 2, the high-pressure homogenization treatment method is: first, the pulp suspension is stabilized under a pressure of 600 bar, and then the pressure is gradually increased to 1200 bar.

8. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In the step 3, the beating degree of the wood pulp is 30°SR, and the wood pulp is composed of coniferous wood pulp and broadleaf wood pulp fibers, wherein the ratio of coniferous wood pulp to broadleaf wood pulp is 10:

1.

9. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In step 3, the mass concentration of tobacco-based cellulose nanofibrils is 0-5%, the mass percentage of PCC is 15wt%, and the mass percentage of guar gum is 0.18wt%.

10. The method for preparing tobacco sheets using tobacco-based cellulose nanofibrils according to claim 1, characterized in that: In step 3, the basis weight of the tobacco sheet base is 50 to 70 g / m2.

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