A polyamide / cellulose acetate multi-stage fiber composite tobacco film, its preparation method and application

Abstract

The present invention relates to a polyamide / cellulose acetate multi-stage fiber composite tobacco film, a preparation method thereof, and an application. The present invention uses polyamide 6 and cellulose acetate as raw materials and prepares a composite tobacco film containing multi-stage sized fibers by means of electrospinning technology. The multi-stage fiber composite film prepared by the present invention has the characteristics of small fiber diameter, multi-stage structure, and high adsorption efficiency. The multi-stage structure can directionally and efficiently adsorb solid particulate matters and toxic and harmful components in indoor cigarette smoke of different sizes, improves the filtering effect, retains a certain cigarette taste, and can also be biodegradable, being green and environmentally friendly. The present invention has the advantages of easily available raw materials, adjustable size, suitability for industrial production, etc., and has good application prospects in flue gas filtration.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly to a polyamide / cellulose acetate multi-stage composite cigarette film and a preparation method thereof. Background Art

[0002] The nano-composite cigarette film can filter and adsorb nicotine, tar and other toxic and carcinogenic substances in the flue gas. A cigarette filter film and a filter tip with excellent filtering performance can greatly reduce the harmful components in the flue gas and reduce the incidence of various respiratory diseases. Therefore, it has a wide application prospect in cigarette filter tips, air purification devices in smoking rooms, and special masks for women and infants.

[0003] For raw materials, the most common raw materials used in cigarette filter tips with the largest market share in the domestic market at present are cellulose acetate filter tips and polypropylene tow filter tips. Although cellulose acetate has the advantages of being non-toxic, odorless, having moderate mechanical strength, being easy to solidify, good thermal stability, small suction resistance, and remarkable filtering effect, its price is relatively high, which is 3-8 times that of ordinary fibers. The high production cost limits its application range. The characteristics of polypropylene fiber are low price, excellent performance, stable chemical properties, and relatively easy forming and processing. However, since the side group of polypropylene in this raw material is a non-polar group, its adsorption and interception performance for polar substances (the source of spicy taste) in the flue gas is poor, and its filtering ability for nicotine and tar is relatively low, which also hinders its further development and application.

[0004] Structurally, the diameter of the fibers in the flue gas filtering material is an important factor determining the filtering effect. For cigarette filtering requirements, the finer the fibers, the higher the filtering efficiency of the flue gas and the better the filtering performance. At present, the effective filtering layer in the existing flue gas filtering products on the market is mostly a single-layer structure. The fibers in the filtering layer are usually prepared by air jet or vertical jet, and the diameter is usually 7-25 μm. The harmful substances in the flue gas are adsorbed and intercepted through physical principles (separating small tar droplets from the smoke and adsorbing them on the fibers), and the removal rate of nicotine, tar and particulate matter is <85%; there are certain deficiencies in the filtering effect for different-sized particles and harmful substances with different components in the flue gas. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a polyamide / cellulose acetate multi-stage fiber composite cigarette film in view of the above-mentioned deficiencies of the prior art. The composite cigarette film has the characteristics of small fiber diameter, multi-stage structure, and high adsorption efficiency. It uses a nano-level multi-stage structure to directionally and efficiently adsorb solid particles and toxic and harmful components in indoor cigarette smoke of different sizes, retains a certain cigarette taste, and can also be biodegradable and environmentally friendly.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0007] A polyamide / cellulose acetate multi-stage fiber composite tobacco film, comprising a substrate layer and a filter layer; the substrate layer is a polyamide nanofiber membrane with a fiber diameter of 30nm - 220nm and a thickness of 2 - 20μm; the filter layer is a cellulose acetate film with a fiber diameter of 250nm - 1000nm and a thickness of 10 - 30μm; the total thickness of the composite tobacco film is not more than 50μm.

[0008] According to the above solution, the polyamide nanofiber membrane is prepared by electrospinning using polyamide as the raw material. Among them, polyamide (PA) includes one or several of PA6, PA66, PA11, PA12, PA46, PA610, PA612, PAl010, etc.

[0009] According to the above solution, the cellulose acetate film is prepared by electrospinning using cellulose acetate as the raw material.

[0010] The preparation method of the above polyamide / cellulose acetate multi-stage fiber composite tobacco film mainly includes the following steps:

[0011] (1) Using formic acid as the solvent, the raw material polyamide is configured into a polyamide spinning solution with a mass concentration of 10% - 20%.

[0012] (2) Electrospinning the polyamide spinning solution described in step (1) under suitable conditions, and electrospinning on aluminum foil to obtain a polyamide nanofiber membrane with uniform size, a thickness of 2 - 20μm, and a fiber diameter of 30nm - 220nm.

[0013] (3) Using cellulose acetate and a solvent to configure a cellulose acetate spinning solution with a mass concentration of 10% - 18%.

[0014] (4) Electrospinning the cellulose acetate spinning solution described in step (3) on the surface of the polyamide nanofiber film obtained in step (2) to form a cellulose acetate nanofiber membrane with a fiber diameter of 370nm - 1000nm and a thickness of 10 - 30μm, that is, obtaining the polyamide / cellulose acetate multi-stage fiber composite tobacco film.

[0015] According to the above solution, in steps (1) and (3), the spinning solution is configured by stirring at room temperature and standing until the spinning solution is clear and transparent without bubbles. Before use, the polyamide is dried.

[0016] According to the above solution, in step (2), the temperature of the electrospinning environment is 60°C, the humidity is lower than 30%, the concentration of the spinning solution is 10 - 15wt%, the electrospinning voltage is 10 - 12kV, the receiving distance is 10 - 22cm, the injection speed is 0.05mm / min, and the rotating speed of the roller receiver is 2000r / min.

[0017] According to the above scheme, in step (3), the solvent can be one or a mixture of two of acetone and N,N-dimethylacetamide in any proportion, and the preferred proportion is acetone:N,N-dimethylacetamide = 1:2 (volume ratio).

[0018] According to the above scheme, in step (4), the process parameters of electrospinning are: the voltage is 9 kv - 18 kv, the receiving distance is 10 - 24 cm, the injection speed is 0.1 - 1 mm / min, and the receiving rotation speed is 200 - 500 r / min; the ambient temperature is 50 - 70 °C, and the humidity is below 40%.

[0019] The polyamide / cellulose acetate multi-level fiber composite cigarette film prepared by the above method has a cellulose acetate nanofiber membrane of the filter layer compounded on the surface of the polyamide nanofiber film of the base material layer. The composite film has a good multi-porous network structure, and the fiber diameter is slender and uniform; among them, the fibers of the base material layer are slender and uniform, without beads and bands, with a diameter of 30 nm - 220 nm, and the macroscopic morphology is a network structure with uniform pores; the fibers of the cellulose acetate film of the filter layer do not contain beads and bands, and the diameter is uniform, with a diameter of 250 nm - 1000 nm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] First, the present invention adopts the technology of electrospinning to prepare polyamide fibers and cellulose acetate multi-level fibers of different orders of magnitude in nanometers. Through the compounding of different porous film layers, a hierarchical adsorption multi-porous network structure is formed, which filters harmful substances in flue gas and air in an orderly and efficient manner by physical interception and chemical adsorption. The present invention effectively improves the interception and adsorption performance of particulate matter with a diameter less than 2.5 μm in cigarette flue gas and air through polyamide fibers at the nanometer size level; and a network structure is formed in the cellulose acetate film layer with uniform size to effectively chemically adsorb nicotine, carbon monoxide, solanesol, etc. in cigarettes and toxic gases in the air. This hierarchical adsorption multi-porous network structure maximally improves the filtering effect on solid particulate matter and harmful substances in flue gas.

[0022] Second, the present invention is a polyamide / cellulose acetate multi-level composite film, which reduces the production cost of pure cellulose acetate cigarette filters and their filtering products, and is suitable for industrial and industrial automation production.

[0023] Third, the polyamide / cellulose acetate multi-level fiber composite cigarette film of the present invention can obtain films with different thicknesses by controlling the spinning time. Therefore, the thickness and proportion of each layer in the composite film are adjustable, and it is suitable for the filtering requirements of different scenarios.

[0024] Fourth, the materials used in the present invention are biodegradable and environmentally friendly, playing a unique role in environmental protection and having the value of sustainable development. Description of the Drawings

[0025] Figure 1 SEM images of the polyamide / cellulose acetate multi-level fiber composite cigarette film before and after adsorbing cigarettes in Example 1 of the present invention;

[0026] Figure 2 Thermal analysis diagram of the polyamide / cellulose acetate multi-level fiber composite cigarette film in Example 1 of the present invention;

[0027] Figure 3 Thermal analysis diagram of the polyamide / cellulose acetate multi-level fiber composite cigarette film in Example 1 of the present invention. Detailed Description of the Invention

[0028] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0029] Example 1

[0030] A polyamide / cellulose acetate multi-level fiber composite cigarette film, comprising a base material layer and a filter layer; the base material layer is a polyamide 6 nanofiber membrane, the base material fibers are slender and uniform without beads, and the macroscopic morphology is a reticular structure with uniform pores, the fiber diameter is 60nm - 80nm, and the thickness is about 10μm; the filter layer is a cellulose acetate nanofiber film, the fiber diameter is 300nm - 450nm, the thickness is about 20μm, without beads and ribbons, and the diameters are uniform; the total thickness of the composite cigarette film is about 30μm.

[0031] The preparation method of the above polyamide / cellulose acetate multi-level fiber composite cigarette film is as follows:

[0032] (1) Place polyamide 6 (PA6) in a drying oven and dry it for 4 hours. Weigh polyamide 6 and formic acid with a high-precision electronic balance to prepare a spinning solution with a mass concentration of 13%. Carry out magnetic stirring at room temperature for 2 hours. When the solution is clear and transparent without bubbles, carry out electrospinning on aluminum foil to obtain a polyamide 6 nanofiber membrane with a thickness of about 10μm and a fiber diameter of 60nm - 80nm; among them, the spinning parameters are: the spinning voltage is 12kV, the receiving method is roller receiving, the roller receiving speed is 2000r / min, an injection needle with an inner diameter of 20μm is used, the distance between the needle and the roller is 12cm, the injection speed is set at 0.05mm / min, the temperature is 60°C, and the humidity is 25%.

[0033] (2) Acetone was selected as the solvent to prepare a cellulose acetate spinning solution with a mass fraction of 12%. Electrospinning of a cellulose acetate nanofiber film was carried out on the polyamide nanofiber film prepared above. In an environment of 60 °C and a humidity below 20%, the spinning parameters were set as follows: the pushing speed was 0.6 mm / min, the applied voltage was 12 kV, the receiving method was roller receiving, the receiving speed was 400 r / min, an injection needle with an inner diameter of 20 μm was used, and spinning was carried out under the condition that the receiving distance was 20 cm. The fiber diameter was 300 nm - 450 nm, and a PA6 / cellulose acetate multi-stage fiber composite tobacco film (i.e., PA6 / cellulose acetate composite film) was prepared, with a thickness of about 30 μm.

[0034] To fully understand the structure and properties of the film material, a smoke adsorption test was carried out in a closed environment. All the smoke after a cigarette was burned out was passed through the composite film prepared in this example under negative pressure. SEM, FTIR, XRD and other tests were carried out on the film samples before and after adsorption respectively, and the results are as follows Figures 1-3 shown.

[0035] Figure 1 The microscopic morphology of the prepared PA6 / cellulose acetate composite film before (left figure) and after (right figure) adsorbing cigarettes. It can be seen from the left figure that before adsorption, the fibers in the composite film are straight and slender, and the network interlaces to form clear pores.

[0036] After the PA6 / cellulose acetate composite film adsorbs cigarettes, as shown in Figure 1 the right figure in the middle, a large amount of harmful substances in the cigarettes are adsorbed in the composite film. These aerosols and particulate matters in the cigarettes are deposited at the fiber pores and intersections, forming large dark areas and adhering to the fiber surface; and the gaps formed between the fibers are significantly reduced, indicating that the network structure of the composite film increases the adsorption area. Through Figure 1 the left-right comparison shows that the PA6 / cellulose acetate composite film can effectively capture harmful substances in cigarettes.

[0037] Figure 2 The thermogravimetric curves of the PA6 / cellulose acetate composite film before and after adsorbing cigarettes. By placing the composite film in a differential scanning calorimeter for thermal analysis (without removing the aluminum foil at the bottom of the film), the temperature was set at 600 °C and the heating rate was 10 °C / min to obtain the TG / DTG curves of the composite film. From Figure 2It can be seen that when the cut-off temperature rises to 258 °C, the weight loss of the PA6 / cellulose acetate composite film before adsorption is 9.21%, which is caused by the decomposition of the first component polyamide 6 in the PA6 / cellulose acetate composite film; when the temperature continues to rise to 304 °C, the other component cellulose acetate in the composite film begins to decompose, and the pyrolysis rate reaches the fastest at 359 °C; when a cigarette burns, the highest temperature at the center of the combustion cone is 700 °C, the temperature at the edge of the burning paper is only about 200 °C, and the temperature at the smoke filter is much lower than 200 °C. Therefore, the decomposition temperature of the PA6 / cellulose acetate composite film meets the cigarette filtration temperature requirements. From Figure 2 It can be known that the weight loss of the composite film before adsorbing cigarettes is 9.2% before 258 °C; while the weight loss of the composite film after adsorbing cigarettes is about 10.95%, which is 1.75% more than the weight loss of the film before adsorbing cigarettes at the same temperature. It can be analyzed that this part is the weight of the adsorbed harmful substances. This shows that the PA6 / cellulose acetate composite film effectively adsorbs the harmful substances in cigarettes, and the mass ratio of the adsorbed harmful substances accounts for 1.75% of the total mass of the film.

[0038] Figure 3 It is the TG-MS curve obtained after the PA6 / cellulose acetate composite film adsorbs the harmful substances in cigarettes. From Figure 3 It can be known that the composite film can adsorb a variety of harmful substances in cigarettes, and their relative molecular masses are 78, 92, 106, 104, 44, 28, 150, 100, 194, 256, 131, 117, 167, 82, 96, and the corresponding substances are benzene, toluene, xylene, styrene, carbon dioxide, carbon monoxide, nitrosodimethylamine, nitrosopyrrolidine, solanesol, palmitic acid, β-methylvaleric acid, indole, carbazole, 2-methylfuran, 2,5-dimethylfuran. This shows that the PA6 / cellulose acetate composite film can effectively adsorb the above harmful substances.

[0039] Example 2

[0040] A polyamide / cellulose acetate multi-stage composite tobacco film, comprising a substrate layer and a filter layer; the substrate layer is a polyamide 66 nanofiber film, the substrate fibers are slender and uniform without beads and ribbons, the macroscopic morphology is a reticular structure with uniform pores, the fiber diameter is between 65 nm and 85 nm, and the thickness is about 10 μm; the filter layer is a cellulose acetate film, the fiber diameter is between 300 nm and 500 nm, the thickness is about 20 μm, without beads and ribbons, and the diameter is uniform; the total thickness of the composite tobacco film is about 30 μm.

[0041] The preparation method of the above polyamide / cellulose acetate multi-stage composite tobacco film is as follows:

[0042] (1) Place polyamide 66 in a drying oven and dry it for 4 hours. Weigh polyamide 66 and formic acid with a high-precision electronic balance to prepare a spinning solution with a mass concentration of 13%. Carry out magnetic stirring at room temperature for 2 hours. When the solution is clear, transparent and free of bubbles, carry out electrospinning on aluminum foil to obtain a polyamide 66 nanofiber membrane with a thickness of about 10 μm. Among them, the spinning parameters are: spinning voltage is 12 kV, the receiving method is roller receiving, the roller receiving speed is 2000 r / min, an injection needle with an inner diameter of 20 μm is used, the distance between the needle and the roller is 12 cm, the injection speed is set at 0.05 mm / min, the temperature is 60 °C, and the humidity is 25%.

[0043] (2) Select acetone as the solvent and prepare a cellulose acetate spinning solution with a mass fraction of 14%. Electrospin cellulose acetate on the previously prepared polyamide 66 nanofiber film. Under the environment of 60 °C and humidity below 15%, set the spinning parameters as: injection speed is 0.7 mm / min, applied voltage is 12 kV, the receiving method is roller receiving, the receiving speed is 450 r / min, an injection needle with an inner diameter of 20 μm is used, and spin at the condition of a receiving distance of 18 cm to prepare a polyamide 66 / cellulose acetate multi-stage composite tobacco film with a thickness of about 30 μm.

[0044] Example 3

[0045] A preparation method of a polyamide / cellulose acetate multi-stage composite tobacco film is as follows:

[0046] (1) Place polyamide 11 in a drying oven and dry it for 4 hours. Weigh polyamide 11 and formic acid with a high-precision electronic balance to prepare a spinning solution with a mass concentration of 15%. Carry out magnetic stirring at room temperature for 2 hours. When the solution is clear, transparent and free of bubbles, carry out electrospinning on aluminum foil to obtain a polyamide 11 nanofiber membrane. Among them, the spinning parameters are: spinning voltage is 15 kV, the receiving method is roller receiving, the roller receiving speed is 2000 r / min, an injection needle with an inner diameter of 20 μm is used, the distance between the needle and the roller is 15 cm, the injection speed is set at 0.06 mm / min, the temperature is 60 °C, and the humidity is 25%.

[0047] (2) Select a mixture of acetone and N,N-dimethylacetamide in a volume ratio of 1:2 as the solvent and prepare a cellulose acetate spinning solution with a mass fraction of 12%. Electrospin cellulose acetate on the previously prepared polyamide 66 nanofiber film. Under the environment of 60 °C and humidity below 20%, set the spinning parameters as: injection speed is 0.6 mm / min, applied voltage is 15 kV, the receiving method is roller receiving, the receiving speed is 300 r / min, an injection needle with an inner diameter of 20 μm is used, and spin at the condition of a receiving distance of 17 cm to prepare a polyamide 11 / cellulose acetate multi-stage composite tobacco film.

[0048] Example 4

[0049] A method for preparing a polyamide / cellulose acetate multi-stage composite tobacco film, the specific steps are as follows:

[0050] (1) Place polyamide 12 in a drying oven and dry it for 4 hours. Weigh polyamide 12 and formic acid with a high-precision electronic balance to prepare a spinning solution with a mass concentration of 13%. Carry out magnetic stirring at room temperature for 2 hours. When the solution is clear and transparent without bubbles, carry out electrospinning on aluminum foil to obtain a polyamide 12 nanofiber membrane; among them, the spinning parameters are: the spinning voltage is 12 kV, the receiving method is roller receiving, the roller receiving speed is 2000 r / min, an injection needle with an inner diameter of 20 μm is used, the distance between the needle and the roller is 12 cm, the injection speed is set at 0.05 mm / min, the temperature is 60 °C, and the humidity is 25%.

[0051] (2) Select acetone as the solvent and prepare a cellulose acetate spinning solution with a mass fraction of 12%. Electrospin cellulose acetate on the above-prepared polyamide 12 nanofiber film. Under the environment of 60 °C and humidity below 20%, set the spinning parameters as: the injection speed is 0.6 mm / min, the applied voltage is 12 kV, the receiving method is roller receiving, the receiving speed is 350 r / min, an injection needle with an inner diameter of 20 μm is used, and spin at a receiving distance of 21 cm to prepare a polyamide / cellulose acetate multi-stage composite tobacco film.

[0052] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and transformations can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A polyamide / cellulose acetate multi-stage fiber composite tobacco film, characterized in that It includes a substrate layer and a filter layer, with a total thickness not greater than 50 μm; the substrate layer is a polyamide nanofiber membrane with a thickness of 2 - 20 μm, and the filter layer is a cellulose acetate film with a thickness of 10 - 30 μm. The preparation method of the polyamide / cellulose acetate multi - layer fiber composite tobacco film includes the following steps: (1) Using formic acid as a solvent, the raw material polyamide is configured into a polyamide spinning solution with a mass concentration of 10% - 20%, and electrospun on aluminum foil to obtain a polyamide nanofiber membrane with uniform size; in this step, the fiber diameter of the electrospinning is in the range of 30 - 220 nm. (2) A cellulose acetate spinning solution with a mass concentration of 10% - 18% is configured with cellulose acetate and a solvent, and electrospun on the surface of the polyamide nanofiber membrane obtained in step (1) to form a cellulose acetate nanofiber membrane. In this step, the fiber diameter of the electrospinning is 250 - 1000 nm, and the polyamide / cellulose acetate multi - layer fiber composite tobacco film is obtained.

2. The polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 1, wherein The polyamide includes one or several of PA6, PA66, PA11, PA12, PA46, PA610, PA612, PAl010.

3. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 1, characterized in that It includes the following steps: (1) Using formic acid as a solvent, the raw material polyamide is configured into a polyamide spinning solution with a mass concentration of 10% - 20%, and electrospun on aluminum foil to obtain a polyamide nanofiber membrane with uniform size; in this step, the fiber diameter of the electrospinning is in the range of 30 - 220 nm. (2) A cellulose acetate spinning solution with a mass concentration of 10% - 18% is configured with cellulose acetate and a solvent, and electrospun on the surface of the polyamide nanofiber membrane obtained in step (1) to form a cellulose acetate nanofiber membrane. In this step, the fiber diameter of the electrospinning is 250 - 1000 nm, and the polyamide / cellulose acetate multi - layer fiber composite tobacco film is obtained.

4. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 3, characterized in that In step (1), the polyamide is dried before use, and then the polyamide spinning solution is configured by stirring at room temperature until the spinning solution is clear and transparent without bubbles.

5. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 3, characterized in that In step (1), the electrospinning environment is at a temperature of 50 - 70 °C, humidity below 30%, electrospinning voltage of 10 - 12 kV, receiving distance of 10 - 22 cm, injection speed of 0.04 - 0.06 mm / min, and drum receiving rotation speed of 1500 - 2500 r / min.

6. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 3, characterized in that In step (2), the solvent is one or a mixture of two of acetone and N,N - dimethylacetamide in any proportion.

7. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 3 or 6, characterized in that In step (2), the solvent is a mixed solvent composed of acetone and N,N - dimethylacetamide in a volume ratio of 1:(1.5 - 2.5).

8. The preparation method of the polyamide / cellulose acetate multi-stage fiber composite tobacco film according to claim 3, characterized in that In step (2), the process parameters of electrospinning are: voltage of 9 kV - 18 kV, receiving distance of 10 - 24 cm, injection speed of 0.1 - 1 mm / min, receiving rotation speed of 200 - 500 r / min; environmental temperature of 50 - 70 °C, humidity below 40%.

9. Application of the composite tobacco film described in claim 1 as a filter material.

10. Application of the composite tobacco film described in claim 1 as a filter material in a cigarette filter tip.

Images