Preparation method of a biodegradable and antibacterial bamboo fiber-based paper straw

Abstract

A preparation method of a biodegradable and antibacterial bamboo fiber-based paper straw, which relates to the preparation method of paper straws. It aims to solve the technical problems of the complex structure and high preparation cost of existing bamboo fiber paper straws. The method is as follows: The fabricated bamboo fiber-based paper is first soaked with a citric acid solution, then soaked with a chitosan quaternary ammonium salt solution, and then rolled into a tube and dried; then it is soaked and treated with an ethanol solution of stearic acid and phytic acid and dried to obtain a biodegradable and antibacterial bamboo fiber-based paper straw. Its contact angle can still reach 90-120° after 30 minutes of contact with water, and the antibacterial rates against Escherichia coli and Staphylococcus aureus reach 100% and 99.63% respectively. The straw is completely degraded under the condition of soil burial for 40 days, is suitable for various beverages such as tea, coffee, milk, and cola, and can be used in the food field.

Description

Technical Field

[0001] The present invention relates to a preparation method of paper straws. Background Art

[0002] Plastic products have been widely used in daily life due to their advantages such as light weight, low cost, durability, and convenient production. However, microplastics generated during the degradation and weathering of plastic products will spread into the food chain and are difficult to degrade, which has a negative impact on the environment and human health. Especially polypropylene plastic straws (PP) as disposable products are difficult to recycle due to their light weight and small volume. It has become an inevitable trend in the industry to replace plastic straws with biomass-based straws.

[0003] Cellulose, as the most abundant green resource on earth, is renewable, biodegradable, and low-cost, making it a potential material for preparing straws. Bamboo is also one of the most important non-wood forest resources, with a wide distribution and a large variety of species. The pulping and papermaking process using bamboo is quite mature. For example, a Chinese patent with the application number CN202221658830.X discloses a paper straw that can be naturally degraded. A separable structure is arranged inside the tube body of the paper straw, and a durable structure is arranged inside the straw tube body. The durable structure includes kraft paper, which is arranged inside the straw tube body. Bamboo fibers are arranged on one side of the kraft paper, and a polylactic acid film is arranged on the other side of the kraft paper. The structure of this paper straw is complex and the preparation cost is high. Summary of the Invention

[0004] The present invention aims to solve the technical problems of the existing bamboo fiber paper straws, such as complex structure and high preparation cost, and provides a preparation method of a biodegradable and antibacterial bamboo fiber-based paper straw. This paper straw has excellent hydrophobic and antibacterial properties.

[0005] The preparation method of the biodegradable and antibacterial bamboo fiber-based paper straw of the present invention is carried out according to the following steps:

[0006] 1. Papermaking of bamboo fiber-based paper;

[0007] 2. Cut the bamboo fiber-based paper into a rectangle, first soak the paper sheet with a citric acid solution with a mass percentage concentration of 10% - 15%, and then soak the paper sheet with a chitosan quaternary ammonium salt solution with a concentration of 10 - 15 g / L; then roll the wetted rectangular wet paper web onto a polytetrafluoroethylene (PTFE) rod, press the edges together, dry at room temperature, and separate from the PTFE rod to obtain a CA / CQAS / BBF straw;

[0008] III. Using absolute ethanol as the solvent, add stearic acid and phytic acid into absolute ethanol according to the mass percentage concentration of stearic acid being 10% - 22% and the mass percentage concentration of phytic acid being 5% - 20%, mix them evenly, and heat to 65 - 70 °C under stirring conditions until the solution becomes clear to obtain a mixed solution; then soak the CA / CQAS / BBF straw obtained in step II in the mixed solution for 10 - 20 minutes, take it out and dry it naturally at room temperature to obtain a biodegradable and antibacterial bamboo fiber-based paper straw, denoted as SA / PA / BBF straw.

[0009] Furthermore, the method for making the bamboo fiber-based paper in step I is carried out according to the following steps:

[0010] (1) First, add the bleached bamboo pulp board into water and soak it for 10 - 12 h, then perform beating treatment to make the slurry concentration 1% - 1.5%; then use a beater to adjust the final beating degree to 30 - 35 °SR. After the beating is completed, perform dehydration treatment to obtain a pulp block.

[0011] (2) According to the basis weight of 80 - 85 g / m 2 Add the pulp block into water, disintegrate it for 10,000 revolutions with a fiber standard disintegrator, filter the slurry through a paper sheet former with a screen mesh of 250 - 300 meshes to obtain a wet paper web; remove the wet paper web from both sides with clean absorbent paper, first place it in a pneumatic paper sheet press and press for 5 - 10 min, and then dry both sides at 100 - 105 °C for 5 - 10 min each with a flat paper sample dryer to obtain the bamboo fiber-based paper.

[0012] Furthermore, the average mass of the rectangular bamboo fiber-based paper in step II is m = 0.2 - 0.3 g.

[0013] Furthermore, the size of the rectangular bamboo fiber-based paper in step II is (3 - 4) cm × (10 - 12) cm.

[0014] The present invention uses bleached bamboo fiber as raw material, prepares paper through papermaking process, then increases the cross-linking effect between fibers through pretreatment with citric acid (CA) and chitosan quaternary ammonium salt (CQAS) solution, then obtains a paper straw through curling, and then soaks the straw in a mixed solution of stearic acid (SA) and phytic acid (PA) to endow the straw with excellent hydrophobic and antibacterial properties. The contact angle of the biodegradable and antibacterial bamboo fiber-based paper straw of the present invention can still reach 90-120° after contacting with water for 30 minutes. The hydrophobic effect of the straw is verified by water absorption rate and contact angle. At the same time, the antibacterial rate against Escherichia coli reaches 100%, and the antibacterial rate against Staphylococcus aureus reaches 99.63%, showing good antibacterial effect. The straw is completely degraded by 100% under the condition of soil burial for 40 days, and is applicable to various beverages such as tea, coffee, milk, cola, etc., showing wide application, and shows good stability at room temperature and in 0°C aqueous solution. At the same time, the preparation method is a green, low-carbon and pollution-free method throughout the process, obtaining a safe and green antibacterial straw. The straw of the present invention is a bamboo fiber-based paper straw with good water stability, biodegradability and antibacterial property, and can be used in the food field. Description of the Drawings

[0015] Figure 1 Comparison diagram of the maximum water contact angles of BBF, CA / CQAS / BBF straws and SA / PA / BBF straws in Example 1;

[0016] Figure 2 SEM diagrams of the surface and cross-section of BBF, CA / CQAS / BBF straws and SA / PA / BBF straws in Example 1;

[0017] Figure 3 Element distribution diagram of the SA / PA / BBF straw prepared in Example 1;

[0018] Figure 4 FTIR spectra of BBF, CA / CQAS / BBF straws, SA / PA / BBF straws prepared in Example 1, CA / CQAS / SA / BBF straws prepared in the comparative example and SA;

[0019] Figure 5 XRD spectra of BBF, CA / CQAS / BBF straws, SA / PA / BBF straws prepared in Example 1, CA / CQAS / SA / BBF straws prepared in the comparative example and SA;

[0020] Figure 6 TGA curves and DTG curves of BBF, CA / CQAS / BBF straws, SA / PA / BBF straws prepared in Example 1, CA / CQAS / SA / BBF straws prepared in Comparative Example 1 and SA;

[0021] Figure 7 Antibacterial evaluation diagrams of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1 against Escherichia coli and Staphylococcus aureus;

[0022] Figure 8 Comparison diagram of dry bending strength of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1;

[0023] Figure 9 Wet bending strength diagram of SA / PA / BBF straws prepared in Example 1;

[0024] Figure 10 Degradation test diagrams of SA / PA / BBF straws, PP straws, PLA straws, and commercial paper straws prepared in Example 1;

[0025] Figure 11 Water stability diagrams of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1 at 25°C;

[0026] Figure 12 Comparison diagram of the applicability of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1 in four beverages;

[0027] Figure 13 Comparison diagram of the applicability of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1;

[0028] Figure 14 Comparison diagram of the water stability of BBF, CA / CQAS / BBF straws, and SA / PA / BBF straws prepared in Example 1 at 0°C;

[0029] Figure 15 Performance radar diagrams of SA / PA / BBF straws, commercial paper straws, and PLA straws prepared in Example 1;

[0030] Figure 16 Contact angle photos of biodegradable and antibacterial bamboo fiber-based paper straws prepared in Examples 2 to 5. Detailed implementation manners

[0031] The beneficial effects of the present invention are verified by the following examples.

[0032] Example 1: The preparation method of the biodegradable and antibacterial bamboo fiber-based paper straw in this example is carried out according to the following steps:

[0033] I. Making bamboo fiber-based paper, and the specific method is carried out according to the following steps:

[0034] (1) First, add the bleached bamboo pulp board into water and soak it for 12 h, then beat it to make the slurry concentration at 1.5%; then use a Valley beater to adjust the final beating degree to 30° SR. After the beating is finished, perform dehydration treatment to obtain pulp blocks.

[0035] (2) According to a basis weight of 80 g / m 2 Add the pulp blocks into water, defibrate them for 10,000 revolutions with a GBJ-A fiber standard defibrator, filter the slurry through a sheet former with a screen mesh of 250 meshes to obtain a wet paper web. Remove the two sides of the wet paper web with clean absorbent paper. First, place it in a PL8-B pneumatic sheet press for pressing for 5 min, and then dry both sides for 5 min each at a temperature of 105 °C through a PL7-C flat paper sample dryer. Peel the bamboo fiber base paper off the absorbent paper and label it as BBF.

[0036] Second, cut the bamboo fiber base paper into rectangles with a size of 3 cm × 10 cm. The average mass of each rectangular paper piece is m = 0.25 g. First, soak the paper pieces with a citric acid solution with a mass percentage concentration of 10%, and then soak them with a chitosan quaternary ammonium salt solution with a concentration of 10 g / L; then roll the wetted rectangular wet paper web onto a polytetrafluoroethylene (PTFE) rod, press the edges tightly together, and dry at room temperature. After separating from the PTFE rod, obtain a CA / CQAS / BBF straw.

[0037] Third, use absolute ethanol as a solvent, add stearic acid and phytic acid into absolute ethanol according to a mass percentage concentration of stearic acid of 13% and a mass percentage concentration of phytic acid of 14%, mix them evenly and heat to 70 °C under stirring conditions until the solution becomes clear to obtain a mixed solution; then soak the CA / CQAS / BBF straw obtained in the second step in the mixed solution for 14 minutes, take it out and dry it naturally at room temperature to obtain a biodegradable and antibacterial bamboo fiber base paper straw, labeled as SA / PA / BBF straw.

[0038] Comparative Example 1: The difference between this comparative example and Example 1 is that the operation in the third step is replaced with the following:

[0039] Third, prepare a stearic acid solution with a mass percentage concentration of 20%; then soak the CA / CQAS / BBF tube obtained in the second step in the stearic acid solution for 14 minutes, take it out and dry it naturally at room temperature to obtain a bamboo fiber base paper straw, labeled as CA / CQAS / SA / BBF straw. Other steps and parameters are the same as those in Example 1.

[0040] Perform a contact angle test on the BBF obtained in the first step of this example, the CA / CQAS / BBF straw obtained in the second step, and the SA / PA / BBF straw obtained in the third step. The contact angles obtained are as Figure 1 shown. From Figure 1It can be seen that the maximum water contact angles of the BBF and CA / CQAS / BBF tubes are 26° and 37° respectively, while the initial contact angle of the SA / PA / BBF straw obtained in Step 3 is up to 134.4°, and the WAC is still 119° after 30 min. Compared with the CA / CQAS / SA / BBF straw, the hydrophobic stability of the straw paper is improved as a whole by the treatment with phytic acid. It is confirmed that the hydrophobic performance is improved by the mixed treatment of phytic acid and stearic acid, and the cations in CQAS crosslink through anion-cation interaction. At the same time, SA enhances the surface roughness of the straw, and its crystalline state increases the repulsive force of water molecules, which plays a crucial role in the hydrophobic effect.

[0041] Figure 2 SEM images of the surface and cross-section of the BBF obtained in Step 1, the CA / CQAS / BBF straw obtained in Step 2, and the SA / PA / BBF straw obtained in Step 3 are shown respectively. Among them, a and d are the SEM images of the surface of BBF, b and e are the SEM images of the surface of CA / CQAS / BBF, c and f are the SEM images of the surface of SA / PA / BBF, g is the SEM image of the cross-section of BBF, h is the SEM image of the cross-section of CA / CQAS / BBF, and i is the SEM image of the cross-section of SA / PA / BBF. It can be seen from a, d, and g that the bleached bamboo fibers (BBF) are interconnected, and there are a large number of pores between the fibers. Water molecules can easily enter the internal structure, resulting in the superhydrophilicity of the straw paper at this time. It can be seen from b, e, and h that for the fibers treated with CA and CQAS, the anions in CA and the cations in CQAS crosslink more tightly through anion-cation interaction, reducing the pores. It can be seen from c, f, and i that in the BBF modified by the mixture of SA and PA, it can be clearly seen that the surface and cross-section of the fibers show a dense structural state. The anions in SA and PA enhance the surface density of the fibers by combining with the cations in CQAS. At the same time, the stearic acid crystals enhance the surface roughness of the fibers by attaching to the surface of the fibers, providing the possibility for the SA / PA / BBF straw to achieve high water resistance and hydrophobicity.

[0042] Figure 3 The element distribution map of SA / PA / BBF obtained in Step 3 of Example 1 is shown. From Figure 3 it can be seen that C, N, O, and P elements are evenly distributed in the SA / PA / BBF straw, with contents of 36%, 6%, 10%, and 7% respectively. It is confirmed that phytic acid has been successfully introduced onto the surface of the straw paper.

[0043] Figure 4 The FTIR spectra of BBF, CA / CQAS / BBF straw, SA / PA / BBF straw, CA / CQAS / SA / BBF straw prepared in Comparative Example 1, and SA in Example 1 are shown. FromFigure 4 It can be seen that for the BBF straw, the peaks at 3321 cm -1 and 2901 cm -1 belong to the vibrations of O-H and C-H respectively. The peaks at 1326 cm -1 and 1023 cm -1 are caused by the bending vibration of O-H and the stretching vibration of C-O respectively. After CA / CQAS treatment, some changes are observed. New peaks appear at 1724 cm -1 , belonging to the stretching vibration of C=O. There are multiple CA molecules and CQAS molecules on the surface of the paper straw to form a dense cross-linked network structure. Some changes are observed after SA and PA treatment. New peaks appear at 1702 cm -1 , 1471 cm -1 and 1380 - 1150 cm -1 respectively, belonging to the stretching vibration of C=O and the bending vibrations of the methyl and methylene groups of SA. The results show that SA and PA are successfully combined with bamboo fibers. In addition, the strong band at 945 cm -1 shows the C polymorphic form of SA, which is consistent with the results of wide-angle X-ray diffraction (WAXD).

[0044] Figure 5 XRD patterns of SA, BBF, CA / CQAS / BBF straw, SA / PA / BBF straw prepared in Example 1 and CA / CQAS / SA / BBF straw prepared in Comparative Example 1. From Figure 5 it can be seen that crystal peaks with different spacing lengths can be seen in the stearic acid crystal. The "long spacing" of stearic acid appears at (7.2°), (11.7°) and (15.5°) on three different diffraction peaks, indicating the thickness and ordered arrangement of stearic acid molecules. At the same time, "short spacing" appears at the diffraction angles of (21.6°) and (23.9°), indicating the lateral stacking order of hydrocarbon chains. The BBF straw, CA / CQAS / BBF straw, and CA / CQAS / SA / BBF straw show characteristic peaks of cellulose I at 16.5° and 22.6°. For the CA / CQAS / SA / BBF straw, the peaks at 7.2°, 11.7°, 21.6°, and 23.9° represent the crystal spacings of SA, indicating that SA exists on the surface in a crystalline state. These values are in good agreement with monoclinic C-type stearic acid.

[0045] Figure 6TGA and DTG curves of the BBF, CA / CQAS / BBF tube, SA / PA / BBF straw prepared in Example 1, and the CA / CQAS / SA / BBF straw prepared in Comparative Example 1, where a is the TGA curve and b is the DTG curve. The thermal stability of the straw is crucial for its normal production and use. From Figure 6 It can be seen that before the temperature rises to 160 °C, the weight loss of the CA / CQAS / BBF straw, CA / CQAS / SA / BBF straw, and SA / PA / BBF straw is slow. And before the temperature rises to 280 °C, the weight loss of BBF is slow, which is attributed to the evaporation of moisture on the surface of the straw paper. As the temperature continues to rise, the rate of weight loss of the sample gradually increases. SA starts to decompose at about 207 °C, CA decomposes at about 176 °C, CQAS decomposes at about 331 °C, PA decomposes at about 260 °C, and the fibers of the uncoated paper decompose at about 348 °C. When the temperature reaches 379 °C, the mass of the sample gradually stabilizes. Compared with the uncoated paper, the residual mass of the modified paper increases while the thermal weight loss rate decreases, which may be related to the changes in fiber size and crystal structure during the modification process. All straws have good thermal stability at temperatures below 100 °C, indicating that the straw can be applied to normal daily use.

[0046] The comparison chart of the antibacterial properties of the BBF straw, SA / PA / BBF straw prepared in Example 1, and the CA / CQAS / SA / BBF straw of Comparative Example 1 using the classic colony counting method is as Figure 7 shown. From Figure 7 It can be seen that the CA / CQAS / SA / BBF straw has poor antibacterial properties against Escherichia coli and Staphylococcus aureus, which are 21.94% and 67.65% respectively. While the SA / PA / BBF straw treated with phytic acid has an antibacterial rate against Escherichia coli that can reach 100%, and the antibacterial rate against Staphylococcus aureus reaches 99.63%. This is because PA contains 6 active phosphate groups, which chelate with divalent cations in lipopolysaccharide, reducing the environmental pH value and causing cell wall damage. The integrity of the bacterial cell wall and cell membrane is damaged, the permeability increases, the cytoplasmic content of the bacteria leaks out, resulting in an increase in the content of alkaline phosphatase and conductivity. PA can not only make the surface of bacteria rough, but also cause rupture, collapse and holes on the cell surface, resulting in the leakage of cell protoplasm.

[0047] The comparison chart of the dry bending strength of the BBF straw, CA / CQAS / BBF straw, and SA / PA / BBF straw prepared in Example 1 is as Figure 8 shown. From Figure 8 It can be seen that with the change of the treatment method, the three straws are completely bent under loads of 110 g, 130 g, and 180 g in the air respectively. It can be seen that the bending resistance of the straws is enhanced after being treated with CA, CQAS, SA, and PA.

[0048] The comparison chart of the load-bearing capacity of the SA / PA / BBF straw prepared in Example 1 in water is as Figure 9 shown. The load-bearing capacity of the BBF straw and the CA / CQAS / BBF straw in water is poor. They soften immediately after being immersed in water and cannot bear any weight. From Figure 9 it can be seen that the SA / PA / BBF straw can carry a weight of 50 g for 2 min in a completely immersed state in water. Because the anions in SA and PA combine with the cations in CQAS, the compactness of the fiber is improved. At the same time, SA adheres to the fiber surface, thereby improving the water stability. At the same time, as shown in Table 1, the mechanical strengths (TS and EB) of the SA / PA / BBF straw still need to be improved.

[0049] Table 1 Comparison of the mechanical properties of different straws

[0050]

[0051] The degradation tests were carried out on the PP straw, PLA straw, commercial paper straw and the SA / PA / BBF straw prepared in Example 1. The PP straw, PLA straw, commercial paper straw and the SA / PA / BBF straw prepared in Example 1 were buried in the same soil environment, and the morphological changes of different straws within 40 days were observed, as Figure 10 shown. From Figure 10 it can be seen that the SA / PA / BBF straw achieved complete degradation within 40 days, and its degradation rate was better than that of the commercial paper straw. In contrast, the PP and PLA straws did not show obvious degradation during the same period, highlighting their poor biodegradability. The SA / PA / BBF straw is expected to replace plastic straws due to its excellent biodegradability and partially solve the problem of white pollution.

[0052] The comparison chart of the hydrophilicity and hydrophobicity of the BBF straw, CA / CQAS / BBF straw and SA / PA / BBF straw prepared in Example 1 at room temperature is as Figure 11 shown. By immersing each straw in a bright blue solution respectively to facilitate the observation of capillary action, the results show that the BBF straw and the CA / CQAS / BBF straw have super hydrophilicity. The bright blue solution reaches the top of the straw within 2 min and 3 min respectively, resulting in phenomena such as the straw swelling, softening and fiber shedding. However, the SA / PA / BBF straw is morphologically stable within 4 h without signs of delamination or edge cracking, and it can still maintain a straight shape after taking the straw out of the solution.

[0053] The figure of immersing the BBF straw, CA / CQAS / BBF straw and SA / PA / BBF straw prepared in Example 1 in tea, coffee, cola and milk respectively to simulate the use scenario is as Figure 12As shown in the figure. The BBF straws only maintained their integrity for 2 minutes, 4 minutes, 1 minute, and 3 minutes in tea, coffee, cola, and milk respectively. The CA / CQAS / BBF straws only maintained their integrity for 3 minutes, 5 minutes, 3 minutes, and 7 minutes in tea, coffee, cola, and milk respectively. The overall maintenance time showed an extended trend, but still could not meet the actual application needs. In contrast, the SA / PA / BBF straws remained stable in shape after being soaked in all beverages for 2 hours, without swelling or bending, showing their superior stability and durability, as Figure 13 shown.

[0054] Test the water stability of the BBF straw, CA / CQAS / BBF straw, and SA / PA / BBF straw prepared in Example 1 at 0°C. Immerse the BBF straw, CA / CQAS / BBF straw, and SA / PA / BBF straw in water at 0°C respectively to evaluate their applicability, as Figure 14 shown. From Figure 14 it can be seen that within 2 minutes and 3 minutes, the BBF straw and CA / CQAS / BBF straw were fully soaked due to capillary action, and the moisture continuously extended to the top of the straw, showing phenomena such as softening and collapse. On the contrary, the SA / PA / BBF straw could still maintain its original shape even after 2 hours, without any signs of delamination or cracking.

[0055] The performance radar chart of the SA / PA / BBF straw, commercial paper straw, and PLA straw prepared in Example 1 is as Figure 15 shown. From Figure 15 it can be seen that the SA / PA / BBF straw was comprehensively compared with two commonly used biodegradable straws (PLA and commercial paper straws) in terms of manufacturing and performance parameters such as cost, biodegradability, wax coverage, taste, hydrophobicity, and large-scale productivity. The cost of the SA / PA / BBF straw was approximately 5 times and 10 times lower than that of the PLA straw and paper straw respectively. In addition, the PLA straw requires specific conditions to achieve complete degradation. The surface of the commercial paper straw is covered with multiple layers of waterproof wax to solve the water stability problem, which not only increases the cost but also limits the speed of large-scale production. In contrast, the SA / PA / BBF straw effectively solves the main disadvantages of PLA and paper straws and has excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, and is promising to be a superior alternative to plastic straws.

[0056] Example 2: The difference between this example and Example 1 is that the concentration of the stearic acid solution in step three is 10%, and the others are the same as in Example 1. The obtained biodegradable and antibacterial bamboo fiber-based paper straw is denoted as SA10 / PA13 / BBF straw.

[0057] Example 3: The difference between this example and Example 1 is that the concentration of the stearic acid solution in Step 3 is 18%, and the others are the same as in Example 1. The obtained biodegradable and antibacterial bamboo fiber-based paper straw is denoted as SA18 / PA13 / BBF straw.

[0058] Example 4: The difference between this example and Example 1 is that the concentration of the phytic acid solution in Step 3 is 10%, and the others are the same as in Example 1. The obtained biodegradable and antibacterial bamboo fiber-based paper straw is denoted as SA14 / PA10 / BBF straw.

[0059] Example 5: The difference between this example and Example 1 is that the concentration of the phytic acid solution in Step 3 is 20%, and the others are the same as in Example 1. The obtained biodegradable and antibacterial bamboo fiber-based paper straw is denoted as SA14 / PA20 / BBF straw.

[0060] The contact angle photos of the biodegradable and antibacterial bamboo fiber-based paper straws prepared in Examples 2 to 5 are as Figure 16 shown, and the specific data are shown in Table 2. It can be seen from Figure 16 Table 2 that the addition of PA improves the hydrophobic stability of the straw as a whole, and the contact angle of the straw paper remains above 90° after 30 minutes, showing good stability.

[0061] Table 2 Contact angles of SA / PA / BBF straws prepared in Examples 2 to 5

[0062] Sample Name of the pipette Contact angle after contacting water for 30 min Example 2 SA10 / PA13 / BBF 95.9° Example 3 SA18 / PA13 / BBF 91° Example 4 SA14 / PA10 / BBF 95.2° Example 5 SA14 / PA20 / BBF 95.6°

[0063] In the present invention, a formed paper is obtained by papermaking with bleached bamboo pulp, and the straw paper is pretreated through the ionic bond interaction between citric acid and chitosan quaternary ammonium salt. Stearic acid (SA) is a saturated fatty acid extracted from animals and plants and can be found in almost all oils and fats. It is a fatty acid with a very wide source. Its unique octadecane structure endows stearic acid with the potential for hydrophobicity. In the present invention, the hydrophobic modification of the straw is achieved by adding stearic acid. Phytic acid (PA) is a non-toxic, renewable, and low-cost natural compound extracted from plants such as soybeans and corn. Due to its special structure with six phosphate groups, it has excellent antibacterial properties. In the present invention, good antibacterial performance is imparted to the straw by adding phytic acid. The straw simultaneously exhibits excellent biodegradability and wide applicability.

Claims

1. A method for preparing a biodegradable, antibacterial bamboo fiber-based paper straw, characterized in that: The method proceeds as follows:

1. Making bamboo fiber-based paper; 2. Cut the bamboo fiber-based paper into rectangles, first soak the paper with a citric acid solution with a mass percentage concentration of 10% to 15%, and then soak the paper with a chitosan quaternary ammonium salt solution with a concentration of 10 to 15 g / L; then roll the wetted rectangular wet paper onto a polytetrafluoroethylene rod, press the edges together, dry at room temperature, and separate from the polytetrafluoroethylene rod to obtain a citric acid / chitosan quaternary ammonium salt / bamboo fiber straw; 3. Using anhydrous ethanol as solvent, add stearic acid and phytic acid to anhydrous ethanol at a mass percentage concentration of 10%-22% for stearic acid and 5%-20% for phytic acid, mix well, and heat to 65-70°C under stirring until the solution is clear to obtain a mixed solution; then soak the citric acid / chitosan quaternary ammonium salt / bamboo fiber straws obtained in step 2 in the mixed solution for 10-20 minutes, take out and dry naturally at room temperature to obtain biodegradable, antibacterial bamboo fiber-based paper straws, recorded as stearic acid / phytic acid / bamboo fiber straws.

2. The method for preparing a biodegradable, antibacterial bamboo fiber-based paper straw according to claim 1, characterized in that: The method for making bamboo fiber base paper described in step 1 is carried out according to the following steps: (1) First, add the bleached bamboo pulp board to water and soak it for 10-12 hours, then beat it to make the pulp concentration between 1% and 1.5%; then use a pulping machine to adjust the final beating degree to 30-35 o SR, after beating, dehydration treatment is carried out to obtain pulp blocks; (2) According to the quantitative 80 ~ 85g / m 2 The pulp mass is added into water, and the pulp is disintegrated by a fiber standard disintegrator for 10,000 revolutions, and the pulp is filtered through a paper sheet former with a filter mesh of 250 to 300 meshes to obtain a wet paper web; Use clean absorbent paper to remove both sides of the wet paper web, first place it in a pneumatic paper press for 5 to 10 minutes, and then pass it through a flat paper sample dryer at a temperature of 100 to 105°C for 5 to 10 minutes on both sides to obtain bamboo fiber-based paper.

3. The method for preparing a biodegradable, antibacterial bamboo fiber-based paper straw according to claim 1 or 2, characterized in that: The size of the rectangular bamboo fiber base paper in step 2 is (3~4) cm × (10~12) cm.

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