Soft multifunctional ginkgo leaf / catkin composite packaging paper and preparation method thereof

Abstract

The invention discloses soft multifunctional ginkgo leaf / catkin composite packaging paper and a preparation method thereof, and belongs to the technical field of packaging paper. Ginkgo leaves are treated by DES to obtain ginkgo leaf cellulose-lignin slurry (GBS), and then the ginkgo leaf cellulose-lignin slurry (GBS) is used as a base material and soft and cheap catkins are used as reinforcing fibers to prepare the soft multifunctional composite packaging paper. The composite packaging paper prepared by the invention has the properties of fluorescence, hydrophobicity, ultraviolet resistance and the like, and is soft, low in cost, biodegradable and wide in application prospect. In addition, the DES used in the method can be continuously recycled, and is suitable for industrial use.

Description

Technical Field

[0001] The invention relates to a soft and multifunctional ginkgo leaf / willow catkin composite wrapping paper and a preparation method thereof, belonging to the technical field of wrapping paper. Background Art

[0002] As people's living standards improve, environmental issues become increasingly prominent, and resource utilization has become a hot topic. Ginkgo biloba leaves are a rich and inexpensive plant material that contains a variety of beneficial ingredients such as polyphenols (about 68.9 mg / g), flavonoids (about 16.6 mg / g), and terpenes (about 4.2 mg / g), but they are mostly burned or fermented as fallen leaves and are not fully utilized (Wu Ping, Yao Fang, Qi Xingpu, et al. Main components and functional activities of all resources of Ginkgo biloba [J]. Food Industry Science and Technology, 2022, 43(9): 447-455. doi:10.13386 / j.issn1002-0306.2021050026.).

[0003] A willow tree can produce 280,000 to 14.85 million catkins a year (FAO. Poplars, willows and people's wellbeing: abstracts of submitted papers [J]. Tigerpaper, 2009, 36 (1): 16-05. DOI: 10.1016 / j.virol.2009.05.018.). Catkin fibers are mainly composed of α-cellulose (about 94.0%), and also contain a small amount of pentose (1.51%), nitrogen-containing substances (0.87%), water-soluble substances (3.30%) and lipids (0.60%) (Liu Liting, Qian Yao, Lv Huijiao, Wu Xiaolong, Huang Chunling. Research and application status of poplar and willow catkin fibers [J]. Printing and dyeing auxiliaries, 2023, 40 (8): 1-5). Because catkin fibers are short, smooth, and non-curly, and the bonding force between fibers is small, they are difficult to spin. They are often prepared as electrode materials for supercapacitors, energy sources, adsorbents, etc., and are used in the field of environmental engineering. They are not common in modern packaging materials.

[0004] By treating ginkgo leaves with a deep eutectic solvent (DES), a ginkgo leaf cellulose-lignin slurry with high viscosity and high solid content can be obtained through the in-situ regeneration of lignin. Chitosan can be added to the slurry to prepare a bio-based composite membrane (for example: CN118599162A), but the prepared membrane is hard and brittle, and the cost of chitosan is relatively high.

[0005] Wrapping paper is a material widely used in commodity packaging. It requires good processing performance, certain mechanical properties, softness, light weight, and in some special occasions, it also needs to have certain waterproof and anti-fouling properties. Summary of the invention

[0006] To solve the above problems, the present invention first uses a low eutectic solvent (DES) to process ginkgo leaves to obtain ginkgo leaf cellulose-lignin slurry (GBS), and then uses ginkgo leaf cellulose-lignin slurry (GBS) as a substrate, and uses soft and cheap catkin fiber as a reinforcing fiber to prepare a soft multifunctional composite wrapping paper. The composite wrapping paper prepared by the present invention has the properties of fluorescence, hydrophobicity, and UV resistance, and is soft, low in cost, and biodegradable, and has broad application prospects. Moreover, the low eutectic solvent (DES) used in the present invention can be continuously reused, which is suitable for industrial use.

[0007] The first object of the present invention is to provide a method for preparing a soft and multifunctional ginkgo leaf / willow catkin composite wrapping paper, comprising the following steps:

[0008] The ginkgo leaf powder is mixed with a deep eutectic solvent (DES), heated, and regenerated to obtain a ginkgo leaf cellulose-lignin slurry (GBS);

[0009] The ginkgo leaf cellulose-lignin slurry (GBS) and catkin fiber are mixed in a mass ratio of 70-90:30-10, paper-made, and dried to obtain a soft and multifunctional ginkgo leaf / catkin composite packaging paper.

[0010] In one embodiment, the catkin fibers have a diameter of 5 to 15 μm and a length of 5 to 10 mm.

[0011] In one embodiment, the particle size of the ginkgo leaf powder is 40-60 meshes.

[0012] In one embodiment, the preparation method of DES is:

[0013] Choline chloride and oxalic acid are mixed in a molar ratio of 1:1 and melted at 80-100° C. to obtain DES.

[0014] In one embodiment, the catkin fibers are obtained by crushing untreated catkin fibers with a length of 10 to 20 mm at 5000 to 8000 r / min for 1 to 3 minutes to obtain catkin fibers with a length of 5 to 10 mm.

[0015] In one embodiment, the preparation method of ginkgo biloba cellulose-lignin slurry (GBS) is:

[0016] Mix 40-60 mesh ginkgo leaf powder and DES in a mass ratio of 1:10-20, heat at 90-120°C for 1-3h to obtain a brown liquid, cool, wash with water, and regenerate to obtain ginkgo leaf cellulose-lignin slurry (GBS);

[0017] Among them, the 40-60 mesh ginkgo leaf powder is obtained by grinding and sieving the dried ginkgo leaves;

[0018] Cooling is cooling to room temperature;

[0019] The volume ratio of water to brown liquid is 1:10-15;

[0020] Regeneration can be accelerated by stirring or ultrasonic treatment;

[0021] The ginkgo leaf cellulose-lignin slurry (GBS) is stirred at 400-800 r / min for 0.5-2h, filtered, and the filtrate is evaporated and dehydrated to recycle DES; the filtration is performed using filter paper with a pore size of less than 5 μm until the filtration is complete; the obtained filtrate is DES, and the remaining viscous filter pulp is GBS.

[0022] The second object of the present invention is to provide a soft and multifunctional ginkgo leaf / willow catkin composite packaging paper prepared by the method described in the present invention.

[0023] The third object of the present invention is to use the ginkgo leaf / willow catkin composite packaging paper of the present invention in the field of food packaging, medicine packaging or cosmetic packaging.

[0024] The fourth object of the present invention is to provide a cosmetic packaging box, which adopts the ginkgo leaf / willow catkin composite packaging paper described in the present invention.

[0025] The fifth object of the present invention is to provide a method for improving the fluorescence performance, UV resistance, mechanical properties and biodegradability of ginkgo leaf packaging paper, comprising the following steps:

[0026] The ginkgo leaf powder is mixed with a deep eutectic solvent (DES), heated, and regenerated to obtain a ginkgo leaf cellulose-lignin slurry (GBS);

[0027] The ginkgo leaf cellulose-lignin slurry (GBS) and catkin fiber are mixed in a mass ratio of 70-90:30-10, paper-made, and dried to obtain a soft and multifunctional ginkgo leaf / catkin composite packaging paper.

[0028] Beneficial Effects

[0029] (1) The present invention utilizes a deep eutectic solvent (DES) to separate lignin from ginkgo leaves, and after adding water, the lignin is regenerated in situ to obtain a ginkgo leaf cellulose-lignin slurry (GBS) with high solid content and high viscosity; and the ginkgo leaf cellulose-lignin slurry (GBS) is mixed with catkin fibers to prepare a low-cost ginkgo leaf / catkin composite packaging paper. The composite packaging paper prepared by the present invention is flat, soft, and strong, with a thickness of about 0.1 mm and a grammage per square meter of about 50 g / m 2, the material input can be appropriately increased or decreased according to actual needs to obtain thicker or thinner packaging paper.

[0030] (2) The mass proportion of ginkgo leaf cellulose-lignin slurry (GBS) in the packaging paper of the present invention is preferably between 70% and 90%. The higher the content of GBS prepared from ginkgo leaves, the better the anti-ultraviolet performance. The UPF value reaches 1928 when the mass proportion of GBS is 90%. The higher the content of catkin fiber in the packaging paper, the better the water repellent effect and the softer the product. When the mass proportion of catkin fiber is 30%, the contact angle reaches 144.2° and the softness reaches 6.03 cm.

[0031] (3) The ginkgo leaf / willow catkin composite packaging paper prepared by the present invention has fluorescent properties and is biodegradable, which greatly reduces resource waste and garbage generation. The raw materials used can be recycled and have broad application prospects. It is a papermaking method with development potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart for the preparation of ginkgo leaf composite packaging paper.

[0033] Figure 2 These are scanning electron microscope images of willow catkin fiber and kapok fiber; among them, (a) willow catkin fiber; (b) kapok fiber; (c) cross section of willow catkin fiber; (d) cross section of kapok fiber.

[0034] Figure 3 Surface morphology of ginkgo leaf composite packaging paper; (a) 80% GBS / 20% WC; (b) 80% GB / 20% WC; (c) ginkgo leaf cellulose-lignin pulp paper (GBS); (d) 80% GBS / 20% chitosan.

[0035] Figure 4 The microstructure diagrams of composite wrapping papers prepared from different materials; among them, (a) ginkgo leaf / willow catkin composite wrapping paper; (b) ginkgo leaf / kapok composite wrapping paper; (c) camphor leaf / willow catkin composite wrapping paper.

[0036] Figure 5 The fluorescence performance diagrams of composite packaging papers made of different materials; among them, (a) 80% GBS / 20% WC; (b) 80% GBS / 20% KF; (c) 80% CLS / 20% WC.

[0037] Figure 6The figures are for testing the softness of composite wrapping paper by the heart-shaped method; among them, (a) Ginkgo leaf / willow catkin composite wrapping paper (70% GBS / 30% WC, 80% GBS / 20% WC, 90% GBS / 10% WC); (b) Ginkgo leaf / kapok composite wrapping paper (70% GBS / 30% KF, 80% GBS / 20% KF, 90% GBS / 10% KF); (c) Camphor leaf / willow catkin composite wrapping paper (70% CLS / 30% WC, 80% CLS / 20% WC, 90% CLS / 10% WC).

[0038] Figure 7 The degradation process diagram of Ginkgo leaf composite packaging paper (80% GBS / 20% WC); (a) placed on the soil surface; (b) buried 5 cm in the soil layer. DETAILED DESCRIPTION

[0039] 1. Morphology / performance test of composite packaging paper:

[0040] (1) Surface morphology

[0041] The surface morphology of the packaging paper was observed under a microscope.

[0042] (2) Fluorescence performance

[0043] An inverted fluorescence microscope was used to test the fluorescence properties of the wrapping paper, and all images were taken in a dark field at room temperature.

[0044] (3) Contact angle measurement

[0045] The contact angle measurement system was used to measure the state of a 10 μL water droplet on the surface of the wrapping paper.

[0046] (4) Anti-ultraviolet performance

[0047] The anti-ultraviolet performance of the packaging paper is measured using a textile UV tester. The lower the UVA and UVB transmittance, the higher the protection factor (UPF), and the better the anti-ultraviolet performance of the sample.

[0048] (5) Mechanical properties

[0049] The breaking strength, breaking elongation and tensile index of the packaging paper were measured using a tensile strength tester, and the sample size was 15×1cm;

[0050] The softness of the packaging paper was determined by the heart-shaped method, and the sample size was 20×2 cm.

[0051] (6) Biodegradability

[0052] The composite wrapping paper has a size of 5×5 cm and is placed in the lawn and buried in natural soil at a depth of 5 cm. Samples are taken regularly to test its biodegradability.

[0053] 2. Raw materials used in the embodiments and comparative examples:

[0054] Willow catkins and ginkgo leaves were collected on the campus of Jiangnan University;

[0055] Kapok fiber was purchased from Pengcai Home Textiles;

[0056] Camphor tree leaves were purchased from Haozhou Jianzheng Trading Co., Ltd.;

[0057] Choline chloride (CAS No.: 67-48-1) and oxalic acid (CAS No.: 144-62-7) were purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0058] Dried ginkgo leaves and camphor tree leaves: select clean leaves, dry them and set aside.

[0059] The preparation method of viscous cellulose-lignin slurry (GBS) is as follows:

[0060] (1) Preparation of deep eutectic solvent (DES):

[0061] Mix choline chloride and oxalic acid in a molar ratio of 1:1, melt at 80°C to obtain a uniform transparent liquid, which is DES, and cool it to room temperature for later use;

[0062] (2) Grind dried fallen ginkgo leaves into powder (GB), pass through a 50-mesh sieve, and mix with the DES obtained in step (1) at a mass ratio of 1:15, heat at 120° C. for 2 h to obtain a brown liquid, and add 10 times the volume of distilled water to wash after cooling to room temperature to regenerate a viscous ginkgo leaf cellulose-lignin slurry (GBS); stir the ginkgo leaf cellulose-lignin slurry (GBS) at 600 r / min for 1 h, filter, and evaporate and dehydrate the filtrate to recycle the DES.

[0063] The preparation method of the viscous camphor leaf cellulose-lignin slurry (CLS) is as follows:

[0064] (1) Preparation of deep eutectic solvent (DES):

[0065] Mix choline chloride and oxalic acid in a molar ratio of 1:1, melt at 80°C to obtain a uniform transparent liquid, which is DES, and cool it to room temperature for later use;

[0066] (2) Grind dried camphor tree fallen leaves into powder (CL), pass through a 50-mesh sieve, and mix with the DES obtained in step (1) at a mass ratio of 1:15, heat at 120° C. for 2 h to obtain a brown liquid, and add 10 times the volume of distilled water to wash the brown liquid after cooling to room temperature to regenerate a viscous camphor tree leaf cellulose-lignin slurry (CLS); stir the camphor tree leaf cellulose-lignin slurry (CLS) at 600 r / min for 1 h, filter, and evaporate and dehydrate the filtrate to recycle the DES.

[0067] 3. Appearance and morphology of catkin fiber and kapok fiber

[0068] The scanning electron microscopy results of willow catkin fibers and kapok fibers after gold spraying are as follows: Figure 2 As shown:

[0069] The diameter of catkin fiber is 5-15μm, the length is 5-15mm, it is fine, soft, light, and has a high fluffiness. The surface is covered with a waxy layer, smooth, without twists, and has a clear cavity structure.

[0070] The diameter of kapok fiber is 20-45 μm, the length is 8-32 mm, and the surface morphology is similar to willow catkins.

[0071] Example 1

[0072] A method for preparing soft and multifunctional ginkgo leaf / willow catkin composite wrapping paper comprises the following steps:

[0073] The untreated willow catkin (WC) fibers with a length of 5 to 15 mm were crushed at 7000 r / min for 2 min to obtain willow catkin (WC) fibers with a length of 5 to 10 mm;

[0074] Ginkgo leaf cellulose-lignin pulp (GBS) and willow catkin (WC) fiber were mixed in a mass ratio of 90:10, dispersed evenly using a deflaker at 1000 r / min, and then vacuum pressed at 110° C. for 5 min using a paper sampler to obtain a ginkgo leaf / willow catkin composite packaging paper (90% GBS / 10% WC).

[0075] Example 2

[0076] The specific implementation is the same as that of Example 1, except that:

[0077] GBS and willow catkin (WC) fibers were mixed at a mass ratio of 80:20, and other conditions remained unchanged to prepare ginkgo leaf / willow catkin composite packaging paper (80% GBS / 20% WC).

[0078] Example 3

[0079] The specific implementation is the same as that of Example 1, except that:

[0080] GBS and willow catkin (WC) fibers were mixed at a mass ratio of 70:30, and other conditions remained unchanged to prepare ginkgo leaf / willow catkin composite packaging paper (70% GBS / 30% WC).

[0081] Example 4

[0082] The specific implementation is the same as that of Example 1, except that:

[0083] GBS and willow catkin (WC) fibers were mixed at a mass ratio of 60:40, and other conditions remained unchanged to prepare ginkgo leaf / willow catkin composite packaging paper (60% GBS / 40% WC).

[0084] Example 5

[0085] The specific implementation is the same as that of Example 1, except that:

[0086] GBS and willow catkin (WC) fibers were mixed at a mass ratio of 50:50, and other conditions remained unchanged to prepare ginkgo leaf / willow catkin composite packaging paper (50% GBS / 50% WC).

[0087] Comparative Example 1

[0088] A method for preparing soft and multifunctional ginkgo leaf / kapok composite wrapping paper comprises the following steps:

[0089] The kapok fibers (KF) with a length of 8 to 32 mm were crushed at 7000 r / min for 2 min to obtain kapok fibers (KF) with a length of 5 to 10 mm;

[0090] GBS and kapok fiber (KF) were mixed in a mass ratio of 90:10, dispersed evenly by a deflaker at 1000 r / min, and vacuum pressed by a paper sampler at 110° C. for 5 min to obtain a ginkgo leaf / kapok composite packaging paper (90% GBS / 10% KF).

[0091] Comparative Example 2

[0092] The specific implementation is the same as that of Comparative Example 1, except that:

[0093] GBS and kapok fiber (KF) were mixed at a mass ratio of 80:20, and other conditions remained unchanged to prepare ginkgo leaf / kapok composite packaging paper (80% GBS / 20% KF).

[0094] Comparative Example 3

[0095] The specific implementation is the same as that of Comparative Example 1, except that:

[0096] GBS and kapok fiber (KF) were mixed at a mass ratio of 70:30, and other conditions remained unchanged to prepare ginkgo leaf / kapok composite packaging paper (70% GBS / 30% KF).

[0097] Comparative Example 4

[0098] The specific implementation is the same as that of Comparative Example 1, except that:

[0099] GBS and kapok fiber (KF) were mixed at a mass ratio of 60:40, and other conditions remained unchanged to prepare ginkgo leaf / kapok composite packaging paper (60% GBS / 40% KF).

[0100] Comparative Example 5

[0101] The specific implementation is the same as that of Comparative Example 1, except that:

[0102] GBS and kapok fiber (KF) were mixed at a mass ratio of 50:50, and other conditions remained unchanged to prepare ginkgo leaf / kapok composite packaging paper (50% GBS / 50% KF).

[0103] Comparative Example 6

[0104] The specific implementation is the same as that of Example 1, except that:

[0105] The ginkgo leaf cellulose-lignin slurry (GBS) was adjusted to the camphor leaf cellulose-lignin slurry (CLS); other conditions remained unchanged, and the camphor leaf / willow catkin packaging paper (90% CLS / 10% WC) was prepared.

[0106] Comparative Example 7

[0107] The specific implementation is the same as that of Comparative Example 6, except that:

[0108] CLS and willow catkin (WC) fibers were mixed at a mass ratio of 80:20, and other conditions remained unchanged to prepare camphor leaf / willow catkin composite packaging paper (80% CLS / 20% WC).

[0109] Comparative Example 8

[0110] The specific implementation is the same as that of Comparative Example 6, except that:

[0111] CLS and willow catkin (WC) fibers were mixed in a mass ratio of 70:30, and other conditions remained unchanged to prepare camphor leaf / willow catkin composite packaging paper (70% CLS / 30% WC).

[0112] Comparative Example 9

[0113] The specific implementation is the same as that of Comparative Example 6, except that:

[0114] CLS and willow catkin (WC) fibers were mixed in a mass ratio of 60:40, and other conditions remained unchanged to prepare camphor leaf / willow catkin composite packaging paper (60% CLS / 40% WC).

[0115] Comparative Example 10

[0116] The specific implementation is the same as that of Comparative Example 6, except that:

[0117] CLS and willow catkin (WC) fibers were mixed in a mass ratio of 50:50, and other conditions remained unchanged to prepare camphor leaf / willow catkin composite packaging paper (50% CLS / 50% WC).

[0118] Comparative Example 11

[0119] The specific implementation is the same as that of Example 2, except that:

[0120] Ginkgo leaf powder (GB) was not treated with DES, and other conditions remained unchanged to prepare Ginkgo leaf powder / willow catkin composite packaging paper (80% GB / 20% WC).

[0121] Comparative Example 12

[0122] The specific implementation is the same as that of Example 2, except that:

[0123] Without using willow catkin (WC) fiber, GBS accounts for 100%, and other conditions remain unchanged to prepare Ginkgo biloba cellulose-lignin pulp (GBS)

[0124] Comparative Example 13

[0125] A method for preparing a ginkgo leaf / chitosan composite packaging film comprises the following steps:

[0126] 1 mL of glacial acetic acid solution was drawn with a syringe, added to a beaker containing 100 mL of deionized water, and stirred for 10 min to prepare a 1% glacial acetic acid solution; 1 g of chitosan powder was accurately weighed, added to 100 mL of 1% glacial acetic acid solution, and stirred at 35°C for 12 h to prepare a 1% chitosan solution;

[0127] Weigh 0.8 g GBS (dry weight) into a beaker, use a syringe to draw 20 mL of 1% chitosan solution and add it to the beaker, first mix and stir in a water bath at 35°C for 0.5 h, then place it in a CNC ultrasonic cleaner for ultrasonic dispersion for 1 h, the ultrasonic power is 100 W, the frequency is 40 kHz, and finally place it in a water bath and stir for 0.5 h to complete the mixing, pour it into a culture dish, let it stand to remove bubbles, put it in a -24°C refrigerator and freeze it for 12 h, take it out, thaw it at room temperature for 2.5 h, put it in an oven at 40°C to dry it for 11 h, and remove the film to obtain the ginkgo leaf / chitosan composite packaging film (80% GBS / 20% chitosan).

[0128] The composite packaging papers prepared in Examples 1 to 5 and Comparative Examples 1 to 13 were tested for morphology and performance, and the results were as follows:

[0129] (1) Surface morphology

[0130] The surface morphology of the Ginkgo leaf composite packaging paper is shown in the figure Figure 3 shown.

[0131] from Figure 3 It can be seen that the surface of the ginkgo leaf / willow catkin composite packaging paper (80% GBS / 20% WC) in Example 2 is smooth, soft and strong, with a thickness of about 0.1 mm and a grammage of about 50 g / m 2 ; The ginkgo leaf powder / willow catkins composite packaging paper (80% GB / 20% WC) prepared from the ginkgo leaf powder not treated with DES in Comparative Example 11 has almost no viscosity, is difficult to shape, and is not suitable for preparing composite packaging paper; the ginkgo leaf cellulose-lignin pulp paper (GBS) without plant fiber in Comparative Example 12 can also be formed, but is brittle and fragile due to the lack of reinforcing fibers, and is not suitable for preparing composite packaging paper; the ginkgo leaf / chitosan composite packaging film (80% GBS / 20% chitosan) prepared in Comparative Example 13 has a certain strength, but is hard in texture and difficult to bend, and is not suitable for being called paper.

[0132] The microstructure of composite packaging paper prepared from different materials is shown in the figure Figure 4 shown.

[0133] from Figure 4 It can be seen that: in general, the surface characteristics of the packaging paper prepared by catkin fiber and kapok fiber under the microscope are not much different. With the increase of GBS mass proportion, the color of the packaging paper becomes darker, the edge hairiness is less, the fiber and GBS are closer, and the surface is smoother; the composite packaging paper prepared by CLS becomes darker with the increase of CLS proportion, but the change difference is not obvious. It can be seen that in general, the mass proportion of GBS and CLS is preferably between 70% and 90%; therefore, the composite packaging paper obtained with GBS mass proportion of 70% to 90% is further used for other performance tests.

[0134] (2) Fluorescence performance

[0135] The fluorescence performance of composite packaging paper made of different materials is shown in the figure Figure 5 shown.

[0136] from Figure 5It can be seen that all composite packaging papers have a fluorescent effect, which may be due to the fact that the aromatic substances contain more conjugated C=C double bonds on the benzene ring, which can absorb light energy to enter the excited state and quickly return to the ground state, producing a fluorescent effect; the ginkgo leaf composite packaging paper also retains this property, which can increase the recognition of the product and has good application prospects in anti-counterfeiting packaging.

[0137] (3) Contact angle measurement

[0138] The contact angle of water droplets was measured on the surface of the wrapping paper. Since the front side of the ginkgo leaf is hydrophilic and the back side is hydrophobic, the GBS treated with DES has both polar hydrophilic side chains (such as phenolic hydroxyl groups) and non-polar hydrophobic main chains (such as hydrocarbon groups). The polar hydrophilic side chains can cross-link with cellulose to provide mechanical strength, and the non-polar hydrophobic main chains can prevent water penetration.

[0139] The contact angle measurement results of the packaging paper are shown in Table 1.

[0140] From Table 1, it can be seen that catkin fiber and kapok fiber are both hydrophobic materials with contact angles above 130°; the contact angle of GBS is 96.9°; the contact angle of the packaging paper prepared by compounding the two is above 110°. At the same ratio, the contact angle of the packaging paper prepared by catkin fiber is larger and can be applied in a wider range. The contact angle of the composite paper prepared with camphor leaves as raw materials is greater than 100°, showing hydrophobicity, but at the same ratio, the water repellent effect is not as good as the composite packaging paper prepared by ginkgo leaves.

[0141] Table 1 Contact angle of packaging paper

[0142]

[0143] (4) Anti-ultraviolet performance

[0144] The test results of the UV resistance of the ginkgo leaf composite packaging paper are shown in Table 2.

[0145] Table 2 Anti-ultraviolet performance of packaging paper

[0146]

[0147] It can be seen from Table 2 that when the mass proportion of GBS is above 70%, the UPF value of the packaging paper reaches 100+, which is much higher than that of A4 printing paper with similar thickness (thickness of about 0.1mm, square meter weight of about 70g / m 2 ), has good anti-ultraviolet performance; and the higher the proportion of GBS, the higher the UPF value, the better the anti-ultraviolet performance of the wrapping paper. Under the same proportion, the anti-ultraviolet performance of the wrapping paper made of catkin fiber is better than that of kapok fiber, and the composite paper made of camphor leaves also has anti-ultraviolet function, and the effect is good.

[0148] (5) Mechanical properties

[0149] The mechanical properties test results of the ginkgo leaf composite packaging paper are shown in Table 3.

[0150] It can be seen from Table 3 that when the mass proportions of GBS and catkin fiber are 80% and 20% respectively, the strength of the wrapping paper is the highest. At the same proportion, the breaking strength, breaking elongation and softness (hanging height) of the wrapping paper prepared from catkin fiber are slightly higher than those of kapok fiber. This may be because catkin fiber is finer and softer, and the structure of the wrapping paper made is more compact. At the same proportion, the performance of the composite paper prepared from ginkgo leaves is slightly better than that of camphor leaves. This may be because the lignin content in ginkgo leaves is higher, and the cellulose-lignin slurry prepared is more viscous and has a better effect of combining with fibers.

[0151] Table 3 Mechanical properties of composite packaging paper

[0152]

[0153] The results of the heart-shaped method for testing the softness of the ginkgo leaf composite wrapping paper are as follows: Figure 6 shown.

[0154] from Figure 6 It can be seen that the higher the fiber ratio, the longer the hanging height and the softer the wrapping paper. Under the same ratio, the wrapping paper made of catkin fiber has a longer hanging height than that of kapok fiber, and the wrapping paper made of ginkgo leaves has a longer hanging height than that of camphor leaves, and the wrapping paper is softer.

[0155] (6) Biodegradability

[0156] Since ginkgo leaves, camphor leaves, willow catkins and kapok are all common products in nature and are degradable, the wrapping paper made from them retains this advantage.

[0157] The degradation process of the ginkgo leaf composite packaging paper (80% GBS / 20% WC) of Example 2 is shown in FIG. Figure 7 shown.

[0158] from Figure 7 It can be seen that: whether Figure 7 (a) placed on the lawn surface, or Figure 7 (b) When shallowly buried in the soil, the composite packaging paper is completely degraded within 50 days.

[0159] Composite packaging paper (GBS / KF) and (CLS / WC) also completely degraded within 50 days. These materials showed good biodegradability in the natural environment and have good application prospects in reducing environmental pollution.

[0160] In summary, the ginkgo leaf / willow catkin composite packaging paper prepared by the present invention has a larger contact angle and better anti-ultraviolet performance than the ginkgo leaf / kapok composite packaging paper. The breaking strength, breaking elongation and softness (hanging height) of the ginkgo leaf / kapok composite packaging paper are higher than those of the ginkgo leaf / kapok packaging paper.

[0161] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a soft and multifunctional ginkgo leaf / willow catkin composite wrapping paper, characterized in that: The steps include: The ginkgo leaf powder is mixed with a low eutectic solvent, heated, and regenerated to obtain a ginkgo leaf cellulose-lignin slurry; The ginkgo leaf cellulose-lignin pulp and willow catkin fiber are mixed in a mass ratio of 70-90:30-10, paper-made, and dried to obtain a soft and multifunctional ginkgo leaf / willow catkin composite packaging paper.

2. The method according to claim 1, characterized in that The diameter of catkin fiber is 5 to 15 μm and the length is 5 to 10 mm.

3. The method according to claim 1, characterized in that The particle size of the ginkgo leaf powder is 40 to 60 meshes.

4. The method according to claim 1, characterized in that The preparation method of the deep eutectic solvent is: Choline chloride and oxalic acid are mixed in a molar ratio of 1:1, and melted at 80-100° C. to obtain a low eutectic solvent.

5. The method according to claim 1, characterized in that The preparation method of ginkgo leaf cellulose-lignin slurry is: The ginkgo leaf powder and the low eutectic solvent are mixed in a mass ratio of 1:10-20, heated at 90-120° C. for 1-3 hours to obtain a brown liquid, and cooled; water is then added for washing, and regeneration is performed to obtain a ginkgo leaf cellulose-lignin slurry.

6. The method according to claim 5, characterized in that Ginkgo leaf powder is obtained by grinding and sieving dried ginkgo leaves.

7. The soft and multifunctional ginkgo leaf / willow catkin composite wrapping paper prepared by the method according to any one of claims 1 to 6.

8. Use of the ginkgo leaf / willow catkin composite packaging paper according to claim 7 in the field of food packaging, medicine packaging or cosmetic packaging.

9. A cosmetic packaging box, characterized in that: It adopts the ginkgo leaf / willow catkin composite packaging paper described in claim 7.

10. A method for improving the fluorescence performance, UV resistance, mechanical properties and biodegradability of ginkgo leaf packaging paper, characterized in that: The steps include: The ginkgo leaf powder is mixed with a low eutectic solvent, heated, and regenerated to obtain a ginkgo leaf cellulose-lignin slurry; The ginkgo leaf cellulose-lignin pulp and willow catkin fiber are mixed in a mass ratio of 70-90:30-10, paper-made, and dried to obtain a soft and multifunctional ginkgo leaf / willow catkin composite packaging paper.

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