A regenerated cellulose-based high-strength conductive composite packing tape and a preparation method thereof

Abstract

The application discloses a regenerated cellulose-based high-strength conductive composite packing belt and a preparation method thereof, and belongs to the technical field of cellulose-based composite materials. The preparation method comprises the following steps: injecting cellulose solution and cellulose / graphene composite solution into different injectors respectively, fully immersing the injector needle into water to push the yarn, and preparing regenerated cellulose yarn and regenerated cellulose / graphene composite yarn; mixing the regenerated cellulose yarn and the regenerated cellulose / graphene composite yarn, uniformly laying the mixture, uniformly casting with polyvinyl alcohol solution, and then drying to obtain a packing belt semi-finished product; wrapping the packing belt semi-finished product after brushing polyvinyl alcohol solution on the regenerated cellulose film, and drying, and the green degradable packing belt with good mechanical properties, water resistance and conductivity is prepared.

Description

Technical Field

[0001] This invention relates to the field of cellulose-based composite materials technology, and in particular to a regenerated cellulose-based high-strength conductive composite packing tape and its preparation method. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Strapping, a common packaging material, is mainly used for sealing boxes, bundling, and transporting goods. Currently, most strapping on the market is made from a blend of polypropylene and polyester plastics. However, both are petroleum-based derivatives, possessing drawbacks such as non-degradability, environmental pollution, and difficulty in recycling. This hinders its development in the field of green packaging. Therefore, developing a green, renewable, high-performance strapping is urgently needed.

[0004] Cellulose is a natural polymer compound that is inexpensive, readily available, environmentally friendly, renewable, and biodegradable. It is poorly soluble in common organic and inorganic solutions, but ionic liquids can directly and physically dissolve cellulose without altering its intrinsic molecular structure and preserving its functional groups. The resulting regenerated cellulose solution possesses fluidity and plasticity, allowing it to be cast into various structures and shapes using molding tools. To impart new functional properties to regenerated cellulose materials, existing technologies often add various functional fillers to the regenerated cellulose solution. However, the addition of fillers may affect the mechanical properties of the regenerated fiber material.

[0005] For packing straps, on the one hand, they need to have high strength to ensure reliable use; on the other hand, if monitoring equipment can be used to monitor changes in humidity and external forces in their environment in real time, economic losses caused by unfavorable environments for the storage and transportation of packaged goods can be effectively reduced. Real-time monitoring requires the packing straps to have good conductivity and environmental sensitivity. Therefore, how to provide a packing strap that combines high strength, good conductivity, good environmental sensitivity, and biodegradability is an urgent problem to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a regenerated cellulose-based high-strength conductive composite packing tape and its preparation method. The composite packing tape has good water resistance, biodegradability, conductivity, and mechanical properties, and is highly sensitive to water and force.

[0007] In a first aspect, the present invention provides a method for preparing a regenerated cellulose-based high-strength conductive composite packing tape, comprising the following steps:

[0008] A) Inject cellulose solution and cellulose / graphene composite solution into different syringes respectively, and then completely immerse the syringe needle in water to push the fibers to obtain regenerated cellulose fibers and regenerated cellulose / graphene composite fibers.

[0009] B) The regenerated cellulose filaments and regenerated cellulose / graphene composite filaments are mixed and laid out evenly, then uniformly cast with polyvinyl alcohol solution, and then dried to obtain a semi-finished packing strap.

[0010] C) After brushing a polyvinyl alcohol solution onto the regenerated cellulose membrane, wrap the semi-finished packing tape around it and dry it to obtain the final product.

[0011] Secondly, the present invention provides a regenerated cellulose-based high-strength conductive composite packing tape obtained by the above preparation method.

[0012] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0013] The preparation method of this invention is simple, with low cost of raw materials and equipment. It can produce green biodegradable packing tape with good mechanical properties, water resistance and conductivity. It is also sensitive to changes in environmental humidity and the degree of external force, and can be used for real-time environmental monitoring, with broad application prospects. Attached Figure Description

[0014] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0015] Figure 1 These are strain tensile diagrams of the regenerated cellulose filaments of Examples 1-9 of the present invention;

[0016] Figure 2 These are strain tensile diagrams of the regenerated cellulose membranes of Examples 1-9 of the present invention;

[0017] Figure 3 These are strain tensile diagrams of the packing strap semi-finished product, the regenerated cellulose-based composite packing strap, and the polypropylene packing strap of Embodiment 9 of the present invention.

[0018] Figure 4 This is a sensing diagram of the regenerated cellulose-based composite packing tape of Embodiment 9 and Comparative Example 1 of the present invention in response to changes in ambient humidity.

[0019] Figure 5 These are the sensing diagrams of external force changes of the regenerated cellulose-based composite packing straps of Embodiment 9 and Comparative Example 1 of the present invention. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] This invention provides a method for preparing a regenerated cellulose-based high-strength conductive composite packing tape, comprising the following steps:

[0022] A) Inject cellulose solution and cellulose / graphene composite solution into different syringes respectively, and then completely immerse the syringe needle in water to push the fibers to obtain regenerated cellulose fibers and cellulose / graphene composite fibers.

[0023] B) The regenerated cellulose filaments and cellulose / graphene composite filaments are mixed and laid out evenly, then uniformly cast with polyvinyl alcohol solution, and then dried to obtain a semi-finished packing strap.

[0024] C) After brushing a polyvinyl alcohol solution onto the regenerated cellulose membrane, wrap the semi-finished packing tape around it and dry it to obtain the final product.

[0025] In this invention, graphene is added during the preparation of composite packing tape. Graphene has good electrical conductivity, optical properties and mechanical properties. When it is combined with cellulose, it can improve the conductivity of the composite material. At the same time, the hydroxyl groups between cellulose molecules can react with the oxygen-containing groups -Oh, COC, and -O- between graphene molecules to form hydrogen bonds, thereby enhancing the physical strength of the cellulose-based derivative.

[0026] This invention utilizes regenerated cellulose filaments and cellulose / graphene composite filaments as a skeleton, then coats the outer layer with a regenerated cellulose membrane, and casts it with a polyvinyl alcohol solution to prepare a high-strength cellulose-based packing strap. Its strength is comparable to or even better than that of existing plastic packing straps, and it also has good biodegradability and conductivity. It is sensitive to changes in environmental humidity and the degree of external force, and can detect changes in humidity and the magnitude of force from four dimensions: resistance, capacitance, impedance, and surface acoustic wave. This reduces the measurement threshold and improves the accuracy of detection, thereby enabling real-time monitoring of humidity changes and external force conditions in the environment where the packaging material is located, reducing economic losses caused by unfavorable environments for the storage and transportation of packaged goods.

[0027] In this invention, the thickness of the regenerated fiber membrane is 0.2–1 mm. The regenerated cellulose membrane is obtained by coating a cellulose solution, soaking it in water, and drying it. Specifically, the cellulose solution is uniformly coated onto a glass plate, coated with an adjustable coating tool, and then the coated glass plate is immersed in water for 20–30 hours for regeneration and then removed and naturally dried to obtain the membrane.

[0028] In this invention, the concentration of the cellulose solution is 1–5 wt%, more preferably 3–5 wt%. If the concentration of the cellulose solution is too low, the mechanical properties of the regenerated cellulose filaments and regenerated fiber membranes prepared therefrom will decrease; if the concentration of the cellulose solution is too high, the dissolution time will increase or complete dissolution will be difficult. This invention does not impose special restrictions on the preparation process of the cellulose solution; methods commonly used by those skilled in the art can be employed, with the aim of obtaining a well-dissolved, homogeneous, and stable cellulose solution.

[0029] In the cellulose / graphene composite solution of this invention, the mass ratio of cellulose to graphene is 1:0.8–1.2, and the mass concentration of cellulose is 1–5 wt%. Excessive cellulose concentration will increase the viscosity of the composite solution, which is detrimental to the uniform dispersion of graphene. Excessive graphene content will lead to poor compatibility between the two, while excessive cellulose content will hinder the effective utilization of graphene's conductivity. The preferred preparation method of the cellulose / graphene composite solution of this invention is as follows: graphene is added to a cellulose solution, and the solution is heated and stirred at 100–130°C and 300–500 r / min for 1–3 h, followed by ultrasonic dispersion for 20–40 min.

[0030] The solvent for the cellulose solution and the cellulose / graphene composite solution of the present invention is an ionic liquid, which may be selected from any one of 1-allyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium chloride, and is preferably 1-allyl-3-methylimidazolium chloride.

[0031] During the wire pushing process of this invention, the wire pushing flow rate of the syringe is 8-15 mL / min, and the diameter of the syringe needle is 0.5-1 mm.

[0032] After the extrusion step, the present invention further includes the step of soaking the obtained regenerated cellulose filaments and cellulose / graphene composite filaments in water for 20-30 hours, and then vacuum drying them at 60-90°C.

[0033] In step B) of the present invention, the width of the laying is 8-15 mm and the thickness of the laying is 0.2-1 mm.

[0034] In this invention, the ratio of regenerated cellulose filaments to regenerated cellulose / graphene composite filaments is 5–12:1, more preferably 10:1. This ratio ensures the conductivity and mechanical properties of the final composite strapping while controlling costs.

[0035] The preferred method of placement in this invention is close placement. During placement, both ends of the regenerated cellulose filaments and the regenerated cellulose / graphene composite filaments are fixed to prevent relative movement during subsequent polyvinyl alcohol solution casting. This invention does not impose special limitations on the fixing method; for example, clamps or pressing can be used for fixing.

[0036] In steps B) and C) of this invention, the concentration of the polyvinyl alcohol solution is 5–15 wt%, and the solvent for the polyvinyl alcohol solution is water. Polyvinyl alcohol is a biodegradable polymer, which mainly acts as a binder in this invention to bond and fix regenerated cellulose filaments, cellulose / graphene composite filaments, as well as packaging tape semi-finished products and regenerated cellulose membranes.

[0037] The drying in steps B) and C) of this invention is preferably vacuum drying, with a drying temperature of 60-90°C and a drying time of 2-5 hours.

[0038] In this invention, a glass plate is used as the base plate for casting and brushing polyvinyl alcohol solution, which facilitates the separation of the base plate from the dried packing strap semi-finished product and the final product.

[0039] In step C) of the present invention, a polyvinyl alcohol solution is brushed onto one side of the regenerated cellulose membrane, and then the side coated with the polyvinyl alcohol solution is used to wrap the semi-finished packing strap; the wrapping is a tight wrapping, with 1 to 3 layers, preferably 2 layers. Further wrapping with the regenerated cellulose membrane can significantly improve the tensile strength of the packing strap.

[0040] The present invention also provides a regenerated cellulose-based high-strength conductive composite packing tape obtained by the above preparation method, which has a width of 10-20 mm and a thickness of 0.5-2 mm.

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0042] In the following examples, the preparation process of the polyvinyl alcohol solution is as follows: 5g of polyvinyl alcohol solid particles are added to 45mL of water and stirred evenly. The mixture is then placed in a 100mL three-necked flask and stirred at 350r / min at 90℃ for 2h until the granular solid dissolves and the solution becomes clear and transparent, thus obtaining a polyvinyl alcohol solution with a mass concentration of 10%.

[0043] Example 1

[0044] (1) Preparation of cellulose solution: 0.5g of dissolved slurry plate fragments (cellulose fragments) were dispersed into 49.5g of 1-allyl-3-methylimidazolium chloride salt, placed in a 250mL three-necked flask, and stirred thoroughly at 450r / min for 1.5h at 120℃ until the sample was completely dissolved, resulting in a pale yellow cellulose solution with a polymer concentration of 1%.

[0045] (2) Preparation of cellulose / graphene composite solution: The cellulose solution in step (1) was stirred and heated at 120℃ and 450r / min. Graphene with a mass ratio of 1:1 to cellulose was added and stirred for 1h. The solution was then placed in an ultrasonic cleaner and dispersed for 30min to allow the graphene to be evenly dispersed in the cellulose solution, thus obtaining the cellulose / graphene composite solution.

[0046] (3) Preparation of regenerated cellulose filaments and cellulose / graphene composite filaments: The cellulose solution and cellulose / graphene composite solution from step (2) were placed in a vacuum defoamer for 5 min to defoam. The defoamed cellulose solution and cellulose / graphene composite solution were then injected into syringes and placed into a precision injection pump. The flow rate was adjusted to 10.0 mL / min and the speed to 15.25 mm / min. A syringe needle with a diameter of 0.62 mm was selected, and the syringe needle was completely immersed in deionized water before pushing the filament. The resulting filament was then immersed in deionized water for 24 h to regenerate, and then removed and tested for the presence of chloride ions with AgNO3. Finally, after straightening and fixing the shape, the filament was placed in a vacuum oven at 80℃ and 0.08 MPa for 30 min to dry, thus obtaining regenerated cellulose filaments and cellulose / graphene composite filaments.

[0047] (4) Preparation of regenerated cellulose membrane: The cellulose solution from step (1) was placed in a vacuum defoamer for 5 minutes to defoam. The defoamed cellulose solution was then evenly coated onto a glass plate that had been preheated in a 60°C oven. The thickness was controlled to 0.5 mm using an adjustable coating tool and the film was scraped. The glass plate was then immersed in deionized water for 24 hours to regenerate and then removed. The presence of chloride ions was tested with AgNO3. Finally, the membrane was naturally dried at room temperature to form a regenerated cellulose membrane with high transparency, good tensile strength, and good extensibility.

[0048] (5) Preparation of regenerated cellulose-based composite strapping: The regenerated cellulose filaments and cellulose / graphene composite filaments from step (3) are uniformly and tightly laid on a glass plate at a ratio of 10:1, with a laying width of approximately 10 mm. Both ends are fixed, and a polyvinyl alcohol solution is uniformly poured onto the laid filaments. After drying in an 80°C oven for 3 hours, a semi-finished strapping product is obtained. One side of the regenerated cellulose membrane is uniformly brushed with a 5% polyvinyl alcohol solution, and then the semi-finished strapping product is wrapped in two layers. It is then dried in an 80°C oven for 2 hours to obtain the regenerated cellulose-based composite strapping.

[0049] Example 2

[0050] The difference between this embodiment and embodiment 1 is that the needle diameter in this embodiment is 0.84 mm and the thickness of the adjustable coating device is 0.7 mm.

[0051] Example 3

[0052] The difference between this embodiment and embodiment 1 is that the needle diameter in this embodiment is 0.9 mm and the thickness of the adjustable coating device is 0.9 mm.

[0053] Example 4

[0054] The difference between this embodiment and Example 1 is that the preparation process of the cellulose solution in this embodiment is as follows:

[0055] 1.5 g of dissolved slurry plate fragments (cellulose fragments) were dispersed into 48.5 g of 1-allyl-3-methylimidazolium chloride and placed in a 250 mL three-necked flask. The mixture was stirred thoroughly at 120 °C and 450 r / min for 1.5 h until the sample was completely dissolved, resulting in a pale yellow cellulose solution with a polymer concentration of approximately 3%.

[0056] Example 5

[0057] The difference between this embodiment and embodiment 4 is that the needle diameter in this embodiment is 0.84 mm and the thickness of the adjustable coating device is 0.7 mm.

[0058] Example 6

[0059] The difference between this embodiment and embodiment 4 is that the needle diameter in this embodiment is 0.9 mm and the thickness of the adjustable coating device is 0.9 mm.

[0060] Example 7

[0061] The difference between this embodiment and Example 1 is that the preparation process of the cellulose solution in this embodiment is as follows:

[0062] 2.5 g of dissolved slurry plate fragments (cellulose fragments) were dispersed into 47.5 g of 1-allyl-3-methylimidazolium chloride and placed in a 250 mL three-necked flask. The mixture was stirred thoroughly at 120 °C and 450 r / min for 1.5 h until the sample was completely dissolved, resulting in a pale yellow cellulose solution with a mass concentration of 5%.

[0063] Example 8

[0064] The difference between this embodiment and embodiment 7 is that the needle diameter in this embodiment is 0.84 mm and the thickness of the adjustable coating device is 0.7 mm.

[0065] Example 9

[0066] The difference between this embodiment and embodiment 7 is that the needle diameter in this embodiment is 0.9 mm and the thickness of the adjustable coating device is 0.9 mm.

[0067] Comparative Example 1

[0068] The difference between this embodiment and Embodiment 9 is that no cellulose / graphene composite filaments are added during the preparation of the regenerated cellulose-based composite packing tape.

[0069] Test case

[0070] The regenerated cellulose filaments and regenerated cellulose membranes from Examples 1-9 were subjected to performance tests, as follows: Figure 1 and Figure 2 As shown in Table 1, the preparation conditions and performance data are summarized.

[0071] Table 1. Preparation conditions and performance data of regenerated cellulose filaments and regenerated cellulose membranes in Examples 1-9.

[0072]

[0073]

[0074] From Table 1 and Figures 1-2 As can be seen, cellulose concentration, needle diameter, and coating thickness will affect the mechanical properties of regenerated cellulose filaments and regenerated cellulose membranes to a certain extent. Among them, the preparation conditions of cellulose concentration of 5%, needle diameter of 0.9 mm, and coating thickness of 0.9 mm (i.e., Example 9) have the best mechanical properties.

[0075] The semi-finished packing strap obtained in Example 9 and the regenerated cellulose-based composite packing strap (approximately 11 mm wide and 0.8 mm thick) were compared with commercially available polypropylene packing strap (12 mm wide and 0.8 mm thick). The results are shown in Table 2 and... Figure 3 As shown.

[0076] Table 2 Performance data of packing strap semi-finished product, regenerated cellulose-based composite packing strap and polypropylene packing strap in Example 9

[0077]

[0078] As shown in Table 2, the mechanical properties of the packing tape semi-finished product obtained by tightly laying regenerated cellulose filaments and cellulose / graphene composite filaments and bonding them with polyvinyl alcohol are significantly improved compared with those of regenerated cellulose filaments, but the tensile strength is not as good as that of commercially available polypropylene packing tape. However, after wrapping the surface of the packing tape semi-finished product with a regenerated cellulose film, the tensile strength is further significantly improved, even exceeding that of existing polypropylene packing tape.

[0079] The regenerated cellulose-based composite packing tape of Example 9 remained stable in water for 30 days, indicating good water resistance. However, when placed in soil, the regenerated cellulose-based composite packing tape of Example 9 underwent significant degradation after 30 days.

[0080] The sensitivity of the regenerated cellulose-based composite packing tapes in Example 9 and Comparative Example 1 to water sensing and the sensitivity to different force applications are as follows: Figure 4 , Figure 5 As shown, the regenerated cellulose-based composite packing tape with added cellulose / graphene composite filaments exhibits higher environmental sensitivity.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a regenerated cellulose-based high-strength conductive composite packing strap, characterized in that, Includes the following steps: A) Inject cellulose solution and cellulose / graphene composite solution into different syringes respectively, and then completely immerse the syringe needle in water to push the fibers to obtain regenerated cellulose fibers and regenerated cellulose / graphene composite fibers. B) The regenerated cellulose filaments and regenerated cellulose / graphene composite filaments are mixed and laid out evenly, then uniformly cast with polyvinyl alcohol solution, and then dried to obtain a semi-finished packing strap; the ratio of the amount of regenerated cellulose filaments to regenerated cellulose / graphene composite filaments is 5~12:

1. C) After brushing polyvinyl alcohol solution onto the regenerated cellulose membrane, wrap the packing strap semi-finished product, and dry it to obtain the final product; The concentration of the cellulose solution is 1-5 wt%; in the cellulose / graphene composite solution, the mass ratio of cellulose to graphene is 1:0.8-1.2, and the mass concentration of cellulose is 1-5 wt%; the solvent for the cellulose solution and the cellulose / graphene composite solution is an ionic liquid.

2. The preparation method according to claim 1, characterized in that, The syringe feed rate is 8~15 mL / min, and the syringe needle diameter is 0.5~1 mm.

3. The preparation method according to claim 1, characterized in that, The ionic liquid is selected from any one of 1-allyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, or 1-ethyl-3-methylimidazolium chloride.

4. The preparation method according to claim 1, characterized in that, After the extrusion step is completed, the process also includes soaking the obtained regenerated cellulose filaments and cellulose / graphene composite filaments in water for 20-30 hours, and then vacuum drying them at 60-90°C.

5. The preparation method according to claim 1, characterized in that, In step B), the width of the laying is 8~15 mm and the thickness of the laying is 0.2~1 mm.

6. The preparation method according to claim 1, characterized in that, The concentration of the polyvinyl alcohol solution in steps B) and C) is 5-15 wt%, and the solvent of the polyvinyl alcohol solution is water; the drying in steps B) and C) is preferably vacuum drying, with a drying temperature of 60-90℃ and a drying time of 2-5 h.

7. The preparation method according to claim 1, characterized in that, In step C), the thickness of the regenerated fiber membrane is 0.2~1mm; the regenerated cellulose membrane is obtained by scraping a cellulose solution, soaking it in water, and drying it.

8. The preparation method according to claim 1, characterized in that, In step C), a polyvinyl alcohol solution is brushed onto one side of the regenerated cellulose membrane, and then the side coated with the polyvinyl alcohol solution is used to wrap the packing tape semi-finished product; the wrapping is a tight wrapping, and the number of wrapping layers is 1 to 3.

9. The regenerated cellulose-based high-strength conductive composite packing tape obtained by the preparation method according to any one of claims 1 to 8.

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