Electrostatically assisted fluorescent fiber directional ordering device and method

Abstract

This invention provides a method for the directional and orderly arrangement of electrostatically assisted fluorescent fibers, comprising the following steps: pre-treating the fluorescent fibers; uniformly distributing the pre-treated fluorescent fibers on a lower substrate, placing a transparent insulating frame on the lower substrate, with the fluorescent fibers located within the insulating frame, the sidewalls of the insulating frame coated with a pre-formed adhesive layer; then placing an upper substrate on top of the insulating frame to form a closed space; based on corona discharge, under the action of a non-uniform electrostatic field, the fluorescent fibers are orderly deposited onto the pre-formed adhesive layer, and then the pre-formed adhesive layer is cured to encapsulate the fluorescent fibers. This invention, by coupling fiber surface control, electrostatic driving, and rapid curing steps, achieves rapid and orderly arrangement of millimeter-scale fluorescent fibers in dry air. It is not only suitable for the functional construction of complex surface structures but also has the potential for seamless integration with continuous production processes such as roll-to-roll manufacturing, providing a practical and feasible process path for large-scale, high-efficiency anti-counterfeiting label manufacturing.

Description

Technical Field

[0001] This invention relates to the field of fiber material assembly technology, and in particular to an electrostatically assisted fluorescent fiber directional and orderly arrangement device and method. Background Technology

[0002] Fluorescent fibers, due to their unique optical properties, have wide applications in anti-counterfeiting, sensing, and decoration. Currently, the mainstream technical approaches to achieving ordered fiber arrangement mainly include the traditional method of randomly blending fibers onto a substrate, and the method of first preparing a prefabricated functional layer containing oriented fibers, followed by transfer printing through a secondary composite process. In addition, fiber orientation technology based on external fields such as electric and magnetic fields has also seen some development.

[0003] Among these technologies, electrostatic field-based fiber manipulation techniques (such as electrospinning) are the most representative. However, these techniques are typically used for polymer materials dissolved or dispersed in liquid media. They involve preparing and depositing micro- and nano-scale fibers through the action of electric fields, and the entire process depends on the evaporation of solvents and a conductive substrate. Therefore, existing electrostatic techniques are mainly suitable for in-situ forming of micro-scale fibers. For pre-fabricated macro-scale solid fluorescent fibers, achieving rapid, batch, and high-precision spatial orientation in a dry environment still faces significant challenges, especially in forming highly consistent orientation structures on non-horizontal surfaces (such as vertical or inclined sidewalls). Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide an electrostatically assisted fluorescent fiber directional and orderly arrangement device and method.

[0005] Therefore, the present invention provides a method for the directional and ordered arrangement of electrostatically assisted fluorescent fibers, comprising the following steps:

[0006] S1. Pre-treat the fluorescent fibers;

[0007] S2. The pretreated fluorescent fibers are evenly distributed on the lower substrate. A transparent insulating frame is placed on the lower substrate, and the fluorescent fibers are located inside the insulating frame. The sidewalls of the insulating frame are coated with a pre-made adhesive layer. Then, the upper substrate is placed on top of the insulating frame to form a closed space.

[0008] S3. Based on corona discharge, fluorescent fibers are deposited in an orderly manner onto a pre-prepared adhesive layer under the action of a non-uniform electrostatic field, and then the pre-prepared adhesive layer is cured to encapsulate the fluorescent fibers.

[0009] Preferably, in step S1, the fluorescent fiber is pretreated, including the following steps:

[0010] Select polymer fibers with fluorescent properties that have a diameter of 0.1-0.2 mm and a length of 1-10 mm;

[0011] The fibers were dried at 180±5℃ for 120±10 minutes to remove surface moisture.

[0012] Preferably, the preparation and curing of the pre-adhesive layer includes the following steps:

[0013] UV-curable adhesive is uniformly coated on the inner sidewall of the insulating frame to form a pre-formed adhesive layer;

[0014] After the fibers are deposited in an orderly manner on the pre-formed adhesive layer, the electric field is kept on, and the deposition area is irradiated with a UV lamp for 30-60 seconds to allow the UV-curable adhesive to cure quickly.

[0015] Preferably, in step S3, the applied voltage range is 17.0-20.5kV, and the discharge time is controlled within 30-50 seconds.

[0016] Preferably, the fiber comprises one or more of polystyrene, polymethyl methacrylate, and nylon 66, with an emission fluorescence wavelength range of 400–700 nm; the upper substrate is made of an insulating material, and the lower substrate is made of a metal material.

[0017] Preferably, the formula for calculating the degree of order of fluorescent fibers is:

[0018]

[0019] Among them, the fiber is defined as being in an ordered direction when the angle between the long axis of the fiber and the vertical direction is less than 30°.

[0020] The present invention also provides an electrostatically assisted fluorescent fiber orientation and orderly arrangement device, comprising:

[0021] A high-voltage power supply is connected to a discharge needle array at the positive terminal and to the lower substrate at the negative terminal, and a non-uniform electric field is constructed by the potential difference between the two terminals.

[0022] An array of discharge needles is uniformly arranged in the top area of ​​the upper substrate to generate spatially uniform corona discharge.

[0023] The upper substrate covers the top of the insulating frame, serving as a carrier for the accumulation of charged particles and the formation of an additional surface charge field;

[0024] The lower substrate serves as a platform for grounding the lower electrode and initial fiber distribution;

[0025] An insulating frame is located between the upper and lower substrates to form a sealed cavity. One of its inner walls is pre-coated with UV-curable adhesive, serving as the sole target surface for fiber orientation deposition.

[0026] Ultraviolet lamps are used to cure fibers deposited on the coated sidewalls in situ while maintaining a high-voltage electric field.

[0027] Preferably, the angle between the adhesive-coated sidewall and the plane of the lower substrate is 85°-90°, so as to maximize the electric field gradient near the sidewall.

[0028] This invention provides an electrostatically assisted directional and ordered arrangement device and method for fluorescent fibers, which has the following beneficial effects:

[0029] (1) Improve the orderliness of sidewall fiber arrangement: By adjusting the electric field parameters, the fibers are guided to preferentially deposit on vertical or inclined sidewalls, so that their long axis is stably aligned along the concentrated electric field lines. Experiments show that the orderliness of sidewall fibers can reach 93.75%, which is significantly higher than that of traditional horizontal substrate deposition, realizing efficient and highly consistent directional arrangement of fluorescent fibers on the sidewall surface;

[0030] (2) By synergistically optimizing fiber state and electric field distribution, the repeatability and consistency of fiber arrangement are significantly improved. The process control is simple, stable and easy to control, and suitable for continuous production.

[0031] (3) The formed oriented fiber array has anisotropic optical response characteristics, which are difficult to imitate and can improve the anti-counterfeiting security level; at the same time, it provides a new way to construct functional surfaces with specific orientation requirements. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of an electrostatically assisted fluorescent fiber orientation and orderly arrangement device;

[0033] Figure 2 This is a diagram of the upright orientation process of fibers in a non-uniform electric field.

[0034] Figure 3 This is a force analysis diagram of a fiber in a non-uniform electric field;

[0035] Figure 4 This is a schematic diagram of the directional deposition of fibers in the sidewall region of the insulating frame;

[0036] Figure 5 This is a schematic diagram of the overall fiber deposition distribution structure;

[0037] Figure 6 This is a graph showing the orderliness of the sidewall fibers.

[0038] The markings in the diagram are: 1. High-voltage power supply; 2. Discharge needle array; 3. Lower substrate; 4. Upper substrate; 5. Insulating frame; 6. Ultraviolet lamp. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products.

[0040] Example:

[0041] like Figures 1-6 As shown, the present invention provides an electrostatically assisted fluorescent fiber orientation and orderly arrangement device, including a high-voltage power supply 1, a discharge needle array 2, an upper substrate 4, a lower substrate 3, an insulating frame 5, and an ultraviolet lamp 6.

[0042] Among them, the high voltage power supply 1 outputs an adjustable DC high voltage of 17.0~20.5kV, the positive terminal is connected to the discharge needle array 2, and the negative terminal is connected to the stainless steel lower substrate 3, and a non-uniform electric field is constructed through the potential difference between the two terminals.

[0043] The discharge needle array 2 is uniformly arranged on the top region of the insulating upper substrate 4. A local strong field is generated at the tip of the discharge needle array 2 by the high voltage power supply 1, which triggers air ionization and forms a stable and uniform corona discharge. The uniform arrangement of the discharge needle array 2 ensures the uniformity of the corona discharge and avoids the difference in fiber deposition density caused by local field inhomogeneity, providing a stable and controllable ion current source for building the driving field in the cavity.

[0044] The upper substrate 4 is made of polystyrene (PS) and covers the top of the insulating frame 5, serving as a carrier for the accumulation of charged particles and the formation of an additional surface charge field. The charged particles generated by corona discharge migrate to the lower surface of the PS upper substrate 4 under the drive of the applied electric field. Due to the insulation of PS, the charge cannot leak and accumulates stably on its surface, forming a surface charge layer. After this layer is superimposed with the applied electric field, the cavity electric field undergoes spatial reconstruction, forming a gradient field near the sidewall of the insulating frame 5.

[0045] The lower substrate 3 is made of stainless steel and serves as a platform for the grounding electrode and the initial fiber distribution.

[0046] The insulating frame 5 is made of PS material and is located between the upper and lower substrates to form a sealed cavity. One of its inner walls is pre-coated with a 20-80 μm thick UV-curable adhesive, which serves as the sole target surface for fiber orientation deposition. The other inner walls remain clean and uncoated. The electric field gradient near the coated sidewall points towards that wall, generating a continuous dielectric attraction for the fibers. Fibers reaching the coated sidewall are adhered and captured by the adhesive layer, while fibers reaching other walls undergo elastic collision and rebound due to the absence of an adhesive layer, continuing to migrate within the cavity, forming multiple selective deposition accumulations on the coated sidewall.

[0047] The single-sided coating method concentrates and guides the final deposition of all fibers in the cavity to a single target surface, which greatly increases the deposition density of the target wall, reduces ineffective deposition, and improves fiber utilization.

[0048] The UV lamp 6 is used to cure the fibers that have been deposited on the coated sidewall in situ while maintaining a high voltage electric field.

[0049] Furthermore, the angle between the adhesive-coated sidewall and the plane of the lower substrate 3 is 85°-90°. In this embodiment, the adhesive-coated sidewall is arranged perpendicularly to the plane of the lower substrate 3, thereby maximizing the electric field gradient near the sidewall.

[0050] like Figures 2-6 As shown, the present invention also provides a method for the directional and ordered arrangement of electrostatically assisted fluorescent fibers, comprising the following steps:

[0051] Step 1: Pre-treat the fluorescent fibers;

[0052] Step 2: The pretreated fluorescent fibers are evenly distributed on the lower substrate 3. A transparent insulating frame 5 is placed on the lower substrate 3, and the fluorescent fibers are located inside the insulating frame 5. A pre-made adhesive layer is coated on one side wall of the insulating frame 5. Then, the upper substrate 4 is placed on top of the insulating frame 5, so that the upper substrate 4 is arranged parallel to the lower substrate 3 and forms a closed space with the insulating frame 5. The pre-made adhesive is a UV-curable adhesive (UV adhesive).

[0053] Step 3: Turn on the high-voltage power supply 1 to induce a stable corona discharge between the discharge needle and the upper substrate 4. The charged particles generated by the discharge migrate towards the PS upper substrate 4 under the influence of the electric field. Since the PS board is an insulating material, charge accumulates on its surface, forming a non-uniform surface charge distribution. This surface charge layer, superimposed on the external electric field of the discharge needle, reconstructs the electric field distribution between the upper and lower substrates, ultimately forming a non-uniform electrostatic field with a specific spatial gradient throughout the entire device space.

[0054] Under the influence of a non-uniform electric field excited by corona discharge, the applied voltage range is 17.0-20.5kV, preferably 18.5-19.5kV; the discharge time is controlled within 30-50 seconds.

[0055] The fiber first rotates from a flat position to a vertical position (the force situation during this process is shown in the attached figure). Figure 3 As shown in the figure, it then moves upward along the direction of the electric field lines, and when it collides with the PS insulating frame 5, it will be attracted and fixed on the side wall.

[0056] Fiber migration driven by a non-uniform electric field is significantly modulated by the spatial distribution of the electric field, resulting in their migration trajectory and final deposition location. Experiments show that the electric field distribution near the sidewalls of the insulating frame 5 has a directional guiding effect on the fibers, promoting their preferential migration and deposition on the sidewall surface (deposition area such as...). Figure 4 and Figure 5 (As shown). By shifting the position of the discharge needle array 2, fluorescent fibers are deposited on the coated sidewalls.

[0057] During the deposition process, under the combined constraints of electric field force and surface geometry, the long axis of the fibers spontaneously adjusts to fit the sidewall surface, thereby achieving a highly ordered directional arrangement.

[0058] like Figure 6 As shown, systematic process experiments revealed a correlation between applied voltage and fiber arrangement order: When the voltage is too low, the electric field is insufficient to drive the fibers to migrate stably to the sidewalls, leading to a decrease in deposition rate; when the voltage is too high, electrostatic repulsion between fibers increases, and their movement trajectories interfere with each other, resulting in a decrease in arrangement order. Specific experimental data are as follows:

[0059] 17.05 0.8 45 36 17.58 0.794872 39 31 18.36 0.848485 33 28 18.89 1 5 5 19.32 0.9375 48 45 19.78 0.875 8 7 20 0.8 10 8

[0060] Based on statistical analysis of experimental data, precise voltage control within the optimized range of 18.5-19.5 kV enables effective regulation of fiber deposition behavior and arrangement order. Under these conditions, fiber deposition order can stably reach over 90%, and further improve to a high level of 93% to 99% under the 18.5-19.5 kV condition.

[0061] Step 4: After deposition is complete, keep the electric field on and use UV lamp 6 to irradiate the deposition area for 30-60 seconds to allow the UV adhesive to cure quickly, thereby firmly encapsulating the fiber on the sidewall surface and ensuring the durability and reliability of its orientation and anti-counterfeiting features.

[0062] After fiber deposition, the electric field is not turned off; instead, the adhesive-coated sidewall is cured by ultraviolet irradiation while the high-voltage electric field is continuously applied. The continuous constraint of the electric field on the fibers covers the entire curing process, fundamentally eliminating the displacement and orientation relaxation of the fibers caused by gravity, capillary force, or adhesive flow during curing. This ensures that the final cured structure completely reproduces the highly ordered oriented morphology driven by the electric field.

[0063] Step 5: After curing, turn off the electric field and perform an orderliness test: Excite the deposited fibers with a UV lamp, observe their fluorescence distribution, calculate and statistically analyze the fiber orderliness, and finally form the overall deposited structure as shown in the figure. Figure 4 and Figure 5 As shown.

[0064] The formula for calculating the fiber orderliness is as follows:

[0065]

[0066] The fiber was defined as being in an ordered direction when the angle between its long axis and the vertical direction was less than 30°. Calculations showed that, under voltages of 18.5–19.5 kV, both sets of independent, repeated experiments achieved an ordering degree of over 93%, verifying the high repeatability of the process.

[0067] Furthermore, in step one, the fluorescent fibers undergo pretreatment, including the following steps:

[0068] 1. Select polymer fibers with fluorescent properties, having a diameter of 0.1-0.2 mm and a length of 1-10 mm; the fibers include one or more of polystyrene, polymethyl methacrylate, and nylon 66, with a fluorescence emission wavelength range of 400-700 nm.

[0069] 2. Dry the fibers at 180±5℃ for 120±10 minutes to remove surface moisture, reduce fiber conductivity, and decrease fiber adhesion. If the fibers contain water, the charge accumulated by corona discharge particles on the fiber surface will leak rapidly down to the substrate 3 through the water film. The fibers cannot accumulate enough net charge, thus losing their ability to migrate driven by the electric field. Therefore, drying can completely remove the water film.

[0070] Furthermore, before starting step two, the device needs to be cleaned. Wipe the inner surfaces of all components with anhydrous ethanol to remove residual particles and grease; after the ethanol has completely evaporated, use an antistatic fan to eliminate any residual triboelectric charge. Then, apply a 20–80 μm thick layer of UV-curable adhesive evenly to only one selected inner sidewall (the adhesive-coated sidewall).

[0071] If all sidewalls are coated with adhesive, fibers are randomly deposited on the four sidewalls, resulting in low deposition density on each sidewall. Furthermore, the electric field gradients near the four sidewalls are oriented differently, leading to competition between driving forces in four directions and complex fiber trajectories. Ultimately, this results in suboptimal order on each sidewall. Conversely, coating only one sidewall causes fibers reaching the uncoated sidewalls to elastically rebound. These fibers are not lost but return to the field to continue migrating, effectively increasing the number of effective fibers and concentrating fiber density. The geometric constraint of the sidewalls has a more significant effect on the overall ordering of the dense fiber group.

[0072] In industrial production scenarios, the discharge chamber can be designed as an open chute structure, with the adhesive-coated sidewall serving as a continuously conveyed flexible label substrate strip (the width of which matches the width of the chamber sidewall). The substrate strip passes through the discharge chamber at a uniform speed, completing continuous operations of fiber distribution, electric field driving, sidewall deposition, and UV curing during its passage. This forms a directional fiber anti-counterfeiting strip continuously distributed along the longitudinal direction of the substrate strip, enabling large-scale continuous production.

[0073] This invention achieves rapid and orderly arrangement of millimeter-scale fluorescent fibers in dry air by coupling fiber surface regulation, electrostatic driving, and rapid curing steps. It is not only suitable for the functional construction of complex surface structures, but also has the potential to be seamlessly integrated with continuous production processes such as roll-to-roll, providing a practical and feasible process path for large-scale and high-efficiency anti-counterfeiting label manufacturing.

[0074] In the description of this invention, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0075] However, the above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made in accordance with the scope of protection of the present invention should still fall within the scope of the claims of the present invention.

Claims

1. A method for the directional and ordered arrangement of electrostatically assisted fluorescent fibers, characterized in that, Includes the following steps: S1. Pre-treat the fluorescent fibers; S2. The pretreated fluorescent fibers are evenly distributed on the lower substrate. A transparent insulating frame is placed on the lower substrate, and the fluorescent fibers are located inside the insulating frame. A pre-made adhesive layer is coated on one side wall of the insulating frame. Then, the upper substrate is placed on top of the insulating frame to form a closed space. S3. Based on corona discharge, fluorescent fibers are deposited in an orderly manner onto a pre-made adhesive layer under the action of a non-uniform electrostatic field, and then the pre-made adhesive layer is cured by in-situ irradiation to encapsulate the fluorescent fibers.

2. The method for directional and ordered arrangement of electrostatically assisted fluorescent fibers according to claim 1, characterized in that, In step S1, the fluorescent fibers are pretreated, including the following steps: Select polymer fibers with fluorescent properties that have a diameter of 0.1-0.2 mm and a length of 1-10 mm; The fibers were dried at 180±5℃ for 120±10 minutes to remove surface moisture.

3. The method for directional and ordered arrangement of electrostatically assisted fluorescent fibers according to claim 1, characterized in that, The preparation and curing of the pre-adhesive layer includes the following steps: UV-curable adhesive is uniformly coated on the inner sidewall of the insulating frame to form a pre-formed adhesive layer; After the fibers are deposited in an orderly manner on the pre-formed adhesive layer, the electric field is kept on, and the deposition area is irradiated with a UV lamp for 30-60 seconds to allow the UV-curable adhesive to cure quickly.

4. The method for directional and ordered arrangement of electrostatically assisted fluorescent fibers according to claim 1, characterized in that, In step S3, the applied voltage range is 17.0-20.5kV, and the discharge time is controlled within 30-50 seconds.

5. The method for directional and ordered arrangement of electrostatically assisted fluorescent fibers according to claim 1, characterized in that, The fiber includes one or more of polystyrene, polymethyl methacrylate, and nylon 66, and emits fluorescence in the range of 400-700 nm; the upper substrate is made of insulating material, and the lower substrate is made of metal.

6. The method for directional and ordered arrangement of electrostatically assisted fluorescent fibers according to claim 1, characterized in that, The formula for calculating the degree of order in fluorescent fibers is: ； Among them, the fiber is defined as being in an ordered direction when the angle between the long axis of the fiber and the vertical direction is less than 30°.

7. A device for the directional and ordered arrangement of electrostatically assisted fluorescent fibers, characterized in that, include: A high-voltage power supply is connected to a discharge needle array at the positive terminal and to the lower substrate at the negative terminal, and a non-uniform electric field is constructed by the potential difference between the two terminals. An array of discharge needles is uniformly arranged in the top area of ​​the upper substrate to generate spatially uniform corona discharge. The upper substrate covers the top of the insulating frame, serving as a carrier for the accumulation of charged particles and the formation of an additional surface charge field; The lower substrate serves as a platform for grounding the lower electrode and initial fiber distribution; An insulating frame is located between the upper and lower substrates to form a sealed cavity. One of its inner walls is pre-coated with UV-curable adhesive, serving as the sole target surface for fiber orientation deposition. Ultraviolet lamps are used to cure fibers deposited on the coated sidewalls in situ while maintaining a high-voltage electric field.

8. The electrostatically assisted fluorescent fiber directional and ordered arrangement device according to claim 7, characterized in that, The angle between the coated sidewall and the plane of the lower substrate is 85°-90°, which maximizes the electric field gradient near the sidewall.

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