A roll-to-roll nanoimprinting apparatus and method

Abstract

This invention relates to a roll-to-roll nanoimprinting apparatus and method. The apparatus includes an impression roller, a mold roller, an auxiliary impression roller assembly, and a release roller. The mold roller cooperates with the impression roller and the release roller at the in-winding and rewinding points, respectively. The mold roller is connected to a bidirectional air pump via an airflow regulator. The bidirectional air pump and airflow regulator adjust the adsorption state of the mold roller to assist in positive and negative pressure gas filling and demolding. Both the impression roller and the release roller are connected to the air pump. A UV curing module is provided on the auxiliary impression roller assembly. At the in-winding point, the positive pressure of the impression roller and the negative pressure of the mold roller provide the imprinting force, and the auxiliary impression roller assembly with the UV curing module assists in filling and curing. At the rewinding point, the negative pressure of the release roller and the positive pressure of the mold roller provide the demolding force, realizing the separation of the completed imprinting portion from the mold roller. Compared with the prior art, this invention effectively increases the filling height of the imprinting adhesive in the mold and also promotes the complete demolding of the cured imprinting adhesive from the mold, improving the processing quality of the nanoimprinting process.

Description

Technical Field

[0001] This invention belongs to the field of nanoimprint technology and relates to a roll-to-roll nanoimprint device and method. Background Technology

[0002] Nanoimprint lithography is an advanced manufacturing technology for creating micro- and nanoscale patterns, widely used in aerospace, flexible electronics, and optical devices. Compared to traditional photolithography, nanoimprint lithography offers advantages such as high resolution, high throughput, and low cost. Roll-to-roll nanoimprint lithography involves continuous imprinting between a roll-shaped die and a substrate, including roll-to-roll and roll-to-planar nanoimprint lithography. Compared to planar nanoimprint lithography, it offers the advantage of large-area nanoimprinting.

[0003] According to patent research, there are many types of mold roller designs and planar embossing demolding technologies for macroscopic manufacturing processes, but no patents have been reported for mold roller designs for large-area roll-to-roll nanoimprinting. For nanoimprinting processes, the embossing filling process and the demolding process directly affect the transfer quality of the nanostructures.

[0004] Among existing related technologies, patent CN101909859A proposes a nano-imprinting mold roller that facilitates mold roller replacement. It achieves mold roller loading, unloading, and fixation through the expansion and contraction of an elastic membrane in a fluid container, maintaining uniform thickness of the transferred film. However, it cannot provide positive and negative pressure at specific locations to promote imprinting and demolding, thus having limitations. Patent CN101249938A discloses a pneumatic micro-nano-imprinting demolding structure. It forms a closed space through a polymer clamping cover, injecting compressed gas through a demolding air channel. Utilizing the principle of fluid isobarism, it pushes the mold and polymer to separate smoothly, effectively preventing polymer deformation. However, this structure is only suitable for planar imprinting and cannot improve the quality of the imprinting filling. Patent CN110962450A discloses a roll-to-roll UV imprinting device and method with electric field-assisted filling and demolding. While it can reduce demolding defects and improve filling quality, the promoting effect of the electric field on demolding weakens after the UV adhesive cures, exhibiting certain limitations. Patent CN113075859A discloses a negative pressure nanoimprinting device and its imprinting method, suitable for nanostructures with greater depth. It can quickly create a negative pressure vacuum environment to promote imprinting filling, but it cannot effectively promote demolding. Patent CN116430670A proposes a demolding device for planar imprinting. By adjusting the vacuum pressure, it ensures uniform force on the product during demolding, improving quality. However, the design is limited to planar imprinting and cannot adjust local positive and negative pressure to simultaneously ensure imprinting and demolding quality. Patent CN211492476U discloses an automatic demolding nanoimprinting device. During demolding, the combined movement of the support mechanism creates an angle between the soft mold and the substrate, mitigating the influence of demolding force and adhesion force on the demolding process and improving the reusability of the soft mold. However, the mechanical peeling method may damage the nanostructure and is only suitable for roll-to-flat nanoimprinting devices.

[0005] Patent CN102866582A discloses a nanoimprinting device and method for patterning high-brightness LEDs. The device includes a substrate stage, a vacuum chuck, a substrate, and a UV-curable nanoimprinting resist. The mold is a thin-film elastic composite soft mold, comprising a pattern layer and a support layer. The pattern layer has water solubility, a thin-film structure, elasticity, and high transparency. The mold is manufactured using a roll embossing process. The method includes a pretreatment process, an embossing process, a curing process, a demolding process, a post-treatment process, and the transfer of the embossed pattern. However, this patent uses a planar-to-planar embossing method, which limits the embossing area and cannot be applied to large-area embossing. Furthermore, this patent utilizes the pressure difference of a vacuum negative pressure environment throughout the entire process to assist in the filling and demolding processes, which requires stringent conditions and is prone to uneven embossing and demolding forces, leading to defects such as bubbles.

[0006] Patent CN105159029A discloses a device and method for large-area micro / nano patterning. The device includes: a frame, a worktable, a substrate, an imprinting material, a soft mold, rollers, an ultraviolet light source, an imprinting mechanism, vacuum lines, and pressure lines. The method includes: pretreatment; imprinting and curing; demolding; and post-treatment. However, this patent uses a roller-to-planar imprinting method, with the soft mold attached to the rollers. This separate design not only limits the imprinting area but also easily causes displacement when the rollers adsorb or lay the mold flat, affecting the quality of the nanostructure. Furthermore, the purpose of the positive and negative pressure conversion in this patent is to allow the soft mold to lay flat or detach from the imprinting material. The imprinting force and demolding force are provided by the line contact pressure of the rollers, which does not assist in imprinting or demolding, thus hindering the filling and complete demolding of the structure.

[0007] In summary, existing technologies for roll-to-roll nanoimprinting equipment and processes have certain limitations. In terms of technical approach, most employ roll-to-plane or plane-to-plane imprinting, which cannot achieve large-area imprinting. During the imprinting filling stage, microstructures are difficult to fill completely, potentially resulting in structural defects such as air bubbles. During the demolding stage, the lack of suitable separation methods means that traditional mechanical peeling can lead to incomplete demolding of nanostructures, resulting in defects such as nanostructure breakage and cracking. Summary of the Invention

[0008] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a roll-to-roll nanoimprinting device and method. This invention effectively increases the filling height of the imprinting adhesive in the mold and can also promote the complete demolding of the cured imprinting adhesive from the mold, thereby improving the processing quality of the nanoimprinting process.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] One of the technical solutions of the present invention is to provide a roll-to-roll nanoimprinting device, which includes an impression roller, a mold roller, an auxiliary impression roller group, and a release roller. The mold roller cooperates with the impression roller and the release roller at the in-winding and rewinding points, respectively. The mold roller is connected to a bidirectional air pump through an airflow regulator. The adsorption state of the mold roller is adjusted by the bidirectional air pump and the airflow regulator to assist in positive and negative pressure gas filling and demolding, thereby improving the filling quality and demolding quality, and thus improving the transfer quality of nanostructures. The impression roller and the release roller are both connected to the air pump. A UV curing module is provided on the auxiliary impression roller group.

[0011] At the winding point, the positive pressure of the impression roller and the negative pressure of the die roller provide the imprinting force. The auxiliary impression roller group with a UV curing module is used for auxiliary filling and curing. At the winding point, the negative pressure of the demolding roller and the positive pressure of the die roller provide the demolding force, so as to separate the imprinted part from the die roller.

[0012] As a preferred technical solution, the airflow regulator is located on the side of the mold roller and is connected to the mold roller through a sealing ring to prevent the positive and negative pressure environments from being disturbed by external air pressure.

[0013] As a preferred technical solution, the device further includes a coating component, which includes a dispensing device and a thickness adjustment roller. The dispensing device supplies imprinting adhesive to the substrate film, the amount of adhesive dispensed at each position is adjusted according to the target structure, and the adhesive is applied in a distributed dispensing manner. The thickness adjustment roller coats the imprinting adhesive evenly on the substrate film to a certain thickness.

[0014] As a preferred technical solution, the thickness adjustment rollers are provided in a pair, including a first thickness adjustment roller and a second thickness adjustment roller. The first thickness adjustment roller is disposed above the substrate film, and the second thickness adjustment roller is disposed below the substrate film. The thickness of the printing adhesive on the substrate film is adjusted by adjusting the distance between the pair of thickness adjustment rollers.

[0015] Furthermore, the mold roller is equipped with a gas pipeline and a drive module. The mold roller is connected to an airflow regulator through the gas pipeline, and the airflow regulator is connected to a bidirectional air pump. The mold roller is driven to rotate by the drive module.

[0016] Furthermore, the outer surface of the mold roller is provided with a template area, and a mold suction hole area is provided outside the template area. The template area transfers the nanostructure onto the substrate film, and the mold suction hole area is connected to the gas pipeline of the mold roller to allow airflow and adjust the adsorption state of the mold roller.

[0017] Furthermore, the mold suction hole area and the mold plate area are distributed axially or circumferentially according to actual production needs. When the molding target has high requirements for large area, the axial distribution is selected, and when the molding target has high requirements for continuity, the circumferential distribution is selected.

[0018] Furthermore, the gas pipeline of the mold roller is connected to the mold suction hole area through a gas guide. The gas guide is evenly distributed along the circumference of the mold roller cross section. Each gas guide has a corresponding airflow regulator that controls the pressure in the gas guide. According to the processing stage, the positive and negative pressure at each position of the mold suction hole area is controlled by a corresponding bidirectional air pump.

[0019] The gas guide, in conjunction with the airflow regulator, divides the mold suction holes on the mold roller surface into two areas: a filling area and a demolding area, with opposite air pressure properties. Two bidirectional air pumps are used to reverse the positive and negative pressure states of the corresponding control areas. Since the two areas have opposite air pressure states, the airflow regulator is used to separate the ranges of the positive and negative pressure areas on the mold roller and regulate the gas flow rate. The gas guide, through the airflow regulator, creates a continuous negative pressure in the mold suction hole area on the surface, forming a negative pressure vacuum zone in the filling area. This prevents air bubbles from forming due to residual gas during the filling process of the imprinting adhesive, which is beneficial for improving filling quality and the fabrication of nanostructures with larger aspect ratios, achieving pattern transfer in the mold area on the mold roller. After the imprinting adhesive cures, the demolding area on the mold roller, covered with the transferred material, is subjected to positive air pressure through the bidirectional air pump and airflow regulator, and in conjunction with the demolding roller and tension adjustment roller, generates the required demolding force, promoting the demolding process and achieving non-destructive separation of the nanostructures.

[0020] The mold roller has different air pressure distribution in different areas; by designing the internal gas guide of the mold roller and adjusting the bidirectional air pump and coded airflow regulator, the mold roller provides positive air pressure in the area where demolding is required and negative air pressure in the area where filling is required; after a working cycle, the functions of the areas are interchanged and the bidirectional air pump is reversed to realize the positive and negative pressure conversion of the mold suction hole area on the mold roller.

[0021] Furthermore, the drive module adopts a step-type printing process, which ensures that the printing adhesive can be fully filled under negative pressure and the action of auxiliary printing rollers during the process, thus ensuring structural quality. During the stopping process, the printing adhesive has enough time to be exposed to ultraviolet light, ensuring complete curing. The advantage of the step-type printing process is that it can form a stable periodic production, improving the quality and efficiency of the transfer printing.

[0022] Furthermore, the outer surface of the impression roller is provided with impression suction holes, which are connected to an air pump through a gas pipeline to provide positive pressure, which works in conjunction with the negative pressure of the mold roller to provide basic impression force;

[0023] The outer surface of the demolding roller is distributed with demolding suction holes. These holes are connected to an air pump via a gas pipeline to provide negative pressure. This negative pressure, combined with the positive pressure of the mold roller, provides a basic demolding force, which promotes the complete demolding of the cured embossed adhesive from the mold, thereby improving the demolding quality.

[0024] As a preferred technical solution, the imprint roller is a flexible roller, which adapts to the unevenness of the substrate film and improves the imprint quality.

[0025] Furthermore, the auxiliary impression roller group includes auxiliary impression rollers, hydraulic devices, and a support frame. Multiple auxiliary impression rollers and UV curing modules are arranged on the support frame. The auxiliary impression rollers are arranged circumferentially along the support frame at the same spacing. The UV curing modules are equidistantly distributed among the auxiliary impression rollers. The distance between the auxiliary impression roller group and the mold roller is adjusted by the hydraulic device according to the processing stage.

[0026] As a preferred technical solution, the UV curing module includes a high-pressure mercury lamp UV (ultraviolet) lamp or a UV-LED (ultraviolet-light-emitting diode) curing light source.

[0027] As a preferred technical solution, the auxiliary impression rollers are arranged circumferentially along the support frame at the same interval via hinges, universal joints, or ball bearings.

[0028] As a preferred technical solution, the hydraulic actuators are located at both ends of the support frame.

[0029] Furthermore, the support frame is arc-shaped and conforms to the curve of the mold roller. The distance between the auxiliary imprint roller and the support frame decreases from the in-winding point to the rewinding point along the circumference of the support frame, so as to ensure that the auxiliary imprint roller conforms to the mold roller in sequence, thereby avoiding interference between the imprinting and filling process of the next cycle and the demolding process of the previous cycle.

[0030] As a preferred technical solution, the auxiliary impression roller is connected to the support frame through an elastic element, which adopts a combination structure of spring and damping to provide adaptive impression force load.

[0031] As a preferred technical solution, the auxiliary impression roller assembly has a structure that includes either a roller type or a track type to adapt to different production needs.

[0032] During the filling process, in the first step, the UV curing module is turned off, and the auxiliary impression roller group is driven by a hydraulic device to sequentially adhere to the mold roller at the corresponding positions, starting from the in-wound position, providing positive pressure to assist in filling and ensure complete filling. Since the filling stage starts from the in-wound position, while the rewinding position is undergoing demolding, sequential adhesion ensures that positive pressure is first applied to the already filled portion at the in-wound position during the stepping process, while no force is applied to the demolding at the rewinding position, avoiding interference between the next cycle's impression filling process and the previous cycle's demolding process. After filling is completed, the second step begins, the device stops rotating, the UV curing module is activated, and the impression adhesive cures. After curing is completed, the auxiliary impression roller group is moved away from the mold roller by a hydraulic device to avoid interfering with the demolding process and to prepare for the next cycle's stepping impression process.

[0033] As a preferred technical solution, the device further includes a tension adjusting roller, on which an imprinted substrate film is fitted. Together with the demolding roller, the film is driven to demold and rewind. The tension is adjusted by adjusting the distance between the demolding roller and the tension adjusting roller.

[0034] As a preferred technical solution, the tension adjusting rollers are provided in a pair, including a first tension adjusting roller and a second tension adjusting roller. The first tension adjusting roller causes the imprinted substrate film to be pulled out horizontally from behind the demolding roller, and the second tension adjusting roller causes the imprinted substrate film to be pulled out vertically from behind the first tension adjusting roller and the winding direction to be changed.

[0035] One of the technical solutions of the present invention is to provide a roll-to-roll nanoimprinting method, which uses the aforementioned device to imprint nanostructures, and the method includes the following steps:

[0036] S1. Coating process: The imprinting adhesive is evenly spread on the surface of the substrate film.

[0037] S2. During the filling process, when the coated substrate film enters the imprint roller area, the imprint roller approaches the mold roller, generating imprinting force. At this time, the imprint roller continuously inputs positive air pressure, and the mold roller in contact with the substrate film continuously provides negative air pressure to ensure a negative pressure environment during filling. As filling progresses, the auxiliary imprint roller group sequentially adheres to the mold roller according to the corresponding positions to provide positive pressure and ensure that filling is completed smoothly.

[0038] S3. Curing process: When the auxiliary imprint roller group is fully in contact with the substrate film being filled, the ultraviolet curing process begins. At this time, the overall displacement of the device remains unchanged. The UV curing module located on the auxiliary imprint roller group is activated until the imprinting adhesive is completely cured, thus realizing the transfer of nanostructures.

[0039] S4. Demolding process: After the nanostructure transfer is completed, the auxiliary impression roller group moves away from the mold roller; the area on the mold roller covered with the transferred substrate film is subjected to positive air pressure through a bidirectional air pump and airflow regulator, so that the substrate film with nanostructure is initially separated from the mold roller; then the device is started, the demolding roller provides negative air pressure, which works with the mold roller to generate demolding force, so that the substrate film is completely separated from the mold roller; at the same time, the substrate film that enters later enters a new filling cycle;

[0040] S5. Rewinding process: After the demolding process is completed, a periodic nanostructure is formed on the substrate film, and demolding and rewinding are completed under the action of the rewinding roller.

[0041] As a preferred technical solution, the spacing of the thickness adjustment rollers is adjusted in advance before the printing begins, and the printing roller, mold roller, auxiliary printing roller group and demolding roller all operate at the same linear speed.

[0042] As a preferred technical solution, the imprinting adhesive includes a UV-curable polyacrylic resin, a UV-curable polyurethane acrylate, or a UV-curable epoxy resin, which can be cured under UV curing module irradiation to successfully transfer nanostructures. The material of the substrate film includes polyethylene terephthalate (PET), polycarbonate (PC), or thermoplastic polyurethane elastomer (TPU) substrate.

[0043] As a preferred technical solution, the device performs the pre-curing process at a slower speed.

[0044] As a preferred technical solution, demolding and winding are completed under the action of tension adjusting roller and winding roller.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) In the filling process, the mold roller provides a negative pressure environment, while the impression roller and the auxiliary impression roller group provide the impression force, which effectively improves the filling height of the impression adhesive in the mold, solves the defects such as incomplete filling of nanostructure and air bubbles in the filling process, and improves the filling quality of large-area nanostructure in roll-to-roll nanoimprinting process.

[0047] (2) In the demolding process, the mold roller provides a positive pressure environment, and the demolding roller provides demolding force, which promotes the complete demolding of the cured embossing adhesive from the mold, solves the defects such as nanostructure breakage and cracking during demolding, and improves the demolding quality of large-area nanostructures in roll-to-roll nanoimprinting process.

[0048] (3) The transfer process of the present invention is an adjustable step-by-step process, which ensures that the printing adhesive is fully cured and completely transferred during the filling process. At the same time, it has strong adjustability and integration. Combined with the innovative positive and negative pressure design, it improves the transfer quality of large-area roll-to-roll nanoimprinting process. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the roll-to-roll nanoimprinting device in an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the circumferentially distributed mold rollers in an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of the axially distributed mold rollers in an embodiment of the present invention;

[0052] Figure 4 This is a schematic diagram of the structure of the impression roller and the release roller in an embodiment of the present invention;

[0053] Figure 5 This is a scanning electron microscope (SEM) image of the moth-eye nanoarray structure in an embodiment of the present invention.

[0054] Explanation of markings in the diagram:

[0055] 1—Dispenser, 2—First thickness adjustment roller, 3—Second thickness adjustment roller, 4—Substrate film, 5—Impression roller, 511—Impression suction area, 6—Mold roller, 611—Mold suction area, 612—Mold area, 7—Auxiliary impression roller group, 701—Auxiliary impression roller, 702—UV curing module, 703—Hydraulic unit, 704—Support frame, 8—Demolding roller, 811—Demolding suction area, 9—First tension adjustment roller, 10—Second tension adjustment roller. Detailed Implementation

[0056] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0057] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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. Furthermore, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and do not imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] Example:

[0060] A roll-to-roll nanoimprinting device, such as Figure 1As shown, it includes an impression roller 5, a mold roller 6, an auxiliary impression roller group 7, and a demolding roller 8. The mold roller 6 cooperates with the impression roller 5 and the demolding roller 8 at the in-winding and rewinding points, respectively. The mold roller 6 is connected to a bidirectional air pump through an airflow regulator. The adsorption state of the mold roller 6 is adjusted by the bidirectional air pump and the airflow regulator to assist in positive and negative pressure gas filling and demolding, thereby improving the filling quality and demolding quality, and thus improving the transfer quality of nanostructures. The impression roller 5 and the demolding roller 8 are both connected to the air pump. A UV curing module 702 is provided on the auxiliary impression roller group 7.

[0061] In this embodiment, the maximum pressure provided by the (bidirectional) air pump is 0.1 MPa, and the maximum power of the UV curing module 702 is 200 mW / cm². 2 ;

[0062] At the in-winding point, the positive pressure of the impression roller 5 and the negative pressure of the die roller 6 provide the impression force. The auxiliary impression roller group 7 containing the UV curing module 702 is used for auxiliary filling and curing. At the winding point, the negative pressure of the demolding roller 8 and the positive pressure of the die roller 6 provide the demolding force, so as to separate the impression completed part from the die roller 6.

[0063] The airflow regulator is located on the side of the mold roller 6 and is connected to the mold roller 6 through a sealing ring to prevent the positive and negative pressure environments from being disturbed by external air pressure.

[0064] The apparatus also includes a coating assembly, which includes a dispensing device 1 and a thickness adjustment roller. The dispensing device 1 supplies imprinting adhesive to the substrate film 4. The amount of adhesive dispensed at each position is adjusted according to the target structure. The adhesive is applied using a distributed dispensing method. The thickness adjustment roller coats the imprinting adhesive evenly on the substrate film 4 to a thickness of less than 5 μm.

[0065] A pair of thickness adjustment rollers are provided, including a first thickness adjustment roller 2 and a second thickness adjustment roller 3. The first thickness adjustment roller 2 is located above the substrate film 4, and the second thickness adjustment roller 3 is located below the substrate film 4. The thickness of the printing adhesive on the substrate film 4 is adjusted by adjusting the distance between the pair of thickness adjustment rollers.

[0066] The mold roller 6 is equipped with a gas pipeline and a drive module. The mold roller 6 is connected to the airflow regulator through the gas pipeline. The airflow regulator is connected to the bidirectional air pump. The mold roller 6 is driven to rotate by the drive module.

[0067] like Figure 2 and Figure 3 As shown, the outer surface of the mold roller 6 is provided with a template area 612, and the outside of the template area 612 is provided with a mold suction hole area 611. The template area 612 transfers the nanostructure onto the substrate film 4, and the mold suction hole area 611 is connected to the gas pipeline of the mold roller 6 to allow airflow and adjust the adsorption state of the mold roller 6.

[0068] In this embodiment, the template area 612 is an anodized aluminum template covering the surface of the mold roller 6. The surface feature structure of the anodized aluminum template is a nano-random micropore array structure. The pore depth of the nano-random micropore array structure is 50-500nm, and is preferably 350nm in this embodiment.

[0069] The mold suction area 611 and the template area 612 are distributed axially or circumferentially according to actual production needs. When the molding target has high requirements for large area, the axial distribution is selected. When the molding target has high requirements for continuity, the circumferential distribution is selected. In this embodiment, for the moth eye nanoarray structure, which has high requirements for continuity, the circumferentially distributed mold roller 6 is designed to transfer the nanostructure.

[0070] The gas pipeline of the mold roller 6 is connected to the mold suction hole area 611 through the gas guide. The gas guide is evenly distributed along the circumference of the cross section of the mold roller 6. Each gas guide is controlled by a corresponding airflow regulator to control the pressure in the gas guide. According to the processing stage, the positive and negative pressure at each position of the mold suction hole area 611 is controlled by a corresponding bidirectional air pump.

[0071] The gas guide, in conjunction with the airflow regulator, divides the mold suction hole area 611 on the surface of the mold roller 6 into two regions: a filling area and a demolding area. These two regions have opposite air pressure properties. Two bidirectional air pumps are used to reverse the positive and negative pressure states of the corresponding control areas. Since the two regions have opposite air pressure states, the airflow regulator is used to separate the ranges of the positive and negative pressure areas on the mold roller 6 and regulate the gas flow rate. The gas guide can create a continuous negative pressure in the mold suction hole area 611 on the surface through the airflow regulator, forming a negative pressure vacuum area in the filling area. This prevents the imprinting adhesive from generating bubbles due to residual gas during the filling process, which is beneficial for improving the filling quality and the fabrication of nanostructures with larger aspect ratios. It can also better realize the pattern transfer of the template area 612 on the mold roller 6. After the imprinting adhesive has cured, the demolding area on the mold roller 6, which is covered with the transferred material, is subjected to positive air pressure through the bidirectional air pump and the airflow regulator. In conjunction with the demolding roller 8 and the tension adjustment roller, it generates the required demolding force, promotes the demolding process, and achieves the non-destructive separation of nanostructures.

[0072] The air pressure distribution in different areas of the mold roller 6 is different. By designing the internal gas guide of the mold roller 6 and adjusting the bidirectional air pump and the coded airflow regulator, the mold roller 6 can provide positive air pressure in the area where demolding is required and negative air pressure in the area where filling is required. After a working cycle, the functions of the areas are interchanged and the bidirectional air pump is reversed to realize the positive and negative pressure change of the mold suction hole area 611 on the mold roller 6.

[0073] The drive module uses a step-type printing process, which ensures that the printing adhesive can be fully filled under negative pressure and the action of the auxiliary printing roller group 7 during the process, thus ensuring structural quality. During the stopping process, the printing adhesive can be exposed to ultraviolet light for a sufficient time to ensure complete curing. The advantage of the step-type printing process is that it can form a stable periodic production, improving the quality and efficiency of the transfer.

[0074] like Figure 4 As shown, the outer surface of the impression roller 5 is distributed with impression suction holes 511. The impression suction holes 511 are connected to the air pump through the gas pipeline to provide positive pressure, which cooperates with the negative pressure of the mold roller 6 to provide basic impression force. At the same time, the impression roller 5 is a flexible roller, which can adapt to the unevenness of the substrate film 4 and improve the impression quality.

[0075] The outer surface of the demolding roller 8 is distributed with demolding suction hole areas 811. The demolding suction hole areas 811 are connected to the air pump through the gas pipeline to provide negative pressure. This negative pressure, combined with the positive pressure of the mold roller 6, provides the basic demolding force, which promotes the complete demolding of the cured imprinted adhesive from the mold and improves the demolding quality.

[0076] The auxiliary impression roller group 7 includes auxiliary impression rollers 701, hydraulic device 703 and support frame 704. Multiple auxiliary impression rollers 701 and UV curing modules 702 are arranged on the support frame 704. The auxiliary impression rollers 701 are arranged at the same interval along the circumference of the support frame 704. The UV curing modules 702 are equidistantly distributed between the auxiliary impression rollers 701. The distance between the auxiliary impression roller group 7 and the mold roller 6 is adjusted by the hydraulic device 703 according to the processing stage.

[0077] The UV curing module 702 includes a high-pressure mercury lamp UV (ultraviolet) lamp or a UV-LED (ultraviolet-light-emitting diode) curing light source, and in this embodiment, a high-pressure mercury lamp UV lamp is preferred.

[0078] The auxiliary impression rollers 701 are arranged circumferentially along the support frame 704 at the same interval via hinges, universal joints or ball bearings, preferably hinges in this embodiment;

[0079] Hydraulic units 703 are located at both ends of the support frame 704;

[0080] The support frame 704 is arc-shaped and conforms to the curve of the mold roller 6. The distance between the auxiliary imprint roller 701 and the support frame 704 decreases from the in-winding point to the rewinding point along the circumference of the support frame 704, so as to ensure that the auxiliary imprint roller 701 conforms to the mold roller 6 in sequence, thereby avoiding the mutual interference between the imprinting and filling process of the next cycle and the demolding process of the previous cycle.

[0081] The auxiliary impression roller 701 is connected to the support frame 704 through an elastic element. The elastic element is a combination of spring and damping structure to provide an adaptive impression force load of up to 0.1 MPa.

[0082] The auxiliary impression roller group 7 has a structure that can be either roller type or track type to adapt to different production needs. In this embodiment, the auxiliary impression roller group 7 adopts a roller type structure.

[0083] During the filling process, in the first step, the UV curing module 702 is turned off, and the auxiliary impression roller group 7 is driven by the hydraulic device 703 to sequentially adhere to the mold roller 6 from the leftmost in-wound position, providing positive pressure to assist in filling and ensure complete filling. Since the filling stage starts from the leftmost in-wound position, while the rightmost rewind position is demolding, sequential adhesion ensures that positive pressure is first applied to the already filled part at the left in-wound position during the stepping process, while no force is applied to the demolding at the right rewind position, avoiding interference between the next cycle's impression filling process and the previous cycle's demolding process. After filling is completed, the second step begins, the device stops rotating, the UV curing module 702 is activated, and the impression adhesive is cured. After curing is completed, the auxiliary impression roller group 7 is moved away from the mold roller 6 by the hydraulic device 703 to avoid interfering with the demolding process and to prepare for the next cycle's stepping impression process.

[0084] The device also includes a tension adjusting roller, on which the imprinted substrate film 4 is fitted. Together with the demolding roller 8, it drives demolding and winding. The tension is adjusted by adjusting the distance between the demolding roller 8 and the tension adjusting roller.

[0085] A pair of tension adjusting rollers are provided, including a first tension adjusting roller 9 and a second tension adjusting roller 10. The first tension adjusting roller 9 causes the imprinted substrate film 4 to be pulled out horizontally from behind the demolding roller 8, and the second tension adjusting roller 10 causes the imprinted substrate film 4 to be pulled out vertically from behind the first tension adjusting roller 9 and changes the winding direction.

[0086] A roll-to-roll nanoimprinting method, using the above-mentioned device to imprint nanostructures, comprises the following specific steps:

[0087] Before the printing begins, adjust the spacing of the thickness adjustment rollers in advance. The printing roller 5, the mold roller 6, the auxiliary printing roller group 7, and the demolding roller 8 all work at the same linear speed.

[0088] A photocurable polyacrylic resin is selected from photocurable polyacrylic resin, photocurable polyurethane acrylate or photocurable epoxy resin as the imprinting adhesive, which can be cured under the irradiation of UV curing module 702 to successfully transfer nanostructures. A PET substrate is selected from polyethylene terephthalate (PET), polycarbonate (PC) or thermoplastic polyurethane elastomer (TPU) substrate as the material of substrate film 4.

[0089] S1. Coating process: Imprint adhesive is supplied to substrate film 4 through dispensing device 1. The amount of adhesive dispensed at each position is adjusted according to the target structure. Distributed dispensing method is used for adhesive application. The device performs pre-curing process at a slower speed. At the same time, the imprint adhesive is evenly spread on the surface of substrate film 4.

[0090] S2. During the filling process, when the coated substrate film 4 enters the area of ​​the impression roller 5, the impression roller 5 approaches the mold roller 6, generating an impression force. At this time, the impression roller 5 continuously inputs positive air pressure, and the mold roller 6, which is in contact with the substrate film 4, continuously provides negative air pressure to ensure a negative pressure environment during filling. As filling proceeds, the auxiliary impression roller group 7 sequentially attaches to the mold roller 6 at the corresponding positions (the left end of the winding position approaches the mold roller 6 first) to provide positive pressure and ensure that filling is completed smoothly.

[0091] S3. Curing process: When the auxiliary imprint roller group 7 is fully in contact with the substrate film 4 being filled, the ultraviolet curing process begins. At this time, the overall displacement of the device remains unchanged, and the UV curing module 702 located on the auxiliary imprint roller group 7 is activated until the imprinting adhesive is completely cured, thus realizing the transfer of nanostructures.

[0092] S4. Demolding process: After the nanostructure transfer is completed, the auxiliary impression roller group 7 moves away from the mold roller 6; the area on the mold roller 6 covered with the transferred substrate film 4 is subjected to positive air pressure through a bidirectional air pump and airflow regulator, so that the substrate film 4 with nanostructure is initially separated from the mold roller 6; then the device is started, the demolding roller 8 provides negative air pressure, and works with the mold roller 6 to generate demolding force, so that the substrate film 4 is completely separated from the mold roller 6; at the same time, the substrate film 4 that enters later enters a new filling cycle;

[0093] S5. Rewinding process: After the demolding process is completed, a periodic moth-eye nanoarray structure is formed on the substrate film 4. Demolding and rewinding are completed under the action of tension adjustment roller and rewinding roller.

[0094] like Figure 5 As shown, under a scanning electron microscope (SEM), the micropore depth of the mold is 350 nm, and the height of the moth-eye structure obtained by imprinting is 300-350 nm, with a regular array arrangement, which proves that the periodic moth-eye nanoarray structure has been successfully prepared.

[0095] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A roll-to-roll nanoimprinting device, characterized in that, The device includes an impression roller (5), a mold roller (6), an auxiliary impression roller group (7), and a demolding roller (8). The mold roller (6) cooperates with the impression roller (5) and the demolding roller (8) at the winding and unwinding points, respectively. The mold roller (6) is connected to a bidirectional air pump through an airflow regulator. The adsorption state of the mold roller (6) is adjusted by the bidirectional air pump and the airflow regulator to assist in positive and negative pressure gas filling and demolding, thereby improving the filling quality and demolding quality, and thus improving the transfer quality of nanostructures. The impression roller (5) and the demolding roller (8) are both connected to the air pump. The auxiliary impression roller group (7) is equipped with a UV curing module (702). At the in-winding point, the positive pressure of the impression roller (5) and the negative pressure of the mold roller (6) provide the impression force. The auxiliary impression roller group (7) containing the UV curing module (702) is used for auxiliary filling and curing. At the winding point, the negative pressure of the demolding roller (8) and the positive pressure of the mold roller (6) provide the demolding force, so as to realize the separation of the impression completed part from the mold roller (6). The mold roller (6) is provided with a gas pipeline and a drive module. The mold roller (6) is connected to an airflow regulator through the gas pipeline. The airflow regulator is connected to a bidirectional air pump. The mold roller (6) is driven to rotate by the drive module. The outer surface of the mold roller (6) is provided with a template area (612), and a mold suction hole area (611) is provided outside the template area (612). The template area (612) transfers the nanostructure onto the substrate film (4). The mold suction hole area (611) is connected to the gas pipeline of the mold roller (6) to allow airflow and adjust the adsorption state of the mold roller (6). The mold suction hole area (611) and the template area (612) are distributed axially or circumferentially; The gas pipeline of the mold roller (6) is connected to the mold suction hole area (611) through the gas guide. The gas guide is distributed circumferentially along the cross section of the mold roller (6). Each gas guide is controlled by a corresponding airflow regulator. The positive and negative pressure of each position of the mold suction hole area (611) is controlled by a corresponding bidirectional air pump according to the processing stage. The gas guide, in conjunction with the airflow regulator, divides the mold suction hole area (611) on the surface of the mold roller (6) into two regions: the filling area and the demolding area. The two regions have opposite air pressure properties. The bidirectional air pump is used to reverse the positive and negative pressure states of the corresponding control areas. Two pumps are provided. Since the two regions have opposite air pressure states, the airflow regulator is used to divide the range of the positive and negative pressure areas on the mold roller (6) and regulate the gas flow rate. The gas guide forms a continuous negative pressure in the mold suction hole area (611) on the surface through the airflow regulator. A negative pressure vacuum zone is formed in the filling area to prevent the printing adhesive from generating bubbles due to residual gas during the filling process. This is beneficial to improving the filling quality and the fabrication of nanostructures with a larger aspect ratio, and to realize the pattern transfer of the template area (612) on the mold roller (6). After the printing adhesive is cured, the demolding area covered with the transferred material on the mold roller (6) is subjected to positive air pressure through a bidirectional air pump and airflow regulator, and cooperates with the demolding roller (8) and tension adjustment roller to generate the required demolding force, promote the demolding process, and realize the non-destructive separation of nanostructures. The pressure distribution of the mold roller (6) is different in different areas; by designing the gas guide inside the mold roller (6) and adjusting the bidirectional air pump and the coded airflow regulator, the mold roller (6) provides positive air pressure in the area where demolding is required and negative air pressure in the area where filling is required; after a working cycle, the functions of the areas are interchanged and the bidirectional air pump is reversed to realize the positive and negative pressure change of the mold suction hole area (611) on the mold roller (6); The drive module adopts step-type printing, which ensures that the printing adhesive can be fully filled under negative pressure and the action of auxiliary printing roller group (7) during the process of moving, thus ensuring the structural quality; during the stopping process, the printing adhesive can have enough time to be exposed to ultraviolet light, thus ensuring that the printing adhesive is fully cured; the advantage of the step-type printing process is that it can form a stable periodic production, improving the quality and efficiency of the transfer printing. The outer surface of the impression roller (5) is provided with an impression suction area (511). The impression suction area (511) is connected to an air pump through a gas pipeline to provide positive pressure, which cooperates with the negative pressure of the mold roller (6) to provide basic impression force. The outer surface of the demolding roller (8) is provided with demolding suction hole area (811). The demolding suction hole area (811) is connected to the air pump through the gas pipeline to provide negative pressure. It cooperates with the mold roller (6) with positive pressure to provide basic demolding force, so as to promote the complete demolding of the cured imprinted adhesive from the mold and improve the demolding quality. The auxiliary impression roller group (7) includes auxiliary impression rollers (701), hydraulic device (703) and support frame (704). Multiple auxiliary impression rollers (701) and UV curing modules (702) are provided on the support frame (704). The auxiliary impression rollers (701) are arranged circumferentially along the support frame (704) at the same interval. The UV curing modules (702) are equidistantly distributed between the auxiliary impression rollers (701). The distance between the auxiliary impression roller group (7) and the mold roller (6) is adjusted by the hydraulic device (703) according to the processing stage. The support frame (704) is arc-shaped and conforms to the curve of the mold roller (6). The distance between the auxiliary imprint roller (701) and the support frame (704) decreases from the in-winding point to the rewinding point along the circumference of the support frame (704) to ensure that the auxiliary imprint roller (701) conforms to the mold roller (6) in sequence, thereby avoiding interference between the imprinting and filling process of the next cycle and the demolding process of the previous cycle. During the filling process, in the first step, the UV curing module (702) is turned off, and the auxiliary imprinting roller group (7) is driven by the hydraulic device (703) to sequentially adhere to the mold roller (6) at the corresponding positions starting from the in-wound position, providing positive pressure to assist in filling and ensure complete filling. Since the filling stage starts from the in-wound position, while the rewinding position is demolding, sequential adhesion can ensure that positive pressure is provided to the already filled part at the in-wound position during the stepping process, while no force is applied to the demolding at the rewinding position, thus avoiding interference between the imprinting and filling process of the next cycle and the demolding process of the previous cycle. After the filling is completed, the second step begins, the device stops rotating, the UV curing module (702) is started, and the imprinting adhesive is cured. After curing, the auxiliary imprinting roller group (7) is moved away from the mold roller (6) by the hydraulic device (703) to avoid interfering with the demolding process and to prepare for the next stepping imprinting process. During the filling process, the mold roller (6) provides a negative pressure environment, while the impression roller (5) and the auxiliary impression roller group (7) provide the impression force, which effectively increases the filling height of the impression adhesive in the mold, solves the defects such as incomplete filling of nanostructure and air bubbles during the filling process, and improves the filling quality of large-area nanostructures in roll-to-roll nanoimprinting process. During the demolding process, the mold roller (6) provides a positive pressure environment, while the demolding roller (8) provides demolding force, which promotes the complete demolding of the cured embossed adhesive from the mold, solves the defects such as nanostructure breakage and cracking during the demolding process, and improves the demolding quality of large-area nanostructures in roll-to-roll nanoimprinting process. The transfer process is an adjustable step-by-step process, which ensures that the imprinting adhesive is fully cured and completely transferred during the filling process. At the same time, it has strong adjustability and integration, and with the innovative positive and negative pressure design, it improves the transfer quality of large-area roll-to-roll nanoimprinting technology.

2. A roll-to-roll nanoimprinting method, characterized in that, This method uses the apparatus of claim 1 to perform imprinting of nanostructures, the method comprising the following steps: S1. Coating process: The printing adhesive is spread on the surface of the substrate film (4); S2, during the filling process, when the coated substrate film (4) enters the area of ​​the impression roller (5), the impression roller (5) continuously inputs positive air pressure, and the mold roller (6) in contact with the substrate film (4) continuously provides negative air pressure to ensure a negative pressure environment during filling; as filling proceeds, the auxiliary impression roller group (7) sequentially attaches to the mold roller (6) according to the corresponding positions to provide positive pressure and ensure that filling is completed; S3, Curing process: When the auxiliary imprint roller group (7) is fully in contact with the substrate film (4) to be filled, the UV curing process begins; at this time, the overall displacement of the device remains unchanged, and the UV curing module (702) located on the auxiliary imprint roller group (7) is started until the imprinting adhesive is completely cured, thus realizing the transfer of nanostructures; S4. Demolding process: After the nanostructure transfer is completed, the auxiliary impression roller group (7) moves away from the mold roller (6); the area on the mold roller (6) covered with the transferred substrate film (4) is subjected to positive air pressure by a bidirectional air pump and airflow regulator, so that the substrate film (4) with nanostructure is initially separated from the mold roller (6); then the device is started, the demolding roller (8) provides negative air pressure, and works with the mold roller (6) to generate demolding force, so that the substrate film (4) is completely separated from the mold roller (6); at the same time, the substrate film (4) that enters later enters a new filling cycle; S5. Rewinding process: After the demolding process is completed, a periodic nanostructure is formed on the substrate film (4), and demolding and rewinding are completed under the action of the rewinding roller.

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