Method of applying coating composition to substrate using high transfer efficiency applicator

Abstract

The invention discloses a method of forming a coating on a substrate. The method provides controlled application of overlapping strips to reduce significant overlapping areas. The method comprises: providing a high transfer efficiency applicator; receiving the image data and a predefined non-linear laying pattern; determining a plurality of overlapping strips, each strip being processable by at least one printhead and forming an overlapping region with an adjacent strip; distributing each overlapping area between adjacent strips, and distributing complementary parts of the non-linear laying pattern to the adjacent strips; applying a coating composition to at least one first strip using the applicator and forming a first portion of the non-linear lay-up pattern in at least one overlapping region thereof; and applying the coating composition to at least one second strip and forming a second portion of the non-linear lay-up pattern in the at least one overlap region.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 510,295, filed June 26, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to a method of applying a coating composition to a substrate using a high-transfer-efficiency applicator to form a coating, and more specifically, to a method comprising selectively controlling the application of an overlap strip to form a continuous layer in the resulting coating with a significantly reduced overlap area. Background Technology

[0004] Microdroplet ejectors are now widely used, both in more traditional applications (such as inkjet printing) and in 3D printing and other rapid prototyping technologies. Fluids (such as ink) can thus acquire new chemical properties to adhere to new substrates and enhance the functionality of the deposited material. Microdroplet ejectors have been developed for industrial applications, such as direct printing onto substrates like ceramic tiles or textiles, or for forming components such as color filters for LCD or OLED displays in flat-panel TVs. This industrial printing technology using microdroplet ejectors allows for small-batch production, product customization services, and even custom-designed printing services. Therefore, it is understandable that microdroplet ejectors are constantly evolving and specializing to adapt to new and / or increasingly challenging applications. However, despite the significant progress made in the field of microdroplet ejectors, there is still room for improvement.

[0005] In recent years, there has been increasing interest in printing on more complex and / or large-scale shapes, such as three-dimensional objects, or surfaces like walls, or objects like vehicles; these surfaces are referred to herein as complex substrates. Printing on such complex substrates may involve printing on one or more non-horizontal surfaces, such as vertical surfaces, surfaces angled to the horizontal, curved surfaces, and complex shapes containing multiple surfaces with different orientations. Previously, some of these complex substrates have been coated using techniques such as spray painting, but this can be undesirable due to the release of large amounts of fine fluid particles into the atmosphere, which can be difficult or costly to handle to prevent environmental damage or operator injury. Therefore, printing on complex and / or large-scale shapes and surfaces using microdroplet nozzles has attracted interest because it allows for targeted and controlled printing on surfaces without releasing large amounts of fine particles into the surrounding area, which may require costly mitigation measures to ensure operator safety or for environmental reasons. This technology also reduces the required fluid volume, thereby lowering associated fluid costs. Furthermore, the printing technology allows for the simultaneous use of multiple colors or fluid types and the printing of complex tasks (such as images) in a limited number of print passes. Printing on complex substrates may require, for example, the use of industrial robots, such as multi-axis machines and / or gantry systems and / or robotic arms.

[0006] There is also growing interest in printing thicker layers (e.g., surface treatments and / or coatings). There is also growing interest in printing thicker areas to create features such as raised areas (e.g., electronic circuitry on a circuit board). There is also growing interest in printing raised features (e.g., tactile features and / or textures and / or 3D decorations). Printing thicker layers or features on a surface can be achieved by printing multiple thinner layers, for example, using a microdroplet ejector for multiple print passes. However, for reasons of time and efficiency, or due to adhesion issues between multiple layers, it may be desirable to use a microdroplet ejector capable of printing thicker layers in a single pass. For example, a typical graphic printing layer (e.g., an image or text) might be 5 μm thick, while a paint layer (e.g., on a vehicle) might be at least 25 μm thick for durability and appearance reasons. There is also growing interest in combining the above end uses to print thicker overall overlays or surface treatments on complex substrates, or to decorate and / or customize complex substrates with images and / or text and / or textures.

[0007] One drawback of printing thicker layers and on complex substrates is that, especially when slow-drying fluids are required, the fluid may have time to undergo significant flow before drying, resulting in a difference between the desired location and / or thickness of the fluid and its final dried location. Understandably, "slow-drying" may mean a drying time of several minutes, rather than a UV-curable ink that can, for example, "dry" (cur) in seconds. For instance, fluid printed onto a complex substrate may be affected by gravity on a non-horizontal surface, causing the fluid to flow across the complex substrate before drying, resulting in variations in the thickness of the printed layer or area drying on the surface, and / or dripping or other artifacts outside the printed layer or area. This can be undesirable for aesthetic reasons (e.g., visible artifacts, such as surface undulations on the printed layer, or dripping below the desired printed area) and / or technical reasons (e.g., a rust-preventive surface treatment may be too thin to be effective in some areas, while being too thick and prone to peeling in others).

[0008] It's easy to understand that printing over a large area, whether on a horizontal or complex substrate, may require printing multiple strips to cover the entire region. For example, it might involve one or more printheads moving back and forth to gradually cover the area, with each printhead producing one stripe at a time. Ideally, the first of any two adjacent stripes will be confined within the desired printing area of ​​the droplet deposition, such that the second of two adjacent stripes is adjacent to and in contact with the first, as shown below. Figure 2B As shown. In practice, especially if the fluid is slow-drying or slow-curing, or if the fluid layer is relatively thick, fluid flow may occur before the first strip dries, cures, and / or sets, causing it to extend beyond the desired first strip printing area (see...). Figure 2B Therefore, when a second adjacent strip is subsequently printed, it may cover a portion of the first strip, creating a bump on the surface (see...). Figure 2C This effect can be more or less noticeable, depending on many factors such as fluid viscosity, drying time, layer thickness, etc. If it leads to observable thickness variations or affects the mechanical properties or image quality of the final layer, this effect is likely undesirable. It is generally understood that this effect is most common when printing multiple strips, where subsequent strips deposit next to previous strips, leaving a noticeable, visible overlap. This type of visual defect is difficult to overcome with conventional applicators and formulations developed to produce a good appearance on horizontal surfaces but which generate very noticeable stripe overlap areas.

[0009] Some applications can overcome these problems, for example, by using fast-drying or fast-curing fluids (e.g., those that set or cure almost immediately after printing, such as UV-curable inks), or by using larger printhead assemblies. However, many applications still require the use of non-fast-drying fluids or fluids that do not cure shortly after printing, and / or desire to print thicker layers, such as for surface coatings or treatments, or to form raised features on surfaces, such as for printing electronic components or tactile features, or for decorative purposes; the thickness of such layers may be approximately 25–100 μm. In such applications, even addressing the aforementioned problems individually is difficult, let alone when these problems are combined due to specific coating requirements (e.g., attempting to achieve a good appearance without overlapping defects on non-horizontal surfaces through multiple coating processes). Summary of the Invention

[0010] This article provides a method for forming a coating on a substrate. The method includes:

[0011] A high-efficiency transfer applicator is provided, comprising a plurality of nozzles arranged on at least one printhead, each nozzle being configured to selectively apply microdroplets of a coating composition to a substrate with substantially no atomization, and each printhead being configured to address the strip by arranging a plurality of lines of coating composition on the strip via the plurality of nozzles.

[0012] Receive image data and a predefined non-linear laydown pattern;

[0013] Determine a plurality of overlapping strips that extend parallel to each other along a first direction, each strip being an area that can be processed by at least one printhead and forming an overlapping area with at least one adjacent strip;

[0014] Each overlapping area is allocated between adjacent strips, and the complementary portion of the nonlinear tiling pattern is allocated to the adjacent strips;

[0015] The coating composition is applied to at least one first strip using the high-transfer-efficiency applicator, and a first complementary portion of the nonlinear layup pattern is formed in at least one overlapping region thereof; and

[0016] The coating composition is applied to at least one second strip using the high-transfer-efficiency applicator, and a second complementary portion of the nonlinear layup pattern is formed in the at least one overlapping region, thereby forming a continuous layer on the substrate.

[0017] A microdroplet ejection device for implementing the method is also provided. The microdroplet ejection device includes one or more microdroplet ejection heads and one or more motion devices, wherein the one or more microdroplet ejection heads are mounted on the one or more motion devices.

[0018] A coating substrate prepared by the method is also provided, an example of which is a coated vehicle part. Attached Figure Description

[0019] The embodiments of this disclosure are described below with reference to the accompanying drawings, some of which are schematic and not drawn to scale, wherein:

[0020] Figure 1A A schematic cross-section of a standard microdroplet array on a complex substrate inclined relative to a horizontal plane is depicted.

[0021] Figure 1B A schematic depiction of in Figure 1A After the fusion and drying of the standard microdroplet array Figure 1A The dried desired swathe is shown on a complex substrate.

[0022] Figure 1C Depicting in Figure 1A After the standard microdroplet array is fused and dried, in Figure 1A A schematic cross-section of an uncompensated strip on a complex substrate is shown.

[0023] Figure 1D Depicting and Figure 1C Schematic cross-sections of different second uncompensated strips.

[0024] Figure 1E Describes the process for processing Figure 1C A schematic cross-section of a compensated droplet array of uncompensated strips.

[0025] Figure 1F Describes the process for processing Figure 1D A schematic cross-section of a compensated droplet array of uncompensated strips.

[0026] Figure 2A A schematic cross-section of two dried desired strips arranged adjacent to each other on a horizontal substrate is depicted.

[0027] Figure 2B Depicting in Figure 2A A schematic cross-section of the first uncompensated strip arranged on a horizontal substrate.

[0028] Figure 2C Depicting in Figure 2AA schematic cross-section of adjacent first and second uncompensated strips arranged on a horizontal substrate.

[0029] Figure 2D Depicting in Figure 2A Arranged on a horizontal substrate Figure 2B The first uncompensated strip and the strip used for compensation Figure 2C A schematic cross-section of the compensated droplet array of the second uncompensated strip.

[0030] Figure 2E Depicting Figure 2B The first uncompensated strip and Figure 2D A schematic cross-section of the second compensation strip formed by the compensation microdroplet array, with the two strips in... Figure 2A They are arranged adjacent to each other on a horizontal substrate.

[0031] Figure 3A Depicting in relation to Figure 1A Schematic cross-sections of first and second uncompensated strips arranged on similar non-horizontal substrates.

[0032] Figure 3B Depicting in Figure 3A A schematic cross-section of the first compensating microdroplet array on a non-horizontal substrate.

[0033] Figure 3C Depicting by Figure 3B A schematic cross-section of the first compensation stripe formed by the first compensation microdroplet array and the second compensation microdroplet array, both arranged in... Figure 3A On non-horizontal substrates.

[0034] Figure 3D Depicting Figure 3C The first compensation band and Figure 3C A schematic cross-section of the second compensation strip formed by the second compensation microdroplet array, both arranged in Figure 3A On non-horizontal substrates.

[0035] Figure 3E Schematic cross-sections of the first and second uncompensated droplet arrays are depicted.

[0036] Figure 4A A schematic cross-section of a dried, uncompensated layer on a complex multi-surface substrate is depicted.

[0037] Figure 4B Depicting in Figure 4A A schematic cross-section of a drying compensation layer on a complex multi-surface substrate.

[0038] Figure 5An apparatus for processing complex substrates is described, wherein the apparatus includes a fluid supply system, a motion device, and a microdroplet ejector connected to the fluid supply system and mounted on the motion device;

[0039] Figure 6 This is a schematic diagram of a multi-axis, multi-arm microdroplet ejection device, which includes multiple microdroplet ejection heads to process complex convex substrates.

[0040] Figure 7 A schematic diagram and its side view depict a stripe printed onto a substrate and adjacent to another stripe.

[0041] Figure 8 A schematic diagram and its cross-sectional side view depict an image processing technique that uses a nonlinear printing pattern in the substrate plane to mechanically offset (index) adjacent stripes printed onto the substrate.

[0042] Figure 9 A schematic diagram and its cross-sectional side view depict an image processing technique that uses a nonlinear printing pattern in the substrate plane to mechanically offset adjacent stripes printed on the substrate.

[0043] Figure 10 A saddle-shaped surface is depicted, representing an idealized pattern of a coating formed according to a specific implementation scheme.

[0044] Figure 11A , 11B 11C depicts photographs taken during the evaluation of the coating prepared in Example 1. Detailed Implementation

[0045] The following detailed description is exemplary in nature and is not intended to limit this disclosure. Furthermore, it is not intended to be bound by the foregoing background or any theories presented in the following detailed description.

[0046] In general, this disclosure provides methods for coating articles, such as methods for applying a coating composition to a substrate (e.g., forming a coating thereon), coating compositions that can be used in the method, and coated articles prepared by such application methods. This disclosure further provides apparatus and systems for performing the methods and / or utilizing the coating compositions in the manner described.

[0047] For the sake of brevity, well-known conventional techniques associated with the compositions, methods, processes, apparatus, systems, and articles, as well as their various parts and components, may be introduced or described to varying degrees in the embodiments herein. For example, conventional techniques for forming coating compositions may not be described in detail herein because the various steps in the manufacture of such compositions are well-known and will be readily understood and conceived by those skilled in the art based on the embodiments and examples provided herein. Similarly, the various tasks and process steps described herein may be incorporated into a more comprehensive procedure or process with additional steps or functions not otherwise described, for example, because they are well-known and readily understood by those skilled in the art. Such conventional steps may be mentioned only briefly or may be omitted entirely without providing well-known process details.

[0048] Embodiments of the present invention aim to reduce visible artifacts caused by overlapping strips during the coating process, thereby producing a uniform coating with a good appearance on complex substrates, and thus reducing or overcoming the aforementioned disadvantages associated with conventional coating formulations and application methods.

[0049] In general, this method utilizes a high-transfer-efficiency applicator comprising multiple nozzles. The nozzles are typically arranged on at least one printhead, each nozzle configured to selectively apply microdroplets of the coating composition to the substrate with substantially no atomization. Each printhead is configured to arrange multiple lines of the coating composition on the substrate through the multiple nozzles. The substrate area treated by a given printhead is referred to as a "strip". An idealized illustration of printhead coating of a substrate is shown below. Figure 7 As shown, the second stripe (stripe 2) is being printed onto the substrate, adjacent to stripe 1 previously printed on the substrate. As illustrated, the stripes are adjacent to each other without gaps. Typically, the coating composition will flow at least to some extent, allowing for the printing of a continuous wet coating through multiple passes / strips.

[0050] During the printing process, there is often some overlap between the strips, so that misalignment between adjacent strips does not result in unprinted areas of substrate that are highly visible to the human eye. Therefore, in these overlapping areas, the substrate is processed at least twice, either through a single pass by multiple overlapping printheads, through multiple passes by a single printhead, or a combination of both. Overall, this method uses image processing and / or image compensation to adjust for factors that may lead to lower-quality printing, including overlap defects and unacceptable layer build-up during application (e.g., through multiple printhead passes). It is understood that these factors can be combined and often render conventional methods unusable for forming coatings with high uniformity and good appearance, especially on non-horizontal surfaces, complex substrates, etc.

[0051] In general, the method presented in this paper utilizes a nonlinear layup pattern to print overlapping stripes of the coating composition onto a substrate, thereby reducing the obvious visibility of overlaps in the resulting dried coating. To this end, image data is used to determine the number of strips required to coat the substrate and obtain the desired image. The number of strips will be based on the printhead size, number of printheads, substrate size, image size, etc. Overall, due to the overlap between adjacent stripes, the width of the printed stripes will be smaller than the width of the stripes processed by the printhead (i.e., the effective coating width of the printhead is reduced due to the overlapping areas).

[0052] This method utilizes a non-linear layup pattern in overlapping regions to mechanically offset and visually fuse adjacent stripes. The shape of the layup pattern is not particularly limited; it is illustrated herein by way of curves, such as arcs, waveforms, and saddle shapes formed by combinations of different dimensions. It will be understood that the layup pattern can be non-linear with respect to one or more dimensions. For example, in some embodiments, the layup pattern is non-linear in the plane of the surface being printed, such as when stripes are printed with the waveform pattern described herein. In some of these or other embodiments, the layup pattern is non-linear in a plane perpendicular to the substrate surface, such that the coating formed in the overlapping regions may have intentionally varying thicknesses to control the surface of the coating being formed.

[0053] Figure 8 A schematic diagram illustrating the execution of this method is shown, with stripe S2 printed next to stripe S1. The strip of the printhead applying the coating composition to form S2 overlaps with the strip printed with S1 in the area indicated by Z1 (i.e., the overlapping area), which is processed by the printhead associated with both stripes S1 and S2. The overlapping area Z1 is allocated between the two stripes, each strip being assigned a complementary portion of the layup pattern, which... Figure 8 The fan-shaped edge of the stripe is indicated in the text. The fan shape, such as the repeating portion of stripe S1 extending perpendicularly to the printing direction in region Z2, is illustrative and not limiting. Such portions can have any size suitable for the methods described herein. Figure 8 The figure also shows a cross-sectional side view along the printing direction at points X1 and X2, illustrating the portion of the overlapping region Z1 where stripes S1 and S2 lie throughout the printing process during the application of the fan-shaped pattern. As shown, the pattern is typically divided by a center line that describes the oscillating path across the overlapping region along the printing direction. This center line, described by the edge of each applied stripe, can be used to define a nonlinear pattern. In some embodiments, the center line is a simple arc, as shown in Figure 11 discussed below. In other embodiments, the center line can be a waveform, such as a sine wave. Other curves and combinations of curves can also be used.

[0054] It is understandable that the edge patterns of each stripe sharing the overlapping area will be complementary, but not necessarily identical. For example, when using... Figure 8 When creating a fan-shaped pattern, the edge pattern of stripe S1 is a series of convex arcs, while the edge pattern of stripe S2 is a series of concave arcs, forming the center line of the fan.

[0055] Each segment of adjacent stripes is processed by the printheads that apply stripes S1 and S2. Therefore, it can be understood that segments of any one or both stripes within the overlapping region can be printed wholly or partially by any printhead processing that overlapping region. In some embodiments, a portion of each segment in the overlapping region is applied by each printhead processing the overlapping stripes. For example, in some embodiments, a small portion of the segment associated with stripe S2 may be applied by the printhead during the application of stripe S1. Similarly, the printhead applying stripe S2 can be used to complete the application of the coating composition to the segments in the overlapping region laid by the printhead applying stripe S1. As can be understood from the description herein, a compensation method can be used to determine how much of each stripe should be applied by a given printhead during the execution of this method.

[0056] In addition to the edge patterns of adjacent stripes, the film construction in overlapping areas can also be selected to control the visual appearance of the final coating. For example, as Figure 9 As shown, a wavy pattern can be formed by applying different amounts of the coating composition, resulting in alternating areas of high and low film buildup. A cross-sectional view of the applied stripes is also shown, illustrating the film thickness formed, for example, by alternating applications of relatively high and relatively low volumes of the coating composition. In some cases, once the dried coating has formed on this wavy patterned surface, the visibility of overlapping areas may be reduced.

[0057] It is understood that nonlinear layup patterns can include saddle-shaped surface types that repeat along the printing direction. Specifically, a saddle-shaped surface is formed when the center lines of the overlapping segments intersect to trace a sine wave in the substrate plane, and the volume of the coating composition and / or the height of the applied coating alternately increases and decreases during application to create a varied build profile along the printing direction. This saddle-shaped surface has alternating highs and lows that are perpendicular to each other. A schematic of such a saddle-shaped surface is shown below. Figure 10 As shown.

[0058] Now that the general principles of the current implementation scheme have been explained, further details of the components, compensation methods, techniques and processes, as well as coating compositions that can be used in the method, will be described below. These, together with the implementation scheme, further illustrate the scope of the implementation scheme envisioned herein.

[0059] First refer to Figure 1AThe image shows a schematic cross-section of a standard microdroplet array 105 on a complex substrate 100 tilted at an angle β relative to the horizontal plane. It is understood that the complex substrate 100 extends into the page (not shown) in the z-direction, and the microdroplets are ejected from a microdroplet ejector head moving above the complex substrate 100. The strips have a width W, which depends on the width of the nozzle rows on the microdroplet ejector head. It is understood that the microdroplet ejector head may include multiple nozzles and is capable of ejecting a large number of microdroplets at any given time point, but for simplicity... Figure 1A Only a few microdroplets 105i-105v were depicted.

[0060] One example of such a droplet ejector head is a shared-wall ejector head, where opposing walls are formed of piezoelectric material sheets with parallel grooves sawn into them to form pressure chambers. In this device, the pressure chambers are arranged side-by-side in parallel, each pressure chamber being fluidly connected to one or more nozzles. The walls of the pressure chambers can be driven according to print instructions to eject one or more fluid droplets through the nozzles. Each pressure chamber can be processed individually to control whether droplets are ejected according to print instructions. In droplet ejector heads that support grayscale, the pressure chambers can be further processed to control the volume of fluid ejected through a given nozzle.

[0061] Now for reference Figure 1B It schematically depicts in Figure 1A After the microdroplets fuse and dry, a desired dry strip 110 is formed on a complex substrate 100. The desired dry strip 110 has a nominal thickness Nt, which is measured perpendicular to the surface of the complex substrate 100 in a thickness direction T (it is generally understood that, depending on the shape of the complex substrate 100, T may be a constant direction or may change direction as the surface orientation of the complex substrate changes). It is generally understood that, depending on the type of fluid deposited, the volume of the dried strip or layer may be similar to the volume of the fluid deposited thereon (e.g., when the fluid forms chemical crosslinks or "cures" and the volume loss is small). Alternatively, the volume of the desired dry strip 110 may be smaller than the volume of the deposited microdroplets that form it, for example, the fluid may contain a carrier liquid that will evaporate completely or partially once deposited on the substrate. Such a carrier liquid may be, for example, water or a solvent. Furthermore, depending on the fluid deposited, certain processes (e.g., curing) may cause polymer molecules to move closer to each other, resulting in a shrinkage in the volume of the dried strip compared to the undried strip.

[0062] It is understandable that, for example, UV-curable inks do not “dry”; they polymerize (cur) and become solid under UV light. In contrast, inks and paints typically “dry” by losing liquid mass / volume and leaving behind solid contents (sometimes resin). It is generally understood that the term “dried” as used herein, such as “dried strip” or “dried layer,” can encompass any process in which a liquid (e.g., ink, varnish, paint, or other fluid that is liquid at the time of deposition) is deposited on a substrate and undergoes the formation of a desired non-liquid layer or coating (e.g., surface treatment or coating or decorative layer, or texturing, etc.) on the substrate. Such processes can include drying by fluid evaporation loss, by curing, by chemical bonding occurring after deposition onto the substrate, etc.

[0063] Figure 1C and Figure 1D Is Figure 1A A schematic cross-section of two different uncompensated strips 110A and 110B of an uncompensated dry layer 120 formed on a complex substrate 100, which is as follows: Figure 1A The uncompensated microdroplet array 105 shown is fused and dried. In both cases, the fluid flows under gravity on the complex substrate 100 before shaping or drying. Figure 1C During the process, fluid flow occurred, causing the thickness 112A at the top of the deformable layer 110A to decrease, becoming less than the nominal thickness Nt, while the thickness 111A at the bottom increased, becoming greater than the nominal thickness Nt. Figure 1D During this process, fluid flow occurs, causing the top thickness 113B to increase (e.g., due to the curvature and fixation of the liquid surface at the top), the middle thickness 112B to decrease, and the bottom thickness 111B to increase. It can also be seen that in both cases, the fluid flow exceeds (below) the desired dry stripe 110, causing the deformed layers 110A and 110B to extend outwards by flow distances 114A and 114B, respectively, exceeding the desired dryness. Figure 1B The desired width W of the dried strip 110 is such that strips 110A and 110B have widths WA and WB, respectively, where WA>W and WB>W.

[0064] It is generally understood that the extent of any gravity-induced flow beyond the width W may vary along the strip (e.g., in the z-direction), and therefore the flow distances 114A, 114B may vary in the z-direction. It is also generally understood that the shape and thickness of the uncompensated drying strips 110A, 110B may also vary in the z-direction, such that the cross-section at any given z-location may differ from, but be similar to, that of the strips. Figure 1C and Figure 1DThose are schematically depicted. However, it is understood that variations in shape, thickness, and flow range may be within measurable or predictable limits. It is understood that such thickness variations may occur regardless of the printing orientation or the size of the printed area on the surface of the complex substrate 100, and the extent of this flow, and the resulting thickness variations, may depend on many factors, as described above, including fluid composition, environmental conditions, and the characteristics of the complex substrate 100 (including shape and orientation).

[0065] As previously shown by the inventors associated with this disclosure, by adjusting the volume and / or spatial resolution of fluid droplets ejected onto a substrate at different locations, flow-induced thickness variations can be mitigated and a more uniform print thickness produced, thereby reducing or overcoming the aforementioned drawbacks. For example, some droplet ejectors are capable of printing using what is commonly referred to as grayscale technology or “grayscale.” This is the ability of certain droplet ejectors to eject fluid droplets in a variety of different volumes (e.g., by ejecting droplets of different sizes (volumes), or by ejecting a large number of smaller droplets, which form a single droplet at a given location on the substrate, depending on the desired droplet volume). Droplets may coalesce in the air or on the substrate, depending on a range of factors, including the type of droplet ejector; the type of fluid, etc. Grayscale levels can be defined as the number of different droplet sizes or volumes that a particular droplet ejector may produce (including so-called “white,” i.e., no droplets ejected). For example, the Xaar1002GS6 printhead can produce seven different droplet sizes with volumes between 6 and 42 picoliters on a substrate. This means the Xaar 1002GS6 can print at eight grayscale levels (including "white"). Typically, grayscale capability is used for image control, such as ejecting a series of microdroplet volumes according to print instructions to refine the appearance of printed feature edges, or for graphic alignment. However, it has been recognized that grayscale can also be used as a way to adjust the volume of ejected fluid to mitigate thickness variations caused by fluid flow on the substrate (e.g., due to non-horizontal flow or flow at stripe edges). Adjusting the ejection volume can produce a more uniform print thickness, thereby reducing or overcoming the aforementioned drawbacks.

[0066] Figure 1E and Figure 1F Schematic cross-sections of the first and second compensating droplet arrays 105A and 105B are depicted. The compensating droplet arrays 105A and 105B respectively process [the droplets] by selectively increasing or decreasing the volume of individual droplets in the respective arrays. Figure 1C and Figure 1D The dried, uncompensated strips 110A and 110B. For example, in Figure 1E In the study, the volume of droplet 10⁵Ai increased compared to droplet 10⁵i, while the volume of droplets 10⁵Aiii-10⁵Av increased compared to droplet 10⁵Ai. Figure 1AIn the 105i-105v microdroplets, the droplet volume gradually decreases at comparable positions, while the 105Av microdroplet is "white" or a non-ejecting droplet. Figure 1F In the process, the volume of droplet 10⁵Bii increases compared to droplet 10⁵Bi, while the volume of droplets 10⁵Biii-10⁵Bv gradually decreases until droplets cease to be ejected at 10⁵Bv, thus producing a more closely approximate volume. Figure 1B The desired drying cross-section of the 110-strip dry compensation strip. This is understandable. Figure 1E and Figure 1F This is merely a conceptual representation that adjusting the droplet volume by increasing or decreasing the amount of fluid ejected from a specific nozzle can be used to counteract deviations in thickness from the ideal or desired value or range Nt caused by fluid flow effects on the substrate.

[0067] In general, the method may include a process of jetting microdroplets to compensate for uncompensated strip thickness variations caused by fluid flow on a substrate. This process typically includes:

[0068] a. Receive uncompensated image data and a predefined nominal thickness Nt;

[0069] b. Determine the thickness variation of one or more uncompensated dry strips 110A, 110B at one or more locations relative to a predefined nominal thickness Nt;

[0070] c. Determine the compensated image data to interpret the thickness variation;

[0071] d. Based on the compensated image data, a fluid volume is sprayed onto the substrate in the form of fluid droplets through one or more nozzles of the droplet ejector head.

[0072] It is generally understood that uncompensated image data may contain information about the image to be printed, and it may also contain geometric information about the substrate to be printed (which may be a complex substrate 100), or the geometric information may be provided separately, such as CAD data, or a surface scan from the substrate to be printed or a representative example.

[0073] Generally, it can be understood that at locations with no thickness variation, the compensated image data for that location can include the uncompensated image data for that location; therefore, the volume of droplets ejected at that location can be the uncompensated droplet volume for that location. It can be further understood that if the thickness at a given location is less than a predefined nominal thickness Nt, then the compensated image data for that location can include the ejection of droplets larger than the uncompensated droplet volume for that location; conversely, if the thickness at a given location is greater than the predefined nominal thickness Nt, then the compensated image data for that location can include the ejection of droplets smaller than the uncompensated droplet volume for that location.

[0074] It can be further understood that the thickness variation can be determined within a representative range of points on the uncompensated strip, rather than at every point where droplets are to be deposited. Therefore, determining the compensated image data used to interpret the thickness variation can include interpolation or other suitable computational methods to determine droplet volume compensation at all points where droplets are to be ejected, based on the thickness variation within a representative range of points on the uncompensated strip or layer. Alternatively, the thickness variation can be determined at a resolution higher than the droplet resolution to determine how the fluid moves between droplet points, and an interpolation scheme from this higher-resolution thickness data can be used to determine the compensated image data.

[0075] It is generally understood that thickness variations can be determined in various ways, such as by creating one or more test substrates by spraying a microdroplet test pattern from a microdroplet ejector onto one or more test substrates 100 and allowing the fluid to dry. This microdroplet test pattern can, for example, produce a square image formed by microdroplets of multiple known microdroplet volumes. Alternatively, the microdroplet test pattern can typically be the pattern required to form the desired image on a flat, horizontal surface; for example, the image produced using an uncompensated microdroplet pattern if the substrate is horizontal, not complex, and unaffected by fluid flow on the substrate.

[0076] It is generally understood that the droplet volumes used to generate the test pattern can all be identical, or they can vary depending on the requirements for generating the desired image (e.g., the desired image may already have variations in droplet volume to refine image edges, as is generally known in the art). It is understood that the test substrates can have the same or similar shape and geometry as the desired substrate, or they can represent a range of shapes and orientations. For example, for printing on an inclined surface, a range of test substrates with an inclination angle β relative to the horizontal plane from 0° to 90° can be used.

[0077] It is generally understood that once the test substrate is prepared and the microdroplets are dried, the thickness variation relative to a predefined nominal thickness Nt (e.g., the desired thickness of a strip or layer) can be determined within a representative range of points on the one or more test substrates. The thickness variation can be determined by measurement, for example, using a surface probe, profilometer, interferometry, laser scanner, or any other suitable method to measure the thickness variation and / or surface morphology at one or more locations on the test substrate and / or desired substrate. It is generally understood that if a series of test substrates are used, the thickness variation on the desired substrate can be determined by interpolation of the test substrates (e.g., if the desired substrate is at a 45° angle to the horizontal plane, and there are test substrates oriented at 40° and 50° relative to the horizontal plane, an interpolation algorithm can be used to determine the thickness variation on the desired substrate).

[0078] Alternatively, instead of printing test substrates for each desired substrate and application, thickness variations can be determined using a lookup table; or by using mathematical models and calculations. Lookup tables and / or calculations can be based on a range of parameters such as fluid type, environmental conditions, and the characteristics of complex substrates. When using a lookup table to determine thickness variations, for example, the table may have been populated with data from multiple test substrates, or by using mathematical models and predictions. When generating lookup table data from multiple test substrates, it can be understood that this can be done for a desired fluid or for a range of test fluids representing a range of characteristics. For example, the test fluids could be for a range of viscosities and / or particle loading and / or particle size, and / or fluid type and / or fluid volume percentage, and / or temperature, etc.

[0079] Now for reference Figures 2A to 2E These figures depict fluid flow at the edges of the strips. For simplicity, this is depicted on a flat, horizontal substrate 200, but it can be understood that such flow can also occur on complex substrates that are not flat or horizontal. Figure 2A A schematic cross-section of two dried desired strips 210a, 210b arranged adjacent to each other on a horizontal substrate 200 is depicted, having a thickness Nt.

[0080] Figure 2B Depicting in Figure 2A A schematic cross-section of a first uncompensated dried strip 210aA arranged on a horizontal substrate 200, and an array of uncompensated microdroplets 205b ejected from a microdroplet ejector head 60 to generate a second strip. The microdroplets 205bi-205bv are all of the same volume, but this is understood to be by no means necessary and depends on the application requirements. It can be seen that, prior to drying, fluid flows outward in the x-direction on both sides of the first uncompensated dried strip 210aA, such that the width WaA of the uncompensated dried strip 210aA is greater than the width W of the desired dried strip 210a. The outward flow on both sides has a width of 214aA. It can also be seen that the first uncompensated dried strip 210aA also includes a thinner strip region 212aA, with a thickness less than the predefined nominal thickness Nt and a width of 217aA. The thinner region 212aA extends beyond the x-direction, such that width 217aA > width 214aA. This means that the thinner region 212aA begins within the width W of the desired dry strip 210a.

[0081] Figure 2C A schematic cross-section depicts a first uncompensated dry strip 210aA and a second uncompensated dry strip 210bA arranged adjacent to the first strip, for example, in Figure 2B The microdroplet array 205b falls onto the substrate 200 and... Figure 2AAfter a second uncompensated dry strip 210bA is formed on the horizontal substrate 200 adjacent to the first uncompensated dry strip 210aA, it can be seen that to the left of the second uncompensated dry strip 210bA, there is an overlapping portion 215bA with a width of 216bA, in which the combined strip thickness is greater than the predefined nominal thickness Nt. It can also be seen that the right side of the second uncompensated dry strip 210bA is similar to the right side of the first uncompensated dry strip 210aA, having a thinner strip region 212bA with a width of 217bA, exceeding the expected strip width W by 214bA.

[0082] Figure 2D A compensated microdroplet array 205bB ejected from a microdroplet ejector head 60 is depicted for processing Figure 2C The second dry uncompensated band 210bA, while Figure 2E A second drying compensation strip 210b generated by the compensation microdroplet array 205bB is depicted. It can be seen that a portion of the second drying compensation strip 210bB covers... Figure 2B The first dried uncompensated strip 210aA, however, reduces the volume of the overlapping region 215bB due to the reduced volume of the droplets 205bi and 205bii, resulting in a combined strip thickness of Nt. This is generally understood to be... Figures 2D-2E An example method for handling thickness variations at strip junctions between adjacent strips 210 is described, wherein in a subsequent strip (210b in the example), the volume of ejected fluid is reduced in the region near the strip junction. Alternatively, the volume of ejected fluid near the strip junction can be reduced in the initial strip (i.e., 210a), or the volume can be reduced in both the initial and subsequent strips (210a and 210b) to control the thickness near the strip junction. Compensating for thickness variations can include adjusting the volume of fluid to be ejected at a given location (e.g., based on measured thickness data at that pixel location, adjusted on a per-pixel (e.g., per microdroplet) basis). Such adjustments can include increasing or decreasing the volume of fluid to be ejected at a given location, e.g., on a per-pixel basis. Alternatively, volume adjustment can be accomplished by interpolating between one or more locations on the uncompensated layer where thickness variations are determined.

[0083] Alternatively, a correction region can be defined by determining the boundaries or edges of the thickness variation area, for example... Figure 2C The thickness variation region 218A extends to both sides of the desired strip connection location. Alternatively, the correction region can be a certain percentage wider on both sides of the thickness variation region 218A to achieve a smoother strip joint, for example, 0-20% or 0-10% wider than the thickness variation region 218A. The compensation image data in the correction region can include using an algorithm to gradually change the volume of the jet fluid within the correction region.

[0084] It is generally understood that when a correction region covers two adjacent stripes, the volume of fluid ejected within the correction region can be varied in the initial strip, subsequent stripes, or both, as described above. For example, compensating image data could include adjusting the print volume such that half the desired volume is ejected on a portion of the initial strip near the strip edge (in the correction region, overlapping region, or both, as described herein), and the other half of the desired volume is ejected on a portion of the subsequent strip near the strip junction (e.g., also in the correction region, overlapping region, etc.). Alternatively, compensating image data could include gradually decreasing the droplet size between adjacent stripes on a portion of the strip near the junction (e.g., in the correction region), for example, using grayscale. Other algorithms can be used to adjust the ejected droplets, such as pattern-based volume changes like dithering, half-tone screening, gradation, etc., which can be applied to the image data. Furthermore, combinations of methods can be used, such as using a gradient of droplet size in one part of the correction region and then using a dithering pattern in another part. It is also possible to use different methods at different stages of the iterative process; for example, one technique might be used for the initial guess, while an alternative method is used in subsequent refinement steps to determine the compensation image data. Such processes and methods can also be used to determine the image data to process the image to reduce the visibility of overlapping areas.

[0085] It can be further understood that determining the compensation image data used to compensate for thickness variations may include changing the spatial resolution of the ejected droplets (e.g., ejecting fewer / more droplets on a given area to change the droplet density, for example, by reducing the droplet density on the substrate by using no ejection or "white" droplets) and / or changing the volume of the ejected droplets. Simple methods, such as gradually reducing the number of ejected droplets, or more complex algorithms as described above, can be used to change the spatial resolution. Furthermore, it can be understood that changing the droplet volume may include increasing and / or decreasing the volume of ejected droplets on a per-droplet basis. Similarly, changing the spatial resolution may include increasing or decreasing the droplet density.

[0086] It is generally understood that determining image data (to assign layup patterns and / or compensate for thickness variations) typically includes determining the location of strip junctions and / or the orientation and / or curvature and / or other geometric features of complex substrates in order to pinpoint the locations where strip overlaps and / or thickness variations occur. This can be accomplished through measurement techniques or by using image data such as CAD data, strip widths (depending on the selected microdroplet ejector), and the desired microdroplet ejector path.

[0087] Now for reference Figures 3A to 3E These figures depict a non-horizontal complex substrate 300 (similar to...) Figure 1AAs shown), multiple stages of deposition of two adjacent strips on substrate 300. Figure 3A A schematic cross-section of first and second dried uncompensated strips 310aA, 310bA arranged on a complex substrate 300 is depicted. These can be used as... Figure 3E The uncompensated droplet arrays 305aA and 305bA shown are formed similarly to Figure 1A The uncompensated droplet array 105. Figure 3B A schematic cross-section of the first compensating microdroplet array 305aB on the complex substrate 300 is depicted, similar to... Figure 1E 305aBi is greater than 305aBii, while 305aBiii-305aBv are smaller, with 305aBv being non-sprayed or "white" droplets. Figure 3C A schematic cross-section is depicted of a first dry compensation strip 310aB and a second compensation microdroplet array 305bB formed by a first compensation microdroplet array 305aB, both arranged on a complex substrate 300. It can be seen that the first and second compensation microdroplet arrays 305aB and 305bB are similar, but it is understood that this is by no means necessary; in other arrangements, the two microdroplet arrays may differ depending on the shape of the dry uncompensated strips 310aA and 310bA to correct their respective dry uncompensated strips. Referring now... Figure 3D It depicts Figure 3C A schematic cross-section of the first and second drying compensation strips 310aB and 310bB on the complex substrate 300. It can be seen that, with... Figure 3A In comparison, adjusting the volume of the jet droplets improved the shape of strips 310a and 310b.

[0088] Figure 4A A schematic cross-section of a deformed and dried layer 420A on a multi-surface complex substrate 400 is depicted. It can be seen that the thickness direction T changes direction, maintaining its perpendicularity to the surface of the complex substrate 400. Layer 420A may contain one or more strips. It can be seen that material accumulates 421A at the inner corner 425, while the material 422A thins out at the outer corner 426 of the complex substrate 400. Figure 4B Depicting in Figure 4A A schematic cross-section of the corrected dried layer 420B on the complex substrate 400. The printing instructions for coating the complex substrate 400 may have been adjusted to reduce fluid deposition at the inner corner 425 and increase fluid deposition at the outer corner 426 to correct defects and provide a more uniform dried layer 420B with corrected regions 421B, 422B.

[0089] It is generally understood that multiple stripes may exist in a layer on a complex substrate (such as complex substrate 400), and subsequent stripes arranged adjacent to previous stripes may be arranged in a manner similar to... Figure 3C , Figure 3D as well as Figure 2D and Figure 2E The correction is made in the manner depicted, depending on the orientation of the substrate in a given area.

[0090] Now for reference Figure 5 The image depicts a microdroplet ejection device 90 processing a complex substrate 500, wherein the microdroplet ejection device 90 includes a fluid supply system 40, a motion device 70, and microdroplet ejection heads 60 connected to the fluid supply system 40 and mounted on the motion device 70. It is understood that this is not limiting; depending on the application, there may be one or more microdroplet ejection heads 60 and one or more motion devices 70. The fluid supply 40 may be one or more fluid supplies, depending on the application requirements. There is also a processor 35 and a controller 30. The controller 30 is controlled by the processor 35 and configured to control the printing process. The controller can control the fluid supply system 40, the motion device 70, and the microdroplet ejection heads 60 according to a printing strategy from the processor 35. The printing strategy may include topographic information about the complex substrate 500 and the positional relationships between the motion device 70, the microdroplet ejection heads 60, and the complex substrate 500; image data about the content to be printed on the complex substrate 500; and motion data about how to process the complex substrate (where and in what order the print strips are applied). The printing strategy may also include using one or more control devices 10 to control the fluid pressure in the droplet ejector head 60 to ensure that the droplet ejector head does not leak or draw in air due to sensing pressure changes as it moves.

[0091] For simplicity, the fluid supply system 40 is depicted in a simplified form, with arrows indicating fluid supply paths. A fluid reservoir 41 and a control device 10 are present near the microdroplet ejector head 60. In this arrangement, the motion device 70 is schematically shown as a robotic arm 72, with the microdroplet deposition head 60 arranged on a mounting base 71 on the robotic arm 72, and shown as processing a 3D object 500. It can be seen that the use of the robotic arm 72 allows the microdroplet ejector head to process protrusions and contours or non-planar surfaces on the surface of the 3D object 500. Therefore, the device 90 includes a motion device 70 configured to move in three or more directions and / or orientations; furthermore, the motion device 70 is a robotic arm 72 with multiple degrees of freedom. Depending on the application requirements, it is generally understood that there may be one or more motion devices 70 and / or one or more robotic arms 72. It can be further understood that the motion device 70 can be any suitable device or mechanism with multiple degrees of freedom. It is understood that, depending on the requirements of a particular embodiment, the fluid supply system 40 may include one or more control devices 10 located at one or more predetermined positions to control the fluid supply pressure near one or more droplet ejector heads 60, thereby maintaining printing performance and droplet size as needed. The control devices 10 may communicate with the controller 30. It is generally understood that the one or more droplet ejector heads may be recirculating droplet ejector heads, in which case the fluid supply system 40 may supply fluid to the droplet ejector heads and remove un-ejected fluid from the droplet ejector heads, and the control devices 10 may be adapted to control the inflow and / or outflow into and out of the droplet ejector heads. The fluid supply system 40 and / or the control devices 10 may be arranged to control fluid pressure and / or recirculation rate.

[0092] Figure 6 This is a schematic diagram of a multi-axis, multi-arm microdroplet ejection device 90', which includes multiple microdroplet ejection heads 60_1i-60_2ii, mounted on a motion device 70' to process a convex complex substrate 600. The motion device 70' includes two arms 72a, 72b connected to a common base 73. Arms 72a, 72b can move independently of each other. Furthermore, the base 73 may also be movable depending on the requirements of a specific application. Each arm 72a, 72b has two microdroplet ejection heads 60 mounted on mounting seats 71a, 71b. It is understood that this is by no means limiting; the device 70' may include one or more arms 72a, 72b and / or one or more microdroplet ejection heads 60, and each arm 72a, 72b may include one or more mounting seats 71a, 71b for mounting one or more microdroplet ejection heads 60.

[0093] The microdroplet ejection device 90' ​​further includes a fluid supply system 40'. The fluid supply system 40' includes a fluid source 20 and fluid paths 21, 22, which respectively supply fluid to the microdroplet ejection head 60 and remove un-ejected fluid from the microdroplet ejection head 60 (for simplicity, not all of fluid paths 21, 22 are depicted). In some applications, there may be no fluid return path 22; that is, during normal operation, all fluid supplied to the microdroplet ejection head 60 may be ejected from the microdroplet ejection head 60. However, it is also understood that the microdroplet ejection head 60 may include a flow circulation design in which a portion of the fluid is ejected through one or more nozzles of the microdroplet ejection head 60, and the remaining un-ejected fluid returns to the fluid source 20 or a collection tank (not shown).

[0094] The microdroplet ejection device 90' ​​may additionally include a controller 30, or may be connected to an external controller 30 and / or processor 35. The controller 30 may control the motion device 70', and / or the fluid supply system 40' and / or the microdroplet ejection heads 60_1i-60_2ii. Alternatively, the processor 35 may include some or all of the functions of the controller 30 to control some or all of the microdroplet ejection devices 90, 90'. The controller 30 and / or processor 35 may include or be provided with lookup tables to determine thickness variations caused by fluid flow on the substrate. Alternatively, one or the other of the controller 30 and / or processor 35 may be equipped with suitable programming and / or algorithms to predict thickness variations caused by fluid flow on the substrate.

[0095] The step of determining the compensation image data used to compensate for thickness variations may include adjusting the volume of fluid to be injected at a given location (e.g., adjusting on a per-pixel basis based on measured thickness data at that pixel location), similar to setting a non-linear tiling pattern by changing the build-up height of the connecting edges of adjacent stripes, as described above. Figure 9 As previously mentioned, such adjustments can include increasing or decreasing the volume of fluid to be ejected at a given location, for example, on a per-pixel basis, or by interpolating between one or more locations where thickness variations are determined on the uncompensated layer. Alternatively, a correction region can be defined near the edge of the strip, within which the volume of ejected fluid is gradually changed based on an algorithm. It is generally understood that such a correction region might be... Figure 2C The thickness variation region 218A seen between two adjacent strips, or possibly one or more thickness variation regions on the substrate caused by the tilt angle of the substrate relative to the horizontal plane, resulting in fluid flow on the substrate, such as... Figure 1C and Figure 1D As shown, or both, such as Figure 3A As shown. Generally, a layer may contain one or more such correction regions, depending on the desired image, image size, etc.

[0096] As previously mentioned, the correction region can be a certain percentage wider than both sides of the thickness variation region 218 to achieve a smoother strip bonding, for example, 0-20% or 0-10% wider than the thickness variation region 218. Alternatively, the correction region can be narrower than the thickness variation region, for example, if Nt is a range and part of the thickness variation region is still within acceptable tolerances. Furthermore, the strip position can be adjusted, for example, by moving or adjusting the droplet injection path, so that a "gap" exists between the desired dried strip positions 210a, 210b, which is filled by fluid flow on the substrate in the compensation strip, but can reduce overflow between strips.

[0097] It is generally understood that the flow behavior and / or drying time of a fluid can be influenced by its properties and composition, such as viscosity, temperature, the type of constituent fluid present (e.g., the type of solvent used), plasticizers, particle loading, particle size, particle size distribution, particle shape, density, etc., as further detailed below. As mentioned earlier, some fluids may experience volume loss during drying (e.g., due to evaporation of the carrier fluid), while others may undergo chemical changes that result in volume shrinkage of the coating as the fluid dries or cures (e.g., chemical bonding, such as polymerization, crosslinking, etc.).

[0098] Flow behavior and drying time can also be affected by environmental factors (such as ambient temperature and humidity) and layer thickness. Layer thickness on the substrate can be influenced by the volume of fluid ejected from the microdroplet nozzles, nozzle spacing, nozzle ejection frequency, and the relative velocity between the microdroplet nozzles and the substrate. Substrate characteristics, such as surface roughness, temperature, polarity, absorbency, chemical composition, porosity, and any surface treatments on the substrate, can also affect drying time and flow velocity (and thus the spread of the fluid on the substrate) beyond the expected strip width W. These characteristics can affect the advancing and receding contact angles of the fluid as it flows on the substrate, thereby influencing the shape and morphology of the final dried coating on the substrate.

[0099] As described above, it is generally understood that the term "drying" as used herein, such as "dry strip" or "dry layer," can encompass any process in which a liquid (e.g., ink, varnish, paint, or other fluid that is liquid at the time of deposition) is deposited on a substrate and undergoes a process of forming a desired non-liquid layer or coating (e.g., surface treatment, coating, or decorative layer, or texturing, etc.) on the substrate. Such processes can include drying by fluid evaporation loss, by curing, by chemical bonding occurring after deposition onto the substrate, etc.

[0100] It can be further understood that a non-liquid layer or coating on a substrate may undergo more than one process to form said non-liquid layer or coating. For example, a liquid may be deposited and then lose volume (drying) through means such as evaporation loss to form an intermediate layer, which may be a semi-solid layer (e.g., a “sticky” paint coating). The intermediate layer may undergo subsequent processes, such as curing processes (e.g., heating in a controlled environment or irradiation with ultraviolet light), to form the final desired non-liquid layer or coating. It can be further understood that when an intermediate layer and the final desired non-liquid layer or coating are present, the thickness may be determined at any and / or both stages to determine whether the layer requires compensation as described herein.

[0101] It is generally understood that, as previously mentioned, fluid flow on a substrate can occur on a non-complex (i.e., flat, horizontal) substrate, such as... Figures 2A-2C As shown, fluid flow may occur on these substrates at strip edges and strip junctions. Fluid flow may also occur on complex substrates at strip edges and strip junctions, and may also occur due to the orientation of some or all of the complex substrate relative to the horizontal plane.

[0102] As is generally understood, the term "complex substrate" as used herein includes substrates containing one or more non-horizontal surfaces. For example, it can include one or more vertical, inclined (e.g., at an angle to a horizontal plane), and any other non-horizontal surfaces. Complex substrates can contain one or more flat and / or one or more non-planar surfaces, such as one or more curved surfaces. Complex substrates can also contain one or more horizontal surfaces (e.g., see...). Figures 4A-4B Non-limiting examples of complex substrates may include walls and roofs of buildings, bottles and containers, vehicles, household goods, consumer products, etc. Such complex substrates may require the application of one or more surface layers for a variety of reasons, including aesthetic reasons such as decoration or beautification, and / or technical reasons such as protective coatings to prevent rust, corrosion, water intrusion, electrical or chemical insulation, and / or for conveying information such as advertising, labels, barcodes, security, tactile information provision, etc.

[0103] As is generally understood, the term "desired substrate" as used herein includes substrates of interest for a particular application and may include non-complex substrates or complex substrates as described herein. For example, a particular application might be printing on a complex substrate (e.g., a vehicle, such as an automobile, or a part of a vehicle, such as a door). It is also generally understood that "desired fluid" might be a fluid required for a particular application (e.g., paint or a protective coating).

[0104] The substrate itself may be coated, i.e., comprising one or more layers on which fluids can be applied. These one or more layers may be applied by the methods described herein, by conventional methods known in the art, or by a combination thereof. Depending on the application, such layers may have specific names and / or functions, typically determined based on the components used to prepare such layers and / or the function of the layers themselves. Examples of such layers or coatings include primers, basecoats, varnishes, topcoats, midcoats, electrocoats, colorcoats, etc.

[0105] The term "basecoat" refers to an opaque coating that provides protection, color, hiding power (also known as "opacity"), and visual appearance. Basecoats typically contain colored pigments, effect pigments (such as metallic pigments), UV absorbers, and other coating additives. The term "basecoat composition" refers to a coating composition that can be used to form a basecoat. Similarly, the term "basecoat layer" refers to a coating formed from such basecoat compositions. Basecoat layers can be formed by applying one or more layers of the same or different basecoat compositions. In automotive coatings, the substrate is typically first coated with a primer layer to provide protection and adhesion, then a basecoat layer is applied over the primer layer, optionally followed by a sealant to provide most of the protection, color, and visual appearance, and subsequently a clear coat layer is applied over the basecoat layer to provide further protection and visual appearance. Sometimes, a single coating, called a "topcoat," can be used to provide the functions of both a basecoat and a clear coat. Additional coatings can also be used. For example, a metallic substrate can be treated with a phosphate material and coated with an electrophoretic paint layer before applying a primer layer.

[0106] The term "intermediate coat" or "intermediate layer" refers to a colored, non-opaque coating located between a base coat and a clear coat in a multi-layer coating system. To achieve unique and appealing colors or visual effects, the automotive industry and other end-use coating applications may use multi-layer coatings with three or more layers, instead of the traditional two-layer "base coat and clear coat" system. A multi-layer system typically includes at least a first colored and opaque base coat, a second clear coat deposited on at least a portion of the base coat, and a third clear coat deposited on at least a portion of the second clear coat. The second clear coat, often called the intermediate coat, contains colored pigments. Intermediate coats are typically formulated to be transparent so that the color of the underlying base coat can be seen through it.

[0107] Previous layers, such as a first base coat, can be applied to the substrate using conventional spraying equipment (e.g., a bell applicator). Subsequent layers, such as a second base coat, can then be applied over the first base coat using a high-transfer-efficiency applicator. During this process, one or more factors can be considered, such as the effect of the surface tension of the first base coat on the second base coat. For example, the surface tension of the first base coat can be increased to improve the flowability of the paint composition applied to it using a high-transfer-efficiency applicator. This improved flowability may be desirable when printing the paint composition across the entire panel of a vehicle. Similarly, the surface tension of the first base coat can be decreased to improve the boundary retention and / or resolution of the paint composition applied to it using a high-transfer-efficiency applicator. This improved boundary retention and / or resolution may be desirable when printing the paint composition as patterns, text, etc. Furthermore, the effect of wet-on-wet application between the first and second base coats can be considered. For example, the choice of carrier and additives may affect whether the coating composition is suitable for wet-on-wet application onto a first base coat.

[0108] It is generally understood that the methods described herein can be used to replace and / or supplement any conventionally applied layers, such as by replacing, adding new layers between existing layers, or adding additional layers on top of existing layers. Examples of such multi-layer applications are described in the table below:

[0109] Multilayer Example 1 - Wet Process

[0110] layer Traditional coating methods Embodiments of the present invention primer Spraying Spraying Base coat Spraying No over-spraying Varnish Spraying Spraying

[0111] Multilayer Example 2 - Wet Process

[0112] layer Traditional coating methods Embodiments of the present invention primer Spraying Spraying Base coat – Color 1 Spraying Spraying Base coat – Color 2 Masking, spraying, removing masking No over-spraying Varnish Spraying Spraying

[0113] Multi-layer Example 3 - Topcoat

[0114] layer Traditional coating methods Embodiments of the present invention primer Spraying Spraying Base coat – Color 1 Spraying Spraying Varnish Spraying Spraying Single coating – Color 2 Masking, spraying, removing masking No over-spraying

[0115] Multi-layer Example 4 – Topcoat

[0116] layer Traditional coating methods Embodiments of the present invention primer Spraying Spraying Base coat – Color 1 Spraying Spraying Varnish Spraying Spraying Base coat – Color 2 Masking, spraying, removing masking No over-spraying Varnish Spraying Spraying

[0117] It is generally understood that the predefined nominal thickness Nt of the upper layer of the substrate may not be a single value, but may include an acceptable range, that is, the thickness of the layer should be within Nmin < Nt < Nmax. The minimum value Nmin and the maximum value Nmax can be set by aesthetic or practical considerations. For example, the acceptable minimum thickness may be the thickness required to prevent corrosion, or to provide a visually uniform surface coverage, or durability and scratch resistance. The acceptable maximum thickness may be the thickness at which the layer dries within a suitable time frame before subsequent steps in the production process, or to keep the article within an acceptable weight range. In some applications, the predefined nominal thickness Nt may be a predefined nominal thickness distribution. For example, a gradual change (opposed to a step change) of the nominal thickness along the layer may be more important, that is, it is not the thickness or the thickness range that is important, but the continuity and smoothness along the surface. Therefore, the predefined nominal thickness may include the allowable rate of change of the thickness with distance, rather than or in addition to the absolute thickness value.

[0118] It can be further understood that, depending on the printing application and the desired final result, different predefined nominal thicknesses Nt may be acceptable at different locations. For example, surface features or decorations may be designed to have a thickness variation across the feature, with different nominal thicknesses Nt(x,y,z) at different points. It can also be understood that when the strip connection is located within such a feature, the method of the embodiments of the present invention can be used to control the nominal thickness Nt at the connection, so that it falls within the acceptable nominal thickness Nt(x,y,z) range at the strip connection location and in its vicinity.

[0119] In addition, it can be understood that in some applications, the predefined nominal thickness Nt may not be provided as a separate value or range, but may be determined from the uncompensated image data by classifying the number of droplets in a given area as being directly related to the expected thickness. For example, depositing 25 grams of the desired fluid over an area of 1 square meter will result in a desired layer of 25 grams per square meter on the surface, from which the expected predefined nominal thickness can be determined. Depending on the type of ink used, information about the expected volume loss / shrinkage can be provided, or it can be obtained from a look-up table.

[0120] Various types of droplet ejection heads 60 may be suitable for embodiments of the present invention. This may include those that eject all fluid supplied to the nozzle, as well as so-called flow-through or recirculating droplet ejection heads 60. A flow-through or recirculating (ejection) head refers to a head in which fluid circulates within the droplet ejection head 60, a portion of which is drawn out and ejected from the nozzle, while the remainder flows out of the droplet ejection head 60. Typically, a droplet ejection head may include one or more nozzles, each of which is fluidly connected to a fluid chamber comprising one or more actuators that can be driven according to printing instructions to eject one or more fluid droplets through the nozzles. Typically, one or more droplet ejection heads may have grayscale capability and may be mounted in droplet ejection devices 90, 90' as described herein or any other droplet ejection device suitable for implementing the droplet ejection method described herein for compensating fluid flow on a substrate. Such droplet ejection devices may include one or more droplet ejection heads and one or more motion devices, wherein the one or more droplet ejection heads may be mounted on the one or more motion devices. The droplet ejection device may further include a fluid supply system 40, 40' or be connected to a separate fluid supply source. The droplet ejection device may further include one or more controllers 30 and / or processors 35. Alternatively, the droplet ejection device may be connected to one or more controllers 30 and / or processors 35 for exchanging control information and commands.

[0121] It is generally understood that the fluid supply system 40, 40' may include one or more fluid reservoirs 41 near the droplet nozzle 60, and / or fluid sources 20 located away from the droplet nozzle 60 and connected to them via the fluid supply path 21, and in the case of a flow circulation nozzle, connected via the fluid return path 22. The fluid supply system 40, 40' may include, for example... Figure 5 One or more control devices 10 are shown to control the fluid pressure in one or more droplet nozzles according to the requirements of the application.

[0122] It is understood that print job data can be received and / or determined and / or calculated prior to printing. Print job data may include information about the geometry of the substrate to be printed (which may be complex), the image to be printed, print resolution, stripe profile and position, number of layers, image stitching requirements, required fluid information, and the microdroplet head motion profile (characteristic distribution) of one or more microdroplet ejectors 60. It may also include information about fluid requirements, fluid pressure, etc., as these may change during printing. It is understood that, for example, the geometry of the substrate to be printed may be CAD (computer-aided design) data or data generated using a surface mapping tool on a substrate example. The microdroplet head motion profile may include the microdroplet head path, microdroplet head speed, microdroplet head acceleration or deceleration, and / or microdroplet head orientation, and therefore may also include or be used to determine the motion profile of the motion devices 70, 70'. Some or all of the print job data may be determined or calculated in the processor 35, or some or all of the print job data may be provided to the processor 35, for example, as one or more data files. Processor 35 may provide instructions to controller 30. The compensated image data described herein may be provided as part of print job data, or may be received and / or determined and / or calculated. For example, uncompensated image data may be provided to processor 35, and compensated image data may be measured, determined, or calculated in processor 35 as described herein.

[0123] It is generally understood that processor 35 and controller 30 can be arranged in any suitable configuration to enable printing apparatus 90, 90' to operate and perform the methods for processing fluid flow on a substrate as described herein. For example, in addition to / instead of controller 30, there may be one or more sub-controllers to control separate parts of printing apparatus 90, 90', and / or some or all of the controller functions may instead be incorporated into processor 35. Controller 30 and / or sub-controllers may be computing devices, microprocessors, application-specific integrated circuits (ASICs), system-on-a-chip modules containing processor elements and FPGA logic, or any other suitable devices to control the functions of various components of printing apparatus 90, 90', such as motion device 70 and / or fluid supply system 40 and / or one or more droplet ejector heads 60. Processor 35 may be, for example, a microprocessor or a computer.

[0124] As described above, various types of fluids can be used in this method. It is generally understood that the fluid is a coating composition, i.e., a fluid composition formulated to be applied to a substrate via a microdroplet ejection device. Depending on the desired printing application, the fluid may be, for example, a water-based coating composition or a solvent-based composition. It is also understood that the fluid can be formulated and used as a one-component (i.e., "1K") composition or a two-component (i.e., "2K") composition.

[0125] It is generally understood that an acceptable coating composition comprises a binder, a crosslinking agent, and a carrier medium (e.g., solvent, water, etc.). The term "binder" typically refers to the film-forming component of a coating composition. It is understood that such binders may include specific polymers, oligomers, or combinations thereof, which are generally essential for forming a coating with desired properties (e.g., hardness, protection, adhesion, etc.). Other components, such as carriers, pigments, catalysts, rheology modifiers, antioxidants, UV stabilizers and absorbers, leveling agents, defoamers, anti-cratering agents, or other conventional additives, are generally not included in the term "binder" unless these additional components are themselves film-forming components. However, as described below, one or more of these additional components may be included in the coating composition.

[0126] It is understood that there are no particular limitations on the binder, and it may include any suitable resin known and used in the types of coating compositions presented herein (e.g., solvent-based and / or water-based paints, single-coat paints, etc.). For example, the resin may comprise acrylic resins, polyester resins, or combinations thereof. Alternatively, the composition and / or the resin itself may comprise polyester and not acrylic resins and / or any other polymers. The composition and / or the resin itself may comprise both acrylic resins and polyesters and not any other polymers.

[0127] Generally, it is understood that acceptable acrylic resins can be reaction products of one or more of the following monomers, or consist essentially of or composed of reaction products of one or more of the following monomers: (meth)acrylamide, N-substituted (meth)acrylamide, octyl (meth)acrylate, nonylphenol ethoxylate (meth)acrylate, isononyl (meth)acrylate, 1,6-hexanediol (meth)acrylate, isobornyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, β-carboxyethyl (meth)acrylate, isobutyl (meth)acrylate, alicyclic epoxides, α-epoxides Combinations of these, including: 2-hydroxyethyl methacrylate, methacrylonitrile, maleic anhydride, itaconic acid, isodecanyl methacrylate, dodecyl methacrylate, n-butyl methacrylate, methyl methacrylate, hexyl methacrylate, methacrylic acid, N-vinylcaprolactam, stearyl methacrylate, hydroxyfunctional caprolactone ester, octadecyl methacrylate, isooctyl methacrylate, hydroxyethyl methacrylate, methyl methacrylate, hydroxypropyl methacrylate, hydroxyisopropyl methacrylate, hydroxybutyl methacrylate, hydroxyisobutyl methacrylate, tetrahydrofurfuryl methacrylate, and so on.

[0128] For example, the acrylic resin may comprise one or more of the following: (meth)acrylated polyurethane (i.e., polyurethane (meth)acrylate), (meth)acrylated epoxy resin (i.e., epoxy (meth)acrylate), (meth)acrylated polyester (i.e., polyester (meth)acrylate), (meth)acrylated (meth)acrylated acrylic resin, (meth)acrylated silicone, (meth)acrylated amine, (meth)acrylated amide; (meth)acrylated polysulfone; (meth)acrylated polyester, (meth)acrylated polyether (i.e., polyether (meth)acrylate), vinyl (meth)acrylate, and (meth)acrylated oil.

[0129] It is generally understood that an acceptable polyester can be any polyester known in the art, including any polyester known in the art, or substantially composed of or consisting of any polyester known in the art. For example, the polyester can be linear or branched. Useful polyesters can include aliphatic or aromatic dicarboxylic acids, polyols, diols, aromatic or aliphatic cyclic anhydrides, and esterification products of cyclic alcohols. Non-limiting examples of suitable alicyclic polycarboxylic acids are tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, inner methylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, inner ethylhexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid, and cyclobutanetetracarboxylic acid. The alicyclic polycarboxylic acids can be used not only in their cis form but also in their trans form, and can be used as mixtures of the two forms. Other non-limiting examples of suitable polycarboxylic acids may include aromatic and aliphatic polycarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids such as tetrachloro or tetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid, and pyromellitic acid. Combinations of polyacids, such as combinations of polycarboxylic acids and alicyclic polycarboxylic acids, may be suitable. Combinations of polyols may also be suitable.

[0130] It is also understood that suitable polyesters can be polymerized by conventional polymerization methods from a monomer mixture containing a chain extender selected from hydroxycarboxylic acids, hydroxycarboxylic acid lactones, and combinations thereof, and one or more branched monomers. Some suitable hydroxycarboxylic acids include glycolic acid, lactic acid, 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvalerate, and hydroxypentanoic acid. Some suitable lactones include caprolactone, valerate; and lactones of the corresponding hydroxycarboxylic acids, such as lactones of 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvalerate, and hydroxypentanoic acid. Branched copolyester polymers can be produced by one-step polymerization of a monomer mixture containing a chain extender and a hyperbranched monomer, or by first polymerizing the hyperbranched monomer and then polymerizing the chain extender. Branched copolyester polymers formed from an acrylic core and the aforementioned chain extender monomers can also be used.

[0131] Generally, the term "crosslinking agent" is understood to refer to a component having "crosslinking functional groups" located in each molecule of a compound, oligomer, polymer, polymer backbone, side chains from the polymer backbone, directed at the ends of the polymer backbone, or combinations thereof, wherein these functional groups are capable of crosslinking with crosslinkable functional groups (during the curing step) to produce a coating in the form of a crosslinked structure. Those skilled in the art will recognize that certain combinations of crosslinking and crosslinkable functional groups are excluded because they cannot crosslink and form a crosslinked structure for film formation.

[0132] In general, coating compositions suitable for use as or as said fluid contain isocyanate crosslinking agents, melamine crosslinking agents, or both.

[0133] Generally, it is understood that an acceptable isocyanate crosslinking agent can be one or more of the following isocyanates, including one or more of the following isocyanates, and is essentially composed of or composed of one or more of the following isocyanates: aromatic, aliphatic, or alicyclic diisocyanates, triisocyanates, or tetraisocyanates, including polyisocyanates having isocyanurate structural units, such as isocyanurates of hexamethylene diisocyanate and isocyanurates of isophorone diisocyanate; adducts of two molecules of diisocyanate (such as hexamethylene diisocyanate) and diol (such as ethylene glycol); urea diketone of hexamethylene diisocyanate; urea diketone of isophorone diisocyanate or isophorone diisocyanate; adducts of trimethylolpropane and m-tetramethylphenyl diisocyanate.

[0134] For example, isocyanates such as oligomers based on hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), or toluene diisocyanate (TDI), such as isocyanurates, biuret, urethane, and adducts of the above isocyanates with polyols, and mixtures thereof, can be used. These can react with polyols, such as OH-containing polyesters, polyethers, acrylates, and polyurethanes, and mixtures thereof, which can be solvent-based, solvent-free, or water-dilutable. Similarly, monofunctional isocyanates and / or blocked isocyanates can be used.

[0135] It is generally understood that isocyanate crosslinking agents can be used alone or in combination with melamine crosslinking agents. Similarly, in some applications, only melamine-type crosslinking agents may be used. Melamine resins suitable as crosslinking agents can be partially or fully etherified with one or more alcohols (such as methanol or butanol). A non-limiting example is hexamethoxymethyl melamine. Other non-limiting examples of suitable melamine resins include monomeric melamine, polymeric melamine-formaldehyde resins, or combinations thereof. The monomeric melamine comprises low molecular weight melamines containing, on average, three or more hydroxymethyl groups etherified with a C1 to C5 monohydric alcohol (such as methanol, n-butanol, or isobutanol) per triazine core, with an average degree of condensation up to about 2, for example in the range of about 1.1 to about 1.8, and a mononuclear species proportion of not less than about 50% by weight. In contrast, polymeric melamines have an average degree of condensation greater than about 1.9. Some suitable monomeric melamines include alkylated melamines, such as methylated, butylated, isobutylated melamines, and mixtures thereof. Many of these suitable monomeric melamines are commercially available. For example, Cytec Industries Inc., West Patterson, NJ supplies them. 301 (degree of polymerization 1.5, 95% methyl and 5% hydroxymethyl), 350 (degree of polymerization 1.6, 84% methyl and 16% hydroxymethyl), 303, 325, 327, 370, and XW3106 are all monomeric melamines. Suitable polymeric melamines include highly amino (partially alkylated, -N, -H) melamines, called... BMP5503 (molecular weight 690, polydispersity 1.98, 56% butyl, 44% amino) is supplied by Solutia Inc., St. Louis, Mo., or by Cytec Industries Inc., West Patterson, NJ. 1158. Cytec Industries Inc. also supplies 1130@80% solids (degree of polymerization 2.5) 1133 (48% methyl, 4% hydroxymethyl and 48% butyl), both are polymerized melamine.

[0136] It is generally understood that coating compositions are typically suspensions of film-forming components and optional additives, and therefore typically contain a carrier medium, such as a solvent or fluid. As mentioned above, the carrier medium can be water-based or solvent-based; that is, the coating composition is typically a water-based composition or a solvent-based composition. Formulations of such carrier media are known in the art and will be best understood from the embodiments and description herein.

[0137] Depending on the application, the solvent may be an organic solvent. Suitable examples of organic solvents may include aromatic hydrocarbons, such as toluene and xylene; ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl pentyl ketone, and diisobutyl ketone; and esters, such as ethyl acetate, n-butyl acetate, and isobutyl acetate. Some specific examples include methanol, ethanol, isopropanol, n-butanol, 2-butanol, tridecyl alcohol, methyl isobutyl ketone, methyl ethyl ketone, 3-butoxy-2-propanol, ethyl 3-ethoxypropionate, butanediol, butanediol acetate, butanol, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, butyl glycolate, hexane, heptane, octane, toluene, xylene, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, 2-butoxyethyl acetate, pentyl acetate, isoamyl acetate, diethylene glycol butyl ether acetate, acetone, xylene, and toluene. However, typically, the coating compositions are substantially free of highly volatile solvents, as well as any other solvents that would interfere with the types of applicators and application processes described herein.

[0138] When used, the organic solvent content is typically greater than about 50% by weight, or greater than 60% by weight, or greater than 70% by weight, or greater than 80% by weight, or greater than 90% by weight, based on the total weight of the liquid carrier in the coating composition. However, any single solvent or carrier medium may be present in the coating composition in any suitable amount, for example, from about 5% to about 70% by weight, or from about 10% to about 65% by weight, based on the total weight of the coating composition. The total amount of carrier used will depend on the type of composition (i.e., water-based or solvent-based) and will be understood in accordance with the solids content range provided herein.

[0139] In some applications, the coating composition contains water as a carrier.

[0140] The coating composition may contain various components, such as binders, dyes, rheology modifiers, carriers, catalysts, conventional additives, or combinations thereof. Conventional additives may include, but are not limited to, dispersants, antioxidants, UV stabilizers and absorbers, surfactants, wetting agents, leveling agents, defoamers, anti-cratering agents, or combinations thereof. In some cases, the coating composition is suitable for use in this method because it contains certain components and / or contains certain components in specific amounts / proportions.

[0141] It is generally understood that the coating composition may have a specific solids content, as shown in the relative component contents provided herein. Typically, the specific solids content of the coating composition will be selected based on other components present in the coating composition and used in the method. For example, the coating composition may be a solvent-based composition with a solids content of about 25% to about 60%, such as about 27% to about 55%, or about 30% to about 50%. Alternatively, the coating composition may be a water-based composition with a solids content of about 5% to about 45%, such as about 8% to about 35%.

[0142] It will also be understood that the coating composition has a specific viscosity, such as a specific shear or complex viscosity, or other rheological properties. Those skilled in the art will understand the factors that affect the viscosity of the composition, including those involved in this method, and methods for determining specific viscosities and related values ​​(e.g., ASTM 2196, etc.).

[0143] Example

[0144] The following examples illustrate embodiments of the present disclosure and are intended to illustrate, rather than limit, the embodiments of the present disclosure set forth in the claims.

[0145] Unless otherwise stated, all parts and percentages are by weight. If provided, the molecular weights (number-average and weight-average molecular weights) mentioned herein can be measured using conventional methods known in the art. For example, the molecular weight of polyaspartic resins can be measured by gel permeation chromatography (GPC), for instance, using polystyrene standards and tetrahydrofuran (THF) eluent. Unless otherwise stated, molecular weights are reported as weight-average molecular weights (Mw).

[0146] Material

[0147] Unless otherwise stated, all solvents, substrates and reagents were purchased or otherwise obtained from various commercial suppliers such as BASF, Covestro, Evonik, Sigma-Aldrich, VWR, Alfa Aesar, etc., and were used as is (i.e. without further purification) or in the form commonly used in the art.

[0148] Various coating compositions were prepared using the following specific materials:

[0149]

[0150]

[0151]

[0152] Coating composition

[0153] A solvent-based coating composition (SB1) was formulated and prepared using the above-described components. Specific components and parameters are shown in the table below.

[0154]

[0155]

[0156] Four additional solvent-based coating compositions (SB2-SB5) were prepared using the components described above. These compositions were formulated according to the methods described herein for overspray application and for use in the printing tests described below. The specific components and parameters of the solvent-based compositions are shown in the table below.

[0157] Coating composition: SB2 SB3 SB4 SB5 melamine 4 20.67 20.44 18.84 15.33 Aromatic hydrocarbons 19.67 10.59 23.98 29.19 Wetting agent 3 - - - 0.20 Enamel Resin 1 51.45 34.95 43.81 21.57 Acrylic resin 3 - 19.53 - 14.65 Acrylic resin 4 - - - 2.93 Paint Additive 2 0.06 0.06 0.05 0.05 Catalyst 1 1.44 1.42 1.31 1.07 UV Additive 2 - - - 4.89 N,N-Dimethylethanolamine - - - 0.38 Black pigment 3 6.71 13.02 12.01 9.77 total: 100.0 100.0 100.0 100.0

[0158] SB2, prepared according to the formulation, is a one-component solvent-based single-coat composition with a viscosity of 29.6 cP at 25°C. SB3 is a one-component solvent-based base coat composition with a viscosity of 42.5 cP at 25°C. SB4 is a one-component solvent-based single-coat composition with a viscosity of 64.9 cP at 25°C. SB5 is a one-component solvent-based single-coat composition with a viscosity of 30 cP at 25°C.

[0159] Water-based coating compositions (WB) were prepared using the components listed above, resulting in WB1-7.

[0160] The specific components and parameters are shown in the table below.

[0161]

[0162]

[0163] General printing method

[0164] Connect the printhead (Xaar 2002 printhead) to the circulation system (Hydra) and mount it on a movable shaft. Mount the substrate onto the movable shaft perpendicular to the printhead. Load the coating composition into the printhead and apply it while the substrate moves beneath the printhead at a selected speed (e.g., 50-150 mm / s) to lay a first stripe along a first stripe having a predefined pattern along the edge. The printhead then moves 40-70 mm to treat a second stripe (overlapping area) that partially overlaps with the first stripe at the edge with the predefined pattern. The coating process is then repeated to lay a second stripe along the edge with the predefined pattern. This stripe is positioned to connect with the first stripe in the overlapping area and form a continuous wet coating. Allow the wet coating to flash dry for up to 10 minutes, then bake at 285°F for 30 minutes to obtain a dry coating with a film thickness of 0.5-2.0 mils.

[0165] Example 1: Image processing for reducing visual defects

[0166] Based on the general printing method described above, the coating composition SB1 was selected for printing tests. Printing conditions of 720 DPI and 50 mm / s were chosen to achieve a dry film buildup of approximately 1.3 mils. A double-strip image was printed in the overlapping area on a substrate (a flat horizontal panel) using an arc-shaped spread pattern. The first stripe, depicting a convex arc along adjacent edges, was then printed. A second stripe was then printed, with the concave arc dimension of its adjacent edges complementary to the convex arc dimension of the first stripe. This process was repeated while varying the stripe offset along the printing direction to evaluate the observable overlap characteristics produced in the overlapping area. Images of the resulting dried layer are plotted below. Figure 11A , 11B In 11C.

[0167] Example 2: Image processing for improving overlap performance / reducing visual defects

[0168] Based on the general printing method described above, the coating composition SB1 described above was also selected for another printing experiment. Printing conditions of 720 DPI and 50 mm / s were selected to achieve a dry film buildup of approximately 1.3 mils.

[0169] Nine independent print tests (AI) were conducted to evaluate the visual results of image processing by changing the predefined tiling pattern in the overlapping areas of adjacent strips.

[0170] Images were created to lay out specific membrane build-up profiles that varied with location. Linear (AC, H) and non-linear lay-up patterns were selected, with non-linear edge patterns using either arcuate (DE, I) or repeating sine wave (FG) geometry. The effect of membrane build-up on the lay-up pattern (AC) was also evaluated by varying the deposited film height along adjacent edges. Observable overlap defects on the resulting coated substrate were then visually evaluated, and a "+ / -" performance rating was given from ---- (low / poor) to ++++ (high / best).

[0171] The parameters and results of specific tests in the printing experiment are shown in the table below:

[0172]

[0173] As shown in the table above, improved visual performance was achieved through the use of image processing methods, providing a coating with a good appearance and low overlap visibility. It is believed that nonlinear stripe laying reduces the apparent visibility of overlapping areas of overlapping stripes. Nonlinear patterns can be used to mechanically offset adjacent stripes, achieving positive results by changing the shape of adjacent edges of adjacent stripes in the substrate plane.

[0174] Therefore, embodiments of the present invention provide a method that can achieve performance and / or appearance superior to comparative methods. Further implementations of the present invention can also provide balanced printing performance (e.g., low sagging, good flow and leveling) while maintaining good coating appearance characteristics.

[0175] The data listed indicate that the exemplary compositions exhibit good performance and can be used to prepare overspray-free coatings in an orderly manner, with some exemplary coatings providing superior performance and appearance compared to some comparative coating compositions.

[0176] While at least one exemplary embodiment has been presented in the foregoing detailed descriptions, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiments or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed descriptions will provide a convenient roadmap for those skilled in the art to implement the exemplary embodiments. It should be understood that various changes can be made to the function and arrangement of the elements described in the foregoing exemplary embodiments without departing from the scope set forth in the appended claims. Furthermore, all combinations of the foregoing components, compositions, method steps, formulation steps, etc., are expressly contemplated herein for use in various non-limiting embodiments, even if such combinations are not expressly described in the same or similar paragraphs.

[0177] Regarding any Markush group relied upon herein to describe specific features or aspects of various embodiments, different, specific, and / or unexpected results can be obtained from each member of the corresponding Markush group, unlike all other Markush members. Reliance on each member of the Markush group, individually and / or in combination, can provide sufficient support for specific embodiments within the scope of the appended claims.

[0178] Furthermore, any scopes and subscopes relied upon in describing the various embodiments of this disclosure fall independently and collectively within the scope of the appended claims, and should be understood as describing and considering all ranges including integer and / or fractional values ​​therein, even if such values ​​are not explicitly stated herein. Those skilled in the art will readily recognize that the scopes and subscopes enumerated herein adequately describe and implement the various embodiments of this disclosure, and that such scopes and subscopes can be further divided into relevant halves, thirds, quarters, fifths, etc. As an example only, the scope “from 0.1 to 0.9” can be further divided into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which are individually and collectively within the scope of the appended claims and can be individually and / or collectively relied upon, providing adequate support for specific embodiments within the scope of the appended claims. Moreover, regarding language defining or modifying scopes, such as “at least,” “greater than,” “less than,” “not exceeding,” etc., it should be understood that such language includes subscopes and / or upper or lower limits. As another example, the range “at least 10” inherently includes subranges from at least 10 to 35, from at least 10 to 25, from 25 to 35, etc., and each subrange can be relied upon individually and / or collectively to provide sufficient support for specific embodiments within the scope of the appended claims. Individual numbers within the disclosed range can be relied upon to provide sufficient support for specific embodiments within the scope of the appended claims. For example, the range “from 1 to 9” includes various individual integers, such as 3, and individual numbers including decimal points (or fractions), such as 4.1, which can be relied upon to provide sufficient support for specific embodiments within the scope of the appended claims. Finally, it should be understood that the term “about” as used for any specific numerical values ​​and ranges described herein is intended to refer to values ​​within ranges of standard error, equivalent function, efficacy, final loading, etc., as understood by a person skilled in the art with conventional techniques and process skills related to the formulation and / or utilization of compounds and compositions such as those described herein. Thus, the term “about” can specify a value within 10%, or 5%, or 1%, or 0.5%, or 0.1% of the listed value or range.

[0179] While this disclosure has described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that many other forms and modifications will be obvious. The appended claims and this disclosure should generally be construed as covering all such obvious forms and modifications, which are all within the true scope of this disclosure.

Claims

1. A method for forming a coating on a substrate, the method comprising: A high-efficiency transfer applicator is provided, comprising a plurality of nozzles arranged on at least one printhead, each nozzle being configured to selectively apply microdroplets of a coating composition to a substrate with substantially no atomization, and each printhead being configured to process the strip by arranging a plurality of lines of the coating composition on the strip via the plurality of nozzles; Receive image data and predefined non-linear tiling patterns; Determine a plurality of overlapping strips that extend parallel to each other along a first direction, each strip being an area that can be processed by at least one printhead and forming an overlapping area with at least one adjacent strip; Each overlapping area between adjacent strips is divided, and the complementary portion of the nonlinear tiling pattern is assigned to the adjacent strips; The coating composition is applied to at least one first strip using the high-transfer-efficiency applicator, and a first complementary portion of the nonlinear paving pattern is formed in at least one overlapping region thereof. as well as The coating composition is applied to at least one second strip using the high-transfer-efficiency applicator, and a second complementary portion of the nonlinear layup pattern is formed in the at least one overlapping region, thereby forming a continuous layer on the substrate.

2. The method of claim 1, wherein the complementary portion of the nonlinear tiling pattern is divided by a center line that describes an oscillating path through the overlapping region along a first direction.

3. The method of claim 2, wherein the centerline: (i) is a waveform oscillating in the plane of the substrate being coated, such that alternating segments of the layer formed on the overlapping region are coated during the application of the coating composition to the first strip and the second strip; (ii) is a sine wave; (iii) delineates a fan-shaped line in the plane of the substrate being coated, such that the at least one first strip and the at least one second strip are applied in the overlapping region with complementary fan-shaped edges; or (iv) any combination of (i)-(iii).

4. The method according to claim 1, wherein the nonlinear laying pattern comprises: (i) A segment extending perpendicular to the plane of the substrate, which alternately increases and decreases the volume of the coating composition and / or the height of the applied coating during application to produce a varied build profile along a first direction; (ii) A saddle-shaped shape that repeats along a first direction, wherein the center line where the overlapping segments intersect traces a sine wave in the substrate plane, and the volume of the coating composition and / or the height of the applied coating are alternately increased and decreased during application to produce a varying build profile along the first direction; or (iii)(i) and (ii) both.

5. The method of claim 1, wherein the at least one first strip and the at least one second strip are (i) applied sequentially via the same printhead; or (ii) applied via different printheads of the applicator.

6. The method of claim 1, wherein the overlapping areas of at least one set of adjacent first strips and second strips are coated with a first volume of the coating composition during the coating of one of the adjacent strips, and then coated with a second volume of the coating composition during the coating of the other of the adjacent strips.

7. The method according to claim 6, wherein the ratio of the first volume to the second volume of the coating composition is about 85:15 to about 15:85, or about 80:20 to about 20:80, or about 75:25 to about 25:75, or about 70:30 to about 30:70, or about 60:40 to about 40:60, or about 50:

50.

8. The method of claim 6, wherein the applicator comprises a first set of printheads configured to coat the plurality of first strips and a second set of printheads configured to coat the plurality of second strips, optionally wherein the first and second sets of printheads are mounted on one or more motion devices.

9. The method according to claim 8, wherein, A first set of printheads is configured to coat the overlapping area with a first volume of the coating composition, and a second set of printheads is configured to coat the overlapping area with a second volume of the coating composition.

10. The method of claim 1, wherein the fluid is a coating composition having a solids content of about 5% to about 70%, and comprises: carrier; The binder, the content of which is based on the total weight of the coating composition, is from 5 to about 70 wt.%; and The crosslinking agent is present in a content of about 0.1 to about 25 wt.% based on the total weight of the coating composition.

11. The method of claim 10, wherein the fluid is further defined as a solvent-based coating composition having a solids content of about 25% to about 60%.

12. The method of claim 10, wherein the fluid is further defined as a water-based coating composition having an initial solids content of about 5% to about 45%.

13. A droplet ejection apparatus for carrying out the method of any one of the preceding claims, comprising: One or more micro-droplet ejection printheads; as well as One or more motion devices, The one or more printheads are mounted on the one or more motion devices.

14. The microdroplet ejection device according to claim 13, wherein one or more of the one or more microdroplet ejection printheads have grayscale capability.

15. A coated substrate prepared by the method of any one of claims 1-12, wherein the coated substrate: (i) is substantially free of visible overlap defects; (ii) is a vehicle component; or (iii) satisfies both (i) and (ii).

Images