Print correction method and droplet ejection head therefor

Abstract

A method of ejecting droplets of fluid to compensate for variations in thickness of a dry uncompensated layer due to fluid flow on a substrate is disclosed. The method comprises: a) receiving uncompensated image data and a predefined nominal thickness; b) determining a thickness variation at one or more locations of one or more dry uncompensated layers on the substrate relative to the predefined nominal thickness; c) determining compensation image data to compensate for the thickness variation; and d) ejecting fluid droplets through one or more nozzles of a droplet ejection head using the compensated image data to form a dry compensation layer on the substrate. Also disclosed is a droplet ejection device (90) for carrying out the method, comprising one or more droplet ejection heads (60) mounted on one or more motion devices (70).

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 509,938, filed June 23, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a print calibration method and a microdroplet ejector head for the method. It can find particularly advantageous applications in printheads such as inkjet printheads. 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 head for multiple print passes (throughs). However, for reasons of time and efficiency, or due to adhesion issues between multiple layers, it may be desirable to use a microdroplet ejector head 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.

[0007] There is also growing interest in combining these 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.

[0008] 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).

[0009] It's easy to understand that printing on large areas, whether on horizontal or complex substrates, may require printing multiple stripes to cover the entire area. For example, it might involve one or more printheads moving back and forth to gradually cover the area, with each printhead producing one stripe (stripe) per pass. 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 the 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 can be seen when printing multiple strips, where subsequent strips are deposited next to previous strips.

[0010] Some applications can overcome these problems by using fast-drying or fast-curing fluids (e.g., those that set or cure almost immediately after printing, such as UV-curable inks). Other applications may only require thin printed layers (approximately 5-10 μm) that dry quickly due to the small volume of fluid involved, such as those used for printing images or patterns. 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. These applications may be affected by undesirable thickness variations caused by flow. Summary of the Invention

[0011] The embodiments of the present invention aim to mitigate thickness variations caused by flow in order to produce a more uniform printing thickness, thereby reducing or overcoming the disadvantages of fluid flow on the aforementioned substrate.

[0012] Various aspects of this disclosure are set forth in the appended independent claims, while specific embodiments are set forth in the appended dependent claims.

[0013] A method is provided for jetting fluid droplets to compensate for thickness variations in a dried, uncompensated layer caused by fluid flow on a substrate. The method includes:

[0014] a) Receive uncompensated image data and predefined nominal thickness;

[0015] b) Determine the thickness variation relative to the predefined nominal thickness at one or more locations of one or more dry uncompensated layers on the substrate;

[0016] c) Determine compensation image data to compensate for the thickness variation; and

[0017] d) Using the compensated image data, fluid droplets are ejected through one or more nozzles of the droplet ejector head to form a dry compensation layer on the substrate.

[0018] 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. 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 desired dry stripes on the complex substrate are shown.

[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 Describing the 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 2A A 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 1ASchematic 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 5 An 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 This is a schematic diagram of the method steps for measuring and compensating for thickness changes caused by fluid flow on a substrate.

[0041] Figure 8 This is a schematic diagram of the method steps for determining and compensating for thickness changes caused by fluid flow on a substrate and printing onto the substrate.

[0042] Figure 9A and 9B This is an illustration of photographs taken during the evaluation of the coating prepared in Example 1, showing the uncompensated layer ( Figure 9A ) and compensation layer ( Figure 9B The relative sagging properties of ).

[0043] Figure 10A and 10B The visible conditions used to evaluate the defects of the coatings prepared in Examples 2-11 are depicted, wherein Figure 10A This shows representative optical distortion indicating defects on the dried layer, resulting in a lower (negative) rating. Figure 10B The display shows a representative undistorted light pattern indicating fewer / less severe defects on the dried layer, resulting in a higher (positive) rating.

[0044] Where appropriate, the same reference numerals are used for the same features. 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 preparing coatings and coated 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 such methods, 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] First refer to Figure 1A The 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 1AOnly a few microdroplets 105i-105v were depicted.

[0049] 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.

[0050] 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.

[0051] It is understood that, for example, UV-curable inks do not “dry” but rather 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 “drying,” as used herein, such as “drying strip” or “drying 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.

[0052] Figure 1C and Figure 1D Is Figure 1AA 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 caused the thickness 112A of the deformable layer 110A at the top to decrease, becoming less than the nominal thickness Nt, while the thickness 111A at the bottom to increase, 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 top liquid surface), 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 range of the desired dry strip 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.

[0053] 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 1D Those 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).

[0054] Surprisingly, it has been recognized that by adjusting the volume and / or spatial resolution of fluid droplets ejected onto the substrate at different locations, flow-induced thickness variations can be mitigated, resulting in a more uniform print thickness, thereby reducing or overcoming the aforementioned drawbacks. For example, some droplet ejectors are capable of printing using what is commonly known as grayscale technology or “grayscale.” This is the ability of certain droplet ejectors to eject fluid droplets in multiple 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. The number of 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 Xaar 1002GS6 printhead can produce seven different droplet sizes with volumes between 6 and 42 picoliters on the substrate. This means the Xaar 1002GS6 is capable of printing eight grayscale levels (including “white”). Typically, grayscale capabilities are 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.

[0055] 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 1A In 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 1FThis 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.

[0056] In general, a method for jetting microdroplets to compensate for uncompensated strip thickness variations caused by fluid flow on a substrate may include:

[0057] a. Receive uncompensated image data and a predefined nominal thickness Nt;

[0058] 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;

[0059] c. Determine the compensated image data to interpret the thickness variation;

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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).

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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 2A After 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.

[0071] 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.

[0072] 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.

[0073] It is generally understood that when the 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. For example, the compensation 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 (within the correction region), and the other half is ejected on a portion of the subsequent strip near the strip junction (within the correction region). Alternatively, the compensation image data could include gradually decreasing the droplet size between adjacent stripes on a portion of the strip near the junction (e.g., within 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 initial guessing, while an alternative method is used in subsequent refinement steps to determine the compensation image data.

[0074] 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.

[0075] It is generally understood that determining the compensation image data used to 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 location where the thickness variation occurs. This can be accomplished through measurement techniques or by using image data such as CAD data, strip width (depending on the selected microdroplet ejector), and the desired microdroplet ejector path.

[0076] Now for reference Figures 3A to 3E These figures depict a non-horizontal complex substrate 300 (similar to...) Figure 1A As 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 in a manner similar 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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).

[0083] 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.

[0084] Now for reference Figure 7 This is a schematic diagram of a method for measuring and compensating for thickness changes caused by fluid flow on a substrate, which can be performed by a microdroplet ejection device 90, 90' or any other suitable device, the method comprising the following steps:

[0085] 1. Print the uncompensated layer using uncompensated image data;

[0086] 2. Determine the thickness of the drying layer compared to the nominal thickness, and determine whether compensation is required;

[0087] 2a. If no compensation is required, proceed to step 5;

[0088] 3. If compensation is required, determine the compensation image data and whether to print a compensation test sample;

[0089] 3a. If no test sample is required, proceed to step 5;

[0090] 4. Print the compensation test sample;

[0091] 4a. Return to step 2, and repeat steps 2-4 as needed;

[0092] 5. Print the product and / or provide the compensated image data to the lookup table.

[0093] It is generally understood that the uncompensated layer in step 1 may contain a single stripe or multiple stripes. Furthermore, the uncompensated layer and subsequent compensation layers may be printed onto suitable test substrates and / or desired substrates. Additionally, to provide data for lookup tables or generate application-specific data, multiple uncompensated and compensation layers may be printed on multiple test substrates and / or desired substrates using desired fluids and / or one or more suitable test fluids, and the above steps may be repeated. Furthermore, steps 2 through 4a may be repeated once or multiple times, forming an iterative loop until the final compensated image data is determined, for example, an initial best guess at the compensated image data during the first pass of steps 2 through 4a, followed by one or more repeated loops, such as fine-tuning loops, which involve printing further adjusted compensated image data onto one or more test substrates and / or desired substrates.

[0094] The plurality of test substrates can be a series of test substrates sufficient to characterize fluid flow on the substrate, measure it, and determine compensated image data. For example, as mentioned above, the test substrates can include the same test substrate, such as a flat plate, at one or more tilt angles relative to the horizontal plane. Alternatively, or as an alternative, one or more complex substrates of different shapes can be used as test substrates at one or more tilt angles, such as a series of curved surfaces with different curvature angles arranged at different orientation angles, or a series of cylinders with different radii, or a series of flat plates with different angles of curvature, etc., all of which can be used as test substrates. Alternatively, or as an alternative, a series of layer thicknesses Nt and multiple strip connections with different orientations can be tested as needed to fill application-specific lookup tables and / or fill more general lookup tables. In some applications, application-specific test substrates can be used, such as a series of cross-sections of the desired product, or components of the desired product.

[0095] Figure 8 This is a schematic diagram of the steps of a method for determining and compensating for thickness variations in a dried, uncompensated layer caused by fluid flow on a substrate and printing it onto the substrate. The method includes:

[0096] a. Receive uncompensated image data and a predefined nominal thickness Nt;

[0097] b. Determine the thickness variation relative to a predefined nominal thickness Nt at one or more locations of one or more dry uncompensated layers on the substrate;

[0098] c. Determine compensation image data to compensate for the thickness variation;

[0099] d. Using the compensated image data, fluid droplets are ejected through one or more nozzles of a droplet ejector head to form a dry compensation layer on the substrate.

[0100] Generally, it can be understood that determining thickness variation may include:

[0101] i. Using uncompensated image data, fluid droplets are ejected through one or more nozzles of a droplet ejector head to form one or more dried uncompensated layers on one or more substrates;

[0102] ii. At one or more locations of the one or more uncompensated dry layers, determine the thickness variation of the one or more uncompensated dry layers relative to a predefined nominal thickness Nt.

[0103] Depending on the application, the one or more substrates may be one or more test substrates as described above, or one or more instances of a desired substrate. The fluid may contain a desired fluid or one or more test fluids, or a series of test fluids. After printing one or more uncompensated layers (which may contain one or more stripes; similarly, a compensated layer may contain one or more stripes) based on uncompensated image data, the method may include determining thickness variations by measuring the thickness and / or surface morphology of the one or more dried uncompensated layers at the one or more locations.

[0104] The method does not involve printing on one or more substrates or test substrates, but instead may include using a lookup table filled with data in step b to determine thickness variations, as described above. Furthermore, step b, determining thickness variations, may include using a mathematical model to calculate the thickness of one or more dried uncompensated layers at one or more locations.

[0105] Similarly, step c. determining the compensation image data may include using mathematical methods. For example, mathematical models and / or empirical models may be used to calculate thickness variations and / or determine the compensation image data. Alternatively, step c. may include using lookup tables to determine the compensation image data.

[0106] Step c. Determining the compensation image data for compensating 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). As previously described, such adjustments may include increasing or decreasing the volume of fluid to be injected at a given location, for example, on a per-pixel basis, or by interpolating between one or more locations on the uncompensated layer where thickness variations are determined. Alternatively, a correction region may be defined near the edge of the strip, within which the volume of fluid injected is gradually changed based on an algorithm. It is generally understood that such a correction region might be... Figure 2CThe 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 have one or more such correction regions, depending on the desired image, image size, etc. As previously mentioned, the correction region can be a certain percentage wider than both sides of the thickness variation region 218 to achieve 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 jetting path, so that there is a "gap" between the dried desired strip positions 210a, 210b, which is filled by fluid flow on the substrate in the compensation strip, but can reduce overflow between strips.

[0107] 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.).

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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).

[0114] 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, intermediate coats, electrophoretic coatings, and color coats.

[0115] 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.

[0116] The term "intermediate coat" or "intermediate layer" refers to a colored, clear coat layer located between the base coat and the clear coat layer 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 layer, a second clear coat layer deposited on at least a portion of the base coat layer, and a third clear coat layer deposited on at least a portion of the second clear coat layer. The second clear coat layer, 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.

[0117] 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.

[0118] 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:

[0119] Multilayer Example 1 - Wet Process

[0120] layer Traditional coating methods Embodiments of the present invention primer Spraying Spraying Base coat Spraying No over-spraying varnish Spraying Spraying

[0121] Multilayer Example 2 - Wet Process

[0122] 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

[0123] Multi-layer Example 3 - Topcoat

[0124] 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

[0125] Multi-layer Example 4 – Topcoat

[0126]

[0127]

[0128] 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 allowable 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 matters, but the continuity and smoothness along the surface. Therefore, the predefined nominal thickness may include the allowable rate of change of thickness with distance, rather than or in addition to the absolute thickness value.

[0129] 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 and near the strip connection location.

[0130] 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 may be provided, or it may be obtained from a look-up table.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] It is generally understood that an acceptable coating composition contains a binder, a crosslinking agent, and a carrier medium (e.g., solvent, water, etc.). The term "binder" generally 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] In general, coating compositions suitable for use as or as said fluid contain isocyanate crosslinking agents, melamine crosslinking agents, or both.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] In some applications, the coating composition contains water as a carrier.

[0151] 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.

[0152] 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%.

[0153] 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.).

[0154] Example

[0155] 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.

[0156] 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 example using polystyrene standards and tetrahydrofuran (THF) eluent. Unless otherwise stated, molecular weights are reported as weight-average molecular weights (Mw).

[0157] Material

[0158] 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.

[0159] Various coating compositions were prepared using the following specific materials:

[0160]

[0161]

[0162] Coating composition

[0163] 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.

[0164]

[0165]

[0166] 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.

[0167] 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

[0168] 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.

[0169] Water-based coating compositions (WB) were prepared using the components listed above, resulting in WB1-7.

[0170] The specific components and parameters are shown in the table below.

[0171]

[0172] General printing method

[0173] Connect the printhead to the circulation system (Hydra) and mount it on the 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 down the first stripe. Then move the printhead 40-70 mm and repeat the process to lay down the second stripe, thus forming 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.

[0174] Example 1: Image compensation for improving sagging performance

[0175] Based on the general printing method described above, the coating composition SB5 was selected for the printing test. Specifically, SB5 was loaded into a Xaar 1003 printhead and applied to a substrate (a flat, horizontal panel). Printing conditions of 1080 DPI and 50 mm / s were selected to achieve a dry film buildup of approximately 0.9 mils. The coated panel was then dried vertically, and the resulting uncompensated layer was visually evaluated. An image of the dried uncompensated layer is shown below. Figure 9A .

[0176] Use from Figure 9A Image data obtained from the dried, uncompensated layer is used to determine compensated image data for another SB5 print, specifically to compensate for the thickness build-up at the bottom of the panel caused by coating composition sagging. The compensated image data is then used to print SB5 on a second substrate, forming a dried compensation layer thereon. An image illustration of the dried compensation layer is shown below. Figure 9B .like Figure 9A and Figure 9B As shown, compensating for drips (i.e., by changing the volume of the printing fluid / wet film thickness at the bottom / lower part of the panel) results in smaller thickness variations on the stripes, manifested as fewer visual defects and very little / no dripping at the lower edge of the panel.

[0177] Example 2: Image compensation for improving overlap performance / reducing visual defects

[0178] Based on the general printing method described above, the coating composition SB1 described above was also selected for another printing experiment. A Xaar 2002 printhead containing two sets of nozzles (500 nozzles per set, totaling 1000 nozzles, grouped as 1-500 and 501-1000) was placed vertically, and the coating composition was applied downwards to the upper surface of the substrate panel. Printing conditions of 720 DPI and 50 mm / s were selected to achieve a dry film buildup of approximately 1.3 mils.

[0179] Ten independent printing experiments were conducted to evaluate image compensation by varying the relative fluid volume applied from each set of nozzles during one or two passes on the same area of ​​the substrate (i.e., the second pass printing on the wet layer formed by the first pass). The relative fluid volume applied from each set of nozzles was selected from levels 0 (none / minimum) to 7 (maximum). Visual defects were then assessed for each coated substrate and given a rating from 0 (low / poor) to 10 (high / best).

[0180] Visual performance examples are as follows Figure 10A and 10B As shown, where Figure 10AThis shows a representative optical distortion (D) indicating defects on the dried layer, resulting in a lower (negative) rating. Figure 10B The display shows a representative undistorted light pattern indicating fewer / less severe defects on the dried layer, resulting in a higher (positive) rating.

[0181] The parameters for the printing experiment are shown in the table below, along with the visual ratings corresponding to the prepared coated substrates.

[0182]

[0183] As shown in the table above, the experiments were conducted using different grades of fluid (paint) between the first and second passes. Experiment 1 represents a fluid grade (e.g., volume / volume) ratio of 100:0 to 0:100 per pass, while Experiments 2-10 represent variations of this ratio from 85:15 to 15:85, for example, volume / volume ratios between consecutive experiments of approximately 80:20, 75:25, 70:30, etc.

[0184] Experiment 1 was conducted using an "on / off" method. In the first pass, nozzles 1-500 sprayed grade 7 paint, and nozzles 501-1000 sprayed grade 0 paint. In the second pass (covering the same area), nozzles 1-500 sprayed grade 0 paint, and nozzles 501-1000 sprayed grade 7 paint. In this Experiment 1, the lowest visual rating was selected based on the observed defects.

[0185] In contrast, Experiment 5 achieved the highest visual rating and was based on image compensation performed according to an embodiment of the present invention.

[0186] Therefore, embodiments of the present invention provide a method capable of achieving a balance between printing performance (e.g., low sagging, good flow and leveling) and maintaining good coating appearance characteristics. Specific implementations of the embodiments of the present invention can also provide performance and / or appearance superior to comparative methods.

[0187] 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 the comparative coating compositions.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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 jetting fluid droplets to compensate for thickness variations in a dried, uncompensated layer caused by fluid flow on a substrate, comprising: a. Receive uncompensated image data and predefined nominal thickness; b. Determine the thickness variation relative to the predefined nominal thickness at one or more locations of one or more dry uncompensated layers on the substrate; c. Determine compensation image data to compensate for the thickness variation; as well as d. Using the compensated image data, fluid droplets are ejected through one or more nozzles of a droplet ejector head to form a dry compensation layer on the substrate.

2. The method according to claim 1, wherein, Step b. Determining the thickness variation includes: i. Using uncompensated image data, fluid droplets are ejected through one or more nozzles of a droplet ejector head to form one or more dried uncompensated layers on one or more substrates; ii. At one or more locations of the one or more uncompensated dry layers, determine the thickness variation of the one or more uncompensated dry layers relative to the nominal thickness.

3. The method of claim 2, wherein the fluid comprises the desired fluid.

4. The method of claim 2, wherein the fluid comprises one or more test fluids.

5. The method of claim 2, wherein the substrate comprises one or more test substrates.

6. The method of claim 2, wherein the substrate comprises a desired substrate, optionally wherein the desired substrate is a vehicle component.

7. The method of claim 2, wherein step ii. determining the thickness variation comprises measuring the thickness and / or surface morphology of the one or more dried uncompensated layers at one or more locations on the one or more dried uncompensated layers.

8. The method of claim 1, wherein step b. determining the thickness change comprises: (i) Calculate the thickness of the one or more dry uncompensated layers at the one or more locations using a mathematical model; (ii) Using a lookup table or database, determine the thickness of the one or more dried uncompensated layers at the one or more locations based on the uncompensated image data and the substrate geometry; or (iii)(i) and (ii) both.

9. The method of claim 1, wherein step c. determining the compensation image data for compensating for thickness variations includes adjusting the volume of fluid to be injected at a given location.

10. The method according to claim 9, wherein, Adjusting the volume of fluid to be injected at a given location includes increasing or decreasing the volume of fluid to be injected at that location.

11. The method of claim 1, wherein step c. determining the compensated image data comprises: (i) Use lookup tables; (ii) Determine the compensated image data using mathematical methods; (iii) Determine the location of the strip joint and / or the orientation and / or curvature and / or other geometric features of the complex substrate; (iv) Use pattern-based volume changes; or Any combination of (v)(i)-(iv).

12. The method of claim 11, wherein for the strip connection: Step c. Determine the compensation image data used to compensate for thickness variations between adjacent strips, including gradually decreasing droplet size and / or spacing over a portion of one or two strips near the junction; and / or Step c. Determine the compensation image data to compensate for thickness variations by printing half the volume on a portion of the initial strip near the joint, and printing the other half the volume on a portion of the subsequent strip near the joint.

13. The method of claim 1, wherein the fluid is a coating composition having a solids content of from about 5% to about 70%, and comprising: 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.

14. The method of claim 13, wherein: The fluid is further defined as a solvent-based coating composition having a solids content of about 25% to about 60%; or The fluid is further defined as a water-based coating composition having an initial solids content of about 5% to about 45%.

15. A droplet ejection apparatus for carrying out the method of any one of the preceding claims, comprising: One or more microdroplet ejectors; as well as One or more motion devices, Wherein, the one or more microdroplet ejector heads are mounted on the one or more motion devices; and Optionally, one or more of the one or more microdroplet ejectors have grayscale capability.

Images