KR20210029723A - Direct-to-mesh screen stencil creation - Google Patents

Abstract

A direct-to-mesh (DtM) screen printer is provided that generates screen stencils. The DtM screen printer includes a frame 114 that holds the pre-stretched mesh 112 in place during application of the sprayable emulsion 206, a fixture 116 that holds the frame 114, and the pre-stretched mesh 112. A platen 124 holding the release liquid 122 on one side, a fluid dispenser 126 for spraying the release liquid 122 onto the platen 124 or the mesh 112, and a dictionary opposite the platen It includes a printer carriage that supports the print head 132 for printing a sprayable emulsion 206 on the side of the stretched mesh 112. Also provided is a method of creating a screen stencil for screen printing using a DtM screen printer.

Description

Direct-to-mesh screen stencil creation

The present invention relates to a printer and method for generating a direct to mesh screen stencil.

Screen printing is a printing technique in which ink is transferred onto a substrate using a mesh, excluding areas where ink is not impregnated by a screen printing stencil, also called a blocking stencil. A blade or squeegee moves across the screen to fill the open mesh openings with ink, and then by a reverse stroke causes the screen to momentarily contact the substrate along the contact line. This causes the ink to wet the substrate and withdraw from the mesh opening as the screen bounces after the blade passes.

Creating screen printing stencils is a tedious and labor-intensive task. This is one of the many process steps, chemicals, and large amounts of water required, and is mostly manual. This is currently the least automated part of the screen printing business.

This application claims priority in application number PCT/EP2017/050214 filed on January 5, 2017.

Features of the embodiments of the present invention will become apparent with reference to the following detailed description and drawings, wherein the same reference numerals correspond to similar but not identical components. For the sake of brevity, reference numerals or features having the above-described functions may or may not be described in connection with other figures in which they appear.

1 shows a direct-to-mesh screen printer according to an embodiment of the present invention.
2A-2E are cross-sectional views showing process elements in screen printing using a direct-to-mesh screen printer according to an embodiment of the present invention.
3A-3B provide a comparison between the current technology (FIG. 3A) and the teachings of the present application (FIG. 3B) according to an embodiment of the present invention, schematically showing an emulsion on a mesh.
4 is a flowchart showing a screen printing method according to an embodiment of the present invention.

There are several examples of conventional solutions for forming a stencil for screen printing by directly coating a mesh. Now these are explained.

Mesh preparation and coating:

Direct application of the emulsion: This is done by machine or by hand. Both sides of the screen are appropriately coated by coating with an emulsion. The mechanical or automated version is strictly a machine that replaces humans. The machine is much more accurate in that it applies the correct amount of emulsion and obtains a uniform coating. Machines are generally less wasteful.

Capillary membrane: A capillary membrane is a membrane pre-coated with an emulsion. The mesh is supersaturated with water and the membrane is placed against the supersaturated mesh (emulsion facing down). The emulsion is pulled into the mesh by capillary action. This provides a more accurate coating of the emulsion in both thickness and cover. Once the emulsion has diffused into the mesh, the film peels off.

Once the screen mesh is emulsified, it must be dried. Once dried, the image is ready to be transferred or stenciled. As the emulsion dries, it shrinks and follows the mesh, resulting in a rough and uneven surface (this rough surface leads to accelerated aging of the squeegee during the printing process).

Most emulsions today are activated by ultra-violet (UV) radiation (i.e., UV-activated), but can also be activated with visible light. Once coated, you need to somehow protect the stencil from exposure to light (normal visible light also has enough UV to start the curing process). Hereinafter, it is assumed that the emulsion is UV activated/cured.

Image transfer/stencil manufacturing:

In screen printing, there is one stencil for all colors, typically cyan, magenta, yellow and black (CMYK), plus one stencil for all spot colors (the spot color is one based on a discrete color). Color, and usually may not be easy to achieve with CYMK colors). Areas of the stencil in the stencil that do not want ink to pass through are then blocked by the emulsion that is cured to form the stencil, and all other areas have only meshes. Any openings in the mesh can be completely blocked or partially blocked by the emulsion to form a stencil.

Film Positive Ink: An entirely black layer of ultraviolet (UV) absorber is printed on a transparent plastic sheet. Printing is generally performed by laser or inkjet printers with special film positive inks (film positive ink means a high opacity black ink that completely blocks all visible and ultraviolet). Next, the film is attached to the pre-coated mesh and then exposed to ultraviolet light. The attachment is usually a removable tape (such as a masking tape). Once exposed, the film is removed and the uncured emulsion is washed away.

However, this approach is very labor intensive at all steps and it is impossible to automate many steps. In addition, during film mounting, errors such as requiring adjustment of the final stencil using the correct film prior to printing are liable to occur. In addition to many consumables (inks, membranes), it requires a lot of chemicals and cleaning.

Thermal screen: In this method, the mesh is pre-coated with a thermally activated emulsion. Typically, the (frameless) mesh is placed in a thermal printer, where the emulsion is directly cured/activated. Once completed, the unexposed emulsion is washed away, and the stencil is mounted on the frame and printed.

However, this approach suffers from limited mesh counts. Also, the emulsion is not robust. The pretreated mesh is expensive. Stencil alignment is more intensive. Finally, the stencil can be damaged while it is being mounted.

Computer to Screen (CtS)-Printing: In this method, the coated mesh is printed directly on a screen emulsified with high transparency black ink. This is similar to a membrane positive ink without a membrane. All processes are the same.

However, these machines require high opacity inks that are more expensive than regular inkjet inks.

CtS-wax: This method is closely related to CtS-printing, but it uses wax to block UV light. Everything else is the same.

However, due to the use of molten wax, these machines can be hard to hear. In addition, these machines require the wax to be heated and applied to the mesh.

CtS-direct exposure: This technique directly exposes the emulsion using a UV laser.

However, the machines used in this technology are typically very expensive. Also, this process does not work well with coarse grade meshes. Finally, UV lasers are still very expensive if they need to be replaced.

Each of these methods requires some post-treatment/follow-up measures. Except for thermal activation and CtS direct exposure, all stencils should be exposed after image blocking (film or CtS-printing and wax) has been applied. This process is a powerful developer and takes about 1 to 2 minutes per screen.

Excess emulsion should be washed off from all screens. Care must be taken to ensure that the emulsion does not enter the drainage system. The screen should be dried after cleaning.

In the case of membrane and thermal activation methods, the finished stencil must be fine-tuned when placed in a carousel to ensure proper recording.

Current initiation:

It is clear that a simpler approach using less chemicals and less water is desirable.

As described and claimed herein, and in accordance with the teachings herein, the Direct to Mesh (DtM) approach to forming a stencil involves applying and activating/exposing an emulsion directly on a screen using inkjet technology. Includes. In particular, in accordance with the teachings herein, a DtM screen printer:

A frame that holds the pre-stretched mesh in place during application of the sprayable emulsion;

A fixture for holding the frame;

A platen for holding a release liquid on one side of the pre-stretched mesh;

A fluid dispenser for spraying the release liquid onto the platen or mesh; And

And a printer carriage supporting a print head for printing the sprayable emulsion on the side of the pre-stretched mesh opposite the platen.

1 is a block diagram showing the direct-to-mesh (DtM) printer 100. The DtM printer 100 includes a mesh support system 110 comprising a pre-stretched mesh 112 held in place by a frame 114. Frame 114 is in turn held by fixtures 116. The fixture 116 holds the frame 114 rigid and rigid by the pre-stretched mesh 112 in place during application of the sprayable emulsion.

As used herein, mesh 112 is made of connected strands of woven fabric, fiber, metal, or other flexible/flexible material, here woven in a cross pattern. The material comprising the mesh may include a number of fabrics (silk, polyester); Metals such as stainless steel; Plastics such as polypropylene, polyethylene, nylon, polyvinyl chloride (PVC), or polytetrafluoro-ethylene (PTFE); Or any of glass fibers. The diameter of the strands may be any diameter conventional in screen printing, and the mesh size may also be any size conventional in screen printing. Coarser meshes are typically woven into larger diameter (gauge) strands, which require a thicker emulsion application.

The DtM printer 100 further includes a platen support system 120 comprising a release liquid 122 held against one side of the mesh 112 pre-stretched by the platen 124. The platen 124 firmly holds the release solution 122 against the bottom of the pre-stretched mesh 112. The platen 124 is constructed as smooth and impermeable as possible, and is resistant to dents and cracks. Platen 124 also dissipates energy from UV curing source 208 (not shown in FIG. 1, but shown in FIG. 2D).

The release solution 122 can be applied directly to the platen 124 or mesh 112 once placed on the platen 124 (eg, sprayed, wiped or brushed) prior to applying the sprayable emulsion. For example, the fluid dispenser 126 for injecting or spraying the release liquid 122 into the platen 124 may include one or more nebulizers 126. Nebulizer 126 may be a conventional nebulizer or other nebulizing element.

The release liquid 122 does not react with the cured emulsion, thereby suppressing the dot-gain and diffusion of the printing solution into the printing medium. Since the emulsion cures very quickly after spraying, the dot-gain only needs to be suppressed for a short period of time.

Finally, the DtM printer 100 includes an inkjet printer 130 comprising a print head 132 mounted on a printer carriage 134. The print head 132 prints a sprayable emulsion on the side of the pre-stretched mesh 112 on the opposite side of the platen 124. The printer carriage 134 is a high precision printer carriage that is accurate in both the X and Y Cartesian directions to support accurate droplet placement over one or more passes while accumulating the ejectable emulsion. In fact, emulsions can be "built up" to accommodate a wide range of mesh gauges, from very fine to very coarse. Layering can be used to maintain high resolution as the emulsion accumulates.

Print head 132 may be an inkjet printhead including thermal inkjet, piezoelectric inkjet, drop-on-demand inkjet, or any other suitable jetting printhead capable of jetting fluids, including jettable emulsions disclosed herein.

The screen mesh 112 is stretched on the frame 114, of any type, which can be very expensive or inexpensive and of any gauge. The frame 114 is put into the inkjet printer 130 together with the release liquid 122 disposed on the platen 124. Next, the jettable emulsion is applied to the masking area by the inkjet printer 130 and exposed substantially simultaneously to a high intensity UV lamp such as a light emitting diode (LED) or other suitable UV source. For optimal performance, the wavelength of the UV lamp (or LED) can be adjusted to the reaction range of the sprayable emulsion. In the case of the sprayable emulsion disclosed herein, the emulsion reacts at a wavelength of 395 nm. Other sprayable emulsions may have other reaction wavelengths, including wavelengths lower than 395 nm. In the case of a coarse mesh, application can be a multipass operation to accumulate the required emulsion thickness. “Coarse mesh” means a mesh with a loose weave and thus a larger gap between strands than a fine mesh screen. For example, a 335 mesh count is considered a fine mesh, whereas a 110 mesh count is considered a coarse mesh, where the mesh count is the number of yarns intersecting per square inch.

The direct-to-mesh process disclosed herein is carried out through recent developments for low viscosity sprayable emulsions. "Low viscosity" means a range from about 4 centipoise (cP) to about 15 cP (from about 4 milliPascal seconds to about 15 milliPascal seconds). These new sprayable emulsions are used by UV printers to create an embossing effect on a wide variety of materials. In addition, these new sprayable emulsions are more elastic and can therefore be used in place of the previous emulsions. Light cyan or light magenta can be used to identify the stencil to provide some contrast, but any color, including transparent or vivid colors, can be used in the jettable emulsion.

An example of a sprayable emulsion that can be suitably employed in the process disclosed herein is a UV activated acrylate monomer having elastomeric properties after curing. Sprayable emulsions are special embossed "varnish" polymers that quickly cure into both a highly durable/resistant layer that quickly accumulates on the substrate. In addition, the cured polymer is durable and flexible/elastic (if the polymer is hard, it will easily crack when used and render the stencil useless). The VersaUV (Roland DG) technology is an example of a material useful in carrying out the teachings herein.

The release fluid 122 is configured to provide a smooth and non-reactive printing surface under the mesh 112. It also serves to limit the dot gain of the printed emulsion. Dot-gain occurs when the sprayed droplet (or dot) expands or spreads before UV exposure. This is especially important when employing half tones, i.e. when the entire space in the mesh is filled with emulsion. However, since UV curing occurs very quickly after the emulsion is sprayed, the dot-gain needs to be suppressed only for a short time.

The release liquid 122 is a fluid that manages the dot gain and does not lift or separate the emulsion from the mesh 112 because it does not react with the cured emulsion. The fluid in the release solution 122 is modified or customized for a dispersible emulsion by changing certain properties, including, but not limited to, surface tension, ionic mixture, polar or non-polar components, or whether the fluid is water-soluble or non-aqueous. Can be.

The release liquid 122 may be an aqueous base (eg, distilled water), and water may be used alone or together with at least one emulsifier to prevent evaporation of the release liquid. Along with the class of emulsifiers known as surfactants, examples of emulsifiers include, but are not limited to, polysorbate, glycerin and glycols, such as butyl cellosolve. In some embodiments, the emulsifier may be present in an amount of at least 3v% to 5v% to prevent evaporation of the release liquid. Additional examples of release solutions include aqueous based varnishes such as butylacetate, xylene, xylol, dimethyl benzene, and combinations thereof.

The release liquid 122 is deposited on the platen 124 or the mesh 112 after the mesh is disposed on the platen 124. In most manufacturing processes by current technology, emulsions can be quite rough; This is often caused by the emulsion acclimating to the mesh during the drying process. Such coarse emulsion surfaces can be abraded in the squeegee, which requires resurfacing of the blade or replacement of the squeegee blade. However, in the direct-to-mesh process, the release liquid 122 ensures a very smooth surface when the sprayable emulsion is built into the mesh; See, for example, FIG. 3B and related discussion.

Since the only emulsion applied to the mesh 112 is in the blocking area, there is no overshoot or overexposure due to reflection of ultraviolet rays into the masked area. This gives a smoother and cleaner image. (These overshoot and exposure areas can create spots or drops inside the image, especially around the edges. They are "inverse" with the pinhole.)

The platen 124 provides a smooth, hard, and impermeable surface for the release liquid 122, and gently presses the mesh 112 to ensure a uniform and flat surface that is good for applying the emulsion. In some embodiments, the platen 124 does not absorb the release fluid 122 or does not chemically or physically interact with it, and is planar (e.g. 0.05 mm/meter). By “smooth” is meant that the surface of the platen 124 is a regular surface, which may be polished/gloss or translucent/matte as long as the surface is regular.

Exemplary steps of the direct-to-mesh process are shown in Figures 2A-2E, which are cross-sectional views of the DtM device.

In FIG. 2A, frame 114 surrounds platen 124. The fixture 116 for supporting the frame 114 is omitted in FIGS. 2B to 2E for clarity. The fixture 116 is similar to the conventional one currently in use. One or more elements or sprayers 126 spray the release fluid 122 onto the top surface 124a of the platen 124. The sprayer 126 may be secured in place or configured to traverse the platen 124. The release solution can be applied in a variety of ways; For example, not only spraying, but also wiping, brushing, etc.

In FIG. 2B, the mesh 112 is disposed on the frame 114. Below the mesh 112 is a platen 124 with a thin and uniform coating of release liquid 122 supported on the platen surface 124a. In some embodiments, the thickness of the release liquid 122 is about 20 micrometers (um), but in any case, it is smaller than the gauge of the mesh and is within a 0.5 um plan view. The release liquid 122 backs up the mesh 112 to provide good coverage when a sprayable emulsion is applied. The release liquid 122 is formulated to prevent the sprayable emulsion from adhering to the platen 124. The formulation of the release solution 122 prevents the emulsion from sticking, reacting or otherwise adhering to the platen. In some cases, the emulsion may react with the release liquid 122, but the interaction/reaction may generally disallow any adhesion to the platen 124. When the adhesion to the platen 124 is greater than the adhesion to the mesh 112, the emulsion may be separated/peeled from the mesh. This can lead to pinholes or exposed patches. In the worst case, the mesh can be damaged or torn.

In FIG. 2C, the platen 124 is moved to the mesh 112 together with the release liquid 122, and presses the release liquid against the back surface of the mesh while tightening the mesh. This provides a smooth, tension-level, flat print surface. The movement of platen 124 is indicated by arrow 202.

In Fig. 2D, the print head 132 convertible by the printer carriage 134 (not shown in Fig. 2D, but shown in Fig. 1) is a blocking image or stencil 206 (see Fig. 112), where the blocking image is opposite or negative to the actual image to be printed or screened on a suitable print medium. Print head 132 moves laterally along the direction indicated by arrow 204 to form screen stencil 206 on mesh 112. "Ink", as described above, is essentially a UV sprayable emulsion that is cured by the UV source 208 as it is applied. In one embodiment, the UV source travels laterally along the direction indicated by arrow 210. This is similar to what happens in conventional UV printers. 2D shows the printer head 132 and UV source 208 moving across the mesh 112. However, the mesh support system including the mesh 112 and frame 114 (and fixture 116) can be translated relative to the print head 132 and UV source 208. UV sources 208 may be mounted on either side of the printer head 132 to facilitate bidirectional printing of the mesh 112.

In Figure 2e, the resulting stencil 206 is shown. The stencil 206 can be removed from the printer and can be used immediately without any other preparation or processing.

In some embodiments, the layer 128 may be placed on the surface 124a of the platen prior to spraying the release liquid 122. The layer 128 will be referred to herein as a "background type". The platen 124 was kept at a constant height and then a "background" 128 was placed thereon. Examples of background type 128 are 4mm mirror, 2mm clear glass, 2X glass (top), polyethylene white, glass (top)/mirror (bottom), 4mm glass (top), and 3mm mirror. For example, if a 4mm mirror is used, the printed surface is 2mm higher than that of 2mm clear glass. Sometimes different results have been achieved with the "two-factor background". For example, "2X Glass" consisted of 2 sheets of transparent glass. "The glass (top)/mirror (bottom) was a piece of 2mm glass on top of a 2mm/4mm mirror. Without support for any particular theory, using two plates would have some light reflection/deflection where the two surfaces meet in the middle. It is believed to produce a polyethylene white sheet of white polyethylene.

The comparison of results according to one embodiment is shown in FIGS. 3A and 3B. Both figures show the emulsion applied to the mesh 112.

In Figure 3a, in the combination 300 of the conventional well-spread emulsion 302 and the mesh 112 that can be spread out, the emulsion includes the top of the mesh and the bottom of the mesh, the warp and weft of the mesh (strand 112a, 112b)) appears to be conformal. This occurs conformally as the spreadable emulsion 302 is air dried on the mesh 112. In particular, FIG. 3A shows how the emulsion 302 applied in a conventional manner shrinks as the emulsion dries on the mesh 112 after being applied by hand or by an applicator machine. This shrinkage inevitably occurs as the water component dries. Emulsion 302 is one of those commonly used in the art.

In Figure 3b, in the combination 350 of the inventive sprayable emulsion 302' and mesh 112, the sprayable emulsion appears to have a flat bottom surface 302'a, which is the platen 124 ( And a smooth surface 124a of the release liquid 122 thereon. The top surface 302'b of the sprayable emulsion 302' appears to be less conformal to the warp and weft of the mesh 112 than the current emulsion 302 (the bottom surface 302'a is the actual screen printing process). This is where the screen ink is applied and pressurized using a squeegee during the process). In the case of DtM, since the mesh 112 has the release fluid 122 supported by the smooth platen 124, the lower portion 302'a of the emulsion 302' is more nearly planar or flat. This is also the result of essentially instant curing by ultraviolet light.

This process is a direct-to-mesh (DtM) process to differentiate it from computer to screen (CtS), which requires additional processing both before (i.e. application of the emulsion) and after (cleaning of unexposed emulsions and inks). ). In the DtM process, since no additional treatment is required before and after the application of the sprayable emulsion 302', the generation of the stencil 206 is simple.

4 shows a flowchart of an exemplary DtM process 400 according to the present disclosure for preparing a stencil for screen printing. In the DtM process 400, a direct to mesh screen printer 100 is provided (405). As described above, the DtM screen printer 100 includes a fixture 116 that holds the frame 114, which frame holds the pre-stretched mesh 112 in place during application of the sprayable emulsion 302'. Keep. The platen 124 of the DtM printer 100 holds the release liquid 122 against one side of the pre-stretched mesh 112. Finally, the DtM screen printer 100 is a printer carriage supporting the print head 132 for printing a sprayable emulsion 302' on the side of the pre-stretched mesh 112 opposite the platen 124. It includes (134).

The DtM process 400 leads to a process 410 of placing the frame 114 in the fixture 116. The fixture 116 is part of the DtM printer 100 and is adapted to accommodate a frame 114 of a wide variety of sizes. The fixture 116 accurately fixes the frame 114 in place so that the print carriage 134 is accurately recorded on the mesh 112.

The DtM process 400 continues with 415 applying the release fluid 122 directly to the platen 124 or through the mesh 112. Applying the release liquid 122 may be effective when applied directly to the mesh 112 as previously applied to the platen 124. This can be important for very large stencils or very high dot densities such as 5,000 DPI. In this case, the release liquid 122 may have time to evaporate even if a good emulsifier is used.

In any case, the platen 124 coated with the release liquid 122 comes into contact with the mesh 112 (or the platen 124 comes into contact with the mesh 112 and the release liquid 122 is applied to the mesh. do). In some embodiments, platen 124 may be raised from about 1 millimeter (mm) to about 2 millimeters above the level of the mesh to provide tension to mesh 112.

The DtM process 400 follows a process 420 of applying a sprayable emulsion 302' to the mesh 112. As described above, the jettable emulsion 302' is applied to the mesh 112 by the inkjet printer 130, where the print head 132 jets the jettable emulsion.

The DtM process 400 ends with a process 425 curing the sprayable emulsion 302' using ultraviolet light. Any conventional UV source can be used to cure the sprayable emulsion 302'.

At the end of the DtM process 400, a stencil 206 is formed and cured, ready to be used to screen print the color onto a suitable printing surface, such as, for example, clothing. In particular, the sprayable emulsion after curing forms a screen stencil, where openings in the screen stencil are used to print the image on the printing surface.

Example

Four series of examples were performed. In the examples and tables, the following definitions are now provided.

"Mesh resolution" refers to the number of threads per centimeter (cm). The mesh resolution can include letters representing the thread diameter, such as S (small diameter), T (medium diameter), or HD (heavy diameter). For example, "43T" is a mesh with 43 threads per cm of median diameter.

"Frame type" refers to the type of frame 114 used, and may be a roller frame, aluminum or large roller frame. The “aluminum” frame was a fixed square metal aluminum frame with a mesh bonded with a certain tension before starting. Typical tension values were about 26 Newtons (N). The “roller frame” was a tensile frame that allowed the tension of the mesh to be changed after the stencil was stretched. Roller frames are much more expensive than standard square frames, but they are much easier to keep tension properly and re-stretch. The large roller frame was slightly larger than the roller frame.

The metal mesh was stainless steel and nickel plated mesh. This type of mesh is often used on rotating screens or screens that are exposed to aggressive fluids or are used for long periods (multiple prints/presses) on the same stencil.

"Unit resolution" is the dot density interweave (DPI) jetted from the print head.

"Pulse number" refers to the number of ignition pulses transmitted to individual nozzles.

The print head used has 8 nozzle rows. The heading "Ink Channel" refers to the number of rows used to eject the fluid. "All" means all 8 columns. The notation "11100111" indicates that the middle two lines have not been fired. This gives the effect of a "gap" between jets.

"UV %" refers to the intensity of the UV radiation emitted by the adjustable UV LED source 208. The intensity of the UV LED source 208 was modulated with a Pulse Width Modulator (PMW) to control the intensity of the generated UV light. The maximum value of the UV source 208 used is 100W/cm ² . For example, the notation of 60% means that 60% of the UV rays have been modulated to 60% of the total intensity.

"Release liquid" means the composition of the release liquid 122 applied to the platen 124.

"Background type" is meant to be used on the surface of the platen 124. The platen 124 was kept at a constant height and the “background” was placed on top of the platen. Examples of background types are 4mm mirror, 2mm clear glass, 2X glass (2 pieces of 2mm clear glass), "Glass (top)/mirror (bottom)" (2mm clear glass over 2mm/4mm mirror) and "polyethylene white" (white Polyethylene sheet).

"TEM" means total emulsion measurement and is a unit of measurement of emulsion thickness. Often the EoM (emulsion over mesh) value is used, but this is the ratio of the emulsion thickness divided by the mesh thickness. Here, the number in um indicates the total thickness including the thickness of the emulsion and the thickness of the mesh.

"Smoothness" refers to the smoothness of the stencil. On the side of the platen, the surface should be very smooth to the touch without noticeable roughness. On the printing side, the surface should be smooth to the touch. Some roughness (similar to what can be experienced with opaque glass) was considered "acceptable". In the test results considered "unacceptable", the surface was generally sandpaper-like.

The smoothness results are based on a subjective rating, where 1 is acceptable, 2 is slightly acceptable, 3 is slightly unacceptable, and 4 is unacceptable.

"Result" represents a subjective evaluation of the overall result of the experiment. The same subjective rating scale as described for smoothness is also used here.

"A4 print time" means the time taken to print a screen of A4 paper size (21.0 cm x 29.7 cm).

Example series 1

In Example Series 1, 6 experiments were conducted. Details are shown in Tables 1 (test variables) and 2 (results) below. All experiments used the experimental ink, sprayable emulsion UV Super Flex 100 ink. In each case the mesh color was white. Frame types varied as roller frames, aluminum or large roller frames, as listed in Table 1. The unit resolution in each case was 1440 DPI. In each case, the printing speed was 300 cm/sec. The number of pulses is shown in Table 1. In the first four experiments, all eight ink channels were fired, but in the last two experiments, the middle two nozzle rows of the print head were not fired, creating a gap. In each case the UV was 60% of the total intensity. In all six experiments, the release solution was 100% distilled water. In the first three experiments, the background type was a 4mm mirror and in the last three experiments it was a 2mm clear glass.

As can be seen in Table 2, TQM ranged from 10um to 22um (Experiments 1, 4, 5, 6); TQM was not obtained for experiments 2 and 3 due to the lack of a sealed mesh. For Experiment 1, the smoothness and results were acceptable, but the mesh stuck to the mirror and the TQM of 22pm was considered too high. In experiments 4, 5 and 6, acceptable smoothness and results and sealed mesh were calculated.

It seems that the 2mm clear glass gave better results than the 4mm mirror and the 2 pulses gave better results than the 1 pulse. It is also noted that the frames used in Experiments 2 and 3 were aluminum.

Example Frame type Number of pulses Ink channel UV% Release liquid Background type 1-1 Roller frame 2 all 60% 100% water 4mm mirror 1-2 aluminum One all 60% 100% water 4mm mirror 1-3 aluminum One all 60% 100% water 4mm mirror 1-4 Large roller frame 2 all 60% 100% water 2mm clear glass 1-5 Large roller frame 2 11100111 60% 100% water 2mm clear glass 1-6 Large roller frame 2 11100111 60% 100% water 2mm clear glass

(DtM test, mesh = 43T, unit resolution = 1440 DPI → test variable)

Example TEM Smoothness result comment A4 printing time 1-1 22um One One Good line quality, TQM too high,
The mesh is attached to the mirror 14 minutes 1-2 4 4 Unsealed mesh 14 minutes 1-3 4 4 Unsealed mesh 14 minutes 1-4 13um One One Sealed mesh 14 minutes 1-5 10um One One Sealed mesh 14 minutes 1-6 10um One One Sealed mesh 14 minutes

(DtM test, mesh = 43T, unit resolution = 1440 DPI-result)

Example series 2

In Example Series 2, 12 experiments were conducted. Details are shown in Tables 3 (test variables) and 4 (results) below. All experiments were used with sprayable emulsion UV Super Flex 100 ink. In each case the mesh color was yellow. In each case, the frame type was aluminum. In each case, the unit resolution was 1080 DPI. The printing speed was 375 cm/sec. The number of pulses is shown in Table 3. All eight ink channels were ignited in all experiments. UV was 60% of the total intensity in all experiments except for Experiment 11, which was 40% of the total intensity. The release solution 122 was as specified in Table 3. Background types are shown in Table 3.

As can be seen in Table 4, TQM ranged from 7um to 20um; No TQM was obtained for Experiment 5. For experiments 1-4, 6 and 12, smoothness and results were acceptable. For experiments 7 and 8, smoothness and results were slightly acceptable. In Experiments 5, 9, 10 and 11, both smoothness and results were unacceptable. As indicated in Table II, these experiments resulted in the mesh sticking to the printing surface of the platen.

The only difference between Experiments 4 and 5 is the type of background used, which is 2 x glass top vs. It was polyethylene. The former has better results than the latter.

The only difference between Experiments 4 and 7-8 is the type of background used, 2 x glass top vs. It was on 4mm glass. The former has better results than the latter.

Regarding experiments 9, 10 and 11, these were the only experiments with a liquid containing 95% distilled water and 5% ANODAL ASL (Gedacolor). Other liquids such as 100% distilled water, 80% distilled water + 20% dead sea salt, 80% distilled water + 20% alcohol and 50% distilled water + 25% window cleaner + 25% isopropanol are all acceptable or slightly acceptable Provided possible smoothness and results.

Example Number of pulses Ink channel UV% Release liquid Background type 2-1 3 all 60% 100% water 2x glass (top) 2-2 3 all 60% 80% water, 20% salt (dead sea) 2x glass (top) 2-3 3 all 60% 80% water, 20% isopropanol 2x glass (top) 2-4 3 all 60% 50% water, 25% window cleaner, 25% isopropanol 2x glass (top) 2-5 3 all 60% 50% water, 25% window cleaner, 25% isopropanol Polyethylene white 2-6 3 all 60% 50% water, 25% window cleaner, 25% isopropanol 2x glass (top)/mirror (bottom) 2-7 3 all 60% 50% water, 25% window cleaner, 25% isopropanol 4mm glass (top) 2-8 3 all 60% 50% water, 25% window cleaner, 25% isopropanol 4mm glass (top) 2-9 3 all 60% 95% water, 5% ANODAL ASL liquid (Gedacolor) 4mm mirror 2-10 3 all 60% 95% water, 5% ANODAL ASL liquid (Gedacolor) 4mm mirror 2-11 3 all 40% 95% water, 5% ANODAL ASL liquid (Gedacolor) Glass (top)/mirror (bottom)) 2-12 3 all 60% 80% water, 20% salt (dead sea) Glass (top)/mirror (bottom))

(DtM test, mesh = 43T, unit resolution = 1080 DPI → test variable)

Example TEM Smoothness result comment A4 printing time 2-1 14um One One 10 minutes 2-2 20um One One 10 minutes 2-3 14um One One 10 minutes 2-4 7um One One 10 minutes 2-5 4 4 The mesh is attached to the polyester 10 minutes 2-6 7um One One Excellent line quality 10 minutes 2-7 7um 2 2 Excellent line quality 10 minutes 2-8 7um 2 2 Excellent line quality 10 minutes 2-9 15um 4 4 Mesh adheres smoothly to the mirror 10 minutes 2-10 15um 4 4 Mesh adheres smoothly to the mirror 10 minutes 2-11 15um 4 4 Mesh adheres smoothly to the mirror 10 minutes 2-12 7um One One Excellent line quality 10 minutes

(DtM test, mesh = 43T, unit resolution = 1080 DPI-result)

Example series 3

In Example Series 3, 5 experiments were performed. Details are shown in Tables 5 (test variables) and 6 (results) below. All experiments were used with sprayable emulsion UV Super Flex 100 UV ink. In each case the mesh color was yellow. In each case, the frame type was aluminum. In each case, the unit resolution was 1080 DPI or 1440 DPI. The printing speed was 300 cm/sec or 375 cm/sec as specified in Table 5. The number of pulses is shown in Table 5. In all experiments, the middle two nozzle rows of the print head did not ignite, leaving a gap ("11100111"). UV was 60% of the total intensity. The release solution 122 was 100% distilled water in all six experiments. The background type for all experiments was a 4mm mirror.

As can be seen in Table 6, TQM varied from 3um to 45um.

The smoothness was acceptable in all experiments, while the results were acceptable in experiments 3, 4 and 5. In Experiments 1 and 2, the mesh was slightly sticky and the result was slightly unacceptable.

In Experiments 1 and 2, the number of pulses was the same for both (2), whereas in Experiments 3, 4, and 5, the number of pulses was different (1). Due to this difference, it seems that the results were slightly unacceptable in Experiments 1 and 2.

Example Mesh resolution Unit resolution Speed, cm/sec Number of pulses Background type 3-1 120T 1080DPI 375 2 4mm mirror 3-2 120T 1440DPI 300 2 4mm mirror 3-3 43T 1080DPI 375 One 4mm mirror 3-4 43T 1440DPI 300 One 4mm mirror 3-5 43T 1440DPI 300 One 4mm mirror

(DtM test, mesh = 120T, 43T-test variable)

Example TEM Smoothness result comment A4 printing time 3-1 14um One 3 The mesh is slightly attached 10 minutes 3-2 45um One 3 The mesh is slightly attached 14 minutes 3-3 3um One One 10 minutes 3-4 7um One One 14 minutes 3-5 7um One One 20 minutes

(DtM test, mesh = 120T, 43T-result)

Example series 4

In Example Series 4, four experiments were conducted. Details are shown in Tables 7 (test variables) and 8 (results) below. The mesh resolution in all cases was 195 (US standard). All experiments were used with sprayable emulsion UV Super Flex 100 UV ink. The mesh color in each case was gray/metal. The frame type was metal. In each case, the unit resolution was 1440 DPI. The printing speed was 300 cm/sec. The number of pulses was 1 in all experiments. In all experiments, the middle two nozzle rows of the print head did not ignite, leaving a gap ("11100111"). In Experiment 1-3, UV was 60%, 40%, and 30% of the total intensity, respectively, whereas in Experiment 4, UV was 30% of the total intensity. The release solution of Experiment 1-3 was distilled water; In Experiment 2, no release solution was used. The background type for both experiments was a 3mm mirror.

As can be seen in Table 8, the TQM was 14 μm in all experiments. In Experiment 1-3, both smoothness and results were unacceptable, whereas in Experiment 4, smoothness and results were acceptable.

In Experiments 2 and 3 of Example 1 described above, the frame was aluminum, and both experiments showed unacceptable smoothness and results using 100% distilled water. In Experiment 1 of Example 4, the frame was metal and similar results were obtained, which was unacceptable. On the other hand, in Experiment 2 of Example 4, the frame was also metal, but no liquid was used, and acceptable smoothness and results were observed. Obviously, the combination of liquid and frame is one of the factors as to whether or not you can achieve acceptable softness and results. It has been shown that under certain conditions, better results can be obtained without release liquid or backing paper. Based on the tests described above, emulsions that work without any backing surface can be formulated.

Example Unit resolution Speed, cm/sec Number of pulses UV% Release liquid Background type 4-1 1440DPI 300 1(28V) 60% 100% water 3mm mirror 4-2 1440DPI 300 1(28V) 40% 100% water 3mm mirror 4-3 1440DPI 300 1(28V) 30% 100% water 3mm mirror 4-4 1440DPI 300 1(28V) 30% No liquid 3mm mirror

(DtM test, mesh = 195 (US standard)-test variable)

Example TEM Smoothness result comment A4
Printing time 4-1 14um 4 4 Emulsion is easily removed without hardening the metal mesh 14 minutes 4-2 14um 4 4 Emulsion is easily removed without hardening the metal mesh 14 minutes 4-3 14um 4 4 Emulsion is easily removed without hardening the metal mesh 14 minutes 4-4 14um One One Emulsion hardens well on metal mesh. The mesh does not adhere to the glass. Some UV ink could have been removed from the glass with a window cleaner 14 minutes

(DtM test, mesh = 195 (US standard)-result)

According to the above embodiments, the result is a fluid (both emulsion and any release liquid); Platen composition (eg single glass, double glass, glass and mirror, etc.); Curing strength (UV 20% ~ 100%); Dot density (1080, 1440); Number of pulses; It seems to be affected or able to be affected by very complex interactions such as. From an analytic point of view, the combinations appear to be almost infinite. Currently, the only way to evaluate a set of variables is practical. That is, each set should be tested according to the teachings herein. However, these tests are not considered inappropriate.

An advantage of the DtM process 400 is that it includes complete removal of stencil preparation and post-treatment as follows;

There is no need for a machine such as an emulsion applicator, a dryer, or a separate exposure device.

Most of the chemicals (excluding degreasing agents) and more than 80% of the water used are removed.

All treatments can be carried out without a special low UV light room. In fact, the DtM process can be performed in normal factory/office lighting or daylight. Sprayable emulsions are stored in UV protected cartridges or bags when handling. It is exposed to sunlight or ultraviolet rays only when sprayed onto the mesh 112.

Since the process disclosed herein can use a conventional, less expensive mesh 112, peeling and remeshing the frame 114 rather than cleaning the mesh involving water and chemicals and special cleaning stations. Can often be more efficient and cheaper.

The raw, raw screen, or mesh 112 is placed in the DtM printer 100 and the fully prepared stencil 206 can be removed from the screen and placed directly on a carousel to print an image on the printing surface. have.

Another advantage of the DtM process 400 is that each stencil 206 is registered very accurately in the mesh 112 so that micro-registration can be skipped when mounted on a carousel. According to the DtM process 400, adjustment is not necessary or necessary as each stencil 206 is accurately positioned in the frame 106 (both absolute and relative). This is done through the use of frame fixtures 116. A registration hole or dot is usually attached to the stencil frame. Each different carousel manufacturer has its own registration system. The frame fixture 116 has the same registration system (or perhaps a different design auxiliary registration system). The frame fixture 116 allows precise alignment of the stencil frame 114. To do this, test prints in 4 (or 6 or more) colors, and then fine-tune the carousel. If all the stencils are created on the same printer without changing the carousel (or the carousel out of alignment), the stencils are aligned correctly.

It will be appreciated that the DtM process 400 disclosed herein has a significant reduction in process chemicals and water, as well as a significant reduction in one or both of process time and complexity, labor, and capital equipment (including special lighting installations).

In addition, the DtM process 400 can also be used for rotating screen printing. Rotary screen printing is used for labeling and other rather narrow but frequently repeated printing processes (wallpaper, linear linoleum, etc.). Rotating screen printing is very fast for this application, where four colors (and any spot colors) are placed in the cylinder and the material is passed down. Rotary screen printing typically uses stainless steel mesh 112 for durability and stability.

Today, many rotating stencils are manufactured by large service bureaus (about three in Europe). Each stencil can cost over 100 euros, and annual stencil replacement costs can reach hundreds of thousands of euros. This does not take into account the inconvenience of using the service station. Many companies can recover the cost of their machines within two quarters, reducing their reliance on expensive service bureaus.

In the foregoing description, a number of specific details may be considered to have been described in order to provide a thorough understanding of the embodiments. However, it is believed that these examples may be practiced without being limited to these specific details. In other instances, well-known methods and structures may not be described in detail in order to avoid unnecessarily obscuring the description of the embodiments. In addition, these examples can also be used in combination with each other.

As used in this specification and the appended claims, the indefinite articles “a”, “an” and the definite article “the” in the singular form include a plurality of referents unless the context clearly dictates otherwise. In the following description, a number of specific details may be regarded as set forth in order to provide a thorough understanding of the embodiments. However, it is believed that these examples may be practiced without being limited to these specific details. In other instances, well-known methods and structures may not be described in detail in order to avoid unnecessarily obscuring the description of the embodiments. In addition, these examples can also be used in combination with each other. In addition, when “about” is used to describe a value, it is meant to include small variations (up to 10%) from the stated value as may be caused by manufacturing variations.

Further, the order of the process steps of the claims may be interchanged as appropriate. For example, spraying the release liquid 122 onto the platen 124 or the mesh 112 may include spraying the release liquid onto the platen and then bringing the platen and the mesh together. Alternatively, the platen and the mesh may be brought together and the release solution may be sprayed onto the mesh.

While a limited number of embodiments have been disclosed, it should be understood that many modifications and variations exist therefrom. For example, due to the new high-speed/ultra-fast print head technology that can allow jetting on a vertical plane, the "orientation" of the printer bed/table can be changed from horizontal to vertical.

Claims (15)

In a direct-to-mesh screen printer that creates a screen stencil,
A frame that holds the pre-stretched mesh in place during application of the sprayable emulsion;
A fixture for holding the frame;
A platen for holding a release liquid on one side of the pre-stretched mesh;
A fluid dispenser for spraying the release liquid onto the platen or mesh; And
And a printer carriage supporting a print head for printing the sprayable emulsion on a side of the pre-stretched mesh opposite the platen.
The method of claim 1,
Wherein the fixture holds the frame rigidly and rigidly together with the pre-stretched mesh in place during application of the sprayable emulsion.
The method of claim 1,
The platen is a direct-to-mesh screen printer, characterized in that the release liquid is held firmly against the bottom of the pre-stretched mesh.
The method of claim 3,
The platen is a direct-to-mesh screen printer, characterized in that it is smooth, hard, impermeable to the release solution, and resistant to dents and cracks.
The method of claim 1,
The release liquid is applied to the platen as a very fine and uniform coating or is applied directly to the mesh located on the platen to prevent adhesion of the platen while the sprayable emulsion is applied. Direct-to-mesh screen printer.
The method of claim 1,
The direct-to-mesh screen printer, characterized in that the release liquid suppresses dot-gain while providing a smooth and non-reactive surface after the sprayable emulsion is cured.
The method of claim 1,
The direct-to-mesh screen printer, characterized in that the release liquid contains water and at least one emulsifier in an amount sufficient to prevent evaporation of the release liquid.
The method of claim 1,
The sprayable emulsion has a low viscosity of about 4 cP to about 15 cP, and has both durability and flexibility/elasticity.
The method of claim 8,
The direct-to-mesh screen printer, characterized in that the sprayable emulsion is a UV-activated acrylate monomer having elastomer properties after curing.
The method of claim 1,
A direct-to-mesh screen printer, further comprising a UV source for curing the sprayable emulsion and forming a stencil for screen printing.
A fixture for holding a frame that holds the pre-stretched mesh in place during application of the sprayable emulsion, a platen for holding a release fluid against one side of the pre-stretched mesh, and of the pre-stretched mesh opposite the platen. Providing a direct-to-mesh screen printer comprising a printer carriage supporting a print head for printing the sprayable emulsion on a side;
Placing the frame on the fixture;
Spraying the release liquid onto the platen or mesh;
Forming the platen and the mesh together in a taut configuration;
Applying the sprayable emulsion to the mesh; And
And curing the sprayable emulsion using UV radiation.
The method of claim 11,
Wherein the sprayable emulsion forms a screen stencil after curing, wherein the openings in the screen stencil are used to image the surface.
The method of claim 11,
The method, characterized in that the release liquid suppresses dot-gain while the sprayable emulsion does not adhere after curing.
The method of claim 11,
Wherein the release liquid comprises water and at least one emulsifier in an amount sufficient to prevent evaporation of the release liquid.
The method of claim 11,
The method of claim 1, wherein the sprayable emulsion is a UV-activated acrylate monomer having elastomeric properties after curing.

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