TWI754827B - Direct to mesh screen printer and method for creating a screen stencil - Google Patents

Abstract

A direct to mesh (DtM) screen printer for creating a screen stencil is provided. The DtM screen printer includes a frame to hold a pre-stretched mesh in place during application of a jettable emulsion, a fixture to hold the frame, a platen to hold a release fluid against one side of the pre-stretched mesh, a fluid dispenser for dispensing the release fluid onto the platen or mesh, and a printer carriage supporting a print head for printing the jettable emulsion on a side of the pre-stretched mesh opposite the platen. A process is also provided, the process being for using the DtM screen printer to prepare the screen stencil for screen printing.

Description

Direct screen printing machine and method of creating screen template

Screen printing is a printing technique in which a mesh is used to transfer ink onto a substrate except for areas where the ink is impermeable by a screen printing stencil (also known as a masking stencil). A blade or scraper moves across the screen to fill the open mesh apertures with ink, and then a reverse stroke causes the screen to momentarily touch the substrate along a line of contact. This causes the ink to wet the substrate and be pulled out of the mesh aperture as the screen springs back after the blade has passed.

The establishment of a screen printing template is a tedious and labor-intensive task. It requires several procedural steps, chemical products, large amounts of water and is mainly manual. It is the smallest automated part of the current screen printing business.

100: Direct Mesh (DtM) Press

110: Mesh support system

112: Pre-stretched mesh

112a: Bundle

112b: Bundle

114: Frame

116: Fixtures

120: Platen support system

122: release fluid

124: Platen

124a: Top Surface/Smooth Surface

126: Fluid Dispenser/Sprinkler

128: Layer/Background Type

130: Inkjet Printers

132: Printing head

134: Press carriage

202: Arrow

204: Arrow

206: Screen Templates/Templates

208: Ultraviolet (UV) Curing Source/UV Source

210: Arrow

300: Combination

302: Spreadable Emulsion

302': Sprayable Emulsion

302'a: Flat bottom surface/underside

302'b: Top surface

350: Combination

400: DtM procedure

405: Step

410: Steps

415: Steps

420: Steps

425: Steps

Features of examples of the invention will become apparent upon reference to the following detailed description and drawings, wherein like reference numerals correspond to similar but possibly different components. For the sake of brevity, an element symbol or feature having a previously described function may or may not be described in conjunction with other figures in which it appears.

FIG. 1 illustrates a direct screen printing press according to one example of the present invention.

Figures 2A-2E depict use in cross-sectional views according to an example of the present invention Elements of a screen printing process of a direct screen printing machine.

3A-3B schematically illustrate an emulsion on a mesh according to an example of the present invention, thereby providing a comparison between the current art (FIG. 3A) and the teachings herein (FIG. 3B).

4 is a flowchart illustrating a screen printing method according to an example of the present invention.

Cross-references to related applications

This application claims the priority of Application No. PCT/EP2017/050214 filed on January 5, 2017.

There are several examples of previous solutions for directly coating a mesh to form a stencil for screen printing. Such examples are now described.

Mesh preparation and coating:

Direct Application of Emulsion: This can be done by a machine or by hand. Both sides of the screen must be coated with emulsion to ensure proper coverage. A machine or automated version is strictly a machine that replaces a human. The machine can more accurately apply precise amounts of emulsion and achieve even coverage. The machine generally has less waste.

Capillary Membranes: These are membranes that are precoated with an emulsion. The mesh is supersaturated with water and the film (emulsion side down) is placed against the supersaturated mesh. Capillary action draws the emulsion into the mesh. This can provide a more precise emulsion coating in both thickness and coverage. Once the emulsion has diffused into the mesh, the film is peeled off.

Once the screen mesh is emulsified, the screen mesh must be dried. Once dry, it is ready for image transfer or stenciling. As the emulsion dries, it shrinks and conforms to the mesh, from This results in a rough, uneven surface. (This rough surface causes accelerated aging of the squeegee during the printing process.)

Today, most emulsions are activated by ultraviolet (UV) radiation (ie, UV activated), but can also be activated by visible light. Once coated, the template must be protected from any light exposure (even ordinary visible light has enough UV to start the curing process). In the following, it is assumed that the emulsion is UV activated/cured.

Image Transfer/Stencil Making:

In screen printing, there is one template for each color (usually cyan, magenta, yellow, and black (CMYK)), and one template for each spot color (a spot color is based on discrete colors, usually Colors that may not be easy to achieve with CYMK colors). Areas of the template, one of which is not intended for ink to pass through, are masked by an emulsion that is then cured to form the template; all other areas have mesh only. Any openings in the mesh can be completely or partially occluded by the emulsion to form the template.

Positive Ink: Print an all-black, UV-absorbing layer onto a transparent plastic sheet. Printing is usually done by a laser or inkjet printer with a special positive ink (positive ink means a high opacity black ink that completely blocks all visible and UV light). The film was then attached to the pre-coated mesh and exposed to UV light. Attachment is usually by a removable tape, such as masking tape. Once exposed, the film is removed and the uncured emulsion washed away.

However, this method is very labor-intensive at all stages and it is not possible to automate many steps. Additionally, this method is prone to errors, such as during installation of the film, during use of the correct film, during adjustment of the final stencil prior to printing. Requires a lot of chemicals and cleaning agents and a lot of consumables (inks, membranes).

Hot Mesh: In this method, the mesh is pre-coated with a heat-activated emulsion. Pass Often, the mesh (without a frame) is placed into a thermal printer where the emulsion is directly cured/activated. Once complete, the unexposed emulsion is washed off, the stencil is mounted on a frame and printed.

However, this method suffers from a limited mesh count. Also, the lotion is not as robust. Preprocessed mesh is expensive. Template alignment is denser. Finally, the template may be damaged when it is installed.

Computer-to-Stencil (CtS) printing: In this method, the coated mesh is printed directly onto an emulsifying screen with a high opacity black ink. This is similar to positive ink without film. All procedures are the same.

However, these machines require a high opacity ink, which is more expensive than normal inkjet inks.

CtS-Wax: This method is a close relative of CtS-printing, but uses wax to block UV light. All other departments are the same.

However, due to the use of molten wax, these machines can be temperamental. Additionally, these machines require heated wax to apply it to the mesh.

CtS-Direct Exposure: This technique uses a UV laser to directly expose the emulsion.

However, the machinery used in this technique is usually very expensive. Also, the program does not work on coarse meshes. Finally, UV lasers are still very expensive when they need to be replaced.

Each of the above methods requires some post-processing/follow-up. Except for thermal activation and CtS direct exposure, all stencils must be exposed after applying image masking (film or CtS printing and wax). This procedure takes about 1 to 2 minutes per screen with a strong developer.

All sieves must wash off excess lotion. Care must be taken so that the lotion does not enter the drainage system. Screens must be dried after washing.

For film and thermal activation methods, the finished template must be fine-tuned when placed on the turntable to ensure proper registration.

Current reveal:

It is clear from the previous description of the current technology that a simpler method using less chemicals and less water is desired.

As disclosed and claimed herein, and in accordance with the teachings herein, a direct mesh (DtM) method for forming a template involves the direct application and activation/exposure of an emulsion onto a screen using inkjet technology. In particular and in accordance with the teachings herein, a DtM printer includes: a frame for holding a pre-stretched mesh in place during application of a sprayable emulsion; a clamp for holding the frame ; a platen for holding a release fluid against one side of the pre-stretched mesh; a fluid dispenser for dispensing the release fluid onto the platen or mesh; and a press carriage, It supports a print head to print the sprayable emulsion on the opposite side of the pre-stretch mesh from the platen.

FIG. 1 depicts a block diagram of a direct mesh (DtM) printer 100 . The DtM printer 100 includes a mesh support system 110 that includes a pre-stretched mesh 112 held in place by a frame 114 . The frame 114 is then held by the clamps 116 . Clamps 116 hold frame 114 and pre-stretch mesh 112 securely and securely in place during application of the sprayable emulsion.

As used herein, mesh 112 is made of connected bundles of textile, fiber, metal, or other flexible/ductile material, here woven in a crisscross pattern. Materials making up the mesh Can be any of several textiles (silk, polyester); metals such as stainless steel; or plastics such as polypropylene, polyethylene, nylon, polyvinyl chloride (PVC) or polytetrafluoroethylene (PTFE); or fiberglass . The diameter of the beam can be any diameter commonly found in screen printing, and the mesh size can also be any size commonly found in screen printing. Coarser meshes are usually woven together with larger diameter (gauge) strands, which require a thicker emulsion application.

The DtM printer 100 further includes a platen support system 120 including a release fluid 122 held against the underside of the pre-stretch mesh 112 by a platen 124 . The platen 124 provides a smooth, flat surface for the release fluid 122 to be held firmly against the bottom of the pre-stretch mesh 112 . The platen 124 is configured to be as smooth as possible, fluid impermeable, and resistant to dents and cracks. Platen 124 may also be used to dissipate energy from a UV curing source 208 (not shown in Figure 1, but shown in Figure 2D).

Once the release fluid 122 is in place over the platen, the release fluid 122 can be applied (eg, sprayed or wiped or brushed) directly onto the platen 124 or onto the mesh 112 prior to applying the sprayable emulsion. For example, a fluid dispenser 126 for introducing or dispensing release fluid 122 onto platen 124 may include one or more sprinklers 126 . The sprayer(s) 126 may be conventional atomizers or other spray-type elements.

Release fluid 122 inhibits dot spreading, an effect of a printing fluid spreading into a printing medium, by not reacting with the solidified emulsion. It is only necessary to suppress point expansion for a short period because curing occurs very quickly after spraying the emulsion fluid.

Finally, the DtM printer 100 includes an ink jet printer 130 including a print head 132 mounted on a printer carriage 134 . The print head 132 is configured to print the jettable emulsion on the opposite side of the pre-stretch mesh 112 from the platen 124 . The press carriage 134 is a high precision press carriage that is accurate in both the X and Y Cartesian directions for Accurate droplet placement is supported in one or more passes while accumulating a sprayable emulsion. In fact, the emulsion can "build up" to accommodate a wide range of mesh sizes, from very fine to extra coarse. Layering can be used to maintain high resolution while accumulating emulsions.

Printhead 132 may be an inkjet printhead, such as a thermal inkjet printhead, piezoelectric inkjet printhead, drop-on-demand printhead, or other suitable printhead capable of ejecting fluids, including the jettable emulsions disclosed herein jet print head.

The screen mesh 112 (which can be of any type, even fairly expensive or cheap and of any size) is stretched onto the frame 114 . Frame 114 is placed into ink jet printer 130 where release fluid 122 has been placed on platen 124 . The jettable emulsion is then applied by ink jet printer 130 to the masked areas and exposed to substantially simultaneous exposure with a high intensity UV lamp or other suitable UV source, such as UV light emitting diodes (LEDs). The wavelength of the UV lamp (or LED) can be tuned to the reaction range of the sprayable emulsion for optimum performance. For the sprayable emulsions disclosed herein, the emulsions were reacted at a wavelength of 395 nanometers (nm). Other sprayable emulsions may have other reactive wavelengths, including below 395 nm. For coarse mesh, coating can be performed in multiple passes in order to build up the necessary emulsion thickness. "Coarse mesh" means having a loosely woven mesh, and thus more than a fine mesh screen, between the bundles. For example, a 335 mesh count is considered a fine mesh, while a 110 mesh count is considered a coarse mesh, where the mesh count is the number of line crossings per square inch.

With the recent development of low viscosity sprayable emulsions, the direct mesh process disclosed herein is possible. "Low viscosity" means a range from about 4 centipoise (cP) to about 15 cP (about 4 mPas to about 15 mPas). These new sprayable emulsions are used to create an embossing effect on various materials using UV printers. These new sprayable emulsions are also more elastic, so they can be more easily used as a replacement for one of the previous emulsions. Any color can be used for the sprayable emulsion (including clear or clear), although light cyan or light magenta can be used to provide a slight contrast to verify the template.

An example of a sprayable emulsion that may be suitable for the procedures disclosed herein is a UV activated acrylate monomer in which it has elastomeric qualities after curing. The sprayable emulsion is a special embossed "varnish" polymer that rapidly cures into a highly durable/resistant layer that builds up rapidly on the substrate. The cured polymer is also durable and flexible/elastic (if it is rigid, it tends to break in use and render the template useless). VersaUV (Roland DG) technology is one example of a material that can be used to practice the teachings herein.

Release fluid 122 is configured to provide a smooth, non-reactive printing surface below mesh 112. It is also used to limit the dot expansion of the printed emulsion. Dot expansion occurs when a jetted droplet (or dot) expands or spreads out prior to UV exposure. This is especially important when halftones are used, ie the entire space in the mesh is filled with emulsion. However, it is only necessary to suppress the dot spread for a short period since UV curing occurs very quickly after spraying the emulsion.

Release fluid 122 is a fluid that manages point expansion and does not react with the solidified emulsion so that it does not lift or separate the emulsion from mesh 112 . By changing specific properties, including but not limited to changing surface tension, ionic mixture, polar or non-polar components, or whether the fluid is aqueous or non-aqueous, the process used to release fluid 122 can be modified or tailored for sprayable emulsions. fluid.

Release fluid 122 may be water-based (eg, distilled water), water alone or with at least one emulsifier sufficient to prevent evaporation of the release fluid. Examples of emulsifiers, along with a class of emulsifiers known as surfactants, include, but are not limited to, polysorbates, glycerol, and glycols, such as butyl selezo. In some embodiments, the emulsifier(s) may be present in an amount of at least 3 vol% to 5 vol% to prevent evaporation of the release fluid 122. Further examples of release fluid 122 include water-based varnishes such as butyl acetate, xylenes, mixed xylenes, phthalates, and combinations thereof.

After the mesh is placed on the platen 124 , the release fluid 122 is deposited directly onto the platen 124 or onto the mesh 112 . In most preparations in the current state of the art, emulsions can be quite coarse Roughness; this is usually caused by the emulsion conforming to the mesh during the drying procedure. This rough emulsion surface may wear at the blade, requiring resurfacing or replacement of the blade. However, in a direct mesh procedure, the release fluid 122 ensures a very smooth surface as the sprayable emulsion accumulates in the mesh; see, eg, FIG. 3B and its associated discussion.

Since the only emulsion applied to mesh 112 is in a shadowed area, there is no overshoot or overexposure of UV light reflected into the shadowed area. This provides a smoother, clearer image. (These overshoot and overexposed areas can create spots or depressions inside the image, especially around the edges. These are "inversions" of pinholes.)

The platen 124 provides a smooth, hard, impermeable surface for the release fluid 122, and gently pushes the tension mesh 112 to ensure a well-even, flat surface for the emulsion to be applied. In some embodiments, the platen 124 does not absorb or chemically or physically interact with the release fluid 122 and is planar (±0.05 mm/meter). "Smooth" means that the surface of the platen 124 can be a regular surface of polished/gloss or frosted/matte, as long as the surface is regular.

Example steps of a direct mesh procedure are depicted in Figures 2A-2E, which are cross-sectional views of a DtM device.

In FIG. 2A , the frame 114 surrounds the platen 124 . The jig 116 for supporting the frame 114 is omitted in this figure and FIGS. 2B to 2E . Frame clamps 116 are similar to frame clamps currently used in the art. One or more elements or sprayers 126 spray a layer of release fluid 122 on a top surface 124a of the platen 124 . The sprinkler(s) 126 may be fixed in place or configured to straddle the platen 124 . It will be appreciated that the release fluid can be applied in several different ways: eg wiping, brushing and the like, and spraying.

In FIG. 2B , mesh 112 is placed across the top of frame 114 . Below the mesh 112 is tied a pressure plate 124, the pressure plate 124 having a release fluid 122 supported on a surface 124a of the pressure plate A thin, uniform coating. In some embodiments, the thickness of the release fluid 122 is about 20 micrometers (μm), but in any case less than the size of a mesh, and within ±0.5 μm flatness. Release fluid 122 supports mesh 112 as it is applied to provide good coverage of the sprayable emulsion. The release fluid 122 is formulated to avoid sticking of the sprayable emulsion to the platen 124 . The formulation of release fluid 122 prevents the emulsion from sticking, reacting, or otherwise adhering to the platen. In some cases, the emulsion may react with the release fluid 122 , but that interaction/reaction generally may not allow any adhesion to the platen 124 . If the adhesion to the platen 124 is greater than the adhesion to the mesh 112, the emulsion may debond/delaminate from the mesh. This can lead to pinholes or bare patches. In the worst case, it may cause the mesh to be damaged or torn.

In Figure 2C, the platen 124 with the release fluid 122 is moved up to the mesh 112, tightening the mesh and pressing the release fluid against the back of the mesh. This provides a smooth, tensioned, level surface for printing. Movement of the platen 124 is indicated by arrow 202 .

In FIG. 2D, the print head 132, which can be translated by the printer carriage 134 (not shown in FIG. 2D, but shown in FIG. 1), prints the masking image or stencil 206 (seen in FIG. 2E) directly onto the mesh 112, wherein A masked image is an inverse or negative image of the actual image to be printed or screen printed onto a suitable print medium. The print head 132 is moved laterally in the direction indicated by arrow 204 to form a screen template 206 on the mesh 112 . An "ink" is a UV-curable sprayable emulsion that is substantially UV-cured upon application by the UV source 208 as described above. In one example, the UV source is moved laterally in the direction indicated by arrow 210 . This is similar to what happens in a conventional UV printer. FIG. 2D depicts print head 132 and UV source 208 moving across mesh 112 . However, the mesh support system including mesh 112 and frame 114 (and clamp 116 ) can translate relative to print head 132 and UV source 208 . UV sources 208 may be fitted to both sides of print head 132 to facilitate bidirectional printing of mesh 112 .

In Figure 2E, the resulting template 206 is shown. The stencil 206 can be removed from the printing press and used immediately without any further preparation or processing.

In some embodiments, a layer 128 may be placed on the surface 124a of the platen 124 prior to dispensing the release fluid 122 on the surface 124a of the platen 124 . Layer 128 is referred to herein as a "background type." The platen 124 is held at a constant height and a "background" 128 is then placed on the platen 124 . Examples of background types 128 include a 4mm mirror, 2mm clear glass, 2X glass (top), white polyethylene, glass (top)/mirror (bottom), 4mm glass (top), and 3mm mirror. Thus, if for example a 4mm mirror is used, the printed surface is 2mm higher than the 2mm clear glass. Sometimes, different results are obtained using a "two-component" background. For example, "2X glass" consists of two clear glass sheets, "glass (top)/mirror (bottom) is a 2mm glass sheet on a 2mm/4mm mirror. Without following any particular theory, it is believed that the use of The two plates introduce some light reflection/refraction where the two surfaces meet in the middle. "White Poly" is a sheet of white polyethylene.

A comparison of the results according to an example is shown in FIGS. 3A-3B. Both figures show an emulsion applied to mesh 112.

In Figure 3A, in a combination 300 of a conventional spreadable emulsion 302 and mesh 112, the emulsion is seen conformally following the warp and weft lines (bundles 112a and 112b) of the mesh, including both the top and bottom of the mesh . This shape retention occurs when the spreadable emulsion 302 is air-dried onto the mesh 112. In particular, FIG. 3A shows how a conventionally applied emulsion 302 shrinks as it dries onto the mesh 112 after being applied by hand or with a coater. This shrinkage is inevitable as the water component dries. Emulsion 302 is a commonly used emulsion in the art.

In FIG. 3B, in combination 350 of sprayable emulsion 302' and mesh 112 of the present teachings, the sprayable emulsion is seen to have a smooth surface 124a from platen 124 (and its release thereon) Fluid 122) provides a flat bottom surface 302'a. The top surface 302'b of the sprayable emulsion 302' is seen to be less conformal to the warp and weft of the mesh 112 than the current emulsion 302. (The bottom surface 302'a is where the screen ink will be applied and pressed through using a squeegee during the actual screen printing process.) With respect to DtM, because the mesh 112 has the release fluid 122 supported by the smooth platen 124, the emulsion 302 'The lower side 302'a is more flat or flat. This is also a result of substantially immediate curing by UV radiation.

This procedure is called direct mesh (DtM) to distinguish it from CtS (Computer-to-Plate), which requires additional processing before (ie, applying the emulsion) and after (washing out the unexposed emulsion and ink). In the DtM procedure, no additional processing before and after applying the sprayable emulsion 302' is not required, thus simplifying template 206 creation.

4 depicts a flow diagram of an exemplary DtM procedure 400 for preparing a template for screen printing in accordance with the disclosure herein. In the DtM program 400, the direct-mesh printer 100 is provided 405. As described above, the DtM printer 100 includes a clamp 116 for holding a frame 114 that is configured to hold the pre-stretched mesh 112 in place during application of the sprayable emulsion 302'. The platen 124 of the DtM printer 100 is used to hold the release fluid 122 against one side of the pre-stretch mesh 112 . Finally, the DtM printer 100 includes a printer carriage 134 that supports the print head 132 to print the jettable emulsion 302 ′ on the opposite side of the pre-stretch mesh 112 from the platen 124 .

The DtM procedure 400 continues with placing 410 the frame 114 in the fixture 116 . The fixture 116 is part of the DtM printer 100 and is adapted to receive various frame 114 sizes. The clamps 116 are configured to precisely hold the frame 114 in place so that the press carriage 134 is accurately registered to the mesh 112 .

DtM procedure 400 continues to apply release fluid 122 directly or through mesh 112 415 to platen 124. When applied directly to mesh 112 , applying release fluid 122 can be as effective as when pre-applied to platen 124 . This can be important for very large templates or very high point densities (such as 5,000 DPI) where the release fluid 122 may have time to evaporate even with a good emulsifier.

Regardless, the platen 124 coated with the release fluid 122 is brought into contact with the mesh 112 (or the platen 124 is brought into contact with the mesh 112 and the release fluid 122 is applied to the mesh). In some embodiments, the platen 124 may be raised to about 1 millimeter (mm) to about 2 mm above the height of the mesh to provide a degree of tension to the mesh 112 .

The DtM procedure 400 continues to apply 420 the sprayable emulsion 302 ′ to the mesh 112 . As described above, the sprayable emulsion 302' is applied relative to the mesh 112 by the inkjet printer 130, where the inkjet print head 132 is used to spray the sprayable emulsion.

The DtM procedure 400 ends with curing 425 the sprayable emulsion 302' using UV radiation. Any common UV source can be used to cure the sprayable emulsion 302'.

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

example

Execute four series of instances. In the Examples and Tables, the following definitions are now provided.

"Mesh resolution" refers to the number of lines per centimeter (cm). The mesh resolution may include a letter to indicate the diameter of the wire, such as S (small diameter), T (medium diameter), or HD (large diameter). For example, "43T" is a mesh with 43 medium diameter threads per centimeter.

"Frame Type" indicates the type of frame 114 used and can be a roller Frame, aluminium or large roll frame. The "aluminum" frame is a fixed square metal aluminum frame in which the mesh is glued with a specific tension before starting. A typical value for tension is about 26 Newtons (N). A "roll frame" is one of the re-tensionable frames that allows the tension of the mesh to be changed after the template has been stretched. A roll frame is far more expensive than a standard square frame, but it is easier to keep the tension correct and re-stretch. The large roll frame is slightly larger than the roll frame.

The metal mesh is a stainless steel, nickel-plated mesh. This type of mesh is often used for rotating screens or for screens from the same stencil that have been exposed to corrosive fluids or used for extended periods of time (many prints/presses).

"Unit resolution" is the dot density interleaving (DPI) ejected from the print head.

"Number of pulses" refers to the number of firing pulses sent to an individual nozzle.

The print head used has 8 nozzle rows. The heading "ink channels" refers to the number of columns used to eject fluid. "All" means all 8 columns. The notation "11100111" indicates that the middle two columns are not fired; this imparts the effect of a "gap" between the jets.

"UV%" refers to the intensity of UV radiation emitted by the adjustable UV LED source 208. The intensity of the UV LED source 208 is modulated with a PMW (pulse width modulator) to control the intensity of the UV light produced. The UV source 208 used has a maximum value of 100 W/cm ² . For example, a notation of 60% means that 60% of the UV light is modulated to 60% of full intensity.

"Release fluid" refers to the composition of release fluid 122 applied to platen 124 .

"Background type" refers to what is used on the surface of the platen 124 . Platen 124 is held at a constant height and a "background" is then placed on top of the platen. Examples of background types include a 4mm mirror, 2mm clear glass, 2X glass (two 2mm clear glass sheet), "glass (top)/mirror (bottom)" (2mm clear glass on a 2mm/4mm mirror) and "white polyethylene" (white polyethylene sheet).

"TEM" refers to the total emulsion measure and is a measure of emulsion thickness. Typically, a number of EoM (Emulsion on Mesh) is used, but this is the ratio of the thickness of the emulsion divided by the thickness of the mesh. Here, the number in μm refers to the total thickness, including the thickness of the emulsion plus the thickness of the mesh.

"Smoothness" refers to the smoothness of the template. On the platen side, the surface touch is extremely smooth with no discernible roughness. On the printed side, the surface should feel smooth to the touch. A slight roughness (similar to that experienced with frosted glass) is considered "acceptable". In test results considered "unacceptable", the surface usually looks like sandpaper.

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

"Result" means a subjective assessment of the overall result of an experiment. The same subjective rating scale described for smoothness is also used here.

"A4 printing time" refers to the time it takes to print a screen with the size of A4 media (21.0 cm x 29.7 cm).

Example series 1

In Example Series 1, 6 experiments were performed; details are provided in Tables IA (test parameters) and IB (results). All experiments used UV Super Flex 100 ink as the jettable emulsion, which is an experimental ink. The mesh color in each case is white. Frame types are variously a roll frame, aluminum or a large roll frame, as listed in Table IA. The unit resolution in each case is 1440 DPI. The printing speed in each case was 300 cm/sec. The number of pulses is as described in Table IA. In the first 4 experiments, all 8 ink channels were fired, while in the last 2 experiments, the printed The two nozzle rows in the middle of the brush head are not fired, leaving a gap. UV in each case was 60% of full intensity. The release fluid in all 6 experiments was 100% distilled water. The background type in the first 3 experiments was a 4mm mirror, and in the last 3 experiments it was a 2mm clear glass.

As seen in Table IB, the TEM ranged from 10 μm to 22 μm (Experiments 1, 4, 5, 6); TEMs for Experiments 2 and 3 were not obtained due to the lack of a sealing mesh. For Experiment 1, although the smoothness and results were acceptable, the mesh adhered to the mirror and the resulting TEM at 22 μm was considered too high. Experiments 4, 5 and 6 resulted in acceptable smoothness and results and a sealed mesh.

It seems that 2mm clear glass gives better results than 4mm mirror and 2 further pulses give better results than 1 pulse. It should also be noted that the frame used in experiments 2 and 3 was aluminum.

Example series 2

In Example Series 2, 12 experiments were performed; details are provided in Tables IIA (Test Parameters) and IIB (Results). All experiments use UV Super Flex 100 ink as jettable lotion. The mesh color in each case is yellow. The frame type in each case is aluminium. The unit resolution in each case is 1080DPI. The printing speed was 375 cm/sec. The number of pulses is as described in Table II. In all experiments, all 8 ink channels were fired. For all experiments, UV was 60% of full intensity, except for experiment 11, where UV was 40% of full intensity. Release fluid 122 is as described in Table IIA. Background types are as described in Table IIA.

As seen in Table IIB, the TEM ranged from 7 μm to 20 μm; no TEM was obtained for Experiment 5. For experiments 1 to 4, 6 and 12, the smoothness and results were acceptable. For experiments 7 and 8, the smoothness and results are somewhat acceptable. For experiments 5, 9, 10, and 11, the smoothness and results were unacceptable; as indicated in Table II, these experiments resulted in mesh sticking to the printing surface on the platen.

The only difference between experiments 4 and 5 was the background type used 2x on glass vs polyethylene. It seems that the former produces better results than the latter.

The only difference between experiments 4 and 7 to 8 was the background type used 2x top glass versus 4mm top glass. It seems that the former produces better results than the latter.

Regarding experiments 9, 10 and 11, these are the only experiments using a liquid comprising 95% distilled water and 5% ANODAL ASL (Gedacolor). Other liquids (eg, 100% distilled water, 80% distilled water + 20% Dead Sea salt, 80% distilled water + 20% ethanol, and 50% distilled water + 25% window cleaner + 25% isopropyl alcohol) all gave acceptable or slightly acceptable Accepted smoothness and results.

Example series 3

In Example Series 3, 5 experiments were performed; details are provided in Tables IIIA (test parameters) and IIIB (results). All experiments used UV Super Flex 100 UV ink as the jettable emulsion. The mesh color in each case is yellow. The frame type in each case is aluminium. The unit resolution in each case is 1080DPI or 1440DPI. The printing speed was 300 cm/sec or 375 cm/sec as described in Table IIIA. The number of pulses is as described in Table IIIA. In all experiments, the middle two nozzle rows of the print head were not fired, leaving a gap ("11100111"). UV is 60% of full intensity. The release fluid 122 in all 6 experiments was 100% distilled water. The background type in all experiments was a 4mm mirror.

As seen in Table IIIB, the TEM ranged from 3 μm to 45 μm. For all experiments, the smoothness was acceptable, while for experiments 3, 4, and 5, the results were acceptable. For experiments 1 and 2, the results were slightly unacceptable due to the slight sticking of the mesh.

In experiments 1 and 2, the number of pulses was the same for both (2), while for experiments 3, 4 and 5 the number of pulses was different (1). It appears that this difference caused Experiments 1 and 2 to have slightly unacceptable results.

Example series 4

In Example Series 4, 4 experiments were performed; details are provided in IVA (test parameters) and IVB (results) below. The mesh resolution in all cases is 195 (US standard). All experiments used UV Super Flex 100 UV ink as the jettable emulsion. The mesh colour in each case is grey/metallic. Frame type is metal. The unit resolution in each case is 1440 DPI. The printing speed was 300 cm/sec. The number of pulses was 1 for all experiments. In all experiments, the middle two nozzle rows of the print head were not fired, leaving a gap ("11100111"). In experiments 1 to 3, UV was 60%, 40%, and 30% of full intensity, respectively, while in experiment 4, UV was 30% of full intensity. The release fluid in experiments 1 to 3 was distilled water; in experiment 2, the release fluid was not used. The background type in both experiments was a 3mm mirror.

As seen in Table IVB, the TEM was 14 μm in all experiments. For experiments 1 to 3, both the smoothness and the results were unacceptable, while for experiment 4, the smoothness and results were acceptable.

In experiments 2 and 3 of Example 1 above, the frame was aluminum, and both experiments had unacceptable smoothness and results with 100% distilled water as the liquid. In Experiment 1 of Example 4, the frame was metal and similar unacceptable results were obtained. On the other hand, in Experiment 2 of Example 4, although the frame was also metal, no liquid was used, and acceptable smoothness and results were observed. Clearly, the combination of liquid and frame is a factor in obtaining acceptable smoothness and results one. Under certain conditions, having no release fluid or backing paper has been found to yield better results. Based on the foregoing tests, an emulsion can be formulated that will function without any backing surface.

Based on the foregoing examples, it appears that the results may be influenced or impacted by: some very complex interactions of fluids (both emulsions and any released fluids); platen compositions (eg, single glazing, double glazing, glass Add mirror, etc.); curing intensity (20% to 100% UV); dot density (1080, 1440); number of pulses, etc. From an analytical point of view, it seems that the combinations are almost infinite. Currently, the only method for evaluating a parameter set is pragmatic; that is, each set must be tested based on the teachings herein. However, this test is not considered excessive.

Advantages of the DtM program 400 include the complete elimination of template preparation and post-processing as follows: No need for machines such as emulsion applicators, dryers, separate exposure units.

Eliminates most chemicals (except degreaser) and more than 80% water consumption.

All processing can be done without special low UV light chambers. In practice, DtM procedures can be performed under normal factory/office lighting or daylight. Upon disposal, the sprayable emulsion remains in a UV-resistant box or bag. The sprayable emulsion is only exposed to sunlight or UV light as it is sprayed onto the mesh 112 .

Because the procedures disclosed herein can use conventional, less expensive meshes 112, it is generally more efficient and cheaper to strip and re-mesh the frame 114 rather than wash the meshes (which requires water and chemicals and a special cleaning station).

Raw, untreated screen or mesh 112 is placed on DtM press 100 A fully prepared, ready-to-use stencil 206 is placed on and removed from the screen, which can be placed directly onto a turntable to print an image onto a printing surface.

A further advantage of the DtM procedure 400 is that each template 206 is registered very accurately on the mesh 112, so that micro-registration can be skipped when mounted on a turntable. With the DtM program 400, since each template 206 is positioned exactly on the frame 106 (both absolute and relative), no adjustment or adjustment is required. This is accomplished through the use of frame clamps 116 . The template frame typically has registration holes or points secured to it. Each different turntable manufacturer has its own registration system. Frame fixture 116 is equipped with the same registration system (or possibly an auxiliary registration system of another design). Frame clamps 116 allow precise alignment of template frame 114 . To accomplish this, a test print is made with 4 (or 6 or more) colors, followed by fine-tuning the dial. As long as no changes have been made to the carousel (or the carousel is not misaligned) and all the stencils are built on the same press, the stencils will be precisely aligned.

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

DtM program 400 can also be used for rotary screen printing. Rotary screen printing is used for marking and other narrow but often repetitive printing processes (wallpaper, linear linoleum, etc.). Rotary screen printing is extremely fast for these applications, where each of the four colors (and any spot colors) is placed on a cylinder and the material is passed underneath. Rotary screen printing typically uses stainless steel mesh 112 for durability and stability.

Today, many rotating forms are manufactured by large maintenance facilities (about three in Europe). The cost of each formwork can exceed 100 euros and the annual cost of formwork replacement can reach hundreds of thousands of euros. This does not even take into account the inconvenience of using a maintenance agency. Companies will be able to recoup the cost of their machines within a few quarters while reducing their reliance on expensive repair facilities.

It should be understood that in the foregoing description, numerous specific details are set forth in order to provide a thorough understanding of one example. It should be understood, however, that examples may be practiced without limitation to these specific details. In other instances, well-known methods and structures may not be described in detail to avoid unnecessarily obscuring the description of the examples. Furthermore, examples can be used in combination with each other.

It should be noted that, as used in this specification and the accompanying claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It should be understood that in the foregoing description, numerous specific details are set forth in order to provide a thorough understanding of one example. It should be understood, however, that examples may be practiced without limitation to these specific details. In other instances, well-known methods and structures may not be described in detail to avoid unnecessarily obscuring the description of the examples. Furthermore, examples can be used in combination with each other. Furthermore, when "about" is used to describe a value, this is meant to cover small variations (up to ±10%) from the stated value, such as may result from manufacturing variations.

Furthermore, the order of the procedural steps within the scope of the invention claims may be interchanged as appropriate. For example, dispensing release fluid 122 onto platen 124 or mesh 112 may involve dispensing the release fluid onto the platen and then bringing the platen and mesh together. Alternatively, the platen and mesh can be brought together and the release fluid dispensed onto the mesh.

While a limited number of examples have been disclosed, it should be understood that there are numerous modifications and variations thereof. For example, the "orientation" of a printing machine/table can be changed from horizontal to vertical due to new high/ultra-high speed print head technology that allows jetting onto a vertical surface.

100: Direct Mesh (DtM) Press

110: Mesh support system

112: Pre-stretched mesh

114: Frame

116: Fixtures

120: Platen support system

122: release fluid

124: Platen

126: Fluid Dispenser/Sprinkler

130: Inkjet Printers

132: Printing head

134: Press carriage

Claims (11)

A direct mesh printer for creating a mesh template comprising: a frame for applying a pre-stretched mesh during application of a jettable emulsion ) in place; a fixture to hold the frame; a platen to hold a release fluid against one side of the pre-stretched mesh; a fluid dispenser , which is used to dispense the release fluid onto the platen or mesh; and a printer carriage supporting a print head to print the sprayable emulsion on the opposite side of the pre-stretched mesh from the platen ; wherein the release fluid is configured to inhibit dot-gain while providing a smooth, non-reactive surface for the sprayable emulsion after curing; wherein the platen is configured to abut the pre-stretched mesh a bottom firmly holds the release fluid, wherein the platen is smooth, rigid, and impervious to the release fluid and resistant to dents and cracks, further comprising a UV source for The jettable emulsion is cured and a stencil is formed for screen printing, wherein the UV source is moved across the mesh and is configured to be fitted to both sides of the print head to facilitate bidirectional printing of the mesh. The direct screen printer of claim 1, wherein the clamp is configured to securely and securely hold the frame and the pre-stretched mesh in place during the application of the sprayable emulsion. The direct screen printing machine of claim 1, wherein the release fluid is applied to the platen in a very fine, uniform coating or directly to the mesh when the release fluid is placed on the platen to prevent Adheres to the platen during the application of the sprayable emulsion. The direct screen printer of claim 1 wherein the release fluid comprises water and at least one emulsifier sufficient to prevent evaporation of the release fluid. The direct screen printer of claim 1, wherein the sprayable emulsion has a low viscosity of about 4 cP to about 15 cP and is both durable and flexible/elastic. The direct screen printer of claim 5, wherein the sprayable emulsion is a UV activated acrylate monomer having elastomeric qualities after curing. A method of creating a screen stencil, comprising: providing a direct screen printer comprising: a clamp for holding a frame configured to hold a pre-screen during application of a sprayable emulsion The stretch mesh is held in place; a platen to hold a release fluid against one side of the pre-stretch mesh; and a printer carriage that supports a print head to be in contact with the pre-stretch mesh The jettable emulsion is printed on the opposite side of the platen, wherein the release fluid is configured to inhibit dot spread while providing a smooth, non-reactive surface for the sprayable emulsion after curing, wherein the platen is configured to holding the release fluid firmly against a bottom of the pre-stretch mesh, wherein the platen is smooth, rigid, and impervious to the release fluid and resistant to dents and cracks, further comprising a A UV source for curing the jettable emulsion and forming a stencil for screen printing, wherein the UV source moves across the mesh and is configured to be fitted to both sides of the print head to facilitate the mesh placing the frame in the fixture; dispensing the release fluid onto the platen or mesh; bringing the platen and mesh together in a tensioned configuration; printing the jettable on the mesh emulsion; and curing the sprayable emulsion using UV radiation. 7. The method of claim 7, wherein the sprayable emulsion forms a screen template after curing, wherein the openings in the screen template are to be used to form an image on a surface. The method of claim 7, wherein the release fluid is configured not to adhere to the sprayable emulsion after it cures. 7. The method of claim 7, wherein the release fluid comprises water and at least one emulsifier sufficient to prevent evaporation of the release fluid. The method of claim 7, wherein the sprayable emulsion is a UV activated acrylate monomer having elastomeric qualities after curing.

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