JP2021531998A - Creating a direct-to-mesh screen - Google Patents

Abstract

A method for creating a screen stencil using a direct-to-mesh (DtM) screen printer is provided. The direct-to-mesh printer (DtM screen printer) is on one side of a frame that holds the pre-stretched mesh in place, a fixture that holds the frame, and the pre-stretched mesh. A printer that supports a platen that holds the stripping liquid, a liquid dispenser that applies the stripping liquid to the platen or mesh, and a printhead for printing a printable emulsion on the opposite side of the pre-stretched mesh platen. Including the carriage.

Description

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

Screen printing is a printing technique that uses a mesh to transfer ink onto a substrate, excluding areas that are opaque to the ink by a screen printing stencil, also known as a blocking stencil. The blade or squeegee is moved across the screen to fill the open mesh openings with ink, and then a reverse stroke causes the screen to momentarily contact the substrate along the contact line. This causes the ink to wet the substrate and pull it away from the mesh opening as the screen bounces after the blade has passed.

Creating screen printing stencils is a tedious and labor-intensive task. It requires many process steps, chemicals, large amounts of water and is mostly done manually. This is the least automated part of the current screen printing business.

The embodiments of the present disclosure will be apparent by reference to the following detailed description and drawings. In the drawings, similar reference numbers correspond to similar but not identical components. For brevity, reference numbers or reference features with the functions mentioned above may or may not be described in relation to the other drawings in which they appear.

FIG. 1 shows a direct-to-mesh printer according to an example of the present disclosure.

FIG. 2A is a cross-sectional view showing the elements of a process in screen printing using a direct-to-mesh screen printer according to an example of the present disclosure. FIG. 2B is a cross-sectional view showing the elements of a process in screen printing using a direct-to-mesh screen printer according to an example of the present disclosure. FIG. 2C is a cross-sectional view showing the elements of a process in screen printing using a direct-to-mesh screen printer according to an example of the present disclosure. FIG. 2D is a cross-sectional view showing the elements of a process in screen printing using a direct-to-mesh screen printer according to an example of the present disclosure. FIG. 2E is a cross-sectional view showing the elements of a process in screen printing using a direct-to-mesh screen printer according to an example of the present disclosure.

FIG. 3A schematically shows an emulsion on a mesh that provides a comparison between current technology (FIG. 3A) and disclosure (FIG. 3B) herein according to an example of the present disclosure. FIG. 3B schematically shows an emulsion on a mesh that provides a comparison between current technology (FIG. 3A) and disclosure (FIG. 3B) herein according to an example of the present disclosure.

FIG. 4 is a flowchart showing a screen printing method according to an example of the present disclosure.

There are some examples of previous solutions for directly coating meshes to form stencils for screen printing. These will be described.

・ Mesh preparation and coating:
Direct application of emulsion: Direct application of emulsion is done either mechanically or manually. Both sides of the screen should be coated with emulsion to ensure proper coating. Machines, or automated versions, are, strictly speaking, machines that replace humans. This machine applies a much more accurate and accurate amount of emulsion to obtain a uniform coverage. This machine is generally less wasteful.

Capillary film: Capillary film is a film pre-coated with an emulsion. The mesh is supersaturated with water and the film (emulsion side down) is placed against the supersaturated mesh. The emulsion is drawn into the mesh by capillary action. This provides a more accurate coating of the emulsion in both thickness and cover. As the emulsion diffuses into the mesh, the film is peeled off.

Once the emulsion has penetrated the screen mesh, the screen mesh must be dried. Once the screen mesh has dried, image transfer or stencil creation is possible. When the emulsion dries, it shrinks and forms a mesh-like shape, resulting in a rough, uneven surface. (This rough surface accelerates the aging of the squeegee in the printing process.)

Most emulsions today are activated by ultraviolet (UV) radiation (ie, UV activation), but may be activated by visible light. Once coated, the stencil must be protected from exposure to any light (even normal visible light has enough UV to initiate the curing process). Hereinafter, the emulsion is considered to be UV activated / cured.

Image transfer / stencil creation:
In screen printing, there is one stencil for each spot color in addition to each color, typically cyan, magenta, yellow, and black (CMYK) (spot colors are usually discrete colors that are not easily achieved with CYMK colors). Is based on). Areas of the stencil that you do not want the ink to pass through are blocked by the emulsion that is subsequently cured to form the stencil, and all other areas have only the mesh. Any opening in the mesh may be completely or partially blocked by the emulsion to form the stencil.

Film Positive Ink: A completely black UV absorbent layer is printed on a transparent plastic sheet. Printing is usually performed by a laser or inkjet printer using a special film positive ink, which means a high opacity black ink that completely blocks all visible and UV light. Next, the film is attached to the precoat mesh and exposed to UV light. Installation is usually done with removable tape (such as masking tape). After exposure, the film is removed and the uncured emulsion is washed away.

However, this approach is very labor-intensive at all stages and it is not possible to automate many steps. In addition, errors are likely to occur while attaching the film to adjust the final stencil before printing using the correct film. A large amount of chemicals and cleaning agents are required in addition to a large amount of consumables (ink and film).

Thermal screen:
In this method, the mesh is precoated with a heat activated emulsion. Typically, the mesh (without frame) is placed in a thermal printer where the emulsion is cured / activated directly. When complete, wash off the unexposed emulsion, place the stencil on the frame and print.

However, this approach limits the mesh count. Also, the emulsion is not very strong. Pretreated meshes are expensive. Stencil alignment needs to be done more thoroughly. Finally, the stencil can be damaged while being attached.

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

However, these machines require high opacity inks, which are more expensive than ordinary inkjet inks.

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

However, due to the use of molten wax, these machines can be difficult to handle. In addition, it is required to heat the wax to apply it to the mesh.

CtS direct exposure:
This technique uses a UV laser to directly expose the emulsion.

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

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

All screens must be washed away with excess emulsion. Care must be taken to prevent the emulsion from entering the drainage system. After cleaning, the screen must be dried.

For films and thermal activation methods, the finished stencil must be fine-tuned when placed on the carousel to ensure proper alignment.

It is clear from the above description of current technology that a simpler approach using less chemicals and less water is desirable.

As disclosed and claimed herein, according to the disclosure of the present specification, a DtM (Direct to Mesh) approach for forming a stencil uses inkjet technology to screen an emulsion. Includes direct application to and activation / exposure. In particular, according to the disclosure herein, DtM screen printers include:
A frame for holding the pre-stretched mesh in place while applying a sprayable emulsion,
・ Fixtures for holding the frame,
Platen to hold the stripper against one side of the pre-stretched mesh,
A stripper dispenser that supplies the stripper onto the platen or mesh.
A printer carriage that supports a printhead for printing a jettable emulsion on the opposite side of the pre-stretched mesh platen.

FIG. 1 shows a block diagram of a 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. The frame 114 is held by the fixture 116. The fixture 116 firmly holds the frame 114 with the pre-stretched mesh 112 in place during the application of the jettable emulsion.

As used herein, the mesh 112 is made from connected strands of woven, fiber, metal, or other flexible / ductile material, here woven in a cross pattern. The material that makes up the mesh is a variety of textiles (silk, polyester), metals such as stainless steel, polypropylene, polyethylene, nylon, plastics such as polyvinyl chloride (PVC) or polytetrafluoroethylene (PTFE), or It may be any of glass fibers. The diameter of the strands may be any diameter that is common in screen printing, and the mesh size may be any size that is common in screen printing. Coarse meshes are usually woven with strands of larger diameter (gauge), but this mesh needs to be coated with a thicker emulsion.

The DtM printer 100 further includes a platen support system 120 that includes a stripper 122 held on one side of the mesh 112 pre-stretched by the platen 124. The platen 124 holds the stripper 122 firmly against the bottom of the pre-stretched mesh 112. Platen 124 is configured to be as smooth as possible, impervious to liquids, and resistant to dents and cracks. Platen 124 also functions to disperse energy from UV light source 208 (shown in FIG. 2D, not FIG. 1).

The stripping liquid 122 may be applied directly to the platen 124 or to the mesh 112 positioned on the platen before the jetable emulsion is applied. For example, the liquid dispenser 126 that introduces or coats the stripping liquid 122 onto the platen 124 may have one or more sprays 126. The spray 126 may have a conventional sprayer or spray type element.

The stripping liquid 122 does not react with the cured emulsion, thereby suppressing the dot gain, which is the effect of the printing fluid spreading in the printing medium. Dot gain needs to be suppressed for a short period of time as the cure occurs very quickly after the emulsion is sprayed.

Finally, the DtM printer 100 includes an inkjet printer 130 including a printhead 132 mounted on a printer carriage 134. The printhead 132 is configured to print a jettable emulsion on the opposite side of the pre-stretched mesh 112 to the platen 124. The printer carriage 134 is an accurate precision printer carriage in both the X and Y directions in the Cartesian coordinate system, supporting accurate droplet placement over one or more paths while depositing a jettable emulsion. .. In fact, emulsions can be "built up" to fit a wide range of mesh gauges, from very fine to very coarse. Lamination can be used to maintain high resolution when depositing emulsions.

The printhead 132 includes an inkjet printhead such as a thermal inkjet, a piezoelectric inkjet, a drop-on-demand inkjet, or any other suitable jet printhead capable of jetting a fluid, including the jettable emulsions disclosed herein. May be.

The screen mesh 112 may be of any type, expensive or inexpensive, or any gauge, but may be stretched onto the frame 114. The frame 114 is placed in the inkjet printer 130 together with the stripper 122 placed on the platen 124. The jettable emulsion is then applied to the masking area by an inkjet printer 130 and exposed substantially simultaneously with a high intensity UV lamp or other suitable UV source such as a UV light emitting diode (LED). UV lamps (or LEDs) can be adapted to the reaction range of the emulsion that can be ejected to achieve optimum performance. In the case of jettable emulsions disclosed herein, the emulsion reacts at a wavelength of 395 nanometers (nm). Other injectable emulsions may have other reaction wavelengths, including less than 395 nm. For coarse meshes, the application may be a multipath operation to laminate the emulsion to the required thickness. By "coarse mesh" is meant a mesh that has a coarse weave and therefore has a larger gap between strands than a fine mesh screen. For example, a 335 mesh count is considered to be a fine mesh, while a 110 mesh count is considered to be a coarse mesh. Here, the mesh count is the number of thread intersections per square inch.

The direct-to-mesh method disclosed herein has been made possible by the recent development of low viscosity injectable emulsions. "Low viscosity" means the range from about 4 centipores (cP) to about 15 cP (about 4 millipascals seconds to 15 millipascals seconds). These new injectable emulsions are used in UV printers to create embossing effects on a wide variety of materials. These new injectable emulsions are also more elastic and can therefore be more easily used as a replacement for previous emulsions. Any color, including clear or clear, can be used in the injectable emulsion, but light cyan or light magenta can be used to provide a slight contrast to verify the stencil. Any color, including clear or clear, can be used in the injectable emulsion, but light cyan or light magenta can be used to provide a slight contrast for verifying the stencil.

An example of a propellable emulsion that can be successfully used in the processes disclosed herein is a UV activated acrylate monomer that has elastomer properties after curing. The injectable emulsion is a special embossed "varnish" polymer that rapidly deposits on a substrate and cures to form both a durable layer and a highly resistant layer. The cured polymer is also durable and flexible / elastic (if the polymer is hard, it easily cracks during use, making the stencil useless). VersaUV (Roland DG) technology is an example of materials that may be useful in the practice of the disclosure herein.

The stripper 122 is configured to provide a smooth, non-reactive printed surface beneath the mesh 112. It also serves to limit the dot gain of the printed emulsion. Dot gain occurs when the ejected droplets (ie, dots) expand or spread prior to UV exposure. This is especially important when adopting halftones, i.e., when the entire space within the mesh is not filled with emulsion. However, the dot gain needs to be suppressed for a short period of time as UV curing occurs very quickly after the emulsion is sprayed.

The stripping liquid 122 is a liquid that controls the dot gain and does not react with the emulsion being cured so that the emulsion does not lift or separate from the mesh 112. The fluid for the stripper 122 includes, but is not limited to, changes in surface tension, ionic mixtures, polar or non-polar components, or whether the fluid is aqueous or non-aqueous, by altering certain properties. Can be modified or adjusted for eruptable emulsions.

The stripping liquid 122 may be aqueous (for example, distilled water), water alone, or may contain at least one emulsifier in an amount sufficient to prevent evaporation of the stripping liquid. Examples of emulsifiers include, but are not limited to, emulsifiers known as surfactants containing glycols such as polysorbate, glycerin, and butyl cellulobe. In certain embodiments, the emulsifier may be present in at least 3% to 5% by volume in order to prevent evaporation of the strip 122. Further, as another example of the stripping liquid 122, an aqueous varnish such as butyl acetate, xylene, xylene, dimethylbenzene, and a combination thereof can be mentioned.

The strippery liquid 122 is deposited directly on the platen 124 or on the mesh 112 after the mesh has been placed on the platen 124. In most of the preparations in the current technique, the emulsion can be quite coarse, which is often caused by the conformation of the emulsion to the mesh during the drying process. However, this rough emulsion surface wears with the squeegee and may require remolding or replacement of the squeegee blade. However, in a direct-to-mesh process, the stripper 122 ensures a very smooth surface when the ejectable emulsion is deposited in the mesh. See, for example, Figure 3B and the discussion that accompanies it.

Since the emulsion applied to the mesh 112 is only present in the blocking region, there is no overshoot or overexposure due to the reflection of UV light on the mask region. This provides a much smoother and cleaner image. (These overshoot and overexposure areas can generate spots or droplets inside the image, especially around the edges, which are "inversions" of pinholes.)

The platen 124 is loosely taut with the mesh 112 to provide a smooth, hard, opaque surface for the strippery 122 and to ensure a good, uniform and flat surface on which the emulsion is applied. push. In some embodiments, the platen 124 does not absorb the stripper 122, does not chemically or physically interact with the stripper 122, and is planar (± 0.05 mm / m). By "smooth" is meant that the surface of the platen 124 is a regular surface that can be either polished / glossy or cloudy / matte, as long as the surface is regular.

Illustrative steps of the direct-to-mesh process are shown in FIGS. 2A-2E, which are cross-sectional views of the DtM apparatus.

In FIG. 2A, the frame 114 surrounds the platen 142. The fixture 116 for supporting the frame 114 is omitted in FIGS. 2A and 2B-2E. The frame fixture 116 is similar to that currently used in the art. One or more elements, the spray 126, sprays a layer of stripping liquid 122 onto the top surface 126a of the platen 124. The spray 126 may be fixed in place or configured to cross the platen 124. As a matter of course, the released liquid can be applied by various methods such as wiping and brushing, in addition to spraying, for example.

In FIG. 2B, the mesh 112 is arranged across the top of the frame 114. Below the mesh 112 is a platen 124 with a thin, uniform coating of stripping liquid 122 supported on the surface 124a of the platen. In some embodiments, the stripper 122 has a thickness of about 20 micrometers (μm), but in any case is smaller than the gauge of the mesh and has a flatness within ± 0.5 μm. The strippery 122 backs up the mesh 112 when applied to provide a good coating of the emulsion that can be jetted. The strippery liquid 122 is formulated to avoid adhesion of the jettable emulsion to the platen 124. The formulation of strip 122 prevents the emulsion from binding, reacting, or otherwise sticking to the platen. In some cases, the emulsion may react with the strip 122, but generally does not adhere to the platen 124 due to the interaction / reaction. If the adhesion of the emulsion to the platen 124 is stronger than the adhesion of the emulsion to the mesh 112, the emulsion may detach / detach from the mesh. This can result in pinholes and bare patches. In the worst case, it may cause mesh breakage or crevices.

In FIG. 2C, the platen 124 is moved to the mesh 112 along with the release liquid 122 to strain the mesh and press the release liquid against the back surface of the mesh. This provides a smooth, tensioned, flat printed surface. The movement of platen 124 is indicated by arrow 202.

In FIG. 2D, the printhead 132, which can be moved in parallel by the printer carriage 134 (not shown in FIG. 2D, but shown in FIG. 1), is a block image or stencil 206 (shown in FIG. 2E). Is printed directly on the mesh 112, where the block image is an inversion of the actual image printed or screen printed, in other words a negative. The printhead 132 moves laterally in the direction indicated by arrow 204 to form the screen stencil 206 on the mesh 112. The "ink" is the UV curable jettable emulsion described above, which is essentially UV curable when applied by the UV light source 208. In one example, the UV source travels laterally in the direction indicated by arrow 210. This is similar to what happens with conventional UV printers. FIG. 2D shows a printhead 132 and a UV light source 208 moving across the mesh 112. However, the mesh support system, including the mesh 112 and the frame 114 (and fixture 116), can be translated relative to the printhead 132 and the UV light source 208. UV light sources 208 may be fixed on both sides of the printhead 132 so that the mesh 112 can be printed from both directions.

In FIG. 2E, the stencil 206 is 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 124 prior to applying the stripping liquid 122 onto it. Here, layer 128 is referred to as a "background type". Platen 124 was kept at a constant height and a "background" 128 was placed. Background type 128 includes 4 mm mirror, 2 mm clear glass, 2X glass (top), polyethylene white, glass (top) / mirror (bottom), 4 mm glass (top), and 3 mm mirror. For example, when a 4 mm mirror was used, the printed surface was 2 mm higher than the 2 mm clear glass. Different results were obtained with a "two-part" background. For example, "2X glass" consists of two pieces of clear glass. "Glass (top) / mirror (bottom)" was a 2 mm piece of glass on a 2 mm / 4 mm mirror. It is believed, without specific theory, that the use of two plates results in light reflection / refraction where the two surfaces meet in the middle. "Polyethylene white" was a sheet of white polyethylene.

Comparison of the results by one example is shown in FIGS. 3A-3B. Both figures show the emulsion applied to the mesh 112.

In FIG. 3A, in combination 300 of the conventional spreadable emulsion 302 and mesh 112, the emulsion is conformal to the warp and weft (strands 112a and 112b) of the mesh, including both the top and bottom of the mesh. Follow the target. This conformality occurs when the spreading emulsion 302 is air-dried on the mesh 112. In particular, FIG. 3A shows how the emulsion 302 applied by conventional methods shrinks when dried on the mesh 112 after being applied by hand or by an applicator machine. This shrinkage is unavoidable as the water component dries. Emulsion 302 is commonly used in the art.

In FIG. 3B, in the combination 350 of the injectable emulsion 302'and the mesh 112 of the present disclosure, the injectable emulsion is flattened by the smooth surface 124a of platen 124 (and the stripper on it 122). It can be seen that the bottom surface 302'a is provided. It can be seen that the top surface 302'b of the jettable emulsion 302'is less conformal to the warp and weft threads of the mesh 112 than the current emulsion 302. (The bottom surface 302'a is where screen ink is applied and pressed using a squeegee during the actual screen printing process). In DtM, the lower surface 302'a of emulsion 302'is flatter or flat because the mesh 112 has a stripper 122 supported by smooth platen 124. This is also the result of being cured essentially immediately by UV radiation.

This process is called direct-to-mesh (DtM) and requires additional processing both before and after application of the emulsion (ie, application of the emulsion) and after application (cleaning of the unexposed emulsion and ink). Distinguished from (computer to screen). The DtM process does not require any additional treatment before or after application of the jettable emulsion 302', thus simplifying the preparation of the stencil 206.

FIG. 4 shows a flowchart of an exemplary DtM process 400 according to the disclosure herein for preparing a stencil for screen printing. In process 400, a direct-to-mesh printer 100 is provided (405). As mentioned above, the DtM screen printer 100 includes a fixture 116 for holding the frame 114, which places the pre-stretched mesh 112 in place during application of the jettable emulsion 302'. Configured to hold. The platen 124 of the DtM screen printer 100 is for holding the stripper 122 on one side of the pre-stretched mesh 112. Finally, the DtM screen printer 100 includes a printer carriage 134 that supports a print head 118 for printing a jettable emulsion 302'on the opposite side of the pre-stretched mesh 112 platen 124.

In the DtM process 400, a step 410 is subsequently performed in which the frame 114 is placed on the fixture 116. The fixture 116 is part of the printer 100 and is adapted to accept frames 114 of various sizes. The fixture 116 is configured to accurately secure the frame 114 in place so that the printer carriage 134 is accurately aligned with the mesh 112.

In the DtM process 400, the stripper 122 continues to be applied to the platen 124, either directly or via the mesh 112 (process 415). The application of the stripper 122 may be as effective when applied directly to the mesh 112 as it was previously applied to the platen 124. This can be important for very large stencils or very high dot densities such as 5,000 DPI which may have time to evaporate even when the strip 122 contains a good emulsifier.

In any case, the platen 124 coated with the release liquid 122 is brought into contact with the mesh 112 (or the platen 124 is brought into contact with the mesh 112 and the release liquid 122 is applied to the mesh). In some embodiments, the platen 124 may be raised from about 1 mm (mm) to about 2 mm above the level of the mesh in order to impart austerity to the mesh 112.

The DtM process 400 ends with a process 425 that cures the propellable emulsion 302'using UV radiation. Any common UV source can be used to cure the jettable emulsion 302'.

The DtM process 400 subsequently coats (420) the ejectable emulsion 302'on the mesh 112. As described above, the ejectable eljon 302'is applied to the mesh 112 by the inkjet printer 130 that ejects the emulsion 302'that can be ejected by the inkjet printhead 132.

The DtM process 400 comprises curing (425) the propellable emulsion 302'with UV. Any ordinary UV source can be used to cure the propellable emulsion 302'.

As a result of the DtM process 400, the stencil 206 is formed and cured and ready to be used for screen printing color on a suitable printed surface such as clothing. In particular, after curing, the jettable emulsion forms a screen stencil whose openings are used to print an image on the printed surface.

[Example 4]
Four series of examples were carried out. The following definitions are given in the examples and tables.

"Mesh resolution" refers to the number of threads per centimeter (cm), and the mesh resolution is a letter indicating the diameter of threads such as S (small diameter), T (medium diameter), HD (large diameter), etc. Can be included. For example, "43T" is a mesh having a medium diameter and 43 threads per 1 cm.

"Frame type" refers to the type of frame 114 used, which may be roller frame, aluminum, or big roller frame. The "aluminum" frame was a fixed square metal aluminum frame in which the mesh was glued at a specific tension before the start. Typical values for tension were about 26 Newtons (N). The "roller frame" was a re-stretchable frame that allowed the tension of the mesh to change after the stencil was stretched. Roller frames are much more expensive than standard square frames, but they maintain the correct tension and are much easier to re-stretch. The big roller frame was slightly larger than the roller frame.

The metal mesh was stainless steel or nickel-plated mesh. This type of mesh is often used for rotary screens, screens exposed to erosive liquids, or long-term use (many prints / presses) from the same stencil.

The "unit resolution" is the Dot Density Interweave (DPI) ejected from the printhead.

"Pulse number" refers to the number of firing pulses sent to individual nozzles.

The printhead used had eight rows of nozzles. The heading "ink channel" means how many rows were used to inject the fluid, "all" means all eight rows, and the notation "11100111" means that the middle two rows are not fired. This shows that it gives the effect of a "gap" between the jets.

“UV%” refers to the intensity of UV radiation emitted by the adjustable UV LED light source 208. The intensity of the UV LED light source 208 was modulated by a PMW (Pulse Width Modulator) to control the intensity of the generated UV light. The maximum on the adopted UV light source 208 was 100 W / cm ² . For example, the 60% notation means that 60% of the UV light was modulated to 60% of full intensity.

The “stripping liquid” refers to the composition of the stripping liquid 122 applied to the platen 124.

"Background type" refers to those used on the surface of platen 124. The platen 124 was kept at a constant height, and then a "background" was placed on top of the platen. The background types are 4mm mirror, 2mm clear glass, 2X glass (2 pieces of 2mm clear glass), "glass (up) / mirror (down)" (2mm clear glass on 2mm / 4mm mirror), "polyethylene white". (White polyethylene sheet) etc.

"TEM" is an abbreviation for Total Emulsion Measure, which is a measure of the thickness of an emulsion. Often the word EoM (emulsion over mesh) is used, which is the ratio of the thickness of the emulsion divided by the thickness of the mesh. Here, the number in μm units refers to the total thickness including the thickness of the emulsion plus the thickness of the mesh.

"Smoothness" refers to the smoothness of the stencil. On the platen side, the surface should be extremely smooth to the touch and have an identifiable roughness. On the printed side, the surface should be smooth to the touch. The slight roughness (similar to what you can experience with frosted glass) was considered "acceptable". Generally, sandpaper-like surfaces were considered "unacceptable" from the test results.

The smoothness results are based on subjective ratings, where 1 is within the permissible range, 2 is barely within the permissible range, 3 is barely within the permissible range, and 4 is out of the permissible range.

"Result" means a subjective evaluation of the overall result of the experiment. Again, we use the same subjective rating scale that describes smoothness.

The "A4 print time" is the time required to print a screen having dimensions of A4 paper (21.0 cm x 29.7 cm).

[Example 1]
In Example 1, six experiments were performed. Details are shown in Table 1A (test parameters) and Table 1B (results) below. In all experiments, UV Superflex 100 ink, an experimental ink, was used as the propellable emulsion. The mesh color in each case was white. The type of frame was various roller frames, aluminum or big roller frames, as described in Table IA. The unit resolution in each case was 1440 DPI. The printing speed of each experiment was 300 cm / sec. The number of pulses was as shown in Table IA. In the first four experiments, all eight ink channels were fired, but in the last two experiments, the two nozzle rows in the middle of the printhead were not fired, leaving a gap. UV in each case was 60% of total intensity. The stripper in all six experiments was 100% distilled water. The background type in the first three experiments was a 4 mm mirror, while in the last three experiments it was a 2 mm clear glass.

As seen in Table 1B, TQM ranged from 10 μm to 22 μm (Experiments 1, 4, 5, 6). In Experiments 2 and 3, TQM was not obtained due to the lack of a sealed mesh. For Experiment 1, the smoothness and results were acceptable, but the mesh adhered to the mirror and the resulting 22 μm TQM was determined to be excessive. Experiments 4, 5, and 6 provided acceptable smoothness, results and sealed mesh.

The 2mm clear glass gave better results than the 4mm mirror, and 2 pulses seemed to give better results than 1 pulse. It is also noted that the frames used in Experiments 2 and 3 are made of aluminum.

Table 1A DtM test, mesh = 43T, unit resolution = 1440DPI test parameters.

Table 1B DtM test, mesh = 43T, unit resolution = 1440DPI results

[Example 2]
In Example 2, 12 experiments were performed. Details are shown in Table 2A (test parameters) and Table 2B (results) below. In all experiments, UV Superflex 100 ink was used as the propellable emulsion. The color of the mesh in each experiment was yellow. The frame type in each experiment was aluminum. The unit resolution in each experiment was 1080 DPI. The printing speed was 375 cm / sec. The number of pulses is as shown in Table 2. In all experiments, all eight ink channels were fired. UV was 60% of full intensity in all experiments except Experiment 11, where UV was 40% of full intensity. The stripping liquid 122 was as shown in Table 2A. The background types were those listed in Table 2A.

As can be seen in Table 2B, TQM was in the range of 7 μm to 20 μm, and TQM was not obtained in Experiment 5. For Experiments 1-4, 6, and 12, the smoothness and results were acceptable. For Experiments 7 and 8, the smoothness and results were barely acceptable. For Experiments 5, 9, 10, and 11, neither smoothness nor results were acceptable. As shown in Table 2, these experiments resulted in mesh adhesion to the printed surface on the platen.

The only difference between Experiments 4 and 5 was the background type used, 2 x glass (top) vs. polyethylene. The former seems to give better results than the latter.

The only difference between Experiment 4 and Experiments 7-8 was the type of background used, 2 x glass (top) vs. 4 mm glass (top). The former seems to have yielded better results than the latter.

For Experiments 9, 10, and 11, these were the only experiments using liquids containing 95% distilled water and 5% ANODAL ASL (Gedacolor). Other liquids such as 100% distilled water + 20% distilled water + 20% dead sea salt, 80% distilled water + 20% alcohol, and 50% distilled water + 25% window cleaner + 25% isopropanol are all acceptable or limit acceptable. Smoothness and results were given.

Table 2A DtM test, mesh = 43T, unit resolution = 1080DPI test parameters.

Table 2B DtM test, mesh = 43T, unit resolution = 1080DPI results

[Example 3]
In Example 3, five experiments were performed. Details are shown in Table 3A (Test Parameters) and Table 3B (Results) below. In all experiments, UV Superflex 100 UV ink was used as the propellable emulsion. The color of the mesh in each experiment was yellow. The frame type in each case was aluminum. The unit resolution in each experiment was either 1080 DPI or 1440 DPI. The printing speed was either 300 cm / sec or 375 cm / sec, as shown in Table 2A. The number of pulses is as shown in Table 3A. In all experiments, the two nozzle rows in the middle of the printhead were not fired, leaving a gap ("11100111"). UV was 60% of total intensity. The strip 122 in all six experiments was 100% distilled water. The background type in all experiments was a 4 mm mirror.

As seen in Table 3B, TQM ranged from 3 μm to 45 μm. Smoothness was acceptable for all experiments, but 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 Experiment 1 and Experiment 2, the number of pulses was the same in both (2), but in Experiments 3, 4, and 5, the number of pulses was different (1). Due to this difference, Experiment 1 and Experiment 2 seem to have slightly unacceptable results.

Table 3A DtM test, mesh = 120T, 43T test parameters

Table 3B DtM test, mesh = 120T, 43T results

Example 4 was carried out. Details are shown in Table 4A (test parameters) and Table 4B below. The mesh resolution was 195 (US standard) in all experiments. In all experiments, UV Super Flex 100 UV ink was used as the propellable emulsion. The mesh color was gray / metal in each experiment. The frame type was made of metal. The unit resolution in each case was 1440 DPI. The printing speed was 300 cm / sec. The number of pulses was 1 in all experiments. In all experiments, the two nozzle rows in the middle of the printhead were not fired, leaving a gap ("11100111"). In Experiments 1 to 3, UV was 60%, 40%, and 30% of the total intensity, whereas in Experiment 4, UV was 30% of the total intensity. The stripping solution of Experiments 1 to 3 was distilled water, and the stripping solution was not used in Experiment 2. The background type in both experiments was a 3 mm mirror.

As seen in Table 4B, TQM was 14 μm in all experiments. For Experiments 1-3, both smoothness and results were unacceptable, but for Experiment 4, 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 using 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, the frame was also made of metal, but no liquid was used, and acceptable smoothness and results were observed. Apparently, the liquid and frame combination is one of the factors for acceptable smoothness and results. Under certain conditions, it has been found that better results are obtained without the release fluid or backing paper. Based on the tests described above, it is possible to formulate an emulsion that works without any backing surface.

Table 4A DtM test, mesh = 195 (US standard) Test parameters

Table 4B DtM test, mesh = 195 (US standard) results

From the above examples, the results are liquid (emulsion and stripping liquid), platen composition (eg 1 glass, 2 glasses, glass + mirror, etc.), curing strength (20% -100% UV), dots. It appears to be affected by some very complex interactions such as density (1080, 1440), number of pulses, etc. From an analytical point of view, the combinations appear to be almost infinite. Currently, the only method for evaluating a set of parameters must be practical, i.e., each set must be tested based on the teachings here. However, such tests are not considered excessive.

Benefits of the DtM process 400 include eliminating both stencil creation and post-processing altogether, as follows:

No machines such as emulsion applicators, dryers or separate exposure units are required.

Most of the chemicals (excluding degreasers) and more than 80% of water usage are reduced.

All processes can be carried out without the need for a special low UV lighting room. In fact, the DtM process can be carried out in normal factory / office lighting or daylight. The propellable emulsion is retained inside a UV protected cartridge or bag during handling. The propellable emulsion is exposed to daylight or UV light only when jetted onto the mesh 112.

The process disclosed herein can use conventional, cheaper mesh 112, so it is better to strip the mesh from the frame 114 and re-stretch it for water, chemicals and special cleaning stations. Often it can be more efficient and cheaper than mesh cleaning that requires.

The raw material, unprocessed screen, or mesh 112 is placed on the direct-to-mesh printer 100, the ready-to-use stencil 206 is removed from the screen, and directly on the carousel to print the image on the printing surface. Can be placed.

A further advantage of the DtM process 400 is that each stencil 206 is very accurately registered on the mesh 112 so that micro-alignment can be omitted when mounted on the carousel. In the DtM process 400, each stencil 206 is precisely (absolutely and relatively) placed on the frame 106 so that no adjustment is required or required. This is achieved by the use of the frame fixture 116. The stencil frame is generally provided with registration holes, or points. Each different carousel maker has its own registration system. The frame fixture 116 comprises the same alignment system (or, in some cases, an auxiliary alignment system of a different design). The frame fixture 116 allows accurate alignment of the stencil frame 114. To achieve this, a test print is done in 4 colors (or 6 or more colors) and then the carousel is fine-tuned. If no carousel changes (or the carousel is out of alignment) and all stencils are created on the same printer, the stencils will be aligned correctly.

The DtM process 400 disclosed herein, as well as process chemicals and water, significantly reduces process time and complexity, labor, and / or capital equipment (including specialized lighting equipment). It will be understood that it can be reduced to.

The DtM process 400 can also be used for rotary screen printing. Rotary screen printing is used in some narrow but frequently repeated printing processes (wallpaper, linear linoleum, etc.) such as labeling. Rotary screen printing is very fast in these applications, where each of the four colors (and any spot color) is placed on a cylinder and the material passes underneath. In rotary screen printing, it is common to use stainless steel mesh 112 for durability and stability.

Today, many rotary stencils are made by large service bureaus (about three in Europe). Each stencil can cost more than 100 euros, and the annual cost of replacing a stencil can be hundreds of thousands of euros. It doesn't even consider the inconvenience of using it in a service bureau. Many companies can recover the cost of their machines in a few quarters while reducing their reliance on expensive service bureaus.

It will be appreciated that in the above description, a number of specific details are provided to provide a complete understanding of the embodiments. However, it will be appreciated that the examples can be implemented without limitation to these specific details. In other examples, well-known methods and structures may not be described in detail in order to avoid unnecessarily obscuring the description of the examples. Moreover, the examples may be used in combination with each other.

As used herein and in the appended claims, the singular forms "a", "an", and "the" include a plurality of referents unless explicitly stated in the context. It will be appreciated that the above description provides a number of specific details to fully understand the embodiment. However, it is understood that it can be implemented without limitation to these specific details. In other examples, well-known methods and structures may not be described in detail in order to avoid unnecessarily obscuring the description of the examples. Also, the examples can be used in combination with each other. Further, when describing a value using "about", this means including small variations (up to ± 10%) from the stated values, such as those that can be induced by manufacturing variations. ..

Further, the order of the process steps in the claims can be exchanged as appropriate. For example, dispensing the strip 122 onto the platen 124 or mesh 112 may include dispensing the strip onto the platen and then carrying the platen and mesh together. Alternatively, the platen and mesh may be combined to dispense the stripper onto the mesh.

Although a limited number of examples have been disclosed, it should be understood that there are numerous modifications and variations from them. For example, the printer bed / table "orientation" may be changed from horizontal to vertical due to new high / ultrafast printhead technology that may allow jet injection onto vertical planes.

As seen in Table 1B, the TEM ranged from 10 μm to 22 μm (Experiments 1, 4, 5, 6). In Experiments 2 and 3, no TEM was obtained due to the lack of a sealed mesh. For Experiment 1, the smoothness and results were acceptable, but the mesh adhered to the mirror and the 22 μm TEM obtained was determined to be excessive. Experiments 4, 5, and 6 provided acceptable smoothness, results and sealed mesh.

As can be seen in Table 2B, the TEM ranged from 7 μm to 20 μm, and no TEM was obtained in Experiment 5. For Experiments 1-4, 6, and 12, the smoothness and results were acceptable. For Experiments 7 and 8, the smoothness and results were barely acceptable. For Experiments 5, 9, 10, and 11, neither smoothness nor results were acceptable. As shown in Table 2, these experiments resulted in mesh adhesion to the printed surface on the platen.

As seen in Table 3B, the TEM ranged from 3 μm to 45 μm. Smoothness was acceptable for all experiments, but 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.

As can be seen in Table 4B, the TEM was 14 μm in all experiments. For Experiments 1-3, both smoothness and results were unacceptable, but for Experiment 4, smoothness and results were acceptable.

Claims (15)

A direct-to-mesh screen printer for creating screen stencils.
A frame to hold the pre-stretched mesh in place while applying the jettable emulsion,
・ Fixtures for holding the frame and
-A platen for holding the stripper on one side of the pre-stretched mesh,
A stripper dispenser that supplies the stripper onto the platen or mesh.
A printer carriage that supports a printhead for printing a jettable emulsion on the opposite side of the pre-stretched mesh to the platen.
Direct to mesh screen printer including. The direct-to-the-point according to claim 1, wherein the fixture is configured to firmly hold the frame with the pre-stretched mesh in place during application of the jettable emulsion. Mesh screen printer. The direct-to-mesh screen printer of claim 1, wherein the platen is configured to hold the stripper firmly against the bottom of the pre-stretched mesh. The direct-to-mesh screen printer of claim 3, wherein the platen is smooth, hard, impermeable to the stripper, and resistant to dents and cracks. The stripping solution is applied very thinly and evenly to the platen or directly to the platen when the mesh is placed on the platen, and the mesh is applied to the platen while the injectable emulsion is being applied. The direct-to-mesh screen printer according to claim 1, which prevents adhesion. The direct-to-mesh screen of claim 1, wherein the stripper is configured to suppress dot gain while at the same time providing a smooth, cured surface that does not react to the injectable emulsion. -Printer. The direct-to-mesh screen printer of claim 1, wherein the stripper comprises water and an amount of at least one emulsifier sufficient to prevent evaporation of the stripper. The direct-to-mesh screen printer of claim 1, wherein the jettable emulsion has a low viscosity of about 4 cP to about 15 cP and is both durable and flexible / elastic. The direct-to-mesh screen printer of claim 8, wherein the jettable emulsion is a UV-activated acrylate monomer that has the property of an elastomer after curing. The direct-to-mesh screen printer of claim 1, further comprising a UV source for curing the jettable emulsion to form a stencil for screen printing. A fixture for holding the frame configured to hold the pre-stretched mesh in place during application of the jettable emulsion and a stripper to one side of the pre-stretched mesh. Direct-to-mesh, including a platen for holding the pre-stretched mesh and a printer carriage supporting a print head for printing a jettable emulsion on the opposite side of the pre-stretched mesh to the platen.・ Providing a screen printer and
・ Placing the frame on the fixture and
-Applying the release liquid to the platen or mesh and
・ Tensioning the platen and the mesh
-Applying the sprayable emulsion to the mesh and
-Curing the injectable emulsion using UV radiation and
Process including. 11. The process of claim 11, wherein the cured emulsion forms a screen stencil, and the openings in the screen stencil are used to form an image on the surface. 11. The process of claim 11, wherein the exfoliating liquid does not adhere to the injectable emulsion after curing and is configured to suppress dot gain at the same time. 11. The process of claim 11, wherein the stripper comprises water and an amount of at least one emulsifier sufficient to prevent evaporation of the stripper. 11. The process of claim 11, wherein the jettable emulsion is a UV activated acrylate monomer having elastomeric properties after curing.

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