Explanation and use
When screen-printed apparel sales fall to some extent, designers will be more committed to finding a new visual experience that can attract consumers' attention. Perhaps high-density printing is what they are looking for.
With this method, various colors can be printed, and with a little time and effort, a careful printer can master high-density printing. Below, we make a general discussion on the details of this new method, including the entire process from design pattern selection, plate making, ink processing to printing and drying. Like other new things, this new scheme also needs trial and error to adapt to different printing factories. So don't be afraid of mistakes.
Pattern selection
This is the first step that you need, and perhaps the most important consideration. Line thickness and pattern size are also decisive factors for the success of the high-density printing process. For example, after the printing process is completed, the thin lines will look better than the large area printing. Small area printing design, especially at right angle, compared with large area printing, the ink is easier to hang on the mesh when printing. In general, you must be very familiar with the types of patterns suitable for high-density printing, and you should not use this technique for inappropriate patterns. There are also many patterns that if 3D processing will greatly enhance the visual experience. You need to use these to your advantage.
Plate making
The thickness of the ink layer is determined by the screen yarn thickness and screen thickness. Plate making can use the method of direct coating of photosensitive emulsion, direct / indirect method, or capillary film method, which will be introduced one by one below.
For most thick versions, the commonly used 60-110 mesh (per inch) may be used. You may wish to use a mesh tension lower than normal, such as 14-20 Newtons. Thick plates and thick ink accumulation require a larger screen pitch, and perhaps increased tension can be achieved. With this concept in mind, stop thinking about your prints being too "high". If you think so, you will make the screen distance too close, and make the appropriate screen distance impossible.
In any case, you need to prepare a suitable degreaser to clean the mesh. After sufficient drying time has elapsed, coating or patching (indirect film) is required.
Direct photosensitive emulsion film is achieved by repeatedly coating the printed surface until the required coating thickness is reached. This will take a day or more. Because each coating requires drying to less than 4% moisture content (takes 30 minutes to 1 hour, depending on the emulsion and drying conditions you use) to apply the next layer. After all coatings are completed, you also need to allow the template to be further dried (such as overnight) before exposure, because the screen will not have a good exposure if it is not fully dried.
How to choose a suitable photosensitive emulsion also needs to be studied next time. The best choice is the one with high solids content. The higher the solid content, the less likely to shrink when dry. In addition, use a quick exposure emulsion to minimize exposure time. It takes quite a while to expose the 400-1000 micron film.
â— The single-component light-sensitive polymer emulsion has high solid content and fast exposure speed;
â— The solid content of the diazo-based photosensitive polymer is high, but the exposure speed is not fast enough;
â— The solid content of diazo-based photosensitive emulsion is not high and the exposure speed is the slowest. (The higher the solid content of the diazo-based photosensitive emulsion, the slower the exposure speed)
Either one is available, but I recommend using a photopolymer because it has the fastest exposure speed and good shrinkage control.
The first step is to apply a wet coating on both sides of the screen, and then apply a little more force on the ink side. This allows the photosensitive emulsion to "settle" on the printed surface. Place the screen on a horizontal shelf with the printed side facing down.
After a certain amount of time to dry, enter the thickening stage:
Thickening can be achieved by several different methods:
1. Standard coating: Use a rounded scraper to apply two layers of coating from the bottom to the top (do not dry in the middle). Flip the screen to apply two more wet coatings from the opposite direction on the printing surface. This is called coating 1. Marking the coating helps you know exactly how many times you have applied the coating. Now let it dry, then repeat the above action until the expected thickness is reached. Leave enough time between each coating to let it dry. Depending on your thickness requirements, eight, ten, or more layers may be required. When the third and fourth layers are applied, the screen may be thicker in the middle than the edges. If this is the case, you need to apply one to several more times on the edges to make the thickness of the stencil consistent. You can pour a small amount of emulsion around instead of in the middle. Repeat twice in each direction to make a standard coating, which will leave the emulsion only around the screen. When the eighth or more layers are achieved, it needs to be repeated many times to make the thickness uniform. After the coating is completed, allow sufficient drying time. My suggestion is overnight.
2. Tape assisted coating: stick tape along the periphery of the screen frame, but the width between the tapes should not exceed the scraper. This will help increase the distance between the scraper and the screen, and allow a thicker emulsion to accumulate with each operation. Calculate how many layers of tape to use based on the base thickness. For example, if your tape thickness is 3 mil (1 mil = 25 microns), for a 300-micron-thick film layer, you need 4 layers. In order to achieve the required thickness of the screen, you may need to laminate tape, taking into account the shrinkage factor. Apply the coating twice in each direction, and be careful to keep the scraper "riding" on the tape. Remove the tape before drying to avoid tearing off the dried photosensitive emulsion. Then place the screen on a horizontal shelf with the printed side facing up. For thicker screens, the operation can be repeated as needed, that is, after each coating is completed, a new tape is laminated, and then the next round of operation is performed. Allow enough time to dry in the middle of each coating, and enough time after completion. My suggestion is still overnight.
3. Squeegee coating: This method requires a support plate to provide a flat surface on which the screen ink is placed face down. Correspondingly, the size of this board is smaller than the inner edge of the net basket, but higher than the height of the net frame, so that it can be closer to the mesh. Stick the tape along the outer edge of the screen, but make sure that the width between the tapes does not exceed the coating knife and the support. Stack the tape together (as before) to achieve a thickness to complete the coating in one go (considering shrinkage). At the end of the tape, where the scraper starts and stops, leave extra width to remove unwanted emulsion to keep the screen clean. Now put the photosensitive emulsion on one end of the screen, put the doctor blade along the tape at the same end, and then slowly and steadily push the doctor blade. When finished, place the screen printing face up on a horizontal shelf. Then let it dry for enough time-at least overnight. One disadvantage of this method is that this time, applying such a thick layer may cause unevenness on the surface. The reason is that bubbles rise from the emulsion or are surrounded by dried emulsion near the surface. But this is not the problem itself. Think about the effect of using a negative with a bubble inside to expose it? And, if you use this method, you'd better put the emulsion long enough before the coating to let bubbles out, and ensure that your technology will not introduce new bubbles in the following steps. This is similar to the direct / indirect method of using capillary film. This screen is made by pre-coating the film with emulsion, and then placing the drug film face up on the table, and applying the screen printing surface to the film. Then, use a squeegee to apply photosensitive emulsion to the ink surface. After drying, peel off a layer of protective film on the back. This method considerably improves the firmness between the film and the mesh.
First of all you have to consider which kind of film to use. As with the inter-emulsion, there are diazo type and photosensitive compound type film. The aspect that does not need to be considered is the solid content. Because the indirect film itself is dry and has a 100% solids content. There is no need to consider shrinkage, just simply determine the thickness you need.
Then you also need a support plate, a small roller, a blunt or rounded scraper, and a jade layer emulsion that can work with this film. Place the film emulsion face up on the support plate, then place the screen printing face down on the film tightly. Apply tape to the inside of the screen, the area enclosed is slightly smaller than the film, which helps to deal with the remaining photosensitive emulsion, and can also keep the inside of the screen clean. Pour the photosensitive emulsion on one end, hold the spatula, and slowly, using a standard printing technique, push along the screen. This can be applied with a thin layer of photosensitive emulsion. After drying, it will stick the mesh and film together. Then put it in the dry plus, allow enough time to dry, and then peel off the backing protective film.
You can start exposure now, or you can "roll" it on top of it. To do this, you can place the screen ink on the support plate face down. Put a drop of photosensitive emulsion on the film, put a second layer of film, first from the edge. Then began to use the roller to roll over the film to drive away the bubbles until the entire film was completed. Allow sufficient time for drying, then peel off the backing layer. (At least one company now produces a direct / indirect film, and each layer can be glued together before you stick it to the screen. There is no need to use a photosensitive emulsion; you only need to simply peel off the protective layer and glue it On another layer, then press together with a roller. By pressing the second or more layers to achieve the thickness you want.)
Carefully stick the capillary film on the wet (with water) screen, and use the capillary action to draw the emulsion on the screen. Although you can stack two or more layers of photosensitive film together to increase the thickness, it will have better results if the film is originally thick enough (now the thickness can be 1000 microns; this film can take you The time to make an online version has dropped from one day to less than an hour; the downside is that they are worth $ 50 or more per piece).
Both direct emulsions and direct / indirect films are available in diazo and photosensitive compound types. Similarly, after film drying, the solids content is not a problem. The photosensitive compound is exposed to light very quickly, and all that needs to be done now is to determine the thickness. Capillary photosensitive film is easier to use than straight / indirect film because it uses water to bind the emulsion to the mesh through capillary action. Thick photosensitive polymerized films are available in various specifications and can currently reach 1000 microns. This eliminates the need to crush several layers together.
All you need is a skimmed version, a piece of film, water and a spatula. The method I chose is to place the film emulsion face up on the support plate, and then place the screen printing face down on it. Use a spray bottle to spray a little water for a few seconds to let the capillary action suck the film on the mesh, and then gently scrape off the excess water with a scraper. After drying, you can take the exposure or roll a second layer of film behind it. (There is also a "roll down" method that is also common in capillary photosensitive film applications; but may not be used to it quickly. Although both methods can achieve satisfactory results, the one mentioned here It is easier to operate.)
The last thing to mention is that you can apply the photosensitive emulsion through the screen ink, and increase the durability of the capillary photosensitive film through the direct / indirect duty method.
How thick do you want to make the screen version? Thick printing is harder than standard printing. This requires a little adjustment to achieve the best printing effect, the most is to start from a small amount and then continue to improve. One advantage of printing thermosetting ink is that you can dry the first layer instantaneously, and then you can print the next layer. This method allows you to use a template that is not so thick; I recommend using a range of 150-300 microns at the beginning and increasing it as the technology improves.
Ink
How to find an ink that can meet various requirements has become a biggest obstacle. At the beginning, you better use the ink with better release. Low viscosity, paste ink is better than high viscosity ink. Then, decide how you want the finished product to appear, smooth or rough? Is it rounded or right? Make a good decision before choosing from various inks.
Here are some statements you may use when describing inks:
â— Thickening to increase viscosity. Silica powder is very useful, this additive is used by most manufacturers and is intended to work on all inks;
â— You need a high speed mixer to mix the thickener into the ink. The method of using electric drill and scraper is good;
â— Concentrate foaming additives or foaming bottom slurry to produce rough surface;
â— Lubricant or surface activity increase the fluidity of ink;
â— Tension additives and tension bottom slurry can increase the elasticity, which avoids cracks in your design;
â— Concentrated pigments can increase the intensity and brightness of existing colors. A good way is to check all available additives or modifiers. You will find that each manufacturer actually has many kinds of additives and modifiers, so you need to find an additive that you think is suitable for most situations.
Ink manufacturers have begun to produce products that can handle high-density printing. This can save you debugging time. Remember that they will appear in different appearances in the same category. Therefore, you will also want to know how to better "control" these inks in production.
To make a matte (rough surface) pattern with flat edges, all you need is a low viscosity paste ink. Try to use the ink alone to print what the finished product will look like. If a flat matte surface appears, you do n’t need to add anything; if not, add a concentrated foaming agent or foaming primer, and add a small amount until you reach the matte gloss you need. Then add thickening powder to make it a state similar to paste. The thicker the ink, the smoother the edges, but the harder it is to clean the screen. In order to better clean the screen, you may need to use thinner. Similarly, it is necessary to gradually increase the amount to avoid the ink layer being too thin. At the same time, the right-angled edges cannot be lost. If the ink has poor tensile strength, it should be added with tensile additives or primer. The exact amount of these ingredients depends on the ink and additives you choose. As usual, it is better to record the "retouching" you made, preferably by weight rather than volume.
For the smooth surface pattern with flat edges, the same method as the matte surface (rough surface) pattern is used, except that the use of foaming additives is omitted. If you start with a matte ink (no foaming ingredients added), try adding a tensile additive, or simply change to a low viscosity ink that has a high gloss after drying. Similarly, the exact amount of these ingredients depends on the type of ink and additives you choose.
High-gloss and high-definition patterns with inlaid edges (or rounded corners)-like embellishment of plastic sheets that imitate "welding"-can be printed on multi-color patterns, such as logo images. The selected transparent pulp requires no milky white or yellow after drying, which will also have a high gloss. If necessary, thicken the ink to increase viscosity. This pattern generally does not require a right angle, so do not care too much about the consistency of the ink.
Make a matte side (or rounded corners) matte side (rough side) pattern, using low viscosity ink at the beginning. Gradually add a small amount of thickener, but also pay attention to the fluidity of the ink, so do not wait for the ink to become a paste before stopping. If necessary, add thinner to increase fluidity. In order to increase the three-dimensional feeling of matte surface (rough surface), a little foaming agent can be added. You do n’t need a right angle, so you can add a little more, but do n’t overdo it to make it a standard foaming ink (this will make the surface of the finished product prone to wrinkles and reduce durability).
Printing method
"Usage" is the key here. Developing a method can keep your production in an uninterrupted state, if your technology can only proof, it is not profitable.
Any printed pattern must have a good screen, to ensure that there is enough "free" area around the design, that is to say, the screen frame should be large enough, and the printed area cannot be based on all or almost all of your screen frame. Choose the right ink scraper and push ink stroke distance. After the screen is completed, there is no way to increase the size or increase the scratch stroke. Unless you have to do the online version. Then start with a squeegee with a hardness of about 70 degrees. It is a good idea to have a variety of squeegees of different hardness to spare. If it is a double or triple layer, it can be better controlled. The ink push-back plate should be adjusted to the maximum loading capacity of the screen (referring to the ink to fill the open mesh). If the ink can be pushed back properly, it becomes easier for the doctor to scrape the ink.
Net pitch is a critical adjustment and is also very important. If there is not enough screen distance, the ink cannot be released from the screen onto the clothing. Because the screen pitch is directly related to the screen tension. Screens with high tension require low pitch. Therefore, if necessary, increase the pitch of the low-tension screen.
At the beginning, the printing ink and ink return speed are adjusted to the minimum, and the speed is gradually increased without affecting the printing effect. If the pressure is too high, you will squeeze the ink into the fabric, it is best to let the ink "sit" on the clothing.
If you want the maximum thickness, then stack another layer after drying. Printing two thin layers is much easier than printing one thick layer.
Instant drying
The drying time needs to be carefully calculated to achieve the most suitable drying fixing effect and temperature. Remember that not all instant dryers are the same. For example, quartz tube dryers heat fast. It can quickly dry the surface but it cannot be heated by another 2/3 of the thickness of the ink. Therefore, the first ink layer is inconsistent in physical and chemical states. This may cause the first layer of ink to not support the second layer of ink well, which is a common problem in thick printing. In such cases, infrared drying panels are more appropriate. If the amount of ink is large and it must be heated and dried, it will stay longer. If you want to superimpose your printed patterns layer by layer, you will need to dry them multiple times. So you also need a second or more instant dryers.
Final drying
Curing thermosetting ink generally requires a temperature of 360oF (160 ° C), except that the thickness of the ink layer is 3 times (or higher). This thick printed pattern will take longer to reach the drying temperature, so the residence time should be considered when adjusting the oven temperature. You can also increase the drying temperature, but do not attempt to dry too quickly. Drying at high temperatures for a short period of time can cause other problems. (Text / Professor Hitoshi Ujiie of Philadelphia University) (Compilation / Zhang Zhenbo Sun Man)
- Magnetic surface allows you to use magnets to pin notes, messages, pictures, memos, calendars etc.
- Sturdy aluminum frame with ABS plastic corners, no worry about pointy edges
- Magnetic dry-erase board for sharing ideas and getting organized; ideal for home, school, or office
- The height can be adjusted about 63~78.5 inches, so you can always get a comfortable position. Standing white board is equipped with flipchart hooks, elastic clip and marker tray, you can hang presentation materials or paper pad(recommend 34.25"x22.24") on its flip chart hook or paper clip and place dry erase markers on the marker tray, no messy on the floor
Magnetic Whiteboard With Stand,Office Magnetic Glass Flipchart Easel,Magnetic Glass Flipchart Easel Board,Tempered Magnetic Glass Flipchart Easel
WENYANG STATIONERY MANUFACTURING CO.,LTD. , https://www.marvelousboard.com