The plate you are talking about should be a resin plate, solid photosensitive resin plate making method
Solid photosensitive resin plate is characterized by its fast plate making speed, high printing durability, high resolution, With the advantages of no pollution, it has become the preferred plate material in letterpress printing at home and abroad.
In more than ten years of development, research and promotion of PVA-500 series solid photosensitive resin plates and YZB series solid photosensitive resin plate making machines, we have found that due to users’ insufficient understanding of the characteristics of the plates, there is no Choose good plate making equipment, resulting in unsatisfactory plate making quality.
Here are some ways to quickly master plate making for your friends’ reference at work.
The water-soluble solid photosensitive resin plates we use are all photopolymerizable materials, which undergo polymerization reactions under irradiation of 360nm ultraviolet light. Because it is a water-soluble material, use clean water to rinse away the unexposed parts. After rinsing, it is dried and then post-exposed to stabilize it and improve moisture resistance and print durability.
When using the YZB plate making machine to plate, first set the rinse temperature, rinse, drying time, drying temperature and post-exposure time so that it is a fixed value in each plate making. In this way, we Just control the exposure time according to the job.
1. Exposure
First peel off the protective film of the resin plate, apply some talcum powder to facilitate the absorption of the plate and prevent the film from adhering to the plate, and then expose.
Use a magnifying glass to observe the side of the prepared plate (as shown in Figure 1). You can see that the photosensitive coating is a trapezoid, and the normal angle a is about 70°. Angle a decreases as the exposure time increases. The exposure time is long, and the characters and lines are very strong. After washing and drying, the characters are not easy to fall off or bend, but the produced plate is not thorough enough in small areas, and it feels like something has not been washed out in the gaps; The exposure time is short, the A angle is increased, and after washing and drying, the pen may be missing and the lines may be bent, or the characters and lines may be washed out after washing and drying. If you don't know the correct exposure time, you can first use a small plate and choose different exposure times for exposure. After rinsing and drying, you can determine the correct exposure time by observing the slope of the printed plate. The exposure time of Tianjin Cooltech PVA-500 plate is about 5~7 minutes.
2. Rinse and dry
When the resin plate is rinsed, as the temperature of the rinse water increases, the rinse time should be shortened. However, the water temperature cannot be too high. Generally, it is better to set the washing water temperature of domestic plates at 45°C. The rinsed plate can be directly placed in the drying chamber of the plate-making machine, with the temperature set at 90°C and time of 15 to 20 minutes.
3. Post-exposure
Put the prepared plate directly into the exposure chamber of the plate-making machine for post-exposure. The post-exposure time is generally equal to or longer than the first exposure.
Common troubles and troubleshooting of solid resin plate making
In recent years, water-soluble solid photosensitive resin plates have the advantages of simple plate making process, low cost, no pollution, good ink transfer performance and print durability. It has the advantages of high efficiency, light plate material, short plate making cycle, and can be matched with computer laser phototypesetting system. It is favored by small and medium-sized printing manufacturers and is gradually replacing zinc plates.
Photosensitive resin plate is a letterpress plate with photosensitive properties made by using synthetic polymer materials as film-forming agents and unsaturated organic compounds as photo-crosslinking agents. Almost all photosensitive resin plates undergo cross-linking reactions between molecules under the irradiation of light (mainly ultraviolet light), thereby forming a certain insoluble relief image. Photosensitive resin plates can be divided into two types: solid type and liquid type in terms of plate making technology. The solid series of prefabricated plates composed of saturated photosensitive resins are more expensive, but the quality is relatively good, and can be used to produce product packaging, trademark plates, and screen printing plates; the liquid series composed of unsaturated polyester resins are Coated plate (simply put, it is used to prepare photosensitive liquid for base production, and then coated with resin, sensitized and produced) is relatively cheap and suitable for rougher text line plates. In the actual plate making process of solid photosensitive resin plates, the following problems often occur. Only by comprehensive analysis, differentiated treatment, and finding out the root causes of the problems can the problems be solved.
1. The text, lines, and patterns on the resin plate are too thin or too small, the small characters and independent dots fall off, and the small lines are bent
When making resin plates, thin lines are common Problems such as bending and small text, and independent points falling off.
Main reasons:
l. Insufficient exposure time of the resin plate;
2. The film contrast is small, foggy and unclear;
< p>3. Improper baking and thermal curing of the resin plate;4. When brushing the resin plate, the water temperature is low, the rinsing time is long, the bristles are too hard, and the plate is brushed too deep;
5 , The pressure is too high when printing on the machine, and the adjustment is improper.
Solution:
1. When making resin plates, when encountering small text, lines, patterns, and independent points, the correct exposure time must be mastered. The exposure time of the 3kw gallium iodine lamp is about 20 minutes. The exposure time must be longer than that of the normal version, so that small lines, text, and independent points can stand up and not fall off. Due to the long exposure time, the resin plate produced has a small side slope (about 70°) and a solid base for graphics and text.
2. When baking the resin plate, drying and heat curing, under normal circumstances, the oven temperature is controlled between 60 and 80°C, in order to evaporate the water on the plate; the drying temperature is too high, The resin version is prone to blistering.
3. The operator is required to have excellent darkroom skills. The contrast of the film processing should be as good as possible, without fog, the text and lines should be smooth and smooth, and there should be no lack of pen breaks.
4. When making solid resin plates, whether it is automatically brushed by a plate-making machine or brushed by hand, the water temperature should be controlled at 50-60°C and rinsed until the base is exposed. When brushing a resin plate, you need to rotate the brush. When brushing the plate on one side, it is easy to brush the side and slope, causing small lines to bend and fall off. When brushing the plate, you should choose a brush with soft and suitable bristles. If the bristles are hard, it will cause Small text will be damaged when brushed off; when brushing a resin plate, pay attention to the depth of brushing. It is not necessary to rinse the plate until the bottom is exposed. Brushing the plate too deep will easily cause the words, lines, and patterns on the plate to be brushed away. In addition, pay attention to brushing. Do not rinse the plate for too long.
5. When the resin plate is placed on the machine for printing, it is necessary to adjust the pressure between the inking roller and the resin plate, and the resin plate and the impression cylinder. Adjusting the printing pressure of the resin plate is better than adjusting the copper-zinc plate. , the pressure of printing movable type is smaller. Avoid crushing the fine text lines of the resin plate due to excessive pressure, which will affect its print durability.
2. Text and line plates are blurred when making resin plates
Main reasons:
1. Overexposure;
2. Vacuum adsorption is not accurate when drying;
3. The contrast of the film is small and unclear.
Solution:
1. Master the accurate exposure time of the resin plate, especially hollow text and lines that are most likely to be blurred. Make the graphics and text as bold as possible during design.
2. The air intake of the printing machine should be firm. If the air is not properly sucked, there will be a gap between the resin plate and the film, and ultraviolet rays will enter from all sides, causing photosensitive plates to be pasted.
3. Before printing, you must carefully check whether the apricot film is pasted. Only by having good light transmittance, good contrast and clarity can you meet the needs of plate making quality.
3. The resin plate cannot be washed away
Main reasons:
l. The resin plate has exceeded the shelf life, or has been left unproduced, stored, or transported Light leaked during the process, and the resin plate was photohardened;
2. The water temperature was too low when washing and brushing the plate;
3. The film was not processed well in the darkroom, and the film had poor light shielding and low density.
Solution:
1. The shelf life of the resin plate is about half a piece. Printing manufacturers should purchase according to the production capacity and dosage of the factory. Do not blindly buy too much, otherwise it will cause the expiration date. Invalid.
2. The resin plate is a photosensitive material, and we are most afraid of light leakage during production, storage and transportation. When storing resin plates, temporarily unused plates should be placed in a sealed box and sealed in a black plastic bag; resin plates should be stored in a dry, moisture-proof place.
3. When printing, the water humidity should be controlled at around 60-70℃. If the water temperature is too low, it will affect the dissolution of the non-photosensitive resin film when it encounters water; if the water temperature is too high, the dissolution will be accelerated.
4. Patterns or scratches appear on the resin plate
Main reasons:
1. A small amount of talcum powder was not applied to the resin plate between exposures , corn starch, resulting in loose contact between the film and the resin plate, resulting in bubbles;
2. The vacuum pump of the printing machine does not suck air properly;
3. The film is light-transparent The side is not smooth and has gray fog.
Solution:
1. Apply a small amount of talcum powder and corn starch on the surface of the resin plate. The purpose is to prevent the resin on the plate from adhering to the film and causing incorrect air suction. A small amount of fine particulate matter attached to the resin plate can solve this problem.
2. After the plate printing machine has been used for a period of time, it must be repaired in time, add vacuum oil, and clean the dust and paper wool in the wall of the suction rubber tube. The air suction volume of the vacuum pump is generally 30-40m3/ h.
3. The light transmittance of the negative film should be good, pay attention to the exposure and development time, and fix and wash thoroughly to ensure that the negative film has no fog or yellowing.
5. The resin plate is curled and cracked
Main reasons:
1. The drying and heat curing time is too long;
2. Excessive post-exposure (fill light);
3. The plate is expired or has quality problems.
Solution:
1. The drying and heat curing time of the resin plate cannot be too long. As long as the layout is dry and the curved lines straighten.
2. Post-exposure (fill light) is carried out after drying and heat curing. Do not use excessive fill light, otherwise the resin will easily become hard and brittle. Just see the layout change from green to light red and then to antique yellow. If the plate is seriously curled, soak it in water for 5-10 minutes and then dry it again.
3. When using plates, be sure to recognize the production date. Expired and deteriorated plates are prone to curling and should not be reused.
6. The printed pictures and texts are incomplete
Main reasons:
1. The glass plate of the plate machine is seriously dirty;
2. When tracing ink on the negative plate, the picture and text part of the negative was stained, and the red tear-off film fragments from the imposition fell onto the negative;
3. When brushing the plate, the force was too strong and the bristles were too hard.
Solutions:
1. Develop good working habits of civilized and safe production. Before printing, clean the dust, oil, ink spots, paper scraps and other dirt inside and outside the glass plate of the printing machine with water or cotton wool dipped in alcohol.
2. When tracing ink on the negative, be careful not to cover the graphics and text. Only after the ink is dry can you print the plate. Use imposition red tear-off film to cover the layout to prevent fragments from falling off and blocking the graphics and text. Resulting in incomplete pictures and text.
3. When brushing the resin plate, the force should be even, heavy first and then light; the bristles should not be too hard. At the same time, it is also necessary to prevent hard objects from scratching the layout and causing damage.
Paths to improve the quality of resin plate making
In recent years, small and medium-sized printing companies have eliminated copper-zinc plates that are seriously polluting, cumbersome to operate and cannot be controlled in quality. In addition to trademarks and hardcover books, In addition to copper-zinc plates for hot stamping on covers and packaging decoration, other letterpress printing, such as self-adhesive and bill printing, use simple plate-making procedures, short plate-making cycles, good ink transfer performance, light weight, no pollution, and high Print-resistant solid resin plate. During the resin plate making process, problems such as small characters or small dots falling off and fine lines bending are prone to occur. The solid plate has uneven layout, uneven inking, and spots. It is also difficult to screen a resin plate with a screen of more than 90 lines/inch. Observe the drawbacks of dot size. The above problems are related to the exposure time of the resin plate during the plate making process, the low contrast of the positive negative image, the fog in the light-transmitting part, the unevenness of the resin plate, and the coloration of the surface. The causes and solutions to these problems will be analyzed in detail below. Small text, lines, and dots are lost. The bending of fine lines and the loss of small text and dots may be caused by the following reasons: ① Insufficient exposure time of the resin plate; ② The contrast of the film is small, the graphics and text are unclear, and there is gray fog; ③ Thermal curing treatment of the resin plate ( (Drying plate) is not appropriate; ④ The water temperature for developing the resin plate is low and the rinsing time is long; the brush is hard and the printed plate is darker; ⑤ The printing pressure on the machine is high and the adjustment is improper. The solutions are as follows.
① First of all, you must master the correct exposure time. When encountering small words, lines, patterns or small dots, it is better to use a 3kW gallium iodine lamp to expose for about 20 minutes, which is longer than the normal plate exposure time. Such small words and lines It won't fall off. The longer the exposure time, the better the side slope of the resin plate of graphics and text produced, which can reach about 70°. ② You must have a set of excellent darkroom skills. The contrast of the negative film should be as high as possible, without fog, the text and lines should be smooth and smooth, and there should be no shortage of pen breaks, and the exposure, development, fixation time and temperature of the negative film should be well controlled. ③Whether you are using a solid resin plate making machine to automatically brush the plate or manually brushing the plate, the water temperature must not be too low. It is best to rinse at a water temperature of 50 to 60°C until the base is exposed. It is better to choose a brush with soft bristles. When brushing and rinsing, the brush should be shallower, as long as it has a certain depth. In addition, the printing and rinsing time should not be too long. The drying and heat curing process is generally carried out in an electric oven at a temperature of 60 to 80°C to evaporate the moisture on the plate. Be careful to prevent the drying temperature from being too high. The occurrence of resin bubbling on the layout. ④ Without pressure, the ink cannot be transferred to the paper, but the printing force must be moderate. When the resin plate is printed on the machine, the pressure of the inking roller must be adjusted, and the pressure between the resin plate and the impression roller should be as small as possible while ensuring the printing quality to avoid excessive pressure that may cause small text, lines, and graphics to be crushed. If it is dropped or crushed, the printing durability of the resin plate will be weakened. It is best to use a magnetic plate table or aluminum support plate to stick the plate, because its thickness is uniform, the layout is flat, and the pressure adjustment is relatively easy. The flatness of the wooden board is relatively poor, and it is easy to bulge after being put under pressure and expand and deform when exposed to water. The layout is uneven and pasted. Solid plates (text, lines, hollow plates) that are printed with resin plates often encounter problems with uneven layout and pasting. The reasons are multifaceted. The uneven surface is caused by photosensitive adhesive. The reason for uneven film coating is also due to improper process operation. Before the resin plate is exposed, a small amount of talcum powder should be applied to avoid bubbles caused by gaps between the negative and the resin plate. The vacuum pump of the printing machine must be strong in suction, and the surface of the negative film and the photosensitive film of the resin plate must be closely matched, so as to reduce the problem of surface unevenness. When there are patterns and scratches on the resin plate after development, you can also gently rub it with the grinding charcoal originally used to make copper-zinc plates to remove the patterns and scratches and make the surface smoother, so that the resin plate can be inked. It will be more uniform and the effect will be better. When drying solid plates or hollow plates with small text and lines, the exposure time should be reduced accordingly, so as to avoid the problem that the plate cannot be brushed and the rinse is not deep enough when the plate is washed. When designing the hollow text, lines, and patterns on the resin plate, the problem of smearing should be considered. Design the lines and text of the ink draft to be thicker, so as to avoid the problem of excessive ink color and white leakage when the resin plate is printed on the machine. . In addition, when printing the plate, the vacuum pump must inhale properly, the darkroom technology must be excellent, the contrast of the negative plate must be large, clear, clean, and fog-free to ensure that the plate is not smeared and meets the quality requirements of resin plate printing. It is difficult to observe the dots during plate development. Before exposure, the surface of domestic solid resin plates will appear green or antique yellow, with green resin plates being the most common. After exposure, the resin plate turns old yellow, which is the color most difficult for human vision to observe. When printing a 90 lines/inch dot printing plate, it is not easy to observe the size of the dots, which makes it difficult to control the depth and slope of the printing plate and the quality of the screen version. It is best to add some non-toxic, odorless, non-polluting dyes or colorants on the surface of the photosensitive solid resin plate or in the photosensitive film, such as methyl violet and other pigments, with darker colors such as green, red, blue etc. It is better to observe the situation of the dots when making the plate, so as to facilitate the control of the depth and effect of the plate.
Six common faults and troubleshooting of printing resin plate making
In recent years, water-soluble solid photosensitive resin plates have simple plate making process, low cost, no pollution and good ink transfer performance. , high print durability, light plate material, short plate making cycle, and can be matched with computer laser phototypesetting system. It is favored by small and medium-sized printing manufacturers and is gradually replacing zinc plates.
Photosensitive resin plate is a letterpress plate with photosensitive properties made by using synthetic polymer materials as film-forming agents and unsaturated organic compounds as photo-crosslinking agents. Almost all photosensitive resin plates undergo cross-linking reactions between molecules under the irradiation of light (mainly ultraviolet light), thereby forming a certain insoluble relief image. Photosensitive resin plates can be divided into two types: solid type and liquid type in terms of plate making technology.
The solid series of prefabricated plates composed of saturated photosensitive resins are more expensive, but the quality is relatively good, and can be used to produce product packaging, trademark plates, and screen printing plates; the liquid series composed of unsaturated polyester resins are Coated plate (simply put, it is used to prepare photosensitive liquid for base production, and then apply resin, photosensitize and make) is relatively cheap and suitable for rougher text line plates. In the actual plate making process of solid photosensitive resin plates, the following problems often occur. Only by comprehensive analysis, differentiated treatment, and finding out the root causes of the problems can the problems be solved.
1. The text, lines, and patterns on the resin plate are too thin or too small, the small characters and independent points fall off, and the small lines are bent
When making resin plates, thin lines are common Problems such as bending and small text, and independent points falling off.
Main reasons:
l. Insufficient exposure time of the resin plate;
2. The film has low contrast, is foggy and unclear;
< p> 3. Improper baking and thermal curing of the resin plate;4. When brushing the resin plate, the water temperature is low, the rinsing time is long, the bristles are too hard, and the plate is brushed too deep;
5 , The pressure is too high when printing on the machine, and the adjustment is improper.
Solution:
1. When making resin plates, when encountering small text, lines, patterns, and independent points, you must master the correct exposure time. The exposure time of the 3kw gallium iodine lamp is about 20 minutes. The exposure time must be longer than that of the normal version, so that small lines, text, and independent points can stand up and not fall off. Due to the long exposure time, the resin plate produced has a small side slope (about 70°) and a solid base for graphics and text.
2. When baking the resin plate, drying and heat curing, the oven temperature is generally controlled between 60 and 80°C in order to evaporate the water on the plate; the drying temperature is too high, The resin version is prone to blistering.
3. The operator is required to have excellent darkroom skills. The contrast of the film processing should be as good as possible, without fog, the text and lines should be smooth and clean, and there should be no lack of pen breaks.
4. When making solid resin plates, whether it is automatically brushed by a plate-making machine or manually brushed with a brush, the water temperature should be controlled at 50-60°C and rinsed until the base is exposed. When brushing a resin plate, you need to rotate the brush. When brushing the plate on one side, it is easy to brush the side and slope, causing small lines to bend and fall off. When brushing the plate, you should choose a brush with soft and suitable bristles. If the bristles are hard, it will cause Small text will be damaged when brushed off; when brushing a resin plate, pay attention to the brushing depth. It is not necessary to rinse the plate until the base is exposed. Brushing the plate too deep will easily cause the words, lines, and patterns on the plate to be brushed away. In addition, pay attention to brushing. Do not rinse the plate for too long.
5. When the resin plate is put on the machine for printing, it is necessary to adjust the pressure between the inking roller and the resin plate, and the resin plate and the impression cylinder. Adjusting the printing pressure of the resin plate is better than adjusting the copper-zinc plate. , the pressure of printing movable type is smaller.
Prevent the inking roller and impression roller from crushing the fine text lines of the resin plate due to excessive pressure, affecting its print durability.
2. Text and line plates are blurred when making resin plates
Main reasons:
1. Overexposure;
2. Vacuum adsorption is not accurate when drying;
3. The contrast of the film is small and unclear.
Solution:
1. Master the exact exposure time of the resin plate. Especially hollow text and lines are most likely to be blurred. When designing, make the graphics and text as bold as possible.
2. The air intake of the printing machine must be firm. If the air is not properly sucked, there will be a gap between the resin plate and the film, and ultraviolet rays will enter from all sides, causing photosensitive plates to be pasted.
3. Before printing, you must carefully check whether the apricot film is pasted or not. Only by having good light transmittance, good contrast and clarity can you meet the needs of plate making quality.
3. The resin plate cannot be washed away
Main reasons:
l. The resin plate has exceeded the shelf life, or has been left unproduced, stored or transported. Light leaked during the process, and the resin plate was photohardened;
2. The water temperature was too low when washing and brushing the plate;
3. The film was not processed well in the darkroom, and the film had poor light shielding and low density.
Solution:
1. The shelf life of the resin plate is about half a piece. Printing manufacturers should purchase according to the production capacity and usage of the factory. Do not blindly purchase excessive amounts, otherwise it will cause the expiration date. Invalid.
2. Resin plates are photosensitive materials, and they are most afraid of light leakage during production, storage, and transportation. When storing resin plates, temporarily unused plates should be placed in a sealed box and sealed in a black plastic bag; resin plates should be stored in a dry, moisture-proof place.
3. When printing, the water humidity should be controlled at around 60-70℃. If the water temperature is too low, it will affect the dissolution of the non-photosensitive resin film when it encounters water; if the water temperature is too high, the dissolution will be accelerated.
4. Patterns or scratches appear on the resin plate
Main reasons:
1. A small amount of talcum powder is not applied to the resin plate between exposures , corn starch, resulting in loose contact between the film and the resin plate, resulting in air bubbles;
2. The vacuum pump of the printing machine does not suck air properly;
3. The film is not transparent The side is not smooth and has gray fog.
Solution:
1. Apply a small amount of talcum powder and cornstarch on the surface of the resin plate. The purpose is to prevent the resin on the plate from adhering to the film and causing incorrect air intake. A small amount of fine particulate matter attached to the resin plate can solve this problem.
2. After the plate printing machine has been used for a period of time, it must be repaired in time, add vacuum oil, and clean the dust and paper fluff in the wall of the suction rubber tube. The air suction volume of the vacuum pump is generally 30-40m3/ h.
3. The light transmittance of the negative film should be good, pay attention to the exposure and development time, and fix and wash thoroughly to ensure that the negative film does not have fog or yellowing.
5. The resin plate is curled and cracked
Main reasons:
1. Drying and heat curing time is too long;
2. Excessive post-exposure (fill light);
3. The plate is expired or has quality problems.
Solution:
1. The drying and heat curing time of the resin plate cannot be too long. As long as the layout is dry and the curved lines straighten.
2. Post-exposure (fill light) is carried out after drying and heat curing. Do not use excessive fill light, otherwise the resin will easily become hard and brittle. Just see the layout change from green to light red and then to antique yellow. If the plate is seriously curled, soak it in water for 5-10 minutes and then dry it again.
3. When using plates, be sure to recognize the production date. Expired and deteriorated plates are prone to curling and should not be reused.
6. The printed images and text are incomplete
Main reasons:
1. The glass plate of the plate maker is seriously dirty;
2. When tracing ink on the negative plate, the picture and text part of the negative was stained, and the red tear-off film fragments from the imposition fell onto the negative;
3. When brushing the plate, the force was too strong and the bristles were too hard.
Solutions:
1. Develop good working habits of civilized and safe production. Before printing, clean the dust, oil, ink spots, paper scraps and other dirt inside and outside the glass plate of the printing machine with water or cotton wool dipped in alcohol.
2. When tracing ink on the negative, be careful not to cover the graphics and text. Only after the ink is dry can you print the plate. Use imposition red tear-off film to cover the layout to prevent fragments from falling off and blocking the graphics and text. Resulting in incomplete pictures and text.
3. When brushing the resin plate, the force should be even, heavy first and then light; the bristles should not be too hard. At the same time, it is also necessary to prevent hard objects from scratching the layout and causing damage.