In China, most corrugated paper box manufacturers still use a large number of hand-engraved rubber plates to print. With the development of market economy, the competition in the corrugated box industry has become increasingly fierce. People have higher and higher requirements for corrugated boxes as hand-carved. Rubber plate printing has been far from meeting the needs. In order to enhance the competitiveness of enterprises, shorten the delivery time, provide high-quality corrugated boxes, many corrugated box companies have launched flexible photosensitive plate-making equipment, in order to remain invincible in the fierce market competition.
The flexible photosensitive resin plate is composed of a polyester support film photosensitive resin layer and a protective layer. Compared with the traditional rubber plate, the photosensitive resin plate has many advantages: Fast plate making speed. It can effectively save plate-making time and increase production efficiency.
The reproducibility of the design draft is good, and it is possible to produce a gradation version and a color edition, and get a clearer pattern effect than the rubber edition.
Printing size stability is good. The photosensitive resin plate can be firmly attached to the polyester support film, ensuring dimensional stability and obtaining a very stable printing overprint. The dimensional deformation of the rubber plate has been plaguing the printer.
Thickness of plate. Uniform pressure on the web of the sheet ensures optimum printing quality without the need for flattening and can accurately set printing pressure to produce high-quality corrugated boxes.
High print rate. Can be printed for a long time, with less reproduction rate and downtime. Although the carton paper is rough, the imprinting rate is as high as 500,000, which is 3 to 5 times higher than the rubber plate.
The use of resin plates for high-quality prints requires excellent design and high-quality negatives. Good design drafts are fundamental to high-quality flexible prints to ensure good reproducibility. Design should pay attention to:
1. If photoengraving is used, all lines and text in the produced ink draft must have the same ink level, otherwise it will lead to unnecessary photo correction and manual modification to produce a satisfactory negative film.
2. In the case of satisfying customer requirements, try to make the Yang strokes smaller and the Yin strokes thicker, which increases the spacing between strokes and does not easily result in print stencils.
3. Avoid dots and large areas of color pattern printing on the same block as much as possible. If the large-area color pattern and thin line pattern are separately printed separately, pressure adjustment and needle control are much simpler.
4. If another color is overprinted within a color, and no gaps are required between the colors, the accuracy of the company's printing press must be taken into account when designing, so that the layout of the two colors is superimposed and the width of the overlapping portion is the printing machine's Printing deviation.
5. The design draft must take into account the extension of the resin version. During plate making, the plate does not shrink or elongate. When the plate is mounted on a plate roller, the direction plate of the plate roller will extend, and the resin plate elongation can be calculated:
Elongation of resin plate = (plate roller + double-sided tape thickness ÷ (plate roller + double-sided tape thickness + thickness of resin plate) × 10%
The actual size required at design time multiplied by the extension of the resin version is the size of the design draft.
High-quality negatives are critical to the production of resin plates, and the negatives used must be carefully examined:
1. Transmissive area density should be less than 0.05. This can ensure that the negative film meets the platemaking requirements. There are strong subtle patterns and a clear overcast 2. The density of the opaque areas is greater than 4.0. Too low a density will cause the pattern not to be deep enough or Unexpected patterns appear.
3. The negative film must have the correct pattern direction, that is, when the film is upright, it is a positive image. This is very important. This can ensure that the negative film is in good contact with the surface of the plate when the plate is made. 4. The negative film should be clean, free from blemishes and wrinkles. The wrinkles of the negative pattern part will be reflected on the plate, and holding the negative film in the diagonal direction can reduce the occurrence of wrinkles. After the design draft or photographed into a negative film, it can be plate-making, which is mainly divided into six steps: back exposure, main exposure, rinse, drying, de-bonding and post-processing. In the actual operation, special attention should be paid to the following issues:
1. In order to obtain a high-quality resin plate, when using each new type of plate material, each new lot number material, after replacing the new exposure light tube or light pipe for 20 hours, the back exposure time must be re-determined. . The back exposure time can be determined by a back exposure test, and a backing layer can be used to create a base layer for the desired relief and adhesion of the reinforcing polyester support film and the photosensitive resin layer. The correct back exposure is exposed from the direction of the polyester support film, which protects the pattern's fine pattern during the rinsing process and prevents the relief from collapsing.
2. The main exposure should be performed immediately after back exposure, because the photographic activity will gradually disappear, resulting in a longer main exposure time and poorer exposure latitude 3. When the guaranteed layer of the resin plate is peeled off, the photosensitive speed of the printing plate is rapidly increased. To attenuate, the negative should be immediately placed on the plate or the main exposure must be performed within 10 minutes for best results.
4. The main exposure time can be determined by the main exposure test. After one month or after the replacement of the light pipe, a main exposure test is performed. The main exposure is used to create a printing pattern through a negative film. The photosensitive resin becomes insoluble through the polymerization reaction. The printing plate can Reproduces the subtle pattern on the negative film. Before the main exposure is performed, wipe the vacuum film to discharge the air so that the plate and the negative film are in close contact.
5. The plate must be dry, otherwise it will affect the plate thickness uniformity, after drying, do not let the plate surface contact with other objects surface, do not touch the printed surface with your fingers, otherwise it will leave traces. Before removing the glue, be sure to remove any spots on the surface of the plate. After tacking, the remaining spots on the back of the resin plate are cleaned. If these are not cleaned, the plate thickness uniformity and adhesion of the plate adhesive tape will be affected.
When making a resin plate, it often happens that the thin lines are washed out or the negative part is embossed lighter. Special techniques are needed to achieve the desired effect:
1. Use "separate back exposure" process. The corrugated paper box industry generally adopts a 3.94mm thick flexible resin plate with a depth of 1.52 to 2.00mm. The base layer is thin, and the very fine parts of the printed pattern cannot withstand the conventional exposure. At this time, it is necessary to use " Separation back exposure" process. First, confirm the very thin line points and text areas in the negative film, use the mask to cut out an area outline template, first create all the base layers for the back exposure of the plate, and then accurately position the mask on the surface of the polyester support film according to the negative film instructions. Back exposure is performed to create the base layer for the desired area, and the two back exposure times are determined based on the desired base layer thickness.
2. Use the "main exposure mask" process. If the design draft contains thin line text and negative images that are easy to paste, the masking process can be used to achieve the desired effect. The mask must be made of materials that are not UV permeable. First, the plate is exposed with a shorter main exposure time, which can ensure the depth of the negative, and then the mask is partially covered with a mask to additionally expose the thin lines.
(Text: Li Yutian)
The flexible photosensitive resin plate is composed of a polyester support film photosensitive resin layer and a protective layer. Compared with the traditional rubber plate, the photosensitive resin plate has many advantages: Fast plate making speed. It can effectively save plate-making time and increase production efficiency.
The reproducibility of the design draft is good, and it is possible to produce a gradation version and a color edition, and get a clearer pattern effect than the rubber edition.
Printing size stability is good. The photosensitive resin plate can be firmly attached to the polyester support film, ensuring dimensional stability and obtaining a very stable printing overprint. The dimensional deformation of the rubber plate has been plaguing the printer.
Thickness of plate. Uniform pressure on the web of the sheet ensures optimum printing quality without the need for flattening and can accurately set printing pressure to produce high-quality corrugated boxes.
High print rate. Can be printed for a long time, with less reproduction rate and downtime. Although the carton paper is rough, the imprinting rate is as high as 500,000, which is 3 to 5 times higher than the rubber plate.
The use of resin plates for high-quality prints requires excellent design and high-quality negatives. Good design drafts are fundamental to high-quality flexible prints to ensure good reproducibility. Design should pay attention to:
1. If photoengraving is used, all lines and text in the produced ink draft must have the same ink level, otherwise it will lead to unnecessary photo correction and manual modification to produce a satisfactory negative film.
2. In the case of satisfying customer requirements, try to make the Yang strokes smaller and the Yin strokes thicker, which increases the spacing between strokes and does not easily result in print stencils.
3. Avoid dots and large areas of color pattern printing on the same block as much as possible. If the large-area color pattern and thin line pattern are separately printed separately, pressure adjustment and needle control are much simpler.
4. If another color is overprinted within a color, and no gaps are required between the colors, the accuracy of the company's printing press must be taken into account when designing, so that the layout of the two colors is superimposed and the width of the overlapping portion is the printing machine's Printing deviation.
5. The design draft must take into account the extension of the resin version. During plate making, the plate does not shrink or elongate. When the plate is mounted on a plate roller, the direction plate of the plate roller will extend, and the resin plate elongation can be calculated:
Elongation of resin plate = (plate roller + double-sided tape thickness ÷ (plate roller + double-sided tape thickness + thickness of resin plate) × 10%
The actual size required at design time multiplied by the extension of the resin version is the size of the design draft.
High-quality negatives are critical to the production of resin plates, and the negatives used must be carefully examined:
1. Transmissive area density should be less than 0.05. This can ensure that the negative film meets the platemaking requirements. There are strong subtle patterns and a clear overcast 2. The density of the opaque areas is greater than 4.0. Too low a density will cause the pattern not to be deep enough or Unexpected patterns appear.
3. The negative film must have the correct pattern direction, that is, when the film is upright, it is a positive image. This is very important. This can ensure that the negative film is in good contact with the surface of the plate when the plate is made. 4. The negative film should be clean, free from blemishes and wrinkles. The wrinkles of the negative pattern part will be reflected on the plate, and holding the negative film in the diagonal direction can reduce the occurrence of wrinkles. After the design draft or photographed into a negative film, it can be plate-making, which is mainly divided into six steps: back exposure, main exposure, rinse, drying, de-bonding and post-processing. In the actual operation, special attention should be paid to the following issues:
1. In order to obtain a high-quality resin plate, when using each new type of plate material, each new lot number material, after replacing the new exposure light tube or light pipe for 20 hours, the back exposure time must be re-determined. . The back exposure time can be determined by a back exposure test, and a backing layer can be used to create a base layer for the desired relief and adhesion of the reinforcing polyester support film and the photosensitive resin layer. The correct back exposure is exposed from the direction of the polyester support film, which protects the pattern's fine pattern during the rinsing process and prevents the relief from collapsing.
2. The main exposure should be performed immediately after back exposure, because the photographic activity will gradually disappear, resulting in a longer main exposure time and poorer exposure latitude 3. When the guaranteed layer of the resin plate is peeled off, the photosensitive speed of the printing plate is rapidly increased. To attenuate, the negative should be immediately placed on the plate or the main exposure must be performed within 10 minutes for best results.
4. The main exposure time can be determined by the main exposure test. After one month or after the replacement of the light pipe, a main exposure test is performed. The main exposure is used to create a printing pattern through a negative film. The photosensitive resin becomes insoluble through the polymerization reaction. The printing plate can Reproduces the subtle pattern on the negative film. Before the main exposure is performed, wipe the vacuum film to discharge the air so that the plate and the negative film are in close contact.
5. The plate must be dry, otherwise it will affect the plate thickness uniformity, after drying, do not let the plate surface contact with other objects surface, do not touch the printed surface with your fingers, otherwise it will leave traces. Before removing the glue, be sure to remove any spots on the surface of the plate. After tacking, the remaining spots on the back of the resin plate are cleaned. If these are not cleaned, the plate thickness uniformity and adhesion of the plate adhesive tape will be affected.
When making a resin plate, it often happens that the thin lines are washed out or the negative part is embossed lighter. Special techniques are needed to achieve the desired effect:
1. Use "separate back exposure" process. The corrugated paper box industry generally adopts a 3.94mm thick flexible resin plate with a depth of 1.52 to 2.00mm. The base layer is thin, and the very fine parts of the printed pattern cannot withstand the conventional exposure. At this time, it is necessary to use " Separation back exposure" process. First, confirm the very thin line points and text areas in the negative film, use the mask to cut out an area outline template, first create all the base layers for the back exposure of the plate, and then accurately position the mask on the surface of the polyester support film according to the negative film instructions. Back exposure is performed to create the base layer for the desired area, and the two back exposure times are determined based on the desired base layer thickness.
2. Use the "main exposure mask" process. If the design draft contains thin line text and negative images that are easy to paste, the masking process can be used to achieve the desired effect. The mask must be made of materials that are not UV permeable. First, the plate is exposed with a shorter main exposure time, which can ensure the depth of the negative, and then the mask is partially covered with a mask to additionally expose the thin lines.
(Text: Li Yutian)