The performance of flexo printing art

A·The definition of flexographic printing

Flexographic printing, also known as "FLEXO PRINTING", generally refers to a rubber or plastic relief that is higher than the non-printing part of the printing section, so that when the printing plate is to be printed material (sheet or reel material) For portrait printing. It is a rotary printing method using aqueous or solvent-based thin liquid inks, and is generally used for printing on a web substrate, the only exception being printing on corrugated cardboard. Flexible letterpress printing is developed by using a hard relief printing plate made of metal or plastic, and a thick and thick printing ink. In addition, when the printing length is changed in the rotary relief printing method or the rotary lithographic printing method, the complex combination of the ink printing and inking devices is extremely difficult to correspond to, and thus it is only suitable for printing with a fixed length (diameter). Flexible flexo printing does not distort the flexible printing plate. It is only appropriate to use slight printing pressure. However, the letterpress printing method uses strong pressure printing, which is the same as letterpress printing, but it cannot be confused. The composition of ink is also different depending on the printing pressure. The only common point in the two printing methods is that both sides use convex plates.

The flexographic letter also undergoes transformation under a little pressure, resulting in the coarsening of the line drawing and the enlargement of the dot. The periphery of the line drawing generates a shadow, which deteriorates the printing quality. Large-scale roll-type flexographic plates are difficult to cast and form, and many small plates are attached to the plate cylinder with double-sided adhesive tape. The flexible letterpress printing method was a method invented in the 1890s for printing with kraft paper in a stamping manner that can change the length of the reversal. The use of extremely low viscosity liquid ink eliminates the need for complicated ink printing devices such as letterpress printing. With the use of a rubber plate, printing can be done at a much cheaper cost than a gravure plate cylinder, and with the use of liquid ink, an ink plate and an ink tank are used to supply an excess amount of ink to a variable flow rate pump, and the ink overflows again. Can be returned to the ink tank for reuse. The ink roller feeds ink to the ANILOX ROLLER to supply a certain amount of ink to the plate. The amount of ink can be determined by the roller pressure, hardness, and speed difference. The amount of ink on the printing plate is determined by the size, number of lines and shape of the recesses of the plate roller, and the quality of the printing on the web material is determined by the size of the press plate as in the letterpress printing plate. The diameter of the printing plate and the thickness of the sticker should be subtracted from the printing diameter and then machined and chrome plated.

The rubber plate is cast to a special thickness, and its representative plate height, including double-sided tape, is 1.7 to 7 M/M, etc., respectively, and various thicknesses of the photosensitive resin plate are now used. For example, a plate with a reversal length of 500 M/M has a diameter of 159.3 M/M. If the printing machine uses a printing plate of 3.175 M/M, the diameter of this plate is twice the thickness of the printing plate as the printing diameter becomes 152.78 M/M. In flexographic printing, the diameter of the printing plate can be easily changed. However, due to the relationship of gear transmission, the printing length cannot be freely changed like a gravure printing, and can only be changed in an integral multiple of the number of gear teeth. This is the printed length of the flexographic letter, the only restriction.

Birth of B.Aniline printing

The history of flexographic letterpress printing is actually a history of successive letterpress printing methods. Flexographic letterpress printing is the only major printing method invented in response to the needs of processing and packaging. The manufacturer of paper developed this printing method, originally named "ANILIN" and printed in 1952. It was formally named "Soft Technology" and printed "Flexible Letterpress." Initially, Anilin printed inks using aqueous liquid inks and later solvent-type Anilin dye inks, making the flexographic printing method fully successful. Anilin Ink was developed by the Germans after printing machines and printing methods were invented by French and Americans.

The flexible letterpress printing method was obtained by the American "Kingsley" in 1853 and obtained a patent for a flexographic printing plate. In 1860, it also obtained a patent for a flexographic printing press. From the beginning, his statement was circulated for a long time, but suffered from In the absence of evidence of prints, after Barron & Sons of the United Kingdom obtained a British patent in 1890, the completion of a rubber-plate web press was exact. This patent used extremely low-viscosity ink and a soft rubber plate. The new printing method has been just over 100 years old. The ink is formed from dyes, glucose and water. The printing machine is characterized by the use of soft plates and liquid (aqueous) inks.

The secret ratio of <BIBBY> and Barron's wants to print on kraft paper bags, but there are various sizes of paper bags and it is necessary to change the length of the printing. Only gravure printing can achieve this purpose at the time. The gravure was developed in 1877, and after 50 years (until the I930s) after the gravure printing was completed by Criecher, the gravure printing was still considered a practical printing method for packaging materials.

The liquid ink does not adhere to the metal surface, and the ink cannot be evenly applied to the metal relief. The thick ink is used. The ink of the flat ink needs to use a very viscous ink to make it water-repellent. Therefore, both inks are paste-like. Ink, and limited to a certain printing length of the cylinder printing. In order to change the gantry, there are many ink rollers that take time and effort to replace. Currently, there is a changeable cylinder size and lack of web offset printers, but changing the print length is time-consuming and impractical. If low-viscosity inks are used, only one or two ink rollers can be used to fully wet the printing ink on the printing plate, eliminating the need to use complicated ink supply systems for printing. This enables the use of printing machines of various sizes. . The successful development of the gravure printing machine proved the practicality of using liquid ink to print various lengths of prints.

This led to the motivation of Miriam and Barron to develop a new printing press. The use of new low-viscosity inks can control the transverse effect of printing ink homogenization. It can also eliminate the use of sealed ink tanks and doctor blade adjustment devices, and also because of the use of The soft rubber plate can also eliminate the lengthy preparations for letterpress printing. The error of the metal plate is not easy to control within +25u. The main reason for the change in printing quality is the height of the printing plate. It takes time to remedy the tube lining. Flexibility of the flexo plate can eliminate this adjustment. In order to make a rubber-engraved plate, a mother-type plate is used. Since the plate produced has flexibility, it is much easier than the bending plate-making of a metal plate or an electroplated plate.

The earliest rotary flexographic printing machine that was originally printed with an Anilin ink (coal, dye and solvent mixture) was a product of HOWEG in 1905. Although there was no drying device at the time, the above quick-drying printing was used. Ink has made flexographic printing a success.

C· Flexible Letterpress Art View

In the initial period, the ink roller of the Anilin printing machine could easily generate excessive droplets under the transfer roller, and the wetting angle of the ink roller should be increased. Therefore, slow-drying ink should be used to keep the transfer roller and the plate cylinder. The ink on the slow drying, the recent design of the ink roller has moved to a more horizontal position, so the ink droplets and wet corners of the problem is also resolved. The ink roller revolves at a low speed according to the reel, but when the machine changes from the normal slow speed to the high-speed rotation, serious ink scattering is generated. Later, the rubber transfer roller is changed to a metal roller, and not only the wettability of the printing plate can be improved, but also feasible. Higher speed printing. If you keep the slow roll between the two rollers, you can eliminate bubbles, droplets and other phenomena. The ink metering method has also been greatly improved, so the double roller gap transfer method, which follows the squeegee roller and the chrome roller, continues to be used. In later flexographic printing devices, the use of a grained transfer roller called a grain roll used to quantify the ink in a twin-roll press, while the color printing on precision dots also used a doctor blade system (even two The reverse squeegee system tightly controls the amount of ink on the roll to distribute the more accurate amount of ink given to the printing plate baffle point, and lightly presses it to accurately transfer onto the material to be printed.

The new rubber plate grinder in the printing plate can reduce the height error to less than 25u so that the squeeze amount of the plate becomes 70-75u, so the deformation of the plate is also relatively reduced. The height error of the new photosensitive resin printing plate is only 13u. If this kind of plate material is used, it is also possible to print a high number of lines. This high-precision printing makes the amount of extrusion less and the amount of deformation smaller. Now.

In the past, flexographic printing was limited to 0.4 lines/inch (<39 lines/cm) with 0.4 M/M thin lines. In the 1970s, Dow Chemical completed the glass plate casting method and opened the line for finer line drawing. Number of outlets plate the road. In the 1980s, each photosensitive resin plate manufacturer introduced a very high-quality flexographic printing plate, and it was able to make a mesh size of 133 lines/inch. By the late 1980s, it was possible to print 150-175 lines/inch of color dots. The printing effect goes directly to color gravure printing.

The development and application of photosensitive resin plate can be said to be the hero of flexible flexo printing. The resin plate is a material that uses a photosensitive resin material to form a polymerization (hardening) under the irradiation of a high-intensity light source (ultraviolet rays). This type of plate is used three times. Yuanzhi soft printing plate can be directly from the original plate → plate → casting, directly from the printing plate manuscript → printing → washed out → printing plate, divided into liquid and solid two plates. Photoresist has the following advantages:

1 · Scalability P1 plate is directly plated by the printing plate (negative film), no intermediate process will not interfere with the shrinkage error of the intermediate process (mother plate and welding error), the other substrate is also relatively stable, and a project It is also easier to predict and control the amount of expansion and contraction.

2. Thickness of printing plate A photosensitive resin plate can control the plate thickness and precision within about 12u. Therefore, it can make the printing pressure lower than that of the casting rubber plate to print a comparatively fine picture.

3. Finer Detailing A castable rubber plate can not be sharply angled because it is to be pulled out of the mold plate. However, the photosensitive resin plate does not use a pattern plate, so it can be used for sharpness and detail at a sharper angle. The formation of portraits.

The ink printing system also changed from a two-roller ink containing absorption to a metal roller and then to a doctor-to-ink system. The latest type is the precise and strict control of the ink by the reverse double doctor blade. Ink volume. Due to the above improvements, the quality of the flexographic printing of line portraits and dot prints today can be as long as the gravure and lithography. Some people think that the highest-quality dot-prints printed by flexographic printing are still not comparable to plain-printing and gravure printing, but the quality of flexographic printing has greatly improved, but it is an indisputable fact. As long as you go to European and American supermarkets, you will find that many people who used lithographic and gravure printing in the past have already become flexible flexo printing. For example, the flexible embossed opaque LDPE freezer bag replaced the gravure bag and the lithographically printed cardboard box. The future of flexographic printing is obviously limitless. $Page break $

D. Technical View of Flexible Letterpress

If we take the advancement of flexographic printing in software and hardware other than printing machinery as the artistic view of flexographic letterpress printing, then the flexographic letterpress printing press that acts as the protagonist of the revolutionary development of flexographic letterpress cannot but study the technical aspects.

The structure of the flexographic printing press can be divided into three types: STACK TYPE, COMMON IMPRESSION TYPE, and IN-LINE TYPE. On line printing. The initial Alinlin printing press was mostly used on-line, and later it changed to a stacking type and a common pressure barrel type (also called C·I type for short) due to tension and alignment problems. There are six main factors for selecting the type of printing press: 1. Type of substrate to be printed 2. Printing volume 3. Color gauge accuracy 4. Applicability 5. On-line processing volume 6. Purchaser preference. Most of the printer purchasers use the above six factors as the basis for selecting the type of press. Of the Anilin presses made before World War II, 95% were stacked, and 5% were common cylinders or on-line types. After the World War II, the introduction of plastic film packaging and printing and the improvement of the share of the design of the common cylinder flexo printing press have greatly changed. At present, most of reel type flexographic printing presses are of the common press barrel type, but this is not the most excellent one. There are also a large number of deposition type printing presses, which are more versatile than the other methods. The comprehensive ability of application and printing processing is the same as that of the letterpress machine, and it is the most convenient type for printing and processing integrated production.

The Ainlin printing machine at the beginning is a single-type, continuous or horizontal flexible letterpress printing machine that adds sequential arrangement of printing units. Currently, such printers are used only for the printing of low-stretch and high-strength thick film substrates. The original online flexographic printing press had a major problem, this and the printing unit