Various phenomena and effects of air cushion blanket
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The Chinese printing industry has long referred to lithographic printing as "offset printing". In fact, the lithographic printing press is an "indirect printing" method. After the printing plate is printed, it is not directly transferred to the paper to transfer ink printing. The rubber blanket is mounted on the rubber ★ cylinder as the medium for transferring the printing ink in the middle, picking up the printing ink on the printing plate, and then transferring (writing) on the printed paper medium, so the blanket is The lithographic printing machine plays an extremely important role, and therefore does not call the layout a "lithographic version", but renames it the indirect printed blanket medium and calls it "offset printing", but there are very few letterpress printings that must be indirectly printed on the hard material surface. It is not known whether a blanket is used to transfer the transfer pattern or not.
Before the 1960s, all blankets were made of natural rubber as the material to carry the printed transfer blanket surface. However, after the 1950s, the natural vegetable linseed oil was replaced by petrochemical mordant ink, and the original natural rubber was obviously not resistant. Living in petrochemical solvents and resin intrusion, resulting in abnormal swelling and bulging, so in the 1960s, the surface of the blanket, the use of synthetic rubber, the material of the ink roller and water roller also changed to synthetic rubber, DuPont invested more than one billion dollars The completion of synthetic rubber research, only after more than a decade after the Second World War. However, the blankets so far are all solid, and there is no structure in which the bubble sponge is compressed, and the pressure generated by the bubble is rapidly increased due to the high speed of the printer. At that time, there was a very different theory. The earliest one thought that the plate and the pressure ★ tube (plus the printing paper) were all hard, so the surface of the rubber tube should be raised so that the diameter is larger than two hard diameters. Only then can the "same diameter" be in operation, but in 1937, Miller Miller Printing Company of the United States found that the length of the winding of the hardware ★ barrel embossing is a fixed length of diameter × π, but the soft surface of the rubber tube is rolled one. The circle is equal to the diameter × π plus the elasticity and pressure coefficient, which means that even if the rubber tube is at the same diameter, and the plate cylinder and the pressure cylinder are embossed with each other, the rotation length is greater than two hard ★ cylinders, and the cylinder diameter method is intentional. Increase the compression of the rubber tube, so the rubber ★ tube walks long and runs fast, so the blanket and the printing plate produce unnecessary friction, so the plate is replaced. ★ The tube pad is higher than the gear section 0.1~ 0.15mm, and the rubber tube is placed at the same height as the circumference of the blanket to maintain the same speed of surface imprinting and printing ink transfer during imprinting. This is called the "rolling length method". Always used until todayBut at the time, it was also found that the rubber on the rubber tube was raised forward and backward to offset the pressure when the plate was pressed. This "flange" effect is like the rubber roller. A wire tightening wire will surely fall into the rubber, and the trapped rubber will bulge on both sides. This effect is the same as the "flange" produced by the pressure mentioned above.
In order to solve the problem that the prints and dots generated by the "flange" sometimes have drag marks and shadows, the rubber factory manufactures a blanket with four layers of interwoven textile yarn layers under the blanket surface, in the second Between the three layers, a layer of bubble sponge is sandwiched like a sandwich, and the hardness of the surface rubber layer is slightly increased to compensate for the softening depression of the sponge layer, but this sponge layer is independent of each bubble. In order to have greater compression support, and to provide better rebound strength when decompressing. If the bubble holes are connected by the through-phase, then the sponge layer is overflowed by the pressurized air, and the support force is also weak after the decompression, and only the elastic force of the rubber structure is weakly rebounding. Therefore, it is very important to close the layer of sponge bubbles that are not connected in series to provide support and recovery. Then this layer has an average of 0.4mm sponge cushion layer, which provides the blanket to directly press the sponge air cushion layer under the pressure of printing, and it does not need to move forward and backward to produce a "flange". , causing unnecessary creep, avoiding the phenomenon that the printed print quality has a smear to the shadow. At the same time, because the compression does not have the elastic body rolling length, the blanket height of the blanket is also raised to maintain the concept of the same diameter method. In turn, under the extra elasticity provided by the air cushion blanket, it is impossible to make the traditional blanket completely inelastic. Only the plastic sheet or the hard lining paper under the blanket is called the “hard padding” effect, because the air cushion The layer has provided additional flexibility.
Later, some manufacturers moved the sponge layer of the air cushion blanket down one layer, close to the way between the third and fourth layers of the tube body, and also moved up the air cushion layer under the rubber surface layer and directly attached to the blanket. Below the surface layer, it provides greater elasticity of absorption pressure. However, before and after 2005, an "ultra-thick air cushion blanket" was developed, which increased the bubble pressure of the printing pressure from 0.4 mm to 0.8 to 1.4 mm, especially the blanket with a total thickness of 2.4 mm. In order to accommodate the 1.4mm bubble sponge layer, it can greatly reduce the printing pressure, and at the same time increase the printing plate and the rubber tube, and even the rubber ★ tube and paper contact and transfer ink time. But it does not produce excessive pressure peaks, meaning that the contact of the entire contact is widened, but the pressure is smaller and smoother. It has little effect on the fan-shaped effect of the tail of the mainframe printing paper, and there is no benefit of inaccurate paper-overprinting. Otherwise, like a large flat printing machine with a width of 1450mm or more, the printing paper is pressed, especially after the pressure of 80g/m2 or less, the paper tail is stretched, which is 1.6 and 1.7 times larger than 1000mm. Unable to register and have good dot reproduction.
In addition, in the printing of corrugated paper, if the elasticity of the blanket is insufficient, the corrugated strips of the "rib liner" are produced under the blanket printing, and the pressure of the peak of the corrugated peak is large, and even the peak of the corrugated corrugated collapses, and vice versa. The peak supports the central paper hanging underneath, but because the blanket is not soft enough, the tenter pressure is not long enough, and the strip-shaped "ribs" is more obvious when the print is not transferred enough. Therefore, the production of the ultra-thick air cushion blanket is a giant flat. The printing machine, as well as the corrugated paper developed more evenly under pressure.