The use and maintenance of blanket

Offset printing relies on the transfer of blanket printing and graphic printing. The quality of the blanket will directly affect the quality of the printed matter. However, a good rubber warehouse cloth, due to improper use, will not only affect the life of the rubber belt, but also can not print a good product, the actual work due to the negligence of the operation of the soil, so that the ink knife, thickness gauge steel sheet Hard objects such as coins, tools, etc., or multiple sheets of paper jam into the printing cylinder, causing the blanket to be severely rolled into depressions, or the blanket's surface layer of nitrile rubber cracked, losing its function of graphic transfer and being scrapped, etc., in daily work. Strict job responsibility system, correct operation of the process, and scientific use of test tools, should do the following.

1. Printing blankets are products of macromolecular compounds. Understanding and mastering certain physical and chemical properties of macromolecules are of great significance for the rational use of blankets; the synthetic rubbers used in blankets are mainly nitrile rubber, neoprene, poly. Sulfur rubber, polyurethane rubber and other components. Synthetic rubber has excellent lipophilic properties, heat resistance, aging resistance, oil resistance, abrasion resistance, corrosion resistance, water resistance, solvent resistance, oxidation resistance, etc. Since the blanket is subject to the penetration of gasoline and kerosene in the printing process, it is subject to pressure. And relative friction, cyclical stretching, extrusion deformation, so that the blanket will lose sulfur, desulfurization and back to stick, deformation and lack of elasticity, which will affect the quality of the graphic dot transfer, in this In this case, you must replace the blanket.

2. In the printing, if the blanket is crushed, it can be repaired by using a blanket cleaning reductant repair and reduction, but severe sag, cracking, sulfur loss, and stickiness can only be replaced.

3. Correctly grasping the cutting blanket and mounting steps is also the basic operation method in printing. Before the blanket is cut, it is necessary to identify the orientation of the blanket. First, tearing by hand, because the blanket is composed of a surface layer of glue and a bottom fabric, and the bottom fabric is also composed of a strong long-staple cotton cloth with radial (straight) and weft (horizontal) The difference between silk, therefore, when used for pulling, when the stretching is more, it is the latitudinal direction, and it is difficult to elongate the radial direction; Secondly, the back of the blanket is seen with the eye, the marking on the bottom fabric will be a red line or green. Line to indicate the radial direction of the blanket.

Because the radial direction after the force is smaller than the weft, so the radial direction must be taken as the force direction of the blanket when cutting, that is to say, the radial direction of the blanket should be wrapped around the roller shell. body. The radial direction of the blanket should be perpendicular to the axis of the drum. On the contrary, if the weft direction of the blanket is used as the direction of force, then the elongation, thickness, and firmness of the blanket will be affected, and even the adhesive layer will fall off and blisters will affect the service life of the blanket. Deformation and other defects that affect quality.

4. When the blanket is trimmed, the four sides should be straightened and the rules must be straightened, and the diagonal lines must be equal. In this way, the blanket can bear the same force on the roller and ensure the product quality. If the cutting is not neat; there is a skew phenomenon, it will make the uneven force of the blanket, in the surface of the blanket out of a road uneven marks, meat clothing is not easy to observe, resulting in the network is not clear, local Dots are elongated and the deformations of the lining material are wrinkled.

5. The mouth and hole of the rubber blanket are punched at both ends respectively. When operating, the blanket is laid flat, and the iron plate sandwiching the blanket is used as a template, and the bite edge or the trailing edge of the blanket is aligned and overlapped. The pen is also circled by the screw on the plywood. It must be turned one by one in order to prevent omission. Then punch out the hole with the punch. The diameter of the punch is the same as the diameter of the screw, and the position of the caliber of the blanket and the iron plywood is on a line. Straight lines, can not have high or low, otherwise it will cause the blanket to be skewed. When installing the iron plate, the fastening pin should be tightened one by one from the middle to the left and right, and the tightness of the pin should be the same.

6. The lining materials (felt, worsted wool, paper, etc.) under the blanket must be narrow so that when the blanket is stretched, the left and right edges of the blanket are tightly wrapped around the surface of the roller so that printing can be prevented. Impurities, oils, dust, paper dust, and water bucket wetting fluid enter the blanket during the process, causing oxidation and rust on the surface of the drum shell, and delamination of the rubber blanket. During the daily operation, care should be taken to avoid contact with the blanket on both sides of the blanket with detergents, wetting fluids, etc. to avoid the above situation. The new blanket has a smooth anti-oxidation film and is removed with pumice powder and gasoline to ensure that the surface of the blanket can have good Adsorption ink properties.

7. Cleaning blankets in daily production should be serious, do not allow ink to remain in the pores of the surface of the blanket, otherwise the oxidized conjunctiva will dry up and make its surface smooth, the composition of offset resin ink will become more and more complex, and it will contain some components of the wetting fluid. Chemical reactions can occur, and a bright film on the surface of the blanket can reduce its ink absorption capacity. This will directly affect the improvement of product quality. It will take a long time to stop in the middle and clean the blanket in time before leaving work.

8. During the storage of the blanket, the blanket should not be exposed to oils, acids, alkalis, salts, chemicals, etc., and no heavy objects should be squeezed to avoid breaking the blanket and destroying its elasticity. The blanket is afraid of light. , Aggressive heat aging, and moist air erosion, these conditions will make the surface of the blanket produce sticky, crust, cracked, hardened, and the bottom fabric rotten bad, so stored in a ventilated and dry place, the indoor temperature of about 29 °C, relative The humidity is preferably around 70%.

9. The viscose of the rubber blanket is mainly poor in oil resistance, and rubber often absorbs oil, dampening fluid, etc. to cause it to expand. Severe stickiness will also cause the printing paper to adhere to the surface of the blanket, which is usually called peeling. This not only affects the quality of the product, but also it is difficult to continue printing. When the felt is sticky, it should be stopped and the blanket should be cleaned in time. Use volatile solvents, such as gasoline, wipe with a dry cloth in time after wiping, so as to minimize contact with the solvent to reduce the expansion, after cleaning the blanket, use talc, sulfur powder to wipe the surface of the blanket, This can only receive a temporary effect. When the blanket becomes sticky, only a new blanket can be replaced.

10. Low-grooved remedy for rubber blankets, due to improper adjustment of paper feeding during offset printing or negligence during operation, it is easy to have thick small pieces of paper, stiff fiber clusters in the paper, and multiple sheets of paper stuffed into the drum. The partial depression and subsidence of the blanket can't be transferred completely due to insufficient printing pressure in the low concave area. For this reason, we must fill in the concave area in time to remedy:

1 generally use the back of the blanket shimming method. In order to prevent the recessed area from being visible after the blanket is removed, marks of the corresponding size of the ballpoint pen should be used on the front surface of the blanket.

2 remove the blanket, according to the mark on the front of the blanket to find the corresponding position on the back to draw the same size of the mark, the mark must be accurate, the choice of thickness and the pressure of the blanket depression at the appropriate degree of paper thickness, Tear or cut into the shape of the same size as the mark. If the thickness of a piece of paper is not enough, use two or three pieces of paste to glue the glue on the back of the backside of the blanket and glue it until the glue is dry. cloth.

3 blanket depression can also be used to clean the reducing agent to restore the rubber blanket, the effect is also more ideal, convenient and practical, with a brush, roller, blanket, reducing agent, wipe the blanket in the inkless area, immediately there will be immediate Effect.