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The Factors That Affect The Ink Roller What Are The Factors That Affect The Wetness Of The Ink Roller? Shenzhen Printing Company Tells You
- May 16, 2018 -

1, the aging of the ink roller rubber layer

      Most of the soft ink rollers are made of rubber material, and the wettability and other properties are basically the same as those of the blanket. Since the diameter of the ink roller is several to several tens of times smaller than the diameter of the plate cylinder, the linear velocity of the contact point between the ink roller and the plate should be kept equal. The angular velocity of the ink roller is several to ten times greater than the angular velocity of the plate cylinder. , so in the high frequency of rolling friction state, the ink roller is easy to heat up, thereby accelerating the thermal aging of the soft ink roller rubber, resulting in surface hardening, cracking, and even falling off into pieces, resulting in decreased lipophilicity, affect the ink Moisturizing. In order to slow the heat aging rate of rubber, the tandem roller in the printing ink inking device is usually equipped with cooling and cooling device. The ink roller that has formed the heat aging layer must be processed before the Shenzhen printing factory can restore the original ink transfer performance of the ink roller.

      In addition, after the metal ions contained in the hole wet liquid are transferred to the surface of the ink roller, the surface of the ink roller tends to “crystallize” and affect the lipophilicity and ink-transferability of the ink roller.

  

2. Ink roller surface contamination

      After the ink roller surface absorbs other impurities, it will reduce the surface free energy of the ink roller, affecting the wettability of the ink to the ink roller and the ink transfer performance of the ink roller. The causes of the ink roller surface contamination are as follows: 1. The ink forms a dry film on the surface of the ink roller and the ink is dried on the ink roller at an early stage to form the ink skin; 2. The paper powder that has fallen off from the paper surface is transmitted to the ink roller. And is adsorbed on the surface of the ink roller; 3, the surface of the ink roller absorbs dust and other impurities in the air. Therefore, Shenzhen Printing Factory shall promptly remove the remaining ink and debris from the ink roller during the printing process. At the end of printing, the ink roller must be cleaned.

      The offset ink roller made of metallic iron has weaker lipophilicity. When the amount of wetting fluid in the printing is large and the ink emulsification is severe, the electrolyte or hydrophilic colloid in the wetting fluid will follow. The wetting liquid is dispersed in the ink by the iron with fine beads, and the hydrophilic film is formed on the ink roller, so that the oleophilic ability is lowered, and the ink is difficult to adhere to the surface of the ink roller. In severe cases, the phenomenon of “deinking” occurs. Physical or chemical methods are used to remove the hydrophilic film layer, and the ink roller can restore the original ink absorption and ink transfer performance.

 

      The method of improving the oleophilic performance of the iron ink roller can be coated with a layer of metallic copper roller on the surface of the iron ink roller. Metal copper roller has better ink transfer performance than iron tandem roller, but because copper is easily oxidized metal, especially in emulsified ink, the droplets of wetting fluid contain oxidant, and the surface of copper roller will be oxidized. CuO (copper oxide) is generated. On the other hand, the soft rubber in the printing machine's inking system slowly desulphurizes in the transfer of ink. The copper quality roller is in contact with it for a long period of time and will generate black streaks on the exposed parts. This is a chemical reaction between copper and sulfur. Cu2S (cuprous sulfide) and CuS (copper sulfide). Copper surfaces covered by CUO, CU2S, and CUS suffer from a decrease in the amount of oil-absorbing liquid, which can easily lead to “deinking” and are usually removed with 10% dilute nitric acid.

      In order to make use of the non-polar properties of synthetic resins, plastics, and other non-polar polymers, and to have good oleophilic properties, a strong, wear-resistant polymer is cast onto the core of a metal ink roller to make a hard adhesive. Roller. Polymer polymer rigid rubber roller, no hydrophilic inorganic salt layer or hydrophilic colloid is deposited on the roller surface, which can avoid the disadvantages of the metal transfer roller, enhance the ink transfer performance, and rarely cause deinking. However, the mechanical strength of this kind of ink roller is not better than that of metal. In use, knocking and ink knife scraping should be avoided. Shenzhen Printing Company learned that, in addition, the polymeric hard ink roller and rubber soft ink roller have weak solvent resistance. When cleaning the ink roller, an appropriate solvent should be selected to make the cleaning agent, otherwise the surface of the ink roller will swell or Dissolved, damaged adhesive layer and damaged ink roller.

3, the impact of temperature

      The temperature change will cause the free surface energy of the ink roller to change, and it will also cause the surface tension of the ink to change. Usually, the temperature increase will cause the surface tension and the surface free energy to decrease. The ink wetability of the ink roller depends on the ink. Surface tension and temperature dependence of the free surface energy of the roller. Second, the increase in temperature will accelerate the aging of the gel roller, resulting in decreased wettability.

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