Analysis of several factors influencing the surfac

2022-07-27
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Analysis of several factors affecting the surface smoothness of printed matter

in the daily production process, various reasons require us to dilute the UV varnish used. Generally, the most economical and convenient method is to directly add non reactive solvents such as A.T industrial ethanol into the UV varnish, and only change the instantaneous viscosity of the UV varnish without changing the inherent components of the UV varnish, so as to improve the fluidity and transfer suitability of the UV varnish, Make the printing surface bright and smooth after the varnish is cured. However, when the ethanol is added in excess, the water contained in the ethanol cannot completely volatilize, and the 7 temperature setting will be generated during the UV curing heating process: press the Λ or Ν key on the temperature controller to generate water mist, which will remain in the UV oil film, affecting the transparency of the UV oil film after curing, and even causing incomplete curing and sticky printing surface

solution: in the production process, the amount of non reactive solvents such as ethanol should be controlled as much as possible, and ethanol with high purity should be selected

uv varnish coating unevenness

uv varnish coating unevenness is also one of the main reasons that affect the surface gloss and brightness of printed matter, and the UV varnish coating effect is directly related to factors such as glazing plate, printing pressure, embossing roller and ink

(1) poor consistency of relief height on the printing plate surface will affect the transfer of varnish, thus affecting the quality of varnish coating

(2) this is not the case in printing. Uneven brush pressure will also affect the transfer of varnish to the substrate, resulting in different thickness of UV varnish transferred to the substrate

(3) the hole of the embossing roller is blocked, which makes the ink storage on the surface of the embossing roller uneven, resulting in the congenital deficiency when the UV varnish is transferred to the surface of the substrate

(4) the rejection or interference between the printing ink and the UV varnish, and too much viscous material on the ink surface, will locally block the transfer of the UV varnish to the substrate surface

solution: select flexible plates with excellent plate base; Pay attention to the effectiveness of developer and; Medium wash quality to ensure consistent relief height on the printing plate surface; Adjust the printing pressure to ensure it is moderate and stable; Thoroughly clean the wrinkle roller to ensure that no foreign matters remain in the hole: use the ink and UV varnish produced by the same manufacturer, and try to avoid adding viscous additives to the ink

improper smoothness of paper surface

rough paper surface directly affects the leveling performance of UV varnish on paper surface. When the paper surface is too rough, the flow speed of UV varnish on the paper surface is slow, and almost all the UV varnish transferred to the paper surface is absorbed by the rough paper, making the film-forming material photosensitive resin in the UV varnish permeate between the fibers. After UV curing, the gloss and brightness of the print surface are not good. In addition, the rough surface of the paper will also affect the reflection, diffraction and interference of UV light, leading to UV light failure and affecting the curing effect

however, the higher the smoothness of the paper surface, the better. Because the paper surface is too smooth and its absorption is too poor, the printing ink can not penetrate effectively on its surface, resulting in the crystallization of the ink on its surface and the formation of a non absorbent surface. When UV glazing is carried out on this surface, the penetrating components in the varnish and the photosensitive resin are retained on the paper surface together, which will make the varnish cure incompletely

solution: select paper with good printability, or pre print diluted white ink on the paper surface to change its surface roughness and delay the absorption rate. In addition, the paper surface printability can be improved by priming with water-based varnish, which can also improve the folding resistance of printed matter

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