影響印刷質量的主要因素
1.堵版。網點堵塞會引起油墨的轉移量下降,印刷品顏色將發生變化。發生堵版時,要用溶劑或專用清洗劑清洗印版,同時針對堵版產生的原因采取相應的措施。
2.印版磨損。印版磨損會使網點變小、變淺,從而影響了網點的載墨量。印版磨損的結果是顏色總體變淡。有時白版磨損使白墨上墨量不足,對基材底色的遮蓋力不足,此時應停機換版生產,舊版重新退鍍。若印版滾筒使用過渡網墻坍塌導致不能退鍍,必須重新制版。
3.圖案顏色不一致。版面橫向同時排布多個圖案時,可能發生印版左右兩端圖案顏色不一致的情況。在制版過程中,尤其是滿版實地時,電雕從左到右容易產生網點大小的變化,因此,應注意檢查印版滾筒左右兩端的印刷效果差異。
4.印版設計的合理性。在進行印版設計時要充分考慮到印版設計對印刷過程和印后加工的影響。比如80%和5%左右的網點跳躍區的色彩極易發生層次并級,應提前采取改變措施。
5.印刷環境因素。印刷車間的室溫如果發生大幅度變化,油墨的流動狀態就會發生變化。一般生產車間的溫、溫度控制在溫度(23±5)攝氏度,濕度60%±5%。另外在冬季使用油墨時,要提前預熱,以增加油墨的流動性。
6.印刷條件。當版面受到無規則的風吹時,印刷速度和干燥速度發生變化,都會導致印刷品的顏色發生變化。在印刷過程中應充分考慮以上因素。
Main factors affecting printing quality
1. blocking. The blocking of dot will cause the transfer of ink to decrease, and the color of printed matter will change. In case of blocking, the printing plate shall be cleaned with solvent or special cleaning agent, and corresponding measures shall be taken for the causes of blocking.
2. the printing plate is worn. Plate wear will make the dot smaller and shallower, thus affecting the ink load of the dot. The result of plate wear is that the color is generally lighter. Sometimes the white version is worn out, resulting in insufficient ink on the white ink and insufficient hiding power for the substrate background color. At this time, the production should be stopped for version change, and the old version should be recoated. If the plate cylinder cannot be unplated due to the collapse of the transition screen wall, it must be remade.
3. the pattern color is inconsistent. When multiple patterns are arranged horizontally at the same time, the pattern colors at the left and right ends of the printing plate may be inconsistent. In the process of plate making, especially when the full plate is on the spot, the electric engraving is easy to change the dot size from left to right. Therefore, pay attention to check the printing effect difference between the left and right ends of the plate cylinder.
4. rationality of printing plate design. In the process of printing plate design, the influence of printing plate design on printing process and post press processing should be fully considered. For example, 80% and 5% of the colors in the dot jump area are prone to level merging, and change measures should be taken in advance.
5. printing environmental factors. If the room temperature of the printing workshop changes significantly, the flow state of the ink will change. Generally, the temperature and temperature of the production workshop shall be controlled at (23 ± 5) degrees Celsius and the humidity shall be 60% ± 5%. In addition, when using ink in winter, preheat it in advance to increase the fluidity of the ink.
6. printing conditions. When the layout is blown by irregular wind, the printing speed and drying speed change, which will lead to the color change of the printed matter. The above factors shall be fully considered in the printing process.