Describe four important factors affecting the printing quality of Neat Kraft Paper Pen Display Boxes

Describe four important factors affecting the printing quality of Neat Kraft Paper Pen Display Boxes

There are many factors affecting the quality of Neat Kraft Paper Pen Display Boxes printing image, common are: dot increase, printing contrast, dot deformation, overprinting, ink layer thickness, paper smoothness, printing speed, plate wear and so on. This happens in print production, no matter how carefully the printer operator works. In order to ensure the stability of the printing quality, the operator must sample the printing, make a judgment on the changes, take the corresponding adjustment measures.

Some main characteristic parameters that need to be measured are introduced here, and a sample is measured and evaluated with densitometer X-Rit530 and other instruments as an example.

1. SolidInkDensity

Field density refers to the density value at 100% dot, measured by a densitometer on the field color block. Field density can be understood as a qualitative or quantitative description of the match between printed paper and printing ink. Qualitatively speaking, if the field color block is relatively dark and bright visually, and the dot observed by borrowing a magnifying glass is relatively full, it indicates that the color of the image in the proof is relatively saturated, basically meeting the requirements of printing. On the contrary, the paper and ink combined performance is not good. Quantitatively, we can measure the field density D with a densitometer on the existing field color block. There are two measurement methods: First, in the same printing, choose different field color blocks in different directions (horizontal/vertical) for measurement, and draw the results into the state curve of the field density; Secondly, the continuous proofs or discontinuous sample proofs are selected on the printing press in a certain state for measurement, and the field density curve under the printing state can be obtained by drawing a curve. According to the field density curve drawn, we can find the difference law of the field density in different parts of the same print and the change law of the field density between continuous proofs or discontinuous proofs. We can adjust the printing process by such a rule.

In general, in order to effectively reproduce the order values of images, we need to control the field density of various colors. For fine prints, the field density of yellow (Y) should be controlled between 0.85 and 1.15, that of magenta (M) should be controlled between 1.25 and 1.55, and that of cyan (C) should be controlled between 1.30 and 1.60. Black (BK) should be controlled between 1.40 and 1.80, and the deviation of same-color density should not be greater than 0.05. For general printing requirements, the field density of yellow (Y) should be controlled between 0.80 and 1.10, magenta (M) should be controlled between 1.15 and 1.45, green (C) should be controlled between 1.25 and 1.55, black (BK) should be controlled between 1.20 and 1.60, and the deviation of the same color density should not be more than 0.07.

According to the measurement results, as a general print, except yellow and black meet the requirements of general printing, others cannot meet the general requirements of printing quality. In addition, each color block color difference is large, which shows that the ink is not uniform.

In the range of low field density, field coverage is the main factor affecting the field density. If the field coverage reaches saturation, the influence of the thickness of the ink layer should be prominent. As the thickness of the thinner part of the ink layer gradually increases, the thickness of the ink layer tends to be uniform, so the field density increases. And further to the field density value after the range of high ink surface smoothness on the field density value will also have an impact.

2. Network expansion (DotGain)

Dot enlargement refers to the difference between dot size and dot size on the color separators. In printing production, due to the influence of printing pressure, the number of network cables, dot shape, paper on the double reflection of light and other factors, dot expansion is normal, but it should be controlled within a certain range. Generally speaking, fine printing dot expansion should be controlled at 10%-20%, while general printing dot expansion should be controlled at 10%-25%.

As can be seen from the test results, the dot increase rate increases with the constant increase of dot percentage, reaching the maximum when it reaches 70%, which is caused by dot lap. The proof basically meets the requirements of fine printing in the aspect of controlling dot expansion.

3. PrintContrast

The contrast is used to reflect the transition of layers between the middle tone and the dark tone. The calculation formula is as follows: DS-D75DS, where Pc is the relative contrast, Ds is the field density, and D75 is 75% color block density.

Generally speaking, with the increase of image field density, the relative contrast of the image also increases gradually. However, when the field density increases to a certain value, the dot expansion occurs, and then the relative contrast begins to decline, the level decreases and the contrast decreases.

By comparing the experimental results with the printing standard data, we can see that it basically meets the printing requirements. In addition, it is necessary to know that when the amount of ink reaches 10μm thickness, the ink that reaches its field density, and then increase the amount of ink, the field density of ink increases slowly or almost no longer, but will lead to increasing dot.

4. InkTrapping

Overprint rate is a term used to describe the ability of an ink to adhere to a previous color printing surface. Generally, only red (R), green (G) and blue (B) are tested. The formula is as follows: T= dop-d1d2 where T is the overprint rate, Dop is the density after overprinting, D1 is the density of the first primary color, D2 is the density of the second primary color.

The higher the value of overprint rate, the better the effect of overprint. The quality of overprint rate is closely related to the printing color sequence. In the actual printing production process, different overprint rate reflects the quality of the printed matter will be different.