PS version based on quality control routine testing (below)

(II) Control and Inspection of Product Quality

To evaluate the quality of a product, in addition to the properties of the product itself, it must also have good repeatability and stability. Manufacturers should have a set of strict enterprise standard data to control the quality of products.

â– 1. Detecting solution concentration

The detection of the concentration of the solution used in the plate-based treatment process mostly uses on-line detection. In the production process, the concentration of various solutions used in the plate-based treatment process is quantitatively tested to achieve the specified index. At the same time, the content of Al3+ in the oil, electrolyte and oxidizing solution should also be measured. Concentration testing can be done with a simple, fast acid-base titration assay. Enterprises with good conditions can install an online detector. At present, the accuracy of the PS version of on-line detection instruments produced in China is not too high, and it is only used as a reference. The actual online automatic detection instrument adopts electrochemical analysis method, which uses the quantitative relationship between chemical composition and voltage, current, conductance, etc. to determine the content of each substance in the process of chemical energy and electric energy conversion.

â– 2. Inspect the product's internal quality

1) Edition base performance testing

1 surface roughness. The surface roughness is measured by a surface roughness tester, which is generally assessed by technical parameters such as Ra, Rz, Sm, etc.
Ra - the arithmetic average of the absolute values ​​of the profile offset within the sampling length;
Rz - the sum of the average of the five largest peak heights in the sample length and the average of the five largest valley depths;
Sm - The average of the intervals of the profile micro-nonplanarities over the length of the sample.
The density D of the profile peak can be calculated by Sm:
D=L/Sm, where L is the sampling length.

2 oxide film. The evaluation of the quality of the oxide film mainly depends on the integrity and density of the oxide film, the crystal structure and the thickness of the oxide film.

a. Detection of Integrity and Density The integrity and density of the oxide film were measured using a copper sulfate solution. Under acidic conditions, the copper ion will react with aluminum instead of reacting with AI2O3. When the exposed aluminum or oxide film is loose within the test area, the copper ion in the copper sulfate solution will react with the aluminum at the defect, and the gas will be released. Black spots can be observed at the defects of the oxide film. exist.

b. Inspection of AI2O3 crystal state The observation of the AI2O3 crystal structure by the electron microscope can detect the crystal state of the AI2O3 crystal, and the oxide film is of high quality with few lattice defects.

c. Determination of oxide film thickness The thickness of the PS plate oxide film has a great influence on printing performance. The thickness of the PS plate oxide film is expressed by the mass of Al2O3 per unit area (g/m2), according to the positive PS version. Chemical Industry Standards, Determination of Methods as Specified in HG/T 2694-95.

2) Sensitive properties of photosensitive layer

1 Determination of the thickness of the photosensitive layer. The thickness of the photosensitive layer affects the graphic's oleophilicity, photosensitivity, resolution, print resistance, and developing effect, and its thickness must be strictly controlled within a certain range. The thickness of the photosensitive layer is expressed in terms of the mass per unit area of ​​the photosensitive layer (g/m2), and is measured in accordance with the method specified in the "Pattern Type PS Standard Edition Chemical Industry Standard, HG/T 2694-95".

2 photosensitive layer anti-alkali retention membrane properties. The anti-alkali retention property of the photosensitive layer has a great influence on the resolution and the printing resistance of the plate. Alkalinity mainly refers to the degree of dissolution of the photosensitive layer in the developer, and is expressed by the alkali-retaining film rate. The alkali-retention film ratio is the ratio of the weight per unit area of ​​the photosensitive layer (W1) to the weight W2 of the remaining photosensitive layer after soaking in an alkaline solution (W2/W1). Detecting the anti-alkali retention performance corresponding to different exposures of the PS plate can better show the difference in the photosensitivity of the positive PS plate.

3) Detection of photographic performance

The photosensitivity test of the positive photosensitive layer of the PS plate includes determination of the sensitivity, resolution, contrast ratio, and background color of the PS plate.

1 sensitivity. Sensitivity refers to the sensitivity of the photosensitive material to light, ie, the speed of light, and the sensitivity of the PS plate is expressed in terms of the amount of light exposure. The smaller the exposure required to reach a certain density (light energy absorbed by the photosensitive material), the higher the sensitivity; the more exposure required, the lower the sensitivity.
2 resolution. Resolving power refers to the ability of the photosensitive layer to distinguish the fine level of the original after exposure with a certain amount of exposure.
3PS version gamma. The gamma is an important parameter of the PS version. The contrast coefficient is large, the exposure transition area is small, and the image edge density loss is small, the image is clear, the dot reproducibility and resolution are good, and the exposure latitude is large, and the printing force is high. Sensitivity test is generally conducted with a continuous adjustment ruler and signal bar exposed to the PS plate and measured after development.
4 layout background. The background color (D0) was measured with a reflection densitometer. Under normal conditions, D0 ≤ 0.03.

â– 3. Detection of hair surface air layer

At present, the PS plates of domestic production all increase the rough surface gas-guiding layer, thereby improving the dot reducibility and reducing the pumping time. In order to ensure the stability of the coating, it is necessary to measure the quality and extraction time of the matting agent contained in the unit area. When evacuating, use the dot film and the PS plate to contact the suction and observe the time required for vacuuming.

(III) Finished product inspection

The final procedure for the production of the PS plate is the appearance inspection, mainly to see the PS plate surface coating uniformity, whether the layout is smooth, with or without creases, trachoma, white spots, and dirty spots. According to the grade requirements, they are packaged and then shipped.

Source: Ke Yin Media - "Printing Technology"