In recent years, China's PS version technology has developed rapidly, and output has continued to increase. The prosperity of the market will inevitably bring about fierce market competition. If the PS version manufacturers want to occupy a stable market share, they must ensure the quality and credibility of their products. Therefore, it is very important to ensure good product quality in the PS version production process. Therefore, PS version quality control should be achieved through the following routine tests.
Testing of raw materials
The positive version of PS is composed of photosensitive layer and aluminum base. The raw materials commonly used in PS production plants can be refined into four areas around these two parts:
1) Various raw materials required for the preparation of photosensitive liquid;
2) In order to meet the printing requirements, various raw materials required for a series of process treatments on the aluminum base;
3) Aluminum plate base required by PS version of Yangtu support;
4) Water quality of production water of PS version of Yangtu.
In order to stabilize product quality, before purchasing raw materials, various technical performance indicators of the required materials should be proposed to raw material suppliers according to production requirements; purchased raw materials must be analyzed and tested for their main technical indicators.
1. Analysis and testing of various raw materials required by photosensitive liquid
Yangtu PS plate photosensitive liquid is mainly composed of photosensitive resin, film-forming resin, dye, solvent and other additives.
1) Determination of the performance of 2.1.5-sulfonyl chloride 2.1.5-sulfonyl chloride is orange-yellow crystal and is used for the synthesis of photosensitive resin.
①Determine the melting point. The melting point of a solid substance refers to the temperature at which the substance reaches equilibrium with the liquid state under atmospheric pressure. Under an atmospheric pressure, the change of solid-liquid state of very pure materials is very sharp, and the temperature changes from the initial melting to the total melting temperature does not exceed 1 ℃; if it contains impurities, the melting point decreases and the melting point range is widened. Therefore, measuring the melting point can determine the purity of the compound.
â‘¡ Determination of 2.1.5-sulfonyl chloride content. 2.1.5-The content of sulfonyl chloride has a great influence on the photosensitive performance of photosensitive resin. The purity of 2.1.5-sulfonyl chloride produced by various manufacturers is now high, with a content of more than 98%, but in order to synthesize a stable photosensitive resin, the content of 2.1.5-sulfonyl chloride should be measured. The simplest and most accurate method for detecting the content of 2.1.5-sulfonyl chloride is to use an ultraviolet spectrophotometer, which can be made by a domestic ultraviolet spectrophotometer.
â‘¢ Determination of ultraviolet absorption spectrum. Ultraviolet spectrophotometer can be used to determine the maximum absorption wavelength of 2.1.5-sulfonyl chloride.
2) Measurement of film-forming resin The film-forming resin mainly uses novolak resin, which is a polymer compound.
â‘ Determine molecular weight and molecular weight distribution. Polymer compounds are composed of many molecules of different sizes, and different molecules have different shares. The width of the molecular weight distribution has a great influence on sensitivity and resolution. Gel permeation chromatography (GPC) can easily and accurately determine the number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution of phenolic resins.
â‘¡ Determine the viscosity. The viscosity of the film-forming resin can be measured with a rotary viscometer.
In addition to the above two tests, the melting point of the resin needs to be determined.
3) Determining the moisture content of solvents Except for a few PS manufacturers that use glycol monoethyl ether, methyl ethyl ketone, esters and other mixed solvents to prepare photosensitive liquids, most manufacturers only use ethylene glycol monoethyl ether as the solvent. However, no matter whether it is a multi-component solvent or a single-component solvent, the water content of the solvent must be determined by Karl and Fischer automatic titrators.
2. Analysis of the process of the base treatment process The flow chart of the PS version of the base treatment process is:
Unwinding of aluminum coil → alkaline washing → electrolysis → oxidation → hydrophilization treatment
1) Alkaline cleaning removes grease and natural oxide film on the surface of aluminum plate.
2) Electrolysis forms sand on the surface of the aluminum plate to increase the surface area to improve the hydrophilicity of the non-image area and the adhesion between the aluminum plate and the photosensitive layer.
3) Oxidation produces a solid AI2O3 film on the aluminum plate after electrolysis to improve the abrasion resistance, corrosion resistance and stability of the printing plate.
4) Hydrophilization treatment
Reduce the adsorption of the AI2O3 film to the photosensitive layer, increase the hydrophilicity of the non-image area, and reduce the solubility of AI2O3 and Al in the developer.
The content of inorganic acids and inorganic bases in the raw materials used in the PS plate base treatment process is determined by the volumetric analysis method. When measuring the content of sodium hydroxide, since industrial sodium hydroxide contains a small amount of sodium carbonate, the sodium carbonate should be converted into barium carbonate before being analyzed.
3. Qualitative and quantitative analysis of aluminum-based trace elements usually contains a small amount of trace elements in the aluminum base. Qualitative and quantitative detection of trace elements can be determined by atomic absorption spectrometry. The atomic absorption analysis method has high sensitivity and good repeatability. The operation is simple and fast, but the price of the instrument is relatively high, and the manufacturer can go to the physical and chemical testing center for testing regularly.
4. Analysis and detection of production water of PS version In the production process of PS version, a large amount of water is required. It is best to use deionized water, because the cations and anions in the water will have a certain effect on the PS version, such as halogen ions can corrode the oxide film Produce small holes.
Deionized water can be prepared by ion exchange method, and the conductivity can be measured by a conductivity meter. Each manufacturer can determine the corresponding conductivity value according to the quality requirements of its own production water and conduct periodic measurement.
[NextPage]
Product quality control testing
In addition to some attributes of the product itself, evaluating the quality of a product must also have good repeatability and stability. The manufacturer should have a strict set of enterprise standard data to control the quality of the product.
1. Check the concentration of the solution used for plate treatment
The detection of the concentration of the solution used in the base treatment process mostly uses online detection. During the production process, the concentration of various solutions used in the base treatment process is quantitatively tested regularly to reach the specified index. At the same time, the content of Al3 + in degreasing fluid, electrolyte and oxidizing fluid should also be detected. The concentration test can be completed by a simple and fast acid-base titration analysis method, and enterprises with good conditions can install an online detector. At present, the accuracy of the PS version of online detection instruments produced in China is not too high, and it is only for reference. The actual online automated detection instrument uses electrochemical analysis, which uses the quantitative relationship between the chemical composition and the voltage, current, conductance, etc. of the substance in the process of chemical energy and electrical energy conversion to determine the content of each substance.
2. Test the inherent quality of the product
1) Performance test of the substrate â‘ Surface roughness. The surface roughness is determined by a surface roughness tester, which is generally evaluated by Ra, Rz, Sm and other technical parameters. Among them,
Ra——the arithmetic average value of the absolute value of the contour offset within the sampling length;
Rz——the sum of the average of the five largest contour peak heights and the average of the five largest contour valley depths within the sampling length;
Sm——the average value of the spacing of the micro unevenness of the contour within the sampling length.
The density D of the profile peak can be calculated by Sm:
D = L / Sm, where L is the sampling length.
â‘¡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 thickness of the oxide film.
a. Integrity and compactness detection The integrity and compactness of the oxide film are tested with copper sulfate solution. Under acidic conditions, copper ions will undergo a substitution reaction with aluminum instead of reacting with AI2O3. When the exposed aluminum base or the oxide film is loose in the detection area, the copper ions in the copper sulfate solution will react with the aluminum at the defect, and at the same time, gas will be released, and black spots can be observed at the defect of the oxide film presence.
b. Detection of AI2O3 crystal form state Observation of the AI2O3 crystal form structure through an electron microscope can detect its crystal form state. With fewer lattice defects, the oxide film is of high quality.
c. Determination of the thickness of the oxide film The thickness of the oxide film of the PS version has a great influence on the printing performance. The thickness of the oxide film of the PS version is expressed by the mass of Al2O3 contained in the unit area (g / m2). It is determined by the method specified in the chemical industry standard, HG / T2694-95.
2) Detection of the physical and chemical properties of the photosensitive layer ①Determination of the thickness of the photosensitive layer. The thickness of the photosensitive layer has an effect on the lipophilicity, sensitivity, resolution, printing resistance, and development effect of the graphic, and its thickness must be strictly controlled within a certain range. The thickness of the photosensitive layer is expressed by the mass per unit area of ​​the photosensitive layer (g / m2), which needs to be measured according to the method specified in the "Positive Type PS Version of the Ministry of Chemical Industry Standard, HG / T2694-95".
②The anti-alkali film retention performance of the photosensitive layer. The anti-alkali retention performance of the photosensitive layer has a great influence on the resolution and printing resistance of the plate. Alkali resistance mainly refers to the degree of solubility of the photosensitive layer in the developing solution, which is expressed by the anti-alkali retention rate. The anti-alkali retention rate is the ratio of the weight per unit area of ​​the photosensitive layer (W1) to the weight of the remaining photosensitive layer W2 (W2 / W1) after soaking in an alkaline solution. Detecting the anti-alkali retention performance of the PS plate at different exposures can better express the difference in the photosensitive characteristics of the positive PS plate.
3) Detection of photosensitive performance The sensitivity of the photosensitive layer of the PS version of the positive image includes the determination of the sensitivity, resolution, contrast coefficient and background color of the PS version.
â‘ Sensitivity. Sensitivity refers to the sensitivity of the photosensitive material to light, that is, the speed of light, and the sensitivity of the PS plate is expressed by the amount of exposure. The smaller the exposure required (the light energy absorbed by the photosensitive material) to achieve a certain density, the higher the sensitivity; the more exposure required, the lower the sensitivity.
â‘¡ Resolution. Resolution refers to the ability of the photosensitive layer to distinguish the fine layers of the original after being exposed to a certain amount of exposure.
â‘¢ Contrast coefficient of PS version. The contrast coefficient 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; the exposure tolerance is large, and the printing durability is high. Sensitivity detection is generally measured by continuous exposure of the ladder and signal bar to the PS plate after exposure and development.
④Background color of the layout. The background color (D0) of the plate is measured with a reflection densitometer. Under normal circumstances, D0≤0.03.
3. Detection of the matte air-conducting layer Now the domestically produced PS version has added a matte air-conducting layer, thereby improving the reduction of the outlets and reducing the pumping time. In order to ensure the stability of the coating, it is necessary to check the quality of the matting agent contained in the unit area and the pumping time. When exhausting, use dot film and PS version to contact and observe the time required for vacuuming.
Finished product surface inspection
The final process of PS plate production is the apparent inspection, which mainly depends on the uniformity of the surface coating of the PS plate, whether the plate surface is smooth, whether there are creases, trachoma, white spots, dirty spots. Sort and package according to grade requirements, and then leave the factory.
We are a professional manufacturer and exporter of Plastic Kitchenware. Our Plastic Kitchenware is an essential good helper in kitchen, and also very useful in daily life.
Great for daily time use, ideal for camping, picnic, and school.
We focused on international export product development, production and sales. Welcome to inquire, all factory direct sales, to cooperate with you wholeheartedly!
Plastic Kitchenware
Plastic Kitchenware,Plastic Water Bottle,Plastic Advertising Mug,Plastic Mug With Lid
Fulike Houseware&Gifts Co.,Ltd. , https://www.cnfulike.com