The positive inspection in the production process of positive chart PS plate

In recent years, China's PS plate technology has developed rapidly and its output has continued to grow. The prosperity of the market will inevitably bring about fierce market competition. If PS manufacturers want to have a stable market share, they must ensure the quality and reputation of their products. Therefore, it is of utmost importance to ensure good product quality in the production of PS plates. Therefore, the quality control of the PS plate must be achieved through the following routine tests.

Raw material testing

The positive PS version consists of a photosensitive layer and an aluminum plate base. The raw materials commonly used in the PS plate production plant can be divided into four parts around these two parts:

1) Various raw materials needed for preparing photosensitive liquid;
2) In order to meet the printing requirements, various raw materials required for a series of process treatment of aluminum base are processed;
3) aluminum plate base for the positive PS plate support;
4) The water quality of the production water for the positive PS version.

In order to stabilize the product quality, before purchasing raw materials, various technical performance indicators of the required materials shall be submitted to the raw material suppliers according to the production requirements; the purchased raw materials must be analyzed and tested on its main technical indicators.

1. The analysis and detection of various raw materials required for the photosensitive liquid

Yang Tu PS photosensitive liquid is mainly composed of photosensitive resin, film-forming resin, dye, solvent and other additives.
1) Determination of the 2.1.5-sulfonyl chloride property 2.1.5-The sulfonyl chloride is an orange-yellow crystal for the synthesis of photosensitive resin.
1 Determine the melting point. The melting point of a solid substance refers to the temperature at which the substance is at equilibrium at equilibrium with the liquid state. Very pure substances are very sensitive to changes between solid and liquid states at atmospheric pressure. They do not vary by more than 1°C from the initial melting point to the total melting temperature. If impurities are contained, the melting point decreases and the melting point range widens. Therefore, the melting point can be determined to determine the purity of the compound.
2 Determination of 2.1.5-sulfonyl chloride content. The content of 2.1.5-sulfonyl chloride has a great influence on the photosensitive properties of the photosensitive resin. The purity of 2.1.5-sulfonyl chloride produced by various manufacturers is now higher than 98%. However, in order to synthesize a stable photosensitive resin, the content of 2.1.5-sulfonyl chloride should be determined. The most simple and accurate way to detect the content of 2.1.5-sulfonyl chloride is to use a UV spectrophotometer and a domestic UV spectrophotometer.
3 Determination of UV absorption spectra. Ultraviolet spectrophotometer can be used to determine the maximum absorption wavelength of 2.1.5-sulfonyl chloride.

2) Determination of film-forming resin Film-forming resin is mainly a novolak resin and is a high molecular compound.
1 Determine the molecular weight and molecular weight distribution. The polymer compound is composed of many molecules of different sizes, and the shares of different molecules are different. The width of the molecular weight distribution has a great influence on the sensitivity and resolution. The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution of the phenolic resin can be conveniently and accurately determined by gel permeation chromatography (GPC).
2 Determine the viscosity. The viscosity of the film-forming resin can be measured with a rotational viscometer.
In addition to the above two tests, the melting point of the resin needs to be measured.

3) Determination of solvent moisture content In China, except for a few PS plate manufacturers that use a mixed solvent of ethylene glycol monoethyl ether, butanone, and esters to prepare photosensitive solutions, most manufacturers use only ethylene glycol ether alone as the solvent. However, whether using a multi-component solvent or a single-component solvent, the water content of the solvent must be determined using Karl Fischer Autotitrator.

2. Edition base treatment process analysis The positive figure PS plate base treatment process flow is:
Aluminum roll unwinding → caustic washing → electrolysis → oxidation → hydrophilic treatment

1) Alkali washing removes grease and natural oxide film on the aluminum surface.
2) Electrolysis forms a grain on the surface of the aluminum plate, increasing the surface area to increase the hydrophilicity of the non-image area and the adhesion of the aluminum plate to the photosensitive layer.
3) Oxidation generates a solid AI2O3 film on the aluminum plate after electrolysis to improve the plate's wear resistance, corrosion resistance and stability.
4) Hydrophilization

Reducing the adsorption of the AI2O3 film to the photosensitive layer, improving the hydrophilicity of the non-image area, and reducing 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 was determined by volumetric analysis. When measuring the sodium hydroxide content, since sodium hydroxide for industrial use contains a small amount of sodium carbonate, sodium carbonate should first be converted to barium carbonate precipitation and then analyzed.

3. Qualitative and quantitative analysis of aluminum-based trace elements Detection of aluminum traces usually contains a small amount of trace elements, qualitative and quantitative detection of trace elements can be measured by atomic absorption spectrometry, atomic absorption analysis method with high sensitivity, good repeatability, The operation is simple and fast, but the price of the instrument is relatively high. Manufacturers can regularly go to physical and chemical testing centers for testing.

4. PS version of the production of water analysis and testing in the PS plate production process requires a lot of water, it is best to use deionized water, because the water of the cations and anions will have a certain impact on the PS version, such as halogen ions can oxidize the oxide film and Produce holes.
Deionized water can be prepared by ion exchange. The water quality can be measured by a conductivity meter. Each manufacturer can set the corresponding conductivity value according to the quality requirements of its own production water, and conduct regular measurements.