GB/T 47602-2026Digital printing materials - Positive thermal CTP plates - Test of imaging performance parameters (English PDF)

6.3 Dot area measuring instrument. a density meter for measuring dot area (accuracy

0.001 mm).

6.4 Spectrometer. Printing-specific spectrometer (accuracy

0.01 D).

6.5 Magnifying glass. not less than 40x (accuracy

0.05 mm).

6.6 Acetone. Analytical grade.

6.7 Developer. Developer specifically for thermal CTP plates.

7.2 Measurement

7.2.1 Clean point determination Using an 830 nm thermal CTP plate-making machine, ensure the machine parameters are set correctly, and use the built-in energy test scale of the thermal CTP plate-making machine. Prepare a blank plate for the sample. After developing the sample according to 7.1, place the plate on the platform and apply it to the blank stepped area. Acetone was dripped into the acetone ring. After the acetone had completely evaporated, the difference in reflectance density inside and outside the acetone ring was measured using the optical channel automatically identified by the spectrophotometer. The lowest exposure energy value, not exceeding 0.003, is the clean point of the sample.

7.2.2 Determination of Optimal Exposure Energy Using an 830 nm thermal CTP plate-making machine, the sample was exposed to 50% of its dot area using the built-in energy meter of the thermal CTP plate-making machine. Light plate making. After developing the sample according to 7.1, place the plate on the platform and use a dot meter to measure the dot reproduction value. The exposure energy value at 50% is the optimal exposure energy for the sample.

7.2.3 Resolution Measurement The sample is scanned and plated using the built-in test scale of a thermal CTP plate-making machine. The machine is set with the required screening conditions, and the sample is processed according to 7.1. After development, observe with a magnifying glass to see the restoration of 1%~99% of the dots or 1~3 pixels of halftone lines, indicating that the dot coverage is complete or... The lowest pixel value at which the mesh is clear is the resolution of the sample.

7.2.4 Tolerance Measurement

7.2.4.1 Exposure Latitude Measurement Based on the optimal exposure energy, with a plate-making energy ±10%, the sample is scanned and plated using a thermal CTP plate-making machine, following procedure 7.1. The process involves developing the sample using a method where the change in dot area ratio by 50% before and after changing the exposure energy is used to determine the exposure width of the sample. The magnitude of the tolerance. The smaller the absolute value of the change, the greater the exposure tolerance of the sample.

7.2.4.2 Determination of development time tolerance Based on the optimal exposure energy and recommended development conditions, and with a development time of ±5 s, the sample was prepared and developed according to the operating procedure in 7.1. The processing method involves using the change in dot area ratio by 50% before and after the development time to determine the development time tolerance of the sample. The smaller the absolute value, the greater the tolerance of the sample development time.

7.2.4.3 Determination of developing temperature tolerance Based on the optimal exposure energy and recommended development time, and with a development temperature ±2 °C, the samples were processed for plate making and development according to 7.1. The tolerance of the sample's development temperature is determined by the change in dot area ratio by 50% before and after a change in development temperature. The absolute value of the change is used. The smaller the value, the greater the tolerance of the sample development temperature.