Positive UV CTP plates for offset printing are digital platemaking materials that are directly imaged by ultraviolet (UV) light sources. They have high precision, high stability and environmental protection characteristics and are widely used in commercial printing, packaging printing and other fields. Positive UV CTP plates belong to UV-CTP (Computer-to-Conventional Plate) technology. They use positive image plates (Positive Image) to form images on the plates through ultraviolet (UV, wavelength 405–410nm). During development, the unexposed areas are cleared and the exposed areas are retained to form images. Its imaging process is similar to that of traditional PS plate exposure, but it is directly exposed through digital equipment without the need for film. The core equipment accurately controls the image transfer through a digital micro-mirror (DMD) or a laser head.

Core technical features

- Optimization of photosensitive layer and aluminum base

The positive UV CTP printing plate adopts a new ultraviolet photosensitive layer formula and an aluminum base treated by electrolytic oxidation. Through double-layer coating technology and high-sensitivity resin, it achieves a significant improvement in dot reproduction accuracy (2-98%@250lpi AM screening) and wear resistance. The thickness of the aluminum base oxide layer is usually controlled at 2.80-3.10g/m², and the surface roughness (Ra value) is stable at 0.45±0.02μm, ensuring water-ink balance and printability.

- High printability and adaptability

Ordinary ink printing: The printability can reach more than 200,000 prints, suitable for long-run printing.

UV ink printing: The printability is about 50,000 prints, compatible with UV-LED curing technology, and reduces volatile organic compound (VOC) emissions.

Stability under extreme conditions: Some plates can cope with complex environments such as UV inks and metal inks without baking, and the printability after baking can exceed 1 million prints.

- Fast platemaking and development latitude

Positive UV CTP plates are compatible with mainstream UV-CTP platemakers (such as Kodak Trendsetter and Fujifilm Brillia series), with exposure energy as low as 75mJ/cm², development time of only 25-30 seconds (25℃), and strong compatibility with developer, which can reduce chemical consumption.

Performance advantages of positive UV CTP plates:

1. Platemaking efficiency

Dot restoration: Accurate reproduction of 2-98% dots (200 lines/inch), micro-line accuracy of 6-10μm.

Speed: 10-15 sheets/hour for positive type platemaking, 20-30 sheets/hour for negative type platemaking.

2. Printing endurance and stability

Standard conditions: 100,000 prints for positive type and 150,000 prints for negative type platemaking.

Storage stability: Valid for 2 years at 10-20℃ and 65%RH.

3. Environmental protection and cost

Environmental protection: Reduce chemical waste liquid discharge and meet green printing standards.

Cost-effectiveness:

Compared with thermal CTP plates, UV-CTP plate costs low, which can save thousands of dollars per month.

Long-term use is economical, especially suitable for large-scale printing.

Application scenarios of positive UV CTP plates:

- Commercial printing and packaging fields

High-resolution requirements: 25 micron frequency modulation screening can be achieved, suitable for fine graphics (such as pharmaceutical packaging, high-end books and periodicals).

Environmental compliance: Direct use of UV ink reduces VOC emissions during printing, and complies with EU REACH and other environmental standards.

Cost control: High printability reduces the frequency of plate replacement, for example, more than 30% of plate costs can be saved in long-run printing.

- Printing of special materials:

Combined with UV printing technology (such as UV ink, glazing), high-quality printing of non-absorbent materials such as metal cardboard, plastic, and PVC can be achieved.

Positive UV CTP plates have become the mainstream choice for offset printing due to their high precision, high stability and environmental protection. With the popularization of UV-LED curing and wash-free technology, its application in packaging, commercial printing and other fields will continue to expand.