What Is a Thermal Dissolution CTP Plate?

What Is a Thermal Dissolution CTP Plate?
A thermal dissolution CTP plate is a type of thermal computer-to-plate material. It typically consists of three main layers:

• An aluminum substrate that does not require mechanical graining
• An ink-receptive thermal imaging layer
• A top protective layer, which is either PVA (polyvinyl alcohol) for conventional offset printing or silicone for waterless offset printing

This plate uses a semiconductor laser diode for imaging. During exposure, the thermal imaging layer absorbs the laser energy and undergoes significant physical and chemical changes. In its unexposed state, the coating is alkali-resistant and cannot be dissolved by the developer. After exposure, however, its solubility increases dramatically, allowing the exposed areas to be removed during development.

The basic imaging mechanism works as follows:

• Before exposure:
  The thermal coating is stable and insoluble in alkaline developer.
• After exposure:
  The coating absorbs heat, its structure breaks down, and its solubility increases.
• During development:
  • Exposed areas dissolve in the alkaline developer, forming the non-image (blank) areas
  • Unexposed areas remain intact and form the image areas

After development, the plate usually goes through rinsing and gumming to enhance ink receptivity and durability before it is mounted on the printing press.

Features of Thermal Dissolution CTP Plates

Advantages:

• High imaging quality with excellent contrast and dot reproduction
• No silver-based chemistry required, making it more environmentally friendly
• High stability and strong run length, suitable for medium to long print runs
• No surface graining on the aluminum substrate is required, simplifying production

Applications:

Ideal for commercial printing, book printing, packaging printing, and other offset printing fields that require high-quality image reproduction.