TRITRON

Physical Curing (Self Cure)

Physical curing refers to formation of solid films through physical processes only, while leaving the chemical nature of the components involved unchanged. Three film-forming processes can be distinguished.


Typical for inkjet:

  • Evaporation of volatile components (drying) resulting in formation of films consisting of non-volatile, non-colloidal (non-coalescent) components.

    This type of film formation runs without material changes, which generally permits  such dried coatings to again be dissolved in suitable solvents.

Special characteristics:

  • This film forming process is reversible. This means, that the film forming components remain soluble at least in those solvents they were originally dissolved in, if necessary in combination with a neutralizing agent.
  • In high-speed printing applications (e.g. packaging or mailing), this film forming process is essentially limited to porous media, provided the evaporation of solvents is not accelerated by heat or convection.
  • Film formation through phase transformation.
    Film formation through phase transformation is characterized by transition of ink from a fluid-like to a solid-like aggregate state.

Special characteristics:

  • This film forming process is reversible.


Non-typical for inkjet:

  • Evaporation of volatile components (drying) resulting in formation of films consisting of colloidal components (coalescence).
    A solid film is formed after evaporation of volatile components (drying) by colloidal (coalescent) components flowing together. This kind of film forming is a form of coalescence (fusion of particles).

Special characteristics:

  • This film forming process is irreversible.

Film formation can compete with other physical processes. Especially colloidal components can interact with the substrate. For example, colloidally dispersed pigments applied onto porous media (large surface) can adhere to the substrate in such a way, that they cannot be removed again.