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Drying technologies

Introduction:

In principle we have to differ between physical drying and chemical curing/ film building. In the following, the four main mechanism are shortly described.

1. Penetration

Drying act:

  • Physical drying process
  • Printing material absorbs the thinner of the ink
  • Drying in seconds
  • Part of drying process in printing inks and water based varnishes in cold-set the only drying process.  For example, news paper web offset.

2. Oxidative film building

Drying act:

  • Chemical film building
  • Parts of the printing ink react with oxygen
  • Dryer compounds speed up film building
  • Film building in hours
  • Oxidative film building is a partial process in conventional printing inks.

3. Evaporating

Drying act:

  • The water particles of the varnish are transformed in a steam like condition
  • The steam, or respectively, the steam saturated air will be exhausted
  • Drying in seconds or up to minutes

 

Hint:
The evaporating drying is a partial process of the drying of varnishes. The drying process of water based varnished will be explained in the following.

4. Polymerization UV curing

Curing act:

  • UV radiation and photo initiators are starting the series of polymerization processes
  • Curing process in milliseconds