Products
METALLIC DRIERS

Introduction:
Driers are a group of metallic carboxylates containing either alkaline-earth metals or heavy metals combined with monobasic carboxylic acids of the general formula (RC00)xM where M is a metal radical of valancy state X and R is organic radical containing at least 6-7 carbon atoms soluble in organic solvents and drying oils or alkyd resins.
Driers are added to coatings (paints, varnishes and inks) to speed up the physical change from the liquid to the solid state. This change is affected by an oxidative cross linking mechanism accelerated by the metallic cation of the added drier. The acid is present to secure adequate distribution of the metal throughout the medium.
The use of synthetic monocarboxylic acid like 2 - Ethyl Hexanoic Acid has gained the acceptance in drier technology due to the following advantages.

  • Constant chemical Composition and structure with high purity.
  • No pungent odour as they are odourless.
  • Good colour retention as they are colourless.
  • Yield metal soaps of constant composition, high purity and good stability.
  • All the available metals are effective as drying catalyst.

A good quality drier should meet the following requirements:

  • Uniform metal contents.
  • Readily liquid for easy workability and dosage.
  • Constant colour and viscosity.
  • Readily solube in all alkyds resins.
  • Good stability in white spirit.
Application:
The percentages are calculated as metal on the total quantity of the vehicle (solid matter). These percentages are, however, strongly, dependant on the kind of vehicle.
  METAL
PERCENTAGE
  
 
Cobalt
0.01   0.1
  
 
Manganese
0.01   0.1
  
 
Lead
0.08   0.6
  
 
Calcium
0.03   0.3
  
 
Zinc
0.03   0.5
  
 
Zirconium
0.05   0.3
  
Function:
Driers metals are traditionally divided into two groups - Active (primary) and Auxiliary (Secondary), though it is an arbitatory classification.
Driers that promote oxidation are termed active (primary) driers. Cobalt and manganese are considered active driers. Driers that exhibit no catalytic action on their own appear to enhance synergistically the functioning of the active driers metals and have been postulated as secondary (auxiliary) driers. Lead, Calcium, Zinc and Zirconium are Auxiliary driers.
Cobalt: 
Cobalt is the most active top drier because it drastically activates the drying of oil film by oxidation and is generally used in conjunction with auxiliary driers. Cobalt is used almost exclusively in printing ink driers because the rapid stacking of printed matter demands extremely fast drying.
Manganese:
Manganese is not as active as cobalt but still falls in top driers class. Oxidation is rapid but polymerization is also appears to be promoted so that there is a substantially lessened likelihood of bad skinning and wrinkling. Often a three component drier system is used consisting of manganese, cobalt and a thorough drier such as lead.
Lead:
Lead is effective polymerization drier, causing the film to dry in its entire thickness. Lead drier is seldom used alone but is used in combination with an active drier or top drier to decrease the total drying time. Lead also improves flexibility, toughness, durability and water resistance of the film.
Zinc:
Zinc is an auxiliary drier. Zinc, alone is insufficient but functions synergistically in the presence of a drier such as cobalt. Zinc keeps the film open, so that it remains more easily accessible to oxygen and hardening is realized throughout the paint film. Zinc possesses profound dispersing and wetting properties.
Calcium:
Calcium is an auxiliary drier and is used in combination with Zirconium in lead free systems. Calcium is good wetting and dispersing agent and helps in dispersing pigments when used with Zinc. Calcium prevents haze formation in certain alkyd resins of high acid value
Zirconium:
Zirconium is a very efficient auxiliary drier and is generally used in combination with cobalt and calcium. It is widely accepted substitute for lead free non-toxic paints. It is effective in both air dry and bake coating systems. It improves gloss hardness and thorough drying.
Iron :
Iron is drying agent effective at bake temperatures above 120°C and not effective in coatings which dry by oxidation. It can be used only in dark pigmented coatings.
Copper :
Copper although not used as drier, is very important for fungicidal treatment of textiles, antifouling agent for ships bottom, as an insecticide and wood preservative.
CHARACTERISTICS:
Products
% of Metal
Specific gravity
                      Colour
COBALT OCTOATE
12%
1.035
                        Blue
 
6%
0.890
                        Bluish Violet
MANAGANESE OCTOATE
6%
  0.910 
                        Brown
LEAD OCTOATE
24%
  1.085  
                        Pale Yellow
 
18%
  0.995 
                        Trace Yellow
ZINC OCTOATE
6%
   0.872  
                        Colourless
CALCIUM OCTOATE
3%
     0.885    
                        Colourless
ZIRCONIUM OCTOATE
6%
   0.880  
                        Pale Yellow
IRON OCTOATE               
  6%  
 0.92  
                        Redish Brown
COPPER OCTOATE          
6%
0.8
                        Dark Green