Dries

Introduction

Driers are a group of metallic soaps containing either alkaline – earth metals or heavy metals combined with mono- basic carboxylic acids. They are soluble in organic solvents and binders. the driers are  represented  by the general fomula  ( RCOO ) m where R is an aliphatic or  salicylic and M a metal with valence X as in the case of a natural soap the acid or anion portion of the metallic soap can be varied typical anions currently used are either mephitic acid, 2- ethyl hexane acids.

Driers are added to coatings.  ( paints, varnishes and  inks ) to speedup the physical change form the liquid to the solid state. This change is effected 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 there are two main categories of  driers, I,e. :

Primary active driers:

cobait manganese
 
Auxiliary driers:

lead, zirconium, lithium, strontium, calcium, zinc, barium.

The auxiliary driers are used in conjunction with active driers to improve the final properties of the coatings. The solubility or solvent of these metallic soaps in a variety of organic solvents accounts for their many and varied other uses. Such as catalysts. Fungicides, fuel additives, stabilizers and wetting agents.

Our  many years experience  in the  manufacture  of driers has  lead in recent  years  to the  development  of highly concentrated driers and a new generation of  driers for water – borne  paints .

Comprehensive information about these driers together with our regular range is given further on in the brochure.

Derails are also given about yet another category of driers which are becoming increasingly popular. These are the lead, or barium – free driers. 

Zirconium

Zirconium is an excellent substitute for lead in lead – free paints.

It strongly activates the primary driers, cobalt and manganese and is particularly re- commended for eliminating tacking of certain tall – oil alkyd resins. 

Zirconium is also less toxic than lead or barium.

Lithium

Lithium is a substitute  for lead  and  is  used in  lead – free drier  compositions  in conjunction  with cobalt  and  calcium .

They are excellent drying catalysts even in high – solids; however, the whiteness of long- oil alkyd- based paints may be influenced.    
 
Calcium

This is an interesting drier since there are indications that when used in combination with indications that when used in combination with other metal sops a metal complex is formed. That is to say that if a violet cobalt solution is added to calcium then a vivid blur color appears.

Calcium prevents haze  formation in certain alkyd  resins that  are siccativated  with lead excessive  dosages  however  should  be avoided  in connection with the water sensitivity ( outdoor  durability ) of  the  paint  film .

Zinc

When used in combination with cobalt this type of drier produces a hard film. Zinc  keeps  the  film open thereby  allowing  oxygen  easy access which ensures hardening  throughout  the paint  film. Of all the  driers, zinc is the  best  wetting agent  the  gloss of the  film is also often improved  and it has  an added  property of  counteracting mildew formation .

A good quality drier should meet the following requirements:

• Uniform metal content
• Readily liquid for easy workability and dosage
• Constant colour and viscosity
• Readily soluble in all binders
• Good stability
  

Mobel manufactures the following types of driers:

• driers*
• Web driers
• Special cobalt – free driers
• Drier promoter Drymax
  

A short description of driers based on various metals Primary / active driers – cobalt this is the most active of the driers. It effects rapid surface drying and is generally used in conjunction with auxiliary driers.

An excessive amount of cobalt however reduces the water resistance of the paint and increases the risk of Wrinkling.

Manganese

This is also an active drier though generally less active than cobalt. As an accelerator of the polymerization in baking finishes Manganese is usually more effective than cobalt. Cobalt and Manganese primarily improve the surface drying of the paint filim.
However, the relatively dark colour of the Manganese drier may be a disadvantage.
Auxiliary driers – lead

An entirely different type of drier which is still an important auxiliary drier even through the substitution of zirconium is becoming increasingly popular. Lead is mainly applied in combination with active driers such as cobalt and Manganese. Due it’s polymerizing effect, Lead ensures a thoroughly hardened film.

MOBEL DRIERS

These are metallic salts of naphthenic and/or synthetic acid blends. They are stable and extremely soluble in all usual vehicles and thinners.

They also maintain their excellent stability even when a combination of metal soaps e.g., cobalt zirconium and/or calcium are applied 

MOBEL DRIERS and Application percentages

The percentages are calculated as metal on the quantity of the vehicle (solid matter). These percentages are however, very dependant upon the type of vehicle.

Application percentages the percentages are calculated as metal on the quantity of the vehicle (solid matter).

These percentages are however, very dependant upon the type of vehicle.

As mentioned earlier , active driers are mostly used in combination with auxiliary driers .servo offers a range of ready –made drier combinations, which are called combi driers. These driers have amongst others, the following advantages:

• improved efficiency
• reduction of the amount of raw materials
• reduced risk of weighing errors
• optimal metal proportions
• simplified production process
• uniform quality

In order to meet individual needs, “custom – tailoring “of combination driers is also offered.