Alternatives to cobalt dryers for paints

Number

323-EN

Section

General Section

Use

Sector

Building and construction work

Function

Other

Process

Roller application or brushing

Product category

coatings and paints, thinners, paint removers

Application

Cobalt dryers

Abstract

Cobalt organic salts are very good driers for paints but increasing concern about the hazard of cobalt compounds, in general, made producers look for alternatives.

Substituted substances

Naphthenic acids, cobalt salts

CAS No. 61789-51-3 EC No. 263-064-0 Index No.

Chemical group

Cobalt compounds; carboxylic acid salts

Other adverse effects

Cobalt compounds are 2B carcinogens according to IARC classification.

Reliability of information

Internet information: data are from an internet document and only a basic and partial evaluation could be performed

Reason substitution

CMR

Hazard Assessment

Substance to be substituted: Naphthenic acids, cobalt salts (cobalt naphthenate) has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). According to harmonised classification and labelling (ATP14), cobalt may cause cancer, may damage fertility, is suspected of causing genetic defects, may cause long lasting harmful effects to aquatic life, may cause an allergic skin reaction and may cause allergy or asthma symptoms or breathing difficulties if inhaled. Alternative substances: Iron ( 3+) octanoate (iron octoate) and manganese bis (2-ethylhexanoate) have no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation).

Description of Substitution

Substitution of cobalt due to concern about its hazards resulted in efforts to find alternatives. Examples of such alternatives along with general information on properties and usability are given in a presentation of a known producer. The document also includes results of test for various alternatives, compared to cobalt driers for high-solids alkyd paints. According to the producer, manganese driers currently represent the main alternative to cobalt, with their high drying power, although lower than that of cobalt. Their main disadvantage is the brown discoloration and yellowing of white and light-colour paints. Manganese gives a longer drying time but better film hardness compared to cobalt based driers. An alternative example could be the manganese bis(2-ethylhexanoate) which can substitute naphthenic acids, cobalt salts (cobalt naphthenate) as drier. The document mentions similar salts (octoates/ ethyl hexanoates, naphthenates) of metals like iron or vanadium that can be used as alternatives. Driers can be used with low-chain aliphatic esters of oleic and linoleic acid (not classified as toxic or as VOCs) instead of usual aliphatic or aromatic solvents according to the document.

Case/substitution evaluation

Concern about cobalt is quite generalised to its compounds triggered by the fact that some are classified as sensitisers or carcinogenic or reprotoxicants. It is hard to choose between cobalt and manganese in terms of hazard. Some documents present manganese as less hazardous than cobalt while others state that it is hard to separate and differentiate effects (see Further information). Though manganese bis(2-ethylhexanoate) itself is not classified as a very hazardous substance, some manganese compounds (inorganic) are considered neurotoxicants (see SUBSPORTplus database for substances of high concern). Iron is generally presented as a less toxic metal, compared to cobalt, manganese or vanadium and information available on iron paint driers does not include severe hazards.

State of implementation

In use

Availability of Alternative

Alternative dryers based on manganese, vanadium or iron slats are available on the market.

Producer/Provider

http://borchers.com/index.php?id=2

Type of information supplier

Producer / distributor

Contact