MEL Chemicals' Crosslinkers for the Paper Industry

MEL Chemicals supplies two ranges of formaldehyde-free insolubiliser, Bacote and Zirmel, for pigmented paper and board coatings; offering unparalleled quality and consistency.

Insolubilisers are important additives used in pigmented paper and board coatings to impart the properties required to achieve the highest quality print.

MEL CHEMICALS’ BACOTE (ammonium zirconium carbonate) and ZIRMEL (potassium zirconium carbonate) products are well established in most types of formulation for paper and board, these products provide a speed of cure, effectiveness, runnability and performance that you and your customers demand today.

Formaldehyde free and with FDA and BfR approvals they are the crosslinkers of choice at mills world wide. BACOTE and ZIRMEL are clearly the best solutions for high quality paper and board coating.

GENERAL CHARACTERISTICS

Bacote consists of a clear, aqueous alkaline solution of stabilised ammonium zirconium carbonate, containing anionic hydroxylated zirconium polymers. There is a slight ammonia odour associated with Bacote, and ammonia is released upon evaporation. There is no odour associated after curing.

Where an ammoniacal odour is considered undesirable, Zirmel is recommended. Zirmel consists of a clear, aqueous alkaline solution of stabilised potassium zirconium carbonate and offers all the benefits of Bacote.

Bacote and Zirmel products are all stable at ambient temperatures for a minimum of 12 months and can be used in the temperature range of 0-70ºC.

BENEFITS FOR COATING MILLS

Formaldehyde Free

As inorganic crosslinkers, Bacote and Zirmel are totally formaldehyde free.

Rapid Cure

Effective with all commonly used binders, Bacote and Zirmel react rapidly with binder funtionality as water is released in the drying section. No need for elevated temperatures or extended cure time.

Improved Printability

Achieved by optimal water resistance, reduction of contact angle, uniform distribution of binders within the coating and open coating structure.

Optical Properties

No adverse effects on optical properties - no time or heat exposure yellowing.

Regulatory Status

Approved under FDA and BfR regulations as a component of paper and paperboard in contact with aqueous and fatty foods.

Quality

Manufactured to ISO 9001

MODE OF ACTION

When added to a coating or size press formulation, Bacote and Zirmel interact weakly with oxygenated sites, mainly carboxyl or hydroxyl groups on the binder molecules. Removal of water and carbon dioxide during the drying stage drives the reaction to completion due to the generation of reactive zirconium cations.

Covalent bonds are formed and the reaction is irreversible under normal coating conditions. The reaction is not heat dependent. The dried coating will exhibit optimal water resistance but will remain hydrophilic in nature and the microporous structure of the coating surface will be "open" or unblocked.

Please refer to our Product List for further information about Bacote and Zirmel.

A review of the use of zirconium in surface coatings is available to download.