Hot-Dipped Galvanized Steel

A Comprehensive Portfolio

Most cold-rolled steel is directly coated with zinc in the steel factory. The standard method adds a coating of zinc to the surface of the steel coil by dipping the metal into a hot zinc bath. This is known as hot-dipped galvanizing (HDG). BONDERITE^® offers a comprehensive portfolio of sustainable innovations that boost quality and process efficiency for hot-dipped galvanized steel coil. This includes cleaners and pretreatments for coil coating of HDG materials, passivation solutions that protect the metal against rust or corrosion during transport, as well as innovative thin organic coatings (TOC) that prevent visible fingerprints and boost corrosion protection, while supporting formability and paint adhesion later in the process.

Coil Pretreatment

Coil coating is one of the key applications for hot-dipped galvanizing cold-rolled steel and zinc. Good cleaning and pretreatment are essential for this process. Before the pretreatment step, the material is cleaned and the surface is activated. New BONDERITE^® cleaners are available to improve adhesion, and they work in synergy with the pretreatment to avoid blistering of the paint.

The non-rinse pretreatment afterwards is reliable and easy to control. BONDERITE^® solutions convert the surface of the metal into a non-metallic inorganic layer that is suitable for adhesion and corrosion protection. There is no wastewater created from the pretreatment step. In this way, pretreatments from Henkel enable our customers to make a significant contribution to sustainability – while also increasing process efficiency and reducing costs.

Passivation

Hot-dipped galvanized steel coil can be passivated to improve corrosion resistance. Mostly, this involves the use of chemicals based on Chromium III, which we also offer in our BONDERITE^® portfolio. However, Chromium VI has been banned in the European Union since 2006 and many experts predict a broader ban will come in the next few years, which could also have implications for products containing Chromium III. In this context, there is an urgent need for chromium-free passivation solutions – and BONDERITE^® offers a portfolio of high-performance passivation that meet this need. These innovative and sustainable technologies deliver similar performance to chrome-based products for hot-dipped galvanized steel coil, with a range of additional benefits.

Our BONDERITE^® chrome-free passivation solutions are compliant with RoHS standards and REACH requirements. They are free from other heavy metals too, and do not cause deposits or sludge. The passivation provides very good corrosion protection, while they are also designed to optimize compatibility with other metal-working fluids in downstream processes. They create a uniform, thin, transparent and colorless film on the steel strip.

Thin Organic Coatings (TOC)

BONDERITE^® provides specialty coatings that support the process of manufacturing steel coil for roofs, doors, computer cases, smart phones and many other products. Our transparent organic coatings for hot-dipped galvanized steel substrates protect against corrosion and enhance a range of mechanical properties. These thin organic coatings (TOC) provide a transparent coating, where organic polymers act as a matrix and the inorganic phase is dispersed. The organic part increases the flexibility, chemical resistance and compatibility with other organic systems. The inorganic part increases the durability and adhesion to the hot-dipped galvanized steel coil substrate.

Our portfolio also includes one-component chrome-free thin organic coating options that empower our customers to stay ahead of increasing regulation related to chromium – and support their efforts to boost safety and sustainability.

Benefits of Thin Organic Coatings

The benefits of our thin organic coating solutions include:

Anti-fingerprint: No fingerprints can be seen after handling.
Corrosion protection during storage and transport, and on the end product.
Parts can be formed without the use of further lubricants.
Excellent paint adhesion without further pretreatment.
Less odor during application.
No sticking on surface after drying.
Bright coating surface appearance.