The difference between “epoxy zinc-rich primer” and “inorganic zinc-rich primer”, what is the difference between these two materials?

The primer used in steel structure coating is zinc-rich primer, and the most used ones are “epoxy zinc-rich primer” and “inorganic zinc-rich primer”, what is the difference between these two materials?

The performance of epoxy zinc-rich primer and inorganic zinc-rich primer is basically the same in the steel structure corrosion prevention system of multi-layer coating system, and in many cases, epoxy zinc-rich primer can be used instead of inorganic zinc-rich primer. From the construction point of view and construction speed, epoxy zinc rich primer is more suitable.

In terms of film performance, inorganic zinc-rich primer has high hardness and brittleness, so it is not suitable for thin-walled steel structures, but it is very suitable for large-scale steel structures because the deformation of large-scale steel structures is not big. And inorganic zinc-rich primer hardness, curing is not easy to break; for salt spray resistance, inorganic zinc-rich primer is much higher than the epoxy zinc-rich primer, especially in seawater, single-layer inorganic zinc-rich primer performance is very excellent, can achieve long-lasting corrosion protection.

Steel coating systems include surface preparation, spraying, testing, and maintenance. It can be compared around these aspects:

1, curing environment

Epoxy zinc-rich primer: lower humidity has no effect on curing;

Inorganic zinc-rich primer: need a higher relative humidity to cure, generally need more than 65%.

2、Mixing requirements

Epoxy zinc-rich primer: easy construction, no need for continuous mixing;

Inorganic zinc-rich primer: continuous stirring is required.

3、Properties

Epoxy zinc-rich primer: easy to recoat, no need to close the primer;

Inorganic zinc-rich primer: the surface is porous, which will lead to pinholes and bubbles in the latter paint, and requires special spraying techniques such as mist spraying and unified spraying.

4、Repainting time

Epoxy zinc-rich primer: 23℃, 1.5 hours;

Inorganic zinc-rich primer: very long time, need to make curing test (MEK) to determine whether the construction of intermediate paint.

5. Repair performance

Epoxy zinc-rich primer: easy to repair damaged areas;

Inorganic zinc-rich primer: very sensitive to poor surface treatment, the damaged area is easily delaminated.

6. Film properties

Epoxy zinc-rich primer: small brittleness, good flexibility;

Inorganic zinc-rich primer: brittle paint film, poor flexibility.

In summary, the use of inorganic zinc-rich requirements of water vapor curing, recoating interval at room temperature is very long, the need for curing test before overcoating the latter paint, and the need to use a special mist spraying technology; and epoxy zinc-rich primer can be recoated as long as 1.5 hours of the intermediate paint, conventional construction, high efficiency, you can greatly shorten the construction period of the tension.