Silica makes the epoxy coating stronger!

Epoxy is familiar to everyone.

As a thermosetting resin, epoxy resin has the advantages of good physical properties, electrical insulation, good adhesion, alkali resistance, abrasion resistance, excellent manufacturability, stability and low cost.

At present, epoxy resin is used the most in the coating industry, and the coating made with it as the substrate is called epoxy resin coating

The secret to durable epoxy coating

Since epoxy resin belongs to the category of liquid polymer, it needs the help of curing agents, additives and pigments to incarnate into a corrosion-resistant epoxy coating

There are two main mechanisms for nano-oxide particles to enhance the protective performance of epoxy coatings:

First, by virtue of its small size, it can effectively fill the micro-cracks and pores formed by local shrinkage during the curing of epoxy resin, reduce the diffusion path of corrosive media, and enhance the shielding and protective performance of the coating;

The second is to use the high hardness of the oxide particles to increase the hardness of the epoxy resin, thereby enhancing the mechanical properties of the coating

In addition, adding an appropriate amount of nano oxide particles can also increase the interface bonding strength of the epoxy coating and extend the service life of the coating

Epoxy floor paint

The role of nano silica

Among these nano-oxides, nano-silica (SiO2) is a kind of high presence
.
It is an inorganic non-metallic material with excellent heat resistance and oxidation resistance.
Its molecular state is a three-dimensional network structure with [SiO4] tetrahedron as the basic structural unit
.
Wherein, between the oxygen, the silicon atom is directly covalently linked, solid structure, chemically stable and therefore have excellent heat and weather resistance
.

Nano SiO2 mainly plays the role of anti-corrosion filler in epoxy coating.
On the one hand, nano SiO2 can effectively fill the micro cracks and pores generated during the curing process of epoxy resin and improve the penetration resistance of the coating; on the other hand, , The functional groups of nano-SiO2 and epoxy resin can form physical/chemical cross-linking points through adsorption or reaction, and introduce Si—O—Si and Si—O—C bonds into the molecular chain to form a three-dimensional network structure to improve coating adhesion
.
In addition, the high hardness of nano-SiO2 can significantly enhance the wear resistance of the coating, thereby prolonging the service life of the coating
.

It is the simplest method to add nano-SiO2 directly into the coating through the blending method
.
PALRAJ et al.
used sol-gel method to synthesize nano-SiO2 powder, and compared with micron SiO2, studied the effect of different particle size SiO2 on the protective performance of epoxy coating
.
The results show that, compared with micron SiO2, nano-SiO2 can significantly enhance the resin-filler interface interaction, improve the compactness of the epoxy coating, and thereby improve the penetration resistance of the epoxy coating
.

The salt spray experiment shows that the salt spray resistance time of the nano-SiO2/epoxy composite coating can reach 720h
.
In addition, the dispersed nano-SiO2 particles in the composite coating can well alleviate the impact load on the coating and improve the mechanical properties of the coating
.
The experimental results show that the wear resistance of the nano-SiO2/EP composite coating is about 50% higher than that of the pure epoxy coating
.
However, the silanol groups on the surface of nano-SiO2 tend to agglomerate SiO2 itself, which leads to the failure of the composite coating to achieve the expected protective effect
.
Therefore, it is necessary to modify the surface of nano-SiO2 in order to improve its dispersibility in the epoxy matrix
.