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It is first and foremost an inorganic thixotropic rheological additive, followed by a functional filler; By overlapping nano rod-shaped crystals to form a three-dimensional network structure, the physical network does not rely on ion swelling, making it very suitable for water-based industrial paints, anti-corrosion primers, and bentonite HEUR、 Gas silicon is a complementary relationship.

Mechanism: high shear dispersion opens aggregation → nanorod dispersion; When standing still, the rod bodies overlap with each other to form a grid and lock the pigment filler; Under mixing/spraying and shearing, the mesh structure is disassembled, resulting in a decrease in viscosity and an improvement in flowability; Cutting and disappearing to quickly reconstruct the network, also known as thixotropy

1. Main functions: anti sinking, anti water separation, anti sagging

This is its biggest selling point and also the reason why many formulas use it to replace bentonite:

Electrolyte resistance, salt resistance, and wide pH tolerance: Anti rust primer, zinc powder containing, zinc phosphate, aluminum tripolyphosphate and other multi ion anti-corrosion systems, bentonite is easily broken by ions and viscosity collapse; Concave convex rods are minimally affected by electrolytes, making them less prone to delamination, hard precipitation, and water separation during thermal storage

Spray thick coating, bottom integrated paint: low viscosity during spraying, good atomization and leveling; Spray it to instantly restore viscosity, prevent sagging and thick edges

Addition amount: Water based industrial paint is generally 0.3% to 1.0%; Adding 2% -5% to the filling type will cause extinction

Comparison of Bentonite: Bentonite swells in layers and is sensitive to salt; Concave convex rod is a rod-shaped physical overlap, not afraid of salt, and has obvious advantages in anti-corrosion primer

2. Film density, water resistance, salt spray resistance, barrier

Rod shaped fibers are arranged in a staggered manner in the paint film, forming a maze barrier structure that extends the pathways for water, water vapor, and chloride ion penetration

Improve initial water and salt spray resistance, reduce foaming;

Shortcomings: The native concave convex rod itself has many pores and strong water absorption, which makes it difficult to disperse. Adding too much can increase the water absorption rate and worsen the whitening effect; Be sure to choose a surface modified low oil absorption model, control the amount of addition, and avoid adding too much

Compared to alumina: Alumina is a hard particle with a focus on wear resistance; Concave convex rod is a fiber mesh barrier that focuses on shielding and rheological properties

3. Auxiliary mechanics: wear-resistant, scratch resistant, and improved scrub resistance

Fibers are inserted into the resin film, similar to short fiber reinforcement, to enhance the toughness, abrasion resistance, and scrub resistance of the paint film; But the hardness improvement is far inferior to that of alpha alumina, don’t expect it to be a high wear-resistant topcoat. At the same time, it comes with a slight matte effect: the higher the dosage, the lower the gloss. High gloss topcoat should be added less or not, and primer and matte topcoat are more suitable

4. Assist in suspension, prevent pigment flocculation, and improve tank opening

The specific gravity is relatively light, and when combined with titanium dioxide, barium sulfate, zinc powder, and mica, it inhibits the settling of heavy fillers; After opening the can, it is not easy to cause hard sinking to the bottom, and it recovers well after mixing, with good shaking and melting properties. Can be compounded with HEUR and polyurethane thickeners: high shear viscosity in organic thickening tubes, low shear and anti settling in concave convex rod tubes, and a more comfortable rheological window.

5. Adsorption, insulation, flame retardant auxiliary

High specific surface area and adsorption capacity; Rod like stacking with micropores has a certain insulation effect; In the expansion type fireproof coating, it can assist the carbon layer skeleton to make the carbon layer denser, not the main flame retardant

Formula pitfalls

1. Dispersion is the threshold: Agglomerated concave convex rods are hard lumps that not only do not have thixotropy, but also cause particles, pinholes, and fog shadows; Need sanding, not just simple mixing;

2. High oil absorption value: adding more will increase the viscosity of the formula, consume lotion, and make the paint film brittle; High gloss paint should be used with caution as it can easily reduce gloss;

3. Native hydrophilicity: The unmodified version itself absorbs water, and when the dispersion is poor, the water resistance and water whitening resistance will deteriorate in reverse; Prioritize the use of silane modified and hydrophobic modified coatings for specialized purposes;

4. UV system should be used with caution: for cationic UV systems, attention should be paid to their metal impurities and alkalinity. Some mineral sources may quench the light and produce acid; Free radical UV can do a small amount of rheology, but it is not as stable as gas silicon;

5. Weak effect of oily system: unmodified concave convex rods are difficult to form a network in solvent paint. Oily systems generally prefer organic bentonite and gas-phase silica, and concave convex rods are only used as auxiliary materials

Material structure strengths and weaknesses

Concave convex rod like soil nano rod, physically overlapped salt resistant, anti-corrosion primer anti sinking, anti water separation, water-based system stable dispersion difficult, hydrophilic, extinction, average hardness

Organic bentonite layer swelling oily system, high thixotropy, salt ion viscosity collapse, easy to bubble

Gas phase silica nano amorphous particles, hydrogen bond network transparent, wear-resistant, UV paint, varnish expensive, slow recovery of thixotropy under high shear

Alpha alumina solid hard particles have high hardness, wear resistance, and improved water resistance by filling micropores. They have almost no thixotropy and are suitable for abrasion equipment

Suggestions for selection and implementation

· Waterborne zinc foundation make-up, zinc phosphate anti rust primer, and high ion anti-corrosion system: give priority to concave convex bar to solve the problems of viscosity reduction and water separation of bentonite when encountering salt;

High gloss topcoat: add less or no to avoid loss of gloss and haze;

Want to balance wear resistance and barrier properties: a small amount of rheology of the concave convex rod and a compound of alpha alumina;

Worried about water resistance and whitening: Choose a modified low oil absorption concave convex rod, controlled within 0.5%, and use nano alumina to block micropores.