Calcium Carbonate Boosts Weather Resistance and Stain Resistance in Architectural and Industrial Coatings
Calcium carbonate is categorized into heavy calcium carbonate (GCC) and light calcium carbonate (PCC). Ultrafine and nano calcium exhibit optimal performance, simultaneously enhancing the two core properties of weather resistance and stain resistance in wall paints, industrial coatings, and anti-corrosion paints.
Enhance the Weather Resistance of Coatings
Typical manifestations of weather resistance failure include UV degradable resin, powdering of paint film, loss of gloss, yellowing, cracking, and powdering. Calcium carbonate provides protection from three aspects: filling, barrier, and light stability.
Dense Filling, Reducing Paint Film Pores, Blocking Water and Oxygen Erosion
After pure resin film formation, there are tiny capillary pores, and rainwater, water vapor, oxygen, and acid rain can infiltrate the interior, hydrolyzing the resin, corroding the substrate, and accelerating aging. Calcium carbonate particles fill the micro pores of the coating substrate, making the coating surface denser and smoother.
The size of ultrafine calcium carbonate particles matches the resin voids, tightly stacked and filled, significantly reducing the porosity of the paint film; Form a dense shielding layer, reduce the penetration of moisture, acid and alkali, and atmospheric corrosive media, delay resin hydrolysis and paint film foaming and peeling, and improve long-term outdoor water and acid rain resistance. When ultrafine calcium carbonate (particle size<5 μm ) is applied in latex paint, it can reduce the surface roughness of the coating to below 0.3 μm, significantly improve the uniformity of light reflection, and achieve a glossiness of over 80 at a 60 °angle test.
Disperse Ultraviolet Radiation and Reduce the Rate of Resin Photodegradation
Organic resins such as acrylic acid, polyurethane, and alkyd are prone to chain breakage and pulverization when absorbing UV light; Calcium carbonate itself has weak UV absorption, but it has light scattering properties:
Micro/nano CaCO3 particles are uniformly dispersed in the paint film, refracting and scattering most of the ultraviolet rays, reducing the UV energy directly reaching the resin matrix; Reduce the rate of resin photocatalytic cracking, alleviate outdoor powdering, loss of gloss, and fading; Paired with titanium dioxide for synergistic shading, reducing the amount of high cost titanium dioxide used, while strengthening the overall weather resistance system.
By preparing porous calcium carbonate with a pore size of 100-300nm, the light scattering efficiency is improved by 300%. At the same time, directional alignment agents are added to arrange the sheet-like calcium carbonate in parallel, with a simulated refractive index of 2.45, which can achieve 60-80% substitution of titanium dioxide and meet the coverage requirements of high-end coatings. Currently, Nippon Paint has adopted this technology to achieve a coverage index of 28m ²/g and reduce costs by 35%.
Buffer PH, Resist Acid Rain and Atmospheric Pollutant Corrosion
Calcium carbonate is a weak base with acid-base buffering ability: when outdoor acid rain or industrial sulfides settle on the surface of the paint film, CaCO 3 preferentially reacts with acidic substances to protect the resin from acid corrosion; Prevent paint film from losing gloss, spots, and holes due to acid erosion, and extend outdoor service life.
Enhance the Mechanical Strength of Paint Film and Resist Aging and Cracking
Calcium carbonate, as a rigid inorganic filler, enhances the hardness and tensile modulus of the paint film. Under outdoor temperature changes, thermal expansion and contraction, as well as wind and heat exposure, pure soft resin is prone to brittle cracking; Inorganic calcium particles disperse and disperse internal stress, reducing the risk of paint film cracking and peeling; Reduce the powdering and peeling of the paint film after aging, maintain a complete and continuous protective film, and indirectly improve long-term weather resistance performance.
Enhance the Stain Resistance of Coatings
Anti pollution core logic: reduce surface porosity of paint film, improve surface hardness, optimize surface microstructure, and reduce pollutant adsorption.
Fill in the Micropores to Prevent Stains from Being Embedded
The micropores on the surface of the paint film are the main source of stain adsorption: oil stains, dust, ink, and mold spores can penetrate the pores and be difficult to erase. Ultra fine calcium carbonate fills the gaps in the resin, making the surface of the paint film smoother and less porous; Stains can only adhere to the surface of the paint film and cannot penetrate into the interior. They can be wiped clean with a damp cloth, significantly improving the scrub and stain resistance levels.
Improve the Surface Hardness of the Paint Film, Resist Scratches, and Adhere to Dirt
The pure resin paint film is relatively soft, and outdoor dust and sand friction can easily cause scratches. Scratch grooves are prone to accumulate dirt, and the more you use them, the dirtier they become. Calcium carbonate rigid inorganic particles enhance the Mohs hardness of paint film: reduce surface fine scratches, eliminate dirt grooves; Dust and dirt are not easily stuck on the surface, and can be cleaned by washing with rainwater.
Regulating Surface Micro Roughness to Reduce Pollutant Adhesion
Reasonable particle size combination of calcium carbonate can construct a low adsorption micro surface: the contact area between smooth and dense paint film and dust, organic matter stains is reduced, and the molecular adsorption force is weak; When rainwater infiltrates, it is easier for water to spread and carry away dirt, improving the hydrophobic and easy to clean effect.
Inhibit Paint Film Sticking and Reduce Dust Adsorption
Low quality resin is prone to softening and sticking after high temperature or long-term exposure to sunlight, and outdoor dust will firmly adhere to the sticky paint film. Calcium carbonate increases the glass transition temperature Tg of the paint film, reduces the tendency to soften and stick at high temperatures, and fundamentally reduces dust adhesion and scaling.
Performance Differences Among Different Categories of Calcium Carbonate
Nano Calcium Carbonate
The particle size is extremely small, with the strongest filling density and the greatest improvement in weather resistance and pollution resistance; At the same time, it enhances the flexibility of the paint film, making it less prone to cracking. It is the preferred choice for high-end exterior wall paint and water-based industrial topcoat.
Ultra Fine Precipitated Calcium Carbonate
Controllable crystal structure (spindle shaped, cubic), good dispersibility, high paint film flatness, scrub resistant and stain resistant, suitable for interior wall stain resistant paint.
Ground Calcium Carbonate
Low cost, large filling volume, mainly used for dense shielding, water-resistant and weather resistant foundation reinforcement, mostly used as primer and economical exterior wall paint; When the fineness is insufficient, the anti pollution effect decreases.
What are the Key Points of Supporting Use?
Adequate dispersion with dispersants is required, as particle aggregation can lead to the formation of pores, reducing both properties; Outdoor weather resistant systems require the use of light stabilizers, titanium dioxide, and calcium carbonate as synergistic shading fillers; Reasonably control the amount of addition: Excessive addition will reduce the flexibility of the paint film, make it prone to cracking outdoors, and actually weaken the weather resistance; The proportion of calcium carbonate filler in exterior wall coatings is generally 20% -45%; Surface activated calcium carbonate has better compatibility, denser film formation, and better water and stain resistance than ordinary unmodified calcium.
The weather resistance performance relies on multi-layer protection logic: a dense barrier layer isolates water, oxygen, and acid rain erosion, a light scattering mechanism delays resin powdering degradation, rigid fillers enhance the coating's ability to resist thermal expansion, contraction, and cracking, and alkaline components neutralize acidic atmospheric corrosion; The anti fouling performance optimizes the surface state from the root, fills in micro pores to avoid the deposition of stains, improves the hardness of the coating to reduce fine scratches that are prone to dirt accumulation, reduces interface adhesion, and allows stains to be wiped clean immediately, with long-term self-cleaning characteristics.