Levasil® colloidal silica
Functionality
We help make the ordinary extraordinary
Levasil® colloidal silica aqueous dispersions are available in a variety of grades
These are determined by particle size, structure, concentration, pH, surface charge and surface modification. It is a versatile, inorganic material, also known as silica sol, that can be used for many different industrial functions.
Abrasion and scratch-resistance is key in the waterborne coatings industry. The reason is that abrasion and scratch-resistant coatings last longer and require less frequent recoating. And, in some applications, help protect substrates from corrosion.
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Coating formulations made with colloidal silica help surfaces resist abrasions and scratches in two principal ways:
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Levasil® colloidal silica can be added to waterborne adhesive formulation to improve heat resistance and shear strength and to reduce drying time. In addition, colloidal silica can be used to adjust the viscosity without needing additional thickeners.
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Adhesion describes the tendency for dissimilar surfaces to stick to one another. Colloidal silica dispersions can improve the molecular interaction of waterborne coatings and adhesives with substrates, resulting in better adhesion, in several ways:
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Coated surfaces or layers, especially tacky or those recently coated, have a tendency to stick together. When this happens, they are often ruined. Preventing this from happening is called anti-blocking.
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When added to coating formulations, colloidal silica gives surfaces an anti-blocking capacity for two main reasons:
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Anti-soiling is very important in exterior coatings. The better these coatings resist soiling, the fresher and cleaner they look. And when cleaning is required, dirt is easily removed by rinsing.
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Dirt is attracted to surfaces that are hydrophobic, in other words, afraid of water. When surfaces are more hydrophilic, or water loving, dirt is repelled. This is called anti-soiling. Silica particles in colloidal silica dispersions have many surface hydroxyl-silanol groups, which are very hydrophilic. Thanks to the enrichment of colloidal silica particles in the coating surface you get a less tacky and more hydrophilic surface. This means that water forms a film on the surface, allowing dirt to run off with the water. |
Binding is the process of drawing and holding together materials to form a cohesive whole. Levasil® colloidal silica is the perfect binder in a number of different binding applications.
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The small size of Levasil® colloidal silica particles allows them to be used as a dispersant in some applications. This is particularly useful to formulate highly concentrated, long-term stable, surfactant-free dispersions of pigments.
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Dispersing is the creation of a uniform and consistent liquid formulation that resists settling or clumping through improved separation of particles. By improving the separation of particles, a uniform and consistent liquid dispersion that resists settling or clumping is created. The particles act as a physical spacer, preventing re-agglomeration, and help keep the dispersed material separated by adsorbing on the surface. |
Flocculation is the process of removing unwanted particulates (solids) from liquid, which are otherwise difficult to filter or settle out. Flocculation is common in refractory fiber bonding, the food and beverage, and water treatment industries.
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When colloidal silica is introduced to a liquid, the liquid becomes destabilized electrically. Solids with opposite surface charges are attracted to the colloidal silica particles, forming clusters or clumps called flocs. These flocs then float to the top (creaming), settle to the bottom (sedimentation), or are readily filtered from the liquid. |
Abrasion and scratch-resistance is key in the waterborne coatings industry. The reason is that abrasion and scratch-resistant coatings last longer and require less frequent recoating. And, in some applications, help protect substrates from corrosion.
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This higher coefficient of friction is produced in two primary ways:
After drying, the surfaces in both cases are populated by the small silica particles, increasing their surface roughness and thereby the coefficient of friction. |
Gelling is the process by which a liquid become viscous and eventually a solid. With this functionality Levasil® colloidal silica is a valuable tool in ground consolidation and when producing gel and AGM batteries.
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Colloidal silica particles form gels by linking together along siloxane bridges in branched chains, resulting in a contiguous gel network. The formed network prohibits liquid transport within the gel volume, but can still retain a liquid component through capillary action. In battery applications, sulfuric acid is retained in the gel; while in ground consolidation, it is water that is retained. |
The efficiency with which images and type can be printed onto a surface is referred to as a medium’s printability. Improved printability means that ink colors and images hold to surfaces better and are less likely to penetrate the material below.
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In the simplest of terms, when Levasil® colloidal silica is used in coatings applied to both paper and plastic films, it enhances printability by improving surface hydrophilicity, resulting in better retention of waterborne inks. For inkjet paper, positively charged (cationic) colloidal silica is used in coating formulations. When allowed to dry, the silica agglomerates with a small amount of binder to create a porous coating with excellent dye fixing properties. |
Levasil® colloidal silica can be used to physically and chemically polish various substrates to create nearly defect-free, flat surfaces. Our aqueous dispersions of colloidal silica is commonly used with polishing pads to smooth and polish uneven surfaces. This is the preferred process in the manufacture of integrated circuits and high performance substrates.
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The ideal balance between the surface removal rate and surface roughness, or waviness, is achieved by selecting the proper silica particle with respect to: size, morphology, size distribution, concentration, pH and impurity level. |
News and events
For more information about our Levasil® colloidal silica products, please contact our experts. We look forward to hearing from you.
If you prefer to call us you can reach us at:
China, Shanghai: +86 21 22205000
Brazil, Jundiaí: +55 11 45894800
Germany, Cologne: +49 221 995850
India, Mumbai:+91 22 6842 6700
Japan, Tokyo:+81 356436001
Singapore: +65 6635 5327; 6635 5203
Sweden, Bohus: +46 31 587000
Taiwan - Greater China, Taichung: +886 4 23270520
USA, Houston: +1 312 3206109
Levasil® is a registered trademark of Nouryon in several countries worldwide.
