There are many types of silica sol with significant performance differences. How to choose the right silica sol for oneself

Recently, many fans and friends have been inquiring about silica sol, but there are many types of silica sol with significant performance differences. It is not easy to choose a suitable silica sol for oneself. In order to facilitate everyone to quickly find the silica sol that suits their needs, silica sol is now classified according to its characteristics and respective application scenarios, hoping to be helpful to everyone.

1、 Classified by stabilizer type

1. Sodium type silica sol: The stabilizer is sodium hydroxide, with a pH value generally between 8.5-10.5. It is characterized by the lowest cost, good colloidal stability, long storage period, and contains sodium oxide impurities. It is suitable for ordinary refractory materials, precision casting, ordinary water-based inorganic coatings, papermaking, textiles, ordinary CMP polishing liquids, etc.

2. Potassium type silica sol: The stabilizer is potassium hydroxide, with a pH value generally between 8.5-10.5. It is characterized by extremely low sodium ion content, excellent colloidal stability, and almost no alkali return or whitening. It is suitable for high-end floor curing agents, dark ceramic glazes, high weather resistant inorganic coatings, refractory binders, precision casting, water-based inorganic coatings, silicon fertilizers, ordinary CMP polishing liquids, etc.

3. Ammonium type silica sol: The stabilizer is ammonia water or organic alkali, with a pH value generally between 8.5-10. It is characterized by almost no alkali metals, no salt precipitation or whitening, excellent high-temperature refractoriness, and complete decomposition of ammonium after calcination without residual metal ions. It is suitable for high-end corundum refractory materials, ceramic polishing liquids, electronic coatings, light and dark inorganic topcoats, high-end precision casting, catalyst carriers, etc.

2、 Classified by PH

1. Alkaline silica sol: The pH value is generally between 8.5-10.5, with sodium, potassium, and ammonia types. Colloidal particles are highly stable in alkaline environments and can form dense silicate films with outstanding film-forming and bonding properties. They are widely used in refractory materials, precision casting, anti-corrosion coatings, architectural coatings, ceramic coatings, catalyst carriers, fire-resistant glass, CMP polishing liquids, and other fields.

2. Neutral silica sol: The pH value is generally between 6-8, and its stability is poor. It will not cause abnormal curing of acid and alkali sensitive resins and pigments. It can be used for precision casting, coatings, refractory binders, CMP polishing, catalyst carriers, etc.

3. Acidic silica sol: pH value is generally 2-4, with poor stability and extremely low alkaline metal content. It can be used for mirror polishing of ceramic tiles, rock slabs, CMP polishing of semiconductor materials, water-based matte ceramic topcoat, coatings, precision casting, refractory materials, etc.

3、 Classified by particle size

1. Small particle size silica sol 5-20nm: with a large specific surface area, strong adhesion, strong ability to fill micropores, fine extinction, and transparent paint film, it is widely used in refractory binders, matte coatings, ceramic coatings, catalyst carriers, etc.

2. Medium particle size silica sol 20-40nm: It is a commonly used mainstream specification in the industry and can be used for precision casting, refractory materials, coatings, general CMP polishing solutions, and catalyst carriers.

3. Large particle size silica sol 40-100nm: Matte floor solution with fast polishing rate suitable for rough polishing processes of substrates such as sapphire and silicon wafers, as well as other CMP polishing solutions, fire-resistant glass, high-end matte coatings, etc.

4. Composite particle size silica sol: After compounding large and small particles, it can achieve both filling density and extinction effect, and can be used for high-end inorganic coatings, CMP polishing solutions, etc.

4、 Classified by solid content

1. Low concentration: The solid content is generally 10% -20%, used for impregnation sealing, dilution of polishing solution, small sample experiments, etc.

2. Standard concentration: The solid content is generally 30% -40%, which is mainstream in the market and widely used in refractory materials, precision casting, catalyst carriers, textiles, papermaking, coatings, CMP polishing solutions, etc.

3. High concentration: The solid content is generally 45% -65%, with low transportation costs, and can be used for high solid inorganic coatings, refractory materials, fire-resistant glass, CMP polishing solutions, etc.

5、 Classified by modified raw materials

1. Modification of silane coupling agent: coupling agent types include KH550, KH560, KH570, KH580, KH171, etc. Silane coupling agent is an organic inorganic interface bridge, and the modified silica sol can be well compatible with lotion, resin and other organic substances, and can be used in fields such as glass fiber reinforced plastics, electronic sealing rubber, tire rubber, water-based paint, CMP polishing fluid, etc.

2. Alkyl silane modification: There are MTMS and MTES, etc. Alkyl silane is a pure hydrophobic modification without reactive organic functional groups. The modified silica sol is strongly hydrophobic, hydrophobic, and densifies the paint film, reducing water absorption, anti fouling, anti whitening, and freeze-thaw resistance. It can be used in waterproof coatings, self-cleaning exterior wall coatings, concrete, stone hydrophobic protection and other fields.

3. Water based polymer modification: There are polyvinyl alcohol, cellulose ether, polyethylene glycol, water-based polyurethane, etc., mainly to solve the problems of brittle, easy to crack, and poor workability of silica sol paint film. It is often used in combination with silane to improve film formation, toughness, rheology, and crack resistance.

4. Inorganic modifiers: There are aluminum, boron, zirconium metal ions or their compounds, etc. These substances are inorganic phase modifiers that do not introduce organic functional groups, improve the storage stability, high temperature resistance, hardening, and fire resistance of silica sol, and can be used for fireproof coatings, refractory materials, casting binders, interior wall primers, etc.

6、 Classified by metal impurity content

1. Ordinary silica sol: With high metal impurities and a total metal ion content of>1000ppm, it is inexpensive and has the highest proportion of products on the market. It is suitable for low-end fields without special purity requirements and can be used for precision casting, ordinary refractory material binders, ordinary coatings, fireproof glass, ordinary CMP polishing liquids, etc.

2. High purity silica sol: With low metal impurities, the total number of metal ions is generally less than 100ppm, and the price is relatively high. It is used in fields that are sensitive to metal ions, mainly for catalyst carriers, food processing, cosmetics, some high-end coatings, chromatographic fillers, silicon wafer polishing and other demanding scenarios.

3. Ultra pure silica sol: With very low metal impurities, the total number of metal ions is generally less than 1ppm and sodium ions are less than 200ppb. It is expensive and used in fields that are highly sensitive to metal ions, mainly for high-end catalyst carriers, high-end inorganic coatings, high-end precision ceramics, optical glass, quartz devices, wafer coatings, photovoltaic coatings, chip CMP polishing, chip packaging, etc.