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Yuan Lei's Little Knowledge | Application of Nano Calcium Carbonate in Adhesive

Release time:

2024-01-29 09:34

Nano calcium carbonate refers to the functional inorganic filler with a particle size of 1-100nm, which is widely used in rubber, plastic, paper, ink, coating, sealant and adhesive, medicine, toothpaste, food and other fields. The following small band everyone to understand the application of nano calcium carbonate in adhesive.

 

 

Adhesives are natural or synthetic, organic or inorganic substances that can connect two or more parts or materials together through the adhesion and cohesion of the interface, collectively referred to as adhesives. In short, an adhesive is a substance that binds the adherend together through bonding.

As one of the important fillers of adhesives, nano-calcium carbonate not only has low price, but also has good compatibility with adhesives, which can accelerate the crosslinking process of adhesives, improve thixotropy, improve adhesion, tensile strength and reinforcing effect.

 

The technical requirements of nano calcium carbonate used in adhesives mainly include:

Oil absorption value:Oil absorption value is an index that silicone rubber manufacturers pay close attention to, which directly affects the wettability of nano calcium carbonate in rubber. Higher nano calcium carbonate has advantages in mechanical properties and thixotropy, but it will lead to colloid viscosity, consume more additives and increase production cost. Different manufacturers' formulation systems have different requirements on oil absorption value of nano calcium carbonate, depending on the specific situation.

Crystal Form:Generally cubic or rhombic hexahedron, but also need to adapt to the technical requirements of the product and production equipment.

Particle size:Generally controlled in 60 ~ 100nm, if the particle size is too large, it will reduce the mechanical properties of the glue, and at the same time will lead to the deterioration of the thixotropy of the glue, easy to sag; the particle size is too small, the agglomeration of nano calcium carbonate is serious, the production will make kneading difficult, but also easy to lead to poor dispersion, the colloid surface pitting.

 

 

Moisture:Nano calcium carbonate applied to adhesives requires the lower the moisture content, the better, generally less than 0.5%. If the moisture content of nano calcium carbonate is higher, the hydroxyl groups on its surface increase, and the aggregates show a tendency of mutual agglomeration. Under the action of base glue, a three-dimensional network is formed, which increases the viscosity of the glue, resulting in a longer mixing time, resulting in a decrease in yield and an increase in energy consumption. Excessive water will also react with glue-making additives to generate particles, resulting in poor dispersion of products, the emergence of particles. In the polyurethane adhesive, containing more isocyanate groups prone to hydrolysis, the generation of CO2 is the product surface foaming phenomenon.

pH:Calcium carbonate is a weak alkali salt with a pH value of 8-10. Nano-active calcium carbonate surface coating agents are generally weak organic acids or organic acid salts, which have a certain neutralization effect on their surfaces. In the production process, the phenomenon of calcium carbonate returning to alkali is very common. If the alkali is not well treated, it will generate water with the acidic components in the rubber compound to hydrolyze siloxane to produce inorganic particles, not only make the appearance of the product worse, but also affect its mechanical properties.

Specific surface area:Since the particle size is controlled at 60 ~ 100nm, the corresponding specific surface area should be controlled at 20 ~ 25m 2/g. When the specific surface area is too large, although the reinforcing effect is enhanced, it will also lead to poor extrusion performance of the glue and affect the dispersion effect of the product.

 

With the deepening of research and the maturity of technology, nano calcium carbonate will play a greater role in the field of new adhesives.

Calcium carbonate, nano, requirement, variation, particle size, cause, general, moisture, effect

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