How does silicone enhance scratch resistance on the applied surface-Mingyi

How does silicone enhance scratch resistance on the applied surface

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Silicone resin enhances the scratch resistance of surfaces through the following methods:

Physical Isolation: After curing, the silicone resin coating forms a dense protective film on the surface of the object. This film effectively isolates the object's surface from direct contact with external hard objects, thereby reducing the possibility of scratches. For example, in automotive engine compartments, silicone resin coatings can withstand high-temperature environments for long periods and provide physical protection for circuits and other metal surfaces, preventing them from being scratched by foreign objects.
Buffering Effect: Silicone resin has a certain degree of flexibility and elasticity. When the surface of an object is subjected to external impact, the coating can act as a buffer, absorbing part of the impact energy and reducing the degree of scratching. For instance, in environments with significant vibrations, silicone resin coatings can also serve a vibration-reducing function, indirectly enhancing scratch resistance.

Inherent High Hardness: The molecular structure of silicone resin contains a large number of Si-O bonds, which have high bond energy, giving silicone resin high hardness and wear resistance. When it forms a coating on the surface of an object, it can significantly increase the surface hardness and enhance scratch resistance. For example, isocyanate-modified silicone resin compositions are used for hardening and scratch-resistant treatment of optical plastics, greatly improving the surface hardness and scratch resistance of optical plastics.
Formation of Crosslinked Network Structure: In some modified silicone resins, chemical reactions such as condensation reactions can occur with other substances, forming an organic-inorganic crosslinked network structure on the surface of the object. This further increases the hardness and wear resistance of the coating. For example, in silicone-alumina sol-modified methyl silicone resin wear-resistant films, the basic skeleton is composed of Si-O-Si, Si-O-Al, and Al-O-Al bonds. The addition of alumina sol improves the heat resistance and film hardness.

Lubrication Effect: Silicone resin has good lubricating properties. When applied to the surface of an object, it can reduce the surface friction coefficient, making the surface smoother. When the object comes into contact with other objects, the reduced friction force minimizes the occurrence of scratches. For example, a mixture of ultra-high molecular weight siloxane derivatives and surfactants, when applied to coatings for wood, metal, or plastic, significantly reduces static and dynamic friction coefficients, improving anti-blocking properties and increasing scratch and wear resistance.
Improving Surface Microstructure: During the curing process of the silicone resin coating, it can fill in the tiny pits and uneven areas on the surface of the object, making the surface smoother. This further reduces the friction coefficient and enhances scratch resistance. For example, although the addition of alumina sol in silicone-alumina sol-modified methyl silicone resin wear-resistant films makes the film surface uneven, the formula and process can be optimized to improve the surface microstructure and reduce the friction coefficient.

Chemical Bonding: The reactive groups in silicone resin can chemically bond with the substrate of the object's surface, forming a strong adhesion. This chemical bonding not only prevents the coating from falling off but also enhances the synergistic effect between the coating and the substrate, improving the overall scratch resistance. For example, silicone resin emulsions can form a stable three-dimensional network structure with weather resistance and hydrophobicity on mineral building substrates and coating surfaces. This structure can be firmly attached to the mineral substrate through strong chemical bonds.
Physical Adsorption: When the silicone resin coating cures on the surface of an object, it can physically adsorb onto the substrate. This physical adsorption increases the contact area and bonding force between the coating and the substrate, making the coating more stable. Thus, when subjected to external forces that cause scratching, the coating is less likely to be stripped away, maintaining its protective function for the substrate.

Adding Additives: Introducing specific additives into silicone resin, such as scratch-resistant aids and adhesion enhancers, can further improve the scratch resistance of the coating. For example, scratch-resistant glue is made by mixing scratch-resistant main glue, scratch-resistant aids, and diluents. The scratch-resistant main glue is a polyester polyurethane resin, and the scratch-resistant aid is a cyanate ester curing agent. The scratch-resistant layer formed after coating and curing has a good scratch-resistant effect.
Composite Modification: By compositely modifying silicone resin with other resins or materials, the advantages of various materials can be integrated to prepare coatings with more excellent scratch-resistant properties. For example, through thiol-ene click reactions, a UV-curable transparent coating is prepared using thiol silicone resin and polyurethane-acrylate. The resulting coating has high hardness, good scratch resistance, thermal stability, adhesion, and water resistance.