What is a catalyst?

2021-11-11   Pageview:143

A catalyst, also known as a catalyst, is a class of substances that can change the rate of a chemical reaction without consuming itself during the reaction. According to the definition proposed by IUPAC in 1981, a catalyst is a substance that changes the rate of a reaction without altering the standard Gibbs free enthalpy change of that reaction.

 

 

 

 

 

 

 

 

 

 

 

 

In addition to the general properties of silicone oil, the most characteristic of carbon-containing silicone oil is the chemical reactivity of organic functional groups. As the content of carbon functional groups in the silicone oil increases or decreases, the characteristics of methyl silicone oil can be adjusted to varying degrees to make up for the lack of methyl silicone oil performance in coating applications; and the attractive functional group Y can also give coatings Some special functions.

Fourth, silicone oil containing silicon functional groups
Silicone functional group-containing silicone oil (commonly known as active silicone oil) is a chemical structure of silicone oil that contains groups directly connected to silicon that are easily hydrolyzed, alcoholyzed and cross-linked. Its chemical structure is: R” is one H, one OR, one OH , —Reactive groups on silicon functional groups such as NH; R’=CHa or silicon functional groups;

m, n=0, 1, 2.3,…, they can be the same or different, and the size can be adjusted as needed.
The silicon functional groups in this type of silicone oil have strong reactivity and are easy to form chemical bonds with the surface of fillers and inorganic substrates. In addition, the introduction of silicon functional groups into silicone oil will also affect the characteristics of methyl silicone oil to varying degrees.
Application of Silicone Oil in Coatings

Control the flow of paint on the surface
To spread the coating on the surface of a solid substrate, its surface tension paraffin emulsion use must be less than the critical surface tension of the substrate. The surface tension of the coating is very different from the critical surface tension of the substrate or filler, or the solid dust particles or the substrate are contaminated. These conditions will cause the coating film to pinholes, fish eyes and shrinkage. If silicone oil suitable for the chemical structure is added, the surface tension of the coating can be adjusted, and the above-mentioned morbidity can be controlled. When the solvent in the paint volatilizes, the low-viscosity, low-density medium is brought from the bottom area to the surface to spread, the solvent volatilizes, the system thickens, part of the density increases and then settles back into the liquid paint, and then forms a vortex with the carried pigment. As the system dries, the coating will produce so-called Bernard swirl pockets. Silicone oil additives tend to accumulate on the surface of the system (air/liquid interface). Its chemical structure can be adjusted to make it have different surface activities and be used in different coatings. Liquid/solid, liquid/liquid or liquid/air interfacial tension can be adjusted to control the flow of the paint, which can prevent the above-mentioned coating film morbidity.

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