With the promotion of silicone sealant production technology and the intensification of competition among enterprises, some manufacturers use white oil instead of dimethyl silicone oil as the plasticizer for silicone sealants in order to reduce costs. Using a large amount of white oil instead of silicone oil in the silicone sealant has the consequence that many properties of the silicone sealant are greatly reduced, such as weather resistance, high and low temperature resistance, and the performance of high-performance silicone sealants. This greatly reduces the performance and service life of the originally high-durability and high-performance silicone sealant. After this kind of white oil sealant is used in engineering, it has poor aging resistance and large volume shrinkage.

Dimethicone is a colorless, odorless and transparent liquid. Its molecular formula is mainly composed of dimethylsiloxane segments. Its structure is very similar to the base polymer of silicone sealant, so it has good compatibility with base glue. Dimethicone is odorless, non-toxic, non-volatile, and has good chemical stability. It has small viscosity change in a wide temperature range, and has high boiling point and low freezing point. The electrical properties of dimethyl silicone oil are good, especially in various frequency ranges, the time rate factor is small. It has low surface tension and excellent shear resistance. Based on the above excellent properties, dimethicone is especially suitable for use as a plasticizer and diluent in silicone sealants.

In the application of silicone sealants, considering the needs of construction, it is often necessary to adjust the viscosity of the sealant, reduce the viscosity of the adhesive, and improve the construction fluidity and lubricity of the adherend. plasticizer. At the same time, the addition of plasticizer can also improve the comprehensive performance of the cured adhesive layer, and improve the impact resistance and fatigue resistance of the bonded joint.

On the other hand, the addition of plasticizers will also affect other properties of the silicone sealant. Generally, with the increase of the amount of plasticizer, the tensile strength of silica gel will gradually decrease, and the elongation at break will gradually increase. The reason is that the addition of the non-reactive dimethicone plasticizer reduces the number of connection points between the polymer molecular chains, which reduces the cross-linking density and ultimately reduces the tensile strength. In addition, the reduction of crosslinking density reduces the stiffness of the three-dimensional structure, and the molecules easily slip, resulting in an increase in elongation at break. In addition, it was also found that as the amount of plasticizer increased, the adhesive strength of the silicone rubber generally decreased. The reason is that the plasticizer used is a non-reactive plasticizer, which dilutes the active molecules of the silica gel and reduces the number of active groups per unit volume.

In order to adapt to the larger-scale development of construction in the future and maintain the market growth of silicone sealants, enterprises should continuously improve product quality, enhance sustainable development capabilities, and jointly adhere to industry self-discipline and standardize the market. As a plasticizer, dimethyl silicone oil has been widely used in silicone sealants. Using white oil instead of silicone oil as a plasticizer will greatly reduce the performance of silicone sealants. In engineering use, white oil sealant should be rejected and silicone oil sealant should be selected.