Application of dimethyl silicone oil in silicone sealant

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With the rapid development of China's industrial and construction industry, silicone sealant as a new field inlay, bonded joints, room temperature curing elastic sealing materials, its application of the field more and more extensive. Silicone sealant is composed of five main items: base polymer, cross-linking agent, filler, coupling agent, plasticizer and so on.

　　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 a plasticizer for silicone sealants in order to reduce costs. The use of a large number of white oil instead of silicone oil in the silicone sealant, the consequence is that it greatly reduces the performance of many silicone sealants, such as weather resistance, high and low temperature resistance, high performance of silicone sealants performance. This makes the original high durability, high performance of silicone sealant performance and service life is greatly reduced. Such white oil sealant for engineering, poor aging resistance, volume shrinkage, very easy to appear sealant cracking, brittle hard and other phenomena, affecting the curtain wall sealing and appearance and even cause serious engineering accidents.

　　Dimethyl silicone oil is a colorless and tasteless transparent liquid, its molecular formula is mainly composed of dimethylsiloxane chain segment, the structure is very similar to the base polymer of silicone sealant, so it has good compatibility with the base rubber. Dimethyl silicone oil is odorless, non-toxic, non-volatile and has good chemical stability. It has a wide temperature range with little change in viscosity, high boiling point and low freezing point, and can be used as a liquid in a wide range of temperatures from -50 to 200°C for a long time. The electrical properties of dimethyl silicone oil are good, especially in various frequency ranges when the rate factor is small. Its surface tension is low and its shear resistance is excellent. Based on these excellent properties, dimethyl silicone oil is particularly suitable for use as a plasticizer and diluent in silicone sealants.

　　In the application of silicone sealants, considering the needs of construction, often need to adjust the viscosity of the sealant, reduce the viscosity of the adhesive, improve the construction fluidity and lubricity of the sticky material, so the choice of dimethyl silicone oil and other as plasticizers. At the same time, the addition of plasticizers can also improve the overall performance of the cured adhesive layer, improve the impact resistance of the bonding joint, fatigue resistance, etc..

　　On the other hand, the addition of plasticizers will also have an impact on the other properties of silicone sealants. Generally, as the amount of plasticizer increases, the tensile strength of silicone will gradually decrease and the elongation at break will gradually increase. The reason for this is that the addition of non-reactive dimethyl silicone oil plasticizer reduces the number of connection points between polymer molecular chains, making the cross-link density decrease, which ultimately leads to a reduction in tensile strength. In addition, the decrease in crosslink density reduces the stiffness of the three-dimensional structure and molecules tend to slip, resulting in an increase in elongation at break. In addition, it was also found that with the increase of plasticizer dosage, silicone adhesive strength generally decreased. The reason for this is that the plasticizer used is a non-reactive plasticizer, which acts as a dilution to the silicone active molecules and causes a decrease in the number of active groups per unit volume.

　　In order to adapt to the future development of the building on a larger scale and maintain the market growth of silicone sealants, enterprises should continuously improve product quality, enhance the ability to sustain development, and jointly adhere to industry self-regulation and standardization of the market. Dimethyl silicone oil as a plasticizer has been widely used in silicone sealants, to white oil instead of silicone oil as a plasticizer will make the performance of silicone sealants significantly reduced. In engineering use, the use of white oil sealant should be rejected, choose silicone oil sealant.More information click here: dimethyl silicone oil