Summary of the Production Process in the Silicone Sealant Factory

Summary of the Production Process in the Silicone Sealant Factory
In modern factories, a sophisticated production process is quietly operating, converting various raw materials into high-performance silicone sealants. This process integrates the essence of chemical technology and engineering techniques. 

Silicone sealant, as an important polymer material, is widely used in fields such as building sealing, electronic packaging, and industrial manufacturing due to its excellent weather resistance, high-temperature and low-temperature resistance, and elasticity. The production process of this material is crucial to product quality. Leading global enterprises are continuously improving product quality and production efficiency through automated and continuous production technologies. 

01 Raw Material Preparation and Formula Design
The first and foremost step in the production of silicone sealant is the meticulous preparation of raw materials and the precise formulation design. The main raw materials include 107 silicone rubber, fillers, crosslinking agents, coupling agents, and catalysts, etc. 

The quality of these raw materials directly determines the performance of the final product, so strict quality inspection and control are necessary. 

For neutral transparent silicone sealant, the moisture content in key raw materials such as aerogel silica needs to be precisely controlled. Research shows that its mass fraction should not exceed 0.05%. 

In terms of formula design, the raw material ratios need to be adjusted for products with different applications. For example, ketoxime type silicone sealant adopts a high-temperature end sealing process, which can significantly reduce the amount of crosslinking agent and alleviate the oil seepage phenomenon. 

The formula designer needs to precisely calculate the proportions of various raw materials based on the performance requirements of the product, ensuring that the product has good extrudability, curing speed and final mechanical properties. 

02 Mixed Stirring Process
Mixed stirring is the core step in the production of silicone sealant, aiming to thoroughly mix various raw materials to form a uniform gel. Modern factories usually use powerful dispersers as the main mixing equipment. 

This equipment integrates the functions of dispersion, stirring and mixing. It is equipped with multiple agitators that rotate at high speed around their own axes at different speeds, causing the materials to undergo complex movements within the vessel and being subjected to intense shearing and kneading. 

During the mixing process, precise control of temperature and time parameters is required. For ketoxime type silicone sealant, the high-temperature end-capping process needs to add a crosslinking agent at a temperature of 120℃ and -0.85 MPa for end-capping. 

Vacuum dehydration is a crucial step in the mixing process. Through the vacuum system, it removes the moisture from the raw materials and the bubbles introduced during the mixing process, ensuring the compactness and stability of the product. 

03 Continuous Production Process
To address the issues of unstable performance, frequent equipment cleaning, and high energy consumption in traditional batch production, leading enterprises in the industry have begun to adopt continuous production processes. 

Continuous production is carried out by using a two-stage high-speed disperser in combination with a twin-screw extruder. By controlling the screw machine speed at 550 r/min and the outlet pressure at 1.0 MPa, continuous production is achieved. 

This process can effectively reduce losses, save production costs, and enhance the consistency of product performance. 

The vacuum level of the continuous production line needs to be maintained above -90 kPa to ensure the effective removal of bubbles and volatile substances. 

04 Automation and Intelligence in Production
With the advancement of technology, automation and intelligence have become the trend in silicone sealant production. Hubei Tongcheng High-tech Materials Company has introduced a fully automated production line for mixed-color and neutral transparent sealant materials, which is the most advanced in the country. 

This production line can achieve full automation throughout the process of feeding, production and packaging. It features precise measurement, high production efficiency, large production capacity and no loss or waste. 

What's more advanced is that some enterprises have achieved remote control of production. Technicians can remotely control the equipment through computer connections from different locations, significantly enhancing production flexibility and emergency response capabilities. 

The automated production line not only ensures stable product quality, but also reduces the variability caused by manual operations, thereby further safeguarding the physical health of the production staff. 

05 Defoaming and Post-Treatment Process
The mixed silicone sealant needs to undergo defoaming treatment to remove the air bubbles introduced during the mixing process. The defoaming process is usually carried out in a vacuum system, where the bubbles are completely expelled through a negative pressure environment. 

For high-grade silicone sealant, it also needs to undergo further processing through a three-roll grinding machine or a twin-screw mixer to ensure that the fillers and pigments are evenly dispersed. 

The degassed silicone sealant needs to undergo cooling treatment. For example, for ketoxime type silicone sealant, after the end sealing, it needs to be cooled down to below 50℃ through a condenser, and then coupling agent and catalyst should be added. 

The process control at this stage directly affects the surface condition and internal structure of the product. Any negligence could lead to the appearance of bubbles or layering in the product. 

06 Packaging and Wrapping Process
Packaging is the final step in the production of silicone sealant. Different packaging forms are adopted based on the product's application. Common packaging equipment includes semi-automatic hard tube packaging machines, fully automatic hard tube packaging machines, and fully automatic soft packaging machines, etc. 

The packaging process requires controlling the environmental conditions to prevent the products from prematurely curing due to moisture in the air. For single-component silicone sealant, this step is particularly important. 

Modern factories usually have multiple packaging lines. For instance, a medium-sized production line can be equipped with 4 sets of rigid packaging machines or 2 sets of flexible packaging machines to meet the packaging requirements of different products. 

The packaged products still need to be labeled and date-stamped, then stored in the warehouse, and will be dispatched only after the quality inspection results are confirmed to be合格. 

The production process of silicone sealant is still constantly being innovated, shifting from batch production to continuous, automated and intelligent methods. With the application of new raw materials and new processes, the production of silicone sealant in the future will be more efficient, environmentally friendly and controllable, providing higher-quality products for the construction and industrial sectors.