The role of sealant in energy-saving door and window glass
The importance of building energy efficiency
Energy is an important material basis for human survival and production. In recent years, my country's economic construction has achieved world-renowned achievements, and at the same time, huge energy consumption has also become the focus of the world's attention. The shortage of energy supply and the ecological and environmental problems caused by energy consumption will seriously hinder economic development and affect our living environment.
According to data released by the National Bureau of Statistics recently, China's total energy consumption in 2011 rose to 3.48 billion tons of standard coal. Among them, building energy consumption accounts for more than 28% of the country's total energy consumption. Building energy consumption has shown a sharp upward trend with the continuous increase of the total number of buildings and the improvement of living comfort. According to the current development forecast of building energy consumption, by 2O2O, the proportion of my country's building energy consumption in the total energy consumption of the whole society will reach about 35%, surpassing industrial energy consumption and becoming the first field of energy consumption.
The promotion of building energy conservation is mainly to improve the thermal insulation performance of the building envelope. Among the major components of the building envelope, the curtain wall and doors and windows have poor thermal insulation, which are the main factors affecting the indoor thermal environment and building energy efficiency. Therefore, increasing the thermal insulation performance of doors, windows and curtain walls and reducing energy consumption are important links to improve the quality of indoor thermal environment and improve the level of building energy conservation.
The infrared spectrum of ordinary doors and windows shows that a large amount of heat is radiated to the outside through the glass. The infrared spectrum of energy-saving doors and windows shows that much less heat is radiated through the door and window glass. The colors in the picture are green and blue respectively, which achieves the effect of thermal insulation. The energy-saving effect of energy-saving doors and windows is achieved through the integrity of the entire door and window system, and the sealant material is an indispensable part of the entire system.
Application of silicone sealant in building energy-saving doors, windows and curtain walls
The application of silicone sealant in building doors, windows and curtain walls mainly includes three aspects: secondary sealing of insulating glass, curtain wall structure, weather-resistant sealing and waterproof and weather-resistant sealing of doors and windows. The quality of silicone sealant not only affects the safety of the entire building's door, window and curtain wall structure, but also affects whether the building meets the requirements of energy conservation and environmental protection.
The insulating glass unit has outstanding thermal insulation performance and is an important material to improve the energy-saving level of doors and windows. It has been widely used in buildings in recent years. The dry gas inside the insulating glass makes the insulating glass have the functions of sound insulation, heat insulation, anti-condensation, reducing cold radiation and enhancing glass safety.
Among the two seals of the insulating glass structure, the first seal is to ensure low water vapor penetration, and hot-melt butyl glue is generally used. The function of the second sealant is to ensure the integrity of the glass unit structure, and the silicone sealant is generally selected. In the case of insulating glass for structural assembly, a silicone structural sealant must be selected.
The service life of an insulating glass unit critically depends on the functional retention of the sealing structure, and an excellent edge seal must have the following characteristics:
1. Durable resistance to environmental factors, especially heat, water or moisture and ultraviolet rays;
2. Sufficient structural strength to withstand displacement, so that the change of the first sealant water vapor channel is minimal;
3. Low moisture and gas permeability under service conditions.
If the silicone sealant can not meet the above requirements, then the sealed insulating glass is likely to have fogging phenomenon during the service period, resulting in failure and loss of energy-saving effect.
The HBZ/T0O1-2OO7 "Insulating Glass Production Regulations" formulated by China Building Glass and Industrial Glass Association was released and implemented on July 1, 2007. Most domestic glass manufacturers strictly follow the standard requirements for raw material selection and construction of insulating glass. However, in the fierce market competition, there are still some sealant manufacturers in the industry who ignore the product quality. In order to reduce production costs and unilaterally pursue short-term benefits, "white oil" is added to insulating glass sealants. Because "white oil" is cheap and can make the sealant look better after curing, some irresponsible manufacturers even use it as a selling point to promote and promote products to users.
With the passage of time, a series of serious quality problems brought about by adding "white oil" insulating glass sealant gradually emerged, the outstanding performance is: the service life of insulating glass made of this kind of sealant is generally short, and there is a lot of water leakage , air leakage and condensation, etc., the more serious is that the "white oil" in the insulating glass glue penetrates into the first sealant, that is, the hot-melt butyl sealant. "Tears" phenomenon.
Curtain wall structure, weather sealing and door and window sealing
The curtain wall is composed of panels and structures. It belongs to the outer protective structure of the building. It hangs outside the main structure and can deform with the main structure to transmit the force to the main structure. As a symbol of modern architecture, curtain walls, especially glass curtain walls, have been more and more widely used around the world. The use of large-area glass panels provides buildings with good lighting performance and aesthetic design, but it is also a weak link in energy saving. .
In the past, the energy efficiency of energy-saving doors, windows and curtain walls in the industry focused on how to choose insulating glass with lower thermal conductivity, how to improve the inert gas retention rate of gas-filled insulating glass, and how to design the cavity structure of the profile to reduce heat conduction\Select glue injection insulation Heat or nylon insulation strips, etc., and the choice of silicone sealant has not received enough attention. In fact, the quality of silicone sealant has a very important impact on the performance of energy-saving doors, windows and curtain walls. First, the good and lasting adhesion of silicone structural sealants to curtain wall panels is the guarantee of curtain wall safety, while silicone weather-resistant sealants directly affect the air tightness and water tightness of the entire curtain wall doors and windows. In fact, the sealing failure The resulting energy loss is far greater than the savings that can be achieved by choosing better glass and profiles. No one can imagine talking about building energy conservation and environmental protection in a building that leaks air and rain.
Silicone weather-resistant sealant products are mainly used in weather-resistant and waterproof sealing of curtain wall panels. The outstanding anti-ultraviolet aging properties of silicone products make them excellent in this application. However, if the material is improperly selected, such as the selection of inferior silicone sealant, in addition to its own weather resistance failure, it will sometimes penetrate into the first seal of the insulating glass, causing the butyl glue to be dissolved, thereby causing the insulating glass The failure is shown in Figure 6. Such an example often occurs in practical projects. Similarly, poor quality silicone sealant will also cause poor adhesion of the curtain wall joints, resulting in water leakage from the curtain wall joints and further damage to the interior decoration. The damage is shown in Figure 5 and Figure 8. In actual engineering, when the joint size of some larger plates changes, the displacement capacity of ordinary sealant products will be difficult to meet the requirements, resulting in fatigue cracking as shown in Figure 7. In response to the high requirements for the displacement capacity of silicone sealants for large-sized plates, Sibao Company has launched targeted 50-level displacement capacity silicone weather-resistant sealants and special sealants for lighting roofs, which exceed the national standards for the displacement capacity of weather-resistant sealants. requirements, leading the development of the industry.
The weathering and waterproof sealing of doors and windows is the same as that of curtain walls. It is a systematic project, including the sealing between the window frame and the glass, the sealing between the outer wall and the window frame, etc. The quality of silicone sealant also has an important impact on the performance of doors and windows. Some sealant products are filled with too much heavy calcium carbonate, so that a layer of white filler appears on the surface of the product after curing. Improper selection and use will cause degumming of the laminated glass after contact with the laminated glass, resulting in damage to the appearance as shown in Figure 1O. The quality of silicone sealant is a direct factor that affects the watertightness and airtightness of doors and windows, and high-quality silicone sealant products can maintain long-term adhesion, airtightness and watertightness during the service period.