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1.1 Good warm edge
The edge sealing materials of insulating glass include aluminum strips, steel and stainless steel materials, organic silicon materials, etc. Due to the different thermal conductivity of their materials, the heat conduction formed at the edges of insulating glass also varies greatly. Table 1 shows the thermal conductivity of different types of materials used for insulating glass.
Table 1 Thermal conductivity of different materials:
Material Science | Thermal conductivity [W/(m *K)] |
Aluminium | 160 |
Steel | 50 |
Stainless Steel | 17 |
Glass | 1 |
Silicon Sealant | 0.35 |
TPS material (butyl rubber type) | 0.3 |
The edge sealing system composed of different types of materials will produce different thermal conductivity effects. Thermoplastic spacers (TPS) abandon the good heat transfer metals such as aluminum and stainless steel used in traditional insulating glass spacers. The linear thermal conductivity coefficient of insulating glass made with TPS is much lower than that of traditional products, blocking the heat dissipation at the edge of the glass and improving the energy-saving effect of the entire window.
Picture 1 shows a comparison between traditional slotted aluminum insulated glass and thermoplastic spacer TPS insulated glass under thermal imaging. It can be seen from picture 1 that due to the use of aluminum and other metal materials as spacer materials in traditional edge sealing systems, the thermal conductivity is high, which makes it easy for heat to pass through the insulated glass from the edge sealing area, resulting in lower temperatures at the edges.
Picture 1
With the improvement of people's quality of life, the demand for comfortable living environment is also increasing. The warm edge effect brought by the thermoplastic barrier (TPS) sealing system is conducive to stabilizing indoor temperature, reducing air convection, and providing a more comfortable indoor environment. Due to the presence of the warm edge system, it also reduces the condensation of water mist at the edge of the window glass and lowers the maintenance cost of the window frame (See picture 2)
Picture 2
1.2 Low water vapor permeability
The thermoplastic spacer (TPS) adopts a special butyl rubber mixed with molecular sieve for direct extrusion molding, and the consistency of the sealing material is good. At the same time, due to the close chemical bonding between thermoplastic spacers and glass and silicone adhesive, the hollow glass structure is more stable and the bonding is more firm. Table 2 shows the water vapor and gas permeability of different sealing materials. It can be seen that butyl rubber material has better water vapor and gas barrier ability than silicone rubber and polysulfide rubber, forming a better barrier to prevent water vapor from entering and gas leakage, which is conducive to maintaining the sealing performance of insulating glass for a long time and ensuring energy-saving performance (as shown in below picture 3 ).
Picture 3
Table 2 Water vapor and gas transmittance of different sealing materials
Material Science | Gas permeability g/(m ² 24h) | Water vapor transmittance g/(m ² 24h) |
Polysulfide adhesive | 0.03-0.1 | 5-10 |
Silicone adhesive | ≥ 20 | 15-20 |
Butyl rubber | 0.002-0.005 | ≤ 0.9 |
1.3 Fully automatic production process
The production of insulating glass of TPS system is completed by the automatic system at one time from glass loading, glass film removal, cleaning and drying, thermoplastic strip coating, pneumatic lamination and outer glue coating, avoiding errors and inconsistencies caused by manual operation, and achieving a high degree of uniformity of corner sealing, It completely eliminates the poor corner pressing and sealing of traditional trough aluminum insulating glass, and is suitable for the production of insulating glass of any type, size and shape (as shown in Figure 7).
Figure 7 Edge Bonding of Insulating Glass of Thermoplastic Spacer (TPS) System
2.1 Impact of service environment on insulating glass
As shown in Figure 8, insulating glass will be affected by various external factors during use
Figure 8 Environmental impact factors during the use of insulating glass
In particular, due to the frequent changes of ambient temperature and pressure, the gas in the cavity of the insulating glass is always in the state of thermal expansion or cold contraction, as shown in Figure 9, which makes the sealant under long-term stress. For the traditional double sealing system, the effect of this force will lead to the deformation and loss of the function of the sealant, and the moisture in the environment will constantly permeate from the edge of the insulating glass to the middle cavity. At the same time, the effect of ultraviolet ray, water and other corrosive gases in the environment will accelerate the aging of sealant, thus accelerating the speed of water vapor entering the middle cavity and the escape of filled argon. This kind of water vapor infiltration occurs at any time. The desiccant in the edge sealing system will eventually lose its water vapor adsorption capacity due to continuous adsorption of water molecules, which will lead to the increase of water vapor content in the cavity of the insulating glass and seal failure, leading to lower energy saving effect. Because the thermoplastic spacer sealing system has certain elasticity, it can effectively release the edge stress when the environment changes. At the same time, the thermoplastic spacer has a higher cohesive force to resist the changes brought by the load to ensure the stability of the sealing structure.
Figure 9 Traditional trough aluminum insulating glass
And Schematic diagram of changes in use of thermoplastic spacer strip (TPS) system
For the three glass and two cavity insulating glass commonly used in passive room glass of the new energy-saving building concept (as shown in Figure 10), the glass on both sides of the insulating glass will be subjected to the action of another cavity and generate greater stress, which will lead to the deformation of butyl rubber, reduce the effect of the first seal, increase the water vapor channel, and make the insulating glass fail faster, The sealing advantages of thermoplastic spacers will be more obvious.
Figure 10 Three glass and two cavity insulating glass
Change of sealant
2.2 Factors affecting the service life of insulating glass
According to the requirements of GB50096-2011 Code for Design of Residential Buildings, the service life of buildings shall not be less than 50 years. As an important part of the building, the service life of the insulating glass used by doors, windows and curtain walls has attracted the attention of the industry. It is mentioned in Appendix A "Failure Causes and Service Life of Insulating Glass" of GB/T11944-2012 Insulating Glass Standard that the expected service life of insulating glass should be at least 15 years. However, at present, the overall sealing service life of insulating glass in China is still relatively low, and the general manufacturer does not dare to promise a 10-year warranty. Therefore, we are still far from the standard requirements and building use requirements.
As mentioned above, the service life of insulating glass is directly related to the quality of edge materials (such as spacer, desiccant, sealant) and the manufacturing process of insulating glass. The service life of insulating glass is also affected by the installation condition and service environment.
In 3.1, we introduced the influence of external environment on the service life of insulating glass. In addition to external factors, what other factors affect the service life of insulating glass? The quality of edge sealing is directly related to the sealing durability of insulating glass. The use of sealant with low water vapor and gas permeability is the key. From the previous analysis, we can see that the thermoplastic spacer strip (TPS) has very excellent water vapor and gas barrier capacity, and the sealing durability of insulating glass will be improved if it is used for the edge sealing of insulating glass.
Taking the three glass and two cavity insulating glass system as an example, we can see from Figure 11 that eight bonding interfaces have been formed between the traditional trough aluminum insulating glass sealant and the glass as well as the spacer, while only four bonding interfaces will be formed between the thermoplastic spacer strip (TPS) seal and the glass. From the analysis of the current domestic insulating glass production level and our long-term testing situation, the poor adhesion of sealant, glass and spacer material is the main path leading to the passage of water vapor and gas, that is, under the condition that the water vapor and gas permeability of the sealing material are the same, the thermoplastic spacer sealing system reduces the water vapor and gas transmission channel due to the reduction of the bonding surface, To achieve the long-term durability of insulating glass.
Figure 11 Analysis of sealing and bonding interface of different insulating glass
2.3 Current quality status of insulating glass in China
Water permeability index (I) used in the national standard of insulating glass ）It indicates the water vapor sealing life of insulating glass. According to the standard, the average value of I shall be greater than 0.2; The argon content after the durability test is used to express the gas seal life.
T i Initial moisture content of desiccant
T f Final moisture content of desiccant
T c Standard moisture content of desiccant
What is the water permeability index I value? I value refers to the ratio between the amount of external water vapor entering the insulating glass and its effective absorption in the durability test. The water permeability index I can reflect the residual adsorption capacity and expected service life of the insulating glass sealing system; Be able to comprehensively evaluate the insulating glass system. The smaller the I value, the greater the residual adsorption capacity of the insulating glass and the longer the sealing life.
The National Glass Quality Supervision and Inspection Center has made statistical analysis on the durability test results of more than 300 insulating glass water vapor seals in China in the past two years. The distribution of I value is shown in Figure 12. The median value of I value is close to 15%, and about 15% of I value is greater than 20%.
Figure 12 I value statistics of domestic insulating glass
At the beginning of this century, the European insulating glass association UNI made a statistical analysis of the test results of the water vapor sealing durability of European insulating glass products (as shown in Figure 13). From Figure 13, it can be seen that the median value is between 4% and 5%. From the two statistical results, it can be seen that there is still a big gap between the overall sealing life of domestic insulating glass and that of foreign insulating glass.
Figure 13 I Value Statistics of UNI European Insulating Glass
In recent two years, the glass quality of the passive room has also attracted much attention. Table 3 shows the test results of the National Glass Quality Supervision and Inspection Center on the water vapor sealing durability of the three glass and two cavity insulating glass in recent years. It can be seen from Table 3 that the quality gap of insulating glass produced by different enterprises is relatively large, and the overall quality level still needs to be improved. If such glass is applied to passive buildings, it is far from meeting the requirements of the same life span as buildings. To solve this problem, we should start with materials and processes, and also seek more advanced sealing structures.
NO | Glass Configuration | Ti | Tf | Iav |
1 | 3 Glass 2 cavity | 0.027 | 0.0537 | 0.161 |
2 | Vacuum IGU | 0.0418 | 0.0494 | 0.05 |
3 | 3 Glass 2 cavity | 0.0286 | 0.0492 | 0.125 |
4 | Vacuum IGU | 0.035 | 0.0529 | 0.128 |
5 | 3 Glass 2 cavity | 0.021 | 0.0466 | 0.14 |
6 | 3 Glass 2 cavity | 0.018 | 0.0591 | 0.233 |
The earliest thermoplastic spacer strip (TPS) insulating glass system was born in 1974 in Komelin. Its industrial production has been since the 1990s. At present, there are more than 100 TPS production lines around the world. There are also several production lines of thermoplastic spacer TPS insulating glass in operation in China. The earliest production line was put into production in 2011. Thermoplastic spacer insulating glass and the new generation TPS product 4SG with structural strength have been preliminarily recognized and applied in structural curtain walls, commercial buildings, residential buildings, buses, automobiles and other fields.
Since its inception, the thermoplastic spacer strip (TPS) system has passed the inspection and certification of relevant standards in many countries around the world, including Japanese JIS R3209 Insulating Glass, European Standard EN1279-2 Long term Test Method for Water Vapor Permeation of Insulating Glass, European Standard EN1279-3 Long term Test Method for Gas Permeation of Insulating Glass European standard EN1279-4 Test Method for Physical Characteristics of Insulating Glass Edge Sealing, North American ASTM773/774, French NFP78-451/452, Italian UNI10593, German DIN1286 and other standards.
The insulating glass of this sealing system is also the first three glass two cavity insulating glass system to pass the gas retention test of EN1279.3, with annual argon leakage rates of 0.4%~0.5%.
In order to study and analyze the performance of the insulating glass of the thermoplastic spacer system and verify its advantages in durability, the National Glass Quality Supervision and Inspection Center selected the Thermoplastic Spacer 4SG product produced by Kemelin Company, used Dow Corning silicone structural adhesive as the outer sealant, and used the 100 ultra full-automatic production line to produce the inflatable insulating glass sample. According to the water vapor seal durability and gas seal durability in GB/T11944-2012 standard, five standard cycles were tested respectively.
(1) Durability of water vapor seal
The test of each cycle consists of high and low temperature alternating cycle and constant temperature and humidity. Stage 1: 56 cycles, one temperature cycle every 12 hours, the temperature ranges from - 18 ℃± 2 ℃ to 53 ℃± 1 ℃; Stage 2: The ambient temperature at 58 ℃± 1 ℃ and relative humidity greater than 95% is maintained for 7 weeks, and each cycle is 77 days (as shown in Figure 14).
Figure 14 Cycle Cycle of Water Steam Seal Durability
In this test, five groups of samples are put into the aging test chamber. After each cycle, one group is taken out for the final moisture content test and I value is calculated. junction See Table 4 for results.
(2) Gas seal durability
First, the initial argon content of the insulating glass for durability test is tested, and the results are shown in Table 5.
Table 4 Durability Test Results of 5 Cycles of Thermoplastic Spacer Strip (4SG)
Table 5 Test Results of Initial Argon Content of Samples
Sample No | Initial argon content (% V/V) |
1# | 93.7% |
2# | 93% |
Secondly, according to the test method in GB/T11944-2012, the sample was tested for five cycles, and the argon content was tested after each cycle. See Table 6 for the test results.
Table 6 Argon content test results of samples after aging
cycle | Sample No | Final argon content (% V/V) |
1 cycle | 1# | ninety-two point eight |
2# | ninety-two point two | |
2 cycles | 1# | ninety-one point nine |
2# | ninety-one point three | |
3 cycles | 1# | ninety-one point two |
2# | ninety point five | |
4 cycles | 1# | ninety point four |
2# | eighty-nine point seven | |
5 cycles | 1# | eighty-nine point six |
2# | eighty-nine |
From the test results, both the water permeability index and the argon content of the insulating glass of the thermoplastic spacer strip (4SG) system can still meet the requirements of the national standard after five aging cycles. The test results of the water permeability index after five cycles are better than the test results of the current standard cycle of traditional sealing structures in China, The gas content only decreased by about 4%, indicating that the service life of the insulating glass in this system will be far longer than that of the current mainstream sealing structure insulating glass in China.
From theoretical analysis to test results, it is shown that thermoplastic spacer strip (TPS) is a new generation of insulating glass edge sealing material. This insulating glass system can improve the sealing life of insulating glass and improve the edge effect of insulating glass, which should be vigorously promoted. However, at present, both the thermoplastic spacer sealing material and the automatic production equipment for producing the insulating glass with the sealing structure are imported, and the price is one of the main reasons that restrict the popularization and application of the thermoplastic spacer (TPS) insulating glass. At present, China is still at the stage of equipment research and development and material research, and has not realized industrial production. With the increase of people's understanding of the superior performance of thermoplastic spacer insulating glass and the further improvement of domestic research and industrialization level, its application prospect will be more and more extensive.
reference:
[1] Qinhuangdao Glass Industry Research and Design Institute, Insulating Glass (GB/T11944-2012), China Standards Press.
[2] Dr.Chritian Scherer, Ernst Smar etc，A new warm edge system with superiorenergy efficiency and durability，GPD Glass Performance Days 2015。
[3] Li Jing, Innovative Spacer Sealing System for Curtain Wall 4SG, 2017 China Glass Annual Conference speech.
[4] Yuan Peifeng, et al., Performance Advantages of Thermoplastic Warm Edge Insulating Glass, Proceedings of 2017 China Glass Industry Annual Conference and Technical Seminar.
