1. The importance of insulation strips
In China, building energy consumption accounts for 25% of total social energy consumption. With the economic development and the improvement of people's quality of life and living environment, this proportion will continue to grow. Building doors and windows and building curtain walls are part of the building envelope structure, which is the most active and sensitive part of building heat exchange heat transfer, which is 5-6 times of the wall heat loss. The energy saving of doors, windows and curtain walls accounts for about 40% of building energy efficiency, and has a high weight.
The most direct factor affecting building energy consumption is the thermal insulation performance of building envelopes. The weakest part of the thermal performance of peripheral structures is windows. With the wide application of new wall materials and external wall insulation technology, other The thermal insulation capacity of the envelope structure has been greatly improved. In recent years, China has used a large number of broken bridge technology in the country to produce a large number of broken aluminum alloy doors and windows in the country. The aluminum doors and windows of the broken bridge not only have outstanding thermal insulation performance. It can be made into different colors and patterns inside and outside, such as wood grain aluminum, and has unparalleled advantages in air tightness, water tightness, wind pressure resistance and pollution prevention. Because the requirements for high-rise building doors and windows are light, the second is high strength, the third is long service life, the fourth is good fire performance, the fifth is good lighting performance, and the insulated aluminum alloy window can meet the above requirements, so in the future It is still a mainstream product for a long time.
In the past ten years, the industry of heat-insulating aluminum door and window curtain wall has developed rapidly. Thanks to the promotion of the country and various profile factories, the heat-breaking cold bridge technology used in the insulated aluminum door and window curtain wall is to divide the aluminum alloy window frame into three parts. The material, that is, the outer aluminum alloy frame, the inner aluminum alloy frame, and the intermediate core portion connecting the inner and outer aluminum frames, and the intermediate core portion is called the "heat-breaking cold bridge". Therefore, the material selection of the "core" part is related to the safety of the entire insulated aluminum door and window curtain wall. At present, there are two kinds of materials in the "core" part of the country. The first type is a strip-type polyamide heat-insulating strip, and the second type is a cast-type polyurethane heat-insulating glue. The ratio of the two is 8:2.
Absorbed doors and windows have been used abroad for decades, and the materials used in the insulation strips have experienced PVC and ABS. Finally, the composite material PA66GF25 was confirmed. When using PVC, ABS and other materials as heat insulation strips abroad, the coefficient of linear expansion cannot be matched with the aluminum profiles. When the users use them all year round, the doors and windows of the curtain wall will leak or leak, which will not meet the requirements of “three sexes” and greatly reduce the separation. The heat effect, and the poor aging resistance of these general-purpose plastics such as PVC and ABS are the biggest hidden dangers of safety.
Compared with other composite materials, glass fiber reinforced nylon 66 composite material has excellent mechanical properties, good aging resistance, high and low temperature performance, high dimensional accuracy, and linear expansion coefficient matching with aluminum profiles, ensuring the "three characteristics" of doors and windows. At the same time, with reference to the experience of using foreign thermal insulation strips for decades, it is finally determined that PA66+25% glass fiber composite material is most suitable as the material of heat insulation strip.
At present, the technical level of domestic production of heat insulation strip manufacturers is uneven. Due to the high material cost and complicated extrusion process of PA66GF25 composite materials, most domestic manufacturers produce insulation strips that do not meet GB/T23615.1-2009. . According to market research, the number of insulation bars used in energy-saving aluminum door and window curtain wall in the domestic market is nearly 1 billion meters, but the actual use of PA66GF25 is only about 40%. The remaining 60% are basically made of PVC and other materials, separated by 40% PA66GF25. 15% of the hot strips are produced with genuine PA66 raw materials, and about 25% are produced with sub-brand or recycled water nozzle PA66, so the truly safe and qualified insulation strips account for about 15% of the total. This phenomenon should be brought to the attention of the local construction administrative departments, relevant quality supervision departments and users, paying particular attention to those insulating profiles that are not produced in aluminum profile plants and produced by aluminum profile plants according to user requirements, otherwise it is bound to give energy-saving aluminum doors and windows. The curtain wall industry has serious consequences and adverse effects.
1. Factors in the existence of fake and shoddy insulation strips
1) Low cost of raw materials and processing
The price of genuine PA66 is 30,000~36,000 yuan/ton, the price of sub-brand or recycling nozzle PA66 is 11000~15000 yuan/ton, the price of genuine PVC is 9000~10000 yuan/ton, and the price of sub-brand or recycled PVC is 4000~ 6000 yuan / ton, taking the conventional I-14.8 insulation strip as an example, one ton of PA66GF25 raw material can produce 22000 meters, and one ton of PVC raw material can produce 28000 meters, the cost difference is obvious.
1) The level of processing technology is backward
The processing temperature range of PA66GF25 composite material is narrow, and the extrusion process is quite demanding. The product performance, product appearance quality, dimensional accuracy and complex profile strip mainly depend on raw material quality, processing technology and mold design level.
2)Material toughness advantage Misleading profile manufacturers and door and window factories
When the profile manufacturers pull the bends in the strip and door and window factory, it seems that PVC or recycled PA66 has an advantage from the point of view of use. PVC is a general-purpose plastic with good toughness and is not easy to burst when wearing and pulling. The water receiving port PA66 has been used for many times, and has a wide molecular weight distribution range and contains many impurities (generally containing PA6, PVC, PP, PE, ABS, etc.), and the toughness is good.
3) Aluminum profile manufacturers have insufficient experience in identifying and using insulation strips
China has not used thermal insulation strips for more than 10 years. The implementation of various standards is not determined, and the industry is not standardized. As a result, more and more enterprises are producing counterfeit insulation strips, which seriously disrupts the market order. These are all manufacturers of aluminum profiles. The credibility and the safety of the people do the price.
2. The danger of using fake and shoddy insulation strips
1) Unstable dimensional accuracy, can not guarantee the "three characteristics" requirements of insulated aluminum door and window curtain wall
Due to the low raw material cost, complex composition, backward extrusion process, extensive production, and insufficient mold design level, the poor quality insulation strips lead to low dimensional accuracy. If the insulated doors and windows are made after wearing, the door and window frames are subject to The rainwater penetrates, the heat insulation effect is greatly reduced, and the frame wall is damp and mildew, which affects the appearance of the building. Inferior heat insulation strips expand rapidly after water absorption, and aluminum doors and windows are easy to fall off when used all year round, dangerous!
2) Low mechanical properties
Compared with the injection molding standard spline, the material strength of PVCGF25 is 30~55Mpa, the material strength of recycled water port PA66GF25 is 90~130 Mpa, and the material strength of genuine PA66GF25 is 160~190 Mpa. The performance of the product after single-screw extrusion is greatly reduced, especially the complex shape of the curtain wall insulation strip carries a large-quality aluminum curtain wall, and the mechanical properties are very high.
3) Poor aging resistance
Tensile strength and aging resistance are directly related to the safety of insulated aluminum door and window curtain walls. PVC aging resistance is the worst in the plastic family and is toxic. After testing, PVC has almost lost its mechanical properties after being placed in the outdoor environment for 12 years in the south. If PVCGF25 insulation strip is used, its safe service life is no more than 10 years. At present, the use of PA66GF25 insulation strip in China is less than 10 years. The 1000-hour heat aging in GB/T23615.1-2009 and the 200-hour UV aging test in JG/T174-2005 have certain guiding significance for the service life. After repeated tests, the recycled PA66 insulation strip and PVC insulation strip do not meet the aging resistance requirements of GB/T23615.1-2009 and JG/T174-2005. Only the use of the original PA66GF25 insulation strip can achieve the aging resistance.
4) Does not match the linear expansion coefficient of aluminum profiles
The linear expansion coefficient of PVC (8.3~12×10-5K-1), the linear expansion coefficient of the sub-brand PA66GF25 is (3.0~4.5×10-5K-1), and the linear expansion coefficient of the genuine PA66GF25 is (2.3~3.5×10). -5K-1), the linear expansion coefficient of aluminum alloy (2.35×10-5K-1), the importance of linear expansion coefficient to insulated doors and windows is self-evident.
5) Unsafe and environmentally friendly
Counterfeit PVC insulation strips will slowly release toxic gas during long-term use, because PVC insulation strips are added with plasticizer (dibutyl terephthalate), anti-aging agent (lead stearate), etc. Some toxic additives to enhance its heat resistance, toughness, etc. If the temperature reaches 70 ° C or more, PVC will decompose to produce irritating gases such as chlorine and hydrogen chloride, which is toxic! The recovery nozzle PA66 contains a considerable amount of plastic impurities such as PVC, PP, PE, etc. The composition is more complicated and more toxic! If used for a long time, the incompatible impurities inside the material will be combined with the nylon interface, the impurities will precipitate, the internal structure will be destroyed, and the performance will be significantly reduced.
3. Conclusion
It consists of not less than 65% of polyamide 66 and 25% + 2.5% of glass fiber, and it is a polyamide profile which has a heat transfer effect and a structural connection in the metal heat insulation profile.
The heat insulation strip is the core component of the strip-insulated aluminum profile, which is the “broken bridge” on the heat transfer path of the aluminum profile, which reduces the transfer of heat in the aluminum profile; and the aluminum profile on both sides of the heat insulation profile. The structural joint (see Figure 2-1), through its connection, makes the three parts of the insulated aluminum profile integral and bears the load. Unlike rubber strips, it is made of a new composite material by mechanical rolling. It cannot be replaced separately. Replacement can only be replaced with the entire profile.
This paper introduces the energy-saving effect of nylon 66 insulation strip on the insulated aluminum door and window curtain wall, and analyzes the factors existing in the inferior nylon 66 insulation strip and the impact on the safety of the whole insulated aluminum door and window curtain wall.
At present, there are many examples of domestic insulated aluminum door and window projects. The enterprises use the imported PA66 insulation strips for bidding. After winning the bid, they use PVC insulation strips to make actual low-cost insulation strips for actual processing or qualified PA66 insulation. The strip is mixed with PVC and low-priced PA66 insulation strips, and even the strips with the trademark logo of the high-quality insulation strips face the outside, to "prove" the grade of the heat-insulating strips used, this kind of "small-day crossing" has a strong concealment. Because the price of imported insulation strips is high, and the quality of PVC insulation strips is really too poor, many manufacturers of insulation strips adopt a compromise method, appropriately improve the extrusion process and equipment, and use recycled PA66 for production. Most of the mechanical properties meet the standard requirements when testing, but its mechanical strength is unstable, heat resistance and aging resistance can not be compared with the original PA66 raw materials, and some manufacturers with backward process equipment use the original PA66 injection molded parts for related performance. Detecting, and the obtained test report as the performance test report of the finished heat insulation strip, the test data of this raw material can only represent the material properties, if it is extruded and shaped, etc. Industrial technology factory product performance will be greatly reduced. Some insulated aluminum door and window enterprises have adopted a plan that is both economical and relatively safe after fully understanding the large performance difference between PVC, domestic low-cost insulation strips and imported insulation strips: window frame aluminum profiles are low-priced However, the qualified domestic PA66 insulation strips are tested. The sash aluminum profiles are made of high-quality insulation strips. Because the window frame aluminum profiles are fixed on the wall, even if there is quality risk, there will be no major problems, and the sash aluminum profiles are The activity is carried by the individual, so there is no danger of quality.
Therefore, Hengye advises customers to use high quality insulation strip products.