Laminated glass film EVA, PVB, SGP performance comparison
Laminated glass is a widely used glass in the field of architectural glass, which is also called safety glass. Commonly used interlayer films for laminated glass are: EVA, PVB, SGP.
The full name of EVA is ethylene-vinyl acetate copolymer. Because of its strong water resistance and corrosion resistance, it is widely used in packaging films, functional shed films, foam shoe materials, hot melt adhesives, wires and cables, and toys. In my country, EVA is usually used as sole material.
As the EVA film used for laminated glass, compared with PVB or SGP, EVA has a lower melting temperature and good fluidity, and generally has a good processing effect at about 110 °C. Simple vacuuming and heating can meet the production needs of EVA laminated glass.
The film layer of EVA has good fluidity, and processes such as wire clamping and winding can be carried out in the film layer to produce beautiful decorative glass with patterns and patterns. At the same time, it also has good water resistance, but weak anti-ultraviolet ability, and it is easy to turn yellow and black in long-term sunlight, so it is mainly used for indoor partition and decoration.
The full name of PVB is polyvinyl butyral, which has high transparency, cold resistance and impact resistance. It is currently the most widely used interlayer material for architectural glass and automotive glass.
Compared with EVA, the storage and processing technology of PVB interlayer is much more complicated. Generally, the temperature of PVB lamination is between 18~23℃, the relative humidity is 18~23%, and the moisture content of PVB is 0.4~0.6%. After preheating rolling or vacuuming, it is necessary to use an autoclave at 120~130 ℃, 1.0~1.3MPa, heat preservation and pressure for 30~60 minutes. The energy consumption of high temperature and autoclave equipment is huge.
PVB laminated glass has good safety, sound insulation and UV resistance, but PVB has poor water resistance, and it is easy to open and fall off in a long-term humid environment.
The full name of SGP (SentryGlasPlus) is ionic interlayer, and SGP laminated glass is mainly used in glass skylights, glass exterior windows and curtain walls.
Performance Characteristics of SGP Films
1、Colorless and with high transparency.
2. Low hygroscopicity to prevent water molecules from invading the adhesive layer, resulting in bubbles or degumming.
3. It has good thermal stability and can withstand temperature changes without degumming the adhesive layer or destroying the glass, ensuring the safety of the laminated glass.
4. It has good light stability to ensure that the interlayer material is not easy to change color or become brittle under the action of light, and to ensure the optical properties of the laminated glass.
5. It has good adhesion. When the glass is impacted and broken, the glass will not fall off, ensuring personal safety.
6. It has good elasticity to increase the anti-penetration and vibration absorption properties of the laminated glass.
Performance comparison between PVB and SGP
1. Excellent mechanical properties and high strength. The bearing capacity of SGP laminated glass is twice that of PVB laminated glass of the same thickness; at the same time,the bending deflection of SGP laminated glass is only 1/4 of that of PVB laminated glass under the same load and the same thickness.
2.Tear strength. Under the same thickness, the tear strength of PVB laminated film is 5 times that of PVB. Even if the glass is broken, the SGP film can also bond the broken glass to form a temporary structure after the destruction. Its bending deformation is small, and it can also bear a certain amount of load without falling in the whole piece.
3. Strong stability and moisture resistance. The SGP laminated film itself is colorless and translucent, and has good weather resistance and is not easy to yellow. The yellowing coefficient of SGP film is less than 1.5, while the yellowing coefficient of PVB film is 6~12, so SGP is used more for ultra-white interlayer.
Although the production process of SGP is similar to that of PVB, the terminal price is relatively high, so it is not widely used in China, and its awareness is relatively low.