Technological Process

▎ Film PVB:

Considering the shrinkage of the PVB interlayer, its size after cutting should be slightly larger than the glass.

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▎ Combination:

Conditions for combination room:15-25℃，30% relative humidity；The combination room should be equipped  with a double door,and the air in the room need to be filtrated with positive pressure. The carpet of absorbing dust  should be placed at the entrance.Operators should wear clear and unhaired working clothes.Combination requirements:the film on the glass should be flat or unruffled.Don’t draw the film forcibly during the cutting.The remaining  of film after being cut should be 3 to 5mm more than the glass in width. The knife shouldn’t come into contact with  the glass when trimming to avoid making glass particles to cause any air bubble on the edge. In summer, its best to  unpack the packed film rolls in the combination for more than 8 hours before the combination.

Pre-compression and exhaustion:The combined glass must be pre-pressed and exhausted so that the air between the glass and interlayer can be  removed,and its edges should be well sealed before the high pressure forming.The above procedure can be divided  as follows: 

(1)Rolling exhaustion:After pre-pressing and exhausting the combined glass,the exhaustion and edge sealing are  completed through ‘the first roll’, ‘thermostatic chamber’ and ‘second roll’ in turn.The temperature of glass  surface at the time of output is 60 to 80℃，the glass edges can be sealed well with a transparent stripe around the  laminated glass to avoid any air bubble produced due to reflux air in the high-pressure autoclave,and even-distributed nontransparent parts can exist on other positions. The temperature of the glass surface shouldn’t be too high because it makes the edge sealing too early to  remove the air inside;its temperature shouldn’t be too low because it makes the edge sealing incomplete to produce  reflux air bubbles.The required glass should be prepared before the production so that the continual production can  be ensured asap and any failed control of the glass surface temperature caused by long interval and large changes of  thermostatic chamber temperature can be avoided

(2)Pre-compression and exhaustion in thermal vacuum:place the combined glass into a vacuum bag or put a  vacuum rubber ring around the glass.Exhaustion and edge sealing are completed after cold drawing and hot drawing.Suggestions:decompression vacuum ＞650mmHg,cold-drawn temperature ＜25℃，30-40 minutes,hot-drawn  temperature :80 to 100℃，30 to 60 minutes.

▎High pressure forming:

The glass after finishing the precompression and exhaustion is placed perpendicular to the holder.The space  between both adjacent laminated glasses is more than 5mm. After placing the glass into the autoclave,the door of  this autoclave should be tightly closed.Firstly heat the autoclave to 45℃，and then heat and compress the glass at  the same time.Controlling the heating rate at 5℃/min,and the rate of compression at 0.06Mpa/min.When the  temperature reaches 120 to 140℃ and the pressure reaches 1.0 to 1.3Mpa,please begin to maintain the above  temperature and pressure for 30 to 60 minutes,and the slowly reduce the temperature while maintaining the above  pressure to prevent the glass from bursting up. Finally, the high pressure forming is completed by reducing the  temperature to 45℃ and decompressing to atmospheric pressure.