Problems and cause analysis of the hottest insulat

2022-07-24
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Problems and causes analysis of insulating glass in testing

insulating glass, as an important energy-saving product, is more and more widely used in China. There are 300 insulating glass enterprises in China, with a production capacity of nearly 10million m2, and the product quality has also been greatly improved. According to the prediction of IHS automotive, especially the imported line, it has strong technical force, advanced technology and equipment, strict control over the raw materials used, and a relatively perfect product quality management system. Its product quality is not much different from that of foreign countries; However, the quality of small and medium-sized enterprises, especially the hand-made insulating glass, fluctuates greatly. According to the entrusted inspection of insulating glass in recent years, the unqualified samples are mostly produced manually, mainly manifested in the rising dew point, ultraviolet radiation fog and glass cracking

there are 5 performance tests for insulating glass, including initial dew point, sealing, ultraviolet radiation, high temperature and humidity and climate cycle. The following is a brief analysis of the problems and causes of each inspection

1. The initial dew point

mainly tests whether the air in the insulating glass is dry. According to the national standard, it is qualified if the dew point is equal to or lower than -400c

the reason for the unqualified initial dew point is:

(1) the molecular sieve used is unqualified or has become invalid. If the container containing the molecular sieve is not tightly sealed, the molecular sieve is easy to fail. At this time, activation treatment shall be carried out, that is, heating in the oven at 3000C for more than 3H

(2) the air humidity in the production workshop is too high

(3) after the aluminum frame is installed into the molecular sieve, the pieces cannot be closed in time, and the molecular sieve fails to absorb water for too long

2. Ultraviolet radiation

this test mainly tests whether the insulating glass sealant contains organic volatiles that affect the line of sight. The system is designed as a cheap substitute for the commercial multi-material 3D printer. The insulating glass sample shall be continuously irradiated by a 300W UV lamp for 168h and stored at a temperature of 23 ± 2 ℃ for one week. The inner surface of the insulating glass shall be free of fog, oil or other pollutants

the reason for disqualification is:

(1) the content of organic volatile in sealant is too high

(2) the aluminum strip has not been decontaminated

3. Sealing inspection

this test is used to test the hardness of insulating glass sealant and whether there is leakage. The sample is kept for 2.5h under the condition of 10 ± 0.5kpa lower than the ambient air pressure, the thickness growth deviation is 95%, and the temperature changes regularly between ℃) for 224 cycles. The gas in each circulating insulating glass must undergo an expansion and contraction, so the adhesive force of the sealant can be automatically reset in the whole process by pressing the reset key on the main interface. In addition, due to high humidity, the water vapor transmission rate of sealant should be low, and the molecular sieve should have strong adsorption capacity

the common problems in detection are the rise of final dew point and the phenomenon of glue opening

the causes are:

(1) unqualified sealant is used or the shelf life has expired. After the high temperature and high humidity test, the glue and glass are separated and water enters

(2) uneven mixing and incomplete curing

(2) the effective adsorption capacity of molecular sieve is low or the exposure time in air is too long. The operator is not careful, the sealant is not well sealed, and there is air leakage. Because the molecular sieve should not only absorb the moisture in the air sealed in the interlayer during production to make the initial dew point qualified, but also continuously absorb the moisture diffused into the interlayer through the adhesive layer to make the final dew point meet the requirements

(4) the glass is not cleaned, resulting in the decrease of adhesion

(5) during manual gluing, due to too much rubber mixing at one time, part of the rubber is vulcanized, which increases the bubbles in the rubber layer and affects the bonding strength

(6) unreasonable raw material matching. When making insulating glass with silicone rubber, it must be used together with butyl rubber, because silicone rubber has high water vapor transmission

5. Climate cycle test

this is an aging resistance test and an investigation of the comprehensive performance of insulating glass. It simulates the four seasons of the year (cold, hot, wind and rain). Each cycle has to go through three stages: heating, natural cooling and forced cooling. A total of 320 cycles are carried out. The problems prone to occur in the inspection are the cracking, glue opening and final dew point rise of the insulating glass. In addition to being mentioned in high temperature and high humidity, the main reasons include:

you can only look at "silver" and sigh

(1) the sealant does not maintain good elasticity under low temperature conditions

(2) the content of volatile solvent in sealant is too high (no more than 1.5%)

(3) the original glass sheet itself is not annealed well

as a deep-processing product of glass, the price of insulating glass is relatively expensive. Once it is damaged after installation and use, it is difficult to replace it. Therefore, the raw materials of insulating glass should be carefully selected and the production process should be carried out in strict accordance with the operating procedures. Only in this way can the overall quality level of insulating glass in China be improved (end)

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