3. Problems to be paid attention to during the test
(1) Strictly control the environmental conditions of the laboratory
The laboratory shall have temperature control facilities, under the conditions of 23°c ± 2°c and 30%- 70% relative humidity,the relative humidity of the environment should be reduced as far as possible. When the relative humidity is high, the water absorption rate of the molecular sieve is very fast, and the phenomenon of weighing data is difficult to constant occurs, so that the molecular sieve can absorb more water from the environment and make the test error.
(2) The crucible containing the desiccant should be dry and clean
The crucible containing the desiccant shall be heated to constant weight before use, and the test table shall be clean.Every time you take the desiccant for standard moisture content from the container containing calcium chloride saturated solution, attention should be paid to whether the bottom and outer wall of the crucible are stained with solution or solid.In addition, attention should be paid to whether the container containing calcium chloride saturated solution and the compartment of the crucible have solution aggregation or solid precipitation, and remove the liquid and solids in time.Prevent errors in the weighing process, which making the results inaccurate.
(3) The operation process of taking the desiccant should be as fast as possible.
Exposure of the desiccant water absorption speed is very fast, in a short period of time can absorb a large amount of water, from the sample to take a desiccant to be controlled in the standard required time, it is best for 2 or more people to cooperate, in order to reduce the desiccant in the sampling process of water absorption.
(4) The weighing instrument (one in ten thousand balance) should be placed in a constant temperature and humidity environment, and should be preheated for at least 0.5 h before use, and the surrounding environment should be free of noise and vibration.
4. Several manifestations and possible reasons of insulating glass with unqualified moisture permeability index
4.1 Inqualified performance
(1) From the appearance, the hollow glass sealant discoloration phenomenon, the inner layer of butyl glue is obviously interrupted, small pieces of butyl colloid around the white oil or dirt.
(2) The sealant rubber layer is shallow, inelastic, pulverized, or densely covered with air bubbles, generally with long air bubbles, the sealant and the inner layer of the hollow glass bonding failure, the glass is easy to break away from the rubber layer.
4.2 Cause analysis
(1) The spacing strip or glass is stained with stains, not cleaned before the sheet, resulting in the sealant and glass bond is not good, under the action of the test environment, the glass and glue layer fall off the phenomenon of large water absorption.
(2) The glue mixing or glue application technology is not good, resulting in dense bubbles in the outer channel sealant, the length of some bubbles reach 10 mm, so that the water vapor transmittance of the sealant increases, resulting in the excessive water absorption amount of the desiccant, the water penetration index exceeds the standard.
Some of the desiccant in the interval box is removed by the bonded into a group, the surface of the aggregation of a large number of water droplets, the base can drop water droplets.From the shape of the bubbles in the sealing stock, the majority of the rectangular, and more bubbles, which is caused by uneven mixing or irregular glue.Some large factories also have such a situation, which may be caused by the insufficient attention to the test sample, or the workers' awareness is not strong.
(3) The interval frame strength is not enough.
Some factories use the interval frame strength is particularly small, when cutting the sealant, see the interval frame has deformation, the deformation of the interval frame pull the sealant, make the sealant also deformation or separated from the inner surface of the glass, make the sealant sealing effect is not good or can not play the role of sealing support, in the test process to make the desiccant inhaled a lot of moisture.
(4) The outer channel glue or interval frame contains mineral oil, under the action of the test conditions, the mineral oil quickly permeate out, make the butyl glue dissolution, butyl glue thus flow oil, fracture phenomenon, and lose the sealing bonding effect.
(5) Bul glue edges have not been effectively wrapped, because the production and use of hollow glass has been for a long time, most enterprises rarely appear such mistakes, due to this situation, the durability of hollow glass water gas sealing does not meet the standard requirements is rare.
The test results of the water and gas sealing durability of hollow glass are qualified or not are greatly related to the raw materials, glue mixing technology, production environment and workers' experience. In addition, the test personnel should also have good professional quality and professional dedication.