Standard construction process of insulating glass series ②Secondary sealant

In the last issue of "Insulating glass secondary sealant, did you choose the right one?", the selection guide for insulating glass for different application parts was introduced. This issue will introduce the standard construction process of insulating glass secondary sealant. process.

Adhesion test

Before using the secondary sealant, we need to test the adhesion between the sealant and the film removal glass, white glass, aluminum spacer, etc. in the laboratory.

Now, low-emissivity LOW-E insulating glass has become the first choice for doors, windows and curtain walls, and the K value can even reach about 1.0W/m2·K. Therefore, the adhesion of the sealant to the film-removed LOW-E glass is the focus of attention.

The adhesion test of the insulating glass secondary sealant is generally carried out with reference to the standard of GB 24266-2009 "Silicone Structural Sealant for Insulating Glass". The steps are: first, the H-type specimen is cured under the specified standard conditions for 14 days, then treated in a 45°C water UV box for 300h (ultraviolet light wavelength 340nm), and then the tensile bond test is performed, and the results are evaluated. . In addition, the film removal effect of the LOW-E film is an important factor affecting the UV adhesion of the silicone structural adhesive to the offline LOW-E insulating glass water, and it also needs to be paid attention to.

Compatibility Test

Before applying the secondary sealant for insulating glass, we also need to test the compatibility between the sealant and the contact materials (such as butyl rubber, etc.), you can refer to GB 24266-2009 "Silicone Structural Sealant for Insulating Glass" Appendix A conducts the compatibility test to detect the changes in appearance and tensile adhesion between the secondary sealant and the contacting materials and their mutual heating or UV treatment, so as to select the most suitable product for secondary sealing protection.

construction environment requirements

Silicone sealant should be used in a clean environment with a temperature of 10 to 40°C and a relative humidity of 40% to 60%. The curing and curing area after construction must be clean and well ventilated, the temperature should be kept at 10-40°C, and the relative humidity should be kept at 40-60%; if the relative humidity is lower than 50%, the curing time of the unit should be extended, and a certain amount of humidification should be adopted. measure.

Sizing operation

According to the task list, first of all, we need to confirm whether the selected sealant meets the requirements of design and standard specifications, and at the same time, we must confirm that the sealant is used within the shelf life and cannot use expired products.

Second, check the glue machine. We need to check whether the valve of the glue inlet is working normally, whether the pressure of the pressure pump is normal and whether the filter screen of component B is clean. Put the sealant into the glue machine and carry out the exhaust operation to prevent the gas from entering the equipment and the mixed sealant is Air bubbles, and then adjust the mixing ratio of the equipment (generally, the mixing ratio is 10:1 by volume) and air pressure to ensure smooth and even mixing.

Test before gluing: must be carried out every day when gluing starts: butterfly test (to confirm whether the two-component glue is mixed evenly), pull-off test (to confirm the working time of the glue), and snake test if necessary (to confirm the overall curing of the glue) is normal).

Substrate cleaning: Effectively clean the parts to be bonded on the substrates (glass, aluminum spacers, etc.) to remove dust, oil, etc. LOW-E insulating glass should pay attention to the film removal effect at the edges.

Glue injection: The size of the glue outlet of the glue injection gun should be adapted to the width and depth of the seam. When injecting glue, the nozzle should move evenly against the bottom of the seam to ensure a continuous and smooth glue seam and prevent cavities or blistering. After the glue injection is completed, the insulating glass should be moved to the fixed area for maintenance. There should be no displacement and dislocation during the maintenance process, otherwise it will affect the quality and bonding effect of the composite hollow.

Field record

When applying glue on site, the above steps should be effectively recorded.

Detailed on-site construction records are a reliable guarantee for project construction, and at the same time facilitate effective retrospective inquiry of project information in the later stage.

conservation

The curing of the secondary sealant is greatly affected by the external environment, and it takes a certain amount of time to establish the adhesion. There is a certain difference in the curing speed of the secondary sealant in winter and summer, so the maintenance should be carried out in strict accordance with the standards after gluing. Before handling and installation, we should conduct an on-site rubber tapping test to confirm. If the sealant is not fully cured, or the bonding effect with the substrate is not good, the handling and installation of the board are not allowed.

As the saying goes, three points for materials and seven points for construction is enough to prove the importance of construction specifications.