【Preface】

The application of butyl sealant is the first and crucial step in the production of insulating glass, as it determines the overall performance of insulating glass products. To ensure the appearance and quality of insulating glass, the following technical requirements are imposed on the butyl sealant used:

◆ Appropriate butyl sealant with quality guarantee must be selected;

◆ It has good initial adhesion and adhesion to glass;

◆ It has good sealing performance;

◆ The coating should be uniform and the coating cross-section should be consistent

◆ It has good compatibility with the sealant used in conjunction.

【Theoretical Research and Practical problem discussion and analysis】

Mastering and implementing the correct manufacturing process is the guarantee and prerequisite for the quality of insulating glass. The following briefly discusses the common problems that may occur during the use of butyl sealant and the solutions or suggestions

Phenomenon: The butyl rubber strips coated on the aluminum spacer bars have burrs and are uneven.

Reason: There may be impurities at the outlets of the two rubber nozzles or the mouths of the rubber nozzles may not be smooth.

Solution measures or suggestions: Check whether there are impurities at the outlets of the two rubber nozzles or whether the nozzle mouths are smooth.

Phenomenon: A gap (white line) appears between the butyl rubber strip after lamination and the second sealant.

Reason: The second sealant was not applied in the correct way.

Solution measures or suggestions: When applying the second coat of sealant, apply appropriate force and apply it in one direction to prevent air pockets from entering the sealant and reducing the sealing performance of the insulating glass.

Phenomenon: The extrusion is not smooth after heating, and it is prone to glue breakage (thread breakage).

Reason:The key to using butyl sealant lies in extrusion. The control of temperature is of great significance during the extrusion process. Whether the temperature control is appropriate directly affects the rheological state of the butyl sealant throughout the processing, influencing the intrinsic quality and appearance of the product. Special attention should be paid to the temperature. Excessively high temperatures can cause excessive melting of the sealant, resulting in no strength or even failure to form. When the temperature is too low, the fluidity of the glue is poor, and the machine cannot extrude the glue smoothly, which affects the construction progress. This is the main reason for the unsuccessful extrusion. Another possible reason is that the butyl sealant is mixed with air bubbles during manufacturing, which causes a breakage during the extrusion process.

Solution measures or suggestions: Generally speaking, the selection of temperature should be based on the extrusion temperature range provided by the manufacturer. The temperature of the extruder is generally set between 100 and 150℃ for the barrel and between 102 and 152℃ for the die head. In order to generate a certain pressure on the main machine and ensure uniform extrusion of the melt, the temperature of the die head is required to be higher than that of the barrel. Temperature has a certain lag. During adjustment, it should be noted that heating and cooling should be carried out gradually. Before the application starts, appropriate venting should be done to reduce internal air bubbles and voids. Air bubbles generated during extrusion can cause the adhesive to break.

Phenomenon: The extrusion temperature is well controlled, but the adhesion between the aluminum spacer bars and the butyl sealant is poor or has a weak bond.

Reason: (1) The aluminum spacer bars or conveyor belts are not clean, with oil stains or dust.

1) The belt conveyor is too fast, and the aluminum spacer bars cannot be coated with glue in time.

2) Adjust the gap between the two rubber nozzles proportionally.

3) When applying, the aluminum spacer frame should be placed vertically to prevent the glue nozzle from being difficult to pass through or the glue application position from being incorrect

The phenomenon that the aluminum spacer bars formed do not stick to glue.

4) Butyl sealant is an elastomer that is both elastic and viscous. It is extruded and adsorbed onto clean aluminum spacers under appropriate temperature and pressure, and the molten butyl sealant diffuses onto the surface of the adhered object. Gradually wetting the surface of the adherend and penetrating into the micro-pores on the surface is a physical process. During this process, the butyl rubber only has line contact with the adherend (aluminum spacer bar) on the surface. Only after pressing can it have surface contact with the adherend. Therefore, appropriate construction pressure and temperature are conducive to the progress of this process. It is worth noting that it takes some time (3-5 minutes) for the adhesive to adsorb the aluminum spacer bars to achieve the best bonding effect.

Phenomenon: After the insulating glass is made, the butyl sealant leaks out (tears).

Reason: (1) The butyl sealant used for insulating glass is incompatible with the outer insulating glass sealant;

2) The sealant used for framing insulating glass is not compatible with butyl sealant.

3) The weather-resistant sealant used during the installation of the curtain wall is incompatible with butyl sealant.

4) Use substandard butyl sealant.

Solution measures or suggestions: (1) Select sealants from well-known brands and, if possible, use products from the same company in combination; Before using sealants from different manufacturers, necessary compatibility tests should be conducted (this compatibility test is for butyl sealants). Compatibility tests among the sealant for external insulating glass, the sealant used for framing, or the weather-resistant sealant used during curtain wall installation.

【Notes】

Open the original packaging and check for any obvious particles or debris. Do not apply too quickly to avoid not covering the entire area. If the coating doesn't reach the end or the roller is picked up, or the pressing time is too short, you can readjust the pressing time of the roller. The coated aluminum spacer frames should not be placed for too long, otherwise it will affect the bonding and sealing effect. If the conveyor belt deviates, it should be corrected in time. If there is too much adhesive on the conveyor belt, it should be removed in time. If necessary, a small amount of paraffin wax can be applied to prevent the belt from sticking. After applying the first coat of sealant, try to press it together as soon as possible to avoid the influence of environmental temperature on the adhesion of the product. For insulating glass that has been rolled but not yet coated with the second coat of sealant, it should be placed horizontally. It can be placed vertically for a short time, but it must not collide to avoid unnecessary misalignment. Before making double-pane insulating glass, it is necessary to conduct the required compatibility tests on the double-pane sealant to prevent the two sealants from dissolving.