As a high-performance adhesive, silicone structural adhesive is widely used in construction, automobiles, aerospace and other fields. The quality of its bonding effect directly affects the quality and safety of the product. In order to ensure that silicone structural adhesive can bond better, the following detailed description of its operation points and precautions from multiple aspects:
- Preparation before construction
Environmental control: Silicone structural adhesive should be used in a clean environment with a temperature of 5℃-40℃ (some say 4℃-40℃) and a relative humidity of 40%-80% to obtain a better bonding effect. At the same time, the injection room should be clean, dust-free, fire-free, and well ventilated. The indoor temperature should be controlled at 23±5℃ and the relative humidity should be controlled at 70%±5%.
Surface cleaning: The surface of the substrate to be bonded must be clean, dry, and free of pollutants such as grease, dust, release agent, and curing film. A mixed solvent of 50% isopropyl alcohol and 50% water (for non-oily pollutants) or xylene solvent (for oily pollutants) can be used for cleaning. The cleaning cloth should be soft and non-hairy to avoid secondary pollution. After cleaning, the cleaned part should avoid contact with hands or other sources of contamination again, otherwise it needs to be cleaned again. The cleaned substrate should be injected with glue within 15-30 minutes, otherwise it needs to be cleaned again.
Primer treatment: If primer is required, it should be applied before gluing to improve the bonding effect.
Make a coating plan: Plan the coating method and materials, including choosing single-component or two-component structural adhesive, and what kind of gluing tools to use, etc., to ensure smooth construction.
Silicone structural adhesive
- Construction operation of silicone structural adhesive
Mixing and gluing:
Single-component structural adhesive: It can be squeezed directly from a plastic tube or sausage-shaped packaging with a manual or pneumatic gluing body.
Two-component structural adhesive: Special gluing mixing equipment must be used for mixing and gluing. When mixing glue, the two-component sealant should be loaded according to the specified mixing ratio for full mixing, and butterfly specimens and glue cup pull-off specimens should be set aside to check the mixing condition. When injecting glue, the nozzle of the glue gun should be inserted to an appropriate depth so that the glue can be continuously, evenly and fully injected into the injection gap, and bubbles are not allowed.
Glue injection skills:
The injection action should be carried out continuously, and the diameter of the nozzle should be smaller than the thickness of the injection port so that the nozzle can extend into half of its depth.
The nozzle should move evenly and slowly to ensure that the interface is full of sealant.
The pressure should be adjusted at the joint to ensure that there is enough silicone structural glue at that place.
Finishing and maintenance:
After the glue injection is completed, the excess structural glue outside the interface should be immediately pressed into the interface with a scraper and scraped flat so that the glue contacts the side of the interface.
Remove all temporary protective tapes.
Attach labels with date and number on the unit and place them horizontally in the curing area for maintenance. The curing area must be clean and well ventilated, with a temperature of 5℃-40℃ and a relative humidity of 40%-80%. The curing time varies depending on the single-component or two-component structural adhesive. Generally, the single-component structural adhesive is cured for at least 21 days, and the two-component structural adhesive is cured for at least 14 days.
III. Precautions after use
Avoid touching: Silicone structural adhesive cures in the air, and should be avoided during the curing process to avoid deformation.
Keep clean: After the construction is completed, the tools and surfaces should be cleaned in time to avoid the silicone structural adhesive being difficult to remove after curing.
Storage conditions: Silicone structural adhesive should be stored in a dry and cool place, avoiding direct sunlight and high temperature environment.
Silicone structural adhesive
IV. Other precautions
Compatibility test: In order to ensure the long-term bonding ability of silicone structural adhesive, compatibility test must be carried out to check whether the materials used in the construction will have adverse effects on silicone structural adhesive.
Avoid expired use: It is strictly forbidden to use expired silicone structural adhesive to avoid affecting the bonding effect.
Professional training: Glue injection operators must receive special business training and pass the actual operation assessment before they can take up their posts.
In summary, the bonding effect of silicone structural adhesive is affected by many factors, including construction environment, substrate surface treatment, adhesive mixing and application techniques, finishing and maintenance, and precautions after use. Only by strictly following the operating procedures for construction and maintenance can the bonding effect of silicone structural adhesive be ensured to be better.