Polyurethane adhesives have excellent performance and are widely used. To fully leverage its performance, it is crucial to master the following usage skills.
First, surface treatment is the foundation
This is the most crucial step, which directly affects the final bonding strength. Make sure that the surface of the objects to be bonded is clean, dry and free of oil stains. For materials with high surface energy such as metals and glass, it is recommended to roughen them with sandpaper to increase the mechanical embedding force and contact area. For plastics (such as PP and PE), flame or corona treatment is required to enhance their surface polarity. After processing, it is best to wipe it with a cleaning agent (such as acetone) and wait for it to completely evaporate.
Second, the proportioning and mixing must be precise
For two-component polyurethane adhesives, accurate proportioning must be carried out strictly in accordance with the weight ratio or volume ratio specified in the product manual. Proportional deviation can lead to incomplete curing, seriously affecting the final performance. When mixing, stir thoroughly to ensure uniform contact between the two components. It is recommended to use mechanical stirring and stir slowly along the container wall to reduce the entrainment of bubbles. The mixed adhesive solution should be used up within the applicable period.
Third, the application of glue and pressure should be appropriate
According to the shape and viscosity of the material, select the appropriate adhesive application method (such as troweling, brushing, or roller coating). The adhesive layer is not necessarily the thicker the better. Generally, it is recommended to control it within 0.1-0.5mm, and a uniform thin layer is sufficient. Excessive thickness can lead to residual bubbles, increased internal stress and slow curing. After applying the adhesive, the two objects to be bonded should be aligned and adhered together, and appropriate pressure should be applied. This helps to expel the interface air, allowing the adhesive layer to fully contact the adhered object and form a uniform adhesive film.
Fourth, strictly control the curing conditions
The curing speed and final performance of
Polyurethane Adhesive are significantly affected by temperature and humidity. Most products require a certain temperature (such as room temperature above 25℃) to be fully cured. Moisture-curing one-component polyurethane adhesives particularly require a certain level of humidity in the environment, but excessive humidity can cause bubbles to form on the surface of the adhesive layer. Therefore, it is necessary to ensure that the curing environment is well-ventilated and has appropriate temperature and humidity. After applying pressure, there should be sufficient standing time. Do not move or test the strength too early. Ensure that it is fully cured (usually it can reach the initial strength in more than 24 hours, and complete curing may take several days).
Summary
Successful bonding is a systematic project. From surface treatment, precise proportioning, proper coating and pressing to strict control of curing conditions, no step can be neglected. Only by following these tips can we ensure that the polyurethane adhesive achieves the desired bonding effect.
