Hexamethyldisiloxane manufacturer introduces the use of water-based polyurethane adhesive:
When water-based polyurethane adhesives are used in adhesives, they must generally be formulated to suit construction conditions and substrates. Based on water-based polyurethanes, crosslinkers, thickeners, fillers, plasticizers, For pigments, other additives, other types of water-based resins, and water, the slurry must be stirred uniformly before sizing. It is also necessary to consider whether the additives have any effect on the short-term stability of the water-based polyurethane. In order to obtain higher water resistance, heat resistance, and Bond strength.
At present, many water-based polyurethane systems have popularly used crosslinking agents to form a two-component system, which is similar to a one-component solvent-based (volatile type) polyurethane adhesive system. The pigments generally must be pre-dispersed in water, and then water-based polyurethane is added. Thickeners are generally added at the end, but additives such as thickeners and surfactants are hydrophilic, which may affect the water-resistance, humidity, and heat resistance of the adhesive layer.
The sizing method of the water-based polyurethane adhesive is basically the same as that of the solvent type, such as manual brushing, mechanical roller coating, spraying, etc. When spraying, pay attention to the particle size and viscosity of the emulsion.
Bonding methods include wet bonding and thermal activation.
(1) Wet lamination For porous substrates, after coating at room temperature, they can be directly laminated and pressurized for bonding. The wet lamination method is also the most commonly used bonding construction method for water-based resin adhesives.
(2) For non-permeable substrates, after the adhesive is coated and dried, it can be thermally activated with hot air, infrared lamps, ovens, or drying tunnels. That is, dry lamination, that is, heating to melt the adhesive layer that has no tack on the surface after coating and drying, to impart adhesiveness, and the resin recrystallizes after lamination to immediately obtain a higher initial bonding strength. The bonding method requires a low thermal activation temperature in industrial operation.