Influence of adhesives
(1) Aluminum honeycomb panels produced with polyurethane and epoxy resin reactive curing adhesives are characterized by simple process and low energy consumption. Polyurethane adhesives are flexible and resistant to temperature differences, but they are sensitive to moisture during application and have high requirements for the adhesive environment; epoxy resin adhesives are characterized by good adhesion to aluminum, high temperature resistance, and little effect of moisture. Their disadvantages are that the adhesive film is brittle and the peel strength is not high.
(2) The bonding strength of aluminum honeycomb panels produced with epoxy film technology is low. For aluminum honeycomb panels with a honeycomb core side length of 4mm, a panel thickness of 1mm, and a total thickness of 10mm, the 180° peel strength is about 4N/mm. However, its bonding performance is weather-resistant and its peel strength decreases very little after one year of use. The disadvantage is that the bonding layer of the aluminum honeycomb panel is brittle and the aluminum honeycomb panel will delaminate after long-term vibration.
(3) The bonding strength of aluminum honeycomb panels produced by continuous lamination of thermoplastic film is 3-5 times that of aluminum honeycomb panels produced by the first two processes. For aluminum honeycomb panels with a regular hexagonal honeycomb core with a side length of 4mm, a panel thickness of 1mm, and a total thickness of 10mm, the measured 180° peel strength value is about 18N/mm. It has good adhesion and weather resistance, and its peel strength decreases very little after one year of use. Because it is a continuous production, it is efficient and can meet the requirements of short-term large-scale supply. The disadvantage of this process is that the plane continuous hot lamination machine used is expensive and requires huge investment. Thermoplastic film is a special hot melt film. The film itself must have high cohesive strength and tensile strength, which can ensure the strong bonding of the aluminum honeycomb panel. If a general hot melt film is used, its bonding strength is very low, and the 180° peel strength value is only 3N/mm.
Influence of production process
Aluminum honeycomb panels are produced by hot presses. Since the pressure of the hot press is large and difficult to control, pads are often placed to prevent the aluminum honeycomb core from collapsing. If the pad is too high, it will affect the applied pressure, resulting in low bonding strength. If a flat thermal laminating machine is used, since the pressure is provided by elastic force, the applied pressure can be controlled by adjusting the height. Therefore, the bonding strength of the aluminum honeycomb panel produced by this process is high and very stable.
Influence of surface conditions
The oil, dirt and naturally formed loose oxide layer on the aluminum surface will seriously affect the bonding effect of the aluminum honeycomb panel. Therefore, it must be cleaned and pretreated. The aluminum surface can be treated with phosphating or chromating to form a tight chemical conversion film on the aluminum surface. The treated aluminum has a good bonding effect.
