Foaming tape is an essential foaming material in foamed metal products. It is an effective way of foaming the metal to reduce weight. The foamed product of foam tape depends on its chemical composition and production process. Some foaming tapes have lower foaming performance, some have sound foaming effects, and some can even be foamed into a high-grade spherical shape.
Several domestic manufacturers have attempted to produce foaming tapes, but due to poor quality control, inferior products have been produced and sold with horrible quality. In this paper, we focus on the three types of foaming tapes used by manufacturers today: Water-reducing type air volume reducer, Water-reducing rubberized foaming tape, foamed glass-fiber-reinforced silicon rubber foaming tape.
Water-reducing type air volume reducer (foaming agent)
The foaming agent used in the water-reducing type air volume reducer is mainly polyacrylate polymer dissolved in water. The foaming agent should have the following characteristics: It should produce a large number of bubbles. There are too many or not enough bubbles, affecting foaming quality; good foaming agents have high foaming capacity and expandability.
Second, after foaming, there must be no free water on the surface of the metal product. If foamed products are placed in open-air, they will absorb atmospheric moisture very quickly, and this will cause foaming tape residues.
Third, the foaming agent should have good foaming adhesion to the foamed metal product. Suppose it does not present a substantial foaming effect after foaming. In that case, there is no meaning in using this product because the strength of a foamed metal plate is determined by its initial form – if it can be foamed into a spherical shape, then the sphericity and other parameters for grading are much better. The steel sheet should have a pre-coat so that foaming agents can attach closely to the surface of the steel sheet and quickly spread throughout the gel layer formed on top of surfaces after quenching to achieve rapid heat conduction from inside to outside and increase bubble size.
Water-reducing rubberized foaming tape
This foaming tape is foamed using SBR rubber, which is foamed when the product’s surface is coated with foaming solution, then it will be foamed into a spherical shape in open-air. The main difference between this kind of foaming tape and other foaming tapes in terms of chemical composition is that SBR rubber has a better foaming effect than polyacrylate polymer. It can produce more bubbles and form spherical shapes, which are very important in improving sphericity. The sphericity index for determining grading accuracy used by manufacturers can get higher grades due to this unique property of SBR rubber. If the grade requirements are not high, then water-reducing type foaming tape is recommended because foaming tapes containing SBR rubber are relatively expensive.
Foamed glass-fiber-reinforced silicon rubber foaming tape
This foaming tape is not only foamed with foamed agents but also has the function of fiber reinforcement, which can be used for rafters, beams, and other large structures. It is mainly composed of (SiO2 + CaCO3) particles dispersed in a polymer matrix; it uses foamed glass fiber as a base structure to increase its mechanical strength. This kind of foaming tape has an excellent foaming effect after foaming, no free water on the surface, and high standards in terms of sphericity (if the manufacturer’s requirements are not too high).