新闻资讯

The flame retardancy of pressure-sensitive flame retardant adhesive is usually in conflict with its three properties (peeling force, holding power, initial adhesion). In order to obtain a certain flame retardant properties and add more flame retardant fillers, will inevitably make the adhesive initial adhesion and peel force decreased; flame retardant fillers add a small amount is difficult to achieve satisfactory flame retardant properties. At the same time, the addition of flame-retardant fillers will lead to adhesives in the storage and use of the phenomenon of sedimentation, seriously affecting the normal use of adhesives.

Fumed silica is mainly made of silicon halide in the hydroxide flame first high temperature hydrolysis, and then condensation of amorphous nanoscale particles, with high purity, porous, high temperature resistance and other characteristics, its particle size is small, the specific surface area is large, in the matrix resin can be better dispersed, for many polymer materials can improve its heat resistance, so it has a good comprehensive performance in processing performance, flame retardant properties.

The oxygen index (OI index) is the concentration of oxygen required for a material to reach its ignition point. Generally speaking, the higher the OI index of a material, the higher the oxygen concentration required for ignition and the less likely it is to ignite, and vice versa. It is generally believed that the OI index of the material is less than 21, belongs to the flammable material, 21 ~ 27 belongs to the flame retardant material, more than 28 belongs to the flame retardant material.

Take solvent-based acrylic adhesive as an example: add appropriate amount of fumed silica in acrylic adhesive, the three physical properties of the adhesive has less impact, and at the same time can play a thickening thixotropic, anti-settling effect, but also on the adhesive flame retardant has a certain role in promoting. In the acrylic system without the addition of flame-retardant fillers and fumed silica, its OI index of 18; add flame-retardant fillers, OI index of 28; in the case of keeping the amount of flame-retardant fillers unchanged, the addition of 1% fumed silica, the OI index can reach 30. with the increase in the content of fumed silica, the OI index increases with the increase in the amount of fumed silica when the amount of fumed silica to reach 5%, the OI index can reach 40. This shows that fumed silica in the field of flame retardant adhesives application prospects are very optimistic.