Paraffin is not only the earliest water repellent finishing agent used by human beings, but also the most economical water repellent finishing agent. It can form a hydrophobic film on the fiber surface and has good air permeability . When finishing, the fabric can be treated with organic solvent, lotion and molten state of paraffin. Under the action of heat, paraffin penetrates into the fiber to wrap the fiber and endow the fiber with water repellency.
The water repellent agent of aluminum soap is generally aluminum formate or aluminum acetate. After the aluminum salt is prepared into an aqueous solution, the fabric treated with soap solution is immersed in aluminum salt solution, and the aluminum soap formed after the finishing solution is dried is deposited on the fiber surface, so that the fabric obtains water repellency . Usually, in order to improve the water repellent effect, paraffin and aluminum soap are mixed and dispersed into water for reuse. This kind of water repellent agent is cheap, easy to apply, and has excellent water repellency and air permeability. However, there are serious defects, such as poor washing resistance and rough hand feel. The research shows that after replacing aluminum salt with zirconium salt, the water repellency of the finished fabric is still good and the washing resistance is significantly improved. This is because the stability of zirconium salt in alkaline solution is higher than that of aluminum salt, and zirconium salt also has a fixing effect on paraffin. Zirconium salt can also be used alone for water repellent finishing of fabrics, but the effect is significantly improved when used together with paraffin.
Stearic acid water repellent agent, this kind of water repellent finishing agent first appeared in the 1930s. It is mainly synthesized from stearamide, formaldehyde and melamine. The long-chain alkyl group in stearic acid has hydrophobic properties. The N-hydroxymethyl group can react with the hydroxyl group in the fiber or the finishing agent itself to form a network structure, which makes the water repellent finishing effect of the fabric durable and gives the fabric a plump feel . The disadvantage is that the finished fabric has the problem of formaldehyde emission, which has an adverse impact on the natural environment and human health
