The selection of flocking fabric involves electrochemical knowledge to ensure the best quality of flocked products. The selection of the flock, adhesive, and pigment is crucial.
Flock: Nylon fiber and viscose are the most commonly used viscose materials. Its raw material is wood, which undergoes certain processing. The degree of polymerization is around 250-500, and the crystalline region of the fiber is about 30%-40%. This high crystalline region makes the dye penetration not particularly good, thus making it difficult to achieve a deep black color, requiring special dyeing methods and pigments. Furthermore, due to the lower degree of polymerization, the fiber strength is not as good as nylon.
Nylon fiber is a polymer material made of diaminocarbamic acid or propionamide and organic diacids linked by amides. It has high strength, is very wear-resistant, durable, and has considerable elasticity. Commonly used types include nylon 6 and nylon 66. The disadvantages of nylon 66 are that it yellows at 66 degrees Celsius, becomes sticky and softens at 230 degrees Celsius, and completely melts at 250 degrees Celsius. The disadvantage of nylon at 6 degrees Celsius is that it softens at 180 degrees Celsius and completely melts at 215 degrees Celsius.
Adhesives The adhesives used in flocking are divided into self-crosslinking adhesives and external crosslinking adhesives.
(1) Self-crosslinking adhesives contain groups in their molecules that allow the molecular chains to crosslink themselves, such as hydroxymethyl (-CH2-OH) and epoxy (-CH-CH2). They also possess a copolymerizable group, hydroxymethylacrylamide (CH2=CH-SONHCH2OH) or glycidyl methacrylate (CH2=C-COOCH2-CH-CH2), which opens double bonds and participates in the reaction when copolymerizing with other monomers.
Currently, both types of adhesives are used in flocking. Self-crosslinking adhesives have a longer effective shelf life. Using a small amount of crosslinking agent to increase the depth of crosslinking is more suitable for improving flocking fastness. External crosslinking adhesives, on the other hand, require the addition of some crosslinking agent and catalyst before use, and must be used immediately after preparation; otherwise, crosslinking will occur at room temperature, affecting their performance.
