The invention relates to a
levelling agent and a preparation method and an application thereof. A
structural formula of the
levelling agent is as shown in the following specification, wherein n is a number between 5 and 10. The
levelling agent has the good film-forming property, and contains abundant ester groups, and is capable of combining with dye through a
hydrogen bond, thereby uniformly carrying the dye to the surface of fabric and forming a film in uniform thickness, enabling the dye to be uniformly adhered to the fabric, and preventing the non-uniform dispersion because of the short
contact time of the dye and the fabric. In addition, the film can also prevent migration and sublimation of the dye in a
drying and color development process, and the
chromatic aberration of a warp direction, a weft direction and positive and negative faces of the fabric is prevented. The levelling agent is suitable for continuous padding-type
dyeing and
coating-type
dyeing. Compared with vat dyeingin high-temperature and high-pressure, the
energy consumption can be reduced, the
dyeing efficiency is improved, and the product quality is improved, the color fastness of the fabric and the color uniformity reach a A-grade level stated by a
national standard, so the vat dyeing in high-temperature and high-pressure can be possibly replaced by the continuous dyeing in normal pressure and temperature.