Water Transfer Process Control Analysis (I)

Water drape process

(1) Film activation

The water drape transfer film is laid on the surface of the transfer water tank with the graphic layer facing upwards to keep the water in the water tank clean, and is basically in a neutral state. The activator is used to uniformly spray on the surface of the graphic text, so that the graphic The layers are activated and are easily separated from the carrier film. The activator is an organic mixed solvent mainly composed of aromatic hydrocarbons. It can rapidly dissolve and destroy polyvinyl alcohol, but it will not damage the graphic layer and leave the graphic in a free state. The principle of film activation is shown in the figure below.

Water drape schematic

(2) Water drape transfer process

Items that will require water transfer will gradually come close to the water transfer film along its outline, and the graphic layer will be slowly transferred to the surface of the product under the effect of water pressure, due to the inherent adhesion of the ink layer and the printing material or special coating. Adhesion. During the transfer process, the speed of the substrate and the water coating film should be kept uniform to avoid film wrinkles and make the image unsightly. In principle, we should ensure that the graphic texts are properly stretched to avoid duplication. In particular, overlapping areas and excessive overlap will give people a sense of disorder. The more complex the product is, the more demanding the operation is.

Water temperature is an important parameter that affects the quality of the transfer. If the water temperature is too low, the solubility of the substrate film may decrease. If the water temperature is too high, it may cause damage to the graphic and cause graphic distortion. The transfer tank can use automatic temperature control devices to control the water temperature within a stable range. For the relatively simple and unified large-volume workpieces, special water transfer equipment can also be used instead of manual operations, such as cylindrical workpieces, which can be fixed on the rotating shaft, and the graphics layer can be transferred by rotating on the surface of the film. Water drape transfer process as shown.

Water drape film transfer process

After the transfer blanket graphics, the following steps should be taken:

1 Finishing

Remove the workpiece from the water tank, remove the remaining film, and then rinse with water to remove the floating layer that is not fixed on the surface of the product. Pay attention to the water pressure can not be too much, otherwise it is easy to damage the image of the transfer.

2 drying

The moisture on the surface of the product is removed to facilitate thorough drying of the transfer ink layer; to increase the attachment fastness, it can be dried by a hair dryer, or it can be dried in a drying box. Drying temperature of plastic products can not be too high, roughly 50 ~ 60 °C, the temperature is too high to easily make the substrate deformation; metal, glass, ceramics and other materials, the drying temperature can be properly increased.

3 spray protection paint

In order to enhance the resistance of the graphic layer to the environment, it is necessary to paint the surface. Spray paint can use solvent-based varnish, natural drying or heat drying after spraying; also use UV varnish, UV curing and drying. In contrast, UV curing is more adaptable to environmental requirements.

Solvent-based varnish must be mixed with supporting hardeners, such as water-transfer spray varnish sold by Dongguan Changan General Appliances Co., Ltd., which is a varnish with polyurethane resin as the linking material and should be used with PU hardener; The thickness can be controlled by adding an appropriate amount of thinner to improve the viscosity of the varnish; note that it cannot be dried in the oven. For different substrate materials, Varnish is also divided into three types, namely Varnish for plastic materials, Varnish for flexible materials, and Varnish for non-absorbent materials such as metals and glass.

(to be continued)