Paper transfer color technology question and answer

What are the requirements for preventing the transfer layer from exploding to the paper fibers?

Answer: Generally, the fiber of paper is long fiber, and its flexibility is good. Conifer and broadleaf pine are the most suitable. And need to be arranged in accordance with the vertical direction of the fiber in order to basically meet the transfer paper cut into small sheets do not burst color (referring to the pressure burst aluminum layer, due to the ink covering the surface of the transfer layer, can more clearly see the color burst), no distortion.

What are the requirements for preventing the moisture content of the paper on the transfer layer?

Answer: The water content of the bottom paper is too high, the indoor temperature and humidity are not stable, the transfer paper is easy to be deformed, and there is a phenomenon of a lotus leaf edge with uneven shape. The water content of the transfer paper will be released to varying degrees with changes in storage time and storage temperature. The excessive release of water from the transfer product causes the paper fibers to become relatively hard and brittle. After die-cut indentation, the paper fibers hardened at the indentation are destroyed to varying degrees. Generally, the moisture content of the transfer paper is controlled at 6%, the temperature of the printing shop is controlled at 18°C ​​to 25°C, and the humidity is controlled at 60%±5%.

What are the requirements for preventing the color of the transfer layer from exposing the adhesive?

Answer: The adhesion of the aluminum layer on the transfer paper surface mainly depends on the adhesive properties of the initial dry adhesive and the coating amount. The amount of coating also directly affects the color burst phenomenon. The amount of coating is too small, the amount of adhesive penetrates into the paper is small, the transferred aluminum layer is not easy to completely peel off, the film layer after drying is thin, and it is not easy to resist strong pressure; When the amount of cloth is too large, it is easy to squeeze the glue when the paper and film are compounded. If the temperature of the oven is improperly adjusted, the film forming property is poor, and the connection with the aluminum layer is not strong.

Different coating amounts should be selected according to different papers. For example, for a one-side coated white cardboard with a basis weight of 225 g/m2, the surface finish is high, the fibers are tightly arranged, the stiffness is good, and the surface of the paper is instantly absorbed. Poor, the amount of glue should not be too large, generally controlled at 1.5g/m2 ~ 2.0g/m2; for relatively poor surface finish paper, the amount of glue is generally 2.0g/m2 ~ 2.5g/m2 is appropriate.

What are the requirements on the performance of the adhesive to prevent the discoloration of the transfer layer?

A: At present, most of the transfer paper used in China is a wet transfer method. That is, the transfer adhesive is applied to the aluminum layer or paper surface of the transfer film, and then compounded with paper or a transfer film. After the oven is dried, it is peeled offline or The combination of direct stripping and transfer.

For the wet transfer method, the initial drying performance, drying performance, film forming performance, water resistance (water does not re-dissolve after drying), anti-solvent performance, anti-ultraviolet irradiation performance, anti-friction performance, and resistance to the used aqueous adhesive High-strength pressure performance, high temperature resistance, etc. are all required. The specific requirements for the main performance are as follows.

(1) Requirements for the initial dry performance of the adhesive: After the composite paper passes through the oven, the adhesive should be dried and filmed under certain temperature control conditions, and the adhesive and paper after the initial drying and the transferred aluminum layer The fastness of the bond is sufficient to completely strip the transferred aluminum layer.

(2) Requirements for adhesive viscosity: At present, there are many production equipments for domestic production of transfer paper, such as dry compound-stripping, wet compound-stripping, film coating or paper coating, whichever method is adopted Transfer paper, the viscosity of the adhesive control is more important. The viscosity of the adhesive is too low and the vehicle speed is too fast. When the composite roller is passed through the composite roller, the plastic extrusion phenomenon easily occurs and the adhesive strength of the colloid is affected. If the viscosity of the adhesive is too high and the vehicle speed is too fast, the coating is not uniform, which affects the transfer of the aluminum layer, resulting in incomplete peeling. Therefore, it is necessary to select an appropriate adhesive viscosity according to different compounding methods, drying methods, and coating methods.