Ten questions and answers about printing and printing

1 What is the requirement for paper on the transfer layer burst color?

Answer: Generally, the fiber of the paper is long fiber, and its flexibility is good. Conifer and loose leaf pine are the most suitable. It needs to be arranged perpendicularly according to the direction of the fiber, so as to basically meet the requirement that the transferred paper is not easily discolored after being cut into small pieces, and it is not easy to distort and deform.

2 What are the requirements for the moisture content of the transfer layer in the transfer layer?

Answer: The water content of the bottom paper is too high, the indoor constant temperature, the constant temperature are unstable, the transfer paper is easy to change, and the edge and convex shape of the leaf edge phenomenon occurs. The moisture content of the transferred paper will be released to varying degrees with the storage of time and temperature, and the amount of moisture released from the transferred product is too large, and the fibers of the paper become relatively hard and brittle. After die-cut indentation, the paper fibers hardened at the indentation are destroyed to varying degrees. General technical requirements for the moisture content of special transfer paper: 6%, the temperature control of the printing shop is: true 8-25 °C, humidity control: 60 ± 5 °C is appropriate.

3 What is the requirement for glue on the transfer layer?

A: At present, most of the transfer paper used in China is a wet transfer method. That is, transfer glue is applied to the aluminum layer or paper surface of the transfer film, and then it is compounded with paper or a transfer film. After oven drying, it is peeled offline or connected. The compound and transfer method that is directly left. The requirements for the use of water-based glue for wet transfer are generally the following: Initial drying performance, initial dry viscosity, directly affect the peeling effect; drying performance, directly affect the adhesion fastness of the aluminum layer: film deposition performance, water resistance ( The water is not easily re-dissolved after drying, anti-solvent properties, anti-ultraviolet irradiation performance, anti-friction, anti-high pressure, high temperature resistance; no brittle after drying, etc., directly affect the color of the transfer layer,


4 What are the requirements for the amount of glue applied on the transfer layer?

Answer: The adhesion of the aluminum layer on the surface of the transfer paper mainly depends on the adhesive properties of the glue and the amount of coating. The size of the coating also directly affects the color burst phenomenon. When the coating amount is too small, the amount of glue penetrating the paper is also small, the transfer aluminum layer is not easy to completely leave, the film layer after drying is thin, and it is not easy to resist strong pressure; when the coating amount is too high, the paper and the film are easy to be squeezed when compounded with the film, and the oven Incorrect temperature adjustment, poor film formation in early drying, and poor adhesion to the aluminum layer. According to different papers, choose different degrees of coating amount, for example: 225g/m2 single-side coated white card paper, its surface finish is relatively high, fiber males are arranged densely, the stiffness of the hand is strong, the paper surface instantaneous absorption performance
5 What is the requirement for the drying system when the transfer layer explodes?

Answer: For the drying system, the length requirement is 12-16m, and the temperature zone is at least 3 groups. The 4 groups are the best. Ventilation, ventilation should be relatively large, the hot air directly blows the back of the composite paper, at the same time according to different boot speed to adjust the temperature of different drying tunnel, the speed is slow and the temperature is correspondingly low. On the contrary, the deployment temperature of the optimal oven is: the vehicle speed is 100-125m/min, the first temperature zone of the drying tunnel is set at 100°C; the second temperature zone is set at 110°C; the third temperature zone is set at 110°C; The temperature zone is set at 90°C.

6 UV drying system on the degree of color impact?

A: The light source released by the UV lamp is a UV light source. The UV light has strong penetrability for general substrates. The greater the power of the UV lamp, the greater the penetrability is, for example: dark red, black, Deep blue, etc., the reflected light is not strong color under the same conditions, drying performance is relatively fast, the ink printed on the substrate on the thin and thick, the opposite light intensity will affect the degree of penetration of ultraviolet light to varying degrees. The reflective intensity of the aluminum layer is higher than that of the general UV ink, but the reflective intensity is greatly discounted after being covered tightly by the ink. When the UV rays penetrated through the aluminum layer, the dried film-forming limbs of about 3 sails were formed to various degrees of damage, resulting in an increase in the color of the detonation.

7 After the glue is dried, the indentation destroys it.

A: After the transfer of paper after a strong indentation, it is generally very easy to burst color (explosive color - refers to the pressure burst aluminum layer, due to the ink covering the surface of the transferred aluminum layer, the visual more obvious burst color), while the glue has a relatively high Claim. For different weights of transfer paper, the glue used to dry the film formation requirements are different, determine the temperature of the drying tunnel. The glue drying rate is controlled at about 80%. However, the colloidal tantalum has a strong tackiness (thickness is strong and easy to transfer aluminum layer stripping). Incompletely dried film-forming glue after a strong indentation, the color burst rate is relatively low. On the contrary, the glue film is relatively poor, and after being completely dried, it is easily damaged by strong indentation, resulting in a discoloration phenomenon.

8 What is the impact of the thin and thick layer of transferred aluminum (aluminum) on the color of the explosion?

A: The thinness and thickness of the transferred aluminum layer will affect the color bursting effect in different degrees. The thin aluminum layer can not cover the slight defects on the surface of the BOPP or PET film, and the quality of the transfer film is affected. When the surface of the paper is transferred to the surface of the paper, the concentration of aluminum is less, resulting in the unevenness of the surface of the paper. Vacuum aluminum plating has its molecular arrangement in an uneven state, and aluminum molecules are tightly hooked together to form a thin, dense layer. If the thickness of the transferred aluminum layer is less than 2.010-8, it is time. The fiber will slightly break the aluminum layer and the ink layer will also be damaged.

9 ink printing thickness of the transfer layer surface color impact?

A: The printing thickness of ink mainly depends on the engraving depth of the printing plate to control the printing volume of the ink, the number of engraving lines and the angle of the engraving needle to determine the depth of engraving, different printed matters, different printing processes, and the engraving process of the printing plate is different. The print thickness of the ink is also different. Connection gravure printing machine speed, ink viscosity is low. Compared with the same conditions, the ink sheet of a single sheet gravure printing machine should be thicker. However, the thinness and thickness of the ink layer can affect the color bursting, which is mainly determined by the soft and hard properties of the resin oil in the ink. At present, the system of gravure printing ink produced by many ink manufacturers in China is more suitable for printing. Extensively, for the discoloration phenomenon of the transfer products, the ink formulation has also been adjusted accordingly. No matter whether the ink thickness or thickness of the ink layer is concave or not, it will not affect the color burst.

10 What should be taken care of when choosing a glue to prevent the color of printed products?

A: One of the most common and difficult problems is to change the color of printed products. However, the selection of glue for transfer and the quality requirements for glue are relatively high. Such as the glue's initial drying performance, viscosity, adhesive strength, film forming properties, odor, folding resistance, solvent resistance, high temperature resistance and so on. Only good adaptability can produce the ideal transfer product.

Requirements for the initial dry performance of the glue: After the composite paper passes through the oven, the temperature of the oven is allowed to dry under a certain temperature control condition. The glue after the initial drying is bonded to the paper and the transferred aluminum layer, and the fastness of the adhesion is sufficient. Transfer the aluminum layer completely.

Adhesive viscosity: At present, there are more equipments for domestic production of transfer paper, such as dry compounding and leftover; wet compounding and peeling; film coating or paper coating. No matter which method is adopted to process and produce the transfer paper, the control of glue viscosity is more important. The viscosity of the glue is too low. When the speed is too fast, it is easy to squeeze the glue when passing through the composite roll, which affects the adhesive strength of the colloid. For example, if the viscosity of glue is too high and the speed is too fast, the coating will not be uniform, which will affect the transfer of the aluminum layer and cause incomplete peeling. Therefore, it is necessary to select an appropriate glue viscosity according to different compounding methods, drying methods, and coating methods.

Film forming property: The glue in the transfer paper cannot be completely dried, but its adhesive force after film formation needs to reach 80N, which is enough to adhere the adhesion of the aluminum layer to the standard of 50N pull force. The film forming property of the glue can directly affect the effect of the discoloration of the transfer paper. The good film-forming glue can enhance the flexibility and folding resistance of the paper surface, and at the same time, it also reduces the color burst rate.

Solvent resistance: Transfer paper is divided into the following layers: bottom paper, glue, aluminum layer, varnish. The film-forming glue is generally poor in solvent corrosion resistance, and its corrosion resistance time and anti-corrosion performance mainly depend on the anti-corrosion additives added in the glue to fully protect the film forming property of the glue. Solvents used in gravure printing are mixed high-boiling polar substances with strong corrosiveness, but the volatilization rate is relatively fast and can be volatilized instantaneously under suitable high temperature conditions of 65°C to 90°C. The film structure of the glue will not cause great damage.

High-quality transfer paper needs high-quality raw and auxiliary materials and advanced technology to produce environmentally friendly, high-grade, and high-quality products. (Text / Li Lianjun)