Common faults and troubleshooting of varnish for t

Common faults and troubleshooting of varnish for printing foil paper

1 Pinholes and snowflakes

main reasons:

① there is oil stain on the surface of aluminum foil

② there is too much plasticizer and viscosity in the primer or white paint system

③ equipment consumables caused by uneven surface of mechanical roller or substrate

elimination method:

① remove the oil stain on the surface of aluminum foil or replace the aluminum foil:

② add TX or TM-3 coupling agent into the bottom oil and white paint

③ replace the roller with smooth surface or replace the aluminum foil equipment consumables for printing

2. Poor gloss

main reasons:

① the surface of aluminum foil is rough and uneven, and the adsorption ink is large

② the polish is turbid, opaque and of poor quality

③ the viscosity of glazing oil is low and the coating is too thin

④ the glazing temperature and pressure are insufficient for printing in the middle

Troubleshooting:

① replace the roller coating roller or empty coating for a period of time, and then polish

② choose transparent and good leveling polish

③ choose the glazing oil with high resin content and low viscosity in the glazing oil system

④ adjust the working temperature during glazing to close to the vitrification temperature of glazing oil and increase the roller coating pressure printing tool

3. Uneven and luminous

main reasons:

① poor adhesion of polish or primer to ink

② the viscosity of polish is too low

③ ink layer is too thick or ink film crystallization printing alliance of printing ink

Troubleshooting:

① add an appropriate amount of surfactant into the glazing oil to reduce the surface tension of the glazing oil

② increase the viscosity of the polish or add new polish to the adjusted Polish:

③ add TM-3 coupling agent from Tianyang chemical plant to the polish or roughen the surface of the printing ink film for central printing

4. The coating is easy to burst and not folding resistant

main reasons:

① the temperature in embossing is high, which makes the printed matter, especially the resin in the varnish ink system, brittle after too high hardness

② the pressure of embossing and die-cutting is high, which makes the extension and flexibility of the printed matter after polishing worse

③ improper die cutting, embossing, punching or folding

④ poor adhesion between varnish and ink, equipment consumables

Troubleshooting:

① reduce the embossing temperature, or choose a polish with moderate hardness

② reduce the impact pressure of embossing, die cutting and punching

③ if it is caused by improper die cutting, the longitudinal specification should be used as the production basis for printing die cutting, embossing, punching and folding

as far as possible in the packaging printing design and plate making (the tensile strength of aluminum foil is different due to transverse and longitudinal)

④ replace the base oil or polishing oil with good affinity with the ink, or increase the printing pressure on the printing market

5. Adhesion

main reasons:

① the Polish dries too slowly or not completely

② the polish coating is too thick

③ small blowing, short drying path, low temperature, or weak UV intensity

epoxy resin keeps up with the rapid development of hp-rtm: this high-pressure RTM equipment used by British professional automobile manufacturer penso consulting ④ printing alliance with high substrate accumulation after polishing

Troubleshooting:

① use fast drying polish

② reduce the coating amount of varnish and thin the coating varnish film

③ strengthen the blowing or adjust the blowing angle, extend the drying channel, increase the temperature of the drying channel or the intensity of ultraviolet light

④ try to avoid the substrate piling up over the advanced printing alliance

6. The main reasons for the flake falling off are:

① the surface of the aluminum foil of the substrate is uneven

② the polish or primer is not firmly attached

③ insufficient printing pressure or too much embossing pressure in Central China

Troubleshooting:

① select aluminum foil with flat surface

② choose polish or primer with good adhesion fastness, or add 1% - 5% mixed additives PPH or 4011

③ increase the printing pressure, or reduce the embossing pressure printing technology

7. Fading, discoloration and yellowing

main reasons:

① glazing is for the convenience of oil cooling, and the pH value of the oil or base oil is inconsistent with the ink

② the temperature of the drying film-forming process of varnish is too high during oxidative polymerization, resulting in yellowing

③ polish or primer itself is not resistant to high temperature

④ high temperature resistant printing alliance of pigments and dyes in printing ink system

Troubleshooting:

① replace the glazing oil or base oil that is consistent with the pH value of the ink:

② control the drying of the glazing oil, causing two times of purification drying temperature

③ choose high temperature resistant polish or primer

④ printing technology of replacing high-temperature printing ink or adding organic fillers such as calcium and silicon

varnish foil printing because of the special surface characteristics and texture of the printing materials, it is very harmful to varnish earthquakes in natural disasters and has high requirements. More application experience of

needs to be carefully summarized and summarized in practice in Central China