Decorative paper impregnation process

To create paper resistant to environmental factors, decorative papers are impregnated with phenolic resins. This process is carried out by a 55-meter-long impregnation line. Two resins, phenol formaldehyde and urea formaldehyde, are used to impregnate decorative paper .

These two resins enter the paper cells in two stages, creating a saturation level with an equilibrium percentage of 60 to 200 percent.

This line has several stages and stations for the impregnation process as follows:

1.       Motion rolls

2.       Impregnation roller

3.       Dip pans

4.       Drying tunnels

5.       Cooling tunnel

6.       Cooling rolls

7.       Paper collectors

Motion rolls

All moving rolls are driven by servo motors and convey decorative papers along the line at a uniform speed. Due to the exposure of these moving rolls to resin and high heat, the surface of all these rolls is covered with a chrome layer to ensure longer useful life and efficiency. The conveying speed of these rolls is between 35 and 40 meters per minute .The paper transfer between these rolls is done at different stages by

Auto Splicer  This system maintains the continuity between the decorative paper rolls during the impregnation process and prevents the paper from breaking along the way. The rolls have Infrared sensors at the end and the beginning that are connected to two servo drive motors and control the centering of the paper movement along the way The primary rolls of the machine, which are responsible for unwinding and pulling decorative papers from the main rolls, have an automatic paper tension control system built into them, which prevents the paper from tearing during the impregnation process

Impregnation rollers

mesh -like and grooved manner so that the resin that is impregnated on the surface of the paper does not stick after being placed on these rollers and the continuous movement of the decorative paper along the line is maintained. Another reason for the mesh-like shape of these rollers is their cleaning and ease of cleaning these rollers, which is done very quickly due to their mesh-like construction

Dip pans

The decorative paper is fed into these trays filled with phenolic resins by conveyor rolls and after the decorative paper cells are filled with resins, it is removed from the other side of the tray by conveyor rolls. The temperature of the resin and the amount of resin surface in these trays are constantly measured by thermal and surface sensors. The wall layer of these trays is covered with galvanized materials to reduce erosion due to environmental factors and to prevent heat loss from the walls

Hot air drying tunnels

To remove the gases generated from the surface of the decorative paper after impregnation, tunnels, each three meter  long, are used. All walls of these tunnels have 4 blower plates at the top and bottom, and ten blower plates are installed in the side walls. The thickness of these walls is 120 mm in diameter and covered with rock wool, which causes the least waste of thermal energy during the paper drying process.

In all tunnels, hot air is circulated at a speed of Eighteen cubic meters per hour   by blowers with a diameter of 8 cm. To check and measure the amount of hot air flow and the temperature of the circulating air, a central control system is installed in the main panel of the production line, which measures these two factors at all times in all tunnels and controls their number according to the current need

Cooling tunnel

After the decorative paper has been impregnated and dried, the paper temperature must now return to the standard ambient temperature to maintain the properties of the impregnated paper and bring the temperature of the resins that have penetrated the paper cells closer to ambient temperature

The importance of this process is that if the resin is kept at a high temperature for a long time, the transparency and gloss of the resin molecules will be lost and the color of the impregnated paper will become dull after pressing on MDF sheets . This tunnel is 1 meter long with 2 fans with a power of 3.7 kW and an air circulation equivalent to 5,000 to 10,000

Ventilation and hot air exhaust system

Along the impregnation path, exhaust pipes and fans are installed for the drying and cooling tunnels. This entire process is controlled with high precision by thermal sensors and hygrometers, and as soon as needed, high-power fans begin to expel excess hot air along with the gases created

Impregnated paper collector and cutter

After producing the impregnated sheets, which are converted from decorative paper rolls to sheets, the impregnated sheet cutting system is installed at the end of the production line to cut the impregnated papers into specified lengths with great power and precision. To prevent the impregnated paper from moving during cutting, the rolls in this section are covered with a special plastic coating to prevent the paper from moving during cutting

Packaging

After cutting the impregnated paper sheets, these sheets are stacked on top of each other in the ordered number of pallets and covered with insulating nylons so that the ambient humidity does not negatively affect them and does not cause adhesion between the papers. And the temperature