Solvent-less silicone oil coating technology is very complex and has many technical difficulties in the process.With continuous technical innovations,solvent-less silicone oil coating technology has the advantages in health,environmental friendship,energy consumption,security,efficiency and practical value,making it as one of the solutions to overcome the two most pressing problems-energy shortage and air pollution.
In solvent silicone coating,using more solvent to dilute the silicone oil in low grammage is the common way.It has advantages in precise control of viscosity and release ability.But the disadvantages are obvious that it uses a large amounts of toxic organic solvents that can pollute the drying devices and working environments.In solvent silicone oil coating,microgravure coater is the most widely choice due to its simple structure and easy coating weight control.But it’ hard for it to reach the accuracy within 0.1 g/m2,and the pre-reaction between silicone oil and solvent in the grooves can affect the coating weight obviously and need time to stop for cleaning the impurities.To solve these problems,the coating unit are specially designed into 5-roller type to achieve more precise coating weight control and continuous production.The structure are as followed:

Roller A is coating roller,used to coat the paper;Roller B is rubber transfer roll,used to transfer the silicone oil to roller A for coating.Roller C is metering roller and roller D is fixed roller for scraping extra chemicals on roller C.The silicone oil is kept between roller C and roller D with flaps on the both sides.The coating weight can be easily controlled by adjusting the speed of different roller and the silicone oil is precise metering control of feed according to coating requirements.These functions can be easily achieved by fully automatic computer system control.
 Besides coating units,there are still some necessary parts need to be considered.Unwinding and rewinding devices,drying systems,measuring and dispensing system.The key points of the whole line is the coating weight control,coating curing,humidification system and feeding devices.
Due to the small amount of silicone oil coating, it is required that the silicone oil can be very evenly distributed on the surface of the substrate during coating, so the accuracy of the coating device must be improved. In the coating process, the accuracy of low coating amount is ensured by the speed difference between rollers and the gap between the two measuring rollers.In fact, as long as the metering roller C and the coating roller A maintain a certain speed ratio, the coating amount can be maintained in the required range. When the coating amount changes, the speed difference ratio between the measuring roller, the transfer roller and the coating roller needs to be adjusted or the clearance distance between the measuring roller and the fixed roller needs to be adjusted at the same time.
It is necessary to add a humidification system to the coating line to improve the moisture content of high temperature storage and the flatness and flexibility of the paper. First of all, the silicone coating side not only has the moisture that is not willing to take away, but also has the moisture that is tightly combined with the coating. The uncoated side can become hardened to prevent deflection, so the humidifier requires very good diffusion and excellent drips. In addition, the paper has a certain polarity, and the humidifier can also resist the folding of another load. The humidifier is located after the drying device and before the winding device, and in most cases is a mechanical combination.
Silicone oil feeding method is generally automatic gluing machine. An air filter may be provided over the applicator head and coating assembly to prevent possible adhesive vapors during operation. Since solvent-less silicone oil has a certain tank life, it is important to design the feed tray to ensure consistent flow and non-stagnant discharge for silicone oil recirculation. In addition, the total foam of the coating unit depends on the linear speed of the roller in the feeding tank.
 Whether it is in environmental protection, production safety and stability, improve product quality, or reduce production costs, improve market competitiveness, the use of solvent-free silicone oil coating is very favorable. It is a kind of production method worthy of vigorous advocacy and practical value, and should pay great attention to solvent-free silicone oil coating technology.
We,Qingdao Jieruixin M&T CO LTD,are specialized in paper coating machine design and manufacturing for decades.All series of paper coating solutions can be comprehensively supplied for your request.Please don’t hesitate to contact us if you want to put your effort in paper coating industries.