Language

Soft roller calender is a calender group consisting of a combination of hard and soft rollers. Hard roller: hot roller, cold casting roller, the surface hardness is high, smooth like a mirror surface, with oil or water outside the machine heating to the roller, also useful induction electric heating, roller surface temperature from 120 degrees to 200 degrees, up to 230 degrees. Soft roller: controllable middle and high roller, the surface is made of special polymer, which requires high temperature and high pressure resistance, good elasticity, and can withstand frequent changes in load. The main materials used are epoxy resin, nylon,synthetic rubber, polyester urethane, etc.

Chinese name

soft calendering technology

Composition

Hard and soft rolls

Type

calender unit

Materials

Epoxy resin, nylon, synthetic rubber,

Principle of action

In operation, the paper sheet is in contact with the hot roller. In a short period of time, the hot roller transfers heat energy to the paper and penetrates to a certain critical depth (usually considered to be м 0.007 μ). At this time, the temperature of the paper surface reaches or approaches the softening point of the glass. At this time, the paper surface is plastically strengthened, while the soft roller deforms elastically when pressed, and the pressing area forms surface contact. The hard roller of the mirror surface is like a press mold to make the paper surface smooth and smooth, and retain a good thickness.

 

Product Advantages

 

Compared with hard calendering, it has the following advantages:

① The tightness of the pressed paper is consistent

The calender roller with higher elastic modulus is generally 500-50 times softer than the steel roller. When the elastic roller is in a certain line

When pressed to a hard roll or a chill cast iron roll, the nip width becomes much wider than when the steel-steel roll contacts. The peak pressure decreases with the reciprocal of the nip width, the contact surface is no longer a plane, and the total radial compressive deformation of the steel roll is small (0.2-2%) along the radius of curvature of the steel roll.

In the steel-to-steel nip, if there are uneven patches in the sheet, the pressure is not uniform. When there are too many thick plaques or flocculation blocks on the paper entering the pressure zone, the pressure will be the highest here and the surrounding area will be lower. The overall result is that areas of high fiber density of the web will appear in areas of low fiber density of the same sheet thickness, the latter being subjected to a lower nip pressure impact. When the paper sheet is pressed in the calender roller of the elastic surface layer, the concave depth of the hard roller pressing into the surface layer is large enough that the change of the thickness of the paper sheet will not change the peak pressure (peak pressure is the highest pressure of the center line of the nip).

② Even if the paper uniformity is not good, its opacity can be improved, and eliminate color spots.

Due to the rebound of the soft roll surface material, the roll surface can adapt to any poor uniformity and quantitative changes in the paper sheet. Paper thin area and hot roller contact, at the same time for the thick area, the thickness will not be greatly reduced, such a thick and thin area can increase its fine smoothness, eliminate the color spot.

③ Good absorption of printing ink

Due to the tightness of the paper sheet and the thickness reduction is not very large, the oil absorption film of the pressed paper is good and uniform.

④ It is possible to make the finished product have higher moisture

Because the paper pressing black and color spots are basically eliminated in the soft roller nip, the paper sheet can enter the nip under high moisture.

⑤ ImprovedPaper bulkand maintain the stability of the stiffness.

The stability of soft calendering and line pressure adjustment range is large, can adapt to the requirements of different paper calendering finishing.

⑦ Because the fiber is not strongly squeezed, the paper sheet strength is good, which improves the social preparation operation rate.

⑧ High smoothness can be obtained and two-sided difference is eliminated.

and super calender ratio:

① The maximum allowable temperature of super calendering cannot exceed 85 degrees, and the temperature of soft roller calendering can reach 160-200 degrees

Soft calendering can be at the same speed as the paper machine or coating machine, and the speed does not need to be reduced when the paper is introduced.

The soft roller grinding roller interval time and service life is much longer than the paper roller.

④ Overpressure is difficult to control paper thickness

⑤ Overpressure covers a large area, high cost of packaging plastic surface and grinding roller, and high investment.