Product characteristics

Hydrex® is a synthetic magnesium alumino silicate manufactured by precipitating sodium silicate solution  with a mixture of magnesium and aluminium sulphate. It is used as a filler in wood-containing printing papers as well as wood-free fine paper and multilayer board to improve optical performance, printability and friction. The precipitating conditions for Hydrex® are carefully engineered and controlled. Thus the size and form of the primary particle of the agglomerates are carefully designed and maintained. Hydrex® is manufactured using raw materials thoroughly approved by Huber Engineered Materials in order to ensure a consistent high quality product free of contaminants. Hydrex® maintains a Food and Drug industry level of purity. Due to the pigment precipitation technique, no dispersion aids are required. The synthetic origin of Hydrex® allows long shelf life without the need for biocides.

Optical properties

Hydrex® significantly improves the opacity of paper. This is because the light scattering ability of Hydrex® is very high, almost 500 m2/kg. Thus it is able to enhance the paper's light scattering almost tenfold compared to fiber. The chemical composition of Hydrex® results in a high refractive index. Hydrex® provides the paper with a significant number of light scattering interfaces between air, pigment and fiber. This gives Hydrex® the power to increase opacity at low addition levels. Hydrex® inherently is an ultra-bright pigment, and it significantly increases the brightness of paper. While maintaining paper brightness, bleaching can be reduced, resulting in substantial cost savings.

Printability

Hydrex® improves the paper's printability: The high absorption capacity of Hydrex® increases the print image density thus reducing ink demand. Hydrex® keeps the ink at the paper surface and prevents the ink from migrating into the sheet. Hydrex® reduces strike-through and show-through by preventing ink and solvents from penetrating the paper. As a result, opacity is maintained. Hydrex® can also help in reducing registration problems in multicolor printing presses by increasing paper friction.

Friction Control

Certain furnishes tend to produce paper which has a low coefficient of friction. This can cause winding problems like snaking of the paper web, wrinkles, loose winding and telescoping of the reels. Another problem is slippage during paper transport, which shows up as breaks at the printing house. Hydrex® can solve all of these problems. Typically 1 % Hydrex® in the web increases the kinetic coefficient of friction by 15 %. At the same time an increase in optical properties can be noted.

Low Abrasiveness

Most pigments for filler or coating use tend to cause wear of the paper machine's parts like wires, foils and suction boxes. Also, printing presses and slitter knifes are subject to abrasion. Synthetic silicates reduce the wear substantially due to their amorphous nature with rounded surfaces and pores. In addition Hydrex® is free of abrasive contaminants. As a result, the abrasiveness of Hydrex® is very low.

Interested in using Hydrex in your next paper formulation?

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