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Retention agents (retention aids) are used in the papermaking industry. These are added in the wet end of the paper machine to improve retention fine particles and fillers during the formation of paper. Retention aids can also be used to improve the retention of other papermaking chemicals, including sizing and cationic starches. The improved ...
A Retention agent is added to bind fillers to the paper. Fillers, such as calcium carbonate, usually have a weak surface charge. The retention agent is a polymer with high cationic, positively charged groups. An additional feature of a retention agent is to accelerate the dewatering in the wire section of the paper machine.
the retention of the AKD particles on the wet paper mass on the paper screen; the spreading of the AKD particles on the surface and the penetration in the paper mass; the chemical reaction of the hydroxyl groups of the cellulose (esterification) with the alkylated ketene dimers to form beta-ketocarboxylic esters.
These are dependent on physical contact between the fibres and can be broken by wetting of the fibres. The residual strength of a wetted paper can be less than 10% of the original strength. [1] Various techniques, such as refining of the pulp and wet pressing on the paper machine can be used to reduce the strength loss of the paper upon wetting ...
International Paper: Kraft paper mill Woodchips for paper production. The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper.
Enormous challenges are posed by the trend towards recycled materials paper as raw material (the so-called secondary fibers), the rapid increase in the volume of cardboard at the expense of printing paper, the growing speeds (> 120 km/h [15]) and production quantities (maximum daily capacity of a single machine >4,500 tons or >1.5 million tons ...
Paper engineering is a branch of engineering that deals with the usage of physical science (e.g. chemistry and physics) and life sciences (e.g. biology and biochemistry) in conjunction with mathematics as applied to the converting of raw materials into useful paper products and co-products. [1]
Starch is the most common sizing agent. Cationic starch and hydrophilic agents are also applied, including alkenyl succinic anhydride (ASA) and alkyl ketene dimers (AKD). [5] Cationic starch increases strength because it binds to the anionic paper fibers. [6] The amount added is usually between ten and thirty pounds per ton.