CMC Usages in Papermaking Industry

1. Paper Pulp Additives

Apply CMC into the paper pulp (add before pulping and alums mixing). CMC can disperse fiber, improve uniformity and strength of paper (bursting strength and stiffness). Using CMC with the same beating degree can shorten beating time, conserve energy. Dosage of CMC is 0.2%-0.8% of paper pulp. Can use CMC RM8-1. With the add of CMC, paper tension increases 40%-50%, tearing strength raises 50%, flexibility increased 4-5 times. Meanwhile, paper quality is of smoothness with good ink absorbency and clear printing edge. It's much better to use hard water during production.

2. Surface Sizing Agent

Sound surface strength is required during high-speed printing. When there is a low beating degree or high filling content, usually adopt a surface sizing method to increase the surface strength of paper and paperboard, reduce surface absorption. Through surface sizing, fiber holes of paper are sealed by a layer of sizing film. It can reduce the absorption of moisture in the air, as well as evaporation of moisture in the paper. Prevent paper from rolling up and crushing. Improve the paper absorption of ink and oil. Has the effect of grease-proof, waterproof and oil-resistant.

To avoid paper and paperboard surface lint and powder falling, can use CMC solution with low viscosity and medium viscosity. With medium viscosity, CMC solution can get a layer of compact grease-proof film. Usually, use CMC solution with 1%-2% concentration can get 0.1g/m2--0.5g/m2 sizing. Users can also decide CMC viscosity according to the different base paper. It can mix low and medium viscosity CMC. High purity CMC has a good property of paper film-forming. Instead, Industrial grade CMC with low purity has poor performance on paper film-forming. Dosage of CMC is 1/2-1/3 comparing with that of starch. Especially that modern paper-making factories conduct sizing with the high-speed machine, which can only apply CMC solution with lower viscosity and high purity.

3. Coating Agent

Coating whiteboard paper and chrome paper usually need coating pigment. Use CMC in coating color can improve water retention and rheology effect. CMC is featured by characteristics of good dispersion and binding, with the dosage 0.5%-2.5%. The exact dosage is according to different viscosity and speed of machines.