The application of granular sodium carboxymethyl cellulose (CMC) in the field of paper coating mainly relies on its unique physical and chemical properties (such as water solubility, adhesion, film-forming properties and rheological control ability), playing a key role in improving the performance of coated paper and optimizing production processes.
Core application scenarios in paper coating
1.Coating binder (Binder)
Application scenario: Granular CMC is used in pigment coating liquid (such as a mixed system of inorganic pigments such as kaolin and calcium carbonate and latex), as the main or auxiliary binder, which can improve the bonding strength between pigment particles and the surface of base paper.
1.1Mechanism of function:
1.1.1. After granular CMC is dissolved in water, the electrostatic adsorption of carboxyl groups can firmly adhere the pigment particles to the surface of paper through the hydrogen bonding between hydroxyl groups and the surface of pigments, reducing the phenomenon of powdering and hair loss during coating.
1.1.2. When granular CMC is compounded with synthetic latex (such as styrene-acrylic latex), the amount of latex can be reduced, the cost can be optimized, and the flexibility and crack resistance of the coating can be improved.
Typical case: In the pre-coating or top-coating process of coated paper and lightweight coated paper (LWC), granular CMC and latex are matched in proportion to improve the gloss and printability of the coating.
2. Adjust the rheological properties of the coating liquid
2.1Application scenario: Granular CMC can control the viscosity, thixotropy and water retention of the coating liquid, and adapt to the rheological requirements of different coating processes (such as blade coating, roller coating, and air knife coating).
2.2 Mechanism of function:
2.2.1Thickening and pseudoplasticity: CMC forms a high-viscosity colloid after dissolving in water, and maintains a high viscosity at a low shear rate to prevent pigment sedimentation; the viscosity decreases when sheared by the coating machine, which facilitates uniform coating, and the viscosity recovers after the shear force disappears to avoid coating sagging.
2.2.2 Water retention regulation: Through the water absorption effect of the hydroxyl group in CMC, the penetration rate of water in the coating liquid into the base paper is delayed, ensuring that the pigment particles have enough time to arrange evenly before drying, reducing pinholes and cracks in the coating.
Typical case: In high-solid content coating liquid, the slow dissolution characteristics of granular CMC can avoid instantaneous viscosity surge and facilitate production operation.
3. Improve coating surface performance
3.1 Application scenario: Granular CMC can improve the smoothness, glossiness and printing adaptability of coated paper, especially in the field of high-precision printing (such as magazines and advertising paper).
3.2 Mechanism of action:
Granular CMC is soluble in water and forms a dense film during the coating and sizing process. After film formation, it forms a uniform colloidal network to fill the gaps between pigment particles, making the coating surface smoother and reducing ink penetration and dot deformation during printing.
When granular CMC is compounded with other additives such as starch and polyvinyl alcohol (PVA), it can synergistically optimize the water resistance and abrasion resistance of the coating.
Summary：
Our granular Sodium CMC has the same quality as Nouryon's. (Nouryon's type FINNFIX 2, FINNFIX 5, FINNFIX 10 and FINNFIX 300.) The current application of our products in paper coating is developing towards high efficiency and functionalization. Its performance advantages are particularly prominent in the production of high-end coated paper. In the future, it is expected to further expand the application scenarios through molecular structure design and innovation. At present, our products are widely praised by customers.
