Paper grade CMC is based on cellulose as the main raw material, after alkalization and ultra-fine treatment, and then through multiple chemical reactions such as crosslinking, etherification and acidification made of anion polymer with ether bond structure. Its finished product is white or light yellow powder or granular matter. Non-toxic, tasteless, odorless, with good water retention, and excellent shear thinning.
Main Role of CMC Sodium carboxymethyl cellulose in paper industry:
CMC is used to make coated paper coating. Carboxymethyl cellulose can increase the moisture retention value of the coating to prevent the migration of dissolved adhesives in water to the paper, so as to enhance the leveling of the coating and improve the quality of the coating.
Because CMC is quite good adhesive, so the adhesive force is very good, a carboxymethyl cellulose can replace 3-4 modified starch or 2-3 starch derivatives, at the same time can reduce the amount of latex, help to improve the coating solid content.
At the time of coating can play the lubrication effect, strengthen the separation of the film, the film forming ratio is very good, can make the solid continuous film has a good luster, avoid the “orange peel” situation. The chemical properties of sodium carboxymethyl cellulose CMC mentioned pseudoplastic, this property of carboxymethyl cellulose can make the coating has “pseudoplastic”, resulting in thin coating at high shear, especially suitable for high solid content coating or high-speed coating.
Because the aqueous solution of CMC has the resistance to enzymatic hydrolysis and inert metabolism, the coating has good stability, which is manifested in maintaining the homogeneity of the coating, so that the coating is not easy to deteriorate during the storage period. Second, CMC is used as the surface sizing of paper pulp. The surface sizing of paper can increase stiffness, smoothness, and enhance its surface hardness and permeability.
CMC Can effectively control bending and obtain good printing suitability. Adding a certain proportion of CMC to the surface sizing can make the surface achieve good sealing, and the face of printing can improve the clarity of color printing and save ink. CMC aqueous solution has very good film formation, so CMC in the surface sizing agent is conducive to the film formation of the sizing agent on the surface of the paper, so as to improve the surface sizing effect.
However, due to the higher price of CMC, it is generally only used for paper with special requirements (banknote paper, securities paper, decorative paper, release base paper and high-grade double-adhesive paper).
CMC is used in the wet end of paper machine to add, in the past, sodium carboxymethyl cellulose CMC in papermaking industrial is mainly used in coating and surface sizing, pulp with the innovation of science and technology, in recent years the international has a lot of paper manufacturers through the wet end CMC was added to improve the quality of the products and the achievements are also very significant.
Adding CMC to the wet end provides many major benefits:
1.To improve the evenness of paper CMC is a very good dispersant, dissolve become colloidal reagent CMC is added to the treatment of slurry after easily combined with pulp fiber and fill material particles, due to performance electronegative CMC is dissolved in water, it will make itself already have the paper fiber and filler particles of negative charge electronegativity increases, The particles with the same charge will repel each other, and the fiber and filler in the paper suspension will be more evenly distributed, which is more favorable to the forming of the paper industry, and then enhance the uniformity of the paper.
2. Enhance the physical strength of the pulp to improve the uniformity of the pulp helps to increase the physical density of the pulp (such as: appearance density, tear, fracture length, break resistance and folding resistance), CMC in the change of paper uniformity at the same time also increases the physical strength of the pulp. CMC structure contains carboxymethyl can drink hydroxyl on the fiber lead to compound reaction, consolidate the bond force between the fibers, through the physical production of the manufacturing process behind the paper machine, the bond force between the fibers will be greatly increased, the effect of the main body on the paper page is all the increase in physical rigidity.
Paper grade CMC uses:
In the paper industry, CMC is used in the pulping process, which can improve the retention rate and increase wet strength. Used for surface sizing, as a pigment excipient, improve internal adhesion, reduce printing dust, improve printing quality; Used for paper coating, is conducive to the dispersion and fluidity of pigment, enhance paper smoothness, smoothness, optical properties and printing adaptability. In the paper industry as a practical value and a wide range of additives, mainly because of its water-soluble polymer film formation and oil resistance.
● Used for sizing paper, so that paper has high density, good ink permeability resistance, high wax collection and smoothness.
● Can improve the paper internal fiber viscosity state, so as to improve the paper strength and folding resistance.
● In paper and paper coloring process, CMC helps to control the flow of color paste and good ink absorption.
Generally, the recommended dosage is 0.3-1.5%.