Yuan Lei's Little Knowledge | Calcium Carbonate Commonly Used in Paper Industry and Its Functional Characteristics
The paper industry is one of the largest markets for calcium carbonate. As an important papermaking filler and coating pigment, calcium carbonate has rich sources and low price. Fine particles and high whiteness can significantly improve the opacity of paper. The ink absorption speed is fast and can increase the ink absorption of paper. It can make the paper soft, compact and high gloss. It has little influence on the physical strength of the paper.
At present, the types of calcium carbonate commonly used in the paper industry mainly include heavy calcium carbonate, light calcium carbonate, nano calcium carbonate, mixed calcium carbonate, modified calcium carbonate, calcium carbonate whisker, slurry calcium carbonate, etc.
01 heavy calcium carbonate
Heavy calcium carbonate as a paper filler, the addition of a higher amount of paper, the paper strength and sizing effect is less affected, with better paper copying performance. The disadvantage is that the whiteness of the paper, opacity is slightly poor, need to add dispersant.
Heavy calcium carbonate is mainly used as a filler in printing paper, writing paper, office paper and advertising paper except cigarette paper, filter paper and special low quantitative information paper.
02 light calcium carbonate
Light calcium carbonate as a paper filler, can make the paper opacity high, low wear on the paper machine, and do not need to add dispersant. The disadvantage is that the specific surface area is large, which is detrimental to the sizing effect; the water retention is strong, which is not conducive to the increase of the speed of the paper machine.
03 nano calcium carbonate
After adding nano calcium carbonate filler in the papermaking process, the paper has the following characteristics: it can slow down the aging of the paper, so that the paper can be stored for a longer time; so that the paper can absorb a certain amount of ultraviolet light; so that the paper is not easy to yellow and not easy to hair brittle, and has good isolation properties.
Nano calcium carbonate is used as a coating pigment for papermaking, which is beneficial to improve the gloss, whiteness and hue of coated paper; it can ensure the purity of white pigment color; it is beneficial to improve the optical properties of paper such as opacity, gloss and printing gloss; it can change the rheological properties of coating preparation liquid; it can realize the functionalization of coating processing paper, such as insulation, conductivity, antibacterial properties, etc.
Nano calcium carbonate as a papermaking filler, generally used in the production of special paper products, such as diapers, sanitary napkins, color jet printing paper, paper towels and breathable film.
04 mixed calcium carbonate
When mixed calcium carbonate is used as a filler for printing paper, the paper has the characteristics of high brightness, good surface smoothness, high volume, high rigidity and high tensile strength. When a higher wet press pressure is applied to the paper containing mixed calcium carbonate, a higher dryness can be obtained compared to the paper containing GCC, thereby significantly reducing the drying energy, reducing the greenhouse gas, and saving the production cost of the paper mill. Mixed calcium carbonate is more stable than pre-condensed GCC(pGCC) under turbulent conditions in water. Since HCC can make paper with high volume, high stiffness, high tensile strength without losing smoothness, HCC is expected to be applied to develop high loading printing paper.
05 modified calcium carbonate
The surface modification of calcium carbonate can endow calcium carbonate with excellent physical and chemical properties. For example, chitosan was used for organic coating modification of precipitated calcium carbonate (PCC) by alkali precipitation method. After modification, the water filtration performance of the filling slurry was slightly improved, the solubility was also changed, and the tensile index of the filling paper was significantly improved.
06 Calcium Carbonate Whiskers
Compared with nano-calcium carbonate, calcium carbonate whiskers are less likely to agglomerate, and can play a more effective role in toughening and strengthening. Calcium carbonate whiskers have special columnar orientation, high whiteness and filling, and are arranged in parallel and closely on the surface of the base paper when used as a filler for papermaking. Therefore, it enables the paper to have a more excellent quality index as compared with the use of particulate calcium carbonate.
07 slurry calcium carbonate
The use of slurried calcium carbonate has a more powerful advantage than solid calcium. On the one hand, the slurry calcium has not undergone a drying process, that is, without mechanical friction and collision, and fully retains the naturally formed crystal form, and the shape and size are more consistent. On the other hand, the slurry calcium did not undergo mechanical friction and collision, the crystal debris was less, and the crystal end retained the original blunt tip state, and there was almost no damage. The price is cheap, and the filler retention rate of slurry calcium is nearly 3% higher than that of powder calcium, which reduces the cost of raw materials. Cigarette paper enterprises generally choose local slurry calcium suppliers, and the mode of transportation is tank car or pipeline, which is very convenient.
Calcium carbonate, paper, filler, pulp-like, papermaking, nano, with, properties, modification
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