Application of the most popular cationic dispersed

The application of Cationic Dispersed Rosin Size on coated white paperboard (Part 1)

Abstract: the application experience and experimental steps of Cationic Dispersed Rosin Size on advanced folding coated white paperboard are described

key words: white cardboard; Rosin gum; Sizing effect

our company's 8 # machine mainly produces 250~500g/m2 high-grade folding coated white paperboard and white paperboard, with an annual output of 100000 tons after technical transformation from June to September 2000. In order to ensure and stabilize the product quality, the selected sizing agent in the pulp is mainly traditional and mature cationic dispersion. With the joint cooperation and close cooperation of technicians and technical representatives of papermaking chemicals at home and abroad, some experience and experience have been accumulated in improving and improving the sizing effect, improving the product quality, reducing the sizing cost, and improving the comprehensive benefits of the paper machine. Here is a brief review and introduction

when our company officially produced in April, 1993, hrs-50a lotion rosin produced by a factory in Fuyang, Zhejiang Province was preferred. Its main performance indicators are:

appearance: white emulsion liquid; Solid content: ≥ 50%; Relative bulk density: ≥ 1.06; PH value (10% lotion):4.0~4.5; Anionic type; Cold water is soluble

this product was quite good at that time. Although there were some small technical or packaging problems during its use, it has been used because of the constraints of the planned economy and the lack of market information. By the end of 1995, due to the quality fluctuation of the product, there were many foam in the paper machine, and there were quite a lot of precipitates in summer, which seriously blocked the filtration in front of the metering pump, and the ball beads of the metering pump bonded, resulting in abnormal addition to the system, so that the sizing effect and product quality were fluctuated and affected; In addition, cationic dispersed rosin size, which was successfully researched and developed at home and abroad in the 1980s, has gradually replaced anionic dispersed rosin size, solving the interference problem of anions, cations and impurities in the process of using waste paper for papermaking, and also solving the problem of using rosin for sizing under neutral or near neutral conditions, with less dosage, moderate price and convenient use. Therefore, our company adopted the cationic dispersed rosin gum provided by a foreign-funded company in Shanghai, and then selectively used the same cationic dispersed rosin gum of Suzhou plant a, Tongxiang plant B, and Suzhou plant C in the opinions. The results were quite good, and good economic and social benefits were received. The main performance indexes of this kind of cationic dispersed rosin size series are:

appearance: white lotion; Solid content: (35 ± 1)%; Relative bulk density: 1.05 ± 0.01; PH value: 3.5~4.0; Cationic type; Cold water is soluble

the main characteristics of this kind of products are:

(1) it has a certain positive charge, which can be left on the pulp by itself, and the consumption of alum is small, reducing the pollution to the environment

(2) it can be applied at a wide range of pH values and near neutral (pH 4.5~6.5)

(3) it has strong anti-interference ability to anions, cations and impurities in the size, and is suitable for the size of secondary fibers (recycled waste paper)

(4) the sizing effect is better than that of anionic rosin, and the dosage is less

(5) stable quality, less foam, and no difficulty in sizing in summer

1 sizing mechanism of cationic dispersed rosin size

cationic dispersed rosin size particles have positive charge, zeta potential is about +20mv, which is weak electricity, and can be retained and evenly distributed on the fiber surface of negative charge, but the electrostatic attraction between weak Yang (glue) - weak Yin (fiber) is not enough to achieve good retention of rosin size particles. In order to achieve the ideal sizing degree, a small amount of cationic retention aid needs to be added. At pH 5.5~6.5, the alum hydrolysate in the system exists in the form of polymerized aluminum hydroxide, and its positive electricity disappears, but the adsorption amount of aluminum ions on the fiber surface increases significantly. When the wet paper adsorbed with positively charged rosin particles enters the drying part of the paper machine, the rosin particles are softened at high temperature and react with the aluminum ions on the fiber, and then the rosin particles are positioned to turn the hydrophobic group to the outside of the fiber, The hydrophilic group is firmly combined with the fiber to form a good hydrophobic layer. It can be seen that the main purpose of adding a small amount of aluminum sulfate is to achieve the fixation and positioning of rosin particles in the drying section, rather than retention

2 basic process

3 raw material ratio (taking coated white board as an example)

surface layer: Bleached coniferous wood pulp board, bleached hardwood pulp board

liner: imported newspaper deinking pulp

core layer: imported mixed waste paper, imported corrugated box board waste paper

bottom layer: imported used paper

4 adjustment of sizing sequence and location

our company started with the traditional forward sizing of the front and bottom surfaces of the paper. The results are: large amount of addition, unstable sizing effect, especially the sizing degree of the bottom plate fluctuates severely, there are many foam in the paper machine, and the pulp pool wall and pipe wall are seriously scaled, affecting production and quality. The reason is analyzed as follows: a part of cationic dispersed rosin is consumed on anions, which reduces the sizing material. What are the advantages of the rubber fatigue tester in the slurry replenishment water and what are the operation steps of the equipment? What are the more calcium ions and magnesium ions (the company is located in Hangzhou Bay, the East China Sea, and the water quality is relatively hard) react with rosin to form rosin calcium and rosin magnesium. When alum is added, This prevents the formation of rosin aluminum with lower surface free energy, thereby reducing the sizing effect. After discussing with the technical representatives of a foreign-funded company in Shanghai, the sizing sequence was adjusted to reverse sizing. In addition, the location of sizing was significantly moved forward from the slurry tank to the outlet of the high-level tank (as shown in Figure 2). As a result, the amount of addition was reduced, and the sizing effect was significantly improved, as shown in Table 1

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