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In recent years, with the transformation of the paper industry to neutral paper making, cheap calcium carbonate series fillers are widely used in neutral paper making, and their addition amount reaches 30% to 40% of the total quality of the slurry, or even higher.

Due to the increase of filling amount, the following problems are becoming more and more prominent: poor sizing effect; The tensile strength and surface strength are low, and even cause abnormal production.

These problems have seriously damaged the economic interests of production enterprises and printing units. How to make up for the defects caused by filling has become a problem that many enterprise papermakers pay attention to.

Surface sizing is becoming more and more important and is highly valued by the paper industry.

Surface sizing is an important means to improve the printing performance of paper. Surface sizing can improve the water resistance of paper, improve the physical strength index of paper, effectively improve the phenomenon of hair and powder loss in the printing process, and improve the printing efficiency and printing quality.

Therefore, in order to obtain higher surface strength, printability and form stability of paper pages, surface sizing must be used, and a better surface sizing agent must be selected to improve the quality of paper.

At present, there are many varieties of chemical auxiliaries applied to surface sizing, which can be roughly divided into two categories: natural polymers and synthetic polymers.

Natural polymer products have the advantages of wide source, low price and easy biodegradation, and have always occupied an important proportion in the surface sizing agent market.

The main natural polymer sizing agents used in the production of cultural paper are starch, guar gum, cellulose and hemicellulose, shellac, gelatin, chitin and alginic acid, among which starch surface sizing agent is the most important.

However, synthetic polymer surface sizing agents have been developed rapidly in recent years because they can give paper more excellent properties. At present, the choice of surface sizing agent is mainly based on the different purpose of surface sizing.

In general, modified starch is mainly used as raw material for reinforcement, and AKD or hydrophobic ester which is chemically combined with fiber is mainly used as sizing agent for hydrophobic.

In order to ensure that the paper has sufficient strength and appropriate sizing degree, the surface sizing is usually done by combining modified starch with synthetic sizing agent.

Boiling method of surface sizing solution

Pump a certain amount of liquid oxidized starch into the stainless steel cooking tank, start the agitator, add water to 1/2 of the tank, stir evenly, slowly aerate and heat to 95~100℃, keep warm for 20 min, then add water to the water level, cool down to 60~70℃, and then add the surface sizing agent (PVA needs to be added when boiling). The concentration of the prepared glue is 5%~7% mass fraction, and after stirring evenly, it is filtered through a 60-mesh filter. The viscosity of the glue is not more than 15mPa·s, and the use temperature is kept at 60~70℃.

The paper with surface sizing agent is obviously better than the sizing solution with oxidized starch alone in terms of strength, surface absorption or other aspects.

In terms of absorbability, starch and modified AKD surface sizing agent can significantly improve the sizing effect, which is 26.87% of that of starch alone, followed by styrene acrylic emulsion, which is 16.42%, and PVA surface sizing agent has little effect on improving the sizing effect, which is only 2.99%.

In terms of strength, PVA was the best choice for both tensile strength and surface strength. Compared with starch alone, the tensile strength increased by 21.27% and the surface strength increased by 41.67%, followed by styrene and chitosan, the tensile strength increased by 17.94% and 14.13%, respectively, and the surface strength increased by 33.33%. AKD class has a relatively poor strength improvement.

Considering that PVA is relatively expensive compared with other surface sizing agents, and it is easy to appear the phenomenon of rubber crust when used improperly, and other types of reinforcing agents can meet the production needs and use easily; Considering the cost and the effect of use, it is more appropriate to use styrene C type surface sizing agent in the production of offset paper, both the strength and sizing effect show relatively excellent performance.

Ludao surface sizing agent

No matter what type of surface sizing agent is used in production, it should be reasonable to choose according to the quality requirements of the paper and the production conditions of the paper machine.

The effect of the surface sizing agent should be multifaceted, at present, most people's thinking is that the water resistance is not good to choose the sizing type, the strength is not good to choose the enhanced type, and the production is more passive.

Therefore, the surface sizing agent with excellent bonding properties and excellent water resistance is the best choice in production.

In the production process, how to give full play to the effect of sizing agent is more important, which requires each paper worker to have a deeper understanding and research of the entire process of surface sizing, and expect more and better surface sizing agents to be applied in the paper industry.

Shandong Ludao Energy Technology Co., LTD. - Paper chemical solution supplier

Email: info@sdludao.com

Website: www.sdludao.com