We have always said that for products such as surface sizing agents, product quality and product application are equally important. Sometimes we get a suitable and high-quality surface sizing agent, but the effect is not as expected in actual production. For the understanding and research of surface sizing agents, we can’t just focus on surface issues. The following is a summary of the deeper reasons for entanglement that affect the effect of your surface sizing agent.
- The influence of paper substrate
The paper has a large basis weight, and the amount of sizing agent is relatively large.
The greater the tightness, the smaller the amount of sizing agent.
In addition, the capillary structure of the paper and the size of the fiber pores affect the amount of sizing agent on the paper.
Although the sizing agent has a finishing effect on the rough surface of the paper, it is difficult to achieve the ideal finishing effect for the paper with unsatisfactory surface roughness even if the amount of sizing material is increased.
Therefore, the uniformity of the paper sheet is the primary condition for surface sizing.
- The influence of paper sizing degree
The size of the paper sheet sizing is an important factor that affects the amount of sizing press.
The completely unsizing paper absorbs 100% more sizing material than the sizing paper, and the paper web also absorbs more water, resulting in a decrease in strength and an increase in the rate of end breakage.
Once the sizing degree of the paper reaches a certain value, increasing the sizing degree of the paper will have little effect on the absorption of the sizing agent by the paper web.
- 3. The influence of paper moisture
The amount of moisture entering the sizing press sheet not only affects the amount of sizing material picked up by the sheet, but also the uniformity of its longitudinal and transverse moisture directly affects the uniformity of sizing material absorption.
Therefore, the moisture of the paper sheet entering the sizing press is a key parameter that needs to be controlled during the production process.
In the production process, the moisture content is generally controlled at 5~10%, and the maximum pick-up amount can be obtained at this time.
- The influence of paper machine speed
For ordinary sizing presses, as the speed of the paper machine increases, it is beneficial for the sizing material to adhere to the paper sheet.
But after the vehicle speed increased to 650m/min, the amount of starch picked up by the paper sheet did not increase significantly.
For metered sizing press, under the condition that the supply of sizing material has not changed, as the vehicle speed increases, the time of the paper in the nip is reduced, and the adsorption of sizing material on the paper surface is relatively reduced.
- The influence of sizing press
The horizontal sizing press has a higher pickup capacity than the vertical sizing press. The lower nip pressure is beneficial to increase the thickness of the liquid film passing through the nip.
A sizing roller with a larger diameter and lower hardness is beneficial to the absorption time of the paper sheet to the sizing material.
- The influence of sizing compound
Increasing the solid content of the sizing material within a certain range can increase the pickup amount of the paper sheet to the sizing material, and it is also beneficial to reduce the load of post-drying. But increasing the solid content will reduce the rheological properties of the sizing agent.
The viscosity of the sizing agent affects its rheological properties and film transfer volume. A low viscosity is beneficial to increase the pickup volume, and a high viscosity is beneficial to increase the thickness of the liquid film passing through the nip.
Cationic starch sizing agent is different from anionic or non-ionic modified starch sizing such as oxidized starch. Due to its increased chemical affinity for paper fibers, the use of starch agent slows down the penetration speed of the starch sizing agent solution, and more starch remains The surface of the paper sheet.
The above six aspects are the more recognized situations that can be summarized at present. However, different paper types, water quality, and process conditions will have different requirements and influences.
If you have more views, you are welcome to discuss with us.