How to use PAE wet strength agent
Issuing time:2021-03-27 08:48
The main factors influencing the application effect of PAE wet strength agent are as follows:
1. Electrostatic interaction
The first interaction between PAE wet strength agent and fiber is electrostatic interaction, that is to ensure that the wet strength agent is well adsorbed on the fiber, and then the chemical reaction of cross-linking network is formed in the drying stage, so the electrostatic interaction is the first consideration.
2. Dilution degree
PAE wet strength agent should be diluted to a certain extent before use. If it is too concentrated locally, some fibers will not contact with the wet strength agent, or high charge will appear in some areas, resulting in poor uniformity of paper. The result is uneven distribution of wet strength, and eventually paper products will have various problems.
Generally, the wet strength resin is diluted below 1% to avoid the above problems.
Adding PAE to the slurry can improve the adsorption. Of course, it is not necessary to add PAE to the slurry, depending on the situation.
3. PH value of the system
The pH value of the system is very important for the normal production of wet strength. Only when the pH value is between 5.5-9.0 can the wet strength agent and the fiber be activated to produce wet strength [for the wet strength agent, the amine group that was originally in the proton state is activated, and the epoxy group of PAE based on tertiary amine polyamide is activated (the epoxy group becomes a stable chloro alcohol group by adding acid in the later stage of product production), and the carboxylic group on the fiber also needs to be activated It is easy to complete the reaction in the drying and heating stage only when the carboxylate (COO -) is in the state.
4. Types of pulp
The type of pulp affects the retention of cationic PAE resin. The more carboxyl groups the pulp can absorb, the higher wet strength it can expect.
5. Temperature and residence time
Increasing the residence time of PAE in the batching system is beneficial to improve the retention of wet strength resin and the interaction with fiber, but too long residence time is unfavorable, especially when the system temperature is high. The reason is that the hydrolysis of active functional groups will be intensified, and the migration of resin molecules into the pores of the fiber is not conducive to the generation of wet strength.
6. Anionic substances
Anionic substances may be beneficial or harmful to wet strength. Of course, the negative residues from pulping (including secondary fiber re pulping) and bleaching sections are not good for wet strength, because they are mostly anionic waste, which hinders the retention of wet strength resin. However, the dry strength and wet strength of paper can be significantly improved by using CMC (carboxymethyl cellulose) and other anionic substances reasonably.
The comprehensive influence of moisture content, heating time and temperature of wet paper is complex. For example, two machines producing the same paper may produce different wet strength.
It is very important to predict the actual wet strength of paper by artificial accelerated aging test. Generally, the result of heating at 80 ℃ for 30 minutes can simulate the wet strength of paper produced by natural aging, or the forced ventilation oven can be used to heat at 105 ℃ for 5 minutes. It should be noted that too high temperature or too long heating time in the laboratory will lead to unrealistic high wet strength data, that is, the actual paper machine can not make products with such high wet strength.