Analysis of Influencing Factors on Deinking of Waste Paper Storage

With the increasing awareness of environmental protection and the increasingly acute shortage of resources, people are constantly developing new materials for papermaking. At the same time, they are increasingly recognizing the importance and superiority of waste paper as a renewable fiber resource for papermaking. Nowadays waste paper is taken off. The increasing use of ink in paper mills has gradually become the main raw material for papermaking.

Waste paper from recycling to production, there are many links in the middle, so that there is a process of storage and placement of waste paper, in the daily production practice, we found that some of the stored paper, deinking effect is often unsatisfactory. In foreign countries, waste paper usually does not exceed the storage period of one month. In China, due to limited conditions, the storage period of waste paper can sometimes reach six months or even longer, and it may be exposed to high temperatures, rain, etc. during storage.

The key to making use of waste paper pulp is deinking. The carbon black, pigment and some filler particles in the ink are linked to the paper by printing. In the deinking process of waste paper, these ink particles, ie, binders and pigments are to be used. The formed fine particles are peeled from the surface of the fiber, and the dispersed ink particles are no longer agglomerated by the action of the dispersant and the adsorbent, and are no longer adsorbed on the fibers and removed. Therefore, the binder in the ink has a great influence on the deinking effect of waste paper. It is related to whether the ink can be separated from the fiber. Only the debonding effect is good, and in combination with flotation or washing, high quality deinking can be achieved. Pulp.

The oxidative polymerization resin components such as linseed oil, modified phenolic resin, and alkyd resin contained in the ink in the linking material will undergo oxidative polymerization and cross-linking to form a strong ink during storage of the waste paper due to the influence of the environment. Membrane, which has a detrimental effect on the deinking of waste paper. The following will discuss the impact of time, high temperature, rain and other factors on the deinking of waste paper. The test adopts the flotation method.

With the extension of time, the effect of deinking became worse, and when one year's worth of paper was saved, the whiteness increase value after deinking could only reach half of the three months of preservation. From this result, it can be seen that the long storage period of waste paper is not conducive to the deinking of waste paper. Newsprint waste paper is not easily deinked when it is stored for more than half a year.

The effect of rain storage on deinking

After the acquisition of waste paper, it will be used for production and use by the investigators. There will be a storage time in the middle, and the waste paper may be exposed to the sun and rain in the open space. The de-inking test will be performed on the degraded waste paper. The storage period of the two waste papers used in the experiment is also three months. One of the samples is stored on the outdoor rainy day for one month. The experimental results show that it has been stored in rainwater. The value of the whiteness of the waste paper after deinking is significantly lower than that of the waste paper stored in the room. This means that the humidity of the waste paper will have a detrimental effect on the deinking effect of the waste paper. The higher the more it is not conducive to the deinking of the rear waste paper.

Effect of high temperature storage on the deinking effect of waste paper

The previously discussed storage time and the effect of open storage on outdoor rainy days had a deinking effect. The waste paper placed at a high temperature has a great influence on the deinking effect. Take some of the waste paper that was taken back at the same time and put it in an oven at about 60°C for 12 hours. Take it out for deinking test. Compare it with the blank sample. After the waste paper with high temperature treatment, the difficulty of deinking will increase. After the whiteness decreased significantly. This shows from another side that when the waste paper is stored, if the temperature is too high, it will also affect the deinking effect, resulting in a drop in the quality of the deinked pulp.

The ink particles to be removed by waste paper deinking are fine particles formed by linking materials and pigments, so the binder in the ink has the greatest influence on the deinking of waste paper. The linking material is generally composed of some dry vegetable oils and resins. During the storage process, the linking materials in the waste paper will undergo oxidative polymerization and cross-linking, and become a solid body structure, so that their alkali resistance is greatly enhanced and is not conducive to saponification. Or emulsification, causing great trouble for the deinking of waste paper.

In the process of storage, waste paper is in contact with air. As the time goes by or the temperature and humidity during storage are too high, the unsaturated bonds in the linking material will cross-link and the film will solidify, making it difficult to remove the ink. Reduce the quality of deinked pulp to different extents. The above experiment also illustrates this point. In order to improve the quality of the deinked pulp and make the secondary fibers meet our quality requirements, we should try our best to shorten the storage time of waste paper, especially in the hot summer weather, and the storage time should be shortened. At the same time, try to avoid being wetted by rain during storage to reduce the difficulty of de-inking due to storage and reduce the quality of deinked pulp.


Source: Zhiqiao Paper Net