Waste paper deinking agent and deinking process

The key to using waste paper is to solve the problem of deinking waste paper. The process of deinking waste paper is a combination of chemical and physical processes. The method is: using an efficient deinking agent to separate the ink, impurities and pulp through a deinking device to obtain a regenerated pulp. The methods of deinking include: washing method, flotation method, ultrasonic deinking method, and biological deinking method. The latter two methods are new deinking techniques and have not yet been promoted.

At present, more applications are washing methods and flotation methods, and foreign countries mainly adopt flotation methods. In China, more methods are used for washing or combination of flotation and washing. The most critical is the deinking agent. The specific process is as follows: :

With regard to these two processes, the flotation method has the advantages of low fiber loss, high pulp yield of up to 85% to 95%, small use of deinking, and easy treatment of waste water, but the equipment is expensive and the process requirements are strict. The washing method is easy to operate and the equipment is simple. Therefore, many small and medium-sized paper mills in China use this method. However, its water consumption and power consumption are very high, resulting in low slurry rate and serious water pollution. Therefore, many large paper companies have introduced foreign flotation equipment. The composition of the deinking agent is shown in Table 1.

Table 1 The basic composition, function and dosage of deinking agent

From the above table, it can be seen that the main component of the deinking agent is the surfactant, which is also the key to the study. According to relevant data, at present, Japan mostly uses fatty acids, fatty acid derivatives, higher alcohols, and block polymerization with ethylene oxide, propylene oxide or butylene oxide, and is mostly one-component. In the United States, non-ionic and anionic surfactants are often compounded together. In the deinking technology, all countries are promoting neutral deinking, which can reduce the consumption of chemicals, and is beneficial to control, water filtration, pulp strength, bleaching rate and screening rate.

At present, there are many research institutes for domestic deinking agents and there are more manufacturers, but they are composed of some common surfactants and mostly anionic surfactants. The grades are low, the amount is large, and the effect is high. Poor, especially unable to adapt to the requirements of flotation. Most of the deinking agents used in large-scale flotation and deinking production lines imported from China are still imported. Therefore, the development of high-grade flotation deinking agents such as off-grade color printing paper, color coated paper, and office paper is our future research direction. According to the relevant tests we conducted, it was proved that non-ionic surfactants consisting mainly of ethylene oxide and propylene oxide block copolymers of higher alcohols and greases

The ink effect was quite good. Comparative experiments conducted by the Nanjing Forestry University showed that the deinking agent developed by our institute was close to the imported product.