Application of neutral (alkaline) sizing agent of cationic rosin glue in waste paper pulping and papermaking
my country’s papermaking industry has been adding rosin as a raw material in the papermaking process since a long time ago. Rosin has a high oiliness. Its addition can increase the waterproof and anti-fouling properties of the paper itself, so it has been used to this day. However, during the use of rosin, its adhesion to paper is relatively poor. Therefore, it is necessary to add certain acidic materials to assist it. Once acidic materials are added to paper, the corrosion rate of paper will increase and the durability of paper will be reduced. In order to solve the above problems, all countries are committed to the research and development of neutral rosin sizing technology to ensure that the produced paper is stronger and more durable. This article takes the cationic rosin neutral sizing process in the papermaking process of a factory as an example, hoping that this technology will be promoted on a larger scale.
Tags: process flow; influencing factors; cost advantage; process advantage Cationic rosin neutral sizing technology has been put into use in some papermaking factories in my country. Compared with the traditional papermaking process, this technology has the following advantages: the glue has low acidity and good adhesion; the produced paper has good quality and a certain tension; the production cost is very low; it is highly environmentally friendly and not easy to cause harm to production equipment and personnel. Because this new technology has the above obvious process advantages, it has gradually become the new favorite of many papermaking factories. The following will take the actual production process of a factory as an example to introduce the operation process of this technology in detail.
1 Analysis of the chemical principle of process production
Cationic rosin solution neutral sizing agent is an oily liquid made by reacting rosin as raw material with a high molecular polymer that can react with both rosin and cellulose under alkaline conditions. The solid content of type II is 36% and the pH value is 7-8. Cationic rosin solution neutral sizing agent is very easy to dissolve in cold water and emulsify into a white emulsion in warm water. Since the cationic rosin solution neutral sizing agent can be retained on the fiber surface by electrostatic attraction, its own reaction functional group reacts with cellulose during the paper sheet forming process, so aluminum sulfate is not required as a precipitant. A small amount of aluminum sulfate is added during the sizing process, and its role is only to eliminate the interference of heteroanions in the sizing system. Therefore, excessive aluminum sulfate not only has no effect on sizing, but also hinders the reaction between the sizing agent and cellulose.
2 Introduction to the specific construction process
The raw materials used to make high-strength corrugated paper and 2# kraft paper are all imported waste paper pulp and domestic waste paper pulp. The beating degree after medium-consistency grinding is 30°~32°SR. The process flow is as follows:
↓→neutral sizing agent
waste paper pulp→sizing tank→slurry tank→high-level box→sand remover→
↑a reinforcing agent
pressure screen→pressure former (or mesh slot)
3 Analysis of factors affecting production effect
3.1 The amount of sizing agent added
For the rosin neutral sizing process, the addition of sizing agent should be moderate. According to the results of previous experiments, if the amount of sizing agent added is too low, it will not have a significant sizing effect in the paper production process; and when the amount of sizing agent added is too much, it will cause excessive sizing of the paper, affecting its practicality. Therefore, the amount of sizing agent added should be mastered and controlled within a reasonable range. According to construction experience, the amount of sizing agent added should refer to the amount of traditional acidic sizing agent added, and basically the same amount can meet the production process requirements.
3.2 Acidity and alkalinity control
The properties of the neutral sizing agent added during the production process are not easily affected by the acidity and alkalinity of the solution, so the acidity and alkalinity can fluctuate within an appropriate range.
3.3 Control the amount of aluminum sulfate added
In the rosin neutral sizing process, there is basically no need to add aluminum sulfate raw materials. Under normal circumstances, a small amount of sulfuric acid raw materials is added only to balance the anions in the liquid and ensure the smooth production process. Adding excessive aluminum sulfate will have a counterproductive effect.
3.4 The proportion of sizing agent and reinforcing agent
In the sizing process, an appropriate amount of reinforcing agent can be added to improve the production effect. In this process, the addition ratio of the two should be reasonably adjusted, and sufficient stirring and fusion should be carried out to achieve a more ideal production effect.
3.5 Production process and method
This sizing process is extremely simple to operate, and different sizing methods can be used according to specific production needs.
3.6 Influence of ions in solution
The presence of heteroanions is not conducive to neutral sizing. The raw materials and the washing of raw materials have the greatest impact on the sizing effect. If the slurry with waste paper as the raw material is not washed cleanly, the limit value of the sizing agent for the paper will become larger. Therefore, when a large number of heteroanions exist, in order to achieve the required sizing degree, it is necessary to increase the amount of neutral sizing agent in cationic rosin solution and the amount of anti-interference aluminum sulfate.
3.7 Drying temperature and sizing determination
The drying temperature has little effect on the neutral sizing agent in cationic rosin solution. The paper mill has conducted such an experiment. Two hand-made papers made under the same conditions were placed in an oven at 80℃ and 105℃ for drying and aging for 10 minutes, and the results of the sizing degree were measured. There was little difference. The sizing effect of the cationic rosin solution neutral sizing agent has no hysteresis. The sizing degree of the finished paper can be directly measured by taking the paper sample just off the machine. After several months of trial, no false sizing was found. According to the situation learned from the carton factory, the corrugated paper and boxboard paper with a sizing degree of 0.25-0.75 (scribing method) have good performance.
3.8 Effect of storage time and conditions of cationic rosin solution neutral sizing agent on sizing effect
The sizing effect of the cationic rosin solution neutral sizing agent stored for about a week is the best. Such an experiment has been conducted. A small amount of cationic rosin solution neutral sizing agent was stored at room temperature for more than two months. It was found that the oil would become thicker, but it did not affect the use effect.
4 Cost advantage over traditional papermaking process
Comparison of the cost of high-strength corrugated paper produced with waste paper as raw material
5 Summary of technical advantages of this papermaking sizing process
5.1 Low cost of papermaking production. In the process of using the rosin neutral sizing process, the amount of acid ion raw materials added can be greatly reduced. Moreover, since this construction process itself has extremely high adhesion, the amount of adhesive used is also reduced, which has obvious production cost advantages.
5.2 The construction process is simple and easy to operate. Although this technology is a relatively new production technology, there is no need to make too many changes in terms of construction equipment and construction procedures. On the contrary, this process also saves some production processes, improves the convenience of production operations, and reduces the workload of operators.
5.3 The production process is relatively easy to control. During the production process, the operator can adjust the amount of glue used in time according to the specific production situation to avoid excessive or insufficient use of glue.
5.4 The output is greatly increased. Adding rosin neutral glue during the production process can improve the smoothness of the paper and reduce the probability of paper sticking to the equipment, thereby improving production efficiency, reducing the difficulty of production personnel, and creating more economic benefits in the same time.
5.5 Reduced the degree of damage to production equipment. Traditional acidic papermaking process will corrode production equipment and reduce the service life of equipment, while the use of rosin neutral sizing process can avoid this production defect. In addition, this process can also produce less production pollution wastewater, which is environmentally friendly.
5.6 Improved paper quality. Adding an appropriate amount of rosin neutral sizing agent in the production process can significantly improve the quality of paper. The paper not only has beautiful appearance and reduced roughness, but also strengthens its toughness, making it more durable and more conducive to long-term preservation.
