OBTAINING PAPER SAMPLES USING BASALT FIBERS AND STUDYING THE EFFECT OF NATURAL GLUE OBTAINED FROM CHITOSAN ON PAPER QUALITY

ABSTRACT

In this study, chitosan is used as a substitute for fillers in paper processing and also as an adhesive to improve paper properties. Experiments were carried out to study the use of 1% low molecular weight chitosan to reduce the water-absorbing properties of paper and increase its strength and smoothness.

АННОТАЦИЯ

В данном исследовании хитозан используется для замены наполнителей при обработке бумаги, а также в качестве клея для улучшения свойств бумаги. Были проведены эксперименты для изучения использования 1% низкомолекулярного хитозана для снижения водопоглощающих свойств бумаги и повышения ее прочности и гладкости.

Keywords: Chitosan, paper, cellulose, water absorption, strength, smoothness.

Ключевые слова: Хитозан, бумага, целлюлоза, водопоглощение, прочность, гладкость.

Introduction. Chitosan is a natural polymer derived from the hard shells of aquatic organisms that belong to the crustaceans. Today, in European countries, chitosan is obtained from sea creatures, i.e., crustaceans. In Uzbekistan, chitosan is obtained by several leading scientists from the Bombix snake mulberry silkworm and Apis Mellifera. The chemical structure of chitosan is similar to that of cellulose, where the hydroxyl (OH) in the glucose molecule in the cellulose is replaced by the amine (-NH_2.) in the chitosan. Due to its chemical structure and properties, chitosan can be used as a filler and adhesive, and it has a number of benefits such as increasing paper strength, reducing water absorption, increasing smoothness, and possibly fighting bacteria and mold.

The use of chitosan in paper production can reduce the harmful effects on the environment because chitosan is a natural polymer that decomposes. In this study, chitosan is used to replace the filler in paper processing, as well as an adhesive to enhance the properties of the paper. The experiment was conducted using 1% low molecular weight chitosan to solve the problem of reducing the water absorption property of the paper and increasing the strength and smoothness of the paper. Paper and cardboard are wrapping materials that are very easy to tear; because they are made from cellulose fibers, which are considered renewable materials. However, paper and paper products should consider the use of environmentally friendly materials. Wrapping papers are used for food packaging, they are required to have the required strength, water, and oil resistance. Paper has a few disadvantages with some positive properties in relation to moisture and oil. This is because the surface of the paper is treated with hydrophobic reagents such as paraffin and polyethylene to increase its resistance to moisture, oxygen, odour, and oil. This limits the use of the finished product. We know that paper is a bundle of cellulose fibers, and the fibers take up space to form masses in hydrogen bonds, but this bond is weakened by a large number of water molecules that compete with the hydrogen bond in the fibers. In maintaining this strength, the use of chitosan, which has a unique molecular structure containing both hydroxyl and amine groups at the same time, can overcome the above-mentioned shortcomings [1-5].

The fibers in the paper are bound by hydrogen bonds, and this bond affects the distance between the fibers. The presence of more water can reduce the strength of the paper. To date, several resins and polymers such as urea, phenol, melamine, and formaldehyde have been used to increase paper strength. Today, a number of scientists are conducting research on the use of biodegradable and non-toxic substances. We also used chitosan and starch as natural adhesives in obtaining packaging papers used for the food industry based on annual plant cellulose as a continuation of this research. Our goal was to replace the starch glue, which is still widely used in paper mills, with chitosan [6, 7].

Research objects and methods. Thick paper obtained from an annual plant (cotton) at 100 g/m² for use in this study. Basalt fiber, which is an inorganic fiber (25%, 35%, 45%). Starch and chitosan for gluing purposes. Three chitosan samples with different deacetylation levels (DD) were 75%, 85%, and 95% (as provided by the manufacturer). Analytical and highly pure chemicals were used to conduct the research.

Results and its discussion. The experiments initially began with paperwork. The paper used cellulose from annual cotton, basalt fiber from inorganic fiber, and starch and chitosan for gluing. During the experiment, 10 paper samples were taken. Given that we recommend the samples obtained from the study mainly to the food industry and the furniture industry, several requirements are placed on the papers to be obtained. These are: break length, number of bends, adhesion, and water absorption. Taking these requirements into account, the samples taken were examined and the following results were obtained.

Figure 1. The effect of the amount of glue on the tear length of the paper

As can be seen from the figure 1, the increase in the number of adhesives causes the break length to increase. The types of adhesives vary. The break length of a paper sample prepared with the addition of chitosan shows a higher result than a paper sample prepared with the addition of starch. Summing up the picture, it can be said that the use of 1% glue is the optimal choice. The use of chitosan showed a positive result in the dry strength of the paper, especially in the use of a 1% solution of chitosan with a low molecular weight. But the increase in concentration reduced its dry power. They found that low-molecular-weight local chitosan was more effective than medium-molecular-weight chitosan in all cases where chitosan was used in the paper production process.

Figure 2. The effect of the amount of glue on the number of folds of the paper

From the results of the analysis (Figure 2), it can be concluded that the increase in the number of adhesives leads to an increase in the length of the break. Exactly the number of folds of the paper sample prepared with the addition of chitosan shows a higher result than the paper sample prepared with the addition of starch. An increase in the amount of glue causes the resulting paper samples to become brittle and, in turn, a sharp increase in the refractive index of the paper. This in turn limits the use of paper. In conclusion, the results are positive at a 1% concentration of chitosan.

Figure 3. The effect of its quantity on the degree of adhesion of the paper

As can be seen from the figure 3, an increase in the amount of adhesives increases the strength of the paper in the wet state, but has a negative effect on the strength of the paper in contrast to the dry state. From a chemical point of view, the localization of hydrogen bonds in the mass structure increases. Summing up the picture, it can be said that it is advisable to use chitosan 1% lysine as an adhesive.

Figure 4. The effect of the amount of fillers on the hardness of the paper

As can be seen from the figure 4, an increase in the composition of chitosan and basalt fibers in the composition leads to an increase in the hardness of the paper, which in turn increases the fragility of the paper. In addition, the high concentration of chitosan (2-4%) also reduces the dry strength of the paper. This can also be explained by the fact that the higher the amount of chitosan in the paper, the higher the fragility of the paper and the lower the elasticity. This is of course unfit to work as a wrapping paper.

Figure 5. Dependence of water adsorption on the amount of fillers

When we analyse the data in the figure, the distance between the connecting fibers should correspond to the distance between the segments, because they form a field of interconnection between each other. Even if the water molecule is separated or not separated from the organic bond by the fibers, a large amount of water will disrupt the bonding state of the paper. It can be explained that the hydrogen bond on the surface of the fibers is mainly monopolized by the water molecule because the fiber forms a macroscopic liquid bridge. The weakness of this bridge indicates the strength of the wet tension on the paper. However, the water absorption of the composite depends mainly on the cellulose material. This cellulose increases the rate of water uptake by forming a hydrogen bond between the cell wall fiber and the water and the hydroxyl group.

Conclusion

The application of chitosan as a paper adhesive has the following conclusions:

• chitosan was found to be absorbed by almost all cellulose fibers, especially in the low-concentration distribution of various cellulose systems used in industry. As the degree of deacetylation (DD) increases, its absorption increases.

• low molecular weight chitosan 1% concentration produces paper with low water absorption, smooth and high dry strength compared to chitosan 2-4% concentration. Therefore, the molecular weight of chitosan affects the properties of the processed paper.

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