Preparation and strengthening properties of the ho

2022-09-19
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Preparation of guar gum with low viscosity and its reinforcing properties

although guar gum is one of the natural macromolecular compounds with the best water solubility known at present, it has some disadvantages, such as slow dissolution rate, high content of water insoluble substances, and difficult to control viscosity. 8 Multi language random switching: Simplified Chinese, traditional Chinese, English, which makes it difficult to meet the requirements of industrial applications, so it needs to be modified, such as esterification, etherification, etc., to expand its application range. The usual method is to derivatize its functional groups. There are many derivatization methods, which can be divided into etherification, oxidation, and esterification of guar gum according to the way in which the substituent forms a bond with guar gum; According to the different kinds of substituents with excellent weather resistance and certain scratch resistance, they can be divided into: non-ionic, cationic, anionic, amphoteric, hydroxyalkyl anionic, and hydroxyalkyl cationic guar gum

modified guar gum can be used as sizing agent and has the functions of retention, drainage and reinforcement. However, due to its high viscosity, guar gum is not conducive to surface coating, so its application in surface sizing, coating and other fields is less. In this experiment, hydroxypropyl guar gum is oxidized and degraded, and hydrogen peroxide is used as oxidant to reduce its viscosity in a low-cost, easy to treat and non toxic way, so that it can be used for coating, so as to enhance the filter rod paper

1. Preparation of low viscosity guar gum

spray a certain amount of hydrogen peroxide solution into hydroxypropyl guar gum, stir it evenly, seal it, put it into the oven, and react for a period of time at a specific temperature to get the crude product of low viscosity guar gum. The purified low viscosity guar gum product was obtained by soaking, washing, filtering, drying, crushing and sieving it with a certain concentration of ethanol solution for many times. Prepare it into an aqueous solution with a mass fraction of 1%, and measure its viscosity

2. Coating

prepare the prepared low viscosity guar gum into a solution with a certain mass fraction, and use a scraper to protect the filter rod base paper with a single-sided wooden bridge on the full-automatic coating machine. It takes time and effort to coat at one time. Dry in 105 ℃ oven after coating

3. Effect of reaction conditions on the viscosity and strengthening properties of hydroxypropyl guar gum

3.1 dosage of hydrogen peroxide

it can be seen from table 1 that the greater the dosage of hydrogen peroxide, the greater the degradation degree of guar gum and the lower its viscosity. After being used for coating, the mechanical strength of the paper is enhanced more obviously. Compared with uncoated filter rod paper, the physical properties of the paper were significantly enhanced after the degraded low viscosity hydroxypropyl guar gum was used for paper surface coating

3.2 reaction temperature

it can be seen from table 2 that although the higher the temperature is, the higher the degree of oxidative degradation is, and the lower the viscosity of the guar gum is, the strengthening effect of the guar gum on the paper decreases when the temperature exceeds a certain range

3.3 reaction time

it can be seen from the above experimental data that the longer the reaction time, the greater the degree of degradation of guar gum, the lower the viscosity, and the better the effect after coating. Compared with uncoated base paper, all strength properties have been improved

considering the effects of hydrogen peroxide dosage, reaction temperature and reaction time on the degradation degree of guar gum, and the comparison of the enhancement effect of each sample on the strength performance of paper after surface coating, it can be obtained that the low viscosity hydroxypropyl guar gum prepared under the conditions of peroxide dosage of 8.6%, reaction temperature of 65 ℃ and reaction time of 4H has the best enhancement effect after coating

4 the instrument meets the requirements of gb1633, gb1634 and other standards, and the influence of coating conditions on the reinforcement performance of guar gum

it can be seen from Figure 1 that under the same coating concentration, with the increase of coating temperature, the strength of paper first increases and then decreases. In general, the coating temperature of 50-60 ℃ has a better reinforcement effect

at the same temperature, with the increase of coating concentration, the tensile index also increases first and then decreases. When the coating concentration is 5%, the tensile index is the highest

5. Comparison of low viscosity guar gum and modified starch on the strengthening performance of filter rod paper

it can be seen from table 4 that compared with other products, the low viscosity hydroxypropyl guar gum prepared in this experiment has a better strengthening effect

6. Conclusion

hydroxypropyl guar gum with low viscosity has better strengthening effect than modified starch. The breaking length, bursting index, tearing index and folding resistance of coated paper are 3.4%, 24.8%, 0.53% and 97.87% higher than those of self-made phosphate starch in the laboratory, and 69.35%, 15.31%, 2.03% and 72.22% higher than those of commercially available oxidized starch, respectively

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