Preparation method of low-chlorine refined bleached shellac

Abstract

The invention discloses a preparation method of low-chlorine refined bleached shellac. The preparation method includes: firstly dissolving granular shellac with a sodium carbonate solution to obtain ashellac resin alkali dissolution solution; then carrying out deslagging, temperature adjustment and concentration adjustment sequentially on the shellac resin alkali dissolution solution, and then conducting medium-concentration sodium hypochlorite bleaching to obtain a semi-bleached slurry; then adding assistants into the semi-bleached slurry for adjustment, and then conducting medium-concentration hydrogen peroxide supplementary bleaching by a hydrogen peroxide bleaching solution to obtain a bleached shellac resin solution; carrying out diatomite adsorption filtration on the bleached shellac resin solution, then carrying out acidification precipitation treatment with dilute sulfuric acid or dilute hydrochloric acid with a mass concentration of not higher than 6% to separate out shellacresin; and finally, washing the precipitated shellac resin with water to neutral, then carrying out centrifugal dehydration, crushing and drying, and performing cooling to obtain the low-chlorine refined bleached shellac. The method provided by the invention solves the technical problems of combination of traditional shellac bleaching method with other green bleaching methods, and the prepared low-chlorine refined bleached shellac can meet the preparation requirements of fruit preservatives and even drugs, and is environment-friendly and economical.

Description

technical field [0001] The invention relates to the technical field of shellac preparation, in particular to a method for producing dewaxed, decolorized and bleached shellac by using granular shellac as a raw material. Background technique [0002] Shellac, also known as shellac, is an excellent natural resin and the only animal resin. Due to its stable chemical properties, non-toxic, non-irritating, strong plasticity and film-forming properties, good electrical insulation performance, oil resistance, acid resistance, Waterproof, moisture-proof, UV-resistant, widely used in food, medicine, electrical appliances, coatings, machinery, rubber, plastics, leather, paper, printing, ink and military and other industrial sectors. So far, there is no synthetic resin that fully possesses these properties, and shellac is still an important chemical raw material that cannot be completely replaced by chemical synthetic substances. According to statistics, more than 50% of the lac produc...

AI Technical Summary

Problems solved by technology

[0003] The traditional production of refined bleached shellac uses sodium hypochlorite, which not only produces dioxin and other carcinogens to pollute the environment; and the refined bleached shellac produced not only affects the scope of use of bleached shellac due to its high combined chlorine, but also The application of bleached shellac in fruit preservatives (preservation of apples, citrus and plums, etc.), chocolate packaging and pharmaceuticals also poses a food safety hazard

The existing technology of using granular shellac to produce bleached shellac is mainly to use hypochlorite bleaching of shellac resin alkaline solution to remove red shellac to meet the color quality requirements of bleached shellac, and then supplemented by dechlorination process to remove purple shellac. Combined chlorine on the gum resin, such as the preparation method disclosed by Chinese patent CN101157828A of a low-chlorine bleaching shellac, has a long process flow, high processing cost, and unsatisfactory dechlorination effect

In order to reduce the amount of chlorine introduced in bleached shellac, there are also some manufacturers who try to bleach shellac completely with the method of non-chlorine bleaching, such as the bleaching method of a kind of shellac resin disclosed in Chinese patent CN 105838255A, but due to the The red lacin is difficult to remove, so not only the amount of bleaching agent is large, the production cost is high, but also the bleaching process is cumbersome, the process is complicated, and more equipment is invested, and the quality of the bleached lacin produced is also quite different.

Now bleaching in paper industry, textile industry, etc. has been used O 3 、H 2 o 2 、C 2 h 4 o 3 And some biological bleaching agents such as green bleaching agents such as enzyme preparations replace chlorine-based bleaching agents, but due to the particularity of shellac bleaching, these bleaching agents have not been well combined with the traditional bleaching method of bleaching shellac, and no one has solved shellac. Technical difficulties in combining traditional bleaching methods with other green bleaching methods, so this has always been a blank spot in this technical field