Preparation method of high-molecular-weight cellulose acetate butyrate

Abstract

The invention discloses a preparation method of high-molecular-weight cellulose acetate butyrate, which comprises the steps of 1) conducting activation, specifically, soaking cellulose powder in acetic acid to obtain activated cellulose powder; 2) conducting esterification, specifically, enabling the activated cellulose powder to react with acetic anhydride and butyric anhydride under the condition of an acid catalyst to obtain an esterification reaction solution; 3) conducting neutralization, specifically, adding a neutralizer into the esterification reaction liquid to neutralize the acid catalyst into salt; and 4) conducting reduction, specifically, adding sodium triacetoxyborohydride into the neutralized esterification reaction solution to partially reduce the ester group into hydroxyl,thereby obtaining the high-molecular-weight cellulose acetate butyrate. The method avoids cellulose acetate butyrate glucose unit breakage and molecular degradation caused by hydrolysis by adding water, and also avoids the problems of difficult separation and high metal content caused by adding a heterogeneous catalyst.

Description

technical field [0001] The invention relates to cellulose acetate butyrate, in particular to a preparation method of high molecular weight cellulose acetate butyrate. Background technique [0002] Cellulose acetate butyrate (abbreviated as CAB) is a kind of cellulose mixed ester, which is mainly used in automobile paint, leather brightener, ink, wood paint, motorcycle paint, plastic, thermosetting powder coating, etc. In the car finish varnish, CAB plays an irreplaceable role. In the car primer, metal flakes such as aluminum powder should be used as pigments, and the metal flakes should be oriented parallel to the substrate; CAB is used in car refinish paint systems. It can shorten the drying time, resist cold cracking, and has good polishing performance. [0003] High molecular weight cellulose acetate butyrate has a high melting point and better alcohol resistance, and the thermoplastic film prepared by using it has higher strength and toughness and better mechanical prop...

AI Technical Summary

Problems solved by technology

Chinese patent CN110642954A adopts the method of hydrogenolysis to remove the acyl group of cellulose acetate butyrate so as to obtain high hydroxyl content cellulose acetate butyrate, but this method needs to use noble metal palladium catalyst, the cost is higher, and high molecular weight cellulose acetate butyrate The viscosity of the reaction solution is high, and the separation and recovery of the solid catalyst is difficult, resulting in high metal content in the cellulose acetate butyrate product, so this method is not suitable for the preparation of high molecular weight cellulose acetate butyrate

[0005] In summary, in the current hydrolysis process of cellulose acetate butyrate, directly adding water or palladium-catalyzed hydrogenation is not conducive to the preparation of high molecular weight cellulose acetate butyrate. Therefore, it is necessary to find a new process to solve the existing problems. Various deficiencies in the technology