Preparation method for cellulose carbamic acid ester

A carbamate and cellulose technology, applied in the production field of cellulose derivatives, can solve the problems of increased cost, interference with the reaction between urea and cellulose, complicated operation procedures, etc., achieves improved solubility and rheology, and is beneficial to The effect of post-spinning and shortened reaction time

Inactive Publication Date: 2012-11-07
TIANJIN POLYTECHNIC UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] First, the use of urea is too large, the cost increases, and the residual excess urea is prone to side reactions such as synthesis of biuret, which interferes with the reaction of urea and cellulose, and also blocks the equipment pipeline
[0012] Second, the intercalation and esterification processes are carried out separately, the reaction time is long, and the production efficiency and product quality stability are low
[0013] Third, the degassing process between the intercalation and esterification process, the operation process is too cumbersome, and more importantly, this process will bring out some urea molecules, which may make the cellulose reaction incomplete
[0014] Fourth, for wood or gramineous stem raw material cellulose pulp, restricted by its pulping process, the content of hemicellulose is generally high, and most of the wood pulp has a high degree of polymerization, so the fluidity of later-stage products can be directly used and poor spinnability

Method used

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  • Preparation method for cellulose carbamic acid ester
  • Preparation method for cellulose carbamic acid ester
  • Preparation method for cellulose carbamic acid ester

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] Cotton pulp with a degree of polymerization of 560 and 10% sodium hydroxide solution was prepared at a bath ratio of 1:3, heated at 60°C for 5 hours, and then taken out and dried at room temperature. Take ethanol at a ratio of 1mol / L and add it to the reactor, weigh appropriate amounts of alkalized cotton pulp and urea at a ratio of 1:3, place them in a stainless steel basket in the reactor, and seal the reactor. Introduce carbon dioxide until the air in the device is exhausted, and close the release valve tightly. Then heat up to the reaction temperature of 140°C, then inject carbon dioxide through the high-pressure pump until the reaction pressure reaches 22Mpa, stop the pump, close the intake valve, and maintain the above reaction conditions for 3 hours to complete the esterification reaction. After the reaction is completed, the carbon dioxide in the reactor is emptied within 3 minutes, and the reactor is opened after the pressure drops to normal pressure, and the r...

Embodiment 2

[0045] Use wood pulp with a degree of polymerization of 850 and 15% sodium hydroxide solution at a bath ratio of 1:4 to prepare, heat at 80°C for 2 hours, and then take it out and dry it at room temperature. Take methanol at a ratio of 0.8mol / L and add it to the reactor, weigh an appropriate amount of alkalized wood pulp and urea at a ratio of 1:5, place them in a stainless steel basket, and seal the reactor. Introduce carbon dioxide until the air in the device is exhausted, and close the release valve tightly. Then heat up to the reaction temperature of 150°C, then inject carbon dioxide through the high-pressure pump until the reaction pressure reaches 25Mpa, stop the pump, close the intake valve, and maintain the above reaction conditions for 6 hours to complete the esterification reaction. After the reaction is completed, empty the carbon dioxide in the reactor within 3 minutes, open the reactor after the pressure drops to normal pressure, take out the raw materials, wash a...

Embodiment 3

[0047]Bamboo pulp with a degree of polymerization of 950 and 18% sodium hydroxide solution was prepared at a bath ratio of 1:5, heated at 50°C for 8 hours, and then taken out and dried at room temperature. Take n-butyraldehyde at a ratio of 1.2 mol / L and add it to the reactor, weigh an appropriate amount of alkalized bamboo pulp and urea at a ratio of 1:6, place them in a stainless steel basket in the reactor, and seal the reactor. Introduce carbon dioxide until the air in the device is exhausted, and close the release valve tightly. Then heat up to the reaction temperature of 155°C, then inject carbon dioxide through the high-pressure pump until the reaction pressure reaches 30Mpa, stop the pump, close the intake valve, and maintain the above reaction conditions for 4 hours to complete the esterification reaction. After the reaction is completed, the carbon dioxide in the reactor is emptied within 3 minutes, and the reactor is opened after the pressure drops to normal pressur...

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Abstract

A preparation method for cellulose carbamic acid ester is characterized in that cellulose pulp is added to alkali liquor of set concentration according to certain bath ratio to be processed to obtain alkali cellulose; and the alkali cellulose and urea are used as raw materials, supercritical carbon dioxide flow is used as a carrier, under the assistance of a cosolvent, and supercritical CO2 dissolves the urea and carries the urea to enter positions among alkali cellulose molecules to finish activation of alkali cellulose molecules and embedding of the urea. Simultaneously, by controlling the temperature and pressure of a reaction kettle, the alkali cellulose and the urea embedded among the alkali cellulose undergo esterification to obtain cellulose carbamic acid ester. The method combines two stages of embedding and esterification and simplifies operation and improves production efficiency, and synthesized cellulose carbamic acid ester is stable and controllable in quality. Simultaneously, by alkalization processing the cellulose pulp, obtained products have better flowability and spinnability and are applied to cellulose raw materials with various different polymerization degrees.

Description

technical field [0001] The invention relates to the production technology of cellulose derivatives, in particular to the preparation method of cellulose carbamate. Background technique [0002] Cellulose carbamate (abbreviated as CC) is a nitrogen-containing derivative of cellulose, which has the most potential to replace cellulose xanthate for the production of cellulose fibers. Patents Finnish Patent: 61033, 62318; U.S. Patents: 4567255, 4530999, 4639514 and Chinese patent CN200510070551.6 provide a method for preparing cellulose fibers using cellulose carbamate (Cellulose Carbamate; CC) as an intermediate. However, this method has complex process, high cost, and needs to use toluene, xylene, etc., and there are problems such as environmental pollution. The patent 200510030727.5 of Yin Cuiyu, Shen Xinyuan, etc. provides a method for preparing cellulose carbamate by supercritical carbon dioxide method. Insert between cellulose molecules to activate the cellulose; then red...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/06D01F2/24
CPCY02P20/54
Inventor 尹翠玉王乐军张志鸿张宇峰张阳
Owner TIANJIN POLYTECHNIC UNIV
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