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Method for preparing hydroxypropyl cellulose

A technology of hydroxypropyl cellulose and cellulose, which is applied in the field of preparation of hydroxypropyl cellulose, can solve problems such as unfavorable environmental protection, and achieve the effects of low price, low reaction temperature, and simple synthesis method

Inactive Publication Date: 2004-03-17
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, industrial production of hydroxypropyl cellulose mainly utilizes alkali cellulose pulp to carry out heterogeneous reaction in two steps [E.D.Klug, US Patent 3131176, (1964), US Patent 3278521, (1966); R.G.Bishop, US Patent 3351583, (1967 ); S.Orii, Y.Sasagawa, A.Ito, M.Hiromi, Y.Sakai, US Patent 4292426, (1981)], need to add a large amount of organic solvents such as hexane, heptane, benzene, toluene in the reaction process , propanol, n-butanol, etc. as diluents, which is not conducive to environmental protection

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～5

[0012] Disperse 2 to 4 grams of cellulose powder (CF-11, with a degree of polymerization of about 220, Whatman, UK) in 98 grams of 6wt% NaOH / 4wt% urea aqueous solution, stir for 1 to 5 minutes and place in the refrigerator to freeze (- 5~-10°C), and then the frozen solid was thawed at room temperature and stirred to obtain a transparent cellulose solution. Take 50 grams of the above cellulose solution, add metered propylene oxide all at once or in batches, and stir and react in a water bath at -6°C to 60°C for 10 minutes to 80 hours as required, then add acetic acid to neutralize the reaction solution until neutral Stop responding. The solution obtained from the reaction was dialyzed for one week and then freeze-dried or vacuum-dried to obtain pure hydroxypropyl cellulose in the form of white powder. The reaction conditions and yields of Examples 1-5 are listed in Attached Table 1, and the products obtained are marked as HPC-1, HPC-2, HPC-3, HPC-4 and HPC-5. The molar substi...

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Abstract

The preparation process of hydroxypropyl cellulose includes adding epoxypropane into homogeneous water solution of cellulose, NaOH and urea to react at the temperature from -6 deg.c to 60 deg.c for 10 min to 80 hr; adding acetic acid to neutralize the reacted solution; repeated depositing with acetone and dissolving with water to obtain precipitate; vacuum drying or dialysis for one week before freeze drying to obtain high purity and high homogeneity hydroxypropyl cellulose or hydroxypropyl cellulose gel. The process has non-toxic solvent used, no pollution, convenient operation, mild reaction condition, fast speed, high yield and no organic solvent used as dilutent, and the product has high product purity, homogeneously distributed substituted groups on cellulose glucose unit and basically undegraded cellulose. The present invention provides one new way of preparing hydroxypropyl cellulose in water solution system and with low cost and no pollution.

Description

technical field [0001] The invention relates to a preparation method of hydroxypropyl cellulose, in particular to a method for preparing hydroxypropyl cellulose by carrying out hydroxypropylation reaction in a sodium hydroxide / urea aqueous solution system of cellulose. Background technique [0002] Cellulose is the most abundant renewable resource on earth, and due to its unique reaction function and molecular characteristics such as non-toxic, safe, biodegradable, hydrophilic, chiral and semi-rigid, it will become one of the main chemical raw materials in the future One (J. Schurz, Prog. Polym. Sci., 1999, 24, 481). At present, commercial cellulose derivatives are mainly synthesized by slurry method under heterogeneous conditions, which limits the purity and uniformity of the product. Over the past two decades, many new solvent systems for cellulose have been developed and researched one after another. Among these solvent systems, only a few organic solvent systems are su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B15/00
Inventor 周金平张俐娜邓清海
Owner WUHAN UNIV