Cellulose ethers are classified according to the different products of the etherifying agent used. Hydroxypropyl methyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, benzyl cyanoethyl cellulose Vegetarian, carboxymethyl hydroxyethyl cellulose, etc.
Hydroxypropyl methylcellulose and hydroxyethyl cellulose are more practical.
After etherification, the solubility of cellulose has changed significantly. It can be dissolved in water, dilute acid, dilute alkali or organic solvent. The solubility mainly depends on three factors: (1) The characteristics of the groups introduced in the etherification process, the introduction The larger the group, the lower the solubility, the stronger the polarity of the introduced group, the easier the cellulose ether is to dissolve in water; (2) the degree of substitution and the distribution of etherification groups in macromolecules. Most cellulose ethers can only be dissolved in water under a certain degree of substitution, and the degree of substitution is between 0 and 3; (3) The higher the degree of polymerization of cellulose ether, the less soluble; the higher the degree of polymerization The lower, the wider the degree of substitution that can be dissolved in water. Cellulose ethers have a wide variety and powerful functions, and are widely used in industries such as construction, cement, petroleum, food, textiles, detergents, coatings, medicine, papermaking and electronic components.
Representative examples of cellulose hydroxyalkyl ethers are hydroxyethyl cellulose and hydroxypropyl cellulose. The etherifying agent is an epoxide such as ethylene oxide and propylene oxide. Use acid or alkali as catalyst. Industrial production responds to alkali cellulose and etherifying agents:
The high substitution value of hydroxyethyl cellulose is soluble in both cold water and hot water. Hydroxypropyl cellulose with high substitution value is only soluble in cold water but not hot water. Hydroxyethyl cellulose can be used as a thickener for latex coatings, textile printing and dyeing slurry, papermaking sizing material,
Construction grade latex paint, construction grade real stone paint, adhesive and maintenance colloid, etc. The usefulness of hydroxypropyl cellulose is similar to that of hydroxyethyl cellulose. The low-substitution value of hydroxypropyl cellulose can be used as a construction-grade thickener, which has two functions of adhesion and water retention.