The cellulose ether is a polymer compound having an ether structure made of cellulose.
Each glucosyl group in the cellulose macromolecule contains three hydroxyl groups, a primary hydroxyl group on the sixth carbon atom, a secondary hydroxyl group on the second and third carbon atoms, and a hydrogen in the hydroxyl group is substituted by a hydrocarbon group to form a cellulose ether derivative. Object.
According to the chemical structure classification of the substituents, they can be classified into anionic, cationic and nonionic ethers.
Depending on the etherifying agent used, there are methyl cellulose, carboxymethyl cellulose, ethyl cellulose, benzyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cyanoethyl cellulose, Benzyl cyanoethyl cellulose, carboxymethyl hydroxyethyl cellulose, phenyl cellulose, and the like. Methylcellulose and ethylcellulose are more practical.
The solubility of cellulose after etherification changes significantly, and it can be dissolved in water, dilute acid, dilute alkali or organic solvent. The solubility depends mainly on three factors:
(1) the characteristics of the groups introduced during the etherification process, introduced The larger the group, the lower the solubility, the stronger the polarity of the introduced group, the more soluble the cellulose ether is in water,
(2) the degree of substitution and the distribution of the etherified group in the macromolecule. 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 degree of polymerization of cellulose ether, the higher the degree of polymerization, the more difficult to dissolve; the higher the degree of polymerization Low, the wider the range of substitutions that are soluble in water. Cellulose ethers are widely used in construction, cement, petroleum, food, textile, detergent, paint, pharmaceutical, paper and electronic components industries.
Hydroxypropyl methylcellulose (HPMC) is a nonionic water-soluble cellulose ether polymer, odorless, odorless, non-toxic, white or off-white powder, used in food, medicine, daily chemicals, coatings. , polymerization and construction. With the decrease of the methoxy group content of HPMC, the gel point is increased, the water solubility is decreased, and the surface activity is also decreased.
The main applications in the building are: External wall insulation system: improve water retention, extend open time; improve construction operation performance; improve insulation performance of insulation board. 2. Tile adhesive and grouting agent: increase water retention, extend open time; improve anti-slip performance; improve construction operation and work efficiency. 3. Cement-based plaster and thin layer putty: improve consistency and anti-sag performance; improve water retention, extend open time; improve smoothness of construction operation and improve work efficiency. 4. Interface agent: increase water retention; reduce cracking; improve construction operation and work efficiency. 5. Gypsum-based plaster and putty: improve consistency and anti-sag performance; increase water retention, extend open time; improve the smoothness of construction operation and improve work efficiency. 6. Masonry mortar: improve water retention; reduce water loss to porous substrates; improve construction operation slip and work efficiency. 7. Self-leveling ground mortar: anti-settling and bleeding; improve water retention, reduce shrinkage and cracking; improve operational performance. 8. Crack repairing materials and putty: improve water retention, extend open time; reduce shrinkage and cracking; improve operation and construction. 9. Extrusion molding of cement board: improve water retention; increase lubrication and shape retention; reduce cracking.
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