The general pH value of gypsum products is acidic or neutral. Now there are two types of construction grade hydroxypropyl methylcellulose on the market: slow-dissolving cellulose and instant cellulose (S). Instant cellulose is not suitable for gypsum systems. Products, the solubility is very poor under acidic or neutral conditions, and slow-dissolving hydroxypropyl methylcellulose can be dissolved in gypsum products, but slow-dissolving cellulose has a significant disadvantage, it is easy to agglomerate (when gypsum After the mortar is stirred on the wall for a short time, small granular spots tend to appear on the surface). At present, in gypsum products, especially in machine-sprayed gypsum mortar, it is required that cellulose ether can be fully dispersed and dissolved in a very short time, which requires us to carry out in-depth research on the slow-dissolving cellulose ether production process. Surface treatment (not the so-called addition of other additives in ordinary grade cellulose ether), so as to adapt to the gypsum mortar system. Hydroxypropyl methylcellulose ether with deep surface treatment can have stable dissolution time and good mechanical properties in gypsum mortar, and can significantly improve the leveling and finishing process of mortar.
Machine-sprayed gypsum mortar generally uses relatively low-viscosity hydroxypropyl methylcellulose ether between 20,000 and 75,000, and the addition amount is generally 0.2% to 0.4%. The setting time of machine-sprayed gypsum mortar is controlled at about 1 hour. We use gypsum mortar yield stress, plastic viscosity, thixotropy, rheology and consistency of slurry to judge the performance of gypsum mortar products.
We consider the quality control of desulfurization gypsum source calcining process, fillers (cement, fine aggregate, heavy calcium powder) and admixtures (can be used in disperse latex powder, hydroxypropyl methyl cellulose ether, expanded perlite, gypsum retarder) The choice of the overall product formula cost-effective.
Hydroxypropyl methyl cellulose ether for gypsum mortar has high purity and good workability, and has been widely praised by gypsum mortar customers.
Post time: Apr-25-2024