Hydroxypropyl methyl cellulose (hereinafter referred to as HPMC) can be divided into instant type and slow-dissolving type. Instant hydroxypropyl methyl cellulose (HPMC) refers to the use of cross-linking agent to treat its surface in the production process, so that HPMC can be used in cold water. It disperses quickly in the middle of the water, but it is not really dissolved. After uniform stirring, the viscosity slowly rises before it dissolves; Slow-dissolving HPMC can also be called a hot-dissolving product. In hot water, through uniform stirring, when the temperature of the solution drops to a certain temperature (the gel temperature of our company’s products is about 60 ℃), the viscosity will slowly appear until a transparent viscous colloid is formed.
The physical and chemical indicators of instant and slow-dissolving HPMC are the same, but they are different in the scope of application.
application: Slow-dissolving HPMC is mainly used in dry-mixed mortars such as mortar and putty. After uniform dry-mixing, HPMC is separated by other materials. After adding water, viscosity will appear immediately, and it will not form agglomeration; in glue and paint, there will be agglomeration. phenomenon, must be dissolved in hot water or after thorough stirring.
The application range of instant HPMC is wider than that of slow-dissolving HPMC. It can be used in lime-calcium-based putty and cement-based mortar, as well as glue and paint. Under alkaline conditions, instant HPMC quickly reaches the standard viscosity; in gypsum-based In mortar, due to the acidic pH of gypsum, the viscosity of instant HPMC is very slow, and the initial setting of building gypsum is ≥3min, and the final setting is ≤30min, although a certain amount of retarder is added to gypsum-based mortar to delay its setting. However, its operating time is still not as good as cement-based and gypsum-based products, so some alkaline substances must be added to improve the sticking time of HPMC.