Solubility of Hydroxypropyl Methylcellulose (HPMC)
Because Hydroxypropyl Methylcellulose (HPMC) does not dissolve in hot water, in the initial stage, Hydroxypropyl Methylcellulose can be evenly dispersed in hot water, and then it rapidly dissolves when cooled. Two typical methods are described below.
1). Put the required amount of hot water into the container, and heat to approximately 70 ℃. With slow stirring, gradually add Hydroxypropyl Methylcellulose, and Hydroxypropyl Methylcellulose begins to float on the surface of water, then gradually forms a slurry, and cool the slurry with stirring.
2). Put 1/3 or 2/3 of the required amount of hot water into the container, and heat to approximately 70 ℃. According to method 1), disperse Hydroxypropyl Methylcellulose and then prepare hot water slurry. Then add the remaining amount of cold water to the hot water slurry, and cool the mixture with stirring.
Proper mixture of powders:
Fully mix Hydroxypropyl Methylcellulose powder and a lot of other powdery substances and ingredients with a mixer, and then add water to dissolve. Then at this moment, Hydroxypropyl Methylcellulose can be dissolved without condensation or coagulation, since each subtle little corner, with only a little bit of Hydroxypropyl Methylcellulose powder, can immediately dissolve in contact with water.
Some Problems Regarding Solubility of Hydroxypropyl Methylcellulose
Instant products can quickly disperse in contact with cold water and disappear in the water. The Hydroxypropyl Methylcellulose liquid has no viscosity, because Hydroxypropyl Methylcellulose is only dispersed in the water but not really dissolved. In about 2 minutes, the viscosity of the liquid gradually becomes large, and then a transparent as well as viscous gel will be formed.
Hot-dissolving products may coagulate or condense in contact with cold water, but can quickly disperse and then disappear in hot water. When the temperature drops to a certain temperature (58-65℃ for our products), the viscosity will slowly emerge, until the formation of a transparent viscous gel.
The reason for the coagulation in contact with cold water:
The outer cellulose powder can immediately produce viscosity in contact with cold water, and thicken to form a transparent gel. But the cellulose inside Hydroxypropyl Methylcellulose will be surrounded inside by the gel before contact with water. The solubility of Hydroxypropyl Methylcellulose is still powdery, but will slowly melt away.
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