How to dissolve HPMC?
Hydroxypropyl methylcellulose is also simply called HPMC. This kind of cellulose is a slightly yellowish or white powder object, which is more easily soluble in water. It is mainly a non-ionic cellulose ether made from refined cotton, a natural polymer material, and then through a series of complex chemical processing. Hydroxypropyl methylcellulose is commonly used as an additive for mortar, glue and putty powder. When added to mortar cement, it can be used as water retaining agent and retarder to increase water retention. When added to glue and putty powder, it can be used as adhesive, so as to prolong the operation time and improve the smearability. Let's briefly introduce how to dissolve hydroxypropyl methylcellulose.
Hydroxypropyl methylcellulose can be divided into instant and slow dissolving types. If it is instant hydroxypropyl methylcellulose, it can be dissolved directly and quickly with cold water. The specific method is to select one-fifth to one-third of the required amount of hot water, stir to make the added product completely swell, and then add the remaining part of hot water or cold water, Even ice water can be stirred to a suitable temperature, usually 10 degrees, and can be completely dissolved. For ordinary hydroxypropyl methylcellulose, it can be fully stirred and dispersed with hot water, then added with cold water, stirred and cooled, and then dissolved.
There is also the hot water dissolution method. Because ordinary hydroxypropyl methylcellulose cannot be dissolved in hot water, hydroxypropyl methylcellulose can be evenly dispersed in hot water at the initial stage, and then quickly dissolved when cooled. There are two commonly used methods, as follows: first, put the required amount of hot water in a selected container, The water needs to be heated to about 70 degrees, and then hydroxypropyl methylcellulose is slowly added under gentle stirring. When HPMC begins to float on the surface of the water, a slurry is gradually formed, and then the slurry is cooled under stirring. Second, add one-third to two-thirds of the required amount of water into the selected container, also heat it to about 70 degrees. According to the first method, it is also to disperse hydroxypropyl methylcellulose to prepare hot water slurry, then add the remaining amount of cold water to the previously prepared hot water slurry, stir, and then cool the mixture.
In addition to the above two methods, there are powder mixing method and organic solvent wetting method. The powder mixing method is mainly to mix hydroxypropyl methylcellulose powder with a large number of other powdery substances, and then fully mix it with a mixer. After mixing, add water to dissolve it. At this time, hydroxypropyl methylcellulose can be dissolved without agglomeration. Because there is only a small amount of HPMC powder in each fine corner, it will dissolve immediately when encountering water, This method is often used as putty powder and mortar manufacturers. The organic solvent wetting method is mainly to disperse HPMC into organic solvent, or wet it with organic solvent, and then add cold water, which may dissolve. The organic solvent can be ethylene glycol, ethanol, etc. if caking and wrapping occur during dissolution, it is mainly due to insufficient stirring or ordinary models directly added into cold water, At this time, it should be stirred quickly. If bubbles are generated during dissolution, it can be placed quietly for 2 to 12 hours. The specific time needs to be determined according to the viscosity of the solution. It can also be removed by pressurization or vacuum pumping. At the same time, an appropriate amount of defoamer can be added to eliminate bubbles.