1.Classification:
HPMC can be divided into instant type and hot-melt type. Instant-type products disperse quickly in cold water and disappear into the water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water and has no real dissolution. After about 2 minutes, the viscosity of the liquid gradually increased to form a transparent viscous colloid. Hot-dissolving products, when encountering cold water, can be quickly dispersed in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed. The hot-melt type can only be used in putty powder and mortar. In liquid glue and paint, clumping phenomenon will occur and cannot be used. The instant type has a wider range of applications. It can be used in putty powder and mortar, as well as in liquid glue and paint, without any contraindications.
2.Dissolution method:
Hot water dissolving method: Since HPMC does not dissolve in hot water, HPMC can be uniformly dispersed in hot water at the initial stage, and then rapidly dissolved during cooling. Two typical methods are described as follows: 1), put the required amount in the container hot water and heated to about 70°C. The hydroxypropyl methylcellulose was gradually added with slow stirring, initially the HPMC floated on the surface of the water, and then gradually formed a slurry, which was cooled with stirring. 2), add the required amount of 1/3 or 2/3 of the water in the container, and heat it to 70 ° C, according to the method of 1), disperse HPMC, prepare hot water slurry; then add the remaining amount of cold water to hot water In the slurry, the mixture was cooled after stirring.
Powder mixing method: Mix HPMC powder with a large amount of other powdery substances, mix thoroughly with a mixer, and then add water to dissolve, then HPMC can be dissolved at this time without clumping together, because every tiny little corner has only a little HPMC The powder will dissolve immediately in contact with water. ——This method is used by putty powder and mortar manufacturers. [Hydroxypropyl methylcellulose (HPMC) is used as thickener and water retention agent in putty powder mortar]
Post time: Apr-25-2024