When purchasing HPMC, there is no actual experimental operation, what are the simple methods to judge the quality of HPMC, how to choose high quality HPMC?
By visually judging the quality of HPMC.
(1) Whiteness: The quality of products with good whiteness is relatively good.
Although whiteness does not determine the quality, good quality products are mostly white.
(2) Fineness: The finer the fineness, the better the quality is generally.
HPMC’s fineness is generally 80 mesh and 100 mesh. 120 target products are relatively few
(3) Transmittance: Put (HPMC) in water to form a transparent colloid, and look at its transparency. The better the transmittance, the less insoluble matter.
(4) Specific gravity: The larger the specific gravity, the heavier the weight.
The ratio is large, generally because the content of hydroxypropyl group is high, and the content of hydroxypropyl group is high, the water retention is better.
Use the principle of physical reaction to judge.
Principle: HPMC can be divided into Fast-dissolving and Hot-dissolving types.
- The instant product is rapidly dispersed in cold water and disappears into the water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water, and there is no real dissolution. About 2 minutes, the viscosity of the liquid gradually increased to form a transparent viscous colloid.
- Hot-melting products, in the case of cold water, can quickly disperse in hot water, disappear in hot water, until 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, liquid glue and paint, there will be a phenomenon of clumping, can not be used.
It is available in a wide range of applications, in putty powder and mortar, as well as in liquid glues and coatings. There are no contraindications.