What is the difference between hydroxypropyl methylcellulose (HPMC) with or without S?
1. HPMC is divided into instant type and rapid dispersion type
HPMC instant type does not add any letters, such as “100000” is “100000 viscosity fast dispersion type HPMC”.
2. With or without S, the characteristics are different
Rapidly dispersing HPMC disperses rapidly in cold water and disappears into water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water, and there is no real dissolution. After about two minutes, the viscosity of the liquid gradually increases, forming a transparent sticky liquid. Thick colloid.
Instant HPMC can disperse rapidly in hot water at about 70°C. When the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed.
3. With or without S, the purpose is different
Instant HPMC can only be used in putty powder and mortar. In liquid glues, coatings and cleaning supplies, clumping will occur and cannot be used.
Rapidly dispersing HPMC has a wide range of applications. It can be used in putty powder, mortar, liquid glue, paint, and washing products without any contraindications.
Dissolution method
1. Take the required amount of hot water, put it into a container and heat it to above 80°C, and gradually add this product under slow stirring. The cellulose floats on the water at first, but is gradually dispersed to form a uniform slurry. Cool the solution with stirring.
2. Or heat 1/3 or 2/3 of the hot water to above 85°C, add cellulose to obtain a hot water slurry, then add the remaining amount of cold water, keep stirring, and cool the resulting mixture.
3. Cellulose has a relatively fine mesh number, and exists as a single small particle in the uniformly stirred powder, and it dissolves rapidly when it encounters water to form the required viscosity.
4. Add cellulose slowly and evenly at room temperature, and keep stirring during the adding process until a transparent solution is formed.
What factors affect the water retention of hydroxypropyl methylcellulose?
The water retention of hydroxypropyl methylcellulose HPMC product itself is often affected by the following factors:
1. Cellulose ether HPMC homogeneity
The uniformly reacted HPMC has uniform distribution of methoxy and hydroxypropoxy groups and high water retention.
2. Cellulose ether HPMC thermal gel temperature
The higher the thermal gel temperature, the higher the water retention rate; otherwise, the lower the water retention rate.
3. Cellulose ether HPMC viscosity
When the viscosity of HPMC increases, the water retention rate also increases; when the viscosity reaches a certain level, the increase of the water retention rate tends to be gentle.
Cellulose ether HPMC addition amount
The larger the added amount of cellulose ether HPMC, the higher the water retention rate and the better the water retention effect.
In the range of 0.25-0.6%, the water retention rate increases rapidly with the increase of the addition amount; when the addition amount further increases, the increasing trend of the water retention rate becomes slower.