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HPMC can be divided into instant type (Surface treated) and hot soluble type (Non-surface treated). 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-soluble type, lumped in cold water, but in hot water, quickly disperse, disappear in hot water, until the temperature drops to a certain temperature, the viscosity slowly appears until a transparent viscous colloid is formed. The reason for lumping in the cold water is that the outer cellulose powder encounters cold water, immediately starts to have a viscosity, thickens into a transparent colloid, and the cellulose inside is not in contact with water, and is surrounded by the colloid, or is powdery, but slowly dissolves. In practical applications, it is not necessary to use hot water to dissolve hot-melt products, because the putty powder or mortar is powder. After dry mixing, the cellulose is separated by other materials. When it meets water, it will immediately become viscosity and will not have lumps. The hot-dissolved type can only be used in putty powder and mortar. In liquid glue and paint, there will be lumped. It is available in a wide range of applications for instant type (Surface treated) , in putty powder and mortar, as well as in liquid glues and coatings. There are no contraindications. However, for instant type (Surface treated), it’s water retention and stability are not comparable to hot soluble type (Non-surface treated). Therefore, we recommend hot soluble type (Non-surface treated) in dry powder such as putty powder and mortar.
Hot soluble type (Non-surface treated) HPMC dissolution methods
If the hot soluble type (Non-surface treated) HPMC is added directly to the water, agglomeration will occur before dissolution. However, dissolving in this way is very slow and difficult. Here we recommend three dissolution methods for end users based on different applications：
1 Hot water dissolution method: Since HPMC is not dissolved in hot water, the initial HPMC can be uniformly dispersed in hot water and then rapidly dissolved upon cooling. Two typical methods as follows:
Adding hot water(85°C) into the container. Hydroxypropyl methylcellulose was gradually added with slow stirring, and the HPMC floated on the surface of the water, and then gradually formed a slurry, and the slurry was cooled with stirring.
Adding 1/3 or 2/3 of the required amount of hot water(85°C) to the vessel , gradually add HPMC to hot water and keep stirring. Cold water or ice water is then added to the hot cement slurry to achieve the desired level. Stirring is continued to cool the mixture.
2 Powder mixing method: Mix the HPMC powder with a large amount of other powdery substances, mix well with a blender, and then add water to dissolve. At this time, HPMC can be dissolved without agglomeration, because each tiny small corner has only a little HPMC. The powder will dissolve immediately upon contact with water. – This method is used by putty powder and mortar manufacturers.
3 Organic solvent humidification dissolution method: HPMC is pre-dispersed or wetted with an organic solvent such as ethanol, ethylene glycol or oil, and then dissolved in water, and HPMC can be easily dissolved.
Instant type (Surface treated) HPMC dissolution methods
Surface treatment powders are specially developed to prevent lumping in wet-mixing applications such as paint and emulsion applications. In order to prepare a solution from the surface-treated powder, the powder is directly placed in cold water. Over time, a fully developed solution of suitable viscosity was prepared by continuously stirring the solution.
Note: In order to dissolve quickly, the instant type (Surface treated) HPMC will dissolve rapidly after adjusting PH value to 8-10 by adding ammonia or alkali water, forming a solution.
NON-SURFACE TREATED HPMC
In short, for different types of products, the correct method can be fully dissolved. If agglomeration occurs during dissolution, it is caused by insufficient agitation or direct addition of ordinary models to cold water. At this time, it should be stirred quickly. In addition, if bubbles are generated during dissolution, it can be left to stand or defoamer added.
1. HPMC solubility in water
HPMC is the same as hypromellose and is a water-soluble cellulose ether. HPMC dissolves in cold water and certain polar organic solvent, such as methanol, ethanol, isopropyl alcohol (IPA), and acetone. HPMC can also be dissolved in water-organic solvents and mixed solvents. But is not soluble in hot water.
2. How do you dissolve HPMC?
HPMC solubility ways include hot water solubility, dry powder mixing method, and organic solvent wetting method.
2.1 HPMC solubility in hot water
Because HPMC is not soluble in hot water, we need to cool the HPMC hot solution to a proper temperature. Only in this way, HPMC can be soluble and play the function of increasing viscosity. There are 3 ways in the following.
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1. Pour the required amount of hot water into the container. Heat it until about 70℃. Then stir it slowly. and add HPMC to it. In the beginning, HPMC powder floated on the water solution surface. Gradually forming a slurry through stirring. Stir until the slurry is cool. If the temperature is down to a proper degree, the HPMC becomes water solubility. The HPMC solution begins to have viscosity.
2. Pour 1/3 or 2/3 of the required amount of hot water into the container. Heat it until about 70℃. Then add HPMC. Then stir it slowly to make HPMC powder evenly disperse and thoroughly wet. hot water slurry is prepared. Then add the remaining amount of cold water to the hot slurry and cool the mixture while stirring. Then continue to stir.
3. Put 1/3 or 2/3 of the required amount of hot water into the container. Heat it to about. 70°C. Then stir it slowly to make HPMC powder evenly disperse and thoroughly wet. hydroxypropyl methylcellulose is dispersed. Hot water slurry is prepared. Then add the remaining amount of cold water or ice water to the container. Add HPMC hot water slurry to the cold water, and stir, At last cool down this solution.
2.2 Dry powder mixing method
There is a mixing process between HPMC molecular and other dry powders in a blender. The suggested ratio of dry powder to HPMC is 3:1 or 7:1. Then when stir, add water. Continue to stir until the mixture has completely hydrated.
At this moment, HPMC will not condense. Because HPMC powder molecular is dispersed in every tiny corner. Every corner has little. Therefore, this mixture can be dissolved immediately when meets water.
Non-surfaced HPMC often applies to wall putty and mortar. And this material usually is powder. So in the construction of dry mortar or wall putty, workers would like to use dry powder mixing method rather than use hot water methods.
2.3 Organic solvent wetting method
using an organic solvent to disperse or wet HPMC. Then add water. At this moment, HPMC is easy to dissolve.
3. HPMC solubility in cold water
HPMC solubility in water has two types: surface-treated HPMC and non-surfaced treated HPMC.
3.1 surface treated HPMC solubility in cold water
When adding surface-treated HPMC into the water, HPMC will disperse into the cold water. But don’t have any viscosity. It is just dispersed. stir it and wait around 2 minutes, the solution becomes thick and viscous.
This is because instant HPMC’s surface has a kind of crosslinking agent. Most HPMC manufacturers like using Glyoxal as a crosslinking agent. This agent helps HPMC to disperse in cold water rather than dissolve at the beginning. So the price of surface treated HPMC is high than nor surface-treated HPMC.
3.2 Non-surface treated HPMC solubility in cold water
Hot melt products may condense when in contact with cold water. This is because the outer layer of non-surfaced treated HPMC reacted with cold water. This reaction makes the solution becomes viscous and thicken. The HPMC powder is wrapped in this transparent gel. Only the outer layer is dissolved. The dissolution rate of HPMC inside will be greatly slowed down.
Generally, it will be dissolved by dissolving in hot water.
4.HPMC solubility in organic solvents
Only in the case of polar organic solvents containing a higher percentage, HPMC can be dissolved in an organic solvent. This solubility doesn’t consider whether organic solvents have water. Compare to other substitutes, HPMC has a higher solubility in organic solvents. This is an HPMC solubility in organic solvents in detail. For example, HPMC solubility in IPA or ethanol.
4.1 HPMC solubility in ethanol or isopropyl alcohol
Is HPMC soluble in IPA?
Yes, it is
Is HPMC soluble in ethanol?
Yes, it is. But insoluble in anhydrous ethanol. HPMC exhibits good solubility in higher concentrations of ethanol or isopropyl alcohol.
Hand sanitizer gel generally consists of less than 40% water and more than 60% alcohol. Alcohol used to prevent diseases and eliminate bacteria. Hand sanitizer formulations use HPMC as a detergent thickener to increase viscosity.
Dissolution method of hydroxypropyl methylcellulose in water/alcohol mixture
1. Put ethanol or isopropanol in a container. Slowly add HPMC powder or another detergent thickener while stirring with a mixer
2. Continue stirring until a homogeneous suspension is observed
3. Slowly add cold water to dissolve
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