Chemical properties of Hydroxypropyl Methylcellulose

Hydroxypropyl methylcellulose is a non-ionic cellulose. It is a semi-synthetic substance with an inactive nature. It is a relatively viscous polymer. It is often used as a lubricant in ophthalmology and has an auxiliary effect when taken orally. It is also often used as a thickener in food or as a substitute for animal gelatin. It is also often used as an emulsifier. It is common in the food industry.

Chemical properties

1. Appearance: white or off-white powder.

2. Particle size: 100 mesh pass rate is greater than 98.5%; 80 mesh pass rate is 100%. Special specification particle size 40~60 mesh.

3. Carbonization temperature: 280-300℃

Hydroxypropyl methylcellulose

Hydroxypropyl methylcellulose

4. Apparent density: 0.25-0.70g/cm (usually around 0.5g/cm), specific gravity 1.26-1.31.

5. Color change temperature: 190-200℃

6. Surface tension: 2% aqueous solution is 42-56dyn/cm.

7. Solubility: Soluble in water and some solvents, such as ethanol/water, propanol/water in appropriate proportions. Aqueous solutions are surface active. High transparency, stable performance, different specifications of products have different gel temperatures, solubility changes with viscosity, the lower the viscosity, the greater the solubility, different specifications of HPMC have certain differences in performance, HPMC solubility in water is not affected by pH value.

8. As the methoxy content of HPMC decreases, the gel point increases, the water solubility decreases, and the surface activity also decreases.

9. HPMC also has the characteristics of thickening ability, salt resistance, low ash powder, pH stability, water retention, dimensional stability, excellent film-forming properties, as well as wide enzyme resistance, dispersibility and adhesion.

Dissolution method

1. All models can be added to the material by dry mixing;

2. When it is necessary to add directly to a room temperature aqueous solution, it is best to use a cold water dispersion type. It usually takes 10-90 minutes to thicken after adding;

3. For ordinary models, stir and disperse with hot water first, then add cold water, stir and cool to dissolve;

4. If lumps and clumping occur during dissolution, it is because of insufficient stirring or the ordinary model is directly added into cold water. At this time, it should be stirred quickly.

5. If bubbles are generated during dissolution, they can be left to stand for 2-12 hours (the specific time is determined by the solution viscosity) or removed by vacuuming, pressurizing, etc., or an appropriate amount of defoaming agent can be added.