Hydroxypropyl Methylcellulose (HPMC)
Hydroxypropyl methylcellulose is a methylcellulose modified with a small amount of propylene glycol ether groups attached to the anhydroglucose of the cellulose. The dry product contains 19 per cent. to 30 per cent. of methoxyl (-OCH3) groups and 3 per cent. to 12 per cent. of hydroxypropyl (-OCH2CHOHCH3) groups.
Chemical names: Propylene glycol ether of methylcellulose
(1) Appearance: white or off-white powder
(2) Particle size: throughput efficiency of above 98.5% in 100 mesh, and 100% in 80 mesh.
(3) Carbonization temperature: 280-300
(4) Apparent density: 0.25-0.70g.cm3(usually about 0.5g/cm3), specific gravity: 1.26-1.31.
(5) Color degradation temperature: 190-200
(6) Surface tension: 42-56dyn/cn(2% aqueous solution)
(7) Soluble in water and some organic solvents: its aqueous solution is of surface tension, high transparency and stable property. The solubility varies with the viscosity, the lower the viscosity is, the higher solubility it has. The different HPMC is different in some properties and its solubility in water is not affected by pH
(8) The lower methoxyl content in HPMC, the higher gelatification temperature, the lower solubility in water and surface activity.
(9) HPMC has also other characteristic such as thickening property, pH stability, water retention , excellent film-forming property and good disperse and adhesion power.
Note: 2% aqueous solution at 20 ; *1% aqueous solution at 20 degree C.
Usage: Hydroxypropyl methylcellulose is mainly used as dispersant in the production of PVC and as thickener, stabilizer, emulsifier, excipient, water retention agent, film-forming agent in petrochemical, building materials, agrochemical, ink, printing and dyeing of textile, paper making, cosmetic, etc.
(1) Heat the water to above 85 and slowly add HPMC under slow agitation to gradually form uniform pulp, then cool under agitation to become transparent.
(2) Heat one third to two third of needed water to above 85, add HPMC to form heat pulp, then add residual water and remain agitation, cool to about 20 .
Package and storage: Sealed in the plastic-plated polypropylene woven bag, net weight: 20kg, keeping away from sun, rain and moisture during storage and transportation.