1、 Basic Basic Information
Full name: Hydroxypropyl Methyl Cellulose, abbreviated as HPMC, pharmacopoeial name Hypromellose (Hydroxypropyl Methylcellulose)
CAS number: 9004-65-3
Category: Semi synthetic, non-ionic water-soluble cellulose mixed ether, natural cotton/wood cellulose chemically modified product
Production principle: Refined cotton short fibers/wood pulp are alkalized to produce alkali cellulose, which is then etherified with chloromethane (methylation) and epichlorohydrin (hydroxypropylation), washed with hot water, neutralized, dried, and crushed to obtain it; Non toxic, odorless and tasteless, plant derived, no animal protein

Schematic diagram of HPMC molecular structure
2、 Appearance and core physical and chemical indicators
1. Appearance and form
White/off white fibrous/fine particle powder, with a fluffy texture and no clumping; Conventional 80 mesh 100% sieving, high fineness models above 100 mesh
2. Key physical parameters
Specific gravity: 1.26-1.31; Visual density: 0.25~0.70 g/cm ³
Color changing temperature: 190-200 ℃; Carbonization decomposition temperature: 280~300 ℃
1% aqueous solution pH: 4.0~8.0, pH 3~11 is stable throughout the process, and the viscosity of the acid-base system does not decrease
Dry weight loss: ≤ 5%; Ash content: Industrial/building materials grade ≤ 2%, pharmaceutical and food grade ≤ 1%
Gel temperature: 58~90 ℃ (divided into E/F/K series models), heated to gel, cooled to recover liquid (reversible thermal gel characteristics)
3. Dissolution characteristics (core unique features)
Cold water instant, hot water gel: It can be completely dissolved into transparent viscous liquid when stirred in cold water at room temperature; If the temperature is higher than gel temperature, gel will be precipitated, cooled and re dissolved
Soluble in ethanol/water and isopropanol/water mixed solvents; Pure high concentration alcohol, acetone, insoluble in hot water
Dissolving method: dry mixing method (pre mixed with powder and then added with water); Ordinary models can be dispersed and broken with hot water first, and then cooled and dissolved with cold water to avoid clumping and clumping
Water solution is a pseudo plastic fluid: viscosity decreases with high-speed stirring, viscosity is restored after standing, construction is not easy to splash, and coating is smooth
4. Core chemical properties
Non ionic structure: does not react with metal ions or electrolytes, has strong salt resistance, and is suitable for formulations containing inorganic salts
Excellent film-forming properties: drying forms a flexible, transparent, breathable film with strong adhesion
Six composite functions of water retention, thickening, suspension, emulsification, lubrication, and bonding
Resistant to enzymatic degradation, stable viscosity of aqueous solution after long-term storage; Preservatives need to be added to prevent microbial growth