Hydroxypropyl methyl cellulose (Hypromellose) is a white to off-white cellulose powder or pellet that has the properties of being soluble in cold water and insoluble in hot water similar to methyl cellulose. Hydroxypropyl group and methyl group are ether bond and cellulose anhydrous glucose ring combined, is a non-ionic cellulose mixed ether. It is a semi-synthetic, inactive, viscoelastic polymer commonly used in ophthalmology as a lubricant or as an excipient or excipient in oral drugs

The preparation of
The kraft paper pulp with α-cellulose content of 97%, intrinsic viscosity of 720ml/g and average fiber length of 2.6mm was impregnated in 49% NaOH solution at 40℃ for 50 seconds. The resulting pulp was then extruded to remove the excess of 49% NaOH aqueous solution to obtain alkali cellulose. The weight ratio of (49% NaOH in water) to (solid component in pulp) in the impregnation step was 200. The weight ratio (NaOH component in base cellulose) to (solid component in pulp) was 1.49. The alkali cellulose (20kg) thus obtained was placed in a jacketed pressure reactor with internal agitation and then vacuumed and purged with nitrogen gas to adequately remove oxygen from the reactor. Then, the temperature in the reactor was controlled at 60℃, while the internal stirring was carried out. Then, 2.4kg of dimethyl ether was added and the temperature in the reactor was controlled to maintain at 60 ° C. After the addition of dimethyl ether, methylene chloride was added to make the molar ratio of (methylene chloride) to (NaOH component in basic cellulose) 1.3, propylene oxide was added to make the weight ratio of (propylene oxide) to (solid component in pulp) 1.97, and the temperature in the reactor was controlled from 60 ° C to 80 ° C. After the addition of chloromethane and propylene oxide, the temperature in the reactor was controlled from 80℃ to 90℃. In addition, the reaction was maintained at 90 ° C for 20 minutes. Then, the gas is discharged from the reactor, and the crude hydroxypropyl methyl cellulose is removed from the reactor. The temperature of crude hydroxypropyl methylcellulose was 62℃ when it was removed. Measure the cumulative 50% particle size in the cumulative weight based particle size distribution determined based on the ratio of crude hydroxypropyl methylcellulose passing through openings in five screens, each with a different opening size. As a result, the average particle size of rough particles is 6.2mm. The obtained crude hydroxypropyl methylcellulose was introduced into a continuous biaxial kneader (KRC kneader S1, L/D = 10.2, internal volume 0.12 L, rotation speed 150rpm) at a speed of 10kg/hr to obtain decomposed crude hydroxypropyl methylcellulose. As measured similarly using five screens with different opening sizes, the average particle size was 1.4mm. The slurry was obtained by adding hot water at 80 ° C to the decomposed crude hydroxypropyl methylcellulose in the tank with jacket temperature control, and the weight ratio of (the amount of hydroxypropyl methylcellulose in the decomposed crude hydroxypropyl methylcellulose) to (the total amount of slurry) was changed to 0.1. The slurry was stirred at a constant temperature of 80 ° C for 60 minutes. Then, the slurry is supplied to a rotary pressure filter (BHS Sonthofen product) with a rotation speed of 0.5 RPM and pre-heated. The temperature of the slurry was 93℃. The slurry is supplied by a pump with a discharge pressure of 0.2mpa. The opening size of the rotary pressure filter is 80μm, and the filtration area is 0.12m2. The slurry supplied to the rotary pressure filter is filtered through the filter and transformed into filter cake. The resulting cake was fed with steam of 0.3MPa and hot water at 95 ° C to a weight ratio of 10.0 to the solid component of washed hydroxypropyl methylcellulose and then filtered through a filter. The hot water is supplied by a pump with a discharge pressure of 0.2mpa. After the hot water is supplied, 0.3MPa of steam is supplied. The washed product on the surface of the filter is then removed through a scraper and discharged out of the washer. Continuous steps from the supply of slurry to the discharge of the washed product. The water content of the washed product was 52.8% as measured by heating drying hygrometer. The washed products discharged from the rotary pressure filter were dried using an air dryer at 80 ° C and crushed in the impact mill Victory mill to obtain hydroxypropyl methylcellulose.

application
This product is used as thickening agent, dispersant, binder, emulsifier and stabilizer in textile industry. Also widely used in synthetic resin, petrochemical, ceramic, paper, leather, medicine, food, cosmetics and other industries.