Frysning av lyofiliserade produkter

När lösningen är snabbfrysta (10-50 grad per minut) förblir kristalliterna i storleken som är synlig under mikroskopet; on the contrary, when the solution is slow-frozen (1℃/min), the crystals formed are visible to the naked eye. Coarse crystals leave large gaps in the sublimation, which can improve the efficiency of freeze-drying, while fine crystals leave small gaps after sublimation, which hinders the sublimation of the lower layer. The structure is good, the dissolution speed is Snabb, och fuktabsorptionen av den färdiga produkten är relativt starkare . Läkemedlen är före frysna i frystorkaren på två sätt: en är att kyla ner produkten och torkugnen samtidigt; the other is to cool down the shelf of the drying oven to about -40℃, and then put the product in. The former is equivalent to slow freezing, and the latter is between quick freezing and slow freezing, so it is often used to take into account freeze-drying efficiency and product quality. The disadvantage of this method is that when the product is put into the box, the water vapor in the air will quickly condense on the shelf, and in the early stage of sublimation, if the plate heats up quickly, the sublimation of a large area may exceed the normal load of the condenser. This phenomenon is especially pronounced in summer. The freezing of the product is in a static state. Experience has proved that the phenomenon of supercooling is easy to occur until the temperature of the product has reached the eutectic point. However, the solute is still not crystallized. In order to overcome the supercooling phenomenon, the freezing temperature of the product should be lower than a range below the eutectic point, and it should be kept for a period of time until the product is completely frozen.