Introduction to film coating technology

What is film coating? The coating made of non sugar film-forming materials is generally only one or two thin layers, which is called film coating The main advantages of film coating: good quality As film-forming agents and most auxiliary additives are polymer materials with excellent physical and chemical properties, the film coated tablets can not only be moisture-proof, light-proof, taste masking and wear-resistant, but also not easily moldy and easily disintegrated, greatly improving the dissolution, bioavailability and validity of drugs, greatly expanding the countries and regions where drugs can be sold, and effectively promoting the export of drugs Especially traditional Chinese medicine Less weight gain The quality of the film coating is much lighter than that of the sugar coating Under the condition of the weight of the drug core, the weight of the packed tablets increases The weight of the latter is more than 10 times of the former Therefore, the film coating not only saves a lot of auxiliary materials in production, but also has obvious savings and convenience in packaging, storage, transportation and taking Fast drying Because of the fast drying, the coating operation time is short, generally only 2-3 hours, while sugar coating generally takes 10-16 hours, that is to say, if the same equipment is used for film coating, the utilization rate of equipment will be increased by more than three times, which is equal to the output that can be increased by more than three times; moreover, new workers can master the operation, unlike sugar coating, which can only be wrapped by experienced teachers In particular, many Chinese and Western medicines are sensitive to high temperature in varying degrees When coating, it is quick to dry and short to heat, which is also conducive to ensuring the quality of the core Image beauty The film is beautiful in shape, bright in color, fresh in logo and vivid in image The medicine core can adopt all kinds of flat and curved shapes, and the colors can adopt all kinds of bright colors The trademark and logo of the enterprise can be directly punched on the medicine core After the film coating is wrapped, it is still clear and obvious, which plays an important role in improving the image of the enterprise Many varieties At present, there are many film-forming materials and auxiliary materials, which can be made into film coating with various characteristics after careful design to change the release position of drug core and drug release characteristics Now, in addition to stomach soluble membrane and enteric soluble membrane, there are oral soluble membrane (including tablets), slow-release membrane, controlled-release membrane and composite membrane, as well as Zui new multi-layer membrane, microporous membrane, osmotic pump coating, targeted drug delivery coating, etc., which make The efficacy was greatly improved Widely used Now film coating has been widely used not only in Chinese and Western tablets and pills, but also in small tablets, small pills, granules, soft and hard capsules and even drug powder The film-forming materials can also be directly used in membrane agents, suspensions and hydrophobic drug dispersants There are many solvents Coating agent usually uses water as solvent to prepare coating solution, which not only reduces the cost, but also makes the operating environment more comfortable and safe However, for some drugs that absorb water quickly or will decompose or deteriorate when encountering water, they can only use non-aqueous solvent, which also has many kinds to choose from Standardization The design, process, material and quality of film coated tablets can be standardized and computerized, which is particularly important for GMP management and international sales Why is the use of coating powder for film coating the development trend? Just as film coating is developed to overcome the disadvantages of sugar coating and develop its advantages, coating powder is developed to overcome the disadvantages of self-made coating liquid and develop its advantages Coating powder mainly has the following four specific Uniform quality The coating powder with good quality is produced in industrialization and standardization From raw materials entering the factory, intermediate products to finished products, there are analysis and inspection step by step Only when it reaches the standard can it enter the next step until the finished products leave the factory After the finished products arrive at the pharmaceutical factory, there are also after-sales technical services, which can largely avoid all kinds of quality problems that may occur in the coating liquid prepared by the pharmaceutical factory, so as to achieve the goal of uniform coating film quality batch Cost savings The coating powder with good quality can be coated immediately only by dissolving and homogenizing, and can be prepared by the coating workers themselves, without the need for another special person, saving people, time and equipment, and the coating film quality is guaranteed In this way, according to the total performance price ratio, it can save a lot of cost compared with the coating liquid prepared by the enterprise sanitary The coating powder with good quality is not easy to oxidize, mildew, decompose and deteriorate It is now used as suspension before coating, which can avoid stratification, sedimentation, pollution, mildew and other phenomena that are easy to occur in overnight preparation Easy to use The coating powder with good quality is mostly water-soluble or alcohol soluble Some of them can be prepared with organic solvent or mixed solvent The preparation time is only 0.5-1h, and the coating workers can prepare it It is very convenient to use To sum up, the development of film coating must first develop coating powder with good quality Film coating technology problems and Countermeasures: sticking: mainly due to the spray rate is too fast, in violation of the principle of solvent evaporation balance, so that the pieces adhere to each other In this case, the spraying amount of coating liquid should be reduced, the temperature of hot air should be increased, and the rotating speed of the boiler should be increased The "orange peel" film is mainly caused by improper drying and low spray pressure of the coating liquid, resulting in uneven heat concentration of the ejected droplets, resulting in ripple of the film In this case, evaporation rate should be controlled immediately and spray pressure increased "Bridge construction": refers to the blurring of the mark caused by the coating film on the lettering piece The solution is: slow down the coating spraying speed, reduce the drying temperature, and pay attention to control the hot air temperature Appearance of color spots: this situation is caused by uneven mixing or insufficient fineness of solid characteristics when preparing coating solution The solution is to mix the coating solution well Cracks, cracks, peeling off or abrasion of the coating film on the surface or edge of the tablet: if the coating liquid-solid content is improperly selected, the rotating speed of the coating machine is too fast, and the spraying amount is too small, the appropriate coating liquid-solid content shall be selected, and the rotating speed and spraying amount shall be properly adjusted; if the hardness of the tablet core is too poor, the formula and process of the tablet core shall be improved "Frost spraying" appears on the coating film: this situation is caused by high humidity of hot air, long spraying process and poor atomization effect At this time, it is necessary to reduce the temperature, shorten the spray range and improve the atomization effect There is color difference between tablets: this situation is caused by the uneven fan surface when spraying liquid, excessive solid content of coating liquid or slow rotation speed of coating machine At this time, the spray angle of the spray gun should be adjusted, the solid content of the coating liquid should be reduced, and the rotating speed of the coating machine should be increased properly There are pinholes on the surface of coating film: this situation is caused by too much air involved in the preparation of coating solution Therefore, too much air should be avoided when dispensing Problems in film coating technology and Countermeasures in the early 1950s, * film coating tablets of real significance were born in the United States Since then, the film coating technology has experienced half a century of development However, it started late in China, and only in the late 1970s did a small number of pharmaceutical research institutions and pharmaceutical factories develop various coating solutions and film coating processes, and gradually promote their application Until the mid-1990s, the film coating technology "hot" gradually appeared in China But on the whole, the development of this technology in China is still relatively slow Many pharmaceutical enterprises still have many problems in application due to technical reasons On the surface of the core, spray a uniform coating of a relatively high polymer fabric and form a plastic film layer of several micron thickness to achieve the desired effect This process is called film coating The application of film coating technology is the demand and development trend of pharmaceutical industry Some people think that the film coated tablets are not as good as the sugar coated tablets and not as bright as the sugar coated tablets In fact, compared with the traditional sugar coated technology, the film coated technology has many advantages, such as shorter coating time, more moisture-proof, light proof, and stronger drug stability It is very important to change the concept of sugar coating in the past For a long time, some pharmaceutical companies regard film coating technology as an independent link in tablet production, and film coating is just like sugar coating In fact, it's not that simple As a new technology, film coating is much more strict than sugar coating in terms of chip core requirements and higher hardness requirements, and it also requires mutual cooperation between various processes, a series of technical indicators in the production process and adjustment and mutual matching of requirements Therefore, we must treat the introduction and application of film coating technology in a scientific and realistic manner Only in this way, the film can achieve the ideal effect Good core quality has a decisive effect on film coating Sometimes the mechanical quality of the core is too poor to carry out film coating at all Even if it is barely carried out, the film quality is difficult to guarantee Among all the factors that affect the mechanical properties of the chip core, the hardness and brittleness of the chip Zui are important, and the brittleness is more prominent than the hardness Generally speaking, the hardness of traditional Chinese medicine and Western medicine should be 5kg / cm3 and 4kg / cm3 respectively How to check it? The simple method of Zui is to test with a hardness tester; or to throw a plain piece vertically upward for 2 meters, so that it can land freely, and the hardness is qualified if there are more than two continuous cracks The simple way to check the brittleness is to use your fingers to scrape the edge or the surface of the tablet, which is better if there is no flake powder falling off; the other way is to place about 30 plain tablets in a 250ml glass and shake them vigorously for about two minutes, which is better if the surface and the edge of the tablet are not worn For the plain tablets with high hygroscopicity, the hardness requirement is higher When the film coating technology is applied to coating, whether the coating machine, fluidized bed coating machine or the sugar coated pot are used for coating, the following principles shall be followed: first, the hardness of the core shall be hard enough, otherwise, when the coating starts, the core and the wall of the pot will rub repeatedly, resulting in loose pieces and pockmarks; second, the temperature of the bed shall be kept constant; third, the evaporation of solvent in the equipment and The amount of solvent brought in during the spraying process should be kept in balance, that is, the solvent evaporation and the spraying rate are in a dynamic balance The key to one-sided flatness and delicacy lies in mastering the relationship among the temperature, spray rate and rotation speed of the pan in the whole process, which is the most important part in the operation of film coating During the operation, the atomization degree of the coating liquid directly affects the appearance quality of the coating film, while the atomization effect of the spray liquid is directly determined by the atomization pressure and the atomization system At the beginning of the spray, the principle of grasping the spray speed and the hot air temperature is to make the one side slightly moist, and prevent the one-sided adhesion, and the temperature should not be too low If the temperature is too high, the drying will be too fast, and the film will be rough and uneven; if the temperature is too low, or the spraying speed is too fast, the humidity in the pot will be too high, and soon the film will stick The relationship between the speed of the pot and the coating operation is: low speed, strong film adhesion; high speed, poor film adhesion, easy to peel off In the coating process, if the temperature is too low, the spray quantity is too large, and the film flows and remains, the phenomenon of sticking may appear At this time, the speed can be increased to improve it, and if necessary, the temperature, spray rate and spray range can be properly adjusted to overcome it Under the condition that the quality of coating powder remains unchanged, the common problems and solutions in coating operation are as follows: 1 Sticking: due to too fast spraying amount, which violates the principle of solvent evaporation balance, the tablets adhere to each other In this case, the coating liquid spray should be reduced properly