The film coating process uniformly sprays a relatively stable polymer polymer coating on the surface of the core by spraying to form a plastic film layer of several micrometers thick, so as to achieve a certain expected effect. Compared with the traditional sugar coating technology, the film coating has the advantages of short time consumption, moisture resistance, light protection and stronger drug stability. With the rapid development of the pharmaceutical industry, the film coating process has been widely used in tablets, pills, granules, especially for traditional Chinese medicine tablets which are strong in temperature absorption, easy to crack and easy to fade.
According to the industry, as a new technology, the film-coated clothing has stricter requirements on the core, including its interaction with each other, a series of technical indicators and requirements for adjustment and mutual support in the production process. Claim. Therefore, in order to achieve the desired coating effect, it must be strictly in accordance with manufacturing standards.
Pay attention to the quality of the core
Good core quality has a decisive influence on the film coating. When the quality of the core is too poor, film coating work cannot be performed or is difficult. The quality of the core is related to the hardness and friability of the tablet, with friability being more important. In the industry, in general, the hardness of a medium tablet suitable for film coating should be 5kg/cm3, and the hardness of a western tablet should be about 4kg/cm3.
So how do you check the hardness of the sheet? The industry recommends a simple method for hardness tester detection; or throw a single piece vertically up to 2 meters to make it free to land, more than two times without breaking, the hardness is qualified.
The method of checking the friability is to use a finger to force the edge of the blade or the surface of the sheet, and it is better to have no powder falling off; another method is to place 30 pieces of the plain tablet in a 250 ml glass and shake it vigorously for two minutes. Left and right, it is preferable that the surface of the sheet and the edge of the sheet are not worn. For the hygroscopic film, the hardness requirement is higher.
Focus on the principle of coating
At present, there are many kinds of coating equipment on the market, but no matter which kind of equipment, you should pay attention to the principle of coating. According to the industry, the key to maintaining a smooth and delicate coating surface is the mastery of the whole process, including the relationship between pot temperature, spray volume and speed. This is the top priority in the film coating operation.
In operation, the appearance quality of the coating film of the coating is affected by the degree of atomization of the coating liquid, and the atomization effect of the spray liquid is directly determined by the atomization pressure and the atomization system. Therefore, at the beginning of the spray, it is first necessary to grasp the principle of the spray speed and the hot air temperature to make the sheet surface slightly moist, pay attention to prevent the surface adhesion, and the temperature should not be too low. If the temperature is too high, the drying is too fast, the film formation is easy to be rough, and the color of the film is uneven; if the temperature is too low, or the spray speed is too fast, the humidity in the pan is too high, and the adhesion of the film will soon appear. .
The relationship between the rotation speed of the pan and the coating operation is: the rotation speed is low, the adhesion of the film is strong; the rotation speed is high, the adhesion of the film is poor, and the film is easily peeled off. During the coating process, if the temperature is too low, the spray volume is too large, and the film flows, the sticking phenomenon may occur. At this time, the rotation speed can be increased to improve, and if necessary, the temperature, the spray amount, and the spray range can be appropriately adjusted to overcome.
Understand the common problems of coating
It is understood that in the case of the use of the quality of the coating powder, the problems often appear in the coating include the adhesive sheet: mainly due to the too fast spray volume, which violates the principle of solvent evaporation balance and causes the sheets to adhere to each other. In this case, the spray volume of the coating liquid should be appropriately reduced, the hot air temperature should be increased, and the rotation speed of the pot should be accelerated.
The "orange peel" film appeared: mainly due to improper drying, the spray pressure of the coating liquid was low, and the sprayed droplets were unevenly heated and the film was corrugated. In this case, the evaporation rate should be controlled immediately to increase the spray pressure.
Appearance, "bridge": refers to the film on the lettering film caused by the logo is blurred. The solution is to slow down the spray speed of the coating and reduce the drying temperature, and at the same time, control the hot air temperature.
Spotting: This condition is caused by uneven mixing with the coating liquid or insufficient fineness of the solid traits. The solution is to mix well with the coating liquid.
Cracks, cracks, flaking or edge wear of the tablets on the surface or edge of the tablet: if the solid content of the coating liquid is improperly selected, the speed of the coating machine is too fast, and the spray volume is too small, the appropriate coating liquid solid content should be selected. , properly adjust the speed and the amount of spray; if the core hardness is too bad, you should improve the formulation and process of the core.
The film appears to be "blooming": this situation is caused by excessive humidity of the hot air, too long spray range, and poor atomization. At this time, the temperature should be appropriately lowered, the spray range should be shortened, and the atomization effect should be improved.
There is color difference between the tablets: this situation is caused by uneven fan-out of the spray or excessive solid content of the coating liquid or slow rotation speed of the coating machine. At this time, the angle of the spray gun should be adjusted, the solid content of the coating liquid should be lowered, and the rotation speed of the coating machine should be appropriately increased.
There are pinholes on the surface of the film: this is caused by the entrapment of excess air when preparing the coating solution. Therefore, avoid excessive air entrapment during dosing.
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