Control and solution during the coating process

Coating is an important part of the tablet production process. How to do the coating work directly affects the quality of the coated tablets, so I give some personal views on the coating according to the known coating process.

First of all, the process of sugar coating:

The auxiliary materials required for sugar coating are sucrose, talc, gelatin and pigment, wherein the amount of talc powder can reach more than 50% of the weight of the core.

There are six steps in general sugar coating:

1. The bottom layer can rarely reach more than 6kg due to the hardness of the core. In addition, the individual cores have certain pine pieces. If the isolation layer is directly coated, it is easy to cause the film core to rot in the rolling process. However, it affects the quality of the tablet, so it is necessary to coat 2-3 layers of powder coating layer to increase the core hardness and wear resistance.

2. The barrier layer prevents physical or chemical degradation of the active ingredient in the core by moisture attack.

3. The powder coating layer is rolled to the desired shape and size with 2% gelatin syrup and talc powder.

4, sugar coating layer single syrup.

5. Colored layer of colored syrup.

6. Polish wax or lacquer to achieve bright luster and prevent the intrusion of humid air from outside.

The sugar coated material is prepared freshly to prevent the mildew and other pollution during storage from affecting the quality of the coating. The commonly used materials have the following preparation methods.

1. Preparation of single syrup: the general concentration is 68-70%. Add the calculated purified water to a suitable sandwich container, heat it to boiling by steam and then slowly weigh the sucrose into the container. Stir while stirring, wait for the solution to boil, clean the foam floating on the top, stop heating, and heat it through a 100 mesh sieve to the syrup storage container for heat preservation.

2, the preparation of gelatin slurry: generally containing gelatin amount of 10-15% should be freshly prepared dosage of 120g / 10,000 tablets. Add appropriate amount of gelatin to a stainless steel container and add 10 times of distilled water for more than 12 hours to make the gelatin all expand and heat and dissolve in a water bath for later use.

3, 2% gelatin syrup preparation: Take appropriate amount of gelatin soaked until fully expanded in a sandwich container, heat to add residual distilled water, and heat it to boiling after soaking gelatin, add the calculated sucrose and boil for filtration.

4. Preparation of colored syrup: The dosage of soluble food coloring syrup is generally 0.03-0.3% or depending on the color depth of the specific variety. For example, the dosage of lemon yellow is 0.5g/10,000 pieces, and the pigment is dissolved and added to a certain amount of single syrup. Should be from shallow to deep.

5, talcum powder: the main material of the powder coating is used as a bulking agent.

6, Sichuan wax: white or white-like block, need to be refined before use, heated in a water bath 80-100 ° C dissolved in 100 mesh sieve to remove impurities, cooled and used as a spare, crushed into 80 mesh fine powder when used, you can add some Dimethicone is used as a glossing agent.

The process of coating sugar:

1. Bottom layer: Turn a certain amount of core into the coating pan, turn on the electric furnace to heat the wall, add a certain amount of syrup (the amount depends on the specific variety), so that it can be quickly dispersed evenly, immediately add talcum powder to make the core Do not feel wet, blow the hot air (temperature 30-50 ° C) to dry the sheet, repeat the operation 2-3 times, so that the surface of the core is evenly distributed a mixture of syrup and talcum powder.

2, isolation layer: different from the bottom layer is to use 1015% gelatin syrup plus talcum powder package, until the core is all packaged.

3, powder coating layer: commonly used materials talcum powder, single syrup, 2% gelatin syrup.

The tablets rotating in the pot were alternately packaged with an appropriate amount of warm 2% gelatin syrup and talc.

4. Sugar coating layer: Wet and dry with a single syrup on the outside of the powder coating layer, so that the core is covered with a layer of sugar crystals to form a clothing layer, which is generally blown.

5, colored sugar coating layer: mixed with a single color syrup in different proportions with the single syrup preparation after the surface of the sugar coating is flat, generally starting from the light color paste gradually darken the color, the amount of use is gradually reduced until the color uniform.

6, lighting: after the Zui after a colored syrup is added to close to dry, stop the coating pan, and cover the lid, flip several times, so that the temperature inside the pot is reduced to room temperature, so that the water slowly lost, the surface has tiny crystals, After the one-sided surface is dry, turn the pot on and sprinkle the appropriate amount of wax powder (first use dry wax powder to make the pieces rub against each other, and then produce the gloss and then use the wax powder with the added base silicone oil) until the one side is extremely bright.

Precautions during operation:

1. The time of adding talc should be added immediately after the first and second layers of syrup are evenly mixed. The dosage should be such that the core does not feel wet. Otherwise, the addition of water will penetrate into the core, making the film difficult to dry and easy to cause. During the storage of the sugar-coated tablets, cracks or discoloration and deliquescence occur, and the layers should be dried during the operation.

2. At the end of the operation of the powder coating layer, the leveling operation should be carried out. Each time the amount of syrup used is 2/3 of the powder coating layer, a small amount of talc powder is needed, so that the uneven surface of the sheet is gradually flattened by long-time friction. The temperature is controlled at 30-35 ° C, starting slightly higher, and then gradually decreasing, the amount of syrup also decreases with temperature until the sheet is flat.

3, the temperature of the coating layer should not be too high, the temperature is too high, the water can evaporate quickly, the surface sugar crystals are easy to precipitate, so that the surface is rough, the spots appear, and it is not suitable to use the hot slurry, otherwise the finished product will not be bright, and the lighting is difficult to carry out. Do not warm, apply the remaining temperature of the pot or core to evaporate the water.

4. When the sugar coating layer is to be coated, the surface of the core should be smooth and delicate. Otherwise, the sugar coating will be unevenly distributed, so that the surface appears on the surface. When the layer is colored, it should not be too wet, and should not be too dry, otherwise it is not easy to light.

5, the key to lighting is to control the dryness of the sugar-coated tablets, humidity, high temperature, the surface is not easy to shine, small pieces are more dry than large pieces, there are seasonal effects, in order to prevent slipping, wax powder should be scattered in several times Appropriate application, such as excessive use can make the face wrinkled.

Summary: The operating principle of the tablet-coated icing is "a small number of times, layer by layer".

Sugar coating has always been a common coating form for tablets, but there are many shortcomings: 1. Long production cycle; 2. Long-term heat and humidity conditions in the process, complicated process and high labor intensity; 3. Large amount of sugar is needed. And talcum powder, poor moisture resistance.

Process control and problem solving for film coating:

The first is the requirements of the film coating process and equipment:

1. Make the coating clean and evenly cover the surface of the core.

2. The core should be continuously mixed during the coating process in order to obtain a uniform coating effect.

3. Continue and quickly dry the pieces.

4. Quickly remove the dust and dry air and atomizing air generated in the coating.

In order to achieve effective coating efficiency and evenly distribute the coating solution on the surface, we usually use an air spray gun. The position of the spray gun is especially important, especially when using multiple spray guns, when the distance between the spray gun and the core is too close. Or too far away from the surface of the bed, then the film at the overlap of the atomizing fan will appear to be too warm, when the distance between the gun and the sheet is too close or too close to the surface of the bed, due to the The void will cause the edge of the core to wear (causing the film formation speed to be slow). The incorrect position of the gun will also cause the film to stick due to the moisture of the wall or the baffle. The ideal position of the spray gun and the atomizing fan should be at the intersection of the ones. It is beneficial to disperse the coating liquid to achieve dry balance (the specific position is that the distance between the gun and the sheet is 250-300mm, and the gun and the sheet should be at a 90 degree angle).

The coating conditions are adjusted by measuring and controlling the bed temperature during the coating process. The use temperature is for reference only.

Preparation of coating liquid:

Add the calculated solvent to the liquid preparation container. The liquid level of the solvent is about the same as the diameter of the container. Mix the stirrer 2/3 below the liquid surface. The diameter of the stirrer should be 1/3 of the diameter of the container. The agitator should be stirred at a speed such that the liquid in the container is completely agitated, and the liquid surface just forms a vortex.

The powder of the coating agent with the exact amount of weighing is continuously sprinkled on the surface of the vortex at a constant rate. The rate of addition should be such that the powder is quickly stirred into the vortex, and the feeding process should be completed within 5 minutes.

After the addition is completed, the stirring speed is slowed down, the vortex is just disappeared, and the stirring is continued for 45 minutes until the coating agent is completely dispersed, and the preparation can be directly pumped out from the container.

Preparation points:

1. The powder should be added at a constant rate. As the viscosity of the solution increases, it may be necessary to increase the stirring speed to maintain the vortex.

2. Stirring should be maintained after the coating is finished to avoid excessive air entrapment.

Attachment: Formulation formula for coating material Coating powder dosage = core weight × 4%

Solution weight = coating powder weight ÷ 8%

The amount of solvent = weight of the solution - the amount of powder coating

coating process:

1. Chip core preheating: Pour the fine core sieve to the fine powder into the coating pan, turn on the hot air, and rotate the coating pan. The rotation speed is controlled at 1-3 rpm, and the core is preheated to 40 ~. Coating at 45 ° C.

2. Coating: Open the compressed air valve, the pressure is controlled at 0.3~0.6mpa, and the speed of the pot is adjusted to 5 rpm. The peristaltic pump is sprayed. The peristaltic amount is adjusted according to the temperature of the core, and the initial amount is large. Gradually reduce it later, the temperature also drops below 37 ° C, suspend the spray, and then spray after the temperature rises to prevent the film from sticking to ensure quality.

The direction of the spray is 1/3 of the bed, and the hot air is the lower third of the bed. Pay close attention to the temperature change of the core, keep it above 37 °C, and master the core temperature.

Problems and treatment methods:

1. Adhesion: Because the quality of the coating solution is greater than the drying capacity, the surface is wet, and the adhesion after the Zui causes mutual adhesion. At this time, the adhered cores are separated from each other during the continuous rotation of the coating pan, and the film at the adhesion is broken. .

Solution: Make a dynamic balance between the spray volume and drying capacity of the coating pan, reduce the spray volume or increase the temperature of the dry air, and increase the solid content of the coating liquid.

2. There are two reasons for the rough surface:

1) Spray drying The surface of the coated core is dark and rough, and the surface of the core has a sheet mark. Solution: Reduce the atomization pressure and reduce the air volume and air temperature of the incoming air. It is possible to adjust the formulation of the coating material and reduce the amount of organic solvent.

2) Orange peel-like rough: The surface of the coated tablet core is bright and rough, because the spray solution cannot be dispersed into fine particles due to insufficient atomization pressure. Solution: Increase the atomization pressure, adjust the solid content in the coating formulation and reduce the viscosity of the coating solution.

3. Edge wear: The main reason is that the spraying speed of the coating solution is too slow to protect the edge of the core in time. Solution: Increase the spray volume, reduce the speed, and use a high amount of coating liquid to speed up the film. Adjusting the formulation of the coating solution, increasing the strength of the film, alleviating the degree of wear and reducing the wear resistance of the core.

4, chromatic aberration: (this is rarely the case in film garments) The reason is that the mixing efficiency of the coating pan is too poor, so that it is impossible to achieve a uniform coating effect between the sheets during the normal coating time. . Solution: Extend the coating time, increase the speed of the pan, and increase the strength of the coating material.

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