CN112043596A

CN112043596A - Medical tablet coating processing-based technology

Info

Publication number: CN112043596A
Application number: CN202010981600.6A
Authority: CN
Inventors: 陈晓盛
Original assignee: Individual
Current assignee: Beijing Tongrentang Xingan Health Technology Co.,Ltd.
Priority date: 2017-12-11
Filing date: 2017-12-11
Publication date: 2020-12-08
Anticipated expiration: 2037-12-11
Also published as: CN107802611B; CN107802611A; CN112043596B

Abstract

The invention discloses a process based on medical tablet coating processing, which comprises the following steps of (1) manufacturing a coating paddle: mixing talcum powder, hydroxypropyl methylcellulose and nano-scale silicon dioxide to prepare coating slurry; (2) preheating tablets: putting the tablets in coating equipment, spraying hot gas into the coating equipment through a gas spraying device arranged at the bottom of the coating equipment, and heating the interior of the coating equipment to heat the tablets; (3) and (4) coating. According to the invention, the hydroxypropyl methyl cellulose and the nano-scale silicon dioxide are added into the coating paddle, so that the coating has good characteristics of moisture resistance, oxidation resistance and corrosion resistance, the conditions of oxidation, dampness and deterioration of the tablets are effectively kept, and the stability of the tablets is greatly improved; the medicine property of the tablet can be slowed down, and the condition that the stomach of a user is uncomfortable is avoided.

Description

Medical tablet coating processing-based technology

Technical Field

The invention belongs to the technical field of feed additives, and particularly relates to a process based on medical tablet coating processing.

Background

In the pharmaceutical industry, tablets are generally coated with a coating which can protect the tablets, prevent the tablet chips from oxidative deterioration, moisture or volatilization, conceal unpleasant taste of the tablets when taken, and achieve the effects of facilitating identification of the tablets, alleviating dissolution and release in intestines and stomach of human bodies, and the like.

However, the existing coating is usually prepared from talcum powder, the prepared coating has poor moisture-proof and oxidation-resistant effects, and the tablet coated by the coating cannot achieve good moisture-proof and deterioration-resistant effects. In the existing coating process, the tablets are dried after all coatings are completely coated, so that the drying time is long and the energy consumption is high.

Disclosure of Invention

The invention provides a medical tablet coating processing-based process which is strong in coating performance, energy-saving and environment-friendly, and aims to overcome the defects of the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme: a process based on a medical tablet coating process comprising the steps of:

(1) manufacturing a package paddle: mixing talcum powder, hydroxypropyl methylcellulose and nano-scale silicon dioxide to prepare coating slurry;

(2) preheating tablets: putting the tablets in coating equipment, spraying hot gas into the coating equipment through a gas spraying device arranged at the bottom of the coating equipment, and heating the interior of the coating equipment to heat the tablets;

(3) coating: the bottom of the coating equipment is provided with a spray gun, and the coating paddle is conveyed into the spray gun through a feeding part and is sprayed upwards through the spray gun; meanwhile, the air injection device injects air upwards to ensure that the tablets are sprayed and fall freely, and the tablets are contacted with the coating paddle to coat the tablets; after coating for 30min, stopping the spray gun, maintaining the air injection device, and drying the first layer of coating for 20-30 min; and then the spray gun continues to work to spray the second layer of coating.

The coating paddle is formed by mixing talcum powder, hydroxypropyl methylcellulose and nano-scale silicon dioxide, and the nano-scale silicon dioxide has good moisture resistance, heat resistance, corrosion resistance and oxidation resistance, so that the finally obtained coating has good moisture resistance, oxidation resistance and corrosion resistance by adding the nano-scale silicon dioxide, the oxidation, moisture and deterioration of tablets can be effectively kept, and the stability of the tablets is greatly improved; secondly, the nano-scale material can also effectively enhance the glossiness of the coating, so that the outer surface of the finally prepared tablet has good glossiness; the hydroxypropyl methyl cellulose has good effect of slowing down the outward release of the drug property of the tablet, thereby effectively avoiding the excessive stimulation to the gastric mucosa caused by the too fast release of the drug and avoiding the condition that the stomach of a user is uncomfortable; by using the hydroxypropyl methyl cellulose and the nano-scale silicon dioxide simultaneously, the slow release of the tablet is realized under the condition of ensuring the strong stability of the tablet; the coating is sprayed in a layered spraying mode, so that the uniformity of the coating can be guaranteed, the coating is easy to dry completely, the drying speed is high, the energy consumption is reduced, and energy conservation and environmental protection are realized.

Further, after spraying the second layer of coating for 10-15min, stopping the spray gun, maintaining the air spraying device to work, and drying the second layer of coating for 10-15 min; the thickness of the second layer of coating is thinner than that of the first layer of coating, so that the spraying time is shorter, the drying time is shorter, and the loss of energy consumption is reduced.

Further, after the second layer of coating is dried, the spray gun continues to work, the third layer of coating is sprayed for 5-10min, then the spray gun stops working, the air injection device keeps working, and the third layer of coating is dried for 5-8 min; the thickness of the third layer of coating is thinner than that of the second layer of coating, so that the spraying time is shorter, the drying time is shorter, and the loss of energy consumption is reduced.

Further, the weight part ratio of the talcum powder to the hydroxypropyl methylcellulose to the nano-scale silicon dioxide is 2-4:1.5-2.5: 1.3-1.6; under this kind of proportion, talcum powder can fully play the effect of preventing bonding, guarantees after the misce bene, can not appear the condition of bonding between hydroxypropyl methyl cellulose, the nanometer silicon dioxide to compound on the surface distributes evenly after guaranteeing the tablet coating, has stronger stability.

Further, the weight part ratio of the talcum powder, the hydroxypropyl methyl cellulose and the nano-scale silicon dioxide is 3: 1.1:0.96.

Further, during the preheating step, the temperature in the coating equipment is maintained at 50-55 ℃; the temperature of the gas sprayed by the gas spraying device is 55-58 ℃, and the gas spraying speed is 1-2L/h; when the internal temperature of the coating equipment is lower than 50 ℃, the outer layer of the tablet is difficult to soften, so that the adhesive force of the coating paddle is poor during later coating, and the later coating effect is influenced; when the temperature is higher than 55 ℃, although the outer layer of the tablet can be well softened, the inner part of the tablet is also softened to a certain degree, so that the tablet can be dried only by drying for a long time in the drying step after coating, the working efficiency is low, and the energy consumption is extremely high; when the temperature in the coating equipment is maintained at 50-55 ℃, the outer layer of the tablet can be well softened, and the inner part of the tablet can not be influenced too much, so that the working efficiency can be ensured under the condition of ensuring good adhesive force, and the most energy-saving state is realized; when the temperature of the gas sprayed by the gas spraying device is lower than 55 ℃ and the gas spraying speed is lower than 1L/h, the speed of the hot gas spraying is lower than the speed of cooling the coating equipment, so that the temperature in the coating equipment is difficult to maintain within 50-55 ℃; when the temperature of the gas sprayed by the gas spraying device is higher than 58 ℃ and the gas spraying speed is higher than 2L/h, the temperature rising speed in the coating equipment is too high, so that the temperature in the coating equipment is higher than 55 ℃; after tests, the temperature of the gas sprayed by the gas spraying device is maintained at 55-58 ℃, and the gas spraying speed is maintained at 1-2L/h, so that the temperature in the coating equipment can be maintained within the range of 50-55 ℃.

Further, the coating equipment comprises an operation chamber, a spray gun, an air injection device, a feeding device and a recovery device; the spray gun is arranged at the bottom of the operation chamber, and the air injection device comprises a sleeve sleeved outside the spray gun, an air injection channel arranged in the sleeve and an injection piece connected with the air injection channel; the spraying piece is arranged obliquely; the spraying pieces are arranged in an inclined mode, and the inclined directions of the spraying pieces are arranged in the same direction; the recovery device comprises a recovery pipeline communicated with the bottom of the operation chamber, and a primary discharging part and a secondary discharging part which are arranged on the recovery pipeline. When the coating agent is used, the gas sprayed by the spraying piece can form rotational flow, so that the pellet core can rotate in the upward throwing process in the process of spraying the material upwards, the coating is more uniform, the distribution of the compound in the coating slurry outside the tablet is more uniform, the local damp and deterioration are not easy to occur, and the stability of the tablet is higher; secondly, because the gas is rotational flow, the running track of the pill core in the upward throwing process is spiral, so that the pill core stays in the air for a longer time, is in contact with the packing material for a long time, and has better coating effect; moreover, due to the action of the gas rotational flow, the pill core rotates around the spray head in a circle under the action of centrifugal force, and in the process of throwing the pill core upwards, the pill core cannot be thrown up from the position of the spray head, so that the problem that a large number of packing materials are partially coated on the pill core cannot occur, the outer surface of the pill core is uniformly coated, and the problem of unstable tablet components is effectively avoided; meanwhile, the uniform coating ensures that the release speed of the tablets in gastric juice is uniform, thereby effectively protecting the intestinal health of people; carry out the secondary through elementary ejection of compact spare and level ejection of compact spare and collect the material, guarantee by no longer remaining the powder in the exhaust steam, the powder separation rate is high.

Furthermore, the spray gun comprises a gun barrel and an atomizing spray head, and the atomizing spray head comprises a spray head body, a feeding channel, a first atomizing cavity arranged at the upper part of the spray head body, and a second atomizing cavity and a third atomizing cavity which are symmetrically arranged at the side part of the spray head body; the first atomizing cavity, the second atomizing cavity and the third atomizing cavity are respectively communicated with the feeding channel through a main spraying channel; atomize through three atomizing chamber respectively, mutually noninterfere between each atomizing chamber to the condition of orifice on the whole shower nozzle of comparison all communicates same atomizing chamber, and the pressure of the liquid in the atomizing chamber is bigger, thereby the jet power when making liquid spout from the orifice is bigger, and atomization effect is good, improves dry efficiency.

Further, a spiral drainage track is arranged on the inner wall of the main spraying channel; the inner wall through spraying the main entrance sets up to the heliciform for liquid is the swirl state when spraying the interior circulation of main entrance, thereby liquid is obviously obtained the increase by the impact force when being released to the atomizing intracavity, further promotes the atomization effect of shower nozzle.

Furthermore, a primary atomizing part and a secondary atomizing part are respectively arranged in the first atomizing cavity, the second atomizing cavity and the third atomizing cavity, and a space is formed between the primary atomizing part and the secondary atomizing part to form an atomizing space for spraying and dispersing the medium; the space between the two can guarantee to atomize the fog that erupts via primary atomizing part, can be the spray of form of dispersing to secondary atomizing part on, be basically that the liquid droplet form strikes to secondary atomizing part on, prevent that the liquid that erupts to be the liquid column and sprayed to secondary atomizing part on to the fog droplet can disperse into the fog pearl of minor diameter rapidly after the processing of secondary atomizing part, realizes good atomization effect.

Furthermore, the primary atomization component comprises a primary atomization plate, a central channel arranged in the center of the primary atomization plate and a circle of edge channels arranged on the edge of the primary atomization plate, the distance between every two adjacent edge channels is equal, and spiral impact tracks are arranged on the inner walls of the central channel and the edge channels; the impact rail is arranged, so that the double rotational flow effect of the liquid in the spray head is realized, and the maximum impact force of the liquid during atomization is ensured; divide into central passageway and marginal passageway, the distribution of passageway is comparatively dispersed to the passageway is when spraying liquid, and liquid has bigger space to disperse, can not appear striking the circumstances of offsetting the impact force each other.

Further, the secondary atomization component comprises a secondary atomization plate and a plurality of atomization spray hole groups arranged on the secondary atomization plate, and the positions of the atomization spray hole groups correspond to the positions of the central channel and the edge channel; the atomization spray hole group is a plurality of atomization holes which are annularly arranged; the liquid sprayed out from the channel is generally annular after being dispersed outwards; thereby be annular setting with the atomizing hole, the position of the liquid of correspondence that can be better is gone out, guarantees that liquid is in the biggest state to the impact force of atomizing hole to reach good atomization effect, make the drying effect of product good.

Furthermore, the inner wall of the atomization hole is provided with a rough layer, and a plurality of reinforcing protrusions are arranged on the rough layer; through bellied setting, can cut via the downthehole spun liquid of atomizing and break up, guarantee good atomization effect.

In summary, the invention has the following advantages: hydroxypropyl methylcellulose and nano-scale silicon dioxide are added into the coating paddle, so that the coating has good moisture-proof, oxidation-resistant and corrosion-resistant characteristics, the conditions of oxidation, moisture and deterioration of the tablets are effectively kept, and the stability of the tablets is greatly improved; the medicine property of the tablet can be released outwards quickly, and the condition that the stomach of a user is uncomfortable is avoided; the coating is sprayed in a layered spraying mode, so that the uniformity of the coating can be guaranteed, the coating is easy to dry completely, the drying speed is high, the energy consumption is reduced, and energy conservation and environmental protection are realized.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a schematic structural view of the sleeve of the present invention.

Fig. 3 is a schematic structural diagram of the atomizer according to the present invention.

Fig. 4 is a schematic structural view of a primary atomizing member of the present invention.

Fig. 5 is a schematic structural view of the secondary atomizing member of the present invention.

Fig. 6 is an enlarged view at B in fig. 4.

Fig. 7 is a top view of a secondary atomization plate of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

Example 1

A process based on a medical tablet coating process comprising the steps of: (1) manufacturing a package paddle: mixing talcum powder, hydroxypropyl methyl cellulose and nano-scale silicon dioxide in a mixer to prepare the package paddle, wherein the weight part ratio of the talcum powder to the hydroxypropyl methyl cellulose to the nano-scale silicon dioxide is 2: 1.5: 1.3; specifically, 20kg of talcum powder, 15kg of hydroxypropyl methyl cellulose and 1.3kg of nano-silicon dioxide are mixed to obtain the nano-composite material; (2) preheating tablets: placing the tablets to be coated in a coating apparatus comprising an operating room 1, a spray gun 4, an air-jet device 2, a feeding device 3 and a recovery device 5, as shown in fig. 1-7; the spray gun 4 is arranged at the bottom of the operation chamber 1, the air injection device 2 comprises a sleeve 21 sleeved outside the spray gun, an air injection channel arranged in the sleeve, an injection part 23 connected with the air injection channel and an air blower 24, a heating part 25 is arranged between the air blower 24 and the sleeve 21, the heating part 25 is respectively connected with the air blower 24 and the sleeve 21 through a hose, and the heating part is a heater directly purchased from the market; the injection piece 23 is arranged obliquely; a material blocking barrel 11 is arranged at the bottom of the operation chamber 1, and a feeding gap is formed between the lower part of the material blocking barrel 11 and the bottom wall of the operation chamber 1; when coating, hot air is sprayed into the coating equipment through an air spraying device arranged at the bottom of the coating equipment, so that the temperature inside the coating equipment is raised; specifically, the temperature of the gas sprayed by the gas spraying device is 55 ℃, the gas spraying speed is 1L/h, so that the temperature in the coating equipment is continuously maintained at 50 ℃, and the tablets are heated; (3) coating: the bottom of the coating equipment is provided with a spray gun, and the coating paddle is conveyed into the spray gun through a feeding part and is sprayed upwards through the spray gun; meanwhile, the air injection device injects air upwards, so that the tablets are sprayed and fall freely, and contact with the coating paddle is realized to coat the tablets.

Specifically, the feeding device 2 is a peristaltic pump directly purchased from the market, and the feeding device 2 is connected with the spray gun 4 through a hose; the spray gun 4 comprises a gun barrel and an atomizing nozzle connected to the upper end of the gun barrel, and as shown in fig. 3-7, the atomizing nozzle comprises a nozzle body 41, a feed channel 42, a first atomizing chamber 43, a second atomizing chamber 44 and a third atomizing chamber 45; the feeding channel 42 is arranged at the center of the spray head body 41, and the feeding channel 42 is communicated with the feeding device 2; the first atomizing cavity 43 is arranged at the upper part of the spray head body, and the second atomizing cavity 44 and the third atomizing cavity 45 are positioned below the first atomizing cavity 43 and correspond to the side part of the spray head body; wherein the number of the second atomizing chambers 44 is 2, and the number of the third atomizing chambers 45 is 2; preferably, the second atomization chamber 44 and the third atomization chamber 45 are arranged in bilateral symmetry along the central axis of the nozzle body.

The first atomizing cavity 43, the second atomizing cavity 44 and the third atomizing cavity 45 are respectively communicated with the feeding channel 42 through a main spraying channel 46, preferably, a spiral flow guide track 461 is arranged on the inner wall of the main spraying channel 46, and specifically, the flow guide track 461 is a spiral groove arranged on the inner wall of the main spraying channel 46; in order to enhance the atomization effect, a primary atomization component 47 and a secondary atomization component 48 are respectively arranged in the first atomization chamber 43, the second atomization chamber 44 and the third atomization chamber 45, and a distance is reserved between the primary atomization component 47 and the secondary atomization component 48, so that an atomization space 49 is formed, when a medium is sprayed out from the primary atomization component 47, the medium can be dispersed and then collides with the secondary atomization component 48, and the atomization effect is better.

Specifically, as shown in fig. 4, the primary atomizing member 47 includes a primary atomizing plate 471 fixed in the atomizing chamber, a cylindrical central passage 472 provided at the central portion of the primary atomizing plate, and a cylindrical edge passage 473, the edge passage 473 is provided in plural, and is provided at the upper surface of the primary atomizing plate near the edge, the plural edge passages 473 are provided around the outer circle of the central passage 472 with the central passage 472 as the center, and the intervals between the adjacent edge passages are equal; preferably, the central channel 472 and the edge channel 473 are provided with impact tracks 474, and in particular, the impact tracks 474 are helical grooves which are respectively provided on the inner walls of the central channel 472 and the edge channel 473.

Specifically, as shown in fig. 5-7, the secondary atomizing member 48 includes a secondary atomizing plate 481 fixed to the atomizing chamber and a plurality of atomizing orifice sets 482 provided on the secondary atomizing plate, the positions of the atomizing orifice sets corresponding to the positions of the central channel 472 and the edge channel 473 one by one; further, the atomizing spray hole group 482 is a plurality of atomizing holes 483, the atomizing holes 483 form a ring shape by enclosing, and the distances between the adjacent atomizing holes 483 are equal; in order to enhance the atomization effect, a rough layer 484 is arranged on the inner wall of the atomization hole 483, and specifically, the rough layer 484 is a rubber layer with a rough surface; furthermore, a plurality of reinforcing protrusions 485 are uniformly arranged on the rubber layer at intervals.

The recovery device 5 comprises a recovery pipeline 51 connected with the top of the operation chamber, and a primary discharging part 52 and a secondary discharging part 53 which are arranged on the recovery pipeline; specifically, the primary discharge member 52 is a cyclone discharge device directly purchased from the market; the secondary discharging member 53 comprises a discharging chamber 531 and a wind closing machine arranged at the lower part of the discharging chamber, the side wall of the discharging chamber 531 is communicated with the recycling pipeline 51, and the inner wall of the discharging chamber 531 is provided with a spiral track, so that wind can form a vortex after entering the discharging chamber 531.

Example 2

A process based on a medical tablet coating process comprising the steps of: (1) manufacturing a package paddle: mixing talcum powder, hydroxypropyl methyl cellulose and nano-scale silicon dioxide in a mixer to prepare the package paddle, wherein the weight part ratio of the talcum powder to the hydroxypropyl methyl cellulose to the nano-scale silicon dioxide is 4: 2.5: 1.6; specifically, 40kg of talcum powder, 25kg of hydroxypropyl methyl cellulose and 1.6kg of nano-silicon dioxide are mixed to obtain the nano-composite material; (2) preheating tablets: placing the tablets to be coated in a coating apparatus comprising an operating room 1, a spray gun 4, an air-jet device 2, a feeding device 3 and a recovery device 5, as shown in fig. 1-7; the spray gun 4 is arranged at the bottom of the operation chamber 1, the air injection device 2 comprises a sleeve 21 sleeved outside the spray gun, an air injection channel arranged in the sleeve, an injection part 23 connected with the air injection channel and an air blower 24, a heating part 25 is arranged between the air blower 24 and the sleeve 21, the heating part 25 is respectively connected with the air blower 24 and the sleeve 21 through a hose, and the heating part is a heater directly purchased from the market; the injection piece 23 is arranged obliquely; a material blocking barrel 11 is arranged at the bottom of the operation chamber 1, and a feeding gap is formed between the lower part of the material blocking barrel 11 and the bottom wall of the operation chamber 1; when coating, hot air is sprayed into the coating equipment through an air spraying device arranged at the bottom of the coating equipment, so that the temperature inside the coating equipment is raised; specifically, the temperature of the gas sprayed by the gas spraying device is 58 ℃, the gas spraying speed is 2L/h, so that the temperature in the coating equipment is continuously maintained at 55 ℃, and the tablets are heated; (3) coating: the bottom of the coating equipment is provided with a spray gun, and the coating paddle is conveyed into the spray gun through a feeding part and is sprayed upwards through the spray gun; meanwhile, the air injection device injects air upwards, so that the tablets are sprayed and fall freely, and contact with the coating paddle is realized to coat the tablets.

The other structures of the coating device are the same as those of the coating device in example 1, and thus the description is omitted.

Example 3

A process based on a medical tablet coating process comprising the steps of: (1) manufacturing a package paddle: mixing talcum powder, hydroxypropyl methyl cellulose and nano-scale silicon dioxide in a mixer to prepare the package paddle, wherein the weight part ratio of the talcum powder to the hydroxypropyl methyl cellulose to the nano-scale silicon dioxide is 3:1.1: 0.96; specifically, 30kg of talcum powder, 11kg of hydroxypropyl methyl cellulose and 9.6kg of nano-silicon dioxide are mixed to obtain the nano-composite material; (2) preheating tablets: placing the tablets to be coated in a coating apparatus comprising an operating room 1, a spray gun 4, an air-jet device 2, a feeding device 3 and a recovery device 5, as shown in fig. 1-7; the spray gun 4 is arranged at the bottom of the operation chamber 1, the air injection device 2 comprises a sleeve 21 sleeved outside the spray gun, an air injection channel arranged in the sleeve, an injection part 23 connected with the air injection channel and an air blower 24, a heating part 25 is arranged between the air blower 24 and the sleeve 21, the heating part 25 is respectively connected with the air blower 24 and the sleeve 21 through a hose, and the heating part is a heater directly purchased from the market; the injection piece 23 is arranged obliquely; a material blocking barrel 11 is arranged at the bottom of the operation chamber 1, and a feeding gap is formed between the lower part of the material blocking barrel 11 and the bottom wall of the operation chamber 1; when coating, hot air is sprayed into the coating equipment through an air spraying device arranged at the bottom of the coating equipment, so that the temperature inside the coating equipment is raised; specifically, the temperature of the gas sprayed by the gas spraying device is 55 ℃, the gas spraying speed is 1.5L/h, so that the temperature in the coating equipment is continuously maintained at 53 ℃, and the tablets are heated; (3) coating: the bottom of the coating equipment is provided with a spray gun, and the coating paddle is conveyed into the spray gun through a feeding part and is sprayed upwards through the spray gun; meanwhile, the air injection device injects air upwards, so that the tablets are sprayed and fall freely, and contact with the coating paddle is realized to coat the tablets.

It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims

1. A process based on medical tablet coating processing is characterized in that: the method comprises the following steps:

manufacturing a package paddle: mixing talcum powder, hydroxypropyl methylcellulose and nano-scale silicon dioxide to prepare coating slurry; the weight part ratio of the talcum powder to the hydroxypropyl methyl cellulose to the nano-scale silicon dioxide is 2-4:1.5-2.5: 1.3-1.6; the weight part ratio of the talcum powder to the hydroxypropyl methyl cellulose to the nano-scale silicon dioxide is 3:1.1: 0.96;

preheating tablets: putting the tablets in coating equipment, spraying hot gas into the coating equipment through a gas spraying device arranged at the bottom of the coating equipment, and heating the interior of the coating equipment to heat the tablets; the temperature in the coating equipment is maintained at 50-55 ℃; the temperature of the gas sprayed by the gas spraying device is 55-58 ℃, and the gas spraying speed is 1-2L/h;

coating: the bottom of the coating equipment is provided with a spray gun, and the coating paddle is conveyed into the spray gun through a feeding part and is sprayed upwards through the spray gun; meanwhile, the air injection device injects air upwards to ensure that the tablets are sprayed and fall freely, and the tablets are contacted with the coating paddle to coat the tablets; after coating for 30min, stopping the spray gun, maintaining the air injection device, and drying the first layer of coating for 20-30 min; then the spray gun continues to work to spray the second layer of coating; after the second layer of coating is sprayed for 10-15min, the spray gun stops working, the air injection device keeps working, and the second layer of coating is dried for 10-15 min; after the second layer of coating is dried, the spray gun continues to work, the third layer of coating is sprayed for 5-10min, then the spray gun stops working, the air injection device keeps working, and the third layer of coating is dried for 5-8min

The coating equipment comprises an operation chamber (1), a spray gun (4), an air injection device (2), a feeding device (3) and a recovery device (5); the spray gun (4) is arranged at the bottom of the operation chamber (1), and the air injection device (2) comprises a sleeve (21) sleeved outside the spray gun, an air injection channel arranged in the sleeve and an injection piece (23) connected with the air injection channel;

the spray gun (4) comprises a gun barrel and an atomizing spray head, wherein the atomizing spray head comprises a spray head body (41), a feeding channel (42), a first atomizing cavity (43) arranged at the upper part of the spray head body, and a second atomizing cavity (44) and a third atomizing cavity (45) which are symmetrically arranged at the side part of the spray head body; the first atomizing cavity (43), the second atomizing cavity (44) and the third atomizing cavity (45) are respectively communicated with the feeding channel (42) through a main spraying channel (46);

a primary atomizing part (47) and a secondary atomizing part (48) are respectively arranged in the first atomizing cavity (43), the second atomizing cavity (44) and the third atomizing cavity (45), and a space is formed between the primary atomizing part (47) and the secondary atomizing part (48) to form an atomizing space for spraying and dispersing media;

the primary atomizing component (47) comprises a primary atomizing plate (471) fixedly arranged in the atomizing cavity, a cylindrical central channel (472) arranged at the center of the primary atomizing plate and a cylindrical edge channel (473), the edge channels (473) are arranged in a plurality and are arranged on the upper surface of the primary atomizing plate close to the edge, the edge channels (473) are arranged around the outer circle of the central channel (472) by taking the central channel (472) as a circle center, and the intervals between the adjacent edge channels are equal;

the central channel (472) and the edge channel (473) are both provided with an impact track (474), and the impact track (474) is a spiral groove respectively provided with the inner walls of the central channel (472) and the edge channel (473);

the secondary atomizing member (48) includes a secondary atomizing plate (481) fixedly provided on the atomizing chamber and a plurality of atomizing orifice groups (482) provided on the secondary atomizing plate, the positions of the atomizing orifice groups corresponding one-to-one to the positions of the central passage (472) and the edge passage (473);

the atomization spray hole group (482) is a plurality of atomization holes (483), the atomization holes (483) form a ring shape by enclosing a circle, and the intervals between the adjacent atomization holes (483) are equal;

the inner wall of the atomization hole (483) is provided with a rough layer (484), the rough layer 484 is a rubber layer with a rough surface, and a plurality of reinforcing protrusions (485) are uniformly arranged on the rubber layer at intervals.