Preparation method and device of solvent-free conformal coating

Abstract

The invention belongs to the technical field of solvent-free conformal coating preparation, and particularly relates to a solvent-free conformal coating preparation method and device, and the preparation method comprises the following steps: weighing a polysiloxane ring mixture according to the amount, and placing the polysiloxane ring mixture in a reaction kettle; then adding an acid catalyst or a base catalyst, and slowly adding H2O; a product A is obtained; putting the material into a reaction kettle to obtain a material A1, filling nitrogen, sealing, storing and cooling; putting the cooled material A1 into a reaction kettle, adding diacetylmonoxime, stirring for 10 minutes, and then adding methyltrimethoxysilane, methyldimethoxysilane and tetramethyl orthosilicate to obtain an alkoxy-terminated product A2; and when the product A2 returns to normal temperature, adding the silane auxiliary agent, the flatting agent and the defoaming agent, and filling nitrogen to obtain a finished product of the conformal coating. Low-molecular-weight alkoxy silicone oil is synthesized from a synthesis end, and a silane auxiliary agent, a flatting agent, a defoaming agent, a catalyst and the like are added to prepare the solvent-free silicon three-proofing paint which accords with an environmental protection policy.

Description

Technical Field

[0001] The present invention belongs to the technical field of solvent-free conformal coating preparation, in particular to a method and device for preparing solvent-free conformal coating. Background Art

[0002] Silicone materials have excellent properties such as aging resistance and high and low temperature resistance. Silicone conformal coatings are also resistant to corrosion, salt spray, dust, and static electricity, making them widely used for circuit board protection in the electronics and electrical industry. However, most silicone conformal coatings on the market contain organic solvents, with a solids content of approximately 70%. Around 30% of the solvent evaporates, posing a safety hazard and not complying with national environmental protection policies, resulting in high disposal costs.

[0003] A Chinese patent with publication number CN214320015U discloses a device for preparing low-viscosity, environmentally friendly electronic conformal coating, comprising an outer container, an inner container, a top cover, a No. 1 motor, a power shaft, a box body, a door, a No. 2 motor, and a pressure sensor. The inner container is arranged in the outer container, the top cover is fixed to the top of the outer container, the No. 1 motor is fixed to the top of the top cover, the power shaft is fixed to the bottom end of the No. 1 motor, and a stirring blade is fixed on the power shaft. An inlet is provided at the top of the box body, the door is provided in a through hole in the right side wall of the box body, and the top of the door is connected to the box body via a spring hinge. The No. 2 motor is provided in a cavity at the bottom of the box body, a reel is fixed to the front end of the No. 2 motor, a pull rope is wound on the reel, and the other end of the pull rope is tied to the bottom end of the door. The pressure sensor is provided between the top wall of the inner container and the box body. Self-preparation and weighing are achieved to meet the various needs of users.

[0004] In the above-mentioned technology, during the preparation process of solvent-free conformal coating, no organic solvent is added, but some water needs to be added for mixing and stirring. During the mixing process of the raw materials and water, pores are easily formed between the raw materials. When the raw materials with pores are used to prepare the conformal coating product, the conformal coating product will have defects, resulting in poor quality of the conformal coating product.

[0005] To this end, the present invention provides a method and device for preparing a solvent-free conformal coating. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a preparation method of a solvent-free conformal coating according to the present invention, the preparation method comprising the following steps: S1: First, weigh the polysiloxane ring mixture (i.e., DMC) according to the amount and place it in a reactor. Raise the temperature to 60-90°C, evacuate and stir, and remove water by negative pressure evacuation. Then, add an acid catalyst or a base catalyst, slowly add H2O, and start to maintain the temperature and stir for about 5 hours to open the DMC ring and insert hydroxyl groups. Then, neutralize the mixture by cooling or deactivate the base catalyst by heating, etc., so that the pH value of the material returns to neutral. After completing the above steps, product A is obtained. S2: The materials are placed back into the reactor, heated to 150-200°C, and vacuumed to start decompression for 3-5 hours. After completion, the obtained material A1 is filled with nitrogen, sealed, and stored for cooling; S3: Place the cooled material A1 into a reactor, add butanone oxime, stir for 10 minutes, then add the capping agents: methyltrimethoxysilane, methyldimethoxysilane, and methyl orthosilicate, and fill with nitrogen and stir; after completion, the alkoxy-terminated product A2 is obtained; S4: After the product A2 returns to room temperature, add silane additives, leveling agent, and defoaming agent, fill with nitrogen and start stirring for 30 minutes. After stirring is completed, add tackifier and stir for 30 minutes. Finally, add catalyst and stir for 30 minutes to obtain the finished product of three-conformal paint.

[0008] Preferably, in S1, the solvent-free conformal coating comprises the following raw materials in percentage by mass: DMC: 95-99.5%; H2O: 0.5~5%.

[0009] Preferably, in S3, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A1 product: 90-96%; Butanone oxime: 0.5-2%; Main resin: 1-5%; The main resin includes any one or two of methyltrimethoxysilane, methyldimethoxysilane and methyl orthosilicate.

[0010] Preferably, in S4, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A2 product: 85-95%; Methyl silicone oil: 10-15%; Silane additives: 1-3%; Leveling agent: 0.1~0.5%; Defoaming agent: 0.1~0.5%; Thickener: 0.1-0.5%; Catalyst: 0.2-5%; The silane auxiliary agent includes methyltrimethoxysilane and methyltrihexyloxysilane, the adhesion promoter includes epoxysilane and aminosilane polar group substances, and the catalyst includes organic tin and titanate.

[0011] A device for preparing a solvent-free conformal coating, preferably, the solvent-free conformal coating is stirred using a stirring mechanism, and the stirring mechanism includes: base; Four pillars fixed to the top of the base; Slide the mounting plate attached to the four struts; An outer cylinder fixedly connected to the mounting plate; A second motor is fixedly connected to the top of the outer cylinder, and the output shaft of the second motor extends into the interior of the outer cylinder and is fixedly connected to a rotating rod; a plurality of stirring paddles are fixedly connected to the rotating rod; a U-shaped scraper is fixedly connected to the bottom of the rotating rod, and the U-shaped scraper is in contact with the inner wall of the inner cylinder; a discharge pipe is connected to the bottom of the outer cylinder, and a control valve is installed on the discharge pipe; The outer sides of the pillars are each sleeved with a spring, and the two ends of the spring are respectively fixed to the bottom of the mounting plate and the top of the base; the two ends of the top of the base are each fixed to two fixed plates; an elliptical block is rotatably connected between the two fixed plates via a rotating shaft; the two fixed plates on the same side are each fixed to a first motor, and the output shaft of the first motor is fixed to one end of the rotating shaft.

[0012] Preferably, a vacuum chamber is opened inside the outer cylinder, an inner cylinder is fixedly connected to the inner wall of the outer cylinder, a heating chamber is formed between the inner cylinder and the outer cylinder, and a plurality of heating wires are fixedly connected in the heating chamber.

[0013] Preferably, the top of the outer cylinder is connected to and fixedly connected to a feed hopper, the bottom of the feed hopper is rotatably connected to a sealing plate via a rotating shaft, and the bottom of the sealing plate is fixedly connected to a pressure sensor; one end of the rotating shaft extends to the outside of the feed hopper and is fixedly connected to a gear; an electric push rod is fixedly connected to the outer wall of the feed hopper, and the output end of the electric push rod is fixedly connected to a rack, which meshes with the gear; a sliding opening is provided on the rack; two limit blocks are fixedly connected to the outer wall of the feed hopper, and the limit blocks both slide in the sliding opening.

[0014] Preferably, the top of the outer cylinder is hollowed out and fixed with a filter plate, which is an activated carbon plate; the top of the outer cylinder is fixed with an exhaust pipe; the exhaust pipe is arranged on the outside of the filter plate and is equipped with an air release valve.

[0015] Preferably, the top of the outer cylinder is connected and fixedly connected to a water inlet pipe, and a plugging head is installed on the water inlet pipe.

[0016] Preferably, the top of the outer cylinder is connected and fixedly connected with an air intake pipe, and an air intake valve is installed on the air intake pipe.

[0017] The beneficial effects of the present invention are as follows: 1. The present invention discloses a method and apparatus for preparing a solvent-free conformal coating. By synthesizing a low-molecular-weight alkoxy silicone oil from a synthesis end, instead of the traditional dilution method using organic solvents, the solvent-free silicone conformal coating is prepared by adding silane additives, leveling agents, defoamers, catalysts, and other components. This method complies with national environmental protection policies and reduces processing costs.

[0018] 2. The present invention discloses a method and apparatus for preparing a solvent-free conformal coating. Through the coordination of a spring and an elliptical block, a first motor is activated, which drives a rotating shaft, which in turn drives the elliptical block. Due to the shape of the elliptical block, the elliptical block intermittently pushes a mounting plate upward. The mounting plate then rapidly returns to its original position under the action of gravity and the spring force, generating a primary vibration. As the elliptical block continues to rotate, the mounting plate drives the outer cylinder to vibrate back and forth. This vibration eliminates air holes between the raw materials, thus resolving the problem of air holes that reduce the quality of the solvent-free conformal coating.

[0019] 3. The method and apparatus for preparing a solvent-free conformal coating described in the present invention utilize a sealing plate and a pressure sensor. During the feeding process, the pressure sensor detects the mass of the raw materials in the feed hopper in real time. When the raw materials reach a set mass value, the pressure sensor transmits a signal to a computer program via the pressure sensor. The computer program issues an alarm and stops feeding. At the same time, the computer program controls an electric push rod, which is turned on to drive the rack to move. The rack drives the gear to rotate, and the gear drives the rotating shaft and the sealing plate to rotate. The sealing plate releases the blockage on the feed hopper, allowing the raw materials to fall into the inner cylinder. Then, under the action of the electric push rod, the sealing plate rotates to a horizontal position to seal the feed hopper, realizing the function of automatic quantitative control of feeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 is a flow chart of the method of the present invention; Figure 2 is a first stereogram of the present invention; Figure 3 is a second perspective view of the present invention; Figure 4 It is a sectional view of the main view in the present invention; Figure 5 It is a structural diagram of the spring and the support in the present invention; Figure 6 It is a structural schematic diagram of the feed hopper in the present invention; Figure 7 It is a schematic diagram of the structure of the invention at point A; In the figure: 1. Base; 2. Outer cylinder; 21. Discharge pipe; 22. Control valve; 23. Vacuum chamber; 24. Heating wire; 25. Inner cylinder; 3. Mounting plate; 31. Support; 32. Spring; 33. Fixing plate; 34. Elliptical block; 35. First motor; 4. Feed hopper; 41. Sealing plate; 42. Pressure sensor; 43. Electric push rod; 44. Rack; 45. Gear; 46. Sliding port; 47. Limit block; 5. Second motor; 51. Rotating rod; 52. Agitating paddle; 53. U-shaped scraper; 6. Inlet pipe; 61. Inlet valve; 7. Exhaust pipe; 71. Filter plate; 72. Air relief valve; 8. Water inlet pipe; 82. Sealing head. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods. Example 1

[0023] like Figure 1 As shown, a method for preparing a solvent-free conformal coating according to an embodiment of the present invention comprises the following steps: S1: First, weigh the polysiloxane ring mixture (i.e., DMC) according to the amount and place it in a reactor. Raise the temperature to 60°C, evacuate and stir, and remove water by negative pressure evacuation. Then, add an acid catalyst or a base catalyst, slowly add H2O, and start to maintain the temperature and stir for about 5 hours to open the DMC ring and insert hydroxyl groups. Then, neutralize the mixture by cooling or deactivate the base catalyst by heating, etc., so that the pH value of the material returns to neutral. After completing the above steps, product A is obtained. S2: The materials were put back into the reactor, heated to 150°C, and vacuum was applied at the same time to start decompression and degassing. The time was maintained for 3 hours. After completion, the obtained material A1 was filled with nitrogen and sealed for storage and cooling; S3: Place the cooled material A1 into a reactor, add butanone oxime, stir for 10 minutes, then add the capping agents: methyltrimethoxysilane, methyldimethoxysilane, and methyl orthosilicate, and fill with nitrogen and stir; after completion, the alkoxy-terminated product A2 is obtained; S4: After the product A2 returns to room temperature, add silane additives, leveling agent, and defoaming agent, fill with nitrogen and start stirring for 30 minutes. After stirring is completed, add tackifier and stir for 30 minutes. Finally, add catalyst and stir for 30 minutes to obtain the finished product of three-conformal paint.

[0024] In S1, the solvent-free conformal coating comprises the following raw materials in percentage by mass: DMC: 95%; H2O: 0.5%.

[0025] In S3, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A1 product: 90%; Butanone oxime: 0.5%; Main resin: 1%; The main resin includes methyltrimethoxysilane and methyldimethoxysilane.

[0026] In S4, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A2 product: 85%; Methyl silicone oil: 10%; Silane additives: 1%; Leveling agent: 0.1%; Defoaming agent: 0.1%; Thickener: 0.1%; Catalyst: 0.2%; The silane auxiliary agent includes methyltrimethoxysilane and methyltrihexyloxysilane, the adhesion promoter includes epoxysilane and aminosilane polar group substances, and the catalyst includes organic tin and titanate. Example 2

[0027] like Figure 1 As shown, a method for preparing a solvent-free conformal coating according to an embodiment of the present invention comprises the following steps: S1: First, weigh the polysiloxane ring mixture (i.e., DMC) according to the amount and place it in a reactor. Raise the temperature to 75°C, evacuate and stir, and remove water by negative pressure evacuation. Then, add an acid catalyst or a base catalyst, slowly add H2O, and start to maintain the temperature and stir for about 5 hours to open the DMC ring and insert hydroxyl groups. Then, neutralize the mixture by cooling or deactivate the base catalyst by heating, etc., so that the pH value of the material returns to neutral. After completing the above steps, product A is obtained. S2: The materials were put back into the reactor, heated to 175°C, and vacuum was applied at the same time to start decompression and degassing. The time was maintained for 4 hours. After completion, the obtained material A1 was filled with nitrogen and sealed for storage and cooling; S3: Place the cooled material A1 into a reactor, add butanone oxime, stir for 10 minutes, then add the capping agents: methyltrimethoxysilane, methyldimethoxysilane, and methyl orthosilicate, and fill with nitrogen and stir; after completion, the alkoxy-terminated product A2 is obtained; S4: After the product A2 returns to room temperature, add silane additives, leveling agent, and defoaming agent, fill with nitrogen and start stirring for 30 minutes. After stirring is completed, add tackifier and stir for 30 minutes. Finally, add catalyst and stir for 30 minutes to obtain the finished product of three-conformal paint.

[0028] In S1, the solvent-free conformal coating comprises the following raw materials in percentage by mass: DMC: 97%; H2O: 2.7%.

[0029] In S3, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A1 product: 93%; Butanone oxime: 1.3%; Main resin: 3%; The main resin includes methyldimethoxysilane and methyl orthosilicate.

[0030] In S4, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A2 product: 90%; Methyl silicone oil: 13%; Silane additives: 2%; Leveling agent: 0.3%; Defoaming agent: 0.3%; Tackifier: 0.3%; Catalyst: 1.3%; The silane auxiliary agent includes methyltrimethoxysilane and methyltrihexyloxysilane, the adhesion promoter includes epoxysilane and aminosilane polar group substances, and the catalyst includes organic tin and titanate. Example 3

[0031] like Figure 1 As shown, a method for preparing a solvent-free conformal coating according to an embodiment of the present invention comprises the following steps: S1: First, weigh the polysiloxane ring mixture (i.e., DMC) according to the amount and place it in a reactor. Heat it to 90°C and stir it under vacuum to remove water by vacuuming. Then, add an acid catalyst or a base catalyst, slowly add H2O, and start stirring at this temperature for about 5 hours to open the DMC ring and insert hydroxyl groups. Then, neutralize it by cooling it or deactivate the base catalyst by heating it. The pH value of the material is returned to neutral. After completing the above steps, product A is obtained. S2: The materials were put back into the reactor, heated to 200°C, and vacuum was applied at the same time to start decompression and degassing. The time was maintained for 5 hours. After completion, the obtained material A1 was filled with nitrogen and sealed for storage and cooling; S3: Place the cooled material A1 into a reactor, add butanone oxime, stir for 10 minutes, then add the capping agents: methyltrimethoxysilane, methyldimethoxysilane, and methyl orthosilicate, and fill with nitrogen and stir; after completion, the alkoxy-terminated product A2 is obtained; S4: After the product A2 returns to room temperature, add silane additives, leveling agent, and defoaming agent, fill with nitrogen and start stirring for 30 minutes. After stirring is completed, add tackifier and stir for 30 minutes. Finally, add catalyst and stir for 30 minutes to obtain the finished product of three-conformal paint.

[0032] In S1, the solvent-free conformal coating comprises the following raw materials in percentage by mass: DMC: 99.5%; H2O: 5%.

[0033] In S3, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A1 product: 96%; Butanone oxime: 2%; Main resin: 5%; The main resin includes methyltrimethoxysilane and methyl orthosilicate.

[0034] In S4, the solvent-free conformal coating comprises the following raw materials in percentage by mass: A2 product: 95%; Methyl silicone oil: 15%; Silane additives: 3%; Leveling agent: 0.5%; Defoaming agent: 0.5%; Tackifier: 0.5%; Catalyst: 5%; The silane auxiliary agent includes methyltrimethoxysilane and methyltrihexyloxysilane, the adhesion promoter includes epoxysilane and aminosilane polar group substances, and the catalyst includes organic tin and titanate.

[0035] When the preparation method provided by the present invention is used, the polysiloxane ring body mixture is first weighed according to the amount and placed in a reactor, the temperature is raised to 60°C, and vacuum is stirred to remove water by negative pressure vacuuming; then an acid catalyst or a base catalyst is added, H2O is slowly added, and then the temperature is kept and stirred for about 5 hours to open the DMC ring body and connect the hydroxyl group, and then the pH value of the material is returned to neutral by cooling and neutralizing or heating to inactivate the base catalyst; the above steps are completed to obtain product A; the material is placed in the reactor again, the heating is turned on to 150°C, and vacuum is connected at the same time, and the decompression and denitrification are started, and the time is maintained for 3 hours. After completion, the obtained material A1 is filled with nitrogen, sealed, and stored for cooling; the cooled material A1 is placed in the reactor In the reactor, butanone oxime was added, and after stirring for 10 minutes, a capping agent (methyltrimethoxysilane, methyldimethoxysilane, methyl orthosilicate) was added, and nitrogen was introduced and stirred; after completion, an alkoxy-terminated product A2 was obtained; after the product A2 returned to room temperature, a silane additive, a leveling agent, and a defoaming agent were added, and nitrogen was introduced and stirred for 30 minutes. After the stirring was completed, a tackifier was added and stirred for 30 minutes, and finally a catalyst was added and stirred for 30 minutes to obtain the finished conformal coating. By proposing to synthesize a low molecular weight alkoxy silicone oil from the synthesis end, instead of the traditional dilution method using an organic solvent, a solvent-free silicone conformal coating was prepared by adding additives, catalysts and other components, which complies with national environmental protection policies and reduces processing costs.

[0036] like Figures 2 to 7 As shown, a device for preparing a solvent-free conformal coating is provided. The solvent-free conformal coating is stirred using a stirring mechanism. The stirring mechanism includes: a base 1; four pillars 31 fixedly connected to the top of the base 1; a mounting plate 3 slidably connected to the four pillars 31; an outer cylinder 2 fixedly connected to the mounting plate 3; A second motor 5 is fixedly connected to the top of the outer cylinder 2. The output shaft of the second motor 5 extends into the interior of the outer cylinder 2 and is fixedly connected to a rotating rod 51. A plurality of stirring paddles 52 are fixedly connected to the rotating rod 51. A U-shaped scraper 53 is fixedly connected to the bottom of the rotating rod 51. The U-shaped scraper 53 is in contact with the inner wall of the inner cylinder 25. A discharge pipe 21 is fixedly connected to the bottom of the outer cylinder 2. A control valve 22 is installed on the discharge pipe 21. The outer sides of the pillars 31 are each sleeved with a spring 32, and the two ends of the spring 32 are respectively fixed to the bottom of the mounting plate 3 and the top of the base 1; the two ends of the top of the base 1 are each fixed to two fixing plates 33; an elliptical block 34 is rotatably connected between the two fixing plates 33 via a rotating shaft; a first motor 35 is fixed to the two fixing plates 33 on the same side, and the output shaft of the first motor 35 is fixed to one end of the rotating shaft.

[0037] During the mixing process of raw materials and water, pores are easily formed between the raw materials. Raw materials with pores will cause defects in the three-proof paint product when preparing the three-proof paint product, resulting in poor quality of the three-proof paint product. When the stirring paddle 52, support 31 and spring 32 provided by the present invention are used, during the stirring process, by turning on the second motor 5, the second motor 5 drives the rotating rod 51 to rotate, and the rotating rod 51 drives the stirring paddle 52 to rotate. The stirring paddle 52 fully stirs the raw materials. When the rotating rod 51 rotates, it drives the U-shaped scraper 53 to rotate. The U-shaped scraper 53 scrapes the raw materials on the inner wall of the inner cylinder 25 to prevent the raw materials from adhering to the inner wall of the inner cylinder 25, which is inconvenient to clean. In addition, the U-shaped scraper 53 expands the stirring area. During the stirring process, the first motor 35 needs to be turned on to drive the rotating shaft to rotate. The rotating shaft drives the elliptical block 34 to rotate. According to the shape characteristics of the elliptical block 34, the elliptical block 34 intermittently pushes the mounting plate 3 upward. Then, under the action of gravity and the elastic force of the spring 32, the mounting plate 3 quickly resets, forming a vibration. As the elliptical block 34 continues to rotate, the mounting plate 3 drives the outer cylinder 2 to vibrate back and forth. The vibration eliminates the air holes between the raw materials, solving the problem of air holes reducing the quality of the solvent-free conformal coating.

[0038] like Figure 4 As shown, a vacuum chamber 23 is provided inside the outer cylinder 2 , an inner cylinder 25 is fixedly connected to the inner wall of the outer cylinder 2 , a heating chamber is formed between the inner cylinder 25 and the outer cylinder 2 , and a plurality of heating wires 24 are fixedly connected in the heating chamber.

[0039] When in use, the vacuum chamber 23 provided by the present invention separates the outer tube 2 and the inner tube 25 to form a separation layer, thereby reducing heat loss and keeping the raw materials warm. By setting up a heating chamber, the raw materials can be heated at different temperatures to facilitate the reaction of the raw materials.

[0040] like Figures 6 and 7 As shown, the top of the outer cylinder 2 is connected and fixedly connected to the feed hopper 4, and the bottom of the feed hopper 4 is rotatably connected to a sealing plate 41 through a rotating shaft, and the bottom of the sealing plate 41 is fixedly connected to a pressure sensor 42; one end of the rotating shaft extends to the outside of the feed hopper 4 and is fixedly connected to a gear 45; an electric push rod 43 is fixedly connected to the outer wall of the feed hopper 4, and the output end of the electric push rod 43 is fixedly connected to a rack 44, and the rack 44 is engaged with the gear 45; a sliding opening 46 is opened on the rack 44; two limit blocks 47 are fixedly connected to the outer wall of the feed hopper 4, and the limit blocks 47 both slide in the sliding opening 46.

[0041] When the sealing plate 41 and pressure sensor 42 provided by the present invention are in use, during the feeding process of the feed hopper 4, the pressure sensor 42 detects the quality of the raw materials in the feed hopper 4 in real time. After the raw materials reach the set quality value, the signal is transmitted to the computer program through the pressure sensor 42. The computer program issues an alarm and stops feeding. At the same time, the electric push rod 43 is controlled by the computer program. The electric push rod 43 is turned on, driving the rack 44 to move, and the rack 44 drives the gear 45 to rotate. The gear 45 drives the rotating shaft and the sealing plate 41 to rotate, and the sealing plate 41 releases the blockage of the feed hopper 4, and the raw materials fall into the inner cylinder 25. Then, under the action of the electric push rod 43, the sealing plate 41 rotates to horizontally block the feed hopper 4, realizing the function of automatic quantitative control of feeding.

[0042] like Figure 4 As shown, the top of the outer cylinder 2 is hollowed out and fixed with a filter plate 71, which is an activated carbon plate; the top of the outer cylinder 2 is fixed with an exhaust pipe 7; the exhaust pipe 7 is arranged on the outside of the filter plate 71 and is installed with a relief valve 72.

[0043] When the filter plate 71 provided by the present invention is in use, after heating, the pressure in the inner tube 25 is relatively high. When cooling is required, the air relief valve 72 is opened, and the gas is output from the exhaust pipe 7. At the same time, part of the toxic gas is discharged. By setting the filter plate 71, part of the carbon-containing gas is filtered, the discharge of toxic gas is reduced, and environmental protection is achieved.

[0044] like Figure 2 As shown, the top of the outer cylinder 2 is connected and fixedly connected with a water inlet pipe 8, and a plugging head 82 is installed on the water inlet pipe 8.

[0045] When the water inlet pipe 8 provided by the present invention is in use, the sealing head 82 is opened, the water inlet pipe 8 is connected to the water pump through a hose, and an appropriate amount of water is added.

[0046] like Figure 2 As shown, the top of the outer tube 2 is connected and fixedly connected with an air intake pipe 6, and an air intake valve 61 is installed on the air intake pipe 6.

[0047] When the air inlet pipe 6 provided by the present invention is used, the air inlet pipe 6 is connected to a vacuum pumping device, and the inner cylinder 25 is vacuumed by opening the air inlet valve 61 to meet the mixing conditions of the raw materials.

[0048] Working principle: first weigh the polysiloxane ring mixture according to the amount and put it into the reactor, heat it to 60℃, and vacuum it and stir it, and remove the water by negative pressure vacuuming; then add acid catalyst or base catalyst, slowly add H2O, and then start to keep warm and stir for about 5 hours to open the DMC ring body and connect the hydroxyl group, and then neutralize it by cooling or heat it to make the base catalyst ineffective, so that the pH value of the material returns to neutral; complete the above steps to obtain product A; put the material back into the reactor, turn on the heating to 150℃, and at the same time connect to vacuum, start decompression and denitrification, and keep it for 3 hours. After completion, the obtained material A1 is filled with nitrogen and sealed for storage and cooling; the cooled material A1 is placed in the reactor, and Add butanone oxime, stir for 10 minutes, then add a capping agent (methyltrimethoxysilane, methyldimethoxysilane, methyl orthosilicate), and purge with nitrogen and stir; after completion, alkoxy-terminated product A2 is obtained; after product A2 returns to room temperature, add silane additives, a leveling agent, and a defoamer, purge with nitrogen and stir for 30 minutes, and after stirring is complete, add a tackifier and stir for 30 minutes, and finally add a catalyst and stir for 30 minutes to obtain the finished conformal coating. By synthesizing a low-molecular-weight alkoxy silicone oil from the synthesis end, replacing the traditional dilution method using organic solvents, and then preparing a solvent-free silicone conformal coating by adding additives, catalysts, and other components, the method complies with national environmental protection policies and reduces processing costs. During the stirring process, the second motor 5 is turned on to drive the rotating rod 51 to rotate, and the rotating rod 51 drives the stirring paddle 52 to rotate. The stirring paddle 52 fully stirs the raw materials. When the rotating rod 51 rotates, the U-shaped scraper 53 is driven to rotate. The U-shaped scraper 53 scrapes the raw materials on the inner wall of the inner cylinder 25 to prevent the raw materials from adhering to the inner wall of the inner cylinder 25, which is inconvenient to clean. In addition, the U-shaped scraper 53 expands the stirring area. At the same time, the first motor 35 is turned on, driving the rotating shaft to rotate. This, in turn, drives the elliptical block 34 to rotate. Due to the shape of the elliptical block 34, the elliptical block 34 intermittently pushes the mounting plate 3 upward. Then, under the action of gravity and the elastic force of the spring 32, the mounting plate 3 quickly returns to its original position, causing a vibration. As the elliptical block 34 continues to rotate, the mounting plate 3 drives the outer cylinder 2 to vibrate back and forth. This vibration eliminates air holes between the raw materials, solving the problem of air holes reducing the quality of the solvent-free conformal coating. During the feeding process of the feed hopper 4, the pressure sensor 42 detects the quality of the raw materials in the feed hopper 4 in real time. After the raw materials reach the set quality value, the signal is transmitted to the computer program through the pressure sensor 42. The computer program issues an alarm and stops feeding. At the same time, the electric push rod 43 is controlled by the computer program. The electric push rod 43 is turned on, driving the rack 44 to move, and the rack 44 drives the gear 45 to rotate. The gear 45 drives the rotating shaft and the sealing plate 41 to rotate, and the sealing plate 41 releases the blockage of the feed hopper 4, and the raw materials fall into the inner cylinder 25. Then, under the action of the electric push rod 43, the sealing plate 41 rotates to horizontally block the feed hopper 4, realizing the function of automatic quantitative control of feeding.

[0049] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a solvent-free conformal coating, characterized in that: The preparation method comprises the following steps: S1: First, weigh the polysiloxane ring mixture (i.e., DMC) according to the amount and place it in a reaction kettle, heat it to 60-90°C, and vacuum it and stir it to remove the water by vacuuming it under negative pressure; then add an acid catalyst or a base catalyst, slowly add H2O, and then start to keep warm and stir for about 5 hours to open the DMC ring and connect the hydroxyl group, and then neutralize it by cooling it down or make the base catalyst ineffective by heating it up, so that the pH value of the material returns to neutral; complete the above steps to obtain product A; S2: Put the materials back into the reactor, turn on the heating to 150-200°C, and simultaneously connect to the vacuum, start the decompression and degassing, and keep it for 3-5 hours. After completion, the obtained material A1 is filled with nitrogen, sealed, stored and cooled; S3: placing the cooled material A1 into a reaction kettle, adding butanone oxime, stirring for 10 minutes, then adding a capping agent, filling with nitrogen and stirring; after completion, an alkoxy-terminated product A2 is obtained; S4: After the product A2 returns to room temperature, add silane additives, leveling agents, and defoaming agents, fill with nitrogen and start stirring for 30 minutes. After the stirring is completed, add the tackifier and stir for 30 minutes. Finally, add the catalyst and stir for 30 minutes to obtain the three-proof paint product.

2. The method for preparing a solvent-free conformal coating according to claim 1, characterized in that: In S1, the solvent-free conformal coating comprises the following raw materials in terms of mass percentage: DMC: 95-99.5%; H2O: 0.5~5%.

3. The method for preparing a solvent-free conformal coating according to claim 2, characterized in that: In S3, the solvent-free conformal coating comprises the following raw materials in terms of mass percentage: A1 product: 90-96%; Butanone oxime: 0.5-2%; Main resin: 1-5%; The main resin includes any one or two of methyltrimethoxysilane, methyldimethoxysilane and methyl orthosilicate.

4. The method for preparing a solvent-free conformal coating according to claim 3, characterized in that: In S4, the solvent-free conformal coating comprises the following raw materials in terms of mass percentage: A2 product: 85-95%; Methyl silicone oil: 10-15%; Silane additives: 1-3%; Leveling agent: 0.1~0.5%; Defoaming agent: 0.1~0.5%; Thickener: 0.1-0.5%; Catalyst: 0.2-5%; The silane auxiliary agent includes methyltrimethoxysilane and methyltrihexyloxysilane, the adhesion promoter includes epoxysilane and aminosilane polar group substances, and the catalyst includes organic tin and titanate.

5. A solvent-free conformal coating preparation device, applicable to the solvent-free conformal coating preparation method according to claims 1 to 4, characterized in that: The solvent-free conformal paint is stirred by a stirring mechanism, and the stirring mechanism comprises: Base (1); Four pillars (31) fixedly connected to the top of the base (1); A mounting plate (3) slidably connected to the four pillars (31); An outer cylinder (2) fixedly connected to a mounting plate (3); A second motor (5) is fixedly connected to the top of the outer cylinder (2), and an output shaft of the second motor (5) extends into the interior of the outer cylinder (2) and is fixedly connected to a rotating rod (51); a plurality of stirring paddles (52) are fixedly connected to the rotating rod (51); a U-shaped scraper (53) is fixedly connected to the bottom of the rotating rod (51), and the U-shaped scraper (53) is in contact with the inner wall of the inner cylinder (25); a discharge pipe (21) is connected and fixedly connected to the bottom of the outer cylinder (2), and a control valve (22) is installed on the discharge pipe (21); The outer sides of the pillars (31) are sleeved with springs (32), and the two ends of the springs (32) are respectively fixedly connected to the bottom of the mounting plate (3) and the top of the base (1); the two ends of the top of the base (1) are fixedly connected to two fixing plates (33); an elliptical block (34) is rotatably connected between the two fixing plates (33) via a rotating shaft; and a first motor (35) is fixedly connected to the two fixing plates (33) on the same side, and the output shaft of the first motor (35) is fixedly connected to one end of the rotating shaft.

6. The device for preparing a solvent-free conformal coating according to claim 5, characterized in that: A vacuum chamber (23) is provided inside the outer cylinder (2), an inner cylinder (25) is fixedly connected to the inner wall of the outer cylinder (2), a heating chamber is formed between the inner cylinder (25) and the outer cylinder (2), and a plurality of heating wires (24) are fixedly connected in the heating chamber.

7. The device for preparing a solvent-free conformal coating according to claim 6, characterized in that: The top of the outer cylinder (2) is connected and fixedly connected to a feed hopper (4), the bottom of the feed hopper (4) is rotatably connected to a sealing plate (41) via a rotating shaft, and the bottom of the sealing plate (41) is fixedly connected to a pressure sensor (42); one end of the rotating shaft extends to the outside of the feed hopper (4) and is fixedly connected to a gear (45); an electric push rod (43) is fixedly connected to the outer wall of the feed hopper (4), the output end of the electric push rod (43) is fixedly connected to a rack (44), and the rack (44) is meshed with the gear (45); a sliding opening (46) is provided on the rack (44); two limit blocks (47) are fixedly connected to the outer wall of the feed hopper (4), and the limit blocks (47) both slide in the sliding opening (46).

8. The device for preparing a solvent-free conformal coating according to claim 7, characterized in that: The top of the outer cylinder (2) is hollowed out and fixedly connected with a filter plate (71), and the filter plate (71) is an activated carbon plate; the top of the outer cylinder (2) is fixedly connected with an exhaust pipe (7); the exhaust pipe (7) is arranged outside the filter plate (71) and is equipped with an exhaust valve (72).

9. The device for preparing a solvent-free conformal coating according to claim 8, characterized in that: The top of the outer cylinder (2) is connected and fixedly connected to a water inlet pipe (8), and a plugging head (82) is installed on the water inlet pipe (8).

10. The device for preparing a solvent-free conformal coating according to claim 9, characterized in that: The top of the outer cylinder (2) is connected and fixedly connected to an air intake pipe (6), and an air intake valve (61) is installed on the air intake pipe (6).

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