Preparation device and method of water-based mosquito repellent coating

Abstract

The application relates to the technical field of paint preparation, in particular to a water-based mosquito-proof paint preparation device and method, which comprises a rack assembly including a bearing table, a dispersion driving assembly including a shaft rod arranged below the bearing table, a shearing dispersion assembly including a mounting frame arranged on the outer wall of the shaft rod, a vertical rod arranged at the end of the mounting frame, a stirring paddle arranged at the end of the vertical rod and a threaded sliding groove arranged on the outer surface of the vertical rod, a circumferential backflow assembly including a push plate arranged on the outer periphery of the shaft rod, a sliding sleeve arranged on the outer surface of the shaft rod and a connecting rod arranged between the sliding sleeve and the push plate, a composite transmission assembly including an outer cylinder arranged at the bottom of the bearing table, a guide sliding groove arranged on the inner wall of the outer cylinder, a lifting cylinder arranged on the outer surface of the shaft rod and located in the inner part of the outer cylinder and a positioning sliding block arranged on the outer wall of the lifting cylinder, and the positioning sliding block is located in the inner part of the guide sliding groove; the components are matched to form a composite dispersion flow field, and the dispersion uniformity of the water-based mosquito-proof paint slurry is improved.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, and in particular to an apparatus and method for preparing a water-based mosquito repellent coating. Background Technology

[0002] Water-based interior wall coatings, using water as the main dispersion medium, offer advantages such as low odor, low volatility, easy application, and environmental friendliness, and have been widely used in the field of building interior wall decoration. With increasing demands for healthier and more functional living environments, water-based coatings that also possess insect-repellent properties are gaining attention, in addition to meeting conventional performance requirements such as hiding power, washability, workability, and film-forming properties.

[0003] Existing water-based insect repellent coatings typically incorporate insect-repellent components, such as polycyclic aromatic hydrocarbon (PAH) insect repellent powders, plant-based insect repellent liquids, or other repellent active substances, into a water-based emulsion, pigment, filler, and additive system. This allows the coating film to release or exhibit a certain insect-repellent function after film formation. However, these functional coatings cannot achieve stable effects simply through mixing; their preparation process still presents numerous technological challenges.

[0004] On the one hand, polycyclic aromatic ester insect repellent powders are functional powder components, which are prone to problems such as insufficient wetting, agglomeration, sedimentation or local enrichment in aqueous systems. On the other hand, there are certain compatibility differences between plant-based insect repellent liquids and aqueous emulsion systems. If the dispersion is insufficient, it is easy to cause uneven distribution of insect repellent active components in the coating, resulting in differences in the mosquito repellent effect in different areas of the final coating film.

[0005] In addition, water-based mosquito repellent coatings usually contain pigments and fillers such as titanium dioxide, kaolin, and heavy calcium carbonate. The addition of these pigments and fillers will significantly increase the solid content and slurry viscosity of the system. During the dispersion process, the powder is prone to agglomeration, wall adhesion, and deposition, especially in the peripheral and bottom areas of the barrel. Traditional single rotary stirring structures are difficult to form sufficient reflux and axial exchange, which makes it difficult for materials near the barrel wall to enter the central shear zone in time, thus affecting the fineness, stability, and uniformity of functional component distribution.

[0006] Existing coating preparation equipment mostly adopts fixed stirring paddles, dispersion discs, or single-shaft stirring structures, which mainly rely on rotational motion in one direction to achieve mixing and dispersion. Although such equipment can meet the basic stirring requirements of ordinary water-based coatings, it is often difficult to simultaneously meet the requirements of powder shearing and breaking, axial turning, peripheral reflux, and low-shear compounding of emulsions when processing water-based mosquito repellent coatings containing functional insect repellent powders, plant-based insect repellent liquids, and various pigments and fillers.

[0007] If the stirring speed is increased to enhance the dispersion effect, it is easy to cause excessive shearing of the later added components such as odor-neutralizing emulsion and plant-based insect repellent, affecting the stability of the emulsion, film-forming performance and the effectiveness of functional components; if the stirring intensity is reduced, it is difficult to fully disperse the powder agglomerates containing polycyclic aromatic ester insect repellent powder, titanium dioxide, kaolin and heavy calcium carbonate, resulting in substandard coating fineness, decreased storage stability or uneven insect repellent effect.

[0008] Therefore, how to provide an apparatus and method suitable for the preparation of water-based insect repellent coatings, enabling central shearing, vertical folding, peripheral reflux, and staged compounding in the same equipment, thereby improving the dispersion and refinement of insect repellent powders and pigments while reducing the risk of excessive shearing of emulsions and plant-based insect repellent liquids, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] In view of the problems in the above or existing technologies that make it difficult to simultaneously meet the requirements of powder shearing and agglomeration, axial material turning, peripheral reflux and low-shear emulsion compounding, the present invention is proposed.

[0010] Therefore, the purpose of this invention is to provide an apparatus and method for preparing a water-based mosquito repellent coating.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0012] An apparatus for preparing a water-based mosquito repellent coating, comprising:

[0013] Rack assembly, including the support platform;

[0014] A distributed drive assembly includes a shaft disposed below the support platform;

[0015] The shearing and dispersing assembly includes a mounting bracket disposed on the outer wall of the shaft, a vertical rod disposed at the end of the mounting bracket, a stirring paddle disposed at the end of the vertical rod, and a threaded groove disposed on the outer surface of the vertical rod.

[0016] The peripheral return assembly includes a push plate disposed on the outer periphery of the shaft, a sliding sleeve disposed on the outer surface of the shaft, and a connecting rod disposed between the sliding sleeve and the push plate;

[0017] The composite transmission assembly includes an outer cylinder disposed at the bottom of the support platform, a guide groove disposed on the inner wall of the outer cylinder, a lifting cylinder disposed on the outer surface of the shaft and located inside the outer cylinder, and a positioning slider disposed on the outer wall of the lifting cylinder, wherein the positioning slider is located inside the guide groove.

[0018] The lifting cylinder reciprocates by rotating the shaft, the upright rotates by a threaded groove as the lifting cylinder rises and falls, and the sliding sleeve drives the push plate to move radially by a connecting rod as the lifting cylinder rises and falls.

[0019] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, the frame assembly further includes a lifting frame disposed at the rear end of the support platform, a support frame disposed at the rear end of the lifting frame, and a base disposed at the bottom of the support frame, wherein the lifting frame and the support frame are slidably connected vertically.

[0020] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, a telescopic cylinder is installed on the top of the support frame, the telescopic end of the telescopic cylinder is connected to the lifting frame, a guide rail is provided on the side wall of the support frame, and the lifting frame is slidably connected to the support frame through the guide rail.

[0021] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, the dispersion drive assembly further includes a material cylinder disposed below the support platform and a motor disposed on the top of the support platform, the stirring paddle and the push plate are both located inside the material cylinder, and the output shaft of the motor is connected to the shaft rod.

[0022] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, the end of the mounting frame is provided with a sleeve hole for the upright to pass through, the inner wall of the sleeve hole is provided with a limiting slider, the limiting slider is located inside the threaded groove and is slidably connected, both ends of the threaded groove are connected with a straight groove, the outer wall of the end of the lifting cylinder is provided with a connecting frame, and the top end of the upright is rotatably connected to the connecting frame.

[0023] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, a support rod is provided between the push plate and the outer wall of the shaft, and at least two support rods are provided and distributed in parallel, and both ends of the support rod and the connecting rod are rotatably connected.

[0024] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, a fixing rod is provided between the top of the sliding sleeve and the lifting cylinder, the cross-section of the push plate is a "T" shaped profile, and the end of the push plate is provided with an arc bend.

[0025] In a preferred embodiment of the apparatus for preparing the water-based mosquito repellent coating of the present invention, the lifting cylinder and the shaft are connected by a sliding connection, the guide groove is composed of two semi-circular grooves and two oblique arc grooves, the two semi-circular grooves are respectively arranged in the upper and lower sections of the outer cylinder and distributed on both sides of the outer cylinder, and the two oblique arc grooves are respectively connected between the ends of the two semi-circular grooves.

[0026] A method for preparing a water-based mosquito repellent coating, using an apparatus for preparing water-based mosquito repellent coatings, includes the following steps:

[0027] Pre-dispersion of base liquid: Add 200-300 parts of deionized water to the barrel, along with 6-10 parts of dispersant, 1-2 parts of wetting agent, 3-5 parts of defoamer, and 8-12 parts of humectant. Place the barrel directly below the support platform, activate the telescopic cylinder to lower the stirring paddle and push plate below the liquid surface, and start the motor to drive the shaft to rotate at a speed of 600-800 rpm to form a basic dispersion of the liquid phase components.

[0028] Cellulose activation: Add 2-4 parts of cellulose to the basic dispersion, increase the shaft speed to 1000-1200 rpm and disperse for 10-20 minutes. The shaft drives the upright and push plate to make circular motion. The lifting cylinder forms periodic lifting and lowering through the guide groove. The upright moves up and down with the lifting cylinder and rotates through the threaded groove. The stirring paddle tumbles and shears the cellulose until there are no obvious particles in the system and a pre-thickened slurry is formed.

[0029] Insect repellent component composite dispersion: Add 150-250 parts of polycyclic aromatic ester insect repellent powder and 5-10 parts of plant-based insect repellent liquid to the pre-thickened slurry. Control the stirring paddle to rotate and shear in the middle of the lifting section, and fold and mix in the high and low sections to disperse and coat the polycyclic aromatic ester insect repellent powder in the pre-thickened slurry. The plant-based insect repellent liquid is uniformly introduced into the aqueous continuous phase to form a powder-liquid composite insect repellent dispersion system.

[0030] Pigment and filler fine dispersion: Add 100-200 parts of titanium dioxide, 50-100 parts of 4000 mesh kaolin, 100-200 parts of 2000 mesh heavy calcium carbonate and 2-5 parts of multifunctional regulator to the powder-liquid composite insect repellent dispersion system in sequence, and disperse at high speed for 30 minutes. During this process, the sliding sleeve moves up and down with the lifting cylinder and drives the push plate to reciprocate radially through the connecting rod. This causes the high solids content slurry at the periphery of the cylinder to be periodically pushed towards the central shear zone. The stirring paddle simultaneously performs axial tumbling and self-rotation shearing until the fineness of the system is less than 20 μm, thus obtaining a refined slurry.

[0031] Emulsion film-forming compounding and post-adjustment: Add 200-300 parts of odor-neutralizing emulsion and 10-15 parts of odor-neutralizing film-forming aid to the refined slurry, reduce the shear strength and continue mixing to ensure uniform compounding of emulsion particles, insect repellent components and pigments and fillers. Then add 2-4 parts of thickener and 2-5 parts of bactericide, adjust the pH value to 8.5-9, and control the viscosity at around 105 KU. After passing the test, filter and package to obtain water-based mosquito repellent coating.

[0032] In a preferred embodiment of the preparation method of the water-based mosquito repellent coating of the present invention, the spiral directions of the threaded grooves on adjacent uprights are opposite, so that adjacent stirring paddles rotate in opposite directions during the lifting and lowering process. The push plate opens and closes radially under the drive of the sliding sleeve and connecting rod, so as to periodically push the polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid and pigments and fillers near the inner wall of the barrel towards the central shear zone, thereby forming a composite dispersion flow field and improving the uniformity of the distribution of insect repellent active components in the water-based coating.

[0033] The beneficial effects of the apparatus and method for preparing the water-based mosquito repellent coating of the present invention are as follows:

[0034] This invention, through the cooperation of a dispersion driving component, a shear dispersion component, a peripheral reflux component, and a composite transmission component, transforms the rotational motion of the shaft into the circumferential motion, axial lifting motion, self-rotating shearing motion, and radial reciprocating motion of the pusher, thereby forming a composite dispersion flow field in the barrel and improving the dispersion uniformity of the water-based mosquito repellent coating slurry.

[0035] This invention utilizes the lifting and rotating shearing of the stirring paddle to fully wet, shear, break up, and finely disperse powders containing polycyclic aromatic esters, titanium dioxide, kaolin, and heavy calcium carbonate, which helps to control the fineness of the system to less than 20 μm.

[0036] This invention uses the radial reciprocating motion of the pusher plate to periodically push the high solids content slurry from the periphery and near the barrel wall to the central shear zone, reducing powder adhesion, deposition and local agglomeration, and improving the uniformity of distribution of insect repellent components and pigments.

[0037] This invention employs a staged feeding and dispersion process, first dispersing the liquid phase additives and powder components, and then adding the deodorizing emulsion and film-forming aids for compounding. This approach can balance powder dispersion efficiency and emulsion film-forming stability, reducing the risk of the emulsion being affected by excessive shearing. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the overall structure of the preparation device and method for water-based mosquito repellent coating.

[0040] Figure 2 A schematic diagram of the composite transmission component structure for the preparation device and method of water-based mosquito repellent coating.

[0041] Figure 3A schematic diagram of the shear dispersion component structure of the preparation apparatus and method for water-based mosquito repellent coatings.

[0042] Figure 4 A schematic diagram of the peripheral reflux component structure of the preparation device and method for water-based mosquito repellent coating.

[0043] Figure 5 A schematic diagram of the outer cylinder structure of the preparation device and method for water-based mosquito repellent coating.

[0044] Figure 6 This is an enlarged schematic diagram at point A showing the preparation apparatus and method for water-based mosquito repellent coatings.

[0045] In the diagram: 1. Frame assembly; 11. Base; 12. Support frame; 13. Bearing platform; 14. Lifting frame; 15. Guide rail; 16. Telescopic cylinder; 2. Dispersion drive assembly; 21. Material cylinder; 22. Shaft; 23. Motor; 3. Shearing and dispersing assembly; 31. Vertical pole; 32. Agitator; 33. Connecting frame; 34. Mounting frame; 35. Threaded groove; 36. Straight groove; 37. Sleeve hole; 38. Limiting slider; 4. Peripheral reflux assembly; 41. Push plate; 42. Support rod; 43. Connecting rod; 44. Sliding sleeve; 45. Fixed rod; 5. Composite transmission assembly; 51. Outer cylinder; 52. Guide groove; 53. Lifting cylinder; 54. Positioning slider. Detailed Implementation

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0047] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0048] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0049] Example 1, referring to Figures 1 to 6 This is the first embodiment of the present invention. This embodiment provides a device for preparing a water-based mosquito repellent coating, which includes a frame assembly 1, a dispersion driving assembly 2, a shear dispersion assembly 3, a peripheral reflux assembly 4, and a composite transmission assembly 5.

[0050] Specifically, the frame assembly 1 includes a support platform 13, which is used to support the dispersion drive assembly 2, the shear dispersion assembly 3, the peripheral reflux assembly 4, and the composite transmission assembly 5, and drives the above-mentioned components to rise and fall relative to the barrel 21, so that the stirring paddle 32 and the pusher plate 41 can enter or exit the barrel 21 when preparing water-based mosquito repellent coating.

[0051] The dispersion drive assembly 2 includes a shaft 22 disposed below the support platform 13. The shaft 22 serves as a power output component, used to drive the shear dispersion assembly 3 and the peripheral reflux assembly 4 to move within the material cylinder 21, thereby forming a rotating dispersion flow field of the coating slurry.

[0052] For water-based mosquito repellent coatings, the system contains components such as polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid, titanium dioxide, kaolin, heavy calcium carbonate, and odor-neutralizing emulsion. The slurry has a certain solid content, and the functional insect repellent components and pigments and fillers need to be fully dispersed. Therefore, the rotation of shaft 22 can provide the basic power for subsequent powder wetting, shearing and breaking of agglomerates, slurry homogenization and emulsion compounding.

[0053] The shearing and dispersing assembly 3 includes a mounting frame 34 disposed on the outer wall of the shaft 22, a vertical rod 31 disposed at the end of the mounting frame 34, an agitator 32 disposed at the end of the vertical rod 31, and a threaded groove 35 disposed on the outer surface of the vertical rod 31. When the shaft 22 rotates, the mounting frame 34 drives the vertical rod 31 to make a circular motion around the shaft 22. The agitator 32 forms a circumferential agitation in the material cylinder 21 along with the vertical rod 31. Since the threaded groove 35 is disposed on the outer surface of the vertical rod 31, the vertical rod 31 can generate a self-rotation when it moves up and down with the lifting cylinder 53, so that the agitator 32 can generate a self-rotation shearing action in addition to the circular motion and axial lifting motion.

[0054] The peripheral recirculation assembly 4 includes a push plate 41 disposed on the outer periphery of the shaft 22, a sliding sleeve 44 disposed on the outer surface of the shaft 22, and a connecting rod 43 disposed between the sliding sleeve 44 and the push plate 41. The push plate 41 can move in a circular motion with the shaft 22, and at the same time, it can move in a radial reciprocating motion driven by the sliding sleeve 44 and the connecting rod 43.

[0055] For water-based coating slurries, titanium dioxide, kaolin, heavy calcium carbonate and insect repellent powder containing polycyclic aromatic esters tend to accumulate or adhere to the inner wall of the barrel 21 during the dispersion process. The radial movement of the pusher plate 41 can periodically push the high solids content slurry in the peripheral area of ​​the barrel 21 towards the central shear area, thereby reducing powder agglomeration, barrel wall deposition and local enrichment of insect repellent components.

[0056] The composite transmission assembly 5 includes an outer cylinder 51 disposed at the bottom of the support platform 13, a guide groove 52 disposed on the inner wall of the outer cylinder 51, a lifting cylinder 53 disposed on the outer surface of the shaft 22 and located inside the outer cylinder 51, and a positioning slider 54 disposed on the outer wall of the lifting cylinder 53. The positioning slider 54 is located inside the guide groove 52. When the shaft 22 rotates, the lifting cylinder 53 rotates synchronously with the shaft 22, and the positioning slider 54 moves along the guide groove 52. Since the guide groove 52 has a undulating path, the lifting cylinder 53 forms a reciprocating lifting motion during rotation. The lifting of the lifting cylinder 53 drives the upright 31 and the stirring paddle 32 to move up and down on the one hand, and drives the sliding sleeve 44 to move up and down on the other hand, thereby driving the push plate 41 to move radially reciprocatingly through the connecting rod 43.

[0057] Thus, the single rotational input of the shaft 22 can be simultaneously converted into the circular motion, axial lifting motion, and rotational shearing motion of the agitator 32, as well as the circular motion and radial reciprocating motion of the pusher plate 41, so that a composite dispersion flow field with central shearing, up-and-down folding and peripheral backflow is formed in the barrel 21.

[0058] The composite dispersion flow field is particularly suitable for the uniform compounding of functional insect repellent powders, plant-based insect repellent liquids, pigments, fillers and emulsion systems in water-based mosquito repellent coatings. It helps to improve the uniformity of the distribution of insect repellent active components in the coating and reduce the risk of sedimentation and wall adhesion of high solids slurry during the preparation process.

[0059] This invention, through the cooperation of the frame assembly 1, the dispersion drive assembly 2, the shear dispersion assembly 3, the peripheral reflux assembly 4, and the composite transmission assembly 5, transforms the rotational motion of the shaft 22 into the circular motion, axial lifting motion, rotational shearing motion of the stirring paddle 32, and the radial reciprocating motion of the pusher plate 41. This forms a composite dispersion flow field in the barrel 21 that combines central shearing, up-and-down folding, and peripheral reflux, which can better meet the dispersion requirements of high solids content, multiple powders, and multifunctional components in water-based mosquito repellent coatings.

[0060] The present invention, through the cooperation of the lifting cylinder 53, the positioning slider 54 and the guide groove 52, enables the stirring paddle 32 to form a periodic lifting and lowering during rotation, thereby realizing the axial tumbling and interlayer exchange of the slurry. Compared with the single rotation stirring method, it can effectively reduce the dispersion difference between the bottom and the top of the material cylinder 21, and make the distribution of polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid, titanium dioxide, kaolin and heavy calcium carbonate in the system more uniform.

[0061] This invention utilizes the cooperation between the threaded groove 35 and the limiting slider 38 to cause the upright rod 31 to rotate during the lifting process, thereby enhancing the shearing and breaking ability of the insect repellent powder containing polycyclic aromatic esters and pigments and fillers. Especially in the stages of cellulose activation, composite dispersion of insect repellent components and pigment and filler refinement, the rotation and shearing of the stirring paddle 32 can promote powder wetting, deagglomeration and refinement, which is beneficial to controlling the fineness of the system to less than 20μm and improving the fineness and storage stability of water-based insect repellent coatings.

[0062] The present invention utilizes the cooperation of the sliding sleeve 44, the connecting rod 43 and the push plate 41 to make the push plate 41 generate radial reciprocating motion while moving in a circular motion, periodically pushing the high solids content slurry in the peripheral area of ​​the barrel 21 and near the barrel wall to the central shear zone. This can reduce the adhesion, deposition and local agglomeration of polycyclic aromatic ester insect repellent powder, titanium dioxide, kaolin and heavy calcium near the barrel wall, and improve the powder utilization rate and dispersion uniformity.

[0063] The radial backflow effect of the pusher plate 41 of the present invention can improve the spatial distribution of plant-based insect repellent liquid and polycyclic aromatic ester insect repellent powder in the aqueous system, making it less likely for the insect repellent active components to accumulate or settle in local areas. As a result, the insect repellent active components can be more evenly distributed in the coating film after film formation, which is beneficial to improving the consistency and durability of the mosquito repellent effect.

[0064] Example 2, refer to Figures 1 to 6 This is the second embodiment of the present invention. Unlike the previous embodiment, this embodiment provides the specific structure of the apparatus for preparing water-based mosquito repellent coating.

[0065] Specifically, the frame assembly 1 also includes a lifting frame 14 disposed at the rear end of the support platform 13, a support frame 12 disposed at the rear end of the lifting frame 14, and a base 11 disposed at the bottom of the support frame 12. The lifting frame 14 and the support frame 12 are slidably connected vertically. The support frame 12 is used to provide vertical support, the base 11 is used to improve the overall stability of the machine, and the lifting frame 14 is used to drive the support platform 13 to rise and fall.

[0066] A telescopic cylinder 16 is installed on the top of the support frame 12. The telescopic end of the telescopic cylinder 16 is connected to the lifting frame 14. A guide rail 15 is provided on the side wall of the support frame 12. The lifting frame 14 is slidably connected to the support frame 12 through the guide rail 15. When preparing water-based mosquito repellent coating, the telescopic cylinder 16 extends and drives the lifting frame 14 to descend along the guide rail 15, so that the bearing platform 13 drives the stirring paddle 32 and the push plate 41 into the material cylinder 21. After dispersion, the telescopic cylinder 16 retracts and drives the lifting frame 14 to rise along the guide rail 15, so that the stirring paddle 32 and the push plate 41 exit the material cylinder 21, making it easy to remove the material cylinder 21 and filter and package it.

[0067] The dispersion drive assembly 2 also includes a material cylinder 21 disposed below the support platform 13 and a motor 23 disposed on the top of the support platform 13. The stirring paddle 32 and the pusher plate 41 are both located inside the material cylinder 21. The output shaft of the motor 23 is connected to the shaft 22. The material cylinder 21 is used to contain liquid raw materials, functional insect repellent components, pigments and fillers, emulsions and post-additional additives in the preparation process of water-based mosquito repellent coating. The motor 23 is used to drive the shaft 22 to rotate, thereby providing power for the entire composite dispersion process.

[0068] The mounting bracket 34 has a sleeve hole 37 at its end for the upright 31 to pass through. The inner wall of the sleeve hole 37 is provided with a limiting slider 38, which is located inside the threaded groove 35 and is slidably connected. Both ends of the threaded groove 35 are connected with straight grooves 36. The outer wall of the end of the lifting cylinder 53 is provided with a connecting bracket 33, and the top of the upright 31 is rotatably connected to the connecting bracket 33.

[0069] When the lifting cylinder 53 drives the connecting frame 33 to move up and down, the connecting frame 33 drives the upright 31 to move up and down. During the up and down movement of the upright 31, the limiting slider 38 cooperates with the threaded groove 35, causing the upright 31 to passively rotate, thereby driving the stirring paddle 32 to rotate and shear.

[0070] The linear chute 36 reduces or eliminates the rotation of the upright 31 during the high and low lifting sections, allowing the agitator 32 to achieve different dispersion effects at different heights: in the middle section, it shears and breaks up the polycyclic aromatic hydrocarbon insect repellent powder, titanium dioxide, kaolin, and heavy calcium carbonate; in the high and low sections, it folds and mixes the slurry. This motion method balances powder refinement and system stability, avoiding excessive shearing effects on the subsequently added neutralizing emulsion and plant-based insect repellent.

[0071] A support rod 42 is provided between the push plate 41 and the outer wall of the shaft 22. At least two support rods 42 are provided and distributed in parallel. Both ends of the support rod 42 and the connecting rod 43 are rotatably connected. A fixing rod 45 is provided between the top of the sliding sleeve 44 and the lifting cylinder 53. The cross-section of the push plate 41 is a "T" shaped profile. The end of the push plate 41 is provided with an arc bend. When the lifting cylinder 53 moves up and down, the fixed rod 45 drives the sliding sleeve 44 to move up and down along the shaft 22. The sliding sleeve 44 then pushes and pulls the push plate 41 through the connecting rod 43, so that the push plate 41 generates radial reciprocating motion in the material cylinder 21. The "T" shaped profile of the push plate 41 is conducive to improving the structural stability when pushing the slurry. The arc bend can reduce the local impact of the end of the push plate 41 on the slurry, making it more suitable for pushing the high solids content coating slurry back.

[0072] The lifting cylinder 53 and the shaft 22 are connected by a sliding connection. The guide groove 52 consists of two semi-circular grooves and two oblique arc grooves. The two semi-circular grooves are respectively set on the upper and lower sections of the outer cylinder 51 and distributed on both sides of the outer cylinder 51. The two oblique arc grooves are respectively connected between the ends of the two semi-circular grooves. The guide groove 52 enables the positioning slider 54 to move along a preset trajectory during the rotation of the shaft 22, thereby making the lifting cylinder 53 form a stable periodic lifting.

[0073] When in use, place the material cylinder 21 directly below the support platform 13. The telescopic cylinder 16 drives the lifting frame 14 to descend, so that the stirring paddle 32 and the push plate 41 enter the material cylinder 21. After starting the motor 23, the shaft 22 rotates and drives the mounting frame 34, the upright 31, the stirring paddle 32, the support rod 42 and the push plate 41 to perform circular motion.

[0074] Meanwhile, the lifting cylinder 53 moves along the guide groove 52 via the positioning slider 54, forming a reciprocating up and down movement during rotation. The lifting of the lifting cylinder 53 drives the upright 31 to rise and fall via the connecting frame 33, causing the upright 31 to rotate under the cooperation of the threaded groove 35 and the limiting slider 38.

[0075] The lifting cylinder 53 also drives the sliding sleeve 44 to rise and fall through the fixed rod 45. The sliding sleeve 44 drives the push plate 41 to reciprocate radially through the connecting rod 43. Thus, the water-based mosquito repellent coating slurry in the material cylinder 21 can be subjected to circumferential stirring, up-and-down turning, shearing dispersion and peripheral backflow at the same time.

[0076] In summary, the device in this embodiment, without adding an additional power source, transforms the rotational motion of the shaft 22 into a multidimensional composite dispersion motion through the composite transmission component 5, enabling it to meet the process requirements of powder wetting, insect repellent component homogenization, pigment and filler refinement, and emulsion compounding in the preparation of water-based mosquito repellent coatings.

[0077] Example 3 is the third embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a method for preparing water-based mosquito repellent coating using the above-described preparation apparatus.

[0078] Specifically, water-based mosquito repellent coatings include deionized water, dispersants, wetting agents, defoamers, humectants, cellulose, polycyclic aromatic ester-containing insect repellent powder, plant-based insect repellent liquid, titanium dioxide, 4000-mesh kaolin, 2000-mesh heavy calcium carbonate, multifunctional regulators, odor-neutralizing emulsions, odor-neutralizing film-forming aids, thickeners, and bactericides.

[0079] The specific preparation steps are as follows:

[0080] Step 1: Pre-dispersion of base liquid.

[0081] Add 200-300 parts of deionized water to the barrel 21, and then add 6-10 parts of dispersant, 1-2 parts of wetting agent, 3-5 parts of defoamer and 8-12 parts of humectant in sequence. Place the barrel 21 directly below the support platform 13, start the telescopic cylinder 16 to lower the stirring paddle 32 and push plate 41 below the liquid surface in the barrel 21, start the motor 23 to drive the shaft 22 to rotate, and control the speed of the shaft 22 at 600-800 rpm to make the liquid phase additives evenly dispersed in the deionized water to obtain the basic dispersion.

[0082] In this step, the dispersant and wetting agent can improve the wetting ability of the subsequent powder to the aqueous phase, the defoamer is used to reduce foam aggregation during high-speed dispersion, the humectant is used to improve the water retention of the aqueous system, the circular motion of the stirring paddle 32 causes the liquid phase to form an initial circulation, and the radial push of the pusher plate 41 causes the liquid phase near the inner wall of the barrel 21 to be brought back to the central area, thereby improving the pre-dispersion uniformity of the liquid phase additives.

[0083] Step 2: Cellulose activation and thickening.

[0084] Add 2-4 parts of cellulose to the basic dispersion, increase the rotation speed of shaft 22 to 1000-1200 rpm, and disperse for 10-20 minutes until the system is free of obvious particles and forms a pre-thickened slurry.

[0085] In this step, the shaft 22 drives the stirring paddle 32 to move in a circular motion, while the lifting cylinder 53 moves along the guide groove 52 through the positioning slider 54 and forms a periodic lifting and lowering. The upright 31 rises and falls with the lifting cylinder 53 and rotates through the threaded groove 35, so that the stirring paddle 32 can tumble and shear the cellulose.

[0086] The pusher plate 41 reciprocates radially under the action of the sliding sleeve 44 and the connecting rod 43, pushing the cellulose that is not fully wetted in the peripheral area of ​​the barrel 21 toward the central shearing zone.

[0087] Through the aforementioned combined processes, cellulose can be more fully wetted, dispersed, and swollen, reducing cellulose clumping and localized thickening, thus providing a stable slurry base for the subsequent addition of insect repellent powders and pigments.

[0088] Step 3: Disperse the insect repellent components in a compound manner.

[0089] Add 150-250 parts of polycyclic aromatic ester insect repellent powder and 5-10 parts of plant-based insect repellent liquid to the pre-thickened slurry, and continue to disperse so that the polycyclic aromatic ester insect repellent powder and plant-based insect repellent liquid are evenly distributed in the aqueous slurry system to form a powder-liquid composite insect repellent dispersion system.

[0090] In this step, the polycyclic aromatic ester insect repellent powder is a functional powder component. If it is not sufficiently dispersed, it is easy to cause local enrichment and sedimentation, which will affect the uniformity of the insect repellent effect of the subsequent coating. The plant-based insect repellent liquid needs to be uniformly introduced into the aqueous continuous phase to improve the uniformity of the repellent effect after the coating film is formed.

[0091] In the middle section of the lifting process, the stirring paddle 32 generates self-rotation shearing through the cooperation of the threaded slide 35 and the limiting slider 38, which shears and breaks up the polycyclic aromatic ester insect repellent powder. In the high and low sections of the lifting process, the stirring paddle 32 mainly folds and mixes the slurry, which promotes the exchange between the insect repellent powder and the plant-based insect repellent liquid in different liquid layers. The pusher plate 41 pushes the insect repellent powder that may accumulate near the inner wall of the barrel 21 back to the central area, so that it re-enters the shearing and dispersion zone, thereby improving the overall dispersion uniformity of the insect repellent components.

[0092] Step 4: Refine and disperse pigments and fillers.

[0093] Add 100-200 parts of titanium dioxide, 50-100 parts of 4000-mesh kaolin, 100-200 parts of 2000-mesh heavy calcium carbonate, and 2-5 parts of multifunctional regulator to the powder-liquid composite insect repellent dispersion system in sequence, disperse at high speed for 30 minutes until the system fineness is less than 20μm to obtain a refined slurry.

[0094] In this step, titanium dioxide is used to improve the hiding power of the coating, while kaolin and heavy calcium carbonate are used to improve the coating's filling properties, workability, and film skeleton structure.

[0095] Because the addition of pigments and fillers increases the solid content of the system and the viscosity of the slurry, traditional unidirectional stirring is prone to problems such as powder agglomeration, bottom sedimentation and material adhering to the barrel wall.

[0096] In this embodiment, the stirring paddle 32 shears and breaks up clumps in the central region, and the lifting cylinder 53 drives the stirring paddle 32 to move up and down to achieve axial material turning. The push plate 41 opens and closes radially under the drive of the sliding sleeve 44 and the connecting rod 43, periodically pushing the high solids content slurry from the periphery of the material cylinder 21 to the central shearing zone, thereby forming a composite dispersion process of central shearing, peripheral reflux and up and down turning.

[0097] Through this composite dispersion process, polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid, titanium dioxide, kaolin, and heavy calcium carbonate can be synergistically dispersed in the slurry system, reducing the uneven distribution caused by the local embedding or repulsion of functional insect repellent components by pigments and fillers. This results in water-based mosquito repellent coatings having more stable insect repellent function and more uniform coating performance after subsequent film formation.

[0098] Step 5: Emulsion film-forming compounding.

[0099] Add 200-300 parts of odor-neutralizing emulsion and 10-15 parts of odor-neutralizing film-forming aid to the refined slurry, reduce the rotation speed of shaft 22 and continue mixing to uniformly blend the odor-neutralizing emulsion, odor-neutralizing film-forming aid, insect repellent components and pigments and fillers to obtain water-based coating base material.

[0100] In this step, since the deodorized emulsion is the main film-forming component, excessive shear may affect the stability of the emulsion particles. Therefore, after the emulsion is added, the shear strength is reduced so that the stirring paddle 32 mainly performs gentle dispersion and interlayer exchange. At the same time, the radial pushing action of the pusher plate 41 is used to return the slurry from the periphery of the barrel 21 to the central area.

[0101] This approach avoids localized accumulation of the emulsion and reduces the impact of prolonged high shear on emulsion stability and the effectiveness of plant-based insect repellents.

[0102] Step Six: Post-adjustment and obtaining the finished product.

[0103] Add 2-4 parts thickener and 2-5 parts bactericide to the water-based coating base, continue mixing at low speed to ensure uniform distribution of the thickener and complete the final rheological adjustment. Adjust the pH value of the system to about 8.5-9 and control the viscosity to about 105 KU. After passing the test, filter and package to obtain the water-based mosquito repellent coating.

[0104] In this step, the thickener is added later to avoid excessive viscosity caused by premature addition, which would affect the shear dispersion of the insect repellent powder and pigments. The bactericide is used to improve the storage stability of the water-based coating. Finally, through pH and viscosity control, the resulting water-based insect repellent coating meets the requirements for workability, storage, and film formation.

[0105] Through the above steps, this embodiment enables the polycyclic aromatic ester insect repellent powder and plant-based insect repellent liquid in the water-based mosquito repellent coating to form a relatively uniform functional distribution in the water-based emulsion system. At the same time, titanium dioxide, kaolin, and heavy calcium carbonate can be fully wetted and finely dispersed, reducing powder agglomeration and sedimentation. The resulting water-based mosquito repellent coating has good dispersion stability, workability, film-forming properties, and mosquito repellent function.

[0106] Example 4 is the fourth embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a method for preparing a water-based mosquito repellent coating, which is produced using the preparation apparatus described in Example 1 or Example 2. The specific preparation steps are as follows:

[0107] By weight, add 250 parts of deionized water to the barrel 21, start the motor 23 to rotate the shaft 22 at 700 rpm, then add 8 parts of dispersant, 1.5 parts of wetting agent, 4 parts of defoamer and 10 parts of humectant, and disperse until the liquid phase is uniform to obtain the basic dispersion.

[0108] Add 3 parts of cellulose to the basic dispersion, increase the rotation speed of shaft 22 to 1100 rpm, and disperse for 15 minutes. During the dispersion process, the lifting cylinder 53 forms a periodic lifting and lowering through the guide chute 52. The stirring paddle 32 shears and disperses the cellulose during the lifting and lowering process. The pusher plate 41 pushes the slurry that is not fully dispersed at the periphery of the material cylinder 21 to the central area until the system is a uniform slurry without obvious particles.

[0109] Subsequently, 200 parts of polycyclic aromatic ester insect repellent powder and 8 parts of plant-based insect repellent liquid were added and dispersed to ensure that the insect repellent powder was evenly dispersed in the slurry and that the plant-based insect repellent liquid was introduced into the aqueous continuous phase. Then, 150 parts of titanium dioxide, 75 parts of 4000-mesh kaolin, 150 parts of 2000-mesh heavy calcium carbonate and 3 parts of multifunctional regulator were added in sequence and dispersed at high speed for 30 minutes. The fineness of the slurry was tested to be less than 20 μm.

[0110] Then add 250 parts of deodorizing emulsion and 12 parts of deodorizing film-forming aid, reduce the rotation speed and mix thoroughly to ensure that the emulsion and the aforementioned refined slurry are evenly combined.

[0111] Finally, add 3 parts thickener and 3 parts bactericide, adjust the pH value to about 8.5-9, and control the viscosity at about 105KU. After passing the test, filter and package to obtain water-based mosquito repellent coating.

[0112] In this embodiment, the polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid, pigments and fillers, and emulsion are added at different stages, so that high shear dispersion mainly acts on the powder wetting, agglomeration, and refining stages, while the emulsion and film-forming aids are compounded under low shear after the fineness meets the standard, thereby taking into account the powder dispersion efficiency, emulsion stability, and uniform distribution of insect repellent functional components.

[0113] Compared with conventional single stirring methods, the preparation method in this embodiment can reduce material adhering to the barrel wall and local sedimentation, improve the uniformity of the coating slurry, and facilitate the stable performance of the mosquito-repellent effect after film formation.

[0114] This invention employs a phased feeding and dispersion strategy. First, liquid phase additives are pre-dispersed, followed by cellulose activation and thickening. Then, insect repellent powder containing polycyclic aromatic esters and plant-based insect repellent liquid are added to form a powder-liquid composite insect repellent dispersion system. Next, pigments and fillers such as titanium dioxide, kaolin, and heavy calcium carbonate are added for fine dispersion. Finally, a deodorizing emulsion, a deodorizing film-forming aid, a thickener, and a bactericide are added for low-shear compounding and post-adjustment. This process sequence can avoid the premature addition of thickeners or emulsions, which could lead to excessively high system viscosity or emulsion damage, thus balancing dispersion efficiency, film-forming stability, and uniform insect repellent function.

[0115] This invention reduces shear strength during the emulsion film-forming compounding stage and utilizes the radial reflux of the pusher plate 41 and the gentle interlayer exchange of the stirring paddle 32 to achieve uniform compounding of emulsion, film-forming aid, insect repellent components and pigments and fillers. This can reduce the risk of demulsification of the odor-neutralizing emulsion and the volatilization or local enrichment of the effective components of the plant-based insect repellent, which is beneficial to improving the film-forming performance and odor-neutralizing and environmentally friendly performance of the coating.

[0116] This invention controls the pH value to around 8.5-9 and the viscosity to around 105 KU, and filters and packages the product after the fineness is less than 20 μm. This results in a water-based mosquito repellent coating that has good workability, storage stability, hiding power, film-forming properties, and mosquito repellent function, making it suitable for the industrial preparation of functional water-based interior wall coatings.

[0117] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An apparatus for preparing a water-based mosquito repellent coating, characterized in that, include: The rack assembly (1) includes a support platform (13); as well as, The distributed drive assembly (2) includes a shaft (22) disposed below the support platform (13); and, The shearing and dispersing assembly (3) includes a mounting bracket (34) disposed on the outer wall of the shaft (22), a vertical rod (31) disposed at the end of the mounting bracket (34), a stirring paddle (32) disposed at the end of the vertical rod (31), and a threaded groove (35) disposed on the outer surface of the vertical rod (31); and, The peripheral return assembly (4) includes a push plate (41) disposed on the outer periphery of the shaft (22), a sliding sleeve (44) disposed on the outer surface of the shaft (22), and a connecting rod (43) disposed between the sliding sleeve (44) and the push plate (41); and, The composite transmission assembly (5) includes an outer cylinder (51) disposed at the bottom of the support platform (13), a guide groove (52) disposed on the inner wall of the outer cylinder (51), a lifting cylinder (53) disposed on the outer surface of the shaft (22) and located inside the outer cylinder (51), and a positioning slider (54) disposed on the outer wall of the lifting cylinder (53), wherein the positioning slider (54) is located inside the guide groove (52); wherein, The lifting cylinder (53) reciprocates by rotating the shaft (22). The upright (31) rotates by the threaded groove (35) when it rises and falls with the lifting cylinder (53). The sliding sleeve (44) drives the push plate (41) to move radially by the connecting rod (43) when it rises and falls with the lifting cylinder (53).

2. The apparatus for preparing water-based mosquito repellent coating according to claim 1, characterized in that: The frame assembly (1) further includes a lifting frame (14) disposed at the rear end of the support platform (13), a support frame (12) disposed at the rear end of the lifting frame (14), and a base (11) disposed at the bottom of the support frame (12). The lifting frame (14) and the support frame (12) are connected by sliding vertically.

3. The apparatus for preparing water-based mosquito repellent coating according to claim 2, characterized in that: A telescopic cylinder (16) is installed on the top of the support frame (12). The telescopic end of the telescopic cylinder (16) is connected to the lifting frame (14). A guide rail (15) is provided on the side wall of the support frame (12). The lifting frame (14) is slidably connected to the support frame (12) through the guide rail (15).

4. The apparatus for preparing water-based mosquito repellent coating according to claim 3, characterized in that: The dispersion drive assembly (2) also includes a material cylinder (21) disposed below the support platform (13) and a motor (23) disposed on the top of the support platform (13). The stirring paddle (32) and the push plate (41) are both located inside the material cylinder (21). The output shaft of the motor (23) is connected to the shaft (22).

5. The apparatus for preparing water-based mosquito repellent coating according to claim 4, characterized in that: The mounting bracket (34) has a sleeve hole (37) at its end for the upright (31) to pass through. The inner wall of the sleeve hole (37) is provided with a limiting slider (38). The limiting slider (38) is located inside the threaded groove (35) and is slidably connected. Both ends of the threaded groove (35) are connected with a straight groove (36). The outer wall of the end of the lifting cylinder (53) is provided with a connecting frame (33). The top of the upright (31) is rotatably connected to the connecting frame (33).

6. The apparatus for preparing water-based mosquito repellent coating according to claim 5, characterized in that: A support rod (42) is provided between the outer wall of the push plate (41) and the shaft (22). At least two support rods (42) are provided and distributed in parallel. Both ends of the support rod (42) and the connecting rod (43) are rotatably connected.

7. The apparatus for preparing water-based mosquito repellent coating according to claim 6, characterized in that: A fixing rod (45) is provided between the top of the sliding sleeve (44) and the lifting cylinder (53). The cross-section of the push plate (41) is a "T" shaped profile, and the end of the push plate (41) is provided with an arc bend.

8. The apparatus for preparing water-based mosquito repellent coating according to claim 6, characterized in that: The lifting cylinder (53) and the shaft (22) are connected by a sliding connection. The guide groove (52) consists of two semi-circular grooves and two oblique arc grooves. The two semi-circular grooves are respectively set on the upper and lower sections of the outer cylinder (51) and distributed on both sides of the outer cylinder (51). The two oblique arc grooves are respectively connected between the ends of the two semi-circular grooves.

9. A method for preparing a water-based mosquito repellent coating, comprising using the apparatus for preparing a water-based mosquito repellent coating as described in claim 8, characterized in that, Includes the following steps: S1. Pre-dispersion of base liquid: Add 200-300 parts of deionized water to the material cylinder (21), and add 6-10 parts of dispersant, 1-2 parts of wetting agent, 3-5 parts of defoamer and 8-12 parts of humectant. Place the material cylinder (21) directly below the support platform (13), start the telescopic cylinder (16) to lower the stirring paddle (32) and push plate (41) below the liquid surface, start the motor (23) to drive the shaft (22) to rotate, and control the speed at 600-800 rpm to form a basic dispersion of liquid phase components. S2, Cellulose Activation: Add 2-4 parts of cellulose to the basic dispersion, increase the rotation speed of the shaft (22) to 1000-1200 rpm and disperse for 10-20 minutes. The shaft (22) drives the upright (31) and the push plate (41) to make circular motion. The lifting cylinder (53) forms a periodic lifting and lowering through the guide groove (52). The upright (31) rises and falls with the lifting cylinder (53) and rotates through the threaded groove (35). The stirring paddle (32) tumbles and shears the cellulose until there are no obvious particles in the system and a pre-thickened slurry is formed. S3, Insect repellent component composite dispersion: Add 150-250 parts of polycyclic aromatic ester insect repellent powder and 5-10 parts of plant-based insect repellent liquid to the pre-thickened slurry, control the stirring paddle (32) to rotate and shear in the middle section of the lifting and lowering, and fold and mix in the high and low sections, so that the polycyclic aromatic ester insect repellent powder is dispersed and coated in the pre-thickened slurry, and the plant-based insect repellent liquid is uniformly introduced into the aqueous continuous phase to form a powder-liquid composite insect repellent dispersion system; S4. Refining and dispersing pigments and fillers: Add 100-200 parts of titanium dioxide, 50-100 parts of 4000 mesh kaolin, 100-200 parts of 2000 mesh heavy calcium carbonate and 2-5 parts of multifunctional regulator to the powder-liquid composite insect repellent dispersion system in sequence, and disperse at high speed for 30 minutes. The sliding sleeve (44) rises and falls with the lifting cylinder (53) and drives the push plate (41) to move radially and reciprocally through the connecting rod (43), so that the high solid content slurry at the periphery of the material cylinder (21) is periodically pushed to the central shearing zone. The stirring paddle (32) simultaneously performs axial tumbling and self-rotation shearing until the fineness of the system is less than 20 μm, and a refined slurry is obtained. S5. Emulsion film-forming compounding and post-adjustment: Add 200-300 parts of odor-neutralizing emulsion and 10-15 parts of odor-neutralizing film-forming aid to the refined slurry to reduce the shear strength and continue mixing to ensure uniform compounding of emulsion particles, insect repellent components and pigments and fillers. Then add 2-4 parts of thickener and 2-5 parts of bactericide, adjust the pH value to 8.5-9, and control the viscosity at around 105 KU. After passing the test, filter and package to obtain water-based mosquito repellent coating.

10. The method for preparing the water-based mosquito repellent coating according to claim 9, characterized in that: In steps S3 to S5, the spiral directions of the threaded grooves (35) on adjacent uprights (31) are opposite, so that adjacent stirring paddles (32) rotate in opposite directions during the lifting process. The push plate (41) is driven by the sliding sleeve (44) and the connecting rod (43) to open and close radially, so as to periodically push the polycyclic aromatic ester insect repellent powder, plant-based insect repellent liquid and pigments and fillers near the inner wall of the barrel (21) towards the central shear zone.

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