Method for manufacturing a brush head and brush head

Abstract

The application relates to a manufacturing method of a brush head and the brush head, and the manufacturing method comprises the following steps: providing a brush head body, the brush head body comprising hair planting holes; inserting brush hairs through the hair planting holes and performing melting and baking to form fixed ends, the fixed ends of the brush hairs being located on the side of the brush head body away from the free ends of the brush hairs; positioning the brush head body with the planted hairs in a first mold, the side of the brush head body away from the free ends of the brush hairs and the first mold defining a cavity for injection molding of a rear cover; and injecting a TPE / PP blended modified material containing 3-5 wt% of a compatilizer into the cavity of the first mold to form the rear cover on the side of the brush head body away from the free ends of the brush hairs. After the brush hairs are melted and baked, the TPE / PP blended modified material containing 3-5 wt% of the compatilizer is used to injection mold the rear cover, the rear cover material can be infiltrated into the microstructure in the surface formed by melting and baking of the brush hairs to form a root structure, a three-dimensional lock is formed between the fixed ends of the brush hairs and the rear cover, and the wrapping force is significantly improved.

Description

Technical Field

[0001] This application relates to the field of cleaning products technology, specifically to a method for preparing a brush head and the brush head itself. Background Technology

[0002] Copper-free bristle implantation involves inserting bristles into the toothbrush head body or head piece, and then fixing the ends of the bristles by hot-melting. Since the bristles are only fixed by the fixed ends after hot-melting, if the back cover of the brush head does not have sufficient wrapping force on the bristles, it will affect the pull strength of the bristles. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a method for preparing a brush head and the brush head itself. After the bristles are melted and heated, a TPE / PP blend modified material containing 3-5 wt% compatibilizer is used to injection mold the back cover. This allows the back cover material to penetrate into the microstructure formed on the surface of the melted bristles, forming a root structure. This creates a three-dimensional locking between the fixed end of the bristles and the back cover, significantly improving the wrapping force.

[0004] To solve the above-mentioned technical problems, this application provides a method for preparing a brush head, comprising the following steps:

[0005] S1, providing a brush head body, the brush head body including bristle implantation holes;

[0006] S2, pass the bristles through the bristle holes and heat-melt to form fixed ends, the fixed ends of the bristles are located on the side of the brush head body opposite to the free ends of the bristles;

[0007] S3, the brush head body after bristle implantation is positioned in the first mold, and the side of the brush head body facing away from the free end of the bristles defines a cavity for injection molding the back cover with the first mold.

[0008] S4, inject a TPE / PP blend modified material containing 3-5wt% compatibilizer into the cavity of the first mold to form the back cover on the side of the brush head body facing away from the free end of the bristles.

[0009] In some embodiments, in step S2, the bristles located at different bristle holes are fused together to form the fixed end with a full surface.

[0010] In some embodiments, step S4 includes:

[0011] The following raw materials are provided: the blending ratio of TPE and PP is 60:40-70:30, the addition ratio of compatibilizer is 3-5 wt% of the total mass of TPE and PP, and the addition ratio of peroxide crosslinking agent is 0.3-0.5 phr of the total mass of TPE and PP;

[0012] Mixing, wherein the temperature range of the feeding section is 180-190℃, the temperature range of the melting section is 190-210℃, the temperature range of the mixing section is 220-250℃, the temperature range of the homogenization section is 210-220℃, and the temperature range of the extrusion section is 200-210℃.

[0013] The TPE / PP blended modified material obtained by mixing is injected into the cavity of the first mold at an injection speed of 60-100 mm / s, an injection pressure of 70-90 MPa, a holding time of 3-5s, a holding pressure of 50-70 MPa, a cooling time of 8-20s, and a temperature of 60-80℃.

[0014] In some embodiments, the first mold is provided with a dual-runner gate, which includes a first runner and a second runner. The first runner has a circular cross-section with a diameter of ϕ3mm; the second runner has a rectangular cross-section with dimensions of 5×3mm; the central axes of the first runner and the second runner intersect at a junction point, and the angle between the first runner and the second runner is 75°-85°; the runner length L from the junction point to the filling start point of the cavity is 3-5mm.

[0015] In some embodiments, step S1 includes:

[0016] S11, A second mold is provided, the second mold having a cavity for injection molding the brush head body;

[0017] S12, PPS / carbon fiber composite material is injected into the cavity of the second mold to form the brush head body.

[0018] In some embodiments, the carbon fiber content in the PPS / carbon fiber composite material is 15-25 wt%.

[0019] In some embodiments, when the carbon fiber content in the PPS / carbon fiber composite material is 20 wt%, the length of the carbon fiber is 6-10 mm; or, when the carbon fiber content is 18 wt%, the length of the carbon fiber is 5-8 mm.

[0020] In some embodiments, the portion of the second mold corresponding to the bristle contact surface of the brush head body has a first microstructure;

[0021] Alternatively, after the brush head body is obtained by injection molding, a second microstructure is formed on the brush head body.

[0022] In some embodiments, the second microstructure comprises an array of conical micropores with a diameter of 50-80 μm and a depth of 100-150 μm, wherein the density of the conical micropores is 800-1000 pores / cm². 2The first microstructure is used to form the second microstructure on the brush head body.

[0023] In some embodiments, the carbon fibers are pretreated with boron phenolic resin, wherein the concentration of the boron phenolic resin is 5-8 wt%.

[0024] In some embodiments, a vacuum is drawn to above -0.08 MPa before injection molding, the injection temperature is 300-320°C, the nozzle temperature is below 320°C, the mold temperature is 120-150°C, the injection pressure is 80-120 MPa, the holding pressure is 60-70% of the injection pressure, and the mold cooling time is 20-30 seconds.

[0025] This application also provides a brush head prepared using the method described above.

[0026] This application discloses a method for preparing a brush head and the brush head itself. The preparation method includes the following steps: providing a brush head body, the brush head body including bristle implantation holes; passing bristles through the bristle implantation holes and hot-melting them to form fixed ends, the fixed ends of the bristles being located on the side of the brush head body opposite to the free ends of the bristles; positioning the bristle-implanted brush head body in a first mold, the side of the brush head body opposite to the free ends of the bristles and the first mold defining a cavity for injection molding a back cover; injecting a TPE / PP blend modified material containing 3-5 wt% compatibilizer into the cavity of the first mold to form a back cover on the side of the brush head body opposite to the free ends of the bristles. This application, by hot-melting the bristles and then using a TPE / PP blend modified material containing 3-5 wt% compatibilizer to injection mold the back cover, allows the back cover material to penetrate into the microstructure of the surface formed by hot-melting the bristles, forming a root structure and creating a three-dimensional locking between the fixed ends of the bristles and the back cover, significantly improving the encapsulation force. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a brush head according to one embodiment.

[0028] Figure 2 is a schematic diagram of a brush head body according to one embodiment.

[0029] Figure 3 This is a schematic cross-sectional view of the brush head body according to one embodiment.

[0030] Figure 4 is a schematic diagram of the brush head body after bristle implantation according to one embodiment.

[0031] Figure 5 This is a schematic flowchart illustrating a method for preparing a brush head according to one embodiment. Detailed Implementation

[0032] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. In this application, "each" includes one or more quantities.

[0034] like Figures 1 to 4 As shown, the brush head in this embodiment can be a toothbrush or a brush head with other cleaning functions. The brush head includes bristles 11, a brush head body 12, and a back cover 13. The brush head body 12 includes bristle insertion holes 121, through which the bristles 11 pass. The fixed ends 112 of the bristles 11 are fixed to the side of the brush head body 12 facing away from the free ends 111 of the bristles 11. The back cover 13 at least covers the side of the brush head body 12 facing away from the free ends 111 of the bristles 11.

[0035] The bristles 11 located in different hair-planting holes 121 are fused together to form a single fixed end 112, which can improve the pulling force. Alternatively, the bristles 11 located in different hair-planting holes 121 are each fused together to form a fixed end 112. Alternatively, the bristles 11 in some hair-planting holes 121 are each fused together to form a fixed end 112, and the bristles 11 in some hair-planting holes 121 are fused together to form a single fixed end 112.

[0036] In some embodiments, the structure of the brush head body 12 is not limited to the figures. For example, the bristle implantation holes 121 of the brush head body 12 include fixed area bristle implantation holes and free area bristle implantation holes. The bristle implantation holes can be connected to each other or independent of each other. When the bristle implantation holes are independent of each other, the degree of freedom of the bristles can be adjusted by wrapping the back cover.

[0037] In some embodiments, the brush head body 12 further includes ribs 122, which are formed on one side of the brush head body 12 away from the free end 111 of the bristles 11. The ribs 122 are located between the bristle holes 121, and at least some of the ribs 122 are interconnected. By providing ribs 122 on the brush head body 12, the strength of the toothbrush head can be enhanced. Even after the brush head body 12 is thinned, its strength can still be guaranteed. At the same time, when the bristles 11 are melted, the ribs 122 and the fixed end 112 of the bristles 11 form an interlocking structure during melting, which can enhance the pull-out strength of the bristles 11. This is beneficial for the thinning design of the toothbrush head, especially suitable for the thinning design of copper-free bristle toothbrushes. In one embodiment, a groove is provided on one side of the brush head body 12 away from the free end 111 of the bristles 11. The groove is used to accommodate the fixed end 112 formed after the bristles 11 are melted, and the bristle holes 121 and the ribs 122 are located in the groove. Please combine Figures 2 to 4 The edge of the settling tank is provided with retaining ribs 123. The tufting holes 121 and ribs 122 are located within the settling tank. The ribs 122 may or may not be connected to the retaining ribs 123. In this embodiment, the top surface of the rib 122 is flush with the top surface of the retaining rib 123; that is, the height of the rib 122 is equal to the depth of the settling tank. In this embodiment, as... Figure 2 As shown, the ribs 122 are interconnected to form a honeycomb structure, which has a good strength enhancement effect. In actual implementation, the ribs 122 can also be interconnected to form an irregular structure. In this embodiment, the ribs 122 divide each bristle hole 121 into a separate area, and in each area divided by the ribs 122, the fixed end 112 of the bristles 11 is melted into a whole piece. Figure 4 As shown, the tip of each bristle 11 in each bristle hole 121 is individually melted into a region and combined with the surrounding ribs 122 to improve the pull-out strength of the bristles 11. In one embodiment, the back cover 13 is a soft back cover, and the ribs 122 are at least partially higher than the fixed ends 112 of the bristles 11. When melting the bristles 11, the top surface of the fixed ends 112 of the bristles 11 formed after melting is lower than or equal to the top surface of the ribs 122. That is, after melting the bristles 11, the fixed ends of the bristles 11 do not cover the ribs 122, thus exposing at least a portion of the ribs 122. In this way, when forming the soft back cover 13, the back cover 13 can be well combined with the ribs 122, solving the problem of insufficient bonding force between the soft back cover 13 and the fixed ends 112 of the bristles 11. In this way, the strength of the toothbrush head can be enhanced, while reducing the gap between parts and improving the vibration transmission of the sonic motor. In practice, the height of the rib 122 can also be greater than the depth of the groove, and it can also be combined with the back cover 13.

[0038] In some embodiments, the ribs 122 may also divide a plurality of adjacent hair-planting holes into a region, and the ribs 122 are interconnected to form an irregular structure.

[0039] In some embodiments, the multi-bristle bundle 11 includes a central bristle and multiple outer bristles surrounding the central bristle. The brush head body 12 includes a metal spring and a reinforcing member. The metal spring is encased in the reinforcing member. The metal spring has, for example, a leaf-shaped structure, including a central single-hole structure for forming bristle holes and a surrounding single-hole structure, so that the bristle area corresponding to the central part forms a fixed bristle area. Each single-hole structure has a certain elasticity, allowing the bristle area corresponding to the single-hole structure to form a free-degree bristle area. The metal spring is made of stainless steel and has two body fixing holes at one end for molten plastic to pass through during in-mold injection molding with the brush handle, forming a bolt-type fixing structure to reliably connect the brush head body 12 and the brush handle. The shape of the reinforcing member corresponds to the bristles, including a connected central part and multiple peripheral parts. The central part and each peripheral part have through holes for the corresponding outer bristles to pass through. The reinforcing member is injection molded from rigid plastic, and the reinforcing member encases the metal spring and exposes the body fixing holes on the metal spring. In this embodiment, the reinforcing components include ribs 122 and baffles 123.

[0040] As shown in Figure 5, a method for preparing a brush head according to this embodiment is used to prepare the above-mentioned brush head. The preparation method includes the following steps:

[0041] S1, provides a brush head body, the brush head body including bristle implantation holes;

[0042] S2, pass the bristles through the bristle implantation hole and heat-melt to form a fixed end. The fixed end of the bristles is located on the side of the brush head body that is away from the free end of the bristles.

[0043] S3, Position the bristle-embedded brush head body in the first mold, and define a cavity for injection molding the back cover by the side of the brush head body facing away from the free end of the bristles and the first mold.

[0044] S4, inject a TPE / PP blend modified material containing 3-5wt% compatibilizer into the cavity of the first mold to form a back cover on the side of the brush head body facing away from the free end of the bristles.

[0045] The fixed end is formed by melting multiple bristles from the bristle bundle. After the bristles melt and cool, due to slight differences in the degree of melting and cooling speed of different bristles, tiny gaps are formed on the surface of the fixed end. When melting the bristles, the size and number of tiny gaps on the surface of the fixed end can be adjusted by selecting parameters such as melting temperature, melting time and cooling time.

[0046] In TPE / PP blend modified materials containing 3-5 wt% compatibilizer, the addition ratio of compatibilizer can effectively reduce the interfacial tension of the TPE / PP blend modified material, making the flowability of the blend melt better and having a better penetration effect on the tiny gaps on the surface of the fixed end. Thus, during the injection molding process, the TPE / PP blend modified material can fully penetrate into the tiny gaps on the surface of the fixed end to form a root structure, thereby forming a three-dimensional lock between the fixed end of the brush bristles and the back cover, significantly improving the wrapping force of the brush bristles.

[0047] In some embodiments, step S4 includes:

[0048] The following raw material ratios are provided: the blending ratio of TPE (thermoplastic elastomer) and PP (polypropylene) is 60:40-70:30, the addition ratio of compatibilizer is 3-5 wt% of the total mass of TPE and PP, and the addition ratio of peroxide crosslinking agent is 0.3-0.5 phr of the total mass of TPE and PP.

[0049] Mixing, wherein the temperature range of the feeding section is 180-190℃, the temperature range of the melting section is 190-210℃, the temperature range of the mixing section is 220-250℃, the temperature range of the homogenization section is 210-220℃, and the temperature range of the extrusion section is 200-210℃.

[0050] The TPE / PP blend modified material obtained by mixing is injected into the cavity of the first mold. The injection speed is 60-100 mm / s, the injection pressure is 70-90 MPa (segmented control: initial low speed for 15-30% filling, followed by high speed to complete), the holding time is 3-5 s (the holding time is set according to the product thickness, increasing by 1-3 s / mm with thickness), the holding pressure is 50-70 MPa, the cooling time is 8-20 s, and the temperature of the first mold is 60-80℃.

[0051] During the mixing process, a co-rotating twin-screw extruder can be used for zoned temperature control and segmented shearing to achieve uniform dispersion. The feeding section pre-melts the TPE (unmelted PP) at 180-190℃; the melting section at 190-210℃, where the PP melts and blending begins; the mixing section at 220-250℃ for thorough blending; the homogenization section at 210-220℃ with temperature adjustment to form a microscopic interlocking network; and the extrusion section (die head) at 200-210℃ for uniform melt extrusion. When blending TPE / PP, the melt flow index (MFI) needs to be controlled at 15-25 g / 10min (230°C / 2.16 kg), as excessively high MFI can lead to micropore collapse.

[0052] By selecting a compatibilizer addition ratio of 3-5 wt% of the total mass of TPE and PP, the interfacial issues in high-proportion TPE / PP blends can be resolved, maximizing the soft touch and elasticity of the back cover. Furthermore, the synergistic effect of the compatibilizer and peroxide crosslinking agent is optimized, ensuring effective vulcanization of the TPE phase (improving strength and resistance to permanent deformation) while mitigating degradation of the PP phase, maintaining the overall strength of the matrix, and thus precisely controlling the crosslinking depth. Simultaneously, it most effectively reduces interfacial tension, resulting in better flowability of the blend melt, while moderate crosslinking ensures sufficient melt strength to prevent cracking during high-speed injection. In some embodiments, the compatibilizer is maleic anhydride-grafted polyolefin (MAH-g-POE or MAH-g-PP), and the peroxide crosslinking agent is dicumyl peroxide (DCP).

[0053] In some embodiments, the first mold is provided with a dual-runner gate, which includes a first runner and a second runner. The first runner has a circular cross-section with a diameter of ϕ3mm; the second runner has a rectangular cross-section with dimensions of 5×3mm; the central axes of the first and second runners intersect at the junction point, and the angle between the first and second runners is 75°-85°; the runner length L from the junction point to the filling start point of the cavity is 3-5mm.

[0054] The first flow channel is used to transport the melt dominated by the PP phase, and the second flow channel is used to transport the melt dominated by the TPE phase. A circular flow channel is used for the PP phase, which has low shear sensitivity, making processing simple, reducing flow resistance, and increasing pressure transmission efficiency. A rectangular flow channel is used for the shear-sensitive TPE phase, whose larger perimeter-to-area ratio enhances heat transfer efficiency and prevents TPE from overheating and degrading.

[0055] The angle between the first and second flow channels generates a moderate shear component on the two melt streams, tearing the skin of the melt front and promoting the microscopic interpenetration of the TPE and PP phases. In addition, it reduces sudden changes in flow direction, lowers kinetic energy loss and eddies, and ensures that the melt can be injected into the cavity more smoothly and at a faster speed, ensuring the formation of the root structure in the fixed end of the brush, and with a higher degree of isotropy in mechanical properties.

[0056] The design of the flow channel length L from the confluence point of the flow channel to the filling start point of the cavity ensures that the TPE and PP phases are sheared and mixed to the molecular level before entering the cavity, providing optimal conditions for the compatibilizer to play its role, ensuring the interfacial bonding strength. In addition, it can effectively prevent premature vulcanization of the TPE phase and thermal degradation of the PP phase, ensuring the inherent excellent properties of the material, reducing unnecessary loss of injection pressure, and helping to maintain higher cavity end pressure.

[0057] By selecting a compatibilizer ratio of 3-5wt%, and choosing an injection pressure of 70-90 MPa and an injection temperature of 200-210℃, the TPE / PP blend modified material can effectively penetrate into the micropores at the fixed end of the bristles to form a root structure, forming a three-dimensional lock with the fusion zone of the bristles, thus increasing the encapsulation force by 50%.

[0058] In some embodiments, step S1 includes:

[0059] S11, providing a second mold having a cavity for injection molding the brush head body;

[0060] S12, PPS / carbon fiber composite material is injected into the cavity of the second mold to form the brush head body.

[0061] In this process, carbon fibers are mixed into PPS (polyphenylene sulfide) and melt-blended at a screw temperature of 300-350°C to ensure uniform mixing. The second mold can be fabricated using 3D printing technology, optimizing the flow channel to create vortex flow in the melt, promoting carbon fiber interlacing, or designing a micropillar array on the mold surface to interfere with the flow front and induce random fiber distribution; or simultaneously optimizing the flow channel and designing the micropillar array. The injection temperature is set to 300-320°C, with the nozzle temperature controlled below 320°C to prevent material degradation; the temperature of the second mold is maintained at 120-150°C to optimize crystallinity; the injection pressure is set to 80-120MPa, the holding pressure is 60-70% of the injection pressure, and the mold cooling time is 20-30 seconds. Thus, a flexural modulus ≥220MPa can be achieved by forming an internal support network through the three-dimensional random distribution of micron-level carbon fibers.

[0062] Since PPS is prone to oxidative cross-linking above 300°C, the processing window can be extended by using nitrogen protection or adding 0.5-1% antioxidant (such as Irganox 1010). Carbon fiber is prone to breakage under high pressure; therefore, screw speed optimization (60-80 rpm) and a two-stage venting screw can be used.

[0063] In some embodiments, the carbon fiber content in the PPS / carbon fiber composite is 15-25 wt%.

[0064] In some embodiments, in the PPS / carbon fiber composite material, when the carbon fiber content is 20 wt%, the length of the carbon fiber is 6-10 mm; or, when the carbon fiber content is 18 wt%, the length of the carbon fiber is 5-8 mm.

[0065] When 20wt% carbon fiber is included, a continuous fiber network can be formed, increasing the contact probability and synergistic load-bearing effect between fibers. Simultaneously, the length of the carbon fiber can more effectively transfer and disperse stress, preventing entanglement and breakage at high carbon fiber content. When 18wt% carbon fiber is included, the flowability during injection molding is improved, allowing for slightly shorter fiber lengths, reducing appearance defects caused by fiber agglomeration, ensuring a smooth surface on the back of the brush head, and providing a better bonding interface for subsequent encapsulation with the TPE / PP back cover.

[0066] The preferred diameter of the carbon fiber is 6-9 μm, which provides the maximum effective interfacial bonding area and ensures load transfer. Fibers that are too fine (e.g., below 5 μm) are prone to agglomeration, and excessive interfacial area can become stress concentration points. Fibers that are too coarse (e.g., above 10 μm) have poor adhesion.

[0067] In some embodiments, the carbon fiber is pretreated with boron phenolic resin to improve its interfacial shear strength with the PPS matrix. The concentration of boron phenolic resin is 5-8 wt%. During sizing, the thickness of the sizing film is kept to a moderate thickness. After sizing, the drying temperature is 80-100°C to fully remove moisture and prevent air bubbles from forming during subsequent high-temperature treatment, ensuring the integrity of the sizing film. The initial curing temperature is 220-250°C for 80 seconds, and nitrogen is used for protection to prevent oxidation.

[0068] In some embodiments, the portion of the second mold corresponding to the bristle contact surface of the brush head body has a first microstructure; or, after the brush head body is injection molded, a second microstructure is formed on the brush head body.

[0069] The first microstructure in the second mold is used to simultaneously form the second microstructure on the brush head body during injection molding. Alternatively, after the brush head body is obtained through injection molding, surface processing techniques such as laser lithography and chemical etching can be used to process and form the second microstructure in a corresponding area on the brush head body.

[0070] In some embodiments, the bristles can be made of thermoplastic polyurethane (TPU) elastomer or copolyamide. These materials are designed with a melting / softening point of 120-140°C. When the brush head body has a microstructure on its surface, the bristles can interlock with the brush head body during the melting process, resulting in better bonding strength. Therefore, the melting temperature of the bristles can be reduced to 135±5°C. Lowering the melting temperature of the bristles more effectively prevents the degradation of the molecular chains in the brush head body, further preventing the material around the bristle pores from becoming brittle. Furthermore, TPE itself has a low softening point (typically 130-150°C), and when mixed with PP, the softening point reaches 135°C. The melting temperature of 135°C has a preheating effect, providing an ideal preheating interface for subsequent TPE / PP injection molding, which can promote molecular chain diffusion and fusion, improving the bonding interface between the brush head body and the back cover.

[0071] In some embodiments, the second microstructure comprises an array of conical micropores with a diameter of 50-80 μm and a depth of 100-150 μm, wherein the density of the conical micropores is 800-1000 per cm. 2 The second microstructure can be formed on the bottom or side walls of the settling tank, in areas that can come into contact with the molten bristles.

[0072] When the second mold incorporates the first microstructure (such as a micro-conical hole), a draft angle of ≥3° is designed in the second mold to ensure the integrity of the structure after demolding. Furthermore, vacuum venting grooves can be created around the cavity of the microstructure and connected to a vacuum pump outside the mold. Before injection molding, the pressure is instantly evacuated to above -0.08MPa to completely remove air from the cavity, preventing incomplete filling and localized burning caused by trapped air. This improves the molding yield of the second microstructure and ensures the effective formation of the interlocking structure between the brush head body and the bristles.

[0073] This application discloses a method for preparing a brush head, comprising the steps of: providing a brush head body, the brush head body including bristle implantation holes; passing bristles through the bristle implantation holes and hot-melting them to form fixed ends, the fixed ends of the bristles being located on the side of the brush head body opposite to the free ends of the bristles; positioning the bristle-implanted brush head body in a first mold, the side of the brush head body opposite to the free ends of the bristles and the first mold defining a cavity for injection molding a back cover; injecting a TPE / PP blend modified material containing 3-5 wt% compatibilizer into the cavity of the first mold to form a back cover on the side of the brush head body opposite to the free ends of the bristles. This application, by hot-melting the bristles and then using a TPE / PP blend modified material containing 3-5 wt% compatibilizer to injection mold the back cover, allows the back cover material to penetrate into the microstructure of the surface formed by hot-melting the bristles, forming a root structure and creating a three-dimensional locking between the fixed ends of the bristles and the back cover, significantly improving the encapsulation force.

[0074] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a brush head, characterized in that, Including the following steps: S1, providing a brush head body, the brush head body including bristle implantation holes; S2, passing the bristles through the bristle implantation hole and hot-melting to form a fixed end, the fixed end of the bristles is located on the side of the brush head body opposite to the free end of the bristles, and the surface of the fixed end has a tiny gap. S3, the brush head body after bristle implantation is positioned in the first mold, and the side of the brush head body facing away from the free end of the bristles defines a cavity for injection molding the back cover with the first mold. S4, inject a TPE / PP blend modified material containing 3-5wt% compatibilizer into the cavity of the first mold to form the back cover on the side of the brush head body opposite to the free end of the bristles; wherein, in the TPE / PP blend modified material, the blending ratio of TPE and PP is 60:40-70:30, the addition ratio of compatibilizer is 3-5wt% of the total mass of TPE and PP, and the addition ratio of peroxide crosslinking agent is 0.3-0.5phr of the total mass of TPE and PP; during the injection molding process, the TPE / PP blend modified material penetrates into the tiny gaps on the surface of the fixed end to form a root structure, forming a three-dimensional lock between the fixed end of the bristles and the back cover.

2. The method as described in claim 1, characterized in that, In step S2, the bristles located at different bristle holes are fused together to form the fixed end with a whole surface.

3. The method as described in claim 1, characterized in that, Step S4 includes: Mixing, wherein the temperature range of the feeding section is 180-190℃, the temperature range of the melting section is 190-210℃, the temperature range of the mixing section is 220-250℃, the temperature range of the homogenization section is 210-220℃, and the temperature range of the extrusion section is 200-210℃. The TPE / PP blend modified material obtained by injecting the mixture into the cavity of the first mold.

4. The method as described in claim 3, characterized in that, The first mold is provided with a dual-runner gate, which includes a first runner and a second runner. The central axes of the first runner and the second runner intersect at the confluence point, and the included angle between the first runner and the second runner is 75°-85°. The runner length from the confluence point to the filling start point of the cavity is 3-5mm.

5. The method according to any one of claims 1 to 4, characterized in that, Step S1 includes: S11, A second mold is provided, the second mold having a cavity for injection molding the brush head body; S12, PPS / carbon fiber composite material is injected into the cavity of the second mold to form the brush head body.

6. The method as described in claim 5, characterized in that, The carbon fiber content in the PPS / carbon fiber composite material is 15-25 wt%.

7. The method as described in claim 6, characterized in that, In the PPS / carbon fiber composite material, when the carbon fiber content is 20 wt%, the length of the carbon fiber is 6-10 mm; or, when the carbon fiber content is 18 wt%, the length of the carbon fiber is 5-8 mm.

8. The method as described in claim 5, characterized in that, The portion of the second mold corresponding to the bristle contact surface of the brush head body has a first microstructure; Alternatively, after the brush head body is obtained by injection molding, a second microstructure is formed on the brush head body.

9. The method as described in claim 8, characterized in that, The second microstructure is an array of conical micropores with a diameter of 50-80 μm and a depth of 100-150 μm, wherein the density of the conical micropores is 800-1000 per cm. 2 The first microstructure is used to form the second microstructure on the brush head body.

10. The method as described in claim 5, characterized in that, The carbon fiber is pretreated with boron phenolic resin, and the concentration of the boron phenolic resin is 5-8 wt%.

11. The method as described in claim 5, characterized in that, In step S12, the cavity of the second mold is evacuated to below -0.08 MPa before injection molding, and the injection temperature is 300-320°C.

12. A brush head, characterized in that, It is prepared by any one of claims 1 to 11.

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