Antibacterial toothbrush wire material and preparation method thereof

Abstract

The invention discloses an antibacterial toothbrush wire material and a preparation method thereof. The brush wire material comprises a thermoplastic polymer matrix and at least one of zinc cinnamate, calcium cinnamate or magnesium cinnamate dispersed in the thermoplastic polymer matrix. The cinnamic acid metal salt is excellent in thermal stability in a brush wire melting processing process, and the problem of antibacterial failure caused by high-temperature volatilization of traditional cinnamyl alcohol or cinnamyl aldehyde can be effectively avoided; after being formed, the brush wires are subjected to alkaline damp-heat post-treatment, so that the cinnamic acid metal salt can be partially hydrolyzed, cinnamic acid substances are released, and the cinnamic acid substances are enriched on the surface layers of the brush wires; in a subsequent oral use environment, the substance is further converted into cinnamyl alcohol or cinnamyl aldehyde with high antibacterial activity, so that the antibacterial efficiency is remarkably improved. The antibacterial rate of the obtained brush wire on common oral pathogens such as staphylococcus aureus is larger than or equal to 88%, the mechanical property is excellent, and various colors such as red, blue and green can be achieved by adding pigments. The technical problem that the natural cinnamon antibacterial agent is difficult to apply to the high-temperature spinning process is solved, and the method has functionality and attractiveness and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of oral care materials technology, specifically to an antibacterial toothbrush bristle material and its preparation method. Background Technology

[0002] As a daily oral hygiene tool, toothbrushes' bristles are constantly in a moist environment, making them highly susceptible to bacterial growth, such as Staphylococcus aureus, Escherichia coli, and Streptococcus mutans. These microorganisms not only affect oral hygiene but can also lead to problems like gingivitis and halitosis. Therefore, developing toothbrush bristles with long-lasting antibacterial properties has become an important research direction in the industry.

[0003] Natural plant extracts are widely used in antibacterial toothbrushes due to their safe and broad-spectrum antibacterial properties. Cinnamon extract (whose main active ingredients are cinnamaldehyde and cinnamyl alcohol) has attracted considerable attention for its significant inhibitory effect on various oral pathogens and its refreshing scent. However, both cinnamaldehyde and cinnamyl alcohol are low-boiling-point (cinnamyl alcohol has a boiling point of approximately 250°C, but it is easily oxidized or volatilized below 200°C) and highly heat-sensitive organic compounds, making them difficult to stabilize during the conventional preparation process of toothbrush bristles.

[0004] Currently, toothbrush bristles are mostly made of thermoplastic polymers such as nylon or polybutylene terephthalate, formed through melt extrusion-stretching processes, with processing temperatures typically reaching 220-260℃. Under these high-temperature, high-shear conditions, directly added cinnamyl alcohol or cinnamaldehyde is highly susceptible to volatilization, decomposition, or oxidation, resulting in almost undetectable effective ingredients in the final product and weak or even complete loss of antibacterial effect.

[0005] To address this issue, existing technologies attempt to immobilize cinnamon-based active ingredients using methods such as microencapsulation, adsorption carriers, or low-temperature blending. For example, one patent encapsulates cinnamon oil in gelatin / gum arabic microcapsules and then blends it with nylon. However, the wall materials of these microcapsules are mostly proteins or polysaccharides, which have limited thermal stability and decomposition temperatures typically below 210°C. Under actual extrusion conditions, they are still insufficient to effectively protect the core components. Furthermore, the poor compatibility between hydrophilic microcapsules and hydrophobic polymer matrices can easily lead to decreased mechanical properties of the brush filaments, surface roughness, or shedding, affecting user safety and experience.

[0006] Furthermore, commercially available antibacterial toothbrush bristles are mostly black due to the addition of traditional antibacterial agents such as charcoal black, resulting in a limited color range that fails to meet consumers' demands for personalized and aesthetically pleasing oral care products. Achieving a balance between antibacterial function and a variety of colors would significantly enhance a product's market competitiveness.

[0007] In summary, current technologies have not yet provided a feasible solution that can effectively address the high-temperature processing stability issue of cinnamon-based antibacterial components while also considering the mechanical properties and aesthetic diversity of toothbrush bristles. Therefore, there is an urgent need to develop a novel antibacterial toothbrush bristle material and its preparation method to overcome the aforementioned technical bottlenecks. Summary of the Invention

[0008] The purpose of this invention is to overcome the technical defects in the prior art where cinnamon-based antibacterial components (such as cinnamyl alcohol and cinnamaldehyde) are easily volatilized and decomposed during the high-temperature preparation of toothbrush bristles, resulting in the loss of antibacterial effect. This invention provides a toothbrush bristle material with high thermal stability, long-lasting antibacterial performance, and the ability to achieve a variety of colors, as well as its preparation method.

[0009] To achieve the above-mentioned objectives, this application adopts the following technical solution: An antibacterial toothbrush bristle material comprises a thermoplastic polymer matrix and a metal cinnamate dispersed therein, wherein the metal cinnamate is at least one selected from zinc cinnamate, calcium cinnamate, or magnesium cinnamate. This metal cinnamate exhibits excellent thermal stability (decomposition temperature above 300°C) and maintains structural integrity at conventional bristle melt extrusion temperatures (200-260°C), effectively preventing the loss of active ingredients.

[0010] Furthermore, the particle size of the cinnamic acid metal salt is 1-50 μm, and its content is 1-10 wt% of the total mass of the brush bristle material.

[0011] Furthermore, the thermoplastic polymer matrix is ​​selected from at least one of polyamide 6, polyamide 66, polybutylene terephthalate, or polypropylene.

[0012] Furthermore, the bristle material also contains pigments, which are inorganic pigments or high-temperature resistant organic pigments, giving the bristles any one of the colors red, orange, yellow, green, blue, indigo, purple, or black.

[0013] The pigment is a high-temperature resistant inorganic pigment or a high-temperature resistant organic pigment, with a decomposition temperature of not less than 280℃.

[0014] This application also discloses a method for preparing an antibacterial toothbrush bristle material, comprising the following steps: (1) Cinnamic acid metal salt particles were prepared by reacting cinnamic acid with a metal salt precursor in a solvent. (2) The cinnamic acid metal salt particles, thermoplastic polymer and optional pigment are mixed evenly and then melt-extruded and granulated to obtain brush filament masterbatch; (3) The brush masterbatch is melt-spun to produce a primary brush bristle product; (4) The initial bristle product is subjected to alkaline wet heat post-treatment to activate the metal salt of cinnamic acid therein, so as to obtain toothbrush bristles with antibacterial activity.

[0015] Furthermore, the metal salt precursor in step (1) is zinc nitrate, calcium chloride or magnesium sulfate, the solvent is water or ethanol, the reaction temperature is 25-80℃, and the reaction time is 1-4 hours.

[0016] Furthermore, in step (2), the temperature of melt extrusion is 200-260℃, the screw speed is 50-120rpm, and the residence time of the material in the extruder does not exceed 5 minutes.

[0017] Furthermore, the post-treatment in step (4) is alkaline steam, immersion in a weak alkaline aqueous solution, or treatment with hot and humid air.

[0018] A toothbrush whose bristles are made of the aforementioned antibacterial toothbrush bristle material.

[0019] This invention abandons the traditional approach of directly adding heat-sensitive cinnamyl alcohol / aldehyde, instead using a heat-stable metal cinnamic acid salt as an antibacterial precursor, and achieving active release during the application stage through a controllable post-activation process. This successfully resolves the core contradiction of the incompatibility between high-temperature processing and antibacterial function.

[0020] This application effectively solves the technical problem of loss of antibacterial function caused by the easy volatilization and decomposition of traditional cinnamyl alcohol or cinnamaldehyde during the high-temperature melting process of toothbrush bristles by using a thermally stable metal salt of cinnamic acid as an antibacterial precursor. This metal salt of cinnamic acid can stably exist in the bristles under processing conditions below 260℃. Alkaline moist heat post-treatment of the initial bristle product can promote the partial hydrolysis of the metal salt of cinnamic acid and release cinnamic acid substances, which are then enriched on the surface of the bristles. In the subsequent oral environment, these substances are further converted into cinnamyl alcohol or cinnamaldehyde, which have strong antibacterial activity, thereby significantly improving the antibacterial efficacy. This achieves the dual advantages of "processing stability and activation during use." The resulting bristles not only have an antibacterial rate of over 90% against common oral pathogens (such as Staphylococcus aureus and Escherichia coli), but also have excellent mechanical properties and adjustable color, successfully balancing antibacterial efficacy, processing feasibility, and product aesthetics, significantly superior to existing technologies. Detailed Implementation

[0021] The present application will be further described below through embodiments, but the scope of protection of the present application is not limited to the embodiments.

[0022] Example 1: Preparation of zinc cinnamate brush bristles (1) Synthesis of zinc cinnamate microparticles: 10.0 g of cinnamic acid and 6.5 g of zinc nitrate hexahydrate were added to 100 mL of anhydrous ethanol and stirred until dissolved. The pH was slowly adjusted to 6.5 with 1 mol / L sodium hydroxide ethanol solution. The temperature was raised to 60 °C and stirred at a constant temperature for 2 hours, during which a white flocculent precipitate was formed. The precipitate was cooled to room temperature, filtered, washed three times with anhydrous ethanol, and dried under vacuum at 60 °C for 4 hours. After grinding, the precipitate was passed through a 45 μm sieve to obtain white zinc cinnamate microparticles (D50 = 18 μm, yield approximately 92%).

[0023] (2) Masterbatch preparation: 97.0 wt% polyamide 6, 3.0 wt% of the above-mentioned zinc cinnamate microparticles and 0.5 wt% high-temperature resistant red organic pigment (CIPigmentRed177) were mixed at high speed for 10 minutes; the mixture was then melt-granulated using a twin-screw extruder with temperatures of 220-230-235-230℃, screw speed of 80 rpm, and residence time of approximately 3 minutes to obtain red brush filament masterbatch.

[0024] (3) Bristle forming and post-processing: After drying, the masterbatch was melt-spun at 235℃ to produce initial brush bristles with a diameter of 0.18 mm. These bristles were then placed in saturated sodium bicarbonate vapor at pH 9.5 and treated at 50℃ for 15 minutes to complete antibacterial activation, yielding red antibacterial toothbrush bristles. Antibacterial tests showed a 93% inhibition rate against Staphylococcus aureus, indicating that zinc cinnamate was effectively activated.

[0025] Example 2: Preparation of calcium cinnamate filaments (1) Synthesis of calcium cinnamate microparticles: 10.0 g of cinnamic acid and 5.6 g of calcium chloride dihydrate were added to a mixed solvent consisting of 80 mL of deionized water and 20 mL of anhydrous ethanol, and stirred at room temperature until dissolved. The pH was slowly adjusted to 7.0 with 1 mol / L ammonia. The temperature was raised to 50 °C and stirred at a constant temperature for 1.5 hours, resulting in the precipitation of a white precipitate. The precipitate was cooled to room temperature and filtered. The precipitate was washed twice with deionized water (30 mL each time) and then once with anhydrous ethanol (20 mL). The filter cake was vacuum dried at 60 °C for 5 hours. After grinding, the precipitate was passed through a 45 μm sieve to obtain calcium cinnamate microparticles with a D50 of 22 μm and a yield of approximately 89%.

[0026] (2) Preparation of brush bristle masterbatch: Weigh 96.7g of polybutylene terephthalate (PBT, intrinsic viscosity 1.0dL / g), 3.0g of calcium cinnamate microparticles, and 0.3g of cobalt blue inorganic pigment (CoAl2O4), and mix at high speed for 10 minutes (1500rpm). Granulate using a twin-screw extruder with the following temperature settings: 230℃-235℃-240℃-235℃, screw speed 70rpm, and residence time approximately 3.5 minutes. The extruded strip is then water-cooled and pelletized to obtain blue masterbatch.

[0027] (3) Spinning and forming of the initial brush bristles: After the masterbatch is vacuum dried at 80℃ for 4 hours, it is fed into a spinning machine with a spinning temperature of 245℃. The spinneret has a diameter of 0.25mm, and the spinneret is cooled by side blowing (25℃, 0.4m / s). The hot roller is stretched by 3.2 times and wound into a blue brush filament with a diameter of 0.18mm.

[0028] (4) Post-processing activation: The initial bristles were immersed in a sodium carbonate aqueous solution (pH=10.0, concentration 0.1mol / L) and soaked in a constant temperature water bath at 60℃ for 10 minutes. After removal, they were rinsed 3 times with deionized water and dried at 40℃ for 1 hour to obtain the finished blue antibacterial toothbrush bristles.

[0029] Example 3: Milky white antibacterial toothbrush bristles containing magnesium cinnamate (1) Synthesis of magnesium cinnamate microparticles: 10.0 g of cinnamic acid and 4.9 g of magnesium sulfate heptahydrate were dissolved in a mixed solvent of 60 mL anhydrous ethanol and 40 mL deionized water. While stirring, 1 mol / L sodium hydroxide aqueous solution was slowly added dropwise, with the pH strictly controlled at 6.8 (avoiding exceeding 7.0 to prevent the formation of Mg(OH)₂ precipitate). The temperature was raised to 70 °C, and the reaction was stirred at this constant temperature for 3 hours, resulting in the slow precipitation of a fine white precipitate. The precipitate was cooled and filtered. It was then washed successively with deionized water (2 × 20 mL) and anhydrous ethanol (2 × 20 mL). The precipitate was dried under vacuum at 70 °C for 6 hours. The precipitate was then ground through a 45 μm sieve to obtain magnesium cinnamate microparticles with a D50 of 15 μm and a yield of approximately 82%.

[0030] (2) Preparation of brush bristle masterbatch: Weigh 97.0g PA6 and 3.0g magnesium cinnamate microparticles (without pigments), mix at high speed for 10 minutes; granulate by twin-screw extrusion at a temperature range of 220℃-230℃-235℃-230℃ and a screw speed of 80rpm to obtain milky white masterbatch.

[0031] (3) Spinning and forming of the initial brush bristles: After drying the masterbatch at 80°C for 4 hours, it was spun at 235°C using the same process as in Example 1, yielding a milky white brush filament with a diameter of 0.18 mm.

[0032] (4) Post-processing activation: The initial bristle samples were placed in a constant temperature and humidity chamber, with the temperature set at 60℃ and the relative humidity at 80%, and treated for 20 minutes (the air inside the chamber was naturally slightly alkaline, with a pH of approximately 8.8). After removal, the bristles were dried at 40℃ for 1 hour to obtain the finished milky white antibacterial toothbrush bristles.

[0033] Comparative Example 1: Red bristles with cinnamyl alcohol added directly (without precursor protection) (1) Mixing raw materials Weigh 97.0g of polyamide 6 (PA6), 3.0g of cinnamyl alcohol (purity ≥98%, boiling point 250–252℃) and 0.5g of high-temperature resistant organic red pigment (CIPigment Red 177), add them to a high-speed mixer, and mix at 1500rpm for 10 minutes.

[0034] (2) Preparation of masterbatch and brush bristles The process is the same as in Example 1, yielding a preliminary product of red brush filaments.

[0035] (3) Post-processing Same as Example 1.

[0036] Phenomena and Results: A strong cinnamon aroma is released during the extrusion process, which can be clearly detected by the operator. The finished brush bristles have no special odor; GC-MS analysis showed that the cinnamyl alcohol content in the brush filaments was only 0.09 wt%, equivalent to 3.0% of the feed amount. The antibacterial test showed an inhibition rate of 12%, indicating that the active ingredients were essentially ineffective.

[0037] Comparative Example 2: Red bristles of cinnamyl alcohol encapsulated in gelatin / gum arabic microcapsules (1) Preparation of cinnamyl alcohol microcapsules: 5.0 g of gelatin (Type A, Bloom 200) was dissolved in 90 mL of deionized water (50 °C) to obtain a 5% gelatin solution; 5.0 g of gum arabic was dissolved in 10 mL of water, and the mixture was prepared to obtain a gelatin-gum arabic co-solution; the pH was adjusted to 4.5 with 1 mol / L HCl; 3.0 g of cinnamyl alcohol was added, and the mixture was emulsified at 10,000 rpm for 10 minutes to form an O / W emulsion; the temperature was slowly raised to 55 °C, and the pH was adjusted to 8.5 with 1 mol / L NaOH to induce coagulation and encapsulate the cinnamyl alcohol; the mixture was cooled to 10 °C to solidify, and formaldehyde (0.5 wt%) was added for cross-linking; the mixture was filtered, washed, and freeze-dried to obtain cinnamyl alcohol microcapsules (core content approximately 70 wt%, i.e., containing 2.1 g of cinnamyl alcohol per microcapsule).

[0038] (2) Preparation of brush bristles To ensure consistent cinnamyl alcohol dosage, 4.29g of the above microcapsules (containing 3.0g of cinnamyl alcohol), 92.71g of PA6 and 0.5g of red pigment were weighed, mixed, and then extruded, spun and post-treated according to the process in Example 1.

[0039] Phenomena and Results: The extrudate has a rough surface and a distinct granular texture; TGA showed a total mass loss rate of 4.8% at 260°C (higher than the example); GC-MS analysis revealed that the residual amount of cinnamyl alcohol in the finished product was 1.23 wt%, with a retention rate of approximately 41%. The tensile strength of the bristles was only 265 MPa (a 34% decrease compared to the pure PA6 sample). The antibacterial rate was 48%, with limited antibacterial effect and significantly deteriorated mechanical properties.

[0040] Comparative Example 3: Red brush bristles containing zinc cinnamate but without post-treatment The process was carried out exactly according to steps (1) to (3) of Example 1, including zinc cinnamate synthesis, masterbatch preparation, and spinning. The initial brush filaments were dried directly at 80°C for 1 hour without any alkaline or wet heat treatment as the finished product.

[0041] Phenomena and Results: The appearance of the bristles is the same as that in Example 1, with bright colors and smooth surfaces; The Zn content measured by ICP-OES was comparable to that in Example 1, indicating that zinc cinnamate was not lost. However, the antibacterial test showed an inhibition rate of only 55% (93% in Example 1). After placing the bristles in a simulated oral environment (37°C, pH=6.8 artificial saliva) for 7 days, the antibacterial rate slowly increased to 78%, indicating that zinc cinnamate itself has limited antibacterial properties and needs to be post-processed to release or transform it into substances with strong antibacterial activity (such as cinnamic acid, cinnamyl alcohol, or cinnamaldehyde) in order to exert a highly effective antibacterial effect.

[0042] Performance testing experiments: To comprehensively evaluate the effectiveness of the technical solution of this invention, key indicators such as thermal stability, antibacterial properties, mechanical properties, and appearance were tested on the bristle samples obtained in Examples 1–3 and Comparative Examples 1–3. The specific methods, results, and analysis are as follows: I. Testing Methods Determination of active ingredient retention rate: Cinnamic acid metal salt samples (Example, Comparative Example 3): The content of Zn, Ca or Mg elements was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and the retention rate of cinnamic acid metal salt was calculated according to the feeding ratio.

[0043] Cinnamyl alcohol samples (Comparative Examples 1 and 2): The amount of cinnamyl alcohol residue in the brush was quantified by gas chromatography-mass spectrometry (GC-MS) with internal standard method (benzyl alcohol as internal standard), and the retention rate was calculated.

[0044] Thermal stability test: Thermogravimetric analysis (TGA, nitrogen atmosphere, heating rate 10℃ / min) was used to record the cumulative mass loss rate of the sample at 260℃ during the process of heating from room temperature to 300℃, reflecting the thermal stability of the material at typical brush filament processing temperatures.

[0045] Antibacterial performance test: According to the international standard ISO 22196:2011 "Determination of antimicrobial activity of plastic products", Staphylococcus aureus (ATCC 6538) was used as the test species, and the inhibition rate was calculated after 24 hours of contact:

[0046] Where A represents the number of viable bacteria in the sample group and B represents the number of viable bacteria in the blank control group.

[0047] Mechanical property testing: The tensile strength of a single filament was tested according to GB / T 1040.5-2022 "Determination of tensile properties of plastics - Part 5: Unidirectional fiber reinforced composites", with a clamping distance of 50 mm and a tensile speed of 50 mm / min. Tensiles were tested in each group, and the average value was taken.

[0048] Appearance and color: Visually inspect the surface smoothness; use a colorimeter (CIELab* system) to confirm color consistency.

[0049] II. Test Results sample Active ingredient retention rate* TGA mass loss rate (260℃) Antibacterial rate (%) Tensile strength (MPa) Appearance Example 1 98.5% (Zn) 1.8% 93 385 Smooth surface, bright red Example 2 97.8% (Ca) 2.0% 90 370 Smooth surface, royal blue Example 3 99.1% (Mg) 1.6% 88 390 Smooth surface, milky white Comparative Example 1 3.0% (cinnamyl alcohol) 2.9% 12 402 Smooth surface, red (odorless) Comparative Example 2 41% (cinnamyl alcohol) 4.8% 48 265 The surface is rough and has a grainy texture. Comparative Example 3 98.7% (Zn) 1.7% 55 387 Smooth surface, bright red *Note: Retention rate = (Measured active ingredient content / Theoretical feed amount) × 100%; Metal salts are calculated as metal ions, and cinnamyl alcohol is directly quantified by GC-MS.

[0050] III. Results Analysis Thermal stability and component retention: The TGA mass loss rate of Examples 1–3 was only 1.6–2.0%, which is close to that of pure PA6 / PBT matrix (about 1.0–1.5%), indicating that the metal cinnamate salt is highly stable at 260°C and does not decompose or volatilize.

[0051] Although the total mass loss of Comparative Example 1 was only 2.9% (mainly from the volatilization of 3% cinnamyl alcohol), the cinnamyl alcohol retention rate was as low as 3.0%, proving that it could not withstand melt processing; Comparative Example 2 suffered a greater loss (4.8%) due to the degradation of the microcapsule wall material, and the protection efficiency was limited (retention rate of only 41%).

[0052] Conclusion: This invention fundamentally solves the high-temperature stability problem of thermosensitive cinnamyl alcohol by using metal cinnamate as a precursor.

[0053] Antibacterial properties: After post-treatment activation, Examples 1–3 showed an antibacterial rate as high as 88–93%, which was significantly better than the comparative examples; Although Comparative Example 3 had a high retention rate (98.7%), its antibacterial rate was only 55%, indicating that zinc cinnamate itself has limited antibacterial properties and must be converted into cinnamyl alcohol / aldehyde through post-treatment to exert a strong antibacterial effect. Comparative Examples 1 and 2 showed weak antibacterial effects due to the significant loss of active ingredients.

[0054] Conclusion: The "precursor + post-activation" strategy is the key to achieving highly efficient antibacterial activity.

[0055] Mechanical and appearance properties: The tensile strength of the examples (370–390 MPa) is comparable to that of pure PA6 / PBT (typically 380–410 MPa), indicating that the metal cinnamate salt did not impair the mechanical properties as a functional filler. Comparative Example 2 showed a 34% decrease in strength due to poor compatibility between the hydrophilic microcapsules and the hydrophobic polymer, resulting in interfacial defects. All embodiments showed that the brush filaments were brightly colored and had a smooth surface, demonstrating that the coexistence of pigments and cinnamate metal salts did not affect the processability.

[0056] Conclusion: This invention improves functionality while maintaining excellent usability and aesthetics.

[0057] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An antibacterial toothbrush bristle material, characterized in that, The bristle material comprises a thermoplastic polymer matrix and a metal cinnamate dispersed therein, wherein the metal cinnamate is at least one of zinc cinnamate, calcium cinnamate, or magnesium cinnamate.

2. The antibacterial toothbrush bristle material according to claim 1, characterized in that, The particle size of the cinnamate metal salt is 1-50 μm, and the content is 1-10 wt% of the total mass of the brush bristle material.

3. The antibacterial toothbrush bristle material according to claim 1 or 2, characterized in that, The thermoplastic polymer matrix is ​​selected from at least one of polyamide 6, polyamide 66, polybutylene terephthalate, or polypropylene.

4. The antibacterial toothbrush bristle material according to claim 1, characterized in that, The bristle material also includes pigments, which are inorganic pigments or high-temperature resistant organic pigments, giving the bristles any one of the colors red, orange, yellow, green, blue, indigo, purple, or black.

5. The method for preparing the antibacterial toothbrush bristle material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Cinnamic acid metal salt particles were prepared by reacting cinnamic acid with a metal salt precursor in a solvent. (2) The cinnamic acid metal salt particles, thermoplastic polymer and optional pigment are mixed evenly and then melt-extruded and granulated to obtain brush filament masterbatch; (3) The brush masterbatch is melt-spun to produce a primary brush bristle product; (4) The initial bristle product is subjected to alkaline wet heat post-treatment to activate the metal salt of cinnamic acid therein, so as to obtain toothbrush bristles with antibacterial activity.

6. The method for preparing the antibacterial toothbrush bristle material according to claim 5, characterized in that, The metal salt precursor in step (1) is zinc nitrate, calcium chloride or magnesium sulfate, the solvent is water or ethanol, the reaction temperature is 25-80℃, and the reaction time is 1-4 hours.

7. The preparation method according to claim 5, characterized in that, In step (2), the temperature of melt extrusion is 200-260℃, the screw speed is 50-120rpm, and the residence time of the material in the extruder does not exceed 5 minutes.

8. The method for preparing the antibacterial toothbrush bristle material according to claim 5, characterized in that, The post-treatment in step (4) is alkaline steam, immersion in a weak alkaline aqueous solution, or treatment with hot and humid air.

9. A toothbrush, characterized in that, Its bristles are made of the antibacterial toothbrush bristle material as described in any one of claims 1-4.

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