High-cleaning weather-resistant pbt-nylon composite toothbrush filament and preparation method thereof

Abstract

This application relates to the field of toothbrush bristle processing technology, and more specifically, to a high-cleaning-power, weather-resistant PBT-nylon composite toothbrush bristle and its preparation method, which is prepared from the following raw materials in weight percentages: nylon 25-45%, bifunctional reactive compatibilizer 2-4%, toughening agent 3-6%, nucleating agent 0.3-0.8%, ionic liquid plasticizer 1.0-2.5%, anti-hydrolysis agent 0.5-1%, nano-hydroxyapatite 0.5-1.5%, organosilicon surface modifier 0.3-0.7%, and the balance being PBT; the bifunctional reactive compatibilizer is prepared from the following raw materials in weight percentages: nylon 25-45%, bifunctional reactive compatibilizer 2-4%, toughening agent 3-6%, nucleating agent ... bifunctional reactive compatibilizer 3-6%, bifunctional reactive compatibilizer 0.3-0.7%, bifunctional reactive compatibilizer 0.0-2.5%, bifunctional reactive compatibilizer 0.5-1.5%, bifunctional reactive compatibilizer 0.5-1.5%, bifunctional reactive compatibilizer 0.3-0 The functional group reactive compatibilizer is composed of epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT; the nylon is a long-chain nylon with a number average molecular weight of 15,000-30,000 g / mo. The above formula solves the poor compatibility between PBT and nylon, resulting in improved flexibility and aging resistance of the high-cleaning, weather-resistant PBT-nylon composite toothbrush bristles. These bristles can resist the erosion of the complex oral environment, avoid aging and brittleness, extend service life, and also have elasticity and fracture resistance, reducing gum irritation during use.

Description

Technical Field

[0001] This application relates to the field of toothbrush bristle processing technology, and more specifically, to a weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power and its preparation method. Background Technology

[0002] Currently, most mid-to-low-end toothbrush products use PBT bristles. The raw material cost is significantly lower than that of nylon materials, and the processing technology is mature, the spinning temperature is stable, the breakage rate is low, and the production efficiency is high. Therefore, it has become the preferred material for toothbrush manufacturers.

[0003] However, as consumers increasingly demand durability from oral care products, the inherent defects of traditional PBT toothbrush bristles are becoming more apparent. The oral environment is a complex and dynamic system, and the bristles are in prolonged contact with saliva, surfactants in toothpaste, abrasives, and various organic solvents during use. Over time, the ester bonds in the PBT molecular chain are susceptible to hydrolysis and erosion by moisture and esterases in saliva. Simultaneously, polar solvents in toothpaste can penetrate into the amorphous regions of PBT, causing the material to swell and plasticize. This continuous chemical corrosion gradually destroys the integrity of the PBT molecular chain, leading to significant aging and brittleness in the toothbrush bristles after 2-3 months of use, manifested as a 30-40% decrease in fracture strength and a more than 50% reduction in impact toughness. Brittle bristles not only lose their elastic cleaning ability but are also prone to breakage and splitting, forming sharp ends that irritate the gum tissue. This lack of durability severely restricts the application of PBT materials in the high-end toothbrush market.

[0004] To improve the mechanical properties and lifespan of PBT toothbrush bristles, the industry primarily employs PBT / nylon blending modification or composite spinning processes. By introducing nylon components, their excellent abrasion resistance, impact resistance, and chemical resistance are leveraged to compensate for the shortcomings of PBT. However, PBT, as a non-polar crystalline polymer, is thermodynamically incompatible with the highly polar nylon resin, resulting in a lack of effective chemical bonding or intermolecular forces at their interface. During melt extrusion, the blend is prone to phase separation, forming an unstable island structure, leading to stress concentration and inefficient stress transfer at the interface. This weak interfacial bonding not only prevents the composite material from fully realizing the synergistic effects of its components but also exhibits early failure behaviors such as interfacial debonding and microcrack initiation in bending fatigue tests. Simultaneously, the interface easily becomes a channel for moisture and chemical substances to penetrate, further accelerating the aging rate of the material and creating a vicious cycle of performance degradation.

[0005] It is evident that the poor compatibility and low interfacial bonding strength of PBT / nylon composite materials lead to an imbalance in the mechanical properties of the product and poor process controllability, which restricts the performance improvement of toothbrush bristles and makes it difficult to meet the current market's urgent demand for environmentally friendly, durable, and safe oral care products. Summary of the Invention

[0006] To address the issues of poor compatibility and low interfacial bonding strength in PBT and nylon composite materials, this application provides a weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power and its preparation method.

[0007] In a first aspect, this application provides a weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power, employing the following technical solution: A high-cleaning-performance, weather-resistant PBT-nylon composite toothbrush bristle is prepared from the following raw materials by weight percentage: Nylon 25-45% Bifunctional reactive compatibilizer 2-4% Toughening agent 3-6% Nucleating agent 0.3-0.8% Ionic liquid plasticizer 1.0-2.5% Anti-hydrolysis agent 0.5-1% Nano-hydroxyapatite 0.5-1.5% Organosilicon surface modifier 0.3-0.7% The remainder is PBT; The bifunctional reactive compatibilizer is composed of epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT. The nylon is a long-chain nylon with a number-average molecular weight of 15,000-30,000 g / mol; PBT is a dicarboxylate-terminated polybutylene terephthalate oligomer with a number average molecular weight of 5000-10000 g / mol and a terminal carboxyl group content of 0.5-3 mmol / g.

[0008] By adopting the above technical solution, the poor compatibility between PBT and nylon is solved through the synergistic effect of each component. This improves the flexibility, tensile strength and aging resistance of the high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles, which can resist the erosion of the complex oral environment, avoid aging and brittleness, and extend the service life. At the same time, it has both elasticity and fracture resistance, and reduces gum irritation during use.

[0009] Among them, the bifunctional reactive compatibilizer composed of epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT can form stable chemical bonds with the terminal hydroxyl groups of PBT and the amide bonds of nylon, solving the problem of incompatibility between the two, reducing phase separation and island structure during melt processing, avoiding interfacial stress concentration and debonding problems, realizing the synergistic effect of PBT and nylon, improving the structural uniformity and interfacial bonding strength of composite materials, and enabling composite materials to give full play to the synergistic effect of PBT's processing stability and nylon's chemical resistance and wear resistance, solving the problems of unbalanced mechanical properties and poor process controllability in traditional blending systems.

[0010] The toughening agent and ionic liquid plasticizer work synergistically, combined with the impact resistance of long-chain nylon, to improve the flexibility and bending fatigue resistance of the composite material, thereby enhancing the impact toughness of the bristles and preventing the initiation of interfacial microcracks. The nucleating agent refines the PBT crystal structure, improving the material's rigidity and dimensional stability, so that the bristles maintain excellent elastic cleaning ability while also possessing strong resistance to fracture and bifurcation, reducing the risk of sharp tip formation, minimizing irritation to the gums, and meeting the safety requirements of oral care.

[0011] The anti-hydrolysis agent specifically inhibits the hydrolytic erosion of the ester bonds in the PBT molecular chain. Combined with the stabilizing effect of the ionic liquid plasticizer on the amorphous regions of PBT, it reduces the penetration and swelling of polar solvents and water in toothpaste. This solves the problem of traditional PBT bristles aging, becoming brittle, breaking, and splitting within 2-3 months after long-term use in the complex oral environment. Simultaneously, the anti-hydrolysis agent and the chemical resistance of nylon work synergistically to inhibit molecular chain degradation, prevent embrittlement and failure, and ensure that the bristles maintain their elastic cleaning ability in the complex oral environment for a long time.

[0012] Organosilicon surface modifiers form a dense protective film on the bristle surface, resisting the penetration and erosion of polar solvents and abrasives in toothpaste, and reducing material swelling and plasticization. Furthermore, the organosilicon surface modifiers optimize the wettability and smoothness of the bristle surface, reducing toothpaste residue adhesion, while enhancing the bristles' ability to remove dirt from between teeth, achieving a balance between high cleaning power and gentle care. Nano-hydroxyapatite not only improves bristle hardness and friction cleaning efficiency, but its biocompatibility also reduces oral mucosal irritation.

[0013] Preferably, the mass ratio of the epoxy-functionalized styrene-acrylate copolymer to the glycidyl methacrylate-grafted PBT is (1.5-2.5):1.

[0014] By adopting the above technical solution and optimizing the ratio of the two components, the epoxy-functionalized styrene-acrylate copolymer can fully exert its reactivity with the amide groups of nylon, while the glycidyl methacrylate-grafted PBT can achieve molecular chain entanglement with PBT. The two components synergistically optimize the interfacial bonding state between the two phases, more effectively suppress the phase separation of PBT and nylon, further improve the interfacial strength and mechanical property stability of the composite material, and at the same time ensure the smoothness of the melt spinning process, making the composite toothbrush bristles have better aging resistance, breakage resistance and cleaning adaptability.

[0015] Preferably, the ionic liquid plasticizer is one or a combination of two of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1-butyl-3-methylimidazolium hexafluorophosphate.

[0016] By employing ionic liquid plasticizers, which act on the amorphous regions of PBT, the interaction between ionic bonds and molecular chains enhances chain segment mobility, thereby improving the flexibility and processing flow of the composite material. Simultaneously, these ionic liquids exhibit stable chemical properties and excellent compatibility with the PBT / nylon system. They can synergistically enhance the material's weather resistance with anti-hydrolysis agents, avoiding the migration and volatility defects of traditional plasticizers. This ensures that the brush bristles maintain their elasticity and cleaning power even after long-term use, without affecting the stability of the spinning process.

[0017] Preferably, the nucleating agent is a compound of talc powder and sodium phenyl phosphate in a mass ratio of (0.5-2):1.

[0018] By adopting the above technical solution, talc, as an inorganic nucleating agent, can provide a large number of crystal nucleation sites, refine PBT crystal particles, and improve the material's rigidity and dimensional stability; sodium phenyl phosphate, as an organic nucleating agent, can regulate the PBT crystal structure, promote the formation of stable crystal forms, and enhance crystallization uniformity. The combination of these two in this ratio can regulate the PBT crystallization rate and morphology, avoiding the problems of uneven crystallization and imbalance between rigidity and toughness that exist with single nucleating agents. This results in composite toothbrush bristles possessing both excellent resistance to bending fatigue and structural stability, reducing the initiation of microcracks during use, further improving the bristles' resistance to breakage and splitting, while simultaneously ensuring the stability of the material's molten state during spinning and improving production efficiency.

[0019] Preferably, the toughening agent is a core-shell acrylate-silicone copolymer, wherein the core layer is silicone rubber and the shell layer is polymethyl methacrylate or polybutyl acrylate.

[0020] By adopting the above technical solution, the core layer of silicone rubber possesses excellent elasticity and fatigue resistance, absorbing energy when the material is subjected to external impact or bending, effectively inhibiting the propagation of microcracks. The shell layer of polymethyl methacrylate or polybutyl acrylate can form good interfacial compatibility with PBT and nylon substrates, ensuring that the toughening agent is uniformly dispersed in the composite material and avoiding performance degradation caused by phase separation. The toughening agent in this structure can improve the flexibility, bending fatigue resistance, and impact toughness of the composite toothbrush bristles, solving the problem that traditional toughening agents easily lead to a decrease in material rigidity. This allows the bristles to maintain sufficient cleaning hardness while being more resistant to repeated bending, reducing the risk of breakage and forking, further extending service life and reducing irritation to the gums.

[0021] Preferably, the core-shell acrylate-silicone copolymer has an average particle size of 80-300 nm, and the glass transition temperature (Tg) of the shell polymer is -30°C to 10°C.

[0022] By adopting the above technical solution, the toughening agent within this particle size range can be uniformly dispersed in the PBT / nylon composite system, avoiding stress concentration caused by excessively large particle size or agglomeration caused by excessively small particle size, and fully leveraging the elastic toughening effect of the core silicone rubber. The Tg range of the shell polymer ensures both interfacial affinity between the shell and the PBT / nylon substrate and imparts appropriate flexibility to the shell, enabling it to absorb energy in conjunction with the core layer when the bristles are bent under stress, effectively inhibiting the initiation and propagation of microcracks, improving the bending fatigue resistance and impact toughness of the composite toothbrush bristles, while avoiding the negative impact of toughening agent addition on bristle rigidity and improving bristle durability.

[0023] Preferably, the anti-hydrolysis agent is a compound of polymeric carbodiimide and bisoxazoline compound, with a mass ratio of (2-4):1.

[0024] By employing the above technical solution, polymeric carbodiimide preferentially reacts with the terminal carboxyl groups generated by PBT hydrolysis, inhibiting the continuous hydrolytic breakage of ester bonds. The bisoxazoline compound can crosslink with the terminal hydroxyl and carboxyl groups of PBT and the terminal amino groups of nylon, repairing molecular chain defects and constructing a stable crosslinked network structure, reducing the penetration and erosion of the material by moisture and polar solvents. The combination of these two components in this ratio can block the hydrolysis pathway of the PBT molecular chain at its source, while simultaneously enhancing the chemical stability of the material, delaying the aging and embrittlement process of the bristles in the complex oral environment, significantly improving the weather resistance and lifespan of the composite toothbrush bristles, and avoiding problems such as decreased fracture strength and deteriorated impact toughness caused by hydrolysis.

[0025] Preferably, the bisoxazoline compound is 2,2'-bis(2-oxazoline) or 1,3-phenylbisoxazoline.

[0026] By adopting the above technical solutions, both types of bisoxazoline compounds contain highly active oxazoline functional groups in their molecular structures. These functional groups can rapidly undergo ring-opening cross-linking reactions with the terminal hydroxyl and carboxyl groups produced by PBT hydrolysis and the terminal amino groups of nylon. This repairs the molecular chain structure damaged by hydrolysis and simultaneously constructs a dense cross-linking network, effectively preventing moisture, esterases, and polar components of toothpaste from penetrating into the material. Furthermore, their rigid molecular skeleton enhances the stability of the cross-linking network, preventing a decrease in bristle toughness due to excessive cross-linking. When compounded with polymeric carbodiimide, it can inhibit hydrolysis and provide repair and reinforcement, improving the hydrolysis resistance of the composite toothbrush bristles, delaying the aging and brittleness process, and extending their service life.

[0027] Preferably, the nano-hydroxyapatite is surface-modified with an aminosilane coupling agent, wherein the aminosilane coupling agent is one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0028] By adopting the above technical solution, the dispersion uniformity of nano-hydroxyapatite in the substrate is greatly improved, stress concentration caused by agglomeration is avoided, and the interfacial bonding strength between nano-hydroxyapatite and the substrate is enhanced. This not only leverages the hardness advantage to improve the friction cleaning power of the bristles, but also improves the material's resistance to bending fatigue, strengthens the weather resistance and durability of the composite toothbrush bristles, and does not affect the stability of subsequent spinning processing.

[0029] Preferably, the organosilicon surface modifier is an epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 200-500 g / eq and a viscosity of 50-500 cSt.

[0030] By adopting the above technical solution, the epoxy groups in epoxy-terminated polydimethylsiloxane can chemically bond with the amino groups of nylon and the terminal hydroxyl groups of PBT, enhancing the anchoring effect of the modifier on the surface of the composite material and preventing the loss of the modifier during use. Epoxy-terminated polydimethylsiloxane with a parameter range has both moderate reactivity and film-forming properties, which can form a smooth hydrophobic protective layer on the surface of the bristles, reducing the adsorption and adhesion of toothpaste residue and oral chemicals, and enhancing the frictional compatibility between the bristles and the tooth surface, thus improving cleaning efficiency. At the same time, its moderate viscosity ensures full compatibility with each component during melt spinning without affecting processing stability, further enhancing the weather resistance and cleaning power of the composite toothbrush bristles.

[0031] Secondly, this application provides a method for preparing weather-resistant PBT-nylon composite toothbrush bristles with high cleaning power, using the following technical solution: A method for preparing a weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power includes the following preparation steps: S1. PBT, nylon, bifunctional reactive compatibilizer, toughening agent, nucleating agent, anti-hydrolysis agent and nano hydroxyapatite are premixed at 240-250℃ to obtain a premix. S2. Add the premixed material from the main feed port of the twin-screw extruder, control the screw speed to 200-400 rpm, add the ionic liquid plasticizer and organosilicon surface modifier from the side feed port at the 5th-7th zone of the barrel, and carry out reactive melt blending. The melt temperature is 240-265℃, the melt residence time is 2-5 minutes, and then carry out melt spinning. The spinning temperature is 250-260℃, the spinning speed is 800-1500 m / min, and the nascent monofilament is obtained after cooling. S3. The nascent monofilaments are heat-set at 100-130℃ for 1-3 hours, and then naturally cooled at room temperature to obtain weather-resistant PBT-nylon composite toothbrush bristles with high cleaning power.

[0032] By adopting the above technical solutions, the premixing stage ensures the initial fusion of raw materials at 240-250℃. During twin-screw extrusion, ionic liquid plasticizers and organosilicon surface modifiers are added to the side feed port to prevent their high-temperature decomposition. The screw speed of 200-400rpm and the melt residence time of 2-5 minutes not only enhance the chemical bonding reaction between the bifunctional compatibilizer and PBT / nylon, but also inhibit the separation of the two phases. The spinning temperature of 250-260℃ and the spinning speed of 800-1500m / min match the melting characteristics of the materials, reducing the breakage rate. The heat setting at 100-130℃ for 1-3 hours refines the crystal structure and improves the dimensional stability and mechanical property consistency of the bristles. The resulting composite toothbrush bristles have excellent weather resistance, cleaning power and durability, and the process is highly controllable, making them suitable for large-scale production.

[0033] In summary, this application has the following beneficial effects: 1. This application utilizes a bifunctional reactive compatibilizer to chemically bond the epoxy functional groups of PBT with the terminal hydroxyl groups and nylon amide bonds, respectively, thereby improving the incompatibility between the two materials, eliminating phase separation and interfacial stress concentration, and achieving a synergistic effect of processing stability, chemical resistance, and wear resistance. Toughening agents, ionic liquid plasticizers, and long-chain nylon work together to significantly improve the material's flexibility and resistance to bending fatigue, reducing microcrack initiation. Nucleating agents refine the PBT crystal structure, enhancing rigidity, dimensional stability, and resistance to fracture and bifurcation, effectively preventing the formation of sharp ends. Anti-hydrolysis agents specifically inhibit the hydrolysis of PBT ester bonds, and combined with the stabilizing effect of ionic liquids on amorphous regions, synergistically improve the chemical resistance of nylon, solving the problem of traditional PBT brush filaments becoming brittle after 2-3 months of aging, and extending their service life. Organosilicon surface modifiers form a dense protective film that effectively resists toothpaste solvent erosion and optimizes surface smoothness, reduces residue adhesion, and enhances dirt removal ability; nano-hydroxyapatite improves hardness and friction cleaning efficiency while reducing oral mucosal irritation due to its excellent biocompatibility, achieving a balance between high cleaning power and gentle care. Detailed Implementation Example

[0034] The epoxy-functionalized styrene-acrylate copolymer is a product of BASF ADR-4368 from Germany.

[0035] The number-average molecular weight of PBT grafted with glycidyl methacrylate is 5000 g / mol, the terminal carboxyl group content is 0.5 mmol / g, the grafting rate is 2.5%, the epoxy equivalent is 100 g / eq, and the melt flow rate is 15 g / 10 min at 250℃ and 2.16 kg. Example

[0036] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power is prepared by the following method: S1. PBT674g, nylon250g, bifunctional reactive compatibilizer20g, toughening agent30g, nucleating agent3g, anti-hydrolysis agent5g and nano hydroxyapatite5g are premixed at 240℃ to obtain a premix. The nylon is a long-chain nylon with a number-average molecular weight of 15,000 g / mol; PBT is a dicarboxyl-terminated polybutylene terephthalate oligomer with a number average molecular weight of 5000 g / mol and a carboxyl-terminated content of 0.5 mmol / g. The mass ratio of epoxy-functionalized styrene-acrylate copolymer to glycidyl methacrylate-grafted PBT is 1.5:1. The nucleating agent is a mixture of talc and sodium phenyl phosphate in a mass ratio of 0.5:1; The toughening agent is a core-shell type acrylate-silicone copolymer, wherein the core layer is silicone rubber and the shell layer is polymethyl methacrylate, with an average particle size of 80 nm and a glass transition temperature (Tg) of -30 °C for the shell polymer. The anti-hydrolysis agent is a complex of polymeric carbodiimide and bis(2-oxazoline) compound (2,2'-bis(2-oxazoline)), with a mass ratio of 2:1. S2. Add the premixed material from the main feed port of the twin-screw extruder, control the screw speed to 200 rpm, add 10g of ionic liquid plasticizer (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) and 3g of organosilicon surface modifier from the side feed port at the 5th-7th zone of the barrel, and carry out reactive melt blending at a melting temperature of 240℃ and a melt residence time of 2 minutes. Then carry out melt spinning at a spinning temperature of 250℃ and a spinning speed of 800m / min. After cooling, the nascent monofilament is obtained. The organosilicon surface modifier is epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 200 g / eq and a viscosity of 50 cSt. S3. The nascent monofilaments are heat-set at 100°C for 1 hour, and then naturally cooled at room temperature to obtain weather-resistant PBT-nylon composite toothbrush bristles with high cleaning power.

[0037] The difference between Examples 2-3 and Example 1 lies in the types, amounts, and parameters of raw materials used to prepare the highly effective, weather-resistant PBT-nylon composite toothbrush bristles. Specific differences are shown in Table 1. Table 1. Raw material types, dosages, and parameters for preparing high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles. Example

[0038] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the mass ratio of epoxy-functionalized styrene-acrylate copolymer to the glycidyl methacrylate-grafted PBT is 1:1. Example

[0039] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the core agent is composed of talc and sodium benzoate in a mass ratio of 0.5:1. Example

[0040] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Example 1 is that the toughening agent is a hydrogenated styrene-butadiene block copolymer. Example

[0041] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the anti-hydrolysis agent is polymeric carbodiimide. Example

[0042] A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the nano-hydroxyapatite is surface-modified with an aminosilane coupling agent, which is γ-aminopropyltriethoxysilane.

[0043] Comparative Example 1 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Example 1 is that the bifunctional reactive compatibilizer is an epoxy-functionalized styrene-acrylate copolymer.

[0044] Comparative Example 2 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the bifunctional reactive compatibilizer is glycidyl methacrylate grafted with PBT.

[0045] Comparative Example 3 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the bifunctional reactive compatibilizer is replaced with maleic anhydride-grafted ethylene-octene copolymer.

[0046] Maleic anhydride-grafted ethylene-octene copolymer is the AMPLIFY™ GR 216 product from Dow Chemical Company, USA.

[0047] Comparative Example 4 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that the number average molecular weight of the long-chain nylon is 40,000.

[0048] Comparative Example 5 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Example 1 is that the number-average molecular weight of the dicarboxylated end-capped polybutylene terephthalate oligomer is 15,000.

[0049] Comparative Example 6 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that dibutyl phthalate is used instead of an equal amount of ionic liquid plasticizer.

[0050] Comparative Example 7 A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power. The difference between this embodiment and Embodiment 1 is that PBT is used instead of an equal amount of nucleating agent.

[0051] Tensile strength and elongation at break: Refer to GB / T 1040.3 and use a universal testing machine to test the tensile strength and elongation at break of a single brush filament; Bending fatigue life test: A single brush bristle is fixed at one end, and the other end is subjected to a 90° reciprocating bend at a frequency of 2Hz. The number of cycles at which the bristle breaks is recorded.

[0052] Aging resistance test: Toothbrush bristles were soaked in artificial saliva (pH 6.8, composition: NaCl 0.4g / L, KCl 0.4g / L, CaCl2·2H2O 0.795g / L, NaH2PO4·H2O 0.78g / L, Na2S·9H2O 0.005g / L) at 40℃ for 720h, followed by tensile strength test and bending fatigue life test. Cleaning power test: Toothbrushes were made from the toothbrush bristles obtained in Examples 1-8 and Comparative Examples 1-7; The artificial tooth model uses hydroxyapatite ceramic blocks to simulate teeth, and the surface is coated with a composite layer of β-cryptin dirt and tea stains; The test platform used an Oral-B electric toothbrush with a load of 200g, vibrations of 240 times / min, and an amplitude of ±15°, and was conducted in artificial saliva (pH 6.8) at 37°C.

[0053] Experimental period: Brush teeth twice a day for 2 minutes each time, for 7 days, for a total of 14 cycles; Stain removal rate: The Lab* value of the dental model was measured using a CIELAB spectrophotometer. Stain removal rate (%) = [1 - (ΔE_final / ΔE_initial)] * 100%, ΔE = √[(L1-L0)] 2 + (a1-a0) 2 + (b1-b0) 2 ] Calculate the change in ΔE, test the average removal rate ≥85%, and the removal rate of a single sample ≥80%.

[0054] L0: Initial brightness of the stain; the lower the value, the darker the color. a0: Red-green hue component; positive values ​​indicate redness, negative values ​​indicate greenness. b0: Yellow-blue hue component; positive values ​​indicate a yellowish tint, negative values ​​indicate a bluish tint. L1: Brightness after washing; a higher value indicates that the stains have been removed. a1, b1: Color components after brushing, close to the base color.

[0055] The experimental data are shown in Table 2: Table 2 Experimental data of Examples 1-8 and Comparative Examples 1-7

[0056] The experimental data above show that the high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles prepared by the formula in this application have good tensile strength, elongation at break, resistance to bending fatigue, aging resistance and cleaning power, which can meet the requirements of high-end toothbrushes for weather resistance, mechanical strength and cleaning power.

[0057] Compared with Example 1, Comparative Examples 1-7 showed a decrease in mechanical properties, a shortened fatigue life, a decrease in aging resistance, and a decrease in cleaning performance. This indicates that the synergistic effect of bifunctional reactive compatibilizers, specific PBT and nylon, ionic liquid plasticizers, and nucleating agents can greatly improve the compatibility of PBT and nylon, and simultaneously achieve the comprehensive performance of high mechanical strength, excellent weather resistance, and long-lasting cleaning power of toothbrush bristles.

[0058] Compared with Examples 1, Examples 4-7 show a decrease in tensile strength, elongation at break, flexural fatigue resistance, aging resistance, and cleaning power. This indicates that the present application can further improve the compatibility between PBT and nylon by using a specific ratio of bifunctional compatibilizer, core-shell toughening agent, compound anti-hydrolysis agent, and specific compound nucleating agent, thereby simultaneously achieving the comprehensive performance of high mechanical strength, excellent weather resistance, and long-lasting cleaning power of toothbrush bristles.

[0059] Compared with Example 1, Example 8 showed a slight improvement in tensile strength, flexural fatigue life and stain removal rate. This indicates that surface modification greatly improves the dispersion uniformity of nanoparticles in the PBT / nylon matrix through chemical bonding, further enhancing the mechanical strength, weather resistance and cleaning power of the toothbrush bristles.

[0060] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power, characterized in that, It is prepared from the following raw materials by weight percentage: Nylon 25-45% Bifunctional reactive compatibilizer 2-4% Toughening agent 3-6% Nucleating agent 0.3-0.8% Ionic liquid plasticizer 1.0-2.5% Anti-hydrolysis agent 0.5-1% Nano-hydroxyapatite 0.5-1.5% Organosilicon surface modifier 0.3-0.7% The remainder is PBT; The bifunctional reactive compatibilizer is composed of epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT. The nylon is a long-chain nylon with a number-average molecular weight of 15,000-30,000 g / mol; PBT is a dicarboxyl-terminated polybutylene terephthalate oligomer with a number average molecular weight of 5000-10000 g / mol and a terminal carboxyl group content of 0.5-3 mmol / g. The mass ratio of the epoxy-functionalized styrene-acrylate copolymer to the glycidyl methacrylate-grafted PBT is (1.5-2.5):1; The ionic liquid plasticizer is one or a combination of two of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1-butyl-3-methylimidazolium hexafluorophosphate. The nucleating agent is a compound of talc powder and sodium phenyl phosphate in a mass ratio of (0.5-2):1; The toughening agent is a core-shell type acrylate-silicone copolymer, wherein the core layer is silicone rubber and the shell layer is polymethyl methacrylate or polybutyl acrylate. The core-shell type acrylate-organosilicon copolymer has an average particle size of 80-300 nm, and the glass transition temperature Tg of the shell polymer is -30℃ to 10℃. The anti-hydrolysis agent is a compound of polymeric carbodiimide and bisoxazoline compound, with a mass ratio of (2-4):

1.

2. The high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: The nano-hydroxyapatite is surface-modified with an aminosilane coupling agent, which is one of γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

3. The high-cleaning-power, weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: The organosilicon surface modifier is an epoxy-terminated polydimethylsiloxane with an epoxy equivalent of 200-500 g / eq and a viscosity of 50-500 cSt.

4. A method for preparing weather-resistant PBT-nylon composite toothbrush bristles with high cleaning power as described in any one of claims 1-3, characterized in that, The preparation steps include the following: S1. PBT, nylon, bifunctional reactive compatibilizer, toughening agent, nucleating agent, anti-hydrolysis agent and nano hydroxyapatite are premixed at 240-250℃ to obtain a premix. S2. Add the premixed material from the main feed port of the twin-screw extruder, control the screw speed to 200-400 rpm, add the ionic liquid plasticizer and organosilicon surface modifier from the side feed port at the 5th-7th zone of the barrel, and carry out reactive melt blending. The melt temperature is 240-265℃, the melt residence time is 2-5 minutes, and then carry out melt spinning. The spinning temperature is 250-260℃, the spinning speed is 800-1500 m / min, and the nascent monofilament is obtained after cooling. S3. The nascent monofilaments are heat-set at 100-130℃ for 1-3 hours, and then naturally cooled at room temperature to obtain weather-resistant PBT-nylon composite toothbrush bristles with high cleaning power.

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