Weather-proof PBT-nylon composite toothbrush filament with high cleaning power and preparation method of weather-proof PBT-nylon composite toothbrush filament

Abstract

The invention relates to the technical field of toothbrush bristle processing, in particular to weather-proof PBT-nylon composite toothbrush filaments with high cleaning power and a preparation method of the high-cleaning power weather-proof PBT-nylon composite toothbrush filaments. The PBT / nylon composite material is prepared from the following raw materials in percentage by weight: 25-45% of nylon, 2-4% of a bifunctional reactive compatilizer, 3-6% of a flexibilizer, 0.3-0.8% of a nucleating agent, 1.0-2.5% of an ionic liquid plasticizer, 0.5-1% of an anti-hydrolysis agent, 0.5-1.5% of nano-hydroxyapatite, 0.3-0.7% of an organic silicon surface modifier and the balance of PBT. The bifunctional reactive compatilizer is prepared from an epoxy functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT (Polybutylene Terephthalate); the nylon is long-chain nylon and has a number-average molecular weight of 15000-30000 g / mo, the problem of poor compatibility of PBT and nylon is solved through the formula, so that the prepared weather-resistant PBT-nylon composite toothbrush filament with high cleaning power is improved in flexibility and aging resistance, can resist erosion of a complex oral environment, avoids aging and embrittlement, is prolonged in service life, has elasticity and fracture resistance, and is suitable for popularization and application in the fields of oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning, oral cavity cleaning and the like. And gingival stimulation is reduced in the use process.

Description

TECHNICAL FIELD

[0001] The present application relates to the toothbrush bristle processing technical field, more specifically, to a high-cleaning-force weather-resistant PBT-nylon composite toothbrush filament and a preparation method thereof. BACKGROUND

[0002] At present, most of the low-end toothbrush products use PBT brush filaments, the raw material cost is obviously superior to that of nylon materials, the processing technology is mature, the spinning temperature is stable, the breakage rate is low, and the production efficiency is high, so it becomes the first choice of toothbrush manufacturing enterprises.

[0003] However, with the continuous improvement of consumers' requirements for the durability of oral care products, the inherent defects of traditional PBT toothbrush filaments are increasingly prominent. The oral environment is a complex dynamic system, and the brush filaments are in long-term contact with saliva, surfactants, abrasives and various organic solvents in toothpaste during use. The ester bond in the molecular chain of PBT material is easily hydrolyzed by water and esterase in saliva during long-term use, and the polar solvent components in toothpaste can penetrate into the amorphous region of PBT, causing the material to swell and plasticize. This continuous chemical corrosion will gradually damage the integrity of the PBT molecular chain, causing the toothbrush filaments to become brittle after 2-3 months of use, with a 30-40% decrease in breaking strength and a more than 50% decrease in impact toughness. The brittle brush filaments not only lose their elastic cleaning ability, but are also more prone to breaking and branching, forming sharp ends that irritate the gum tissue. This lack of durability has seriously restricted the application of PBT materials in the high-end toothbrush field.

[0004] In order to improve the mechanical properties and service life of PBT toothbrush filaments, the industry mainly uses PBT / nylon blending modification or composite spinning process. By introducing nylon components, the excellent wear resistance, impact resistance and chemical resistance of nylon can make up for the shortcomings of PBT. However, PBT is a non-polar crystalline polymer, and the strong polar nylon resin is not compatible in thermodynamics, and the interface lacks effective chemical bonding or intermolecular forces. The blend is prone to phase separation during melt extrusion, forming an unstable island structure, resulting in low stress transmission efficiency at the interface. This weak interface bonding not only prevents the composite material from fully utilizing the performance synergy of each component, but also exhibits early failure behaviors such as interface debonding and micro-crack initiation in the bending fatigue test. At the same time, the two-phase interface is prone to be a penetration channel for water and chemicals, further accelerating the aging rate of the material, forming a vicious cycle of performance degradation.

[0005] It can be seen that the poor compatibility and low interface bonding strength of PBT / nylon composite materials will lead to unbalanced mechanical properties of the product, poor process controllability, and restrict the performance improvement of toothbrush filament products, which also makes it difficult to meet the urgent needs of the current market for environmentally friendly, durable and safe oral care products. SUMMARY

[0006] In order to solve the problem of poor compatibility and low interface bonding strength of PBT and nylon composite, the application provides a weather-resistant PBT-nylon composite toothbrush filament with high cleaning power and a preparation method thereof.

[0007] In a first aspect, the application provides a weather-resistant PBT-nylon composite toothbrush filament with high cleaning power, which adopts the following technical scheme: A weather-resistant PBT-nylon composite toothbrush filament with high cleaning power is prepared from the following raw materials in 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% silicone surface modifier 0.3-0.7% the rest is PBT; The bifunctional reactive compatibilizer is composed of epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT; The nylon is long-chain nylon with a number average molecular weight of 15000-30000 g / mol; PBT is a dicarboxyl-terminated polybutylene terephthalate oligomer with a number average molecular weight of 5000-10000 g / mol and a carboxyl content of 0.5-3 mmol / g.

[0008] By adopting the above technical scheme, through the synergistic effect of each component, the poor compatibility of PBT and nylon is solved, the flexibility, breaking strength and aging resistance of the prepared weather-resistant PBT-nylon composite toothbrush filament with high cleaning power are improved, the complex oral environment erosion is resisted, the aging and brittleness are avoided, the service life is prolonged, and at the same time, the elasticity and anti-fracture property are combined, and the gum irritation during use is reduced.

[0009] The bifunctional reactive compatibilizer is composed of an epoxy-functionalized styrene-acrylate copolymer and glycidyl methacrylate grafted PBT. The epoxy functional group can form a stable chemical bond with the terminal hydroxyl group of PBT and the amide bond of nylon, solving the incompatibility problem of the two, reducing the phase separation and island structure in melt processing, avoiding the problem of interface stress concentration and debonding, realizing the synergistic effect of PBT and nylon, improving the structural uniformity and interface bonding strength of the composite material, making the composite material fully play the synergistic effect of the processing stability of PBT and the chemical resistance and wear resistance of nylon, and solving the problems of unbalanced mechanical properties and poor process controllability of traditional blending system.

[0010] The synergistic effect of the toughening agent and the ionic liquid plasticizer, combined with the impact resistance of the long-chain nylon, improves the flexibility and bending fatigue resistance of the composite material, improves the impact toughness of the brush wire, and avoids the initiation of interface microcracks; the nucleating agent refines the PBT crystalline structure, improves the material rigidity and dimensional stability, so that the brush wire not only has excellent elastic cleaning ability, but also has strong anti-fracture and anti-forking performance, the risk of forming sharp ends is reduced, the stimulation to the gums is reduced, and the safety requirements of oral care are met.

[0011] The anti-hydrolysis agent specifically inhibits the hydrolysis of the ester bond of the PBT molecular chain, and cooperates with the stabilizing effect of the ionic liquid plasticizer on the amorphous region of PBT to reduce the penetration and swelling of polar solvents and moisture in toothpaste, so that the brush wire can be used in the complex oral environment for a long time, and the problems of aging and brittleness of traditional PBT brush wire within 2-3 months are solved. At the same time, the anti-hydrolysis agent and the chemical resistance of nylon are synergistic, the molecular chain degradation is inhibited, the embrittlement failure is avoided, and the elastic cleaning ability of the brush wire in the complex oral environment is ensured for a long time.

[0012] The organic silicon surface modifier forms a dense protective film on the surface of the brush wire to resist the penetration and erosion of polar solvents and abrasives in toothpaste, and reduces the swelling and plasticization of the material. The organic silicon surface modifier optimizes the wettability and smoothness of the brush wire surface, reduces the residual attachment of toothpaste, and at the same time improves the peeling ability of the brush wire to dirt in tooth gaps, realizing the combination of high cleaning power and gentle care. Nano-hydroxyapatite not only improves the hardness and friction cleaning efficiency of the brush wire, but also reduces the stimulation to the oral mucosa due to its biocompatibility.

[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 scheme, the dosage ratio of the two is optimized, so that the epoxy functionalized styrene-acrylate copolymer can fully exert the reactivity with the amide group of nylon, the glycidyl methacrylate grafted PBT can realize molecular chain entanglement with PBT, and the combination state of the two-phase interface is optimized, which more efficiently inhibits the phase separation of PBT and nylon, further improves the interface strength and mechanical property stability of the composite material, and ensures the smoothness of the melting spinning process, so that the aging resistance, fracture resistance and cleaning adaptability of the composite toothbrush filament are better.

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

[0016] By using the ionic liquid plasticizer, the chain segment movement ability is improved by the interaction of ionic bond and molecular chain in the amorphous region of PBT, and the flexibility and processing fluidity of the composite material are improved. At the same time, the ionic liquid has excellent chemical stability and compatibility with the PBT / nylon system, can enhance the weather resistance of the material in cooperation with the hydrolysis-resistant agent, avoid the defects of easy migration and volatilization of traditional plasticizers, ensure that the toothbrush filament still maintains elasticity and cleaning force after long-term use, and does not affect the stability of the spinning process.

[0017] Preferably, the nucleating agent is compounded by talc and sodium phenylphosphate in a mass ratio of (0.5-2):1.

[0018] By adopting the above technical scheme, talc as an inorganic nucleating agent can provide a large number of crystal nucleus sites, refine PBT crystalline particles, and improve the rigidity and dimensional stability of the material; sodium phenylphosphate as an organic nucleating agent can regulate the PBT crystal structure, promote the formation of stable crystal form, and enhance the crystallization uniformity. The two are compounded in this ratio to regulate the PBT crystallization rate and crystallization morphology, avoid the problems of uneven crystallization, rigidity and toughness imbalance of single nucleating agent, make the composite toothbrush filament have excellent bending fatigue resistance and structural stability, reduce the initiation of microcracks during use, further improve the fracture resistance and anti-forking ability of the toothbrush filament, and ensure the stability of the material melting state during the spinning process, thereby improving the production efficiency.

[0019] Preferably, 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.

[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 a glass transition temperature (Tg) of -30°C to 10°C for the shell polymer.

[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 on 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.

2. The high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: The mass ratio of the epoxy-functionalized styrene-acrylate copolymer to the glycidyl methacrylate-grafted PBT is (1.5-2.5):

1.

3. The high-cleaning-power, weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: 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.

4. The high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: The nucleating agent is a compound of talc and sodium phenyl phosphate in a mass ratio of (0.5-2):

1.

5. The high-cleaning-power, weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: 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.

6. The high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles according to claim 1, characterized in that: 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.

7. The high-cleaning-power weather-resistant PBT-nylon composite toothbrush bristles according to claim 6, characterized in that: The anti-hydrolysis agent is a compound of polymeric carbodiimide and bisoxazoline compound, with a mass ratio of (2-4):

1.

8. 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.

9. 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.

10. A method for preparing a weather-resistant PBT-nylon composite toothbrush bristle with high cleaning power as described in any one of claims 1-9, 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 through 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 through 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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