A lightweight interior material made of bamboo fiber modified polypropylene with aging resistance and its preparation method

Abstract

This invention relates to the field of modified polypropylene composite materials, and discloses an aging-resistant bamboo fiber modified polypropylene lightweight interior material and its preparation method. This aging-resistant bamboo fiber modified polypropylene lightweight interior material is prepared from the following parts by weight: 30-40 parts polypropylene, 45-60 parts bamboo fiber, 4-6 parts modified titanate coupling agent, 0.3-1 parts silver-loaded nanomaterials, and 5-15 parts filler. The aging-resistant bamboo fiber modified polypropylene lightweight interior material provided by this invention, by using a modified titanate coupling agent containing hindered phenolic antioxidant groups, pyrophosphate coupling groups, and neopentyl glycol chelate rings within the molecule, and adding silver-loaded nanomaterials to composite with polypropylene, results in an interior material that possesses excellent interfacial bonding strength, long-lasting resistance to heat and oxygen aging and photo-oxidative aging, high-efficiency antibacterial ability, and lightweight characteristics, allowing for long-term application in the harsh environments of automotive interiors.

Description

Technical Field

[0001] This invention relates to the field of modified polypropylene composite materials, and in particular to an aging-resistant bamboo fiber modified polypropylene lightweight interior material and its preparation method. Background Technology

[0002] Bamboo fiber, as a natural renewable resource, has advantages such as high specific strength, wide availability, and biodegradability. In recent years, it has been gradually applied to the reinforcement and modification of composite materials for automotive interiors to replace some petroleum-based materials, thereby achieving the goals of lightweighting and greening.

[0003] On the one hand, bamboo fiber is rich in polar hydroxyl groups on its surface, resulting in extremely poor compatibility with the polymer matrix. This makes fiber dispersion in the matrix difficult, leading to weak interfacial bonding and low stress transfer efficiency, ultimately resulting in insufficient impact strength and dimensional stability of the composite material. To address the interfacial compatibility issue, existing technologies often employ coupling agents to treat the surface of bamboo fiber. However, these coupling agents have a single structural function, only addressing the coupling problem and failing to prevent interfacial aging and degradation of the composite material under long-term thermo-oxidative and photo-oxidative environments. Automotive interior parts are often subjected to prolonged high temperatures and strong ultraviolet radiation. The hemicellulose and lignin components in bamboo fiber are easily degraded under thermo-oxidative conditions, causing fiber discoloration and yellowing, as well as matrix chain breakage and embrittlement. Existing solutions typically involve adding antioxidants to the formulation for macroscopic protection. However, these free antioxidants are easily lost from the matrix during long-term use, failing to form a continuous and effective free radical trapping barrier at weak points in the composite interface, leaving interfacial aging and cracking problems prominent.

[0004] On the other hand, bamboo fiber contains sugars and proteins, making it prone to mold growth and odor in humid and hot environments, severely limiting its application in interior trim. While existing technologies can achieve highly efficient antibacterial effects by introducing nano-silver ions, exposed nano-silver will produce a photocatalytic effect in the presence of ultraviolet light and oxygen, generating reactive oxygen free radicals, which will accelerate the photo-oxidative aging of the polymer matrix and the bamboo fiber itself. Although other non-silver-based antibacterial agents can avoid the photocatalytic problem, their antibacterial efficiency is far lower than that of silver-based antibacterial agents. At the same time, conventional simple mixing methods of nano-silver will further affect the compatibility between the components.

[0005] Therefore, there is an urgent need for a lightweight interior material made of bamboo fiber modified polypropylene that can simultaneously address interfacial compatibility, interfacial oxidation resistance, and long-term silver ion anchoring at the molecular level, while also possessing strong aging resistance and antibacterial properties. Summary of the Invention

[0006] The technical problem to be solved by this invention is that the existing technology has the disadvantage of insufficient aging resistance and antibacterial properties of bamboo fiber composite materials. To this end, we propose an aging-resistant bamboo fiber modified polypropylene lightweight interior material and its preparation method that can simultaneously solve the problems of interfacial compatibility, interfacial oxidation resistance and long-term silver ion anchoring at the molecular level.

[0007] To achieve the above objectives, this application adopts the following technical solution: an aging-resistant bamboo fiber modified polypropylene lightweight interior material, which is prepared by the following parts by weight of materials: 30-40 parts of polypropylene, 45-60 parts of bamboo fiber, 4-6 parts of modified titanate coupling agent, 0.3-1 parts of silver-loaded nanomaterials and 5-15 parts of filler.

[0008] The modified titanate coupling agent has the structure shown in Formula A:

[0009] ;

[0010] Where R= .

[0011] In this invention, the addition of modified titanate coupling agent can simultaneously achieve multiple functions. On the one hand, the pyrophosphate groups chemically condense with the hydroxyl groups on the surface of bamboo fiber to form a stable interfacial bridge, and the long-chain alkyl groups are chemically bonded to the polypropylene matrix, significantly improving the interfacial bonding force and compatibility between the fiber and the matrix, and increasing the tensile strength and impact toughness of the material. On the other hand, the retained P-OH and pyrophosphate multidentate coordination structure can anchor the silver-loaded nanomaterials inside the material through chemical complexation, achieving uniform dispersion, slow release and long-lasting antibacterial effect of silver ions, avoiding the agglomeration problem of silver particles in melt processing and the photocatalytic problem caused by exposure.

[0012] Preferably, the polypropylene is selected from homopolymer polypropylene or copolymer polypropylene with a melt flow index of 10-15 g / 10 min;

[0013] The bamboo fiber is selected from at least one of bamboo pulp fiber and bamboo virgin fiber;

[0014] The silver-loaded nanomaterial is selected from at least one of silver-loaded zirconium phosphate, silver-loaded zeolite, and silver-loaded glass.

[0015] The filler is selected from at least one of talc, calcium carbonate, wollastonite, and mica powder.

[0016] Preferably, the bamboo fiber has a length of 0.5-3 mm and a diameter of 20-80 μm;

[0017] The silver-loaded nanomaterial has a silver content of 1-5 wt% and an average particle size of 20-200 nm.

[0018] The average particle size of the filler is 1-10 μm.

[0019] Preferably, the modified titanate coupling agent is prepared by the following steps:

[0020] (1) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid reacts with 1,6-hexanediol under the action of a catalyst to prepare hindered phenolic alcohol;

[0021] (2) After the hindered phenol alcohol and n-octanol are mixed, they are reacted with phosphorus pentoxide to prepare mixed pyrophosphate ester;

[0022] (3) Mixed pyrophosphate and tetraisopropyl titanate were reacted under anhydrous conditions to prepare titanium pyrophosphate intermediate;

[0023] (4) The titanium pyrophosphate intermediate is reacted with neopentyl glycol to prepare the modified titanate coupling agent.

[0024] Preferably, the specific method of step (1) is as follows: 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 1,6-hexanediol and organic solvent are added to a reactor, the catalyst is added after stirring and dissolving, and the reaction is refluxed at 100-130°C for 6-12 hours. After the reaction is completed, the mixture is washed and dried to obtain hindered phenol alcohol.

[0025] The catalyst is p-toluenesulfonic acid, and the amount of catalyst used is 0.5-2% of the molar amount of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid;

[0026] The organic solvent is selected from toluene or cyclohexane;

[0027] The molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to 1,6-hexanediol is 1:2.5-4.

[0028] Preferably, the specific method of step (2) is as follows: In a reactor, hindered phenol alcohol and n-octanol are added and stirred until evenly mixed. Phosphorus pentoxide is added at 40-55°C, and the temperature is raised to 70-85°C for 3-5 hours to mature. Then deionized water is added and hydrolyzed at 50-60°C for 1-2 hours. After vacuum distillation, mixed pyrophosphate is obtained.

[0029] The amount of deionized water added is 2-5% of the mass of phosphorus pentoxide;

[0030] The molar ratio of the hindered phenol alcohol, n-octanol and phosphorus pentoxide is 1:(3-3.5):(1.5-1.8).

[0031] In this invention, a modified titanate coupling agent is intramolecularly grafted with a hindered phenolic structure, which is covalently linked to the pyrophosphate end via a flexible alkyl chain and anchored to the coupling agent molecule by chemical bonds. Under the action of the coupling agent, it binds to the interface region between bamboo fiber and polypropylene. The hindered phenolic group can capture free radicals generated by thermal and photo-oxidative aging near the interface. Combined with the auxiliary antioxidant function of the pyrophosphate group itself, it can form a fixed-point continuous protection on the interface, fundamentally inhibiting the problem of interface aging and cracking, and significantly improving the long-term thermal and photo-oxidative stability of interior materials.

[0032] Preferably, the specific method of step (3) is as follows: In a reactor, a mixture of pyrophosphate and solvent is added, stirred and dissolved, and then tetraisopropyl titanate is added. Under nitrogen protection, the temperature is raised to 60-90°C, the reaction is carried out for 2-4 hours, and the titanium pyrophosphate intermediate is obtained by vacuum distillation.

[0033] The solvent is selected from toluene or xylene;

[0034] The molar ratio of the mixed pyrophosphate and tetraisopropyl titanate is 2.05-2.2:1.

[0035] Preferably, the specific method of step (4) is as follows: In a reactor, titanium pyrophosphate intermediate and neopentyl glycol are added, the temperature is raised to 80-100℃ and reacted for 2-4 hours, and after cooling, the mixture is filtered and distilled under reduced pressure to obtain the modified titanate coupling agent.

[0036] The molar ratio of the titanium pyrophosphate intermediate to neopentyl glycol is 1:0.95-1.1.

[0037] In this invention, neopentyl glycol in the modified titanate coupling agent, as a chelating diol, can form a six-membered chelate ring structure with titanium atoms containing two methyl side groups. On the one hand, this structure endows the coupling agent with excellent hydrolytic stability, making it less prone to deactivation during the processing of water-containing bamboo fibers and high-humidity environments, ensuring consistent coupling efficiency. On the other hand, the two methyl groups in this structure can form a hydrophobic shielding space, which, after complexing with silver-loaded nanomaterials, can physically isolate the direct contact between ultraviolet light and oxygen on the complexed silver particles, effectively inhibiting the photocatalytic generation of reactive oxygen species in the silver-loaded nanomaterials, thus resolving the contradiction between antibacterial function and anti-aging at the structural level.

[0038] This invention also provides a method for preparing any one of the above-mentioned aging-resistant bamboo fiber modified polypropylene lightweight interior materials, comprising the following steps:

[0039] (1) Dry bamboo fiber under vacuum at 70-100℃, then soak it in sodium hydroxide solution for 20-60 minutes, wash it with water until neutral, and then dry it under vacuum at 70-100℃ again.

[0040] (2) The dried bamboo fiber, modified titanate coupling agent and silver-loaded nanomaterials are premixed in a high-speed mixer at 60-80℃ for 5-10 minutes, and then polypropylene and filler are added and mixed for 2-5 minutes to obtain the premix.

[0041] (3) The premixed material is melt-blended in a twin-screw extruder, stretched, cooled and granulated, and then injection molded to obtain the aging-resistant bamboo fiber modified polypropylene lightweight interior material.

[0042] Preferably, the vacuum drying conditions in step (1) are: temperature 80-100℃, drying time 3-4 hours; and the mass concentration of the sodium hydroxide solution is 1-5%.

[0043] Preferably, in step (2), the modified titanate coupling agent is first dissolved in an ethanol / water mixed solvent at a concentration of 1-3 wt%, and then uniformly applied to the surface of bamboo fiber by spraying before premixing.

[0044] The conditions for the twin-screw extruder in step (3) are as follows: feeding section temperature 160-170℃, melt mixing section temperature 180-195℃, metering section temperature 190-200℃, extrusion die temperature 190-200℃, and screw speed 200-400rpm.

[0045] The technical effects and advantages of this invention are as follows:

[0046] (1) The aging-resistant bamboo fiber modified polypropylene lightweight interior material provided by the present invention adopts a modified titanate coupling agent containing hindered phenol antioxidant groups, pyrophosphate coupling groups and neopentyl glycol chelate rings in the molecule, and adds silver-loaded nanomaterials to polypropylene composite. The resulting interior material has excellent interfacial bonding strength, long-term heat and oxygen resistance and photo-oxidation resistance, high-efficiency antibacterial ability and lightweight characteristics, and can be used for a long time in the harsh environment of automotive interior.

[0047] (2) The lightweight interior material of bamboo fiber modified polypropylene provided by the present invention uses neopentyl glycol in the modified titanate coupling agent as a chelating diol, which can form a six-membered chelate ring structure with titanium atoms containing two methyl side groups. On the one hand, this structure gives the coupling agent excellent hydrolytic stability, making it less prone to deactivation in the processing of water-containing bamboo fiber and high-humidity environment, ensuring the consistency of coupling efficiency. On the other hand, the two methyl groups of this structure can form a hydrophobic shielding space, which can physically isolate the direct contact between ultraviolet light and oxygen on the complexed silver particles after complexing with silver nanomaterials, effectively inhibiting the photocatalytic generation of active oxygen in silver nanomaterials, and solving the contradiction between antibacterial function and anti-aging from the structural level.

[0048] (3) The aging-resistant bamboo fiber modified polypropylene lightweight interior material provided by the present invention has a modified titanate coupling agent with an intramolecularly grafted hindered phenolic structure. It is covalently connected to the pyrophosphate end through a flexible alkyl chain and anchored to the coupling agent molecule through chemical bonds. Under the action of the coupling agent, it is combined with the interface region of bamboo fiber and polypropylene. The hindered phenolic group can capture free radicals generated by thermal and photo-oxidative aging near the interface. Combined with the auxiliary antioxidant function of the pyrophosphate group itself, it can form a fixed-point continuous protection on the interface, fundamentally inhibiting the problem of interface aging and cracking, and significantly improving the long-term thermal and photo-oxidative stability of the interior material.

[0049] (4) The aging-resistant bamboo fiber modified polypropylene lightweight interior material provided by the present invention can achieve multiple functions simultaneously by adding modified titanate coupling agent. On the one hand, the pyrophosphate group and the hydroxyl group on the surface of bamboo fiber form a stable interface bridge through chemical condensation. The long-chain alkyl group and the polypropylene matrix are chemically bonded, which significantly improves the interfacial bonding force and compatibility between the fiber and the matrix, and improves the tensile strength and impact toughness of the material. On the other hand, the retained P-OH and pyrophosphate multidentate coordination structure can anchor the silver-loaded nanomaterials in the material through chemical complexation, so as to achieve uniform dispersion, slow release and long-term antibacterial effect of silver ions, and avoid the problem of silver particles agglomeration in melt processing and the photocatalytic problem caused by exposure.

[0050] (5) The aging-resistant bamboo fiber modified polypropylene lightweight interior material provided by the present invention achieves weight reduction through the synergistic combination of high bamboo fiber filling amount, polypropylene, silver-loaded nanomaterials and modified titanate coupling agent. At the same time, the silver-loaded nanomaterials and hindered phenolic groups provide synergistic protection from the two dimensions of antibacterial and anti-oxidation, respectively, so that the overall service life of the material under the coupled aging conditions of multiple factors such as damp heat and light is significantly extended compared with traditional bamboo fiber polypropylene composite materials. Attached Figure Description

[0051] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0052] Figure 1 This is a flowchart illustrating the preparation process of the aging-resistant bamboo fiber modified polypropylene lightweight interior material of this invention.

[0053] Figure 2 The reaction formula and structural formula for the preparation of the modified titanate coupling agent of the present invention are shown below.

[0054] Figure 3 This is the mass spectrum of the modified titanate coupling agent of the present invention;

[0055] Figure 4 The image shows the infrared spectrum of the modified titanate coupling agent of this invention. Detailed Implementation

[0056] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0057] In the specific embodiments of this invention, the polypropylene is homopolymer polypropylene with a melt flow index of 12 g / 10 min, purchased from Jiangsu Lixing Youxin Materials Co., Ltd.; the bamboo fiber is bamboo virgin fiber with a length of 2 mm and a diameter of 20-80 μm; the silver-loaded nanomaterial is silver-loaded zirconium phosphate with a silver content of 3 wt% and an average particle size of 80 nm; the silver-loaded zeolite has a silver content of 2 wt% and an average particle size of 80 nm; the remaining reagents and equipment are conventional reagents and equipment in this technical field.

[0058] Preparation of modified titanate coupling agents

[0059] The modified titanate coupling agent was prepared by the following steps:

[0060] (1) In a 500 mL three-necked flask equipped with a stirrer, thermometer, water separator and reflux condenser, add 0.1 mol of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.3 mol of 1,6-hexanediol and 150 mL of toluene, stir to dissolve, add 0.0015 mol of p-toluenesulfonic acid, heat to 110 °C and reflux to separate water, react for 8 hours, cool to room temperature after the reaction is completed, wash, dry and distill under reduced pressure to obtain 37.2 g of a pale yellow viscous liquid hindered phenol alcohol;

[0061] (2) In a 250mL three-necked flask equipped with a stirrer, thermometer and nitrogen inlet, add 0.05mol of hindered phenol alcohol and 0.15mol of n-octanol, stir and mix evenly, control the temperature at 50℃, add 0.09mol of phosphorus pentoxide in batches, add in about 30 minutes, raise the temperature to 80℃, ripen the reaction for 4 hours, then add 0.45g of deionized water, hydrolyze at 55℃ for 1.5 hours, after the reaction is completed, remove excess n-octanol by vacuum distillation at 90℃, and obtain 52.6g of amber viscous liquid mixed pyrophosphate;

[0062] (3) In a 250 mL three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel and nitrogen inlet, add 0.21 mol of mixed pyrophosphate and 100 mL of anhydrous toluene, stir to dissolve, add 0.1 mol of tetraisopropyl titanate under nitrogen protection, heat to 80 °C, continue to react for 3.5 hours, and obtain a dark amber transparent liquid titanium pyrophosphate intermediate after vacuum distillation;

[0063] (4) In a 250 mL three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel and nitrogen inlet, add 0.1 mol of titanium pyrophosphate intermediate, 0.1 mol of neopentyl glycol and 20 mL of anhydrous toluene. After stirring evenly, heat to 90 °C and react for 2.5 hours. After the reaction is completed, cool to room temperature, filter and distill under reduced pressure to obtain a yellowish-brown viscous liquid, which is the modified titanate coupling agent shown in Formula A, with a yield of 61.8 g.

[0064] Example 1

[0065] First, weigh out 30 parts of homopolymer polypropylene, 60 parts of bamboo fiber, 4 parts of modified titanate coupling agent, 0.8 parts of silver-loaded zirconium phosphate, and 5.2 parts of talc powder according to the following weight proportions.

[0066] Then, the following steps are used to prepare a lightweight interior material made of bamboo fiber modified polypropylene with resistance to aging:

[0067] (1) Dry the bamboo fiber under vacuum at 90°C for 3.5 hours until the moisture content is <0.4%, then soak the bamboo fiber in a 3% sodium hydroxide solution for 40 minutes, rinse repeatedly with deionized water until the pH of the washing solution is 7.0, and then vacuum dry it again at 70°C until the moisture content is <0.3%;

[0068] (2) The modified titanate coupling agent was dissolved in an ethanol / water mixed solvent at a concentration of 2wt%, and applied evenly to the dried bamboo fiber surface by atomization spraying. The treated bamboo fiber and silver-loaded zirconium phosphate were added to a high-speed mixer and premixed at 600 rpm for 8 minutes at 70°C. Then, homopolymer polypropylene and talc were added and mixed at 900 rpm for 3 minutes to obtain the premix.

[0069] (3) The premixed material is melt-blended in a twin-screw extruder with the following conditions: feeding section temperature 165℃, melt mixing section temperature 180℃, metering section temperature 195℃, extrusion die temperature 195℃, and screw speed 300rpm. The extruded strands are water-cooled and pelletized, and then injection molded at a temperature of 185-200℃, an injection pressure of 80MPa, and a mold temperature of 45℃ to obtain the aging-resistant bamboo fiber modified polypropylene lightweight interior material.

[0070] Example 2

[0071] The components and their contents were changed to: 35 parts homopolymer polypropylene, 50 parts bamboo fiber, 5 parts modified titanate coupling agent, 0.6 parts silver-loaded zeolite, and 9.4 parts calcium carbonate.

[0072] The material preparation steps are basically the same as in Example 1, except that the concentration of sodium hydroxide solution for bamboo fiber pretreatment is 5%, the impregnation time is 30 minutes, and the twin-screw extruder conditions are: feeding section temperature 170℃, melt mixing section temperature 185℃, metering section temperature 200℃, extrusion die temperature 200℃, and screw speed 250 rpm.

[0073] Comparative Example 1

[0074] The process is basically the same as in Example 1, except that the modified titanate coupling agent is replaced with an equal amount of isopropyltris(dioctylpyrophosphate) titanate.

[0075] Comparative Example 2

[0076] The process is basically the same as in Example 1, except that the modified titanate coupling agent is replaced with an equal amount of isopropyltris(dioctylpyrophosphate) titanate, and 0.5 parts of neopentyl glycol are added in step (2).

[0077] Comparative Example 3

[0078] The process is basically the same as in Example 1, except that the modified titanate coupling agent is replaced with an equal amount of isopropyltris(dioctylpyrophosphate) titanate, and 0.5 parts of hindered phenolic antioxidant 1010 are added in step (2).

[0079] Performance testing

[0080] The properties of the materials in Examples 1-2 and Comparative Examples 1-3 were tested according to the following test methods and standards: tensile strength was tested according to GB / T1040.2-2022 at a tensile rate of 50 mm / min; flexural modulus was tested according to GB / T9341-2008 at a test rate of 2 mm / min; cantilever beam notched impact strength was tested according to GB / T1843-2008; density was tested according to GB / T1033.1-2008; thermo-oxidative aging was conducted according to GB / T7141-2008, with aging in a 150℃ oven for 500 hours, and the tensile strength retention rate after aging was tested; xenon lamp aging was conducted according to GB / T16422.1-2022 at an irradiance of 60 W / m². 2 (300-400nm), blackboard temperature 65℃, relative humidity 50%, color difference ΔE measured after aging for 800h; antibacterial rate tested according to GB / T31402-2023, with Escherichia coli and Staphylococcus aureus as the bacterial strains. Test results are shown in the table below: Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength / MPa 68 62 52 55 54 Flexural modulus / GPa 3.8 3.5 3.0 3.2 3.1 <![CDATA[Impact strength / kJ·m -2 > 9.8 9.6 7.2 7.5 7.4 <![CDATA[Density / g·cm -3 > 0.93 0.89 0.95 0.94 0.94 Strength retention rate / % 87 83 64 67 70 Color difference ΔE 2.3 2.5 6.5 5.2 5.8 Antibacterial rate / % ≥99 ≥99 ≥95 ≥95 ≥95

[0081] A comparison of the data from Examples 1-2 and Comparative Example 1 shows that the material in Example 1 using the modified titanate coupling agent of the present invention exhibits superior mechanical strength, aging resistance, and antibacterial ability compared to the material using commercially available titanate coupling agents. This indicates that the synergistic effect of the hindered phenolic group's interfacial site-fixed antioxidant function and the pyrophosphate coupling function in the modified titanate coupling agent of the present invention can significantly improve the aging resistance and interfacial strength of the material, improve compatibility issues, and effectively complex silver-loaded nanomaterials and anchor them near the interface. This not only achieves uniform dispersion, sustained release, and long-lasting antibacterial effect of silver ions, but also avoids the photocatalytic aging side effects caused by aggregation and exposure.

[0082] According to the data comparison between Examples 1-2 and Comparative Example 2, neopentyl glycol in the comparative example is physically mixed in the form of free small molecules. It is unevenly dispersed in the polypropylene matrix and is extremely easy to migrate. It cannot form a durable and effective space shielding layer around the silver particles. Its xenon lamp aging value is much higher than that of Examples 1 and 2. Compared with Comparative Example 1, it only shows a slight improvement. This indicates that the space shielding function of neopentyl glycol must rely on its fixation around the coupling agent titanium core through chemical chelation to achieve the same effect. Simple physical mixing cannot achieve the same effect.

[0083] A comparison of the data from Examples 1-2 and Comparative Example 3 shows that even with the addition of hindered phenolic antioxidant 1010 in Comparative Example 3, its strength retention rate at 150℃ / 500h was only 70%, and ΔE=5.8 after 800h under xenon lamp, both significantly worse than Examples 1 and 2. This further illustrates that free antioxidants are prone to migration and loss during long-term use. In contrast, the design of this invention, which fixes the hindered phenolic chemical bonds to the coupling agent skeleton, can achieve continuous and stable antioxidant protection in the interface region, with an effect far exceeding that of exogenous addition schemes.

[0084] In summary, this invention integrates multiple functions such as interfacial coupling, interfacial anti-oxidation, silver ion anchoring, and anti-photocatalysis into a single coupling agent molecule through an integrated structural design at the molecular level. This results in significant improvements in mechanical properties, aging resistance, antibacterial properties, and lightweight properties of bamboo fiber modified polypropylene materials. It effectively solves the problems of weak interfacial bonding, insufficient aging resistance, and the contradiction between antibacterial and anti-aging properties in existing bamboo fiber composite materials.

[0085] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A lightweight interior material made of bamboo fiber modified polypropylene with aging resistance, characterized in that, It is prepared by the following parts by weight: 30-40 parts polypropylene, 45-60 parts bamboo fiber, 4-6 parts modified titanate coupling agent, 0.3-1 parts silver-loaded nanomaterials and 5-15 parts filler; The modified titanate coupling agent has the structure shown in Formula A: ； Where R= .

2. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 1, characterized in that, The polypropylene is selected from homopolymer polypropylene or copolymer polypropylene with a melt flow index of 10-15 g / 10 min. The bamboo fiber is selected from at least one of bamboo pulp fiber and bamboo virgin fiber; The silver-loaded nanomaterial is selected from at least one of silver-loaded zirconium phosphate, silver-loaded zeolite, and silver-loaded glass. The filler is selected from at least one of talc, calcium carbonate, wollastonite, and mica powder.

3. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 1, characterized in that, The modified titanate coupling agent is prepared by the following steps: (1) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid reacts with 1,6-hexanediol under the action of a catalyst to prepare hindered phenolic alcohol; (2) After the hindered phenol alcohol and n-octanol are mixed, they are reacted with phosphorus pentoxide to prepare mixed pyrophosphate ester; (3) Mixed pyrophosphate and tetraisopropyl titanate were reacted under anhydrous conditions to prepare titanium pyrophosphate intermediate; (4) The titanium pyrophosphate intermediate is reacted with neopentyl glycol to prepare the modified titanate coupling agent.

4. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 3, characterized in that, The specific method of step (1) is as follows: In a reactor, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 1,6-hexanediol and organic solvent are added, and after stirring and dissolving, a catalyst is added. The reaction is refluxed at 100-130°C for 6-12 hours. After the reaction is completed, the mixture is washed and dried to obtain hindered phenol alcohol. The catalyst is p-toluenesulfonic acid, and the amount of catalyst used is 0.5-2% of the molar amount of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid; The organic solvent is selected from toluene or cyclohexane; The molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to 1,6-hexanediol is 1:2.5-4.

5. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 3, characterized in that, The specific method of step (2) is as follows: In the reactor, hindered phenol alcohol and n-octanol are added and stirred evenly. Phosphorus pentoxide is added at 40-55℃, and the temperature is raised to 70-85℃ for 3-5 hours to mature. Then deionized water is added and hydrolyzed at 50-60℃ for 1-2 hours. After vacuum distillation, mixed pyrophosphate is obtained. The amount of deionized water added is 2-5% of the mass of phosphorus pentoxide; The molar ratio of the hindered phenol alcohol, n-octanol and phosphorus pentoxide is 1:(3-3.5):(1.5-1.8).

6. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 3, characterized in that, The specific method of step (3) is as follows: In a reactor, a mixture of pyrophosphate and solvent is added, stirred and dissolved, and then tetraisopropyl titanate is added. Under nitrogen protection, the temperature is raised to 60-90℃ and reacted for 2-4 hours. The titanium pyrophosphate intermediate is obtained by vacuum distillation. The solvent is selected from toluene or xylene; The molar ratio of the mixed pyrophosphate and tetraisopropyl titanate is 2.05-2.2:

1.

7. The lightweight interior material with aging-resistant bamboo fiber modified polypropylene according to claim 3, characterized in that, The specific method of step (4) is as follows: In a reactor, titanium pyrophosphate intermediate and neopentyl glycol are added, the temperature is raised to 80-100℃ and reacted for 2-4 hours, and after cooling, the mixture is filtered and distilled under reduced pressure to obtain the modified titanate coupling agent. The molar ratio of the titanium pyrophosphate intermediate to neopentyl glycol is 1:0.95-1.

1.

8. A method for preparing the aging-resistant bamboo fiber modified polypropylene lightweight interior material according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Dry bamboo fiber under vacuum at 70-100℃, then soak it in sodium hydroxide solution for 20-60 minutes, wash it with water until neutral, and then dry it under vacuum at 70-100℃ again. (2) The dried bamboo fiber, modified titanate coupling agent and silver-loaded nanomaterials are premixed in a high-speed mixer at 60-80℃ for 5-10 minutes, and then polypropylene and filler are added and mixed for 2-5 minutes to obtain the premix. (3) The premixed material is melt-blended in a twin-screw extruder, stretched, cooled and granulated, and then injection molded to obtain the aging-resistant bamboo fiber modified polypropylene lightweight interior material.

9. The preparation method according to claim 8, characterized in that, The vacuum drying conditions in step (1) are: temperature 80-100℃, drying time 3-4 hours; and the mass concentration of the sodium hydroxide solution is 1-5%.

10. The preparation method according to claim 8, characterized in that, In step (2), the modified titanate coupling agent is first dissolved in an ethanol / water mixed solvent at a concentration of 1-3 wt%, and then applied evenly to the surface of bamboo fiber by spraying before premixing. The conditions for the twin-screw extruder in step (3) are as follows: feeding section temperature 160-170℃, melt mixing section temperature 180-195℃, metering section temperature 190-200℃, extrusion die temperature 190-200℃, and screw speed 200-400rpm.

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