A bamboo fiber modified composite plastic material and a preparation method thereof

Abstract

The application relates to the field of composite plastic materials, in particular to a bamboo fiber modified composite plastic material and a preparation method thereof. According to weight parts, the bamboo fiber modified composite plastic material comprises the following raw materials: 50-70 parts of polyethylene, 20-30 parts of modified bamboo fiber, 5-10 parts of a flame retardant, 0.5-1.5 parts of a plasticizer, 1.5-3 parts of a compatilizer and 0.5-2 parts of a lubricant. The bamboo fiber modified composite plastic material has excellent anti-aging, flame-retardant, bacteriostatic and mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite plastic materials, in particular to a bamboo fiber modified composite plastic material and a preparation method thereof. BACKGROUND

[0002] Non-metal composite material pipelines have been widely used in many industries such as petroleum, chemical industry, papermaking and urban water supply due to their advantages of corrosion resistance, smooth inner surface and low energy consumption in conveying. With the rapid development of China's economy, the market's recognition of composite material pipelines is continuously improving, and the demand is also increasing. Polyethylene (PE) is an organic material with excellent comprehensive performance, good physical and chemical stability and mechanical properties, and is widely used in pipeline materials. However, polyethylene has obvious shortcomings in rigidity and strength, so other components are added to form a composite material.

[0003] Bamboo fiber is derived from natural bamboo, which has the advantages of high strength, good toughness and large rigidity, and is an ideal reinforcing phase of composite materials. However, the surface of bamboo fiber has polarity and hydrophilicity, which is fundamentally different from the non-polar and hydrophobic polyethylene matrix, resulting in poor interfacial adhesion between the two, which ultimately limits the improvement of the performance of the composite material.

[0004] In addition, higher requirements for flame retardation and antibacterial properties are put forward for pipelines, while PE is flammable and prone to microbial growth. Therefore, it is particularly important to modify the surface of bamboo fiber to enhance its interfacial compatibility with polyethylene and to endow the composite material with better flame retardation and antibacterial properties. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a bamboo fiber modified composite plastic material with excellent antibacterial, flame retardant and mechanical properties.

[0006] The second purpose of the present application is to provide a preparation method of a bamboo fiber modified composite plastic material, which is simple to operate and easy to practice.

[0007] One of the purposes of the present application is achieved by the following technical scheme:

[0008] A bamboo fiber modified composite plastic material, by weight, comprises the following raw materials: polyethylene 50-70 parts, modified bamboo fiber 20-30 parts, flame retardant 5-10 parts, plasticizer 0.5-1.5 parts, compatibilizer 1.5-3 parts, lubricant 0.5-2 parts;

[0009] The preparation process of the modified bamboo fiber is as follows:

[0010] (1) adding 2,2,6,6-tetramethylpiperidine oxide, sodium bromide and sodium hypochlorite into water, mixing, then adding bamboo fiber and adjusting pH to 10.0-10.2, and then carrying out a heating reaction, after the reaction is completed, filtering, washing, and vacuum drying to obtain the oxidized bamboo fiber;

[0011] (2) adding the oxidized bamboo fiber into dimethyl sulfoxide, then adding compound A and concentrated sulfuric acid to react, after the reaction is completed, filtering, washing, and vacuum drying to obtain the modified bamboo fiber;

[0012] The structural formula of the compound A is as follows:

[0013] .

[0014] Preferably, the molecular weight of the polyethylene is (2-6)×10 5 .

[0015] Preferably, in step (1), the mass ratio of the bamboo fiber, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide, and sodium hypochlorite is 1:(0.01-0.02):(0.02-0.04):(0.4-0.8); the temperature of the heating reaction is 55-60℃, and the time is 1-1.5h.

[0016] Preferably, in step (2), the amount ratio of the oxidized bamboo fiber, compound A, and concentrated sulfuric acid is 1g:(1.8-3.6)g:(0.5-0.6)mL; the temperature of the reaction is 85-90℃, and the time is 2.5-3h.

[0017] Preferably, the preparation process of the compound A is as follows:

[0018] The compound A is obtained by dissolving 1,2,2,6,6-pentamethyl-4-(oxetan-2-ylmethoxy)piperidine and octylamine in methanol, refluxing for 18-20h, and then purifying.

[0019] Preferably, the molar ratio of the 1,2,2,6,6-pentamethyl-4-(oxetan-2-ylmethoxy)piperidine and octylamine is 1:(1-2); and the time of the refluxing reaction is 18-20h.

[0020] Preferably, the preparation process of the flame retardant is as follows:

[0021] S1. adding sodium hydride into N,N-dimethylformamide, then adding imidazole and stirring for 20-30min, and then adding 1-bromo-4-naphthyl isocyanate to react, after the reaction is completed, purifying to obtain intermediate 1;

[0022] The structural formula of the intermediate 1 is as follows:

[0023] ;

[0024] S2. Melamine, the intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium and 1,1'-bis(diphenylphosphino)ferrocene are added to toluene for reaction, and after the reaction is completed, purification is carried out to obtain the flame retardant;

[0025] The structural formula of the flame retardant is:

[0026] .

[0027] Preferably, the molar ratio of the imidazole, 1-bromo-4-naphthyl isocyanate and sodium hydride in step S1 is 1: (1-1.5): (1.2-1.5); the reaction time is 1.5-2h.

[0028] Preferably, the molar ratio of the melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium and 1,1'-bis(diphenylphosphino)ferrocene in step S2 is 1: (3-3.5): (9-10): (0.09-0.1): (0.18-0.2); the reaction temperature is 110-120℃.

[0029] Preferably, the lubricant is PE wax or paint wax; the plasticizer is selected from one of dioctyl terephthalate, dibutyl phthalate and dioctyl sebacate; and the compatibilizer is maleic anhydride grafted polyethylene.

[0030] The second object of the present application is achieved by the following technical scheme:

[0031] The preparation method of the bamboo fiber modified composite plastic material comprises the following steps:

[0032] According to the weight parts, each raw material is taken and uniformly mixed, and then transferred to a twin-screw extruder for extrusion granulation at 120-150℃ and 50-200r / min.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] 1. The present application provides a composite plastic material taking polyethylene, modified bamboo fiber, flame retardant and the like as raw materials, which has excellent anti-aging, flame-retardant, antibacterial and mechanical properties.

[0035] 2. The modified bamboo fiber is added in the composite plastic material of the present application, which can improve the mechanical properties and anti-aging properties of the composite plastic material. The modified bamboo fiber is prepared by reacting 1,2,2,6,6-pentamethyl-4-(oxirane-2-ylmethoxy) piperidine and octylamine to generate a hydroxyl-containing compound A, and then grafting compound A onto the surface of the oxidized bamboo fiber through esterification reaction. The mechanism of the modified bamboo fiber to improve the mechanical properties and anti-aging properties of the composite plastic material is as follows: the C8 straight-chain alkyl group at the end of the compound A grafted onto the surface of the bamboo fiber is similar to the polyethylene main chain structure, which can produce strong van der Waals force with the polyethylene matrix during melt blending and promote physical entanglement between chain segments, thereby improving the dispersibility and interfacial adhesion strength of the bamboo fiber in the matrix. At the same time, the highly alkylated piperidine ring in compound A enhances the overall hydrophobicity, which helps to reduce the polarity difference at the interface and further improve the compatibility between the two. In addition, the hindered amine light stabilizing structure in the molecule of compound A can effectively capture the free radicals generated during the photo / thermal oxidation of polyethylene, interrupting the degradation chain reaction, thereby significantly improving the anti-aging properties of the polyethylene composite material.

[0036] 3. The flame retardant is also added in the composite plastic material of the present application, which can improve the flame retardant properties and antibacterial properties of the composite plastic material. The flame retardant is prepared by reacting 1-bromo-4-naphthyl isocyanate with imidazole to obtain intermediate 1, and then further reacting with melamine. The mechanism of the flame retardant to improve the flame retardant properties is as follows: the triazine ring and naphthalene ring in the flame retardant have high thermal stability and chemical stability, and can build a dense protective carbon layer on the surface of the material after heating, which can isolate the transmission of oxygen and heat. At the same time, the triazine ring, imidazole ring and other rings in the flame retardant contain a large number of nitrogen atoms, which can release non-combustible gases such as nitrogen (N2) and ammonia (NH3) during thermal decomposition, effectively diluting the concentration of oxygen and combustible cracking gas on the surface of the polymer, thereby inhibiting combustion; and can also generate nitrogen-containing free radicals (such as NO), which can capture high-activity free radicals (such as H and HO) in the combustion chain reaction, effectively interrupting the combustion reaction process. In addition, the rich imidazole groups in the molecule of the flame retardant endow the composite plastic material with excellent antibacterial properties. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the infrared spectrum of the modified bamboo fiber prepared in Preparation Example 4. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0039] In this embodiment of the invention, the molecular weight of polyethylene is 4 × 10⁻⁶. 5 .

[0040] Preparation Example 1

[0041] This preparation example provides a compound A, which is prepared by the following method:

[0042]

[0043] Following a reaction ratio of 1 mmol:1.5 mmol:18 mL, 1,2,2,6,6-pentamethyl-4-(ethylene oxide-2-ylmethoxy)piperidine (CAS: 71882-90-1) and octylamine were dissolved in methanol and refluxed for 19 h. After the reaction was complete, the mixture was concentrated under vacuum, and the residue was dissolved in dichloromethane, washed with water, dried over anhydrous magnesium sulfate, filtered, concentrated under reduced pressure, and purified by silica gel column chromatography to obtain compound A (yield 71.9%). The NMR and mass spectrometry results of compound A are as follows:

[0044] 1 H NMR: (C 21 H 44 O2N2, 400MHz, DMSO-d6) δ: 0.88 (m, 3H), 1.22 (s, 12H), 1.24-1.31 (m, 10H), 1.37-1.43 (m, 4H), 1.64-1.68 (m, 2H), 2.26 (s, 3H ), 2.51-2.55 (t, 2H), 2.81-2.85 (m, 1H), 3.08-3.12 (m, 1H), 3.28-3.37 (m, 3H), 3.54-3.58 (m, 1H), 4.49 (s, 1H), 5.52 (s, 1H). MS(ESI)m / z=357.29[M].

[0045] Preparation Example 2

[0046] This preparation example provides a compound A, which is prepared by the following method:

[0047] According to the amount ratio of 1,2,2,6,6-pentamethyl-4-(oxane-2-ylmethoxy)piperidine, octylamine, methanol 1 mmol: 1 mmol: 15 mL, 1,2,2,6,6-pentamethyl-4-(oxane-2-ylmethoxy)piperidine and octylamine are dissolved in methanol, refluxed for 18 h, after the reaction is completed, vacuum concentration, the residue is dissolved in dichloromethane, washed with water, dried with anhydrous magnesium sulfate, filtered, reduced pressure concentration, silica gel column purification, to obtain compound A (yield 70.6%), the nuclear magnetic resonance and mass spectrum results of compound A are the same as those of preparation example 1.

[0048] Preparation example 3

[0049] The present preparation example provides a compound A, and the preparation method is as follows:

[0050] According to the amount ratio of 1,2,2,6,6-pentamethyl-4-(oxane-2-ylmethoxy)piperidine, octylamine, methanol 1 mmol: 2 mmol: 20 mL, 1,2,2,6,6-pentamethyl-4-(oxane-2-ylmethoxy)piperidine and octylamine are dissolved in methanol, refluxed for 20 h, after the reaction is completed, vacuum concentration, the residue is dissolved in dichloromethane, washed with water, dried with anhydrous magnesium sulfate, filtered, reduced pressure concentration, silica gel column purification, to obtain compound A (yield 69.3%), the nuclear magnetic resonance and mass spectrum results of compound A are the same as those of preparation example 1.

[0051] Preparation example 4

[0052] The present preparation example provides a modified bamboo fiber, and the preparation method is as follows:

[0053]

[0054] (1) According to the amount ratio of bamboo fiber, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide, sodium hypochlorite, water 1 g: 0.15 g: 0.03 g: 0.6 g: 0.22 L, 2,2,6,6-tetramethylpiperidine oxide (CAS: 2564-83-2), sodium bromide and sodium hypochlorite are added to water and mixed thoroughly, then bamboo fiber is added, and then 1 mol / L NaOH solution is used to adjust the pH value to 10.1, and reacted at 57℃ for 1.2 h, after the reaction is completed, the solid phase is filtered, washed with water until neutral, and vacuum dried to obtain oxidized bamboo fiber;

[0055] (2) According to the amount ratio of oxidized bamboo fiber, compound A, concentrated sulfuric acid, dimethyl sulfoxide 1 g: 2 g: 0.55 mL: 55 mL, the oxidized bamboo fiber is ultrasonically dispersed in dimethyl sulfoxide, compound A of preparation example 1, concentrated sulfuric acid is added, and reacted at 86℃ for 2.8 h, after the reaction is completed, the solid phase is filtered, then washed with acetone and water in turn, and vacuum dried to obtain modified bamboo fiber.

[0056] Preparation Example 5

[0057] The present preparation example provides a modified bamboo fiber, and the preparation method is as follows:

[0058] (1) According to the amount ratio of bamboo fiber, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide, sodium hypochlorite and water 1 g:0.01 g:0.02 g:0.4 g:0.2 L, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide and sodium hypochlorite are added to water and mixed thoroughly, then bamboo fiber is added, and then 1 mol / L NaOH solution is used to adjust the pH value to 10, and the reaction is carried out at 55°C for 1.5 h. After the reaction is completed, the solid phase is filtered, washed with water until neutral, and then vacuum dried to obtain oxidized bamboo fiber;

[0059] (2) According to the amount ratio of oxidized bamboo fiber, compound A, concentrated sulfuric acid and dimethyl sulfoxide 1 g:1.8 g:0.5 mL:50 mL, the oxidized bamboo fiber is ultrasonically dispersed in dimethyl sulfoxide, compound A of preparation example 2, concentrated sulfuric acid is added, and the reaction is carried out at 85°C for 3 h. After the reaction is completed, the solid phase is filtered, and then washed with acetone and water in turn. After vacuum drying, the modified bamboo fiber is obtained.

[0060] Preparation Example 6

[0061] The present preparation example provides a modified bamboo fiber, and the preparation method is as follows:

[0062] (1) According to the amount ratio of bamboo fiber, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide, sodium hypochlorite and water 1 g:0.02 g:0.04 g:0.8 g:0.24 L, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide and sodium hypochlorite are added to water and mixed thoroughly, then bamboo fiber is added, and then 1 mol / L NaOH solution is used to adjust the pH value to 10.2, and the reaction is carried out at 60°C for 1 h. After the reaction is completed, the solid phase is filtered, washed with water until neutral, and then vacuum dried to obtain oxidized bamboo fiber;

[0063] (2) According to the amount ratio of oxidized bamboo fiber, compound A, concentrated sulfuric acid and dimethyl sulfoxide 1 g:3.6 g:0.6 mL:60 mL, the oxidized bamboo fiber is ultrasonically dispersed in dimethyl sulfoxide, compound A of preparation example 3, concentrated sulfuric acid is added, and the reaction is carried out at 90°C for 2.5 h. After the reaction is completed, the solid phase is filtered, and then washed with acetone and water in turn. After vacuum drying, the modified bamboo fiber is obtained.

[0064] Preparation Example 7

[0065] The present preparation example provides a flame retardant, and the preparation process is as follows:

[0066]

[0067] S1. Following the ratio of imidazole, 1-bromo-4-naphthyl isocyanate, sodium hydride, and N,N-dimethylformamide (1 mmol: 1.2 mmol: 1.4 mmol: 3 mL), sodium hydride (60%, dispersed in paraffin oil) was dispersed in N,N-dimethylformamide. Imidazole was then added and stirred for 22 min. Next, 1-bromo-4-naphthyl isocyanate (CAS: 1591-96-4) was added, and the reaction was carried out at room temperature for 1.6 h. After the reaction was complete, water was added to the reaction solution to precipitate the product. The product was filtered, washed successively with water and diethyl ether, and dried under vacuum to obtain intermediate 1 (yield 76.9%). The NMR and mass spectrometry results of intermediate 1 are as follows:

[0068] 1 H NMR: (C 14 H 10 N3OBr, 400MHz, DMSO-d6) δ: 6.77-6.81 (d, 1H), 7.12-7.16 (d, 1H), 7.44-7.48 (m, 2H), 7. 52-7.56 (m, 1H), 7.92-7.96 (d, 1H), 8.00-8.04 (d, 1H), 8.12-8.18 (m, 2H), 9.79 (s, 1H). MS(ESI)m / z=315.00[M].

[0069] S2. Melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylacetone)dipalladium, 1,1'-bis(diphenylphosphine)ferrocene, and toluene were added to toluene in a ratio of 1 mmol:3.2 mmol:9.5 mmol:0.05 mmol:0.19 mmol:11 mL. The reaction mixture was reacted at 115 °C, and the reaction progress was monitored by TLC. After the reaction was completed, the reaction solution was added to water, the organic phase was extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, concentrated, and purified by column chromatography to obtain the flame retardant (yield 83.7%). The NMR and mass spectrometry results of the flame retardant are as follows:

[0070] 1 HNMR: (C 45 H 33 N 15 O3, 400MHz, DMSO-d6) δ: 7.02-7.06 (d, 3H), 7.12-7.16 (d, 3H), 7.32-7.38 (m, 6H), 7.43-7 .48 (m, 6H), 7.60-7.64 (d, 3H), 8.14 (s, 3H), 8.15-8.17 (d, 3H), 8.86 (s, 3H), 9.97 (s, 3H). MS(ESI) m / z=831.29[M].

[0071] Preparation Example 8

[0072] The present preparation example provides a flame retardant, and the preparation process is as follows:

[0073] S1. According to the amount ratio of imidazole, 1-bromo-4-naphthyl isocyanate, sodium hydride, N,N-dimethylformamide 1 mmol: 1 mmol: 1.2 mmol: 2.5 mL, sodium hydride (60%, dispersed in paraffin oil) is dispersed in N,N-dimethylformamide, then imidazole is added and stirred for 25 min, then 1-bromo-4-naphthyl isocyanate (CAS: 1591-96-4) is added, and the reaction is carried out at room temperature for 1.5 h. After the reaction is completed, water is added to the reaction solution to precipitate the product. After filtration, the product is washed with water and diethyl ether in turn, and vacuum dried to obtain intermediate 1 (yield 74.5%). The nuclear magnetic resonance and mass spectrum results of intermediate 1 are the same as those of preparation example 7.

[0074] S2. According to the amount ratio of melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium, 1,1'-bis(diphenylphosphino)ferrocene, toluene 1 mmol: 3 mmol: 9 mmol: 0.09 mmol: 0.18 mmol: 10 mL, melamine, the intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium and 1,1'-bis(diphenylphosphino)ferrocene are added to toluene, and the reaction is carried out at 110°C. The progress of the reaction is monitored by TLC. After the reaction is completed, the reaction solution is added to water, and the organic phase is extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, concentrated, and purified by column chromatography to obtain a flame retardant (yield 80.4%). The nuclear magnetic resonance and mass spectrum results of the flame retardant are the same as those of preparation example 7.

[0075] Preparation Example 9

[0076] The present preparation example provides a flame retardant, and the preparation process is as follows:

[0077] S1. According to the amount ratio of imidazole, 1-bromo-4-naphthyl isocyanate, sodium hydride, N,N-dimethylformamide 1 mmol: 1.5 mmol: 1.5 mmol: 3.5 mL, sodium hydride (60%, dispersed in paraffin oil) is dispersed in N,N-dimethylformamide, then imidazole is added and stirred for 30 min, then 1-bromo-4-naphthyl isocyanate (CAS: 1591-96-4) is added, and the reaction is carried out at room temperature for 2 h. After the reaction is completed, water is added to the reaction solution to precipitate the product. After filtration, the product is washed with water and diethyl ether in turn, and vacuum dried to obtain intermediate 1 (yield 75.2%). The nuclear magnetic resonance and mass spectrum results of intermediate 1 are the same as those of preparation example 7.

[0078] S2. According to the amount ratio of melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium, 1,1'-bis(diphenylphosphino)ferrocene, toluene 1 mmol: 3.5 mmol: 10 mmol: 0.1 mmol: 0.2 mmol: 12 mL, the melamine, the intermediate 1, sodium tert-butoxide, tris(dibenzylideneacetone)dipalladium and 1,1'-bis(diphenylphosphino)ferrocene are added to toluene, reacted at 120℃, the reaction progress is monitored by TLC, after the reaction is completed, the reaction solution is added to water, the organic phase is extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, concentrated, and purified by column chromatography to obtain the flame retardant (yield 81.9%), the nuclear magnetic resonance and mass spectrum results of the flame retardant are the same as those of Preparation Example 7.

[0079] Example 1

[0080] The example provides a bamboo fiber modified composite plastic material, which comprises the following raw materials in parts by weight: polyethylene 60 parts, modified bamboo fiber of Preparation Example 4 25 parts, flame retardant of Preparation Example 7 7 parts, dioctyl terephthalate 1 part, maleic anhydride grafted polyethylene 2 parts, and PE wax 1 part.

[0081] The example also provides a preparation method of the bamboo fiber modified composite plastic material, which comprises the following steps:

[0082] The raw materials are weighed and uniformly mixed according to the above weight parts, and then transferred to a double-screw extruder for extrusion granulation at 140℃ and 70r / min. After uniform mixing and plasticization, the bamboo fiber modified composite plastic material is obtained.

[0083] Example 2

[0084] The example provides a bamboo fiber modified composite plastic material, which comprises the following raw materials in parts by weight: polyethylene 50 parts, modified bamboo fiber of Preparation Example 5 20 parts, flame retardant of Preparation Example 8 5 parts, dibutyl phthalate 0.5 parts, maleic anhydride grafted polyethylene 1.5 parts, and lacquer wax 0.5 parts.

[0085] The example also provides a preparation method of the bamboo fiber modified composite plastic material, which comprises the following steps:

[0086] The raw materials are weighed and uniformly mixed according to the above weight parts, and then transferred to a double-screw extruder for extrusion granulation at 120℃ and 200r / min. After uniform mixing and plasticization, the bamboo fiber modified composite plastic material is obtained.

[0087] Example 3

[0088] This embodiment provides a bamboo fiber modified composite plastic material, which, by weight, includes the following raw materials: 70 parts of polyethylene, 30 parts of modified bamboo fiber from Preparation Example 6, 10 parts of flame retardant from Preparation Example 9, 1.5 parts of dioctyl sebacate, 3 parts of maleic anhydride-grafted polyethylene, and 2 parts of PE wax.

[0089] This embodiment also provides a method for preparing the above-mentioned bamboo fiber modified composite plastic material, including the following steps:

[0090] Weigh each raw material according to the above weight proportions and mix them evenly. Transfer the mixture to a twin-screw extruder and extrude and granulate it at 150°C and 50 r / min. After uniform mixing and plasticizing, the mixture is ready.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that melamine is used instead of the flame retardant in Preparation Example 7.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that bamboo fiber is used instead of the modified bamboo fiber used in Preparation Example 4.

[0095] Experimental Example 1

[0096] The modified bamboo fiber prepared in Example 4 was analyzed by Fourier transform infrared spectroscopy (FT-IR), and the results are as follows: Figure 1 As shown.

[0097] Figure 1 The images show the infrared spectra of the modified bamboo fibers prepared in Example 4. Curve a is the infrared spectrum of unmodified bamboo fibers, curve b is the infrared spectrum of oxidized bamboo fibers, and curve c is the infrared spectrum of modified bamboo fibers. (Observation) Figure 1 It is known that, compared to bamboo fiber, oxidized bamboo fiber has a lower content of 1670cm. -1 The characteristic absorption peak of C=O appears at 3331 cm⁻¹. -1 The characteristic absorption peak of the hydroxyl group was significantly strengthened, indicating the successful preparation of oxidized bamboo fiber; compared with oxidized bamboo fiber, the modified bamboo fiber showed a stronger absorption peak at 3000 cm⁻¹. -1 1597cm -1 The presence of characteristic absorption peaks for methyl and NH indicates the successful preparation of modified bamboo fiber.

[0098] Experimental Example 2

[0099] The impact properties of the materials obtained in Examples 1-3 and Comparative Examples 1-2 were tested according to GB / T1043.1-2008, and the results are shown in Table 1.

[0100] The tensile strength and tensile modulus of the materials obtained in Examples 1-3 and Comparative Examples 1-2 were detected according to GB / T1040.1-2018, and the results are shown in Table 1.

[0101] The flame retardancy of the materials obtained in Examples 1-3 and Comparative Examples 1-2 was detected according to GB / T2406.2-2009, and the results are shown in Table 1.

[0102] The antibacterial property of the materials obtained in Examples 1-3 and Comparative Examples 1-2 was detected according to ISO22196-2011, and the results are shown in Table 1.

[0103] The materials obtained in Examples 1-3 and Comparative Examples 1-2 were irradiated under ultraviolet light with an intensity of 720 W / m2for 10 days, and the impact performance of each material after irradiation was detected according to GB / T1043.1-2008. The anti-aging performance was evaluated by the retention rate of impact strength, and the results are shown in Table 1.

[0104] Table 1

[0105]

[0106] As shown in Table 1, compared with Example 1 and Comparative Example 1, the flame retardant property and antibacterial property of the composite plastic material obtained by using melamine instead of the flame retardant of the application are reduced. The above results show that the flame retardant obtained by the application can improve the flame retardant property and antibacterial property of the composite plastic material. The above flame retardant is prepared by reacting 1-bromo-4-naphthyl isocyanate with imidazole to obtain intermediate 1, and then further reacting with melamine. The mechanism of improving the flame retardant property is as follows: the triazine ring and naphthalene ring in the flame retardant have high thermal stability and chemical stability, and can build a dense protective carbon layer on the surface of the material after heating, which can isolate the transmission of oxygen and heat. At the same time, the triazine ring, imidazole ring and other nitrogen-containing groups in the flame retardant can release nitrogen gas (N2), ammonia gas (NH3) and other non-combustible gases during thermal decomposition, effectively dilute the concentration of oxygen and combustible cracking gas on the surface of the polymer, and then inhibit combustion; and generate nitrogen-containing free radicals (such as NO), which can capture high-activity free radicals (such as H and HO) in the combustion chain reaction, effectively interrupting the combustion reaction process. In addition, the imidazole groups in the molecule of the flame retardant endow the composite plastic material with excellent antibacterial property.

[0107] Compared with Example 1, the mechanical properties and anti-aging properties of the composite plastic material obtained by Comparative Example 2 are reduced, in which bamboo fibers are used instead of the modified bamboo fibers of the application. The above results show that the modified bamboo fibers of the application can improve the mechanical properties and anti-aging properties of the composite plastic material. The above modified bamboo fibers are prepared by reacting 1,2,2,6,6-pentamethyl-4-(oxirane-2-ylmethoxy)piperidine and octylamine to generate a hydroxyl-containing compound A, and further grafting compound A onto the surface of the oxidized bamboo fibers through esterification reaction. The mechanism of action of the modified bamboo fibers in improving the mechanical properties and anti-aging properties of the composite plastic material is as follows: the C8 straight-chain alkyl group at the end of the compound A grafted onto the surface of the bamboo fibers is similar to the polyethylene main chain structure, which can produce strong van der Waals force with the polyethylene matrix during melt blending and promote physical entanglement between chain segments, thereby improving the dispersibility and interfacial adhesion strength of the bamboo fibers in the matrix. At the same time, the highly alkylated piperidine ring in compound A enhances the overall hydrophobicity, which helps to reduce the polarity difference at the interface and further improves the compatibility between the two. In addition, the hindered amine light stabilizing structure in the molecule of compound A can effectively capture the free radicals generated during the photo / thermal oxidation of polyethylene, interrupt the degradation chain reaction, and thus significantly improve the anti-aging properties of the polyethylene composite material.

[0108] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the scope of protection of the application. Any non-essential changes and substitutions made by those skilled in the art based on the application belong to the scope of protection required by the application.

Claims

1. A bamboo fiber modified composite plastic material, characterized in that, By weight, it includes the following raw materials: 50-70 parts polyethylene, 20-30 parts modified bamboo fiber, 5-10 parts flame retardant, 0.5-1.5 parts plasticizer, 1.5-3 parts compatibilizer, and 0.5-2 parts lubricant; The preparation process of the modified bamboo fiber is as follows: (1) Add 2,2,6,6-tetramethylpiperidine oxide, sodium bromide and sodium hypochlorite to water and mix, then add bamboo fiber and adjust the pH to 10.0-10.2, then heat the reaction, filter, wash and vacuum dry after the reaction is complete to obtain oxidized bamboo fiber; (2) The oxidized bamboo fiber was added to dimethyl sulfoxide, and then compound A and concentrated sulfuric acid were added to react. After the reaction was completed, the mixture was filtered, washed and vacuum dried to obtain the modified bamboo fiber. The structural formula of compound A is as follows: ； The structural formula of the flame retardant is: 。 2. The bamboo fiber modified composite plastic material according to claim 1, characterized in that, In step (1), the mass ratio of bamboo fiber, 2,2,6,6-tetramethylpiperidine oxide, sodium bromide, and sodium hypochlorite is 1:(0.01-0.02):(0.02-0.04):(0.4-0.8); the heating reaction temperature is 55-60℃ and the time is 1-1.5h.

3. The bamboo fiber modified composite plastic material according to claim 1, characterized in that, In step (2), the ratio of oxidized bamboo fiber, compound A, and concentrated sulfuric acid is 1g:(1.8-3.6)g:(0.5-0.6)mL; the reaction temperature is 85-90℃ and the time is 2.5-3h.

4. The bamboo fiber modified composite plastic material according to claim 3, characterized in that, The preparation process of compound A is as follows: 1,2,2,6,6-pentamethyl-4-(ethylene oxide-2-ylmethoxy)piperidine and octylamine were dissolved in methanol, refluxed, and purified to obtain compound A.

5. The bamboo fiber modified composite plastic material according to claim 4, characterized in that, The molar ratio of 1,2,2,6,6-pentamethyl-4-(ethylene oxide-2-ylmethoxy)piperidine to octylamine is 1:(1-2); the reflux reaction time is 18-20 h.

6. The bamboo fiber modified composite plastic material according to claim 1, characterized in that, The preparation process of the flame retardant is as follows: S1. Sodium hydride was added to N,N-dimethylformamide, then imidazole was added and stirred for 20-30 min. Then 1-bromo-4-naphthyl isocyanate was added to react. After the reaction was completed, the mixture was purified to obtain intermediate 1. The structural formula of intermediate 1 is: ； S2. Melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylacetone)palladium and 1,1'-bis(diphenylphosphine)ferrocene are added to toluene for reaction. After the reaction is completed, the mixture is purified to obtain the flame retardant.

7. The bamboo fiber modified composite plastic material according to claim 6, characterized in that, In step S1, the molar ratio of imidazole, 1-bromo-4-naphthyl isocyanate, and sodium hydride is 1:(1-1.5):(1.2-1.5); the reaction time is 1.5-2 hours.

8. The bamboo fiber modified composite plastic material according to claim 6, characterized in that, In step S2, the molar ratio of melamine, intermediate 1, sodium tert-butoxide, tris(dibenzylacetone)palladium, and 1,1'-bis(diphenylphosphine)ferrocene is 1:(3-3.5):(9-10):(0.09-0.1):(0.18-0.2); the reaction temperature is 110-120℃.

9. The bamboo fiber modified composite plastic material according to claim 1, characterized in that, The lubricant is PE wax or lacquer wax; the plasticizer is selected from one of dioctyl terephthalate, dibutyl phthalate, and dioctyl sebacate; the compatibilizer is maleic anhydride-grafted polyethylene.

10. A method for preparing a bamboo fiber modified composite plastic material according to any one of claims 1-9, characterized in that, Includes the following steps: Weigh each raw material according to the stated weight proportions and mix them evenly. Transfer the mixture to a twin-screw extruder and extrude and granulate it at 120-150℃ and 50-200r / min. After uniform mixing and plasticizing, the mixture is ready.

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