Multifunctional additive for inhibiting carbonization of bamboo powder and masterbatch for pbat / bamboo powder dustproof net

Abstract

The application discloses a multifunctional additive for inhibiting carbonization of bamboo powder and a PBAT / bamboo powder dustproof net master batch, wherein the multifunctional additive simultaneously has a silane coupling agent, a hindered phenol antioxidant and a long-chain alkyl group; on one hand, the silane coupling agent structure is used to make it chemically bonded and firmly anchored on the surface of the bamboo powder; on the other hand, the long-chain aliphatic structure and the hindered phenol structure are used to realize 'anchoring-lubricating-antioxidation' synergy; in this way, the thermal oxidative degradation and carbonization in the bamboo powder processing process are inhibited, and the interface interaction between the bamboo powder and the PBAT is improved, so that a full-biodegradable composite material with light color and good mechanical properties is obtained.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable polymer composite materials technology, and particularly relates to a multifunctional additive for inhibiting bamboo powder carbonization and a masterbatch for PBAT / bamboo powder dustproof net. Background Technology

[0002] With the advancement of global policies to ban and restrict plastics and the proposal of "dual carbon" goals, the development of high-performance biodegradable materials has become an urgent need. Polybutylene adipate terephthalate (PBAT), as a fully biodegradable polyester with excellent comprehensive properties, has broad application prospects in packaging, agricultural films, and other fields due to its good ductility and film-forming properties. However, pure PBAT suffers from problems such as low modulus, insufficient strength, and high cost, which restricts its further promotion.

[0003] To reduce costs and impart eco-friendly properties to materials, incorporating natural biomass fillers into the PBAT matrix is ​​a mainstream modification approach. Bamboo powder, with its wide availability, biodegradability, and high rigidity, has become an ideal reinforcing filler. However, the surface of bamboo powder is rich in polar hydroxyl groups, resulting in poor compatibility with hydrophobic PBAT and weak interfacial bonding. More importantly, during the high-temperature shearing process of melt blending, bamboo powder is highly susceptible to carbonization and blackening due to thermo-oxidative degradation. This not only severely affects the appearance of the composite material but also often leads to a decline in mechanical properties.

[0004] Currently, modification research on PBAT / bamboo powder composites typically approaches the issue from two independent angles: one is to improve interfacial adhesion by adding silane coupling agents or maleic anhydride graft compatibilizers; the other is to attempt to mitigate thermal degradation by adding small-molecule antioxidants (such as hindered phenols). The common practice in the industry is to simply physically blend these additives. However, this traditional "compounding" approach has significant drawbacks: firstly, small-molecule additives are prone to migration and volatilization during processing, resulting in poor long-term stability; secondly, physical blending leads to uneven dispersion of additives, preventing antioxidants from accurately concentrating on the bamboo powder surface most susceptible to carbonization, resulting in low efficiency; most importantly, the functional components are independent and lack synergy, making it difficult to simultaneously address the root causes of interfacial incompatibility and carbonization problems caused by frictional heat generation and free radical oxidation. Summary of the Invention

[0005] To address the problems in the background art, this invention provides a multifunctional additive for inhibiting bamboo powder carbonization and a masterbatch for PBAT / bamboo powder dustproof nets. The multifunctional additive simultaneously possesses a silane coupling agent, a hindered phenolic antioxidant, and long-chain alkyl groups. On the one hand, it utilizes the silane coupling agent structure to chemically bond the bamboo powder, thereby firmly anchoring it to the surface of the bamboo powder. On the other hand, it utilizes the long-chain aliphatic structure and the hindered phenolic structure to achieve a synergistic effect of "anchoring-lubrication-antioxidation." In this way, it not only inhibits the thermo-oxidative degradation and carbonization during the bamboo powder processing but also improves the interfacial interaction between bamboo powder and PBAT, thereby obtaining a light-colored, fully biodegradable composite material with excellent mechanical properties.

[0006] The present invention proposes a multifunctional additive for inhibiting the carbonization of bamboo powder, the structural formula of which is shown below:

[0007] Part A is derived from hindered phenolic antioxidants, part B is derived from terminal hydroxyl long-chain alkyl acids, and part C is derived from aminosilane coupling agents; R1 and R2 are each independently selected from C1-C5 alkyl or hydrogen, m is an integer from 0 to 3, n is an integer from 8 to 16, and R3 is a C1-C4 alkyl.

[0008] In this invention, the additive is essentially a multifunctional additive that integrates interfacial coupling, boundary lubrication and free radical capture functions. It reduces frictional heat from the source, interrupts the oxidation chain reaction during the process, and simultaneously enhances interfacial adhesion. It is a key technological breakthrough for preparing high-performance, light-colored PBAT / bamboo powder fully biodegradable composite materials.

[0009] Preferably, the multifunctional additive is obtained by esterification condensation of a carboxyl-containing hindered phenolic antioxidant with a terminal hydroxyl long-chain alkyl acid to obtain an intermediate, followed by amidation condensation with an aminosilane coupling agent.

[0010] Preferably, the carboxyl-containing hindered phenolic antioxidant is at least one of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid or 4-hydroxy-3,5-dimethylbenzoic acid; the terminal hydroxyl long-chain alkyl acid is at least one of 8-hydroxyoctanoic acid, 12-hydroxydodecanoic acid or 16-hydroxyhexadecanoic acid; and the aminosilane coupling agent is at least one of 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

[0011] Preferably, the esterification condensation is carried out under the conditions of dehydrating agent N,N'-dicyclohexylcarbodiimide (DCC) and catalyst 4-dimethylaminopyridine (DMAP), and the reaction temperature of the esterification condensation is 20-30°C and the time is 18-24h.

[0012] Preferably, the amidation condensation is carried out under the conditions of a dehydrating agent of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and a catalyst of 1-hydroxybenzotriazole (HOBt), and the reaction temperature of the amidation condensation is 20-30°C and the time is 18-24h.

[0013] Preferably, the mass ratio of the carboxyl-containing hindered phenolic antioxidant, the terminal hydroxyl long-chain alkyl acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(0.60-0.90):(0.65-1.00):(0.02-0.08); the mass ratio of the intermediate, the aminosilane coupling agent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 1-hydroxybenzotriazole is 1:(0.35-0.70):(0.35-0.75):(0.20-0.50).

[0014] This invention also proposes a masterbatch for PBAT / bamboo powder dustproof netting, which is obtained by pre-modifying bamboo powder with the above-mentioned multifunctional additives to obtain modified bamboo powder, then mixing it with PBAT and melt extruding it.

[0015] Preferably, the pre-modification includes: dispersing bamboo powder and multifunctional additives in an alcohol-water mixed solvent, adjusting the pH to 4-6, and then stirring for a coupling reaction; the stirring coupling reaction is carried out at a temperature of 60-80 ℃ for 1-3 h.

[0016] Preferably, the process parameters for melt extrusion include: a screw speed of 200-300 rpm, a feeding speed of 3-5 Hz, and extrusion temperature zones of 90 ℃, 110 ℃, 130 ℃, 140 ℃, 140 ℃, 140 ℃, 145 ℃, 145 ℃, 145 ℃, 140 ℃, 140 ℃, 140 ℃.

[0017] Preferably, the mass ratio of PBAT, bamboo powder and multifunctional additive is 1:(0.15-0.60):(0.01-0.08).

[0018] Compared with the prior art, the present invention has the following technical effects: (1) The present invention integrates silane anchoring groups, hindered phenolic antioxidant units and long-chain alkyl lubricating structures into a single molecule. The prepared multifunctional additive can be firmly bonded to the surface of bamboo powder, achieving synergistic effect of "anchoring-lubrication-antioxidation", overcoming the defects of traditional physical compounding schemes such as functional dispersion and easy migration.

[0019] (2) The additives of this invention can be anchored to the surface of bamboo powder through silane groups, and the long-chain aliphatic structure and hindered phenolic structure can improve the interfacial interaction between bamboo powder and PBAT. At the same time, they can reduce frictional heat generation and block free radical oxidation, thereby inhibiting the carbonization of bamboo powder during processing. The resulting composite material has a light color, excellent mechanical properties, and a simple preparation process, and has good industrial application value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the synthetic route of the multifunctional auxiliary agent DBHP-12-HDA-APTES described in this invention; Figure 2 This is a schematic diagram illustrating the mechanism of action of PBAT / bamboo powder / DBHP-12-HDA-APTES as described in this invention; Figure 3 The infrared spectra of DBHP, 12-HDA, APTES, DBHP-12-HDA-1 and DBHP-12-HDA-APTES-1 described in this invention are as follows: Figure 4 The following are actual appearance pictures of the PBAT / bamboo powder dustproof net and its masterbatch described in this invention: (a) Example 1; (b) Example 2; (c) Example 3; (d) Comparative Example 1; (e) Comparative Example 2; (f) Comparative Example 3. Detailed Implementation

[0021] The present invention will now be described in detail through specific embodiments. However, these embodiments are clearly provided for illustrative purposes and are not intended to limit the scope of the present invention.

[0022] In the following examples, bamboo powder (600-1000 mesh), polybutylene adipate terephthalate (PBAT), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid (DBHP), 12-hydroxydodecanoic acid (12-HDA), and 3-aminopropyltriethoxysilane (APTES) are all commercially available.

[0023] Example 1 Reference Figure 1 This embodiment proposes a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the following method: (1) Under nitrogen protection, 27.8 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 21.6 g of 12-hydroxydodecanoic acid, and 1.22 g of 4-dimethylaminopyridine were added to a 250 mL three-necked flask, followed by 150 mL of anhydrous dichloromethane. The mixture was stirred and dissolved, and the resulting reaction system was placed in an ice bath and cooled to 0 °C to obtain solution A. 22.7 g of N,N'-dicyclohexylcarbodiimide was dissolved in 50 mL of anhydrous dichloromethane and added dropwise to solution A over 30 min, controlling the temperature not to exceed 5 °C. After the addition was complete, the mixture was stirred at 0 °C for 1 h, the ice bath was removed, and the reaction was allowed to proceed at room temperature (25 °C) for 24 h. After the reaction was completed, the white precipitate was removed by filtration. The filtrate was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine. The organic phase was dried with anhydrous sodium sulfate, filtered, and 40 mL of the solution was added to the flask. The crude product was concentrated under reduced pressure at ℃, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 8:1 → 4:1 gradient elution). The target component was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum at 40 ℃ to constant weight to obtain a white solid, which is the intermediate (DBHP-12-HDA-1). (2) Dissolve 23.8 g of the above intermediate (DBHP-12-HDA-1) and 11.1 g of 3-aminopropyltriethoxysilane in 150 mL of anhydrous tetrahydrofuran, add 6.8 g of 1-hydroxybenzotriazole, stir to dissolve, cool to 0 °C in an ice bath, then add 10.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride in portions, controlling the temperature not to exceed 5 °C. After the addition is complete, stir at 0 °C for 1 h, remove the ice bath, and react at room temperature (25 °C) for 24 h. After the reaction is complete, remove the tetrahydrofuran under reduced pressure at 40 °C, dissolve the residue in 200 mL of dichloromethane, wash successively with phosphate buffer solution with pH 6.5-7.0 and saturated saline, dry the organic phase with anhydrous sodium sulfate, filter, and 40 The crude product was concentrated under reduced pressure at ℃, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 6:1 → 2:1 gradient elution). The target component was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum at 40 ℃ to constant weight to obtain a pale yellow viscous liquid, which is the multifunctional auxiliary agent (DBHP-12-HDA-APTES-1).

[0024] Reference Figure 2 This embodiment also proposes a PBAT / bamboo powder dustproof net, which is prepared by the following method: (1) 0.2 kg of bamboo powder was vacuum dried at 80 °C for 9 h to obtain dried bamboo powder. Then, 20 g of the above DBHP-12-HDA-APTES-1 was dissolved in an ethanol / water mixed solvent, the pH was adjusted to 4.0-5.5, and the mixture was stirred and hydrolyzed for 45 min. The dried bamboo powder was then added, and the mixture was stirred and reacted at 70 °C for 2 h. After filtration and drying, DBHP-12-HDA-APTES-1 modified bamboo powder was obtained. (2) 0.8 kg of PBAT and the above-mentioned DBHP-12-HDA-APTES-1 modified bamboo powder were mixed at high speed. The resulting mixture was melt-extruded. The screw speed was set to 300 rpm, the feeding speed was 4 Hz, and the extrusion temperature zone was set to 90 ℃, 110 ℃, 130 ℃, 140 ℃, 140 ℃, 140 ℃, 145 ℃, 145 ℃, 145 ℃, 140 ℃, 140 ℃, 140 ℃. The resulting extrudate was cooled, drawn, and pelletized to obtain masterbatch. The masterbatch was then blown into film, cut into filaments, and woven to obtain the PBAT / bamboo powder dustproof net.

[0025] Example 2 This embodiment proposes a multifunctional additive to inhibit the carbonization of bamboo powder, which is prepared by the method described in Example 1, except that 8.6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added in batches in step (2) to obtain the multifunctional additive (DBHP-12-HDA-APTES-2).

[0026] This embodiment also proposes a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-2 is used instead of DBHP-12-HDA-APTES-1.

[0027] Example 3 This embodiment proposes a multifunctional additive to inhibit the carbonization of bamboo powder, which is prepared by the method described in Example 1, except that 14.3 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added in batches in step (2) to obtain the multifunctional additive (DBHP-12-HDA-APTES-3).

[0028] This embodiment also proposes a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-3 is used instead of DBHP-12-HDA-APTES-1.

[0029] Example 4 This embodiment proposes a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the method described in Example 1. Except for step (1), in which 27.8 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 16.7 g of 12-hydroxydodecanoic acid, and 0.56 g of 4-dimethylaminopyridine are added, and 18.1 g of N,N'-dicyclohexylcarbodiimide is dissolved in 50 mL of anhydrous dichloromethane to obtain intermediate (DBHP-12-HDA-4); in step (2), 23.8 g of the above intermediate (DBHP-12-HDA-4) and 16.7 g of 3-aminopropyltriethoxysilane are dissolved in 150 mL of anhydrous tetrahydrofuran, and 11.9 g of 1-hydroxybenzotriazole is added. The mixture is stirred to dissolve, cooled to 0 °C in an ice bath, and 17.8 g of 1-hydroxybenzotriazole is added in batches. g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was used to obtain a pale yellow viscous liquid, which is the multifunctional additive (DBHP-12-HDA-APTES-4).

[0030] This embodiment also proposes a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-4 is used instead of DBHP-12-HDA-APTES-1.

[0031] Example 5 This embodiment proposes a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the method described in Example 1. Except for step (1), in which 27.8 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 25.0 g of 12-hydroxydodecanoic acid, and 2.22 g of 4-dimethylaminopyridine are added, and 27.8 g of N,N'-dicyclohexylcarbodiimide is dissolved in 50 mL of anhydrous dichloromethane to obtain intermediate (DBHP-12-HDA-5); in step (2), 23.8 g of the above intermediate (DBHP-12-HDA-5) and 8.3 g of 3-aminopropyltriethoxysilane are dissolved in 150 mL of anhydrous tetrahydrofuran, and 4.8 g of 1-hydroxybenzotriazole is added. The mixture is stirred to dissolve, cooled to 0 °C in an ice bath, and 8.3 g of 1-hydroxybenzotriazole is added in batches. g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was used to obtain a pale yellow viscous liquid, which is the multifunctional additive (DBHP-12-HDA-APTES-5).

[0032] This embodiment also proposes a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-5 is used instead of DBHP-12-HDA-APTES-1.

[0033] Comparative Example 1 This comparative example presents a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the method described in Example 1, except that 4.8 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added in batches in step (2) to obtain the multifunctional additive (DBHP-12-HDA-APTES-6).

[0034] This comparative example also presents a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-6 is used instead of DBHP-12-HDA-APTES-1.

[0035] Comparative Example 2 This comparative example presents a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the method described in Example 1, except that 19.1 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is added in batches in step (2) to obtain the multifunctional additive (DBHP-12-HDA-APTES-7).

[0036] This comparative example also presents a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-7 is used instead of DBHP-12-HDA-APTES-1.

[0037] Comparative Example 3 This comparative example presents a multifunctional additive for inhibiting the carbonization of bamboo powder, which is prepared by the method described in Example 1. Except that in step (2), 0.61 g of 4-dimethylaminopyridine is added instead of 6.8 g of 1-hydroxybenzotriazole, and 11.35 g of N,N'-dicyclohexylcarbodiimide is added in batches instead of 10.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride to obtain the multifunctional additive (DBHP-12-HDA-APTES-8).

[0038] This comparative example also presents a PBAT / bamboo powder dustproof net, which is prepared by the method described in Example 1, except that DBHP-12-HDA-APTES-8 is used instead of DBHP-12-HDA-APTES-1.

[0039] Comparative Example 4 This comparative example presents a comparative auxiliary agent, which is prepared by the following method: Under nitrogen protection, 13.9 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 11.1 g of 3-aminopropyltriethoxysilane were dissolved in 150 mL of anhydrous tetrahydrofuran. 6.8 g of 1-hydroxybenzotriazole was added, and the mixture was stirred until dissolved. The mixture was cooled to 0 °C in an ice bath. Then, 10.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added in portions, with the temperature controlled not exceeding 5 °C. After the addition was complete, the mixture was stirred at 0 °C for 1 h. The ice bath was removed, and the reaction was allowed to proceed at room temperature (25 °C) for 24 h. After the reaction was complete, the tetrahydrofuran was removed by vacuum distillation at 40 °C. The residue was dissolved in 200 mL of dichloromethane and washed successively with phosphate buffer (pH 6.5-7.0) and saturated saline solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and then... The crude product was concentrated under reduced pressure at ℃, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 6:1 → 2:1 gradient elution). The target component was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum at 40 ℃ to constant weight, yielding a pale yellow viscous liquid, which is the contrast agent (DBHP-APTES).

[0040] This comparative example also presents a PBAT / bamboo powder dustproof net, which is prepared by the following method: (1) 0.2 kg of bamboo powder was vacuum dried at 80 °C for 9 h to obtain dried bamboo powder; 13.8 g of the above DBHP-APTES additive and 6.2 g of 12-hydroxydodecanoic acid were dissolved together in an ethanol / water mixed solvent, the pH was adjusted to 4.0-5.5, and the mixture was stirred and hydrolyzed for 45 min before being added to the aforementioned dried bamboo powder. The mixture was stirred and reacted at 70 °C for 2 h, filtered, and dried to obtain bamboo powder modified with the comparative additive. (2) 0.8 kg of PBAT and the bamboo powder modified by the above-mentioned comparative additives were mixed at high speed. The resulting mixture was melt-extruded. The screw speed was set to 300 rpm, the feeding speed was 4 Hz, and the extrusion temperature range was set to 90 ℃, 110 ℃, 130 ℃, 140 ℃, 140 ℃, 140 ℃, 145 ℃, 145 ℃, 145 ℃, 140 ℃, 140 ℃, 140 ℃. The resulting extrudate was cooled, drawn, and pelletized to obtain masterbatch. The masterbatch was then blown into film, cut into filaments, and woven to obtain the PBAT / bamboo powder dustproof net.

[0041] The mechanical properties of the dustproof nets obtained in the above embodiments and comparative examples were tested (GB / T1040.3-2006), as shown in Table 1 below: Table 1. Mechanical property tests and color comparison of the dustproof nets obtained in the examples and comparative examples.

[0042] From Table 1 and Figure 4It can be seen that the PBAT / bamboo powder dustproof nets prepared in Examples 1-3 of this invention all have good mechanical properties and light appearance color. Among them, Example 1 has the best overall performance, with a tensile strength of 24.5 MPa and an elongation at break of 421%; the tensile strengths of Examples 2 and 3 are 22.9 MPa and 23.6 MPa, respectively, and the elongations at break are 355% and 388%, respectively, all of which are significantly better than those of Comparative Examples 1-3.

[0043] The above results demonstrate that by integrating silane anchoring groups, hindered phenolic antioxidant units, and long-chain lubricating structures into the same additive molecule, this invention can effectively improve the interfacial compatibility between bamboo powder and the PBAT matrix, enhance the uniformity of bamboo powder dispersion, and strengthen the stress transfer and deformation capabilities of the composite material. Further comparison of Examples 1-3 shows that the mechanical properties of the composite material initially increase and then slightly decrease with optimization of coupling reaction conditions. Example 1 exhibits the best performance, indicating that an appropriate amount of coupling agent is beneficial for improving the structural integrity of the DBHP-12-HDA-APTES additive and the anchoring efficiency on the bamboo powder surface, allowing for a full synergistic effect of anchoring, lubrication, and antioxidant action. When the amount of coupling agent is too low, the bonding between the additive and the bamboo powder surface is insufficient, weakening the interfacial reinforcement effect. When the amount of coupling agent is too high, side reactions or residues may be introduced, leading to increased internal defects or restricted molecular chain movement. Therefore, the performance of Example 3 is slightly lower than that of Example 1.

[0044] As shown in Comparative Examples 1-3, significantly low or high amounts of coupling agent, or changes in the reaction system, all reduce material performance. Comparative Example 1, due to insufficient coupling reaction, exhibits weak surface modification of bamboo powder and numerous interface defects. While Comparative Example 2 has higher tensile strength than Comparative Example 1, its elongation at break is lower, indicating that excessive coupling agent may cause localized interface stiffening. Comparative Example 3, using a DCC / DMAP system, has a higher risk of byproduct removal and residue, leading to decreased additive purity and interface uniformity, thus resulting in the lowest mechanical properties. In terms of color, the dustproof nets obtained in Examples 1-3 are generally lighter in color, while those in Comparative Examples 1-3 are significantly darker. This indicates that the additives of this invention can reduce processing friction and heat generation through long-chain lubrication structures and capture free radicals, inhibiting thermo-oxidative degradation and bamboo powder carbonization through hindered phenolic structures, thereby achieving simultaneous improvement in mechanical properties and appearance.

[0045] As shown in Comparative Example 4, when only silane anchoring groups and hindered phenolic antioxidant units are integrated into the additive molecule, but 12-hydroxydodecano acid is physically blended in the form of free small molecules instead of being chemically bonded to the additive molecule structure, it will not be able to effectively improve the interfacial compatibility between bamboo powder and PBAT matrix, and the resulting dustproof net color 3 is significantly darker.

[0046] Figure 1 This is a schematic diagram of the synthetic route for the multifunctional auxiliary agent DBHP-12-HDA-APTES of this invention. (Refer to...) Figure 2 It is known that esterification reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and 12-hydroxydodecanoic acid under DCC / DMAP catalysis system yields the intermediate DBHP-12-HDA, which has both hindered phenolic structure and long-chain aliphatic structure. Subsequently, under the action of EDC / HOBt system, the carboxyl group in the intermediate undergoes amidation reaction with the amino group in 3-aminopropyltriethoxysilane to obtain the multifunctional additive DBHP-12-HDA-APTES containing silane anchoring group, hindered phenolic antioxidant unit and long-chain lubricating structure.

[0047] Figure 2 This is a schematic diagram illustrating the synergistic modification mechanism of PBAT / bamboo powder / DBHP-12-HDA-APTES according to the present invention. On one hand, the silane groups in DBHP-12-HDA-APTES undergo a condensation reaction with the hydroxyl groups on the surface of bamboo powder after hydrolysis, forming a stable silicon-oxygen bond structure on the bamboo powder surface, thereby enhancing the interfacial bonding between bamboo powder and the PBAT matrix. Simultaneously, the amide groups in the additives can form hydrogen bonds with the PBAT end groups and the hydroxyl groups on the bamboo powder surface, increasing the interfacial interaction force and enhancing the strength of the composite material. On the other hand, the long-chain aliphatic structure in the additives can play a lubricating and compatibilizing role, improving the dispersion uniformity of bamboo powder in the PBAT matrix and reducing frictional heat generation during processing; the hindered phenolic structure, by capturing free radicals and blocking oxidation chain reactions, inhibits the thermo-oxidative degradation and carbonization of bamboo powder and PBAT during processing. Through the synergistic effect of silane anchoring, interfacial reinforcement, long-chain lubrication, and hindered phenolic antioxidant properties, the processing stability, mechanical properties, and thermo-oxidative aging resistance of the PBAT / bamboo powder composite material are comprehensively improved.

[0048] This invention performs infrared spectral analysis on samples containing DBHP, 12-HDA, APTES, DBHP-12-HDA-1, and DBHP-12-HDA-APTES-1, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the DBHP sample is at 3377 cm⁻¹ -1 A stretching vibration peak of the phenolic hydroxyl group (OH) appears nearby, at 1606 cm⁻¹. -1 A stretching vibration peak of the benzene ring skeleton C=C appeared nearby; the 12-HDA sample showed a peak at 2913 cm⁻¹. -1 and 2848 cm -1 The antisymmetric and symmetric stretching vibration peaks of methylene-CH2- appear at 1682 cm⁻¹. -1 A stretching vibration peak of the carboxyl group (C=O) appears nearby. Compared with DBHP and 12-HDA, the DBHP-12-HDA-2 sample retains both the benzene ring characteristic peak of DBHP and the long-chain methylene characteristic peak of 12-HDA, and reaches a peak at 1297 cm⁻¹.-1 and 1215cm -1 The presence of a relatively obvious COC / CO stretching vibration absorption peak nearby indicates that the carboxyl group in DBHP and the hydroxyl group in 12-HDA underwent an esterification reaction, successfully generating the DBHP-12-HDA-2 intermediate. Furthermore, compared to DBHP-12-HDA-1, DBHP-12-HDA-APTES-1 showed a higher absorption peak at 1071 cm⁻¹. -1 956cm -1 and 769cm -1 The presence of distinct Si-O-Si, Si-OC, and Si-C related absorption peaks nearby indicates the introduction of the APTES silane structure into the system; simultaneously, the absorption peak shape in the carbonyl region changes, and a peak appears at 1600 cm⁻¹. -1 The presence of absorption changes in the vicinity that may overlap with the vibrations of the aromatic ring skeleton and amide bonds, combined with the appearance of characteristic silicon-oxygen peaks, indicates that DBHP-12-HDA and APTES underwent an effective coupling reaction. In summary, DBHP, 12-HDA, and APTES reacted effectively according to the designed route, successfully synthesizing the DBHP-12-HDA-APTES-2 auxiliary agent containing a hindered phenolic structure, a long-chain aliphatic structure, and a silane coupling structure.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multifunctional additive for inhibiting bamboo powder carbonization, characterized in that, Its structural formula is shown below: Part A is derived from hindered phenolic antioxidants, part B is derived from terminal hydroxyl long-chain alkyl acids, and part C is derived from aminosilane coupling agents; R1 and R2 are each independently selected from C1-C5 alkyl or hydrogen, m is an integer from 0 to 3, n is an integer from 8 to 16, and R3 is a C1-C4 alkyl.

2. The multifunctional additive for inhibiting bamboo powder carbonization according to claim 1, characterized in that, The multifunctional additive is obtained by esterification condensation of a carboxyl-containing hindered phenolic antioxidant with a terminal hydroxyl long-chain alkyl acid to obtain an intermediate, followed by amidation condensation with an aminosilane coupling agent.

3. The multifunctional additive for inhibiting bamboo powder carbonization according to claim 2, characterized in that, The carboxyl-containing hindered phenolic antioxidant is at least one of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid or 4-hydroxy-3,5-dimethylbenzoic acid; the terminal hydroxyl long-chain alkyl acid is at least one of 8-hydroxyoctanoic acid, 12-hydroxydodecanoic acid or 16-hydroxyhexadecanoic acid; and the aminosilane coupling agent is at least one of 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

4. The multifunctional additive for inhibiting bamboo powder carbonization according to claim 2 or 3, characterized in that, The esterification condensation is carried out under the conditions of dehydrating agent N,N'-dicyclohexylcarbodiimide and catalyst 4-dimethylaminopyridine. The reaction temperature of the esterification condensation is 20-30℃ and the time is 18-24h.

5. The multifunctional additive for inhibiting bamboo powder carbonization according to claim 2 or 3, characterized in that, The amidation condensation is carried out under the conditions of dehydrating agent of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and catalyst of 1-hydroxybenzotriazole. The reaction temperature of the amidation condensation is 20-30℃ and the time is 18-24h.

6. The multifunctional additive for inhibiting bamboo powder carbonization according to claim 4 or 5, characterized in that, The mass ratio of the carboxyl-containing hindered phenolic antioxidant, the terminal hydroxyl long-chain alkyl acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(0.60-0.90):(0.65-1.00):(0.02-0.08); the mass ratio of the intermediate, the aminosilane coupling agent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 1-hydroxybenzotriazole is 1:(0.35-0.70):(0.35-0.75):(0.20-0.50).

7. A masterbatch for PBAT / bamboo powder dustproof netting, characterized in that, It is obtained by pre-modifying bamboo powder with the multifunctional additive described in any one of claims 1-6 to obtain modified bamboo powder, and then mixing it with PBAT and melt extruding it.

8. The masterbatch for PBAT / bamboo powder dustproof netting according to claim 7, characterized in that, The pre-modification includes: dispersing bamboo powder and multifunctional additives in an alcohol-water mixed solvent, adjusting the pH to 4-6, and then stirring for a coupling reaction; the temperature of the stirring coupling reaction is 60-80 ℃, and the time is 1-3 h.

9. The masterbatch for PBAT / bamboo powder dustproof netting according to claim 7 or 8, characterized in that, The process parameters for melt extrusion include: screw speed of 200-300 rpm, feed rate of 3-5 Hz, and extrusion temperature ranges of 90 ℃, 110 ℃, 130 ℃, 140 ℃, 140 ℃, 140 ℃, 145 ℃, 145 ℃, 145 ℃, 140 ℃, 140 ℃, 140 ℃.

10. The masterbatch for PBAT / bamboo powder dustproof netting according to claim 7 or 8, characterized in that, The mass ratio of PBAT, bamboo powder and multifunctional additive is 1:(0.15-0.60):(0.01-0.08).

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