Bamboo-plastic composite vibrating diaphragm and preparation method and application thereof

Abstract

The invention provides a bamboo-plastic composite vibrating diaphragm and a preparation method and application thereof, and relates to the technical field of vibrating diaphragm materials for loudspeakers. According to the invention, by regulating and controlling the bamboo content and form and compounding with different resins, the rigidity and the stability of the vibrating diaphragm are enhanced, and the sound conduction efficiency and the sound quality performance are optimized through the complementary advantages of the properties of different materials, so that the vibrating diaphragm can adapt to a wider range. The bamboo material is applied to the loudspeaker diaphragm to replace a glass fiber or carbon fiber composite material, so that the energy loss in the vibration process can be effectively reduced, the sound definition and fidelity can be improved, the high energy consumption pollution can be reduced, and the trend of sustainable development can be met.

Description

Technical Field

[0001] The invention relates to the technical field of diaphragm materials for loudspeakers, and in particular to a bamboo-plastic composite diaphragm and a preparation method and application thereof. Background Art

[0002] As an indispensable part of audio equipment, the performance of speakers directly affects the sound reproduction and listening experience. Among the many components of speakers, the diaphragm is one of the key factors that determine the sound quality.

[0003] The existing diaphragm material options are relatively single, resulting in a lack of diversity and customizability in sound quality and timbre performance; carbon fiber and glass fiber materials have a high density, which makes the overall weight of diaphragms made of carbon fiber and glass fiber materials heavy, which may affect the vibration efficiency, and the cost of carbon fiber is relatively high, and glass fiber has problems such as large mechanical wear, high processing energy consumption, non-degradability, and difficult waste disposal; diaphragms made of pulp and polyester fibers often have problems with unnatural sound quality and insufficient fidelity during the sound restoration process; diaphragms made of metal or composite materials may impose a burden on the environment during production and use, and resources are limited. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a bamboo-plastic composite diaphragm and a preparation method and application thereof. The bamboo-plastic composite diaphragm prepared by the present invention has low cost, low density and is easy to process. It can not only meet consumers' demand for high-quality and diversified sound quality, but also promote the green development of the speaker industry. It has important theoretical significance and application value.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a bamboo-plastic composite diaphragm. The raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material. The bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt. The modified thermoplastic resin material includes modified thermoplastic resin granules or modified thermoplastic resin films.

[0007] The preparation method comprises the following steps:

[0008] When the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the preparation method of the bamboo-plastic composite diaphragm includes method one or method two:

[0009] Method 1: Mix bamboo material and modified thermoplastic resin granules, perform melt blending and granulation in sequence to obtain granules; perform a first pressing on the granules to obtain a bamboo-plastic composite diaphragm;

[0010] Method 2: alternately stacking bamboo material and modified thermoplastic resin film, and performing a second pressing to obtain a bamboo-plastic composite diaphragm;

[0011] When the bamboo material is bamboo fiber felt, the preparation method of the bamboo-plastic composite diaphragm includes method three, method four or method five:

[0012] Method 3: alternately stacking bamboo material and modified thermoplastic resin granules, and performing a third pressing to obtain a bamboo-plastic composite diaphragm;

[0013] Method 4: alternately stacking the bamboo material and the modified thermoplastic resin film, and performing a fourth pressing to obtain a bamboo-plastic composite diaphragm;

[0014] Method 5: directly perform the fifth pressing on several layers of bamboo fiber felt to obtain a bamboo-plastic composite diaphragm.

[0015] Preferably, the bamboo material is modified bamboo material; the modification method of the modified bamboo material includes one or more of mechanical treatment, wet heat treatment, radiation treatment, chemical treatment and biological treatment; the mechanical treatment includes surface grinding and / or crushing, the wet heat treatment includes steaming, the radiation treatment includes one or more of flame treatment, corona treatment, microwave treatment and plasma treatment, the chemical treatment includes modifier treatment, and the biological treatment includes one or more of microbial degradation, enzymatic modification and biological coating;

[0016] The modifying agent used in the modified bamboo material includes alkaline compounds, polydopamine, silane coupling agent KH550 or maleic anhydride grafted polyolefin solution.

[0017] Preferably, the raw materials for preparing the modified thermoplastic resin material include thermoplastic resin, cross-linking agent and functional additives;

[0018] The thermoplastic resin includes one or more of PP, PET, PE, PLA, PBAT, PBS, PA and viscose fiber;

[0019] The crosslinking agent includes one or more of maleic anhydride grafted polyolefin, silane coupling agent and polyvinyl alcohol, wherein the maleic anhydride grafted polyolefin includes maleic anhydride grafted polypropylene and / or maleic anhydride grafted poly POE; the silane coupling agent includes KH550, titanate or monosilane; the polyvinyl alcohol is low-polymerization degree polyvinyl alcohol and / or medium-polymerization degree polyvinyl alcohol; the mass of the crosslinking agent is 1-20% of the mass of the thermoplastic resin;

[0020] The functional additives include antioxidants and / or mildewproofing agents; the antioxidants include one or more of antioxidant KY-1010, vinyl POSS nano-modifiers and methacrylic POSS nano-enhancers; the mildewproofing agents include one or more of polystyrene caprylate, polypyridine, cinnamon oil, camphor powder, titanium phosphate and silane; the mass of the functional additives accounts for 1 to 15% of the mass of the thermoplastic resin.

[0021] Preferably, the raw materials for preparing the bamboo-plastic composite diaphragm further include fillers, and the fillers include one or more of metal fillers and inorganic non-metal fillers.

[0022] Preferably, the filler includes one or more of floating beads, hollow glass microbeads, inorganic mineral powder, inorganic mineral fibers and metal short fibers.

[0023] Preferably, the raw materials for preparing the bamboo-plastic composite diaphragm further include embedded steel bars; the embedded steel bars are composed of fiber embedded steel bars.

[0024] Preferably, the anchoring includes one-dimensional anchoring or two-dimensional anchoring.

[0025] The present invention provides a bamboo-plastic composite diaphragm prepared by the preparation method described in the above technical solution.

[0026] Preferably, the density of the bamboo-plastic composite diaphragm is 0.5-1.2 g / cm 3 , creep modulus is 800~1200Mpa, and Young's modulus is 25~45GPa.

[0027] The present invention provides application of the bamboo-plastic composite diaphragm described in the above technical solution in loudspeaker diaphragm materials.

[0028] The invention provides a method for preparing a bamboo-plastic composite diaphragm. The raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material. The bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt. The modified thermoplastic resin material includes modified thermoplastic resin granules or modified thermoplastic resin film. The preparation method includes the following steps: when the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the preparation method of the bamboo-plastic composite diaphragm includes method one or method two: method one, mixing the bamboo material with the modified thermoplastic resin granules, and sequentially performing melt blending and granulation to obtain granules; The granular material is subjected to a first pressing to obtain a bamboo-plastic composite diaphragm; Method 2: Bamboo material and modified thermoplastic resin film are alternately stacked and laid, and a second pressing is performed to obtain a bamboo-plastic composite diaphragm; When the bamboo material is bamboo fiber felt, the preparation method of the bamboo-plastic composite diaphragm includes Method 3, Method 4 or Method 5: Method 3: Bamboo material and modified thermoplastic resin granular material are alternately stacked and laid, and a third pressing is performed to obtain a bamboo-plastic composite diaphragm; Method 4: Bamboo material and modified thermoplastic resin film are alternately stacked and laid, and a fourth pressing is performed to obtain a bamboo-plastic composite diaphragm; Method 5: Several layers of bamboo fiber felt are directly subjected to a fifth pressing to obtain a bamboo-plastic composite diaphragm. In the present invention, bamboo material, as a natural material with abundant resources, has the characteristics of fast growth rate and strong regeneration ability. Bamboo material (including one or more of bamboo powder, short bamboo fiber and long bamboo fiber) is light in weight and low in density, which is beneficial to improving the vibration efficiency and response speed of the diaphragm. At the same time, the multi-layer structure and good mechanical properties of bamboo fiber enable it to exhibit good acoustic performance in a wider frequency band; its natural fiber structure and physical properties give it unique sound quality and timbre, manifesting as a warm and natural sound characteristic; using bamboo fiber as the material of the speaker diaphragm can not only make full use of the rich bamboo resources and promote the diversified development of the bamboo industry, but also cleverly integrate bamboo elements and China's profound bamboo culture, giving audio equipment a unique cultural connotation and natural charm.

[0029] The present invention not only enhances the rigidity and stability of the diaphragm by regulating the content and morphology of bamboo materials and compounding with different thermoplastic resins, but also optimizes the efficiency of sound conduction and sound quality performance through the complementary advantages of different material properties, so that the diaphragm can adapt to a wider range of sound. The present invention uses bamboo materials in speaker diaphragms to replace glass fiber or carbon fiber composite materials, which can effectively reduce energy loss during vibration, improve sound clarity and fidelity, reduce high energy consumption pollution, and conform to the trend of sustainable development.

[0030] The present invention can not only meet the needs of consumers for high-quality and diversified sound quality, but also promote the green development of the speaker industry, and has important theoretical significance and application value. The present invention aims to overcome the limitations of the prior art and propose an innovative bamboo-plastic composite diaphragm for speakers (also known as prepreg diaphragm) and a preparation method thereof, so as to achieve performance optimization and environmental protection upgrade of speaker diaphragm materials.

[0031] The present invention has the following beneficial effects:

[0032] (1) The bamboo-plastic composite diaphragm is designable. By varying the bamboo content and form and compounding it with different resins, it can achieve a variety of vibration modes and frequency response characteristics, thereby meeting the sound quality and timbre requirements in different application scenarios and achieving a customizable sound quality experience.

[0033] (2) The low density of bamboo helps to reduce the overall weight of the diaphragm, improve vibration efficiency and sound response speed;

[0034] (3) Bamboo has good sound conduction and damping properties, reducing unnecessary vibration attenuation and resonance, thereby improving the fidelity and naturalness of sound quality;

[0035] (4) Bamboo is a natural renewable resource, and its production and use process has little impact on the environment, which helps reduce dependence on traditional resources;

[0036] (5) Compared with traditional fiber composite diaphragm materials such as carbon fiber and glass fiber, bamboo-plastic composite diaphragm has the advantages of lower cost, less mechanical wear, lower processing energy consumption, and easy degradation and waste disposal, which reduces production costs and environmental pressure.

[0037] In the present invention, a method of combining multiple interface modifications (including bamboo material modification, crosslinking agent and functional additives in modified thermoplastic resin materials, and fillers and reinforcing bars in the preparation raw materials) can improve the distribution of bamboo materials in the bamboo-plastic composite diaphragm, improve the uniformity of bamboo material distribution, and improve the interface compatibility and mechanical properties of the bamboo-plastic composite diaphragm. The present invention uses a prepreg process to prepare a bamboo-plastic composite diaphragm, and adjusts the diaphragm sound quality of the bamboo-plastic composite diaphragm by compounding different bamboo materials with resins, performing interface modification on the bamboo materials (i.e., the bamboo materials are modified bamboo materials, and the modifiers are added by plasma treatment, and the modifiers are silane coupling agents, etc., and alkali treatment), appropriate process parameters (pressure, temperature, time, etc.), and adding reinforcing bar layers, etc., thereby reducing the distortion of the diaphragm, improving the diaphragm sound quality, and achieving the diaphragm performance requirements of good rigidity (high specific curvature), low density, low frequency, high elasticity, and appropriate internal damping. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the preparation process of the bamboo-plastic composite diaphragm in the embodiment;

[0039] Figure 2 This is a physical picture of the bamboo-plastic composite diaphragm prepared in Example 1. DETAILED DESCRIPTION

[0040] The present invention provides a method for preparing a bamboo-plastic composite diaphragm. The raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material. The bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt. The modified thermoplastic resin material includes modified thermoplastic resin granules or modified thermoplastic resin films.

[0041] The preparation method comprises the following steps:

[0042] When the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the preparation method of the bamboo-plastic composite diaphragm includes method one or method two:

[0043] Method 1: Mix bamboo material and modified thermoplastic resin granules, perform melt blending and granulation in sequence to obtain granules; perform a first pressing on the granules to obtain a bamboo-plastic composite diaphragm;

[0044] Method 2: alternately stacking bamboo material and modified thermoplastic resin film, and performing a second pressing to obtain a bamboo-plastic composite diaphragm;

[0045] When the bamboo material is bamboo fiber felt, the preparation method of the bamboo-plastic composite diaphragm includes method three, method four or method five:

[0046] Method 3: alternately stacking bamboo material and modified thermoplastic resin granules, and performing a third pressing to obtain a bamboo-plastic composite diaphragm;

[0047] Method 4: alternately stacking the bamboo material and the modified thermoplastic resin film, and performing a fourth pressing to obtain a bamboo-plastic composite diaphragm;

[0048] Method 5: directly perform the fifth pressing on several layers of bamboo fiber felt to obtain a bamboo-plastic composite diaphragm.

[0049] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0050] In the present invention, the raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material, the bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt, and the modified thermoplastic resin material includes modified thermoplastic resin pellets or modified thermoplastic resin film.

[0051] In the present invention, the particle size of the bamboo powder is preferably 20-500 μm; the particle size of the bamboo charcoal powder is preferably 0.1-2.1 μm. The length of the bamboo fiber is preferably ≥20 mm, and the diameter of the bamboo fiber is preferably 0.01-1.20 mm; the preparation method of the bamboo fiber can be found in CN 110592685 A.

[0052] In the present invention, the bamboo material is preferably modified bamboo material; the modification method of the modified bamboo material preferably includes one or more of mechanical treatment, wet heat treatment, radiation treatment, chemical treatment and biological treatment; the mechanical treatment preferably includes surface grinding and / or crushing, the wet heat treatment includes steaming, the radiation treatment preferably includes one or more of flame treatment, corona treatment, microwave treatment and plasma treatment, the chemical treatment preferably includes modifier treatment, and the biological treatment includes one or more of microbial degradation, enzymatic modification and biological coating. The modifier used in the modified bamboo material preferably includes alkaline compounds, polydopamine, silane coupling agent KH550 or maleic anhydride grafted polyolefin solution. The alkaline compound can be an alkali metal hydroxide and / or an alkaline earth metal compound. In the present invention, the preparation method of the modified bamboo material preferably includes: mixing the bamboo material and the modifier, standing, and then washing, drying and heat treating in sequence to obtain the modified bamboo material. In the present invention, the standing time is preferably 0.5 to 6 hours. In the present invention, the washing liquid used is preferably deionized water; the drying temperature is preferably 25±2°C; the drying time is preferably 0.5-6h. In the present invention, the heat treatment temperature is preferably 103±2°C, and the heat preservation time is preferably 0.5-6h; drying refers to drying in the air, and heat treatment is to further reduce the moisture content of the bamboo material for subsequent processing.

[0053] In the present invention, the thickness of the bamboo fiber felt is preferably 1 to 40 mm. In the present invention, the bamboo fiber felt is formed by a composite of bamboo fiber and resin fiber, and the bamboo fiber felt contains a thermoplastic resin. The thermoplastic resin preferably includes one or more of PP, PET, PE, PLA, PBAT, PBS, PA and viscose fiber. In the present invention, the bamboo fiber felt is preferably prepared by weighing, opening, homogenizing, mechanically combing, air-laying and needle-punching the bamboo fiber felt raw material in sequence. In the present invention, the bamboo fiber felt raw material includes bamboo fiber and thermoplastic resin, or the bamboo fiber felt raw material includes bamboo fiber, thermoplastic resin and other fibers. The length of the bamboo fiber is preferably 2 to 250 mm, and the diameter is preferably 0.01 to 1.20 mm. The thermoplastic resin preferably includes one or more of PP, PET, PE, PLA, PBAT, PBS, PA and viscose fiber. In the present invention, the other fibers preferably include one or more of other chemical fibers, metal fibers and inorganic non-metallic fibers; the other chemical fibers preferably include regenerated fibers; the metal fibers preferably include aluminum fibers and / or titanium fibers; the inorganic non-metallic fibers preferably include glass fibers. The mass percentage of the thermoplastic resin in the bamboo fiber felt is ≥15%.

[0054] In the present invention, the modified thermoplastic resin material includes modified thermoplastic resin pellets or modified thermoplastic resin films.

[0055] In the present invention, the raw materials for preparing the modified thermoplastic resin material preferably include thermoplastic resin, crosslinking agent and functional additives. The mass percentage of the crosslinking agent to the mass percentage of the thermoplastic resin is preferably 1-20%, more preferably 2-18%, and specifically 15% or 2.5% in the embodiment. The mass percentage of the functional additive to the mass percentage of the thermoplastic resin is preferably 1-15%, more preferably 2-10%, and specifically 3%, 8% or 6.5% in the embodiment. In the present invention, the thermoplastic resin preferably includes one or more of PP, PET, PE, PLA, PBAT, PBS, PA and viscose fiber. In the present invention, the crosslinking agent preferably includes one or more of maleic anhydride grafted polyolefin, silane coupling agent and polyvinyl alcohol; the maleic anhydride grafted polyolefin preferably includes maleic anhydride grafted polypropylene and / or maleic anhydride grafted poly POE. In the present invention, the silane coupling agent preferably includes KH550, titanate or monosilane. In the present invention, the polyvinyl alcohol is preferably low and / or medium degree of polymerization polyvinyl alcohol. In the present invention, the functional additives preferably include antioxidants and / or mildew inhibitors; the antioxidants preferably include one or more of antioxidant KY-1010, vinyl POSS nano-modifiers and methacrylic POSS nano-enhancers; the mildew inhibitors preferably include one or more of polystyrene caprylate, polypyridine, cinnamon oil, camphor powder, titanium phosphate salts and silanes.

[0056] In the present invention, the modified thermoplastic resin pellets are preferably obtained by mechanical blending, melt blending and granulation of raw materials for preparing modified thermoplastic resin materials; the granulation is carried out in a granulator, and the temperatures of the first to fourth zones of the granulator are 150±10°C, 170±10°C, 170±10°C and 160±10°C respectively. The particle size of the modified thermoplastic resin pellets is preferably 0.2-2mm. The preparation method of the modified thermoplastic resin film preferably includes: preparing the modified thermoplastic resin pellets into a modified thermoplastic resin film by pressing in a hot press molding method; the pressing includes: hot pressing temperature of 180°C, pressure of 0.5MPa, time of 1min, cold pressing temperature of 10°C, cold pressing pressure of 5MPa, and cold pressing time of 5min. The thickness of the modified thermoplastic resin film is preferably 0.1-0.3mm.

[0057] In the present invention, the raw materials for preparing the bamboo-plastic composite diaphragm preferably also include fillers. In the present invention, the fillers preferably include one or more of metal fillers and inorganic non-metallic fillers. In the present invention, the fillers preferably include one or more of floating beads, hollow glass microbeads, inorganic mineral powders, inorganic mineral fibers and metal short fibers. In the present invention, the diameter of the floating beads is preferably 0.1-0.2 mm; the diameter of the hollow glass microbeads is preferably 20-80 microns; the diameter of the inorganic mineral powder is preferably 0.02-0.2 mm; the diameter of the inorganic mineral fibers is preferably 0.02-0.2 mm; the inorganic mineral fibers are preferably quartz fibers; the diameter of the metal short fibers is preferably 0.2-1 mm.

[0058] In the present invention, the method for adding the filler preferably includes: when the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, in the method one, the method for adding the filler is preferably: blending with the bamboo material and modified thermoplastic resin granules, or after obtaining the granules, mixing with the granules and then performing the first pressing. In the method two, the bamboo material and the filler are mixed and then alternately stacked and laid with the modified thermoplastic resin film, or the bamboo material, the filler and the modified thermoplastic resin film are alternately stacked and laid. When the bamboo material is bamboo fiber felt, before the fourth pressing, the fifth pressing or the sixth pressing, in the method three, the bamboo material, the filler and the modified thermoplastic resin granules are alternately stacked and laid; in the method four, the bamboo material, the filler and the modified thermoplastic resin film are alternately stacked and laid; in the method five, several layers of bamboo fiber felt and the filler are alternately stacked and laid.

[0059] In the present invention, the raw materials for preparing the bamboo-plastic composite diaphragm preferably also include embedded steel bars. The embedded steel bars are composed of fiber embedded steel bars. In the present invention, the thickness of the embedded steel bars is preferably 0.5 to 2 mm. In the present invention, the fiber embedded steel bars are preferably woven from one or more of bamboo fibers, glass fibers and metal fibers. In the present invention, the diameter range of the bamboo fibers, chemical fibers or metal fibers is preferably 0.1 to 2 mm. In the present invention, the weaving preferably includes one-dimensional weaving and / or two-dimensional weaving. The present invention utilizes embedded steel bars to strengthen and toughen the bamboo-plastic composite diaphragm, thereby increasing the designability of the bamboo fiber composite diaphragm, and can be used to specifically prepare or strengthen various composite diaphragms.

[0060] In the present invention, the implanted reinforcement preferably includes one-dimensional implanted reinforcement or two-dimensional implanted reinforcement. In the present invention, the preparation method of the one-dimensional implanted reinforcement preferably includes: weaving fibers into bundles of fibers to obtain one-dimensional implanted reinforcement. In the present invention, the length of a single fiber in the one-dimensional implanted reinforcement is preferably 10 to 2000 mm, the diameter is preferably 1 to 50 mm, the linear density is preferably 0.5 to 10000 tex, the unidirectional arrangement spacing is preferably 1 to 200 mm, and the fiber volume content is preferably 5 to 80%.

[0061] In the present invention, the preparation method of the two-dimensional implanted reinforcement preferably includes: firstly weaving the fibers into bundles of fibers according to the preparation method of the one-dimensional implanted reinforcement, and weaving the bundles of fibers in full transverse, full longitudinal or orthogonal directions to obtain a net or belt. In the present invention, the weaving angle between the fibers in the two-dimensional implanted reinforcement is preferably 0 to 180°, the length of the net or belt is preferably 100 to 2000 mm, the width is preferably 50 to 2000 mm, the thickness is preferably 0.1 to 10 mm, and the fiber volume content is preferably 20 to 70%.

[0062] In a specific embodiment of the present invention, the specific type of the implanted reinforcement is set in a suitable arrangement mode; when the implanted reinforcement is a one-dimensional implanted reinforcement, the unidirectional arrangement spacing is preferably 1 to 20 mm; when the implanted reinforcement is a two-dimensional implanted reinforcement, the inter-fiber weaving angle is preferably 0 to 180°, more preferably 30 to 90°. The selection of materials, weaving methods and preparation processes of the implanted reinforcement in the present invention can refer to CN115368707 A.

[0063] In the present invention, the method of adding the embedded steel bars preferably includes: when the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the method of adding the embedded steel bars is to directly lay them flat in the system before the first pressing or the second pressing hot pressing; when the bamboo material is bamboo fiber felt, the method of adding the embedded steel bars is to directly lay them flat in the system before the fourth pressing, the fifth pressing or the sixth pressing hot pressing.

[0064] In the present invention, the raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material, the bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt, the modified thermoplastic resin material includes modified thermoplastic resin granules or modified thermoplastic resin film, and in the bamboo-plastic composite diaphragm: the mass of the bamboo material accounts for a percentage of the total mass of the bamboo material and the modified thermoplastic resin material of preferably 5 to 90%, and specifically preferably 15 to 85%.

[0065] In the present invention, when the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the preparation method of the bamboo-plastic composite diaphragm includes method one or method two:

[0066] Method 1: Mix bamboo material and modified thermoplastic resin granules, perform melt blending and granulation in sequence to obtain granules; perform a first pressing on the granules to obtain a bamboo-plastic composite diaphragm;

[0067] Method 2: alternately stack bamboo material and modified thermoplastic resin film, and perform a second pressing to obtain a bamboo-plastic composite diaphragm.

[0068] The following is a detailed description of method 1: bamboo material and modified thermoplastic resin pellets are mixed, melt blended and granulated in sequence to obtain pellets; the pellets are first pressed to obtain a bamboo-plastic composite diaphragm. In the present invention, the mass of the bamboo material accounts for preferably 5 to 90% of the total mass of the bamboo material and the modified thermoplastic resin pellets, and is preferably 15 to 85%, and is specifically 30% in the embodiment.

[0069] In a specific embodiment of the present invention, the bamboo material and modified thermoplastic resin granules preferably include: 30wt% modified bamboo powder, 20wt% modified PBAT granules and 50wt% modified PP granules, wherein the modified bamboo powder is polydopa modified bamboo powder. The modified PBAT granules preferably include PBAT, titanium phosphate accounting for 5wt% of PBAT, camphor powder accounting for 3wt% of PBAT, and maleic anhydride grafted polypropylene accounting for 2.5wt% of PBAT. The modified PP granules preferably include PP, cassia oil accounting for 3wt% of PP as polypropylene, silane accounting for 15wt% of PP as polypropylene, and maleic anhydride grafted polypropylene accounting for 2.5wt% of PP.

[0070] In the present invention, the mixing of the bamboo material and the modified thermoplastic resin pellets is preferably carried out in a high-speed mixer. In the present invention, the melt blending is preferably carried out in a twin-screw extruder; the temperature of the melt blending is preferably 160±10°C, 170±10°C, 190±10°C, 180±10°C and 150±10°C in sequence. In the present invention, the granulation is preferably carried out in a pelletizer. In the present invention, the diameter of the pellets is preferably 0.2 to 2 mm.

[0071] In the present invention, when the bamboo-plastic composite diaphragm is prepared by method 1, the raw materials for preparing the bamboo-plastic composite diaphragm also include embedded steel bars. The embedded steel bars are preferably two-dimensional embedded steel bars. Before the first pressing, the method 1 preferably also includes: alternately stacking the granular material and the two-dimensional embedded steel bars.

[0072] In the present invention, the first pressing is preferably performed in a hot press; the first pressing preferably includes hot pressing and cold pressing. In the present invention, the temperature of the hot pressing is preferably 160-190°C, the pressure of the hot pressing is preferably 1-5MPa, and the time of the hot pressing is preferably 5-20min; the temperature of the cold pressing is preferably 5-35°C, the pressure of the cold pressing is preferably 0-5MPa, and the time of the cold pressing is preferably 5-20min.

[0073] In the present invention, the thickness of the bamboo-plastic composite diaphragm obtained by method 1 is preferably 0.1-10 mm.

[0074] The second method is described in detail below: bamboo material and modified thermoplastic resin film are alternately stacked and laid, and a second pressing is performed to obtain a bamboo-plastic composite diaphragm.

[0075] In the present invention, when the bamboo-plastic composite diaphragm is prepared by method 2, the raw materials for preparing the bamboo-plastic composite diaphragm also include fillers and / or embedded steel bars. The embedded steel bars are preferably one-dimensional embedded steel bars. The alternating layering and laying in method 2 is replaced by: alternately layering and laying bamboo materials, fillers and / or embedded steel bars, and modified thermoplastic resin films. Or before the alternating layering and laying in method 2, the bamboo materials and the fillers are mixed to obtain a mixture; the alternating layering and laying in method 2 is replaced by: alternately layering and laying the mixture, embedded steel bars, and modified thermoplastic resin films.

[0076] In the present invention, the modified bamboo material in the second method is preferably modified by KH550. The modified thermoplastic resin film is a modified polylactic acid film. The modified polylactic acid film preferably comprises PLA, polypyridine accounting for 5wt% of PLA is polylactic acid, vinyl POSS nano-modifier accounting for 1.5wt% of PLA is polylactic acid, and maleic anhydride grafted poly POE accounting for 2.5wt% of PLA.

[0077] In a specific embodiment of the present invention, the alternately stacked paving method in method 2 preferably includes: laying the bamboo material flat on the modified thermoplastic resin film on the pressing plate, then covering it with one-dimensional embedded steel bars, and finally covering it with the upper modified thermoplastic resin film. In the present invention, the inner layer of the pressing plate is affixed with release paper to prevent the thermoplastic matrix from adhering to the pressing plate.

[0078] In the present invention, the second pressing is preferably hot pressing and cold pressing performed in sequence; hot pressing fuses the materials, and cold pressing shapes the finished product. In the present invention, the temperature of the hot pressing is preferably 170±10°C, the pressure is preferably 1±0.5MPa, and the time is preferably 1 to 5min. The pressure of the cold pressing is preferably 0 to 5MPa, and the time of the cold pressing is preferably 5 to 20min.

[0079] Alternatively, in the present invention, the method 2 is replaced by the following steps: alternately stacking and laying bamboo materials and modified thermoplastic resin films, performing a first second pressing, and obtaining an initial composite film; alternately stacking and laying the initial composite film, performing a second second pressing, and obtaining a bamboo-plastic composite diaphragm. In the invention, the bamboo material is modified KH550 modified bamboo fiber. The modified thermoplastic resin film is prepared from modified PLA pellets and modified PBAT pellets, and the mass ratio of the modified PLA pellets to the modified PBAT pellets is preferably 70:30. The percentage of the bamboo material in the total mass of the bamboo material and the modified thermoplastic resin film is preferably 5 to 90%, specifically preferably 15 to 85%, and specifically 30% in the embodiment.

[0080] In the present invention, the modified thermoplastic resin film is preferably prepared from modified PLA pellets and modified PBAT pellets, and the modified polylactic acid pellets preferably include PLA, polypyridine accounting for 5wt% of PLA is polylactic acid, vinyl POSS nano-modifier accounting for 1.5wt% of PLA is polylactic acid, and maleic anhydride grafted poly POE accounting for 2.5wt% of PLA. The modified PBAT pellets preferably include PBAT, titanium phosphate accounting for 5wt% of PBAT, camphor powder accounting for 3wt% of PBAT, and maleic anhydride grafted polypropylene accounting for 2.5wt% of PBAT. In the present invention, the alternating stacking of the bamboo material and the modified thermoplastic resin film preferably includes: sequentially laying the modified thermoplastic resin film, the modified bamboo material and the modified thermoplastic resin film; then performing the first and second pressing; obtaining the initial composite film. The parameters of the first second pressing include: the temperature of the hot pressing is preferably 170±10°C, the pressure is preferably 1±0.5MPa, and the time is preferably 1-5min. The pressure of the cold pressing is preferably 0-5MPa, and the time of the cold pressing is preferably 5-20min. The second second parameters of the second pressing include: the hot pressing temperature is 170±10°C, the pressure is 1±0.5MPa, and the time is 1min.

[0081] In the present invention, the thickness of the bamboo-plastic composite diaphragm obtained by method 2 is preferably 0.1-10 mm.

[0082] In the present invention, when the bamboo material is bamboo fiber felt, the preparation method of the bamboo-plastic composite diaphragm includes method three, method four or method five:

[0083] Method 3: alternately stacking bamboo material and modified thermoplastic resin granules, and performing a third pressing to obtain a bamboo-plastic composite diaphragm;

[0084] Method 4: alternately stacking the bamboo material and the modified thermoplastic resin film, and performing a fourth pressing to obtain a bamboo-plastic composite diaphragm;

[0085] Method 5: directly perform the fifth pressing on several layers of bamboo fiber felt to obtain a bamboo-plastic composite diaphragm.

[0086] The following is a detailed description of method three: alternately stack bamboo and modified thermoplastic resin pellets, perform a third pressing, and obtain a bamboo-plastic composite diaphragm. In the present invention, the bamboo is preferably KH550 modified bamboo fiber felt. The modified thermoplastic resin pellets are modified polypropylene pellets. The modified PP pellets preferably include PP, cassia oil accounting for 3wt% of PP as polypropylene, monosilane accounting for 15wt% of PP as polypropylene, and maleic anhydride grafted polypropylene accounting for 2.5wt% of PP.

[0087] In the present invention, the third pressing is preferably performed in a hot press; the third pressing preferably includes hot pressing and cold pressing performed in sequence; hot pressing fuses the materials, and cold pressing shapes the finished product. The temperature of the hot pressing is preferably 170-190°C, the pressure of the hot pressing is preferably 1-5MPa, and the time of the hot pressing is preferably 5-20min; the temperature of the cold pressing is preferably 5-35°C, the pressure of the cold pressing is preferably 0-5MPa, and the time of the cold pressing is preferably 5-20min. The present invention solidifies the thermoplastic resin through the third pressing and tightly combines it with the bamboo fiber.

[0088] In a specific embodiment of the present invention, the modified bamboo fiber felt is preferably modified with KH550.

[0089] In a specific embodiment of the present invention, the modified thermoplastic resin pellets are modified PP pellets, and the modified PP pellets preferably include PP, cassia oil accounting for 3wt% of PP, silane accounting for 15wt% of PP, and maleic anhydride grafted polypropylene accounting for 2.5wt% of PP.

[0090] In the present invention, during the alternating layering, the modified thermoplastic resin granules are only required to be fully spread on the surface of the bamboo fiber felt. The alternating layering is performed in a mold.

[0091] In the present invention, the thickness of the bamboo-plastic composite diaphragm obtained by method three is preferably 1 to 15 mm.

[0092] The following is a detailed description of method four: alternately stack bamboo materials and modified thermoplastic resin films, perform a fourth pressing, and obtain a bamboo-plastic composite diaphragm. In the present invention, the alternate stacking is performed in a mold. In the present invention, the fourth pressing preferably includes hot pressing and cold pressing performed in sequence; hot pressing fuses the materials, and cold pressing shapes the finished product. In the present invention, the temperature of the hot pressing is preferably 170±10°C, the pressure is preferably 1±0.5MPa, and the time is preferably 1 to 5min. The temperature of the cold pressing is preferably 5 to 35°C, the pressure of the cold pressing is preferably 0 to 5MPa, and the time of the cold pressing is preferably 5 to 20min.

[0093] In the present invention, the thickness of the bamboo-plastic composite diaphragm obtained by method 4 is preferably 0.05-5 mm.

[0094] The following is a detailed description of method five: directly subject several layers of bamboo fiber felt to the sixth pressing to obtain a bamboo-plastic composite diaphragm. In the present invention, the fifth pressing preferably includes hot pressing and cold pressing performed in sequence; hot pressing fuses the materials, and cold pressing shapes the finished product. In the present invention, the temperature of the hot pressing is preferably 140 to 190°C, the pressure of the hot pressing is preferably 0.5 to 2.0 MPa, and the time of the hot pressing is preferably 1 to 30 minutes. The temperature of the cold pressing is preferably 5 to 35°C, the pressure of the cold pressing is preferably 0 to 5 MPa, and the time of the cold pressing is preferably 5 to 20 minutes.

[0095] In the present invention, the thickness of the bamboo-plastic composite diaphragm obtained by method five is preferably 1 to 15 mm.

[0096] The present invention provides a bamboo-plastic composite diaphragm prepared by the preparation method described in the above technical solution. In a specific embodiment of the present invention, the density of the bamboo-plastic composite diaphragm is 0.5-1.2 g / cm 3 , creep modulus is 800~1200Mpa, and Young's modulus is 25~45GPa.

[0097] The present invention provides the application of the bamboo-plastic composite diaphragm described in the above technical solution in diaphragm materials, preferably applied to diaphragm materials for loudspeakers.

[0098] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0099] Embodiment 1 (method three)

[0100] A bamboo felt reinforced polypropylene composite diaphragm comprises: 50 parts (by weight, the same below) of KH550 modified bamboo felt and 50 parts of unmodified PP resin system.

[0101] (1) 40 g of KH550 was added to 1960 g of anhydrous ethanol and stirred for 5 min. A bamboo felt material (2 mm thick, 100 mm long, and 100 mm wide) was immersed in the mixture, and the mixture was sealed with a plastic wrap and allowed to stand for 30 min. The resulting product was washed with deionized water and dried, and then placed in an oven at 103° C. for heat treatment for 2 h to obtain a modified bamboo felt material. The specific preparation method of the bamboo felt material is as follows: a bamboo fiber material and a PP fiber are mechanically combed and / or air-laid, and then needle-punched to obtain a bamboo felt material (i.e., a bamboo fiber felt), wherein the mass percentage of the PP fiber in the bamboo fiber felt is 15%.

[0102] (2) placing unmodified polypropylene pellets and an auxiliary agent (cassia oil is 3wt% of polypropylene, monosilane is 15wt% of polypropylene, and maleic anhydride grafted polypropylene is 2.5wt% of polypropylene) in a high mixer and blending for 30 minutes, then placing in a granulator for granulation, and pelletizing the obtained material in a granulator, the temperatures of zones 1 to 4 of the granulator are 150±10° C., 170±10° C., 170±10° C. and 160±10° C., respectively, to obtain modified polypropylene pellets (modified PP pellets);

[0103] (3) The modified bamboo felt material and the modified polypropylene granules are alternately laid in a mold, and then hot-pressed and cold-pressed to obtain a bamboo felt material reinforced polypropylene composite diaphragm; the hot-pressing temperature is 170° C., the hot-pressing pressure is 1.0 MPa, and the hot-pressing time is 5 min. The cold-pressing temperature is 5° C., the cold-pressing pressure is 2 MPa, and the cold-pressing time is 5 min.

[0104] The composite diaphragm prepared by the above method has a density of 0.6 g / cm 3 , the creep modulus is 1000MPa, and the Young's modulus is 31.8GPa. The obtained composite diaphragm has the characteristics of high creep modulus, high stiffness, small elastic deformation and light weight.

[0105] Embodiment 2 (method 2)

[0106] A bamboo fiber reinforced polylactic acid composite diaphragm, in which the mass of the KH550 modified bamboo fiber accounts for 30% of the total mass of the KH550 modified bamboo fiber and the modified polylactic acid granules.

[0107] (1) KH550 was used to modify the interface of bamboo fiber (i.e. short fiber, length 100-150 mm, diameter 0.12-0.15 mm). 40 g KH550 was added to 1960 g anhydrous ethanol, stirred for 5 min, then 100 g bamboo fiber (length 100-150 mm, diameter 0.12-0.15 mm) was added, and stirring continued for 25 min. The mixture was sealed with plastic wrap and allowed to stand for 30 min. The obtained product was washed with deionized water and dried, and then placed in a 103°C oven for heat treatment for 2 h to obtain modified bamboo fiber.

[0108] (2) Polylactic acid (PLA) and additives (polypyridine is 5wt% of polylactic acid, vinyl POSS nano-modifier is 1.5wt% of polylactic acid, and maleic anhydride grafted poly POE is 2.5wt% of polylactic acid) are placed in a high mixer and blended for 30 minutes, then placed in a granulator for granulation, and the resulting material is pelletized in a pelletizer. The temperatures of zones 1 to 4 of the granulator are 150±10°C, 170±10°C, 180±10°C and 160±10°C, respectively, to obtain modified polylactic acid pellets.

[0109] (3) The modified polylactic acid pellets were molded by a hot press at a temperature of 180° C., a pressure of 0.5 MPa, and a time of 1 min, and the cold press temperature was 10° C., the cold press pressure was 5 MPa, and the cold press time was 5 min to prepare a modified polylactic acid film with a thickness of 0.3 mm.

[0110] (4) One-dimensional plant fiber reinforcement: Continuous bamboo fibers were prepared according to the method of Example 1 in Chinese patent CN112878074A (a method for preparing continuous bamboo fibers), wherein the continuous bamboo fibers were 500 mm long and 2 mm in diameter; the continuous bamboo fibers were woven into bundles to obtain one-dimensional plant fiber reinforcements with a linear density of 35 tex and a diameter range of 3 to 10 mm.

[0111] (5) The modified bamboo fiber is tightly laid on the modified polylactic acid film of the pressing plate (the inner layer of the pressing plate is affixed with release paper to prevent the thermoplastic matrix from adhering to the pressing plate), the one-dimensional plant fiber reinforcement is arranged horizontally, and the unidirectional arrangement spacing is 5 mm, and the upper modified polylactic acid film is laid, and the upper pressing plate is closed and hot pressed. The hot pressing temperature is 170±10°C, the pressure is 1±0.5MPa, and the time is 1min, to obtain a bamboo fiber reinforced polylactic acid composite diaphragm with a thickness of 1.2mm.

[0112] The composite diaphragm prepared by the above method has a density of 0.7g / cm 3 , the creep modulus is 1200MPa, and the Young's modulus is 37.6GPa. The obtained composite diaphragm has the characteristics of high creep modulus, high stiffness, small elastic deformation and light weight.

[0113] Embodiment 3 (method one)

[0114] A bamboo powder reinforced PBAT\PP composite diaphragm, the composite diaphragm is composed of 30% by weight of polydopamine-modified bamboo powder and 70% by weight of a PBAT\PP resin system.

[0115] (1) Polydopamine was used to modify the interface of bamboo powder (particle size of 100-120 microns), bamboo powder was added to deionized water, dopamine solution was added, and the mixture was stirred at 20°C for 18 hours. After the reaction, the mixture was washed with anhydrous ethanol and distilled water in turn, and then dried to obtain polydopamine-modified bamboo powder; the dopamine solution was prepared by mixing tris(hydroxymethyl)aminomethane, dopamine hydrochloride and deionized water in a ratio of 0.12g:0.2g:100mL. The obtained bamboo powder was placed in an oven at 103°C for heat treatment for 1.5 hours to obtain modified bamboo powder (the bamboo powder was heat treated to absolute dryness, and after modification, the moisture content of the bamboo powder needed to be reduced before subsequent processing).

[0116] (2) According to the raw material ratio and steps in step (2) of Example 1, modified PP pellets are obtained.

[0117] (3) PBAT and an auxiliary agent (titanium phosphate is 5wt% of PBAT, camphor powder is 3wt% of PBAT, and maleic anhydride grafted polypropylene is 2.5wt% of PBAT) are placed in a high mixer and blended for 30 minutes, and then placed in a granulator for granulation. The resulting material is pelletized in a pelletizer. The temperatures of zones 1 to 4 of the granulator are 160±10°C, 180±10°C, 180±10°C and 170±10°C, respectively, to obtain modified PBAT pellets.

[0118] (4) 30 wt% of modified bamboo powder, 20 wt% of modified PBAT pellets and 50 wt% of modified PP pellets were placed in a high-speed mixer and blended for 15 min, and then placed in a twin-screw extruder for melt blending at temperatures of 160±10°C, 170±10°C, 190±10°C, 180±10°C and 150±10°C, respectively. The resulting material was pelletized in a pelletizer to obtain bamboo powder\PBAT\PP pellets.

[0119] (5) Two-dimensional plant fiber reinforcement: Bamboo fibers were prepared according to the method of Example 3 in Chinese patent CN110592685A (a method for preparing bamboo fibers), and the bamboo fibers were woven according to a two-way cross-weaving method with an angle of 30° between the bamboo fibers to obtain a mesh of two-dimensional reinforcement. The two-dimensional reinforcement was 2000 mm long, 50 mm wide and 2 mm thick.

[0120] (6) Two-dimensional embedded reinforcement was laid on the bamboo powder\PBAT\PP granules, which were placed in a hot press with a hot pressing temperature of 180±10°C and a pressure of 2.5±0.5MPa, and pressed for 20min (hot pressing for 10±5min, hot pressing temperature of 180°C, hot pressing pressure of 5MPa, cold pressing for 10±5min, cold pressing temperature of 5°C, cold pressing pressure of 5MPa) to obtain a bamboo powder reinforced PBAT\PP composite diaphragm with a thickness of 1.5mm.

[0121] The composite diaphragm prepared by the above method has a density of 0.7g / cm 3 , the creep modulus is 1100MPa, and the Young's modulus is 40.6GPa. The obtained composite diaphragm has the characteristics of high creep modulus, high stiffness, small elastic deformation and light weight.

[0122] Embodiment 4 (method 2)

[0123] A bamboo fiber reinforced PLA\PBAT composite diaphragm is composed of 30% KH550 modified bamboo fiber and 70% modified PLA granules\modified PBAT granules.

[0124] (1) According to the raw material ratio and steps in step (1) of Example 2, modified bamboo fiber was prepared.

[0125] (2) PLA was modified according to the raw material ratio and steps of Example 2 to obtain modified PLA pellets; PBAT was modified according to the raw material ratio and steps of Example 3 to obtain modified PBAT pellets.

[0126] (3) The modified PLA pellets and modified PBAT pellets (mass ratio of 70:30) were placed in a high mixer and blended for 30 minutes, then placed in a granulator for granulation, and the resulting material was granulated in a granulator. The temperatures of zones 1 to 4 of the granulator were 150±10°C, 170±10°C, 180±10°C and 160±10°C, respectively, to obtain modified PLA\PBAT pellets. The modified PLA\PBAT pellets were molded by a hot press at a temperature of 190°C, a pressure of 0.5MPa, and a time of 1min to prepare a modified PLA\PBAT film with a thickness of 0.3mm.

[0127] (4) The bamboo fiber is tightly spread on the modified PLA\PBAT film of the pressing plate (the inner layer of the pressing plate is affixed with release paper to prevent the thermoplastic matrix from adhering to the pressing plate), and the modified PLA\PBAT film on the upper layer is spread, and the upper pressing plate is closed and hot pressed at a temperature of 170±10°C, a pressure of 1±0.5MPa, and a time of 1min to obtain a bamboo fiber reinforced PLA\PBAT prepreg.

[0128] (5) Three layers of the bamboo fiber reinforced PLA\PBAT prepreg were laid out, and then placed in a hot press with a hot pressing temperature of 180±10°C and a pressure of 2.5±0.5MPa for 20 minutes (hot pressing for 10±5 minutes, hot pressing temperature of 180°C, hot pressing pressure of 5MPa, cold pressing for 10±5 minutes, cold pressing temperature of 5°C, cold pressing pressure of 5MPa) to obtain a bamboo fiber reinforced PLA\PBAT composite diaphragm with a thickness of 1.1 mm.

[0129] The composite diaphragm prepared by the above method has a density of 0.6 g / cm 3 , the creep modulus is 900MPa, and the Young's modulus is 36.6GPa. The obtained composite diaphragm has the characteristics of high creep modulus, high stiffness, small elastic deformation and light weight.

[0130] The present invention adopts different bamboo materials and thermoplastic resins, and adjusts the sound quality of the bamboo-plastic composite diaphragm by changing the compounding ratio of the bamboo material, filler and thermoplastic resin and matching appropriate process parameters, so as to achieve the diaphragm performance requirements of good rigidity (high specific bending rate), low density, appropriate internal damping and high elastic Young's modulus, and fast sound speed, thereby realizing its high added value application in the field of speaker diaphragms.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a bamboo-plastic composite diaphragm, wherein the raw materials for preparing the bamboo-plastic composite diaphragm include bamboo material and modified thermoplastic resin material, wherein the bamboo material includes one or more of bamboo powder, bamboo charcoal powder, bamboo fiber and bamboo fiber felt, and the modified thermoplastic resin material includes modified thermoplastic resin granules or modified thermoplastic resin film; The preparation method comprises the following steps: When the bamboo material is one or more of bamboo powder, bamboo charcoal powder and bamboo fiber, the preparation method of the bamboo-plastic composite diaphragm includes method one or method two: Method 1: Mix bamboo material and modified thermoplastic resin granules, perform melt blending and granulation in sequence to obtain granules; perform a first pressing on the granules to obtain a bamboo-plastic composite diaphragm; Method 2: alternately stacking bamboo material and modified thermoplastic resin film, and performing a second pressing to obtain a bamboo-plastic composite diaphragm; When the bamboo material is bamboo fiber felt, the preparation method of the bamboo-plastic composite diaphragm includes method three, method four or method five: Method 3: alternately stacking bamboo material and modified thermoplastic resin granules, and performing a third pressing to obtain a bamboo-plastic composite diaphragm; Method 4: alternately stacking the bamboo material and the modified thermoplastic resin film, and performing a fourth pressing to obtain a bamboo-plastic composite diaphragm; Method 5: directly perform the fifth pressing on several layers of bamboo fiber felt to obtain a bamboo-plastic composite diaphragm.

2. The preparation method according to claim 1, characterized in that: The bamboo material is modified bamboo material; the modification method of the modified bamboo material includes one or more of mechanical treatment, wet heat treatment, radiation treatment, chemical treatment and biological treatment; the mechanical treatment includes surface grinding and / or crushing, the wet heat treatment includes steaming, the radiation treatment includes one or more of flame treatment, corona treatment, microwave treatment and plasma treatment, the chemical treatment includes modifier treatment, and the biological treatment includes one or more of microbial degradation, enzymatic modification and biological coating; The modifying agent used in the modified bamboo material includes alkaline compounds, polydopamine, silane coupling agent KH550 or maleic anhydride grafted polyolefin solution.

3. The preparation method according to claim 1, characterized in that: The raw materials for preparing the modified thermoplastic resin material include thermoplastic resin, crosslinking agent and functional additives; The thermoplastic resin includes one or more of PP, PET, PE, PLA, PBAT, PBS, PA and viscose fiber; The crosslinking agent includes one or more of maleic anhydride grafted polyolefin, silane coupling agent and polyvinyl alcohol, wherein the maleic anhydride grafted polyolefin includes maleic anhydride grafted polypropylene and / or maleic anhydride grafted poly POE; the silane coupling agent includes KH550, titanate or monosilane; the polyvinyl alcohol is low-polymerization degree polyvinyl alcohol and / or medium-polymerization degree polyvinyl alcohol; the mass of the crosslinking agent is 1-20% of the mass of the thermoplastic resin; The functional additives include antioxidants and / or mildewproofing agents; the antioxidants include one or more of antioxidant KY-1010, vinyl POSS nano-modifiers and methacrylic POSS nano-enhancers; the mildewproofing agents include one or more of polystyrene caprylate, polypyridine, cinnamon oil, camphor powder, titanium phosphate and silane; the mass of the functional additives accounts for 1 to 15% of the mass of the thermoplastic resin.

4. The preparation method according to claim 1, characterized in that: The raw materials for preparing the bamboo-plastic composite diaphragm also include fillers, and the fillers include one or more of metal fillers and inorganic non-metal fillers.

5. The preparation method according to claim 4, characterized in that: The filler includes one or more of floating beads, hollow glass microbeads, inorganic mineral powder, inorganic mineral fibers and metal short fibers.

6. The preparation method according to claim 1, characterized in that: The raw materials for preparing the bamboo-plastic composite diaphragm also include embedded steel bars; the embedded steel bars are composed of fiber embedded steel bars.

7. The preparation method according to claim 6, characterized in that: The reinforcing bar implantation includes one-dimensional reinforcing bar implantation or two-dimensional reinforcing bar implantation.

8. The bamboo-plastic composite diaphragm prepared by the preparation method according to any one of claims 1 to 7.

9. The bamboo-plastic composite diaphragm according to claim 8, characterized in that: The density of the bamboo-plastic composite diaphragm is 0.5-1.5 g / cm 3 , creep modulus is 800~1200Mpa, and Young's modulus is 25~45GPa.

10. Use of the bamboo-plastic composite diaphragm according to any one of claims 8 to 9 in loudspeaker diaphragm materials.

Images