A high-aspect-ratio bamboo-plastic composite filler for lightening automobiles and household appliances and a preparation method thereof

Abstract

The application provides a high-aspect-ratio bamboo-plastic composite filler for lightening automobiles and household appliances and a preparation method thereof, and belongs to the technical field of polymer composite materials and biomass resource utilization technology.The pretreated bamboo waste is sheared and ground so that the bamboo waste is dissociated into microfiber bundles, and after sieving, superfine bamboo fiber powder is obtained; after the superfine bamboo fiber powder is heated, the material is kneaded and coated by spraying into a modifier solution, and modified bamboo powder is obtained; the modified bamboo powder is vacuum dried and cooled to obtain the high-aspect-ratio bamboo-plastic composite filler.The high-aspect-ratio bamboo-plastic composite filler prepared by the application greatly improves the mechanical strength of the material, the density is reduced by 10% compared with a talc powder system, and the processing fluidity is excellent.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials and biomass resource utilization technology, and in particular to a high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances and its preparation method. Background Technology

[0002] Currently, the automotive and home appliance industries are extremely focused on "bio-based carbon reduction" and "lightweighting." Traditional inorganic powders (such as talc and glass fiber) are often used to modify PP / ABS plastics to increase strength, but they have disadvantages such as high specific gravity (increasing product weight), high carbon footprint, and wear and tear on processing equipment.

[0003] Bamboo fiber possesses natural advantages such as light weight, high specific strength, and renewability, making it an excellent alternative to lightweight fillers. However, directly applying bamboo powder to plastic modification faces two major technical bottlenecks: 1. Poor compatibility: Bamboo powder is rich in hydrophilic hydroxyl groups, which have extremely weak interfacial bonding with hydrophobic thermoplastics (PP, ABS, etc.), resulting in large interfacial defects in the composite material and a decrease in mechanical properties.

[0004] 2. Difficulty in maintaining powder morphology: Conventional dry ball milling or pulverization can easily break bamboo fibers into equiaxed powders, resulting in the loss of the fiber's reinforcing effect (a decrease in aspect ratio), and thus failing to provide a skeletal support function similar to that of glass fiber.

[0005] Therefore, there is an urgent need for a process that can both ultrafinely pulverize bamboo waste to plastic processing grade particle size (200-800 mesh), maintain a high aspect ratio, and achieve thorough hydrophobic modification. Summary of the Invention

[0006] The purpose of this invention is to provide a high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances and its preparation method, so as to solve the technical problems of poor compatibility, low aspect ratio and significant weight gain of existing bamboo powder fillers.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing high aspect ratio bamboo-plastic composite fillers for lightweighting automobiles and home appliances, comprising the following steps: 1) Cut and grind the pretreated bamboo waste to dissociate it into microfiber bundles, and then sieve it to obtain ultrafine bamboo fiber powder. 2) After heating the ultrafine bamboo fiber powder, the modifier solution is sprayed into it through atomization to knead and coat the material, thereby obtaining modified bamboo powder. 3) The modified bamboo powder was vacuum dried and cooled to obtain a high aspect ratio bamboo-plastic composite filler; The modifier solution contains a compatibilizer, a coupling agent, and a dispersion medium.

[0008] Furthermore, the ultrafine bamboo fiber powder has a particle size of 200-800 mesh and a fiber aspect ratio of 5-20:1.

[0009] Furthermore, in step 2), the heating temperature is 90~120℃, and the kneading and coating time is 10~20min.

[0010] Furthermore, the compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer.

[0011] Furthermore, the coupling agent is silane coupling agent KH-550, silane coupling agent KH-560 or titanate coupling agent NDZ-201; The dispersion medium is ethanol.

[0012] Furthermore, the mass ratio of the compatibilizer, coupling agent, and dispersion medium is 2~4:1:3~6; the amount of the modifier solution added is 3~8% of the mass of the ultrafine bamboo fiber powder.

[0013] Furthermore, the vacuum drying process is carried out until the moisture content of the modified bamboo powder is <1%.

[0014] The present invention also provides a high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances. The high aspect ratio bamboo-plastic composite filler has a particle size of 400~800 mesh, a powder contact angle of >110°, and is highly hydrophobic.

[0015] The beneficial effects of this invention are: 1. Lightweight and carbon reduction: Compared to talc (specific gravity 2.7), bamboo fiber has a specific gravity of only about 1.4. With the same amount of addition, it can reduce weight by 15%-20%, and the bio-based has a high carbon content, which meets the ESG requirements of car manufacturers.

[0016] 2. High reinforcement performance: The high aspect ratio (5:1-20:1) microfiber structure combined with excellent interfacial compatibility makes its reinforcement effect in PP / ABS better than that of chopped glass fiber, and does not wear the screw.

[0017] 3. High added value and waste utilization: Low-value bamboo product waste is transformed into special plastic modification powder with a mesh size of 400 or higher, which greatly enhances the economic value of bamboo waste. Detailed Implementation

[0018] This invention provides a method for preparing high aspect ratio bamboo-plastic composite fillers for lightweighting automobiles and home appliances, comprising the following steps: 1) Cut and grind the pretreated bamboo waste to dissociate it into microfiber bundles, and then sieve it to obtain ultrafine bamboo fiber powder. 2) After heating the ultrafine bamboo fiber powder, the modifier solution is sprayed into it through atomization to knead and coat the material, thereby obtaining modified bamboo powder. 3) The modified bamboo powder was vacuum dried and cooled to obtain a high aspect ratio bamboo-plastic composite filler; The modifier solution contains a compatibilizer, a coupling agent, and a dispersion medium.

[0019] In this invention, waste materials from bamboo product factories (bamboo shavings, bamboo hairs) are used as raw materials, and the core processes include "flexible shearing ultrafine grinding" and "in-situ composite modification": Flexible shearing ultrafine grinding: Abandoning traditional strong impact crushing, this method employs disc grinding or vibration shearing principles. Under shearing force, bamboo is delaminated and disintegrated into microfiber bundles along the fiber axis, rather than breaking laterally. This ensures that while achieving an ultrafine particle size of 200-800 mesh, the fiber aspect ratio is maintained above 5:1, providing excellent tensile and flexural strength for plastics.

[0020] In-situ composite modification: In a high-speed modifying machine, a coupling agent (such as silane) first reacts chemically with the hydroxyl groups on the surface of bamboo powder (dehydration condensation), and then a hydrophobic polymer "shell" is formed on the surface of the bamboo powder through physical entanglement and melt coating by a compatibilizer (such as MAPE). This double-layer coating structure increases the contact angle of bamboo powder to over 110°, perfectly solving the compatibility problem with the plastic matrix.

[0021] In this invention, the pretreatment involves sorting and removing impurities from the collected bamboo product processing waste, adjusting the moisture content to 10-15%, and obtaining bamboo waste; the bamboo product processing waste is bamboo shavings or bamboo hair.

[0022] In this invention, the particle size of the ultrafine bamboo fiber powder is 200-800 mesh, preferably 300-700 mesh, and more preferably 400-600 mesh; the fiber aspect ratio is 5-20:1, preferably 6-15:1, and more preferably 10-15:1.

[0023] In this invention, in step 2), the heating temperature is 90~120℃, preferably 95~115℃, and more preferably 100~110℃; the kneading and coating time is 10~20min, preferably 12~18min, and more preferably 15min.

[0024] In this invention, the compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer, preferably maleic anhydride-grafted polyethylene.

[0025] In this invention, the coupling agent is silane coupling agent KH-550, silane coupling agent KH-560 or titanate coupling agent NDZ-201, preferably silane coupling agent KH-550. The dispersion medium is preferably ethanol.

[0026] In this invention, the mass ratio of the compatibilizer, coupling agent and dispersion medium is 2~4:1:3~6, preferably 3:1:4~5; the amount of the modifier solution added is 3~8% of the mass of the ultrafine bamboo fiber powder, preferably 4~7%, and more preferably 5~6%.

[0027] In this invention, the vacuum drying process is carried out until the moisture content of the modified bamboo powder is <1%.

[0028] The present invention also provides a high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances. The high aspect ratio bamboo-plastic composite filler has a particle size of 400~800 mesh, preferably 500~600 mesh; the powder contact angle is >110°, and it is highly hydrophobic.

[0029] The composite filler of the present invention is used in the manufacture of modified plastics for automotive interior parts, high-end home appliance shells and environmentally friendly WPC high-strength panels, as a lightweight bio-based alternative filler to talc or glass fiber.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] Preparation of ultrafine bamboo fiber powder for modified PP in automotive interior parts: 1. Pretreatment: Take bamboo waste from bamboo product factories, sort out impurities, and adjust the moisture content to 12%.

[0033] 2. Flexible shearing and grinding: Bamboo shavings are fed into a disc mill, the gap between the grinding discs and the shearing rate are controlled, the machine temperature is controlled to be <60℃, and after grinding, the shavings are passed through a 400-mesh sieve. The average length-to-diameter ratio is measured to be 8:1.

[0034] 3. Surface hydrophobic modification: 400-mesh bamboo powder is put into a high-speed mixer and heated to 110℃. MAPE (4 parts) and silane coupling agent KH-560 (1 part) are dissolved in 5 parts ethanol to prepare a modifier solution. The modifier solution is evenly sprayed into the bamboo powder through an atomizing nozzle. The amount of modifier solution added is 5% of the mass of the ultrafine bamboo fiber powder. High-speed kneading is carried out for 15 minutes to allow the solvent to evaporate and MAPE to melt and coat the powder.

[0035] 4. Drying and cooling: Vacuum drying to a moisture content of 0.5%, followed by cooling to obtain a hydrophobic bamboo-plastic composite filler (contact angle 115°).

[0036] Example 2

[0037] Preparation of ultrafine bamboo fiber powder for ABS modification of high-end home appliance shells: The pretreatment is the same as in Example 1.

[0038] 2. Flexible shear grinding: Vibration shear milling was used to further refine the powder to 800 mesh, and the average length-to-diameter ratio was measured to be 5:1.

[0039] 3. Surface hydrophobic modification: 400-mesh bamboo powder is put into a high-speed mixer and heated to 100℃. SEBS-g-MAH (5 parts), titanate coupling agent NDZ-201 (1.5 parts), and anhydrous ethanol (5 parts) are selected for composite modification. The above mixture is atomized and sprayed into the bamboo powder. The amount of modifier solution added is 6% of the mass of ultrafine bamboo fiber powder. High-speed kneading is carried out for 20 minutes.

[0040] 4. Vacuum dry to a moisture content of 0.6%, and after drying and cooling, obtain 800-mesh ultrafine modified bamboo powder with a contact angle of 112°.

[0041] Comparative example: Unmodified commercially available bamboo powder

[0042] Commercially available unmodified 200-mesh bamboo powder was used, without any surface treatment.

[0043] Application performance testing: Bamboo powder from Examples 1, 2, and the comparative example was granulated by twin-screw extrusion with PP resin (Example 1, Comparative Example) or ABS resin (Example 2) at a mass fraction of 30%, and then injection molded into standard test strips. These strips were then compared with pure PP and PP with 30% added talc.

[0044] Table 1 Performance Tests

[0045] As shown in Table 1, the high aspect ratio bamboo-plastic composite filler prepared by this invention significantly improves the mechanical strength of the material (tensile strength increased by 40% in Example 1), while reducing the density by 10% compared to the talc system, and exhibits excellent processing fluidity. The comparative example, due to lack of modification, suffers a severe decline in the mechanical properties of the composite material, rendering it completely unusable. The product of this invention fully meets the material requirements for lightweight automotive and high-end home appliance housings.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances, characterized in that, Includes the following steps: 1) Cut and grind the pretreated bamboo waste to dissociate it into microfiber bundles, and then sieve it to obtain ultrafine bamboo fiber powder. 2) After heating the ultrafine bamboo fiber powder, the modifier solution is sprayed into it through atomization to knead and coat the material, thereby obtaining modified bamboo powder. 3) The modified bamboo powder was vacuum dried and cooled to obtain a high aspect ratio bamboo-plastic composite filler; The modifier solution contains a compatibilizer, a coupling agent, and a dispersion medium.

2. The preparation method according to claim 1, characterized in that, The ultrafine bamboo fiber powder has a particle size of 200-800 mesh and a fiber aspect ratio of 5-20:

1.

3. The preparation method according to claim 2, characterized in that, In step 2), the heating temperature is 90~120℃, and the kneading and coating time is 10~20min.

4. The preparation method according to claim 1 or 3, characterized in that, The compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer.

5. The preparation method according to claim 4, characterized in that, The coupling agent is silane coupling agent KH-550, silane coupling agent KH-560 or titanate coupling agent NDZ-201. The dispersion medium is ethanol.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the compatibilizer, coupling agent, and dispersion medium is 2~4:1:3~6; the amount of the modifier solution added is 3~8% of the mass of the ultrafine bamboo fiber powder.

7. The preparation method according to claim 1 or 6, characterized in that, The modified bamboo powder is vacuum dried until its moisture content is <1%.

8. The high aspect ratio bamboo-plastic composite filler for lightweighting automobiles and home appliances prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The high aspect ratio bamboo-plastic composite filler has a particle size of 400~800 mesh, a powder contact angle of >110°, and is highly hydrophobic.

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