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CN-122011682-A - Thermosetting composite material with high impact strength and preparation method thereof

CN122011682ACN 122011682 ACN122011682 ACN 122011682ACN-122011682-A

Abstract

The invention discloses a thermosetting composite material with high impact strength and a preparation method thereof, which belong to the technical field of thermosetting composite materials, wherein, first, enzymolysis lignin is dialyzed and self-assembled to obtain rigid nano lignin microspheres, then, silane coupling agent is utilized to introduce active carbon-carbon double bonds on the nano lignin microspheres, and in-situ copolymerization is carried out on the nano lignin microspheres to form flexible polyacrylate buffer layers, thus, modified nano lignin microspheres are obtained, and are uniformly dispersed in an epoxy resin system, and the thermosetting composite material is prepared through vacuum defoamation and heating solidification, and the composite material can still maintain good impact strength and intrinsic structural rigidity under the high temperature state through the energy absorption buffer effect of the flexible layer and the covalent chemical anchoring effect between the modified microspheres and a resin matrix, thus, and is suitable for the scenes with severe requirements on anti-impact heat-resistant protection such as battery packs of new energy automobiles.

Inventors

  • WANG DECHENG
  • CHEN AIMING
  • QI CHAOMING

Assignees

  • 宁国中奕橡塑有限公司

Dates

Publication Date
20260512
Application Date
20260331

Claims (8)

  1. 1. The thermosetting composite material with high impact strength is characterized by comprising the following raw materials in parts by mass: 100-300 parts of epoxy resin, 90-270 parts of methyl tetrahydrophthalic anhydride, 5-15 parts of modified nano lignin microspheres and 2-6 parts of N, N-dimethylbenzylamine; the modified nano lignin microsphere is prepared by the following steps: Placing the double bond-containing nano lignin microsphere, butyl acrylate, acrylic acid, azodiisobutyronitrile and N, N-dimethylformamide in a reaction kettle under the protection of nitrogen atmosphere, reacting for 1-2h at 60-80 ℃, adding the reaction solution into a mixed solution prepared by methanol and deionized water according to the volume ratio of 1:1 for precipitation, filtering, and vacuum drying to constant weight to obtain the modified nano lignin microsphere.
  2. 2. The thermoset composite material of claim 1, wherein the double bond containing nanolignin microspheres, butyl acrylate, acrylic acid, azobisisobutyronitrile, and N, N-dimethylformamide are used in a ratio of 20-40g to 2-4g to 0.2-0.4g to 200-400mL.
  3. 3. The thermoset composite material of claim 2, wherein the double bond-containing nanolignin microspheres are prepared by: Placing gamma-methacryloxypropyl trimethoxy silane and absolute ethyl alcohol into a reaction kettle, adding an acetic acid aqueous solution with the concentration of 0.5mol/L to adjust the pH value of the reaction solution to 4-6, stirring for 1-2 hours at 25-35 ℃, adding rigid nano lignin microspheres, reacting for 1-2 hours at 50-60 ℃, filtering, washing, and vacuum drying to constant weight to obtain the double bond-containing nano lignin microspheres.
  4. 4. A thermoset composite material having high impact strength according to claim 3, wherein the gamma-methacryloxypropyl trimethoxysilane, absolute ethyl alcohol, and rigid nanolignin microspheres are used in a ratio of 4-6g:200-400ml:30-50g.
  5. 5. A thermoset composite material having high impact strength according to claim 4, the preparation method is characterized in that the rigid nano lignin microsphere is prepared by the following steps: placing the enzymatic hydrolysis lignin, gamma-valerolactone and ultrapure water into a reaction kettle, stirring for 20-40min at 25-35 ℃ to obtain lignin solution, adding the lignin solution into 4-6 times of the volume of the ultrapure water, continuously stirring for 20-40min at the same temperature, transferring the solution in the bag into the reaction kettle after dialysis, reacting for 12-14h at 150-170 ℃, centrifuging, and freeze-drying to constant weight to obtain the rigid nano lignin microsphere.
  6. 6. The thermoset composite of claim 5, wherein the enzymatic lignin, gamma valerolactone and ultrapure water are present in a ratio of 40-60:200-300ml:20-40mL.
  7. 7. The method of preparing a thermoset composite material having high impact strength according to claim 1, comprising the steps of: Placing epoxy resin and methyl tetrahydrophthalic anhydride in a reaction kettle, stirring for 1-2h at 50-70 ℃, adding modified nano lignin microspheres, performing ultrasonic dispersion for 1-2h, cooling to 25-35 ℃, adding N, N-dimethylbenzylamine, stirring for 20-40min, vacuum defoaming for 20-40min at 25-35 ℃, adding the defoamed mixed solution into a mold, moving into a blast drying box, pre-curing for 1-2h, curing for 2-4h, cooling and demolding to obtain the thermosetting composite material with high impact strength.
  8. 8. The method of producing a thermoset composite material having high impact strength according to claim 7, wherein the pre-cure temperature is 80-100 ℃ and the cure temperature is 130-150 ℃.

Description

Thermosetting composite material with high impact strength and preparation method thereof Technical Field The invention belongs to the technical field of thermosetting composite materials, and particularly relates to a thermosetting composite material with high impact strength and a preparation method thereof. Background The battery pack bottom shell of the new energy automobile is a core structural component for bearing the physical protection and bearing functions of a battery pack in the automobile, and in a complex actual driving working condition, the bottom shell is faced with transient high-energy damage situations such as high-frequency scattering of broken stones on a road surface, hollow collision of a roadblock and the like at any time, so that the protective material is required to have extremely high impact resistance, catastrophic fragmentation of the material is prevented, the thermosetting composite material represented by epoxy resin is used, and the high-strength and lightweight advantages brought by a compact three-dimensional crosslinked network after the material is cured and molded are utilized to gradually replace the traditional metal, so that the battery pack bottom shell becomes an ideal matrix material for manufacturing the chassis protective component. However, epoxy resin has serious intrinsic brittleness due to extremely high crosslinking density, so that the epoxy resin has extremely high impact strength required by a bottom shell, a great amount of toughening modifier such as elastomer or flexible polymer is generally required to be introduced into the epoxy resin in industry, but the traditional toughening mode usually has the cost of sacrificing the original compact crosslinking network of a matrix, so that the heat-resistant rigidity of the whole material is weakened, in an actual service scene, the bottom shell is required to be in a high-temperature environment for releasing a great amount of heat by high-rate charge and discharge of a battery for a long time, under the high-temperature working condition, the free volume inside the polymer system is rapidly expanded due to the fact that the traditional toughening system damages the high-temperature resistant skeleton of the epoxy resin, and the molecular chain segment is severely desorbed and slipped and softened due to heating, so that the composite material cannot effectively transfer stress when being subjected to external high-energy impact, and the bottom shell is easy to crack and lose efficacy when being bumped. Therefore, how to construct a thermosetting composite material capable of continuously maintaining high impact strength supported by a rigid framework in a high-temperature environment, so as to effectively resist high-energy physical collision and ensure the integrity of the whole structure, and the thermosetting composite material has become a key technical problem to be solved in the field of the composite materials of the current new energy automobiles. Disclosure of Invention The invention aims to provide a thermosetting composite material with high impact strength and a preparation method thereof, and by constructing a high-efficiency chemical anchoring network between modified nano lignin microspheres and an epoxy resin matrix, a composite system can still keep stable rigid framework support and high-efficiency impact energy dissipation in a high-temperature environment, so that the actual requirements of core protection components such as a battery pack bottom shell of a new energy automobile on high impact strength and structural safety of the material in a complex running environment are met. The aim of the invention can be achieved by the following technical scheme: The invention provides a thermosetting composite material with high impact strength, which comprises the following raw materials in parts by mass: 100-300 parts of epoxy resin, 90-270 parts of methyl tetrahydrophthalic anhydride, 5-15 parts of modified nano lignin microspheres and 2-6 parts of N, N-dimethylbenzylamine. The invention also provides a preparation method of the thermosetting composite material with high impact strength, which comprises the following steps: placing epoxy resin and methyl tetrahydrophthalic anhydride (curing agent) in a reaction kettle, stirring for 1-2h at 50-70 ℃, adding modified nano lignin microspheres, performing ultrasonic dispersion for 1-2h, cooling to 25-35 ℃, adding N, N-dimethylbenzylamine (accelerator), stirring for 20-40min, vacuum defoaming for 20-40min at 25-35 ℃, adding the defoamed mixed solution into a die, transferring into a blast drying box, pre-curing for 1-2h, curing for 2-4h, cooling and demolding to obtain the thermosetting composite material with high impact strength. Further, the pre-curing temperature is 80-100 ℃ and the curing temperature is 130-150 DEG C Further, the preparation process of the modified nano lignin microsphere comprises the following steps: Placing the double b