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BR-102024017396-A2 - PROCESS FOR OBTAINING A COMPOSITE BASED ON WOOD WASTE, GRAPHENE NANOPLATES AND POLYVINYL ACETATE, PRODUCT AND USE

BR102024017396A2BR 102024017396 A2BR102024017396 A2BR 102024017396A2BR-102024017396-A2

Abstract

This technology describes a process for obtaining a composite comprising 50% to 70% (w/w) wood waste, 30% to 50% (w/w) polyvinyl acetate, and 0.01% to 1% graphene nanoplatelets. It offers the following advantages: it utilizes waste from various types of wood generated by the furniture industry; it produces a solid product with mechanical and biological resistance; it uses only four inputs, including water which is evaporated during the process; and it uses pressures of 3 MPa to 6 MPa and temperatures of 70 to 100 °C. The process, as well as the resulting composite, can be used by the furniture industry for the construction of objects based on wood waste.

Inventors

  • ADRIANA LUISA DUARTE
  • ROSEMARY DO BOM CONSELHO SALES
  • GLAUCINEI RODRIGUES CORRÊA
  • SIDNEY NICODEMOS DA SILVA
  • ÍCARO RODRIGUES DANTAS

Assignees

  • UNIVERSIDADE DO ESTADO DE MINAS GERAIS
  • UNIVERSIDADE FEDERAL DE MINAS GERAIS - UFMG
  • CENTRO FEDERAL DE EDUCAÇÃO TECNOLÓGICA DE MINAS GERAIS - CEFET/MG

Dates

Publication Date
20260310
Application Date
20240823

Claims (7)

  1. 1. PROCESS FOR OBTAINING A COMPOSITE BASED ON WOOD WASTE, characterized by using graphene nanoplatelets and polyvinyl acetate, through the following steps: a) Sieving the wood waste to achieve a particle size of 0.1 mm to 3.0 mm; b) Preparing an aqueous solution of polyvinyl acetate at a concentration of 50% (w/w) to 10% (w/w) in deionized water; c) Preparing a suspension of graphene nanoplatelets at a ratio of 0.01% (w/v) to 1.0% (w/v) in deionized water in a 1:4 ratio proportional to the amount of polyvinyl acetate used and stirring for up to 40 minutes at a rotation speed of up to 10 to 15 rpm; d) Add the product obtained from step “b” to the product obtained in step “c”, stirring for up to 40 minutes at a speed of up to 10 rpm or until the suspension has a homogeneous appearance; e) Mix between 30% and 50% of the product obtained from step “d” with between 50% and 70% of wood residue, sieved according to step “a”, and stir for up to 10 minutes at a speed of 5 rpm; f) Heat a mold to a temperature between 70 °C and 100 °C, where the mold is made of male-female type stainless steel in the form of a counter-mold of the object to be obtained; g) Apply a layer of release agent to the stainless steel surface of the mold; h) Deposit the material obtained in step “e” into the stainless steel mold; i) Press the male-female molds together for up to 1 minute with a pressure between 3 MPa and 6 MPa, repeating this step up to 10 times or until no more smoke comes out of the object being molded; j) Press the male-female molds together for up to 10 minutes with a pressure between 3 MPa and 6 MPa; k) Demold the object generated after pressing and place it on a flat surface with a temperature between 5 °C and 40 °C, where each square centimeter of the generated object is under a mass between 10g and 20g for a time between 2 hours and 24 hours; l) Cut off the excess edges of the object obtained from step “k”.
  2. 2. PROCESS, according to claim 1, characterized in that, in step “a”, the wood residue is wood powder or agglomerated wood powder such as MDF, MDP and plywood, where the wood residue must have a particle size of 0.106 mm to 0.120 mm for MDF, MDP and plywood and 2.36 mm to 2.95 mm for wood powder.
  3. 3. PROCESS, according to claim 1, characterized in that, in step “c”, the graphene nanoplatelets are multilayered with a specific surface area of 60 m2/g to 70 m2/g, purity between 95% and 100%, particles with an aspect ratio of 5 μm to 15 μm and a number of layers between 10 and 70.
  4. 4. PROCESS, according to claim 1, characterized in that, in steps “c” to “e”, the agitation is carried out in a mechanical stirrer with a two-bladed propeller.
  5. 5. PROCESS, according to claim 1, characterized in that, in step “m”, the cutting of excess edges is carried out by means of a circular saw.
  6. 6. COMPOSITE PRODUCT BASED ON WOOD WASTE, obtained according to the process defined in any one of claims 1 to 5, characterized by comprising 50% to 70% by mass of wood waste, 30% to 50% polyvinyl acetate, between 0.01% and 1% graphene nanoplatelets and having a thickness between 1 mm and 50 mm.
  7. 7. USE OF THE COMPOSITE defined in claim 6, characterized by being in the production of flat plates and plates with curvatures.

Description

[001] The present technology relates to a process for obtaining a composite comprising 50% to 70% (w/w) wood waste, 30% to 50% (w/w) polyvinyl acetate and 0.01% to 1% graphene nanoplatelets which presents the following advantages: it utilizes waste from various types of wood generated by the furniture industry, it generates a solid product with mechanical and biological resistance, it uses only four inputs, including water which is evaporated during the process, and it uses pressures of 3 MPa to 6 MPa and temperatures of 70 to 100 °C. The process, as well as the composite obtained, can be used by the furniture industry for the construction of objects based on wood waste. [002] Climate change calls upon humanity to responsibly exploit natural resources. Therefore, it is necessary to reduce deforestation for timber or to better reuse it in products with a long lifespan and properties that are beneficial to society. Materials based on wood waste are already used for this purpose, such as Medium-density Fiberboard (MDF), Medium-density Particleboard (MDP), or wood fiberboard. The production process for these materials may require the use of various synthetic compounds such as paraffin, epoxy resin, thermosetting polymers, among others, and may involve several steps, such as compression, heating, fiber grinding, cooling, fiber ordering, cutting, sanding, coating, and others. [003] One proposal to increase the strength of objects made from wood waste is the addition of nanocomposites. Carbon nanocomposites exhibit high mechanical strength, which can be transferred to other materials when incorporated correctly. Among carbon nanomaterials, there is graphene which, being hydrophobic, presents, as one of the greatest challenges for its use, the formulation of stable dispersions in water, which depends on the addition of suitable surfactants. Minimizing graphene agglomeration at the end of the process after water evaporation is fundamental to maintaining the material's properties. Another way to minimize graphene agglomeration is by adding polymers such as polyvinyl acetate. The polymer can partially bond to graphene sheets, preventing their reaggregation (KHAN, Umar et al. Improved adhesive strength and toughness of polyvinyl acetate glue on addition of small quantities of graphene. ACS Applied Materials and Interfaces, v. 5, n. 4, p. 1423-1428, 27 Feb. 2013.). [004] In this sense, in the state of the art there are some documents that reveal devices and equipment that aim to obtain a composite based on wood waste comprising nanocomposites and polymers. [005] The paper entitled “Effect of Nanographene on Physical, Mechanical, and Thermal Properties and Morphology of Nanocomposite Made of Recycled High-Density Polyethylene and Wood Flour. BioResources”, published in January 2017 (https://doi.org/10.15376/biores.12.1.1382-1394), investigates the influence of nanographene in wood composites containing 30% by weight of wood sawdust and 70% by weight of high-density polyethylene. The composite was reinforced with graphene nanoparticles at concentrations, by mass, of 0.5, 1.5, and 2.5%. The results showed that the 0.5% by mass concentration of graphene nanoparticles increased flexural strength, notch strength, low porosity, and impact resistance. However, the addition of 2.5% reduced these properties and increased thermal stability. In this document, the composite comprises maleic anhydride grafted with polyethylene. The disclosed process requires a temperature of 200 °C and a pressure of 25 MPa. [006] The document entitled “Antibacterial Activity of Polymer Nanocomposites Incorporating Graphene and Its Derivatives: A State of the Art”, published on 06/26/2021 (Link: https://doi.org/10.3390/polym13132105), describes the antimicrobial properties of polymer nanocomposites reinforced with graphene and its derivatives, such as graphene oxide and reduced graphene oxide. In this document, the nanocomposites were classified as acrylic, methacrylic, biodegradable synthetic, and natural polymer matrices. The article presents the use of polyvinyl alcohol but not polyvinyl acetate. Furthermore, it does not present a process using wood powder to produce boards that can be used by the furniture industry. [007] Patent document BR102019004110A2, with a priority date of 27/02/2019, entitled “Process for obtaining a granulated wood product with a matte black surface finish”, describes a process for obtaining a granulated wood product with an aesthetic matte black surface finish and the respective product. The process includes a step in which the polyvinyl acetate polymer binder reacts with carbon steel, which generates changes in the appearance of the final product, such as darkening and the appearance of a matte finish. The change in appearance eliminates a finishing or coating step with paint necessary for finishing other granulated wood materials. This document does not use nanomaterials. [008] Patent document CN101724190A, with a prior