WO2022126218A1 - Nanocellulose- and lignosulphonate-based adhesive coacervate and method for producing same - Google Patents

Nanocellulose- and lignosulphonate-based adhesive coacervate and method for producing same Download PDF

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WO2022126218A1
WO2022126218A1 PCT/BR2021/050559 BR2021050559W WO2022126218A1 WO 2022126218 A1 WO2022126218 A1 WO 2022126218A1 BR 2021050559 W BR2021050559 W BR 2021050559W WO 2022126218 A1 WO2022126218 A1 WO 2022126218A1
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adhesive
nanocellulose
coacervate
cellulose
lignosulfonate
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PCT/BR2021/050559
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French (fr)
Portuguese (pt)
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Diego MAGALHÃES DO NASCIMENTO
Gabriele POLEZI
Juliana DA SILVA BERNARDES
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Cnpem - Centro Nacional De Pesquisa Em Energia E Materiais
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Publication of WO2022126218A1 publication Critical patent/WO2022126218A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H8/00—Macromolecular compounds derived from lignocellulosic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/02—Cellulose; Modified cellulose

Definitions

  • compositions comprising modified cellulose and sulfonated lignin.
  • Cellulose is the most abundant natural polymer on the planet, and can be produced by microorganisms in the form of microbial cellulose, but mainly by plants, where it is present as a structural component of the cell wall.
  • cellulose is today a promising alternative for use in various materials.
  • cellulose is a linear-chain polysaccharide, with the general formula (C 6 Hio0 5 )n, consisting of hundreds or thousands of D-glucose units linked together by 3-1 type bonds, 4-glycosidics.
  • the amount of glucose units in the polymer chain also known as the degree of polymerization (DP), depends on the species and growth conditions of the plant. For example, cellulose extracted from wood pulp, such as eucalyptus and pine, has about 300 to 1700 units of the saccharide in its chain, while celluloses from fibrous species, such as cotton, have 800 to 10000 units of glucose.
  • the length of the chain and the degree of polymerization reflect on several properties of cellulose.
  • One of the characteristics of cellulose is its low solubility in water and in most organic solvents, due to the high cohesion energy that involves intra and intermolecular hydrogen bonds and van der Waals interactions.
  • Cellulose can be found with different mechanical properties, due to the variety of shapes, sizes and degrees of crystallinity of its particles.
  • cellulose is mainly obtained from wood pulp and cotton. It is mainly used to produce paper, cotton and linen for clothing, nitrocellulose for films and explosives, cellulose acetate for films and carboxymethylcellulose for formulated products.
  • Nanocellulose is the term used to describe cellulosic materials with dimensions in the nanometer range (10 -9 m). Nanocelluloses can be classified into three main categories: i) nanofibrillated cellulose (CNF), ii) nanocrystalline cellulose (CNC) and iii) bacterial nanocellulose (BNC).
  • CNF nanofibrillated cellulose
  • CNC nanocrystalline cellulose
  • BNC bacterial nanocellulose
  • the main route of obtaining CNC is via acid hydrolysis of cellulosic pulp. This method promotes the removal of amorphous regions of the material, generating well-defined crystals of stable nanocellulose in colloidal suspension.
  • the CNF is obtained by the mechanical treatment of the cellulose pulp. Mechanical shear is responsible for breaking the rigid structure of cellulose fibers, strongly cohesive by hydrogen bonds and van der Walls interactions, thus decreasing the size of the fibers.
  • Nanocellulose has attracted great attention from researchers due to its interesting properties, such as excellent mechanical characteristics, high surface area, richness of hydroxyl groups for functionalization and ecological characteristics important to the environment.
  • Lignin is the second most abundant natural macromolecule in nature. Like cellulose, lignin is present in the cell wall of plant tissues, comprising 10% to 25% of lignocellulosic biomass. In the plant cell wall, lignin fills the spaces between the cellulose and hemicellulose components, keeping the cellulosic fibers together and, consequently, is responsible for conferring structural properties such as rigidity, resistance and impermeability to vascular plants, especially woody species.
  • Lignin is a highly cross-linked three-dimensional macromolecule consisting of three types of substituted phenols (coniferyl, synapyl and p-coumaryl alcohols) organized in cross-linked covalent bonds. Their chains can have different structures and degrees of polymerization, depending on the species of plant from which they are extracted.
  • a lignin extraction route comprises the treatment of wood by oxidation processes, such as the Kraft process, and subsequent extraction and purification of lignin from the generated black liquor.
  • oxidation processes such as the Kraft process
  • LignoBoostTM with features disclosed in W02006031175, W02006038863, WQ2009104995, among other documents
  • LignoForceTM with features disclosed in WO2011150508, among other documents
  • SLRP sequential process of recovery and purification of liquid lignin
  • the pH of the black liquor is reduced to approximately 9 to 10, using CO 2 or mineral acid, which leads to the precipitation of lignin.
  • the lignin is then separated by filtration or pressing, and the impurities are removed by washing with an aqueous acid solution, leading to the formation of lignin with high purity.
  • the lignin of the black liquor precipitates as a liquid phase, separating only by gravity and not by filtration, as in the other two processes; this confers greater purity of the lignin obtained with a smaller number of treatment steps.
  • coacervate is used in colloid chemistry to denote association of oppositely charged molecules (polyelectrolytes) that lead to the formation of a water-poor phase. When separated, these polycations and polyanions show good solubility in aqueous media. However, when these species are mixed, electrostatic interactions occur that lead to the formation of species. neutral, less soluble in the aqueous medium, then phase separation occurs.
  • the colloid-rich phase is known as the coacervated phase, while the phase containing very small amounts of colloid is known as the equilibrium phase.
  • Patent document US20160168272A1 discloses a process for producing cellulose fibers, nanofibers and lignin-containing cellulose nanocrystals.
  • Patent document WO2019213730A1 discloses an adhesive based on natural rubber latex at pH equal to or greater than 9, lignin precipitated at acidic pH in its non-functionalized form and nanocellulose in its non-functionalized form, as well as the process of production of the same.
  • Jayaramudu et al (2019, Composites Part B, v. 156, p. 43-50) disclose an adhesive made from a mixture of poly(ethylene oxide) and lignin (PEO-L).
  • the increase in the lignin content in the mixture showed a proportional increase in the adhesive properties, with the shear stress of the pure PEO adhesive being 442 kPa, while the shearing stress of the PEO-L adhesive with 30% lignin was 835 kPa, in single lap joint tests performed on nanofibrillated cellulose (CNF) films.
  • CNF nanofibrillated cellulose
  • Patent document US6790271 B2 discloses a waterproof adhesive formulation comprising isolated soy protein, a plasticizer, a vegetable oil and lignin or a lignin derivative.
  • Soy protein is present in a proportion above 50%, giving the adhesive water resistance.
  • the plasticizer described is a polyol, preferably glycerol, in a concentration above 20%.
  • Vegetable oil is modified to have at least one reactive site with the protein and the polyol.
  • the function of lignin or a lignin derivative is to increase the stiffness of the adhesive.
  • the lignin derivative that presented the most advantageous results in the manufacture of the adhesive of the description was lignosulfonate.
  • a disadvantage associated with this prior art is the need to cure the adhesive at high temperatures (about 165°C).
  • an adhesive containing nanofibers and/or nanocrystals with surfaces functionalized with anionic or cationic groups which does not require the application of high temperatures in a curing or self-adhesion step.
  • a waterproof adhesive capable of joining a plurality of substrates and presenting easy application.
  • This plurality of substrates comprises glass, polymers or cellulosic substrates of different compositions, including fabrics, woods, papers and cardboard, all of which may be in wet or humid conditions. It is also an object of the present description that such an adhesive is capable of joining joints of similar or dissimilar substrates.
  • an adhesive coacervate comprising from 0.01 to 10% (m/m) of anionic or cationic nanocellulose and from 0.01 to 40% (m/m) sulfonated lignin, which settles on dry substrates or wet, without the need to apply high temperatures and/or pressures for fixing it.
  • the purposes of the present description are also achieved by a process of producing said adhesive coacervate.
  • This process comprises mixing a sulfonated lignin solution in an aqueous dispersion of anionic or cationic nanocellulose, homogenizing the mixture, centrifuging and separating the solid phase thereof, where the solid phase is the adhesive coacervate.
  • Figure 1 is a schematic illustration of the electrostatic complexation process of components of the adhesive of the present description.
  • Figures 2a, 2b and 2c are photographs of specimens glued with an adhesive coacervate modality of the present description.
  • Figures 3a, 3b and 3c are photographs of specimens after immersion in water, the specimens having been previously glued with a modality of the coacervate adhesive of the present description.
  • Figure 4a is an optical microscopy image of a joint of paper substrates glued with an embodiment of the adhesive coacervate of the present disclosure.
  • Figure 4b is an X-ray microtomography image of the interface between glass slides bonded with an adhesive coacervate embodiment of the present disclosure.
  • Figure 5 is a graph showing the maximum rupture strength as a function of elongation of specimens subjected to shear testing of simple joints bonded with a modality of the coacervate adhesive of the present description.
  • Adhesive coacervates based on anionic or cationic nanocellulose and lignosulfonate and their production processes are described.
  • the nanocellulose used comes from sugarcane bagasse, which is an environmentally sustainable raw material and is an abundant agro-industrial residue.
  • the nanocellulose used comes from woody species, such as eucalyptus and pine, or from fibrous species, such as cotton, rice and corn.
  • the nanocellulose used is obtained by mechanical treatment of the cellulosic pulp, with the rupture of hydrogen bonds between the fibers and reduction of the size of the fibers, resulting in a nanofibrillated cellulose (NFC).
  • NFC nanofibrillated cellulose
  • the CNF is subjected to a pre-treatment of cationization or oxidation by TEMPO, before being added to the lignosulfonate to prepare the adhesive.
  • the nanocellulose used is obtained from the controlled acid hydrolysis of the cellulosic pulp, with removal of the amorphous regions of the material generating well-defined crystals of nanocellulose stable in colloidal suspension, resulting in a nanocrystalline cellulose (CNC) ).
  • CNC nanocrystalline cellulose
  • the CNC is subjected to a pre-treatment of cationization or oxidation by TEMPO, before being added to the lignosulfonate to prepare the adhesive.
  • the process is conducted by the dropwise addition of a lignosulfonate solution to an aqueous nanocellulose dispersion.
  • the aqueous dispersion of nanocellulose has a solids content of 0.1% to 10% by weight on a dry basis.
  • it is necessary to homogenize the dispersion for example, using a vortex mixer with moderate agitation, from 200 to 3000 RPM, for a period between 2 and 20 seconds.
  • the mixture of components is left under moderate agitation, for example, using a vortex mixer at 200 to 3000 RPM, for 2 to 5 minutes, at room temperature, to ensure homogenization.
  • FIG. 1 presents an illustrative scheme of the electrostatic complexation process between modified cellulose (represented in red) and the lignosulfonate (shown in blue).
  • Electrostatic complexation is a type of non-covalent supramolecular interaction between two oppositely charged species that, in general, leads to an associative phase separation.
  • the electrostatic attraction of these components occurs, releasing the counter-ions to the medium and promoting a separation of liquid-liquid phases, where the phase rich in polyelectrolytes is called coacervate, and the phase rich in water and counter ions is called the dilute phase.
  • the adhesive coacervates based on nanocellulose and lignosulfonate obtained from the process described herein contain from 10% to 90% of nanocellulose and from 10% to 90% of lignosulfonate, both expressed in mass on a dry basis.
  • the adhesive was tested in shear tests of simple joints of glass-glass, paper-paper and MDF-MDF (English acronym for "wood fiber and medium density boards"), the test being adapted from the ASTM D1002 standard -10 in a universal EMIC testing machine attached to a load cell with capacity of 50 kgf.
  • Glass specimens comprise pairs of slides, each 7.6 cm long and 2.6 cm wide.
  • the other specimens are made up of pairs of strips 8.0 cm long and 2.0 cm wide.
  • the joint was formed by adding about 400 pL of the polyelectrolytic suspension with a concentration of approximately 1 % (m/m) in an adhesion area with dimensions between 1 and 2 cm x 2.5 cm previously wetted with deionized water .
  • the strips were pressed using a standard stainless steel weight of 200 g for 3 min at room temperature.
  • at least 8 specimens of each substrate are prepared for.
  • the specimens were conditioned for 24h, at a temperature of 22 °C and 23% relative humidity before the shear measurements.
  • Figures 2a, 2b and 2c show the specimens prepared for the test.
  • figures 3a, 3b and 3c show the substrates remaining glued after being subjected to immersion in water.
  • Figure 4a presents an optical microscopy image of the paper-paper joint glued with the coacervate adhesive described here.
  • Figure 4b presents images obtained by X-ray microtomography of the interface of the glass sheets joined by the adhesive, in which it can be seen that the interface between the substrates presents a characteristic continuity of bonded systems. During the curing step, adhesion and cohesion interactions are maximized, thus increasing the interaction between the glass and the adhesive.
  • Figure 5 presents a graph of load vs. elongation of this test, with resulting curves for the three substrates: paper-paper, MDF-MDF and glass-glass.
  • FIG 5 is presented a schematic illustration of the test, with the specimens in side view, glued in simple joints and with arrows at their ends indicating the application of the test load. The results of this test are visualized in terms of maximum failure force and maximum failure shear stress in table 1.
  • Table 1 Maximum breaking force and maximum breaking shear stress for the joints of paper, MDF and glass glued with a modality of the adhesive coacervates of the present description.

Abstract

The present application describes an adhesive that is in the form of a solid coacervate made of compounds that can be obtained from agroindustrial waste, particularly cellulose and lignosulphonate. The cellulose used in the composition is nanofibrillated or nanocrystalline cellulose, preferably nanofibrillated cellulose. A method for producing said adhesive coacervate is also described.

Description

COACERVADO ADESIVO A BASE DE NANOCELULOSE E LIGNOSSULFONATO E PROCESSO DE PRODUÇÃO DO MESMOADHESIVE COACERVATE BASED ON NANOCELLULOSE AND LIGNOSULFONATE AND PRODUCTION PROCESS THEREOF
CAMPO DA DESCRIÇÃO DESCRIPTION FIELD
[0001] A presente descrição se refere a composições compreendendo celulose modificada e lignina sulfonada. [0001] The present description relates to compositions comprising modified cellulose and sulfonated lignin.
FUNDAMENTOS DA DESCRIÇÃO DESCRIPTION FUNDAMENTALS
[0002] Celulose é o polímero natural mais abundante do planeta, podendo ser produzido por micro-organismos na forma de celulose microbiana, mas, principalmente, pelas plantas, onde está presente como componente estrutural da parede celular. Por ser um produto proveniente de recursos renováveis, ser biodegradável e biocompatível, a celulose é hoje uma alternativa promissora para uso em diversos materiais. [0002] Cellulose is the most abundant natural polymer on the planet, and can be produced by microorganisms in the form of microbial cellulose, but mainly by plants, where it is present as a structural component of the cell wall. As a product from renewable resources, being biodegradable and biocompatible, cellulose is today a promising alternative for use in various materials.
[0003] Em sua forma pura, a celulose é um polissacarídeo de cadeia linear, com fórmula geral (C6Hio05)n, constituído por centenas ou milhares de unidades de D-glicose ligadas entre si por ligações do tipo 3-1 ,4-glicosídicas. A quantidade de unidades de glicose na cadeia polimérica, também conhecida como grau de polimerização (DP), depende da espécie e das condições de crescimento da planta. Por exemplo, celuloses extraídas de polpa de madeiras, como eucalipto e pinho, têm cerca de 300 a 1700 unidades do sacarídeo em sua cadeia, enquanto celuloses provenientes de espécies fibrosas, como o algodão, possuem de 800 a 10000 unidades de glicose. [0003] In its pure form, cellulose is a linear-chain polysaccharide, with the general formula (C 6 Hio0 5 )n, consisting of hundreds or thousands of D-glucose units linked together by 3-1 type bonds, 4-glycosidics. The amount of glucose units in the polymer chain, also known as the degree of polymerization (DP), depends on the species and growth conditions of the plant. For example, cellulose extracted from wood pulp, such as eucalyptus and pine, has about 300 to 1700 units of the saccharide in its chain, while celluloses from fibrous species, such as cotton, have 800 to 10000 units of glucose.
[0004] O comprimento da cadeia e o grau de polimerização refletem em diversas propriedades da celulose. Uma das características da celulose é a baixa solubilidade em água e na maioria dos solventes orgânicos, devido a elevada energia de coesão que envolve ligações de hidrogênio intra e intermoleculares e interações de van der Waals. [0004] The length of the chain and the degree of polymerization reflect on several properties of cellulose. One of the characteristics of cellulose is its low solubility in water and in most organic solvents, due to the high cohesion energy that involves intra and intermolecular hydrogen bonds and van der Waals interactions.
[0005] A celulose pode ser encontrada com diferentes propriedades mecânicas, devido à variedade de formas, tamanhos e graus de cristalinidade de suas partículas. Para uso industrial, a celulose é obtida principalmente a partir de polpa de madeira e algodão. É usada principalmente para produzir papel, algodão e linho para roupas, nitrocelulose para filmes e explosivos, acetato de celulose para filmes e carboximetilcelulose para produtos formulados. [0005] Cellulose can be found with different mechanical properties, due to the variety of shapes, sizes and degrees of crystallinity of its particles. For industrial use, cellulose is mainly obtained from wood pulp and cotton. It is mainly used to produce paper, cotton and linen for clothing, nitrocellulose for films and explosives, cellulose acetate for films and carboxymethylcellulose for formulated products.
[0006] Nanocelulose é o termo usado para descrever materiais celulósicos com dimensões na faixa de nanômetros (10-9 m). As nanoceluloses podem ser classificadas em três categorias principais: i) celulose nanofibrilada (CNF), ii) celulose nanocristalina (CNC) e iii) nanocelulose bacteriana (BNC). [0006] Nanocellulose is the term used to describe cellulosic materials with dimensions in the nanometer range (10 -9 m). Nanocelluloses can be classified into three main categories: i) nanofibrillated cellulose (CNF), ii) nanocrystalline cellulose (CNC) and iii) bacterial nanocellulose (BNC).
[0007] A principal rota de obtenção da CNC é via hidrólise ácida da polpa celulósica. Este método promove a remoção das regiões amorfas do material gerando cristais bem definidos de nanocelulose estáveis em suspensão coloidal. [0007] The main route of obtaining CNC is via acid hydrolysis of cellulosic pulp. This method promotes the removal of amorphous regions of the material, generating well-defined crystals of stable nanocellulose in colloidal suspension.
[0008] A CNF é obtida pelo tratamento mecânico da polpa celulósica. O cisalhamento mecânico é responsável pelo rompimento da estrutura rígida das fibras de celulose, fortemente coesas por ligações de hidrogênio e interações de van der Walls, diminuindo assim o tamanho das fibras. [0008] The CNF is obtained by the mechanical treatment of the cellulose pulp. Mechanical shear is responsible for breaking the rigid structure of cellulose fibers, strongly cohesive by hydrogen bonds and van der Walls interactions, thus decreasing the size of the fibers.
[0009] A nanocelulose tem atraído grande atenção de pesquisadores devido suas interessantes propriedades, como excelentes características mecânicas, alta área superficial, riqueza de grupos hidroxila para funcionalização e características ecológicas importantes ao meio ambiente. [0009] Nanocellulose has attracted great attention from researchers due to its interesting properties, such as excellent mechanical characteristics, high surface area, richness of hydroxyl groups for functionalization and ecological characteristics important to the environment.
[0010] Lignina é a segunda macromolécula natural mais abundante na natureza. Assim como a celulose, a lignina está presente na parede celular de tecidos vegetais, compondo de 10% a 25% da biomassa lignocelulósica. Na parede celular vegetal, a lignina preenche os espaços entre os componentes de celulose e hemicelulose, mantendo as fibras celulósicas unidas e, consequentemente, é responsável por conferir propriedades estruturais como rigidez, resistência e impermeabilidade às plantas vasculares, principalmente de espécies lenhosas. [0010] Lignin is the second most abundant natural macromolecule in nature. Like cellulose, lignin is present in the cell wall of plant tissues, comprising 10% to 25% of lignocellulosic biomass. In the plant cell wall, lignin fills the spaces between the cellulose and hemicellulose components, keeping the cellulosic fibers together and, consequently, is responsible for conferring structural properties such as rigidity, resistance and impermeability to vascular plants, especially woody species.
[0011] A lignina é uma macromolécula tridimensional altamente reticulada constituída por três tipos de fenóis substituídos (álcoois coniferílico, sinapílico e p- cumarílico) organizados em ligações covalentes cruzadas (cross-link). Suas cadeias podem ter diferentes estruturas e graus de polimerização, dependendo da espécie de planta a qual é extraída. [0011] Lignin is a highly cross-linked three-dimensional macromolecule consisting of three types of substituted phenols (coniferyl, synapyl and p-coumaryl alcohols) organized in cross-linked covalent bonds. Their chains can have different structures and degrees of polymerization, depending on the species of plant from which they are extracted.
[0012] Uma rota de extração da lignina compreende o tratamento da madeira por processos de oxidação, como o processo Kraft, e posterior extração e purificação da lignina a partir do licor negro gerado. São bem conhecidos três procedimentos comerciais para extrair e purificar a lignina do licor negro, sendo os processos LignoBoost™ (com características reveladas em W02006031175, W02006038863, WQ2009104995, dentre outros documentos), LignoForce™ (com características reveladas em WO2011150508, dentre outros documentos), e o processo sequencial de recuperação e purificação da lignina líquida, de acrônimo inglês SLRP (com características reveladas em WO2011037967, WO2012161865, dentre outros documentos). Nos dois primeiros processos o pH do licor negro é reduzido para aproximadamente de 9 a 10, usando CO2 ou ácido mineral, o que leva a precipitação da lignina. A lignina é então separada por filtração ou prensagem, e as impurezas são removidas pela lavagem com solução aquosa de ácido, levando a formação de lignina com alta pureza. Já no processo SLRP a lignina do licor negro precipita como uma fase líquida, separando-se apenas pela gravidade e não por filtragem, como nos outros dois processos; isso confere maior pureza da lignina obtida com um menor número de etapas de tratamento. [0012] A lignin extraction route comprises the treatment of wood by oxidation processes, such as the Kraft process, and subsequent extraction and purification of lignin from the generated black liquor. Three commercial procedures for extracting and purifying lignin from black liquor are well known, being the processes LignoBoost™ (with features disclosed in W02006031175, W02006038863, WQ2009104995, among other documents), LignoForce™ (with features disclosed in WO2011150508, among other documents) , and the sequential process of recovery and purification of liquid lignin, of English acronym SLRP (with characteristics revealed in WO2011037967, WO2012161865, among other documents). In the first two processes, the pH of the black liquor is reduced to approximately 9 to 10, using CO 2 or mineral acid, which leads to the precipitation of lignin. The lignin is then separated by filtration or pressing, and the impurities are removed by washing with an aqueous acid solution, leading to the formation of lignin with high purity. In the SLRP process, the lignin of the black liquor precipitates as a liquid phase, separating only by gravity and not by filtration, as in the other two processes; this confers greater purity of the lignin obtained with a smaller number of treatment steps.
[0013] A extração de lignina por processos de reação do licor negro com sulfitos ou outros derivados de enxofre gera lignossulfonatos de alto valor agregado. Neste processo, a matéria-prima lignocelulósica é colocada para reagir com uma mistura de CO2 e uma base de sulfito, em condições de alta temperatura e pH ácido, obtendo-se então um licor composto por lignina sulfonada (lignossulfonato). Os lignossulfonatos têm uma ampla variedade de aplicações, dentre as quais pode-se citar seu uso como aditivo plastificante na fabricação de cimento e asfalto, dispersantes para defensivos agrícolas e corantes têxteis, agente de tratamento de água, entre outros. [0013] The extraction of lignin by reaction processes of black liquor with sulfites or other sulfur derivatives generates lignosulphonates of high added value. In this process, the lignocellulosic raw material is placed to react with a mixture of CO 2 and a sulfite base, under conditions of high temperature and acidic pH, thus obtaining a liquor composed of sulfonated lignin (lignosulphonate). Lignosulfonates have a wide variety of applications, among which its use as a plasticizing additive in the manufacture of cement and asphalt, dispersants for agricultural pesticides and textile dyes, water treatment agent, among others.
[0014] O termo "coacervado" é utilizado na química dos colóides para denotar associação de moléculas com cargas opostas (polieletrólitos) que levam a formação de uma fase pobre em água. Quando separados, esses policátions e poliânions apresentam boa solubilidade no meio aquoso. No entanto, quando essas espécies são misturadas ocorrem interações eletrostáticas que levam a formação de espécies neutras, menos solúveis no meio aquoso, ocorrendo então separação de fases. A fase rica em colóide é conhecida como fase coacervada, enquanto a que contém quantidades muito pequenas de colóide é conhecida como fase de equilíbrio. [0014] The term "coacervate" is used in colloid chemistry to denote association of oppositely charged molecules (polyelectrolytes) that lead to the formation of a water-poor phase. When separated, these polycations and polyanions show good solubility in aqueous media. However, when these species are mixed, electrostatic interactions occur that lead to the formation of species. neutral, less soluble in the aqueous medium, then phase separation occurs. The colloid-rich phase is known as the coacervated phase, while the phase containing very small amounts of colloid is known as the equilibrium phase.
ESTADO DA TÉCNICA STATUS OF THE TECHNIQUE
[0015] O estado da técnica apresenta algumas formulações de adesivos compreendendo lignina e seus derivados. [0015] The state of the art presents some adhesive formulations comprising lignin and its derivatives.
[0016] Ghaffar e Fan (2014, International Journal of Adhesion & Adhesives, v. [0016] Ghaffar and Fan (2014, International Journal of Adhesion & Adhesives, v.
48, p. 92-101 ) apresentam uma revisão sobre a lignina de palha (em contraste com a lignina de madeira) e suas possíveis aplicações em formulações de adesivos. 48, p. 92-101 ) present a review of straw lignin (in contrast to wood lignin) and its possible applications in adhesive formulations.
[0017] O documento de patente US20160168272A1 revela um processo para produção de fibras celulose, nanofibras e nanocristais de celulose contendo lignina. [0017] Patent document US20160168272A1 discloses a process for producing cellulose fibers, nanofibers and lignin-containing cellulose nanocrystals.
[0018] O documento de patente WO2019213730A1 revela um adesivo a base de látex de borracha natural em pH igual ou maior que 9, lignina precipitada em pH ácido em sua forma não-funcionalizada e nanocelulose em sua forma não- funcionalizada, bem como o processo de produção do mesmo. [0018] Patent document WO2019213730A1 discloses an adhesive based on natural rubber latex at pH equal to or greater than 9, lignin precipitated at acidic pH in its non-functionalized form and nanocellulose in its non-functionalized form, as well as the process of production of the same.
[0019] Jayaramudu e colaboradores (2019, Composites Part B, v. 156, p. 43- 50) revelam um adesivo feito de mistura de poli(óxido de etileno) e lignina (PEO-L). O aumento do conteúdo de lignina na mistura mostrou proporcional aumento das propriedades adesivas, sendo a tensão de cisalhamento do adesivo de PEO puro 442 kPa, enquanto a tensão de cisalhamento do adesivo de PEO-L com 30% de lignina foi de 835 kPa, em ensaios do tipo single lap joint realizados em filmes de celulose nanofibrilada (CNF). [0019] Jayaramudu et al (2019, Composites Part B, v. 156, p. 43-50) disclose an adhesive made from a mixture of poly(ethylene oxide) and lignin (PEO-L). The increase in the lignin content in the mixture showed a proportional increase in the adhesive properties, with the shear stress of the pure PEO adhesive being 442 kPa, while the shearing stress of the PEO-L adhesive with 30% lignin was 835 kPa, in single lap joint tests performed on nanofibrillated cellulose (CNF) films.
[0020] Yotov e colaboradores (2017, Bulgarian Chemical Communications, v. [0020] Yotov et al (2017, Bulgarian Chemical Communications, v.
49, Special Issue L, p. 92-97) revela um adesivo cuja composição compreende lignossulfonatos em substituição parcial ou total da resina fenol-formaldeido (PFR) tradicionalmente utilizada para esse tipo de compósito. As propriedades mecânicas e a resistência à água desse adesivo natural de lignossulfonato se mostram adequadas frente às especificações definidas em padrões de adesivos para fabricação de placas de fibra de madeira de média densidade (MDF). Na fabricação desse compósito, as fibras de madeira e o lignossulfonato são coladas em alta temperatura e pressão, processo denominado auto-adesão. 49, Special Issue L, p. 92-97) discloses an adhesive whose composition comprises lignosulfonates in partial or total replacement of the phenol-formaldehyde resin (PFR) traditionally used for this type of composite. The mechanical properties and water resistance of this natural lignosulfonate adhesive are adequate in relation to the specifications defined in adhesive standards for the manufacture of medium density wood fiber boards (MDF). In the manufacture of this composite, the wood fibers and the lignosulfonate are glued in high temperature and pressure, a process called self-adhesion.
[0021] O documento de patente US6790271 B2 revela uma formulação adesiva à prova d'água compreendendo proteína de soja isolada, um plastificante, um óleo vegetal e lignina ou um derivado de lignina. A proteína de soja encontra-se em proporção acima de 50%, conferindo ao adesivo resistência à água. O plastificante descrito é um poliol, preferencialmente glicerol, em concentração acima de 20%. O óleo vegetal é modificado para ter ao menos um sítio reativo com a proteína e o poliol. A função da lignina ou um derivado de lignina é aumentar a rigidez do adesivo. O derivado de lignina que apresentou resultados mais vantajosos na fabricação do adesivo da descrição foi o lignossulfonato. Uma desvantagem associada a essa técnica anterior é a necessidade de curar o adesivo em altas temperaturas (cerca de 165 °C). [0021] Patent document US6790271 B2 discloses a waterproof adhesive formulation comprising isolated soy protein, a plasticizer, a vegetable oil and lignin or a lignin derivative. Soy protein is present in a proportion above 50%, giving the adhesive water resistance. The plasticizer described is a polyol, preferably glycerol, in a concentration above 20%. Vegetable oil is modified to have at least one reactive site with the protein and the polyol. The function of lignin or a lignin derivative is to increase the stiffness of the adhesive. The lignin derivative that presented the most advantageous results in the manufacture of the adhesive of the description was lignosulfonate. A disadvantage associated with this prior art is the need to cure the adhesive at high temperatures (about 165°C).
[0022] Não é revelado no estado da técnica um adesivo que compreenda lignossulfonato combinado com um outro componente que não seja derivado de petróleo, proteína, óleo vegetal ou poliol. [0022] It is not disclosed in the prior art an adhesive that comprises lignosulfonate combined with another component that is not derived from petroleum, protein, vegetable oil or polyol.
[0023] Também não é revelado no estado da técnica um adesivo contendo nanofibras e/ou nanocristais com superfícies funcionalizadas com grupos aniônicos ou catiônicos, e que dispensa aplicação de altas temperaturas em uma etapa de cura ou auto-adesão. [0023] Also not disclosed in the prior art is an adhesive containing nanofibers and/or nanocrystals with surfaces functionalized with anionic or cationic groups, and which does not require the application of high temperatures in a curing or self-adhesion step.
BREVE DESCRIÇÃO DO OBJETO BRIEF DESCRIPTION OF THE OBJECT
[0024] É um dos objetivos da presente descrição revelar um adesivo à prova d'água, capaz de unir uma pluralidade de substratos e que apresenta fácil aplicação. Esta pluralidade de substratos compreende vidros, polímeros ou substratos celulósicos de diferentes composições, incluindo tecidos, madeiras, papéis e papelão, todos podendo estar em condições molhadas ou úmidas. Também é objetivo da presente descrição que tal adesivo seja capaz de unir juntas de substratos similares ou díspares. [0024] It is one of the objectives of the present description to reveal a waterproof adhesive, capable of joining a plurality of substrates and presenting easy application. This plurality of substrates comprises glass, polymers or cellulosic substrates of different compositions, including fabrics, woods, papers and cardboard, all of which may be in wet or humid conditions. It is also an object of the present description that such an adhesive is capable of joining joints of similar or dissimilar substrates.
[0025] Os objetivos da presente descrição são alcançados por um coacervado adesivo compreendendo de 0,01 a 10% (m/m) de nanocelulose aniônica ou catiônica e de 0,01 a 40% (m/m) lignina sulfonada, o qual se fixa em substratos secos ou molhados, sem necessidade de aplicar altas temperaturas e/ou pressões para fixação do mesmo. [0025] The purposes of the present description are achieved by an adhesive coacervate comprising from 0.01 to 10% (m/m) of anionic or cationic nanocellulose and from 0.01 to 40% (m/m) sulfonated lignin, which settles on dry substrates or wet, without the need to apply high temperatures and/or pressures for fixing it.
[0026] Os objetivos da presente descrição também são alcançados por um processo de produção do referido coacervado adesivo. Este processo compreende misturar uma solução de lignina sulfonada em uma dispersão aquosa de nanocelulose aniônica ou catiônica, homogeneizar a mistura, centrifugar e separar a fase sólida da mesma, em que a fase sólida é o coacervado adesivo. [0026] The purposes of the present description are also achieved by a process of producing said adhesive coacervate. This process comprises mixing a sulfonated lignin solution in an aqueous dispersion of anionic or cationic nanocellulose, homogenizing the mixture, centrifuging and separating the solid phase thereof, where the solid phase is the adhesive coacervate.
BREVE DESCRIÇÃO DAS FIGURAS BRIEF DESCRIPTION OF THE FIGURES
[0027] As modalidades ora descritas encontram-se ilustradas nas figuras listadas a seguir. [0027] The modalities described herein are illustrated in the figures listed below.
[0028] A figura 1 é uma ilustração esquemática do processo de complexação eletrostática de componentes do adesivo da presente descrição. [0028] Figure 1 is a schematic illustration of the electrostatic complexation process of components of the adhesive of the present description.
[0029] As figuras 2a, 2b e 2c são fotografias de corpos de prova colados com uma modalidade do coacervado adesivo da presente descrição. [0029] Figures 2a, 2b and 2c are photographs of specimens glued with an adhesive coacervate modality of the present description.
[0030] As figuras 3a, 3b e 3c são fotografias de corpos de prova após imersão em água, os corpos de prova tendo sido previamente colados com uma modalidade do coacervado adesivo da presente descrição. [0030] Figures 3a, 3b and 3c are photographs of specimens after immersion in water, the specimens having been previously glued with a modality of the coacervate adhesive of the present description.
[0031] A figura 4a é uma imagem de microscopia ótica de uma junta de substratos de papel colada com uma modalidade do coacervado adesivo da presente descrição. [0031] Figure 4a is an optical microscopy image of a joint of paper substrates glued with an embodiment of the adhesive coacervate of the present disclosure.
[0032] A figura 4b é uma imagem de microtomografia de raios X da interface entre lâminas de vidro coladas com uma modalidade do coacervado adesivo da presente descrição. [0032] Figure 4b is an X-ray microtomography image of the interface between glass slides bonded with an adhesive coacervate embodiment of the present disclosure.
[0033] A figura 5 é um gráfico mostrando a força máxima de ruptura em função do alongamento de corpos de prova submetidos a ensaio de cisalhamento de juntas simples coladas com uma modalidade do coacervado adesivo da presente descrição. [0033] Figure 5 is a graph showing the maximum rupture strength as a function of elongation of specimens subjected to shear testing of simple joints bonded with a modality of the coacervate adhesive of the present description.
DESCRIÇÃO DETALHADA DO OBJETO DETAILED DESCRIPTION OF THE OBJECT
[0034] São descritos coacervados adesivos à base de nanocelulose aniônica ou catiônica e lignossulfonato e processos de produção dos mesmos. [0035] Na modalidade preferida do coacervado adesivo, a nanocelulose utilizada é proveniente de bagaço de cana-de-açúcar, que é uma matéria prima ambientalmente sustentável e trata-se de um resíduo agroindustrial abundante. [0034] Adhesive coacervates based on anionic or cationic nanocellulose and lignosulfonate and their production processes are described. [0035] In the preferred modality of adhesive coacervate, the nanocellulose used comes from sugarcane bagasse, which is an environmentally sustainable raw material and is an abundant agro-industrial residue.
[0036] Em uma modalidade do coacervado adesivo, a nanocelulose utilizada é proveniente de espécies lenhosas, como eucalipto e pinho, ou de espécies fibrosas, como algodão, arroz e milho. [0036] In a modality of adhesive coacervate, the nanocellulose used comes from woody species, such as eucalyptus and pine, or from fibrous species, such as cotton, rice and corn.
[0037] Em uma modalidade do coacervado adesivo, a nanocelulose utilizada é obtida pelo tratamento mecânico da polpa celulósica, com o rompimento de ligações de hidrogênio entre as fibras e diminuição do tamanho das fibras, resultando em uma celulose nanofibrilada (CNF). Nessa modalidade, a CNF é submetida a um pré- tratamento de cationização ou oxidação por TEMPO, antes de ser adicionada ao lignossulfonato para preparação do adesivo. [0037] In a modality of coacervate adhesive, the nanocellulose used is obtained by mechanical treatment of the cellulosic pulp, with the rupture of hydrogen bonds between the fibers and reduction of the size of the fibers, resulting in a nanofibrillated cellulose (NFC). In this modality, the CNF is subjected to a pre-treatment of cationization or oxidation by TEMPO, before being added to the lignosulfonate to prepare the adhesive.
[0038] Em uma modalidade do coacervado adesivo, a nanocelulose utilizada é obtida a partir da hidrólise ácida controlada da polpa celulósica, com remoção das regiões amorfas do material gerando cristais bem definidos de nanocelulose estáveis em suspensão coloidal, resultando em uma celulose nanocristalina (CNC). Nessa modalidade, a CNC é submetida a um pré-tratamento de cationização ou oxidação por TEMPO, antes de ser adicionada ao lignossulfonato para preparação do adesivo. [0038] In an adhesive coacervate modality, the nanocellulose used is obtained from the controlled acid hydrolysis of the cellulosic pulp, with removal of the amorphous regions of the material generating well-defined crystals of nanocellulose stable in colloidal suspension, resulting in a nanocrystalline cellulose (CNC) ). In this modality, the CNC is subjected to a pre-treatment of cationization or oxidation by TEMPO, before being added to the lignosulfonate to prepare the adhesive.
[0039] Em uma modalidade do presente processo de produção do coacervado adesivo, o processo é conduzido por meio da adição, gota-a-gota, de uma solução de lignossulfonato a uma dispersão aquosa de nanocelulose. A dispersão aquosa de nanocelulose tem teor de sólidos de 0,1% a 10% em massa em base seca. Para cada gota da solução de lignossulfonato adicionada é necessário homogeneizar a dispersão, por exemplo, utilizando-se um agitador vórtex com agitação moderada, de 200 a 3000 RPM, por período entre 2 e 20 segundos. Ao final da etapa de adição do lignossulfonato, a mistura dos componentes é deixada sob agitação moderada, por exemplo, utilizando-se um agitador vórtex de 200 a 3000 RPM, por 2 a 5 minutos, a temperatura ambiente, para garantir a homogeneização. [0039] In one embodiment of the present adhesive coacervate production process, the process is conducted by the dropwise addition of a lignosulfonate solution to an aqueous nanocellulose dispersion. The aqueous dispersion of nanocellulose has a solids content of 0.1% to 10% by weight on a dry basis. For each drop of lignosulfonate solution added, it is necessary to homogenize the dispersion, for example, using a vortex mixer with moderate agitation, from 200 to 3000 RPM, for a period between 2 and 20 seconds. At the end of the lignosulfonate addition step, the mixture of components is left under moderate agitation, for example, using a vortex mixer at 200 to 3000 RPM, for 2 to 5 minutes, at room temperature, to ensure homogenization.
[0040] A figura 1 apresenta um esquema ilustrativo do processo de complexação eletrostática entre a celulose modificada (representada em vermelho) e o lignossulfonato (representado em azul). A complexação eletrostática é um tipo de interação supramolecular não covalente entre duas espécies de cargas opostas que, em geral, leva a uma separação de fases associativa. Durante a etapa de misturas da celulose e lignina, ocorre a atração eletrostática destes componentes, liberando os contra-íons para o meio e promovendo uma separação de fases líquido-líquido, onde a fase rica em polieletrólitos é denominada coacervado, e a fase rica em água e contra-íons é denominada como fase diluída. [0040] Figure 1 presents an illustrative scheme of the electrostatic complexation process between modified cellulose (represented in red) and the lignosulfonate (shown in blue). Electrostatic complexation is a type of non-covalent supramolecular interaction between two oppositely charged species that, in general, leads to an associative phase separation. During the step of mixing cellulose and lignin, the electrostatic attraction of these components occurs, releasing the counter-ions to the medium and promoting a separation of liquid-liquid phases, where the phase rich in polyelectrolytes is called coacervate, and the phase rich in water and counter ions is called the dilute phase.
[0041] Em uma modalidade do presente processo de produção do coacervado adesivo, após a complexação eletrostática e a homogeneização da mistura, a mesma é centrifugada por 5 a 60 minutos com velocidades entre 4500 e 6000 RPM, ocorrendo a separação entre a fase rica em polieletrólitos e a fase rica em água e contra-íons. Após a centrifugação, o sobrenadante líquido é descartado e o produto sólido é o coacervado adesivo da presente descrição, estando pronto para ser aplicado sobre as superfícies de substratos, tais como papel, vidro, plástico e alumínio, sem necessidade de aplicação de calor e/ou pressão elevada para cura do adesivo. [0041] In a modality of the present process of production of the adhesive coacervate, after the electrostatic complexation and the homogenization of the mixture, it is centrifuged for 5 to 60 minutes with speeds between 4500 and 6000 RPM, occurring the separation between the phase rich in polyelectrolytes and the water-rich phase and counter-ions. After centrifugation, the liquid supernatant is discarded and the solid product is the coacervate adhesive of the present description, being ready to be applied on the surfaces of substrates, such as paper, glass, plastic and aluminum, without the need for application of heat and/or or high pressure to cure the adhesive.
[0042] Os coacervados adesivos a base de nanocelulose e lignossulfonato obtidos a partir do processo aqui descrito contêm de 10% a 90% de nanocelulose e de 10% a 90% de lignossulfonato, ambas expressas em massa em base seca. [0042] The adhesive coacervates based on nanocellulose and lignosulfonate obtained from the process described herein contain from 10% to 90% of nanocellulose and from 10% to 90% of lignosulfonate, both expressed in mass on a dry basis.
ENSAIOS EM JUNTAS ADESIVAS TESTS ON ADHESIVE JOINTS
[0043] Foram realizados ensaios de cisalhamento em corpos de prova apresentando juntas unidas com o coacervado adesivo de uma modalidade da presente invenção. Em todos os ensaios, a modalidade do coacervado adesivo utilizada apresenta 50% de CNF e 50% de lignossulfonato, ambas concentrações em massa seca, o adesivo tendo sido obtido segundo quaisquer processos aqui descritos. [0043] Shear tests were performed on specimens showing joints joined with the coacervate adhesive of an embodiment of the present invention. In all tests, the coacervate adhesive modality used has 50% CNF and 50% lignosulfonate, both concentrations in dry mass, the adhesive having been obtained according to any of the processes described herein.
[0044] O adesivo foi testado em ensaios de cisalhamento de juntas simples de vidro-vidro, papel-papel e MDF-MDF (sigla inglesa para “placas de fibra de madeira e média densidade”), sendo o ensaio adaptado da norma ASTM D1002-10 em uma máquina universal de ensaios EMIC acoplada a uma célula de carga com capacidade de 50 kgf. Os corpos de provas de vidro compreendem pares de lâminas, cada qual com 7,6 cm de comprimento e 2,6 cm de largura. Os demais corpos de provas são constituídos de pares de tiras com 8,0 cm de comprimento e 2,0 cm de largura. [0044] The adhesive was tested in shear tests of simple joints of glass-glass, paper-paper and MDF-MDF (English acronym for "wood fiber and medium density boards"), the test being adapted from the ASTM D1002 standard -10 in a universal EMIC testing machine attached to a load cell with capacity of 50 kgf. Glass specimens comprise pairs of slides, each 7.6 cm long and 2.6 cm wide. The other specimens are made up of pairs of strips 8.0 cm long and 2.0 cm wide.
[0045] A junta foi formada pela adição de cerca de 400 pL da suspensão polieletrolitica com concentração de aproximadamente 1 % (m/m) em uma área de adesão com dimensões entre 1 e 2 cm x 2,5 cm previamente molhada com água deionizada. As tiras foram prensadas usando um peso padrão em aço inox de 200 g por 3 min a temperatura ambiente. Para este ensaio da formulação testada, são preparados no mínimo 8 corpos de prova de cada substrato para. Os corpos de prova foram condicionados por 24h, a temperatura de 22 °C e 23 % de umidade relativa antes das medidas de cisalhamento. As figuras 2a, 2b e 2c apresentam os corpos de prova preparados para o ensaio. Por sua vez, as figuras 3a, 3b e 3c apresentam os substratos permanecendo colados após serem submetidos a imersão em água. [0045] The joint was formed by adding about 400 pL of the polyelectrolytic suspension with a concentration of approximately 1 % (m/m) in an adhesion area with dimensions between 1 and 2 cm x 2.5 cm previously wetted with deionized water . The strips were pressed using a standard stainless steel weight of 200 g for 3 min at room temperature. For this test of the tested formulation, at least 8 specimens of each substrate are prepared for. The specimens were conditioned for 24h, at a temperature of 22 °C and 23% relative humidity before the shear measurements. Figures 2a, 2b and 2c show the specimens prepared for the test. In turn, figures 3a, 3b and 3c show the substrates remaining glued after being subjected to immersion in water.
[0046] A figura 4a apresenta uma imagem de microscopia óptica da junta papel-papel colada com o coacervado adesivo aqui descrito. Por sua vez, a figura 4b apresenta imagens obtidas por microtomografia de raios X da interface das lâminas de vidro unidas pelo adesivo, em que se pode ver que a interface entre os substratos apresenta uma continuidade caraterística de sistemas colados. Durante a etapa de cura, as interações de adesão e coesão são maximizadas, aumentando assim a interação entre o vidro e o adesivo. [0046] Figure 4a presents an optical microscopy image of the paper-paper joint glued with the coacervate adhesive described here. In turn, Figure 4b presents images obtained by X-ray microtomography of the interface of the glass sheets joined by the adhesive, in which it can be seen that the interface between the substrates presents a characteristic continuity of bonded systems. During the curing step, adhesion and cohesion interactions are maximized, thus increasing the interaction between the glass and the adhesive.
[0047] Os três corpos de prova (juntas de papel, MDF e vidro) foram submetidos a ensaio de cisalhamento de juntas simples coladas, utilizando uma velocidade de cisalhamento de 1 ,5 mm/min. A tensão de cisalhamento máxima de ruptura foi determinada pela razão entre a força máxima de ruptura e a área colada dos corpos de prova. [0047] The three specimens (joints made of paper, MDF and glass) were subjected to a shear test of simple glued joints, using a shear speed of 1.5 mm/min. The maximum failure shear stress was determined by the ratio between the maximum failure force and the bonded area of the specimens.
[0048] A figura 5 apresenta um gráfico de carga vs. alongamento desse ensaio, com curvas resultantes para os três substratos: papel-papel, MDF-MDF e vidro-vidro. Na mesma figura 5 é apresentada uma ilustração esquemática do ensaio, com os corpos de prova em vista lateral, colados em juntas simples e com setas em suas extremidades indicando a aplicação da carga de ensaio. Os resultados deste ensaio são visualizados em termos de força máxima de ruptura e tensão de cisalhamento máxima de ruptura na tabela 1 . [0048] Figure 5 presents a graph of load vs. elongation of this test, with resulting curves for the three substrates: paper-paper, MDF-MDF and glass-glass. In the same figure 5 is presented a schematic illustration of the test, with the specimens in side view, glued in simple joints and with arrows at their ends indicating the application of the test load. The results of this test are visualized in terms of maximum failure force and maximum failure shear stress in table 1.
[0049] Tabela 1 - Força máxima de ruptura e tensão de cisalhamento máxima de ruptura para as juntas de papel, MDF e vidro colados com uma modalidade dos coacervados adesivos da presente descrição. [0049] Table 1 - Maximum breaking force and maximum breaking shear stress for the joints of paper, MDF and glass glued with a modality of the adhesive coacervates of the present description.
Tensão de cisalhamentoShear stress
Corpos de prova Força máxima de ruptura (N) máxima de ruptura (kPa)Specimens Maximum breaking force (N) Maximum breaking strength (kPa)
Papel-papel 22,3 ± 0,5 11 ,1 ± 0,2 Paper-paper 22.3 ± 0.5 11 .1 ± 0.2
MDF-MDF 88,5 ± 15 24,3 ± 0,1 MDF-MDF 88.5 ± 15 24.3 ± 0.1
Vidro-vidro 61 ,4 ± 0,3 44,3 ± 7,7 Glass-glass 61.4 ± 0.3 44.3 ± 7.7
[0050] Os resultados dos ensaios apresentados demonstram a boa interação do coacervado adesivo com os substratos, sua capacidade de cura a temperatura ambiente, sua resistência à água após a cura e sua boa resistência mecânica em ensaio de cisalhamento. Aliado a essas vantagens, cabe destacar a seleção de componentes e métodos ambientalmente amigáveis na composição e processo de fabricação do coacervado adesivo aqui descrito. [0050] The results of the tests presented demonstrate the good interaction of the adhesive coacervate with the substrates, its ability to cure at room temperature, its resistance to water after curing and its good mechanical resistance in shear test. Allied to these advantages, it is worth highlighting the selection of environmentally friendly components and methods in the composition and manufacturing process of the coacervate adhesive described here.
[0051] Embora modalidades exemplares dos processos e produtos descritos tenham sido apresentadas neste relatório, não se pretende que o escopo de proteção seja limitado à literalidade das mesmas. Portanto, a descrição deve ser interpretada não como limitativa, mas meramente como exemplificações de modalidades particulares que guardam o conceito inventivo aqui apresentado. Um técnico poderá prontamente aplicar ensinamentos aqui apresentados em soluções análogas, decorrentes dos mesmos, limitadas apenas pelo escopo das reivindicações deste pedido. [0051] Although exemplary modalities of the processes and products described have been presented in this report, the scope of protection is not intended to be limited to their literalness. Therefore, the description should be interpreted not as limiting, but merely as exemplifications of particular modalities that keep the inventive concept presented here. One skilled in the art may readily apply teachings presented herein to analogous solutions arising therefrom, limited only by the scope of the claims of this application.

Claims

REIVINDICAÇÕES
1. Coacervado adesivo, caracterizado por compreender em sua formulação lignossulfonato e nanocelulose aniônica ou catiônica. 1. Adhesive coacervate, characterized by comprising in its formulation lignosulfonate and anionic or cationic nanocellulose.
2. Coacervado adesivo, de acordo com a reivindicação 1 , caracterizado pelo fato da nanocelulose ser proveniente de resíduos agroindustriais de uma espécie vegetal selecionada do grupo que compreende cana-de-açúcar, eucalipto, pinho, algodão, arroz, milho e misturas destes. 2. Adhesive coacervate, according to claim 1, characterized in that the nanocellulose comes from agro-industrial residues of a plant species selected from the group that comprises sugarcane, eucalyptus, pine, cotton, rice, corn and mixtures thereof.
3. Coacervado adesivo, de acordo com a reivindicação 2, caracterizado pelo fato da nanocelulose ser proveniente de resíduos agroindustriais de cana-de-açúcar. 3. Adhesive coacervate, according to claim 2, characterized in that the nanocellulose comes from sugarcane agro-industrial residues.
4. Coacervado adesivo, de acordo com qualquer uma das reivindicações 1 a 3, caracterizado pelo fato da nanocelulose ser celulose nanofibrilada. 4. Adhesive coacervate, according to any one of claims 1 to 3, characterized in that the nanocellulose is nanofibrillated cellulose.
5. Coacervado adesivo, de acordo com qualquer uma das reivindicações 1 a 3, caracterizado pelo fato da nanocelulose ser celulose nanocristalina. 5. Adhesive coacervate, according to any one of claims 1 to 3, characterized in that the nanocellulose is nanocrystalline cellulose.
6. Coacervado adesivo, de acordo com qualquer uma das reivindicações 1 a 5, caracterizado por compreender nanocelulose na proporção de 10% a 90% em massa em base seca. Adhesive coacervate, according to any one of claims 1 to 5, characterized in that it comprises nanocellulose in the proportion of 10% to 90% by weight on a dry basis.
7. Coacervado adesivo, de acordo com qualquer uma das reivindicações 1 a 6, caracterizado por compreender lignossulfonato na proporção de 10% a 90% em massa em base seca. Adhesive coacervate, according to any one of claims 1 to 6, characterized in that it comprises lignosulfonate in the proportion of 10% to 90% by weight on a dry basis.
8. Processo de produção do coacervado adesivo a base de nanocelulose e lignossulfonato das reivindicações 1 a 7, caracterizado por: misturar lentamente, gota-a-gota, uma solução de lignina sulfonada em uma dispersão aquosa de nanocelulose, sob agitação moderada, constante, em que a referida dispersão aquosa de nanocelulose tem teor de sólidos de 0,1 % a 10% em massa em base seca; homogeneizar a mistura de lignina sulfonada e nanocelulose, mantendo a agitação moderada entre 2 e 5 min; centrifugar a referida mistura; separar a fase sólida da mistura centrifugada, em que a fase sólida é o coacervado adesivo. 8. Production process of the coacervate adhesive based on nanocellulose and lignosulfonate of claims 1 to 7, characterized by: slowly mixing, drop by drop, a solution of sulfonated lignin in an aqueous dispersion of nanocellulose, under moderate, constant agitation, wherein said aqueous nanocellulose dispersion has a solids content of from 0.1% to 10% by weight on a dry basis; homogenize the sulfonated lignin and nanocellulose mixture, maintaining moderate agitation between 2 and 5 min; centrifuging said mixture; separating the solid phase from the centrifuged mixture, wherein the solid phase is the adhesive coacervate.
9. Processo, de acordo com a reivindicação 8, caracterizado por centrifugar a referida mistura por período entre 14 e 18 minutos com velocidade entre 4500 e 6000 RPM. Process according to claim 8, characterized by centrifuging said mixture for a period between 14 and 18 minutes at a speed between 4500 and 6000 RPM.
10. Uso do coacervado adesivo das reivindicações 1 a 7, caracterizado por ser para a adesão de substratos molhados ou em condições úmidas. 10. Use of the coacervate adhesive of claims 1 to 7, characterized in that it is for the adhesion of wet substrates or in humid conditions.
11. Uso do coacervado adesivo, de acordo com a reivindicação 10, caracterizado por ser para a adesão de substratos similares ou díspares selecionados do grupo compreendendo vidros, polímeros e substratos celulósicos. 11. Use of the adhesive coacervate, according to claim 10, characterized in that it is for the adhesion of similar or dissimilar substrates selected from the group comprising glasses, polymers and cellulosic substrates.
PCT/BR2021/050559 2020-12-18 2021-12-18 Nanocellulose- and lignosulphonate-based adhesive coacervate and method for producing same WO2022126218A1 (en)

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