Bio-based composite material and bio-based composite

Abstract

A bio-based composite material is disclosed. The invention relates to a bio-based composite material comprising sawdust and a resin matrix based on lignin and tannin, the bio-based composite material comprising the sawdust in a total amount of 25-90% by weight based on the total weight of the bio-based composite material. Methods of producing the bio-based composite material, bio-based composites, and methods of producing bio-based composites are also disclosed.

Description

Technical Field

[0001] The present disclosure relates to bio-based composite materials and methods of producing the bio-based composite materials. In addition, the present disclosure relates to bio-based composite materials and methods of producing the bio-based composite materials. Background Art

[0002] Biocomposites are composites formed from a matrix (resin) and natural fiber reinforcements. Environmental considerations and the cost of synthetic fibers have driven research into using natural fibers as reinforcements for polymer composites. The matrix phase can be formed from polymers derived from both renewable and non-renewable resources. In addition to holding the fibers together, the matrix also provides protection to the fibers from environmental degradation and mechanical damage. Many industrial applications require further development of biocomposites. Summary of the invention

[0003] Disclosed is a bio-based composite material, which comprises sawdust and a resin matrix based on lignin and tannin, wherein the bio-based composite material comprises 25-90% by weight of the sawdust, based on the total weight of the bio-based composite material.

[0004] A method for producing a bio-based composite material is also disclosed. The method comprises:

[0005] - providing a resin matrix, wherein the resin matrix is ​​polymerized from lignin and tannin and a cross-linking agent, and has a viscosity of 50-1000 mPa·s;

[0006] - providing sawdust with a dry matter content of 50-100%;

[0007] - spraying the resin matrix onto the sawdust and mixing simultaneously to bond the resin matrix to the sawdust,

[0008] To form the bio-based composite material, wherein the composite material contains 25-90 weight % of sawdust in total based on the total weight of the composite material.

[0009] Also disclosed is a bio-based composite material formed by compounding the bio-based composite material disclosed in the specification.

[0010] A method for producing a bio-based composite is also disclosed. The method comprises:

[0011] - Compounding the bio-based composite material disclosed in the present specification by molding the bio-based composite material while maintaining the temperature of the bio-based composite material at 80-200°C. DETAILED DESCRIPTION

[0012] Disclosed is a bio-based composite material, which comprises sawdust and a resin matrix based on lignin and tannin, wherein the total amount of sawdust contained in the bio-based composite material is 25-90% by weight, based on the total weight of the bio-based composite material.

[0013] Bio-based composite materials may contain water and / or inorganic salts in addition to sawdust and the resin matrix.

[0014] In one embodiment, the bio-based composite material consists of sawdust and a resin matrix. In one embodiment, the bio-based composite material consists of sawdust, a resin matrix and water. In one embodiment, the bio-based composite material consists of sawdust, a resin matrix and an inorganic salt. In one embodiment, the bio-based composite material consists of sawdust, a resin matrix, an inorganic salt and optionally water. In one embodiment, the bio-based composite material consists of sawdust, a resin matrix, an inorganic salt and water.

[0015] In one embodiment, the bio-based composite material is formed from a resin matrix that is sprayed onto sawdust while mixing to bond the resin matrix to the sawdust.

[0016] In one embodiment, the resin matrix is ​​formed by polymerizing lignin and tannin with a cross-linking agent.

[0017] In one embodiment, no compound selected from phenols is used to form the resin matrix. In this specification, unless otherwise indicated, the term "compound selected from phenols" is understood to mean a fossil-based phenolic compound. That is, phenols are compounds consisting of a single aromatic ring to which one or more hydroxyl groups (-OH) are bonded. Such a compound selected from phenols may be, for example, phenol, cresol or resorcinol.

[0018] The inventors have surprisingly discovered that a completely bio-based resin matrix can be used with sawdust to produce a bio-based composite material. When a resin matrix prepared from lignin and tannin (biopolymers) is used, it is possible to provide a resin matrix that can be effectively mixed with sawdust to provide a bio-based composite material from which a "liquid wood"-like composite can be formed. The bio-based composite material has the added benefit of curing in the presence of heat without the use of any additional hardener or curing agent.

[0019] The average particle size of sawdust can be 0.001-1 mm, or 0.01-0.8 mm, or 0.05-0.6 mm, or 0.1-0.4 mm, or 0.15-0.2 mm. The average particle size of sawdust can be determined by a vibrating sieving method using different mesh sizes (5 sieves with mesh sizes between 1.4 mm and 100 μm). After vibration, particles of different sizes may remain on the sieve, which are too large to pass through the sieve.

[0020] Based on the total weight of the bio-based composite material, the bio-based composite material may contain a total amount of 30-88 wt%, or 40-86 wt%, or 50-84 wt%, or 60-82 wt%, or 65-80 wt%, or 70-78 wt% of sawdust. Based on the total weight of the bio-based composite material, the bio-based composite material may contain a total amount of 10-75 wt%, or 12-70 wt%, or 14-60 wt%, or 16-50 wt%, or 18-40 wt%, or 20-35 wt%, or 22-30 wt% of resin matrix.

[0021] A method for producing a bio-based composite material is also disclosed. The method comprises:

[0022] - providing a resin matrix, wherein the resin matrix is ​​polymerized from lignin and tannin with a cross-linking agent to form a resin matrix having a viscosity value of 50-1000 mPa·s;

[0023] - providing sawdust with a dry matter content of 50-100%;

[0024] - spraying the resin matrix onto the sawdust and mixing simultaneously to bond the resin matrix to the sawdust,

[0025] To form the bio-based composite material, wherein the composite material contains 25-90 weight % of sawdust in total based on the total weight of the composite material.

[0026] The cross-linking agent may be an aldehyde, such as formaldehyde or paraformaldehyde. In one embodiment, the aldehyde is prepared from biomethanol. Thus, the aldehyde may be of bio-based origin. The aldehyde may also be of fossil origin. That is, produced from fossil materials. In one embodiment, the aldehyde is prepared from methanol.

[0027] The method comprises providing sawdust having a dry matter content of 50-100%. In one embodiment, the sawdust provided has a dry matter content of 55-95%, or 60-92%, 70-90%, or 80-85%. The dry matter content can be determined after removing liquid from the sample and then drying 1 gram of the sample at a temperature of 105°C for 3 hours. The effectiveness of drying can be ensured by weighing the sample, drying it for another two hours at a specified temperature, and re-weighing the sample. If the measured weights are the same, drying is complete and the total weight can be recorded.

[0028] Unless otherwise stated, "total weight" in this specification is to be understood as the weight of dry matter and liquid part (eg water).

[0029] The molar ratio of the crosslinking agent to the "lignin and tannin" can be 0.9-1.7, or 1.0-1.6, or 1.1-1.7, or 1.2-1.6. In this specification, the calculation method of the molar ratio (MR) is as follows:

[0030] MR=n(Fa) / (n(T)+n(L))

[0031] in

[0032] n = moles of substance

[0033] Fa = cross-linking agent

[0034] T = Tannin

[0035] L = lignin

[0036] The molar amount of a substance is calculated as follows:

[0037] n=M / m

[0038] in

[0039] M = molar mass of the substance, in g / mol

[0040] m = mass of the substance in grams

[0041] In this specification, the above calculations use the following values:

[0042] M (tannin) = 320 g / mol (estimated based on literature and assumed chemical structure)

[0043] M (lignin) = 180 g / mol (estimated based on literature and assumed chemical structure)

[0044] The weight ratio of tannin to lignin may be 0.05-1.0, or 0.1-0.43, or 0.15-0.33.

[0045] In the context of this specification, the term "lignin" may refer to lignin derived from any suitable lignin source. In one embodiment, lignin is substantially pure lignin. The term "substantially pure lignin" should be understood as at least 70% pure lignin, or at least 90% pure lignin, or at least 95% pure lignin, or at least 98% pure lignin. Substantially pure lignin may contain up to 30%, or up to 10%, or up to 5%, or up to 2% other components and / or impurities. Extracts and carbohydrates (such as hemicellulose) may be examples of such other components.

[0046] Furthermore, in the context of this specification, the term "tannin" may refer to tannin derived from any suitable tannin source. In one embodiment, the tannin is substantially pure tannin. The term "substantially pure tannin" is to be understood as at least 70% pure tannin, or at least 90% pure tannin, or at least 95% pure tannin, or at least 98% pure tannin. Substantially pure tannin may contain up to 30%, or up to 10%, or up to 5%, or up to 2% of other components and / or impurities.

[0047] Lignin may contain less than 30 wt %, or less than 10 wt %, or less than 5 wt %, or less than 3 wt %, or less than 2.5 wt %, or less than 2 wt % carbohydrates. Tannin may contain less than 20 wt %, or less than 15 wt %, or less than 10 wt % carbohydrates. The amount of carbohydrates present in lignin or tannin can be measured by high performance anion exchange chromatography with a pulsed amperometric detector (HPAE-PAD) according to the SCAN-CM71 standard.

[0048] The ash percentage of lignin can be less than 7.5 wt%, or less than 5 wt%, or less than 3 wt%, or less than 1.5 wt%. The ash percentage of tannin can be less than 10 wt%, or less than 5 wt%, or less than 3 wt%. The ash content can be determined as follows: First, place the sample in an oven at 105°C for 3 hours and determine the dry solids content. Preheat the ceramic crucible to 700°C for 1 hour and weigh it after cooling. Place the sample (1.5g-2.5g) in the ceramic crucible and weigh it. Place the crucible with a lid in a cold oven. Increase the furnace temperature: 20-200°C, 30 minutes => 200-600°C, 60 minutes => 600-700°C, 60 minutes. Continue burning at 700°C for 60 minutes without covering. Cool the crucible in a desiccator and add a few drops of hydrogen peroxide (H2O2) to the sample. 2 O 2 ,30%), and then burn in a furnace at 700°C for 30 minutes. If there are still black spots in the ash, repeat the hydrogen peroxide treatment and combustion. The crucible is cooled and weighed. All weighings are performed after cooling in a desiccator with an accuracy of 0.1 mg.

[0049] Result calculation

[0050] Ash content % = (100a x 100) / (b x c)

[0051] in

[0052] a=ash weight, g

[0053] b = sample weight, g

[0054] c = dry solids of sample, %.

[0055] The ash content of a sample is the mass of the sample remaining after combustion and annealing, expressed as a percentage of the dry content of the sample.

[0056] In one embodiment, the lignin is industrial lignin. In the context of this specification, the term "industrial lignin" may refer to lignin derived from lignin in any biomass by any technological process. In one embodiment, industrial lignin refers to lignin obtained from an industrial process.

[0057] Lignin for preparing resin matrix can be selected from the group consisting of kraft lignin, steam explosion lignin, biorefining lignin, supercritical separation lignin, hydrolysis lignin, flash precipitation lignin, biomass source lignin, alkaline pulping lignin, soda process lignin, organosol pulping lignin, alkaline lignin, enzyme hydrolysis lignin and any combination thereof. In one embodiment, lignin is wood-based lignin. Lignin can be derived from softwood, hardwood, annual plant or any combination thereof.

[0058] Unless otherwise specified, in this specification, "kraft lignin" is understood to mean lignin derived from kraft black liquor. Black liquor is an alkaline aqueous solution of lignin residues, hemicellulose and inorganic chemicals used in the kraft pulping process. The black liquor from the pulping process includes components derived from different softwood and hardwood species in different proportions. Lignin can be separated from the black liquor by different techniques (including, for example, precipitation and filtration). Lignin usually begins to precipitate when the pH value is lower than 11-12. Different pH values ​​can be used to precipitate lignin parts with different properties. These lignin fractions differ from each other in molecular weight distribution, such as Mw and Mn, polydispersity, hemicellulose and extract content. The molar mass of the lignin precipitated at a higher pH value is higher than the molar mass of the lignin precipitated at a lower pH value. In addition, the molecular weight distribution of the lignin part precipitated at a lower pH value is wider than the molecular weight distribution of the lignin part precipitated at a higher pH value. The precipitated lignin can be purified from inorganic impurities, hemicellulose and wood extractives by an acid washing step. Further purification can be achieved by filtration.

[0059] In this specification, the term "flash precipitated lignin" is to be understood as lignin precipitated from the black liquor by using a carbon dioxide-based acidulant (preferably carbon dioxide) in a continuous process, under the influence of an overpressure of 200-1000 kPa, reducing the pH of the black liquor stream to the precipitation level of lignin, and then suddenly releasing the pressure to precipitate the lignin. The method for producing flash precipitated lignin has been disclosed in patent application FI20106073. The residence time of the above method is less than 300 s. Flash precipitated lignin particles with a particle size of less than 2 μm form agglomerates and can be separated from the black liquor by, for example, filtration. Compared with ordinary kraft lignin, the advantage of flash precipitated lignin is that it is more reactive. The flash precipitated lignin can be purified and / or activated as required for further processing.

[0060] Lignin can be derived from an alkaline process. The alkaline process can first liquefy the biomass with a strong base and then perform a neutralization process. After the alkaline treatment, the lignin can be precipitated in a similar manner as described above.

[0061] Lignin can be derived from steam explosion, a pulping and extraction technique that can be applied to wood and other fibrous organic materials.

[0062] In this specification, unless otherwise stated, "biorefinery lignin" is understood to mean lignin that can be recovered from a refinery facility or process that converts biomass into fuels, chemicals and other materials.

[0063] In this specification, unless otherwise specified, "supercritically separated lignin" is understood to be lignin that can be recovered from biomass using supercritical fluid separation or extraction techniques. Supercritical conditions correspond to temperatures and pressures that exceed the critical point of a given substance. Under supercritical conditions, there are no separate liquid and gas phases. Supercritical water or liquid extraction is a method of using water or liquids to decompose and convert biomass into cellulosic sugars under supercritical conditions. The water or liquid acts as a solvent to extract sugars from cellulosic plant matter, while the lignin remains as solid particles.

[0064] Lignin can be derived from a hydrolysis process. Lignin derived from a hydrolysis process can be recovered from pulp or wood chemical processes.

[0065] Lignin can be derived from an organosolv process, which is a pulping technology that uses organic solvents to dissolve lignin and hemicellulose.

[0066] In one embodiment, the lignin consists of softwood kraft lignin. In one embodiment, the lignin is softwood kraft lignin. In one embodiment, the lignin is a combination of softwood lignin and hardwood lignin. In one embodiment, up to 30 wt%, or up to 25 wt%, or up to 10 wt%, or up to 5 wt% of the lignin is derived from hardwood.

[0067] The weight average molecular weight of softwood kraft lignin may be 2500-9000 Da, or 3000-8000 Da, or 3500-7000 Da. Lignin, such as kraft lignin, may have a polydispersity index of 2.9-6.0, or 3.0-5.0, or 3.2-4.5.

[0068] The weight average molecular weight can be determined using gel permeation chromatography (GPC) equipped with a UV detector (280 nm) in the following manner: Dissolve the sample in 0.1 M NaOH. Filter the sample solution with a 0.45 micron PTFE filter. Use a PSS MCX pre-column, and The column and the sulfonated styrene-divinylbenzene copolymer matrix were measured in 0.1M NaOH eluent (0.5 ml / min, T = 30 ° C). The molecular weight distribution of the samples was calculated based on Na-polystyrene sulfonate standards (6 pieces) Mw 891-65400. The values ​​of Mw (weight average molecular weight) and Mn (number average molecular weight), polydispersity index (PDI, Mw / Mn) were reported based on two parallel measurements.

[0069] The amount of alkali-insoluble matter in softwood kraft lignin may be less than 10%, or less than 5%, or less than 0.5%. The amount of alkali-insoluble matter can be determined as follows: First, place the sample in an oven at 105°C for 3 hours and determine the dry solid content of the sample. Dissolve 100 g of the sample in 277 g of a NaOH-water solution (pH 12-13) and mix at 50-60°C for 30 minutes. Filter the solution through a glass filter using a Buchner funnel. Wash the residue on the filter with 0.1 M NaOH and finally with water. Dry the filter with the residue in an oven and then weigh it. The amount of alkali-insoluble matter is then calculated as follows:

[0070] Alkali insoluble matter, % = [filter weight with residue (dry) (g) - filter weight] / [sample weight (g) × sample dry solid content (%)]

[0071] use 31 When measured by P NMR, the amount of condensed and syringyl groups in softwood kraft lignin can be less than 3.0 mmol / g, or less than 2.5 mmol / g, or less than 2.0 mmol / g. 31When measured by P NMR, the amount of aliphatic OH groups in softwood kraft lignin can be less than 3.0 mmol / g, or less than 2.5 mmol / g. 31 The amount of guaiacyl OH in the softwood kraft lignin may be at least 1.5 mmol / g when measured by P NMR.

[0072] After phosphitylation, 31 Measurements made by P NMR spectroscopy can be used to quantitatively determine functional groups (aliphatic and phenolic hydroxyl groups and carboxylic acid groups). Sample preparation and measurement were performed according to the method of Granata and Argyropoulos (Granata, A., Argyropoulos, D., J. Agric. Food Chem. 1995, 43: 1538-1544). An accurately weighed sample (~25 mg) was dissolved in N,N-dimethylformamide and mixed with pyridine and an internal standard solution (ISTD) endo-N-hydroxy-5-norbornene-2,3-dicarboximide (e-HNDI). The phosphitylation reagent (200 μl) 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane was slowly added, and finally 300 μl CDCl was added. 3 NMR measurements were performed immediately after the addition of the reagents. Spectra were measured using a spectrometer equipped with a probe optimized for broadband detection.

[0073] In one embodiment, the tannin used may be derived from any wood species. The tannin may be derived from, for example, the bark or heartwood. White oak, beech, oak, chestnut, pine, spruce and acacia species are examples of possible sources of tannin.

[0074] In one embodiment, the tannin used is derived from cork bark. The tannin can be separated from the cork bark in the debarking unit of a sawmill or pulp mill. The separation process can be combined with an ethanol extraction process, a hot water extraction process, a hot steam extraction process or a water-ethanol extraction process of the cork bark.

[0075] In one embodiment, the tannin is a condensed tannin. Condensed tannins have a high dry matter content and are therefore suitable for use in the methods disclosed in this specification. The dry matter content of the condensed tannins may vary between 40-100%, and is suitably between 60-90% or 70-80%. Tannins with such dry matter contents can be easily dispersed, thereby achieving good reactivity with other reactant components. The tannin may also be a hydrolyzable tannin.

[0076] The tannin may have a weight average molecular weight (Mw) of 1500-5000 Da, or 2000-4500 Da, or 2500-4000 Da. The tannin may have a polydispersity index of 2.8-1.0, or 2.6-1.3, or 2.4-1.5.

[0077] In one embodiment, hexamine is used to prepare the resin matrix. In one embodiment, the resin matrix comprises hexamine. The use of hexamine in preparing the resin matrix has the added benefit of providing a more robust structure, as the hexamine can be considered to act as a curing agent.

[0078] In one embodiment, the viscosity of the resin matrix is ​​50-1000 mPa·s, or 50-250 mPa·s, or 250-600 mPa·s. The viscosity can be measured at a temperature of 25° C. using a rotational viscometer (digital Brookfield viscometer LVDV-II+Pro; conical spindle). The inventors unexpectedly found that when the resin matrix has the above viscosity value (e.g., 50-250 mPa·s), one can evenly mix it with sawdust by spraying.

[0079] Providing sawdust may include mixing the sawdust with water. Providing sawdust may include mixing the sawdust with water in an amount of 5-20 wt%, or 6-10 wt%, based on the total weight of the sawdust provided.

[0080] Providing sawdust may include mixing the sawdust with an inorganic salt solution in an amount of 5-20 wt %, or 6-10 wt %, based on the total weight of the sawdust provided. Chlorides, phosphates, and nitrates are examples of salt types that may be used. Sodium sulfate (Na 2 SO 4 ) can be mentioned only as a specific example. Mixing sawdust with an inorganic salt solution can reduce the electrical properties of the sawdust, thereby making the bio-based composite material easier to handle and allowing for efficient subsequent compounding. The concentration of the inorganic salt solution can be 1-10 wt %, or 2-8 wt %, or 3-6 wt %.

[0081] In one embodiment, water or an inorganic salt solution is mixed with the sawdust before the resin matrix is ​​sprayed on the sawdust. In one embodiment, water is mixed with the sawdust before the resin matrix is ​​sprayed on the sawdust. In one embodiment, an inorganic salt solution is mixed with the sawdust before the resin matrix is ​​sprayed on the sawdust.

[0082] The inventors have surprisingly discovered that the viscosity of the resin matrix and the fact that it is sprayed onto the sawdust (rather than simply mixed together, for example) enables the production of a bio-based composite material which, in addition to being formed from bio-based materials, can also be cured by heating to form a bio-based composite without the use of an additional curing agent.

[0083] The resin matrix is ​​sprayed on the sawdust and mixed at the same time. That is, the combination of sawdust and resin matrix is ​​mixed while spraying the resin matrix. In one embodiment, mixing includes high shear mixing. Mixing, such as high shear mixing, can be carried out at a speed of 360-1000rpm, or 450-900rpm, or 650-800rpm. High shear mixing can be carried out with a (conical) mixing vessel, for example, with a central paddle rotor, which is equipped with an impact blade at the top. An example of a high shear mixer is a Cyclomix mixer. TM mixer.

[0084] The spraying of the resin matrix can be performed, for example, by means of a nozzle, so as to break up the resin matrix into droplets which are evenly sprayed or distributed on the sawdust.

[0085] Spraying may be performed at a pressure of 0.1-5 MPa, or 0.5-4 MPa, or 1-3 MPa, or 1.5-2.5 MPa.

[0086] In one embodiment, the bio-based composite material formed is a powdered material. The bio-based composite material as a powdered material can be considered similar to kinetic sand or magic sand. Therefore, the bio-based composite material is not in liquid form, nor is it like dough, but is a powdered or sand-like material.

[0087] The bio-based composites also have good raw material stability, that is, they maintain their powdery physical form when stored at room temperature.

[0088] Therefore, a bio-based composite material formed by the bio-based composite material disclosed in this specification is also disclosed.

[0089] Unless otherwise specified, compounding in this specification refers to the process of forming a bio-based composite material into a bio-based composite material of a desired shape.

[0090] In one embodiment, the visual appearance of the bio-based composite is similar to liquid wood. Liquid wood is a bioplastic composed of the following natural components: lignin, cellulose fibers, and some additives. As a thermoplastic material, it can be molded, so it is also called "liquid wood." That is, liquid wood has a similar composition, appearance, and properties to wood, but it can melt when heated and be molded like a thermoplastic material.

[0091] The bio-based composites disclosed in this specification have the added utility of being similar in visual appearance to wood materials, but having mechanical properties similar to traditional thermoset or thermoplastic materials.

[0092] The maximum bending stress of the bio-based composite may be 12-20 MPa, or 13-19 MPa, or 14-18 MPa. The maximum bending stress may be determined according to standard ISO 178:2010 (span length 48 mm, test speed 5 mm / min).

[0093] The flexural modulus of the bio-based composite may be 1400-2400 MPa, or 1500-2300 MPa, or 1600-2200 MPa. The flexural modulus may be determined according to standard ISO 178:2010 (span length 48 mm, test speed 5 mm / min).

[0094] These mechanical properties of the bio-based composites indicate that the formed bio-based composites are moldable, i.e., they can be compressed into a desired shape.

[0095] A method for producing a bio-based composite is also disclosed. The method comprises:

[0096] - Compounding the bio-based composite material disclosed in the present specification by molding the bio-based composite material while maintaining the temperature of the bio-based composite material at 80-200°C.

[0097] In one embodiment, the compounding of the bio-based composite material is performed by molding the bio-based composite material while maintaining the temperature of the bio-based composite material at 90-180°C, or 100-170°C, or 110-160°C, or 120-150°C, or 130-140°C.

[0098] In one embodiment, molding is performed by compression molding, injection molding, or extrusion.

[0099] In one embodiment, the molding is performed at a pressure of 1.2-140 MPa, 2-120 MPa, or 5-100 MPa, or 10-90 MPa, or 20-80 MPa, or 40-70 MPa, or 50-60 MPa.

[0100] In one embodiment, the molding is performed by compression molding at a pressure of 1.2-140 MPa, 2-120 MPa, or 5-100 MPa, or 10-90 MPa, or 20-80 MPa, or 40-70 MPa, or 50-60 MPa.

[0101] In one embodiment, the molding is performed by injection molding at a pressure of 1.2-140 MPa, 2-120 MPa, or 5-100 MPa, or 10-90 MPa, or 20-80 MPa, or 40-70 MPa, or 50-60 MPa.

[0102] In one embodiment, the molding is performed by extrusion at a pressure of 1.2-140 MPa (12-1400 bar), 2-120 MPa, or 5-100 MPa, or 10-90 MPa, or 20-80 MPa, or 40-70 MPa, or 50-60 MPa.

[0103] In one embodiment, molding is performed for 0.5-60 minutes, or 1-45 minutes, or 5-30 minutes.

[0104] In one embodiment, no additional curing agent is used to compound the bio-based composite material.

[0105] The bio-based composite materials disclosed in this specification have the added benefit of being formed from large amounts of sawdust. The bio-based composite materials have the added benefit of having the visual appearance of wood materials while satisfying the mechanical properties of many applications.

[0106] The methods disclosed in this specification have the additional utility of providing bio-based composite materials that can be used to replace fossil-based thermosets or thermoplastics.The bio-based composite materials can be made from 100% bio-content, and thus the bio-based composites can also be made from 100% bio-content.

[0107] Example

[0108] Embodiments of the present disclosure will now be described in detail.

[0109] The following description discloses some embodiments in such detail that those skilled in the art can utilize methods based on the present disclosure. Not all steps of the embodiments are discussed in detail, because many steps will be obvious to those skilled in the art based on the present disclosure.

[0110] Example 1 - Production of Bio-based Composite Materials

[0111] First, a resin matrix is ​​provided. The following components and their amounts are used:

[0112]

[0113] The percentages of the components used in this embodiment (by total weight, calculated as dry matter content) are as follows:

[0114]

[0115] The molar ratio of formaldehyde to "lignin and tannin" is 1.5.

[0116] First, water and NaOH I were mixed at room temperature and heating was started. When the temperature reached 70°C, lignin was added to the mixture and mixing and heating were continued for 30 minutes while maintaining the temperature at about 90°C. The temperature of the mixture was then allowed to cool to 60°C and formaldehyde was added.

[0117] The resulting mixture is mixed and heated at a temperature of about 72°C for a further 45 minutes. NaOH II is then added and mixing and heating is continued at a temperature of about 70-75°C for a further 45 minutes. NaOH III is then added and mixing and heating is continued at a temperature of about 87-89°C for a further 1 hour and 15 minutes. NaOH IV is then added followed by tannin and mixing and heating is continued at a temperature of about 90°C until the resulting mixture has a viscosity of about 170-180 mPa·s (measured at 25°C). The mixture is then cooled to 30°C.

[0118] The resulting resin matrix has the following measured properties:

[0119]

[0120]

[0121] Then sawdust was provided. 1.5 kg sawdust (particle size 125 μm) was mixed with 190 g sodium sulfate (Na 2 SO 4 The water content of the sawdust provided was 17%.

[0122] The above 1.35 kg sawdust was transferred into the cup of the high shear mixer. Then 0.15 kg of resin matrix was sprayed into the cup using a 1.2 mm nozzle at a pressure of 5 bar while mixing the sawdust in the high shear mixer at 750 rpm. Mixing was continued until a homogeneous mixture was achieved.

[0123] Example 2 - Production of Bio-based Composite Materials

[0124] In this example a bio-based composite material was produced.

[0125] First, a resin matrix is ​​provided. The following components and their amounts are used:

[0126]

[0127] The percentages of the components used in this embodiment (by total weight, calculated as dry matter content) are as follows:

[0128]

[0129] The molar ratio of formaldehyde to "lignin and tannin" is 1.5.

[0130] First, water and NaOH I were mixed at room temperature and heating was started. When the temperature reached 70°C, lignin was added to the mixture and mixing and heating were continued for 30 minutes while maintaining the temperature at about 90°C. The temperature of the mixture was then allowed to cool to 60°C and formaldehyde was added.

[0131] The resulting mixture was mixed and heated at a temperature of about 72°C for a further 45 minutes. NaOH II was then added and mixing and heating was continued at a temperature of about 70-75°C for a further 45 minutes. NaOH III was then added and mixing and heating was continued at a temperature of about 87-89°C for a further 1 hour and 15 minutes. NaOH IV was then added followed by tannin and mixing and heating was continued at a temperature of about 90°C until the resulting mixture had a viscosity of about 170-180 mPa·s (measured at 25°C). The mixture was then cooled to 30°C. 0.4 kg of hexamine (100%) was then added to the mixture.

[0132] The resulting resin matrix has the following measured properties:

[0133]

[0134] Then sawdust was provided. 1.5 kg sawdust (particle size 125 μm) was mixed with 190 g sodium sulfate (Na 2 SO 4 The water content of the sawdust provided was 17%.

[0135] Five samples with different ratios of sawdust and resin matrix were prepared. The sawdust was placed in the cup of a high shear mixer. A certain amount of resin matrix was then sprayed into the cup using a 1.2 mm nozzle at a pressure of 5 bar while mixing the sawdust in a high shear mixer at 750 rpm. Mixing was continued until a homogeneous mixture was achieved. Table 1 shows the samples prepared:

[0136] Table 1. Prepared bio-based composite samples

[0137]

[0138] Example 3 - Production of Bio-Based Composites

[0139] In this example, bio-based composites were produced using samples 1, 4 and 5 prepared in Example 2. Each sample was compounded by compression molding it at a pressure of 3.9 MPa for 20 minutes in a temperature chamber at 120°C. During this period, the temperature of the sample reached 120°C.

[0140] The maximum bending stress and bending modulus of the prepared composite were tested. The results are shown in Table 2.

[0141] Table 2. Maximum flexural stress and flexural modulus of the prepared bio-based composites

[0142]

[0143] From the above results, it can be seen that the mechanical properties of the prepared bio-based composites meet the standards required in many applications in which the prepared bio-based composites can be used.

[0144] It is obvious to a person skilled in the art that, as technology develops, the basic idea can be implemented in various ways. Therefore, the implementations are not limited to the above-described embodiments; instead, they may vary within the scope of the claims.

[0145] The embodiments described above can be used in any combination with each other. Several embodiments can be combined to form further embodiments. The bio-based composite materials, bio-based composites and methods disclosed herein may include at least one of the aforementioned embodiments. It will be understood that the above benefits and advantages may relate to one embodiment, or may relate to several embodiments. The embodiments of the present invention are not limited to embodiments that can solve any or all of the problems described, nor are they limited to embodiments that have any or all of the benefits and advantages described. It should be further understood that the "one" item mentioned refers to one or more items therein. The term "comprising" used in this specification includes the features or behaviors thereafter, without excluding the presence of one or more other features or behaviors.

Claims

1. A bio-based composite material comprising sawdust and a resin matrix based on lignin and tannin, wherein: The bio-based composite material comprises sawdust in an amount of 25-90 wt %, based on the total weight of the bio-based composite material.

2. The bio-based composite material according to claim 1, wherein: The bio-based composite material is formed from a resin matrix that is sprayed onto sawdust while mixing to bond the resin matrix to the sawdust.

3. A bio-based composite material as claimed in any one of the preceding claims, wherein: The resin matrix is ​​formed by polymerizing lignin and tannin with a cross-linking agent.

4. A bio-based composite material as claimed in any one of the preceding claims, wherein No compounds selected from the group consisting of phenols are used to form the resin matrix.

5. A bio-based composite material as claimed in any one of the preceding claims, wherein: The average particle size of the sawdust is 0.001-1 mm, or 0.01-0.8 mm, or 0.05-0.6 mm, or 0.1-0.4 mm, or 0.15-0.2 mm.

6. A bio-based composite material as claimed in any one of the preceding claims, wherein The bio-based composite material comprises sawdust in a total amount of 30-88 wt%, or 40-86 wt%, or 50-84 wt%, or 60-82 wt%, or 65-80 wt%, or 70-78 wt%, based on the total weight of the bio-based composite material.

7. A bio-based composite material as claimed in any one of the preceding claims, wherein Based on the total weight of the bio-based composite material, the bio-based composite material comprises a total amount of 10-75 wt%, or 12-70 wt%, or 14-60 wt%, or 16-50 wt%, or 18-40 wt%, or 20-35 wt%, or 22-30 wt% of the resin matrix.

8. A method for producing a bio-based composite material, wherein: The method comprises: - providing a resin matrix, wherein the resin matrix is ​​polymerized from lignin and tannin with a cross-linking agent to form a resin matrix having a viscosity value of 50-1000 mPa·s; - providing sawdust with a dry matter content of 50-100%; - spraying the resin matrix onto the sawdust and mixing simultaneously to bond the resin matrix to the sawdust, To form the bio-based composite material, wherein the composite material contains 25-90 weight % of sawdust in total based on the total weight of the composite material.

9. The method of claim 8, wherein: The viscosity of the resin matrix is ​​50-250 mPa·s, or 250-600 mPa·s.

10. The method according to claim 8 or 9, wherein: Providing sawdust includes mixing the sawdust with an inorganic salt solution, wherein the amount of the inorganic salt solution is 5-20 wt %, or 6-10 wt %, based on the total weight of the provided sawdust.

11. The method according to any one of claims 8 to 10, wherein: The sawdust provided has a dry matter content of 55-95%, or 60-92%, 70-90%, or 80-85%.

12. A bio-based composite material formed by compounding the bio-based composite material according to any one of claims 1 to 7.

13. The bio-based composite of claim 12, wherein: The visual appearance of the bio-based composite is liquid wood-like.

14. The bio-based composite according to claim 12 or 13, wherein: The maximum bending stress of the bio-based composite is 12-20 MPa, or 13-19 MPa, or 14-18 MPa.

15. The bio-based composite according to any one of claims 12 to 14, wherein The flexural modulus of the bio-based composite is 1400-2400 MPa, or 1500-2300 MPa, or 1600-2200 MPa.

16. A method for producing a bio-based composite, wherein: The method comprises: - Compounding the bio-based composite material according to any one of claims 1 to 8 by molding the bio-based composite material while maintaining the temperature of the bio-based composite material at 80-200°C.

17. The method of claim 16, wherein: No additional curing agent is used to compound the bio-based composites.

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