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WO2025215302A1 - Lignine modifiée en tant qu'agent ignifuge dans des produits thermoplastiques - Google Patents

Lignine modifiée en tant qu'agent ignifuge dans des produits thermoplastiques

Info

Publication number
WO2025215302A1
WO2025215302A1 PCT/FI2025/050175 FI2025050175W WO2025215302A1 WO 2025215302 A1 WO2025215302 A1 WO 2025215302A1 FI 2025050175 W FI2025050175 W FI 2025050175W WO 2025215302 A1 WO2025215302 A1 WO 2025215302A1
Authority
WO
WIPO (PCT)
Prior art keywords
lignin
modified
thermoplastic
weight
acid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/FI2025/050175
Other languages
English (en)
Inventor
Kirsi Immonen
Petri Widsten
Amelie TRIBOT
Chamseddine GUIZANI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VTT Technical Research Centre of Finland Ltd
Original Assignee
VTT Technical Research Centre of Finland Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by VTT Technical Research Centre of Finland Ltd filed Critical VTT Technical Research Centre of Finland Ltd
Publication of WO2025215302A1 publication Critical patent/WO2025215302A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K21/00—Fireproofing materials
    • C09K21/14—Macromolecular materials
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C59/00—Compounds having carboxyl groups bound to acyclic carbon atoms and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
    • C07C59/235—Saturated compounds containing more than one carboxyl group
    • C07C59/245—Saturated compounds containing more than one carboxyl group containing hydroxy or O-metal groups
    • C07C59/265—Citric acid
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07G—COMPOUNDS OF UNKNOWN CONSTITUTION
    • C07G1/00—Lignin; Lignin derivatives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones

Definitions

  • the present invention relates to a modified lignin material that is based on lignin, to a method for modifying such a lignin, as well as to the use of said modified lignin material as a fire retardant in thermoplastic products.
  • bioplastics are finding their way into various areas, such as covers for electronics, construction and transportation. Those are all also areas where fire retardancy is one of the main material requirements.
  • Thermoplastic polyester-type materials are all flammable.
  • Commercial fire retardants, such as phosphate-based materials can be used to alleviate their flammability, but the high loading of phosphate reagent (>15% by weight) that is typically needed for proper fire protection reduces the strength properties of the material.
  • lignin to replace various commercial additives is also under active research due to its versatility and its renewability.
  • Lignin could also be a suitable renewable-based fire retardant, but when introduced as such into thermoplastic materials, it can deteriorate the mechanical properties of the material.
  • lignin is not a very effective flame retardant, some modification of the lignin (phosphorus and/or nitrogen-modification) is required.
  • Costes et al. suggests using blends of organosolv or kraft lignin with phytic acid.
  • the phytic acid improved the fire behaviour of the polylactide substrates to which the blend was added, it negatively affected other thermo-mechanical properties.
  • phytic acid is toxic, expensive, and not desirable for use as a reagent.
  • the high cost of raw materials for other bio-based flame retardants such as chitosan and tannic acid is also a problem.
  • a renewable-based modified lignin material there is provided a renewable-based modified lignin material.
  • a modified lignin material that is suitable for use as a fire retardant.
  • the present invention thus relates to a modified lignin material, based on lignin, which contains citric acid in an acid: lignin ratio of 1 : 1-1 : 10, as well as to the use of said material as a fire retardant in thermoplastic products, such as bioplastics.
  • thermoplastic products are, for example, products used in transportation, such as in ships or motor vehicles, products used as covers for electronic equipment or for injection molded or extruded items used e.g. in public buildings.
  • the invention relates to a method for modifying a lignin by mixing an aqueous solution of citric acid and lignin in an acid: lignin ratio of 1 : 1-1 : 10, and by treating the mixture at 130-220°C.
  • the citric acid will esterify with the lignin in the aqueous mixture, while still leaving free carboxylic acid groups in its structure, for example to take part in binding to a thermoplastic material or ligno-cellulosic material, in biocomposites, e.g. via free hydroxyl groups.
  • the invention is based on test carried out on different lignin materials, demonstrating that such lignins from different modification processes have different reactivities during combustion. These tests confirmed the flame retardancy of these differently modified lignin materials. The flame retardancy depends on several factors, including the lignin content, the structural and chemical properties of the lignin, the dispersion and compatibility with the polymer, and the thermal degradation of the lignin during melt processing. Alkali lignin was found to perform best in the fire retardants of the invention, but also organosolv lignin can be used.
  • the modified lignin of the invention is from renewable origin. It has been found herein to have an efficiency comparable to that of a commercial fire retardant, while being used at lower loadings.
  • the efficacy is improved by the modification described herein, as neat lignin in a thermoplastic material has a lower efficacy as a fire retardant. Due to the modification, the behaviour of the lignin-based fire retardant is also more predictable, and it is also more capable of maintaining the strength properties of the thermoplastic compared to neat lignin and commercial fire retardant.
  • the modified lignin has an increased potential to form covalent bonds with certain thermoplastics, e.g.
  • thermoplastic polymer ones containing hydroxyl groups, such as hydroxy functional polyesters, modified thermoplastic starches, or cellulosic or lignocellulosic materials, e.g. fillers, thus particularly efficiently preventing migration of the fire-retardant from the thermoplastic polymer.
  • hydroxyl groups such as hydroxy functional polyesters, modified thermoplastic starches, or cellulosic or lignocellulosic materials, e.g. fillers
  • FIGURE 1 shows the total heat release rate (HRR) of analysed PLA samples containing the modified lignin material of the invention.
  • FIGURE 2 shows peak of HRR (pHRR) values for analysed PLA samples containing the modified lignin material of the invention, the left column of each sample indicating the pHRR values (W/g), and the right column of each sample indicating the temperatures (°C) at which the pHRR values were reached.
  • FIGURE 3 shows the tensile strengths of analysed PLA samples containing the modified lignin material of the invention.
  • FIGURE 4 shows the impact strengths of analysed PLA samples containing the modified lignin material of the invention.
  • FIGURE 5 shows the limiting oxygen index (LOI) results for HDPE compounds containing 20% microcellulose (MC) or flax fibres in combination with commercial APP flame retardant and VTT citric acid modified lignin (CAL).
  • LOI limiting oxygen index
  • FIGURE 6 shows the tensile strength results for HDPE compounds containing 20% microcellulose (MC) or flax fibres in combination with commercial APP flame retardant and VTT citric acid modified lignin (CAL).
  • MC microcellulose
  • CAL citric acid modified lignin
  • FIGURE 7 shows the Charpy impact strength results for HDPE compounds containing 20% microcellulose (MC) or flax fibres in combination with commercial APP flame retardant and VTT citric acid modified lignin (CAL).
  • MC microcellulose
  • CAL citric acid modified lignin
  • alkali lignin is intended to encompass any lignin that is dissolved in an alkaline cooking process of woody material, such as kraft or soda cooking.
  • thermoplastic is intended to cover any plastic polymer material that becomes pliable or moldable at an elevated temperature and solidifies upon cooling.
  • thermoplastics are well known, and include acrylics, acrylonitrile butadiene styrene (ABS), cellulose acetate (CA), celluloseacetate butyrate (CAB), cellulose acetate propionate (CAP), nylon, polylactic acid (PLA), polyhydroxybutyrate (PHB), polyhydroxybutyrate valerate (PHBV), polyhydroxybutyrate hexanoate (PHBH), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polyglycolic acid (PGA), polyethylene furanoate (PEF), polycaprolactone (PCL), polybenzimidazole (PBI), polycarbonate (PC), polyether sulfone (PES), polyoxymethylene (POM), polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene (PE) (AB
  • bioplastic or “bioplastic compounds”, in turn, comprises polymers produced from natural or renewable sources, in the present context particularly bio-thermoplastic polymers. They can be biodegradable or non- biodegradable, but are preferably biodegradable.
  • the present invention thus relates to a modified lignin material, based on lignin, which contains citric acid at an acid: lignin ratio of 1 :1-1 :10 attached to the lignin surface via ester bonds.
  • the lignin can be any alkali lignin, preferably a lignin material obtained from a kraft or soda process, or organosolv lignin.
  • the alkali lignin materials are preferred.
  • Citric acid has been found to be a particularly advantageous fire retardant due to its non-toxic and innocuous character and low cost.
  • the hydroxyl groups of the lignin have reacted with the carboxyl groups of the citric acid, and formed ester bonds.
  • the citric acid: lignin ratio is 1 :2 - 1 :7, more preferably about 1 :4.
  • the modified lignin material consists of organic components.
  • modified lignin material described herein can be used for example as a fire retardant in thermoplastic products.
  • Such a modified lignin material can be prepared for example by a method wherein citric acid is combined with lignin in an aqueous mixture at an acid: lignin weight ratio of 1 : 1-1 : 10, by further mixing the components, and by heat treating the mixture at 130-220°C to cause a partial esterification of the lignin surface.
  • a preferred acid: lignin ratio is 1 :2 - 1 :7, the ratio most suitably being about 1 :4.
  • the modified lignin material can be prepared for example by mixing the lignin solution containing the citric acid, and heat treating the mixture at a temperature of 140-180 °C, preferably at a temperature of about 160 °C.
  • the increased temperature is maintained for at least 10 minutes, preferably 1-10 h, most suitably 2-6 h.
  • the treatment time depends on the used temperature, as a higher temperature can be combined with a shorter time.
  • the mixing can be carried out for example using a batch reactor with mixer/homogenizer or compounder.
  • the method described herein is carried out in an aqueous environment, without organic solvents.
  • the dry material content can be high, preferably 40 - 95% by weight, more preferably 50 - 90% by weight, and most suitably 70 - 85% by weight.
  • the preparation is followed by a purification of the modified lignin material, typically by removing any unbound citric acid by washing the solid material with water until a near neutral pH of the filtrate is achieved, typically a pH of 6-7.
  • the wet modified lignin product can also be dried to a powder.
  • modified lignin material described herein can be used to prepare a modified thermoplastic product using typical plastic melt processing methods such as compounding, injection or extrusion, to be formed of a thermoplastic material or compound containing said modified lignin and optionally organic filler material.
  • the thermoplastic material can be any natural or renewable thermoplastic material, typically a bioplastic material.
  • bioplastic materials are the durable bioplastics bio-polyethylene (bio-PE), bio-polypropylene (bio-PP), bio-polyethylene terephthalate (bio-PET), particularly bio-PP.
  • Other examples of useful thermoplastics are the biodegradable polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoates (PHAs) and thermoplastic starch, preferred alternatives being the biodegradable thermoplastics, more preferably the PLA or the thermoplastic starch, and a particularly preferred material being PLA.
  • modified lignin in the thermoplastic material can be lower than in commercial products, while still providing sufficient fire retardancy.
  • the modified lignin is present in the thermoplastic material at ⁇ 30% by weight, preferably 10- 28% by weight, more preferably 15-25% by weight, and most suitably about 20% by weight.
  • the modified thermoplastic product consists of organic agents and organic materials.
  • conventional organic fillers can be mixed in the compound, such as fibre reinforcement agents, preferably selected from fibres made of glass, carbon, paper, wood or boron.
  • Citric acid (CA, 1 part by weight) and alkali lignin (4 parts) were combined with water (1 part), mixed thoroughly and treated at an elevated temperature of 160 °C for 4 hours.
  • the obtained heat-treated CA-modified lignin material (CA-L) was washed with water to near neutral pH (>6), filtered and dried.
  • the obtained modified lignin material (CA-L) was introduced to PLA at a loading of 20%. It was compared to reference samples containing neat alkali lignin (AL) and a commercial phosphate-based material (Exo lit 423, ammonium polyphosphate (APP), Clariant).
  • MCC Micro-combustion calorimetric
  • CA-E provided similar total heat release and 2% lower peak heat release rate values than APP. It also provided 1.1% more residues. Compared to AE the total heat release was 7% lower for the CA-E, while the amount of residues was 1% higher. However, the AE caused a collapse in tensile strength from 62 MPa to 25 MPa, whereby it is not an advantageous fire retardant in PEA. APP reduced the strength of the PLA to 43 MPa. With CA-L the tensile strength remained as high as 49 MPa.
  • the material With the CA-L of the invention, the material also maintained its strength properties to an acceptable degree.
  • Test materials were obtained from high density polyethylene (HDPE) compounds, which are known to be highly flammable, and mixing this HDPE with microcellulose (MC) and flax in combination with commercial ammoniumpolyphosphate (APP) flame retardant or VTT citric acid modified lignin (CAL), in a 20w-% content (a 1/5 ratio).
  • HDPE high density polyethylene
  • MC microcellulose
  • APP ammoniumpolyphosphate
  • CAL citric acid modified lignin
  • CA-lignin with MC enables to reduce flammability only slightly or not significantly, but makes the material more slowly burning, i.e. having a smaller burning distance. This, in turn, causes a charring effect.
  • CA-lignin with flax showed a slightly improved LOI (from 19 to 19.7) and smaller burning distance, i.e. with the desired charring effect.
  • the modified lignin material of the invention can be used as an additive in a wide range of materials, particularly as a fire retardant, for example in thermoplastics.
  • This modified lignin has been found to have an efficacy as a fire retardant comparable to that of commercial fire retardants, while it can be used at lower loadings. Due to the modification, the alkali lignin -based fire retardant also maintains the strength properties of the thermoplastic material to a higher degree than the commercial fire retardants applied at a similar loading.
  • PHAs polyhydroxyalkanoates pHRR peak heat release rate

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Compounds Of Unknown Constitution (AREA)

Abstract

Selon la présente invention, il est fourni un matériau de lignine modifiée qui est basé sur une lignine qui a été modifiée à l'aide d'acide citrique. En outre, un procédé de modification d'une telle lignine est fourni, ainsi que l'utilisation de ladite lignine modifiée en tant qu'agent ignifuge dans des produits thermoplastiques.
PCT/FI2025/050175 2024-04-08 2025-04-08 Lignine modifiée en tant qu'agent ignifuge dans des produits thermoplastiques Pending WO2025215302A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20245436A FI20245436A1 (en) 2024-04-08 2024-04-08 Modified lignin as a fire retardant in thermoplastic products
FI20245436 2024-04-08

Publications (1)

Publication Number Publication Date
WO2025215302A1 true WO2025215302A1 (fr) 2025-10-16

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Application Number Title Priority Date Filing Date
PCT/FI2025/050175 Pending WO2025215302A1 (fr) 2024-04-08 2025-04-08 Lignine modifiée en tant qu'agent ignifuge dans des produits thermoplastiques

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Country Link
FI (1) FI20245436A1 (fr)
WO (1) WO2025215302A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10057910A1 (de) * 2000-11-21 2002-06-06 Advanced Recovery Technologies Verfahren zur Derivatisierung und Veredelung von technischem Lignin, veredeltes technisches Lignin und Verwendung des derivatisierten Lignins
WO2015094099A1 (fr) * 2013-12-16 2015-06-25 Ren Fuel K2B Ab Composition comprenant des esters de lignine et d'huile ou des acides gras

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5484896A (en) * 1994-03-24 1996-01-16 The Procter & Gamble Company Esterified high lignin content cellulosic fibers
CN105638757A (zh) * 2016-01-19 2016-06-08 黄伟洪 一种服装干燥防霉杀菌剂
WO2020036638A1 (fr) * 2018-08-13 2020-02-20 Wisys Technology Foundation, Inc. Thermoplastique composite de poly(acide lactique) et de lignine pour impression 3d
CN110527524A (zh) * 2019-07-31 2019-12-03 中国林业科学研究院林产化学工业研究所 一种木质素磺酸盐基三源一体阻燃剂的制备方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10057910A1 (de) * 2000-11-21 2002-06-06 Advanced Recovery Technologies Verfahren zur Derivatisierung und Veredelung von technischem Lignin, veredeltes technisches Lignin und Verwendung des derivatisierten Lignins
WO2015094099A1 (fr) * 2013-12-16 2015-06-25 Ren Fuel K2B Ab Composition comprenant des esters de lignine et d'huile ou des acides gras

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
CARRETIER VALENTIN ET AL: "Influence of Sepiolite and Lignin as Potential Synergists on Flame Retardant Systems in Polylactide (PLA) and Polyurethane Elastomer (PUE)", MATERIALS, vol. 13, no. 11, 28 May 2020 (2020-05-28), pages 2450, XP093082255, DOI: 10.3390/ma13112450 *
CHOLLET BENJAMIN ET AL: "Lignin Nanoparticles as A Promising Way for Enhancing Lignin Flame Retardant Effect in Polylactide", MATERIALS, vol. 12, no. 13, 2 July 2019 (2019-07-02), pages 2132, XP093283430, ISSN: 1996-1944, DOI: 10.3390/ma12132132 *
CHRISTIANE LAINE ET AL: "Lignin and lignin derivatives as components in biobased hot melt adhesives", JOURNAL OF APPLIED POLYMER SCIENCE, vol. 136, no. 38, 10 October 2019 (2019-10-10), New York, pages 47983, XP055711765, ISSN: 0021-8995, DOI: 10.1002/app.47983 *
EUROPEAN POLYMER JOURNAL, vol. 94, 2017, pages 270 - 285
SANJAM CHANDNA ET AL: "Lignin Upconversion by Functionalization and Network Formation", ANGEWANDTE CHEMIE, VERLAG CHEMIE, HOBOKEN, USA, vol. 63, no. 8, 29 November 2023 (2023-11-29), pages n/a, XP072585116, ISSN: 1433-7851, DOI: 10.1002/ANIE.202313945 *

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