Resin composition and method for producing same

Abstract

Provided is a resin composition that is excellent in manufacturing processability, in which lignin, which is plant-derived biomass, is effectively utilized and modified lignin, which is a modified product of lignin, is dispersed or dissolved in the resin in a good state. [Solution] The resin composition contains modified lignin and a resin, wherein the modified lignin is alkyl-etherified lignin in which at least a portion of the aromatic hydroxyl groups of the lignin are etherified with at least one alkyl group selected from the group consisting of linear alkyl groups having 4 to 22 carbon atoms, branched alkyl groups having 4 to 22 carbon atoms, cycloalkyl groups having 4 to 22 carbon atoms, and arylalkyl groups having 4 to 22 carbon atoms, the modified lignin has a sulfur atom content of less than 0.2 mass%, the lignin content of the modified lignin is 50 to 90 mass% based on the total of the lignin and the alkyl groups, and the modified lignin has a number average molecular weight of 800 to 10,000.

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a method for producing the same. [Background technology]

[0002] In recent years, with a view to achieving carbon dioxide reduction and a circular economy, there has been active research and development into technologies that utilize biomass materials, particularly wood, a plant-derived material. Biomass materials include cellulose, lignocellulose, and lignin. Among these, lignin is known to be one of the most abundant substances on Earth, with an annual production of 80 million tons. However, due to issues such as coloring, low solubility, and ease of handling, the only industrial application of lignin is sulfonation and application as a dispersant for cement, while the majority of lignin is incinerated and used as fuel energy.

[0003] In recent years, the effective utilization of lignin for industrial and commercial applications has been investigated. Specifically, the modification of lignin and its application to thermoplastic resins and thermosetting resins have been investigated. For example, phenol-modified lignin obtained by using lignin as a raw material for phenolic resins has been proposed (Patent Documents 1 and 2). Polyalkylene glycol-modified lignin obtained by reacting lignin with polyethylene glycol has also been proposed (Patent Documents 3 and 4). Furthermore, vinyl polymer-modified lignin obtained by adding radically polymerizable polymerization initiating groups to lignin and then grafting vinyl monomers from the polymerization initiating groups by living radical polymerization has been proposed (Non-Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-224288 [Patent Document 2] Patent No. 7405317 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-108392 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-121321 [Non-patent literature]

[0005] [Non-Patent Document 1] International Journal of Biological Macromolecules Volume207,15 May 2022,Pages522-530 Summary of the Invention [Problem to be solved by the invention]

[0006] However, phenol-modified lignin is thermosetting, which limits its applications, and polyalkylene glycol-modified lignin is soft and the introduced polyalkylene glycol chains have low heat resistance, making it difficult to produce articles with satisfactory physical properties.

[0007] Polyvinyl polymer-modified lignin is expected to improve the heat resistance and solvent solubility of the polyvinyl polymer to which it is applied. However, because vinyl monomers are grafted by living radical polymerization, the resulting modified lignin is prone to contain residual polymerization catalysts and other components, and the polymerization rate is often insufficient, resulting in residual monomers. This requires purification, and the formulation and polymerization conditions must be carefully considered depending on the monomer to be polymerized, making the manufacturing process less versatile.

[0008] The present invention has been made in consideration of the problems of the prior art, and an object of the present invention is to provide a resin composition that effectively utilizes lignin, which is a plant-derived biomass, and in which modified lignin, which is a modified product of lignin, is dispersed or dissolved in the resin in a good state, and that has excellent manufacturing processability. Another object of the present invention is to provide a simple method for manufacturing this resin composition. [Means for solving the problem]

[0009] That is, according to the present invention, there is provided the following resin composition. [1] A modified lignin and a resin are contained, and the modified lignin is such that at least a part of the aromatic hydroxyl groups of the lignin is replaced with a linear alkyl group having 4 to 22 carbon atoms, a branched alkyl group having 4 to 22 carbon atoms, a cycloalkyl group having 4 to 22 carbon atoms, or a hydroxyl group having 4 to 22 carbon atoms. 7 A resin composition comprising an alkyl-etherified lignin etherified with at least one alkyl group selected from the group consisting of aryl alkyl groups of 1 to 22, wherein the modified lignin has a sulfur atom content of less than 0.2 mass%, a content of a portion derived from the lignin constituting the modified lignin is 50 to 90 mass%, and a number average molecular weight of the modified lignin is 800 to 10,000. [2] The resin composition according to [1], wherein the content of the modified lignin is 1 to 33.4 mass % based on the total mass of the modified lignin and the resin. [3] The resin composition according to [1] or [2], wherein the resin is a thermoplastic resin. [4] The resin composition according to any one of [1] to [3], wherein the resin is an olefin-based polymer, and the alkyl group is a linear alkyl group having 8 to 22 carbon atoms or a branched alkyl group having 8 to 22 carbon atoms. [5] The resin composition according to [4], wherein the alkyl group is an octadecyl group.

[0010] Furthermore, according to the present invention, there is provided a method for producing a resin composition as shown below. [6] A method for producing the resin composition according to any one of [1] to [5] above, comprising the steps of: reacting an alkali metal salt with aromatic hydroxyl groups of lignin having a sulfur atom content of less than 0.5% by mass to form an alkoxide; and then reacting an alkyl halide to obtain a modified lignin that is an alkyl-etherified lignin; wherein the alkyl halide is selected from the group consisting of linear alkyl halides having 4 to 22 carbon atoms, branched alkyl halides having 4 to 22 carbon atoms, cycloalkyl halides having 4 to 22 carbon atoms, and alkyl halides having 4 to 22 carbon atoms. 7A method for producing a resin composition comprising at least one selected from the group consisting of aryl alkyl halides of 1 to 22. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a resin composition having excellent manufacturing processability, in which lignin, which is a plant-derived biomass, is effectively utilized and modified lignin, which is a modified product of lignin, is dispersed or dissolved in a resin in a good state. Furthermore, according to the present invention, it is possible to provide a simple method for manufacturing this resin composition. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an NMR chart of modified lignin HR-1 obtained in Synthesis Example 1. [Figure 2] 1 is an IR chart of modified lignin HR-1 obtained in Synthesis Example 1. [Figure 3] 1 is a photomicrograph (50x magnification) showing the microstructure of a sheet produced using resin composition J-1 produced in Example 1. [Figure 4] 1 is a photomicrograph (50x magnification) showing the microstructure of a sheet produced using the resin composition HJ-1 produced in Comparative Example 1. [Figure 5] 1 is a photomicrograph (50x magnification) showing the microstructure of a sheet produced using the resin composition HJ-2 produced in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Resin composition> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the resin composition of the present invention is a composition containing modified lignin and a resin. The modified lignin is a composition in which at least a part of the aromatic hydroxyl groups of the lignin is replaced with a linear alkyl group having 4 to 22 carbon atoms, a branched alkyl group having 4 to 22 carbon atoms, a cycloalkyl group having 4 to 22 carbon atoms, or a hydroxyl group having 4 to 22 carbon atoms. 7The alkyl-etherified lignin is etherified with at least one alkyl group selected from the group consisting of aryl alkyl groups of 1 to 22. The sulfur atom content of the modified lignin is less than 0.2% by mass, and the content of the lignin-derived portion constituting the modified lignin is 50 to 90% by mass. The number average molecular weight of the modified lignin is 800 to 10,000.

[0014] The resin composition of this embodiment is a composition in which modified lignin, a plant-derived biomass, has been well dispersed or dissolved to improve its resin properties due to its polyaromaticity. Lignin itself is a naturally occurring product that is poorly soluble and difficult to disperse, making it difficult to incorporate into thermoplastic resins and the like. Attempting to disperse or dissolve lignin in a thermoplastic resin results in the formation of lignin particles. In contrast, specific modified lignins can be well dispersed or dissolved in resins such as thermoplastic resins. Therefore, the use of specific modified lignins not only allows for the incorporation of a large amount of lignin into the resin, but is also expected to improve the transparency of the material.

[0015] The resin composition of this embodiment effectively utilizes lignin, an unused natural material, and therefore contributes to environmental friendliness, carbon neutrality, prevention of global warming, and waste reduction. Furthermore, blending lignin containing many aromatic rings into a resin can improve the physical properties of the resin, and is expected to provide articles with UV absorption, antibacterial properties, antioxidant properties, heat resistance, and other benefits. Furthermore, since modified lignin can also function as a lignin-derived brown colorant, weight reduction can be achieved compared to when brown inorganic pigments are used. Furthermore, because lignin is biodegradable, the use of the resin composition of this embodiment is expected to help solve the problem of waste plastics.

[0016] When kraft lignin, organosolv lignin, sulfonated lignin, and the like, which contain a large amount of sulfur (S), are thermally processed, a large amount of unpleasant sulfur odor is likely to be generated. Therefore, thermal processing of lignins containing a large amount of sulfur is difficult, and the odor tends to remain in the resulting article. In contrast, the modified lignin used in the resin composition of this embodiment has a low sulfur atom content, so it generates almost no odor during thermal processing, and the articles produced also have almost no odor.

[0017] (lignin) The modified lignin used in the resin composition of this embodiment is produced by modifying lignin obtained from plants or wood through decomposition, etc. Examples of raw materials for lignin include wood and plants such as conifers such as cedar, pine, and cypress; broad-leaved trees such as beech, birch, oak, and zelkova; and grasses such as rice, wheat, corn, and sugarcane.

[0018] The method for producing lignin is not particularly limited, and lignin produced by paper production, pulp production, bioethanol production, cellulolytic enzyme-based processes, etc. can be used. Lignin obtained by the above processes is pure lignin extracted as the target product, or a by-product of the above processes. Examples of lignin obtained as a by-product include kraft lignin, lignosulfonic acid, soda lignin, organosolv lignin, explosive lignin, and lignophenol. The modified lignin contained in the resin composition of this embodiment is obtained by modifying lignin having a sulfur atom content of less than 0.5% by mass, preferably less than 0.2% by mass. It is preferable to use lignin obtained by a production process such as a bioethanol production process or a cellulolytic enzyme method. The lignin may contain impurities such as polysaccharides and inorganic substances.

[0019] Lignin is a naturally occurring material with a complex chemical structure. Its complex structure includes aromatic rings, phenolic hydroxyl groups, aliphatic hydroxyl groups, aldehydes, ether groups, ketone groups, and unsaturated bonds, making it difficult to determine its chemical structure. A typical example of the structure of lignin is shown below.

[0020] TIFF0007756827000001.tif155170

[0021] Lignin typically contains aromatic hydroxyl groups (phenolic hydroxyl groups) in its molecular structure. The presence or absence of phenolic hydroxyl groups can be confirmed by infrared spectroscopy, nuclear magnetic resonance analysis, and color reaction. The amount of phenolic hydroxyl groups can also be quantified by titration. Examples of titration methods include acetic anhydride-pyridine titration, titration using Folin-Ciocalteu reagent, and calculations based on IR or NMR peaks. However, because lignin is highly colored and its structure is complex and undetermined, it is difficult to accurately measure the amount of phenolic hydroxyl groups. In the present invention, IR or NMR analysis is used to confirm that the lignin contains sufficient phenolic hydroxyl groups. In other words, the amount of phenolic hydroxyl groups in the lignin used is not particularly limited, and any lignin containing one or more phenolic hydroxyl groups in its molecule can be used.

[0022] Lignin has a complex structure, and even when dissolved in a solution, it does not form a random coil like a linear polymer, but rather has a complex three-dimensional structure, making it difficult to accurately measure its molecular weight. In the present invention, a solution prepared by dissolving lignin and modified lignin in a solvent such as tetrahydrofuran (THF) or dimethylformamide (DMF) is used, and the number-average molecular weight (Mn) of the lignin and modified lignin measured by gel permeation chromatography (GPC) in terms of polystyrene is taken as the molecular weight of the lignin and modified lignin. The number-average molecular weight (Mn) of lignin is preferably 500 to 9,000, and more preferably 800 to 8,000. If the Mn of lignin is less than 500, the molecular weight is too small, which may make it difficult to achieve the effects of using lignin. On the other hand, if the Mn of lignin exceeds 9,000, the Mn of the modified lignin also increases, which may lead to problems such as an increase in viscosity, a decrease in compatibility with the resin used as a dispersion medium, or a tendency to gel during mixing. The molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) of lignin is not particularly limited, and may be, for example, 1.5 to 100. In this specification, the "number average molecular weight (Mn)" is a polystyrene-equivalent value measured by GPC using THF as a developing solvent. Examples of detectors used in GPC measurements include a differential refractometer (RI detector) and an ultraviolet detector (UV detector, measurement wavelength 254 nm). A UV detector was used in the examples described below.

[0023] (modified lignin) Modified lignin is an alkyl-etherified lignin in which at least a portion of the aromatic hydroxyl groups of the lignin are etherified with specific alkyl groups (alkyl-etherification). By bonding many alkyl groups to the molecular backbone of lignin, the lignin is endowed with properties such as thermoplasticity and solvent solubility, and its compatibility with resins can be improved.

[0024] The alkyl group may be a linear alkyl group having 4 to 22 carbon atoms, a branched alkyl group having 4 to 22 carbon atoms, a cycloalkyl group having 4 to 22 carbon atoms, or a 7The straight-chain alkyl group having 4 to 22 carbon atoms is at least one selected from the group consisting of arylalkyl groups having 4 to 22 carbon atoms. Examples of the straight-chain alkyl group having 4 to 22 carbon atoms include a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group, a heneicosyl group, and a docosyl group.

[0025] Examples of branched alkyl groups having 4 to 22 carbon atoms include isobutyl, t-butyl, 2-ethylhexyl, 3,7-dimethyloctyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldodecyl, and 3,7,11-trimethyldodecyl groups. Branched alkyl groups having 4 to 22 carbon atoms also include primary alkyl groups having a cyclic cycloalkyl group such as a cyclohexylmethyl group. Examples of cycloalkyl groups having 4 to 22 carbon atoms include a cyclohexyl, t-butylcyclohexyl, trimethylcyclohexyl, tricyclodecyl, and isobornyl group. Furthermore, 7 Examples of the arylalkyl group of 1 to 22 include a benzyl group and a phenylethyl group.

[0026] When an olefin polymer, which is a thermoplastic resin, is used as the resin, the alkyl group is preferably a linear alkyl group having 8 to 22 carbon atoms or a branched alkyl group having 8 to 22 carbon atoms, and more preferably a linear alkyl group having 8 to 22 carbon atoms. Modified lignin etherified with these alkyl groups has particularly excellent compatibility with olefin polymers. Furthermore, the crystallinity of the long-chain alkyl group improves handleability, and this is also preferred from the viewpoint of the thermoplasticity and low melting point of the modified lignin. Examples of linear alkyl groups having 8 to 22 carbon atoms include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, and docosyl. These alkyl groups are aliphatic groups derived from natural materials such as coconut oil. Therefore, modifying natural lignin with these alkyl groups to produce modified lignin allows the entire modified lignin to be a natural material, which is environmentally preferable. Among these, the alkyl group is preferably an octadecyl group from the viewpoints of cost, crystallinity, melting point, and the like.

[0027] Modified lignin is lignin in which at least a portion of the aromatic hydroxyl groups of lignin have been etherified with alkyl groups, and is composed of lignin-derived moieties and the introduced alkyl groups. The content of the lignin-derived moieties constituting the modified lignin is preferably 50 to 90 mass% and more preferably 60 to 80 mass% based on the total of the lignin-derived moieties and the alkyl groups. If the content of the lignin-derived moieties exceeds 90 mass%, the amount of alkyl groups is small, resulting in insufficient compatibility with resins and the likelihood of the formation of lumps. On the other hand, if the content of the lignin-derived moieties is less than 50 mass%, the amount of alkyl groups is large, resulting in a decrease in the mechanical properties of the resin, causing it to soften, or a significant decrease in the melting temperature of the resin composition.

[0028] When the modified lignin is one in which some of the aromatic hydroxyl groups of the lignin have been etherified with a specific alkyl group, the remaining aromatic hydroxyl groups may be left as they are or may be etherified with an alkyl group other than the specific alkyl group. The remaining aromatic hydroxyl groups may be reacted with a compound having an epoxy group or a compound having a carboxy group. Furthermore, the aliphatic hydroxyl groups in the lignin structure may be reacted with a compound capable of reacting with the hydroxyl groups, such as a compound having a carboxy group, an amino group, or an isocyanate group, or an acid halide.

[0029] The sulfur atom content of the modified lignin is less than 0.2% by mass, preferably less than 0.1% by mass. By using modified lignin with a sulfur atom content of less than 0.2% by mass, it is possible to suppress the generation of a foul odor (sulfur odor) during processing and reduce the sulfur odor remaining in the molded product. As will be described later, modified lignin with a sulfur atom content of less than 0.2% by mass can be obtained by modifying lignin with a sulfur atom content of less than 0.5% by mass.

[0030] The number average molecular weight (Mn) of the modified lignin is 800 to 10,000, preferably 1,000 to 8,000. If the Mn of the modified lignin is less than 800, the molecular weight is too small, and the effects of using the modified lignin may not be fully realized. On the other hand, if the Mn of the modified lignin is more than 10,000, the compatibility with resins may be reduced or the viscosity may increase when kneaded with resins. The molecular weight distribution (PDI) of the modified lignin is not particularly limited and may be, for example, 1.5 to 100.

[0031] (resin) The resin may be a conventionally known thermoplastic resin or thermosetting resin. Examples of the thermoplastic resin include olefin polymers such as polyethylene, polypropylene, polyethylene vinyl acetate, polyethylene vinyl alcohol, polyethylene ethyl acrylate, polymethylpentene, and polycyclopentadiene; styrene polymers such as polystyrene, polystyrene butadiene polymer, and polyacrylonitrile butadiene styrene; halogenated vinyl polymers such as polyvinyl chloride, polyvinylidene chloride, and polytetrafluoroethylene; acrylic polymers such as polymethyl methacrylate and polyacrylonitrile; vinyl acetate polymers such as polyvinyl acetate and polyvinyl alcohol; ester polymers such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, and polyhydroxyalkanoic acid; amide polymers such as nylon 6, nylon 66, and polyamide 11; carbonate polymers such as polybisphenol A carbonate; acetal polymers such as polyoxymethylene; urethane polymers; silicone polymers; and engineering plastics such as polyphenylene ether, polyphenylene sulfide, and polyether ether ketone. Examples of the thermosetting resin include phenol resin, urea resin, alkyd resin, unsaturated polyester resin, and epoxy resin.

[0032] As the resin, it is preferable to use a thermoplastic resin that can be processed into films, molded articles, containers, fibers, etc. Among them, since modified lignin having a long-chain alkyl ether group is used, it is preferable to use an olefin-based polymer that has good compatibility with such modified lignin, and it is more preferable to use a versatile olefin-based polymer such as polyethylene or polypropylene.

[0033] The content of modified lignin in the resin composition is preferably 1 to 33.4% by mass, more preferably 5 to 25% by mass, based on the total weight of the modified lignin and the resin. If the content of modified lignin is less than 1% by mass, the effects of using the modified lignin may be less pronounced. On the other hand, if the content of modified lignin is more than 33.4% by mass, the amount of alkyl ether groups in the modified lignin structure may be too large, which may significantly reduce the physical properties of the resin composition itself. When the content of modified lignin in the resin composition is 1 to 33.4% by mass, the content of the lignin-derived portion in the resin composition is, for example, 0.5 to 30% by mass, based on the total weight of the modified lignin and the resin.

[0034] (additives) The resin composition may further contain various additives as components other than the modified lignin and resin. Examples of additives include antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, lubricants, compatibilizers, conductive materials, magnetic materials, foaming agents, fragrances, odor-reducing agents, and flame retardants. Lignin may decompose upon heating to generate vanillin and other compounds. Therefore, amines or hydrazine compounds can be added to the resin composition to trap vanillin. Colorants such as dyes and pigments may also be added. Furthermore, various fillers such as silica, glass fiber, carbon fiber, carbon nanotubes, cellulose fiber, cellulose nanofiber, lignocellulose, and unmodified lignin may also be added.

[0035] When wood-derived materials such as cellulosic fiber, lignocellulose, and unmodified lignin are used as fillers, modified lignin adsorbs to the surface of these fillers and acts as a dispersant, allowing these fillers to be dispersed in the resin in the form of fine particles. Furthermore, when fillers with a six-membered ring carbon skeleton, such as carbon fiber or carbon nanotubes, are used, the polyaromatic rings of the modified lignin adsorb to the filler through ππ stacking, allowing the filler to be well dispersed in the resin.

[0036] The resin composition of the present embodiment is useful as a material for various molded articles such as automobiles, home appliances, electronic components, display materials, construction materials, food containers, cosmetic containers, agricultural films, and battery materials.

[0037] The resin composition may be molded directly into a molded body, or it may be prepared as a masterbatch containing a high concentration of modified lignin, diluted with a resin to a predetermined modified lignin content, and then molded into a molded body. The resin composition of this embodiment effectively utilizes the effects of lignin, improving the mechanical properties and light resistance of the base resin. Furthermore, since the resin composition uses lignin, which is a biomass material, it is possible to produce environmentally friendly molded bodies. Furthermore, since the resin composition of this embodiment uses lignin derived from plants such as wood, it can also be used to produce molded bodies with a woody texture. Furthermore, since the resin composition of this embodiment uses lignin, it is expected to provide molded bodies that are environmentally degradable and lose their shape when left in the environment due to the action of white-rot fungi that decompose lignin.

[0038] <Method of manufacturing resin composition> The resin composition can be produced by the following method. That is, one embodiment of the method for producing a resin composition of the present invention is a method for producing the resin composition, which includes a step (modification step) of reacting an alkali metal salt with aromatic hydroxyl groups of lignin having a sulfur atom content of less than 0.5% by mass to form an alkoxide, and then reacting an alkyl halide to obtain a modified lignin, which is an alkyl-etherified lignin. The alkyl halide may be a linear alkyl halide having 4 to 22 carbon atoms, a branched alkyl halide having 4 to 22 carbon atoms, a cycloalkyl halide having 4 to 22 carbon atoms, or a cycloalkyl halide having 4 to 22 carbon atoms. 7 At least one selected from the group consisting of aryl alkyl halides of 1 to 22.

[0039] When alkyl-etherifying lignin, the reaction can be carried out in a state in which the lignin is completely dissolved in a lignin-soluble organic solvent. Alternatively, the aromatic hydroxyl groups on the surface or inside of particulate lignin dispersed in a lignin-insoluble or poorly soluble solvent can be alkyl-etherified. Examples of organic solvents capable of dissolving lignin include amide-based solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and 3-methoxy-N,N-dimethylpropionamide; sulfoxide-based solvents such as dimethyl sulfoxide and sulfolane; and urea-based solvents such as tetramethylurea and dimethylimidazolidinone. Examples of solvents capable of dissolving or poorly dissolving lignin include water; hydrocarbon-based solvents such as toluene; alcohol-based solvents such as isopropyl alcohol; ketone-based solvents such as acetone and methyl ethyl ketone; ester-based solvents such as butyl acetate; ether-based solvents such as tetrahydrofuran; and glycol-based solvents such as diethylene glycol dimethyl ether. A lignin-soluble organic solvent and a lignin-insoluble or poorly soluble solvent may be used in combination.

[0040] The lignin used has a sulfur atom content of less than 0.5% by mass, preferably 0.3% by mass or less. By modifying lignin having a sulfur atom content of less than 0.5% by mass, modified lignin having a sulfur atom content of less than 0.2% by mass can be obtained.

[0041] After dissolving or dispersing lignin in a solvent, at least a portion of the aromatic hydroxyl groups of the lignin can be alkoxidized by reacting with an alkyl metal salt. The concentration of lignin in a lignin solution or dispersion obtained by dissolving or dispersing lignin in a solvent may be, for example, 10 to 40 mass%, and considering productivity and the like, 20 to 33 mass%. Examples of alkyl metal salts include carbonates such as sodium carbonate and potassium carbonate; alkali metal alkoxides such as sodium methoxide and potassium t-butoxide; and sodium hydride.

[0042] Alkoxide lignin, in which at least a portion of the aromatic hydroxyl groups have been alkoxidized, is reacted with an alkyl halide, whereby the alkali metal halide is eliminated and at least a portion of the aromatic hydroxyl groups of the lignin are alkyl-etherified, thereby obtaining a modified lignin that is an alkyl-etherified lignin.

[0043] The reaction between alkoxide lignin and alkyl halides is a nucleophilic substitution reaction by the alkyl halides. Examples of alkyl halides include linear alkyl halides having 4 to 22 carbon atoms, branched alkyl halides having 4 to 22 carbon atoms, cycloalkyl halides having 4 to 22 carbon atoms, and alkyl halides having 4 to 22 carbon atoms. 7 At least one selected from the group consisting of aryl alkyl halides of 1 to 22 is used. From the viewpoint of suppressing the side effect of the alkyl halide elimination reaction, it is preferable to use a primary alkyl halide. Furthermore, alkyl chloride, alkyl bromide, and alkyl iodide can be used as the alkyl halide. Among these, it is preferable to use alkyl bromide from the viewpoint of elimination property and stability. Specific examples of alkyl halides include octyl bromide, nonyl bromide, decyl bromide, dodecyl bromide, tridecyl bromide, tetradecyl bromide, hexadecyl bromide, heptadecyl bromide, octadecyl bromide, and docosyl bromide. Among these, octadecyl chloride, octadecyl bromide, and octadecyl iodide are preferred, with octadecyl bromide being particularly preferred.

[0044] The amount of alkyl halide to be reacted with alkoxidized lignin is not particularly limited. However, in order to prevent the remaining unreacted alkyl halide, it is preferable to react a small amount of alkyl halide relative to the alkoxidized hydroxyl groups. Specifically, the amount of alkoxidized lignin is preferably 1.1 to 3 times by mole, more preferably 1.3 to 2 times by mole, per mole of alkyl halide.

[0045] The temperature at which the aromatic hydroxyl groups of lignin are reacted with the alkali metal salt may be, for example, 0 to 100°C, and preferably 30 to 50°C. The temperature at which the alkoxidized lignin is reacted with the alkyl halide may be, for example, 50 to 150°C, and preferably 70 to 110°C.

[0046] After reacting the alkoxide lignin with an alkyl halide, the reaction solution can be added to water or an aqueous liquid medium containing water to precipitate modified lignin. Using an aqueous liquid medium containing an acidic substance such as hydrochloric acid or acetic acid can convert the remaining alkoxide that did not react with the alkyl halide into aromatic hydroxyl groups. The precipitated modified lignin can then be thoroughly washed with water, methanol, or the like to remove the alkali metal halide that was produced. After washing, the modified lignin can be made into a water paste, or after drying, the powder can be converted into a block of modified lignin. It can also be pulverized as needed.

[0047] The desired resin composition can be obtained by mixing and kneading the obtained modified lignin, resin, and various additives used as needed using a conventionally known method. When the resin is solid, it is preferable to heat-melt the resin and knead it. For kneading, a mixing roll, a Banbury mixer, a kneader, a kneader-ruder, a single-screw extruder, a multi-screw extruder, or the like can be used. The temperature during kneading can be set taking into consideration the melting point and midpoint of the resin used. After kneading, the obtained resin composition can be cut into a sheet or pelletized using a pelletizer. On the other hand, when the resin is liquid, a mixer such as a disper can be used. [Example]

[0048] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0049] <Synthesis of modified lignin> (Synthesis Example 1) 525 parts of dimethylformamide (DMF) was added to a reaction vessel and stirred. 114.1 parts of Lignin-1 (trade name "LIGNOVA PURE", manufactured by Fibenol, number average molecular weight (Mn) 610, molecular weight distribution (PDI) 20.3, peak top molecular weight (PT) 1,200, lignin content 98.8%, sulfur atom content 0.2%) was added and dissolved in DMF. A dark brown solution was obtained, with almost no insoluble matter. Molecular weight and other values ​​were measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the developing solvent, and are polystyrene-equivalent values.

[0050] 45.6 parts of potassium carbonate was added and the reaction was carried out at 50°C for 2 hours. 100.2 parts of octadecyl bromide (SB) was added and the reaction was carried out at 90°C for 7 hours. There was no insoluble matter at the beginning of the reaction, but after 2 hours, the mixture became opaque. It is believed that the reaction produced potassium bromide as a by-product. After the reaction was completed, the reaction solution was analyzed by GPC, and no peak for the raw material SB was detected, so it is believed that all of the SB had reacted with lignin.

[0051] 5,000 mL of water was placed in a separate container, and 200 parts of hydrochloric acid diluted 10 times with water was added. When the reaction solution was added while stirring with a disperser, a brown powder precipitated. After stirring for 30 minutes, the mixture was filtered. The filtrate was slightly brown and almost transparent. After thorough washing with water, the mixture was removed and dried in a dryer at 60°C. Using a moisture meter set at 120°C, the mixture was further dried until the nonvolatile content reached 99% or more, yielding 189.1 parts of modified lignin HR-1, a brown powder with a nonvolatile content of 99.5%.

[0052] The resulting modified lignin HR-1 was analyzed by GPC, revealing a single peak. Furthermore, the Mn was 2,400, the PDI was 10.5, and the PT was 3,400, confirming that these values ​​were higher than those of the raw material lignin-1. NMR and IR were measured using a nuclear magnetic resonance spectrometer and an infrared spectrophotometer. The NMR chart of the modified lignin HR-1 is shown in Figure 1. The IR chart of the modified lignin HR-1 is also shown in Figure 2. As shown in Figure 1, the aromatic ring peak of the lignin is observed around 6.5 to 6.7 ppm, and the alkyl group peak of the octadecyl group can also be confirmed. Furthermore, as shown in Figure 2, the peak at 3,000 cm -1 Alkyl groups near 1,700 cm -1 A characteristic peak of lignin was observed near the center. From the above, it was confirmed that alkyl etherified lignin was produced. In addition, a portion of the material was burned, and the resulting gas was absorbed in an absorption liquid, which was then analyzed by ion chromatography. As a result, a peak of sulfur atoms was observed. The sulfur atom content was then quantified and found to be 0.12%, indicating that the amount of sulfur atoms was very low.

[0053] Since all of the SB used was reacted, the amount of alkyl group (octadecyl group) and lignin contained in the obtained modified lignin can be calculated according to the following calculation method.

[0054] A: Number of moles of SB = Number of moles of hydrogen released from lignin: 100.2 (parts by mass of SB) ÷ 333.4 (molecular weight of SB) = 0.3 B: mass% of octadecyl groups in SB = 253.5 (molecular weight of octadecyl groups in SB) ÷ 333.4 (molecular weight of SB) × 100 = 76.0 C: Amount of lignin after reaction = 114.1 (mass parts of lignin) - 0.3 (amount of hydrogen atoms released during the reaction) = 113.8 D: Mass of octadecyl group introduced into lignin = 100.2 (mass part of SB) × B / 100 = 76.1 Lignin content in modified lignin (mass%) = C ÷ (C + D) × 100 = 113.8 / (113.8 + 76.1) × 100 = 60

[0055] From the above, it can be seen that the modified lignin HR-1 contains lignin and alkyl groups in a ratio of lignin:alkyl group=60:40, and the lignin content is 60%.

[0056] (Synthesis Examples 2 to 6, Comparative Synthesis Examples 1 to 3) Modified lignins HR-2 to 6 and HHR-1 to 3 were obtained in the same manner as in Synthesis Example 1 above, except that the types and amounts of various materials shown in Tables 1 and 2 were used. Various physical properties of the obtained modified lignins are shown in Tables 1 and 2. The amount of DMF was adjusted so that the other raw materials accounted for 33.1% by mass. The meanings of the abbreviations in Tables 1 and 2 are as follows: BB: Butyl bromide DB: Dodecyl bromide TB: Tetradecyl bromide Lignin-2: Trade name "IndulinAT", manufactured by INGEVITY, Mn 800, PDI 11.18, PT 1,200, lignin content 97.5%, sulfur atom content 5%)

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[0059] The modified lignin HHR-1 obtained in Comparative Synthesis Example 1 has a high lignin content and a low alkyl group content, i.e., a modified lignin with a low amount of alkyl groups compatible with resins. The modified lignin HHR-2 obtained in Comparative Synthesis Example 2 has a low lignin content and a high alkyl group content. When this modified lignin HHR-2 was dried in the same manner as in Synthesis Example 1, it dissolved at 60°C and was found to be soft. In Comparative Synthesis Example 3, a lignin with a high sulfur atom content was used. As a result, a strong sulfur odor was detected during synthesis and drying after precipitation, raising concerns about its processing and use in products.

[0060] <Production and Evaluation of Resin Composition (1)> Example 1 83.3 parts of polyethylene (PE-1) (trade name "Novatec LF640MA", manufactured by Japan Polyethylene Corporation, MFR 5g / 10min, melting point 113°C, crushed product), 16.7 parts of modified lignin HR-1, and 0.1 parts of antioxidant (trade name "Irganox 10101", manufactured by BASF) were placed in a plastic bag and mixed by shaking well. Next, the mixture was kneaded at 180°C using a mixing mixer (model "IMC-A911", manufactured by Inoue Seisakusho Co., Ltd., kneading blade clearance 0.5mm) to obtain Resin Composition J-1, a dark brown mixture. No unpleasant odors such as sulfur odor were generated during kneading. The evaluation result for manufacturing processability was "○". The evaluation criteria for manufacturing processability are shown below. ○: No bad odor was generated. ×: A strong bad odor was generated.

[0061] The obtained resin composition J-1 was pulverized using a pulverizer, and then a sheet approximately 0.5 mm thick was produced using a hot press. The produced sheet was a uniform brown sheet without any lumps or foreign matter, and the compatibility evaluation result was "Good." A micrograph (50x magnification) showing the microstructure of the produced sheet is shown in Figure 3. Figure 3 shows that the modified lignin was dispersed in the resin in an extremely well-compatible state. The compatibility evaluation criteria are as follows: ○: No lumps or foreign matter were found, and the mixture was well-miscible. △: Some lumps or foreign matter were found, but the amount was small. ×: Compatibility was observed, but there were many lumps and foreign matter. XX: Almost no compatibility, resulting in lumps or foreign matter.

[0062] (Examples 2 to 20, Comparative Examples 1 to 5) Resin compositions J-2 to 20 and HJ-1 to 5 were obtained in the same manner as in Example 1 described above, except that the formulations and conditions were as shown in Tables 3 to 7. The physical properties and evaluation results of the obtained resin compositions are shown in Tables 3 to 7. The meanings of the abbreviations in the tables are as follows. FIG. 4 shows a photomicrograph (50x magnification) illustrating the microstructure of a sheet produced using resin composition HJ-1 produced in Comparative Example 1. FIG. 5 shows a photomicrograph (50x magnification) illustrating the microstructure of a sheet produced using resin composition HJ-2 produced in Comparative Example 2. PE-2: Polyethylene, product name "Suntech-LD-M6545", manufactured by Asahi Kasei Corporation, MFR 45g / 10min, bit cut softening point temperature 79℃, coarsely crushed PP: Polypropylene, product name "Prime Polypro J707EG", manufactured by Prime Polymer, MFR 30g / min PA: Polyamide 11, product name "Rilsan BMNO", manufactured by Arkema, melting point 189°C PES: Polylactic acid, trade name "Luminy LX175", manufactured by Total Corbion PLA, MFR 8g / 10min, melting point 150-160℃

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[0068] <Production and Evaluation of Resin Composition (2)> Examples 21 and 22 Resin composition J-3 obtained in Example 3 was pulverized using a pulverizer. 75 parts of PE-1 and 25 parts of the pulverized resin composition J-3 were mixed and then kneaded at 180°C using a twin-screw extruder. The mixture was then extruded into strands, cooled, and cut with a pelletizer to obtain resin composition J-21 in the form of pellets.

[0069] Similarly, pellet-shaped resin composition J-22 was obtained using 90 parts of PE-1 and 10 parts of pulverized resin composition J-3. Resin composition J-21 had a modified lignin content of 8.3% and a lignin content of 5%. Resin composition J-22 had a modified lignin content of 3.3% and a lignin content of 2%. Using each of the obtained resin compositions, sheets were produced in the same manner as in Example 1. When the produced sheets were observed, no lumps or foreign matter were found, indicating good compatibility. From the above results, it was found that by diluting a resin composition containing a high concentration of modified lignin, it is possible to produce resin compositions and molded articles in which the modified lignin is adjusted to a desired concentration. In other words, it was found that the resin composition of this embodiment can be used as a masterbatch.

[0070] Example 23 77.5 parts of a cresol novolac epoxy resin (trade name "Epiclon N-660", manufactured by DIC Corporation), 20 parts of modified lignin HR-5, 0.5 parts of 2-methylimidazole, and 2 parts of carnauba wax were mixed and kneaded for 5 minutes using a heated roll at a temperature of 100°C to obtain a sheet-like molded product. The obtained sheet-like molded product was cooled and then pulverized to obtain resin composition J-23. The obtained resin composition J-23 had a modified lignin content of 20% by mass and a lignin content of 4.6%. Using the obtained resin composition J-23, a sheet was produced in the same manner as in Example 1. When the produced sheet was observed, no lumps or foreign matter were found, indicating good compatibility.

[0071] <Reference evaluation example> PP and resin composition J-14 were each injection molded at 200°C to produce dumbbell specimens (dumbbell thickness: 2 mm). A tensile test was performed in accordance with JIS K7161 using a tensile testing machine (Universal Testing Machine, manufactured by Shimadzu Corporation), and the tensile strength, tensile elongation, and tensile modulus were measured and calculated. The dumbbell specimens produced using PP had a tensile strength of 27.6 MPa, a tensile elongation of 40%, and a tensile modulus of 1,450 MPa. In contrast, the dumbbell specimens produced using resin composition J-14 had a tensile strength of 24.3 MPa, a tensile elongation of 53%, and a tensile modulus of 1,560 MPa. These results demonstrate that the use of modified lignin improved the physical properties of the resin (PP). Similar tests were also performed on the resin compositions produced in other examples, confirming the improved physical properties of the resins. [Industrial Applicability]

[0072] The resin composition of the present invention is useful as a constituent material for automobiles, home appliances, electronic components, display materials, buildings, containers, films, batteries, semiconductor encapsulants, and the like.

Claims

1. Contains modified lignin and resin, the modified lignin is an alkyl-etherified lignin in which at least a portion of aromatic hydroxyl groups of lignin are etherified with at least one alkyl group selected from the group consisting of a linear alkyl group having 4 to 22 carbon atoms, a branched alkyl group having 4 to 22 carbon atoms, a cycloalkyl group having 4 to 22 carbon atoms, and an arylalkyl group having 7 to 22 carbon atoms; The sulfur atom content of the modified lignin is less than 0.2% by mass, The content of the portion derived from the lignin constituting the modified lignin is 50 to 90% by mass, A resin composition, wherein the modified lignin has a number average molecular weight of 800 to 10,000.

2. The resin composition according to claim 1, wherein the content of the modified lignin is 1 to 33.4 mass% based on the total of the modified lignin and the resin.

3. The resin composition according to claim 1 , wherein the resin is a thermoplastic resin.

4. the resin is an olefin-based polymer, 2. The resin composition according to claim 1, wherein the alkyl group is a linear alkyl group having 8 to 22 carbon atoms or a branched alkyl group having 8 to 22 carbon atoms.

5. The resin composition according to claim 4, wherein the alkyl group is an octadecyl group.

6. A method for producing the resin composition according to any one of claims 1 to 5, a step of reacting an alkali metal salt with aromatic hydroxyl groups of the lignin having a sulfur atom content of less than 0.5% by mass to form an alkoxide, and then reacting an alkyl halide with the alkoxide to obtain a modified lignin that is an alkyl-etherified lignin; The method for producing a resin composition, wherein the alkyl halide is at least one selected from the group consisting of linear alkyl halides having 4 to 22 carbon atoms, branched alkyl halides having 4 to 22 carbon atoms, cycloalkyl halides having 4 to 22 carbon atoms, and aryl alkyl halides having 7 to 22 carbon atoms.

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