Polyalkylene glycol lignin fatty acid ester and composition containing oil or organic solvent

Abstract

To provide: a lignin derivative which is easily mixed with oil and an organic solvent; and a mixed composition of such a lignin derivative with oil and / or an organic solvent.SOLUTION: There are provided: a lignin derivative in which at least one hydroxyl group of polyalkylene glycol lignin is esterified by a fatty acid; and a mixed composition of the lignin derivative and oil and / or an organic solvent. Specifically, a plastic, a resin additive, a rubber additive, ink and a coating additive are suitably usable by imparting miscibility to oil and an organic solvent to the lignin derivative.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to lignin derivatives that are easily miscible in oils and organic solvents, and mixtures thereof with oils and / or organic solvents. These can be suitably used as additives for plastics, resins, rubbers, inks, and paints. [Background technology]

[0002] There has been growing interest in the use of biomass as a modifier for industrial materials such as resins, plastics, and rubber, as well as an additive for inks and paints. Examples of biomass include biological or biologically derived materials such as fruit, vegetable, and grain processing waste, wood chips, and paper products. Among these, wood-derived lignin has attracted particular attention in recent years as a biomass resource. Lignin is a polymeric compound primarily composed of aromatic units. Due to its chemical and mechanical stability, it is used as an additive or modifier for industrial products. Specifically, lignosulfonic acid (salt) is a typical water-soluble lignin obtained from the wastewater of the sulfite chemical pulping process (a high-temperature, high-pressure reaction using sulfite and calcium sulfite). It is widely used as a concrete admixture, dispersant, ion-exchange resin, and other applications.

[0003] On the other hand, it is expected that lignin's physicochemical stability and dispersibility derived from its polymer structure will be used as an additive to improve the quality and functionality of industrial materials such as plastics, resins, and rubber products. However, lignin itself and existing derivatives such as the aforementioned lignosulfonic acid (salt) have poor affinity with these materials, making it difficult to mix the two uniformly, and this has not yet led to practical application.

[0004] To solve these problems, various lignin derivatives that are miscible with oils and organic solvents have been investigated. Specifically, polyethylene glycol lignin, in which the lignin component of wood is modified with polyethylene glycol (Patent Documents 1-4, Non-Patent Documents 1-2), modified products with the addition of ethylene oxide or acylated products with fatty acids (Patent Documents 3, 5-7), and derivatives in which alkylene oxide is further added to polyalkylene glycol lignin (Patent Document 5) have been disclosed. However, none of the prior art has yet produced a lignin derivative that is sufficiently miscible with oils and organic solvents. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-197517 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-105991 [Patent Document 3] Patent No. 7383260 [Patent Document 4] Japanese Patent Application Publication No. 2023-128444 [Patent Document 5] Patent No. 6713256 [Patent Document 6] Special Publication No. 2017-501290 [Patent Document 7] Patent No. 6525343 [Non-patent literature]

[0006] [Non-Patent Document 1] Takata et al, BioResources 11(2), 4446-4458 (2016) [Non-patent document 2] ttNge et al, ACS Sustainable Chem. Eng. 2018, 6, 7841-7848 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention relates to providing lignin derivatives that are easily miscible in oils and organic solvents, and mixture compositions of these with oils and / or organic solvents. [Means for solving the problem]

[0008] The present inventors have conducted extensive research into lignin derivatives and have found that fatty acid esters of polyalkylene glycol lignin are easily miscible with oils and organic solvents and can be suitably used as additives for plastics, resins, rubbers, inks, and paints. This finding led to the completion of the present invention.

[0009] That is, the present invention relates to the following (1) to (4). (1) A fatty acid ester of a fatty acid having 2 to 28 carbon atoms and a linear and / or branched structure, which may contain an unsaturated bond, and a polyalkylene glycol lignin. (2) The polyalkylene glycol lignin fatty acid ester according to (1), wherein the fatty acid is liquid at room temperature. (3) The polyalkylene glycol lignin fatty acid ester according to (1) or (2), wherein the polyalkylene glycol is polyethylene glycol. (4) A composition comprising a mixture of the polyalkylene glycol lignin fatty acid ester according to any one of (1) to (3) and an oil and / or an organic solvent. [Effects of the Invention]

[0010] According to the present invention, there can be provided a polyalkylene glycol lignin fatty acid ester which can be suitably used as an additive for plastics, resins, rubbers, inks and paints, and which is easily miscible with oils and organic solvents. DETAILED DESCRIPTION OF THE INVENTION

[0011] The polyalkylene glycol lignin used as the raw material in the present invention can be produced by the methods disclosed in Patent Documents 1 and 4. For example, lignocellulose, which is primarily derived from woody or herbaceous biomass such as cedar and is composed of polysaccharide polymers such as cellulose and hemicellulose and the phenolic polymer lignin, can be obtained by solvolysis in the presence of an acid catalyst using polyalkylene glycols such as ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol, glycerin, or polyglycerin as a solvent. Derivatives obtained by further adding ethylene oxide or propylene oxide to the resulting polyalkylene glycol lignin or (poly)glycerin lignin can also be used (Patent Document 3). Here, ethylene oxide or propylene oxide may be added to the phenolic hydroxyl groups of glycol lignin or to the glycol chains derived from the glycol lignin raw material, thereby further extending the glycol chains. Either method can be used in the present invention, and a mixture of the two methods is acceptable.

[0012] As the polyalkylene glycol lignin used in the present invention, polyethylene glycol lignin is particularly preferred from the viewpoints of availability of raw materials and production costs.

[0013] In the present invention, the polyalkylene glycol lignin is further converted into a fatty acid ester. There are no particular limitations on the method for producing the fatty acid ester. Specifically, the fatty acid ester can be produced by known techniques, such as direct esterification using a fatty acid and an alkali or acid catalyst, transesterification using a fatty acid methyl (ethyl) and an alkali or acid catalyst, or a method using a fatty acid chloride (acid chloride). The catalyst is not particularly limited, and can be any of the commonly used catalysts for esterification, such as alkali catalysts such as sodium hydroxide or potassium hydroxide, acid catalysts such as sulfuric acid, paratoluenesulfonic acid, and fluoroboric acid ether complex, or dehydration condensation agents such as carbodiimides.

[0014] In the present invention, the fatty acid chloride method can be applied to facilitate the esterification reaction and achieve a high esterification rate. Specifically, this method uses dimethylformamide (DMF) and pyridine as solvents, and fatty acid chloride is added dropwise at room temperature or a low temperature of 10°C or less to cause the reaction. The reaction product is then extracted with ethyl acetate or the like, washed with water, and dried to obtain the target product.

[0015] The fatty acids used in the esterification of the present invention preferably have 2 to 28 carbon atoms and have a linear and / or branched structure containing unsaturated and / or saturated bonds. Specific examples include linear saturated fatty acids such as acetic acid, propionic acid, hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; linear unsaturated fatty acids such as acrylic acid, oleic acid, palmitoleic acid, linoleic acid, and linolenic acid; and branched saturated fatty acids such as 2-ethylhexanoic acid, 2-hexyldecanoic acid, isostearic acid, and Guerbet fatty acid. Liquid fatty acids at room temperature are particularly preferred because the resulting esters are more miscible with oils and organic solvents. Furthermore, these fatty acids can also be used in the present invention in the form of methyl esters, ethyl esters, and / or acid chlorides.

[0016] In the present invention, a mixed composition containing an oil and / or an organic solvent can be prepared to improve compatibility and workability when added to industrial materials such as plastics, resins, rubbers, inks, and paints. The blending ratio of the polyalkylene glycol lignin fatty acid ester of the present invention to the oil and / or organic solvent is not particularly limited and may be any ratio as long as the fluidity of the mixed composition is maintained. However, a ratio of polyalkylene glycol lignin fatty acid ester (A):oil and / or organic solvent (B) of 0.1:99.9 to 95.0 to 5.0 (parts by mass) is preferred in terms of workability when added to industrial materials.

[0017] The oil and / or organic solvent to be blended with the polyalkylene glycol lignin fatty acid ester of the present invention is not particularly limited as long as it is miscible with the product of the present invention. Specific examples include hydrocarbons such as normal hexane, cyclohexane, heptane, decane, liquid paraffin, gasoline, kerosene, squalane, benzene, toluene, and xylene; esters such as ethyl acetate, propyl acetate, isopropyl myristate, triglycerides, and animal and vegetable oils; water-soluble organic solvents such as methanol, ethanol, isopropanol, acetone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and N-methylpyrrolidone; and halogenated solvents such as chloroform and dichloromethane. [Example]

[0018] The effects of the present invention will be explained using the following examples and comparative examples, but the technical scope of the present invention is not limited to these. In the examples, the notation "%" may be used, but unless otherwise specified, it represents "% by mass." Furthermore, unless otherwise specified, each operation is performed at room temperature (25°C).

[0019] Example 1: Preparation of polyalkylene glycol lignin Polyethylene glycol (400) lignin was prepared from polyethylene glycol with a weight-average molecular weight of 400 (polyethylene glycol 400) and cedar wood flour (hereinafter referred to as PEG400 lignin, Comparative Product 1) according to the examples in Patent Document 3. Commercially available polyethylene glycol (PEG400) with a weight-average molecular weight of 400 and 1% sulfuric acid as an acid catalyst were placed in a reaction vessel and stirred. The wood flour was placed in a reaction vessel and reacted at 140°C for 90 minutes with stirring. After cooling the reaction vessel and confirming that the internal temperature was below 30°C, sodium hydroxide (0.1 mol / L) was added and stirred. The resulting solid component was filtered to recover the reaction solution. Sulfuric acid was added to the resulting reaction solution to adjust the pH to 2.0. This resulted in a suspension of PEG400 lignin. The PEG400 lignin was then recovered by filtration. The PEG400 lignin was then suspended in water and washed, then recovered by filtration and dried. The resulting substance was a dark brown powder. The chemical structure of the preparation was determined by FT-IR and 1 This was confirmed by H-NMR. 1 g of PEG400 lignin was dissolved in 10 g of a mixture of acetic anhydride and pyridine (mixing weight ratio = 1 / 1), and the solution was placed in a water bath at 50°C for 24 hours to carry out an acetylation reaction. The resulting acetylated product was separated, purified, and dried. Next, this acetylated product was dissolved in CDCl3 and analyzed at 60 MHz using TMS as a standard substance. 1 The H-NMR spectrum was measured. In this spectrum, the peak at 3.5 to 3.6 ppm was identified as the methylene proton in the oxyethylene chain, and this identification confirmed that polyethylene glycol had been added to the lignin molecule. Next, the FT-IR spectrum of 1 mg of the same sample was measured using the KBr tablet method. In this spectrum, the peak at 3400 cm originating from the hydroxyl group was observed. -1 near 1600cm -1 Near and 1510 cm -1 near 1100cm due to ether bonds -1 Characteristic absorption was confirmed in the vicinity.

[0020] Example 2: Preparation of polyalkylene glycol lignin fatty acid ester Lauric acid ester, stearic acid ester, and isostearic acid ester were each prepared by the following method using the PEG400 lignin prepared in Example 1. The obtained substances were dark brown viscous solids to pastes. <PEG400 Lignin Lauric Acid Ester (Invention Product 1)> PEG400 lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, lauric acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, exchanged water and ethyl acetate were added in that order to extract the reaction product into an organic layer. Sodium sulfate was added to the organic layer to dry it. The organic layer was filtered and the resulting organic layer was concentrated to dryness using a rotary evaporator to obtain PEG400 lignin lauric acid ester (Invention Product 1). The chemical structure of the preparation was confirmed by FT-IR and 1 10 mg of lauric acid ester was dissolved in CDCl3 and analyzed by H-NMR at 60 MHz using TMS as the standard substance. 1 The H-NMR spectrum was measured. In this spectrum, the peaks at 3.5 to 3.65 ppm were identified as methylene protons in the oxyethylene chain, and the peaks at 0.8 to 1.5 ppm were identified as methylene protons of the lauric acid skeleton. This identification confirmed the structure in which lauric acid is ester-bonded to lignin molecules to which polyethylene glycol has been added. The FT-IR spectrum of 1 mg of the same sample was measured using the KBr pellet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 near 1100cm due to ether bonds -1 A specific absorption characteristic was confirmed in the vicinity. <PEG400 lignin stearate (Invention 2)> PEG400 lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, stearic acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, exchanged water and ethyl acetate were added in that order to extract the reaction product into an organic layer. Sodium sulfate was added to the organic layer to dry it. The organic layer was filtered, and the resulting organic layer was concentrated to dryness using a rotary evaporator to obtain PEG400 lignin stearate ester (Invention Product 2). The chemical structure of the preparation was confirmed by FT-IR and 110 mg of stearic acid ester was dissolved in CDCl3 and analyzed by 1 H-NMR at 60 MHz using TMS as the standard substance. 1 The H-NMR spectrum was measured. In this spectrum, the peaks at 3.5 to 3.65 ppm were identified as methylene protons in the oxyethylene chain, and the peaks at 0.8 to 1.5 ppm were identified as methylene protons of the stearic acid skeleton. This identification confirmed the structure in which stearic acid is ester-bonded to lignin molecules to which polyethylene glycol has been added. The FT-IR spectrum of 1 mg of the same sample was measured using the KBr pellet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 near 1100cm due to ether bonds -1 Characteristic absorption was confirmed in the vicinity. <PEG400 Lignin Isostearate Ester (Invention 3)> PEG400 lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, isostearic acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, exchanged water and ethyl acetate were added in that order to extract the reaction product into an organic layer. Sodium sulfate was added to the organic layer to dry it. The organic layer was filtered, and the resulting organic layer was concentrated to dryness using a rotary evaporator to obtain PEG400 lignin isostearate ester (Invention Product 3). The chemical structure of the preparation was confirmed by FT-IR and 1 10 mg of isostearate was dissolved in CDCl3 and analyzed by H-NMR at 60 MHz using TMS as the standard substance. 1The H-NMR spectrum was measured. In this spectrum, the peaks at 3.5 to 3.65 ppm were identified as methylene protons in the oxyethylene chain, and the peaks at 0.8 to 1.5 ppm were identified as methylene protons of the isostearic acid skeleton. This identification confirmed the structure in which isostearic acid is ester-bonded to lignin molecules to which polyethylene glycol has been added. The FT-IR spectrum of 1 mg of the same sample was measured using the KBr tablet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 near 1100cm due to ether bonds -1 Characteristic absorption was confirmed in the vicinity.

[0021] Example 3: Preparation of lignin fatty acid ester - comparative product As comparative products, lauric acid ester, stearic acid ester, and isostearic acid ester of lignin were prepared using lignin (a reagent manufactured by Kanto Chemical Co., Ltd.) according to Example 2. The obtained substances were dark brown solids to viscous solids. <Lignin laurate (Comparative product 2)> Lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, lauric acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, the suspension was washed with purified water. The suspension was filtered, and the powdery reaction product was recovered and dried using a rotary evaporator to obtain lignin lauric acid ester (Comparative Product 2). The chemical structure of the preparation was confirmed by FT-IR and 1 10 mg of lauric acid ester was dissolved in CDCl3 and analyzed by H-NMR at 60 MHz using TMS as the standard substance. 1The H-NMR spectrum was measured. In this spectrum, the peaks between 0.8 and 1.5 ppm were identified as methylene protons of the lauric acid skeleton. This identification confirmed the structure in which lauric acid is ester-bonded to the lignin molecule. FT-IR spectrum was measured using 1 mg of the same sample by the KBr pellet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 Characteristic absorption was confirmed in the vicinity. <Lignin stearate (Comparative product 3)> Lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, stearic acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, the suspension was washed with purified water. The suspension was filtered, and the powdery reaction product was recovered and dried using a rotary evaporator to obtain lignin stearate ester (Comparative Product 3). The chemical structure of the preparation was confirmed by FT-IR and 1 10 mg of stearic acid ester was dissolved in CDCl3 and analyzed by 1 H-NMR at 60 MHz using TMS as the standard substance. 1 The H-NMR spectrum was measured. The peaks between 0.8 and 1.5 ppm were identified as methylene protons of the stearic acid skeleton. This confirmed the structure in which stearic acid is ester-bonded to the lignin molecule. The FT-IR spectrum of the same sample was measured using the KBr pellet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 Characteristic absorption was confirmed in the vicinity. <Lignin isostearate ester (comparison product 4)> Lignin, toluene, and pyridine were placed in a reaction vessel and cooled to 0°C while stirring. Next, isostearic acid chloride was added dropwise to the reaction vessel over 1 hour to allow the reaction to proceed. After the reaction, the suspension was washed with purified water. The suspension was filtered, and the powdery reaction product was recovered and dried using a rotary evaporator to obtain lignin isostearate ester (Comparative Product 4). The chemical structure of the preparation was confirmed by FT-IR and 1 10 mg of isostearate was dissolved in CDCl3 and analyzed by H-NMR at 60 MHz using TMS as the standard substance. 1 The H-NMR spectrum was measured. In this spectrum, the peaks between 0.8 and 1.5 ppm were identified as methylene protons of the isostearic acid skeleton. This confirmed the structure in which isostearic acid is ester-bonded to the lignin molecule. The FT-IR spectrum of 1 mg of the same sample was measured using the KBr pellet method. In this spectrum, the peak at 3400 cm due to the hydroxyl group was observed. -1 The decrease near 1730cm and the carbonyl bond-derived -1 near 1600cm -1 Near and 1510 cm -1 Characteristic absorption was confirmed in the vicinity.

[0022] Example 4: Solubility Test Solubility tests were conducted on Invention Products 1 to 3 and Comparative Products 1 to 4 using dimethylformamide, acetone, toluene, ethyl acetate, chloroform, dichloromethane, hexadecyl 2-ethylhexanoate, and vegetable oil (medium-chain fatty acid triglyceride) in a ratio of Invention Products 1 to 3 and Comparative Products 1 to 4 to each solvent of 1:9. Furthermore, solubility tests were conducted on dimethylformamide, acetone, toluene, ethyl acetate, hexadecyl 2-ethylhexanoate, and vegetable oil (medium-chain fatty acid triglyceride) by heating at 60°C. The solubility criteria were as follows. The results are shown in Tables 1 and 2. <Judgment criteria> ◎: Uniform transparent dissolution 〇: Translucent solution with fluorescence △: Suspension dispersion ×: Insoluble solid precipitate

[0023] [Table 1]

[0024] [Table 2] [Industrial Applicability]

[0025] The present invention provides polyalkylene glycol lignin fatty acid esters of lignin, which impart miscibility with oils and organic solvents, and can be suitably used as additives for modifying plastics, resins, rubbers, inks, and paints.

Claims

1. A fatty acid ester of a fatty acid having 2 to 28 carbon atoms and a linear and / or branched structure, which may contain an unsaturated bond, and a polyalkylene glycol lignin.

2. 2. The polyalkylene glycol lignin fatty acid ester according to claim 1, wherein the fatty acid is liquid at room temperature.

3. 3. The polyalkylene glycol lignin fatty acid ester according to claim 1, wherein the polyalkylene glycol is polyethylene glycol.

4. A composition comprising a mixture of the polyalkylene glycol lignin fatty acid ester according to claim 1 or 2 with an oil and / or an organic solvent.

5. A composition comprising a mixture of the polyalkylene glycol lignin fatty acid ester according to claim 3 and an oil and / or an organic solvent.

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