WO2022201366A1

WO2022201366A1 - Cellulose derivative

Info

Publication number: WO2022201366A1
Application number: PCT/JP2021/012277
Authority: WO
Inventors: 由紀子松尾; 寛樹谷口; 暁浩樋口
Original assignee: 株式会社ダイセル
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2022-09-29

Abstract

In this cellulose derivative, some or all of the hydroxyl groups in the cellulose are esterified by a carboxylic acid derived from a biomass resource. The carboxylic acid is preferably a C1-4 fatty acid.

Description

Cellulose derivative

The present invention relates to cellulose derivatives. In particular, the present invention relates to cellulose derivatives derived from 100% biomass resources.

Cellulose derivatives exhibit good thermoplasticity depending on the substituents introduced, so they can be applied to the production of molded products by melt molding, injection molding, and the like. Cellulose derivatives such as cellulose acetate are known to be biodegradable and decomposed by activated sludge. In recent years, due to growing interest in the global environment, biodegradable molded articles have been desired in various technical fields.

In recent years, due to the growing interest in environmental issues such as carbon neutrality and zero emissions, there is a demand for the development of materials derived from biomass resources instead of materials derived from petroleum resources. Fuels such as bioethanol and biodiesel have been developed as materials derived from biomass resources, and interest in bioplastics is increasing.

For example, Japanese Patent Application Laid-Open No. 2013-79395 (Patent Document 1), Japanese Patent No. 4380704 (Patent Document 2) and Japanese Patent No. 5303237 (Patent Document 3) disclose methods for producing biomass resource-derived polyesters. In this production method, at least one component of the dicarboxylic acid raw material and the diol raw material is said to be derived from biomass resources.

JP 2013-79395 A Patent No. 4380704 Patent No. 5303237

Examples of plant-derived biomass resources include woody biomass and herbaceous biomass. Cellulose obtained from wood, cotton, etc. can be said to be 100% derived from biomass resources. On the other hand, cellulose esters are obtained by esterifying cellulose with various carboxylic acids, and conventionally, chemicals derived from petroleum resources are used for these carboxylic acids. ASTM D6866 defines a method for measuring the radioactive carbon ¹⁴ C present in carbon derived from biomass resources and evaluating the degree of biomass of materials. The degree of biomass of cellulose ester esterified with carboxylic acid derived from petroleum resources is about 60%, although it depends on the degree of substitution.

For example, a cellulose derivative with a biomass content of 100% can be obtained by using carboxylic acid derived from biomass resources. However, conventionally, it has been known that chemicals derived from biomass resources using fermentation methods are often contaminated with impurities derived from raw materials and fermenting bacteria, and that there are many variations in quality. In particular, cellulose derivatives, whose decomposition temperature and melting temperature are close to each other, are feared to have adverse effects on molded products due to impurities, and their industrial use has been avoided.

The purpose of the present disclosure is to provide a 100% biomass resource-derived cellulose derivative by utilizing biomass resource-derived chemicals that have been avoided in the past.

In the cellulose derivative of the present disclosure, some or all of the hydroxyl groups of cellulose are esterified with carboxylic acid derived from biomass resources. Preferably, the carboxylic acid is a C1-C4 fatty acid.

Preferably, this cellulose derivative has a biomass degree of 100% calculated according to ASTM D6866.

Preferably, the cellulose derivative has a total degree of substitution with carboxylic acid of 1.8 or more.

The iron content of this cellulose derivative is preferably 0.7 ppm or more.

This cellulose derivative is a material derived from 100% biomass resources. Biomass resources are produced by, for example, plants fixing carbon dioxide in the atmosphere. Therefore, even if this cellulose derivative is incinerated after being used as a product, the amount of carbon dioxide generated does not increase as a whole, so it can contribute to the achievement of zero emissions.

An example of a preferred embodiment will be specifically described below. Each configuration and combination thereof in each embodiment is an example, and addition, omission, replacement, and other modifications of configuration are possible as appropriate without departing from the gist of the present disclosure. This disclosure is not limited by the embodiments, but only by the scope of the claims. Also, each aspect disclosed in this specification may be combined with any other feature disclosed in this specification.

In the specification of the present application, "X to Y" indicating the range means "X or more and Y or less". Also, unless otherwise noted, all test temperatures are room temperature (20°C ± 5°C).

[Cellulose derivative]
In the cellulose derivative of the present disclosure, some or all of the hydroxyl groups of cellulose are esterified with carboxylic acid derived from biomass resources. In other words, the cellulose derivative of the present disclosure has substituents derived from carboxylic acid obtained from biomass resources. This cellulose derivative does not have a substituent derived from a carboxylic acid obtained from petroleum resources.

Here, biomass is defined as "renewable, biologically derived organic resources excluding fossil resources". Biomass resources are produced by plants that fix carbon dioxide in the atmosphere. Examples include resource crops such as sugar cane and corn, unused biomass such as rice straw, wheat straw, and rice husks, and wood generated from construction. , sawmill leftovers, and food waste.

In the cellulose derivative of the present disclosure, cellulose derived from plant biomass such as wood is esterified with carboxylic acid derived from biomass resources. The catalyst, solvent, etc. used for the esterification are not introduced into the final cellulose derivative. Therefore, the cellulose derivative of the present disclosure is a 100% biomass resource-derived material that does not contain petroleum resource-derived raw materials. The cellulose derivative of the present disclosure, which is 100% derived from biomass resources, does not increase the total amount of carbon dioxide generated even if it is incinerated after being used as a product, so it can contribute to the achievement of zero emissions.

[Biomass degree]
The degree of biomass is the ratio of the radiocarbon ¹⁴ C concentration measured according to ASTM D6866-20 to the ¹⁴ C concentration of a standard substance (standard modern carbon). The ¹⁴ C concentration of petroleum resource-derived carbon is 0, and the ^{14 C concentration of the standard material is equivalent to the 14} ^C concentration of biomass resource-derived carbon. material content. That is, when the ¹⁴ C concentration of the measurement sample is the same as the ¹⁴ C concentration of standard modern carbon, the calculated biomass degree is 100%, meaning that this sample is 100% derived from biomass resources.

The cellulose derivative of the present disclosure has a biomass degree of 100% calculated according to ASTM D6866-20. By measuring the degree of biomass, it is possible to distinguish between the cellulose derivative of the present disclosure which is 100% biomass resource-derived and the cellulose derivative containing petroleum resource-derived raw materials.

Specifically, the biomass degree of the cellulose derivative of the present disclosure can be measured by the following method. First, the sampled measurement is burned to purify the generated carbon dioxide, which is then hydrogen-reduced with an iron catalyst to produce graphite (C). Next, the ¹⁴ C concentration ( ¹⁴ C/ ¹² C) in this graphite is quantified by accelerator mass spectrometry (AMS). For quantification, a ¹⁴ C-AMS dedicated device (manufactured by NEC) can be used. The ratio of the obtained ¹⁴ C concentration of the measurement sample to the ¹⁴ C concentration of the standard sample (standard modern carbon) is calculated as the degree of biomass.

[carboxylic acid]
The carboxylic acid that esterifies the cellulose derivative of the present disclosure is not particularly limited as long as it is obtained from biomass resources, and may be a saturated carboxylic acid or an unsaturated carboxylic acid. From the viewpoint that the obtained cellulose derivative is excellent in biodegradability, the number of carbon atoms in the carboxylic acid is preferably 1 or more and 4 or less. A preferred carboxylic acid is a fatty acid having 1 to 4 carbon atoms because of its low environmental impact. The carboxylic acid may have 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 2 to 3 carbon atoms.

The cellulose derivative of the present disclosure, in which some or all of the hydroxyl groups of cellulose are esterified with carboxylic acid derived from biomass resources, has an acyl group as a substituent. Preferred acyl groups are one or more selected from acetyl, propionyl and butyryl groups. Cellulose derivatives of the present disclosure may have other substituents obtained from biomass resources.

[Total degree of substitution]
The total degree of substitution of this cellulose derivative with carboxylic acid derived from biomass resources is not particularly limited, and is appropriately adjusted according to the application. As used herein, the total degree of substitution means the total degree of substitution by all acyl groups contained as substituents in the cellulose derivative of the present disclosure. From the viewpoint of facilitating melt molding, the total degree of substitution is preferably 1.8 or more, more preferably 1.85 or more, even more preferably 1.90 or more, still more preferably 2.0 or more. 1 or more is particularly preferred. From the viewpoint of obtaining high biodegradability, the total degree of substitution is preferably 2.8 or less, more preferably 2.75 or less, even more preferably 2.6 or less, even more preferably 2.5 or less. 4 or less is particularly preferred. Especially when biodegradability is important, the total degree of substitution is preferably 2.3 or less. In order to achieve both melt moldability and biodegradability, a cellulose derivative having a total degree of substitution of 1.9 or more and 2.6 or less is preferable.

The total degree of substitution of the cellulose derivative may be from 1.8 to 2.8, from 1.8 to 2.75, from 1.8 to 2.6, from 1.8 to 2.6. 5, may be from 1.8 to 2.4, may be from 1.8 to 2.3, may be from 1.85 to 2.8, may be from 1.85 to 2.75 may be from 1.85 to 2.6, may be from 1.85 to 2.5, may be from 1.85 to 2.4, may be from 1.85 to 2.3 well, may be from 1.9 to 2.8, may be from 1.9 to 2.75, may be from 1.9 to 2.6, may be from 1.9 to 2.5, 1.9 to 2.4, 1.9 to 2.3, 2.0 to 2.8, 2.0 to 2.75; may be from 0 to 2.6, may be from 2.0 to 2.5, may be from 2.0 to 2.4, may be from 2.0 to 2.3, may be from 2.1 to 2.8, 2.1 to 2.75, 2.1 to 2.6, 2.1 to 2.5, 2.1 to 2.5. It may be 4, and it may be 2.1 to 2.3. When durability in the environment is required and biodegradability is not preferred, the total degree of substitution of the cellulose derivative is preferably 2.6 or more, more preferably 2.7 or more, and particularly preferably 2.8 or more. The cellulose derivative of the present disclosure may also be water-soluble, in which case the preferred total degree of substitution is 0.4-0.9.

The total degree of substitution of the cellulose derivative is the sum of the degrees of acyl substitution at the 2-, 3- and 6-positions of the glucose ring, and can be measured by the following method. For example, it can be measured by the NMR method according to the method of Tezuka (Carbonydr. Res. 273, 83 (1995)). That is, the free hydroxyl groups of the cellulose derivative are acylated with a carboxylic acid anhydride in pyridine. The type of carboxylic acid anhydride used here should be selected according to the purpose of analysis. For example, when analyzing the butyryl substitution degree of cellulose butyrate, acetic anhydride is preferred. In addition, for example, acetic anhydride is good when analyzing the degree of butyryl substitution of cellulose acetate butyrate, and butyric anhydride is good when analyzing the degree of acetyl substitution. The obtained sample is dissolved in deuterated chloroform and the ¹³ C-NMR spectrum is measured. For example, when the substituent is an acetyl group or a butyryl group, the carbon signal of the acetyl group is in the region of 169 ppm to 171 ppm in the order of 2-, 3-, and 6-positions from the high magnetic field, and the carbon signal of the butyryl group is , 171 ppm to 173 ppm in the order of 2nd, 3rd and 6th positions from the high magnetic field side. As another example, when a cellulose derivative having a propionyl group or a cellulose derivative having no propionyl group is treated with propionic anhydride to analyze the degree of propionyl substitution, the signal of the carbonyl carbon of the propionyl group is from 172 ppm. They appear in the same order in the 174 ppm region. Since the total degree of substitution of the cellulose derivative treated with carboxylic anhydride by Tezuka's method or a similar method is 3.0, the carbonyl carbon signal of the acyl group originally possessed by the cellulose derivative and the carbonyl of the acyl group introduced by the carboxylic anhydride treatment The sum of the areas of the signals is normalized to 3.0, and the abundance ratio of the acetyl group, butyryl group and propionyl group at the corresponding positions (in other words, the area ratio of each signal) is obtained, which is the glucose in the cellulose derivative. It can be each acetyl, butyryl or propionyl degree of substitution at the 2-, 3- and 6-positions of the ring. Needless to say, substituents containing acyl groups that can be analyzed by this method are only substituents that do not correspond to the carboxylic anhydride used for the treatment for analytical purposes. In addition to ¹³ C-NMR, it can also be analyzed by ¹ H-NMR.

However, the total degree of substitution at the 2-, 3- and 6-positions of the glucose ring of the sample cellulose derivative is 3.0, and the substituents are all limited substituents such as acetyl and butyryl groups. If this is known in advance, the NMR spectrum can be measured by directly dissolving the sample in deuterated chloroform, excluding the propionylation step. If the substituents are all acetyl and butyryl groups, the carbon signals of the acetyl groups are in the region from 169 ppm to 171 ppm in the order 2, 3, 6 from the high field, as in the case involving the step of propionylation. , the butyryl group carbon signals appear in the same order in the region from 171 ppm to 173 ppm, so from the abundance ratio of the acetyl group and butyryl group at the corresponding positions (in other words, the area ratio of each signal), the glucose in the cellulose derivative Each degree of acetyl and butyryl substitution at the 2-, 3- and 6-positions of the ring can be determined.

[Weight average molecular weight and molecular weight distribution]
The weight average molecular weight (Mw) of the cellulose derivative of the present disclosure is not particularly limited, and can be appropriately selected depending on the application. For example, when applied to melt molding, the weight-average molecular weight of the cellulose derivative is preferably 100,000 or more, more preferably 120,000 or more, from the viewpoint of obtaining molded articles having excellent strength. The weight average molecular weight of the cellulose derivative is preferably 1,500,000 or less, more preferably 1,200,000 or less, from the viewpoint of obtaining appropriate fluidity when melted. When biodegradability is emphasized, the weight average molecular weight of the cellulose derivative is preferably 1,000,000 or less, more preferably 800,000 or less, more preferably 500,000, from the viewpoint of obtaining high biodegradability. More preferred are:

The molecular weight distribution (molecular weight distribution Mw/Mn obtained by dividing the weight average molecular weight Mw by the number average molecular weight Mn) of the cellulose derivative of the present disclosure is preferably 1.0 to 5.0, more preferably 1.3 to 4.0. 0.5 to 3.0 are particularly preferred. When the molecular weight distribution is within this range, the melt fluidity is improved.

The weight average molecular weight Mw and the molecular weight distribution Mw/Mn can be measured by a high performance liquid chromatography system in which a gel filtration column is connected to a detector for detecting refractive index and light scattering. As a high performance liquid chromatography system, for example, Shodex GPC SYSTEM-21H can be used. As a detector, for example, a differential refractive index detector (RI) can be used. The measurement conditions are as follows.
Solvent: Dichloromethane Column: TSKgel GMHXL (7.8 x 300 mm) Double guard column: TSKgel guardcolumn HXL-H
Sample concentration: 2000 ppm
Flow rate: 0.8mL/min
Sample injection volume: 100 μL
Standard sample: PMMA (molecular weight 1850, 7360, 29960, 79500, 201800, 509000, 625500)
Column temperature: 28°C

[Iron content]
The cellulose derivative of the present disclosure may have an iron content of 0.7 ppm or more, and may be 1.0 ppm or more, with an upper limit of 5.0 ppm. Carboxylic acids derived from biomass resources may contain various impurities mixed in raw materials or during manufacturing processes. Compared with the carboxylic acid derived from petroleum resources, the content of iron presumed to be mixed from the manufacturing equipment is particularly high. Iron is a compound that affects the esterification reaction described below. However, the present inventors have found that even a carboxylic acid derived from this biomass resource can yield a cellulose derivative with physical properties (processability, biodegradability, etc.) that are sufficiently industrially applicable.

The iron content in the cellulose derivative can be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) using an ICP emission spectrometer (Agilent 5110 manufactured by Agilent Technologies). The measurement conditions are plasma output: 1200 W, plasma gas: 12 L/min, carrier gas: 0.7 L/min, auxiliary gas: 1.0 L/min, measurement wavelength: 238.204 nm. can.

[Method for producing cellulose derivative]
The method for producing the cellulose derivative of the present disclosure is not particularly limited as long as carboxylic acid derived from biomass resources is used for esterification of hydroxyl groups of cellulose. For example, the cellulose derivative of the present disclosure can be obtained by reacting a raw material cellulose with a carboxylic acid obtained from a biomass resource in an amide solvent such as dimethylformamide in the presence of p-toluenesulfonyl chloride. According to this method, p-toluenesulfonyl chloride and amide solvent acting as a catalyst are not introduced into the cellulose derivative. Therefore, a cellulose derivative with a biomass degree of 100% can be obtained.

(carboxylic acid)
The method for obtaining carboxylic acid from biomass resources is not particularly limited, and conventionally known methods are used. For example, a method of producing carboxylic acid from sugars contained in woody biomass using microorganisms such as acetic acid bacteria is known. Specifically, it is a method of culturing acetic acid bacteria in a liquid medium containing saccharides extracted from biomass resources, and distilling and concentrating the obtained culture solution containing acetic acid. A method of fixing carbon dioxide in the air with biomass such as algae and recovering carboxylic acid, which is an intracellular metabolite, may be used. Alternatively, bioacetic acid may be obtained by reacting carbon monoxide obtained by gasifying woody biomass with biomethanol.

(raw material cellulose)
Raw material cellulose used in the method for producing a cellulose derivative of the present disclosure includes wood pulp (softwood pulp, hardwood pulp); cotton linter; microcrystalline cellulose; regenerated cellulose such as rayon and cellophane; powdered cellulose; microfibrillated cellulose; A fiber or the like can be used. It is also possible to use bacterial cellulose synthesized using a cellulose-producing bacterium or an enzyme derived from the bacterium. You may use 2 or more types together.

If necessary, the raw material cellulose can be wet- or dry-pulverized using a mixer, disc refiner, or the like. For the purpose of improving reactivity, the raw material cellulose may be pretreated. As the pretreatment, a method of immersing the raw material cellulose in water and/or carboxylic acid is preferred. When carboxylic acid is used, it is preferable to use carboxylic acid derived from biomass resources.

(Esterification step)
In the esterification step, raw material cellulose, p-toluenesulfonyl chloride, and carboxylic acid derived from biomass resources are added to an amide-based solvent and heated with stirring to introduce acyl groups into the hydroxyl groups of cellulose. The total degree of substitution of the resulting cellulose derivative can be adjusted by adjusting the amount of carboxylic acid added, heating conditions, and the like. From the viewpoint of reaction efficiency, the heating temperature is preferably 40 to 100°C, more preferably 50 to 80°C. The heating time is preferably 2 to 20 hours, more preferably 2 to 10 hours, although it depends on the amount of treatment.

(Washing/drying process)
After completion of the esterification reaction, the reaction solution is added to methanol, the precipitate is filtered off, the product obtained is washed with water and/or methanol, and then dried to obtain the cellulose derivative of the present disclosure. A known method is used for the washing and drying method. As methanol for washing, biomethanol obtained from biomass resources is preferred.

(Other embodiments)
After dehydrating the carboxylic acid derived from biomass resources using a known method, the cellulose of the present disclosure is obtained by esterifying the raw cellulose using an acid catalyst such as sulfuric acid with the carboxylic anhydride as an acylating agent. Derivatives may be obtained. The cellulose derivative of the present disclosure may be obtained by further esterifying the cellulose derivative obtained by esterification with another carboxylic acid. A cellulose derivative of the present disclosure having a desired degree of substitution may be obtained by de-esterifying a cellulose derivative obtained by esterification to adjust the degree of substitution.

Although the effects of the present disclosure will be clarified by examples below, the present disclosure should not be interpreted in a limited manner based on the description of the examples.

[Example 1]
500 mL of ion-exchanged water was added to 10 g of wood pulp, and the mixture was immersed for 1 hour, followed by suction filtration to obtain a filter cake. After adding 500 mL of dimethylformamide (manufactured by Nacalai) to this filter cake and stirring, the procedure of collecting the filter cake by suction filtration was repeated a total of three times. After that, the entire amount of the obtained filter cake was put into a separable flask (capacity 1 L) equipped with a three-one motor, a reflux condenser, a thermometer and a dropping funnel, and 300 mL of dimethylformamide and 71 g of p-toluenesulfonyl chloride (Nacalai company) was added. While stirring at room temperature, 22 g of acetic acid (manufactured by Aldrich, from potatoes) was added dropwise. After stirring at 70° C. for 4 hours, the mixture was allowed to cool to room temperature. By adding the obtained reaction solution to 3 L of methanol, the reaction product was precipitated, and a white solid was separated by suction filtration. After washing the resulting white solid three times with ion-exchanged water, it was dried by heating at 80° C. for 12 hours to obtain 11 g of the cellulose derivative of Example 1. A portion was sampled and subjected to ¹³ C-NMR spectrum measurement to confirm that it was cellulose acetate with a total degree of substitution of 2.6.

[Example 2]
10 g of the cellulose derivative of Example 1 was put into a separable flask (capacity 1 L) equipped with a three-one motor, a reflux condenser, a thermometer and a dropping funnel, and 300 mL of dimethylformamide and 6 g of p-toluenesulfonyl chloride were added. . While stirring at room temperature, 5 g of propionic acid (manufactured by Aldrich, derived from sheep) was added dropwise. After stirring at 70° C. for 4 hours, the mixture was cooled to room temperature. By adding the obtained reaction solution to 3 L of methanol, the reaction product was precipitated, and a white solid was separated by suction filtration. The resulting white solid was washed with ion-exchanged water three times and then dried by heating at 80° C. for 12 hours to obtain 11.3 g of the cellulose derivative of Example 2. A portion was sampled and subjected to ¹³ C-NMR spectrometry to confirm that it was cellulose acetate propionate with a degree of acetyl substitution of 2.6 and a degree of propyl substitution of 0.3.

[Example 3]
11.5 g of the cellulose derivative of Example 3 was obtained in the same manner as in Example 2, except that 6 g of butyric acid (manufactured by Aldrich, derived from sugar cane) was used instead of propionic acid. A portion was sampled and subjected to ¹³ C-NMR spectroscopy to confirm that it was cellulose acetate butyrate with a degree of acetyl substitution of 2.6 and a degree of butyryl substitution of 0.2.

[Comparative Example 1]
10.8 g of the cellulose derivative of Comparative Example 1 was added in the same manner as in Example 1, except that acetic acid derived from petroleum resources (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of acetic acid (manufactured by Aldrich, derived from potatoes). Obtained. A portion was sampled and subjected to ¹³ C-NMR spectrometry to confirm that it was cellulose acetate with an acetyl substitution degree of 2.6.

[Example 4]
First, woody biomass was pulverized to 20 mm or less, supplied to a gasification furnace (circulating fluidized bed), and gasified by adding air and steam to raise the temperature. Ash and the like in the obtained gas was separated by a high-temperature dust collector, and after the contained tar was decomposed by a catalyst, the gas was cooled to 200°C by a gas cooling device. After the components that precipitated out during the cooling process were removed with a low-temperature dust collection facility, the gas from which harmful acid and alkaline substances were removed with a wet gas purification facility was introduced into the methanol synthesis facility. After the gas was pressurized to the pressure required for synthesis at the methanol synthesis facility, trace amounts of sulfur and other substances remaining in the gas were removed, and biomethanol was synthesized through a catalytic reaction.

Separately, carbon monoxide was obtained by burning woody biomass. This carbon monoxide was reacted with the aforementioned biomethanol to obtain bioacetic acid by the Monsanto method. Acetic anhydride was obtained from the obtained bioacetic acid through a ketene furnace.

The cellulose derivative of Example 4 was obtained by reacting cellulose (wood pulp) with this acetic anhydride as an acetylating agent and the aforementioned bioacetic acid as a solvent in the presence of a sulfuric acid catalyst. Specifically, 100 parts by weight of raw material pulp (cotton linter pulp, α-cellulose content of 98% by weight) is pulverized with a mixer, then 500 parts by weight of bioacetic acid is sprinkled and mixed at 60° C. for 2 hours for pretreatment. performed. Thereafter, the raw material pulp after pretreatment was mixed with 250 parts by weight of acetic anhydride and 10 parts by weight of sulfuric acid, and then acetylated by holding at 70° C. for 12 minutes. Next, 50 parts by weight of an aqueous magnesium acetate solution having a concentration of 20% by weight was added, and the reaction solution was kept sealed at 150° C. for 1 hour, and then poured into dilute acetic acid to obtain a precipitate. After washing the precipitate with ion-exchanged water, it was dried at 100° C. to obtain 130 g of a cellulose derivative. A portion was sampled and subjected to ¹³ C-NMR spectrometry to confirm that it was cellulose acetate with an acetyl substitution degree of 2.6.

<Total degree of substitution>
The total degree of substitution of the cellulose derivatives of Examples 1-4 and Comparative Example 1 was quantified by measuring ¹³ C-NMR spectra in deuterated chloroform according to the method described above. The results obtained are shown in Table 1 below.

[Weight average molecular weight Mw]
The weight average molecular weights of the cellulose derivatives of Examples 1-4 and Comparative Example 1 were measured by gel permeation chromatography (GPC) according to the method described above. The results obtained are shown in Table 1 below as Mw.

[Iron content]
The iron content of the cellulose derivatives of Examples 1-4 and Comparative Example 1 was quantified by inductively coupled plasma atomic emission spectrometry (ICP-AES) according to the method described above. The results obtained are shown in Table 1 below as Fe (ppm).

[Biomass degree]
The biomass degrees of the cellulose derivatives of Examples 1-4 and Comparative Example 1 were measured by radiocarbon concentration measurement (AMS measurement) according to the method described above. The percentage of ¹⁴ C in sample carbon relative to standard modern carbon is shown in Table 1 below as biomass degree (%). If it exceeds 100%, it is uniformly 100%.

As shown in Table 1, the biomass degree of all the cellulose derivatives of Examples was 100%, confirming that they are 100% biomass resource-derived materials. From this evaluation result, the superiority of the present invention is clear.

The cellulose derivative according to the present disclosure can be applied to various fields by changing the type of substituent, the degree of substitution, the molecular weight, etc., depending on the application.

Claims

A cellulose derivative in which some or all of the hydroxyl groups of cellulose are esterified with carboxylic acid derived from biomass resources.
The cellulose derivative according to claim 1, wherein the carboxylic acid is a fatty acid having 1 to 4 carbon atoms.
The cellulose derivative according to claim 1 or 2, which has a biomass degree of 100% calculated according to ASTM D6866-20.
The cellulose derivative according to any one of claims 1 to 3, wherein the total degree of substitution with the carboxylic acid is 1.8 or more.
The cellulose derivative according to any one of claims 1 to 4, which has an iron content of 0.7 ppm or more.