Synthesis of carboxymethylcellulose with low gel particle size

Abstract

The present invention relates to carboxymethylcellulose (CMC) having low gel particle size, compositions containing CMC, methods for preparing the same, and uses thereof.

Description

Technical Field

[0001] The present invention relates to carboxymethyl cellulose (CMC), particularly carboxymethyl cellulose (CMC) having low gel particles, compositions containing CMC, methods for preparing the same, and its use, for example, in batteries.

Background Art

[0002] CMC is used in a wide variety of technical fields. Areas that benefit from the thickening and gel-forming properties of CMC are, for example, the petroleum industry (e.g., drilling fluids), the food industry, the pharmaceutical industry, the paper industry, the electrical and electronics industry, the textile industry, and the construction industry.

[0003] Due to the significant growth of electric vehicles and portable electronic devices, the demand for rechargeable batteries, particularly various types of lithium-ion batteries (LIB) in which CMC acts as a binder for graphite anodes, is increasing. However, undissolved CMC particles, such as gel particles in an aqueous CMC solution, tend to cause defects in the anode of the battery, thereby degrading the battery performance of LIB.

[0004] One method of reducing undissolved CMC particles is to filter the CMC solution as described in European Patent No. 2355215 B1.

[0005] Another method of manufacturing CMC with reduced gel particles is described in European Patent No. 3187509 B1, and the method includes a step of adding a base to adjust the pH of the reaction mixture to 8.0 to 9.0 and a step of performing a heat treatment at 40°C to 70°C for 30 minutes to 120 minutes.

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, there is still a need to prepare CMC having low undissolved CMC particles such as low gel particles.

[0007] To overcome the current challenge of providing CMC having low undissolved particles such as low gel particles, the inventors have shown that CMC having low gel particles can be obtained by using a method in which the alkalizing agent / monohaloacetic acid ratio is higher than 2, and the steps of adding a base to adjust the pH of the reaction mixture and heat-treating the reaction mixture are omitted.

[0008] Therefore, an object of the present invention is to provide a novel method for preparing a type of CMC having low gel particles. [Means for solving the problem]

[0009] This task involves the following steps: a) A step of suspending non-regenerated cellulose in a mixture of water / alcohol solvent, adding an alkalizing agent, reacting the non-regenerated cellulose with the alkalizing agent in the presence of water / alcohol solvent, and optionally adding hydrogen peroxide, b) A step of adding monohaloacetic acid or a salt thereof to the alkalized cellulose of step a), and reacting the alkalized cellulose of step a) with monohaloacetic acid or a salt thereof, c) A step of adding acid to the reaction mixture from step b) to adjust the pH of the reaction mixture to 6.0 to 8.0, d) After the completion of step c), a step to remove the solvent and This is resolved by a method for preparing carboxymethylcellulose (CMC), which includes, where the alkalizing agent / monohaloacetic acid ratio is greater than 2, and which further includes the steps of adding a base to adjust the pH of the reaction mixture after the completion of step d) and heat-treating the reaction mixture.

[0010] The present invention also relates to novel CMCs obtained and obtainable by the methods described herein.

[0011] The present invention further relates to carboxymethylcellulose (CMC) having a degree of substitution (DS) of 0.5 or less, and having a number of gel particles of less than 200 / 5cm×5cm, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, even more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less when measured in a 1% aqueous solution.

[0012] Another aspect of the present invention relates to a composition comprising carboxymethylcellulose obtained or obtainable by the method described herein, or a composition comprising carboxymethylcellulose as described herein, wherein the number of gel particles is 200 / 5cm×5cm or less, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, even more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less.

[0013] A further aspect of the present invention is the use of the compositions described herein as coating agents for battery electrodes.

[0014] Another aspect of the present invention is the use of carboxymethylcellulose as a thickener and / or coagulant, binder, stabilizer, emulsifier, film-forming agent, suspending agent, protective colloid, crystallization inhibitor, or enteric coating.

[0015] Further aspects of the present invention include the use of carboxymethylcellulose as a polymer component of crosslinking interface forming capsules in drilling fluids, e.g., petroleum drilling fluids; pharmaceutical dosage forms, e.g., capsules, tablets, solutions, suspensions, emulsions, creams and lotions; food products, e.g., structured, extruded or coated food products such as processed meat products, dairy products, bakery products, meat substitutes, dressings, sauces, marinades, soups and spreads; cosmetic applications, e.g., hair styling products, toothpaste, emulsions, creams and lotions; detergents; paper coatings or paper binding; welding electrodes; textile applications, e.g., textile printing and dyeing; household products, laundry and dishwashing, etc.; ceramic applications, e.g., clay bodies and tile manufacturing; adhesives; paints; and construction applications, e.g., gypsum or cement-based dry mortar applications. [Modes for carrying out the invention]

[0016] Detailed embodiments of the present invention are described below. Some of the detailed embodiments are discussed in separate sections. This is for ease of reference and is not limiting in any way. Unless otherwise explicitly indicated in the context, all embodiments described below apply equally to all embodiments of the present invention.

[0017] As used herein, the terms "CMC" or "carboxymethylcellulose" refer to carboxymethylcellulose or its salts, for example, the formula -CH2CO2A (wherein A is hydrogen or K). + monovalent cations such as, or preferably Na + This includes cellulose substituted with the group (which is ). Examples of carboxymethylcellulose salts may include metal salts such as sodium carboxymethylcellulose salt.

[0018] The method for preparing carboxymethylcellulose according to the present invention involves the following steps: a) A step of suspending non-regenerated cellulose in a mixture of water / alcohol solvent, adding an alkalizing agent, reacting the non-regenerated cellulose with the alkalizing agent in the presence of water / alcohol solvent, and optionally adding hydrogen peroxide, b) A step of adding monohaloacetic acid or a salt thereof to the alkalized cellulose of step a), and reacting the alkalized cellulose of step a) with monohaloacetic acid or a salt thereof, c) A step of adding acid to the reaction mixture from step b) to adjust the pH of the reaction mixture to 6.0 to 8.0, d) After the completion of step c), a step to remove the solvent and This includes, where the alkalizing agent / monohaloacetic acid ratio is greater than 2, and does not further include the steps of adding a base to adjust the pH of the reaction mixture after the completion of step d) and heat-treating the reaction mixture.

[0019] In this specification, the term "regenerated cellulose" refers to cellulose prepared by regeneration (i.e., returning to a solid form) from a solution containing dissolved cellulose fibers. The term "unregenerated cellulose" refers to cellulose, typically cellulose fibers, that have not undergone a process of dissolving in a solvent and then regeneration (i.e., recovery of cellulose in a solid form) from that solution. In particular, "unregenerated cellulose" refers to cellulose that has not been recovered from a cellulose xanthogenet solution, or a cellulose / cupramonium solution, or a cellulose solution in N-methylmorpholine-N-oxide.

[0020] The non-regenerated cellulose used in the preparation of CMC is natural cellulose such as cotton linters and wood pulp, for example, hardwood or softwood pulp. Typically, cotton linters or wood pulp are used depending on the desired application of the CMC. The pulp according to the present invention has a critical viscosity number measured according to ISO 5351:2010 of 50 to 300 mL / g, preferably 1000 to 3000 mL / g, and more preferably 300 to 1000 mL / g.

[0021] The essential steps of the method for preparing carboxymethyl cellulose are to alkalize cellulose by reaction with an alkalizing agent (alkalization step (a)), and to add monohaloacetic acid to cause etherification of the alkalized cellulose (carboxymethylation step (b)).

[0022] Cellulose is first alkalized in the alkalization step (a) in the presence of water and alcohol (isopropyl alcohol and / or methanol), and then monohaloacetic acid is added in the carboxymethylation step. In the alkalization step, the single components (e.g., cellulose, water, alcohol, alkalizing agent) can be added in any order. However, it is preferred to mix cellulose with water, isopropyl alcohol, and optionally methanol in the first step, and then add the alkalizing agent in a subsequent step.

[0023] There are various options for the method of contacting cellulose with the alkalizing agent. Preferably, cellulose powder is used as the starting material. Typically, the cellulose powder is suspended (slurried) in a solvent / water mixture containing water, isopropyl alcohol, and / or methanol before adding the alkalizing agent as a solid or aqueous solution.

[0024] According to a preferred slurry method, the alkalization step (a) is typically carried out at a temperature within the range of 10 - 40°C, preferably 15 - 40°C, more preferably 15 - 30°C, even more preferably 18 - 25°C, and most preferably about 20°C. The typical reaction time for the alkalization step ranges from 15 - 120 minutes, preferably 40 - 100 minutes, more preferably 50 - 80 minutes, depending on the reaction temperature. In one embodiment, the alkalization step is carried out at about 20°C for 50 - 70 minutes, preferably 60 minutes.

[0025] In the carboxymethylation step (b), monohaloacetic acid or a salt thereof, preferably a sodium salt, can be added undiluted, or as a solution, preferably as an aqueous solution, or as a solution in water and isopropyl alcohol and optionally methanol. The carboxymethylation step is typically carried out at a temperature in the range of 40 to 100°C, preferably 50 to 90°C, more preferably 60 to 80°C, and most preferably about 70°C. In preferred embodiments, the monohaloacetic acid is already added to the reaction mixture before the carboxymethylation temperature is reached; more preferably, the monohaloacetic acid is added before the heating step begins or within the first few minutes of the heating step, generally at the temperatures described above for the alkalizing step, for example, 15 to 40°C. Early addition of monohaloacetic acid at lower temperatures can avoid undesirable decomposition of cellulose (resulting in a decrease in viscosity) that may occur at higher temperatures in the absence of monohaloacetic acid. After the desired temperature (carboxymethylation temperature) of the carboxymethylation step described above is reached, the carboxymethylation temperature is typically maintained for a period of 0 to 180 minutes, preferably 20 to 140 minutes.

[0026] The product obtained from the carboxymethylation step, i.e., etherification, is a sodium or potassium salt of carboxymethylcellulose, depending on the alkalizing agent used. In a preferred embodiment, the CMC salt is neutralized by adding an acid, preferably an organic acid such as acetic acid or formic acid, more preferably acetic acid. Here, "neutralization" means adjusting the pH value to 6-9, preferably 6-8.

[0027] Next, the CMC is separated from the reaction mixture and, if necessary, purified and dried according to the intended end use. Purification is carried out according to standard methods well known to those skilled in the art. For example, the CMC can be washed with organic solvents including mixtures of organic solvents such as methanol, acetone, methanol / water mixtures, acetone / methanol mixtures, and methanol / isopropyl alcohol / water mixtures, as well as solvent (mixture) / water mixtures.

[0028] The alkalizing agent is preferably NaOH, KOH, or a mixture thereof. In one embodiment, NaOH is used as the alkalizing agent. In another embodiment, KOH is used as the alkalizing agent. In the latter case, residual K in the generated CMC + The ions are preferably Na in a subsequent step. + It is exchanged by ions.

[0029] Monohaloacetic acid can be used as a free acid or in the form of a salt thereof. Preferably, monochloroacetic acid or a salt thereof is used in the method of the present invention, including all of the preferred embodiments described below.

[0030] According to the present invention, it is important to observe the molar ratio of each of the above components when preparing CMC.

[0031] The alkalizing agent / monohaloacetic acid ratio is 2.1 to 20, preferably 2.5 to 20, and more preferably 4.0 to 20.

[0032] In other embodiments, the alkalizing agent / monohaloacetic acid ratio is 2.6-20, 2.8-20, 3.0-20, or 3.5-20.

[0033] In another embodiment, the alkalizing agent / monohaloacetic acid ratio is 2.1 to 15, preferably 2.5 to 15, and more preferably 4.0 to 15.

[0034] In other embodiments, the alkalizing agent / monohaloacetic acid ratio is 2.6-15, 2.8-15, 3.0-15, or 3.5-15.

[0035] In a further embodiment, the alkalizing agent / monohaloacetic acid ratio is 2.1 to 10, preferably 2.5 to 10, and more preferably 4.0 to 10.

[0036] In other embodiments, the alkalizing agent / monohaloacetic acid ratio is 2.6-10, 2.8-10, 3.0-10, or 3.5-10.

[0037] In certain embodiments, the alkalizing agent is added as a solid.

[0038] "Solvent" and similar terms refer to a substance that dissolves other substances (solutes) to form a mixture (solution) in which they are essentially uniformly dispersed at the molecular or ionic level.

[0039] In a preferred embodiment of the present invention, non-regenerated cellulose is reacted with an alkalizing agent in the presence of a water / alcohol solvent.

[0040] In a particular embodiment of the present invention, the alcohol is isopropyl alcohol and / or methanol.

[0041] Furthermore, in certain embodiments, 10 to 100 moles of alcohol are used in the methods described herein based on 1 mole of anhydrous glucose units of cellulose.

[0042] In a further embodiment, the present invention also relates to carboxymethylcellulose obtained or obtainable by the method described herein.

[0043] When preparing an aqueous solution of CMC, gel particles derived from the CMC may remain in the solution as undissolved material. Mechanical drying or wet grinding processes for the CMC can reduce the size of the gel particles in the aqueous solution, but this may result in coating separation or pinholes on the electrodes.

[0044] Surprisingly, the compositions disclosed herein were found to have a very low amount of gel particles, for example, less than 200 / 5cm×5cm, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less.

[0045] The carboxymethylcellulose (CMC) disclosed herein has a degree of substitution (DS) of 0.5 or less and a gel particle count of less than 200 / 5cm×5cm, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less.

[0046] In certain embodiments, carboxymethylcellulose (CMC) has a degree of substitution (DS) of less than 0.4.

[0047] The degree of substitution (DS) is the average number of OH groups substituted on a single anhydrous glucose unit. This is determined according to ASTM D 1439-03, "Standard Test Methods for Sodium Carboxymethylcellulose; Degree of Etherification, Test Method B: Nonaqueous Titration." When a solid sample of CMC is treated with glacial acetic acid at its boiling point, an amount of acetate ions corresponding to sodium carboxymethyl groups is released. These acetate ions can be titrated as a strong base in acetic anhydride using a perchloric acid standard solution. The titration endpoint is determined by potentiometric measurement. Other alkali salts of carboxylic acids (e.g., sodium glycolate and disodium diglycolate) behave similarly and can be co-titrated.

[0048] The present invention also relates to compositions comprising carboxymethylcellulose as described herein.

[0049] The compositions containing CMC disclosed herein have a number of gel particles of 200 / 5cm×5cm or less, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less.

[0050] In one embodiment of the present invention, the novel CMC typically has a viscosity of at least 100 mPa·s, preferably at least 200 mPa·s, more preferably at least 600 mPa·s, and most preferably at least 100 mPa·s, when measured as a 1% by weight aqueous solution as described below. The viscosity is generally up to 40,000 mPa·s, preferably up to 30,000 mPa·s, preferably up to 25,000 mPa·s, and more preferably up to 20,000 mPa·s, when measured as a 1% by weight aqueous solution as described below.

[0051] To determine the viscosity, a 1% solution was prepared as follows (total solution volume 300g): 294g of deionized water (minus the water in the CMC) was placed in a 500ml screw-cap bottle kept at a constant temperature of 25°C. Next, 6g (dry weight) of CMC was uniformly stirred at a rotation speed of approximately 1300 rpm to prepare the solution. The solution was then stirred at a constant rotation speed (approximately 1000-1500 rpm) and a temperature of 25°C for 1 hour and 30 minutes. After that, stirring was stopped, and the solution was held at 25°C for 30 minutes without stirring, and then the viscosity was determined. The viscosity of the solution was measured using a Brookfield LVT viscometer at 30 rpm and 25°C, with spindle 3 used for Examples 1-3 and 7, and spindle 2 used for Examples 4-6 and 8-11.

[0052] A 1 wt% aqueous solution of CMC is prepared in the same manner as described above for viscosity analysis and further rolled on a roller device for 24 hours. Transmittance and turbidity are analyzed using a Turbidimeter 2100AN (Hach Company, Loveland, Colorado, USA) with tungsten filament lamp emission having wavelengths of 300–1000 nm. Transmittance is an optical analysis of light passing through the sample cell (diameter: 24 mm) at a specified wavelength (610 nm in this case). It is expressed as the percentage of transmitted light. This system is calibrated against water (100% transmittance). The results are the average of 8 measurements. Turbidity is an analysis of scattered light passing through the sample cell (diameter: 24 mm) and is expressed in NTU (nephelometric turbidity units) according to USEPA Method 180.1. The analysis is performed against a formazin standard (StablCal®, catalog number 2659505) in the range of less than 0.1 NTU to 7500 NTU. A USEPA Method 180.1 filter module (catalog number 3031200, 400-600 nm) was used. The results are the average of 10 measurements.

[0053] Furthermore, this specification discloses battery electrodes in which the electrodes are coated with the compositions disclosed herein. Furthermore, this specification discloses lithium-ion battery electrodes, such as secondary battery electrodes, coated with the compositions disclosed herein. In one embodiment, the electrode is an anode. In yet another embodiment, the electrode is a cathode. Furthermore, this specification discloses a battery comprising the battery electrodes disclosed herein.

[0054] When used in relation to lithium-ion batteries, the term "active material" and similar terms refer to a substance that is a source of lithium ions or a substance that can accept lithium ions. In relation to the cathode of a lithium-ion cell, the active material is a source of lithium ions, such as lithium cobalt oxide or lithium manganese oxide. In relation to the anode of a lithium-ion cell, the active material is a lithium ion acceptor, such as graphite. Active materials are typically in the form of very small particles with a diameter of 100 nanometers to 100 micrometers.

[0055] When used in relation to lithium-ion batteries, "anode" and similar terms refer to the negative electrode in the discharge cycle. The anode is the electrode where oxidation reactions occur within the battery during discharge, meaning electrons are released and flow out of the battery.

[0056] The term "battery" and similar terms refer to a collection or assembly of cells in a usable state. A battery typically includes a suitable enclosure, electrical connections, and electronic devices to control and protect the cells from failures such as fire, thermal runaway, explosion, and discharge. The simplest battery is a single cell. Batteries are classified into primary batteries, i.e., non-rechargeable batteries, and secondary batteries, i.e., rechargeable batteries.

[0057] When used in relation to lithium-ion batteries, "binder polymer" and similar terms refer to a polymer that holds together active material particles within the electrodes of a lithium-ion battery, maintaining a strong connection between the electrodes and the contacts. Binder polymers are typically inert to substances that come into contact with lithium-ion batteries during discharge, charging, and storage.

[0058] When used in relation to lithium-ion batteries, "cathode" and similar terms refer to the positive electrode in the discharge cycle. Lithium in lithium-ion batteries resides in the cathode. The cathode is the electrode where a reduction reaction occurs during discharge.

[0059] The term "cell" and similar terms refer to a basic electrochemical unit that includes electrodes, separators, and electrolytes.

[0060] When used in relation to lithium-ion batteries, the term "conductive agent" and similar terms refer to substances that facilitate the movement of ions between the electrodes of a cell. Carbon-based compounds and materials, such as acetylene black, carbon nanotubes, and carbon-based polymers, are typical conductive agents used in lithium-ion batteries.

[0061] When used in relation to lithium-ion batteries, "electrolyte" and its synonyms refer to a substance that transports positively charged lithium ions through a separator, either from anode to cathode or vice versa.

[0062] The term "lithium-ion battery" and its synonyms refer to a rechargeable (i.e., secondary) battery in which lithium ions move from the negative electrode to the positive electrode during discharge and in the reverse direction during charging. Lithium-ion batteries use an intervening lithium compound as a single electrode material, rather than the metallic lithium used in non-rechargeable lithium batteries (also known as primary batteries). An electrolyte that enables ion movement and two electrodes are the components of a lithium-ion battery cell.

[0063] When used in relation to lithium-ion batteries, the term "separator" and similar terms refer to a porous thin film that physically separates the anode and cathode. The primary function of a separator is to facilitate the movement of lithium ions within the cell while preventing physical contact between the anode and cathode. Separators are typically simple plastic films, such as polyethylene or polypropylene, or ceramics, with pore sizes designed to allow the passage of lithium ions.

[0064] The CMC according to the present invention has been shown to be very useful as a coating agent for battery electrodes, such as lithium-ion battery electrodes, and preferably secondary battery electrodes. In one embodiment, the battery electrode is a cathode or an anode.

[0065] In one embodiment, the present invention also relates to a battery in which electrodes are coated with the compositions described herein. In particular, the electrodes are lithium-ion electrodes. In specific cases, the battery electrodes are secondary battery electrodes. The electrodes can be anode or cathode.

[0066] Another aspect of the present invention is the use of carboxymethylcellulose as a thickener and / or coagulant, binder, stabilizer, emulsifier, film-forming agent, suspending agent, protective colloid, crystallization inhibitor, or enteric coating.

[0067] Further aspects of the present invention include the use of carboxymethylcellulose as a polymer component of crosslinking interface forming capsules in drilling fluids, e.g., petroleum drilling fluids; pharmaceutical dosage forms, e.g., capsules, tablets, solutions, suspensions, emulsions, creams and lotions; food products, e.g., structured, extruded or coated food products such as processed meat products, dairy products, bakery products, meat substitutes, dressings, sauces, marinades, soups and spreads; cosmetic applications, e.g., hair styling products, toothpaste, emulsions, creams and lotions; detergents; paper coatings or paper binding; welding electrodes; textile applications, e.g., textile printing and dyeing; household products, laundry and dishwashing, etc.; ceramic applications, e.g., clay bodies and tile manufacturing; adhesives; paints; and construction applications, e.g., gypsum or cement-based dry mortar applications. [Examples]

[0068] The following examples are provided for illustrative purposes only and are not intended to limit the scope of the following claims. Unless otherwise indicated, all parts and percentages are by weight.

[0069] First, cellulose powder was introduced into a dry 3-liter experimental reactor under ambient or nitrogen atmosphere, and then a solvent mixture of isopropyl alcohol, methanol, and water was added. Granular NaOH was added at 20°C with stirring, and stirring continued for 15 minutes, after which hydrogen peroxide was added at a concentration of 3% in water (Examples 7-11); stirring continued at 20°C for a total of 60 minutes. The reaction mixture was then heated to 70°C within 40 minutes, and monochloroacetic acid was added as a 79.6 wt% aqueous solution during the first few minutes of the heating stage. The temperature was maintained at 70°C for 120 minutes during the carboxymethylation step, and then the reaction mixture was cooled to 20°C within approximately 60 minutes. The pH of the cooled reaction mixture was adjusted to 7.5 with acetic acid, and then the solution was filtered. The filtered residue was then washed at least five times with 2 L of isopropanol / methanol / water mixture (isopropanol / methanol / water weight ratio 5:3:2) until no chloride ions were detected in the filtrate. This was followed by a final washing step using pure methanol. The washed samples were dried overnight in a drying cabinet at 55°C, and then ground using a laboratory mill.

[0070] The degree of substitution of the obtained CMC was determined as described in the summary section of the specification. A 1% by weight CMC sample solution was also prepared, and its viscosity, turbidity, and transmittance were determined as described in the summary section of the specification.

[0071] Determination of the number of gel particles To determine the number of gel particles according to this description, the gel was observed by a wet coating method by coating a surface-treated PET film with a CMC solution, and the repeatability coefficient was measured in a 5cm x 5cm square area. The CMC solution was prepared under the following detailed process: Approximately 1,000 grams of CMC powder were dispersed on the surface of aluminum foil in an automatic humidity tester (humidity analyzer MA37 from Sartorius AG, Germany). A humidity test was performed using the automatic test process at a temperature of 130°C. The CMC solution was prepared by adding 135.5 grams of deionized water to a metal cup of a high-speed mixer and mixing at a speed of 300 rpm. Then, approximately 1.5 grams of CMC powder was added to the water. After dispersing all the powder in the water, the mixing speed was increased to 4000 rpm and mixing continued for 30 minutes. Due to the high-speed mixing, a clear aqueous solution containing many bubbles was obtained. To remove the bubbles, the prepared CMC solution was stored at room temperature for 1 day. Next, a 5cm x 5cm square was cut from A4 size paper and covered with a PET film of the same size. A few drops of the prepared CMC solution were drawn from the middle / bottom of the CMC solution bottle and then dropped onto a closely spaced square area on the left side of the PET film. Subsequently, a knife blade with a 100-micrometer gap was used to cast from left to right. The wet coating of the CMC solution on the PET film was observed under LED light, and bright spots were identified as insoluble gels. To reduce errors in manual observation, the number of gels from each square was calculated and recorded by two people. As a tip for clarifying the observation, placing a glass plate between the A4 paper background and the PET film made the bright spots of the gels much clearer.

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] Table 4

Claims

1. (a) A step of suspending non-regenerated cellulose in a mixture of water / alcohol solvent, adding an alkalizing agent, reacting the non-regenerated cellulose with the alkalizing agent in the presence of the water / alcohol solvent, and optionally adding hydrogen peroxide, (b) A step of adding monohaloacetic acid or a salt thereof to the alkalized cellulose of step a), and reacting the alkalized cellulose of step a) with the monohaloacetic acid or a salt thereof, (c) A step of adding an acid to the reaction mixture in step b) and adjusting the pH of the reaction mixture to 6.0 to 8.0, (d) After the completion of step c), a step to remove the solvent and A method for preparing carboxymethylcellulose (CMC) containing, A method wherein the alkalizing agent / monohaloacetic acid ratio is greater than 2, and after the completion of step d), the method further includes the step of adding a base to adjust the pH of the reaction mixture and the step of heat-treating the reaction mixture.

2. The method according to claim 1, wherein the alkalizing agent / monohaloacetic acid ratio is 2.6-20, 2.6-15, 2.6-10, 2.8-20, 2.8-15, 2.8-10, 3.0-20, 3.0-15, 3.0-10, 3.5-20, 3.5-15, or 3.5-10.

3. The method according to claim 1, wherein the alkalizing agent / monohaloacetic acid ratio is 4.0 to 20, 4.0 to 15, or 4.0 to 10.

4. The method according to claim 1, wherein the alcohol in step a) is isopropyl alcohol and / or methanol.

5. The method according to any one of claims 1 to 4, wherein in step a), 10 to 100 moles of alcohol are used based on 1 mole of anhydrous glucose units of the cellulose.

6. The method according to any one of claims 1 to 5, wherein the alkalizing agent in step a) is sodium hydroxide (NaOH), potassium hydroxide (KOH), or a mixture thereof, preferably sodium hydroxide (NaOH).

7. The method according to any one of claims 1 to 6, wherein the alkalizing agent in step a) is added as a solid.

8. Carboxymethylcellulose that can be obtained by the method described in any one of claims 1 to 7.

9. Carboxymethylcellulose (CMC) having a degree of substitution (DS) of 0.5 or less, and having a number of gel particles of less than 200 / 5cm×5cm, more preferably 100 / 5cm×5cm or less, more preferably 50 / 5cm×5cm or less, more preferably 25 / 5cm×5cm or less, and most preferably 15 / 5cm×5cm or less when measured with a 1% aqueous solution.

10. The carboxymethylcellulose (CMC) according to claim 9, wherein the degree of substitution (DS) is less than 0.

4.

11. A composition comprising carboxymethylcellulose obtained or obtainable by the method of any one of claims 1 to 7, wherein the number of gel particles is 200 / 5cm × 5cm or less, 100 / 5cm × 5cm or less, more preferably 50 / 5cm × 5cm or less, more preferably 25 / 5cm × 5cm or less, or more preferably 15 / 5cm × 5cm or less, or carboxymethylcellulose according to claim 9 or 10.

12. Use of the composition according to claim 11 as a coating agent for battery electrodes.

13. The use according to claim 12, wherein the battery electrode is a lithium-ion battery electrode.

14. The use according to claim 12 or 13, wherein the battery electrode is a secondary battery electrode.

15. The use according to any one of claims 12 to 14, wherein the electrode is an anode.

16. The use according to any one of claims 12 to 14, wherein the electrode is a cathode.

17. A battery electrode in which the electrode is coated with the composition described in claim 11.

18. The battery electrode according to claim 17, wherein the battery electrode is a lithium-ion battery electrode.

19. The battery electrode according to claim 17 or 18, wherein the battery electrode is a secondary battery electrode.

20. The battery electrode according to any one of claims 17 to 19, wherein the electrode is an anode.

21. The battery electrode according to any one of claims 17 to 19, wherein the electrode is a cathode.

22. A battery comprising a battery electrode according to any one of claims 17 to 21.

23. Use of carboxymethylcellulose as a thickener and / or coagulant, binder, stabilizer, emulsifier, film-forming agent, suspending agent, protective colloid, crystallization inhibitor, or enteric coating.

24. Drilling fluids, e.g., petroleum drilling fluids; pharmaceutical dosage forms, e.g., capsules, tablets, solutions, suspensions, emulsions, creams and lotions; food products, e.g., structured, extruded or coated food products such as processed meat products, dairy products, bakery products, meat substitutes, dressings, sauces, marinades, soups and spreads; cosmetic applications, e.g., hair styling products, toothpaste, emulsions, creams and lotions; detergents; paper coatings or paper binding; welding electrodes; textile applications, e.g., textile printing and dyeing; household products, laundry and dishwashing, etc.; ceramic applications, e.g., clay bodies and tile manufacturing; adhesives; paints; and construction applications, e.g., gypsum or cement-based dry mortar applications; use of carboxymethylcellulose as a polymer component of crosslinking interface forming capsules.

Images