CN-121986201-A - Modified cellulose fiber and modified cellulose microfiber

Abstract

Provided is a novel cellulose microfiber which is not significantly limited in use or a cellulose fiber which is a raw material for cellulose microfiber. A modified cellulose fiber which is modified with a polycarboxylic acid group and has a first dissociating acid amount/second dissociating acid amount of 0.25 to 1.0 and a first dissociating acid amount of 0.35 mmol/g or more. A modified cellulose microfibril, characterized in that the modified cellulose fibre has an average fibre diameter of 100 nm or less.

Inventors

• LIU XIAOYUE

Assignees

• 大王制纸株式会社

Dates

Publication Date

20260505

Application Date

20241022

Priority Date

20231121

Claims (5)

1. 1. A modified cellulose fiber which is modified with a polycarboxylic acid group and has a first dissociating acid amount/second dissociating acid amount of 0.25 to 1.0 and a first dissociating acid amount of 0.35 mmol/g or more.
2. 2. The modified cellulose fiber according to claim 1, which is carbamated.
3. 3. The modified cellulose fiber according to claim 1, wherein the dispersion having a concentration of 0.2 mass% has a total light transmittance of 65% or more, and the dispersion having a concentration of 1.0 mass% has a B-type viscosity of 40000 cP or more.
4. 4. The modified cellulosic fiber of claim 1, wherein the polycarboxylic acid is citric acid.
5. 5. A modified cellulose microfiber according to any one of claims 1 to 4, wherein the modified cellulose fiber has an average fiber diameter of 100 nm or less.

Description

Modified cellulose fiber and modified cellulose microfiber Technical Field The present invention relates to modified cellulose fibers and modified cellulose microfibers. Background In recent years, nanotechnology has been attracting attention, which aims at miniaturizing a substance to a nanometer level to obtain new physical properties different from those of the existing substances. Cellulose microfibrils produced from pulp, which is a cellulose-based raw material, by chemical treatment, pulverization treatment, or the like are excellent in strength, elasticity, thermal stability, and the like, and are therefore expected to be used in industrial applications such as filter materials, filter aids, ion exchanger substrates, fillers for chromatographic analysis instruments, and fillers for blending resins and rubbers, and in applications such as blending agents for cosmetics such as lipsticks, powder cosmetics, and emulsion cosmetics. Further, cellulose microfibrils are excellent in water dispersibility, and are therefore expected to be used in various applications such as viscosity-maintaining agents for foods, cosmetics, paints and the like, reinforcing agents for food raw material green compacts, moisture-maintaining agents, food stabilizers, low-calorie additives, emulsion stabilizing aids and the like. Conventionally, in order to obtain such cellulose microfibrils, a method of mechanically defibrating cellulose fibers using a high-pressure homogenizer, a high-speed rotary homogenizer, an ultrasonic homogenizer, or the like has been employed (for example, refer to patent document 1). However, these methods require a large amount of energy to be consumed in performing the defibration. Accordingly, in order to reduce the energy required for defibration, a method of defibration by TEMPO oxidation has been proposed. However, this method has difficulty in economical aspects, and depyrogenation becomes a technical problem. Therefore, a phosphorylation method and the like have been proposed. However, if the technique is only relied on, there is a possibility that the technique may cause problems such as marine pollution. Therefore, other new technology proposals are required. However, as a technique different from the above-described method of modifying cellulose fibers, there has been a method of modifying cellulose fibers with citric acid (see patent documents 2 and 3). However, in patent document 2, the use of the dispersion is significantly limited because the citric acid is modified by boiling and the viscosity of the dispersion is low. In addition, the solution of patent document 3 has a problem of low transparency of the dispersion. In particular, in foods, cosmetics and the like, there is a need for a dispersion having high transparency, and the problem of increasing the transparency is unavoidable in addition to expanding the use of cellulose microfibrils. Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2010-216021 Patent document 2 Japanese patent application laid-open No. 2015-140403 Patent document 3 Japanese patent laid-open publication No. 2019-189792 Disclosure of Invention Technical problem to be solved by the invention The present invention aims to provide a novel cellulose microfiber which is not limited in use or a cellulose fiber which is a raw material of cellulose microfiber. Means for solving the problems The present inventors focused on a method of modifying cellulose fibers with citric acid in order to solve the above-mentioned problems. This is because citric acid is a substance of natural origin and has various advantages in that it can react under near neutral conditions, even under lower temperature conditions, and so on. However, as previously mentioned, the use of existing cellulose microfibrils based on citric acid modification is significantly limited. Accordingly, the present inventors have conducted various studies independently and repeatedly, and as a result, have found that cellulose fibers are liable to crosslink after being modified with citric acid, and that once the cellulose fibers crosslink, the fibers become thicker, and the viscosity and transparency are lowered. Based on such findings, the following means are conceivable. It should be noted that, although patent document 3 describes that "cellulose nanofibers" is regarded as fibers having a fiber diameter (or a fiber width) of several nanometers to several hundreds of nanometers in a word sense, the present specification is not limited to this size range. For example, fibers having a fiber diameter of about 3000 nm are also included. The document describes that the fiber diameter of the cellulose nanofiber can be freely adjusted. However, as previously mentioned, cellulose fibers are prone to cross-linking after modification with citric acid, making it difficult to reduce the fiber diameter. Of course, it is not entirely impossible to reduce the fiber diameter, but