Methylcellulose (MC) is a water-soluble polymer compound widely used in food, medicine, daily chemicals, construction and other industries. Its production process involves multiple steps, mainly including cellulose extraction, modification reaction, drying and crushing.

1. Extraction of cellulose
The basic raw material of methylcellulose is natural cellulose, which is usually derived from wood pulp or cotton. First, the wood or cotton is subjected to a series of pretreatments to remove impurities (such as lignin, resin, protein, etc.) to obtain pure cellulose. Common pretreatment methods include acid-base method and enzymatic method. In the acid-base method, wood or cotton pulp is treated with sodium hydroxide (NaOH) or other alkaline solutions to dissolve lignin and other impurities, thereby extracting cellulose.

2. Etherification reaction of cellulose
Next, a methylation reaction (etherification reaction) is carried out to prepare methylcellulose. The core step of the etherification reaction is to react cellulose with a methylating agent (usually methyl chloride, methyl iodide, etc.) to obtain methylcellulose. The specific operation is as follows:

Choice of reaction solvent: Polar solvents (such as water, ethanol or a mixed solvent of water and alcohol) are usually used as reaction media, and catalysts (such as sodium hydroxide) are sometimes added to improve reaction efficiency.
Reaction conditions: The reaction is carried out at a certain temperature and pressure, and the usual reaction temperature is 50-70°C. During the reaction, methyl chloride reacts with the hydroxyl (-OH) group in the cellulose molecule to convert it into methyl cellulose.
Reaction control: The methylation reaction requires precise control of reaction time and temperature. Too long reaction time or too high temperature may cause cellulose decomposition, while too low temperature or incomplete reaction may lead to insufficient methylation, affecting the performance of methyl cellulose.

3. Neutralization and cleaning
After the reaction is completed, unreacted methylation reagents and catalysts may remain in the methyl cellulose product, which needs to be neutralized and cleaned. The neutralization process usually uses an acidic solution (such as acetic acid solution) to neutralize the alkaline substances in the reaction product. The cleaning process uses a large amount of water or alcohol to remove solvents, unreacted chemicals and by-products after the reaction to ensure the purity of the final product.

4. Drying and crushing
After washing, the methylcellulose is usually in a paste or gel state, so it needs to be dried to obtain a powdered product. There are many ways to dry, and the commonly used ones include spray drying, freeze drying and vacuum drying. During the drying process, the temperature and humidity need to be strictly controlled to avoid decomposition caused by high temperature or damage to the gel properties.

After drying, the obtained methylcellulose needs to be crushed to achieve the required particle size. The crushing process is usually completed by air jet milling or mechanical milling. By controlling the particle size, the dissolution rate and viscosity characteristics of methylcellulose can be adjusted.

5. Inspection and packaging of the final product
After crushing, the methylcellulose needs to undergo strict quality control to ensure that it meets the technical specifications. Common inspection items include:

Moisture content: Too high moisture content of methylcellulose will affect its stability and storage.
Particle size distribution: The size and distribution of particles will affect the solubility of methylcellulose.
Degree of methylation: The degree of methylation is a key indicator for evaluating the quality of methylcellulose, affecting its solubility and application performance.
Solubility and viscosity: The solubility and viscosity of methylcellulose are important parameters in its application, especially in the field of food and medicine.
After passing the inspection, the product will be packaged according to different needs, usually in plastic bags or paper bags, and marked with production batch number, specifications, production date and other information.

6. Environmental protection and safety
During the production process of methyl cellulose, appropriate environmental protection measures need to be taken, especially for chemicals and solvents used in the reaction process. After the reaction, waste liquid and waste gas must be treated to avoid polluting the environment. In addition, chemical reagents in the production process should be strictly carried out in accordance with safety operating procedures to ensure the safety of workers.

The production process of methyl cellulose mainly includes cellulose extraction, methylation reaction, washing and neutralization, drying and crushing. Each link has an important impact on the quality of the final product, so control and monitoring in the production process are very critical. Through these process steps, methyl cellulose that meets different application requirements can be produced.