What are the different processes to creating manila paper?

There are two main processes used to create manila paper: the chemical process and the mechanical process.

Chemical Process

1. Raw Material Preparation: Agricultural residues like sugarcane bagasse, wheat straw, and jute sticks are collected and cut into small pieces. These materials serve as the primary sources for making manila paper.

2. Pulping: The raw materials undergo a chemical pulping process to separate lignin from cellulose fibers. This is typically done using chemicals such as sodium hydroxide (NaOH) or kraft chemicals (a mixture of sodium hydroxide and sodium sulfide).

3. Washing and Screening: The resulting pulp is washed and screened to remove unwanted residues and impurities.

4. Bleaching (Optional): Depending on the desired quality and color of the final product, the pulp may undergo a bleaching process using chemicals like hydrogen peroxide or chlorine-based compounds.

5. Papermaking: The bleached or unbleached pulp is fed into a papermaking machine, where it is formed into sheets and dried. The paper passes through a series of rollers to press out excess water and achieve the desired thickness.

Mechanical Process

1. Raw Material Preparation: Similar to the chemical process, agricultural residues like sugarcane bagasse and wheat straw are gathered and cut into smaller pieces.

2. Grinding/Defibering: The raw materials undergo a mechanical defibering process using machinery like refiners or grinders. This breaks down the plant fibers into individual cellulose fibers.

3. Washing and Screening: The resulting fibers are washed and screened to eliminate contaminants.

4. Papermaking: The pulp is then fed into a papermaking machine, where it is formed into sheets and dried.

The mechanical process is generally faster and less expensive compared to the chemical process, but it produces paper with lower strength and durability due to the shortened fibers.

After completing either the chemical or mechanical process, the manila paper can be further processed to enhance its properties or add specific characteristics, such as coating, calendaring (smoothing the surface), or adding additives for desired qualities like water resistance or improved opacity.