Papermaking evolved long back, in 105 AD China. Since then the uses of paper have become numerous making the global paper and pulp industry, a billion dollar one globally. However, the modern method of papermaking bears a close similarity to the original process formulated by Ts’ai Lun in the court of the Chinese emperors. The steps of the process are pulping, which separates the fibers, beating and refining the fiber, mixing water with the refined fiber, forming a web of fiber by applying the diluted fiber on a screen, pressing the web in order to increase the density, drying so that no moisture remains and pressing the mass to get the end product.
This March, there will be a tissue industry expo at Miami, USA, where many prominent tissue industry players are expected to attend. There will also be pulp and paper equipment suppliers, and if you are concerned about the future of the paper industry, you should definitely attend. You can check out their site here: http://www.tissueworld.com/miami/en-us/pulp-fiber-processing-equipment
Most paper is made from wood, but apart from it, rags, flax, sugarcane residue are also used to make pulp and paper. These days recycled paper is also a popular choice for raw material. The fibers that are of primary interest in papermaking are Cellulose. It comprises almost 50% of wood. Lignin, the complex organic compound, holds the wood fibers together. The pulping process aims to remove the lignin without making the fibers weaker.
Wood from almost any plant or tree can be used to make paper; they all have their individualities affecting the end product. Softwood yielding trees like Pines, Firs and Spruces produce long and strong fibers which is great for stiff paper, used in products like containers etc. Hardwood yields shorter fibers which result in paper of less strength, less durability and less brightness.
Any form of pulping uses basic steps like cutting the wood and debarking it, mechanical or chemical separation of wood fiber from lignin and extractives, which are then dissolved, removal of colour particles by bleaching and the last step is paper formation and finishing. If the raw material is recycled paper then there are minor changes in the process.
Recycled paper is first sorted into different categories. The categories vary from country to country. Printed paper needs to be deinked before it can be processed into graded graphic paper. To deink the paper either it is placed in a huge tank called pulper, where paper fiber is separated from paper with huge amounts of water and broken down to form a slurry. This process is called washing. Most of the water containing dispersed ink particles is drained through screens or slots. In the process of floatation the mass is added to water and contaminants are removed. Chemicals are added to the resultant slurry to produce froth. Air is then blown into the mixture making ink rise to the surface with air bubbles and trapping the ink residue in a layer of foam.
Specialized process and sophisticated pulping equipment are the keys to a great pulping and perfect paper.