Composition of Paper

A paper-based product typically contains 90–99 percent cellulose fibres, which are the most essential component impacting end-use qualities and the principal structural element. The chemical and physical qualities of paper products are influenced by a network of self-bonding cellulose fibres within the network structure. The inorganic fraction of the paper, which consists primarily of filling and loading materials such as calcium carbonate, clay, titanium oxide, and so on, may range from 0 to 30%.

Chemical Composition of Paper

The chemical composition of paper varies according to its type or grade. The majority of paper grades are made up of both organic and inorganic materials. The organic fraction, which consists of cellulose, hemicellulose, lignin, and/or different lignin compounds (Na-lignite, for example), can range from 70 to 100 per cent sometimes including filling and loading materials. 

Chemical Formula of Paper

As we know paper is primarily made out of cellulose, which comes from wood pulp. Cellulose is a polysaccharide made up of a chain of glucose molecules bonded together. It is the primary component of plant cell walls, and its chemical formula is (C6H1O5)n, where n specifies the number of cellulose units. Thus, the molecular formula of cellulose, (C6H1O5)n can be used to symbolise paper but exactly no chemical formula exists for it as it is far too complex to be represented by a single chemical formula.C6H1

Ingredients of paper

• Cellulose fibre: Short Cellulose fibre are the primary raw material used to make paper. Cellulose fibre is the most basic component of plant matter, and it may be removed in vast quantities from wood. Softwood trees, hardwood trees, recycled fibre, and rag are the four main sources of cellulose fibre used in the production of paper (usually composed of textile cuttings and cotton).

• Sizing: Starch and rosin are used as sizing materials. These substances can be used both internally and externally. Internal sizing is used to offer paper water resistance, which is important in lithography sheets. Internal sizing is often accomplished with rosin or papermakers’ alum. Surface sizing regulates the absorption of printing ink on the paper surface, resulting in clearer images.

• Filler: Fillers are used to increase the smoothness, opacity, and colour of paper before it is printed. They help reduce strike-through, which occurs when ink penetrates the paper and appears on the opposite side. The most frequently used fillers are the clay, titanium dioxide, and calcium carbonate.

• Pigments: Pigments and dyes are needed to make coloured paper. In sheetfed offset lithography, coloured papers are fairly frequent. The print designer must be aware of the negative impact coloured sheets have on coloured inks and graphics.

Process of Papermaking

1. Making pulp: Logs are tumbled in drums to remove the bark before being transferred to grinders, which crush them between spinning slabs to break them down into a pulp. Before being transferred to the paper mill, the pulp is purified through filters.

2. Beating: The pulp is subjected to the effect of machine beaters inside a big tub. Various filler materials might be applied at this phase. The pulp is then pounded and squeezed in a process called, fittingly enough, beating. At this time, sizings are also introduced.

3. Conversion from pulp to paper: Pulp is compressed via a succession of rollers, while water is drained by suction mechanisms beneath the belt which results in a sheet of paper. A device is known as a dandy move across the sheet of pulp and presses a design into it if the paper is to be water-marked. To remove the residual water from the pulp, a big machine may include 40 to 70 drying cylinders.

4. Finishing: The paper is then compressed even more by passing it through calendars, which are metal rollers. It is then coiled into enormous reels and processed further, depending on its intended application. The paper can be polished even more by running it through a sizing vat.

Different types of paper

• Tissue paper- Tissue paper, like other paper products, is made primarily of cellulose fibres. The fibre might be 100% virgin, 100% recycled, or a mix of both. Due to environmental concerns, 100% recycled fibres are used.

• Book paper- As the name suggests, used in printing and publishing books.

• Copy paper- Used for printers, photocopiers, fax machines, and other general-purpose office and home purposes

• Matt Coated Paper- Matt paper is the polar opposite of glossy paper, as it is coated with a matt texture to reduce glare on non-shiny paper.

Conclusion

Thus, the composition of the paper is heterogeneous in nature consisting of a mixture of cellulose, hemicellulose, lignin, and/or different lignin compounds which makes it not possible for the paper to have a particular formula. In short, there are two steps to papermaking, firstly cellulose fibres are collected and processed to pulp from a variety of sources, and then the pulp is mixed with water and fed into a paper machine for conversion from pulp to paper.