What is the most important factor in the printing process?

Paper as an important pillar in the printing process

Today, there are over 3,000 types of paper products in the world, each of which, depending on different variables, has different roles and effects on their final use. Paper is considered as a pivotal element in the printing process and, given its characteristics, has a major role in determining the quality of printing and the qualitative properties of the printed product over its useful life.

What is the most important factor in the printing process?

Therefore, adequate and practical knowledge of it is necessary to understand the mutual relations of paper, composite and printing equipment in different stages of printing. As it has been said, unfortunately, in the printing industry of the country, the technical know-how existing in paper and its properties is more experimental, and this has not been considered sufficiently even in the academic disciplines associated with the printing industry. In this article, we try to address these issues in a concise and useful way

Raw materials for the preparation of paper

 Raw materials The types of paper, in general, are cellulose materials made from various sources:

Flax, hemp, cotton, long fibers (about 1.2 to 6 mm).

Plants such as wheat, barley, straw, hemp and so on.

The trees that have needle leaves, such as pine (long fibers) or broad leaves, such as sycamore (with short fibers of about 0.5 to 1.2 mm).

Types of waste paper or scraps and stacked paper parts.

Cane sugar

What is the most important factor in the printing process?
Steps to make paper

Turning the wood into pieces is done using a grinding machine and a chip making machine and passing chips from a special sieve, and pieces of length of at least 4 and a width of 2 cm (in the case of wood) are obtained.

Bake wood and produce dough

 

This practice may be exerted through mechanical means, without the use of chemicals and by boiling steam, which is commonly used to make cheap and straw paper, such as a newspaper paper. In chemical method, sodium hydroxide (in alkaline method), calcium hydrogen sulfite, in acidic medium (pH = 2-3, bisulphite method) or sodium sulfite (in sulfite method) with a little sodium carbonate at a temperature higher than. 100 ° C and under pressure. At this stage, a brown colored puff is used to make cardboard, cardboard or straw paper.

What is the most important factor in the printing process?

Pulp Washing

Alkaline washing is performed using a 3% solution at 45 to 50 ° C for one to two hours. This is done to remove lichen and reduce the color of the dough.

Chemical application (decolourisation)

It takes place in two stages:

1-chlorine, which is at pH = 2 to 25 to 45 ° C for about an hour. At this stage, the remaining legetin in the dough is soluble, which varies between 3% and 15% depending on the type of chemicals used for cooking.

2. Decontamination by sodium hypochlorite (3% solution), chlorine dioxide, hydrogen peroxide, ozone and so on at pH = 9-10, so that only the oxidation of legetin and cellulose is not affected.
Pulp drying

At this stage, the pulp passes through a cleaning device and lacing 2 to 3 mm in holes to lose most of its water. Then they pass through strong presses to remove the remaining water.

What is the most important factor in the printing process?

Pressing, cutting and packing

By passing the dried paste from special rollers, it is cut into paper plates, cut and packaged by cutting machine in order sizes and market demand.

In general, paper is a complex product or several mechanical-mechanical structures, and in this sense it is sometimes referred to as composites. The various properties of paper types are influenced by the ingredients that make up the paper.

What is the most important factor in the printing process?

So according to the above, the paper should be considered from 3 comments:

1- Anatomy and Morphology:

Paper is made from lignocellulosic fibers derived from trees and lignocellulosic plants. Lignocellulosic plants include a wide and wide range of plant species that can be divided into trees (leafy and broadleaf) and non-woody plants (including a large variety of herbaceous and non-herbaceous plants). Lignocellulosic fibers are in fact the major part of vegetative cells that form plants and trees, and according to the wide range of plants and trees, there are similarities and differences in morphology in terms of fiber length and other anatomical traits. Obviously, these traits and parameters have important effects on the physical-mechanical and even the chemical properties of the resulting paper.

2- Chemical:

Lignocellulosic fibers are complex compounds of organic organic polymers, which are interconnected by complex biochemical processes and form the cell wall of the fiber. The most important of these natural polymers are cellulose, hemicellulose, lignin and extractive compounds. Each of these polymers has its own chemical properties that play a decisive role in determining the chemical properties of fibers and paper. Depending on the paper and the process of making it, some of these polymers may or may not exist in the final paper.

What is the most important factor in the printing process?

This is a matter of great importance to the mutual interaction of paper with other organic polymers used in the printing industry, especially printing ink and dyes. Because it is obvious that any chemical used in the printing process should be compatible with these organic polymeric polymers in order to play its intended role. On the other hand, it should be noted that there are many additives available to create, maintain or improve and enhance the propertiesOr various features are added during the paper making process at the paper mill.

What is the most important factor in the printing process?

Most of these materials include sizing materials, fillers and special additives. Obviously, these materials will also play a decisive role in the process of using and applying a variety of paper. Therefore, in general, in the printing process, all these materials and other consumable chemicals, such as printing ink, etc., should be compatible and reactive, in order to obtain the appropriate print quality.

In addition to the above, the process of making pulp is also an important factor in determining the traits of paper. Methods for making pulp including chemical, mechanical and chemical – mechanical and semi-chemical methods, each of which itself includes various types of subgroup methods. Paper pulp and paper, usually derived from each of these processes, have their own attributes and applications that should be considered when using them in the printing process.

On the other hand, temthe paper making sys (acidic and alkaline) is another important factor that has a major impact on the properties of the paper, and in particular its durability and durability.

What is the most important factor in the printing process?

3. Mechanical:

The paper making machine is a composite and mechanical device with a three-dimensional structure with an orthotropic elasticity symmetry. The presence of such a structure has a direct impact on the physical and mechanical properties of paper during use, especially in the printing process.

What is called paper problems in the printing process, such as threading, folding, etc., is mainly due to its mechanical properties. It should be noted that when making paper in a paper making machine, most of the cellulosic fibers are parallel to the machine’s lining.

This direction is called the direction or direction of the machine (MD) and its perpendicular direction is perpendicular to the construction or perpendicular to the machine (CD). The mechanical properties of the paper in these two directions, as well as in the direction of paper thickness (direction Z), are different. Different pressures on the paper (in rolls or sheets) from different printers of the machine or when moving paper in the space between the cables, need Considering that the paper has the proper mechanical properties to prevent any problems.