1, the composition of the paper Paper is a material added by the plant fiber filler, rubber, pigment and other ingredients into a processing material.
The raw materials that make up paper are straw, bamboo, cotton, and available waste. Depending on the raw materials, the nature of the formed paper will also be different.
Fillers are materials used to increase the flexibility of paper, reduce paper transparency and stretchability, and make the surface of the paper even and even, such as talc for general printing paper, kaolin for high grade paper, and barium sulfate. The use of filler should be appropriate, usually about 20% of the paper, too much will reduce the resistance and flexibility of the thread, and will hinder the absorption of ink, resulting in the powder off when printing.
The rubber compound is used to fill the small pores in the paper to improve the water resistance of the paper, and it can also improve the gloss and strength of the paper and prevent the paper from fluffing. Commonly used rubber compounds are rosin, alum and starch.
The colorants are used to enhance the color purity of paper, and most of them use inorganic pigments or organic dyes.
2, the paper specifications Paper according to the different uses of the printing can be divided into flat sheet and roll paper, flat sheet paper for general printing presses, roll paper is generally used for high-speed rotary press.
The size of the paper is generally produced according to the standards set by the country. The paper size for printing, writing and drawing papers is: web width is divided into 1575mm, 1092mm, 880mm and 787mm; flat paper size is divided into size: 880mm x 1230mm, 850mm x 1168mm, 880mm x 1092mm, 787mm Six kinds of x 1092mm, 787mm x 960mm, 690mm x 960mm.
The standard for books and magazines and paper format size, the national regulations are to use 880mm x 1230mm, 900mm x 1280mm, 1000mm x 1400mm uncut single paper size printing. Due to equipment, production, supply and other reasons, the original 787mm x 1092mm, 850mm x 1168mm size paper can still continue to be used, but it should be noted that this size is to be phased out of the old standard format, after the paper size will be New national standards transition.
In the coastal areas, because of the large number of foreign-funded printing companies, many printing organizations still widely use some old-fashioned paper. The paper's weight is expressed in terms of weight and weight. It is generally expressed in terms of quantification, which is what we commonly call "weight." Quantitative refers to the mass relationship of the unit area of ​​paper, expressed in g/m2. For example, 150g of paper means that the weight per sheet of this type of paper is 150g. Paper with a weight of 200 g/m2 or less (including 200 g/m2) is called "paper", and a paper with a weight exceeding 200 g/m2 is called "cardboard." The order weight refers to the total mass of paper per order (1 sheet for 500 sheets) and the unit is calculated in kg (kg). According to the paper's basis weight and size, the weight can be calculated using the formula of weight (kg) = paper size (m2) x 500 x basis weight (g/m2).
2. Paper Paper is one of the important contents that prepress workers need to pay attention to, which determines the maximum range of printed products.