Offset Printing 1000 Questions (200-213)

200. What are the common classification methods for paper?
A: There are many types and sizes of paper. The classification methods are also different. Common classification methods are as follows.
1 according to the quantitative and thickness: paper is usually divided into two major categories of paper and paperboard, usually the amount of paper below the limit of 250g/m2 and the thickness of 0.1mm is called paper, the amount of more than 250g/m2 and the thickness of 0.1 Paper above mm is called cardboard.
2 according to the fiber material: usually divided into plant fiber paper and non-plant fiber paper two categories, the former is called ordinary paper, the latter is called special paper.
3 Press the papermaking method: two types of manual paper and machine paper.
4 by processing type: sub-coated paper and coating paper two categories.
5 according to the printing method: divided into newsprint, letterpress printing paper, offset printing paper, gravure printing paper and other categories.
6 According to use: divided into cultural paper, industrial and agricultural technology paper, packaging paper and household paper.

201. Offset printing paper generally divided into several categories?
A: Offset printing paper is generally divided into coated paper and non-coated paper.

202. What are the basic characteristics of coated paper?
A: Coated paper refers to non-coated paper as the base paper (paper base). The on-line or off-line coating device coats the surface (single or double-sided) with a layer of white paint and is super-calendered or pressed. Patterned paper. Offset printing coating paper, embossed paper, high gloss coated paper, etc., are all coated paper.

203. What are the basic characteristics of non-coated paper?
A: Non-coated paper refers to pulp fibers that have been treated with pulping. After different beating methods and the addition of certain excipients, the wet fiber layer of the web is directly made and pressed and dried to form sheet-like fiber products. . Offset printing paper, writing paper, and cover paper are all non-coated papers.

204. What are the common specifications for offset printing paper?
A: The paper size generally refers to the paper's packaging form, size, and basis weight.

205. There are several types of offset paper packaging?
Answer: According to the offset printing type, the offset printing paper generally has two kinds of packaging forms: flat plate and reel.

206. What are the sizes of offset printing paper?
A: The paper size refers to the size of the paper format. For flat paper, it mainly refers to its width and length; for web, it mainly refers to its width. The national standard has made the following provisions on the size of the base paper for printing, writing and drawing.
Sheet size: 880 mm×1230 mm, 880 mm×1092 mm, 787 mm×1092 mm, 787 mm×960 mm, 690 mm×960 mm, 850 mm×1168 mm.
Web size: 1576mm, 1092mm, 880mm, 787mm.

207. What is the ration of paper?
A: Quantitative refers to the theoretical standard weight specified in the paper quality standard, in g/m2. The ration of paper is determined based on the use of the paper and the craftsmanship. Due to technical reasons, the actual amount of paper (the actual weight of the paper) can fluctuate.

208. What is flatbed paper?
A: Flatbed paper refers to paper copied by a paper machine, and is cut to a certain size by a paper cutting machine and is packed into pieces by a prescribed weight. If the basis weight is less than 50g/m2, the weight of each package shall not exceed 125kg; if the basis weight is greater than or equal to 50g/m2, the weight of each package shall not exceed 175kg.

209. What is a web of paper?
Answer: Roll paper refers to the paper copied by a paper machine, which is cut into a certain width by a rewinding machine and is wound on a paper core of a certain diameter. Common offset webs such as roll offset newsprint, book and paper, etc., generally have a package diameter of 800-1400mm, each weighing about 300kg, and a length of about 6000m.

210. How to calculate the weight of sheet and ream according to the basis weight of paper?
Answer: Sheet weight (g) = sheet size (m2) × basis weight (g/m2)

211. What are the basic requirements for offset printing?
A: Paper is an important factor in determining the quality of printing in offset printing materials. In the offset printing process, the paper generally needs to undergo a series of processes such as paper feeding, pressure introduction, peeling, and paper collection. Therefore, the properties of the offset printing paper must be directed to the above process to satisfy the appearance, physical, mechanical, and chemical properties of the process. And technical requirements.

212. What are the basic requirements for the appearance of offset printing paper?
Answer: Regarding the appearance properties of offset printing paper, regardless of the type of press used, the offset printing paper must satisfy the fibrous structure (or coating) that is uniform, flat, and clean, with no wrinkles, creases, fiber bundles, and defects on the paper surface. Mechanical damage such as scratches, holes, holes, nicks, and other issues affecting the quality of print jobs and prints.

213. What are the basic requirements for the physical and mechanical properties of offset printing paper?
A: Due to the difference in the structure and printing speed of the printing press and the nature of the printed matter, it has different requirements for the main physical and mechanical properties such as surface properties, ink-absorbing properties, optical properties, and mechanical strength of the offset printing paper, but the paper All kinds of properties must be compatible with the paper feeding method, printing speed, and printing pressure of the printing press to ensure that the paper can be printed smoothly and obtain the desired printing quality and effect.

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