Q&A on Printing Paper (175-185)

175. What are the commonly used printing paper?
Answer: Commonly used printing paper is mainly divided into cultural printing paper, commercial printing paper, packaging printing and special printing paper. The cultural papers mentioned here include newsprint papers and books and papers, namely letterpress paper, offset printing paper, offset book paper, single-sided offset printing paper, dictionary paper, thin letterpress paper, primary and secondary school textbook paper, etc.; commercial printing paper. Including coated paper, cast coated paper, placard, weekly newspaper, white cardboard, gravure printing paper, rice paper, cover paper, calligraphy paper, etc.; packaging paper including single white paperboard, single coated white paperboard, cast White paperboard, cover board, envelope cardboard, grassboard, etc.; special printing paper includes Braille printing paper, stamp paper, map paper, banknote paper, security paper and so on.

176. What is the size specification of printing paper?
A: The national standard (GB-147-89) of the People's Republic of China regulates the size of printing paper.
Web: Width specifications are 1575mm, 1562mm, 1280mm, 1230mm, 900mm, 880mm and 787mm.
Flat paper: The web size is 1000mm x 1400mm, 900mm x 1280mm, 880 x 1230mm, 787mm x 1092mm.
The allowable deviation of web width is ±3mm; the allowable deviation of flat web size is ±3mm.

177. Newsprint is divided into several categories?
A: The national standard divides newsprint into four grades based on product quality, namely A, B, C, and D. Among them, grades A and B are applicable to high-speed rotary offset presses. A and other products to reach the international advanced level of paper products, B and other products should represent the domestic advanced level.

178. What are the performance characteristics of newsprint?
A: The primary performance of newsprint should be good ink absorption and water resistance in order to meet the requirements of high-speed web offset presses; secondly, the tensile strength should be high to ensure that no paper breaks occur during the printing process. Paper should be smooth, at least through ordinary calendering, so that the printed text and pictures do not leak lines, no lost points, and clear and beautiful graphics; Newsprint does not allow through the print, so it must have high opacity.

179. What are the performance characteristics of letterpress paper?
A: Letterpress paper generally has a certain strength, paper soft, smooth paper, uniform thickness, good ink absorption, lint-free, impermeable, etc.; requirements for letterpress white paper, A-level letterpress paper is not Below 65%, Grade B is not less than 60%, and Grade C is not less than 55%. The whiteness of letterpress paper for book printing should be different according to the characteristics of the book.

180. What are the performance characteristics of offset printing paper, and what are the special requirements for papermaking?
A: Offset paper is generally used for printing books such as high-grade books, pictorials, pictures, trademarks, and posters. Since offset paper is mainly used for offset printing, the paper deformation during printing will affect the accuracy of registration, in order to enhance the paper's water resistance, improve the paper's dimensional stability, surface strength, reduce the powder falling, hair loss failure during the printing process, copying When using long-fiber free-form beating and surface sizing when dry, since the offset ink is mostly oxidative conjunctiva drying, in order to increase the drying speed of the ink on the paper, the pH of the offset paper should tend to be neutral or slightly alkaline. Sex.

181. What are the performance characteristics of offset printing?
A: Offset book paper is a substitute for letterpress paper and is mainly used to print books, documents and magazines. In addition to the performance of letterpress paper, offset book paper also has some special requirements: higher tensile strength, avoiding the problem of paper breakage during high-speed offset printing; at the same time, it must have high surface strength and resistance. Waterborne.

182. What are the performance characteristics of single-sided offset paper?
A: Single-sided offset paper, commonly known as single-tape, is only suitable for printing single-sided prints. The effect of double-sided printing is not good. The standard stipulates that the frontal smoothness is not less than 80s for Grade A products, 40s for Grade B products, and 35s for Grade C products. After soaking, the longitudinal stretching rate is no more than 0.5% and the transverse stretching rate is no more than 2.5%. The fibrous structure of the paper should be uniform, and there must be no obvious lint and powder off during printing.

183. How is the dictionary paper classified?
A: The national standard divides the dictionary paper into three levels according to the level of product quality, namely, A, B, and C. A is a product with international advanced level, B is a product with advanced domestic level, and C is a qualified product.

184. What are the performance characteristics of dictionaries?
Answer: Dictionaries are thinner and have higher tensile strength. They are less likely to break on rotary presses; they are white, highly opaque and clearly printed. The standard stipulates that the dictionaries should have a whiteness requirement of 77% to 79%, an opacity of not less than 70% to 81%, and an average breaking length of 2300 to 2500m. At the same time, dictionaries must not lose powder or lose hair during printing. And can not have dust, spots and other defects.

185. How to classify thin relief paper?
A: The industry standard divides A, B, and C grades according to the quality of the thin letterpress paper. The A-level thin letterpress paper has a low basis weight and is used for printing common dictionaries and pocketbooks. The B and C-class thin letterpress papers are generally quantitative. At 40-48g/m2, it is mostly used for the printing of general reference books or technology books.

Source: Ke Yin Media - "Printing Technology"