Offset paper refers to printing paper, also known as offset paper. It is a kind of high-grade printing paper, which is generally used for offset printing machine for book printing or color printing. Offset paper is divided into single-sided offset paper and double-sided offset paper, as well as super calendering and ordinary calendering
(1) The raw materials of offset paper and the properties of offset paper. Offset paper is generally made of bleached softwood chemical pulp and appropriate bamboo pulp. When processing offset paper, filling and sizing are heavy. Some high-grade offset paper also needs surface sizing and calendering. Offset paper needs good water resistance, dimensional stability and strength due to the principle of ink and water balance when printing. Offset paper is mostly used for color printing. In order to restore the original color of the ink, it is required to have a certain degree of whiteness and smoothness. Offset paper is generally used for printing picture albums, color illustrations, trademarks, covers, ring linings, high-grade books and this volume. In recent years, due to the improvement of people's culture and living standards, book materials have also developed to a higher level, and more and more books and periodicals and this volume are printed on offset paper. Due to the advantages of offset paper, such as white, neat, flat and delicate, the book is clear, flat and not easy to deform. Compared with the bald version and newsprint, the grade of offset paper is very different, which is welcomed by readers and users. The number of books and periodicals bound with offset paper will increase substantially in the future to meet the needs of the market.
(2) Specifications of offset paper. The specifications of offset paper are the same as those of the above two kinds of paper. For other specifications, please refer to the national standard GB147 Size of Base Paper for Printing, Writing and Drawing. The size error and deviation shall not exceed ± 3mm. There are various quantities of offset paper, and the commonly used quantities are 60, 70, 80, 90, 120, 150, 180, 200 and 250 g/m2. The offset paper used for printing books and periodicals is below 90g/m2, and the cover is about 70-200g/m2. Offset paper is crisp, smooth and easy to bind. ① Any method used during page collision can achieve good page collision tidiness effect. ② Any folding machine can achieve good folding effect, especially suitable for high-speed folding. ③ Offset paper books and periodicals shall be designed with three fold or less (four fold is not allowed). It is better to cover the book after two folds (more than 80g/m2), because the offset paper is thick and has a large amount of weight, and too many folds are easy to produce a zigzag fold or a dead fold that is not easy to expand, resulting in uneven cut and uneven book block quality problems after cutting. ④ When the number of pages or thickness of the iron wire is the same as that of the uncoated paper, the diameter of the large iron wire shall be used. ⑤ The viscosity of the binder is higher (thicker) than that used for uncoated paper, because offset paper has a large quantity, smooth surface, low viscosity (thinner), and is not firm or peels off after sticking. ⑥ The hardcover book block of offset paper is not easy to be rounded and ridged, especially when it is thick. Because the offset paper is slippery, it is easy to expose each book post after rounding, while the front edge of the book post is round and appears ladder shape; The creases in the creases can not be smoothed due to manual smashing during ridge forming, resulting in defective products. ⑦ Generally, books and periodicals made of offset paper are of high grade, so the cover material should be better than the book block material to match the inside and outside of the book. |