In the paper packaging industry, moisture absorption and softening of cartons, deformation phenomenon, use effect and strength performance decline is easy to appear quality problems, but also the usual customer quality complaints of the main problems. Therefore, it is very important to control the purchasing quality and production process control of the base paper to improve the quality of the carton products.
Relationship between quality index of base paper and moisture resistance of carton
The quality of box board and corrugated paper has a direct impact on the moisture resistance of cartons. Among them, the tightness, sizing degree, positive and negative water absorption index of the base paper have a great impact on the moisture resistance of the base paper. However, the tightness and sizing degree of the base paper are good, and its water absorbency index is low, and its moisture proof performance is good. In the production process practice, we found that the tightness and sizing of box paper and corrugated paper are poor, and the strength of corrugated board produced by production is also poor. This is because of the poor tightness of the base paper, its fiber structure appears loose, easy to absorb moisture in the external environment (including steam emitted from a single-sided machine). On the other hand, the sizing degree of the base paper is poor, and the paper surface is easy to absorb moisture from the outside environment. Therefore, according to the actual production process, it is very important to control the quality of the base paper. Corrugated paper in the current national standards has no sizing degree and positive and negative water absorption test items, box paper only positive and negative water absorption test items, base paper quality control coverage has certain limitations. In view of this, according to the actual quality of production, we have formulated the enterprise standards of corrugated paper and boxboard paper. The sizing degree and water absorption index of the raw paper are quickly tested by simple and simple method. The method is: randomly extract a piece of reel paper, drop water on the paper surface, observe the speed of water droplets on the paper surface. The standard unit is greater than or equal to 60S. All the raw papers which can not meet the inspection standards are returned to the warehouse. By adopting such control measures, the quality of the raw papers has been improved and the moisture-proof performance of the cartons has been improved obviously. In addition, due to the different quality grades of carton paper and corrugated paper, technical indicators are also different, therefore, the best choice of high-grade beer packaging is to choose high-quality base paper to make cartons, which is also an important technological measure to improve the moistureproof performance of pre-printed beer cartons.
Influence of technical indexes of white board on moisture resistance of cartons
Usually, the surface of the pre-printed carton is white board paper, which is mounted on the outer layer of the corrugated carton, so it is easy to touch the moisture of the outside air. Therefore, some technical indicators of the white board paper also directly affect the moisture-proof performance of the whole carton. According to the production practice, the author thinks that the roughness, smoothness, gloss and water absorption of the printed surface of white board paper have great influence on the moisture-proof performance of cartons. Therefore, it must be emphasized that these technical indexes should be controlled within the scope of national standards, or even higher than the national standards in order to improve the cartons. Moistureproof performance. Especially in the post-press processing of white board with polishing technology, the poor quality of paper coating is easy to absorb oil, so that the paper lacks the proper oil layer and brightness, it is easy to absorb external moisture. According to the national standard GB / T10335.4 - 2004 "coated whiteboard" and technical specifications, Coated Whiteboard paper can be divided into three categories: top grade, first grade and qualified products, and there are white and grey background, and the technical specifications are different. In production practice, we found that the brightness of white board with high quality is higher after polishing, on the contrary, it is obviously lack of brightness, and its moisture resistance is poor. Therefore, according to the different quality grades of food and the difference of environmental temperature and humidity in the place of sale, selecting the appropriate grade of white board for printing can not only give consideration to the economy of moderate packaging, but also better achieve moisture-proof packaging, meet the quality requirements of the market. According to the author's quality management experience, the selection of pre-printed whiteboard quality grade principle is: general product grade; sales, use cycle is shorter; product sales, the use of environmental humidity is relatively dry; carton printing plate ink coating area is larger, pre-printed whiteboard paper can be selected as appropriate first-class or qualified products into Print can be done. On the contrary, the product grade is higher; the sales and use cycle is longer; the environmental humidity of the product sales and use is relatively high; the printing surface ink coating area is not large, can use high-quality white board paper for printing, which is also an important technological measure to improve the moisture-proof performance of the pre-printed carton.
Improving moisture resistance of pre printed cardboard boxes through production process control
Above mentioned the moisture absorption caused by the external factors of the carton, first of all from the carton's outermost pre-printed paper, then, pre-printed whiteboard through the control of technical indicators of the base paper and printing layout design (printing ink coating area is large, its moisture absorption is low), to improve the moisture-proof performance of the carton, the effect is after all Limited. To achieve durable, wear-resistant and better moisture-proof effect, can be achieved through the use of coating, polishing, calendering process. Among them, the coating process is the best, but the production cost is higher, increase the cost of food packaging, and also cause greater difficulties and trouble to recycle materials, this process is only suitable for high-grade products and long-distance transport of products packaging. Polished and calendered paper is a relatively common processing technology, its moisture-proof and anti-friction effect is by polishing paint, commonly known as polishing oil, its production process is relatively simple and economical. By polishing and calendering, a bright and smooth protective layer can be formed on the surface of white board paper. Generally, the packaging of middle and low grade beer and other products adopts calendering or calendering technology. Therefore, according to the characteristics of the product, we should choose the appropriate post-press processing technology, so that the moisture-proof effect and appearance quality of the product packaging have been better taken into account.