Corrugated box printing press printing process is divided into offset printing, flexo printing and gravure printing (silk screen printing is being eliminated). There are two types of prepress and post printing according to the printing sequence process. Offset color box is a single sheet of paper printed with single-sided corrugated board, die-cutting, paste box molding, with watermark general box after the first board printing process is different. After the rise of micro-cartons in Europe, offset printing can also be used after printing, but A, C, B, and E high-end color printing is still limited to the offset printing process. Therefore, the amount of veneer laminating machines and glue used in the production of papers has not only declined, but has increased at a rate of 10% per year. In 2003, more than 1,000 veneers were sold in the Pearl River Delta, Yangtze River Delta, and the developed areas of Beijing, Tianjin and Tangshan. There is an increase in the production of adhesives for the production of adhesives. Based on my own experience, the author has listed some of the offset tile techniques for offset printing cartons for your reference.

Composite applications

The paper-bonding compound is the first post-printing process of the offset veneer color box. Stickiness and pressing directly affect the cartridge efficiency and the forming effect. Multi-layer carton (three-layer, five-layer), paper box and folding box, U/V card tile/tile tile, double-layer 500 card card card can be completed through the compound, the product is used for packaging Beer, liquor, beverages, food, fruits, appliances, electronics and cosmetics. Some small carton manufacturers outsourced the purchase of color noodles, posted on their own, made moon cake boxes in summer, and made fruit boxes in winter, regardless of the season. Many breweries also use offset veneer boxes, such as the Venus beer cartons branch that purchased 3 squeegee machines at a time. Due to the limitations of the process, the compounding efficiency is generally not high, and the wide-hour speed of 1200mm-1600mm is between 2500 and 7000 sheets. Therefore, the paper-bonding composite process is more suitable for carton and carton packaging with smaller batches and more complicated product structure. The normal color registration of high-volume RSC cartons should adopt flexographic post-printing, and dot printing can adopt flexographic or gravure pre-printing.

Product size limitations come from the device. From the crepe process itself, of course, a small-sized carton is easier to handle and quality is more easily guaranteed. For multi-layer backing composites, pay attention to the direction of the paper grain. The paper patterns on the two sheets of the carton are perpendicular to each other. The paper grain direction of the carton should be perpendicular to the direction of the corrugation, so that a higher compressive strength can be obtained and the permeability can also be reduced. phenomenon.

The operation of the automatic winding machine has a high requirement for the paperboard, and the paper and the single tile must be dry and flat. At the same time, the proficiency of the operating personnel is also high. The semi-automatic machine has a simple structure and is equipped with a cardboard anti-winding device, and the manual work is relatively flexible. Not fast. The production efficiency and machine cost of the fully automatic machine are almost 2.5 times that of the semi-automatic manual machine.

In order to avoid the corrugation height being less crushed and damaged during the compounding process, on the one hand, the board must not be too soft and the moisture content is controlled below 14%; on the other hand, the pressure, angle and speed of the press machine area are moderated. The effective lamination length of the domestic veneer machine is set at 3.2 meters. The carton factory may require the machine manufacturer to extend it to 3.8 meters. With a longer lamination length, the operator can remove and reduce the 22 nip rollers under the belt according to the product requirements. The automatic paper winding machine is equipped with a hydraulic sensing system at the press-fitting position and automatically raises the roller height to adjust the pressure of different paper sections. This user-friendly design can not only reduce the burden on the operator, but also protect the strength of the carton.

Bonding performance

Compression resistance, flat pressure, burst strength and adhesion are important physical indicators of corrugated boxes. Strength is related to the processing technology of paper and paperboard, and bonding and compound glue are inseparable. The veneer bonding directly affects the next process of the carton and the customer's on-line packaging. Gluing becomes an important part of the lap paper composite process. If the adhesive is not uniform, the adhesiveness is not good, the cardboard surface will blisters, and the cardboard back surface will be glued. The corrugated can see the powder.

The machine's machining accuracy determines the uniformity of the coating. The accuracy of the outer circle and the inner circle of the rubber roller requires the rollers to pass through the outer car and the inner car. The roundness of the rollers is exactly the same, and there will be no wheel eccentricity and rejection of the rubber after 2 years of operation. The accuracy of the veneer machine remains unchanged for at least 5 years. The automatic machine adopts built-in plastic tank, closed pump glue, glue supply hydraulic pressure, uniform, safety and hygiene.

The glue used for crepe paper is starch glue and chemical glue. There are two kinds of starch glue, yellow plastic and white plastic, the domestic carton composite has basically eliminated yellow plastic. The currently used white rubber powder has the advantages of easy availability of raw materials, environmental protection, low cost, and ease of use. However, the adhesive force is not strong, it is easy to mold, the drying speed is slow, the film becomes brittle after drying, and more suspended matters are used during use. Precipitation, stability is not good. If you use a large amount of glue to update the frequency, you only need to use a simple stirring device. Before the glue is used, it is required to check the viscosity. In the compounding process, not only the adhesive effect is observed. The quick drying of glue is very important. Due to the high moisture content, the carton has good resistance to pressure after die cutting. The glue must be able to bond and dry completely within 4 hours. Otherwise, the cartons produced tend to collapse and the strength is damaged. The ratio of quick-drying rubber powder to water is generally 1:5, which is adjusted according to different products. After 3 minutes of initial tacking, the moisture content quickly drops to 20%, then drying slows down, and the cardboard moisture should be tested before die-cutting.

Chemical glue includes inorganic adhesive sodium silicate solution (water glass), commonly used for bonding between outer handsheet paper and inner core board, PH is 11-13, is alkaline, easy to contaminate the bonded materials, and absorbs moisture. Poor weatherability; PVA PVOH poor water resistance, adhesive strength is not high; Polyvinyl acetate (PVAc) room temperature curing speed, easy to use, high bonding strength, long storage period, colorless and transparent film after curing It does not contaminate the surface to be bonded, the adhesive layer has toughness, it has little damage to the tool, and it has a certain water resistance to cold water. Lamination 3065LV of National Starch Chemical Co., Ltd. belongs to this category.

The combination of crepe papers is strongly influenced by the work environment. The dampness of the air will cause the cardboard to be soft and soft. Therefore, it is advisable to place the machine in a constant temperature and humidity room.

If the machine is adjusted and the glue is used normally but it still produces degumming, the cause may be raw paper. All wood pulp ox card face paper will be poorly absorbed due to paper density and tightness. The rubber particles are difficult to penetrate quickly into the inner layer of the paper fiber, so that the adhesiveness is not secure. The solution is to try low viscosity glue. Robust corrugation ensures that delamination defects do not occur when the carton is automatically boxed by pulling up the cardboard (stand).

Automatic boxing

Food, beverage, beer, daily chemical, pharmaceutical and other industries are increasingly using automated carton packer packaging to solve the new problems of mass production and rising labor costs. The carton boxing machine is composed of five steps: the box, the vertical box, the folding cover, the bottom spray glue, and the transmission. The steps must be consistent and the beats must be consistent during the work. The automatic packing changed the appearance of the traditional manual box bloated, loose, making it more compact and more beautiful, the structural advantages of the corrugated box to get the best performance; Secondly, the automatic box into a hot melt adhesive to replace the plastic sealing tape, can be effective Prevent white pollution, in line with the concept of environmental protection, is conducive to the promotion of commercial exports.

Automatic packaging was once slow because of expensive equipment promotion. In recent years, China's light industrial machinery manufacturers have developed economical packing machines, equipped with Nordson, and made 40 boxes per minute to complete the carton packaging terminal system. The comprehensive automation not only improves the labor efficiency of the packaging process, but also expands the application function of carton packaging.

The automatic box-packing machine requires high strength, stiffness, and low moisture content. The soft and soft carton box can not guarantee the normal box folding, but also affects the shape of the carton after molding. This happens to be the "soft rib" of the paper-bonding process. .

Eliminating the defects of the carton on the automatic offset carton carton, the first one is to detect the moisture of the base paper (less than 12%); the second is to control the moisture (less than 10%) of the cardboard after the cold glue and tile, and the cardboard from the veneer At least 24 hours after the natural drying time, and then slotted or die-cutting. Offset printing uses partial gloss, but the hot-melt glue coating department does not use clear oil, which helps seal the box fast and securely.

Source: Corrugated Box