With the rapid development of solvent-free compound glue, technology and equipment, the application field of solvent-free compound glue is becoming wider and wider. Recently, a special solvent-free laminating machine for cigarette packet jam / transfer film lamination in Shanghai Zhou Tai was successfully accepted and sent to a domestic listed group company. The group company is a leading enterprise in the domestic cigarette packet industry. Previously, there were many Zhou Tai laminating machines. At the same time, Zhou Tai also transformed and upgraded many of its laminating equipment from different manufacturers. So how to complete such products as cigarette pack paperboard through solvent-free compounding? What are the specific requirements for solvent-free composite equipment? Today we will simply share.
If we want to make such products well, we need to comprehensively consider multiple factors of "people, machines, materials, methods and environment", that is, 4m + 1E in our usual management is indispensable. First of all, we understand the material characteristics and quality standards of this kind of products, which is the main basis for us to formulate the process route, operating procedures and equipment configuration. Cigarette pack paperboard has almost strict requirements for appearance, and has very high requirements for flatness and gloss. At the same time, it also has very high functional requirements for the adhesion strength and folding resistance of aluminized transfer layer.
1、Material characteristics
take 250gsm cardboard composite pet transfer film as an example. We need to consider several characteristics of the material:
1) cardboard is a rigid material with high stiffness, thick thickness and large thickness deviation.
2) cardboard is a water absorbent material, which is relatively sensitive to environmental humidity, and its moisture content directly affects the glue amount.
3) aluminized transfer film is also a rigid material with high thickness and flatness, How to ensure the full fit of two layers of rigid materials in the process of compounding and winding is a problem that must be solved.
4) there are paper scraps in the paper jam, which will affect the appearance and composite strength.
5) the unwinding diameter of the paper jam exceeds 1300mm and the winding diameter exceeds 1600mm.
2、 Equipment requirements
1. Tension control: the paper jam unwinding and winding tension is large enough, and the maximum winding tension needs to be no less than 60kg. M. at the same time, it is necessary to maintain the stability of tension in the winding process. Zhoutai's unique double taper tension control mode (both winding tension and winding roller pressure are controlled by automatic taper) can ensure the winding effect of paper jam to the greatest extent, Because when the winding diameter is large enough, the torque transmitted by the motor alone through the tension control mode of central winding is not enough to achieve the same tightness of the winding table and the winding core. At this time, the importance of the winding pressure roll is fully reflected. At the same time, due to the low initial viscosity of solvent-free composite, we adopt the full closed-loop tension control mode, and drive the floating roller through the Japanese Fujikura low friction cylinder to gently control the material tension, so as to fully protect the material and prevent the relative displacement of two rigid materials due to the fluctuation of tension.
2. Glue amount control: as the cardboard is a water absorbent material, part of the glue will be absorbed by the paper fiber. Only the glue left on the paper surface can contribute to the composite strength. Therefore, the moisture content of the cardboard and environmental humidity have a significant impact on the glue amount. Therefore, each equipment has the function of temperature and humidity online monitoring, and the installation position of the humidifier is reserved, Provide reference for customer process adjustment; In addition, the coating unit of the equipment adopts three servo control mode and cooperates with zhoutai's unique large-diameter rubber roller. When using single component glue, the maximum glue amount can reach 5gsm, effectively covering all kinds of products with glue amount requirements. In addition, the cleaning of solvent-free gluing unit is very important but cumbersome, especially the cleaning of single component glue, which gives operators a headache. The equipment is specially equipped with automatic cleaning function and rapid roll change function. There is no need to use the traditional foot switch to rotate the steel roll for cleaning, so as to shorten the cleaning and order change time.
3. Composite unit: since most of the paperboard composite uses single component glue, the viscosity of the glue is relatively high, the leveling performance is poor, and the thickness deviation of the paperboard is large, so at the composite unit, in order to ensure the full leveling of the glue and the close fitting of the material, the composite unit of the equipment adopts a three roll composite structure (i.e. composite steel roll, composite pressure roll and back pressure roll), The deformation of the composite rubber roller is overcome by the back pressure roller to ensure reliable and sufficient lamination. At the same time, because the single component glue needs high-temperature heating, the equipment is equipped with high-efficiency cooling roller before winding after lamination.
4. Others: in addition to the three key control points of tension, gluing and compounding, other details of the equipment also have special design, such as wrap angle of guide roller, type selection and installation of dust removal device, configuration of fast receiving roller, unique deviation correction design, software design, etc.