2 How to solve the problem that the film product is not bonded?
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If the printing format is too large (or printing in the field), the contact area between the surface of the paper and the adhesive will be reduced, and the adhesive effect between the surface of the printing product and the adhesive will be reduced, and the quality and service life of the coated product will be greatly reduced. . Therefore, it is best to avoid laminating large-format or printed products in the field.
If the printed ink layer is too thick, the hindrance to the adhesive will increase, and it will directly cause delamination, and thus it cannot be bonded. Comparing the characteristics of the ink layer obtained by various printing processes, the thickness of the ink layer of the offset printing ink is the lowest, which is 1 to 2 μm. Therefore, it is preferable to select the offset printing for offset printing, and to pay attention to controlling the overprinting effect and printing of the color printing. The final ink layer thickness.
Also, undried inks can cause the film to expand and elongate, resulting in blistering of the film product and thus poor adhesion. The key to solving this problem is to ensure that the ink is completely dry before coating, and that it can be accelerated by assisted drying, but the use of ink adjuvants should be minimized because excessive use of drying oil will increase the smoothness and fineness of the ink layer surface. , thereby exacerbating the adhesion of film products. At the same time, attention should be paid to reducing the use of dusting and the influence of the shop environment on the film coating of the printed product. The dusting on the surface of the printing product and the dust and impurities adhering to the surface of the printing product in the workshop may interact with the adhesive. The "false adhesion" phenomenon makes it easier for the printed product and film to separate.
Film coating process
The film-covered product is finally completed by a lamination process, and the quality of the lamination depends on the effect of the lamination process. The coating process parameters mainly include the drying effect (ie, the coating film process), the composite temperature, the composite pressure, the coating condition of the adhesive, and the coating speed. Here, the author analyzes the drying effect of the adhesive, the effect of the binding force of the adhesive, and the effect of the coating pressure.
1. Drying effect of adhesive
The drying effect of the adhesive and the drying condition of the ink on the surface of the printing ink have similar effects on the quality of the coating film. If the solvent is not completely dried, the film will expand and stretch, causing blistering, which will result in false bonding.
2. Adhesive binding effect
The adhesive effect of the adhesive is mainly considered in two aspects. One is the application of adhesives, which requires that the adhesive on the surface of the film is uniform and effective, and the thickness of the adhesive must be controlled according to the surface characteristics and structure of the printed product: if the thickness is too thin, the adhesive will be reduced. Force; too thick, it will affect the drying speed. The second is composite temperature, which affects the molecular energy and molecular force of the adhesive. When the molecular force is too small, the adhesion of the film product is too small. In addition, if the composite temperature is too high, the structure of the film will be damaged. Generally, the composite temperature is controlled at 70 to 90°C.
3. Effect of film pressure
The effect of film pressure is affected by two factors: composite pressure and film speed. The composite pressure will promote the penetration and diffusion of the adhesive, and its size should be considered in conjunction with the coating material and other processes; the coating speed is also a multiple-influencing parameter, and its size will affect the coating thickness of the adhesive and the drying speed. Combine with other factors to adjust at the same time.