The composite adhesives are mainly solvent-based. The main adhesives for solvent-based adhesives are SBS and terpene resins, and the solvents are toluene, gasoline No. 120, and ethyl acetate. Since some of the components in the printing ink are close to the components of the solvent-based coating adhesive, and both contain the resin and the organic solvent, the quality of the paper-plastic composite is not very stable. Especially in color textbooks, the problem of blistering is even more pronounced. The cover of the film does not cover the book block and does not blisters. After a pack of book blocks, it blisters. At the same time, solvent-based adhesives have unfavorable factors such as low flash point, flammability, toxic, harmful, polluting the environment, and affecting operators' health. Composite adhesives are primarily solvent-based. The main adhesives of solvent-based adhesives are SBS and terpene resin, and the solvents are toluene, No. 120 gasoline, and ethyl acetate. Because some components in printing inks are close to those of solvent-based paint binders, they all contain resins and organic solvents, so the quality of paper-plastic composites is not very stable. Especially in color textbooks, the blistering problem is more prominent. The film cover does not cover the book block and does not blister. After a pack of book blocks, it blistered. At the same time, solvent-based adhesives have unfavorable factors such as low flash point, flammable, toxic, harmful, polluting the environment, and affecting the health of operators.
In recent years, people's requirements for product quality and environmental awareness are getting higher and higher. Therefore, it is an imperative development trend to study the use of non-toxic and stable coating adhesives.
Experiments on water-based film adhesives
In order to test the temperature resistance, moisture resistance, oil resistance and other properties of the printed film after coating, the testers conducted some routine comparative tests.
1. Temperature test
The solvent-based film-coated prints and the water-based film-coated prints were put into an oven at the same time, and the temperature resistance test was carried out at 70°C. After 25 minutes, the print for the solvent-based film was wrinkled, and after 28 minutes, the print for the water-based film was only wrinkled. After testing, the water-based film adhesive meets the temperature resistance requirements of the printed film.
2. Water resistance test
Both coated prints were immersed in water at the same time. After soaking for 24 hours, rub by hand to separate the paper fibers from the film, and observe the remaining ink layer and fiber amount on the film. If there is more residue, it means that the glue has good water resistance after drying. Tests have shown that the water resistance of the water-based film adhesive is better than that of the solvent-based film adhesive.
3. Oil resistance test
Both water-based and solvent-based lamination products contained a certain amount of ink, and degumming and foaming were observed. Solvent-based testing found blisters within 1 day. However, no blistering or blistering was found in the water-based film adhesive for 5 consecutive days. Proving that water-based film adhesives are superior to solvent-based ones. The water-based film adhesive is water-soluble and can be diluted and cleaned with ordinary tap water. It is non-toxic, harmless and pollution-free.
Experiments show that the application of water-based film adhesive is feasible. Once the UV light intensity has decayed, the lamp must be replaced. In order to ensure the quality of the product, do not limit the use of the light source without increasing the exposure time.
3. Correctly grasp the developing temperature and time
Since the main resin of the photosensitive ink contains hydrophilic groups, it has good solubility in weak alkaline aqueous solution. It is usually developed with 1% to 1.5% sodium carbonate aqueous solution. The ink without hydrophilic groups will dissolve when exposed to ultraviolet light. Lose. During the development process, the temperature has a great influence on the dissolution rate of the ink. Increasing the developing temperature is much faster than increasing the concentration of the aqueous sodium carbonate solution. Usually, the temperature of the developer is controlled within the range of 30 to 34° C., and the development time is 15 to 30 seconds. If the temperature is too low, the ink will dissolve too slowly, and the residual ink will remain on the product; if the temperature is too high, it will damage the ink film or line deformation of the light-cured part, affect the mechanical strength of the ink film, and reduce the electroplating resistance and etching resistance. . Four, photosensitive ink coating method
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