Discussion on the operation technology of pre-film lamination and its influence on the suitability of binding book binding
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
In recent years, the film of the textbook is basically using a pre-coated film. Since we have not used it for a long time and there are many problems, according to our process practice, the quality of the precoat film is mainly temperature and pressure. Three factors of speed, so the correct handling of the relationship between the three is essential to ensure the quality of the precoat film and the impact on the production of the next process.
We know that paper-plastic coating is the result of the physical interaction of thermocompression, temperature, pressure and speed are realized.
This three basic factors of physical integration, the correct handling of the relationship between the three is the key to process technology.
Temperature: It is the first key of the film. The adhesive for the pre-coating film is hot melt adhesive. The temperature determines the melting state of the hot melt adhesive, which determines the leveling performance of the hot melt adhesive and determines the molecular direction of the hot melt adhesive. BOPP film, printing ink layer, paper substrate and other three molecules between the molecules of the diffusion capacity, but also determine the crystallinity of the hot melt adhesive, only the correct control of the temperature of the working area, in order to make the precoat film solid heat on the film The molten rubber layer is completely melted into a viscous flow state, and has suitable fluidity to achieve wet adhesion to the surface of the printed matter, and to ensure immediate curing after compounding. The laminated product is made to have a flat appearance, is bright enough, has a good degree of melting of the rubber layer, and has no creases. And can peel off the ink. The temperature control of the laminating process also affects and determines the thermal melting of the film to solve the change in heat and the resistance to new heat. Therefore, strict temperature control is the primary key to precoat film coating. According to our practice. Temperature control is between 80 and 100 The range of C is suitable.
Pressure: Appropriate pressure should be used while properly controlling the lamination temperature, because the surface of the paper itself is not very flat. Only under the action of pressure, the hot melt adhesive in the viscous state will be in the process of driving away the air on the surface of the printed matter. Fully wet the surface of the paper print. Produce colloidal molecules to the ink layer of the paper print, the diffusion between the paper molecules, dislocation, and achieve good adhesion, forming a complete coverage of the entire surface of the printed matter, so that the printed matter is bright, no fog, flat layer of glue, no crease The bonding effect is good. If the pressure is not increased, the thermoplastic curing machine of the hot melt adhesive can be fully expressed without proper wrinkles. In order to ensure that the film product is added after the compounding process. It has strong resistance to various physical peeling, impact and other effects. (such as indentation, bronzing, hot melt glue, etc.) to achieve a perfect uniform speed of the internal structure and surface state of the composite print: the paper film is a composite movement in the dynamic process. The speed of movement determines the time that the paper-plastic composite stays in the thermocompression working interface, and also determines the temperature and pressure of the laminator input and the cooperation of paper and plastic in the actual production process. Actual action value. When the film temperature and pressure are fixed. The change of speed will change the film coating effect, and because of the upper limit of temperature and the limitation of pressure supply, it will only change from the direction less than the set value, and with the acceleration of speed, the amplitude will decrease obviously, and the hot pressing force will decline. Make the composite effect worse. Running too fast. The bond is not strong. There will be fog, too slow to be inefficient. Even bubbling.
So the compound runs at a speed. 4. Determine the time for the precoat film and paper print to achieve bonding. According to our experience, the general speed control is suitable for about 10-20 sheets of paper in one minute. (The speed of the electronic laminator is due to hot pressing
The tube is small. The speed should be slower. The actual action value of the three factors of temperature, pressure and speed has a certain range. Due to the difference in equipment.
This requires us to find the best value in practice to ensure the composite effect of the pre-coating film and create favorable conditions for the spine cover of the next process without leaving the shell and not blistering.
The pre-coating compound, how to create favorable conditions for the next process (including indentation, bronzing, vinyl binding, etc.) is also one of the important factors that we should consider in the process of using the pre-coated film.
When the precoat film is combined with the paper print. The lower limit is 80C and the upper limit is 100C. Intuitively, after the composite body is separated from the hot press roller, the brightness is high, no fog, good flatness, and no blistering. In such a temperature range, the hot melt adhesive can fully receive heat from the outside to the inside. Function, the modification of various raw materials in the gel body can be fully exerted, and the entire rubber layer is completely melted. Produces a true, firm bond, rather than a superficial, shallow, unshelled or blistering phenomenon that does not bend or reheat.
When the lower limit temperature is slightly downward, the brightness of the composite product will decrease. When the upper limit temperature is slightly increased, bubbles that are not smooth and have different shapes are burned on the surface of the film. (This phenomenon is particularly obvious in the electronic laminating machine) just right to grasp the critical working area of the film temperature. Not only the composite effect is good, but also the hot melt colloid is close to the hot spot of the cross-linking reaction. The solidification of the colloid is hard, so that it will not soften easily when it is heated again. The correct temperature control method for the film operation is to master this finely. The film temperature is very close to the crosslinking reaction temperature.
Recently, when we used the pre-coated film to cover the cover and then stapled the staples, we found that most of the stapled skins that were split after being wound up showed shell spine and blistering. This phenomenon occurs when the film is removed from the heat source and then water-cooled and immediately split automatically. (Our equipment is equipped with water cooling system and automatic dividing system and winding system for optional use.) The curing time of hot melt adhesive for laminating film is about 10~15s, and the time required for natural cooling in normal temperature of production environment is greater than this. Standard time, especially if the semi-finished product is laminated and wound before splitting. The temperature accumulation between each other is difficult to disperse, so that the natural cooling and curing are prolonged, and it is usually slowly cooled and solidified. Will cause the hot melt to gradually form crystals. The formation of crystals improves the sensitivity of the colloid to temperature, which may cause the softening of the hot melt adhesive again, weakening the high temperature coating operation to approximate the heat resistance function of the cross-linking reaction, so we use water cooling and instant automatic Dividing to prevent heat accumulation, creating a low temperature quenching solidification zone immediately after the film product is removed from the heat source. Let it cool down quickly. The viscosity of the hot melt adhesive in the molten state is rapidly increased. The chain link is too late for exercise. Crystals are difficult to form, which allows the film to heat up again without significant melt softening. For the wireless binding to ensure that the temperature will not cause the spine to leave the shell and blister. In order to ensure the perfect binding of the perfect binding, the quality of the binding and laminating products is guaranteed.