Exposure of four main causes of plastic film dry lamination "sticking edge" failure
Release time: June 15, 2020 13:21:17 reading volume: 1213 times
so-called “ Gluing edge ” It refers to that after the plastic film is coated with glue, it is heated and dried by the drying channel. After the substrate film and composite film are extruded by hot pressing steel roller, both sides of the winding product appear “ Gluing edge ” Phenomenon. Rewinding of finished products “ Gluing edge ” After the film is firmly bonded, it is difficult to separate the film. This phenomenon is most likely to occur in the use of two-component two-liquid reaction adhesive. When the composite product is seriously broken and deformed, the product will be scrapped directly. There are many kinds of edge sticking faults in the composite process, “ Gluing edge ” The probability of failure will be minimized.
"Sticking edge" fault is related to the amount of glue on the coating
We know that the amount of glue is determined by the depth of the glue roller and the operation concentration. But in fact, many small enterprises still use the non scraper type compound machine. The biggest difference between the non scraper type compound machine and the scraper type compound machine is that: "the glue loading amount of the former is adjusted by the screw rods at both ends of the upper rubber roller, while the latter is that the scraper directly scrapes the rubber net roller; the depth and operation concentration of the net roller directly affect the glue feeding amount; the non scraper type adjusting glue feeding amount is adjusted through the screw rods at both ends of the upper rubber roller 。 In fact, it is to adjust the pressure between the top rubber roller and the net roller. The pressure is light and the amount of glue is large, but the amount of glue on the contrary is small. In the process of operation, if the pressure of screw rods on both sides is not adjusted properly, the gluing must be thick and thin, and the thick side will adhere after being extruded by hot pressing roller. It is often left on the hot steel roller by glue, and the glued side will give out "Chi Chi Chi" sound. At the same time, the film on the thick side of gluing will bend inward, affecting the flatness of the product.
The solution is divided into two steps:
1. First of all, screw rods at both ends should be compressed before gluing, and the amount of glue should not be too large during operation.
2. The most direct way to detect the amount of glue is to squeeze the upper cot with the index finger, and observe the depth of the glue liquid at the extrusion position of the top rubber roller. Only when both sides are consistent can we point out that we must pay attention to safety, and it is best to complete it by skilled workers. If the scraper is used to scrape the upper glue roller, the amount of glue is determined by the depth of the roller and the operation concentration. The pressure and angle of the scraper are also very important. If the pressure of the scraper is not enough, there must be more glue on the roller. Because of this, the edge of the composite product will stick. The angle between the scraper and the roller is often adjusted in the thirty-five If the angle is too large, it is easy to damage the mesh, shorten the service life of the roller, the angle is small, the glue is more, and the edge is easy to stick. The pressure of the scraper is adjusted by a hand wheel, and the angle of the scraper is adjusted by the screw wheel on the tool holder.
The edge sticking fault is related to the drying temperature
The drying system of dry compound machine is divided into three areas, namely evaporation area, hardening area and odor elimination area. The energy consumption of the three sections is almost equal. The temperature of evaporation zone is generally controlled at 60 - seventy In general, the hardening area and odor elimination area are controlled within seventy — eighty Between ℃. Of course, with the changes of ambient temperature and humidity and the structure of composite products, corresponding adjustment is made.
In practice, we notice that the width of the substrate is more than 1500px, and the thickness is less than 1500px 38µm When above, it should not be lower than the temperature control sixty-five Otherwise, it is easy to stick, and at the same time, it is related to the machine speed 80m/min The drying channel should also be relatively higher in temperature, which is conducive to the volatilization of flux, no odor left, and rapid reaction of molecular bonds in the glue solution, which is good for quality. Of course, if the drying temperature is not up to the requirements, the two ends of the film are easy to stick after being extruded by hot steel roller. Experts often have such a sentence: both sides of the membrane stick, speed and temperature are related. It can be seen that temperature control is very important.
3、 The edge sticking fault is related to the width of the material
If the width of the printing substrate is larger than the width of the composite film, the edge sticking will happen. At the same time, the glue will stick on the hot pressing cot, which will seriously affect the quality.
Solution: increase the width of composite film. Under normal conditions, the width of thick composite film is 25px larger than that of printing film, that is, both sides are separated 0.5mm To prevent edge sticking failure. Another way can be solved. But there are some limitations, this method is only suitable for BOPP/OPP Heat sealing or OPP/PET The so-called "lamination" refers to the lamination of the lamination. Because the composite material is narrower than the printing material, the phenomenon of "sticking edge" is avoided. When coating the composite, it should be noted that the corona treatment surface can not be reversed, that is, the film treatment surface is used for gluing.
4、 Other factors cause edge sticking
In dry lamination, due to the selection of glue pressure roller, the purpose of the pressure roller is to compact the printing film and the coating roller, so that the coating is uniform and does not produce bubbles. The width of pressure roller is generally 12.5px less than that of printing film. In particular, when the film on the roll is too large to cause the film to stick PA/CPE It is most likely to occur when combined. In addition, the printing substrate is not smooth, the left and right swing in the process of operation, and displacement occurs when coating and gluing, which is easy to stick to the boundary.
Solution: the printing substrate is first rolled with a leveler, so that there is no displacement in the composite, and there is no glue attached, thus avoiding the edge sticking fault of the finished product. Of course, the high-speed dry compound machine has electric eye tracking, so there is no need to roll flat.
The edge sticking failure of the composite product is also related to the hardness of the upper cot. We have noticed that the two-component cots are easy to "harden" after using for a period of time. The "hardened" cots lack elasticity and tend to overflow when gluing compared with new cots. The overflow dehydration "runs" towards both sides, which creates conditions for "sticking edge". The solution is to place the top rubber roller in the curing chamber for curing one — two The temperature is controlled at fifty The degree of hardening is improved at about ℃. Make it evenly coated, there is no glue phenomenon. It reduces the probability of "sticking edge" failure, and the hygiene on the traction roller is also very important. If glue is attached carelessly, it must be wiped clean to avoid sticking the roller and edge, which must be paid attention to.
In addition, the edge sticking of the composite products is also related to the depth of the wire roller and the machine speed. When the depth of the wire roller is too large, the amount of glue is too thick, and the machine speed is too fast, the coated substrate can not be completely dried in the drying channel, resulting in glue overflow when the hot glue pressing roller and hot steel roller extrude, not only the steel bonding roller and hot glue pressing roller bring inconvenience to the operation, but more importantly, the product layer adhesion occurs Therefore, when the glue feeding system is of scraper type and the depth of wire roller determines the amount of glue, the selection of wire number of wire rod is very important. For special products such as cooking bags, it is required that the glue is thicker. In this case, as long as the machine speed is reduced and the drying temperature is increased, until the edge does not stick.
To sum up, all kinds of faults can be reduced to the lowest point.
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