Aluminized paper: the green pursuit of the packaging industry (below)

Third, aluminum printing paper printing and ink

Aluminized paper is a special printing adaptability, and the surface of the aluminized layer has a metal characteristic. In the printing process, the characteristics of the aluminized paper surface are directly related to the printing adaptability of printing materials such as printing ink. Therefore, the printing adaptability of the aluminized paper is actually easier to grasp than the printing adaptability of the aluminum foil. Aluminized paper has high surface strength, it can adapt to the speed of high-speed printing presses, and it can also withstand the pulling force generated by the value-added of ink stickiness. It has good adaptability to improve production efficiency and stabilize printing quality. Aluminized paper surface tension is conducive to the transfer of ink during printing, printing ink film flat, smooth, clear and complete graphics. The aluminized paper has a relatively compact structure with essentially no gaps and its surface is similar to a mirror surface. Therefore, aluminum-plated paper does not have absorption properties like ordinary paper and has low absorption.

The color arrangement of printing should generally highlight the main style of the design. In the printing, the color of the first printing and the color of the after printing are different due to the color sequence. The effect is also very different; the absorption performance and drying performance of the aluminized paper In terms of particularity, it is recommended that the printing of multi-color printing presses should follow the following points: Colors that are dark in color and small in area should be printed in advance. Generally, a large-area background color should be printed in the final print. Such as the first printing a large area on the ground, will cause the back of the color overprint is not on, but also easy to scratch the back of a few colors in the back of the printing, scratching the surface of the background color, resulting in a decline in product quality, affecting the appearance and design effects. The main colors should be printed at the back. In general, completely transparent ink does not exist, the hue of the printed product tends to favor the hue of the post-printing color; the color of the overprinting accuracy should be printed first. Because aluminum-plated paper has the dual physical properties of metal and paper, it should be printed on the front with a high-precision color. There are strict requirements in the design of cigarette packs and beer bottle stickers. When designing manuscripts, it is necessary to fully consider the lines of the printed products and the automatic packaging lines to avoid unnecessary losses.

In terms of ink and drying requirements for printing aluminized paper, penetration is the basis for fixing the ink on the substrate. The fixing speed is the drying condition of the ink, and the drying time is the key to the ink conjunctiva. Penetration is the basis for fixation. In resin inks, the binder for high-grade inks consists mainly of resins, dry plants, and pigments. Fixing speed is determined by the instantaneous penetration of pigment oil on the substrate, and it also relates to the drying time of the ink. In order to penetrate the ink, it is necessary to have a substrate with good absorption performance. However, the absorption performance of aluminum-plated paper is not ideal, whether it is the use of fast-drying, bright fast-curing offset ink, or synthetic ink offset ink, plating Aluminum ink still has liquid solvents after it is inked. This kind of ink is not only the main cause of product stickiness, but also the cause of poor drying. To avoid sticking and improve drying performance, special inks must be used.

POP ink is an ideal choice for aluminized paper printing. The main advantage over other inks is that other inks cannot be applied to vacuum aluminized films, gold and silver cardboards, films, synthetic papers, and various non-absorbing materials due to adhesion and drying problems. Printed on the material. Therefore, when printing non-absorbent materials, the price of using POP ink is only compared with UV ink. The price of POP ink is only half that of UV ink, and the color is brighter than UV ink, and it is not easy to crack. POP inks can be printed with a general offset press. Unlike UV inks, they require a high-power light curing machine. Printing presses for POP inks do not need dedicated ink rollers, blankets, blister covers, washing water, etc. UV inks are different. All consumables need proprietary and expensive than POP inks. Therefore, using POP ink has a certain price advantage. In the process of using POP inks, the minimum amount of platemaking water should be controlled. The pH is generally between PH5-6. The dampening water temperature should not be too high, otherwise it will cause emulsification, generally between 10-15°C. In the case of adding desiccant or other additives, the amount should not exceed 2%, and the speed should not be too fast, it is best to control at 8000-10000pcs / h. The temperature and humidity of the printing shop should not be too high. Otherwise, the moisture on the printing surface will increase, resulting in emulsification. Generally, the temperature is controlled at 25-28°C and the humidity is about 60%.

Fourth, aluminum coated paper conforms to the trend of environmental protection

As far as cigarette packs are concerned, Chinese tobacco packaging has been moving from soft packs, ordinary white card hard packs to glass cards, and popular aluminum foil gold and silver cardboard in recent years, and high-grade matte technology using PET composite cardboard. The forefront of the packaging industry. Although aluminum foil gold and silver cardboard and PET composite paperboard have become high-grade packaging materials with good decorative performance and anti-counterfeiting performance, they are non-environmental materials. In order to meet the requirements of environmental protection and reduce the need for packaging costs of cigarettes, it is an inevitable trend to replace aluminum foil cardboard and aluminized gold and silver cardboard with aluminum-coated cardboard.

The biggest advantage of composite aluminum foil liner is good moldability and excellent sealing. At present, aluminum spray paper not only meets the requirements of cigarette packs in terms of performance, but also the aluminum layer thickness of aluminum spray paper is only 1/200 of composite aluminum foil and weighs only 1/125. In the transfer of aluminum spray paper, due to solving the problems of brightness, folding resistance and printing adaptability, compared with aluminum foil composite card and PET composite paperboard (commonly known as "bright card"), it has better cigarette pack formability, not Burst, no deformation characteristics. Aluminum foil gold and silver cardboard can neither be recycled as aluminum products, nor can it be recycled as paper. PET composite paperboard is a composite product of aluminized film and paper, plastic film can not be degraded, it is not conducive to environmental protection. Governments in developed countries use tax policies to promote the use of environmentally friendly materials, making aluminum-sprayed liners widely used in recent years. Because aluminum-sprayed liners are classified as single materials, with a mark of 0.4 mark/kg, and aluminum foil composite liners as composite products, with a tax of 2.10 marks/kg. This legislation has had an explosive impact on the cigarette industry. The original aluminum foil composite paper packaging materials have begun to transfer to aluminum-plated paper. Aluminum spray paper and transfer aluminum spray paper have also begun to receive widespread attention and application in China, especially in cigarette package materials. After solving a series of problems in printing and forming technology, aluminum spray paper, especially transfer aluminum spray paper, has been applied to cigarette packs on a large scale.

The aluminum layer of aluminum lining paper is 0.02 μm thick, and the thickness of aluminum foil composite lining paper is 7 μm. The difference between the two is more than 300 times. The consumption resources of aluminum liner lining paper are obviously lower than that of aluminum foil composite lining paper, but their The appearance and barrier properties of steam, water, and light are almost the same, and aluminum-sprayed liners are easier to recycle, burn, and easily oxidized and degraded after disposal. After the cigarette box is discarded, its aluminum layer is oxidized in a short period of time and will not cause environmental pollution. After the waste is collected, it can also be sent to the paper mill for recycling. The price of sprayed aluminum paperboard is 10% lower than that of aluminum foil paperboard. The speed of cigarette packaging machines printed on sprayed aluminum paperboard is significantly higher than that of cigarette papers made of aluminum foil composite paperboard (approximately 200 bags/minute higher). Due to the above reasons, the widespread use of sprayed aluminum paperboard will also form a trend.

Author: HU Zhi-peng

Source: "Printed Materials in China"

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