Flexo printing cold hot gold pine paper technology

With the mass production of flexo printing red tri-ring corrugated paper, the process of common flexo-printing tipping paper is becoming more and more mature, and the company has begun to advance to higher-level foil-type tipping paper. Under the premise of existing equipment, the technology of flexo-printing cold-seal gold tipping paper is placed in front of us. Under the guidance and strong support of the company's leaders, after several times of proofing, the first test and the middle test have finally been completed. Production, which condenses the hard work of Antai countless people.

Cold Stamping Process Introduction

Cold foil stamping is a printing decoration process that uses UV transfer adhesive to transfer the foil stamping film to the substrate. The actual process is to use a printing unit with a UV drying device as a glue coating unit. When the substrate passes through this unit, All parts that need to be glued are coated with a transfer adhesive. After the film is pressed through the stamping film, the hot stamping film is transferred to the glued part, cured, and finally peeled off. Its main material is cold film and transfer glue. From the aspect of cold film, it is the same as the number of layers of hot stamping foil, but its adhesive layer is required to maintain good quality in the case of high speed and low pressure. Viscosity; protective layer requires better gloss, high clarity and easy peeling; peeling layer should have good peelability. The transfer of glue plays an important role in the cold stamping process, and the glue that matches the hot stamping film must be used to obtain a satisfactory cold ironing effect.

Blue Yipin Cork Paper Flexo Printing Line Cold Stamping Process Difficulties

Cold-foil technology is currently mainly used in labels and hose-type products. After rapid development, it is gradually applied to the hot stamping of cigarettes, and its application on water pine paper is less. The customer sample of the blue one-pin pine paper products undertaken by the company is made by gravure printing and round-press hot stamping. Its difficulties include the following:

1. Substrate special

The basic weight of the base paper used to print blue water pine paper is 32 g, and its thickness is only about 0.037 mm. It is easily deformed, wrinkled, and broken during the production process. This inconveniences the operation. At the same time, the tobacco factory produces a tipping paper product. The grammage and moisture content are strictly regulated. The gram weight and the high or low moisture content affect the speed of the hood. This requires the operator of the machine to strictly control the amount of ink applied and the temperature and humidity of the shop. Through the constant exploration of machine personnel and instrument detection, the mutual separation and humidification between printing units can reduce deformation and avoid wrinkling, and at the same time obtain a stable weight and moisture index.

2. Hot stamping pattern is complicated

The gold lines, Huangshan Chinese and English characters in the printed pattern are the parts that need to be transferred. In addition to the gold lines, the fonts in the Chinese and English characters of Huangshan are small and the writing is clear. There is a certain degree of difficulty in the flexo platemaking, except that the resin version should be considered. Compression deformation, but also take into account the printing rate of India; at the same time printing corrugated paper version are mostly seamless version, and the traditional flexo plate process flow is different, the production process includes: processing version of the drum, package Rubber, laser engraving and cleaning processes, the quality of the printing plate first and foremost in the selection of the plate, the rubber version of Shore hardness 60 degrees to 65 degrees is suitable for the cold plate; then the image processing of the laser engraving process. Blue Blue's face blue, transfer version is after many image processing and continuous plate trial to meet customer requirements.

3. The key is UV transfer

(1) Due to the particularity of the substrate and the complexity of the gold foil pattern, the cold stamping process has been increased to a certain degree of difficulty. The UV transfer requires the selection of an appropriate number of anilox rolls and the corresponding UV lamp power. Here, the anilox roll It is mainly used for quantitative gluing, and the amount of sizing directly affects the transfer effect. The power of the curing lamp can be adjusted with the operation. The higher the operating speed, the greater the power of the mercury lamp. During the production process, UV lamps and reflectors should be kept as clean as possible. Dirty, dirty spots, and stickiness of transfer adhesives are not allowed; at the same time, UV transfer glue, gold-plated film primer and printing ink are not allowed. Matching directly determines the effect of cold ironing. After the manufacturer's recommendation and trial and error, we have chosen the matching UV transfer adhesive and gold foil primer, but we still cannot achieve the desired transfer effect in the production process. Finally, we found that the blue ink and the first two are adapted. Poor performance, after analysis by coating a layer of binder on the blue ink surface, the transfer effect meets the customer's requirements.

(2) Distance between glue coating, cold foiling, UV lamp curing, and peeling process requirements: To avoid wrinkling, the shorter the distance between the units, the better. There should be no idler between the release film and the peeling.

In a typical structure, the distance from the glue coating to the stripping process should not exceed 1 meter. The peeling device must be safely and stably installed in the UV unit. It not only plays the role of peeling off the metal foil, but also makes the metal foil not affected by the separation before the UV treatment. In addition, it can also reduce surface wrinkling and cornering. When recycling metal foil waste, pay attention to adjust the winding tightness to prevent wrinkling and separation.

Reprinted from: China Packaging News