Hot stamping process experience sharing

At present, the cold-hot process has become a hot spot in the Chinese market. In fact, European countries and the United States began to develop this technology many years ago. The Kurz company, as a leader in the hot stamping industry, has been devoting itself to research in this area. At that time, customers in Europe and America also encountered problems such as leaks and unclear edges. Everyone has made unremitting efforts, and in the last few years it has been able to successfully apply the cold-scalding process. Now these customers can use the cold ironing process normally to feel the convenience and advantages brought by this new process. The application range of the cold-scalding process is more and more extensive, and the market has a very large space for development. Therefore, Kurz hopes to bring mature technologies from Europe and the United States to Chinese customers and help Chinese customers successfully use this new process.

What is a cold ironing process

Cold foiling refers to the preprinting of UV-curing glues and the transfer of cold foils to the substrate to be stamped. The basic equipment configuration is:
- Presses (flexographic, offset, letterpress printing)
- Cladding unit - Unwinding unit - Rewind unit - UV curing unit

Therefore, most of the commonly used roll label printers with film or round hot stamping units are already suitable for cold ironing. Other modifications may be suitable for cold rolling, and most equipment suppliers can provide specially designed cold pressing components. .

Cold process (in flexo printing, for example)

UV adhesive can be printed flexo or offset. In both of the above methods, the UV adhesive is first applied to the substrate, then the cold foil is applied, the UV curing is performed before the peeling, and finally the peeling is performed.

Advantages and features of the cold ironing process:

Nowadays, the competition between industries is very fierce. Everyone is looking for efficient, low-cost but innovative printing solutions. The cold-hot process can be said to be the right choice. We are now promoting the cold-scalding process. Instead of using cold lapping to replace hot lapping, cold lapping and blanching are two completely different processes. Each has its own advantages and disadvantages. Therefore, we need to understand the characteristics of each process, combined with the conditions of its own equipment and project requirements. Try to use their advantages to make the best choices.

Some hot stamping projects have many problems that cannot be solved if they use hot stamping, but they can be easily completed if cold stamping is used. The cold ironing process can achieve the gradual effect that cannot be obtained by the traditional blanching process. If this effect is combined with the design theme, it will bring a new design effect and feeling. The advantages of the overall cold-ironing process are as follows:

* Low investment costs - no need for hot stamping experience and special stamping equipment, stencils, stamping tools or gaskets * Flexible, efficient, economical - especially suitable for low volume production * Low cost, high efficiency - available Standard printing plate * High speed, effective - production speeds up to 120 meters per minute * Can be used on thin and soft or heat-sensitive packaging materials - such as heat-shrink film hot stamping possible, etc. * Printing, hot stamping online Completed at one time - easy to control printing accuracy * Break through the tradition, bring a vivid three-dimensional effect - can create a metallic half-tone gradient effect

However, the cold ironing process also has disadvantages:
*The ratio of foil to substrate is 1:1. It is not possible to save the foil consumption. However, this conflict can be alleviated in the design as much as possible. * Not suitable for rough substrate surfaces, but it can be solved by process cooperation. * Existing curing adhesives are not Applicable to some plastics, but cold glue suppliers will increase with market demand

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Application Tips for Cold Press Technology:

In general, any flexo printing project can be cold-hot. This process requires coating, lamination, and stripping units. Using a cold stamping process, a gradual cold lapping effect can be achieved depending on the glue, substrate, roller, and plate used. To achieve a good hot stamping effect, all units are required, including the number of lines, the amount of glue applied, the UV lamp power, the plate hardness, the peeling angle, the substrate, the UV curable adhesive, the cold foil, etc. .

* The glue on the cold-hot glue market is very diverse. You must test carefully and choose the right glue for you. The manufacturer's product specification sheet should indicate whether their product is suitable for a free-radical UV-curable ink coating and whether it can be used in solvent-based or liquid-based inks.

* Types of substrates that can be cold-stenciled In fact, all materials that can be printed on a flexo press, such as PP, PE, and non-absorbent paper, can be cold-sealed. If there is a problem with adhesion, it can be solved collaboratively with the glue supplier. Under normal circumstances, after corona treatment and printing, the effect will be more ideal.

*Ink Roller - The average amount of glue depends on the pattern, select the right number of ink rollers. We do not recommend UV adhesive directly on the rough, untreated material surface. It should be primed first.

*Foil coating unit We recommend that after applying UV glue, apply cold foil with a suitable hardness of silicone roller, and the tension of the feeding/winding unit is appropriate to prevent wrinkling. If the hardness of the nip roll is too low, the cold foil transfer effect is not good. The rollers of the foil-coating unit must be completely clean and dust-free. The proper pressure of the foil-coating unit is critical to avoid bubbles, which can cause poor transfer.

*Applicable UV lamp
UV curing should use medium or high pressure mercury lamps. The lamp power should be adjustable with the operating speed.

* The distance between glue coating, cold foiling, UV lamp curing and stripping process is required to avoid wrinkles. The shorter the distance between the processes, the better. There should be no idler between the foil cover and the stripping unit. In the general structure, the distance from the glue coating to the peeling process should not exceed 1 meter. The processing speed is generally 45-120 meters per minute.

* Possible problems and solutions

*Remember: Improper use of glue will directly lead to poor quality of cold foils* If cold foil cannot be transferred, check the glue quality * Make sure the glue is fully cured, if necessary, increase the power of UV lamps * If glue Do not bond to the substrate, increase the power of the UV lamp or corona treatment to obtain higher surface tension * Too thin glue coating or too little nip roll pressure will cause pinholes in the cold hot part * The glue is not fully cured , UV lamp power is insufficient or the use of defective cold foil will lead to reduced wear resistance or poor adhesion * If the processing speed is low, you need to adjust the power of the UV lamp * If the cold transfer foil is not smooth, adjust the pressure roller or pressure Feed Roller Pressure * Incorrect roll pressure setting will cause uneven edges. Adjusting the roll and nip roll pressure can prevent this from happening. * Note the effect of the peeling angle on the transfer of the foil. * If the foil tension is cold Too large, cracks appear on the surface after hot stamping. * If stenciling occurs, reduce the amount of glue or increase the hardness of the nip roller.

Promotion work and successful design case:

Kurz is not satisfied with the ordinary lines and the cold-hot effects of the text. We also hope to use the half-tone effect to match the theme of the design so that the final effect can be vivid or layered. Therefore, we and our partners have been constantly debugging and trying to explore and accumulate certain experience. Successfully expressing this network and gradient effects in different design patterns has not only won favorable comments from domestic customers, but also has just ended in Chicago, USA. The show was also very popular. It is believed that it will bring new feelings and choices to the market and printing industry.

After unremitting efforts, many domestic customers have successfully applied this technology to the label industry, such as transparent beacons and personal care products. In the near future, everyone can see that the cold-ironing process will be used in cigarette packs and packaging. Widely used in such products, the outlook is encouraging.

The application range of the cold ironing process:

Packaging: Wine label, medicine label, beverage label, candy paper card, wine box, film box, cigarette pack food and medicine: shampoo label, toothpaste box Cosmetics: Lipstick, cream, makeup box Others: Greeting cards, leaflets Zhang

Reprinted from: China Labels and Threads