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According to the forecast of Beijing Meteorological Observatory, the lowest temperature in Beijing will be around - 16 ℃ on the night of the 6th. According to statistics, the lowest temperature in Beijing since 2000 is - 17 ℃. If the temperature in Beijing during this cold wave is lower than - 17 ℃, it will be the lowest temperature record since the 21st century.

In the face of the cold wave, what problems should the printing and packaging personnel pay attention to?

Prevent rotary offset ink from thickening in cold weather

For the ink, if the room temperature and the liquid temperature of the ink have a significant change, the ink migration state will change, and the hue will also change.

At the same time, low temperature weather on the high light parts of the ink transfer rate will have a significant impact. Therefore, when printing high-end products, the temperature and humidity of the printing workshop should be controlled in any case. In addition, the use of ink in winter to preheat in advance, in order to reduce the temperature change of the ink itself.

Note that low temperature ink is too thick, viscosity is also large, but it is best not to use diluent or inking oil to adjust its viscosity. Because when the user needs to adjust the ink properties, the total amount of various auxiliaries that can be contained in the original ink produced by the ink manufacturer is limited. If the amount exceeds the limit, even if it can be used, the basic performance of the ink will be weakened and the printing quality and printing technology will be affected.

The phenomenon of ink thickening caused by temperature can be solved by the following methods:

① Put the original ink on the radiator or next to the heater, make it slowly warm up and gradually return to its original state.

② When it is urgent to use boiling water for external heating, the specific method is to pour the boiling water into the basin, and then put the original bucket (box) ink in the water, but to prevent water vapor immersion, take it out when the water temperature drops to about 27 ℃, open the cover and stir evenly. The temperature of printing workshop should be kept at about 27 ℃.

Pay attention to the use of antifreeze UV varnish

UV varnish is also a kind of material that is easily affected by low temperature. Therefore, many suppliers specialize in two different formulations: winter and summer.

The formula in winter is lower than that in summer, which can make the leveling performance of varnish better when the temperature is lower.

It should be noted that if the winter formula is used in summer, it is easy to cause incomplete oil curing and anti adhesion; On the contrary, the summer formula used in winter will cause poor leveling performance of UV oil, resulting in blistering and orange peel failure.

Influence of low temperature weather on paper

In printing production, paper is one of the consumables which have high requirements for environmental temperature and humidity. Paper is a porous material. Its basic structure is composed of plant fibers and accessories, which has strong hydrophilicity. If the environmental temperature and humidity are not well controlled, it will lead to paper deformation and affect the normal printing. Therefore, to maintain the appropriate environment temperature and humidity is the key to improve the quality of paper printing and production efficiency.

The requirement of ambient temperature for ordinary paper is not so obvious, but when the ambient temperature is lower than 10 ℃, ordinary paper will become very "brittle", and the adhesion of ink layer on its surface will decrease in the printing process, which is easy to cause deinking phenomenon.

Gold and silver card paper is usually made of coated paper, white board paper, white card paper, etc., and then compounded with PET film or aluminum foil. Gold and silver card paper requires higher ambient temperature because metal and plastic materials are very sensitive to temperature changes. When the ambient temperature is lower than 10 ℃, the suitability of gold and silver card paper will be greatly affected. When the ambient temperature of gold and silver card paper is about 0 ℃, a large amount of water vapor will appear on its surface after it is transported from the paper warehouse to the printing workshop, Affect the normal printing, and even lead to waste products. If you encounter the above problems, and the delivery time is tight, the staff can first turn on the UV lamp to let the paper run again, so that its temperature is balanced with the ambient temperature before formal printing.

In addition, low temperature drying, low relative humidity, paper and air moisture exchange, paper drying, warping, shrinkage, will cause poor overprint.

Effect of low temperature on adhesive

Adhesive is an important chemical agent in today's industrial production. The performance of adhesive directly affects the quality of industrial products.

In the production of adhesives, an important technical index is the control of temperature. Most of the raw materials of adhesives are organic polymers, which are highly dependent on temperature, which means that their mechanical properties and viscoelasticity are affected with the change of temperature.

It should be pointed out that low temperature is the main cause of glue false adhesion.

When the temperature drops, the hardness of the adhesive becomes hard, which changes the stress effect of the adhesive. At the opposite low temperature, the movement of polymer chain in the adhesive is limited, which reduces the flexibility of the adhesive.