Influence of temperature and humidity on Printing:
1. Influence on printing effect: in the case of high temperature and high humidity in summer, when plastic gravure printing is carried out, due to the evaporation of solvent, the water vapor in the surrounding air condenses, which makes the surface of printing ink film form mist. Due to the short printing oven and fast printing speed, the ink layer loses luster and the overall printing effect fogs.
2. Influence overprint: mainly affect paper and NY film, paper is composed of plant fiber, plant fiber has porous and hydrophilic, very sensitive to water. Environmental temperature and humidity slightly change, the paper moisture content will change. The influence of air relative humidity on paper moisture content is generally the increase of relative humidity and the increase of paper moisture content. The change of paper moisture content will cause paper expansion (including local deformation). When printing multi-color overprint products, the moisture content of the paper decreases and the transverse size shrinks when it passes through an oven unit. When the shrinkage is large, the overprinter will be inaccurate. However, if the excessive moisture content is too low, the paper becomes brittle and hard, easy to tear, and static electricity and broken material are easy to occur during printing. Especially in the north, the humidity changes greatly in winter and summer, and this effect is more obvious. Therefore, paper printing needs to control the moisture content of paper.
BOPA film is made of polyamide 6 (nylon 6). Polyamide contains polar amide (- CO-NH -). The amide group in polyamide molecular chain can coordinate with water molecule, so nylon membrane has strong water absorption. And nylon water absorption, size will change, never affect overprint.
3. Printing knife line, floating dirty and other problems: too much humidity, poor ink dispersion, increased affinity between ink and plate roller, printing plate is not easy to clean; but humidity is too small, because electrostatic adsorption dust, both will cause knife line.
4. Anti sticking phenomenon: "back sticking" (back sticking, back sticking) refers to the phenomenon that the printing layer adheres to the back of the film or the printing layer adheres to each other in the process of compounding or bag making after the plastic film is printed and rolled up. "Anti sticking" phenomenon is easy to happen in high temperature, especially in the environment of high humidity. Due to high temperature in summer and high viscosity of ink, it is easy to cause high residual solvent or "false dry" phenomenon. In addition, too much humidity increases the force of ink and non printing surface to a certain extent.

Therefore, the control of temperature and humidity is very important for the printing process. In order to ensure good printing effect, the temperature should be controlled at 20-25 ℃ at room temperature, and the humidity should be controlled at about 40%. All of these are helpful to the true reproduction of color and reduce the appearance of quality defects. Some enterprises with large scale and standardized management will control the environment of printing workshop. Central air conditioning is used to control the temperature and humidity of the environment in summer and humidifier is used in winter.

However, limited by the workshop conditions, some manufacturers have limited ability to adjust the temperature and humidity. At this time, we need to adjust our own process in time to reduce the occurrence of quality problems.
Influence of temperature and humidity on recombination
The influence of environmental temperature and humidity on lamination is mainly in the adhesive. In the high temperature and high humidity environment, condensation will occur at the anilox roller and rubber roller, which will increase the adhesive tension and affect the leveling of the glue; in the high temperature environment, the reaction speed of the glue will be accelerated, and the reaction speed of the water with the curing agent will be faster, which will lead to the rapid rise of the viscosity of the glue and lead to the glue Adhesive turbidity white, greatly affect the coating effect, resulting in spots, bubbles and other phenomena. In addition, the moisture will consume the curing agent in the adhesive, which will cause incomplete curing and affect the peel strength and temperature resistance of the adhesive
What are the measures to deal with the composite process in high temperature and high humidity weather?
1. In high temperature and high humidity season, it is better to use it in two hours. At the same time, according to the curing condition of the product, the curing dose should be increased appropriately (about 5-10%).
2. For the materials that are easy to absorb moisture and oxidize, such as NY, EVOH, Al, etc., wrap the film with aluminum foil or aluminum plating composite film and put it in wooden frame or other dry environment.
3. Because the influence of water in the environment is relatively difficult to control, the amount of water and alcohol in ethyl acetate is strictly controlled.
4. Check whether there are water drops on the guide roller and composite roller, and wipe them with dry towel.
5. The coating unit should be properly isolated and protected to reduce the air circulation, and the ethyl ester volatilization in the glue tank should be reduced. In addition, the rubber barrel must be covered.
6. The glue tank is heated to provide the heat needed for ethyl ester volatilization, and the condensation of water vapor is reduced due to the increase of temperature of rubber tank and roller.
Influence on the properties of materials and finished products
1. Impact on COF
Many manufacturers may have encountered the phenomenon that the film is too astringent in summer and not smooth in winter. Therefore, the influence of temperature and humidity on film COF is very worthy of attention. When necessary, the winter and summer formula can be negotiated with the supplier.
COF refers to the friction coefficient. The smoothness of the film is mainly achieved by adding a smooth agent. After the film is formed, the smooth agent migrates from the inside of the film to the surface and accumulates into a uniform thin layer, which can significantly reduce the friction coefficient of the film and make the film have a good smooth effect. Most of these additives are inorganic polymer materials (such as amines or waxes), which have poor compatibility with the resin. Usually, starting from 30 ℃, the commonly used lubricants are close to their melting point and become bonded. The friction coefficient of the film will rise sharply. The force applied during the test will fluctuate greatly, showing an intermittent sliding or bonding effect. If the content of the lubricant is too high, it will affect the printability of the film, which is very unfavorable for printing. Generally speaking, with the increase of the ambient temperature, the friction coefficient of the material surface will change to a certain extent, but the magnitude of the change depends on the sensitivity of the material to temperature and the type and amount of additives added.
2. Preservation of NY bags: single layer PE bags are used after bag making to prevent curling and warping.
In addition, it also has a great influence on the extrusion composite strength, hoping to attract attention.
Production and processing of composite flexible packaging is an industry with great environmental impact. The temperature, humidity, dust size and quantity sometimes have a great impact on the quality of our products
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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