As an environmentally friendly packaging material, biodegradable self-adhesive bag is increasingly used in various fields. Its viscosity is one of the important factors affecting the use effect, and the two environmental factors of temperature and humidity have an important influence on its viscosity. Understanding this influence is crucial for the correct use and storage of biodegradable self-adhesive bags.
The effect of temperature on the viscosity of biodegradable self-adhesive bags mainly comes from its change in the properties of glue. Generally speaking, the glue used in biodegradable self-adhesive bags is mostly water-based glue or hot melt glue. When the temperature rises, the movement of glue molecules intensifies, the distance between molecules increases, and the viscosity of the glue decreases. This is because higher temperatures make the glue thinner and more fluid, resulting in a weakened adhesion to the surface of the adherend. On the contrary, when the temperature decreases, the movement of glue molecules slows down, the distance between molecules decreases, and the glue becomes thicker and more viscous. But if the temperature is too low, the glue may become too hard and lose its elasticity, thereby affecting its ability to wet and adhere to the surface of the object, resulting in a decrease in viscosity.
In a high temperature environment, the viscosity of the biodegradable self-adhesive bag will be significantly reduced. For example, when the ambient temperature exceeds 35℃, the glue of the self-adhesive bag may become too thin, making the seal of the bag easy to open automatically, or easy to be easily uncovered after pasting, and it cannot play a good sealing and fixing role. Moreover, high temperature may also accelerate the aging process of the glue, causing the performance of the glue to gradually decline. Even after the temperature returns to normal, the viscosity is difficult to fully recover to the original level. When in a high temperature environment for a long time, the viscosity of the self-adhesive bag will continue to weaken, and the glue may even seep out, contaminating the packaged items.
The effect of low temperature on the viscosity of the biodegradable self-adhesive bag cannot be ignored. When the temperature is below 5℃, the viscosity of the glue will increase, but the flexibility of the glue will decrease at this time and become more brittle. In this case, the self-adhesive bag may not fit the surface of the object well when pasting, and bubbles or wrinkles are prone to appear. Moreover, if a certain external force is applied to the self-adhesive bag after pasting, due to the lack of elasticity of the glue, it is easy to cause the glue layer to break, causing the self-adhesive bag to separate from the adherend and the viscosity to fail. In addition, the low temperature environment may also harden the material of the self-adhesive bag, affecting its overall flexibility and operability, and indirectly affecting the viscosity.
The effect of humidity on the viscosity of the biodegradable self-adhesive bag is mainly achieved by affecting the interaction between the glue and the surface of the adherend. In a high humidity environment, the moisture in the air will form a thin layer of water film on the surface of the self-adhesive bag and the adherend. This layer of water film will hinder the direct contact between the glue and the surface of the adherend, thereby reducing the viscosity of the glue. At the same time, moisture may also dilute the glue, reduce the concentration of the active ingredients of the glue, and further weaken the viscosity. In addition, for some highly hydrophilic glues, excessive moisture will cause them to undergo a hydrolysis reaction, destroy the chemical structure of the glue, and cause a decrease in viscosity.
In a high humidity environment, such as when the relative humidity exceeds 70%, the viscosity of the biodegradable self-adhesive bag will be significantly reduced. After being pasted, the self-adhesive bag is prone to loose adhesion and will fall off with a slight tear. When it is peeled off, there is often no obvious glue mark left. This is because the viscosity of the glue has been greatly weakened by the water. In addition, high humidity may also cause water droplets or water mist to appear on the surface of the self-adhesive bag, making the surface of the bag moist, which not only affects the appearance, but also further affects the viscosity. In a high humidity environment for a long time, the glue of the self-adhesive bag may also mold and deteriorate, seriously affecting its viscosity and performance.
The viscosity of the biodegradable self-adhesive bag is greatly affected by temperature and humidity. In actual use and storage, it should be placed in an environment with suitable temperature (generally 15℃ - 25℃) and moderate humidity (relative humidity 40% - 60%) as much as possible to ensure that its viscosity can be maintained in good condition, play the best use effect, and extend its service life.
