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In the process of soft packaging production, adhesive solvent free play a crucial role. This polyurethane resin-based adhesive is widely favored for its unique environmental friendliness and high efficiency. However, in practical applications, temperature and humidity—two environmental factors—significantly impact the performance of adhesive (solvent free). This article will explore the effects of temperature and humidity on adhesive (solvent free) for soft packaging, and how to optimize their use under different environmental conditions.
Solvent-free adhesives rely on the curing reaction between isocyanate groups and compounds or polymers containing active hydrogen. According to the Arrhenius equation and Van't Hoff's approximation rule, temperature is a key factor affecting the rate of chemical reactions. In adhesive (solvent-free), an increase in temperature will accelerate the reaction rate of isocyanate with hydroxyl or water, thus increasing the curing speed and bonding strength of the adhesive.
However, in practical applications, excessively high temperatures may cause the solvent free polyurethane adhesive to cure too quickly, resulting in uneven coating, bubbles, and other issues; while excessively low temperatures may cause incomplete curing of the adhesive, affecting bonding performance and the appearance quality of the composite film. Therefore, in the production process, it is necessary to adjust the temperature and curing time according to the actual situation to ensure that the adhesive's performance reaches its optimal state.
Humidity affects adhesive solvent free primarily in two ways: First, moisture in the air will react with the isocyanate in these laminating adhesives, consuming the isocyanate components and leading to a decrease in the adhesive's performance; second, in a high-humidity environment, materials such as films and inks tend to absorb moisture, which then affects the appearance quality and bonding performance of the composite film.
Specifically, moisture in the air will react with isocyanate to produce carbon dioxide gas, causing defects such as bubbles and white spots on the surface of the composite film. At the same time, moisture will also consume the isocyanate components in the adhesive, resulting in incomplete curing of these flexible packaging adhesives, affecting bonding performance and the heat resistance of the composite film.
To optimize the use of adhesive solvent free in the face of humidity's impact, the following measures can be taken: First, in high-humidity environments, enhance ventilation and dehumidification in the compounding workshop to reduce the moisture in the air; second, pay attention to the storage and transportation conditions of materials such as films and inks to prevent moisture absorption; lastly, appropriately adjust the adhesive's formulation and dosage, increasing the content of isocyanate components to improve the adhesive's resistance to moisture.
In summary, temperature and humidity are important factors affecting the performance of adhesive solvent free for soft packaging. In practical applications, we need to adjust temperature and humidity conditions according to the actual situation and take corresponding measures to optimize the adhesive's performance. As one of the leading industrial laminating adhesive manufacturers in the domestic high-performance polyurethane adhesive industry and the preferred brand for users, COMENS is committed to providing customers with the highest quality products and services, aiding the development of the soft packaging industry.
