‍The non drying of solvent-free composite glue is often caused by incorrect mixing ratio, uneven mixing of glue, and deterioration of isocyanate components in the glue. How to solve this problem? This article analyzes separately.
1. The glue mixing ratio is incorrect
Customers equipped with glue machines should pay special attention to regular and timely maintenance and cleaning of the glue machines, especially the sealing of the glue machines, otherwise the isocyanate components are prone to react with water vapor and deteriorate. If the proportion of the two components produced by the glue machine is incorrect, it will cause the glue to not solidify and become sticky.
The core of the glue machine is the glue pump. Whether it is a plunger pump or a gear pump, there is usually an automatic alarm system for the imbalance of the glue liquid ratio. Generally speaking, new rubber pumps will not have any problems during initial use, but with the extension of service life, if the relevant maintenance and upkeep measures cannot keep up. Once there is a problem with the glue pump and the adhesive ratio is out of balance without alarm, there will be a batch of quality accidents.
Generally speaking, as long as the proportion is determined, the refractive index of the newly mixed adhesive at a certain temperature is constant. Although in practical operation, there may be some changes in the refractive index due to the influence of temperature and testing time, there are rules to follow. The detection of refractive index can be carried out at any time without affecting online production, making the operation very convenient. Enterprises can determine whether the mixing ratio is accurate by measuring the refractive index.
2. Uneven mixing of glue
The glue should be stirred thoroughly, and stirring until the glue is clear indicates that it has been evenly mixed, especially when manually stirred.
3. Deterioration of isocyanate components in adhesive
The isocyanate component in the adhesive is prone to react with moisture in the air, causing the adhesive to fail, so this requires special attention during storage and use.
Sometimes aluminum plated material composites exhibit stickiness, while transparent material composites do not have similar problems. This is mainly because aluminum plated materials have better hydrophilicity than transparent materials, and the water on the aluminum plated film reacts with the adhesive.
The solution can be achieved by increasing the amount of isocyanate components, or by applying glue to aluminum plated materials, which can also be improved to a certain extent. At the same time, special attention should be paid to the storage and protection of aluminum plated materials, and packaging should not be opened before compounding.