Due to the chemical nature of polyurethane adhesives, solvents containing water, alcohols, amines, esters, etc., that contain active hydrogen or reactive groups are not allowed to be used in the formulation of glues, but only high purity esters, ketones, hydrocarbons (alkanes or Inert solvents, such as aromatic hydrocarbons, also need to consider the product's hygiene and safety and avoid odors and odors.
Toxic aromatic hydrocarbons such as toluene and xylene should be used as little as possible. Methyl ethyl ketone (ie, ketones) with heavy odors should also be used sparingly. It is best not to use these problematic solvents. In the case of having to use, it is necessary to work hard on drying, to ensure that they are as volatile as possible, and the amount of residue is as small as possible.
The economically developed countries are very sensitive to the hygienic properties, odors, and odors of packaging materials, and those who have slight problems cannot pass. So if you are using for packaging of export products, you must pay special attention!
When exporting products, the content of aromatic hydrocarbon in the residual solvent of the packaging material itself is often too high. After the food is loaded into the food, it migrates to the food through the inner layer material and is absorbed by the food, resulting in odor or toxicity of the food. Accepted and returned.
Sometimes there is such a problem: the composite bag smells no smell at room temperature, but when the bag is still hot food (such as freshly baked cookies from a processing line), it is cooled. When the food was tasted, unpleasant odor appeared. This was because the migration of residual solvents was promoted when the temperature was high.
This odor problem is often caused not only by the adhesives and the solvents used, because many plants only use ethyl acetate ethyl esters, but toluene remains on the packaging bags. Odor odor of butanol or xylene, which is the reason for printing inks. Today's composite printing inks mostly use "composite inks," which are so-called "printing inks."
Solvents are used in this type of ink. In addition to the ethyl ester ethyl ester, there are odor-toxic and high-boiling solvents such as butanone, xylene and butanol.
Because the pigment particles in the ink are small, the specific surface area is large, and the adsorption ability is very strong. Although it has been heated and dried during printing, due to short time and high speed, the drying is often incomplete, and the residual solvent is too much, especially in a large area. This is especially true for multiple sets of printing. These residual solvents are brought into the compounding process and are harder to run off after compounding. They have to slowly migrate and infiltrate, so the above problems will occur.
Taixing Chaobang Adhesive Co., Ltd.
