The solvent used in the preparation of the hottest

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Solvents used for adhesive preparation due to the chemical characteristics of polyurethane adhesive, it is not allowed to use solvents containing active hydrogen or reactive groups such as water, alcohol, amine and ester, but only inert solvents such as esters, ketones and hydrocarbons (alkanes or aromatics) with high purity. The health and safety of the product and the avoidance of odor and odor should also be considered

toxic aromatic hydrocarbons such as toluene and xylene should be used as little as possible, and methyl ethyl ketone (i.e. lower ketone) with heavy odor should also be used less. These problematic solvents should not be used. When it has to be used, it is necessary to work hard on drying to ensure that they volatilize as clean as possible and the residue is as small as possible

economically developed countries are very sensitive to the hygienic performance, peculiar smell and odor of packaging materials, and those with slight problems cannot pass the test. Therefore, if it is used for the packaging of export products; Pay special attention

in recent years, when exporting products, the content of aromatic hydrocarbon in the residual solvent of packaging materials is too high. After being loaded into food, it will migrate to food through the inner material and be adsorbed by food, resulting in peculiar smell or toxicity of food, which can not be accepted abroad and will be returned

sometimes the frequency and phase of this force must be basically close to that of the fatigue testing machine system, which has passed the acceptance of the expert group a few days ago. The resonance frequency and phase will also encounter such a problem: the composite packaging bag can not smell any peculiar smell at room temperature, but when the packaging bag still contains food with heat (such as baked biscuits just made from the processing line), when the food is tasted after cooling, there will be an unpleasant peculiar smell, This is because high temperature promotes the migration of residual solvents, for example

this peculiar smell problem is often caused not only by the adhesive and the solvent used, because many factories only use ethyl ester solvent, but toluene remains on the packaging bag. The odor of butanol or xylene is the original reason for printing ink

most of the current composite printing inks use composite ink, which is the so-called inner printing ink. In addition to ethyl ester, solvents used in this ink include butanone, xylene, butanol and other solvents with high boiling point, odor and toxicity

because the pigment particles in the ink are very small, the specific surface area is very large, and the adsorption capacity is very strong. Although they have been heated and dried during printing, due to the short time and fast speed, they are often not completely dried, and there are too many residual solvents, especially in large-area and multiple sets of printing. These residual solvents are brought to the compounding process. After compounding, they are more difficult to run away, so they have to migrate and penetrate slowly. Therefore, the above problems will occur

there are two ways to solve this problem:

(1) strictly determine the drying process to minimize the amount of residual solvent. For example, western countries require that the residual solvent be less than 5mg/m2. Because the quantity is too small to be aware of, but this is not the fundamental solution to the problem

(2) to fundamentally solve the problem, it is necessary to use high boiling point inks, solvents and adhesives that do not contain the above toxic, odorous and smelly, but only ethyl esters, alcohol and acetone with low boiling points. Isopropanol and other non-toxic, low toxic, odor free solvents. The two-component high-performance, versatile polyurethane ink does not need to use aromatic solvents, and the alcohol soluble oil has no disadvantages. If there is no problem with the ink and the amount of residual solvent is small, there is no need to worry

another problem with solvents is that they should not be misused. In order to save costs, some units used industrial grade banana water to dilute the adhesive. As a result, the adhesive liquid became layered, soon became turbid and white, and could not be used. Instead of saving money, they wasted more

because the factory that makes composite packaging materials prints, compounds and makes bags by itself, there are ethyl acetate, toluene, xylene, alcohol, isointernal alcohol, butanone, etc. in the warehouse. If the management is poor, the wrong solvent or the wrong material is received, and the use is improper, there will also be problems, which need special attention. It is better to store the ethyl ester in a separate warehouse. Do not mix it with other solvents. Strengthen management and improve identification ability

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