Editor's Note: With the rapid development of the world economy, packaging printing presents a splendid scene, and more and more beautiful packaging is produced in printing plants. People appreciate the beauty of these “clothes†while enjoying the beautiful outerwear, especially for food packaging. This is a very important issue - the safety of food packaging prints.
The carton packs made of eco-friendly paper or cardboard, such as cigarettes, snack foods, and children's nutritional breakfasts, are processed by various printing methods, and the ink adheres to the paper, indicating whether or not there is any adverse effect on the contents of the package, or whether Will there be harmful substances transferred to the food, ie are there any unsafe factors? Especially for gravure printing inks, which are commonly used in cigarette printing, how does the safety of this type of ink printing product test and test?
We know that printed packaging materials have different degrees of odor, depending on the printing method used or the composition of the ink. How to evaluate these odors? The first thing that should be explained here is that what we emphasize is not what the smell it is emitting is, but the effect of the packaging material formed after printing on the content of the package. We hope that packaging will have as little impact on the smell and taste of its contents as possible.
As we all know, taste and smell are chemical sensations, and their stimulatory effects are the result of biomolecular reactions. Scientists have shown that different parts of our tongues produce acid, sweet, bitter and salty taste effects, and our sense of smell is more sensitive, we can quickly smell the nuances of nuances, but at the same time, the nose is also prone to fatigue. "It does not work, so it is generally recommended that perfume manufacturers do not continuously identify more than three kinds of taste." Then, what is the testing standard for the odor of packaging prints? This article briefly introduces several testing methods used by the German printing industry for reference.
1. Gas Chromatography Analysis Gas chromatography analysis is widely used in the production of gravure printing packaging materials. The content of residual solvents and other odors on the printed package can be objectively determined by gas chromatography analysis. During GC analysis, the gas passes through a separation column and is measured by the detector. Even a small amount of gas can be detected. Flame ionization detector (FID) is its main detection tool. Connect the detector to a PC to record the time and the amount of gas leaving the separation column. Each free monomer condition can be identified by comparison with known fluid chromatography. At the same time, each free monomer content can be obtained by measuring the area of ​​the recorded peak and comparing it with a known volume. In the case of an investigation of the unknown monomer in the folding carton, gas chromatography is usually used together with mass spectrometry (MS) to identify unknown monomers by mass spectrometry.
In gas chromatography, headspace analysis methods are commonly used to analyze folding cartons. The sample to be tested is placed in a sample vial for heating to vaporize the analyzed monomer and enter the headspace. The subsequent process is the same as the previously described test procedure.
2. The Robinson test defines the Robinson test in the German standard DIN 10955 "Influence of packaging materials on the taste of test materials". For printing, we are concerned about the effect of solvent residues after ink printing. Therefore, printing houses usually use the modified Robinson test method (MHM) to achieve the purpose of testing.
In the inspection process, the surface of the substrate is printed with an amount of ink of 1.5 g/m 2 , and then the printed matter and packaged product, for example, after being put on chocolate for a certain period of time (approximately one day), is evaluated for the taste of the package. The result is usually divided into For 5, etc.: 0 = no change in taste; 1 = difficult to discern changes in taste; 2 = slight changes in taste; 3 = changes in taste; 4 = marked changes in taste.
Occasionally, some people also perform tests under actual environmental conditions. For example, the carton is tested under high humidity conditions at 75% RH, and the results are generally quite different from those specified in DIN 10955.
The above two methods are used to quantitatively detect the effect of the ink on the odor and taste of the package after the printing of the printed matter through an experimental method, thereby providing a clear method for evaluating whether the carton package printing is environmentally friendly and safe. China's printing factories and corresponding departments can refer to foreign advanced detection methods and international standards to formulate detection methods and standards that are in line with international standards and in line with China's production conditions, so as to promote the development of printing.