Biodegradable Bubble mailing bag wholesaler.What should be done if the composite packaging bag has an odor that affects the product?

The odor in packaging bags not only affects the contents of the packaging, but also to a certain extent harms the health of customers, which is an issue that cannot be ignored in product safety. How to reduce the odor of composite packaging bags has become a basic requirement in the packaging bag industry. Below, professional flexible packaging manufacturers will combine their rich experience in producing composite packaging bags to interpret the reasons and solutions for the odor generated in packaging bags.

1、 Source of odor

The odor in the film mainly comes from two parts: the resin itself, various additives, and its own low molecular weight substances; The odor that occurs during the processing of soft packaging.

Thin films, various inks, adhesives, and organic solvents can all bring various odors. The odor generated by packaging materials is diverse and complex, including sweet, sour, sulfur, medicinal, burnt, paraffin, petroleum, ink, soap, tar, solvent, etc. Odor is not only caused by one substance, but also by a mixture of several substances. It is particularly difficult to describe odors, as small changes in the composition of the mixture can lead to differences in odor.

2、 Source analysis

1. The influence of resin itself

Thin films are generally processed with polymer resins, which are composed of molecules of varying sizes and have different molecular weight distributions and low molecular content. Low molecular weight substances are prone to oxidation and volatilization during extrusion processing, producing odors.

The resin synthesis process is divided into solution method and meteorological method. The two different composition methods also have differences in odor. The solution method, due to the process of removing many low molecular substances after composition, theoretically has a better taste than meteorological method.

Many additives need to be added to the resin to improve its performance, and these additives are the biggest source of flavor. Smoothing agents are generally acylamide compounds with a slightly sweet taste. The taste of antistatic agents is very pungent and cannot be used in low odor packaging. The opening agent is generally composed of inorganic substances, usually calcium carbonate and silicon dioxide. However, in terms of opening effect, silica is much better than calcium carbonate, but in terms of taste, calcium carbonate is better than silica. Antioxidants are usually phenolic substances and also have a certain taste. Due to the problem of catalyst residue in linear molecules, it is necessary to add antioxidants.

Color masterbatch: Commonly used white masterbatch usually adds some wax and stearate as dispersants and lubricants. These low molecular weight substances will be separated during processing and have a strong taste, so they should be placed in the middle layer as much as possible in multi-layer co extrusion.

2. Odor during the production process of composite packaging bags

1. Thermal decomposition produces

The components of substances that produce odors during the decomposition of polyethylene can be roughly divided into two categories: aliphatic hydrocarbons and aromatic hydrocarbons. According to research, saturated or unsaturated hydrocarbons that decompose into three to twenty-eight carbons during thermal decomposition, among which the three to six carbon compounds produced by short branched chains have the greatest impact on the content. Due to their low volatility and low polarity, these substances can be stored for a long time in the membrane.

2. Thermal oxidation produces odor

When plastic is processed at high temperatures and high shear forces, in addition to thermal decomposition, after being extruded from the mold mouth, it also produces a thermal oxidation reaction with oxygen in the air, and the resulting substances can also cause odors.

Surface corona treatment produces odors. In order to make the ink or adhesive have good adhesion, different plastic films need to be corona or flame treated. Due to the oxidation reaction, the surface tension of the offset plate becomes stronger, and a group of substances (hydroxyl, aldehyde, ketone, and carboxyl) generated during the processing will be encountered in the subsequent application of the coating. Assuming that the intensity of treatment increases, not only will it increase surface tension, but it will also increase the degree of polymer degradation, resulting in the production of small molecules (aldehydes and ketones) that are prone to transpiration; These easily transpiration aldehydes and ketones can produce unpleasant odors.

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