1. Introduction of composite film bags for food
In order to adapt to different food preservation and storage requirements, food packaging bags are continuously updated, from the past single-layer packaging film to a variety of multi-layer composite packaging film.
The composite film bag organically combines different materials. For example, the outer layer uses paper materials to facilitate printing; the middle layer uses aluminum foil to avoid light; the inner layer uses non-toxic, water-resistant and oil-resistant polyethylene to directly contact food. Combine the advantages of various materials to obtain better performance packaging film bags.
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Second, the composite film bag food residue standard solvent
Food composite film bags may have solvent residues due to printed inks and adhesives, and may migrate into foods during use, with certain safety risks.
In July 2006, AQSIQ issued a "food packaging, containers, tools and other products production license General" food made mandatory by the kind of residual solvent in the composite packaging film and its limits, categories include benzene-based solvents :
Benzene, toluene, p-xylene, o-xylene, m-xylene;
Other solvents: ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, butyl acetate.
According to GB / T10004-2008 "Plastic composite film for packaging, dry compounding of bags, extrusion compounding", the total amount of solvent residue in the composite film bag for food should be ≤ 5mg / m2 , and benzene solvents should not be detected 0.01 mg / m2 ).
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3. The detection method of solvent residue
The residual solvent is detected by a hydrogen ion detection gas chromatograph, and the standard curve method is used for quantitative analysis.
According to GB / T10004-2008 , first cut 0.2m2 of the sample to be tested, and quickly cut the sample into 10mm × 30mm pieces, put it into a clean bottle preheated at 80 ℃, and quickly seal.
Put it into ( 80 ± 2 ) ℃ dry box for 30 minutes. Take a certain amount of gas from the bottle and quickly inject it into the chromatograph for measurement.
Find the corresponding amount on the standard curve according to the peak area of ​​the sample.
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4. Precautions for solvent residue detection
1. Sampling should be uniform, while avoiding the location with ink or adhesive, and only cut the part of the composite film bag that contacts the food;
2. Because the solvent is easily volatilized, the action needs to be rapid when configuring the standard curve to minimize the opening time of the standard substance in the bottle;
3. Both the standard substance and the sample bottle must be tightly sealed to avoid errors caused by diffusion during heating.
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