Global Coatings Network News:
Global Coatings Network News:
With the expansion of the definition of food safety, the requirements for packaging of food and agricultural products in various countries continue to increase.
In the international market, many food and agricultural products are packaged in steel drums, and the hygienic requirements of their inner wall coatings have attracted wide attention from all countries.
As early as the 1950s, the US FDA required great attention to the inspection of packaging barrels for food and agricultural products.
In order to meet the needs of the international market, my country has also made specific regulations on the hygienic requirements of the inner wall coatings of the packaging barrels of exported food and agricultural products.
At present, the steel barrels with inner coating and packaging used to contain food and agricultural products in my country generally include honey barrels, juice barrels and ketchup barrels.
If the inner-coated packaging barrels used to contain these foods, the hygienic quality of the inner wall paint does not meet the requirements of safe food hygiene, which will cause secondary pollution to the food, thereby affecting the internal quality of the product.
According to regulations, the food-grade coatings allowed to be used on the inner walls of the steel drums include polyamide epoxy resin coatings, peroxyethylene coatings and organic fluorine coatings.
(Polyamide epoxy resin coating)
Polyamide epoxy resin coatings belong to epoxy resin coatings, and epoxy resin coatings belong to curing film-forming coatings.
Epoxy resin is generally polymerized by bisphenol A (diphenol-based propane) and epichlorohydrin.
Depending on the degree of polymerization, the molecular weight of epoxy resin is also different.
From a hygienic point of view, the larger the molecular weight (that is, the smaller the epoxy value), the more stable it is, and the less likely it is for harmful substances to dissolve and migrate into food, so its safety is higher.
As the curing agent of polyamide epoxy resin coating, polyamide itself is a kind of high molecular compound, and there is no report of its toxicity.
The quality of polyamide epoxy resin (epoxy value of epoxy resin) is closely related to the ratio of curing agent and the degree of curing.
The proportion of curing agent is appropriate and the higher the degree of curing, the less uncured substances in the epoxy resin coating will migrate to the food.
According to the provisions of GB9686-88 "Hygienic Standard for Polyamide Epoxy Coatings for Inner Walls of Food Containers", the evaporation residue of polyamide epoxy resin coatings in various solvents should be controlled below 30 mg/L.
Perchloroethylene paint uses perchloroethylene resin as raw material and is matched with plasticizer.
After painting or spraying the inner wall of the packaging barrel, it will naturally dry to form a film.
Perchloroethylene coatings are generally divided into primers and topcoats.
Perchlorovinyl resin contains vinyl chloride monomer, which is a carcinogenic toxic compound.
The perchloroethylene paint after film formation may still contain vinyl chloride residues.
According to GB7105-86 "Sanitary Standard for Perchlorovinyl Inner Wall Coatings for Food Containers", the vinyl chloride monomer residues in the perchloroethylene paint after film formation should be controlled within Below 1 mg/kg.
Plasticizers, solvents and other additives used in perchloroethylene coatings must comply with the relevant provisions of GB9685-94 "Sanitary Standards for the Use of Additives for Food Containers and Packaging Drums", and no toxic or highly toxic additives should be used.
The coating film is required to be uniform and free of bubbles, spots, wrinkles and shedding.
Organic fluorine coatings include polyfluoroethylene, polytetrafluoroethylene and polyhexafluoropropylene coatings .
These coatings are polymerized with vinyl fluoride, tetrafluoroethylene and hexafluoropropylene as the main raw materials, with certain additives, and sprayed on the packaging barrel The inner wall surface.
Organic fluorine coating has the characteristics of anti-sticking and corrosion resistance, but its acid resistance is poor, so it is widely used on steel barrels of inner coating packaging barrels containing honey.
In terms of application, the organic fluorine coating on the steel barrel of the honey-coated packaging barrel is polytetrafluoroethylene, or PVF coating for short.
It is a high molecular compound with stable chemical properties and no monomer residues under normal circumstances.
It is a relatively safe coating for the inner wall of food packaging barrels.
However, when cleaning the inner wall of the steel drum of the packaging barrel, most of the packaging barrel manufacturers currently use spray cleaning and drying lines for cleaning.
The cleaning agent is usually chromate, which may cause the chromium salt to remain on the surface of the container and then be mixed into the inner coating.
Therefore, when the steel barrels coated with honey inside are produced, the steel barrels coated with honey inside should be inspected in accordance with GB1167-89 "Sanitary Standards for Polytetrafluoroethylene Paint on the Inner Wall of Food Containers".
The standard stipulates that the appropriate amounts of chromium and fluorine should be controlled between 0.
01 mg/L and 0.
2 mg/L, respectively.
In addition, when PTFE is baked, if the temperature reaches 280℃, it will fission and produce highly volatile and toxic fluoride.
Therefore, when using PTFE-coated honey-coated steel barrels, generally The baking temperature should not exceed 250°C.
In recent years, the fruit juice, ketchup and honey exported by our country have often been returned abroad due to excessive pesticide content.
As a food packaging barrel, the residual amount of solvent for the inner wall coating should be as low as possible.
Therefore, when producing food inner coating packaging barrels, we must follow the food safety and hygiene requirements to ensure that the food packaging barrels are clean and the residual harmful content does not exceed the hygienic standard requirements.
To this end, an interlocking supervision system should be formed.
Enterprises using food packaging barrels should obtain food safety and sanitation inspection reports for the packaging barrels from the packaging barrel manufacturer; packaging barrel manufacturers should request the coating supplier for the food safety of inner wall coatings.
Hygiene inspection report.
At the same time, relevant departments should also conduct regular supervision and inspection of food packaging barrels and issue inspection reports.
(Source: Global Coatings Network) (For more information, please log in: Global Coatings Network http:// )