"Invisible Shield" for Secret Cans: Food Grade Inner Coating

When people come home from the baking outdoors on a hot summer day, they are accustomed to taking out a can of drink from the refrigerator and downing it - so you have unconsciously completed the interaction with the paint. Have you ever thought that this small can, why can play a key role in ensuring the safety and quality of food and beverage, the "secret" is hidden in the can of beverage you drink. The seemingly insignificant inner coating, in fact, shoulders the important task of protecting product quality and consumer health, is a crucial part of aluminum can packaging. Next, let's explore the mystery of aluminum can food grade coating.

The main function of food grade inner coating

(1) Corrosion protection ‌

Food-grade inner coating is like putting on a layer of strong "protective clothing" for aluminum cans, effectively preventing the material in the can from coming into direct contact with the metal can.

Many foods and beverages, especially acidic beverages, such as common carbonated beverages, in this acidic environment, metal tanks are prone to chemical reactions, thus being corroded.

With food grade inner coating, it can form a reliable barrier between acidic drinks and metal aluminum cans, effectively avoid metal corrosion, greatly extend the service life of aluminum cans, to ensure that the product in the shelf life always maintain a good packaging state.

(2) Ensuring food safety

Food safety is the lifeblood of the food and beverage industry, and food grade coating plays a crucial role in it. It effectively blocks the migration of metal ions from the tank to food and beverage, where long-term ingestion of metal contamination may cause health risks (such as nervous system damage).

Therefore, the standard food grade inner coating is very important to ensure food safety. It can ensure that food and beverage meet strict food safety standards in the whole supply chain process, so that consumers can eat at ease.

(3) Maintain product flavor ‌

Metal itself has a certain chemical activity, even trace metal and food and beverage contact, may also trigger some chemical reactions, thus changing the flavor and taste of food and beverage.

For fruit juice, coffee and other products with high flavor requirements, the role of food grade inner coating is indispensable. The high-quality inner coating can completely isolate the contact between the metal and the product, ensure that the flavor and taste of the product are not interfered by external factors, so that every drink tasted by consumers is as original as when it is just produced, fresh and refreshing.

The performance requirements of aluminum can inner coating

(A) Excellent adhesion

The adhesion between the inner coating and the metal surface is the basis to ensure the packaging quality of aluminum cans. In the production process of aluminum cans, it needs to go through a series of complex processing procedures such as drawing, stamping and beaming. In order to ensure that the inner coating has excellent adhesion, we will fully consider the chemical bond between the material and the metal, intermolecular forces and other factors when selecting the inner coating material. At the same time, in the production process, the metal surface will also be pretreated, such as cleaning, degreasing, passivation, etc., to improve the roughness and activity of the metal surface, enhance the adhesion between the inner coating and the metal.

(2) Good flexibility

We use food grade inner coating materials, through special formulation design and process treatment, with excellent flexibility. These materials can effectively absorb and disperse stress during the processing of aluminum cans, ensuring that the inner coating can remain intact under various complex deformation conditions, providing reliable protection for cans.

(3) Excellent chemical stability

Different food and beverage have different chemical properties, aluminum can inner coating needs to have excellent chemical stability, for acidic drinks, such as carbonated drinks, carbolic acid in carbonated drinks, fruit acid in fruit juice, etc., have strong acidity, long-term contact with the inner coating may lead to degradation or dissolution of the inner coating, thus affecting the quality and safety of products. Therefore, the inner coating needs to be able to resist the corrosion of acidic substances.

For food and beverages containing oil, such as milk, coffee drinks, etc., the inner coating needs to have good oil resistance, grease may penetrate into the inner coating, change the physical properties of the inner coating, and reduce its anti-corrosion and barrier properties. In addition, some food and beverage may also contain preservatives, pigments, spices and other additives, these chemicals may also have different degrees of impact on the inner coating.

Our food grade inner coatings undergo rigorous testing and screening to effectively resist the attack of common chemicals, ensuring stable performance in different product environments and providing lasting protection for can packaging.

Common beverage aluminum can inner coating materials

The choice of different inner coating materials depends on the nature of the can content (e.g. acidity, sugar), production process (whether high temperature sterilization is required) and environmental requirements (e.g. water-based coating is more environmentally friendly). Aluminum two-piece cans are mostly made of epoxy resin.

1.‌ Epoxy resin based coating ‌: it has good comprehensive performance, good processing performance, can be in the production process of cans, smoothly through a variety of complex processing procedures with epoxy resin as the main component, water-based environmental protection, non-toxic tasteless, strong acid resistance, can block the beverage and metal direct contact ‌, It is mainly used for protecting the inner wall of aluminum two-piece cans of acidic drinks such as beer and carbonated drinks.

2.‌ Acrylic Modified Epoxy coating ‌: Combining acrylic resin and epoxy resin graft polymerization to improve adhesion and corrosion resistance, suitable for type D /I beer cans and soft drink cans ‌

With the continuous progress of science and technology and people's increasing requirements for food safety and environmental protection, some new or special inner coating materials are also emerging. For example, water-based modified epoxy resin coating, which uses water as solvent, has the characteristics of environmental protection and low toxicity, which is in line with the current development trend of green environmental protection. This KIND OF coating in direct contact with beer, carbonated drinks, tea drinks, coffee and energy and sports drinks of all aluminum two-piece can wall corrosion excellent performance, gradually attracted the attention and favor of the market.

There are also some inner coating materials with special functions, such as the inner coating materials with antibacterial properties, which can inhibit the growth and reproduction of microorganisms in the tank and further extend the shelf life of food and beverage; The inner coating material with high barrier performance can better block the influence of oxygen, moisture and other external factors on food and beverage, and maintain the freshness and quality of products. Although the application scope of these new inner coating materials is relatively narrow at present, they represent the development direction of inner coating materials for cans in the future, and are expected to be more widely used in the future with the continuous maturity of technology and cost reduction.

Industry standards and regulations for inner coating aluminum cans

(1) Domestic standards

In China, in order to ensure the quality and safety of food grade inner coating of aluminum cans, a series of strict national standards and regulations emerge at the historic moment.

Among them, GB 4806.10-2016 "National Standard for Food Safety Food Contact Coatings and coatings" is an important basic standard, which makes clear provisions on the basic requirements, technical requirements, inspection methods and other aspects of food contact coatings and coatings, covering all kinds of food contact coatings including aluminum can inner coating. Common norms and guidelines are provided for the whole industry.

GB 11677-2012 "National Standard for food safety, water based modified epoxy resin coating on the inner wall of cans" has formulated special standards for the water based modified epoxy resin coating used on the inner wall of cans. The standard specifies the scope of application and technical requirements of such coatings in detail. In terms of technical requirements, strict standards have been set for the color and luster of the coating, appearance, performance of the coating and related indicators of the coating soaking liquid, to ensure that the water-based modified epoxy resin coating can meet the requirements of food safety and corrosion prevention when applied to the inner wall of aluminum cans.

(2) International standards

Internationally, the European Union's food contact material regulation system and the relevant provisions of the United States Food and Drug Administration (FDA) have a wide influence in the field of food grade coating of cans. The EU regulation on food contact materials has strict and detailed provisions on the safety and migration limit of food contact materials, covering a variety of materials that may come into contact with food, including the coating materials inside cans. It clearly defines the migration limits of different types of chemicals in food contact materials.

When our country formulates the standard of food grade inner coating of cans, we actively learn from the international advanced standards and experience, and strive to be in line with international standards. In some key indexes and technical requirements, our country standard has reached or is close to the international advanced level.

Conclusion

As the core element of aluminum can packaging, food-grade inner coating plays an irreplaceable key role in corrosion prevention, food safety and product flavor maintenance. It is not only an important guarantee for the quality of cans, but also a trust bridge connecting consumers and food and beverage enterprises.

With the increasing requirements of consumers for food safety and environmental protection, the food grade inner coating industry of cans is also constantly innovating and developing. In the future, the inner coating materials will be developed in the direction of more environmental protection and high performance, and the production process will be more intelligent and refined to meet the changing market demand.

As a supplier of aluminum cans, we will always adhere to the bottom line of quality, constantly increase investment in research and development, improve the level of production technology, strictly abide by industry standards and regulations, to provide customers with high-quality and safe cans products.