The selection of adhesives for food flexible packaging requires consideration of a number of factors. In general, the following conditions should be met:
(1) Non-toxic;
(2) No harmful extracts appear after packaging foods;
(3) Applicable temperature requirements for food storage;
(4) good weather resistance, no yellow foaming, no chalking and delamination;
(5) have a certain resistance to media capabilities;
(6) Does not erode the printing pattern ink and has a high affinity for the ink.
The adhesive for packaging composite films should also have the following properties:
(1) Adhesion: The adhesive must have the ability to simultaneously bond two different materials;
(2) Softness: Meet the requirements of flexible transportation and storage after compounding;
(3) Heat resistance: According to the food processing technology, there is a certain degree of heat resistance;
(4) Cold resistance: It can meet the requirements for low temperature storage of foods;
(5) Resistance to medium: The stability of the adhesive is very important. It must be able to withstand the erosion of the medium, otherwise it will cause the layered peeling of the composite film and lose the packaging effect.
(6) Safety and Hygiene: Meet the requirements of food packaging safety and health related standards
China has already had laws and regulations and corresponding hygiene standards for food and packaging materials. There are two of them: First, the “Food Hygiene Law of the People's Republic of China†and the second is “Administrative Measures for Plastic Products and Raw Materials for Foodâ€. The "Food Hygiene Law" was promulgated by the State Council, and the "Administrative Measures" was promulgated by the Ministry of Health. Both of these are mandatory laws that violate their rules and regulations. The content of food hygiene regulations is much broader than the management methods and is a comprehensive law. The latter is professional and refers only to plastic products and raw materials. The scope of management is limited to the production and management of various plastic food container containers that come in contact with food, packaging materials made of conveyor belts and plastics, and synthetic resins and auxiliaries used therein.
There are two major series of alternatives to solvent-based adhesives. One is a water-based adhesive. Advantages of water-based adhesives are: Viscosity does not change significantly with changes in the molecular weight of the polymer, which can quantify polymer macromolecules to increase their cohesive strength; viscosity is generally lower than that of solvent-based ones; easy to mix with other resins or pigments Improve performance and reduce costs; Non-combustible and non-toxic, suitable for substrates that are easily attacked by organic solvents; Easy to formulate and easy to clean.
Water-based adhesives are mainly single-component and two-component products. The characteristics of the single-component series are that they do not need to be proportioned when gluing, and are used directly. The operation process is simple, the cost is low, and the production efficiency is high. The advantages are more prominent in the composite properties of the film and the aluminized film, and do not cause the transfer of the aluminized film like the polyurethane adhesive. Due to the limitation of peel strength, one-component water-based adhesives are mainly used in the field of lightweight packaging such as puffed foods, biscuits, candy condiments and pharmaceuticals. The two-component water-based adhesives break through the technical problems of peel strength, heat resistance and chemical resistance, and can be used for packaging including cooking foods and liquid foods.
The second is a solvent-free adhesive. Solvent-free adhesives are basically also composed of two-component polyurethane adhesives, whose main agent and curing agent have higher viscosity at room temperature but still have fluidity and are semi-solid substances. When compounding is to be performed, the main agent and the curing agent are mixed in proportions, placed in an adhesive tray having a heat-retaining function, the viscosity is reduced to a suitable level by heating, and then passed through an anilox roller having a heat insulating function. Go to the substrate. After coating, it is not necessary to heat and dry directly to compound with another substrate.
Rohm and Haas Company is the first multinational company to promote waterborne composite adhesives in China's flexible packaging market, and it is also the first company to commercially supply waterborne adhesives in the Chinese market. Rohm and Haas Company believes that the flexible packaging market in Europe and the United States currently uses water-based and solvent-free series. The development direction of China's flexible packaging market is undoubtedly more environmentally friendly and healthier. Rohm and Haas Company helps its customers to cope with future regulations.
At present, Rohm and Haas has accounted for about 90% of the global market for water-based adhesives in the flexible packaging industry.
American Rohm and Haas company's water-based adhesives are mainly single-component and two-component two major product lines. One-component water-based adhesives are mainly used in light-weight packaging such as puffed foods/cookies/confectionery/condiments. The two-component water-based adhesives overcome technical difficulties such as peel strength/heat resistance and chemical resistance, and can be used for high-end products such as steamed foods and liquid packaging. The adhesive layer of the water-based acrylic adhesive is both flexible and tough, and is particularly suitable for manufacturing various laminating composite films for food packaging. Many well-known domestic egg yolk pies/biscuit/ instant noodles/muesli/soybean milk brands have even designated their packaging manufacturers to use water-based adhesives produced by Rohm and Haas. End-user support has accelerated the promotion of water-based adhesives in China.
Rohm and Haas committed itself to promoting the development of energy-saving, safety, and environmental protection throughout the entire industry chain. Through technical support and exchanges with food manufacturers, it has recognized new environmentally-friendly packaging to promote the normal and healthy development of the industry chain. At the same time, Rohm and Haas has always paid attention to the voices of the environment, communities and consumers. It advocates moderate packaging and green packaging in the industry, and advocates that packaging should be based on practical environmental protection and safety and health, and pay attention to environmental protection and other social responsibilities.
Rohm and Haas Company is the world's largest manufacturer of acrylic emulsions and has invested in the construction of two acrylic emulsion production plants in Beijing, China. Rohm and Haas introduced the mature environmentally friendly water-based adhesive in the US market. It does not contain organic solvents, and its performance can fully meet the requirements for film and film used in general food packaging, and dry compounding between film and aluminized film. Requires alternative solvent-based polyurethane adhesives and can be used directly on existing solvent-based dry scrubbers. Rohm and Haas company's raw materials for adhesives, such as monomers and intermediates, are self-manufactured and synthesized. A strong supply chain ensures the stability of raw materials. Rohm and Haas' advanced production processes and fully automated equipment have made it the world leader in water-based adhesives. In addition, the use of this water-plastic composite packaging film can be cut immediately without curing, so it can reduce the production cycle for color printing manufacturers, especially in the busy season can easily deal with emergency orders of food manufacturers.
Source: Ink Information