Although the use of hot melt adhesives in medical packaging accounts for only a small proportion of the total market share of hot melt adhesives, the technical requirements for the period are very high, because if the adhesive fails, it may lead to endangering human health.

Manufacturers have a unique set of requirements for medical packaging (including pharmaceuticals and medical devices), including reliable barriers that can withstand sterilization and sterilization, can prevent drugs from being stolen, and are easy to use, strong in texture, and reasonably priced. Timely, reliable technical backing, etc., for a multi-layer composite, requires that the laminate be able to withstand the third heat, withstand impact and tear resistance. Therefore, a variety of tests must be performed on this laminate to see if the characteristics of the mixture can meet the packaging requirements.

Hot melt adhesives are used for many advantages of medical packaging:

The first is that it can take different forms and be applied as separate points, lines or patterns. The materials used for this pattern are only 30 to 50% of the total coated area.

Secondly, hot melt adhesives can be applied on the surface of coated materials and have better adaptability than ordinary aqueous adhesives or solvent-containing adhesives. It can be used above a coating weight of 5 g/m2 to a coating weight of more than 50 g/m2. High coating materials can absorb shocks and vibrations to the package under severe shipping conditions.

Third, the biological coexistence and harmonization of products is that hot-melt adhesives will not cause biological reactions to packaging materials and products.

However, there are some restrictions on the use of hot melt adhesives for medical packaging. Its viscosity must be limited to less than 10,000 centipoise (viscosity unit) at 165°C, because in the case of high temperatures, it will affect and limit the amount of hot melt adhesives. performance.

The hot melt adhesive is 100% solid, it does not need to be dried or cured, only needs to be melted and then cooled, so the equipment for applying the hot melt adhesive is relatively simple and does not require excessive cost.

In terms of technology and development in the use of hot melt adhesives in the post-printing process, etc., the technology and structure have changed in recent years, particularly due to environmental protection campaigns and the effects of waste recycling regulations; however, the printing has been modified at a later stage. Including cover, laminating and other technologies are still regarded as effective measures to improve the printing quality. There are many reasons for taking these measures, including:

1. To improve the display effect of product packages is a better way to improve the company's image.

2. Protect product packaging and prevent ground wear during transportation.

3. Protect product packaging from external influences, such as the effects of wet climates.

4, increase the sense of beauty and health and cleanliness.

As early as 60 years ago, in the later printing period, the process of covering light was mainly using cellulose acetate to protect packaging, book covers, posters, and magazine covers. In the future, solvent-based Vanishin replaces cellulose acetate. Twenty-five years ago, UV-cured coating became a major shift in printing and finishing because it reduced costs and contained no volatile organic compounds, but it provided high gloss and prevented wear.

Today, the application of barrier coating on the packaging has become a key area of ​​the post-printing process, and the enhancement of barrier properties has become the main purpose of medical packaging. If the packaged product is to be protected from moisture, the barrier coating is applied externally to prevent the moisture from penetrating the package;

If the product itself seeps out grease or moisture, the barrier coating is applied to the surface of the inner layer of the package.

However, starting from the concept of environmental protection, the use of barrier coatings on the surface or inner layer of packaging will increase the difficulty of sorting, recycling, and regeneration of packaging waste. There is also a problem of gas pollution during incineration. Therefore, it is not a case of packaging in Germany that implements new packaging regulations. Compatible, but hopefully accepted in other countries.

In the face of new developments, new coating materials and coating technologies are being researched and developed, namely, new coating materials using water as the dispersion medium, and the coating materials are dried at a high speed by a hot air jet dryer. Overcome the above issues. There are two ways to apply this coating:

1. Barrier coating on water and oil - The application of 8 g/m2 of simple coating on porcelain clay can be effective. It is used for packaging internal barriers. In the surface without porcelain coating, secondary coating is required, and hot air is blown dry at high speed. The total amount of secondary coating is recommended to be 12 g/m2.

2. Barrier coating to prevent water vapor - secondary coating is required. The first coating is used for sealing and the next is barrier coating.

Since the above coatings do not contain chlorine and fluorine, they are in line with today's environmental goals, and their packaging waste can be completely regenerated. At the same time, there is no negative impact on the coating line and the water treatment plant, and there are no hazardous emissions when the waste is burned.

Source: "Shanghai Packaging," 2005, Issue 4,