Adhesive selection and performance test methods

Due to the progress of social civilization and the demand of the market, more and more new materials and new processes are applied to the packaging industry, and bonding is increasingly used in the packaging industry as an important material that combines the complete packaging of a product. . After contacting many printing and packaging factories in China, we discovered that many manufacturers (including some large-scale printing and packaging plants) are absolutely professional in printing, but do not know much about adhesives, and even blindly choose and use them. Therefore, it brings great losses and waste to all manufacturers. "Difficult to bond" has become a bottleneck to all packaging companies, and almost every packaging and printing company has a deep headache.

In fact, as long as you choose a good, good use of adhesive, "difficult to bond" problem is completely resolved. Comprehensive experience and lessons of many printing factories, their problems often appear in the "select, use" these two links.

How to choose adhesive

1. Choose according to different materials

None of the adhesives are omnipotent, and one glue can only fit into one or a certain type of specific adherent material. Some manufacturers' blindly using plastics with “try it for a try” is a waste of time and energy, and it also causes great losses. Nowadays, BOPP/paper, polishing/paper, PET/paper, and high-light printing paper/paper are commonly used in various packaging factories. More than 98% of the products in packaging plants are made of these materials. In addition there are some such as PVC / paper, PVC / wood, UV / paper, etc., can use a special sealing glue.

2. According to the adhesive quality standards and performance options

Adhesives The most important quality standards are: A, adhesive strength (adhesion); B, high temperature resistance; C, low temperature resistance; D, aging resistance; E, adhesive strength retention. Many domestic packaging plants appear to have poor adhesion or brittle products for a period of time. Degumming is basically related to the above factors.

Paper-plastic adhesives require high bonding strength, strong initial adhesion, excellent resistance to high and low temperatures, good adhesion and retention, excellent moisture resistance and a wide range of bonding; the disadvantage of miscible adhesives is the slightly poor cleaning performance of containers. Liquid glue is wiped with solvent (due to good moisture resistance). The packaging plant hopes to meet all existing bonding requirements (BOPP/paper, polishing/paper, PET/paper, UV light/paper, ink/ink) through one or two types of adhesives.

Therefore, all manufacturers must choose the type of adhesive, according to their own actual situation, understand the characteristics of various varieties, performance indicators and scope of adaptation. At the same time, they must have a certain understanding of the companies that provide plastics, such as whether the products are mature, and how stable they are. Otherwise, the blind use of plastic is a great hazard, because the viscose products have hysteresis, many degumming phenomenon is only a few days or even months later, so use plastic must be careful.

3. price

The choice of adhesives, in addition to quality, is another important factor is the price. Some manufacturers believe that the higher the price and quality, the better. This view is very one-sided. In fact, adhesives only account for a small percentage of the cost of packaging products. Therefore, we must seek a suitable price level under the premise of understanding product characteristics, quality standards, and performance.

For packaging users, the glue that uses the most adhesive should be the sealing glue, and its adhesive properties and inspection methods are briefly introduced here.

Adhesive properties and inspection methods for sealing glue

Finished packages may not be used immediately, sometimes for months or even a year. Therefore, it is very important that the adhesive's resistance to cold and heat and its aging resistance are good or bad. For example, some packaging boxes work well for a short period of time. After a period of time, degumming and brittleness of the film occur. Therefore, in testing a glue adhesive performance should start from the following aspects:

1. Tear a sealed box along the edge of the seam to see if the substrate being bonded is torn or not. At the same time, use a nail to scrape the paper base attached to the film. If only a small piece of paper can be removed at a time Or the paper base could not be scraped at all, indicating that the adhesive has good adhesion on the film. Plastic/plastic sealing glue Since the two adhered surfaces are BOPP films, the film has a very strong flexibility, so it is not easy to damage, and it can be felt that the two adhered surfaces have strong adhesive force during the test.

Second, the bonded packaging box (at least one day has been placed) placed in a constant temperature oven at 60 °C baked for 72 hours out to cool if the seam or bottom does not pop open, hands do not take off the packaging box, plastic The film was not brittle, indicating no problem with the heat resistance of the adhesive.

Third, the bonded packaging box (at least one day has been placed) in the freezer in the refrigerator freezer 72 hours to be out of the box to dry the water after the hand shot box does not degummed, the film is not brittle, indicating that the adhesive There is no problem with the low temperature resistance.

Fourth, the first three kinds of adhesive products have passed through the preservation of some samples every two months to check a box, continuous inspection for six months no problem that the sealant can be used with confidence. (Text / Lin Enguo)