Printing Waterborne Adhesives Features and Selection Points

Water-based adhesives are mainly made of macromolecule polymers, water-soluble resins, etc. Water is used as a solvent, the odor is small, and the environment is non-toxic. With the continuous improvement of people's environmental awareness, water-based adhesives have become the mainstream of the market in recent years.

In practical applications, some packaging and printing companies lack sufficient understanding of water-based adhesives, causing some quality problems. Among them, the issue of water-based adhesives that are difficult to bond is one of the technical bottlenecks that plague many packaging and printing companies. In order to allow more packaging and printing companies to understand water-based adhesives, I will elaborate on the characteristics and choices of water-based adhesives in the hope that they will give the industry a little inspiration.

Waterborne Adhesives Features

1. Suitable substrate

None of the adhesives are omnipotent, and an adhesive is only suitable for bonding certain or certain specific materials. At present, water-based adhesives are mainly used for bonding between paper/paper, PET/paper, BOPP/paper, PVC/paper, plastic/plastic and other substrates.

2. Inherent characteristics

Each aqueous adhesive has its "inherent properties." The inherent characteristics of aqueous adhesives mainly include appearance (product appearance and film appearance), solid content, density, pH value, solvent ratio, open time, high/low temperature resistance, initial viscosity, and curing viscosity. Water-based adhesive bonding methods are generally divided into the machine sticky, hand sticky, machine sticky and hand stick with three kinds, different sticking methods correspond to different inherent characteristics. For example, when using stickies, the open time of water-based adhesives is required to be short; when hand-glue is used, the open time of water-based adhesives is required to be long; when the film is bonded, the film is required to be flexible and has a high curing viscosity. In terms of high/low temperature resistance, water-based adhesives are required to be baked at 60° C. for 72 hours, and then frozen at a temperature of 10° C. for 72 hours. The adhesive strength remains unchanged, and there is no degumming or film brittleness.

3. Advantages and disadvantages

Advantages of water-based adhesives are: water-based adhesives belong to the emulsification system, so its viscosity does not change with the change of polymer molecular weight, and its environmental protection, non-flammable, easy to clean. Disadvantages are: due to the addition of various emulsifiers, stabilizers, pH regulators, and antifreeze and antifreeze additives in water-based adhesives, it will cause some pollution to the environment. In addition, the water-based adhesive volatilizes slowly, the initial viscosity is poor, the price is high, the wettability of the plastic film is poor, and the equipment is easily rusted.

Waterborne Adhesive Selection

1. Application indicators

Some packaging and printing companies report that some water-based adhesives will soon undergo degumming after gluing; stickiness will be unstable, sometimes with strong bonds, and sometimes they will not stick together; they will be applied well when the weather is hot, but in the weather In cold situations, it cannot be applied.......... In fact, this is due to insufficient understanding of the application of water-based adhesives.

Different types of water-based adhesives have different preparation methods and production processes, so their chemical properties and physical properties are also different, that is, different application indicators. The author believes that the more important application indicators of waterborne adhesives in the packaging and printing industry include four aspects: bond strength, high/low temperature resistance, moisture resistance, and stickiness. The defects such as poor adhesion, degumming, and brittle film that often occur in practical applications are basically caused by the above four application indicators failing to reach the standard.

2. Value for money

When selecting water-based adhesives, the principle of “quality first, price second” should be adopted. However, some packaging and printing companies have a very one-sided view and mistakenly think that the higher the price of water-based adhesives, the better the quality; on the contrary, the worse the quality. In fact, this is not absolute. The author believes that when choosing water-based adhesives, we must first understand the characteristics of the processed products, choose a higher cost-effective adhesive, this is a reasonable way to buy.