Water-based adhesive with polymer, water-soluble resin as the main raw materials, water as diluent, tasteless, environmentally friendly and non-toxic. With the continuous improvement of people's awareness of environmental protection, waterborne adhesives have developed rapidly in recent years.
1. Characteristics of waterborne adhesive:
1. Applicable substrate.
No adhesive is omnipotent, and an adhesive is only suitable for bonding a particular material or a particular material. At present, waterborne adhesives are mainly used for bonding between polished paper / paper, PET/ paper, BOPP/ paper, PVC/ paper, plastic / plastic and other substrates.
2. Main features:
The characteristics of waterborne adhesive mainly include appearance (product appearance and film appearance), solid content, density, pH value, solvent ratio, opening time, high / low temperature resistance, initial viscosity, curing viscosity and so on.
The bonding methods of waterborne adhesives are generally divided into three types: mechanical bonding, hand bonding, mechanical bonding and hand bonding. Different bonding methods correspond to different characteristics. Usually, when the mechanical adhesive is used, the opening time of the waterborne adhesive is short; when the hand adhesive is used, the opening time of the waterborne adhesive is long; when the film is bonded, the film is flexible and the curing viscosity is high. In the aspect of high / low temperature resistance, water-based adhesive is required to be baked at 60 ℃ for 72 hours, and then frozen at-10 ℃ for 72 hours, the bond strength does not change, there is no degumming, film brittleness and so on.
3. Advantages and disadvantages.
The advantage of waterborne adhesive is that waterborne adhesive belongs to emulsion system, so its viscosity does not change with the change of polymer molecular weight, and it is environmentally friendly, non-flammable and easy to clean.
The disadvantage is that the waterborne adhesive will cause some pollution to the environment because of the addition of various emulsifiers, stabilizers, pH regulators and anti-freezing agents. In addition, the water-based adhesive volatilizes slowly, the initial viscosity is poor, the price is on the high side, the wettability to the plastic film is poor, easy to rust the equipment.
II. Selection of Waterborne Adhesives.
1. Application index.
The preparation methods and production processes of different types of waterborne adhesives are different, so their chemical and physical properties are also different, that is, the application index is different. It is generally believed that the important application indexes of waterborne adhesive in packaging and printing industry mainly include bond strength, high / low temperature resistance, moisture resistance and stickiness. In practical application, the defects such as weak bonding, degumming and brittleness of adhesive film are basically caused by the substandard of the above four application indexes.
2. Performance-to-price ratio.
When choosing water-based adhesives, we should first understand the characteristics of processed products and choose adhesives with higher performance and price, which is a reasonable way to choose and buy.