Hot-melt adhesives are as numerous as they are versatile. Generally, hot melts are applied by extruding, rolling or spraying, and the high melt viscosity makes them suitable for porous and permeable substrates. HMA are capable of bonding an array of different substrates including: rubbers, ceramics, metals, plastics, glass and wood.
Today, HMA (hot-melt adhesives) can be found in a selection of different types, permitting use in a wide range of applications across several industries. To use with hobby or craft projects such as the assembly or repair of remote device foam model aircraft, and artificial floral arrangements, hot-melt sticks and hot-melt glue guns are used in the application of the Double Sided Fusible Interfacing. To be used in industrial processes, adhesive is supplied in larger sticks and glue guns with higher melting rates. Besides hot melt sticks, HMA could be delivered in other formats including granular or power hot melt blocks for bulk melt processors. Larger applications of HMA traditionally use pneumatic systems to offer adhesive.
Examples of industries where HMA is utilized includes: Closing the flaps of corrugated boxes and paperboard cartons in the packaging industry. Spine gluing within the bookbinding industry. Profile-wrapping, product assembly and laminating applications in the woodworking industry. Disposable diapers are constructed with the use of HMA, bonding the non-woven material to both backsheet as well as the elastics. Many electronic device manufacturers may also make use of an HMA to affix parts and wires. or secure, insulate, and protect the device’s components
Sometimes manufacturers request a particular hot melt color or clarity. Where does colour result from? How come some adhesives more transparent than the others? Does color and clarity mean quality? How come customers like light colored and transparent adhesives?
All materials in this universe, when their electrons are excited by certain energy, may emit a wavelength showing different colors. These colors are observed by human eyes or detected by instruments. Most polymeric materials containing more polar functional groups and double or triple bonds, have a tendency to generate colorful bodies. Consequently, whenever a hot melt formulation contains more polar ingredients, including non-hydrogenated hydrocarbons resins and natural rosin along with its derivatives, they are normally darker as opposed to those hydrogenated ingredients.
Disregarding color, when the ingredients used in a hot melt formulation are extremely compatible, having similar solubility parameters, the formulated product will likely be clear or transparent. On the contrary, for a less compatible and Hot Melt Adhesive Film for Textile Fabric, the looks is cloudy or opaque.
Clarity may not be a huge concern for a lot of applications. However, the heat stability for all those cloudy and opaque formulations may be relatively poor in comparison to some clear formulations. Incompatible ingredients inside the formulation often separate far from the other person upon heating at elevated temperatures due to their widely different solubility parameters. Note that all these cloudy and opaque appearance fails to apply to those materials with crystalline including wax and ethylene segment of Ethylene Vinyl Acetates (EVA).
Many users, especially in the Asian countries, often ask for water white and clear HMPSAs for most applications simply due to esthetics reason. Consequently, water white, hydrogenated tackifying resins are required for anyone formulations. All selected ingredients should be compatible also. In the principle of adhesion, a much more polar adhesive caarow generates better adhesion to substrates due to the higher surface energy. In other words, the selection of higher priced water white ingredients for esthetic purpose may adversely hurt adhesive performance. To compensate the losing of portion intrinsic adhesion resulted from lower surface energy; adhesive’s rheology is then becoming a key point affecting adhesion performances. The rheology or mechanical property of adhesives is going to be discussed in a separate article.
Indeed, apart from the esthetic reason, clear Shape Flex SF101 Alternative exhibit much better heat stability and pot life when they are heated at elevated temperatures for long periods of energy. This is very important particularly for that process using an open coating system, for instance a roll coating line.