Hot-melt adhesives are as numerous as they are versatile. Generally, hot melts are applied by extruding, rolling or spraying, as well as the high melt viscosity makes them suitable for porous and permeable substrates. HMA are capable of bonding a range of different substrates including: rubbers, ceramics, metals, plastics, glass and wood.
Today, HMA (hot-melt adhesives) are available in a number of different types, making it possible for use in a wide variety of applications across several industries. To use with hobby or craft projects like the assembly or repair of handheld remote control 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. Apart from hot melt sticks, HMA may be delivered in other formats such as granular or power hot melt blocks for bulk melt processors. Larger uses of HMA traditionally use pneumatic systems to supply adhesive.
Samples of industries where HMA is used includes: Closing the flaps of corrugated boxes and paperboard cartons within the packaging industry. Spine gluing within the bookbinding industry. Profile-wrapping, product assembly and laminating applications within the woodworking industry. Disposable diapers are constructed with the use of HMA, bonding the non-woven material to the backsheet and also the elastics. Many electronic device manufacturers could 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 the colour come from? Why are some adhesives more transparent as opposed to others? Does color and clarity mean quality? Why do 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 or double or triple bonds, tend to generate colorful bodies. Consequently, each time a hot melt formulation contains more polar ingredients, such as non-hydrogenated hydrocarbons resins and natural rosin as well as its derivatives, they may be normally darker compared to those hydrogenated ingredients.
Disregarding color, if the ingredients used in a hot melt formulation are very compatible, having similar solubility parameters, the formulated product is going to be clear or transparent. On the contrary, for any less compatible and Hot Melt Adhesive Film for Textile Fabric, the look is cloudy or opaque.
Clarity will not be a big concern for most applications. However, the temperature stability for anyone cloudy and opaque formulations may be relatively poor when compared to some clear formulations. Incompatible ingredients in the formulation tend to separate away from each other upon heating at elevated temperatures because of their widely different solubility parameters. Remember that the aforementioned cloudy and opaque appearance will not pertain to those materials with crystalline like wax and ethylene segment of Ethylene Vinyl Acetates (EVA).
Many users, especially in the Asian countries, often demand water white and clear HMPSAs for most applications simply as a result of esthetics reason. Consequently, water white, hydrogenated tackifying resins are needed for anyone formulations. All selected ingredients should be compatible too. Inside the principle of adhesion, a much more polar adhesive caarow generates better adhesion to substrates due to its higher surface energy. Quite simply, the selection of higher priced water white ingredients for esthetic purpose may adversely hurt adhesive performance. To make up the loss of portion intrinsic adhesion resulted from lower surface energy; adhesives rheology will then be becoming an important factor affecting adhesion performances. The rheology or mechanical property of adhesives will likely be discussed in a separate article.
Indeed, aside from the esthetic reason, clear Shape Flex SF101 Alternative exhibit far better heat stability and pot life when they are heated at elevated temperatures for long periods of energy. This is very important particularly for the process using an open coating system, like a roll coating line.