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 ideal 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 purchased in a number of different types, making it possible for use in a wide variety of applications across several industries. For use with hobby or craft projects like 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 use of the Double Sided Fusible Interfacing. To use in industrial processes, adhesive is supplied in larger sticks and glue guns with higher melting rates. Besides hot melt sticks, HMA may be delivered in other formats including granular or power hot melt blocks for bulk melt processors. Larger uses of HMA traditionally use pneumatic systems to provide adhesive.
Examples of industries where HMA can be used includes: Closing the flaps of corrugated boxes and paperboard cartons inside the packaging industry. Spine gluing in the bookbinding industry. Profile-wrapping, product assembly and laminating applications in the woodworking industry. Disposable diapers are constructed through the use of HMA, bonding the non-woven material to both the backsheet as well as the elastics. Many electronic device manufacturers could also use an HMA to affix parts and wires. or secure, insulate, and protect the device’s components
Sometimes manufacturers request a certain hot melt color or clarity. Where does the colour result from? How come some adhesives more transparent than others? Does color and clarity mean quality? Why do customers like light colored and transparent adhesives?
All materials in this particular 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, tend to generate colorful bodies. As a result, whenever a hot melt formulation contains more polar ingredients, like 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 very compatible, having similar solubility parameters, the formulated product is going to be clear or transparent. On the other hand, to get a less compatible and Hot Melt Adhesive Film for Textile Fabric, the looks is cloudy or opaque.
Clarity may not be a large concern for most applications. However, the temperature stability for anyone cloudy and opaque formulations may be relatively poor in comparison to some clear formulations. Incompatible ingredients within the formulation tend to separate from each other upon heating at elevated temperatures because of the widely different solubility parameters. Remember that the above mentioned cloudy and opaque appearance fails to pertain to those materials with crystalline including wax and ethylene segment of Ethylene Vinyl Acetates (EVA).
Many users, especially in the Asian countries, often demand water white and clear HMPSAs for many applications simply due to esthetics reason. Consequently, water white, hydrogenated tackifying resins are needed for all those formulations. All selected ingredients should be compatible as well. Inside the principle of adhesion, a much more polar adhesive caarow generates better adhesion to substrates because of its higher surface energy. In other words, your selection of more expensive water white ingredients for esthetic purpose may adversely hurt adhesive performance. To compensate the loss of portion intrinsic adhesion resulted from lower surface energy; adhesive’s rheology is then becoming a key factor affecting adhesion performances. The rheology or mechanical property of adhesives will be discussed in a separate article.
Indeed, apart from the esthetic reason, clear Shape Flex SF101 Alternative exhibit far better heat stability and pot life while they are heated at elevated temperatures for a long period of time. This is very important particularly for that process employing an open coating system, such as a roll coating line.