The manufacturing of a dispersion adhesive tape is typically a fast, simplified process. A more exclusive group of adhesive tapes is manufactured using a solid-based adhesive containing pure acrylate. The manufacturing process is slower and more labour intensive than that required for acrylate dispersion adhesives. This type of acrylic tape, due to its robustness, has been utilised in the aeronautical and automobile industries for decades.
The key differences between the two types of adhesive tape Dispersion and Solid Acrylate is the omission of the need for additional resins when the tapes are manufactured in the Solid Acrylic adhesive process. There are two forces at play when considering adhesive joints: Adhesion; the force of holding the adhesive to a substrate and Cohesion; the adhesives ability to hold itself together.
Striking the correct balance between adhesion and cohesion makes for the ideal adhesive tape. If the adhesive is in direct contact with the surface, attractive forces Van der Waals forces — will result between the two elements at a molecular level. The closer the adhesive comes to the surface, the more these forces will come into play and increase the strength of adhesion to the surface. A similar principle of adhesion applies with the Gecko, which is able to walk upside-down to smooth surfaces such as panes of glass.
This is made possible by the large number of very fine setae hairs on the feet of the Gecko, increasing the contact surface and thus facilitating sufficiently strong adhesive forces. With these pressure activated solid acrylic adhesive tapes, the adhesive is "wetted" providing "the flow" to form strong clinging bonds at the molecular level —similar to what we witness in nature with geckos. Much of how we judge the suitability of airtightness tapes is down to how sticky we feel they are.
The stickiness or lack thereof is typically decided by the simple finger or thumb test. Pressing a finger onto the face of the adhesive. The result? Silicone is an example of a liquid with high surface tension. If silicone is present as a coating on the surface of the substrate, it will be difficult to be wetted by the adhesive. If used as an adhesive, on the other hand, it will produce a durable bond. Adhesion and cohesion must be considered when formulating or choosing the right adhesives.
An ideal bond consists of a combination of a high surface energy substrate and a low surface tension adhesive. The phenomenon described is attributed to the viscoelasticity of the adhesive at room temperature. Viscoelastic objects are materials that possess both viscous and elastic characteristics.
When gentle pressure is applied to the tape, it decreases its viscosity thus encouraging flow on the substrate at the microscopic level. Due to its elastic property, the original viscosity is regained with stronger intermolecular force with the substrate.
The Rolling Ball Test and Loop Tack Test are the most common quality control checks used to assess the tackiness of the adhesive tapes being produced. Adhesive tapes consist of a carrier, adhesive, and release liner. Not all types of adhesive tapes are required to have all the components but are still dependent on the properties of the material and the intended storage of the tape itself.
A more careful materials selection must be done on the carrier and adhesive especially when downstream processes, such as cutting, are involved. The adhesive tape may contain the following:. The carrier, or the backing material, is a thin flexible film that contains the adhesive. The carrier can have the following materials, depending on the end application of the adhesive tape:. This is the main component of every adhesive tape which primarily serves its purpose.
Adhesives are the polymeric compounds that are applied to the surface of two items to connect them and resist their separation.
The commonly used adhesives are enumerated below. Rubber adhesives are commonly used in duct tapes, masking tapes, and carton sealing tapes. It may be derived from natural rubber or synthetic rubber. Silicone adhesives are found in tapes which are mainly used in the electronics industry, where significant amounts of heat are dissipated in electronic components.
A release liner is one of the components that must be present in double-coated tapes and adhesive transfer tapes. This layer is peeled-off before the bond is made to the substrate. It preserves the tackiness of the adhesive until it is ready to be used, and protects it from sticking from the carrier. Adhesive tapes are categorized according to the arrangement of the carrier, adhesive, and release liner:.
Double-coated tapes are used to bond substrates with different surface properties which require different bonding requirements. It is highly customizable and the thickness of the adhesive can be varied on the opposite sides. The thermal resistance of a double-coated tape depends on the properties of its carrier. Create your free account or Sign in to continue.
See Subscription Options. Go Paperless with Digital. Louis H. Sharpe, editor in chief of the Journal of Adhesion , provides the following reply to this deceptively complex question: "The simplest answer that I can give to the question is that pressure-sensitive adhesives which are polymers are 'tacky' or 'sticky' because they are essentially very high viscosity liquids that also have some elastic characteristics--in technical terms, they are 'viscoelastic.
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