Duct tape Image credit: Duck Tape | Acrylic transfer tape Image credit: 3M | Filament tape Image credit: Grainger

 

Adhesive tapes are used to assemble materials or parts together using a sticky chemical bond. Adhesive tapes are an alternative to other assembly methods such as mechanical assembly (press fit, snap fit, etc.), mechanical fastening, adhesive bonding, soldering, welding and brazing. Adhesive tape has the advantage of lower temperature applications compared to soldering, welding and brazing. It also does not require pre-drilled and/or pretapped holes or welded-on studs on the components like is needed for mechanical fastening. Adhesive tape can be easier for production operation and automation compared to processes using a liquid adhesive, which must be sprayed, rolled or otherwise dispensed onto the parts before bonding. In adhesive tapes, the adhesive is preapplied to a uniform backing material that enables the tape to be handled with web processing equipment. The disadvantage of adhesive tape is its inferior strength compared to brazing, welding or mechanical fastening. The lower bond strengths may not meet more demanding design requirements.

 

Dutch artist Johan Rijpma uses adhesive tape to create mesmerizing art displays.

 

 How Adhesive Tape is Made

 

 

  Adhesive tape production Image credit: Made How

 

 

Adhesive tapes are made by coating a backing or carrier (paper, plastic film, cloth, foam or foil) with an adhesive on a web or roll coater. The adhesive-coated tape is wound up to form a large jumbo roll. The jumbo roll is then split into narrow bands, which are wound on individual cores to produce the retail or commercial size rolls of tape. 

 

How adhesive tape is made. Video Credit: Discovery / Science Channel

 

How Adhesive Tape Works

 

Adhesive tapes work differently depending on adhesive coating, adhesive cure technology and backing. The backing or carrier can also result in performance differences due to strength or thermal characteristics - paper vs. film vs. metal foil vs. fiberglass cloth.

  • Air setting or film drying materials form a bond or "harden" by evaporating water or an organic solvent. Inorganic binders or cements are sometimes air setting. Refractory-type products may develop strong bonds after firing. Many pastes and gum adhesives are film-drying.
  • Anaerobic adhesives cure in the absence of air or oxygen.
  • Thermoplastic or hot melt adhesives can be repeatedly softened by heat and then hardened or set by cooling, which allows parts to be removed or repositioned during assembly. Most hot melt adhesives are solvent-free thermoplastics that melt or drop in viscosity above 180°F and then rapidly set upon cooling. They are used in a variety of manufacturing processes, including bookbinding, woodworking, construction, product assembly and box and carton heat sealing. Hot melt adhesive technology stems from the previous use of molten wax for bonding. Thermoplastic systems were introduced to satisfy performance needs. Typically, a pure hot melt system will not have the heat resistance of two-part, catalyst or thermoset adhesives. Hybrid hot melt systems are available which exhibit a degree of reactive curing. Polyethylenes, polyamides and ethylene-vinyl acetates are common types of hot melt adhesives. Heat activated adhesives become sticky or tacky when warmed and are used in contact or PSA-type applications.
  • Thermoset adhesives are crosslinked polymeric resins cured using heat or heat and pressure. Cured thermoset resins do not melt and flow when heated, but they may soften. Cured thermoset resins also generally have higher resistance to heat than thermoplastics, but cannot be melted down and reprocessed. Phenolic, melamine and urea formaldehyde resins are thermosetting adhesives that offer strong bonds and good resistance to high temperatures.
  • Room temperature curing or vulcanizing products are polymer resins or compounds that either cure or vulcanize at room temperature. Vulcanization is a thermosetting reaction involving the use of heat and/or pressure in conjunction with a vulcanizing agent. It results in greatly increased strength, stability and elasticity in rubber-like materials. The vulcanizing agent is a crosslinking compound or catalyst. Silicones use moisture, acetic acid and other compounds as curing or vulcanizing agents.
  • Pressure sensitive adhesives (PSA) adhere to most surfaces with very slight pressure and retain their tackiness. PSAs are available in solvent and latex or water-based forms. Pressure sensitive adhesives are often based on non-crosslinked rubber adhesives, acrylics or polyurethanes. They form viscoelastic bonds that are aggressively and permanently tacky, and adhere without the need of more than finger or hand pressure.
  • UV or radiation cured adhesives use ultraviolet light, visible light or electron beam (EB) irradiation to initiate curing which forms a permanent bond without heating or excessive heat generation. One disadvantage of UV curing adhesives is the requirement that one substrate is UV transparent. Some UV resin systems employ a secondary curing mechanism to complete curing of adhesive regions shielded from the UV light. EB curable adhesives use electron beam radiation to cure or initiate curing. The electron beam can penetrate through material that is opaque to UV light.
  • Reactive/moisture cured resins are single-component adhesives that are applied in the same way as hot-melt adhesives. The resins react with moisture to crosslink and polymerize, thus resulting in a cured material. Polyurethane reactants (PUR) are examples of this type of technology. Certain silicones and cyanoacrylates also use a reaction with moisture or water to cure the adhesive or sealant.
  • Single component adhesives or sealant systems consist of one resin that hardens by reaction with surface moisture, a surface applied activator-primer or through the application of heat.
  • Two or multi-component adhesive or sealant systems consist of two or more resins or a resin and a hardener, crosslinker, activator or catalyst that when combined, react and cure into a polymerized compound or bond. Two component systems are mixed and then applied.
  • Other unlisted, specialty, proprietary technologies or cure types.


Composition of Adhesive Tape

Adhesive tapes typically consist of an adhesive-coated backing called a carrier. Single-sided tape is used to attach overlapping or adjoining materials where the tape is used to splice or seam the materials together. Double-sided tape is coated with adhesive on both sides and allows the joining of items back-to-back. Transfer tape consists of a single layer of adhesive without any backing. Transfer tape can also join parts between mating surfaces in a back-to-back or butt joint fashion.

 

Adhesive Coating Types

Selecting adhesive tapes and films requires an analysis of coating types. Acrylic adhesives provide excellent environmental resistance. Epoxy resins exhibit high strength and low shrinkage during curing. Polyurethane (PUR) and isocyanate adhesives provide excellent flexibility, impact resistance and durability. Silicone adhesives have a very high temperature resistance. Rubber-based adhesives provide highly flexible bonds. Pressure sensitive adhesives (PSA) are tacky at room temperature in a dry (solvent-free) form; they adhere firmly to a variety of surfaces upon contact, requiring only the application of finger or hand pressure. Some adhesives are thermally activated or require moisture. Others, such as latex gums, adhere to themselves. Hot melt and thermoset adhesives are commonly available.

 

Adhesive Coating Options

Acrylic Acrylic adhesives provide excellent environmental resistance and faster setting times than other resin systems.
 Epoxy Epoxy resins are adhesives that exhibit high strength and low shrinkage during curing. Epoxies are known for their toughness and resistance to chemical and environmental damage.
Hot Melt/Heat Activated Heat activated, thermally activating or heat bond adhesives become tacky or sticky when heat is applied. The adhesive may soften but not necessarily melt. Hot melt adhesives can be repeatedly softened and melted by heat and hardened or set by cooling. Cooling allows the removal or repositioning of parts during assembly.
None/Non-adhesive Non-adhesive tapes, films or laminates do not have an applied adhesive but may be self-adhering. PTFE thread-sealing tape is a type of non-adhesive tape.
Pressure Sensitive (PSA)  Pressure sensitive adhesives (PSAs) or contact adhesives are aggressively and permanently tacky at room temperature in dry (solvent free) form. They adhere firmly to a variety of dissimilar surfaces upon contact, requiring only the application of finger or hand pressure. PSAs do not require water, solvent or heat activation in order to exert a strong adhesive force on materials such as paper, plastic, glass, wood, cement and metal. PSAs have a sufficiently cohesive holding and elastic nature so that despite their aggressive tackiness, they can be manipulated by hand and removed from smooth surfaces without leaving a residue. In terms of general trade usage, leading tape manufacturers do not sanction the extension of the term "pressure sensitive" to include tapes and adhesives just because they are sticky (e.g. fly paper), or just because they adhere or cohere.
 Rubber Rubber-based adhesives provide highly flexible bonds and are usually based on butadiene-styrene, butyl, polyisobutylene or nitrile compounds.
 Silicone Silicone adhesives and sealants have a high degree of flexibility and very high temperature resistance.
 Specialty/Other Other unlisted adhesive types

 

Backing/Carrier Types

Adhesive tapes and films vary in terms of carrier material. Films are synthetic resin adhesives that sometimes include a carrier fabric. Typically, plastic films are made of thermoplastic resins. Aluminum foil is laminated to paper or plastic films for improved strength. Electrodeposited copper foil is used in the manufacture of multilayer printed circuit boards (PCB). Transfer tape, a highly versatile product that consists of a thin adhesive film without a carrier, can be transferred to most dry surfaces from a peel-away release liner. Transfer tape and double coated tapes often use a release liner to enable or improve handling and dispensing of the tape product. Liners for double-sided tapes often incorporate differentially coated release liners that are easy to peel. These release liners are made of paper, film or silicone sheets. Board liners are heavyweight paper liners that are usually measured in terms of points. The 12-point liner is the most common type. Other backing materials include cloth, foam, paper, plastic, rubber, silicone and urethane.

 

Backing/Carrier Options

Acrylic/Acrylate Acrylic films are plastic or thermoplastic resin films manufactured using polymethyl methacrylate (PMMA) or polymethyl-2-methylpropanoate. PMMA resins are the result of polymerization of acrylic acid derivatives or other acrylate compounds such as esters of acrylic acid, methacrylic acid, acrylonitrile and their copolymers. Acrylic films have good optical properties (clarity) and are UV stable. Plexiglas® (Altofina Chemicals, Inc.) is a common acrylic sheet and film material
Cloth-Woven Fabric

Cloth products incorporate woven cloth or a fabric layer(s) for reinforcement, improved strength, heat resistance or electrical properties.

Cloth-Felt/Non-woven

Felt or non-woven tape, film or laminates are applied to substrates to prevent scratching.

Glass/Fiberglass Tape and film products are reinforced with fiberglass, fiberglass composite material or a glass layer.
Filament

Filament is generically referred to as strapping tape. Filament tape draws its strength from thousands of individual filaments woven into yarns that are embedded in adhesive on the tape's backing.

Fluoropolymer Fluoropolymer films, layers or coatings consist of plastics such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF). Fluoropolymer coatings are used in applications that require superior chemical resistance, good dielectric properties and water and stain repellent characteristics. Fluoropolymers are also used in applications where the material handled must not stick to the belt, fabric or laminate. Polytetrafluoroethylene (PTFE) is an insoluble compound that exhibits a high degree of chemical resistance and a low coefficient of friction. It is sometimes marketed in proprietary classes of materials such as Teflon®, a registered trademark of DuPont Dow Elastomers.
Foam Adhesive-coated polyolefin foams include an adhesive that is protected by a liner in the form of a tape, film or laminate.
Metal Foil/ Sheet Metal foil tapes have aluminum, aluminum-reinforced and lead backings.
Paper Paper or flat back products have a paper backing.
Plastic/Polymer Plastic products incorporate one or more plastic layers, or consist of plastic film or sheets that can be clear or colored, printed or plain, single-layered or multilayered, and combined with materials such as aluminum and paper. There are two general categories of plastics: thermoplastics and thermosets.
PET/Polyester Polyethylene teraphthalate (PET)/polyester products use a PET or polyester backing in the form of tape, film or laminate.
Polyimide (e.g. Kapton®) Polyimide film maintains excellent physical, mechanical, chemical and electrical properties over a wide range of physical environments. Kapton® tape is made of polyimide film and a heat-resistant, silicone adhesive. Kapton is a registered trademark of DuPont Teijin Films. Polyimide films are very useful substrates for the manufacture of flexible circuit materials.
 PVC/Vinyl Polyvinyl chloride (PVC)/vinyl products use a vinyl or PVC backing in the form of a tape, film or laminate.
 Rubber Products use a rubber backing in the form of a tape, film or laminate.
 Silicone Products use a silicone backing in the form of a tape, film or laminate.
Specialty/Other Other unlisted backing materials.

 

Adhesive Tape Specifications

Important performance specifications for adhesive tapes include peel strength, tensile strength, temperature resistance and dielectric strength. Physical parameters include width, thickness and length. 

Performance Specifications

Temperature Resistance Temperature resistance is the maximum temperature that products can withstand.
Peel Strength/Adhesion Peel strength or adhesion is the force required to separate two bonded surfaces.
Electrical Resistivity Electrical resistivity is the longitudinal electrical resistance (ohm-cm) of a uniform rod of unit length and unit cross-sectional area. Resistivity is the inverse of conductivity.
 Dielectric Strength Dielectric strength is the voltage that products can withstand without allowing the passage of current.

 

Sizes/Configuration

Width The breadth between predetermined edges of a tape, film or laminate. 
Thickness Thickness is the distance from one surface of a tape, film, or laminate backing or adhesive to the other. It is usually expressed in mils or thousandths of an inch and is measured under slight pressure with a special gauge.

 

Features of Adhesive Tape

Adhesive tapes and films are available with a variety of features. Some are chemically resistant, thermally insulating or electrically conductive. Others are permanent, removable, repositionable or protective. Safety products are reflective, highly visible and provide warnings about unsafe conditions. Weather resistant products are suitable for outdoor use. Transparent products allow the transmission of light.

 

Features Available

Abrasion/Scratch Resistant Tape and film products feature abrasion or scratch resistance.
Anti-Static/ESD Control Tapes or film products have anti-static, static dissipating or electrostatic discharge (ESD) control features. Typically, ESD control products have conductive, friction reducing or ionizing characteristics.
Dielectric/Insulating Dielectric tapes are used as membrane dielectrics in multilayer capacitors. These tapes consist of an acrylic polymer mixed with a dielectric solid. 
Electrically Conductive Electrically conductive products can conduct electricity and provide protection from electrostatic discharge (ESD). They may also provide shielding from electromagnetic interference (EMI) or radio frequency interference (RFI). Conductive tapes and films are used in electrical heating elements and other electronics applications 
EMI/RFI Shielding EMI or RFI shielding products can provide protection or shielding from electromagnetic interference (EMI) or radio frequency interference (RFI). Most shielding products use a conductive material to surround the device or equipment requiring shielding. Conductive EMI shielding works on the electric field portion of the electromagnetic wave or interference. Magnetic shielding is less common.
Permanent Once applied, products become permanently bonded to the substrate.
Removeable Removable tapes can be applied and then removed without damaging the substrate, but not necessarily reused or repositioned.
Thermally Insulating/Insulative Thermally insulating or insulative products, such as structural insulative panels (SIP), provide insulation from heat.
Transparent Transparent products allow the transmission of light. A tape is rated as transparent if 10-point type can be read easily when the tape is applied directly over it.
 UV/Weather Resistant Weather resistant products are suitable for outdoor use and resistant to ultraviolet (UV) light, cold, heat, water or other weather conditions.
Other Other unlisted or proprietary features. 

 

Adhesive Tape Applications

There are a variety of applications for adhesive tapes and films, as described in the table below. Some are suitable for automotive, aerospace, construction, industrial, medical or packaging applications. Others are designed for use with coated abrasives or cable ends. Electrical tape provides high voltage and heat resistance. Masking tape is used to temporarily cover bands or small areas next to an area to be painted. Duct tape is used in heating, ventilation and cooling (HVAC) applications. Adhesive tapes and films are used to splice film, build membrane switches or control panels, and join materials together in processes such as seaming or hot sealing. Products that are suitable for printing, graphics and signage applications are also available. 

Applications

Ceramic/Glass Ceramics consist of oxides, carbides, nitrides and other non-metals with high melting points. Ceramics are suitable for applications requiring wear resistance, thermal stability and electrical resistivity.
Concrete/Masonry Concrete and cements consist of a mixture of a binder or clinker and a coarser aggregate. They are used to patch or line floors and walls, bond brick, and join components for use in high-temperature applications. Clinker is a fused mineral or mineral mixture, such as alumina or bauxite and lime, which is crushed into a fine powder. Aggregates are coarser, granular materials that are added to mortar, grout or cement at mixing to impart special properties such as thermal stability, wear resistance and oxidation resistance. Synthetic aggregates are fused mineral or mineral mixtures crushed to a coarse, granular size range rather than a fine, powdered clinker. Portland cement is the most common bond used in structural concretes and mortars. Polymer cements have a resin bond and are used in corrosion protection, mortars for corrosion-resistant floor tiles, and other specialized industrial applications. Masonry consists of tile, bricks, stone or other ceramic components that are bonded together with mortar or adhesive.
Composites Composite materials consist of a resin (suitable for molding) and a matrix (typically fibers or textile material) which serves to enhance strength, alter electrical or magnetic properties, or enhance wear resistance
Dissimilar Substrates Adhesive or sealant systems can bond dissimilar substrates, such as metal to rubber.
Metal Metals are opaque, fusible, ductile and typically lustrous substances that are good conductors of heat and electricity. They form cations by the loss of electrons and yield basic oxides and hydroxides. Metals that are used in structural engineering applications have a high toughness that is a combination of high strength and ductility.
Paper/Paperboard Paper or paperboard products are produced from a pulp of cellulose, cotton, wood or other vegetable fibers. The pulp is laid down on a fine screen from a water suspension to form sheets that are dried and further processed.
Plastic Plastics are organic, synthetic or processed materials that are mostly thermoplastic or thermosetting polymers of high molecular weight. They can be made into objects, films or filaments.
Porous Surfaces Substances are adhesives or sealants with a high viscosity or gel-like consistency. Typically, these materials have the ability to work with porous surfaces.
Rubber/Elastomer Rubber and elastomers are characterized by a high degree of flexibility and elasticity (high reversible elongation). Natural or synthetic rubber is vulcanized to increase useful properties such as toughness and resistance to wear for use in tires, electrical insulation and waterproof materials. Vulcanization is a chemical treatment that adds sulfur and heat to crosslink the rubber. Natural rubber is an elastic substance that is obtained by coagulating the milky juice of any of various tropical plants. Essentially, natural rubber is a polymer of isoprene and is prepared as sheets and then dried. Synthetic rubbers or elastomers can be based on a variety of systems such as silicone, polyurethane or neoprene.
Textiles/Fabrics Substances are adhesives or sealants suitable for coating, filling, sizing or sealing non-woven or woven textiles. Sizing adhesives or resins are used to fill paper, textile webs and other fibrous products.
Wood/Wood Product Wood is a natural composite extracted from the stems, branches and roots of trees. It is a hard, fibrous substance that consists of xylem, cellulose fibers in an amorphous, lignin polymer matrix. Lignin is a biogenetic cross linked polymer which bonds together adjacent cell walls into a straw or wood tissue composite. Cellulose is a polysaccharide of glucose units that constitute the chief part of the cell walls of plants. It occurs naturally in fibrous products such as cotton and kapok and is the raw material of many manufactured goods such as paper, rayon and cellophane.
 Other Other unlisted, specialty or proprietary substrates. 

Resources

Made How - Cellophane Tape

 

Science Channel How it's Made via Youtube

 

3M - Industrial Tapes

 

Gulf Packaging - Adhesive Tape

 

Read user Insights about Adhesive Tapes

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