ADHESIVE TYPES

The complete UHU range.

WET ADHESIVES

Wet adhesives are only applied to one of the parts to be joined, which is then immediately glued to the second part. The parts must be fixed together as adhesion only occurs when the solvents have evaporated. In case of so-called (solvent-free" adhesives, water is the carrier substance. Open-poured materials encourage the drying of wet adhesives. 

Glues with solvents are used for a wide range of jobs. In particular these include jobs involving a particularly fast application sped, when paper curling must be avoided or when non-porous materials are being glued. These adhesives consist of resins or rubbers that are converted to liquid form using traditional solvents e.g. alcohol, acetone or methylacetate. The glue sets as a result of the evaporation of the solvent. The solvent must therefore be able to escape through the material. This is the case with wood, cardboard and leather. In the case of non-permeable, airtight materials such as metal, porcelain or hard plastics, the glued surface must be as long and narrow as possible so that the solvent can escape out the sides. Many plastics are, to varying extents, corroded or even dissolved by solvents. Therefore, when glueing plastics you must always note the corresponding instructions on the packaging.

Permeable materials

Permeable materials

Non-permeable materials

Non-permeable materials

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CONTACT ADHESIVES

Contact adhesives are applied to both parts to be joined. After the flash-off time, which varies depending on the solvent, the parts to be joints are pressed together with a high level of force. The parts to be joined bond immediately. Loads can be applied to the workpiece after a short period of time. 

UHU contact adhesives, such as UHU All Purpose Adhesive Power or UHU greenit, are applied using the double-sided bonding method. They are particularly well-suited to the glueing of thick materials that are solvent-permeable. Contact adhesive enable the creation of instant bonds, that become very strong after a short period of time. They remain elastic even once dry, and are therefore particularly suitable for materials that must remain flexible at the glued joint (e.g. soles of shoes, leather belts). Contact adhesives are also used in large surface processing (e.g. the veneering of tables). Solvent-free UHU contact adhesives are also available.

Contact adhesives
Contact adhesives

What is "contact bonding"?

Contact bonding is a procedure whereby a thin and even layer of adhesive is painted over both surfaces to be glued together. The parts are not immediately joined together, but are kept apart (so that the solvent can evaporate) until the glued surfaces feel "dry to the touch". Only then are the parts placed gently on top of one another, aligned and briefly and forcefully pressed together. Here it is the pressing force and not its duration that is important. If contact bonding is performed correctly, the positioning of the parts can no longer be corrected. 

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REACTIVE ADHESIVES

Reactive adhesives are adhesives that set by means of chemical, physical or catalytic processes. Depending on the reactive behaviour, they can have one or two components.

Single-component reactive adhesives
Single-component reactive adhesives react with air humidity, UV light or atmospheric oxygen (aerobic adhesives), or with the exclusion of air, e.g. with metal ions (anaerobic adhesives) Single-component adhesives are applied onto one of the surfaces to be glued. The reaction starts immediately as a result of the second reactive component in the atmosphere or on the surface to be glued. 

Two-component reactive adhesives
Two-component reactive adhesives consist of components in liquid, paste or powder-form, which must generally be precisely mixed in the stated proportions. The processing time (pot life) is limited, with setting commencing immediately. The glued joint must be fixed in place until fully set, with the setting time dependent on the type of adhesive and the ambient temperature.

High-performance bonding with reactive adhesives
(fast, strong and versatile)

Reactive adhesives are adhesives that set by means of chemical, physical or catalytic reactions. They are generally used when a high level of strength is required. These reactive adhesives generally have two components (binder and hardener). Binders and hardeners are always packaged separately. If the two components come into contact with one another, a reaction begins that sets the glue, causing it to reach its final strength.
Single-component reactive adhesives contain a non-active hardener, which does not reactive while in the packaging under normal conditions. A reaction only begins when the hardener comes into contact with the second reactive component. Depending on the type of adhesive, the reaction is started by air humidity, UV light or atmospheric oxygen (aerobic adhesives).

HERE'S HOW IT WORKS:

In the case of two-component adhesivesbinders and hardeners are mixed thoroughly at the specified ratios and must be used within the stated processing time (between one hour and several hours depending on the type of adhesive). A temperature of approx. 20°C is ideally suited for bonding.

In the case of single-component adhesives, the adhesive is applied onto one of the surfaces to be bonded. The reaction starts immediately as a result of the second reactive component in the atmosphere or on the surface to be glued. This second component must actually also be present.

Cyanoacrylate adhesives (superglues) set in the absence of oxygen, with the air humidity that is present on the surface to be bonded. The prerequsite is therefore an absolutely perfect fit between the surfaces to be bonded, which may be moistened by breathing on them if necessary.

WHEN ARE REACTIVE ADHESIVES USED?

  • When the glued joint is to be subject to heavy loads. 
  • When the glued joint is required to be particularly strong or temperature-resistant. 
  • When the glued surfaces are enclosed, meaning that any solvents could not escape through the material.

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SINGLE-COMPONENT REACTIVE ADHESIVES

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TWO-COMPONENT REACTIVE ADHESIVES

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HOT-MELT ADHESIVES

Hot-melt adhesives come in cartridge, pen, powder, granulate, mesh or film form. They are solvent free, with no mixing or dosing generally required.
Hot-melt adhesives melt under temperature. This takes place either directly within the glued join (e.g. by ironing the edges) or using a glue gun, from which hot glue is applied to the parts to be bonded. Hot-melt adhesives melt at temperatures between 110°C (UHU Glue Gun Melt 110) and above 220°C with some other systems.

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PRESSURE-SENSITIVE ADHESIVES

Pressure-sensitive adhesives are products that remain permanently adhesive. These materials are used in instances where the adhesion is not intended to be permanent and subsequent separation is desired. Pressure-sensitive adhesives are mainly used on adhesive films and tapes, on double-sided sticky tape and sticky pads, as well as on sticky notes, self-adhesive labels and films.

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