LSE Tape Technology

Tecman Advanced Material Engineers have a range of LSE tapes formulated for bonding low surface energy plastics and other LSE materials.

Adhesive Tapes for Bonding LSE Substrates

Our technical support team are experienced in specifying LSE tape and developing technical bonding solutions for low surface energy materials and substrates.

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Low Surface Energy Bonding

The basic principle of adhesion is the molecular attraction between dissimilar materials. The strength of adhesion is determined by the surface energy of the material and for adhesive to form a strong bond with a substrate it must ‘wet out’, flowing across the surface of the substrate, increasing the adhesives surface area and allowing maximum bond strength.  It's crucial that the correct selection is made when using adhesive tape for bonding low surface energy (LSE) plastics.

Fig.1 represents a High Surface Energy that supports adhesion and the droplet of liquid is wetting out to the surface.

Fig.2 is a Low Surface Energy and the droplet is clinging to itself rather than the solid surface.



Many material manufacturers will not publish the surface energy of a substrate and identifying this at an early stage is critical to providing a successful bonding solution. Surface energy is normally measured in energy units called dynes/cm. A dyne is the amount of force required to produce an acceleration of 1 cm/sec² on a mass of 1g. Traditionally the surface energy of a substrate is measured using a contact angle measuring device. This is often impractical in a normal manufacturing environment so a more common solution is to apply a dyne solution to the solid surface.

Typical Surface Energies (Dynes/CM)

The dyne level of a substrate is one of the most significant factors in selecting the correct bonding solution. With the ever-increasing use of LSE engineering plastics in many areas this element of bonding considerations is becoming more and more important. Many Pressure Sensitive Adhesive (PSA) manufacturers are directing a large percentage of R&D resource into developing PSA technologies that will provide superior adhesion to LSE substrates.

It is strongly recommended that an adhesive Application Engineer is consulted at the design stage of any project which requires adhesion. For one they will have an in-depth knowledge of the polymer construction of materials and secondly, they are in touch with the latest developments within PSA technology. Tecman offer technical support for selecting the most effective adhesive product for low surface energy plastics and other LSE materials.

There are two basic ways that adhesion can be formed to a LSE substrate:

1. Increase the surface energy of a substrate through use of a surface treatment process. This can be a mechanical treatment such an Inline Corona Treatment or plasma or a chemical treatment. There are many chemical treatments commercially available today which will promote superior adhesion. There are a number of benefits to selecting a surface treatment. Perhaps the most significant is that it opens up the range of PSA’s that can be used in an application. The Design Engineer has greater freedom of choice to meet all of the requirements of the project including adhesion performance and cost considerations.

2. It is often not possible or unviable to apply a surface treatment in a manufacturing environment. In these cases, an LSE compatible adhesive, or LSE tape, needs to be selected to achieve the adhesion performance required. These PSA’s have additional polymers within their core construction which will increase adhesion to LSE substrates. These polymers are a mix of synthetic and natural resins. By their very nature rubber-based adhesives, whether hot-melt rubber or a solvent rubber have superior bond strength to LSE substrates. However, there are a number of limitations to a rubber adhesive which often exclude them from selection when choosing a bonding solution.

Benefits of Adhesive Tape for LSE Substrates

• Cleaner
• Quicker
• Lightweight
• No need for investment in machinery
• Eliminates structural weak points
• Spreads stress evenly
• Can withstand movement and vibration
• Invisible
• Economical

Typical Rubber PSA Characteristics

This leaves acrylic PSA technology to provide high performance bonding to LSE. However pure acrylic PSA in its natural state will not bond to LSE substrates without the aid of a surface treatment. To overcome this, special tackifier additives are blended with the pure acrylic PSA construction. There is always a compromise on the performance of pure acrylic as it will take on some of the characteristics of a rubber. However, a modified acrylic PSA will still offer significantly higher levels of performance than a rubber based PSA. Some of the characteristics of a pure acrylic and modified acrylic are as follows;

Typical pure acrylic PSA characteristics

 
Modified acrylic adhesives with carefully selected additives give the best of both acrylic and rubber adhesives, however not all modified acrylics will give high adhesion to LSE substrates. It is important to consult an Application Engineer before selecting.

Most common alternatives for bonding or fixing low surface energy plastics and other LSE materials are  mechanical fixings such as welds, rivets and screws or solvent welds. These traditional methods require investment in major equipment for labour intensive operations to be carried out, such as hole spotting, drilling, tapping welding and surface refinishing. These create structural weak points or areas were rust or corrosion can set in.

Solvent welds rely on hazardous solvents which require specialist equipment for dealing with fumes and health and safety requirements.

Tecman has a range of PSA tapes for bonding LSE substrates, including transfer adhesives, film tapes and 3M™ LSE tapes. Tecman’s Application Engineers regularly specify adhesive tape for bonding LSE substrates as they are fast becoming the preferred choice for design and engineering projects due to the demand for cleaner, quicker and more cost-effective solutions.

Contact us

For more information about our range of LSE tapes, please contact our technical sales team on +44 (0)1926 337 466 or request a consultation.

Request a consultation