3M™ VHB™ - How to Select the Right Alternative to 3M VHB 4941 Series Tapes

Many companies are still digesting the news that they will likely be required to transition to new acrylic foam tape alternatives from the trusted 3M VHB tapes they have used for years. The VHB 4941 Series, the VHB RP Series Tapes, along with several market specific VHB tapes are affected by a Force Majeure. These widely used VHB acrylic foam tapes will soon be in short supply. Fortunately, there are a number of alternatives that are available. However, before making a switch, it is important to consider a number of factors to ensure you are choosing the right tape for your application.

First, to avoid any confusion, it is important that we define terms. 3M VHB Tapes are acrylic foam tapes. 3M invented the acrylic foam tape category back in the late 1970’s and designated their tapes by the trade name VHB. People often use the term “VHB” or sometimes “very high bond” to describe the category. We’ll properly use the term VHB to refer to 3M’s brand of acrylic foam tapes and refer to products in the category as the generic, acrylic foam tape. 

If you are using a 3M VHB Tape affected by the Force Majeure, the good news is you’ve already specified and use acrylic foam tape. So, you know that the right acrylic foam tape will work for your job. The trick now is to find the right alternative. Acrylic foam tape is typically constructed with a thin pressure sensitive adhesive laminated to an acrylic foam core with a release liner. The thin adhesive, the foam core, and the liner are designed for specific application requirements. When selecting the right replacement it is important to consider the surface adhesive, the closed cell foam core, and the tape thickness. Differences in any of these variables can affect application performance.    

Pressure Sensitive Adhesive Skins

Modifications in the adhesive layer will change adhesion performance as substrates change. The VHB 4941 Series Tapes and VHB RP Series Tapes use adhesive skins designed to bond well to the most common surfaces like high surface energy materials (like metals), medium surface energy plastics (like polystyrene and ABS) and many painted surfaces. Fortunately, there are several 3M products whose adhesive skins bond as well to these substrates and are unaffected by the Force Majeure. The VHB GPH Series Tapes were designed to bond well to high and medium surface energy substrates without the use of primers. Other global tape manufacturers like Tesa, Avery Dennison, and St. Gobain also have developed acrylic foam tapes which bond well to high and medium surface energy plastics. The VHB 5952 Series Tapes were designed to bond well to high and medium surface energy substrates and the more difficult to adhere powder coated paint surfaces. As the name suggests, the LSE VHB Series products should bond well to most surfaces without the use of primers including low surface energy plastics like polyethylene and polypropylene.   

Acrylic Foam Core

As the inventor of acrylic foam tapes, 3M has long been the leader in the acrylic foam core technology. Acrylic foam tapes are terrific at absorbing dynamic loads because of the viscoelastic nature of the foam core.  3M has developed different core types which provide various benefits. The first generation of VHB Tapes 3M invented, like the VHB 4950 Series Tapes, have very firm cores. While the construction provides high strength, the lack of conformability often can inhibit some surface wet out of the adhesive to substrate bond. Any gaps in contact between the tape and the substrate will reduce overall performance, since the bond isn’t able to leverage all of the tape core strength. With the goal of improving total surface wet out and broadening substrate adhesion, more conformable acrylic foam cores were developed. The foam core of the VHB 4941 Series Tapes, VHB RP Series Tapes, and the market focused VHB Tapes (CV Series, G Series, B Series) were developed to be more conformable while maintaining very high core strength. Increasing foam core conformability allows the adhesive wet out to dramatically improve on the substrate surface. Subsequently, the bond leverages a higher percentage of total tape strength and total performance improves. This excellent balance of strength and conformability is the reason the VHB 4941 Series Tapes are the most widely used acrylic foam tapes today. 

Fortunately, 3M has continued to innovate in acrylic foam tape technology. The VHB GPH Series tapes, were developed targeting a blend of conformability and strength, while leveraging other technological advances. Testing by 3M seems to confirm that the VHB GPH tape core provides outstanding dynamic load absorption in applications where vibration and wind loads are high. At the same time, these tapes also have best in class high temperature resistance capabilities. While a relative newcomer, the VHB GPH Series Tape core appears to be a very strong candidate for applications in the commercial vehicle, signage, and architectural panel markets.  More conformable still, the VHB 5952 Series Tapes and VHB LSE Series Tapes have soft foam cores. This helps to optimize bonds on textured surfaces like powder coated metals and ensures very high surface wet out to maximize bond strength on more challenging to adhere surfaces. These foam cores however, are unable to withstand the degree of dynamic stress loads of the VHB 4941 Series Tapes. So, while they are perfect for many applications in markets like appliance, office furniture, and electronics, they may not be ideal where consistently high dynamic loads are present. 

Tape Thickness

Core thickness is always a critical factor in ensuring an optimal bond. The thicker the tape visa vis the bonded substrates, the more surface adhesive wet out you can expect. At the same time, using too thick of tape can also reduce bond performance. It is wise to follow the Goldilocks approach when it comes to tape thickness. The typical rule of thumb is the acrylic foam tape should be about 50% of the thickness of the thinnest bonded substrate. So, for example, if you are bonding a 18 gauge painted aluminum panel to an 1/8” thick steel frame, you’d start with at least a 25 mil thick tape. If you are moving to an acrylic foam tape with a firmer core, it is possible to offset some of the surface adhesive wet out challenges by using slightly thicker tape. 

When we look at the acrylic foam tape products from other major tape companies like Tesa, St. Gobain, and Avery, the most common construction we see is higher tack acrylic adhesives laminated to firm acrylic foam core technology. The adhesive skins provide the benefit of adhering to a broad range of substrates, while the firm acrylic foam core will lower the adhesive skin surface wet out. Recently, more conformable foam core solutions have launched. In any case, these products can provide good acrylic foam tape solutions that perform well in many applications. 

In conclusion, there are still many available options from 3M and others, you may choose as alternatives to your supply constrained VHB tape. The VHB GPH Series products should be a strong fit for many applications, yet, as a newer offering, it may not be available for all of your thickness, color, or liner needs. Next, the VHB 5952 Series tapes come in a wide range of thicknesses, liner options, and is available in white or black. But, the foam core may not be strong enough for all high stress applications and overall pricing can be significantly higher than other acrylic foam tapes. Lastly, acrylic foam tapes from other major tape manufacturers have evolved to fill many of the gaps in the currently available 3M product line and their affordable pricing will help improve your bottom line.

Given that you have already specified 3M VHB acrylic foam tape in your application and are now looking for an alternative to meet your needs, we’d suggest that you test two or three different acrylic foam tape products in your application to ensure that you find the right fit for you. Given the importance that acrylic foam tape plays in end products, it is critical to leverage unbiased experts you can trust to help guide you through tape selection and evaluation process. An expert will be able to understand your application and find the right solution that works for you!      

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