As described in the article “How Polyimide Tapes are Made“, tapes are composed of two distinct layers, each of which is critical to the properties of the final product. The first layer is the backing material, and whether this is polyimide film (the generic verison of DuPont’s Kapton), polyvinyl chloride (PVC), Polyethylene terephthalate (PET), or some other plastic, cloth or paper material, this layer is selected to provide half of the tape’s final properties. The other half is determined by the adhesive layer applied to this backing layer.
The Usual Suspects
Generally speaking, manufacturers use three different adhesive types in combination with the backing material to produce a final “tape” product. Though these adhesive types can be subdivided into subgroups, the main categories are as follows:
- Silicone
- Acrylic
- Rubber
Each of these adhesive types have advantages and disadvantages which make them more or less suitable for particular applications. Here we will draw the major lines outlining these differences.
Silicone adhesives
Silicones have been used to formulate adhesive products for decades due to their flexibility, temperature cycling resistance, chemical resistance, and wide range of possible material properties.
Silicone adhesives have the following general characteristics:
- High flexibility (low modulus) at sub-ambient temperature
- Consistent performance over wide temperature range (a reason they work so well with Polyimide Tapes)
- Excellent ageing and UV resistance (a reason they work so well in LED applications)
- High temperature resistance
- Good resistance to polar solvents
Compared to acrylic and rubber adhesives, they are significantly more expensive, but due to their excellent high temperature performance they are very well suited to splicing tapes, masking tapes and polyimide (Kapton) tapes.
Acrylic Adhesives
Acrylic adhesives can either be water-based (this is also referred to as emulsion or dispersion) or solvent-based. Water-based are slower drying compared to solvent-based systems but generally solvent-based acrylic systems have better resistance to other solvents, chemicals and water. Comparatively, water-based systems are less expensive than their solvent-based counter parts.
Acrylic adhesives are generally divided into two subgroups: Pure and Modified
Pure acrylic
Pure acrylic adhesives share the following characteristics:
- Reasonable adhesion to a wide range of substrates (see modified acrylics below)
- Good ageing, transmittance and UV resistance (a reason they are often used in fiberoptic applications
- Reasonable temperature resistance; between silicones (high resistance) and rubber (low resistance)
Pure acrylics have a lower tack (“stickyness when dry” for the layman) and less adhesion on hard-to-bond plastics such as high- and low-density polyethylene (HDPE & LDPE) and polypropylene (PP) than modified acrylic or rubber adhesives. Pure acrylic adhesives are mainly used on tapes whose applications are bonding, sealing or surface protection.
Modified acrylic
For all intents and purposes, modified acrylics have the same characteristics as pure acrylics, but have superior adhesion to the hard-to-bond-plastics mentioned above. Generally, these are more expensive than pure acrylics and are used for plastic bonding (including vinyl and linoleum), lamination and splicing.
Rubber Adhesives
Just from looking at the roll, it is very hard to tell what type of rubber is used on the tape. Look at the figure to the right, and this same picture can be used to describe every type of rubber-tape below. The key is to ask the supplier what type of rubber adhesive is used. Like acrylics, rubber adhesives can be divided into two subgroups: Natural and Synthetic
Natural rubber
These adhesive have higher tack (again “stickyness when dry” for the layman) than acrylic adhesives as well as higher shear strength but they have limited UV resistance. These are used in the cheapest tapes on the market, but have limited applications. Natural rubber adhesives are used in duct tapes, low-temperature masking tapes and surface protection tapes (think of the tape you get on your new fridge or stove).
Synthetic rubber
As the name implies, synthetic rubber is “formulated rubber” – think coming from the lab, not coming from the tree. Synthetic rubber can broken into three subgroups: Hot-melt, Solvent and Butyl rubber.
Hot-melt rubber
Hot-melt is a low-temperature melting plastic, which makes this adhesive have low temperature resistance. It also ages poorly (becoming brittle) and has low UV resistance. This rubber is used for low- to medium-duty carton sealing, low-temperature splicing as well as paper core starting applications.
Solvent rubber
Solvent-rubber based adhesives have better temperature and aging performance but still poor UV resistance. It is used for electrical and foam tapes.
Butyl rubber
Butyl rubber based tapes have excellent UV and aging resistance but lower mechanical strength. These tapes are used in foam tape applications and construction and plumbing applications such as pipe joints.
Visit www.caplinq.com to learn more about both our Polyimide films without adhesive, or our Polyimide tapes with acrylic or silicone adhesive. You can also contact us if you have further questions on the temperature resistance of polyimide tapes and films.
thanks very much for your sharing. i learn much
How I can identificate a rubber vs a acrylic adhesive, if I don’t have sofisticated equipment?
Thanks
Often smelling the tape can tell you also. Rubber tends to have a very sweet smell.
Can you help me in choosing the best type of adhesive to use in a tape that has to be pasted on a powder coated Alumnium enclosure. Operating temperature 130Deg c and max voltage 4kV.
Thanks.
For powder coating applications, as with other temporary bonding applications, there are three key factors to look for:
1 – Price is important since it is an intermediate step and does not have any value once the process is important. For these reasons, look for a a polyester instead of a polyimide. Polyester is good for intermittent (5 mins or so) at 180°C and are much less expensive than a polyimide film.
2 – No adhesive residue after removal. You didn’t apply the masking tape only to have it leave an adhesive layer after removal. For this reason, look for a low-adhesion bonding material.
3 – Backing thickness. For handling these materials, 1mil thickness may (but is not always) be too thin. You want to choose a thickness that meets your needs without going any thicker. Extra thickness means extra cost that you will just throw away once the process is complete.
CAPLINQ recommends three potential materials, listed in order of recommendation (links are to the products technical datasheets):
a) PET1.5A-ULA-RL: 1.5-mil polyester film backing with an ultra-low-adhesion pressure sensitive acrylic adhesive on a paper release liner. It is designed to be a temporary bonding or masking tape for use in a wide range of applications.
b) PET2SG: Difference with the one above is that it is not on a release liner, is 2mil thick (instead of 1.5mil) and uses a silicone adhesive. Designed for applications that need slightly higher adhesion and temperature resistance and do not want a release liner.
c) PET1S: Difference with first one is that it is only 1mil thick and uses silicone and no release liner.
I am looking for a masking tape. I need to mask an area for application of an epoxy – very sensitive to silicone. The application is at room temperature so high temp is not required. Which adhesive type would make for a better alternative – rubber or acrylic? I can see advantages to both, but would one or the other affect my epoxy like the silicone does?
Both acrylic adehsive and rubber woudl work, but the acrylic adhesive will work the best as it will also leave the least residue after removal.
Thank you for the speedy feedback. I appreciate it.
Could you help me list the disadvantages for each adhesive, specifically silicone. Is it really only the price that can be said is bad? Or is it more difficult to process or perhaps apply?
Thanks!
Silicone adhesive is almost always good. The biggest downside is that silicones can outgas under vacuum. In space applications, this outgassing can cause deposits in unwanted areas. Processing and application of silicone adhesives, is never a problem.
This post is very good. Thanks for putting it together. I have a much better understanding of the subject now.
Keep up the hard work.
Great post.
I tried to make PVC insulation/ electrical tape using hot melt but failed as I could not find a suitable Hot melt PSA(plasticizer resistant). Now I am ging to use liquid adhesive . Isthere any water based adhesive for Electrical tape? Or Am I left to choose between solvent acrylic and solvent rubbet based adhesive? Which one would you recommend?
Thanks in advance for your help
You really make it appear really easy together with your presentation however I find this matter to be really one thing that I
feel I’d by no means understand. It sort of
feels too complex and very large for me.
I’m looking forward to your next put up, I will attempt to get the hold of it!
Good morning! I have an individual project in science and my task is to create a stronger type of tape. Is there anything stronger than silicone?
Can you provide insight on what type of adhesive would outgas the least? This would be for basically a room temperature, and standard atmosphere condition. Sounds like Silicone is the worst, but what would be better rubber vs. acrylic based?
Hi, I am trying to fix an electronics dial that has a thin film flexible covering skin. This rubber “skin ” has torn. Will a silicone tape be as flexible as a silicone adhesive? Is silicone the best choice?
Thank you,
Lauri
hi could you please tell me what are the major types of acrylic adhesives and applications for the same.
I am looking for pvc insulation tape coating line and this post gives me a clue which kind of adhesive am going to use
Sir i am Nasar khan from Pakistan please tell me what types of Adhesive tapes is best for the boxes in which we pack the sweet because some time the hands of man who packing the sweet some oil deposit on their hands, due to which every tape do not make a good bond.
We supply the complete tapes, not just the adhesives themselves for these tapes. I think that a rubber adhesive would still be the best for food-related tapes.
Please call us to discuss your application in more detail.
I would expect that a rubber based adhesive would still have worse outgassing than an acrylic-based adhesive.
sir
we are looking for rubber based glue for making masking paper tape and surface protection tape
i read your post above and you have recommended natural rubber based glue for the same kindly can u offer TDS of names of few manufacturers of the same
thanking you for your help in advance
best regards
rajaish
What does “thermosetting” refer to when it is used to describe tape made with thermosetting silicone pressure-sensitive adhesive?
Best regards,
Richard
Richard, I don’t know exactly. Thermosetting means that its chemical process can no longer be reversed. In the same of pressure sensitive adhesive, I supposed that over the silicone hardens and it is no longer possible to remove without adhesive residue, but I’m not sure if that actually makes it thermosetting. I would argue that the silicone adhesive “dries”, but not necessarily thermosets after application.
Hi
Which tape would leave the least residue on a painted wooden surface after removing it 2 or 3 hours after putting it on?
Very interesting read! I got some hints from your powder coating reply!
I like a silicone adhesive (that will stick to the tape and not on my product – powder coated or painted metal), that can stick for years on expensive products and still leaves no residue. I like a low tack.
I am aware that PET is ideal, but I like something that is softer to manage curves better. Are there PVC/Vinyl tapes with silicone based adhesives? I need to plot some shapes with a cutter.
Hi. I just sent you a direct message but then noticed you are answering questions similar to mine here, so I thought I should post it here as well. I’m trying to figure out what would be the best tape for covering up part of an incandescent bulb (a Philips 45-Watt R20 Dimmable Spot Light). I would tape it between the base and where it flares out, to limit the light that shines through the fixture. I’m concerned about melting, of course, but also about odor. (This fixture is in the kitchen.) What do you think would be best? Thanks so much for any advice you can offer.
I honestly think you would be better off replacing the bulb for one with less lumens rather that cover it with a tape.