Technology Zone
Bondtec
Bondtec covers the surface and bonding techniques that change what a textile can do. This zone covers plasma and chemical surface treatment, thermal, ultrasonic and adhesive bonding, lamination and the machinery behind them.
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Bondtec — page 1 of 1
What this zone covers
Bondtec: how it works, key numbers and troubleshooting
Fundamentals
Surface energy decides adhesion
Nothing sticks to a surface that will not wet. Polyolefins, polyester and most technical fibres have a surface energy too low for an adhesive to spread, so the first step is raising it: corona discharge for film and web, atmospheric plasma for three-dimensional and delicate substrates, low pressure plasma for the most demanding work, or a chemical primer. The treatment decays within hours to days, so bonding follows treatment closely or it does not work at all.
Thermal bonding and welding
Where the material is thermoplastic, the material itself becomes the adhesive. Hot air and hot wedge welding melt the surfaces and press them together, and they carry most tarpaulin and membrane seaming. Ultrasonic welding puts high frequency vibration into a small area, which is fast, clean and needs no consumable, and it is why hygiene and medical converting lines are full of ultrasonic horns. High frequency welding suits polar polymers such as PVC and polyurethane.
Adhesive bonding
Adhesives cover everything welding cannot: different polymers, non-melting fibres, and joints that need flexibility. Hot melt adhesives are applied as film, web, powder or spray and reactivate with heat, and they are what most laminating lines use. Reactive polyurethane hot melts crosslink after application with moisture and give far better heat and wash resistance. Solvent and water-based systems still hold their place where a very thin, uniform layer is needed.
Lamination
Laminating bonds two or more layers into one composite fabric: a face, a membrane and a backing, for instance. Flame lamination melts a foam layer and is fast and cheap but restricted by emissions rules. Adhesive lamination with a dot or web pattern preserves breathability and handle, and the pattern coverage is the setting that trades bond strength against drape. The bond must survive the wash cycles the product will see.
Testing the joint, not the material
A bonded assembly fails at the interface long before either material fails. That means peel strength, shear strength and, above all, the same tests after heat ageing, humidity and washing. A joint that peels at 60 newtons fresh and 15 after ten washes is a joint that will come back. Where the joint is safety relevant, destructive testing of production samples belongs in the routine, not in the qualification file only.
Key parameters
| Parameter | Typical range | Rule of thumb |
|---|---|---|
| Surface energy target | Above 38 dyne/cm, 44 and up for demanding bonds | Measure with test inks before bonding; do not assume the treater worked |
| Corona treatment decay | Effective for hours to a few days | Treat in line with bonding wherever possible |
| Ultrasonic frequency | 20, 30 or 35 kHz | Lower frequency for thicker material, higher for fine and delicate webs |
| Hot melt coat weight | 5 to 30 g/m2 for laminating | More adhesive means a stiffer, less breathable laminate, not a better one |
| Dot coverage | 10 to 30 % of the area | Coverage trades bond strength against handle and breathability |
| Welding temperature window | Within 10 to 20 degrees of the optimum | Establish a window by trial and peel test, then control the middle of it |
| Peel strength | 20 to 100 N/50 mm depending on construction | Specify after wash and heat ageing, not fresh |
| Reactive hot melt cure | 24 to 72 hours at ambient humidity | Do not test or ship before the crosslink has finished |
Troubleshooting
| Symptom | Likely causes | What to do |
|---|---|---|
| Laminate delaminates after washing | Adhesive not rated for the wash temperature, insufficient coat weight, or a reactive system tested before cure | Move to a reactive polyurethane hot melt, verify the cure time, and test after the full wash cycle count |
| Bond fails immediately at the interface | Surface energy too low, treatment decayed, or a silicone finish on the substrate | Measure with test inks, treat in line, and remove or ban silicone from the process |
| Ultrasonic weld cuts through the web | Amplitude or pressure too high, wrong anvil pattern, or dwell too long | Lower the amplitude, change the anvil pattern to spread the energy, and reduce dwell |
| Welded seam is strong but stiff and brittle | Overheating, too wide a weld, or a material welded outside its window | Establish the temperature window with peel tests and run in the middle, and narrow the weld where the design allows |
| Laminate is stiff and no longer breathes | Coat weight too high or dot coverage too great | Reduce coverage, use a finer dot pattern, and re-test breathability against the specification |
| Adhesive strikes through to the face | Coat weight too high, temperature too high at the nip, or an open face fabric | Lower the coat weight and nip temperature, and consider a web adhesive rather than a coating |
| Bond strength varies across the width | Uneven treatment, uneven adhesive application, or nip pressure not parallel | Profile the treatment and the nip across the width, and check roller wear |
Go deeper: news and case studies · frequently asked questions
Equipment Guide
Bondtec in the Equipment Guide
8 equipment types
Recommended manufacturers
H.B. Fuller Company
As the largest pureplay adhesives company in the world, H.B. Fuller's innovative, functional coatings, adhesives and sealants enhance the quality, safety and performance of products people use every day. Founded in 1887, our mission to Connect What Matters is brought to life by more than 7,100 global team members across more than 30 market segments in 150 countries.
Bemis Associates Inc.
US adhesives and specialty films company developing heat-activated bonding films, thermoplastic adhesive tapes, seam sealing tapes and embellishment films. Its bonding solutions replace or reinforce stitching in performance apparel, outerwear, footwear, automotive interiors and handbags, supported by Co-Lab application labs in the US, Europe and Asia.
tesa SE
As a multinational company, tesa develops innovative adhesive tapes and self-adhesive product solutions for various industries, commercial customers, and end consumers for more than 125 years. There are already more than 7,000 tesa adhesive solutions that help improve the work, products or lives of our customers. tesa is active in 100 countries.
Herrmann Ultraschalltechnik GmbH & Co. KG
Builds ultrasonic welding machines, generators, modules and tooling for joining without adhesives, screws or external heat. Machine lines include HiQ, ULTRACELL, ULTRASAFE and ULTRASAFE X, serving plastics, packaging, nonwovens, metals and battery applications. Runs a dedicated nonwovens laboratory for material and bonding analysis.
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Questions and answers
Frequently asked about bondtec
Weld or glue?
Weld where both materials are thermoplastic and compatible, because there is no consumable, no cure time and no third chemistry to fail. Glue where they are not: different polymers, non-melting fibres, or a joint that has to stay flexible. Welding also gives a cleaner product for medical and hygiene use, which is why ultrasonic converting dominates those lines.
Why does surface treatment stop working?
Because it is not permanent. Corona and plasma raise surface energy by oxidising the top molecular layers, and those layers reorganise over hours to days, faster when it is warm. Treat as close to bonding as the line allows, verify with test inks rather than assuming, and remember that a treated roll stored for a week is effectively untreated.
Which adhesive for a washable laminate?
A reactive polyurethane hot melt, in nearly all cases. It applies like a hot melt and then crosslinks with ambient moisture, which gives it the heat and wash resistance that a plain hot melt lacks. The catch is the cure time: 24 to 72 hours before it reaches full strength, so do not test or ship on the same day and expect the final numbers.
How much adhesive should a laminate have?
Less than instinct suggests. More adhesive gives a stiffer, less breathable laminate and does not reliably give a stronger bond, because the failure is usually at the interface rather than in the adhesive layer. Dot patterns at 10 to 30 percent coverage give the balance most products want, and a finer dot at the same coverage gives a softer result.
Can ultrasonic welding handle any fabric?
Any thermoplastic one, and the proportion matters: a blend with too much natural fibre will not weld because there is not enough polymer to fuse. Fabric weight, anvil pattern, amplitude and dwell all interact, and the usual failure is too much energy cutting through the web rather than too little. It is fast, clean and consumable-free where the material allows it.
How should I specify bond strength?
As peel strength in newtons per fifty millimetres, tested after the ageing the product will see: wash cycles, heat, humidity, or all three. A fresh peel value is easy to hit and tells you nothing about the third summer. For safety relevant joints, put destructive testing of production samples into the routine rather than relying on the original qualification.
Is flame lamination still used?
Less every year. It is fast and cheap and needs no adhesive, but it burns a layer of foam to make the bond, which brings emissions that are increasingly hard to permit, and it limits the materials to those that will flame laminate at all. Adhesive lamination with a dot pattern has taken over most of the work, with better control over handle and breathability.
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