Which Bonding or Sealing Solution is Right for Your Process?

Technical advances in the hygiene, packaging and converting industries have led to a variety of options for the bonding, sealing and welding of nonwoven textiles, plastic packaging film and other materials. Understanding the benefits and drawbacks of each technology can help you make the right choice for your application. This article compares rotary and stationary ultrasonic with hot melt adhesive, thermal and compression welding solutions.

Each application has its own characteristics to consider when comparing these technologies.  This could include ease of deployment, composition of materials being bonded, consumer preferences for the end product, production cost, process control and sustainability.  Additionally, some applications must also consider FDA / USDA requirements, storage and heat tolerances of package contents, consumer preferences for re-opening a sealed package and cleanliness of the production area.

Key points of comparison shown in the table and addressed in more detail below include technical capability, quality of the bond, start up time and production speed, product damage, cost, process control, end user concerns and sustainability.

Ultrasonics

Technical Capability – Capability is impacted by composition of the materials being bonded. Ultrasonics is only applicable to certain plastics and nonwoven blends.

Quality of Bond – Excellent; providing all parameters are correct.

Start Up Time – Very short

Production Speed – Increases production line efficiency; can increase your process uptime while lowering your process waste, robust to process and web upsets such as substrate splices, elastic splices, machine stop/start events.

Product Damage – Minimal, no adhesive bleed-through, no heat damage

Cost – Ultrasonic technology carries a higher initial cost than the others, but makes up for it with savings on costly adhesive materials, complex adhesive delivery systems, labor and materials (it allows you to utilize lower cost nonwoven materials or film substrates).

Process Control – Enables customized aesthetics, Can utilize lighter weight elastic materials without compromising performance, and eliminates adhesive creep

End User Concerns – Improves product comfort and performance; maximizes elastic performance; maximizes fabric softness; eliminates the stiffening effect of adhesive; size, shape of gathers customizable

Sustainability – Lower energy cost than thermal solutions; cleaner technology than hot melt adhesive solutions.

 

Adhesives

Technical Capability – Adhesive processes offer the most substrate flexibility.

Quality of Bond – Usually very good; although there are some instances when the adhesive breaks down due to oils or temperature of the surrounding area.

Start Up Time – Process delay associated with system heat-up/cool-down cycles

Production Speed – Excellent speed capability

Product Damage – Negative product effects—stiffness, tackiness, bleed-through, blocking

Cost – Higher system energy costs; high cost of raw materials usage, storage, handling, and transportation

Process Control – Process delay to clean adhesives from process equipment due to overspray, bleed-through, etc.; spray limitations / challenges with high-speed, intermittent processes; waste issues because the lines are full of adhesive between startup and shut down events; safety concerns because of high temperature raw materials, applicators, hoses, pumps, and melters.

End User Concerns – Adhesives can cause stiffness and discomfort.

Sustainability – Adhesives are the least sustainable option listed mostly due to difficulties recycling complex chemicals.

 

Thermal Bonding

Technical Capability – Capability is impacted by material properties but often requires a sealant layer

Quality of Bond – Usually very good; although there are some instances when it causes degradation of material outside bond zone

Start Up Time – Process delay associated with system heat-up/cool-down cycles

Production Speed – External application of heat can reduce speed capability

Product Damage – Potential product damage due to over-exposure to heat

Cost – Higher system energy costs

Process Control – Safety considerations due to high temperature equipment

End User Concerns – Degradation of material, speed capabilities

Sustainability– More sustainable option than hot melt adhesive option due to the fact that there are no raw materials added to the process.

 

Compression / Pressure Welding

Technical Capability – Capability impacted by material properties

Quality of Bond – Dependent on speed of process

Start Up Time – Starts immediately, but getting up to speed can take time

Production Speed – Best when operating at high speed

Product Damage – Similar to ultrasonics, no heat damage, but could have adhesive bleed through when adhesive is added to the process

Cost – lowest per code; often requires grade specific parts

Process Control – Can be a high-wear process; Waste and variability due to speed-dependent attachment strengths—at times an added adhesive system is used to overcome these limitations

End User Concerns – Grade change flexibility

Sustainability – High, unless adhesives are required to enhance low speed capabilities.

Aurizon Ultrasonics manufactures rotary ultrasonic equipment used in various industries to bond, attach, emboss and laminate thermoplastic materials. Our rotary ultrasonic systems offer a number of features and benefits over hot melt adhesive applications and thermal bonding, such as material savings, energy savings, sustainability benefits and increased process speeds.

Read more about replacing heat or glue based processes with rotary ultrasonic technology in an industrial application.

Feel free to contact us with questions.

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