Core Winding Adhesives: Ensuring Tension and Strength in Winding Processes

semgeekseo
12 minutes ago
4 min read

In industries such as tissue, paper towel, packaging tube manufacturing, and specialty cores, the core winding step is critical. The adhesive used during core winding has a direct impact on the mechanical integrity, dimensional stability, and runnability of the finished rolls or tubes. Choosing the right adhesive and managing tension and strength effectively can make the difference between smooth production and costly defects. In this article, we explore how core winding adhesives function, what properties are essential, and how to ensure optimal performance in high-speed winding settings.

What Is Core Winding?

Core winding is the process of forming a rigid tube (or core) around which other material, such as tissue, paper, film, or packaging, is wound. In a typical tissue or paper roll line, the web material is affixed to a core, and subsequent layers are wound tightly in a roll. The adhesive must bond each successive wrap to the core and maintain this bond under tension, both during winding and during downstream handling or storage.

There are two common winding techniques:

Spiral (spiral-wrapped) winding, where the core is built by spirally wrapping a strip of material.
Convolute (or longitudinal) winding, where sheets are wrapped in an axial direction.

Regardless of method, the adhesive must accommodate the mechanical demands of winding at various speeds and under varying tension.

Key Requirements of Core Winding Adhesives

To perform well in a core winding application, adhesives must satisfy several critical criteria:

High initial tack (“wet tack”)
When a new layer is applied, the bond must form quickly so that the wrap does not slip. Rapid tack is important especially as layers are under tension.
Fast setting or cure
The adhesive should develop strength quickly so that subsequent winding or handling does not disturb the bond. Slow curing adhesives can allow slippage or delamination under high tension.
Sufficient green strength and final strength
Green strength refers to the initial strength of the bond before full curing. A strong green bond prevents movement during processing. Over time, the adhesive should reach a higher ultimate bond strength to ensure structural integrity.
Good compatibility with substrates and coatings
The adhesive must bond reliably with the core substrate (often paperboard, kraft, or laminated paper) and must tolerate surface coatings, inks, or barrier layers.
Dimensional stability and rigidity
Especially in tubes or cores, the adhesive must help maintain roundness, resist crushing or ovalizing forces, and prevent warping under load. Manufacturers often look for adhesives with high crush and stiffness values.
Machinability and process compatibility
The adhesive must be compatible with the equipment (wheel, slot die, roller, cascade coater, blade metering) and not cause clogging, skinning, or excessive maintenance.
Environmental resilience
The bond must hold under temperature/humidity changes, and sometimes moisture or chemical exposure in end use.
Cost, waste, and ease of handling
A practical adhesive must be economical, easy to dispense and clean, and not generate excessive waste or byproducts.

How Adhesive Choice Affects Tension and Strength

Because winding inherently applies tension across the layers, the adhesive must resist shear and peel forces. If the adhesive bond is weak, the layers may slip or separate under tension, compromising roll integrity. Some key aspects to manage tension and strength include:

Optimizing adhesive solids and viscosity
A higher solids content often improves film strength, but too high a viscosity may hinder application and wetting. Many core adhesives are in the range of 1,000 to 5,000 cPs (centipoise) depending on speed.
Formulation additives
Resins, flexibilizers, tackifiers, and rheology modifiers can be inserted to tailor bond strength and flexibility under load.
Controlling application thickness and uniformity
Uneven glue lines lead to weak spots. Consistent adhesive application helps resist delamination under stress.
Layer sequencing and dwell times
The time between glue application and wrapping (dwell time) must be controlled so that the adhesive is in the right tack window when bonding.
Preload tension and nip pressure
Apply enough mechanical pressure when bonding to ensure full contact, but without crushing or distorting the core.
Testing under dynamic loads
Adhesive performance should be tested under simulated winding tension, peel, and shear to confirm durability.

Types of Core Winding Adhesives

Several adhesive technologies are commonly used in core winding:

Waterborne emulsions (PVAc, polyvinyl, resin emulsions)
These are popular because of ease of handling, cleanup, and tuneability. Many formulations offer a balance of tack, open time, and final bond strength.
Hot-melt adhesives
Useful in high-speed or high-temperature applications where rapid bond formation is critical.
Dextrin or starch-based adhesives
Used often for cost-sensitive or paper-based cores where biodegradability or simpler formulations are acceptable.
Resin-enhanced or modified adhesives
These may contain additional resins or crosslinkers to boost bond strength, stiffness, or environmental durability.

Practical Tips for Ensuring Tension and Strength in Production

Pilot test adhesives under real winding tension
Lab tests are useful but real-world conditions (speed, humidity, temperature, mechanical stress) often reveal issues.
Monitor adhesion during startup and roll changes
Frequent checks of bond integrity, peel strength, and slippage help catch problems early.
Optimize dwell time and nip configurations
Ensure the adhesive is properly “activated” before the layer is applied, and that pressure is applied precisely.
Maintain consistent coating systems
Avoid nozzle clogging, leakage, or starved glue lines, which lead to weak spots.
Maintain substrate cleanliness and preparation
Dust, fibers, or surface irregularities degrade adhesion. Pre-treatment or priming may help.
Account for thermal and moisture cycles
If the environment fluctuates, choose adhesives with proven resilience under those conditions.
Use statistical process control
Track adhesive usage, thickness, bond performance, and correlate with roll failures or customer defects.

Benefits of Well-Formulated Adhesive in Core Winding

When the adhesive system is properly selected and managed, manufacturers enjoy:

Higher throughput (fewer stoppages, fewer defects)
Lower waste (fewer out-of-spec rolls or rejected cores)
Stronger, more stable cores that resist collapse or warping
Better customer satisfaction and reduced returns
Lower maintenance and adhesive system downtime

Ultimately, the core winding adhesive is a small but absolutely critical component in the overall success of converting and winding operations.

Ready to elevate your winding operations with adhesives engineered for strength, precision, and reliability? Discover the full range of adhesive solutions

and technical support at Lanço Adhesives.