The Basics of Hot Melt Graveure (dot) Lamination
What is Hot Melt Graveure or “Dot” Lamination?

Hot Melt Graveure or “Dot” lamination uses an exact pattern of microscopic “dots” of adhesive on the surface of one web of material to bond that web to another web of material and form a composite. The materials joined can be the same material or entirely different types of materials, such as nonwovens, films, fabrics, or already made composites.

This is called a Graveure process because it is similar to the rotograveure printing process. In rotograveure, pictures, designs and words are engraved into the printing cylinder. The cylinder picks up ink as it rotates and deposits the ink on the paper web (for example) as the paper passes against the cylinder.

In the “Dot” or Hot Melt Graveure process, adhesive is in a heated trough until the right viscosity. As the rotating graveure roll contacts the trough, the cavities on the roll are filled with adhesive. A doctor blade seals the trough towards the engraved roll and cleans the surface of the latter, so that adhesive is only applied in the pattern of the engraving to the receiving web as it passes.

ILLUSTRATION 4

As the web passes between the graveure roll and a counter roll. The receiving web then contacts the mating web under appropriate temperature and pressure to form the composite.

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Why use Hot Melt Graveure or “Dot” Lamination instead of traditional or blanket-type lamination?
• Different materials with different physical characteristics, such as physical strength, permeability of liquids or gases, melt temperatures, etc. can be precisely bonded to form a high performance composite. • The “dot” bonding technique only closes permeable materials at those points. • Precision bonding can be defined to meet exact customer needs in terms of location, frequency, or pattern. • “Dot” Lamination is a high speed process.

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Lamination & the Creation of Composite Materials
Lamination is the process of joining two or more layers of the same or different material together to form a composite. The traditional means of lamination was to apply some combination of high temperature, pressure, and adhesive to form a bond. While effective for many situations, with today’s high performance materials, the value of the material and its special performance properties may be sacrificed using traditional methods. The materials can be crushed by too much pressure or degraded by excess temperature or smothered by a cover layer of adhesive.

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Selective & Exact Lamination – The Key Technology of Beckmann Converting
The goal of Beckmann Converting is to create composites that make maximum use of the performance characteristics of each layer of the composite by selectively and exactly bonding the layers into a composite using effective technologies that can be precisely controlled to give the right amount of bonding at exact points. Beckmann Converting’s key to success is the mastery of ultrasonic lamination and hot melt graveure (dot) lamination.

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The Basics of Ultrasonic Lamination
What is Ultrasonic Lamination?

Ultrasonic lamination uses the conversion of acoustic energy to heat to form spot welds of specific size in exact locations. This technique is an ideal method to join sheets of different or similar materials (nonwovens, films, composites, or fabrics) into a single composite or laminate.

The layers of raw material are arranged and brought together as in any traditional lamination process to pass over a central rotating roll or “anvil”.

ILLUSTRATION 1

Instead of the uniform smooth surface roll used for pressure bonding, Ultrasonic Laminating uses a pattern of dots on the anvil or “pattern” roll. Each dot is the site of an individual bond across all layers of the lamination.

NP OPEN DIAMOND

Accoustic energy is generated from a “horn”. Each horn is individually powered so that its output can be exactly tuned to a series of pulses. Each pulse is a pressure wave that acts as a tiny hammer, impacting the material over the dot tens of thousands of times per second.

The degree of bonding at each dot is determined by the nature of the material in the layers, the amount of energy applied from the horn, the size and shape of the dot, and the “dwell” time of the material in relation to the dot. The discrete bonding at specific points is an important feature of Ultrasonic Lamination, as it allows the unbonded materials to function as they were designed.

ILLUSTRATION 2

Ultrasonic Lamination is a non-contact and therefore non-wearing process. As the layers to be laminated move across the dwell area, the layers are not pulled or pressured onto the dots. For effective bonding, the layers actually need to relax as they dwell over the dot, so the conversion of acoustic energy to heat for bonding is not dissipated or wasted.

ILLUSTRATION 3

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Why use Ultrasonic Lamination instead of traditional or blanket-type lamination?
• Different materials with different physical characteristics, such as physical strength, permeability of liquids or gases, melt temperatures, etc. can be precisely bonded to form a high performance composite. • The point bonding of Ultrasonic Lamination only closes permeable materials at those points. • Correct applications can manufacture uniform composites without the degradation of the individual materials due to excess heat or pressure or chemical attack. • Precision bonding can be defined to meet exact customer needs in terms of location, frequency, or pattern. • Ultrasonic Lamination allows recycling of materials as no adhesive or chemicals are used in the process. • Ultrasonic Lamination is a high speed process … • Ultrasonic Lamination is a clean process that is ideal for health care, filtration, and other applications where potential contamination is a primary concern.

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