Sustainably manufactured adhesives and efficient processing for box spring beds, foam mattresses and pocket innerspring mattresses
Mattresses have become part of a person’s lifestyle. When choosing the suitable mattress, consumers are influenced by the latest trends, for instance box spring beds. A healthy and restful sleep has also moved up on the priority list of consumers. Therefore, a new bed is no longer expected to last a lifetime. Trends that were previously known only from fashion now play an important role in the decision of customers which mattress to buy. Private consumers and the trade sector expect products with properties similar to those of sports clothing: a soft touch, breathability, washing and sterilisation resistance, plus high resistance to heat and mechanical stress.
Increasing requirements in mattress manufacturing
Mattresses and especially box spring beds are manufactured in a wide variety of material combinations and qualities, which require very versatile manufacturing processes. Since these products are assembled either totally or partially by hand, the process cycles vary very much and put high demands on the adhesive technology. In addition, different mattress designs (structure, size, hardness) are often produced on the same unit or line. To avoid any unwanted refitting due to adhesive change, the adhesive has to provide the necessary range of characteristics to be suitable for all these applications.
Adhesives and comfort
The high diversity in materials and the increased requirements must be taken into account when choosing a suitable adhesive for mattresses. The adhesive has to meet high demands due to a wide range of applications from the individual manufacturing processes of the different designs: laminating and coating of mattress upholstery fabrics, laminating of textile compounds, bonding of pocket and barrel innerspring mattresses, mattress assembly, and, of course, foam laminating.
Thermoplastic and reactive hot melt adhesives for mattress manufacturing
The longer open time of pressure-sensitive hot melts, dispersions and solvent-based adhesives has made this products for a long time the number one choice in mattress manufacturing.
However, pressure-sensitive hot melt adhesives provide only a limited heat resistance and bondings may fail during transport, especially when they are shipped overseas in containers where temperatures of 80 °C and more are possible. In addition, melting units have to be cleaned and filters changed more often due to the low thermal stability of these products.
Dispersion adhesives, on the other hand, need sufficient time to dry and to build up strength. Therefore, an intermediate storage period is required after application, before downline processing can continue. At the end of the manufacturing process, the mattresses have to be stored for another 48 hours before packaging. This is necessary to allow the trapped water from the dispersion to evaporate. Otherwise, the metal springs in airtight shrink-wrapping may corrode and it mould may form.
Due to continuously rationalised processes and increasing line speeds, the above-mentioned adhesive groups are now being replaced by more powerful thermoplastic and reactive hot melt systems. The new adhesives are all-rounders and very versatile. Therefore, no refitting is required to bond different materials and the fast build-up of strength facilitates faster process cycles.
PO and PUR systems can handle high tensions and restoring forces even in short pressing cycles and are therefore ideal for manufacturing pocket innerspring mattresses. Among other benefits provided by these adhesives, (pocket) innerspring mattresses may be packed directly after pressing in roll packs without the risk of any movement in the bondline. Only hot melts provide the necessary bond strength to ensure that the mattress lays flat after unpacking; dispersions do not meet these requirements.
In foam lamination, especially soft, elastic hot melts impress with an increased overall comfort. Due to high resistance to mechanical stress, hot melts are extremely durable, meeting the necessary standards to facilitate warranties of up to ten or fifteen years by some mattress manufacturers.
In mattress manufacturing, hot melt adhesives provide more efficient processes and superior products.
In addition to ensuring an increased comfort of the end product and being suitable for different mattress designs, hot melts also impress with the positive characteristics regarding safe working conditions and the protection of the environment and health – in production as well as in use. Hot melts are adhesive systems with a solids content of 100 %. Therefore, emissions are much lower than of solvent-based adhesives, which are still widely used in mattress manufacturing. In general, PO and PUR hot melts are made of the same polymer group as the foams in mattresses. Therefore, the mattress can be recycled together without separate disposal.
Superior processing characteristics of thermoplastic Jowatherm® and reactive Jowatherm-Reaktant® adhesives meet the different requirements of the entire manufacturing chain of box spring beds and mattresses regarding processing efficiency, health protection, safety and comfort.
The professional article is published in the journal ‚Möbelfertigung 1|2016‘ in German language. You can download the original article down below.