In order to gain a good understanding of this issue, we first need to consider the two ways of looking at the meaning of 'water resistance'. Each related to a specific aspect and has an impact on the final result of the product:
The ‘whitening’ procedure, which is caused by the incorporation of water molecules into the adhesive film (see Fig. 1 with a visible white color in a display window). This phenomenon represents a visual impairment and is of particular importance in visible applications such as the ‘no label look’ or graphic protection films or lamination films.
Water resistance depends on the bond strength of bonded adhesive tape when exposed to water or moisture. In many technical applications, it does not matter whether an adhesive film discolors. The bond strength between the bonded substrates is the decisive factor.
From the start we can be clear that the nature of the substrate to which the self-adhesive film is applied plays a decisive role. The substrate's physical properties, its surface roughness, porosity or polarity are significant factors affecting bond strength. When immersed in water it is possible for a polymer film to absorb up to 30% of its weight in water. For example, a top-coat applied to a film to make it receptive to inkjet printing readily absorbs humidity and water can easily penetrate the boundary layer betwee the self-adhesive film and the substrate. Notwithstanding, the challenge of 'water-resistance' as it relates to the bond strength of the adhesive is essentially the same, whether the adhesive system is water-based or solvent-based.
ATP is the perfect partner for your own development. We will support you at our R&D centre and offer you the option to carry out tests according your specifications.
| ATP old generation N/25 mm | ATP new generation N/25 mm | |
|---|---|---|
| Separation force on a polyamide film after ageing in water (24h) | 1.9 | 20.3 |
However, coming back to the issue of whitening, it is important first of all to understand the difference between a water-based adhesive system and one which is based on solvents. In both cases the adhesive consists of acrylate polymers or acrylate co-polymers produced with the monomers normally used in pressure-sensitive adhesives, e.g. butyl acrylate or 2-ethyl hexyl acrylate. Accordingly, the two types of adhesive system are not different in this respect. It is argued, therefore, that the difference lies in the additives or, more precisely, the surfactants that are essential for the production of water-based dispersions.
These surfactants are auxiliary substances that help to blend and stabilise two components such as water and oil that are not miscible. However, having investigated this issue over the last two years, we have concluded that the quality of the film and the coating process have a much bigger influence on the ‘whitening’ behaviour of a pressure sensitive film than do surfactants. So at ATP we have leveraged this understanding and worked with our raw material suppliers to develop pressure-sensitive films that can match the performance of solvent-based adhesive systems in terms of water whitening.
Indeed this development of high bond strength water-based adhesive systems with excellent whitening behaviour continues apace. We now have water-based adhesive systems, which even after being immersed in water for several days exhibit no visual impairment or any loss of adhesive force. These systems have been applied to products for the graphics industry such as overlaminates requiring water-resistance, particularly when used for outdoor applications.
The pictures show our adhesive systems after being fully immersed in water for a total of 24 hours. Whilst the two adhesives on the left show both whitening and a loss of adhesion, our new adhesive development on the right exhibits neither whitening nor loss of adhesive force.
- To protect health and the environment against the risks posed by chemical substances
- To develop alternative methods to test the hazardousness of substances
- To guarantee the free movement of affected products within the EU.
In order to achieve this, products are classified into one of the following groups:
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Every protagonist has to ensure the flow of information about the secure handling of a product at the joint to the following player. To reach the targets protection of the human health and environment substances of very high concern (SVHC) are identified and listed in the so called candidate list. This schedule is constantly updated. Mentioned substances are not deleted from the candidate list and normally will be transferred to Annex XIV of substances subject to authorization.
And now it becomes interesting because there exist measures which can cause pressure sensitivity:
- punishment of offence against the REACH-regulation (large monetary fines or imprisonment, dependent on the offence)
- substances which are mentioned in the candidate list and used from an user more than 1t/a should be notified to the ECHA
- or the first time the consumer has the right to be informed about SVHC´s in the article he bought. According to Article 33 (2) the consumer has to be informed within 45 days after request if a SVHC is contained in an article.
ATP presents a range of new, low‑emission adhesive systems for use in the following automotive interior applications:
- Soundproofing and insulation
- Sealing
- Electronic sensors and components
- Decorative interior trims
- Door interior trims
- Roof headliners
Every protagonist has to ensure the flow of information about the secure handling of a product at the joint to the following player. To reach the targets protection of the human health and environment substances of very high concern (SVHC) are identified and listed in the so called candidate list. This schedule is constantly updated. Mentioned substances are not deleted from the candidate list and normally will be transferred to Annex XIV of substances subject to authorization.
Typical substrates bonded by ATP’s adhesives include:
- Plastics including, ABS, PC, PP, PE, PVC.
- Metals, and painted and powder- coated substrates
- Textiles and fabrics Produkte innerhalb der EU
- Foam substrates including, PU, PE, PVC, PVC/Nitrile, EPDM, Neoprene.
Furthermore ATP announced July 2014 a significant new investment of approx. €20 million for their production facility in Mihla / Buchenau, this investment includes the construction of a production and warehousing facility with a new 12’000m² building together with 860 m² office complex. The central focus point of the new factory will be the new 70 m long, state-of-the-art coating line with clean-air manufacturing allowing ATP to offer adhesive tapes with exceptionally high quality optical appearance. Managing Director Daniel Heini explained ‘the new production facility will create between 50-60 new jobs for highly trained staff, in addition ATP will continue offering training places for job-starters.’ Every year the company offers school leavers training places in various departments such as laboratory, engineering, warehouse, logistics and in sales and service.