Ketjenflex® 9S, a grade of specialty sulfonamide flexibilizer from France-based Axcentive, has long been known as an additive for melamine-resin formulations used in the manufacture of decorative laminates. A melamine resin manufacturer typically sources melamine (or an alternative amino resin) to polymerise with formaldehyde and various additives which enhance flexibility, toughness, flow, resin stability or just to cut cost. Reactions are done in kettles at elevated temperatures. At the impregnation stage – which can be integrated or independent – decorative papers are soaked in a bath of melamine resin to make the final laminate product. In the case of low-pressure laminate (LPL) this is the only step before pressing onto board at 20-30 bars. In the case of HPL, decorative papers are pressed along with phenolic-resin-impregnated Kraft papers, all together in the melamine resin bath at 70-80 bars. Laminate sheets can be sold separately (4a) for downstream lamination onto various substrates, or by the manufacturer as a final laminated product (4b) such as flooring panels or kitchen worktops.
At the impregnation stage, firms can use external modifiers such as glycols (DEG, TEG), alcohols such as sorbitol, and even sugars. These nonreactive additives are essentially processing aids, facilitating impregnation of the paper and reducing water retention during drying. They are generally less efficient in stabilising and flexibilizing the resin matrix than internal modifiers. Because they make the resin network softer without binding to it, external plasticizers may also be associated with detrimental effects such as reduced water and steam resistance.
Earlier on at the resin synthesis stage, firms can incorporate internal plasticizers including caprolactam, benzoguanamine, urea – or Ketjenflex® 9S. All these products fully bond to the polymer matrix, thereby altering its structure in a way that makes it more flexible and resilient. The advantage of Ketjenflex® 9S at this stage is in toughness, moisture resistance and superior post-formability, which is desirable by fabricators who would like to mould the laminate into sharp angles and tight radii around a shaped surface or substrate, to offer consumers an effect which more closely resembles solid surface or real stone.
Naturally, many formulators choose to employ both internal and external plasticizers which fulfil these different roles. So, Axcentive recently created a new modelling tool based on their long experience, to model alternative formulations for specific customers including various proportions of internal and external plasticiser to optimise the balance of the two types of additive, and secondly to observe the differences in performance between different primary (external) plasticizers.
As a branded specialty additive, Ketjenflex® 9S offers high performance but also makes economic sense. Through modelling of various formulations, Axcentive has demonstrated that with the right combination of plasticizers, Ketjenflex® 9S can successfully replace caprolactam and benzoguanamines at a lower addition rate, resulting in a formulation which is entirely cost competitive. Trials of this formulation by new customers during Spring 2015 validated the performance of the formulation and the superior properties of the resulting laminate compared to the (caprolactam-based) control.
The development team at Axcentive went further in breaking new ground. Toby Heppenstall, General Manager at Axcentive, explains.
“Since looking more closely at the chemistry in 2014 we had suspected that Ketjenflex® 9S should bring the same advantages to LPL resin formulations as HPL. LPL makers were telling us that the key thing they wanted to achieve in the market was better post-formability to position more effectively against HPL. But no-one had really considered our technology. Once we put two and two together it was just a question of finding the right development partner.”
Axcentive’s distributor in Turkey, Eigenmann & Veronelli, were instrumental in finding that partner. Carlo Giubaldi, the General Manager of E&V Turkey picks up the story:
“We approached a major player in Turkey and through a joint assessment, learned that the customer’s main objectives were to enhance flexibility and gloss. Ketjenflex® 9S was trialled and validated as a new standard raw material which furthermore replaced more dangerous and less effective chemicals”.
Arno Schut, Technical Manager at Axcentive explained that understanding the customer’s reaction conditions and process was as important as coming up with the right guide formulation.
E&V’s Giubaldi concludes: “The Axcentive and E&V teams were both effective and creative in identifying and meeting the customer requirements in this case. We are proud of the success story that came of this fruitful partnership.”
Axcentive sells Ketjenflex® 9S globally. Current development activity with LPL is occurring mainly in Southern Europe and the Middle East but with both HPL and LPL markets expected to grow strongly worldwide in the next few years, prospects for sales in Asia, India and Latin America are also considered to be good.