Within the context of REACH all boron compounds were classified as SVHC-substances (Substances of Very High Concern) on June 20th, 2011. This is applicable for a contents as of 0,1 %, whereas boron compounds, as reprotoxic, have to be classified as category two, R 60 and R 61 and marked with a skull and crossbones symbol.
For the use of alternative substances Emsland Group did a significant step after intensive research work with the development of Emdex 1480 and Emdex 1750. In collaboration with BK Giulini, who introduced the substitute Gilunal A at the end of 2011, a dextrin-based glue system came into existence. For this purpose various dextrins were tested regarding compatibility and stability with Gilunal A. On basis of these results several studies were carried through in terms of Open Time and adhesion speed of different glue mixes (see table).
Systems with high solids content (approx. 53 %) were examined in a targeted manner and the viscosity was measured at different glue temperatures. The measurements of Open Time/initial gluing till complete gluing were carried through at a temperature of 20°C. Based on the results, Emdex 1480 with a share of 7 % of Gilunal A was favoured for further application tests.
During the practical tests at Herbster Hülsen in Schopfheim the formulation of EMDEX 1480, Gilunal A and mineral fillers proved to be superior in view of technically and economically aspects compared with the former borax-containing mixes.
Only 7 % of Gilunal A were necessary to achieve an optimal gluing of the cores. Initial gluing, wet adhesion time, setting time and quick drying process match well with the fast production process and allow for high final strength values and dimension stability. Furthermore additives in the mixes provide optimum flow properties and a high solids content of the dextrin glue.
For Herbster Hülsen the requirements for the glue are fulfilled. For the gluing process the former requirements regarding gluing properties, film hardness, heat resistance as well as increasing emphasis on environmental impacts continue to play an important rule.
The dextrins produced by Emsland Group are 100 % based on renewable raw materials. Dextrins are listed in Annexe IV of the REACH-Regulation and thus do not require a further registration. They are also admitted for the food industry.
For the core production usually soluble glass, dispersion adhesives and increasingly adhesives on a starch basis like Emdex 1480 are being used. When using dextrin glues, the finished products prove to be superior in terms of higher strengths and dimensional stability. Furthermore high solids concentrations and short setting times of glues can be realised with dextrins as shown in this mutual project. With the borax free adhesive formulation on the basis of Emdex 1480 and Emdex 1750 as well as Gilunal A, Herbster Hülsen feels moving closer to the goal of achieving greater added value and more sustainability by using renewable and harmless raw materials.
For both Emdex 1480 and Emdex 1750 Emsland Group offers ready to use blends in liquid form. For an individual guidance our sales team supports your requests.
Telefon: +49 (0) 5943/81-354
Mobil: +49 (0) 172-5308514