This project will adapt a new coating technology to enhance surface protection of glass to increase strength and enabling light-weighting of flat and container glass products. UK glass production is an energy intensive industry consuming ~9TWh/yr, 70% of this energy is used to melt the glass in the furnace. Reducing the weight of glass products will reduce the energy required and CO2 produced during manufacture. Basic engineering formula demonstrate a direct correlation between glass strength and wall thickness; therefore increasing glass strength will enable product thickness to be reduced leading to associated weight savings. Being a brittle material, surface defects with dimensions in the order of microns can lead to catastrophic glass failure. Glass strength will be maximised through aligning coating formulation to surface flaws, maximising crack filling & pinning potential, minimising driving force for crack propagation. In demonstrating that the coating has the potential to strengthen glass and reduce weight of glass products by 10-15%, the project will show how the technology to reduce energy consumption by >1TWh and CO2 emissions by 250kT.

Glass containers are moulded at the ‘hot’ end (1050°C-1200°C) by an Individual Section machine (IS machine). Prior to annealing newly formed glass containers (600?C) are subjected to a Hot End Coating (HEC) of tin oxide using precursors such as MonoButyltin TriChloride (MBTC) or tin tetrachloride. The HEC film preserves the mechanical strength and scratch resistance of the glass, whilst increasing bond strength enabling enhanced adhesion of a Cold End Coating (CEC). After annealing a CEC of polyethylene emulsion (water-based wax) is applied as an atomisation spray. This coating renders the glass slippery, enabling fast scratch and damage-free movement through the inspection and filling conveyor lines. HEC’s are well documented for being corrosive, toxic in-life and environmentally damaging; however their usage has remained an industry standard since 1975. There are 292 glass manufacturing plants globally (excluding India and China) across 27 sizable companies; on average 125,000 containers are formed per minute from 1924 production lines. Graphoidal wishes to conduct a period of R&D to develop a pre-production prototype ‘onestep’ cold-end coating process, thereby eliminating the hazardous and expensive organotin HEC. The container glass industry is continually searching for solutions to drive down production costs. Substituting the use of organotins for siloxane based polymers will eliminate hot-end coating requirements and allow savings of up to 30% on current prices of organotins. Further, organotins enter the environment by air and have devastating effects on aquatic species. Exposure by inhalation from the air and ingestion from the soil has also been demonstrated to have a toxicological impact on terrestrial animals.