In-mould gel-coating with a separator layer Zoltán Gombos and John Summerscales Plymouth University, UK

Gel-coat Many applications require a separate surface finish for cosmetic and/or durability reasons. This coating, known as the gel-coat, is normally applied to the mould tool before the structural laminate is moulded. Gel coats should be 0.5-0.6 mm thick [Scott Bader Crystic Polyester Handbook]

Gel-coat application by hand-painting or spray onto the open mould. The process releases volatile organic compounds (VOC) into the workplace and the environment. by mould-opening and flow into the space horizontal surfaces increase by the required distance vertical surfaces see no increase in space

Drivers Styrene Producers Association has recently recommended implementing a 20ppm limit that ensures employee safety. “ultra-low styrene content spray gelcoat” reported to have achieved an average styrene concentration of 22.3 ppm relative to 54.3 ppm for a “standard gelcoat”

New in-mould process applicable to RTM, RIFT and similar processes mould cavity divided by a separator layer separator has texture to provide stand-off from mould surface enhance physical bond to laminate and gel-coat IPR published as British Patent GB 2 432 336A

IMGC concept as for RTM, but with two injection ports:

Trilaminate separator layer two textiles faces bonded either side of an impermeable membrane textile provides: keying to laminate defined space for gel-coat membrane: separates two resin systems

Reference cases for IMGC Hand-Painted Gel-Coat (HPGC) In-Mould Surfacing (IMS) Removable silicone shim AR Harper, Production of composite mouldings Patent WO2013/132211A1, 12 September 2013.

Processes flat plates double opposed tetrahedron mould simulated resin transfer moulding (RTM) between two glass plates with central injection points double opposed tetrahedron mould

Materials used AHCL Alan Harper Composites Limited, Saltash, United Kingdom. Ccot Centro Tessile Cotoniero E Abbigliamento SpA, Busto Arsizio, Italy. DeIJ De IJssel Coatings BV, Moordrecht, The Netherlands. DSM DSM (formerly Dutch State Mines), Heerlen, The Netherlands. SB Scott Bader, Wellingborough, United Kingdom. SGV Saint Gobain Vetrotex, Litomyšl, Czech Republic

Characterisation flow to complete fill aesthetic finish WaveScan Distinctness of Image (DOI) instantaneous styrene vapour levels PhoCheck Tiger Photo-Ionisation Detector (PID) with a 10.6 eV lamp set at 0.349 for styrene referenced to the isobutylene (C4H8, CAS 115-11-7) calibration below 3000 ppm at 20°C and 90% RH gel-coat pull-off adhesion strength EN ISO 4624:2002 standard procedures

Aesthetic finish Mean DOI Dorigon RTM IMGC RIFT IMS HPGC flat plate 93.2 93.4 92.2 tetrahedron ~ 70.2 75.9 high DOI is good maximum DOI is 96

Styrene levels styrene level (ppm) flat tetra IMGC TWA 0.24 (-99.7%) N/A ceiling 36 (-96.5%) IMS 0.23 (-99.2%) 0.37 (-98.7%) 49 (-92.6%) 107 (-84.0%) HPGC 71 29 1017 668

Pull-off adhesion tests EN ISO 4624:2002

Pull-off adhesion strengths Strength (MPa) RTM IMGC RIFT IMS HPGC flat plate 7.8 23.7 27.9 tetrahedron ~ 13.4 16.1 target levels minimum 8 MPa ideally > 20 MPa typical industrial parts 16-20 MPa failure for IMGC occurs at separator layer interfaces:

Double tetrahedron mould tool Separator fabric will not conform to complex shape

Conclusions all processes capable for flat plates IMGC cannot (yet) handle complex shapes need more conformable separator layer need greater cohesion within separator layer closed mould gel-coating significantly reduces styrene levels

grant agreement number FP7-SME-2011-1-286520. Acknowledgements This research was funded by the European Union's Seventh Framework Programme managed by REA-Research Executive Agency ([FP7/2007-2013] [FP7/2007-2011]) under grant agreement number FP7-SME-2011-1-286520.

 Thank you for your attention any questions ?