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

2. 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 mm thick [Scott Bader Crystic Polyester Handbook]

3. 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

4. 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”

5. 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 A

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

7. 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

8. 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.

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

10. 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

11. 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 for styrene referenced to the isobutylene (C4H8, CAS ) calibration below 3000 ppm at 20°C and 90% RH
gel-coat pull-off adhesion strength
EN ISO 4624:2002 standard procedures

12. 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

13. 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

14. Pull-off adhesion tests
EN ISO 4624:2002

15. 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 MPa
failure for IMGC occurs at separator layer interfaces:

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

17. 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

18. 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/ ] [FP7/ ]) under
grant agreement number FP7-SME

19.  Thank you for your attention
any questions ?