Vinyl ester powder pre-preg
The invention provides a powder pre-preg comprising as sole resin a vinyl ester resin having a Tg in the range of −5 to +30° C. and a melt viscosity @100° C. in the range of 2 to 75 dPa·s, which can be used in making a composite at a temperature as low as 80° C.
1. Powder pre-preg comprising as sole resin a vinyl ester resin free of reactive diluents and monomers, where the resin has a Tg in the range of −5 to +30° C. and a melt viscosity at 100° C. in the range of 2 to 75 dPa·s.
2. Powder pre-preg according to claim 1 , wherein the vinyl ester resin has a Tg in the range of +5 to +25° C.
3. Powder pre-preg according to claim 1 , wherein the vinyl ester resin has a melt viscosity at 100° C. in the range of 10 to 25 dPa·s.
4. Powder pre-preg according to claim 1 , comprising one or more cure initiators having a 1 hour half-life temperature below 100° C.
5. Powder pre-preg according to claim 1 , comprising one or more additives selected from the group of fillers, surface modifiers, pigment, fire retardants, intumescent additives, and mixtures thereof.
6. Powder pre-preg according to claim 1 , comprising fibres selected from the group consisting of loose fibres, non-woven fabrics and woven fabrics.
7. Process for preparing a powder pre-preg according to claim 1 , comprising a fixing step which consists of heating at a temperature in the range of 70-100° C.
8. Process for preparing a powder pre-preg according to claim 7 , wherein the powder used would have 80% by volume of particles between 20 and 100 um, and 99% between 0.5 and 100 um.
9. Process for preparing a powder pre-preg according to claim 7 , wherein the heating is for a duration of 3 to 7 minutes.
10. Process for preparing a powder pre-preg according to claim 7 , wherein the temperature range is 70-95° C.
11. Process for preparing a powder pre-preg according to claim 7 , wherein the temperature range is 70-90° C.
12. Process for preparing a composite from a powder pre-preg according to claim 1 , comprising placing the pre-preg in a mould and heating the pre-preg, wherein the heating step consists of heating at a temperature in the range of 70-120° C.
13. Process for preparing a powder pre-preg according to claim 12 , wherein the heating is at a temperature in the range of 75-100° C.
14. Process for preparing a powder pre-preg according to claim 12 , wherein the heating is at a temperature in the range of 80-90° C.
15. Powder pre-preg according to claim 1 , wherein the vinyl ester resin has a Tg in the range of +10 to +20° C.
16. Powder pre-preg according to claim 1 , comprising one or more cure initiators having a 1 hour half-life temperature below 85° C.
17. Powder pre-preg according to claim 1 , comprising one or more cure initiators having a 1 hour half-life temperature below 70° C.
18. Powder pre-preg according to claim 1 , one or more cure initiators selected from organic peroxides.