Process for preparing a fiber-reinforced composite material

Abstract

Process for the preparation of a fiber-reinforced composite material comprising the step of contacting (i) a radically curable resin, (ii) fibers with a total water content of 0.5-20 wt %, based on the total weight of fibers, (iii) at least one transition metal compound selected from manganese, iron, and copper compounds, and (iv) a peroxide.

Claims

1. A process for the preparation of a fibre-reinforced composite material comprising curing a radically curable resin by contacting (i) a radically curable resin, (ii) fibres with a total water content of 0.5-20 wt %, based on the total weight of fibres, (iii) at least one transition metal compound selected from the group consisting of salts and complexes of manganese, iron, and copper compounds, and (iv) a peroxide, wherein the resin is an unsaturated polyester resin, a vinyl ester resin, or a (meth)acrylate resin.

2. The process according to claim 1, wherein the fibres are natural fibres selected from the group consisting of flax, jute, kenaf, industrial hemp, flax, bamboo, and ramie.

3. The process according to claim 1, wherein the transition metal compound is a copper compound, an iron compound, or a combination thereof.

4. The process according to claim 1, wherein the peroxide is selected from the group consisting of organic hydroperoxides, ketone peroxides, peroxycarbonates, and peroxyesters.

5. The process according to claim 4, wherein the peroxide is a ketone peroxide.

6. The process according to claim 1, wherein the radically curable resin composition is prepared by adding the transition metal compound to the resin in the form of a solution comprising, apart from the transition metal compound, an alkali or alkaline earth metal compound, a phosphorous-containing compound, and/or a 1,3-diketone.

7. The process according to claim 1, wherein the transition metal compound is added to the resin in an amount of 1-75 mmol/kg resin.

Description

EXAMPLES

(1) The following materials were used in the examples below:

(2) TABLE-US-00001 Synolite 1967-X1 a non-preacceleratored DCPD polyester resin (ex DSM) Butanox? M50 methyl ethyl ketone peroxide with an active oxygen content of 8.9 wt % (50 wt % in dimethyl phthalate; ex AkzoNobel) Nouryact? CF32 a Fe-based accelerator solution ex AkzoNobel Accelerator NL49-P Cobalt(II) 2-ethylhexanoate, 1% Co, in solvent mixture (ex AkzoNobel) inhibitor NLD-20 2,6-di-tert-butyl-4-methylphenol-based inhibitor ex AkzoNobel non-woven flax as non-pretreated flax containing approx 9.3 wt % received water, after storage at a temperature of 13.9? C. at 71% relative humidity Dried non-woven flax flax dried in a halogen/hot air dryer for 1 hour at 105? C., resulting in a weight loss of 9.3 wt % compared to the flax as received wet non-woven flax flax saturated with water vapour containing approx. 14 wt % water after storage in a closed container at 20? C. and 100% RH for 96 hours.

(3) A closed vacuum injection mould of 30?50?0.4 cm was used to prepare test panels. Two pieces of non-woven flax of 5 mm thickness were put in the mould. Resin compositions were prepared by mixing 100 parts by weight (pbw) resin, 1 pbw accelerator solution, 1 pbw of peroxide, and 0.5 pbw of inhibitor NLD-20, injecting the mixture in a mould, and allowing the mixture to cure. The gel time was approximately 45 minutes. The mould was kept at 20? C. during cure. The resulting fibre content was approx 35 wt % in the finished composition.

(4) A cured plate containing the Co-based accelerator and the wet flax (having a water content of 14 wt %) contained poorly wetted parts, whereas cured plates containing the Fe-based accelerator and the plate containing the Co-based accelerator in combination with dried flax looked fine.

(5) Test strips were taken from the test panels and the tear strength, the elongation at break, and the Young's modulus were measured according to ISO 527 on an Instron 3367 instrument.

(6) TABLE-US-00002 Tensile Elongation strength at break Young's (MPa) (%) modulus example flax metal width length width length width length 1 dried Co 32.4 52.8 1.2 1.6 4.9 6.9 (comp) 2 dried Fe 32.6 51.8 1.5 1.7 4.2 6.1 (comp) 3 wet Co X.sup.a X.sup.a X.sup.a X.sup.a X.sup.a X.sup.a (comp) 4 wet Fe 32.1 60.8 2.8 2.5 3.5 5.3 .sup.aX means: incomplete cure

(7) These data show that the cured panel containing the Fe-containing accelerator and the wet flax had a higher tear strength than the panels obtained with dried flax (Co or Fe-accelerated), especially in the longitudinal direction.

(8) Also the elongation at break was higher for this sample than for the other samples, while the stiffness (Young's modulus) was less.