Method for producing a fibrous composite material

Abstract

The invention relates to a method for producing a fibrous composite material using at least one epoxy resin and at least one initiator comprising one or more cationic metal olefin complexes. The invention further relates to a fiber-containing agent and to a fiber-containing composite material as such.

Claims

1. A method for manufacturing a fiber-containing composite material, steps of which comprise: a) providing fibers, b) treating the fibers with thermoplastic particles selected from solid rubbers, block copolymers, polysulfones, polyethersulfones, polyetherketones, polybutylene terephthalates, polycarbonates, polyetherimides, polyalkylenes, polyamides, polyesters, polyamide-imides, polyaryl ethers, or polyarylates, c) contacting the treated fibers obtained in step b) with a composition comprising at least one epoxy resin, and at least one initiator that has a neutral charge and contains one or more cationic metal-olefin complexes, to form a fiber-containing agent, and d) curing the fiber-containing agent obtained in step c) by irradiation selected from X-radiation, gamma rays, electron beams, or UV rays, sufficient to form a fiber-containing composite material, wherein at least 90% of the thermoplastic particles, based on the total number of thermoplastic particles, have an average particle size of 20 m to 70 m.

2. The method according to claim 1, wherein the fibers are present in the form of a woven fabric, a mat, a knitted fabric, or a braid.

3. The method according to claim 1, wherein the fibers are carbon fibers.

4. The method according to claim 1, wherein the thermoplastic particles have a glass transition temperature, determined by means of dynamic mechanical analysis (DMA), of at least 45 C.

5. The method according to claim 1, wherein the at least one metal in the cationic metal-olefin complex is selected from silver, cobalt, copper, aluminum, or titanium.

6. The method according to claim 1, wherein the at least one olefin in the cationic metal-olefin complex is selected from propene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, isoprene, norbornene, cyclohexene, cyclooctene, cyclodecene, 1,4-cyclohexadiene, 4-vinylcyclohexene, trans-2-octene, styrene, 5-norbornene-2-carboxylic acid, butadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,9-decadiene, sorbic acid ethyl ester, 1,3-cyclohexadiene, 1,3-cyclooctadiene, 1,5-cyclooctadiene, norbornadiene, dicyclopentadiene, cycloheptatriene, trans,trans,trans-1,5,9-cyclododecatriene, trans,trans,cis-1,5,9-cyclododecatriene, cyclooctatetraene, squalene, diallyl carbonate, diallyl ether, diallyldimethylsilane, cyclopentadiene, ethyl vinyl ether, limonene, 1,2-dihydronaphthalene, cinnamic acid ethyl ester, ethyl acrylate, ethyl methacrylate, stilbene, oleic acid methyl ester, or linolenic acid methyl ester.

7. The method according to claim 1, wherein the initiator contains, in addition to one or more cationic metal-olefin complexes, one or more anions that are selected from hexafluoroantimonate (SbF.sub.6.sup.), hexafluorophosphate (PF6.sup.), boron tetrafluoride (BF.sub.4.sup.), hexafluoroaluminate (AlF.sub.6.sup.3), trifluoromethanesulfonate (CF.sub.3SO.sub.3), nitrate (NO.sub.3.sup.), hexafluoroarsenate (AsF.sub.6.sup.), tetrakis(pentafluorophenylborate) (B[C.sub.6F.sub.5].sub.4.sup.), tetrakis[3.5-bis(trifluoromethyl)phenyl]borate (B[C.sub.6H.sub.3 (CF.sub.3).sub.2].sub.4.sup.), tetraphenylborate (B[C.sub.6H.sub.5].sub.4.sup.), hexafluorotitanate (TiF.sub.6.sup.2), or hexafluorogermanate (GeF.sub.6.sup.2), hexafluorosilicate (SiF.sub.6.sup.2), hexafluoronickelate (NiF.sub.6.sup.2), or hexafluorozirconate (ZrF.sub.6.sup.2).

8. The method according to claim 1, wherein the initiator contains at least five identical or different metal cations that, by way of bridging olefin ligands having at least two CC double bonds, form a cationic coordination polymer.

9. The method according to claim 1, wherein the initiator is selected from [Ag(cyclohexene).sub.1-4]SbF.sub.6, [Ag (cyclooctene).sub.1-4]SbF.sub.6, [Ag (trans-2-octene).sub.1-4]SbF.sub.6, [Ag(styrene).sub.1-4]SbF.sub.6, [Ag (5-norbornene-2-carboxylic acid).sub.1-4]SbF.sub.6, {[Ag(1,5-hexadiene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (1,7-octadiene).sub.1.5]SbF.sub.6}.sub.1-p, {[Ag (1,9-decadiene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (sorbic acid ethyl ester).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (1,3-cyclohexadiene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (1,3-cyclooctadiene).sub.1-4]SbF.sub.6}.sub.1-p, Ag (1,5-cyclooctadiene).sub.2]SbF.sub.6, {[Ag (norbornadiene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (dicyclopentadiene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag (cycloheptatriene).sub.1-4]SbF.sub.6}.sub.1-p, {[Cu (1,7-octadiene).sub.1-4]SbF.sub.6}.sub.1-p, [Cu (1,5-cyclooctadiene).sub.2]SbF.sub.6, [Ag (aIIyI glycidyl ether).sub.1-4]SbF.sub.6, {[Ag(trans,trans,cis-1,5,9-cyclododecatriene).sub.1-4]SbF.sub.6}.sub.1-p, {[Ag(trans,trans,trans-1,5,9-cyclododecatriene).sub.1-4]SbF6}.sub.1-p, {[Ag(cyclooctatetraene).sub.1-4]SbF.sub.6}.sub.1-p, or {[Ag(squalene).sub.1-4]SbF.sub.6}.sub.1-p, wherein p=20,000,000.

10. The method according to claim 1, wherein the initiator is suitable for initiating or accelerating non-thermal hardening of an epoxy resin.

11. A fiber-containing composite material manufactured by the method according to claim 1.

12. The method according to claim 1, wherein steps a) and b) are repeated before step c) is performed.

13. The method according to claim 1, wherein the thermoplastic particles have an average particle size of more than 30 m to less than 70 m.

Description

EXEMPLIFYING EMBODIMENTS

(1) 1. Manufacturing the Initiator

(2) Synthesis of the initiators encompassing at least one cationic metal-olefin complex occurs on the basis of methods known in the literature (H. W. Qinn, R. L. Van Gilder, Can. J. Chem. 1970, 48, 2435; A. Albinati, S. V. Meille, G. Carturan, J. Organomet. Chem. 1979, 182, 269; H. Masuda, M. Munakata, S. Kitagawa, J. Organomet. Chem. 1990, 391, 131; A. J. Canty, R. Colton, Inorg. Chim. Acta 1994, 220, 99). In this, AgSbF.sub.6 (Aldrich, 98%; or Chempur, 95+%) is dissolved in toluene or THF and reacted with an excess of alkene, by preference four equivalents. The high molecular weight metal-olefin complexes thus obtained, of the {[Ag(alkene).sub.a]SbF.sub.6}.sub.100-p type where p assumes a value between 101 and 20,000,000, are poorly soluble and precipitate out of the reaction mixture, and can then be isolated by filtration. The substances are then dried under high vacuum.

(3) In the case of further metals and ligands, firstly the respective metal chloride is reacted with AgSbF.sub.6 in a suitable solvent such as e.g. methanol, the precipitated AgCl is removed by filtration, and the resulting solution of the metal hexafluoroantimonate is reacted with the respective ligand. The solvent is then removed and the compound is dried under high vacuum.

(4) 2. Manufacturing the Resin Formulation

(5) Substances Used:

(6) TABLE-US-00001 DEN431 Epoxy resin, phenol novolac type (Dow Chemicals) DEN438 Epoxy resin, phenol novolac type (Dow Chemicals) PES Radel A-704 Polyethersulfone (Solvay) EP2240A Core-shell material: silicone rubber particles having an organic casing structure (Nanoresins)

(7) The resins resp. resin formulations, which are liquid, viscous, or solid at room temperature (54.95 wt % DEN431+23.55 wt % DEN438+15 wt % PES Radel A-704+5 wt % EP2240A), are mixed at room temperature with the corresponding initiator (see above; 1.5 wt % {[Ag(1,7-octadiene)1.5]SbF6}.sub.1-p), heated to a maximum of 80 C., and stirred until the initiator is completely dissolved in the resin. It is then cooled to room temperature.

(8) 3. Manufacturing the Fiber-Containing Composite Material

(9) Fiber-containing composite materials are manufactured using HTA carbon fibers (Toho Tenax) as a fiber component and the resin formulation recited above as a resin component, as follows:

(10) Firstly, a film of resin having a surface weight of 80 g/m.sup.2 is generated using a model ZP 25008 melt adhesive application device (Inatec company). A prepreg having a fiber volume proportion of approximately 60% is then obtained by processing the resin film using a model MDW 100-2 prepreg winding system (Microsam company).

(11) Unidirectional laminates having a layer thickness of 3 mm are manufactured by laying 12 unidirectional prepregs onto one another, the individual prepregs being obtained in accordance with the procedure described above. For manufacture of the laminates, after each new prepreg ply is placed onto a vacuum table a vacuum is applied to it in order to reduce the porosity of the material. For the case according to the present invention, in which thermoplastic particles are used as interlaminar tougheners, the corresponding thermoplastic particles are scattered onto the surface of each individual prepreg ply before the next prepreg ply is laid on, so that the application quantity indicated in Table 1 is obtained. In the present case, polyethersulfone particles of the Virantage type (Solvay Advanced Polymers, LLC), having an average particle diameter of approx. 50 m, are used as thermoplastic particles.

(12) The laminates are then deaerated by means of a vacuum bag, and passed through an electron beam unit (10 MeV); hardening occurs in four steps, in each of which a dose of 33 kGy is introduced (132 kGy total). For better release of the hardened laminates (i.e. the fiber-containing composite materials) from the mold, they are first coated with a thin layer of Frekote-700NC (Henkel Loctite) as a release agent.

(13) 4. Mechanical Data for the Fiber-Containing Composite Materials

(14) The interlaminar mode I energy release (Glc) is determined in accordance with DEN EN 6033. Two aluminum blocks are adhesively bonded onto the two surfaces of the double cantilever beam (DCB) specimen alongside an initial crack. After accurate measurement of the specimen, it is clamped into a tensile testing machine and loaded. The progress of the crack is observed with a microscope over the entire experimental period. During the experiment, the force-displacement diagram is plotted in order to determine the interlaminar mode I energy release. A universal testing machine (UPM) of the Zwick company (model Z 2.5) is used to carry out the fracture mechanics experiments. Double cantilever beam (DCB) test specimens (250 mm25 mm3 mm) serve as test specimens. All measurements are carried out at 23 C. and 50% relative humidity.

(15) The interlaminar mode II energy release rate (GIIc) is determined in accordance with DIN EN 6034. The end-notched flexure (ENF) test is carried out on a three-point bending apparatus, and the progress of the crack is observed with a microscope over the entire experimental period. A force-displacement diagram is plotted during the experiment in order to determine the interlaminar mode II energy release rate. A universal testing machine (UPM) of the Zwick company (model Z 2.5) is used to carry out the fracture mechanics experiments. ENF test specimens (120 mm25 mm3 mm) are used as test specimens. All measurements are carried out at 23 C. and 50% relative humidity.

(16) The fracture mechanics data determined for the fiber-containing composite materials are presented in Table 1:

(17) TABLE-US-00002 TABLE 1 Interlaminar mode I and mode II energy release data Virantage polyethersulfone GIc GIIc (quantity applied in interlaminar region) (J/m.sup.2) (J/m.sup.2) (ref.) 248 565 10 g/m.sup.2 360 950 20 g/m.sup.2 345 1188 40 g/m.sup.2 380 875

(18) It is evident that use of the polyethersulfone particles of the type recited above results in toughness modification, in particular an interlaminar toughness modification, of the fiber-containing composite materials under investigation.