EP2582516A1

EP2582516A1 - Semifinished product for the production of fibre composite components based on stable polyurethane compositions

Info

Publication number: EP2582516A1
Application number: EP11721759.6A
Authority: EP
Inventors: Friedrich Georg Schmidt
Original assignee: Evonik Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2010-06-17
Filing date: 2011-05-18
Publication date: 2013-04-24
Also published as: DE102010030233A1; US20130078417A1; MX2012013547A; MY153324A; RU2013101967A; CN102933384A; KR20130113947A; CA2799340A1; BR112012030303A2; ZA201209546B; AU2011267319A1; WO2011157507A1; AU2011267319B2; JP2013530280A

Abstract

The invention relates to a semifinished product for the production of fibre composite components, comprising at least two walls of fibre-filled matrix material, which are angled in a meandering manner and are thermally joined to one another to form a symmetrical core structure. The invention addresses the problem of providing a semifinished product which is suitable as a core structure for a fibre composite component in sheet form that has better draping qualities as a result of the not yet cured matrix, but at the same time is sufficiently stable in terms of its shape and composition that it can be easily handled. This problem is solved by using as the matrix material a polyurethane composition which contains as a binder a polymer having functional groups that are reactive with respect isocyanates and contains as a hardener diisocyanate or polyisocyanate that is blocked internally and/or by blocking agents.

Description

Semi-finished product for the production of fiber composite components based on storage-stable polyurethane compositions

The invention relates to a semifinished product for the production of fiber composite components, comprising at least two meandering angled walls made of fiber-filled

Matrix material, which are forming a symmetrical core structure thermally joined together. Furthermore, the invention relates to a method for producing such a semifinished product, to a method for producing fiber composite components from such a semifinished product and to a fiber composite component produced from such a semifinished product.

A fiber composite component is a part of a technical device, which is made of a fiber composite material. Fiber composite components are widely used in aerospace, automotive, mechanical engineering and sports equipment due to their low specific weight and high rigidity and load capacity. Fiber composites are inhomogeneous materials, constructed from a plastic matrix material and incorporated therein natural or artificial, organic or inorganic fibers. The fibers are used for power transmission in the fiber composite component, the matrix introduces the external forces into the fibers and protects them from harmful

Influences of the environment.

A special feature of the fiber composite construction is that fiber composite material and fiber composite component arise simultaneously, namely by the insoluble bonding of fiber and matrix. Classic materials such as steel or wood already exist before the component formed from them.

Fiber composite components are, however, constructed of semi-finished, manageable, geometrically determined moldings containing fiber and matrix material of the later

Composite, but still without firm cohesion of fiber and matrix.

The latter arises only with curing of the matrix by a chemical reaction. Accordingly, in the manufacture of fiber composite components, drawer or semi-finished products which may sometimes be draped or cut to one another are then arranged relative to one another and then cured to form the composite material.

Plate-shaped fiber composite components usually comprise two in the plate plane

extending, parallel spaced cover layers between which a hexagonal honeycomb structure is laminated as torsionally rigid core. The hexagon Honeycomb structure is in turn made up of a plurality of fibrous walls, which are arranged orthogonal to the cover layers.

A method for producing a core suitable for a fiber composite component

Hexagonal honeycomb structure is described in DE 38 38 153 C2. This is a

formed thermoplastic matrix material with fibers into a wall, which receives in a subsequent forming step has a meandering angled 120 ° shape. Then several of these walls are aligned with each other, so that the adjacent

Mäanderschleifen form hexagonal honeycombs. The weldable thermoplastic material allows the walls to be thermally bonded at the joints of adjacent meandering loops.

The principle-dictated property of this honeycomb structure produced on a thermoplastic basis is its high rigidity even before the completion of the fiber composite component, since the thermoplastic matrix has already hardened. Thus, strictly speaking, it is not a semi-finished product in the sense described above. Disadvantage of this honeycomb structure is their poor drapability in the production of the composite component.

In view of this prior art, the invention is based on the object to provide a suitable as a core structure for a plate-shaped fiber composite component semi-finished, which has a better drapability due to the not yet cured matrix, but at the same time sufficiently stable in form and storage, so that easy to handle is.

This problem is solved in that as a matrix material

Polyurethane composition is used which

a) as a binder an isocyanate-reactive functional groups

having polymers,

b) and as hardener internally and / or blocked with blocking agents di- or

polyisocyanate

contains.

The invention is therefore a semi-finished product for the production of

Fiber composite components, comprising at least two meandering angled walls of fiber-filled matrix material, which are thermally joined together forming a symmetrical core structure,

characterized, in that the matrix material is a polyurethane composition which comprises a) as binder, an isocyanate-reactive functional group

having polymers,

b) and as hardener internally and / or blocked with blocking agents di- or

polyisocyanate

contains.

Said polyurethane composition according to the invention is not yet cured. For this purpose, the addition of heat energy to lift the blocking of the curing agent, so that the crosslinking reaction can start.

The invention is based, inter alia, on the surprising finding that fiber-filled matrix material of this polyurethane composition can be thermally attached at a temperature which is below the temperature required to repeal the

Blockage effect is necessary. This means that walls made of fiber-filled, uncured matrix material can be "attached" to one another in a plastic welding process in order to produce a symmetrical core structure, such as hexagonal honeycombs, from the walls, since the crosslinking reaction is further inhibited despite thermal joining The curing of the semifinished product then takes place at a higher temperature level in the case of extensive heat exposure at the joints a much greater strength than the only welded, uncrosslinked semi-finished.

A further development of the invention provides for providing the semifinished product with at least one covering layer applied to the core structure, wherein the core structure and covering layer are joined in a material-locking manner. Cohesive means in particular glued or thermally joined as soldered or welded. Bonding is useful if the cover layer is made of a different material than the matrix material, for example of metal. As long as the matrix material of the core connected to the cover layer is not cured, its stiffening effect is not so pronounced.

A particularly preferred embodiment of the invention provides to build the cover layer of a matrix material as the walls and the core structure with the

Cover layer of the semifinished product also to add thermally. The special advantage of this Namely embodiment is that during curing of the

Polyurethane composition has a cross-linking via the junctions of core and

Cover layer away, so that the fiber composite component receives a particularly high strength. The uncured top layer is still flexible.

A semifinished product according to the invention is produced as follows: a) Provision of a polyurethane composition comprising as binder a

towards isocyanate-reactive functional group-containing polymers and as a hardener internally and / or blocked with blocking agents di- or

polyisocyanate

b) providing fibers,

c) mixing the polyurethane composition and the fibers into one

Molding compound

d) forming the molding material into a flat wall,

e) reshaping the wall to give it a meandering angled shape, f) aligning the meandering angled wall to another meandering angled wall,

g) thermal joining of at least the two walls to a symmetrical

Core structure.

Such a method is also the subject of the invention.

The Polyerthanzusammensetzung can be powdered dry or - provided in a solvent - wet provided.

The mixing of the dry powder with the fibers can be carried out, for example, in a manner known per se in a (screw) extruder, the primary shaping of the wall by extruding the molding composition through a suitably shaped tool. The mixing of fiber and matrix in the extruder will only be possible with short fiber lengths.

If larger fiber lengths are processed or a unidirectional fiber alignment can be achieved, the mixing / prototyping in a conventional manner in a

Pultrusion process done. Here, a wet polymer composition is processed. The fibers can be present in textile fabrics (for example woven, braided, knitted, knitted, knitted, laid, non-woven) and impregnated in a manner known per se with the polyurethane composition dissolved in the solvent. The solvent is evaporated from the soaked fabric leaving the wall of fiber filled matrix material.

Preferably, the manufacturing process is extended to include steps for applying topcoat to the core structure. This gives a semi-finished product with cover layers. The attachment of the cover layer to the core structure takes place at temperatures such as during thermal joining.

The thermal joining of the walls to the core or the cover layer (s) to the core is preferably carried out at a temperature below the temperature below the

Curing temperature of the polyurethane composition is so that in the joining area no polymerization of the matrix takes place and the semi-finished product remains supple.

The curing of the semifinished product to the finished fiber composite component then takes place at a temperature above that during thermal joining. A method according to the invention for producing a fiber composite component thus comprises the steps of providing a semifinished product produced according to the invention and curing the polyurethane composition at a temperature above the temperature during thermal joining.

The invention thus also relates to a process for the preparation of a

Fiber composite component with these steps and a fiber composite component, which is made of a semifinished product according to the invention, in particular by said method.

An essential feature of the present invention is the use of an inhibited polyurethane composition as matrix material, which

a) as a binder an isocyanate-reactive functional groups

having polymers,

b) and as hardener internally and / or blocked with blocking agents di- or

polyisocyanate

contains.

In principle, all, even other storage stable at room temperature reactive

Polyurethane compositions are suitable as matrix materials. Particularly suitable Polyurethane compositions consist of mixtures of a functional group-reactive with respect to NCO-containing polymers as a binder and temporarily deactivated, that is internally blocked and / or blocked with blocking agents di- or polyisocyanates, as a curing agent.

Suitable functional groups of the polymers used as binders are hydroxyl groups, amino groups and thiol groups which react with the free isocyanate groups with addition and thus crosslink and harden the polyurethane composition. The binder components must have a solid resin character (glass transition temperature greater than room temperature). Suitable binders are polyesters, polyethers, polyacrylates, polycarbonates and polyurethanes having an OH number of 20 to 500 mg KOH / gram and an average molecular weight of 250 to 6000 g / mol. Particularly preferred

hydroxyl-containing polyesters or polyacrylates having an OH number of 20 to 150 mg KOH / gram and an average molecular weight of 500 to 6000 g / mol.

Of course, mixtures of such polymers can be used. The amount of polymers having the functional groups is selected such that each functional group of the binder component accounts for 0.6 to 2 NCO equivalents or 0.3 to 1.0 uretdione groups of the hardener component.

Suitable hardener components are blocked or internally blocked (uretdione) di- and polyisocyanates with blocking agents.

The diisocyanates and polyisocyanates used according to the invention can consist of any desired aromatic, aliphatic, cycloaliphatic and / or (cyclo) aliphatic di- and / or polyisocyanates.

As aromatic di- or polyisocyanates, in principle, all known aromatic compounds are suitable. Particularly suitable are 1, 3 and 1, 4-phenylene diisocyanate, 1, 5-naphthylene diisocyanate, tolidine diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate (2,4-TDI), 2,4'-diphenylmethane diisocyanate ( 2,4'-MDI), 4,4'-diphenylmethane diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates (MDI) and oligomers

Diphenylmethane diisocyanates (polymer-MDI), xylylene diisocyanate,

Tetramethylxylylene diisocyanate and triisocyanatotoluene.

Suitable aliphatic di- or polyisocyanates advantageously have 3 to 16

Carbon atoms, preferably 4 to 12 carbon atoms, in the linear or branched alkylene radical and suitable cycloaliphatic or (cyclo) aliphatic diisocyanates advantageously 4 to 18 carbon atoms, preferably 6 to 15 carbon atoms, in the cycloalkylene radical. Under (cyclo) aliphatic diisocyanates the skilled person understands at the same time cyclic and aliphatic bonded

NCO groups, as z. B. isophorone diisocyanate is the case. In contrast, is meant by cycloaliphatic diisocyanates those which have only directly attached to the cycloaliphatic ring NCO groups, for. B. H ₁₂ MDI.

Examples are cyclohexane diisocyanate, methylcyclohexane diisocyanate,

Ethylcyclohexane diisocyanate, propylcyclohexane diisocyanate,

Methyldiethylcyclohexane diisocyanate, propane diisocyanate, butane diisocyanate,

Pentane diisocyanate, hexane diisocyanate, heptane diisocyanate, octane diisocyanate,

Nonane diisocyanate, nonane triisocyanate, such as 4-isocyanatomethyl-1, 8-octane diisocyanate (TIN), decane and triisocyanate, undecanediol and triisocyanate, dodecanedi and triisocyanates.

Preference is given to isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI),

Diisocyanatodicyclohexylmethane (H ₁₂ MDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate / 2,4,4-trimethylhexamethylene diisocyanate (TMDI), norbornane diisocyanate (NBDI). Very particular preference is given to using IPDI, HDI, TMDI and H ₁₂ MDI, it also being possible to use the isocyanurates.

Also suitable are 4-methylcyclohexane-1,3-diisocyanate, 2-butyl-2-ethylpentamethylene diisocyanate, 3 (4) -isocyanatomethyl-1-methylcyclohexyl isocyanate, 2-isocyanatopropylcyclohexyl isocyanate, 2,4'-methylenebis (cyclohexyl ) diisocyanate, 1,4-diisocyanato-4-methyl-pentane.

Of course, mixtures of di- and polyisocyanates can be used.

Furthermore, preference is given to using oligoisocyanates or polyisocyanates which are prepared from the abovementioned diisocyanates or polyisocyanates or mixtures thereof by linking by means of urethane, allophanate, urea, biuret, uretdione, amide, isocyanurate, carbodiimide, uretonimine , Oxadiazinetrione or iminooxadiazinedione structures.

Particularly suitable are isocyanurates, especially from IPDI and HDI.

The polyisocyanates used in the invention are blocked. In question come to external blocking agents such. Ethyl acetoacetate, diisopropylamine,

Methyl ethyl ketoxime, diethyl malonate, ε-caprolactam, 1, 2,4-triazole, phenol or substituted phenols and 3,5-dimethylpyrazole. The preferred hardener components are IPDI adducts containing isocyanurate moieties and ε-caprolactam blocked isocyanate structures.

An internal blocking is possible and this is preferably used. The internal blocking takes place via a dimer formation via uretdione structures which, at elevated temperature, split back into the originally present isocyanate structures and thus initiate crosslinking with the binder.

Optionally, the reactive polyurethane compositions may contain additional catalysts. These are organometallic catalysts, such as. B.

Dibutyltin dilaurate (DBTL), Zinnoctoat, bismuth neodecanoate, or tertiary amines, such as. B. 1, 4-diazabicyclo [2.2.2.] Octane, in amounts of 0.001 - 1 wt .-%. These

used in accordance with the invention reactive polyurethane compositions are used under normal conditions, for. B. with DBTL catalysis, from 160 ° C, usually cured from about 180 ° C and designated as.

For the preparation of the reactive polyurethane compositions customary in powder coating technology additives such as leveling agents, for. As polysilicone or acrylates, light stabilizers z. As sterically hindered amines, or other auxiliaries, such as. As described in EP 669 353, be added in a total amount of 0.05 to 5 wt .-%. Fillers and pigments such. Titanium dioxide may be added in an amount of up to 30% by weight of the total composition.

Reactive (variant I) in the context of this invention means that the reactive polyurethane compositions used according to the invention, as described above, cure at temperatures above 160 ° C., depending on the type of fiber.

The reactive polyurethane compositions used in the invention are used under normal conditions, for. B. with DBTL catalysis, from 160 ° C, usually from about 180 ° C cured. The time for curing the inventively used

Polyurethane composition is usually within 5 to 60 minutes.

Preferably, in the present invention, a matrix material is used, consisting of a polyurethane containing uretdione reactive polyurethane compositions, substantially containing a) at least one hardening agent containing uretdione groups, based on

Polyadditionsverbindungen of aliphatic, (cyclo) aliphatic or cycloaliphatic uretdione polyisocyanates and hydroxyl-containing compounds, wherein the curing agent is below 40 ° C in solid form and above 125 ° C in liquid form and a free NCO content of less than 5 wt. % and a uretdione content of 3 - 25 wt .-%, b) at least one hydroxyl-containing polymer which is below 40 ° C in solid form and above 125 ° C in liquid form and an OH number between 20 and 200 mg KOH / gram, c) optionally at least one catalyst, d) optionally auxiliaries and additives known from polyurethane chemistry, so that the two components hardener and binder are present in the ratio of 0.3 to 1 uretdione group for each hydroxyl group of the binder component the hardener component is omitted, preferably 0.45 to 0.55. The latter corresponds to an NCO / OH ratio of 0.9 to 1, 1 to 1.

Uretdione group-containing polyisocyanates are well known and are described, for example, in US 4,476,054, US 4,912,210, US 4,929,724 and EP 417,603. A Comprehensive Review of Industrially Relevant Techniques for Dimerization of

Isocyanates to uretdiones provides the J. Prakt. Chem. 336 (1994) 185-200. In general, the reaction of isocyanates to uretdiones takes place in the presence of more soluble

Dimerization catalysts such. For example, dialkylaminopyridines, trialkylphosphines,

Phosphorous acid triamides or imidazoles. The reaction - optionally carried out in solvents, but preferably in the absence of solvents - is stopped when a desired conversion is achieved by addition of catalyst poisons. Excess monomeric isocyanate is subsequently separated by short path evaporation. If the catalyst is volatile enough, the reaction mixture can be freed from the catalyst in the course of the monomer separation. The addition of catalyst poisons can be dispensed with in this case. In principle, a wide range of isocyanates is suitable for the preparation of polyisocyanates containing uretdione groups. The above di- and polyisocyanates can be used. Preferably, however, di- and

Polyisocyanates of any aliphatic, cycloaliphatic and / or (cyclo) aliphatic di- and / or polyisocyanates. According to the invention, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI),

Diisocyanatodicyclohexylmethane (H ₁₂ MDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate / 2,4,4-trimethylhexamethylene diisocyanate (TMDI),

Norbornane diisocyanate (NBDI) used. Very particular preference is given to using IPDI, HDI, TMDI and H ₁₂ MDI, it also being possible to use the isocyanurates.

Most preferably, IPDI and HDI are used for the matrix material.

The implementation of these polyisocyanates containing uretdione groups to hardeners containing uretdione groups involves the reaction of the free NCO groups with

hydroxyl-containing monomers or polymers, such as. As polyesters, polythioethers, polyethers, polycaprolactams, polyepoxides, polyester amides, polyurethanes or low molecular weight di-, tri- and / or tetra alcohols as chain extenders and optionally monoamines and / or monoalcohols as chain terminators and has been frequently described (EP 669 353, EP 669 354 DE 30 30 572, EP 639 598 or EP 803 524).

Preferred uretdione hardeners have a free NCO content of less than 5% by weight and a content of uretdione groups of 3 to 25% by weight, preferably 6 to 18% by weight (calculated as C2N2O2, molecular weight 84). Preference is given to polyesters and monomeric dialcohols. Besides the uretdione groups, the hardeners can also

Isocyanurate, biuret, allophanate, urethane and / or urea structures.

In the case of the hydroxyl-containing binder polymers, preference is given to using polyesters, polyethers, polyacrylates, polyurethanes and / or polycarbonates having an OH number of 20-200 in mg KOH / gram. Particular preference is given to using polyesters having an OH number of 30-150, an average molecular weight of 500-6000 g / mol, which are below 40 ° C. in solid form and above 125 ° C. in liquid form. Such

Binders have been described, for example, in EP 669 354 and EP 254 152.

Of course, mixtures of such polymers can be used. The amount of hydroxyl-containing polymers is chosen so that each

Hydroxyl group of the binder component 0.3 to 1 Uretdiongruppe the hardener component, preferably 0.45 to 0.55, is omitted.

Optionally, additional catalysts can be present in the reactive polyurethane compositions according to the invention. These are organometallic catalysts, such as. As dibutyltin dilaurate, zinc octoate, bismuth neodecanoate, or tertiary amines, such as. B. 1, 4-diazabicyclo [2.2.2.] Octane, in amounts of 0.001 - 1 wt .-%. These reactive polyurethane compositions used in this invention are used under normal conditions, for. B. with DBTL catalysis, from 160 ° C, usually cured from about 180 ° C and designated as variant I.

For the preparation of the reactive polyurethane compositions according to the invention, the customary in the powder coating technology additives such as leveling agents, for. B.

Polysilicone or acrylates, light stabilizers z. As sterically hindered amines, or other auxiliaries, such as. As described in EP 669 353, be added in a total amount of 0.05 to 5 wt .-%. Fillers and pigments such. Titanium dioxide may be added in an amount of up to 30% by weight of the total composition.

The reactive polyurethane compositions used in the invention are used under normal conditions, for. B. with DBTL catalysis, from 160 ° C, usually from about 180 ° C cured. The reactive polyurethane compositions used according to the invention provide a very good flow and thus a good impregnating ability and in the

cured state excellent chemical resistance. When using aliphatic crosslinkers (eg IPDI or H ₁₂ MDI) is also a good

Weather resistance reached.

Particularly preferred in the invention, a matrix material is used

Containing at least one highly reactive uretdione groups

A polyurethane composition substantially containing

a) at least one hardener containing uretdione groups

and

b) optionally at least one polymer reactive with NCO groups

functional groups;

c) 0.1 to 5 wt .-% of at least one catalyst selected from quaternary

Ammonium salts and / or quaternary phosphonium salts with halogens, hydroxides, alcoholates or organic or inorganic acid anions as counterion;

and

d) 0.1 to 5 wt .-% of at least one co-catalyst selected from

d1) at least one epoxide

and or d2) at least one metal acetylacetonate and / or quaternary

Ammonium acetylacetonate and / or quaternary phosphonium acetylacetonate; e) optionally known from polyurethane chemistry auxiliaries and additives.

In particular, a matrix material is used consisting of at least one highly reactive powdery uretdione-containing polyurethane composition as matrix material, essentially containing

a) at least one hardening agent containing uretdione groups, based on

Polyadditionsverbindungen of aliphatic, (cyclo) aliphatic or

cycloaliphatic uretdione groups contained polyisocyanates and

hydroxyl-containing compounds, wherein the hardener is below 40 ° C. in solid form and above 125 ° C. in liquid form and has a free NCO content of less than 5% by weight and a uretdione content of 3 to 25% by weight, b) at least one hydroxyl-containing polymer which is in liquid form below 40 ° C in solid form and above 125 ° C and an OH number between 20 and 200 mg KOH / gram;

c) 0.1 to 5 wt .-% of at least one catalyst selected from quaternary

and

d) 0.1 to 5 wt .-% of at least one co-catalyst selected from

d1) at least one epoxide

and or

d2) at least one metal acetylacetonate and / or quaternary

Ammonium acetylacetonate and / or quaternary phosphonium acetylacetonate; e) optionally known from polyurethane chemistry auxiliaries and additives, so that the two components hardener and binder are present in the ratio that accounts for each hydroxyl group of the binder component 0.3 to 1 uretdione of the hardener component, preferably 0.6 to 0.9. The latter corresponds to an NCO / OH ratio of 0.6 to 2 to 1 or 1, 2 to 1, 8 to 1.

These highly reactive polyurethane compositions used according to the invention are cured at temperatures of 100 to 160 ° C and referred to as variant II. The thermal joining (plastic welding) can then take place at about 80 ° C. According to the invention, suitable highly reactive polyurethane compositions containing uredione groups comprise mixtures of temporarily deactivated, ie uretdione-containing (internally blocked) di- or polyisocyanates, also referred to as hardeners, and the catalysts according to the invention and optionally additionally a functional group-reactive polymer having NCO groups (Binder), also referred to as resin. The catalysts ensure curing of the Urediongruppen containing polyurethane compositions at low temperature. The Urediongruppen-containing polyurethane compositions are thus highly reactive.

As binders and hardeners, such components are used as described above.

The catalysts used are quaternary ammonium salts, preferably tetralkylammonium salts and / or quaternary phosphonium salts with halogens, hydroxides, alcoholates or organic or inorganic acid anions as counterion. Examples are:

Tetramethylammonium formate, tetramethylammonium acetate,

Tetramethylammonium propionate, tetramethylammonium butyrate, tetramethylammonium benzoate, tetraethylammonium formate, tetraethylammonium acetate,

Tetraethylammonium propionate, tetraethylammonium butyrate, tetraethylammonium benzoate, tetrapropylammonium formate, tetrapropylammonium acetate,

Tetrapropylammonium propionate, tetrapropylammonium butyrate,

Tetrapropylammonium benzoate, tetrabutylammonium formate, tetrabutylammonium acetate, tetrabutylammonium propionate, tetrabutylammonium butyrate and

Tetrabutylammonium benzoate and tetrabutylphosphonium acetate,

Tetrabutylphosphonium formate and ethyltriphenylphosphonium acetate,

Tetrabutylphosphoniumbenzotriazolat, Tetraphenylphosphoniumphenolat and

Trihexyltetradecylphosphonium decanoate, methyltributylammonium hydroxide,

Methyltriethylammonium hydroxide, tetramethylammonium hydroxide,

Tetraethylammonium hydroxide, tetrapropylammonium hydroxide,

Tetrabutylammonium hydroxide, tetrapentylammonium hydroxide,

Tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,

Tetradecylammonium hydroxide, tetradecyltrihexylammonium hydroxide,

Tetraoctadecylammonium hydroxide, benzyltrimethylammonium hydroxide,

Benzyltriethylammonium hydroxide, tri-methylphenylammonium hydroxide, Triethylmethylammonium hydroxide, tri-methylvinylammonium hydroxide,

Methyltributylammonium methoxide, methyltriethylammonium methoxide,

Tetramethylammonium methoxide, tetraethylammonium methoxide,

Tetrapropylammonium methoxide, tetrabutylammonium methoxide,

Tetrapentylammonium methoxide, tetrahexylammonium methoxide,

Tetraoctylammonium methoxide, tetradecylammonium methoxide,

Tetradecyltrihexylammonium methoxide, tetraoctadecylammonium methoxide,

Benzyltrimethylammonium methoxide, benzyltriethylammonium methoxide,

Trimethylphenylammonium methoxide, triethylmethylammonium methoxide,

Trimethyl vinyl ammonium methoxide, methyl tributyl ammonium ethoxide,

Methyltriethylammoniumethanolat, Tetramethylammoniumethanolat,

Tetraethylammoniumethanolate, tetrapropylammoniumethanolate,

Tetrabutylammonium ethanolate, tetrapentylammonium ethanolate,

Tetrahexylammonium ethoxide, tetraoctylammonium methoxide,

Tetradecylammonium ethoxide, tetradecyltrihexylammoniumethanolate,

Tetraoctadecylammonium ethanolate, benzyltrimethylammoniumethanolate,

Benzyltriethylammonium ethanolate, tri-methylphenylammonium ethanolate,

Triethylmethylammoniumethanolate, tri-methylvinylammoniumethanolate,

Methyltributylammoniumbenzylate, methyltriethylammoniumbenzylate,

Tetramethylammonium benzylate, tetraethylammoniumbenzylate,

Tetrapropylammonium benzylate, tetrabutylammonium benzylate,

Tetrapentylammonium benzylate, tetrahexylammoniumbenzylate,

Tetraoctylammonium benzylate, tetradecylammoniumbenzylate,

Tetradecyltrihexylammoniumbenzylate, tetraoctadecylammoniumbenzylate,

Benzyltrimethylammoniumbenzylat, Benzyltriethylammoniumbenzylat, tri- methylphenylammoniumbenzylat, Triethylmethylammoniumbenzylat, tri- methylvinylammoniumbenzylat, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrabutylammonium fluoride, tetraoctylammonium, benzyltrimethylammonium, tetrabutylphosphonium hydroxide, Tetrabutylphosphoniumfluorid, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide,

Benzyltrimethylammonium chloride, benzyltriethylammonium chloride,

Benzyltripropylammonium chloride, benzyltributylammonium chloride,

Methyltributylammonium chloride, methyltripropylammonium chloride,

Methyltriethylammonium chloride, methyltriphenylammonium chloride, Phenyltrimethylammonium chloride, benzyltrimethylammonium bromide,

Benzyltriethylammonium bromide, benzyltripropylammonium bromide,

Benzyltributylammonium bromide, methyltributylammonium bromide,

Methyltripropylammonium bromide, methyltriethylammonium bromide,

Methyltriphenylammonium bromide, phenyltrimethylammonium bromide,

Benzyltrimethylammonium iodide, benzyltriethylammonium iodide,

Benzyltripropylammonium iodide, benzyltributylammonium iodide, methyltributylammonium iodide, methyltripropylammonium iodide, methyltriethylammonium iodide,

Methyltriphenylammonium iodide and phenyltrimethylammonium iodide,

Methyltributylammonium hydroxide, methyltriethylammonium hydroxide,

Tetramethylammonium hydroxide, tetraethylammonium hydroxide,

Tetrapropylammonium hydroxide, tetrabutylammonium hydroxide,

Tetrapentylammonium hydroxide, tetrahexylammonium hydroxide,

Tetraoctylammonium hydroxide, tetradecylammonium hydroxide,

Tetradecyltrihexylammonium hydroxide, tetraoctadecylammonium hydroxide,

Benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide,

Trimethylphenylammonium hydroxide, triethylmethylammonium hydroxide,

Trimethylvinylammonium hydroxide, tetramethylammonium fluoride,

Tetraethylammonium fluoride, tetrabutylammonium fluoride, tetraoctylammonium fluoride and benzyltrimethylammonium fluoride. These catalysts may be added alone or in mixtures. Preference is given to tetraethylammonium benzoate and

Tetrabutylammonium hydroxide used.

The proportion of catalysts may be 0.1 to 5 wt .-%, preferably from 0.3 to 2 wt .-%, based on the total formulation of the matrix material.

A variant according to the invention includes the attachment of such catalysts to the functional groups of the binder polymers. In addition, these catalysts may be surrounded with an inert shell and encapsulated with it.

As co-catalysts d1) epoxides are used. In question come here z. B.

Glycidyl ethers and glycidyl esters, aliphatic epoxides, diglycidyl ethers based on bisphenol A and glycidyl methacrylates. Examples of such epoxides are triglycidyl isocyanurate (TGIC, trade name ARALDIT 810, Huntsman), mixtures of terephthalic acid diglycidyl ester and trimellitic triglycidyl ester (trade name ARALDIT PT 910 and 912, Huntsman),

Glycidyl ester of versatic acid (trade name KARDURA E10, Shell), 3,4- Epoxycyclohexylmethyl 3 ', 4'-epoxycyclohexanecarboxylate (ECC), diglycidyl ether based on bisphenol A (trade name EPIKOTE 828, Shell) ethylhexyl glycidyl ether, butyl glycidyl ether, pentaerythritol tetraglycidyl ether, (trade name POLYPOX R 16, UPPC AG) as well as other types of polyoxymethylene with free epoxy groups. It can also be used mixtures. Preference is given to using ARALDIT PT 910 and 912 used.

Suitable cocatalysts d2) are metal acetylacetonates. Examples of these are zinc acetylacetonate, lithium acetylacetonate and tin acetylacetonate, alone or in

Mixtures. Zinc acetylacetonate is preferably used.

Also suitable as cocatalysts d2) are quaternary ammonium acetylacetonates or quaternary phosphonium acetylacetonates.

Examples of such catalysts are tetramethylammonium acetylacetonate,

Tetraethylammonium acetylacetonate, tetrapropylammonium acetylacetonate,

Tetrabutylammonium acetylacetonate, benzyltrimethylammonium acetylacetonate,

Benzyltriethylammonium acetylacetonate, tetramethylphosphonium acetylacetonate,

Tetraethylphosphonium acetylacetonate, tetrapropylphosphonium acetylacetonate,

Tetrabutylphosphonium acetylacetonate, Benzyltrimethylphosphoniumacetylacetonat, Benzyltriethylphosphoniumacetylacetonat. Particularly preferred

Tetraethylammoniumacetylacetonat and tetrabutylammonium acetylacetonate used. Of course, mixtures of such catalysts can be used.

The proportion of cocatalysts d1) and / or d2) can be from 0.1 to 5% by weight, preferably from 0.3 to 2% by weight, based on the total formulation of the matrix material.

With the help of the inventively used highly reactive and thus at low temperature curing polyurethane compositions can at 100 to 160 ° C.

Curing temperature not only saves energy and curing time, but it can also use many temperature-sensitive fibers.

Highly reactive (variant II) in the context of this invention means that the uretdione group-containing polyurethane compositions used according to the invention cure at temperatures of 100 to 160 ° C, depending on the nature of the fiber. This curing temperature is preferably from 120 to 150.degree. C., more preferably from 130 to 140.degree. The time for curing the polyurethane composition used according to the invention is within 5 to 60 minutes. Contain the highly reactive Urediongruppen used in the invention

Polyurethane compositions offer a very good flow and thus a good impregnation and in the cured state an excellent

Chemical resistance. When using aliphatic crosslinkers (eg IPDI or H ₁₂ MDI), a good weathering resistance is additionally achieved.

The reactive or highly reactive used according to the invention as a matrix material

Polyurethane compositions essentially consist of a mixture of a reactive resin and a hardener. After melt homogenization, this mixture has a glass transition temperature T _g of at least 40 ° C. and usually reacts above 160 ° C., in the reactive polyurethane compositions or above 100 ° C., in the highly reactive polyurethane compositions to form a crosslinked polyurethane and thus forms the Matrix of the composite. That means the

According to the invention semifinished products are prepared after their preparation from the fibers and the applied reactive polyurethane composition as a matrix material, which is present in uncrosslinked, but reactive form.

A thermal joining (attachment) to the structure of the core structure is then possible at about 75 to 82 ° C. The semi-finished products are as a result stable in storage, usually several days and even weeks and can thus be further processed at any time into fiber composite components. This is the essential difference to the two-component systems already described above, which are reactive and not storage-stable, since these are after the

Apply immediately to react to polyurethanes and crosslink.

The invention will now be explained in more detail with reference to embodiments. For this show:

Figure 1: Laboratory scattering device (Villars Minicoater 200) for the production of

Walls;

Figure 2: Graphical representation of enthalpy over time

Figures 3 and 4: Graphical representation of the glass transition temperature T _g over time; Figure 5: Production of a semifinished product according to the invention and subsequent

Further processing to fiber composite component (schematic).

Used fiberglass scrims / fabrics:

The following fiberglass scrims / fabrics were used in the Examples, hereafter referred to as Type I and Type II.

Type I is a canvas E-glass fabric 281 L Art.No. 3103 of the company "Schlösser &Cramer" The fabric has a basis weight of 280 g / m ² .

Type II GBX 600 Art.No. 1023 is a sewn biaxial E-glass-clutches (-45 / + 45) of the company "Schlösser &Cramer", which means two layers of fiber bundles, which lie one above the other and are offset at an angle of 90 degrees This structure is held together by other fibers which, however, are not made of glass The surface of the glass fibers is equipped with a standard sizing which is modified with aminosilane The scrim has a basis weight of 600 g / m ² .

DSC measurements

The DSC investigations (glass transition temperature determinations and

Reaction enthalpy measurements) were carried out with a Mettler Toledo DSC 821 e according to DIN 53765.

Highly reactive powdered polyurethane composition

A highly reactive powdered polyurethane composition having the following formulation was used to make the walls of the semi-finished products. (In% by weight):

The comminuted feedstocks from the table are intimately mixed in a premixer and then homogenized in the extruder to a maximum of 130 ° C. After cooling, the extrudate is broken and ground with a pin mill. The used

Sieve fractions had mean particle diameters between 63 and 100 μηη.

Physical Properties

By selecting suitable sintering conditions during various preliminary tests, the following settings proved to be well suited for the production of the walls on the minicoater:

There were about 150 g / powder on a square of glass fiber at a

Web speed of about 1, 2 m / min applied. This corresponds to a layer thickness of about 500 μηη with a standard deviation of about 45 μηη.

With a power of the IR emitters of 560 W so strip-shaped walls at temperatures between 75 and 82 ° C could be prepared, wherein the highly reactive powdered polyurethane composition was sintered, which was irrelevant whether the powders were still sintered with powder structure still recognizable, or itself resulted in a complete melt on the Glasfasergelege, as long as the reactivity of the powdered polyurethane composition was retained.

Fabricating the core structure

The strip-shaped, flat walls of fiber-containing matrix material can be further processed according to Figure 5 to symmetrical core structures.

For this purpose, the strip-shaped, flat wall 1 is first angled continuously at room temperature with a constant leg length of 120 °, so that it receives a meandering shape 2 similar to a trapezoidal sheet.

Then, a plurality of these angled walls are arranged in pairs so that they abut each other with their crest and sole portions. With now again increased temperature between 75 and 82 ° C, the angled walls 2 per

Roller crimping thermally joined together so that the apex and sole portions of the adjacent walls adhere to each other and in this way form a regular, symmetrical hexagon honeycomb structure 3, the finished semi-finished product.

Storage stability of the semi-finished products

The storage stability of the semi-finished products was determined by the reaction enthalpies of the

Crosslinking reaction determined by DSC studies. The results are shown in FIG. 2 and FIG.

The cross-linking ability of the PU semi-finished products is not impaired by the storage at room temperature for at least a period of 7 weeks.

Production of the fiber composite component

Figure 5 is further illustrated schematically, as from the semifinished product 3, a fiber composite component 4 is formed. The composite component was produced by means of a press technique known to the person skilled in the art on a composite press. The honeycomb structure 3 was pressed on a table press with cover layers of the same material. This table press is the Polystat 200 T from Schwabenthan, with which the honeycomb structure was pressed at 130 to 140 ° C with cover layers of the same fibrous matrix matrix to the corresponding fiber composite panels. The pressure was varied between normal pressure and 450 bar. Dynamic compression, ie changing pressures can be depending on the component size, thickness and polyurethane composition and thus the Viscosity adjustment at the processing temperature for the wetting of the fibers prove to be advantageous.

In one example, the temperature of the press was maintained at 135 ° C, the pressure was increased after a reflow phase of 3 minutes to 440 bar and held until removal of the composite component from the press after 30 minutes at this level.

The obtained hard, stiff, chemical resistant and impact resistant

Fiber composite components 4 with a fiber volume fraction of> 50% were examined with respect to the degree of cure (determined by DSC). The determination of

Glass transition temperature of the cured matrix shows the progress of crosslinking at different curing temperatures. In the used

Polyurethane composition is complete after about 25 minutes, the crosslinking, in which case no reaction enthalpy for the crosslinking reaction is more detectable. The results are shown in FIG.

Two composites were produced under exactly the same conditions and

then their properties are determined and compared. This good reproducibility of the properties was also confirmed in the determination of interlaminar shear strength (ILSF). Here, an average ILSF of 44 N / mm ^{2 was} achieved with a fiber volume fraction of 54 and 57%, respectively.

Instead of the "classical" honeycomb structure shown (position 3 of FIG. 5), the walls of the semifinished product can also assume the meandering shape of bump plates

Core structure for composite components in lightweight construction. In the manufacture of bump plates, flat walls are embossed with a plurality of polygonal protuberances projecting from the plane. Octagonal and hexagonal bumps are particularly suitable for the semi-finished products according to the invention. But also quadrangular and triangular formations are possible. These are particularly well suited for use as the core of a sandwich.

Compared with the walls of the classical honeycomb pattern, the humps meander in two dimensions; meanwhile the honeycomb walls meander in one dimension only. The bump plates are like honeycomb walls offset from each other added together, so that a symmetrical core structure is formed. In contrast In comparison to conventional honeycomb cores, this new structure provides a high joining surface for the cover layer connection.

In connection with the matrix material presented here, bump plates can be produced particularly advantageously, since the uncured polymer composition permits a very steep bump design and thus permits extreme constructions which are not readily producible in metal.

Bump plates and related manufacturing processes are used inter alia in

DE102006031696A1, DE102005026060A1, DE102005021487A1, DE19944662A1, DE10252207B3, DE10241726B3, DE10222495C1 and DE10158276C1 discloses. As far as the deformation is described in the sheet metal processing, this technology is also applicable to the present matrix materials.

Claims

claims

1 . Semifinished product for the production of fiber composite components, comprising at least two meandering angled walls of fiber-filled matrix material, which form a symmetrical core structure forming thermally joined together,

characterized,

in that the matrix material is a polyurethane composition which

c) as a binder an isocyanate-reactive functional groups

having polymers,

d) and as a hardener internally and / or blocked with blocking agents di- or

polyisocyanate

contains.

2. Semifinished product according to claim 1,

marked by

at least one cover layer applied to the core structure, wherein the core structure and the cover layer are joined in a material-locking manner.

3. Semifinished product according to claim 2,

characterized,

that the cover layer comprises fiber-filled matrix material which is a polyurethane composition,

a) which as binders a isocyanate-reactive functional group-containing polymers

b) and as hardener internally and / or blocked with blocking agents di- or

polyisocyanate

contains

and that the cover layer and core structure are thermally joined.

4. Method for producing a semifinished product,

characterized by the following steps: a) providing a polyurethane composition containing as binder a polymer having isocyanate-reactive functional groups and as hardener internally and / or blocked with blocking agents di- or polyisocyanate

b) providing fibers,

c) mixing the polyurethane composition and the fibers into one

Molding compound

d) forming the molding material into a flat wall,

e) reshaping the wall to give it a meandering angled shape, f) aligning the meandering angled wall to another

meandering angled wall,

g) thermal joining of at least the two walls to a symmetrical

Core structure.

5. The method according to claim 4,

characterized by the additional steps of: h) applying a cover layer to the core structure, wherein the cover layer comprises a fiber filled matrix material which is a

Polyurethane composition containing as binder a isocyanate-reactive functional group-containing polymers and as a hardener internally and / or blocked with blocking agents di- or polyisocyanate,

i) thermal joining of the cover layer with the core structure.

6. The method according to claim 4 or 5,

characterized,

the thermal joining takes place at a temperature below the curing temperature of the polyurethane composition.

7. Method for producing a fiber composite component,

characterized by the following steps:

a) providing a semifinished product produced according to one of claims 4 to 6, b) curing the polyurethane composition at a temperature above the temperature during thermal joining.

8. fiber composite component produced from a semifinished product according to one of claims 1 to 3, in particular produced by a method according to claim 7.