Composite semifinished products and mouldings produced therefrom and directly produced mouldings based on hydroxy-functionalized (meth)acrylates and uretdiones which are crosslinked by means of radiation to give thermosets

Abstract

The invention relates to a process for producing storage-stable polyurethane prepregs and to moldings (composite components) produced therefrom. The prepregs and, respectively, components are produced by mixing (meth)acrylate monomers, (meth)acrylate polymers, hydroxy-functionalized (meth)acrylate monomers and/or hydroxy-functionalized (meth)acrylate polymers with uretdione materials. Photoinitiators can also optionally be added. This mixture or solution is applied by known processes to fiber material, e.g. carbon fibers, glass fibers or polymer fibers, and is polymerized with the aid of radiation or of plasma methods. Polymerization, e.g. at room temperature or at up to 80 C., gives thermoplastics or thermoplastic prepregs, and these can subsequently also be subjected to forming processes. The hydroxy-functionalized (meth)acrylate constituents can then be crosslinked with the uretdiones already present within the system, by use of elevated temperature. It is thus possible to produce dimensionally stable thermosets or dimensionally stable crosslinked composite components.

Claims

1. A process for producing a composite moulding, comprising: i) preparing a reactive composition comprising: a (meth)acrylate monomer having one group selected from the group consisting of a hydroxyl group, an amine group and a thiol group; a reactive resin component based on (meth)acrylate wherein at least one constituent of the resin component has hydroxy groups, amine groups and/or thiol groups, a blocked di- or poly-isocyanate, wherein the di- or poly-isocyanate is blocked with a blocking agent or is internally blocked, and at least one photoinitiator; ii) directly impregnating a fibrous substrate with the reactive composition; iii) hardening the reactive composition impregnated in the fibrous substrate by exposure to ultraviolet radiation to obtain a composite; iv) shaping the composite product; and v) crosslinking the hardened shaped composite by heat treatment at a temperature from 80 C. to 220 C. to obtain the composite moulding.

2. The process according to claim 1, wherein a quantitative ratio of the reactive resin component to the blocked di- or poly-isocyanate component is from 90:10 to 50:50.

3. The process according to claim 1, wherein the reactive resin component comprises in polymerized form: from 0% by weight to 30% by weight of crosslinking agents, from 30% by weight to 100% by weight of monomers, from 0% by weight to 40% by weight of prepolymers.

4. The process according to claim 1, wherein the reactive composition comprises: from 0% by weight to 30% by weight of blocked di- or poly-isocyanate crosslinking agents, from 30% by weight to 99% by weight of monomers, from 1% by weight to 20% by weight of urethane (meth)acrylates, from 0% by weight to 40% by weight of prepolymers and from greater than 0% by weight to 10% by weight of the photoinitiator.

5. The process according to claim 1, wherein the photoinitiator comprises at least one of a hydroxyketone and a bisacylphosphine, and a concentration of the photoinitiator is from 0.2 to 10.0% by weight.

6. The process according to claim 1, wherein the fibrous substrate comprises at least one material selected from the group consisting of glass, carbon, a plastic, a natura fibre, and a mineral material, and wherein the fibrous substrate is a textile sheet made of non-woven knitted fabrics or non-knitted structures.

7. The process according to claim 1, wherein the di- or polyisocyanate is at least one selected from the group consisting of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), diisocyanatodicyclohexylmethane (H.sub.12MDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate/2,4,4-trimethylhexamethylene diisocyanate (TMDI) and norbornane diisocyanate (NBDI), and the di- or polyisocyanate is blocked with at least one external blocking agent selected from the group consisting of ethyl acetoacetate, diisopropylamine, methyl ethyl ketoxime, diethyl malonate, -caprolactam, 1,2,4-triazole, phenol or substituted phenols and 3,5-dimethylpyrazole.

8. The process according to claim 1, wherein the reactive composition further comprises from 0.01 to 5.0% by weight of catalysts.

9. The process according to claim 1, wherein the isocyanate component further comprises uretdiones produced from at least one selected from the group consisting of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), diisocyanatodicyclohexylmethane (H.sub.12MDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate/2,4,4-trimethylhexamethylene diisocyanate (TMDI) and norbornane diisocyanate (NBDI).

10. The process according to claim 9, wherein: the blocked di- or poly-isocyanate is in a solid form at below 40 C. and in a liquid form at above 125 C., and has less than 5% by weight of free NCO groups and from 3 to 25% by weight of the uretdiones, and the blocked di- or poly-isocyanate further comprises from 0.01 to 5% by weight of at least one catalyst selected from a quaternary ammonium salt and a quaternary phosphonium salt having halogens, hydroxides, alcoholates, organic or inorganic acid anions as counterions.

11. The process according to claim 9, wherein the blocked di- or poly-isocyanate further comprises from 0.1 to 5% by weight of at least one co-catalyst selected from the group consisting of an epoxide, a metal acetylacetonate, a quaternary ammonium acetylacetonate, and a quaternary phosphonium acetylacetonate, and optionally further comprises known polyurethane-chemistry auxiliaries and known polyurethane-chemistry additives.

12. The process according to claim 1, wherein the resin component and the blocked di- or poly-isocyanate isocyanate component are present in a ratio in relation to one another such that for each hydroxy group of the resin component, the number of internally blocked di- or polyisocyanates of the isocyanate component is from 0.3 to 1.0.

13. A moulding produced by the process according to claim 1, comprising: at least one fibrous substrate, and at least one crosslinked reactive composition comprising a hardened (meth)acrylate resin as a matrix.

14. A boat, a ship, an aircraft, a space craft, an automobile, a bicycle, a motorcycle, a pedal cycle, an automotive, a construction, a medical device, a sporting device, an electrical device, an electronic device or a power-generating system, comprising the moulding according to claim 13.

15. A process for producing a composite moulding, comprising: i) preparing a reactive composition comprising: a (meth)acrylate monomer having one group selected from the group consisting of a hydroxyl group, an amine group and a thiol group; a reactive resin component based on (meth)acrylate wherein at least one constituent of the resin component has hydroxy groups, amine groups and/or thiol groups, a blocked di- or poly-isocyanate, wherein the di- or poly-isocyanate is blocked with a blocking agent or is internally blocked; ii) directly impregnating a fibrous substrate with the reactive composition; iii) hardening the reactive composition impregnated in the fibrous substrate by exposure to an electron beam or with an atmospheric-pressure plasma; iv) shaping the composite product; and v) crosslinking the hardened shaped composite by heat treatment at a temperature from 80 C. to 220 C.; wherein when the hardening is obtained by atmospheric-pressure plasma, the plasma is generated away from the composite and is blown with high flow velocity onto the impregnated fibrous substrate.

Description

EXAMPLES

(1) The examples use the following glass-fibre laid scrims/woven glass-fibre fabrics: woven glass-filament fabric, 296 g/m.sup.2Atlas, finish FK 144 (Interglas 92626)

(2) Production of uretdione-containing hardener H:

(3) 119.1 g of IPDI uretdione (Evonik Degussa GmbH) were dissolved in 100 ml of methyl methacrylate, and 27.5 g of methylpentanediol and 3.5 g of trimethylolpropane were admixed therewith. After addition of 0.01 g of dibutyltin dilaurate, the mixture was heated to 80 C. for 4 h, with stirring. There were then no remaining NCO groups detectable titrimetrically. The effective latent NCO content of the hardener H is 12.8% by weight (based on solids).

(4) Reactive Polyurethane Composition

(5) Reactive polyurethane compositions with the following formulations were used for producing the prepregs and the composites.

(6) Comparative Example 1 corresponds to the teaching of WO 2011/071450.

(7) TABLE-US-00001 Comparative Example 1 Hardener H Hardener component 53.3% by wt. Evonik (60% in MMA) a) containing Industries AG (effective NCO: 7.7%) uretdione groups Hydroxypropyl Reactive diluent 14.0% by wt Evonik acrylate containing OH Industries AG Lamination resin C Methacrylate resin 8.2% by wt Evonik Industries AG Methyl methacrylate Reactive diluent 22.7% by wt Evonik (MMA) Industries AG Dibenzoyl peroxide Free-radical initiator 0.9% by wt Fluka N,N-bis(2-hydroxy- Accelerator 0.9% by wt Aldrich ethyl)-p-toluidine

(8) The starting materials from the table were intimately mixed in a premixer and then dissolved. This mixture can be used for about 2-3 h before it gels.

(9) To produce the prepregs, the woven glass-fibre fabric was saturated with the solution of the matrix materials. The prepregs were dried to constant weight for 30 min in an oven at temperatures of 60 C. Fibre content by mass was determined as 47% in Example 1.

(10) The prepreg of Example 1 exhibited a weight loss after drying of about 34%, based on matrix. The impregnated glass-fibre mats were pressed at 180 C. and 50 bar for 1 h (Polystat 200 T from Schwabenthan) and thus fully crosslinked. The Tg of the hard, stiff, chemicals-resistant and impact-resistant composite components (sheet material) was 119 C.

(11) TABLE-US-00002 Example 1 (according to the invention) Hardener H Hardener component 53.3 wt % Evonik (60% in MMA) a) containing Industries AG (effective NCO: 7.7%) uretdione groups Hydroxypropyl acrylate Reactive diluent 14.0 wt % Evonik containing OH Industries AG Lamination resin C Methacrylate resin 8.2 wt % Evonik Industries AG Methyl methacrylate Reactive diluent 22.7 wt % Evonik Industries AG Irgacure 819 Photoinitiator 1.8 wt % Ciba

(12) The starting materials from the table were intimately mixed in a premixer and then dissolved. If light is excluded, this mixture can be stored for about 1-2 years without gelling.

(13) To produce the prepreg, the woven glass-fibre fabric was saturated with the solution of the matrix materials. The material was then dried at 1.5 m/min under a UV LED lamp (Heraeus NobleCure, based on water-cooled heat sink,

(14) wavelength: 3955 nm, power density: 8 W/cm.sup.2 at operating distance of 5 mm,

(15) emission window: 25135 mm.sup.2). Fibre content by mass was determined as 54% in Example 2.

(16) The prepreg of Example 2 exhibited a weight loss after drying of about 12%, based on matrix.

(17) The impregnated glass-fibre mats were pressed at 180 C. and 50 bar for 1 h (Polystat 200 T from Schwabenthan). The Tg of the hard, stiff, chemicals-resistant and impact-resistant composite components (sheet material) was 123 C.

(18) It was thus possible to show that the process of the invention can significantly reduce the loss of reactive diluent.