Storage-stable polyurethane prepregs and mouldings produced therefrom composed of a polyurethane composition with liquid resin components

Abstract

Provided is a storage-stable polyurethane prepegs and mouldings produced therefrom composed of polyurethane compositions with liquid resin components, preferably liquid polyols. A prepeg contains(A)a fibrous support and (B)a matrix material containing a reactive polyurethane composition. The polyurethane composition contains a mixture of a liquid resin component(b)having a functional group reactive towards an isocyanate and having a glass transition temperature(Tg)or melting point below 25 C., with a hydroxyl number of 50 to 2000 mg KOH/gram, and a curing agent(a)comprising a di- or polyisocyanate internally blocked or blocked with a blocking agent. In addition, the polyurethane composition contains 0.6 to NCO equivalents or 0.3 to 1 uretdione group in (a) for each functional group of (b).

Claims

1. A prepreg, comprising: A) a fibrous support and B) a reactive polyurethane composition comprising: a) a curing agent containing uretdione groups, based on polyaddition compounds from aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates containing uretdione groups and hydroxyl group-containing compounds, where the curing agent exists in solid form below 40 C. and in liquid form above 110 C., and has a free NCO content of less than 5 wt.% and a uretdione content of 3-25 wt.%, b) at least one hydroxyl group-containing liquid resin component b) having a glass transition temperature (Tg) or melting point below 25 C. and an OH number between 50 and 2000 mg KOH/gram, c) optionally at least one catalyst, d) optionally auxiliary substances and additives, wherein components a) and b) are present in a ratio such that there is from 0.3 to 1 uretdione group of component a) for each hydroxyl group of component b) and the curing agent does not comprise an external blocking agent.

2. The prepreg of claim 1, wherein a melting point of the reactive polyurethane composition is at least 30 C.

3. The prepreg of claim 1, wherein a glass transition temperature (Tg) of the reactive polyurethane composition is at least 30 C.

4. The prepreg of claim 1, wherein the fibrous support comprises a glass fiber, a carbon fiber, a plastic fiber, a natural fiber or a mineral fiber.

5. The prepreg of claim 1, wherein the fibrous support comprises a planar textile body of non-woven material, a knitted good, or a non-knitted skein.

6. The prepreg of claim 1, wherein the aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanate is at least one member 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-trimethyl-hexamethylene diisocyanate (TMDI), and norbornane diisocyanate (NBDI).

7. The prepreg of claim 1, wherein the aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanate comprises an isophorone diisocyanate adduct comprising an isocyanurate grouping.

8. The prepreg of claim 1, wherein the reactive polyurethane composition comprises the at least one catalyst c) and a content of the catalyst c) is from 0.001 to 1 wt.% based on the total weight of the reactive polyurethane composition.

9. The prepreg of claim 1, wherein the prepreg comprises the at least one catalyst c): a content of the catalyst c) is from 0.1 to 5 wt.%, based on the total weight of the reactive polyurethane composition, the catalyst c) comprises a quaternary ammonium salt or a quaternary phosphonium salt, having a halogen, a hydroxide, an alcoholate, or an organic or inorganic acid anion as a counter-ion; and the prepeg comprises at least one cocatalyst as additive d), a content of the at least one cocatalyst is from 0.1 to 5 wt.%, based on the total weight of the reactive polyurethane composition, and the at least one cocatalyst is selected from the group consisting of d1) and d2): d1) an epoxide and d2) a metal acetylacetonate, a quaternary ammonium acetylacetonate, or a quaternary phosphonium acetylacetonate; and the prepeg further optionally comprises e) an auxiliary substance or additive.

10. The prepreg of claim 1, which comprises the at least one catalyst c) and the catalyst c) is selected from the group consisting of tetramethylammonium fotimiate, tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium butyrate, tetramethylannnonium benzoate, tetraethylaminoniumn formate, tetraethylammoniinn 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 tetrabutyl-ammonium benzoate and tetrabutylphosphonium acetate, tetrabutylphosphonium formate and ethyltriphenylphosphonium acetate, tetrabutylphosphonium benzotriazolate, tetraphenyl-phosphonium phenolate and trihexylletradecylphosphonium decanoate, methyltributyl-ammonium hydroxide, methyltriethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetrabutyl-ammonium hydroxide, tetradecylammonium hydroxide, tetradecyltrihexylammonium hydroxide, tetraoctadecylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, trimethylphenylammonium hydroxide, triethylmethyl-ammonium hydroxide, trimethylvinylammonium hydroxide, methyltributylammonium methanolate, methyltriethylammonium methanolate, tetramethylammonium methanolate, tetraethylammonium methanolate, tetrapropylammonium methanolate, tetrabutylammonium methanolate, tetrapentylammonium methanolate, tetrahexylammonium methanolate, tetraoctylammonium methanolate, tetradecylammonium methanolate, tetradecyltrihexyl-ammonium methanolate, tetraoctadecylammonium methanolate, benzyltrimethylammonium methanolate, benzyltriethylammonium methanolate, trimethylphenylammonium methanolate, triethylmethylammonium methanolate, trimethylvinylammonium methanolate, methyltributyl-ammonium ethanolate, methyltriethylammonium ethanolate, tetramethylammonium ethanolate, tetraethylammonium ethanolate, tetrapropylammonium ethanolate, tetrabutyl-ammonium ethanolate, tetrapentylammonium ethanolate, tetrahexylammonium ethanolate, tetraoctylammonium methanolate, tetradecylammonium ethanolate, tetradecyltrihexyl-ammonium ethanolate, tetraoctadecylammonium ethanolate, benzyltrimethylammonium ethanolate, bertzyltriethylammonium ethanolate, trimethylphenylammonium ethanolate, triethylmethylammonium ethanolate, trimethylvinylammonium ethanolate, methyltributyl-ammonium benzylate, methyltriethylammonium benzylate, tetramethylammonium benzylate, tetraethylammonium benzylate, tetrapropylammonium benzylate, tetrabutylammonium benzylate, tetrapentylanamonium benzylate, tetrahexylanmionium benzylate, tetraoctyl-ammonium benzylate, tetradecylammonium benzylate, tetradecyltrihexylammonium benzylate, tetraoctadecylammonium benzylate, benzyltrimethylammonium benzylate, benzyhriethylammonium benzylate, trimethylpheitylammonium benzylate, triethylmethyl-ammonium benzylate, trimethylvinylarnmonium benzylate, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrabutylammonium fluoride, tetraoctylammonium fluoride, benzyltrimethylammonium fluoride, tetrabutylphosphonium hydroxide, tetrabutyiphosphonium fluoride, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethyl-ammonium iodide, benzyltrimethylammonium chloride, benzyltriethylarnmonium chloride, benzyltripropylammonium chloride, benzyltributylammonium chloride, methyltributyl-ammonium chloride, methyltripropylammonium chloride, methyltriethylammonium chloride, methyltriphenylammoniurn chloride, phenyltrimethylammonium chloride, benzyltrimethyl-ammonium bromide, benzyltriethylammonium bromide, benzyltripropylammonium bromide, benzyltributylammonium bromide, methyltributylammonium bromide, methyltripropyl-ammonium bromide, methyltriethylammonium bromide, methyltriphenylammonium bromide, phenyltrimethylammonium bromide, benzyltrimethylammonium iodide, benzyltriethyl-ammonium iodide, benzyltripropylammonium iodide, benzyltributylammonium iodide, methyltributylammonium iodide, methyltripropylammonium iodide, methyltriethylammonium iodide, methyhriphenylammonium iodide and phenyltrimethylammonium iodide, methyl-tributylammonium hydroxide, methyltriethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutyl-ammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, tetradecylammonium hydroxide, tetradecyhrihexylammonium hydroxide, tetraoctadecylarrimonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, trimethylphenylammonium hydroxide, triethytmethyl-ammonium hydroxide, trimethylvinylammonium hydroxide, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrabutylarrmionium fluoride, tetraoctylammonium fluoride and benzyltrimethylammonium fluoride.

11. The prepreg of claim 9, comprising the cocatalyst d1), wherein the cocatalyst d1) is at least one member selected from the group consisting of a glycidyl ether, a glycidyl ester, an aliphatic epoxide, and a diglycidyl ether based on bisphenol A and a glycidyl methacrylate.

12. The prepreg of claim 9, comprising the cocatalyst d2), wherein the cocatalyst d2) is a least one member selected from the group consisting of zinc acetylacetonate, lithium acetylacetonate and tin acetylacetonate.

13. The prepreg of claim 9, comprising the cocatalyst d2), wherein the cocatalyst d2) is at least one member selected from the group consisting of tetramethylammonium acetylacetonate, tetraethylammonium acetylacetonate, tetrapropylammonium acetylacetonate, tetrabutylammonium acetylacetonate, benzyltrimethylammonium acetylacetonate, benzyltriethylammonium acetylacetonate, tetramethylphosphonium acetylacetonate, tetraethylphosphonium acetylacetonate, tetrapropylphosphonium acetylacetonate, tetrabutylphosphonium acetylacetonate, benzyltrimethylphosphonium acetylacetonate, and benzyltriethylphosphonium acetylacetonate.

14. The prepreg of claim 1, wherein the resin component b) is liquid from 20 to 23 C.

15. The prepreg of claim 1, wherein the liquid resin component b) comprises at least one member selected from the group consisting of a monomeric-polyol, a polyester, a polycaprolactone, a polyether, a polyacrylate, a polycarbonate and a polyurethane, having an average molar mass of 62 to 3000 g/mol.

16. The prepreg of claim 1, wherein the liquid resin component b) comprises a polyol having a hydroxyl number number of 200 to 1500 mg KOH/gram.

17. The prepreg of claim 1, wherein the liquid resin component b) comprises a polyol having an average molecular weight of 100 to 1000 g/mol.

18. The prepreg of claim 1, wherein the liquid resin component b) comprises a polyol having a hydroxyl number number of 501 to 1000 mg KOH/gram, and which is liquid at 20 to 23 C.

19. The prepreg of claim 1, having a fiber volume content of more than 10%.

20. The prepreg of claim 1, consisting essentially of the fibrous support A) and the reactive polyurethane composition B) and the prepreg is attached to C) at least one foil fixed on the prepreg via the polyurethane composition.

21. A process for producing the prepreg of claim 1, the process comprising producing the reactive polyurethane composition, and impregnating the fibrous support with the polyurethane composition, which has optionally been dissolved in solvent, and optionally removing the solvent.

22. A direct melt impregnation process for producing the prepreg of claim 1, the process comprising producing the reactive polyurethane composition in a melt, and directly impregnating the fibrous support with the melt.

23. A composite component comprising, in reacted form, the prepreg of claim 1.

24. A composite component comprising, in reacted form, the prepreg of claim 1, wherein the polyurethane composition is crosslinked.

25. The prepreg of claim 1, which is storage-stable and does not undergo polymerization in storage for 28 days at 40 C.

Description

EXAMPLES

(1) Glass Fibre Nonwovens/Fabrics Used:

(2) The following glass fibre nonwovens/fabrics were used in the examples:

(3) Glass filament fabric, 296 g/m.sup.2Atlas, Finish FK 144 (Interglas 92626)

(4) Production of the Uretdione-Containing Curing Agent H:

(5) 119.1 g of IPDI uretdione (Evonik Degussa GmbH) were dissolved in 100 ml of butyl acetate, 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. No residual free NCO groups were then detectable by titration. The curing agent H has an effective latent NCO content of 12.8% by weight (based on solid).

(6) Reactive Polyurethane Composition

(7) Reactive polyurethane compositions were used for the production of the prepregs and the composites.

(8) TABLE-US-00002 Comparative Example 1 (not according to the invention) Curing agent H Curing component a) 25.5% by wt. Evonik (60%) containing Industries (effective uretdione groups NCO: 7.7%) Uralac P1580 Hydroxyl 34.7% by wt. Cytec (OHN 83 mg polyester Industries KOH/g) resin b) Inc. molar mass about 1500 g/mol Tg 51 C. Benzoin Devolatizing 0.2% by wt. Aldrich agent Butyl acetate Solvent c) 39.8% by wt. Fluka

(9) TABLE-US-00003 Inventive Example 2 (according to the invention) Curing agent H Curing component a) 65.3% by wt. Evonik (60%) containing Industries (effective uretdione groups NCO: 7.7%) Polyol 4640 Polyol b) 10.9% by wt. Perstorp (OHN 630 mg KOH/g) molar mass 360 g/mol liquid Benzoin Devolatizing 0.2% by wt. Aldrich agent Butyl acetate Solvent c) 23.9% by wt. Fluka

(10) TABLE-US-00004 Inventive Example 3 (according to the invention) Curing agent H Curing component a) 68.5% by wt. Evonik (60%) containing Industries (effective uretdione groups NCO: 7.7%) Voranol 490 Polyol b) 13.9% by wt. Dow (OHN 490 mg KOH/g) molar mass 490 g/mol liquid Benzoin Devolatizing 0.2% by wt. Aldrich agent Butyl acetate Solvent c) 17.4% by wt. Fluka

(11) TABLE-US-00005 Inventive Example 4 (according to the invention) catalysed Curing agent H Curing component a) 60.1% by wt. Evonik (60%) containing Industries (effective uretdione groups NCO: 7.7%) Polyol 4640 Polyol b) 8.5% by wt. Perstorp (OHN 630 mg KOH/g) molar mass 360 g/Mol liquid Tetraethyl- Catalyst 0.5% by wt. Evonik ammonium Industries benzoate Araldit PT 912 Epoxide 1.5% by wt. Huntsman Oxalic acid Acid 0.2% by wt. Aldrich Benzoin Devolatizing 0.2% by wt. Aldrich agent Butyl acetate Solvent c) 30.4% by wt. Fluka
OHN=hydroxyl number

(12) The starting materials from the table were mixed intimately in a premixer and then dissolved in the stated solvent.

(13) For the production of the prepreg, the glass fibre fabric was impregnated with the solution of the matrix materials. The prepregs were dried to constant weight in an oven at temperatures of 50 to 70 C., with application of vacuum. The fibre mass content was determined as 49% in Comparative Example 1 (10 tests), 55% in Inventive Example 2 (10 tests), 48% in Inventive Example 3 (10 tests) and 52% in Inventive Example 4 (10 tests).

(14) The prepreg of Comparative Example 1 exhibited severe blistering during removal of the solvent, presumably because of the high viscosity, and this gave a very irregular surface.

(15) This prepreg could not therefore be further processed.

(16) The prepreg according to the invention of Inventive Example 2 gave, in contrast, after removal of the solvent, a coherent surface without blistering. This prepreg could be further processed successfully. The prepreg according to the invention of Inventive Example 3 gave, after removal of the solvent, a coherent surface with little blistering. This prepreg could be further processed successfully, although not as successfully as Inventive Example 2. The prepreg according to the invention of Inventive Example 4 gave, after removal of the solvent, a coherent surface without blistering. This prepreg could be further processed successfully.

(17) DSC Measurements

(18) The DSC tests (glass transition temperature determinations and enthalpy of reaction measurements) are performed with a Mettler Toledo DSC 821e as per DIN 53765.

(19) The DSC studies on the prepregs from Examples 1 and 2 give the following results:

(20) TABLE-US-00006 TABLE 1 DSC studies prior to and after storage at 40 C. CEx. Inv. Inv. Inv. 1 Ex. 2 Ex. 3 Ex. 4 Exothermic peak (1st heating 200 203 196 174 procedure) in C. Exothermic peak (1st heating 36 95 103 39 procedure), enthalpy of reaction in J/g Tg (2nd heating procedure) in C. 94 97 119 121 Exothermic peak (1st heating 203 202 198 180 procedure) in C. after 28 days of storage at 40 C. Exothermic peak (1st heating 33 90 98 51 procedure), enthalpy of reaction in J/g after storage for 28 days at 40 C. Tg (2nd heating procedure) in C. 92 96 103 117 after 28 days of storage at 40 C.

(21) The glass transition temperatures measured in the second heating procedure are the glass transition temperatures of the fully crosslinked/reacted matrix material.

(22) The DSC studies on the prepregs from Examples 1, 2, 3 and 4 prior to and after storage can be found in Table 1. The enthalpies of reaction measured for the prepregs according to the invention of Inventive Examples 2, 3 and 4 do not decrease significantly during the course of storage, and this is evidence of the storage stability of the matrix material.

(23) Composite Component Production

(24) The composite components were produced on a composite press by a compression technique known to those skilled in the art. The homogeneous prepregs produced by direct impregnation were compressed into composite materials on a benchtop press. This benchtop press is the Polystat 200 T from the firm Schwabenthan, with which the prepregs were compressed to the corresponding composite sheets at temperatures between 120 and 200 C. The pressure was varied between normal pressure and 450 bar.

(25) In Inventive Examples 2 and 3, the temperature of the press was set to 150 C. and increased to 180 C. during the course of the pressing process, and the pressure was increased to 5 bar after a short melting phase of 3 minutes and was retained until removal of the composite component from the press after up to 30 minutes. The hard, rigid, chemicals resistant and impact resistant composite components (sheet products) were tested for degree of curing (determination by DSC). With the polyurethane composition used, crosslinking is complete after about 20 minutes, whereupon there is also no residual enthalpy of reaction detectable for the crosslinking reaction.

(26) In Inventive Example 4 (catalysed version), the temperature of the press was set to 150 C. and increased to 180 C. during the course of the pressing process, and the pressure was increased to 5 bar after a short melting phase of 3 minutes and was retained until removal of the composite component from the press after up to 10 minutes. The hard, rigid, chemicals resistant and impact resistant composite components (sheet products) were tested for degree of curing (determination by DSC). With the polyurethane composition used, crosslinking is complete after about 20 minutes, whereupon there is also no residual enthalpy of reaction detectable for the crosslinking reaction.

(27) Blistering prevented pressing of the prepreg of Comparative Example 1, which is not according to the invention.