Compositions Comprising a Fiber Material and a Thermoplastic Binder

Abstract

The invention relates to compositions comprising a fiber material and a specific thermoplastic binder. The thermoplastic binder comprises at least one thermoplastic polyurethane polymer, wherein said thermoplastic polyurethane polymer comprises a reaction product of (i) at least one semi-crystalline polyester polyol, and (ii) at least one polyisocyanate. The molar ratio of the NCO groups of said polyisocyanate (ii) to the sum of OH groups of said polyester polyol (i) is less than 1.00:1 and the thermoplastic polyurethane polymer has (a) a melting enthalpy of at least 20 J/g, (b) a melting point (T.sub.m) of >70 C., and (c) an average number molecular weight (M.sub.n) of 5,000 to 80,000 g/mol. Furthermore, the present invention relates to a fiber-reinforced composite comprising a cured thermosetting polyurethane polymer matrix reinforced by the composition according to the present invention. Moreover, a method for the manufacture of the fiber-reinforced composite according to the present invention and use of the composition or the fiber-reinforced composite in railway vehicles, automotive vehicles, aircraft vehicles, boats, space vehicles, motorbikes, bicycles, sporting goods, helmets, functional clothing, shoes, construction parts in bridges and buildings or wind turbine blades are described.

Claims

1. A composition comprising a fiber material and a thermoplastic binder, wherein the thermoplastic binder comprises at least one thermoplastic polyurethane polymer that is a reaction product of: (i) at least one semi-crystalline polyester polyol having a melting point (T.sub.m) of from 40 to 180 C.; and (ii) at least one polyisocyanate; wherein the molar ratio of the NCO groups of said polyisocyanate (ii) to the sum of OH groups of said at least one semi-crystalline polyester polyol (i) is less than 1.00:1; and the thermoplastic polyurethane polymer has (a) a melting enthalpy of at least 20 J/g, (b) a melting point (T.sub.m) of >70 C., and (c) an average number molecular weight (M.sub.n) of 5,000 to 80,000 g/mol.

2. The composition according to claim 1, wherein said thermoplastic polyurethane polymer has an equivalent weight of 3500 to 15000 g/eq.

3. The composition according to claim 1, wherein the thermoplastic binder comprises 50 to 99.9 wt.-% of the at least one thermoplastic polyurethane; and 0.1 to 50 wt.-% of additives, based on the total weight of the said thermoplastic binder.

4. The composition according to claim 1, wherein the thermoplastic binder comprises 0.1 to 50 wt.-% of additives, based on the total weight of the said thermoplastic binder, and is selected from stabilizer, adhesion promoter, filler, plasticizer, further thermoplastic polymers which are different from the at least on thermoplastic polyurethane copolymer, or a combination thereof.

5. The composition according to claim 1, comprising 0.1 to 40 wt.-% of the thermoplastic binder; and 60 to 99.9 wt.-% of the fiber material, based on the total weight of said composition.

6. The composition according to claim 1, wherein the fiber material contains fibers selected from glass fibers, synthetic fibers, carbon fibers, boron fibers, ceramic fibers, metal fibers, natural fibers and combinations thereof.

7. The composition according to claim 1, wherein the fiber material is in the form of a mat, woven fabric, nonwoven fabric, non-crimped fabric, knitted fabric, plies, or roving.

8. The composition according to claim 1, wherein the at least one polyester polyol contains at least two hydroxyl groups.

9. The composition according to claim 1, wherein the at least one polyester polyol is formed through a condensation reaction of one or more polyhydric alcohols having from 2 to 30 carbon atoms with one or more polycarboxylic acids having 2 to 14 carbon atoms.

10. The composition according to claim 1, wherein the at least one polyisocyanate has a molecular weight from 160 g/mol to 500 g/mol.

11. The composition according to claim 1, wherein the at least one polyisocyanate is selected from the group consisting of the isomers of diphenymethanediisocyanate (MDI), the isomers of phenylenediisocyanate, naphthalene-1,5-diisocyanate (NDI), the isomers of toluenediisocyanate (TDI), m- and p-tetramethyl xylylene diisocyanate (TMXDI), m- and p-xylylenediisocyanate (XDI), 3,3-dimethyldiphenyl-4,4-diisocyanate (TODD, toluene diisocyanate, di- and tetraalkyl diphenylmethane diisocyanate, 4,4-dibenzyl diisocyanate and combinations thereof.

12. The composition according to claim 1, wherein the at least one polyisocyanate is selected from the group consisting of ethylene diisocyanate, dodecane diisocyanate, dimer fatty acid diisocyanate, 4,4-dibenzyldiisocyanate, 1,6-diisocyanato-2,2,4-trimethylhexane, butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), tetramethoxybutane-1,4-diisocyanate, 1,12-diisocyanato-dodecane, 4,4-dicyclohexylmethanediisocyanate, 1,3-cyclohexane or 1,4-cyclohexane diisocyanate, 1-methyl-2,4-d iisocyanato-cyclohexane, 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), hydrogenated or partly hydrogenated MDI ([H]12MDI (hydrogenated) or [H]6MDI (partly hydrogenated), and combinations thereof.

13. A fiber-reinforced composite comprising a cured thermosetting polyurethane polymer matrix reinforced by cured reaction products of the composition according to claim 1, wherein the fiber material comprises more than 30% by volume of the fiber-reinforced composite based on the total volume of the fiber-reinforced composite.

14. The fiber-reinforced composite according to claim 13, wherein the cured thermosetting polyurethane polymer matrix is a reaction product of a two-component polyurethane matrix resin comprising: at least one polyol (I) having a number average molecular weight (M.sub.n) of less than 3,000 g/mol; and at least one polyisocyanate (II); wherein the molar ratio of the OH groups of said polyol (I) to the NCO groups of said polyisocyanate (II) is from 2:1 to 1:2.

15. A method for the manufacture of fiber-reinforced composites according to claim 13, comprising: providing an external mold; providing the composition according to claim 1; disposing the composition according to claim 1 into the mold; introducing the uncured thermosetting polyurethane polymer matrix into said mold under pressure and/or vacuum; and curing said composition at a temperature of up to 140 C.

16. A railway vehicle, automotive vehicle, aircraft vehicle, boat, space vehicle, motorbike, bicycle, sporting good, helmet, functional clothing, shoe, construction part in a bridges, construction part in a building or wind turbine blade comprising the composition according to claim 1 or the fiber-reinforced composite according to claim 13.

Description

EXAMPLES

[0090] Methods

[0091] The following measurement methods are employed in the present invention if not explicitly stated otherwise.

Melting Point and Tg

[0092] The melting enthalpy, Tg and melting point are, if not indicated otherwise, determined using an analytical-balance capable of measuring to 0.1 mg and a Mettler Toledo TA Instruments Q20 DSC unit. The DSC is calibrated using an Indium standard. For the actual measurement, 5 to 10 mg of sample is weighed into an aluminum DSC pan and the lid fixed securely. The temperature of the DSC chamber is set at 40 C. prior to use. The sample pan and reference pan (blank) is placed into the DSC cell chamber. The temperature is reduced to 0 C. at a cooling rate of 20 C. per minute. The temperature is held at 0 C. for 20 minutes and then increased to 200 C. at a heating rate of 10 C. per minute. The Tg is obtained from an inflection in the heat flow whereas Tm is obtained from an endothermic peak in the heat flow. The melting enthalpy is calculated by integration of the endothermic peak in the heat flow with the linear baseline.

Molecular Weight

[0093] The respective compounds/compositions are analyzed for molecular weight and molar mass distribution by Gel Permeation Chromatography (GPC) under the same chromatographic condition. Test samples are dissolved in N,N-dimethylacetamide and each of the prepared sample solutions is filtered through a 0.20 m syringe filter into analysis vial. The prepared sample solutions is analyzed by liquid chromatography using a GPC separation technique using Styragel columns with N,N-dimethylacetamide/LiCl elution and refractive index detection at 80 C. The number average molecular weight (M.sub.n) and weight average molecular weight (M.sub.w) that is determined for the tested substances is based on an external calibration that is carried out with polystyrene standards.

Equivalent Weight

[0094] The equivalent weight is determined by OH number determination according to DGF-CV 17a (98).

Melt Viscosity

[0095] Melt viscosity was measured using a Brookfield Viscometer model RVDV-1+ with a Model 106 temperature controller and Thermosel unit, calibrated with viscosity standard oil. 10 to 12 g of adhesive is weighed into a disposable aluminum viscometer tube. The tube is inserted into the Viscometer and left to equilibrate for 30 minutes at 160 C. The preheated spindle no. 27 is inserted into the adhesive and allowed to rotate for 30 minutes at 160 C.; the speed of rotation is changed according to the viscosity range measured. The initial viscosity V1 at 160 C. is then measured.

Example 1: Preparation of the Thermoplastic Binder Compositions

[0096] The polyester polyol was weighed into a glass flask and heated to 120 C. with mechanical stirring. The flask was sealed and vacuum was applied for 1 hour (pressure 2-5 mbar) via a vacuum pump to remove water. Flake MDI was added and allowed to react with the hydroxyl groups at 130 C. The reaction was followed by infra-red spectroscopy until the NCO absorption at 2200 cm.sup.1 disappeared.

TABLE-US-00001 TABLE 1 Thermoplastic binder compositions E1 E2 E3 V1 Semicryst. 300 g/0.1508 eq 250 g/0.1257 eq 150 g/0.0775 eq polyester polyol 1 Semicryst. 87.88 g/0.0517 eq 207.73 g/0.1222 eq polyester polyol 2 Amorph. 42.84 g/0.0305 eq polyester polyol 4,4-MDI 9.43 g/0.0754 eq 10.47 g/0.0838 eq 12.12 g/0.0969 eq 12.73 g/0.1018 eq Melting 33 30 22 10 enthalpy (J/g) Melting 93 94 115 120 point ( C.) Equivalent 4000 7013 9840 7100 weight (g/eq) Number 8000 14026 19680 14200 average molecular weight M.sub.n (g/mol) Cryo- OK OK OK OK milling Caking no caking no caking no caking caking

E1-E3: According to the Invention

V1: Comparative Example

[0097] Semi-crystalline polyester 1: Dynacoll 7340 (Evonik Industries), OH number 28-29, equivalent weight 1934-1989 g/eq
Semi-crystalline polyester 2: Dynacoll 7321 (Evonik Industries); OH number 33, equivalent weight 1700 g/eq
Amorphous polyester: Dynacoll 7150 (Evonik Industries); OH number 40, equivalent weight 1402.5 g/eq
4,4-MDI: 4,4diphenyl methane diisocyanate (Desmodur 44MC, Covestro)