HYDROPHOBIC AND HIGHLY ELASTIC TWO-COMPONENT POLYURETHANE COMPOSITION HAVING MECHANICAL PROPERTIES AND ADHESIVE PROPERTIES NOT DEPENDENT ON TEMPERATURE

Abstract

A two-component polyurethane composition includes a first component, including at least one polybutadiene polyol P1 having an average molecular weight of 2,000 to 10,000 g/mol and an average OH functionality of 2.1 to 4, and a second component, including at least one polyisocyanate and optionally at least one isocyanate-terminated polyurethane prepolymer. The composition also contains at least one hydrophobic diol P2 having an average molecular weight of 500 to 5,000 g/mol, selected from polybutadiene diols, polyester diols, polycarbonate diols, polyether diols having a repeat unit having at least 4 C atoms, and/or at least one hydrophobic compound P3, which is terminated with amino groups and has an average molecular weight in the range of 200 to 2,000 g/mol. The ratio of the number of hydroxyl groups from P1 to the number of hydroxyl and primary and secondary amino groups from P2 and P3 is 2:1 to 16:1.

Claims

1. A two-component polyurethane composition comprising a first component comprising at least one polybutadiene polyol P1 having an average molecular weight M.sub.n in the range from 2000 to 10000 g/mol and an average OH functionality in the range from 2.1 to 4, and a second component comprising at least one polyisocyanate and optionally at least one isocyanate-terminated polyurethane prepolymer, wherein the polyurethane composition further comprises at least one hydrophobic diol P2 having an average molecular weight M.sub.n in the range from 500 to 5000 g/mol selected from the group consisting of polybutadiene diols, polyester diols, polycarbonate diols and polyether diols having a repeat unit having at least 4 carbon atoms and/or at least one hydrophobic compound P3 terminated by amino groups and having an average molecular weight M.sub.n in the range from 200 to 2000 g/mol, where the molar ratio V1 of the number of hydroxyl groups from the polybutadiene polyol P1 to the number of hydroxyl and primary and secondary amino groups from diol P2 and the compound P3 is in the range from 2:1 to 16:1, and where the average molecular weight M.sub.n is determined by gel permeation chromatography against polystyrene as standard.

2. The two-component polyurethane composition as claimed in claim 1, wherein the polybutadiene polyol P1 has an average OH functionality in the range from 2.1 to 2.9.

3. The two-component polyurethane composition as claimed in claim 1, wherein it comprises at least one diol P2 in the form of an aliphatic or cycloaliphatic diol, preferably a polytetramethylene oxide diol or a polycarbonate diol based on 3-methylpentane-1,5-diol and hexane-1,6-diol, or a polyester carbonate diol based on hexane-1,6-diol and -caprolactone, or a polyester diol based on 3-methylpentane-1,5-diol and adipic acid or sebacic acid.

4. The two-component polyurethane composition as claimed in claim 1, wherein the diol P2 has an average molecular weight M.sub.n in the range from 500 to 2000 g/mol.

5. The two-component polyurethane composition as claimed in claim 1, wherein the compound P3 is a p-aminobenzoic diester of a polytetramethylene oxide diol.

6. The two-component polyurethane composition as claimed in claim 1, wherein the polyisocyanate is diphenylmethane 4,4- or 2,4- or 2,2-diisocyanate or any mixture of these isomers (MDI), or a mixture of MDI and MDI homologs (polymeric MDI or PMDI), or a mixture of MDI and oligomers, polymers or derivatives derived therefrom.

7. The two-component polyurethane composition as claimed in claim 1, wherein the parent monomeric diisocyanate of the isocyanate-terminated polyurethane prepolymer is selected from the group consisting of diphenylmethane 4,4- or 2,4- or 2,2-diisocyanate or any mixture of these isomers (MDI), tolylene 2,4- or 2,6-diisocyanate or any mixtures of these isomers (TDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) and hexamethylene 1,6-diisocyanate (HDI).

8. The two-component polyurethane composition as claimed in claim 1, wherein it further comprises at least one catalyst.

9. The two-component polyurethane composition as claimed in claim 8, wherein the catalyst is a bismuth(III) carboxylate, a Zn(II) carboxylate, a bismuth(III) 1,3-ketoacetate, a zirconium(IV) 1,3-ketoacetate, a bismuth(III) oxinate, a bismuth(III) 1,3-ketoamidate, a zirconium(IV) 1,3-ketoamidate, a zirconium(IV) diketonate, or a mixture thereof.

10. The two-component polyurethane composition as claimed in claim 1, wherein it further comprises at least one filler.

11. The two-component polyurethane composition as claimed in claim 1, wherein it further comprises at least one adhesion promoter.

12. The two-component polyurethane composition as claimed in claim 1, wherein it has a content of plasticizers of less than 1% by weight.

13. A method of bonding a first substrate to a second substrate, comprising the steps of: mixing the first and second components of the polyurethane composition as claimed in claim 1, applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded, and joining the two substrates within the open time of the mixed polyurethane composition.

14. The method as claimed in claim 13, wherein one or both of the substrates is a metal, a ceramic, a glass fiber-reinforced plastic, a carbon fiber-reinforced plastic or a polymer substrate having low surface energy, such as a polyolefin, polymethylmethacrylate or polycarbonate substrate.

15. (canceled)

Description

EXAMPLES

Substances Used:

[0143]

TABLE-US-00001 Poly bd Polybutadiene polyol, OH functionality about 2.5, R45 average molecular weight about 2800 g/mol, OH number 47.1 mg KOH/g (Poly bd R-45HTLO from Cray Valley) PolyTHF Polytetramethylene oxide diol, average molecular 2000 weight about 2000 g/mol, OH number 56 mg KOH/g (PolyTHF 2000 from BASF) Kuraray Polyester diol, average molecular weight about P2010 2000 g/mol, OH number 56 mg KOH/g (Kuraray P- 2010 from Kuraray) Krasol Polybutadienediol, OH functionality about 1.9, average 2000 molecular weight about 2000 g/mol, OH number 50 mg KOH/g, (Krasol LBH P-2000 from Cray Valley) Caradol Polypropylene oxide diol, average molecular weight about 2000 g/mol, OH number 56 mg KOH/g (Caradol ED 56 from Shell) Desmophen Polyester carbonate diol, average molecular weight C1200 about 2000 g/mol, OH number 56 mg KOH/g (Desmophen C 1200 from Bayer Material Science) Versalink p-Aminobenzoic diester of polytetramethylene oxide P-1000 diol, average molecular weight about 1200 g/mol, amine number 95 mg KOH/g (Versalink P-1000 from Air Products) Versalink p-Aminobenzoic diester of polytetramethylene oxide P-650 diol, average molecular weight about 850 g/mol, amine number 120 mg KOH/g (Versalink P-650 from Air Products) Catalyst Bismuth(III) carboxylate (K-Kat XC-C227 from King Industries) Filler Mineral filler based on calcium carbonate (Winnofil SPT from Solvay) Carbon black Monarch 120 from Cabot Polyisocyanate Modified diphenylmethane diisocyanate containing MDI-carbodiimide adducts, liquid at room temperature, NCO content 29.4% by weight (Isonate M 143 from Dow) Krasol- Prepolymer of 82% by weight of Krasol LBH P 2000 MDI prep. (see above) and 18% by weight of MDI (Lupranat MI from BASF with 2,4- and 4,4-MDI in a weight ratio of 1:1) Krasol- Prepolymer of 87% by weight of Krasol LBH P 2000 TDI prep. (see above) and 13% by weight of TDI (Desmodur T- 80 from Bayer) C1200- Prepolymer of 85% by weight of Desmophen C1200 TDI prep. (see above) and 15% by weight of TDI (Desmodur T-80 from Bayer) Desmophen- Prepolymer of 80% by weight of Desmophen C1200 MDI prep. (see above) and 20% by weight of MDI (Lupranat MI from BASF with 2,4- and 4,4-MDI in a weight ratio of 1:1)

Preparation of Polyurethane Compositions of the Invention

[0144] For each composition, the ingredients specified in tables 1, 3 and 5 were processed in the amounts specified (in parts by weight) of the first component, component-1, by means of a vacuum dissolver with exclusion of moisture to give a homogeneous paste, and stored. The ingredients of the second component, component-2, specified in tables 1, 3 and 5 were likewise processed and stored. Subsequently, the two components were processed by means of a SpeedMixer (DAC 150 FV, Hauschild) for 30 seconds to give a homogeneous paste and immediately tested as follows:

[0145] For determination of the mechanical properties, the adhesive was converted to dumbbell form according to ISO 527, Part 2, 1B, and stored/cured at 23 C. for 24 h and then at 80 C. for 3 h. After a conditioning period of 24 h, the modulus of elasticity, the tensile strength and the elongation at break of the specimens thus produced were measured according to ISO 527 on a Zwick Z020 tensile tester at the respective temperature specified in the tables and a testing speed of 200 mm/min.

[0146] For measurement of the tensile shear strength, various test specimens were produced, by applying the adhesive 1 minute after conclusion of the mixing time in each case between two heptane-degreased cathodically electrocoated (e-coated) steel sheets or isopropanol-degreased polycarbonate sheets (uncoated Makrolon) in a layer thickness of 1.6 mm and over an overlapping bonding area of 1545 mm. The test specimens were stored/cured at 23 C. for 24 h and then at 80 C. for 3 h. After a conditioning period of 24 h at 23 C., the tensile shear strength was determined according to DIN EN 1465 at a pulling speed of 10 mm/min, unless stated otherwise.

[0147] The Tg (glass transition temperature) was determined from DMTA measurements on strip samples (height 2-3 mm, width 2-3 mm, length 8.5 mm) which were stored/cured at 23 C. for 24 h and then at 80 C. for 3 h, with a Mettler DMA/SDTA 861e instrument. The measurement conditions were: measurement in tensile mode, excitation frequency 10 Hz and heating rate 5 K/min. The samples were cooled down to 70 C. and heated to 200 C. with determination of the complex modulus of elasticity E* [MPa], and a maximum in the curve for the loss angle tan was read off as Tg.

[0148] Z-1 to Z-15 are inventive examples. Rf.1 to Rf.8 are comparative examples. The values stated in table 1, 3 and 5 each denote parts by weight in the overall composition.

TABLE-US-00002 TABLE 1 Examples Z-1 Z-2 Z-3 Z-4 Rf.1 Z-5 Component-1: Poly bd R45 60 60 60 60 70 60 PolyTHF 2000 10 Desmophen C1200 10 Kuraray P2010 10 Versalink P-650 10 Versalink P-1000 10 Filler 20 20 20 20 20 20 Carbon black 10 10 10 10 10 10 Catalyst 0.04 0.04 0.04 0.04 0.04 0.04 Component-2: Polyisocyanate 9.0 9.0 9.0 10.1 9.2 11.2 Molar ratio V1.sup.1 5.0 5.0 5.0 3.0 2.4 .sup.1Ratio of the number of OH groups of Poly bd R45 to the sum total of the number of OH and NH.sub.2 groups from Poly THF 2000, Kuraray P2010, Desmophen C1200, Versalink P-650 and Versalink P-1000

TABLE-US-00003 TABLE 2 Examples Z-1 Z-2 Z-3 Z-4 Rf.1 Z-5 Tensile shear strength 2.8.sup.1 2.5.sup.1 2.9.sup.1 3.3.sup.1 2.5.sup.1 2.6.sup.1 [MPa] 100CF 100CF 80CF/ 100CF 100CF 95CF/ 1.6 mm onto e-coat/e-coat 20SCF 5SCF 1.6 mm onto PC/PC.sup.2 n.d. 2.7.sup.1 2.3.sup.1 n.d. 1.4.sup.1 2.0.sup.1 90CF/ 70CF/ 90AF/ 100 SCF 10SCF 30SCF 10CF Tensile strength [MPa] 3.1 3.8 3.0 3.0 2.6 2.5 23 C. Elongation at break [%] 394 383 299 231 182 169 23 C. Modulus of elasticity 3.8 3.2 3.6 5.0 4.9 5.8 0.5 to 5% [MPa] 23 C. Shore A 58 54 57 65 66 61 1st Tg ( C.) 47 56 56 60 58 54 2nd Tg ( C.) 10 17 70 3rd Tg ( C.) 168 160 160 155 158 .sup.1determined at 20 mm/min; .sup.2PC stands for polycarbonate (Makrolon); n.d. stands for not determined; CF stands for cohesive failure; SCF stands for substrate/cohesive failure; AF stands for adhesive failure.

TABLE-US-00004 TABLE 3 Examples Z-3 Z-6 Z-7 Z-8 Rf.2 Rf.3 Rf.4 Rf.5 Rf.6 Rf.7 Rf.8 Component-1: Poly bd R45 60 60 63 66.5 45 25 21 60 45 Krasol 2000 60 45 Kuraray P2010 10 7 3.5 25 45 49 10 25 Caradol 10 25 Filler 20 20 20 20 20 20 20 20 20 20 20 Carbon black 10 10 10 10 10 10 10 10 10 10 10 Catalyst 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Component-2: Polyisocyanate 9.0 9.0 9.0 8.9 9.4 9.9 10 10.2 8.9 10.2 9.8 Kuraray P2010 10 Molar ratio V1.sup.1 5.0 5.0 7.6 16.0 1.5 0.4 0.3 (5.4) (5.0) 1.6 1.5 .sup.1Ratio of the number of OH groups of Poly bd R45 (or Krasol 2000) to the sum total of the number of OH and NH.sub.2 groups from Poly THF 2000 (or Caradol), Kuraray P2010 and Desmophen C1200

TABLE-US-00005 TABLE 4 Examples Z-3 Z-6 Z-7 Z-8 Rf.2 Rf.3 Rf.4 Rf.5 Rf.6 Rf.7 Rf.8 Tensile shear strength 2.9.sup.1 2.6 2.2 2.5 1.8 0.7 0.5 0.08 2.1 0.04 1.05 [MPa] 80CF/ 90CF/ 80CF/ 80CF/ 60CF/ 100SCF 100SCF CF95 100SCF 1.6 mm onto e-coat/e-coat.sup.1 20SCF 10SCF 20SCF 20SCF 40AF SCF5 1.6 mm onto PC/PC.sup.2 2.3.sup.1 2.8 2.4 2.5 2.1 0.4 0.3 0.06 2.4 0.03 0.9 70CF/ 80CF/ 70CF/ 50CF/ 90CF/ 100AF 90AF/ 50CF/ 95SCF/ 30SCF 20SCF 30SCF 50SCF 10AF 10SCF 50SCF 5AF Tensile strength [MPa] 3.0 3.8 3.1 2.6 4.0 4.9 4.0 0.3 2.5 0.4 2.3 23 C. Elongation at break 299 378 358 288 527 726 736 153 351 238 473 [%] Modulus of elasticity 3.6 3.1 3.1 3.3 2.7 2.7 2.5 1.5 2.3 0.8 1.6 0.5 to 5% [MPa] 23 C. Shore A 57 53 54 47 52 50 52 28 46 31 39 1st Tg ( C.) 56 52 55 52 54 26 28 12 45 12 28 2nd Tg ( C.) 17 17 17 14 22 80 3rd Tg ( C.) 160 160 160 160 160 145 140 140 160 140 158 .sup.1determined at 20 mm/min; .sup.2PC stands for polycarbonate (Makrolon); CF stands for cohesive failure; SCF stands for substrate/cohesive failure; AF stands for adhesive failure.

TABLE-US-00006 TABLE 5 Examples Z-3 Z-9 Z-10 Z-11 Z-12 Z-13 Z-14 Z-15 Component-1: Poly bd R45 60 60 60 60 60 60 60 60 Kuraray P2010 10 10 10 10 10 Filler 20 20 20 20 20 20 20 20 Carbon black 10 10 10 10 10 10 10 10 Catalyst 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Component-2: Polyisocyanate 9.0 8.2 6.4 8.2 6.5 7.5 7.6 5.9 Krasol-MDI prep. 8.2 25.6 Krasol-TDI prep. 8.3 26 C1200-TDI prep. 7.5 C1200-MDI prep. 7.6 23.6 Molar ratio V1.sup.1 5.0 5.6 6.9 5.7 7.1 7.8 8.3 2.7 .sup.1Ratio of the number of OH groups of Poly bd R45 to the sum total of the number of OH and NH.sub.2 groups from Poly THF 2000, Kuraray P2010, Desmophen C1200 and Versalink P-650 and Versalink P-1000

TABLE-US-00007 TABLE 6 Examples Z-3 Z-9 Z-10 Z-11 Z-12 Z-13 Z-14 Z-15 Tensile shear strength 2.9.sup.1 2.7 3.3 2.9 3.1 2.9 2.7 3.3 [MPa] 80CF/ 100CF 10CF/ 10CF/ 10CF/ 90CF/ 100CF 90CF/ 1.6 mm onto e-coat/e-coat 20SCF 90SCF 90SCF 90SCF 10SCF 10SCF 1.6 mm onto PC/PC.sup.2 2.3.sup.1 3.4 3.4 2.9 3.2 3.1 3.4 3.4 70CF/ 100CF 10CF/ 30CF/ 80CF/ 100CF 100CF 90CF/ 30SCF 90SCF 70SCF 20SCF 10SCF Tensile strength [MPa] 3.0 2.9 3.2 3.0 2.1 3.4 4.0 3.4 23 C. Elongation at break 299 292 327 415 524 295 282 390 [%] 23 C. Modulus of elasticity 3.6 3.4 3.1 2.4 3.6 4.1 4.2 2.9 0.5 to 5% [MPa] 23 C. Shore A 57 55 58 51 48 61 59 53 1st Tg ( C.) 56 47 47 40 38 53 52 53 2nd Tg ( C.) 17 17 17 15 12 14 3rd Tg ( C.) 160 162 162 158 158 160 160 160 .sup.1determined at 20 mm/min; .sup.2PC stands for polycarbonate (Makrolon); CF stands for cohesive failure; SCF stands for substrate/cohesive failure

[0149] The plot of the modulus of elasticity (complex modulus of elasticity E* [MPa] as a function of the temperature [ C.]) for the compositions Rf.1 (.diamond-solid.), Rf. 3 (), Z-3 (.box-tangle-solidup.), Z-6 (o) and Z-10 (+) is shown in FIG. 1. This shows that the noninventive compositions, within the temperature range between 20 C. and 120 C., have a comparatively strong dependence of the complex modulus of elasticity E* on temperature (Rf. 3) or, like Rf.1, have a very minor dependence of the complex modulus of elasticity on temperature at these temperatures but also have only very low values for the moduli of elasticity. For the inventive compositions, by comparison, a dependence of the modulus E* on temperature comparable to Rf.1 is found, with modulus values higher by a factor of 2-3. By comparison with Rf.3, much higher values are obtained for the modulus E* at temperatures above 120 C.

[0150] Rf. 1 shows almost ideal flexible characteristics with very low dependence of the modulus of elasticity E* on temperature, but is unsuitable as an adhesive owing to inadequate bonding properties, especially to polycarbonate.