TWO-COMPONENT POLYURETHANE COMPOSITION

Abstract

A two-component polyurethane composition which includes a polyol component and a polyisocyanate component, wherein the polyol component includes at least one reaction product of epoxidized vegetable oils with monofunctional C.sub.1-8-alcohols A1-1 and/or at least one reaction product of epoxidized fatty acid esters with monofunctional C.sub.1-8-alcohols with aliphatic alcohols A1-2, at least one polybutadiene polyol A2 and at least one alkoxulated alkylenediamine A3. The polyurethane composition of the invention has high strength and only a minor dependence of mechanical properties, especially of strength, on temperature, especially in the range from 50 C. to +120 C.

Claims

1. A two-component polyurethane composition consisting of a polyol component K1 and a polyisocyanate component K2; wherein the polyol component K1 comprises at least one reaction product of epoxidized vegetable oils having a C.sub.18 fatty acid content of more than 50% by weight based on the total amount of fatty acids, with monofunctional C.sub.1-8 alcohols A1-1; and/or at least one reaction product of epoxidized fatty acid esters of monofunctional C.sub.1-8 alcohols with aliphatic alcohols having an OH functionality in the range from 2 to 5, where the parent fatty acid component of the epoxidized fatty acid esters is fatty acid mixtures having a content of C.sub.18 fatty acids of at least 50% by weight, based on the overall fatty acid mixture A1-2; and at least one polybutadiene polyol having an OH functionality in the range from 2.1 to 2.9, and having an average molecular weight in the range from 2000 to 4000 g/mol, and an OH number of 40-100 mg KOH/g A2; and at least one alkyoxylated alkylenediamine having an OH number of 350-950 mg KOH/g A3; and wherein the polyisocyanate component K2 comprises at least one aromatic polyisocyanate B1, and where the ratio of all NCO groups of the aromatic polyisocyanates B1: all OH groups of the polyol component K1=0.9:1-1.2:1.

2. The two-component polyurethane composition as claimed in claim 1, wherein the ratio of the OH groups of (A1-2+A1-2+A2)/(A3) is 1.1-20, 1.15-16, 1.25-16.

3. The two-component polyurethane composition as claimed in claim 1, wherein the ratio of the OH groups of (A1-2+A1-2)/(A3) is 1.1-16.

4. The two-component polyurethane composition as claimed in claim 1, wherein the ratio of the percentages by weight, based on the total weight of the two-component polyurethane composition, of ((A1-1+A1-2+A3+B1)/(A2)) is 2.6-16.

5. The two-component polyurethane composition as claimed in claim 1, wherein they include an alkoxylated alkylenediamine having an OH number of 350-950 mg KOH/g A3 selected from the list consisting of N,N,N,N-tetrakis(2-hydroxyethyl)ethylenediamine, N,N,N,N-tetrakis(2-hydroxypropyl)ethylenediamine and N,N,N,N,N-pentakis(2-hydroxypropyl) diethylenetriamine.

6. The two-component polyurethane composition as claimed in claim 1, wherein the vegetable oils of A1-1 are vegetable oils selected from the list consisting of sunflower oil, rapeseed oil and castor oil.

7. The two-component polyurethane composition as claimed in claim 1, wherein the content of oleic acid and linoleic acid in the fatty acid mixtures in A1-2, based on the overall fatty acid mixture, is at least 60% by weight.

8. The two-component polyurethane composition as claimed in claim 1, wherein the polyol component K1 includes at least one reaction product A1-1 and at least one reaction product A1-2, where the weight ratio (A1-1/A1-2) is from 1:3 to 3:1.

9. The two-component polyurethane composition as claimed in claim 1, wherein the aromatic polyisocyanate B1 is monomeric MDI or oligomers, polymers and derivatives derived from MDI.

10. A method of bonding a first substrate to a second substrate, comprising the steps of: mixing the polyol component (K1) and the polyisocyanate component (K2) of a two-component polyurethane composition as claimed in claim 1, applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded, joining the substrates to be bonded within the open time, curing the polyurethane composition.

11. A method of filling joins and gaps in a substrate, comprising the steps of: a) mixing the polyol component (K1) and the polyisocyanate component (K2) of a two-component polyurethane composition as claimed in claim 1, b) applying the mixed polyurethane composition to the gap or join to be filled in the substrate, c) curing the polyurethane composition in the join or gap.

12. A method of producing fiber-reinforced composite parts and a two-component polyurethane composition as claimed in claim 1, wherein the polyol component K1 and the polyisocyanate component K2 are mixed and then are introduced into a mold containing the fibers under reduced pressure and/or elevated pressure.

13. The method as claimed in claim 12, wherein the fibers are selected from the group consisting of natural fibers, glass fibers, carbon fibers, polymer fibers, ceramic fibers and metal fibers.

14. A fiber composite consisting of fibers and a cured two-component polyurethane composition as claimed in claim 1.

15. A method of using a two-component polyurethane composition as claimed in claim 1 as an infusion resin.

Description

EXAMPLES

Substances Used:

[0156]

TABLE-US-00002 Neukapol A1-1, reaction product of epoxidized vegetable oils 1119 (rapeseed oil) having a proportion of unsaturated C-18 fatty acids of 91% by weight, based on the total amount of fatty acids, with monofunctional C.sub.1-8 alcohols. OH functionality 2.0, average molecular weight about 390 g/mol, OH number of 290 mg KOH/g, Neukapol 1119, Altropol Kunststoff GmbH, Germany Neukapol A1-2, reaction product of epoxidized fatty acid esters of 1565 methanol with glycerol, where the parent fatty acid component of the epoxidized fatty acid esters is fatty acid mixtures of rapeseed oil or sunflower oil, with a content of unsaturated C-18 fatty acids of at least 80% by weight, based on the overall fatty acid mixture. OH functionality 3.0, average molecular weight about 540 g/mol, OH number of 310 mg KOH/g, Neukapol 1565, Altropol Kunststoff GmbH, Germany Polybd A2, polybutadiene polyol having primary OH groups, OH 45 HTLO functionality 2.4-2.6, average molecular weight about 2800 g/mol, OH number 48 mg KOH/g (Poly bd R-45HTLO from Total Cray Valley, USA) Quadrol A3, N,N,N,N-tetrakis(2-hydroxypropyl)ethylenediamine, OH number 770 mg KOH/g, Quadrol, Sigma Aldrich Sylosiv Zeolite (Sylosiv A3 from W. R. Grace & Co., USA) Desmodur Polymeric MDI, average NCO functionality of 2.5, VL Desmodur VL, Covestro AG, Germany

[0157] Production of Polyurethane Compositions

[0158] For each composition, the ingredients specified in table 1 were processed in the specified amounts (in parts by weight) of the polyol component K1 by means of a vacuum dissolver with exclusion of moisture to give a homogeneous paste, and stored. The ingredients of the polyisocyanate component K2 specified in table 1 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 (ratio of all NCO groups B1: all OH groups of the polyol components K1 in each case=1.07) and immediately tested as follows:

[0159] To determine the mechanical properties, the adhesive was converted to dumbbell form according to ISO 527, Part 2, 1B, and stored for 7 days under standard climatic conditions (23 C., 50% relative humidity) or stored under standard climatic conditions for 12-24 h and then cured for 3 h at 80 C. Thereafter, at room temperature, modulus of elasticity in the range from 0.05% to 0.25% elongation (Modulus of elasticity, Em 0.05-0.25%), modulus of elasticity in the range from 0.5% to 5% elongation (Modulus of elasticity, Em 0.5-5%, tensile strength (TS) and elongation at break (EB) of the test specimens thus produced were measured to ISO 527 on a Zwick Z020 tensile tester at a testing rate of 10 mm/min.

[0160] Glass transition temperature, abbreviated in the tables to T.sub.g, 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 T.sub.g.

[0161] The results are reported in table 1.

[0162] The progression of the modulus of elasticity (complex modulus of elasticity E* [MPa] as a function of temperature [ C.]) for the compositions E6 () and R8 () is shown in FIG. 1. The progression of tan as a function of temperature [ C.] for compositions E6 () and R8 () is shown in FIG. 2.

[0163] Lap shear strength (LSS for short) was measured by producing test specimens having compositions based on R8, E6, E6 and E7. The sole difference in the case of the compositions mentioned was that, rather than 1 part by weight of Sylosiv, the parts by weight of Sylosiv, fumed silica and precipitated chalk marked by * In table 1 were used. For example, for composition R8, rather than 1 part by weight of Sylosiv, the following Ingredients were used: 1 part by weight of Sylosiv, 3 parts by weight of fumed silica, 6 parts by weight of precipitated chalk. The adhesive was applied in each case 1 minute after conclusion of the mixing time between two heptane-degreased carbon fibre-reinforced composite test specimens (Sika Carbodur sheets, Sika Schweiz AG, Switzerland) in a layer thickness of 0.8 mm and over an overlapping bonding area of 1045 mm. The test specimens were stored/cured under standard climatic conditions for 24 h and then at 80 C. for 3 h. After a conditioning time of 24 h under standard climatic conditions, lap shear strength was determined to DIN EN 1465 with a tension rate of 10 mm/min at 23 C. (LSS RT), or at 80 C. (LSS 80 C.). The decrease in lap shear strength in % of the measurement at 23 C. compared to that at 80 C. is shown in table 1 as LSS RT vs. 80 C..

TABLE-US-00003 TABLE 1 R1 R2 R3 R4 R5 R6 R7 E1 E2 E3 E4 R8 E5 E6 E7 Polyol comp. K1 A1-1 Neukapol 20 20 20 20 20 20 10 10 10 10 1119 A1-2 Neukapol 20 20 20 20 20 5 5 5 5 1565 A2 Polybd 45 5 10 10 5 10 5 10 5 7 10 HTLO A3 Quadrol 5 5 5 5 5 5 5 5 5 5 Sylosiv 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 (1**) (1.25**) (1.35**) (1.5**) Precipitated (6**) (7.5**) (8.1**) (9**) chalk Fumed silica (3**) (3.75**) (4.05**) (4.5**) Polyisocyanate comp. K2 Desmodur VL 14.5 15.5 15.1 15.7 16.7 25.2 24.2 24.8 25.3 26 26.4 20.5 21.1 21.4 21.7 Mixing ratio 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 100: 69.1 73.9 58.2 50.7 53.9 96.8 92.9 79.9 70.4 84.0 73.2 97.5 81.3 76.3 70.1 NCO/OH-ratio 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 1.07 (A1 1 + A1 1.61 1.51 1.57 1.63 1.67 1.74 1.16 1.22 1.24 1.28 2 + A2)/A3 (A1 1 + A1 7.0 3.6 3.7 10.0 5.0 10.2 5.1 8.2 5.9 4.2 2 + A3 + B1)/A2 (A1 1 + 1.6 1.5 1.5 1.5 1.6 1.6 1.2 1.2 1.2 1.2 A1 2)/A3 Gelation Time 191* 102* 165* 136* 102 2 4 4 4 2 3 2 2 2 2 [min] 3 h at 80 C. TS [MPa] n.d. 28.8 16.6 n.d. 15.2 54.1 54.4 43.5 33.3 44.6 32.7 61.1 44.1 42.4 37.6 EB [%] n.d. 5 5 n.d. 14 7 6 6 6 8 7 8 5 5 6 Em0.05-0.25% n.d. 1180 720 n.d. 595 1980 2130 1660 1260 1590 1240 2290 1620 1440 1260 [MPa] Em 0.5-5% n.d. 526 311 n.d. 286 1026 1010 832 628 835 620 1142 874 807 713 [MPa] 1.sup.st Tg ( C.) 55 55 55 55 55 55 55 55 55 55 2.sup.nd Tg ( C.) n.d. 87 97 n.d. 84 120 134 140 145 132 132 127 144 153 153 LSS RT n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 7.5** 14.0** 13.5** 14.0** [MPa]** LSS 80 C. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 11.8** 11.4** 9.5** [MPa]** LSS RT vs. 16%** 16%** 32%** 80 C.** *= foaming, **= compositions with exchange of 1 part by weight of Sylosiv, n.d. = not determined

[0164] Table 1 specifies the components of the polyol comp. K1, or of the polyisocyanate comp. K2, in parts by weight.

[0165] The figures ((A1-1+A1-2+A3+B1)/(A2)) in table 1 relate to the weight ratios of the proportions of A1-1 Neukapol 1119, A1-2 Neukapol 1565, A2 Polybd 45 HTLO and A3 Quadrol L and B1 Desmodur VL present.

[0166] The figures (A1-2+A1-2+A2/(A3) and (A1-2+A1-2)/(A3) in table 1 relate to the ratio of the OH groups of A1-1 Neukapol 1119, A1-2 Neukapol 1565, A2 Polybd 45 HTLO, and A3 Quadrol L. The ratio described above is understood to mean the molar ratio of the groups mentioned.

[0167] The term Mixing ratio indicates the proportion of component K2 in parts by weight that has been added to 100 parts by weight of the appropriate component K1.

[0168] Gelation time [min] as a measure of open time was determined the tack-free time. For this purpose, a few grams of the adhesive were applied to cardboard in a layer thickness of about 2 mm and, under standard climatic conditions, the time until, when the surface of the adhesive was gently tapped by means of an LDPE pipette, there were for the first time no residues remaining any longer on the pipette was determined.

[0169] E1 to E7 are inventive examples. R1 to R8 are comparative examples.

[0170] It is apparent from table 1 that the comparative compositions R1, R2, R6, R7 and R8 do not have a first glass transition temperature (Tg1) at low temperatures of below 50 C. This leads to brittle materials of high strength that break easily under high tensile or compressive stress.

[0171] Compositions E5, E6 and E7, by comparison with comparative composition R8, have significantly higher lap shear strength from carbon fibre-reinforced composite substrates. It has been found that, surprisingly, the drop in lap shear strength at 80 C. is very small compared to the measurements at 23 C. Typically, prior art polyurethane compositions show a significant drop in lap shear strength (>50%). For example, the drop in lap shear strength (LSS RT vs. 80 C.) of a composition according to ex. 1 in table 1 on page 7 of EP1690880A1 in the aforementioned measurement of lap shear strength is 72%.