TWO-COMPONENT POLYURETHANE COMPOSITION WITH A HIGH DEGREE OF HYDROPHOBICITY AND ADJUSTABLE POT LIFE

Abstract

A polyurethane composition includes first and second components, wherein the first component contains between 30% and 99% by weight of a polyol mixture including 100 parts by weight of at least one hydrophobic polyol, 10 to 75 parts by weight of at least one hydrophilic polyol, 0 to 25 parts by weight of at least one diol having two hydroxyl groups linked via a C2 to C9 carbon chain; and also at least one compound having at least one thiol group; and the second component includes at least one polyisocyanate, wherein one of the two components additionally includes at least one metal catalyst for the reaction of hydroxyl groups and isocyanate groups that is able to form thio complexes and the molar ratio of all the thiol groups in the at least one compound to all metal atoms in the at least one metal catalyst is between 1:1 and 250:1.

Claims

1. A polyurethane composition comprising a first component A and a second component B, wherein the first component A comprises between 30% and 99% by weight based on component A of a polyol mixture P comprising 100 parts by weight of at least one hydrophobic polyol P1, 10 to 75 parts by weight of at least one hydrophilic polyol P2, 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups that are linked via a C2 to C9 carbon chain, and also at least one compound T having at least one thiol group; and the second component B comprises at least one polyisocyanate I; wherein one of the two components additionally comprises at least one metal catalyst K for the reaction of hydroxyl groups and isocyanate groups that is able to form thio complexes and the molar ratio of all the thiol groups in the at least one compound T to all metal atoms in the at least one metal catalyst K is between 1:1 and 250:1.

2. The polyurethane composition as claimed in claim 1, wherein the metal catalyst K comprises a bismuth(III) compound.

3. The polyurethane composition as claimed in claim 2, wherein the bismuth(III) compound additionally contains an 8-hydroxyquinoline ligand or a 1,3-ketoamide ligand.

4. The polyurethane composition as claimed in claim 1, wherein the diol P3 is a linear aliphatic diol having two primary hydroxyl groups that are linked via a C4 to C9 carbon chain.

5. The polyurethane composition as claimed in claim 1, wherein the at least one compound T comprises a polythiol compound having 2 to 6 thiol groups, or a mercaptosilane.

6. The polyurethane composition as claimed in claim 5, wherein the at least one compound T is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), and 3-mercaptopropyltrimethoxysilane.

7. The polyurethane composition as claimed in claim 1, wherein the molar ratio of all the thiol groups in the at least one compound T to all metal atoms in the at least one metal catalyst K is between 5:1 and 100:1.

8. The polyurethane composition as claimed in claim 1, wherein the metal catalyst K is present in the first component A.

9. The polyurethane composition as claimed in claim 1, wherein the hydrophilic polyol P2 is a polyether polyol.

10. The polyurethane composition as claimed in claim 1, wherein the polyisocyanate I is a form of diphenylmethane 4,4′-, 2,4′- or 2,2′-diisocyanate that is liquid at room temperature or any desired mixtures of these isomers (MDI) in the form of polymeric MDI or MDI containing proportions of oligomers or derivatives.

11. The polyurethane composition as claimed in claim 1, wherein the second component B comprises a polyurethane polymer containing isocyanate groups.

12. The polyurethane composition as claimed in claim 1, wherein the hydrophobic polyol P1 is a polybutadiene polyol, a dimer fatty acid-based polyester polyol, a polytetramethylene oxide diol, or a mixture of the polyols, wherein the polyol P1 has an average OH functionality of between 2 and 2.5.

13. A method for the adhesive bonding of a first substrate to a second substrate, comprising the steps of: mixing the first and second components of a 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.

14. An article resulting from the adhesive bonding method as claimed in claim 13.

15. (canceled)

Description

EXAMPLES

[0207] Substances used:

TABLE-US-00001 TABLE 1 Substances used. Voranol CP- Voranol ® CP 4755 (Dow Chemical); polyether triol, 4755 CAS No. 9082-00-2; MW: 5000 g/mol; OH value: 35 mg KOH/g; average OH functionality: 3 Dianol 3130 Dianol ® 3130 HP (Arkema); propoxylated bisphenol A; HP MW: 982 g/mol; OH value 115 mg KOH/g; average OH functionality: 2 PolyBD R-45 Poly bd ® R-45HTLO (Cray Valley); polybutadiene HTLO polyol; MW: 2800 g/mol; OH value 47 mg KOH/g; average OH functionality: 2.5 Priplast 1838 Priplast ® 1838 (Croda); dimer fatty acid-polyester diol; MW: 2000 g/mol; OH value 56 mg KOH/g; average OH functionality: 2 Desmophen Desmophen ® 5034 BT (Covestro); glycerol-started, 5034 BT ethylene oxide end-capped polypropylene glycol; MW: 4800 g/mol; OH value: 35 mg KOH/g; average OH functionality: 2.6 Desmophen Desmophen ® 28HS98 (Covestro); polypropylene glycol; 28HS98 MW: 720 g/mol; OH value: 233 mg KOH/g; average OH functionality: 3 Kuraray Kuraray ® F-510 (Kuraray); polyester polyol from F-510 MPD/TMP adipate; MW: 500 g/mol; OH value: 336 mg KOH/g; average OH functionality: 3 Butane-1,4- Butane-1,4-diol (Sigma Aldrich) diol GDMP Thiocure ® GDMP (Bruno Bock Thiochemicals); glycol di(3-mercaptopropionate) Desmodur Desmodur ® CD-L (Covestro); modified CD-L diphenylmethane 4,4′-diisocyanate (MDI); NCO content: 29.5% by weight Desmodur Desmodur ® CD-S (Covestro); modified diphenylmethane CD-S 4,4′-diisocyanate (MDI); NCO content: 29.5% by weight Desmodur 44 Desmodur ® 44 MC liquid (Covestro); monomeric MC diphenylmethane 4,4′-diisocyanate (MDI); NCO content: 33.6% by weight Carbon black Monarch ® 570 (Cabot Corp.); carbon black (filler) Kaolin White Tex ® (BASF); calcined aluminum silicate (filler) Chalk Omyacarb ® 5 GU (Omya); ground natural chalk (filler) Coscat 83 35% by weight of Coscat 83 (organobismuth catalyst; Coscat ® 83 (Vertellus Specialties Inc.)) in plasticizer containing 1 molar equivalent of 8-hydroxyquinoline (based on Bi) (2.68 mmol Bi/g)

[0208] Preparation of Polyurethane Compositions

[0209] For each composition, the ingredients of the first component A specified in the tables were processed in the specified amounts (in parts by weight or wt.-%), by means of a vacuum dissolver with the exclusion of moisture, into a homogeneous paste and stored. The ingredients of the second component B specified in the tables were likewise processed and stored. The two components were then processed for 30 seconds, by means of a SpeedMixer® (DAC 150 FV, Hauschild), into a homogeneous paste, which was immediately tested as follows:

[0210] To determine the mechanical properties, the adhesive was fashioned into a dumbbell shape according to ISO 527, Part 2, 1B and stored/cured at 23° C. and 50% RH (relative humidity) for the time specified in the tables (1 day and 7 days) and then at 90° C. for 7 days. After a conditioning period of 24 h at 23° C. and 50% RH, the modulus of elasticity in the 0.05 to 0.25% elongation range, the tensile strength, and the elongation at break of the test specimens thus produced were measured in accordance with DIN EN ISO 527 on a Zwick Z020 tensile tester at 23° C. and 50% RH and a testing speed of 10 mm/min. To measure the tensile shear strength, various test specimens were produced, in each case by applying the adhesive 1 minute after the end of the mixing time between two heptane-degreased cathodically-electrocoated steel plates in a layer thickness of 2 mm and over an overlapping bonding area of 15×45 mm. The test specimens were stored/cured for 24 h at 23° C. (“cool conditions”). Some of the samples were then additionally stored/cured for 10 days under hot and humid conditions (40° C. and 100% relative humidity). After a conditioning period of 24 h at 23° C. and 50% RH, the tensile shear strength was determined in accordance with DIN EN 1465.

[0211] Viscosity was measured on an MCR 302 parallel-plate rheometer (Anton Paar) with a plate diameter of 25 mm and a plate distance of 1 mm at a frequency of 10 s.sup.−1 and a temperature of 20° C. This was done by first manually mixing the two components for 30 sec in a beaker using a spatula and immediately applying them to the plates for the measurement.

[0212] The results of the measurements are given in the tables.

[0213] In the tables, compositions according to the invention are identified as “I” (I-1 to I-11) and non-inventive reference compositions as “R” (R-1 to R-4).

TABLE-US-00002 TABLE 2 Example compositions R-1, R-2, I-1, and I-2. Example R-1 R-2 I-1 I-2 First component A (amounts in wt-%, based on first component A) PolyBD R-45 HTLO 99.0 — 80.0 90.0 Priplast 1838 — 99.0 — — Desmophen 28HS98 — — 19.0 9.0 GDMP 0.4 0.4 0.4 0.4 Coscat 83 0.6 0.6 0.6 0.6 Second component B (amounts in wt-%, based on first component B) Desmodur CD-S 100.0 100.0 100.0 100.0 Mixture of first component A and second component B Mixing ratio (parts by weight B 1.36 1.61 6.24 6.24 per 10 parts by weight A) Time t.sub.1 [min] until viscosity = After After 17.8 19.8 100 Pa .Math. s only only Time t.sub.2 [min] until viscosity = 19 min 17 min 19.8 22.4 500 Pa .Math. s 42 Pa .Math. s 50 Pa .Math. s Time t.sub.3 [min] until viscosity = 20.6 23.6 1000 Pa .Math. s Time t.sub.3 minus time t.sub.2 >10 >10 0.8 1.2

TABLE-US-00003 TABLE 3 Example compositions R-3, R-4, I-3, I-4, and I-5. Example R-3 R-4 I-3 I-4 I-5 First component A (amounts in wt-%, based on first component A) Priplast 1838 99.0 99.8 79.2 79.2 79.2 Desmophen — — 19.8 — — 28HS98 Desmophen 5034 — — — 19.8 — BT Dianol 3130 HP — — — — 19.8 GDMP 0.4 — 0.4 0.4 0.4 Coscat 83 0.6 0.2 0.6 0.6 0.6 Second component B (amounts in wt-%, based on first component B) Desmodur CD-S 20.0 20.0 20.0 20.0 20.0 Desmodur 44 19.0 19.0 19.0 19.0 19.0 MC Desmophen 5034 46.0 46.0 46.0 46.0 46.0 BT Carbon black 15.0 15.0 15.0 15.0 15.0 Mixture of first component A and second component B Mixing ratio 4.26 4.16 6.87 3.94 5.12 (parts by weight B per 10 parts by weight A) Time t.sub.1 [min] After 7.3 11.3 22.8 27.3 until viscosity = 17 min 100 Pa .Math. s only Time t.sub.2 [min] 50 Pa .Math. s 16.8 13.4 28.9 33.6 until viscosity = 500 Pa .Math. s Time t.sub.3 [min] 22.2 14.5 32.4 37.9 until viscosity = 1000 Pa .Math. s Time t.sub.3 minus >10 5.4 1.1 3.5 4.3 time t.sub.2

[0214] The viscosity measurements in Tables 2 to 5 show that the compositions of the invention continue to have low viscosity for a comparatively long time (time t.sub.1), but then cure very rapidly (time t.sub.2 and t.sub.3, especially difference between time t.sub.2 and t.sub.3).

[0215] The subtraction of time t3 minus time t2 shows the rate of curing. The smaller this value, the more rapidly the composition cures. In order to exhibit a rate of curing that is according to the invention adequate, the value for t.sub.3 minus t.sub.2 should be less than 5, preferably less than 4.5. In particularly preferred embodiments, the value for t.sub.3 minus t.sub.2 is less than 2, especially less than 1.5.

TABLE-US-00004 TABLE 4 Example compositions I-6 to I-9. Example I-6 I-7 I-8 I-9 First component A (amounts in wt-%, based on first component A) Priplast 1838 79.2 90.0 69.3 59.4 Desmophen 28HS98 — 9.0 29.7 39.6 Kuraray F-510 19.8 — — — GDMP 0.4 0.4 0.4 0.4 Coscat 83 0.6 0.6 0.6 0.6 Second component B (amounts in wt-%, based on first component B) Desmodur CD-S 20.0 20.0 20.0 20.0 Desmodur 44 MC 19.0 19.0 19.0 19.0 Desmophen 5034 BT 46.0 46.0 46.0 46.0 Carbon black 15.0 15.0 15.0 15.0 Mixture of first component A and second component B Mixing ratio (parts by 8.38 5.45 8,178 9,482 weight B per 10 parts by weight A) Time t.sub.1 [min] until 19.8 27.7 11.2 9.8 viscosity = 100 Pa .Math. s Time t.sub.2 [min] until 25.4 32.7 12.9 11.1 viscosity = 500 Pa .Math. s Time t.sub.3 [min] until 28.9 35.3 13.7 11.8 viscosity = 1000 Pa .Math. s Time t.sub.3 minus time t.sub.2 3.5 2.6 0.8 0.7

TABLE-US-00005 TABLE 5 Example compositions I-10 and I-11. Example I-10 I-11 First component A (amounts in wt-%, based on first component A) Priplast 1838 47.0 44.0 Desmophen 28HS98 15.0 6.0 Butane-1,4-diol — 6.3 Chalk 30.0 35.0 Carbon black 8.0 8.0 GDMP 0.3 0.3 Coscat 83 0.4 0.4 Second component B (amounts in wt-%, based on first component B) Desmodur CD-L 44 44 Voranol CP-4755 32 32 Kaolin 15 15 Carbon black 10 10 Mixture of first component A and second component B Mixing ratio A:B (v/v) 2:1 1:1 Time t.sub.1 [min] until viscosity = 11.0/4.6/2.3 4.8/-/- 100 Pa .Math. s (25° C./40° C./55° C.) Time t.sub.2 [min] until viscosity = 13.0/5.5/2.7 6.6/-/- 500 Pa .Math. s (25° C./40° C./55° C.) Time t.sub.3 [min] until viscosity = 14.0/5.9/2.0 7.9/-/- 1000 Pa .Math. s (25° C./40° C./55° C.) Time t.sub.3 minus time t.sub.2 (25° C./40° C./  1.0/0.4/0.2 1.3/-/- 55° C.)

TABLE-US-00006 TABLE 6 Measured values for example compositions I-10 and I-11. Example I-10 I-11 Measurement results Elastic modulus (0.05-0.25% extension) 8.0 31.7 [MPa] Elastic modulus (0.5-5.0% extension) [MPa] 6.6 28.7 Tensile strength [MPa] 5.8 12.4 Elongation at break [%] 172 228 Tensile shear strength (cool conditions) 3.4 8.0 [MPa] Fracture profile (cool conditions) 100 100 [% cohesive] Tensile shear strength (7 d hot/humid n/m 7.3 conditions) [MPa] Fracture profile (7 d hot/humid conditions) n/m 100 [% cohesive] “n/m” means that the value was not measured.

[0216] Table 5 shows for experiment 1-10 that the application temperature too has an influence on the rate of curing and the pot life. This means that the application and curing of the composition can be additionally influenced via the application temperature too.

[0217] Table 6 shows that the use of a diol P3 (in this case butane-1,4-diol in example 1-11) has a clearly positive influence on the mechanical properties of a composition of the invention.