High-functionality polyisocyanates containing urethane groups

Abstract

The present invention relates to new, urethane-group-containing polyisocyanates based on aliphatic and/or cycloaliphatic diisocyanates, and to their use.

Claims

1. A high-functionality polyisocyanate, comprising urethane groups and obtained by: reacting (a) at least one alkoxylated polyfunctional alcohol (A) obtained by alkoxylating trimethylolpropane with one or more alkyene-oxide units selected from the group consisting of ethylene oxide and propylene oxide, and having a OH-functionality which is on average more than 2; (b) at least one polyisocyanate (B) having an NCO-functionality of more than 2, which comprises at least one selected from the group consisting of an isocyanurate group, a biuret group, a uretdione group, and an allophanate group and is constructed from at least one selected from the group consisting of an aliphatic isocyanate and a cycloaliphatic isocyanate, under reaction conditions under which urethane groups are formed between (A) and (B), with the proviso that a molar ratio of NCO groups to OH groups between (B) and (A) is at least 3:1, and wherein the polyisocyanate (B) comprises a uretdione group.

2. The high-functionality polyisocyanate of claim 1, wherein the polyisocyanate (B) comprises at least one polyisocyanate comprising at least one isocyanurate group based on 1,6-hexamethylene diisocyanate, and having a viscosity of 600-3000 mPa*s.

3. A two-component coating composition, comprising the high functionality polyisocyanate of claim 1.

4. A two-component coating composition, comprising: at least one high-functionality polyisocyanate of claim 1; at least one compound having at least 2 groups that are reactive toward isocyanate groups; and optionally, at least one selected from the group consisting of a solvent, a pigment, an additive, and a thickener.

5. A process for preparing a polyurethane coating material, comprising: reacting the high-functionality polyisocyanate of claim 1 with at least one binder which comprises isocyanate-reactive groups.

6. A process for preparing a polyurethane coating material, comprising: reacting the high-functionality polyisocyanate of claim 1 with at least one binder selected from the group consisting of a polyacrylate polyol, a polyester polyol, a polyether polyol, a polyurethane polyol, a polyurea polyol, a polyetherol, a polycarbonate, a polyesterpolyacrylate polyol, a polyesterpolyurethane polyol, a polyurethanepolyacrylate polyol, a polyurethane-modified alkyd resin, a fatty-acid-modified polyesterpolyurethane polyol, a copolymer with at least one allyl ether, and a copolymer, and a graft polymer from at least one of the compounds stated.

7. A coating material, comprising the high-functionality polyisocyanate of claim 1.

8. A refinish-coating composition, wood-coating composition, and/or vehicle coating composition, comprising the high-functionality polyisocyanate of claim 1.

9. An adhesive or sealant, comprising the high-functionality polyisocyanate of claim 1.

10. The coating material of claim 7, which, in cured form, is a polyurethane coating material.

11. A method of curing a coating material, the method comprising heating a coating material comprising the high-functionality polyisocyanate of claim 1.

12. The high-functionality polyisocyanate of claim 1, having an isocyanate group content of 12-50% by weight based on the total weight of the high-functionality polyisocyanate.

13. A polyurethane coating obtained by reacting the high-functionality polyisocyanate of claim 1 with a hydroxy-functional polyacrylate polyols at a stoichiometric NCO/OH ratio of 1:1.

14. The high-functionality polyisocyanate of claim 1, wherein the alkoxylated polyfunctional alcohol (A) has an OH-functionality which is at least 3.

Description

EXAMPLES

(1) Polyisocyanate A:

(2) Basonat HI 100 from BASF SE, HDI isocyanurate having an NCO content of 22.2% and a viscosity of 3500 mPa*s at 23 C., functionality of about 3.4.

(3) Polyisocyanate B:

(4) Basonat LR 9046 from BASF SE, HDI isocyanurate having an NCO content of 23.7% and a viscosity of 1350 mPa*s at 23 C., functionality of about 3.2.

(5) Trifunctional Alcohol A:

(6) Trifunctional polyethylene oxide prepared with potassium hydroxide catalysis, starting from trimethylolpropane, and having an OH number of 600 mg KOH/g (to DIN 53240) and a molecular weight of 277 g/mol.

(7) Trifunctional Alcohol B:

(8) Trifunctional polypropylene oxide prepared with potassium hydroxide catalysis, starting from trimethylolpropane, and having an OH number of 546 (to DIN 53240) and a molecular weight of 308 g/mol.

(9) Trifunctional Alcohol C:

(10) Polycaprolactone prepared in the presence of butyltin tris(2-ethylhexanoate), starting from trimethylolpropane, by reaction with 3 equivalents of caprolactone, and having an OH number of 319 (to DIN 53240) and a molecular weight of 527.8 g/mol.

(11) Hazen Color Number:

(12) Method for determining the yellowing of technical liquids to DIN ISO 6271. An acidic solution of potassium hexachloroplatinate is used as the standard.

Comparative Example 1

(13) Basonat HI 100 from BASF SE: HDI isocyanurate having an NCO content of 22.2% and a viscosity of 2800 mPa*s at 23 C.

Comparative Example 2

(14) Desmodur N3790 from Bayer AG: HDI isocyanurate (90% in butyl acetate), having an NCO content of 17.8% and a viscosity of 2150 mPa*s at 23 C.

Example 1

(15) 300.00 g (0.5236 mol) of polyisocyanate A, 11.70 g (0.084 mol) of trimethylolpropane in 133.6 g of butyl acetate were mixed. The solution is hazy at room temperature and has an NCO content of 14.9%. The solution becomes transparent when the temperature is raised from room temperature to 60 C. The mixture was reacted with addition of dibutyltin dilaurate as catalyst. After 2 hours at 60 C., the NCO content was 12.3%. The batch was then cooled and filtered through Seitz T5500 filters. The product has a viscosity of 550 mPas at 23 C. and a color number of 14 Hazen.

Example 2

(16) 294.60 g (0.53 mol) of polyisocyanate A, 25.00 g (0.084 mol) of trifunctional alcohol A in 137.0 g of butyl acetate were mixed. The solution is transparent at room temperature and has an NCO content of 14.4%. The mixture was reacted with addition of dibutyltin dilaurate as catalyst. After 1 hour at 80 C., the NCO content was 11.5%. The batch was then cooled and filtered through Seitz T5500 filters. The corresponding product had a viscosity of 470 mPas at 23 C. and a color number of 60 Hazen.

Example 3

(17) 300.00 g (0.524 mol) of polyisocyanate A, 26.86 g (0.084 mol) of trifunctional alcohol B in 140.08 g of butyl acetate were mixed. The solution was transparent at room temperature and had an NCO content of 14.1%. The mixture was reacted with addition of dibutyltin dilaurate as catalyst. After 2 hours at 60 C., the NCO content was 10.4%. The batch was then cooled and filtered through Seitz T5500 filters. The corresponding product had a viscosity of 500 mPas at 23 C. and a color number of 18 Hazen.

Example 4

(18) 230.4 g (0.42 mol) of polyisocyanate A, 25.0 g (0.047 mol) of trifunctional alcohol C in 75.0 g of butyl acetate were mixed. The solution was transparent at room temperature. The mixture was reacted with addition of dibutyltin dilaurate as catalyst. After 1.5 hours at 60 C., the NCO content was 11.2%. The batch was then cooled and filtered through Seitz T5500 filters. The corresponding product had a viscosity of 760 mPas at 23 C. and a color number of 10 Hazen.

Example 5

(19) 350.0 g (0.65 mol) of polyisocyanate B and 5.0 g (0.050 mol) of glycerol were mixed in 152.1 g of butyl acetate. The solution was transparent at room temperature. The mixture was reacted with addition of dibutyltin dilaurate as catalyst. After 2 hours at 80 C., the NCO content was 14.4%. The batch was then cooled and filtered through Seitz T5500 filters. The product obtained had a viscosity of 70 mPas at 23 C. and a color number of 20 Hazen.

(20) Performance Testing:

(21) The inventive and comparative polyisocyanates were mixed with acrylic-acid-free, hydroxy-functional polyacrylate polyols (Joncryl 922, BASF; solids content=80% in butyl acetate; OH number=143 mg KOH/g, corresponding to a stoichiometric NCO/OH ratio of 1:1) and were adjusted with butyl acetate to an application viscosity of 20 s (DIN 53 211, cup 4 mm efflux nozzle). Using a drawing frame, coatings with a wet film thickness of 200 m were applied to metal panels. The resultant clearcoats were flashed off at room temperature for 10 minutes and, for determining the scratch resistance and acid resistance, were cured at 60 C. over a period of 30 minutes. Prior to the tests the coating films were stored for 24 h at 232 C. and 5010% humidity.

(22) Test Methods:

(23) The gel time is considered to be the time between coating-material formulation and complete gelling of the coating material.

(24) For determining the drying rate of the coating-material surface, the coating material, after application, was contacted at regular intervals with a cotton pad. The test is ended when cotton fibers no longer adhere to the coating-material surface.

(25) The pendulum hardness was determined by the method of Knig (EN ISO 1522).

(26) The cross-cut was determined in accordance with EN ISO 2409. The ratings in that test are between 0 (very good adhesive strength) and 5 (very poor adhesive strength).

(27) For determining the scratch resistance of the coating material, the surface is subjected to scratching using a scouring pad containing corundum particles, under a weight of 500 g. The damage is determined via the gloss value of the coating material. The reflow is determined by heating, at the temperature indicated in the table and for the time indicated in the table, after scratching via 50 double rubs.

(28) The sulfuric acid resistance was tested (etch test) in accordance with EN ISO 2812-1 (method 3) in the temperature range of 35-75 C.:

(29) Using a pipette, a 25 m drop of 1% strength sulfuric acid was applied to a coating material, cured at a predetermined temperature (30 minutes at 80 or 130 C.) on a gradient oven panel, and this metal panel was heated in the gradient oven at 35-75 C. for 30 minutes. The panel was subsequently washed with water and dried. The parameter reported is the lowest temperature at which initial etching on the coating material was discernible.

(30) The temperature of the curing of the coating material is identified in the table by 80 C. or 130 C.

(31) n.d. stands for measurement values not determined.

(32) TABLE-US-00001 Comp. example 1 Comp. example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Cotton test (min) 260 210 100 75 48 70 210 Etch test 80 C., 0 h [ C.] <30 <30 42 39 40 38 43 after 24 h [ C.] <30 <30 42 38 40 38 43 Scratch resistance 80 C.; 20 [%] 94 93 97 97 96 95 95 Scratch resistance 80 C.; 60 [%] 100 100 101 101 101 102 102 10 double rubs; 20 [%] 2 8 13 33 34 16 n.d. 10 double rubs; 60 [%] 7 21 32 51 58 36 n.d. 50 double rubs; 20 [%] 1 1 2 2 2 2 n.d. 50 double rubs; 60 [%] 5 6 9 8 8 10 n.d. Scratch resistance 130 C.; 20 [%] 96 89 97 96 96 95 n.d. Scratch resistance 130 C.; 60 [%] 102 101 102 101 101 103 101 10 double rubs; 20 [%] 8 19 20 22 23 13 n.d. 10 double rubs; 60 [%] 25 51 50 52 56 46 n.d. 50 double rubs; 20 [%] 2 5 4 5 5 5 n.d. 50 double rubs; 60 [%] 6 15 17 18 18 18 n.d. Pendulum damping 80 C. 38 49 80 70 80 72 59 Pendulum damping 130 C. 62 73 118 111 115 107 103