WATER-DISPERSIBLE POLYISOCYANATES

Abstract

The present invention relates to improved water-dispersible polyisocyanates, which feature not only high ease of incorporation into aqueous polyol dispersions, even at low shear rates, for example by hand-incorporation, but also improved optical properties.

Claims

1. A water-dispersible polyisocyanate (A), comprising (a) at least one diisocyanate or polyisocyanate, (b) at least one surfactant comprising an amine and a mixture of compounds based on formulae (I) and (II): ##STR00005## in which R.sup.1 and R.sup.2 are independently alkyl, cycloalkyl or aryl, optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles, wherein in said mixture of compounds of formulae (I) and (II), a molar ratio of the compound (II) to the compound (I) is from 5:95 to 95:5, (c) at least one monofunctional polyalkylene glycol, (d) optionally at least one high molecular mass diol or polyol, (e) optionally at least one low molecular mass diol or polyol, and (f) at least one solvent (E), which comprises at least one carboxylic acid ester group and has a hydrophilic-lipophilic balance value HLB of 7.8 or less calculated by formula HLB=20*(M.sub.h/M), wherein M.sub.h represents mole weight of heteroatoms and M represents mole weight of the solvent molecule.

2. The water-dispersible polyisocyanate (A) according to claim 1, wherein the solvent (E) is based on formula (III), ##STR00006## in which R.sup.3 and R.sup.4 are independently alkyl, cycloalkyl, alkoxy or aryl, optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles.

3. The water-dispersible polyisocyanate (A) according to claim 2, wherein in in the formula (III), R.sup.3 is alkyl, alkyloxy or alkoxyalkyl and R.sup.4 is alkyl or alkoxyalkyl.

4. The water-dispersible polyisocyanate (A) according to claim 1, wherein the compound (f) is present in an amount of 0.1-60 wt. %, based on a total weight of components (a), (b), (c), (d), (e) and (f).

5. The water-dispersible polyisocyanate (A) according to claim 1, wherein the solvent (E) is butyldiglykolacetat, butylglycolacetat or butylacetat.

6. The water-dispersible polyisocyanate (A) according to claim 1, wherein the component (a) is a polyisocyanate containing allophanate and/or isocyanurate groups which is based on isophorone diisocyanate and/or 1,6-hexamethylene diisocyanate.

7. The water-dispersible polyisocyanate (A) according to claim 1, wherein in the component (b), R.sup.1 and R.sup.2 are independently selected from the group consisting of phenyl, methyl, ethyl, n-butyl, and 2-ethylhexyl.

8. The water-dispersible polyisocyanate (A) according to claim 1, wherein the compound (c) fulfills formula
R.sup.5O[X.sub.i].sub.kH in which R.sup.5 is C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkyl uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, or is C.sub.6-C.sub.12 aryl, C.sub.5-C.sub.12 cycloalkyl or a five- or six-membered heterocycle containing oxygen, nitrogen and/or sulfur atoms, optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles, k is an integer from 5 to 30, and each X.sub.i for i=1 to k is independently selected from the group consisting of CH.sub.2CH.sub.2O, CH.sub.2CH(CH.sub.3)O, CH(CH.sub.3)CH.sub.2O, CH.sub.2C(CH.sub.3).sub.2O, C(CH.sub.3).sub.2CH.sub.2O, CH.sub.2CHVin-O, CHVin-CH.sub.2O, CH.sub.2CHPh-O, and CHPh-CH.sub.2O, in which Ph is phenyl and Vin is vinyl.

9. The water-dispersible polyisocyanate (A) according to claim 8, wherein k is an integer from 7 to 13.

10. An aqueous coating composition, comprising at least one water-dispersible polyisocyanate (A) according to claim 1 and at least one aqueous polyol component (D).

11. An aqueous coating composition according to claim 10, wherein the aqueous polyol component (D) is selected from the group consisting of a polyacrylate-polyol dispersion, a polyester-polyol dispersion, a polyether-polyol dispersion, a polyurethane-polyol dispersion, a polycarbonate-polyol dispersion, and a hybrid thereof.

12. A process for preparing an aqueous coating composition, the process comprising: mixing the polyisocanate (A) according to claim 1 with at least one aqueous polyol component (D) at a maximum shear rate of 10 to 1000 s.sup.1.

13-14. (canceled)

15. A coating material, an adhesive or a sealant, comprising: at least one polyisocyanate (A) according to claim 1.

Description

EXAMPLES

Polyisocyanate A

[0197] Polyisocyanate was prepared by trimerizing some of the isocyanate groups of 1,6-diisocyanatohexane (HDI) and containing isocyanurate groups, said polyisocyanate being composed substantially of tris(6-isocyanatohexyl) isocyanurate and its higher homologs, with an NCO content of 22.2% and a viscosity at 23 C. of 2800 mPa*s (commericially available as BASONAT H1100 at BASF SE, Ludwigshafen, Germany)

Hydrophilic Compound B1

[0198] Monofunctional polyethylene oxide was prepared starting from methanol and with potassium hydroxide catalysis, with an average OH number of 160 mg KOH/g, measured according to DIN 53 240, corresponding to a molecular weight of 350 g/mol. The residues of catalyst still present were subsequently neutralized with acetic acid and the product was desalinated. In the course of this procedure, potassium acetate formed was also removed.

Hydrophilic Compound B2

[0199] Mixture of butylphosphate and dibutylphosphate (molar ratio 1.3/1.0) neutralized with triethylamine.

Example 1

[0200] 250 g Polyisocyanate A, 8.8 g hydrophilic compound B1 and 16 g hydrophilic compound B2 were reacted at 90 C. for 3 hours. The product obtained had an NCO content of 19.3% and a viscosity of 3700 mPas at 23 C.

Coating Formulation and Properties

Formulation

[0201] Under stirring at 1000 rpm with a lab stirrer, to 532.7 g Bayhydrol A 145 (available from Bayer MaterialScience/Covestro, solids content: 45%, OH content: 3.3% calculated based on solids) was subsequently added 22.05 g Borchi Gen HMP (adhesion promoter), 3.36 g Borchi Gol 3739 (former Baysilone 3739, substrate wetting agent), 35.0 g deionized water and 8.4 g of a mixture of dimethylethanolamine:water 1:1 (adjustment to pH=8.2-8.5), followed by 98.49 g deionized water. The mixture was stirred for 45 min., and let stand without stirring for 1 d, to give 700 g of formulated dispersion component with a solids content of 35.0%.

[0202] The polyisocyanate from the above example was diluted to a solids content of 70% or 80% respectively with solvent. Mixing was performed at 1200-1300 rpm with a lab stirrer for 5 min. After degassing with nitrogen, the diluted isocyanate was let standing without stirring for 1 d, to give the polyisocyanat component.

[0203] The dispersion component and the polyisocyanate component were mixed at an index of 150, i.e. such, that in the lacquer hydroxy and isocyanate groups have a stoichiometric ratio of 1:1.5. To 25 g of the dispersion component were added 8.13 g (in case of the usage of a 70% polyisocyanate solution) or 6.69 g (in case of the usage of a 80% polyisocyanate solution), respectively, of the polyisocyanate component. After addition and waiting for 30 sec., the mixture was stirred for 30 seconds by hand using a wooden spatula. To adjust the viscosity 1.8 g (in case of the usage of a 70% polyisocyanate solution) or 1.7 g (in case of the usage of a 80% polyisocyanate solution) of deion. water, respectively, were added, to give the water-based two-component coating system.

[0204] To assess hand miscibility, two procedures were used:

a. films: films were prepared on glass via drawdown bar at 180 wet layer thickness; the films were assessed visually in terms of appearance, transparency, existence of coagulum and if so, at which diameter
b. thicker layers: The lacquer was cast on a glass plate. The glass plate was put at a 5 angle and the assessment was also done visually: optical appearance, coagulum and if so, at which diameter.

[0205] Graduations for both methods: [0206] clear=best score [0207] hazy=second-best score [0208] slightly turbid=third-best score [0209] turbid=fourth-best score [0210] coagulum=worst score

TABLE-US-00002 TABLE 1 Evaluation of films (cf., above, method a) Example or comparative 70% solution 80% solution example (CE), of the poly- of the poly- respectively Solvent isocyanate isocyanate CE1 Butoxyl.sup.[1] slightly turbid slightly turbid CE2 propylene carboante slightly turbid slightly turbid CE3 MPA.sup.[2] turbid turbid CE4 Proglyde DMM.sup.[3] slightly tubid turbid CE5 PGDA.sup.[4] hazy slightly turbid CE6 BGA.sup.[5]:DMM 1:1 turbid turbid CE7 EEP.sup.[6] slightly turbid slightly turbid Example 1 BDGA.sup.[7] clear clear Example 2 BGA.sup.[5] clear clear Example 3 butyl acetate hazy clear

TABLE-US-00003 TABLE 2 Evaluation of thicker layers (cf., above, method b) Example or comparative 70% solution 80% solution example (CE), of the poly- of the poly- respectively Solvent isocyanate isocyanate CE1 Butoxyl.sup.[1] turbid turbid CE1 propylene carbonate turbid turbid CE3 MPA.sup.[2] turbid turbid CE4 Proglyde DMM.sup.[3] turbid turbid CE5 PGDA.sup.[4] slightly turbid turbid CE6 BGA.sup.[5]:DMM 1:1 slightly turbid slightly turbid CE7 EEP.sup.[6] turbid turbid Example 1 BDGA.sup.[7] hazy hazy Example 2 BGA.sup.[5] hazy hazy Example 3 butyl acetate slightly turbid hazy
[1] 3-Methoxy-butyl acetate (from Celanese)
[2] Methoxypropyl acetate
[3] Di(propyleneglycol)dimethylether mixture of isomers (from Dow Chemical)
[4] Propyleneglycol diacetate
[5] Butylglycol acetate
[6] O-Ethyl-3-ethoxy propionate
[7] Butyldiglycol acetate

[0211] In Examples 1 to 3 the water emulsifiable polyisocyanates were mixed by hand with the aqueous dispersion of the polyol and show improved optical properties.