Water-emulsible isocyanates having improved gloss

Abstract

The invention relates to a process for the preparation of water-emulsifiable isocyanates and to their use.

Claims

1. A water-emulsifiable polyisocyanate, comprising (A) a polyisocyanate derived from at least one (cyclo)aliphatic diisocyanate, (B) a polyol having a functionality of hydroxyl groups of at least 2 and up to 4 and a number-average molar weight of at least 92 to 1500 g/mol, (C) a monoalcohol comprising at least 7 ethylene oxide groups, and (D) optionally a solvent, wherein: a ratio of NCO groups in (A) to hydroxyl groups in (B) and (C) is from 5:1 to 100:1, an amount of ethylene oxide groups, calculated as 44 g/mol, based on a sum total of (A), (B) and (C), is at least 12% by weight, an amount of component (B) is from 0.5 to 4.0% by weight, based on the sum total of (A), (B) and (C), an amount of component (C) is at least 5% and up to 25% by weight, based on the sum total of (A), (B) and (C), and the water-emulsifiable polyisocyanate has a viscosity at 23 C. in accordance with DIN EN ISO 3219/A.3 in a cone/plate system with a shear rate of 1000 s.sup.1 of from 2500 mPas to 12,000 mPas.

2. The water-emulsifiable polyisocyanate according to claim 1, wherein the (cyclo)aliphatic diisocyanate is selected from the group consisting of hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, 4,4-di(isocyanatocyclohexyl)methane, and 2,4-di(isocyanatocyclohexyl)methane.

3. The water-emulsifiable polyisocyanate according to claim 1, wherein the polyisocyanate is an isocyanurate of hexamethylene 1,6-diisocyanate.

4. The water-emulsifiable polyisocyanate according to claim 1, wherein the polyol (B) comprises (B1) esterification product of at least one fatty acid with at least one polyalcohol and/or (B2) esterification product of at least one hydroxyalkane carboxylic acid or a lactone thereof with at least one polyalcohol and/or (B3) an optionally alkoxylated polyalcohol.

5. The water-emulsifiable polyisocyanate according to claim 4, wherein compound (B1) is castor oil having an OH number of from 160 to 173 mg KOH/g.

6. The water-emulsifiable polyisocyanate according to claim 4, wherein compound (B2) is at least one compound selected from the group consisting of: ##STR00003## where R.sup.4 is hydrogen or a C1 to C4 alkyl radical, k, l, m, and q in each case are independently a positive integer of from 1 to 5, Yi in each case is independently a radical [O(CH.sub.2).sub.z(CO)], and z is a positive integer of from 2 to 6.

7. The water-emulsifiable polyisocyanate according to claim 4, wherein compound (B3) is at least one compound selected from the group consisting of: ##STR00004## where R.sup.5 is hydrogen or a C.sub.1 to C.sub.4 alkyl radical, t, u, v, and w in each case are independently 0 or a positive integer of from 1 to 6, and each Z.sub.i 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.

8. The water-emulsifiable polyisocyanate according to claim 1, wherein the monoalcohol (C) is a compound of formula
R.sup.1O[X.sub.i].sub.kH where R.sup.1 is C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkyl optionally 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- to six-membered heterocycle comprising oxygen, nitrogen and/or sulfur atoms, k is an integer of from 7 to 35, and each X.sub.i is independently CH.sub.2CH.sub.2O.

9. A coating material, comprising: the water-emulsifiable polyisocyanate according to claim 1.

10. A coated article, comprising: a substrate; and the coating material according to claim 9 on the substrate, wherein the substrate is selected from the group consisting of wood, wood veneer, paper, paperboard, cardboard, textile, leather, nonwoven substrate, plastics surface, glass, ceramic, mineral building material, metal, and coated metal.

Description

EXAMPLES

(1) In this specification, unless indicated otherwise, parts are to be understood as meaning parts by weight.

(2) Polyisocyanate A:

(3) HDI isocyanurate having an NCO content of 22.2% and a viscosity of 2800 mPa*s at 23 C. (available commercially as Basonat HI 100 from BASF SE, Ludwigshafen).

(4) Polyether A:

(5) Monofunctional polyethylene oxide, prepared starting from methanol and with potassium hydroxide catalysis, having an OH number of 112 (according to DIN 53240) and a molecular weight of 500 g/mol. The basic catalyst residues still present were subsequently neutralized with acetic acid and the product was desalted. The same procedure also removes potassium acetate that has formed.

(6) Polyether B:

(7) Difunctional polyethylene oxide, prepared with potassium hydroxide catalysis, having an OH number of 560 (according to DIN 53240) and a molecular weight of 200 g/mol. The basic catalyst residues still present were subsequently neutralized with acetic acid.

(8) Polyether C:

(9) Trifunctional polyethylene oxide, prepared starting from trimethylolpropane and with potassium hydroxide catalysis, having an OH number of 600 mg KOH/g (according to DIN 53240) and a molecular weight of 280 g/mol. The basic catalyst residues still present were subsequently neutralized with acetic acid.

(10) Polyesterol A:

(11) Trifunctional polycaprolactone, prepared starting from trimethylolpropane, having an OH number of 310 (according to DIN 53240) and a molecular weight of 540 g/mol.

(12) Polyol A:

(13) Castor oil (OH number 164 mg KOH/g)

Comparative Example 1

(14) 174 g of polyisocyanate A and 26 g of polyether A were reacted at 85 C. for 4 hours. The corresponding product has an NCO content of 17.9%, and a viscosity of 2550 mPas at 23 C., and would be only partly water-dispersible.

Inventive Example 1

(15) 250 g of polyisocyanate A, 35 g of polyether A, and 5 g of polyol A were reacted with addition of 0.06 g of zinc neodecanoate (50% strength in butyl acetate) as catalyst. After 2 hours at 85 C., the NCO content was 17.6%. The corresponding product has a viscosity of 3900 mPas at 23 C. and a color number of 33 Hazen.

Inventive Example 2

(16) 250 g of polyisocyanate A, 45 g of polyether A, and 6 g of polyesterol A were reacted without addition of catalyst. After 3 hours at 90 C., the NCO content was 16.7%. The corresponding product has a viscosity of 4080 mPas at 23 C. and a color number of 43 Hazen.

Inventive Example 3

(17) 250 g of polyisocyanate A, 40 g of polyether A, 2 g of polyether B and 5 g of polyol A were reacted with addition of 0.06 g of dibutyltin dilaurate as catalyst. After 3 hours at 90 C., the NCO content was 16.8%. The corresponding product has a viscosity of 4680 mPas at 23 C. and a color number of 76 Hazen.

Inventive Example 4

(18) 250 g of polyisocyanate A, 44 g of polyether A, and 1.5 g of polyether C were reacted with addition of 0.03 g of dibutyltin dilaurate as catalyst. After 3 hours at 90 C., the NCO content was 17.1%. The corresponding product has a viscosity of 3530 mPas at 23 C. and a color number of 42 Hazen.

(19) Gloss Measurements:

(20) Component A:

(21) Blumor Intensiv Component from Blanchon.

(22) The 100% polyisocyanate was diluted to 70% with dipropylene glycol dimethyl ether. Then 5 g of this quantity of curing agent were added to 45 g of component A. The formulation was then stirred by hand with a wooden spatula at 140-180 rpm for approximately 20 seconds. Without being filtered, the completed varnish was then applied to a cardboard panel, using a 150 m four-way bar applicator. After drying (at 60 C. for 30 minutes), a measurement was made of the gloss from two different angles (20 and 60), using a micro TRI Gloss apparatus from Byk.

(23) TABLE-US-00001 Comp. Inv. Inv. Inv. Inv. Gloss example Example 1 Example 2 Example 3 Example 4 20 2.3 11 10.5 8.6 8.3 60 17.8 44.5 42.5 39.2 38.3