Monoallophanates based on alkoxysilane alkyl isocyanates

Abstract

A monoallophanate can be used in paint or adhesive compositions. The monoallophanate has the formula 1: ##STR00001##
where R, R.sup.1-R.sup.6 are each independently identical or different hydrocarbyl radicals having 1-8 carbon atoms, which may be branched or cyclic, or else may be integrated together to form a cyclic system, and m and n are each independently 0-2.

Claims

1. A monoallophanate having the formula (1): ##STR00003## wherein R, R.sup.1-R.sup.6 are each independently identical or different hydrocarbyl radicals having 1-8 carbon atoms, which may be branched or cyclic, or else may be integrated together to form a cyclic system, and m and n are each 0.

2. The monoallophanate according to claim 1, wherein R.sup.1 and R.sup.5 are each independently methyl or ethyl.

3. The monoallophanate according to claim 1, wherein R.sup.2 and R.sup.4 are each independently methyl or propyl.

4. The monoallophanate according to claim 1, wherein R.sup.1=R.sup.5 and R.sup.2=R.sup.4.

5. The monoallophanate according to claim 1, wherein R.sup.1 and R.sup.5 are each methyl or ethyl, and R.sup.2 and R.sup.4 are each methyl or propyl.

6. The monoallophanate according to claim 1, wherein R.sup.1=R.sup.5=methyl, and R.sup.2=R.sup.4=propyl.

7. A process for preparing the monoallophanate according to claim 1, the process comprising: reacting A) an isocyanate comprising at least one alkoxysilane group with B) a monourethane comprising at least one alkoxysilane group, at temperatures in the range from 20 to 220 C.

8. The process for preparing the monoallophanate according to claim 7, wherein the monourethane of B) is represented by formula (3):
R.sub.n(OR.sup.1).sub.3-nSiR.sup.2NH(C=O)OR.sup.3(3) wherein R, R.sup.1, R.sup.2 and R.sup.3 are each independently identical or different hydrocarbyl radicals having 1-8 carbon atoms, which may be branched or cyclic, or else may be integrated together to form a cyclic system.

9. The process for preparing the monoallophanate according to claim 8, wherein R.sup.2 is methyl or propyl, and R.sup.1 is methyl or ethyl and R.sup.3=R.sup.1.

10. The process for preparing the monoallophanate according to claim 8, wherein the monourethane of B) is N-trimethoxysilylpropylmethyl carbamate.

11. The process for preparing the monoallophanate according to claim 7, wherein the isocyanate of A) is represented by formula (2):
R.sup.6.sub.m(OR.sup.5).sub.3-mSiR.sup.4NCO(2) wherein R.sup.6, R.sup.5 and R.sup.4 are each independently identical or different hydrocarbyl radicals having 1-8 carbon atoms, which may be branched or cyclic, or else may be integrated together to form a cyclic system.

12. The process for preparing the monoallophanate according to claim 11, wherein R.sup.4 is methyl or propyl, and R.sup.5 is methyl or ethyl.

13. The process for preparing the monoallophanate according to claim 11, wherein the isocyanate of A) is isocyanatopropyltrimethoxysilane.

14. A paint composition, which comprises the monoallophanate according to claim 1.

15. An adhesive composition, which comprises the monoallophanate according to claim 1.

Description

EXAMPLES

(1) 1)

(2) Preparation of the monoallophanates according to the invention

(3) a)

(4) 236 g (1 mol) of trimethoxysilylpropylmethyl carbamate (Evonik Industries AG) and 205 g of isocyanatopropyltrimethoxysilane (Evonik Industries AG) are mixed with one another and heated to 175 C. for 2 h. Thereafter, the starling materials are removed at 100 C. and 0.3 mbar by means of a short-path distillation. This leaves 183 g (41.5%) of a clean, water-clear liquid.

(5) C13-NMR in CDCl.sub.3 (ppm): 156.9 (1); 154.4 (1); 53.5 (1); 50.5 (10); 46.3 (1); 43.2 (1); 23.2 (1); 22.6 (1). 6.7 (1); 6.5 (1).

(6) Viscosity is about 200 mPas and hence is very low.

(7) b)

(8) 236 g (1 mol) of trimethoxysilylpropylmethyl carbamate (Evonik Industries AG), 205 g of isocyanatopropyltrimethoxysilane (Evonik Industries AG) and 0.4 g of tin(II) chloride are mixed with one another and heated to 150 C. for 1 h. Thereafter, the starting materials are removed at 90 C. and 0.3 mbar by means of a short-path distillation. This leaves 339 g (76.9%) of a clean, water-clear liquid. (for NMR see above)

(9) c)

(10) 236 g (1 mol) of trimethoxysilylpropylmethyl carbamate (Evonik Industries AG), 205 g of isocyanatopropyltrimethoxysilane (Evonik Industries AG) and 1 g of iron(III) acetylacetonate are mixed with one another and heated to 90 C. for 3 h. Thereafter, the starling materials are removed at 90 C. and 0.3 mbar by means of a short-path distillation. This leaves 184 g (41.5%) of a clean, water-clear liquid. (for NMR see above)

(11) 2)

(12) Paint Formulation:

(13) 44.5 g of Setalux 1760 (OH-functional acrylate, Nuplex industries) and 30 g of inventive product a) are mixed with 25 g of butyl acetate/xylene (1:1), and 0.5 g of catalyst (VESTANAT EP-CAT 11, Evonik Industries AG) is added. This mixture is coated onto a steel sheet with a 120 m spiral coating bar and baked at 140 C. for 22 min. The coating (layer thickness 30 m) has a pendulum hardness of 176 s and a chemical resistance of >150 MEK twin strokes. It is thus fully cured.

(14) Scratch Resistance:

(15) The starting gloss is 86 scale divisions (SD) (20) After the brush test, the gloss has dropped to 84 SD. The Crockmeter test leads to a gloss of 83 SD. The loss of gloss is thus 2 or 3 SD and hence the scratch resistance is excellent.

(16) Evaluation: loss of gloss resulting from scratches 0-9 SD excellent, 10-20 very good, 21-34 good, 35-44 average, >45 poor

(17) By comparison, commercial 2-pack PUR paints based on Setalux 1760 have a loss of gloss of about 30 SD.

(18) Brush Test (Wet):

(19) Instrument: U 1 Serial no. 003, manufacturer: BASF L+F, built: 1993

(20) The paint surface is damaged with a screen fabric (nylon screen fabric no, 11, mesh size 25 m) under a weight (2 kg). The screen fabric and the paint surface are wetted copiously with a detergent solution (0.25% Persil solution in water). The test panel is moved in backward and forward strokes under the screen fabric with the aid of a motor drive. The gloss is measured before and after the test.

(21) Crockmeter Test (Dry)

(22) Instrument: U 1 Serial no. 003, manufacturer: BASF L+F, built: 1993

(23) The paint surface is damaged with a fabric (3M 281Q WetODry Polishing Paper) under a weight (920 g). The test panel is moved in backward and forward strokes under the fabric with the aid of a motor drive.