Primer with long cure time for polymeric substrates

• US 20060167190A1
• Filed: 07/11/2003
• Published: 07/27/2006
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Sika Technology Ag (Compagnie de Saint-Gobain SA)
• Original Assignee: Sika Technology Ag (Compagnie de Saint-Gobain SA)
• Inventors: Wirz, Thomas, Venetz, Fabian, Trabesinger, Gerald
• Granted Patent: US 7,507,443 B2
• Time in Patent Office: Days
• US Class Current: 525/457
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/3893 containing silicon
• CPC Class Codes: C08G 18/7831 containing biuret groups
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08J 2475/00 Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

The invention relates to a primer composition, comprising at least one polyurethane prepolymer (A) with isocyanate terminal groups, at least one aliphatic polyisocyanate (B), at least one aromatic polyisocyanate (C) and at least one reaction product (D), which may be obtained from at least one epoxysilane and at least one aminosilane or from at least one epoxysilane and at least one mercaptosilane. The invention relates to the use of the primer composition as primer for adhesives, sealants and floor coatings.

Claims

1. A primer composition comprising

at least one polyurethane prepolymer A having isocyanate end groups,

at least one aliphatic polyisocyanate B,

at least one aromatic polyisocyanate C,

at least one reaction product D obtainable from at least one epoxysilane and at least one aminosilane or from at least one epoxysilane and at least one mercaptosilane.

2. The primer composition of claim 1, characterized in that the polyurethane prepolymer A is prepared from at least one polyol and at least one polyisocyanate.

3. The primer composition of claim 2, characterized in that the polyol is a polyoxyalkylene polyol.

4. The primer composition of claim 3, characterized in that the polyol is a polyoxypropylene polyol, in particular a polyoxypropylene diol or triol.

5. The primer composition of claim 2, characterized in that the polyol has a molecular weight of 250-20 000 g/mol, in particular 500-10 000 g/mol, preferably 800-4000 g/mol.

6. The primer composition of claim 1, characterized in that the aliphatic polyisocyanate B is an aliphatically NCO-bearing isocyanurate B1 and/or an aliphatically NCO-bearing biuret B2.

7. The primer composition of claim 6, characterized in that the aliphatic NCO-bearing isocyanurate B1 is an IPDI-isocyanurate.

8. The primer composition of claim 6, characterized in that the aliphatically NCO-bearing biuret B2 is an HDI-biuret.

9. The primer composition of claim 1, characterized in that the aromatic polyisocyanate C is an aromatically NCO-bearing isocyanurate.

10. The primer composition of claim 9, characterized in that the aromatic polyisocyanate C is an aromatically NCO-bearing isocyanurate which can be prepared from toluene diisocyanate and hexamethylene diisocyanate.

11. The primer composition of claim 1, characterized in that the epoxysilane used for preparing the reaction product D is an epoxydimethoxymethylsilane, an epoxytrimethoxysilane or an epoxytriethoxysilane, preferably 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane or 3-glycidyloxypropyltriethoxysilane, especially 3-glycidyloxypropyltrimethoxysilane.

12. The primer composition of claim 1, characterized in that the aminosilane used for preparing the reaction product D is an aminodiethoxymethylsilane, aminodimethoxymethylsilane, aminotrimethoxysilane or an aminotriethoxysilane, in particular a trimethoxysilane having primary amino groups or in particular a triethoxysilane having primary amino groups, preferably 3-(2-aminoethylamino)propyltrimethoxysilane or 3-aminopropyltrimethoxysilane.

13. The primer composition of claim 1, characterized in that the reaction product D is prepared from 3-glycidyloxypropyltrimethoxysilane and 3-aminopropyltrimethoxysilane.

14. The primer composition of claim 1, characterized in that for preparing the reaction product D epoxysilane and aminosilane are used in a ratio of the number of active amine hydrogens/number of epoxy groups=3:

1-1;

3, especially 2;

1-1;

1.5, preferably 2;

1-about 1;

1.

15. The primer composition of claim 1, characterized in that for preparing the reaction product D epoxysilane and mercaptosilane are used in a ratio of the number of mercapto groups/number of epoxy groups=1.5:

1-1;

1.5, especially 1.2;

1-1;

1.2, preferably about 1;

1.

16. The primer composition of claim 1, characterized in that it further comprises at least one solvent which is not isocyanate-reactive at room temperature.

17. The primer composition of claim 16, characterized in that the solvent is a dialkyl ketone or an alkyl carboxylic acid having C1 to C6 alkyl substituents.

18. The primer composition of claim 17, characterized in that the solvent is selected from the group consisting of methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, hexyl acetate and diethyl malonate.

19. The primer composition of claim 1, characterized in that it further comprises at least one catalyst, preferably an organotin catalyst, selected in particular from the group consisting of dibutyltin dilaurate, dibutyltin dichloride, tin-thioester complexes, mono-n-butyltin trichloride, di-n-butyltin oxide, di-n-butyltin diacetate, and dibutyltin carboxylate.

20. The primer composition of claim 1, characterized in that it further comprises at least one silane selected from the group consisting of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-(4,5-dihydroimidazolyl)propyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane (monomeric or polymerized), vinyltrimethoxysilane (monomeric or polymerized), vinyltriethoxysilane (monomeric or polymerized), vintyltris(2-methoxyethoxy)silane (monomeric or polymerized), 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, methyltrimethoxysilane, methyltriethoxysilane, trimethoxypropylsilane, triethoxypropylsilane, 2-methylpropyltrimethoxysilane, triethoxyisobutylsilane, octyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, cyclohexyldimethoxymethylsilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methacryloyloxypropyltriethoxysilane (monomeric or polymerized), especially 3-glycidyloxypropyltrimethoxysilane and 3-glycidyloxypropyltriethoxysilane.

21. The primer composition of claim 1, characterized in that it comprises at least one filler, especially carbon black.

22. The use of the primer composition of claim 1 as a primer for adhesives, sealants or floor coverings, especially 1-component moisture-curing polyurethane adhesives or sealants based on polyurethanes or polyurethane-silane hybrids.

23. A method characterized in that a primer composition of claim 1 is applied by means of brush, felt, cloth or sponge to a substrate by hand or automatically or by means of robots.

24. The method of claim 23, characterized in that the substrate is glass, glass ceramic or a plastic, especially PDMS-PC or PDMS-PMMA.