ACTIVATOR FOR ACCELERATED ADHESION DEVELOPMENT

Abstract

An activator composition having a) between 0.5% and 50% by weight of a catalyst K for crosslinking two-component adhesives which is liquid at 23 C., b) between 40% and 99.5% by weight of an organic solvent L, c) between 0% and 10% by weight of at least one silane S including at least one hydrolyzable silane group and preferably at least one functional group selected from mercapto, epoxy, amino, methacryloyl, vinyl and alkyl group. The activator composition is storage stable for at least one month. The activator composition is moreover active independently of the applied amount and may be applied in layers having a thickness such that the adhesive may be applied after not more than 30 seconds.

Claims

1. An activator composition comprising a) between 0.5% and 50% by weight of a catalyst K which is liquid at 23 C. for the crosslinking of two-component adhesives, b) between 40% and 99.5% by weight of an organic solvent L, c) between 0% and 10% by weight of at least one silane S having at least one hydrolyzable silane group and at least one functional group selected from mercapto, epoxy, amino, methacryloyl, vinyl and alkyl group, wherein the catalyst K comprises a 1,3-ketoamidate complex of a metal, and in that the solvent L is selected from the group of acetone, methyl ethyl ketone, methyl n-propyl ketone, diisobutyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, acetylacetone, mesityl oxide, cyclohexanone, methylcyclohexanone, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, n-butyl propionate, diethyl malonate, 1-methoxy-2-propyl acetate, 3-methoxy-n-butyl acetate, ethyl 3-ethoxypropionate, diisopropyl ether, diethyl ether, dibutyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylbenzene, toluene, xylene, heptane, octane, naphtha, white spirit, petroleum ether, benzine, methylene chloride, methanol, ethanol, isopropanol, and mixtures of these solvents.

2. The activator composition as claimed in claim 1, wherein the solvent L is selected from the group of n-heptane, ethanol, isopropanol, methyl acetate, ethyl acetate, butyl acetate, isopropyl acetate, 1-methoxy-2-propyl acetate, 3-methoxy-n-butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethylbenzene and mixtures thereof.

3. The activator composition as claimed in claim 2, wherein the solvent L is selected from the group of n-heptane, ethanol, isopropanol, ethyl acetate, methyl ethyl ketone, and mixtures thereof, where the solvent L comprises or consists of n-heptane and/or ethanol.

4. The activator composition as claimed in claim 1, wherein the catalyst K comprises a complex of a metal selected from the group of Fe, Bi, Al, Zn and Zr.

5. The activator composition as claimed in claim 4, wherein the catalyst K comprises an organic compound selected from the group of tertiary amines, guanidines and amidines.

6. The activator composition as claimed in claim 1, wherein the activator composition is free of tin compounds.

7. The activator composition as claimed in claim 1, wherein the activator composition comprises between 0.5% and 10% by weight of silane S.

8. The activator composition as claimed in claim 1, comprising a) between 0.5% and 25% by weight of the catalyst K, b) between 65% and 99.5% by weight of the organic solvent L, c) between 0% and 10% by weight of a silane S.

9. A method of using an activator composition comprising obtaining the activator composition as claimed in claim 1, and accelerating the buildup of adhesion in a two-component adhesive using the activator composition.

10. A kit of parts comprising c) an activator composition as claimed in claim 1, d) a two-component adhesive.

11. A method of accelerating the buildup of adhesion on a substrate S1 in the bonding of the substrate S1 to a second substrate S2, comprising the steps of i) applying an activator composition as claimed in claim 1 to at least one of the two substrates; ii) flashing off the activator composition applied; iii) applying a two-component adhesive or sealant to the first substrate S1; iv) contacting the adhesive or sealant with a second substrate S2; or i) applying an activator composition as claimed in claim 1 to at least one of the two substrates; ii) flashing off the activator composition applied; iii) applying a two-component adhesive or sealant to the second substrate S1; iv) contacting the adhesive present on the second substrate S2 with the first substrate S1.

12. The method as claimed in claim 11, wherein at least one of the substrates S1 and S2 comprises a metal, a painted surface or a plastic.

13. The method as claimed in claim 11, wherein the two-component adhesive or sealant is a polyurethane adhesive or an adhesive based on silane-functional polymers.

14. An article produced by a method as claimed in claim 11.

15. The article as claimed in claim 14, wherein the article is a mode of transport.

Description

EXAMPLES

[0100] The activator compositions that follow according to table 1 were produced by adding the catalyst K to the solvent L and stirring well under nitrogen. In all cases, n-heptane was used as solvent and one % by weight of catalyst K, based on the overall resulting composition, was added.

TABLE-US-00001 TABLE 1 Activator compositions prepared. Trade name (manufacturer) Activator Catalyst K of catalyst K Comments A-1 (Ref.) Acetylacetonato-Fe(III) Fe(acac).sub.3 Soluble and (Sigma storage- Aldrich) stable A-2 (Ref.) Bi(III) carboxylate K-Kat XK-651 Soluble and (King storage- Industries) stable A-3 (Ref.) Dibutyltin dilaurate Addocat 201 Soluble and (Lanxess) storage- stable A-4 Fe(III) tris(N,N-diethyl-3- (by method in Soluble and oxobutanamidate) EP2604617) storage- stable A-5 Fe(III) tris(N,N-dibutyl-3- (by method in Soluble and oxoheptanamidate) EP2604617) storage- stable A-6 Fe(III) tris(N,N-dibutyl-3- (by method in Soluble and oxohexanamidate) EP2604617) storage- stable A-7 (Ref.) Dioctyltin dilaurate TIB KAT Soluble and 216 (TIB storage- Chemicals) stable A-8 (Ref.) Dioctyltin thioglycolate Fomrez UL-29 Slight (Momentive) precipitation after a couple of days A-9 (Ref.) Dimethyltin thioglycolate Fomrez UL- Slight 54(Momentive) precipitation after a couple of days A-10 (Ref.) 1,3,5-tris(3- Jeffcat TR-90 Soluble and (dimethylamino)propyl)- (Huntsman) storage- hexahydro-s-triazine stable

[0101] The activator compositions in table 1 were placed into tightly sealable glass bottles and, after storage at room temperature for 1 day, used for the adhesion tests. The substrate used was plates coated by cathodic dip coating (from Rocholl, Germany).

[0102] Adhesion Test of Adhesion Promoter Compositions

[0103] The compositions were applied to the substrate by means of a cellulose cloth soaked therewith (Tela, Tela-Kimberly Switzerland GmbH) or by means of a cotton bud. On application by cotton bud, distinctly more activator was applied to the bonding surface, such that running of the activator solution was visible. All substrates were cleaned immediately prior to application of the adhesion promoter composition by wiping using a cellulose cloth (Tela) that had been soaked with isopropanol and flashed off for at least 2 minutes prior to the application of the adhesion promoter composition.

[0104] 30 seconds after application of the adhesion promoter composition, SikaForce-7666 L10 BT, a two-component polyurethane adhesive, was applied by means of expression cartridge and nozzle, so as to result in a bonding area of 1545 mm and a layer thickness of 1.6 mm. SikaForce-7666 L10 BT is a high-modulus, two-component polyurethane adhesive commercially available from Sika Automotive GmbH, Germany.

[0105] After a curing time of 1 hour, the adhesive was tested after storage in a climate-controlled room (1 h) (23 C., 50% rel. air humidity), and after storage in a climate-controlled room for 24 h (24 h).

[0106] The bonding of the adhesive was tested by means of a tensile shear strength test and analysis of the fracture profile. Tensile shear strength was tested here in accordance with ISO 4587/DIN EN 1465 on a Zwick/Roell Z010 tensile tester on the above-described mutually bonded cathodically electrocoated substrates (bonding area: 1545 mm; layer thickness: 1.6 mm; measurement speed: 10 mm/min; temperature: 23 C.). All activators of the invention gave fully cohesive fracture profiles.

[0107] Adhesion was assessed via the fracture profile of the substrates pretreated with activator. What is desired is purely cohesive behavior.

[0108] All inventive compositions produced showed exceptional storage stability. Even after several months no precipitation or cloudiness was observable.

TABLE-US-00002 TABLE 2 Tensile shear strength of the test bonds. Application Cellulose cloth Cotton bud Curing time 1 h RT 24 h RT 1 h RT 24 h RT Activator Tensile shear strength [MPa] None (Ref.) 1.63* 7.80 1.63* 7.80 A-1 (Ref.) 2.20 5.49 1.41* 7.76 A-2 (Ref.) 1.24* 6.56 0.59* 4.31* A-3 (Ref.) 0.45* 5.00* 1.63 4.77* A-4 1.37 8.44 1.71 7.89 A-5 2.07 9.15 2.41 7.96 A-6 2.34 8.77 2.42 8.32 A-7 (Ref.) 0.26* 1.89* 0.57* 2.99* A-8 (Ref.) 0.65* 7.63 0.75* 5.45* A-9 (Ref.) 1.80 7.45 0.46* 6.17 A-10 (Ref.) 1.61 4.07* 0.62* 6.76 *partial or complete adhesive failure of the bond.

[0109] In addition, tests were conducted with infrared (IR) curing. This involves coating a test sheet with the activator composition as described above for the bonds, clamping it into an IR device and preheating it from below. During that time, the adhesive was applied to the opposite side. After a defined heating phase, a second coated test sheet was clamped in and hence joined. The adhesive and the activator layer had a temperature of 105 C. Thereafter, the bond was stored under standard climatic conditions for 24 h. Of all activators A-1 to A-10, only A-4, A-5 and A-6 showed a completely cohesive fracture profile and the expected strengths irrespective of the amount of the activator applied.