ONE-COMPONENT HEAT-ACTIVATABLE POLYURETHANE WATER-BASED ADHESIVE COMPOSITION

Abstract

One-component heat-activatable polyurethane water-based adhesive composition, which comprises, with respect to the total weight of the adhesive composition: —from 12% to 50%, by weight of dry matter, of an aqueous dispersion of a polyurethane (A) comprising alkoxysilyl pending and/or terminal groups, and —from 0.5% to 5% by weight of a glycidoxy substituted alkoxysilane compound (B) with a glycidoxy functionality of at least 2.

Claims

1-12. (canceled)

13. One-component heat-activatable polyurethane water-based adhesive composition, which comprises, with respect to the total weight of the adhesive composition: from 12% to 50%, by weight of dry matter of an aqueous dispersion of a polyurethane (A) comprising alkoxysilyl pending and/or terminal groups, and from 0.5% to 5% by weight of a glycidoxy substituted alkoxysilane compound (B) with a glycidoxy functionality of at least 2.

14. One-component adhesive composition according to claim 13, wherein the water-based dispersion of polyurethane (A) is an aqueous anionic aliphatic polyurethane aqueous dispersion.

15. One-component adhesive composition according to claim 13, wherein the alkoxy radical comprised in the alkoxysilyl pending and/or terminal groups of polyurethane (A) is selected from the group consisting of methoxy and ethoxy radicals.

16. One-component adhesive composition according to claim 13, wherein the silane compound (B) has a glycidoxy functionality of at least 3.

17. One-component adhesive composition according to claim 13, wherein it also comprises, with respect to the total weight of said adhesive composition, from 8 to 30%, by weight of dry matter, of an aqueous emulsion of a copolymer (C) of vinyl acetate and ethylene (VAE).

18. One-component adhesive composition according to claim 17, wherein the VAE (C) is such that: the Brookfield viscosity of a 55% weight/weight in dry matter aqueous dispersion of (C) is greater than 4000 mPa.Math.s at 25° C.; and/or its glass transition temperature (Tg) is greater than 0° C.

19. One-component adhesive composition according to claim 13, wherein the composition comprises up to 15% by weight of dry matter of an aqueous dispersion of a non silylated polyurethane (D).

20. One-component adhesive composition according to claim 13, wherein water represents from 20% to 60% by weight of the total weight of the adhesive composition.

21. One-component adhesive composition according to claim 17, wherein it comprises: from 12% to 40%, by weight of dry matter of the aqueous dispersion of polyurethane (A); from 0.5% to 2% by weight of compound (B); from 9 to 28%, by weight of dry matter of the aqueous emulsion of VAE copolymer (C); and between 3 and 13% by weight of dry matter of the aqueous dispersion of non silylated polyurethane (D).

22. Process of manufacturing the heat-activatable polyurethane water-based adhesive composition of claim 13, said process comprising the steps of: i. introducing an aqueous emulsion of the VAE copolymer (C), when present, in a mixing vessel under stirring; then ii. introducing the aqueous dispersion of the polyurethane (A), in said vessel under constant stirring; then iii. introducing silane compound (B) in said vessel, still under stirring.

23. Method of joining a substrate and a decorative expandable thermoplastic cover material, by thermoforming lamination, said method comprising the steps of: a) applying the heat-activatable polyurethane water-based adhesive composition of claim 13, on the surface of said substrate; b) drying the applied composition to remove water; then c) applying the expandable thermoplastic cover material on the substrate surface coated with the dried adhesive composition, by a thermoforming lamination process.

24. Method according to claim 23, wherein the expandable thermoplastic cover material is a PVC foil.

Description

EXAMPLES 1-5 (ACCORDING TO THE INVENTION)

[0094] The water-based adhesive compositions of examples 1-5 in Table 1 were prepared by simple mixing of their ingredients under stirring, as pointed out above in the detailed description of the process according to the invention.

[0095] Each of these adhesive compositions was implemented in the preparation of laminates through thermoforming lamination, as follows.

[0096] Use was made, as the substrate, of a square ABS plaque of 10 cm side and 3 mm thickness and, as the thermoplastic cover, of a PVC foil of 22 cm length, 2.5 cm width and 1.5 mm thickness.

[0097] Each of the compositions were sprayed on the ABS rigid substrate at a controlled coating weight comprised in the range from 100 to 120 g/m.sup.2 (expressed as wet amount). Then, the coated ABS substrate was placed in an oven at 50° C. for 10 minutes, for drying. The PVC foil was then heat-pressed onto the dried coated ABS substrate, at a temperature of 70° C. for both the upper and lower panels of the laboratory press, and at a nominal pressure of 2 MPa which was maintained for 10 seconds.

[0098] Laminates thus prepared were submitted to a 180° peel test on an Instron tensile strength tester, with the jaw speed set at 300 mm/min. This test was carried out after allowing the laminates to stand at room temperature after their preparation: 1 minute (to assess initial strength) or 1 day (to assess final strength).

[0099] The results obtained have been expressed in N/25 mm and gathered in Table 1.

[0100] All examples show a 180° peel result after 1 minute which is greater than 15 N/25 mm, which is considered as quite appropriate.

[0101] Further, the 180° peel result after 1 day is, for all examples, greater than 50 N/25 mm, which corresponds to a very good final strength.

[0102] In addition, for the examples 3, 4 and 5, the final strength is even more improved, being greater than 85 N/25 mm. For these 3 examples, a substrate failure of the PVC skin (noted SF in Table 1) is also observed, which means that said PVC skin is, during the peeling operation, torn on a percentage of its surface which is assessed and also pointed out in Table 1 just before the SF letters. Such a failure mode for the corresponding laminate contrasts with the adhesive failure mode observed for examples 1 and 2 and points towards an excellent degree of structural integrity for the adhesive joint of the laminate.

EXAMPLES A-C (COMPARATIVE)

[0103] Examples 1-5 are reproduced, with the detailed compositions shown in Table 1, replacing, as the silane compound (B) CoatOSil® MP 200 by Silquest® Wetlink 78 which is available from MOMENTIVE and which is a mono-functional 3-glycidoxypropyl alkoxysilane.

[0104] The peel test results are also shown in Table 1.

[0105] The peel values after 1 day are less than 50 N/25 mm, which is considered as quite inappropriate.

TABLE-US-00001 TABLE 1 Content in % weight/weight Ex. A Ex. B Ex. C Ingredients Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 (comp) (comp) (comp) (A) ADWEL ® 1530 36.5 35 36.5 35 12.5 36.5 35 12.5 (% w/w dry matter) (B) CoatOSil ® MP 200 1 1 1 1 1 — — — Silquest ® Wetlink 78 — — — — — 1 1 1 (C) DA 104 9.9 16.5 — — — — — (% w/w dry matter) VINNAPAS ® 645 — — 9.9 16.5 27.5 9.9 16.5 27.5 (% w/w dry matter) (D) DISPERCOLL ® U XP 4.5 — 4.5 — 12.5 4.5 — 12.5 2682 (% w/w dry matter) PREVENTOL ® D7 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 AMP-95 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 ANTIFOAM 691 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 HYDROPALAT ® WE 3475 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 DEURHEO ® WT-180F 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Blue C6 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Water 47.45 46.85 47.45 46.85 45.85 47.45 46.85 45.85 (N/25 180° peel after 1 mn 19 31 35 25 33 27 18 30 mm) 180° peel after 1 day 54 79 107/96% SF 92/42% SF 102/71.5% SF 25 46 37