CATIONIC POLYSACCHARIDE-BASED PRIMARY COATINGS FOR HYDROPHOBIC SURFACES

Abstract

The instant invention relates to primary coating compositions that comprises a cationic polysaccharide, to be applied on a hydrophobic surface before a subsequent application of a polar or water based coating composition, such a as a paint or an adhesive.

Claims

1. A primary coating composition that comprises a cationic polysaccharide.

2. The primary coating composition according to claim 1, wherein the cationic polysaccharide has a molecular weight between 20,000 and 5,000,000 g/mol.

3. The primary coating composition according to claim 1, wherein the cationic polysaccharide is a cationic cellulose, a cationic starch and/or a cationic guar.

4. The primary coating composition according to claim 1, wherein the cationic polysaccharide includes a cationic cellulose.

5. The primary coating composition according to claim 1, wherein the cationic polysaccharide includes a cationic guar.

6. (canceled)

7. (canceled)

8. (canceled)

9. A process for applying a polar composition or an aqueous composition on a hydrophobic surface, the process comprising: (E1) contacting the surface at least on certain zones with a cationic polysaccharide, whereby a coating based on said cationic polysaccharide is obtained on said zones of the surfaces, (E2) applying the polar or aqueous composition on all or part of the zones of the surface covered by the cationic polysaccharide, as obtained in step (E1).

10. The process of claim 9, wherein the applied composition is a paint.

11. The process of claim 9, wherein the applied composition is an adhesive.

12. The primary coating composition according to claim 4, wherein the cationic cellulose is cellulose modified by quaternary ammonium cationic groups.

13. The primary coating composition according to claim 12, wherein the quaternary ammonium cationic groups are ammonium groups carrying three radicals which are identical or different and selected from the group consisting of hydrogen and alkyl radical having from 1 to 10 carbon atoms.

14. The primary coating composition according to claim 13, wherein the quaternary ammonium cationic groups are trialkylammonium.

15. The primary coating composition according to claim 5, wherein the cationic guar is guar modified by quaternary ammonium cationic groups.

16. The primary coating composition according to claim 15, wherein the quaternary ammonium cationic groups are ammonium groups carrying three radicals which are identical or different and selected from the group consisting of hydrogen and alkyl radical having from 1 to 22 carbon atoms.

17. The primary coating composition according to claim 16, wherein the quaternary ammonium cationic groups are trialkylammonium.

18. The process of claim 10, wherein the paint is a waterborne paint.

19. The process of claim 11, wherein the adhesive is a waterborne adhesive.

Description

EXAMPLE

[0055] The example illustrates the effect of the deposition of the Jaguar? C162 as a primer before the coating of a paint. The paint which was used in this example is the epoxy white paint of Akzo Nobel commercialized in France under the name Epoxy monocoucheJulienpeinture directe sur surface lisses?chage rapide.

[0056] The primer was deposited on polyethylene surfaces (square of 2 cm?2 cmthickness: 2 mm) and then the paint was applied on the treated polyethylene.

[0057] For seek of comparison, several tests were carried out with distinct conditions for the deposition of solution S, that are summarized in the table below.

[0058] In each test, the polyethylene surface was first cleaned with isopropanol by immersion during 30 minutes at 20? C., overnight dried under hood, and then rinsed with water and dried.

[0059] The rinsed and dried surface of polyethylene was then immersed in the aqueous solution S at 20? C., with an immersion time indicated below, and then the surface was dried, and optionally rinsed with water as indicated in the table (when rinsed with water, the surface was then dried)

[0060] As a comparison, a blank (test no. 1) was performed in the same conditions, but without any pretreatment of the polyethylene surface; and another test (no. 6) as been performed with a commercial primer (namely the DUPLI-COLOR primer commercialized by Motip Dupli, applied by a spray coating according to the recommendation of the supplier).

[0061] After coating of the paint and drying overnight, the cohesion of the paint was tested by using a LUMIFRAC apparatus:a metallic plate was adhesive bonded on the backside of the sample (on the non painted face of the sample) and cured at 22? C., the painted surface was cleaned with ethanol (fibre free cloth) and then dried by evaporation for more 15 minutes. Then a stamp was adhesive bonded to the paint surface (with a two-component epoxy adhesive 3M Scotch Weld DP 490) and the surface with this stamp was placed in the LUMIFRAC apparatus, wherein it was submitted to an increasing centrifugation leading to an increasing traction force (linea load increase of 10 N/s), that can also be expressed as a traction strength ? on the surface of the stamp adhesive bonded to the paint, expressed in MPa. When the traction became to high, a delamination of the paint occurred, reflecting the cohesion of the paint. The table below gives the traction strength ?.sub.limit where the delamination occurred for each test (the higher ?.sub.limit, the higher the cohesion).

TABLE-US-00001 TABLE conditions of each test and measured ?.sub.limit Test no.: 1 6. (Blank) 2 3 4 5 (comparative) Immersion No 15 min 60 min Spray coating of time immersion Dupli Color in solution S the treated no yes no yes no surface is rinsed with water ? ?.sub.limit (MPa) 0.594 1.955 1.736 2.922 2.395 3.224