ADHESION PROMOTER FOR COATINGS ON METAL SURFACES

Abstract

Coating or resin compositions substantially free of bisphenol A with excellent surface adhesion comprising a compound in an effective amount of less than 10% w/w based on the resin with the following structure:

##STR00001##

The adhesion promoters are preferably aldehyde condensation products of aromatic carboxylic acid, phosphonic acid, phosphinic acid, sulphonic acid or sulphinic acid or its corresponding ionic form.

Claims

1. Coating or resin composition comprising a compound in an effective amount of less than 10% w/w based on the resin with the following structure: ##STR00007## wherein X and Y are each independently selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyls, substituted aryls, polar functional groups, alcohol, mercapto, amines, amides, ketones, aldehydes, carboxylic acids, phosphonic acids, phosphinic acids, sulphonic acids, sulphinic acids and heterocycles; and wherein W and Z are each independently selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyls, substituted aryls, polycylic aromatics, substituted polycyclic aromatics, polar functional groups, alcohol, amines, ketones, aldehydes, carboxylic acids, phosphonic acids, phosphinic acids, sulphonic acids, sulphinic acids and heterocycles.

2. The composition according to claim 1, wherein the aromatic moiety is selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene and structure homologues.

3. The composition according to claim 1, wherein one of the substituents X or Y is selected from the group consisting of a carboxylic acid, hydroxyl group, phosphonic acid, phosphinic acid, sulphonic acid, sulphinic acid and heterocycles or their corresponding ionic form (either metal salts or neutralized with an alkaline.

4. The composition according to claim 1, wherein one of the substituents X or Y is a hydroxyl group or carboxylic acid or their corresponding ionic form.

5. The composition according to claim 1, wherein one of the substituents X or Y is a carboxylic acid or its corresponding ionic form.

6. The composition according to claim 1, wherein the aromatic moieties are linked via aldehyde condensation.

7. The composition according to claim 6, wherein the aldehyde is selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxal and furfural.

8. The composition according to claim 6, wherein the aldehyde is condensated with one of a hydroxyl benzoic acid, dihydroxyl benzoic acid, trihydroxyl benzoic acid, hydroxyl dicarboxylic benzene and dihydroxyl dicarboxylic benzene.

9. The composition according to claim 6, wherein the aldehyde is condensated with salicylic acid.

10. The composition according to claim 1, wherein the starting materials comply with FDA (21CFR175.300) and EFSA (EU directive, No 10/2011) regulations for direct food contact.

11. The composition according to claim 1, wherein the adhesion promoter is admixed with a resin system selected from the group consisting of polyester/aminoplast resin, polyol/aminoplast resin, polyacrylate/aminoplast and alkyd resin/aminoplast.

12. The composition according to claim 1, wherein the resin mixture further comprises one or more of pigments, dyes, fillers, waxes, solvents, neutralizers, stabilizers, flow additives, slip additives, rheology improvers or mixtures thereof.

13. (canceled)

14. A method of coating a surfaces comprising: applying a composition according to claim 1 on at least a portion of the surface; and curing between 0 and 300 C.

15. A coating composition comprising a resin and an adhesion promoter of the formula: ##STR00008## wherein n is a number from 0 to 1000; wherein X.sub.1 and Y.sub.1 are each independently selected from the group consisting of hydroxyl and polar functional groups, alcohol, mercapto, nitro, amines, primary amides, secondary amides, ketones, aldehydes, epoxy phosphate esters, sulphates, carboxylic acids, phosphonic acids, phosphinic acids, sulphonic acids, sulphinic acids and heterocycles; wherein W.sub.1 is independently selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyls, substituted aryls, polycylic aromatics, substituted polycyclic aromatics, polar functional groups, alcohol, mercapto, nitro, amines, primary amides, secondary amides, ketones, aldehydes, epoxy phosphate esters, sulphates, carboxylic acids, phosphonic acids, phosphinic acids, sulphonic acids, sulphinic acids and heterocylces; and wherein at least one of X.sub.1 and Y.sub.1 is hydroxyl and the other group is a polar functional group.

16. The coating composition according to claim 15, wherein the adhesion promoter comprises a condensate of salicylic acid and formaldehyde.

17. The composition according to claim 1, wherein the composition is substantially free of bisphenol A.

18. The composition according to claim 17, wherein the composition further embodies excellent surface adhesion.

19. The composition according to claim 17, wherein the composition further embodies excellent metal surface adhesion.

20. The method according to claim 14, wherein curing occurs between 50 and 250 C.

21. The method according to claim 14, wherein curing occurs between 140 and 220 C.

Description

EXAMPLES

Examples 1 and 2 and Comparative Examples A and B

[0059] Formaldehyde salicylic add condensation products have been synthesized according to the procedure described in U.S. Pat. No. 4,245,083, example 1. After reaction, the polymer has been dissolved in butylglycol and neutralized with dimethylarninoethanol and diluted with water to obtain a yellow liquid, which can be handled easily

[0060] The formaldehyde salicylic acid condensate has been admixed (5% as solid on total amount of resin) with standard thermal curable coating system and tested on both aluminum and steel panels. The standard coating system contains: 10.0 g Cymel 3745, 1.0 g 1,6-hexanediol, 3.0 g butylglycol, 0.14 1-butanol and 0.03 g Cycat 500. After thermal curing (200 C., 3 minutes), cross cuts have been made in the panels and pasteurized for one hour at 90 C. Adhesion has been tested with Scotch 3M tape (ASTM D3359).

TABLE-US-00001 Adhesion (0-5, 0 = full Appearance adhesion loss; Exam- after 5 = no ple Composition Substrate pasteurization adhesion loss) A Standard Aluminum Adhesion Full adhesion loss on loss (0) cross cuts B Standard Steel Adhesion Full adhesion loss on loss (0) cross cuts 1 Standard plus Aluminum No No adhesion 5% salicylic blushing loss (5) acid/formal- dehyde condensate 2 Standard plus Steel No No adhesion 5% salicylic blushing loss (5) acid/formal- dehyde condensate

[0061] The experiments show that the components according the invention showed excellent adhesion in various concentrations on both aluminum and steel.

Examples 3 to 13 and Comparative Example C

[0062] Aluminum cans (33cl) are treated with 40 mg XL. Black ink from INX. The treated cans were cut into pieces of 5 cm width. The can pieces are covered by a varnish by means of a spiral bar (8 micron). The varnish contains 100 g Cymel 303LF, log 1,6-hexanediol, 30 g butyl glycol, 0.20 g wetting agent, 0.60 g sulphonic acid catalyst and 10 g demineralized water. To the varnishes of the invention a compound of the invention is added in an amount of 5 wt %; the compounds are tabulated in the Table below. The compounds or condensates were prepared by thoroughly mixing the starting materials (in composition column) in a 250 ml glass flask. Subsequently, 0.5 g sulphonic acid catalyst (NaCure 155 by King Industries) was admixed. The mixture was stirred and allowed to boil for 2 hours. To some of the reaction mixturesin cases that require water solubilityaqueous dimethylamino ethanol is added to solubilize the condensate.

TABLE-US-00002 Example C No promoter 3 Urad DD79 BPA-phosphate ester 4 Condensate 1 Salicylic Acid/formaldehyde (97 g/69 g) 5 Condensate 2 Salicylic Acid/formaldehyde (245 g/46 g) 6 Condensate 3 Salicylic Acid/4-t-butyl phenol/ formaldehyde (12 g/12 g/46 g) 7 Condensate 4 Salicylic Acid/4-t-butyl phenol/ formaldehyde (5 g/19.7 g/45 g) 8 Condensate 5 4-Hydroxybenzoic acid/formaldehyde (24 g/46 g) 9 Condensate 6 4-Hydroxybenzoic/4-t-butyl phenol/ formaldehyde (5 g/18 g/46 g) 10 Condensate 7 Gallic acid/formaldehyde (24 g/46 g) 11 Condensate 8 2-Hydroxynaphthoic acid/4-t-butyl phenol/formaldehyde (4 g/10 g/46 g) 12 Condensate 9 Salicylic Acid/Glyoxal (25 g/41 g) 13 Condensate 10 Salicylic Acid/4-t-butyl phenol/ Benzaldehyde (10 g/11 g/21 g)
The treated aluminium pieces are cured at 190 C. in a box oven. All samples showed over 50 double MEK rubs, which means that the varnishes are fully cured. Cured aluminum pieces are subjected to pasteurization at 95 C. for 10 and 30 minutes, respectively, and evaluated on adhesion and scratch resistance. The results are shown in the Table below.

TABLE-US-00003 Adhesion Adhesion Adhesion after 10 after 30 after 1 Appearance Exam- min pasteur- min pasteur- hour pasteur- after pasteur- ple ization ization ization ization C Adhesion Full adhesion Full adhesion n.d. loss loss loss 3 Pass Pass Pass High scratch resistance 4 Pass Pass Pass High scratch resistance 5 Pass Pass Pass High scratch resistance 6 Pass Pass Pass High scratch resistance 7 Pass Slight loss Adhesion loss High scratch of adhesion resistance 8 Pass Slight loss Adhesion loss High scratch of adhesion resistance 9 Pass Pass Slight loss High scratch of adhesion resistance 10 Pass Pass Pass High scratch resistance 11 Pass Full adhesion Full adhesion n.d. loss loss 12 Pass Pass Very slight High scratch loss of adhesion resistance 13 Pass Pass Very slight High scratch loss of adhesion resistance
All varnishes in accordance with the invention show a considerable improvement in adhesion properties and appearance compared to the varnishes of Comparative Example C. The best results are obtained with salicylic acid-containing condensates.