WO2009072905A2

WO2009072905A2 - Surface coating

Info

Publication number: WO2009072905A2
Application number: PCT/NZ2008/000325
Authority: WO
Inventors: Andreas Michael Herbert Gabriel
Original assignee: Katja Products Limited
Priority date: 2007-12-04
Filing date: 2008-12-03
Publication date: 2009-06-11
Also published as: WO2009072905A3

Abstract

A coating composition adapted or effective to bestow an anti corrosion effect on a metal substrate surface, the composition being at least substantially chromium free and having a surface active molecule or surface active ionic species in a compatible liquid carrier (whether wholly or in part polymerisable, or not), the molecule or species having a hydrophilic domain which is a single phosphonic acid group and being carbonyl-free.

Description

"SURFACE COATING"

TECHNICAL FIELD

The present invention relates to anti-corrosion compositions, protected metal surfaces, surfaces coated by compositions as previously mentioned, polymerisable compositions, coated metal surfaces, methods of coating surfaces to bestow an anti-corrosive effect, etc.

BACKGROUND ART

Traditionally surface coatings are used to provide protection from deterioration of a substrate material and in particular corrosion of metallic substrates. Known corrosion-inhibiting primers include at least a corrosion inhibiting additive and solvent.

Chromates are widely used in corrosion-inhibiting coatings owing to their overall good performance on many substrate materials and in many service environments. Further, the basic coating constituents bear practically no restrictions on the desired final coating formulation, application method or use. However, hexavalent chromium compounds are undesirable due to their toxicity and ecological impact and will require a suitable replacement.

Many alternative coating formulations of claimed lower ecological impact have been described in literature naming corrosion-inhibiting components such as zinc, aluminium, phosphoric acid, its salts and condensation products, certain silanes, sulphonic and phosphonic acids and or certain salts thereof. More related to the present invention, corrosion-inhibiting coatings containing certain α-amino-, α-hydroxy-, di- and poly-phosphonic acid salts with either certain metal pigments or amines have been described in corrosion-inhibiting coatings.

Each of the for enamed chromate-replacement strategies suffers from well-known disadvantages. Some coating formulations comprise of solid metallic pigments or chemical compounds reacted with solid metallic pigments dispersed in a liquid, resulting in a two-phase paint system with known disadvantages such as dispersion problems. Other coating formulations use reactive compounds or chemical intermediates that represent a hazard in their own right either during manufacture or application. Others arc sensitive to their environment during storage and will lose theft ability to protect quickly with shelf storage life. In some further cases the film forming binder must be selected from a restricted range of compatible compounds.

Despite numerous efforts no chromate replacement strategy has yet been developed offering the same versatility and effectiveness.

We have determined that a considerable advantage arises where, as an active molecule for the purpose of corrosion resistance (whether applied in a liquid carrier or not and/or whether carried in a polymerisable or polymerised matrix or not), is one having a molecule which has a single phosphonic acid or analogue thereof functionality as a hydrophilic domain and elsewhere has almost exclusively or largely a hydrophobic domain. Examples include organo-phosphonic acids having a single phosphonic acid functionality.

Polyphosphonate salts have hitherto been proposed in British Patent 2172599 as an inclusion in paints. We have determined however a single phosphonic functionality is preferably to a polyphosphonate functionality in any such additives.

DISCLOSURE OF INVENTION

The invention in an aspect consists in a polymerised or polmerisable (preferably resin ot resin including) composition having an inclusion of a compound or compounds the molecule(s) which has a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) (is preferably carbonyl-free) and has a hydrophobic domain yet which, when the resin has, or notionally has, polymerised and is on, or is notionally on, a metal surface of a kind attractive to the phosphonic acid functionality, the polymer holds said molecule(s) as a matrix yet still allows some migration to such a surface when such a said surface is proximate and is not fully loaded.

Preferably said surface is of a kind selected from, for example, 2inc, aluminium, steel, etc. or alloys of any such metals.

Preferably said composition is free of chromium values.

The invention in another aspect consists in a polymerised or polmerisable (preferably resin or resin including) composition having an inclusion of at least one carbonyl-free organophosphonic acid which has a single phosphonic acid functionality and has a hydrophobic domain.

In a further aspect the present invention consists in a coated metal surface, having a metal surface proximate layer provided by a polymerised (eg, resin or resin including) composition wherein the polymerised composition includes as an inclusion a compound or compounds the tnolecule(s) of which has (A) a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) and (B) a hydrophobic domain, and wherein polymerised composition holds said molecule(s) as a matrix, yet still allows some migration of such molecule(s) to such to said metal surface (eg, when proximate and not fully loaded with such molecule(s)).

In a further aspect the present invention consists in a coated metal surface, having a metal surface proximate layer provided by a polymerised (eg, resin or resin including) composition wherein the polymerised composition includes as an inclusion a compound or compounds the molecule(s) of which are carbonyl-free and has(have) (A) a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) and (B) a hydrophobic domain, and preferably wherein polymerised composition holds said molecule(s) as a matrix, yet still allows some migration of such molecule(s) to such to said metal surface (eg, when proximate and not fully loaded with such molecule (s)).

Preferably said migration occurs when there is physical damage to such a coating or a layer.

Preferably said migration occurs until such time as there is an equilibrium at the surface between such molecules as have had access and those that are ready to migrate to the surface (ie, until fully loaded).

In another aspect the present invention consists in a coating composition adapted or effective to bestow an anti corrosion effect on a metal substrate surface, the composition being at ^■ least substantially chromium free (preferably chromium free) and having a surface active molecule or surface active ionic species in a compatible liquid carrier, the molecule or species having a hydrophilic domain which is a single phosphonic acid group.

In another aspect the present invention consists in a coating composition adapted or effective to bestow an anti corrosion effect on a metal substrate surface, the composition being at least substantially chromium free (preferably chromium free) and having a surface active molecule or surface active ionic species in a compatible liquid carrier (whether wholly or in part polymerisable, or not), the molecule or species having a hydrophilic domain which is a single phosphonic acid group and being carbonyl-free.

Preferably said molecule or species is carried at least in part as a suspension.

In some forms of the present invention, said species can be carried as a part solution or a whole solution.

Most preferably however, the molecule or species is carried as a suspension in one or more liquids, at least one of which is an organic carrier (preferably an organic solvent but not necessarily for the surface active molecule or surface active species).

Preferably there can be a co-solvent presence irrespective of whether or not the active molecule or active species is carried partly dissolved and/or partly as a suspension.

Preferably the remainder or the molecule or species (the remainder being other than said hydrophilic domain) is free of any "reaction sites" and/or heteroatoms.

In a preferred form of the present invention the surface active molecule has a formula as follows: - A -

(Formula I)

In other versions the molecule or species is a source of the species or is the species:

(Formula II)

In each of Formulas I and II the R₁, R₂ and R₃ can be the same or different. Each can be H or a (saturated or unsaturated) unsubstituted branched or (saturated or unsaturated) unsubstituted unbranched alkyl or an unsubstituted (saturated or unsaturated) aryl (unsubstituted to the extent that there is no substitution by other than an alkyl and/or aryl for any H).

Preferably the alkyl and/or aryl group is saturated.

Whilst each of R₁, R₂ and R₃ can be H, preferably, in Formula I or Formula II, at least one Of R₁, R₂ and R₃ has a C content.

As used herein, R₁, R₂ and R₃ whilst alkyl as defined and/or aryl as defined, can, in any total or partial combination of R₁, R₂ and R₃, be any cyclic, fused or unfused, alkyl and/or aryl group. Such cyclic alkyl or aryl group can be fused or unfused. Preferably any such cyclic, alkyl and/or aryl group is (whether fused or unfused) devoid of any heteroring(s) or heteroatoms. Preferably any such cyclic group(s) is devoid of reaction sites.

Preferably in Formula II or Formula II the hydrophϋic domain is that domain provided by the negatively charged oxygens shown in formula 2 or which result from the free acid of formula 1.

In a further aspect the present invention consists in a coating composition effective or adapted to bestow an anticorrosion effect on a metal substrate surface, the composition being at least substantially chromium free (preferably chromium free) and having a content of a surface active molecule of Formula I as previously defined and/or a source of the species of Formula II as previously defined.

Preferably the single phosphonic acid group, or the anionic form thereof, is said hydrophilic domain of a single phosphonic acid group containing molecule or species. In another aspect the invention is an anti-corrosion coating composition having a presence of molecules at least in part as a suspension in a liquid carrier, there being only a single phosphonic acid group or anionic derivative thereof in such molecules or species.

In another aspect the invention is an anti-corrosion composition comprising or including:

From 1 to 99 w/w% of molecules of Formula I or molecules providing species of formula II.

In another aspect the invention is a method of protecting a metal surface, which method comprises or includes the steps of applying to said surface a coating of a composition comprising a resin system and a compound or compounds having single phosphonic acid domains able to attach to the 'metal and at least one hydrophobic domain, and, after at least one partial set of the resin system of that first coating, applying over that coating a compatible resin system capable of being set and/or self setting, wherein" preferably the compounds with the single phosphonic acid domains are retainable witfiinrhe matrix of the polymeric resin system of the first coating by forces that will not prevent mobility of such compounds to an adjacent exposure of the metal surface.

In another aspect the present invention is, in combination, a composition of any of the kinds aforesaid for use as a primer and a coating composition for application to such primer when dry or set, optionally to key thereto.

In another aspect the invention is a coated substrate that is a metal surface on which a coating composition of the present invention has been applied.

In another aspect the invention is a method of priming or coating a metal, said method comprising or including steps of applying (eg, by dipping, or brushing, spraying or the like) a composition of any aspect of the present invention thereto thereby to prime the metal or to coat the metal.

The method, if to prime, can include subsequent steps to provide a finish (eg, of at least two layers, the innermost being of the primer).

In another aspect the invention is a surface thus coated or primed.

In yet a further aspect the present invention consists in a coated metal surface the coated metal surface having attaching to the metal the hydrophilic domain of a molecule or species having a single phosphonic group.

Preferably said active has been applied using a coating composition, eg, of the present invention. As used herein the term "metal" in respect of the surface to be protected against corrosion by priming and/ or coating is a metal or metal alloy surface. Preferred metals include steel and alloys of iron. Examples include iron, zinc, aluminium, etc. and/ or alloys thereof.

As used herein the term "surface active" in respect of the anticorrosive active in a coating composition of the present invention, in a coating of the present invention, on a surface, etc. (all of the present invention) refers to a species/molecule having at least one hydrophilic domain (preferably only one) and otherwise a hydrophobic domain or otherwise having hydrophobic domains.

As used herein "anti corrosion effected" and other variations includes any resistance to rusting (if iron or an iron including alloy) and/or oxidation.

As used herein the term "carrier" refers to a liquid in which the active molecules and/ or species is carried (whether wholly or in part as suspended particles or as dissolved species or molecules) and irrespective of how that carrier subsequently behaves ie, evaporates, pilimarises, sets or the like.

The carrier can be a single chemical entity or a mixture of chemical entities. It can be an organic solvent. It can be a polymerisable matrix of any compatible kind.

Other liquids can be used whether in conjunction with and organic solvent or not.

As used herein "key" or variations thereof mean some method of grip/bonding/ etc. between the primer and any adjacent layer.

The reference herein to "comprising" or "including" does not rule out other actives being present and does not rule out other substances being present eg, tinting agents, suspension agents, volatiles, etc. As used herein the term "and/or" includes "and" or "or", or where the context allows, both.

As used herein "(s)" following a noun means, as might be appropriate, the singular or plural form of the noun, or both.

BRIEF DESCRIPTION OF DRAWINGS

Preferred forms of the present invention will now be described with reference to the following drawings in which:

Figure 1 is, for Example 1, a plot of cathodic delamination expressed as distance away from the defect (x_dd) in micrometers versus time in minutes,

Figure 2 is, for Example 1, a surface Potential Plot by SKP technique showing the surface potential (E_∞π) in relationship with the distance (x) away from the anodic defect,

Figure 3 is, for Example 1, a surface Potential Plot of SrCrO₄ by SKP technique showing the surface potential (E_coπ) in relationship with the distance (x) away from the anodic defect, Figure 4 is a plot, for ClOlO Mild Steel Coupons, of the mass loss experienced by ClOlO mild steel coupons coated with a primer containing any of RA6, RN6 and RNl 8 was lower than those experienced by a primer containing the same amount of zinc chromate or any other corrosion preventing pigment,

Figure 5 is a plot, for Grade 2024 Aluminium Coupons, of the mass loss experienced by the coupons coated with a primer containing Jupiter Product was the closest to those experienced by a primer containing the same amount of zinc chromate and significantly better than that of any other corrosion preventing pigments,

Figure 6 is a plot, for Hot Dip Zinc Galvanised ClOlO Grade Mild Steel Coupons of the mass loss experienced by the coupons coated with a primer containing Jupiter Product was the closest to those experienced by a primer containing the same amount of zinc chromate and significantly better than that of any other corrosion preventing pigments,

Figures 7 to 9 compare the best of RA 6, RN6 and RNl 8 ("Katja"), in each instance, against a du Pont product standard as hereinafter identified,

Figure 10 is plot in respect of Example 4 of cathodic delamination potential (vs hydrogen) against distance from defect (in micrometers) for Phenylphosphonic Acid in PVB, and

Figure 11 is the comparator to Figure 10 in respect of Example 4 with Nitrolotri (methyl phosphonic acid) in PVB.

Example 1

Cathodic Delamination

Testing Authority European University w- -_p Cathodic Delamination by Scanning Kelvin Probe Technique lest lype _(Sκp)

Test Description SKP measurement in high humidity (93% RH) of the cathodic delamination away from a large anodic defect. Cathodic sites of oxygen reduction in proximity to anodic sites are largely held responsible for the spread of corrosion. The lower the cathodic delamination rate the better the protection from corrosion.

Compared Coating Poly vinyl butyral resin ~ 30 μm containing 20% by weight of actives pigment/additive:

• strontium chromate SrCrO4 and

• 'RA6' (ie, phenylphosphonic acid as free acid) Substrate Pure Iron, Fe 99.99%

RA6 suppresses cathodic delamination significantly better than

Test result SrCrO₄ on pure iron Compound Identity RA6 is Phenylphosphonic Acid (as free acid)

Figure 1 is a plot of cathodic delamination expressed as distance away from the defect (x_dd) in micrometers versus time in minutes. In this test the coating containing SrCrO₄ delaminated faster by over one order of magnitude by comparison to the coating containing RA6.

Figure 2 is a surface Potential Plot of RA6 by SKP technique showing the surface potential (E_corr) in relationship with the distance (x) away from the anodic defect.

Figure 3 is a surface Potential Plot of SrCrO₄ by SKP technique showing the surface potential (E_coπ) in relationship with the distance (x) away from the anodic defect.

Example 2

Test Results: Cyclic Salt Spray Tests

Testing Authority New Zealand R&D Government Institute

Test Type ASTM G 85-98, StandardP ^' ractice for Modified Salt Spray (Fog) Testing, Method A5: Dilute Electrolyte Spray/Dry Cyclic Test.

This test method is reported to produce results more closely related to atmospheric corrosion than a continuous neutral salt spray test.

Test Description Samples are exposed to an environment inside a salt spray chamber operating to the requirements of ASTM B 117-97, 'Standard Practice for Operating Salt Spray (Fog) Apparatus', using the following configuration:

• 1 hour dilute electrolyte spray at 24 ± 3°C of 0.35% ammonium sulphate and 0.05% sodium chloride in deionised water, pH 5.0 to 5.4.

^' • 1 hour dry off at 35 ± 2°C

• The test duration was 168 hours (one week)

• The corrosion rate of standard mild steel coupons (ISO 9227) was found to be 185 ± 20 gm^"2 over a period of 96 hours, which is sltghtiy more corrosive (~20%) by comparison to a continuous neutral salt spray test (ASTM B 117 or ISO 9227) in the same chamber. Coating system The coating system comprised of otherwise unpigmented and transparent layers of primer and top coat. The coating system was specifically not designed to withstand a corrosive environment for long in order to comparatively evaluate the action of the additive/pigment.

Part A PVB Resin Primer 7.20 wt %

(Wacker Poliform BRl 8)

Additive/ Pigment 7.00 wt % Ethanol 49.20 wt % n-Butanol 16.15 wt %

Part B Phosphoric Acid 85% 3.65 wt % Water 3.20 wt %

Ethanol 13.60 wt %

The components were united and mixed for 5 minutes using a high speed stirrer at 1200 rpm.

Clear solution of a acrylic resin (Rohm & Haas Paraloid B-66)

Top Coat 25% in xylene

The coating applied to mass loss coupons by dipping and drying in an air convection oven at 40⁰C. The average coating thickness determined by mass gain was ~25μm -30μm, of which ~10μm were the primer layer. .

Additive/ ID Trade Name Product Type Supplier Pigments

CL2Q basic zinc and potassium

SNCZ chromate with zinc hydroxide

Actirox 215 icon (II & III) and zinc

Nubiola phosphates, hydrated

Moly-White

^Z ₉ ^; ₁ ^1Z ₉ ^ι C _al .ci .um and , zi .nc mo ,ly ,bd jates M _..oIy ^J White

Pigments

4 Phosphinal zinc aluminium phosphate SNCZ PZ04 5 Hispafos SP hydrated zinc phosphate Nubiola

6 RA6 Phenylphosphonic Acid Katja Products

Hexane phenylphosphonic

Katja Products

7 RN6 Acid

8 RN18 Octa decylphosphonic Acid Katja Products

Substrate Mass Loss Coupons

1 ClOlO Gtade Mild Steel

2 Grade 2024 Aluminium

3 Hot Dip Zinc Galvanised ClOlO Grade Mild Steel

Evaluation Mass Loss expressed as mass per unit area [gni^"2] as per ASTM G Method 1-90 'Standard Practice for Preparing, Cleaning and Evaluating Corrosion Test Specimens'.

Results are presented as the average of three individual measurements together with the standard deviation of the data set.

Compound

RA6: Phenylphosphonic Acid — free acid Identity

RN6: Hexanephenylphosphonic Acid — free acid

RNl 8: Octadecylphosphonic Acid - free acid

ClOlO Mild Steel Coupons

The mass loss experienced by ClOlO mild steel coupons coated with a primer containing any of RA6, RN6 and RNl 8 was lower than those experienced by a primer containing the same amount of zinc chromate or any other corrosion preventing pigment.

Grade 2024 Aluminium Coupons

The mass loss experienced by the coupons coated with a primer containing any of RA6, RN6 and RNl 8 was the closest to those experienced by a primer containing the same amount of zinc chromate and significantly better than that of any other corrosion preventing pigments. Hot Dip Zinc Galvanised ClOlO Grade Mild Steel Coupons

The mass loss experienced by the coupons coated with a primer containing any of RA6, RN 6 and RN 18 was the closest to those experienced by a primer containing the same amount of 2inc chromate and significantly better than that of any other corrosion preventing pigments.

Example 3

Direct Comparison of Complete Coating Systems

A commercially available automotive coating system comprising of primer, intermediate and top coat was chosen as a point of reference (Spies & Hecker, DuP ont Products).

A primer based on the same resin and solvent system to the DuPont product was formulated, replacing the anti-corrosion additive of the DuPont primer with an equivalent quantity by mass of our single phosphonic^'acid active(s).

Steel samples were then prepared by coating them with the two primers and subsequently applying the same intermediate and top coat to both types of samples. The coating systems therefore are fundamentally identical in terms of their applied coating thickness and tie and top coat. The only point of difference being the anti-corrosive pigment contained within the primer layer.

In each batch three individual samples were prepared per sample type, any numerical results are the average of three individual measurements.

1. Cyclic Corrosion Test Results (GM 9540P)

Sample Batch #1 — DuPont Coating Sample Batch #1 — Katja Coating System System 'Standard Equivalent'

Sample Batch #1 is characterised by:

• 20μm primer applied in two coats

• lOOμm top coat applied in two coats

• Equivalent levels of additives in the primer based on mass

• 32 days exposure

Sample Batch #2 — Katja Coating System Sample Batch #2 - DuPont Coating System 'Standard Equivalent'

Sample Batch #2 is characterised by: • 20μm primer applied in two coats

• lOOμm top coat applied in two coats

• Equivalent levels of additives in the primer based on mass 32 days exposure

A numerical expression of the pictorial evidence provided above is on the following page.

Cathodic Blisters

The corrosion performance of the coatings was measured in terms of the amount of catliodic blister corrosion damage occurring next to the scribe. A lower the area of cathodic delamination/blisters corresponds to a better corrosion performance of the coating.

Example 4

Figures 10 and 11 provide plots of experimental evidence of the importance of a surface active molecule (SAM) characteristics of the phosphonic acid species.

The results compare a SAM-phosphonic acid (phenylphosphonic acid) (Figure 10) to a small, polar molecule containing three phosphonic acid heads joined to a single nitrogen via three methylene bridges (Nitrilotri(methylphosphonic acid) (Figure 11). Despite the 'firepower' of having three active groups this compound does not impart corrosion preventive properties onto a steel substrate in any way comparable to the phenyl phosphonic acid.

The plots of Figures 10 and 11 are in respect of following:

_, ~ Cathodic Delamination by Scanning Kelvin Probe Technique lest lype ^_κp)

SKP measurement in high humidity (93% RH) of the cathodic delamination away from a large anodic defect. ^ _ . . Cathodic sites of oxygen reduction in proximity to anodic sites are largely held responsible for the spread of corrosion. The lower the cathodic delamination rate the better the protection from corrosion.

Poly vinyl butyral resin ~ 30 μm containing 20% by weight of pigment/additive:

Coatⁱng type _# Nitrilotri(methylphosphonic acid) N-(CH₂-PO₃Ha)₃

• Phenylphophsonic Acid Substrate Pure Iron, Fe 99.99% Test result Albeit a phosphonic acid in nature and three phosphonic acid groups per (small) molecule the polar Nitrilotri (methylphosphonic acid does not prevent cathodic delamination at all. The surface potential is that of an actively corroding surface throughout. The compound does not impart any corrosion protection

Phenylphosphonic acid, being a surface active molecule (SAM), raises and maintains a surface profile comparative to a non-corroding surface and therefore imparts corrosion protection.

Compound Identity (RA6) Phenylphosphonic Acid (as free acid)

Example 5

Example: Improved Coating Blister Resistance

Below is an example illustrating improved coating blister resistance using a salt form Katja additive.

Substrate Material

Cold rolled mild steel sheet, type 1008/1010, matte surface finish, 0.8 x 100 x 300 mm

Surface Preparation or Pre-treatment

Wiped with Spies Hecker Permanent Silicon Remover 7010 antistatic.

Katja Primer

Katja steel primer, approximate composition of the resin on a wt% was as follows: PVB Resin 18.0

Zinc-Phenyl Phosphonate 7.5 salt

Dispersion aid 1.5

Solvent 73.0

100.0

Reference Coating

Spies Hecker Wash Primer type Priomat 3688 resin and 3689 activator. Spies Hecker Permasolid HS Premium Surfacer 5310. Spies Hecker Permaαron Series 257 automotive top coat, AG211 'Super Weiss'.

Coating Application

Coatings applied (spray) to the requirements of the technical data sheets of the Spies Hecker products by a third party as appointed by DuPont.

Primer 2 coats - Priomat 8 μm DFT 2 coats - Katja 8 -20 μm DFT

Tie Coat 1 coat 80 μm DFT Top Coat 2 coats 100 μm DFT

Results

Claims

CLAIMS:

1. A polymerised or polmerisable composition having an inclusion of a compound or compounds the molecule(s) which has a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) (is preferably carbonyl-free) and has a hydrophobic domain yet which, when the resin has, or notionally has, polymerised and is on, or is notionally on, a metal surface of a kind attractive to the phosphonic acid functionality, the polymer holds said . molecule(s) as a matrix yet still allows some migration to such a surface when such a said surface is proximate and is not fully loaded.

2. ^• A composition of claim 1 free of chromium values.

3. A composition of claim 1 wherein said surface is of a kind selected from zinc, aluminium, or iron or alloys of any such metals.

4. A polymerised or polmerisable composition haying an inclusion of at least one carbonyl-free organophosphonic acid which.has a single phosphonic acid functionality and has a hydrophobic domain.

5. A composition of any one of die preceding claims that is or was resin inclusive.

6. A coated metal surface, having a metal surface proximate layer provided by a polymerised composition wherein the polymerised composition includes as an inclusion a compound or compounds the molecule(s) of which has (A) a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) and (B) a hydrophobic domain, and wherein polymerised composition holds said molecule(s) as a matrix, yet still allows some migration of such molecule(s) to such to said metal surface (eg, when proximate and not fully loaded with such molecule(s)).

7. A coated metal surface, having a metal surface proximate layer provided by a polymerised composition wherein the polymerised composition includes as an inclusion a compound or compounds the molecule(s) of which are carbonyl-free and has (have) (A) a single phosphonic acid functionality (ie, a single phosphonic acid domain or analogue thereof) and (B) a hydrophobic domain, and preferably wherein polymerised composition holds said molecule(s) as a matrix, yet still allows some migration of such molecule (s) to such to said metal surface (eg, when proximate and not fully loaded with such molecule (s)).

8. A surface of claim 6 or 7 wherein said migration occurs when there is physical damage to such a coating or a layer.

9. A surface of claim 8 wherein said migration occurs until such time as there is an equilibrium at the surface between such molecules as have had access and those that are ready to migrate to the surface (ie, until fully loaded).

10. A coating composition adapted or effective to bestow an anti corrosion effect on a metal substrate surface, the composition being at least substantially chromium free (preferably chromium free) and having a surface active molecule or surface active ionic species in a compatible liquid carrier, the molecule or species having a hydrophilic domain which is a single phosphonic acid group.

11. A composition of claim 10 that is chromium free.

12. A coating composition adapted or effective to bestow an anti corrosion effect on a metal substrate surface, the composition being at least substantially chromium free and having a surface active molecule or surface active ionic species in a compatible liquid carrier (whether wholly or in part polymerisable, or not), the molecule or species having a hydrophilic domain which is a single phosphonic acid group and being carbonyl-free.

13. A composition of claim 12 that is chromium free.

14. A composition of claim 10, 11, 12 or 13 wherein said molecule or species is carried at least in part as a suspension.

15. A composition of claim 10, 11, 12 or 13 said molecule or species can be carried as a part solution or a whole solution.

16. A composition of any one of claims 10 to 13 where the molecule or species is carried as a suspension in one or more liquids, at least one of which is an organic carrier

17. A composition of claim 16 wherein the organic carrier is an organic solvent but not necessarily for the surface active molecule or surface active species.

18. A composition of any one of claims 10 to 17 wherein there is a co-solvent presence irrespective of whether or not the active molecule or active species is carried partly dissolved and/or partly as a suspension.

19. A compositionof any one of claims 10 to 18 wherein the remainder of the molecule or species (the remainder being other than said hydrophilic domain) is free of any "reaction sites" and/or heteroatoms.

20. A composition of any one of claims 10 to 19 wherein the surface active molecule has a formula as follows:

(Formula I) wherein the R₁, R₂ and R₃ can be the same or different, each can be H or a (saturated or unsaturated) unsubstituted branched or (saturated or unsaturated) unsubstituted unbranched alkyl or an unsubstituted (saturated or unsaturated) aryl (unsubstituted to the extent that there is no substitution by other than an alkyl and/or aryl for any H).

21. A composition of any one of claims 10 to 19 wherein the surface active molecule or species is a source of the species or is the species:

(Formula II) wherein the R₁, R₂ and R₃ can be the same or different, each can be H or a (saturated or unsaturated) unsubstituted branched or (saturated or unsaturated) unsubstituted unbranched alkyl or an unsubstituted (saturated or unsaturated) aryl (unsubstituted to the extent that there is no substitution by other than an alkyl and/or aryl for any H).

22. A composition of claim 20 or 21 wherein the alkyl and/or aryl group is saturated.

23. A composition of any one of claims 20 to 22 wherein at least one of R₁, R₂ and R₃ has a C content.

24. A composition of any one of claims 20 to 23 wherein R₁, R₂ and R₃ whilst alkyl as defined and/or aryl as defined, can, in any total or partial combination Of R₁, R₂ and R₃, be any cyclic, fused or unfused, alkyl and/or aryl group, such cyclic alkyl or aryl group being fused or unfused.

25. A composition of claim 24 wherein any such cyclic, alkyl and/or aryl group is (whether fused or unfused) devoid of any heteroring(s) or heteroatoms.

26. A composition of claim 25 wherein any such cyclic group(s) is devoid of reaction sites.

27. A composition of any one of claims 21 to 26 wherein in Formula II or Formula II the hydrophilic domain is that domain provided by the negatively charged oxygens shown in Formula II or which result from the free acid of Formula I.

28. A coating composition effective or adapted to bestow an anticorrosion effect on a metal substrate surface, the composition being at least substantially chromium free and having a content of a surface active molecule of Formula I as previously defined and/or a source of the species of Formula II as previously defined in any one of claims 20 to 26.

29. A composition of claim 28 wherein the single phosphonic acid group, or the anionic form thereof, is said hydrophilic domain of a single phosphonic acid group containing molecule or species.

30. An anti-corrosion coating composition having a presence of molecules at least in part as a suspension in a liquid carrier, there being only a single phosphonic acid group or anionic derivative thereof in such molecules or species.

31. ^■ An anti-corrosion composition comprising or including: from 1 to 99 w/w% of molecules of Formula I or molecules providing species of Formula II as previously defined in any one of claims 20 to 26.

32. A method of protecting a metal surface, which method comprises or includes the steps of applying to said surface a coating of a composition comprising a resin system and a compound or compounds having single phosphonic acid domains able to attach to the metal and at least one hydrophobic domain, and, after at least one partial set of the resin system of that first coating, applying over that coating a compatible resin system capable of being set and/or self setting, wherein the compounds with the single phosphonic acid domains are retainable within the matrix of the polymeric resin system of the first coating by forces that will not prevent mobility of such compounds to an adjacent exposure of the metal surface.

33. In combination, a composition of any of the lands defined in any one of claims 1 to 5 or 10 to 31 and for use as a primer and a coating composition for application to such primer when dry or set, optionally to key thereto.

34. A coated substrate that is a metal surface on which a coating composition of any one of claims 1 to 5 or 10 to 31 has been applied.

35. A method of priming or coating a metal, said method comprising or including steps of applying (eg, by dipping, or brushing, spraying or the like) a composition of any one of claims 1 to 5 or 10 to 31 thereby to prime the metal or to coat the metal.

36. A method of claim 35 which includes at least one subsequent step to provide a finish.

37. A surface coated or primed by a method of claim 35 or 36.

38. A coated metal surface, the coated metal surface having attaching to the metal the hydrophilic domain of a molecule or species having a single phosphonic group.

39. A coated metal surface of claim 38 wherein the molecule or species has been applied using a coating composition, of any one of claims 1 to 5 and 10 to 31.