Anti-corrosive paintings and coatings containing nanoparticles

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Korrózióellenes festések és bevonatok, amelyek nanorészecskéket tartalmaznak

Az európai szabadalom ellen, megadásának az Európai Szabadalmi Közlönyben való meghirdetésétől számított kilenc hónapon belül, felszólalást lehet benyújtani az Európai Szabadalmi Hivatalnál. (Európai Szabadalmi Egyezmény 99. cikk(1))

A fordítást a szabadalmas az 1995. évi XXXIII. törvény 84/H. §-a szerint nyújtotta be. A fordítás tartalmi helyességét a Szellemi Tulajdon Nemzeti Hivatala nem vizsgálta.

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Eurepaisehes Patent ami

Europaan Patent Office

Office européert des brevets

<img file="HUE034369T2_D0002.tif" />

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EP 2 352 789 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention of the grant of the patent:

15.02.2017 Bulletin 2017/07 (21) Application number: 09801812.0 (22) Date of fiiing: 07.12.2009 (51) IntCI.:

C08K 3134 &lt;^{2006 01&gt;} C09D 5108 &lt;^{2006 01&gt;}

C09D 7112 (^200β·⁰¹&gt; C08K 9104 (^200β·⁰¹&gt;

(86) International application number:

PCT/IT2009/000550 (87) International publication number:

WO 2010/064274 (10.06.2010 Gazette 2010/23) (54) ANTI-CORROSIVE PAINTINGS AND COATINGS CONTAINING NANOPARTICLES

KORROSIONSSCHUTZLACKE UND NANOPARTIKEL ENTHALTENDE BESCHICHTUNGEN PEINTURES ANTIROUILLES ET REVÉTEMENTS CONTENANT DES NANOPARTICULES (84) Designated Contracting States: (72)

AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT Ll LT LU LV MC MK MT NL NO PL PT RO SE Sl SK SM TR (74) (30) Priority: 05.12.2008 ITTV20080160 (43) (73)

Date of publication of application:

10.08.2011 Bulletin 2011/32

Proprietor: Nanto SRL 34121 Trieste (TS) (IT) (56)

Inventor: KÉNIG, Shmuel

Haifa 35081 (IL)

Representative: Santi, Filippo et al Barzanö &amp; Zanardo Roma S.p.A.

Via Piemonte 26

00187 Roma (IT)

References cited:

WO-A-03/080894 WO-A-2005/059045

US-A1- 2002 173 559 US-A1- 2006 025 505

ΕΡ 2 352 789 Β1

Note: Within nine months ofthe publication ofthe mention ofthe grant ofthe European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall nőt be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

ΕΡ 2 352 789 Β1

Description [0001] The present invention refers to nanoplatelet containing anticorrosion paints and coatings.

[0002] Particularly the present invention refers to anticorrosion paints and coatings containing nano particles consisting of inorganic aluminium-silicate having a piatelet shape, in the following defined as nanoclays.

[0003] It is known that coating, painting and primer formulations are based on polymers containing solid particulates, pigments, plasticizing agents and others technological aids dissolved in organic solvents (organic based coatings) or water (water based coatings).

[0004] It is alsó known that, among currently commercially available anticorrosion paints and coatings, epoxy, polyurethane or acrylic paints and coatings display excellent adhesion and durability properties and, particularly, are extensively used to coat steel structures in orderto retard the corrosion effects resulting from oxygen and humidity combination activity.

[0005] However, as a result of inherent composition thereof, these paints and coatings absorb humidity and do nőt represent an oxygen optimál barrier. The humidity absorption and oxygen passage are the reason fór the corrosion process of coated metals, resulting in oxide formation at metal-coat interface. Such phenomenon is then followed by coating separation (debonding) and increasing degradation of metallic substrate.

[0006] In order to overcome these limitations of previously known paints and coatings, according to US No. 6,878,767 a reduced permeability paint formulation has been disclosed, comprising afilmogen agent, a pigment and a multitude ofchemically treated nano-particles having a piatelet shape, that is mostly bi-dimensionally developed, with afew hundred and about one nanométer as to lateral dimensions and thickness, respectively. According to said patent, the percentage of platelets (preferably aluminium-silicate, in any case consisting of water-impermeable matéria!) dispersed within the formulation is 1 to 10% by volume and the platelets are chemically treated with organic (like fór example amino- or epoxy-terminated silane) or inorganic (like fór example an aliphatic acid) compounds in order tofacilitate theirorientation according to parallel direction of substrate, the paint is applied on, thus increasing the platelets intermolecular forces. By arranging according to substrate surface parallel direction, the platelets reduce available passage spaces to corrosive liquid or gas molecules and increase the distance to be travelled in order to reach the coating layer and substrate interface, thus reducing the possibility of oxide formation on the interface and successive coat debonding.

[0007] On the other hand has been demonstrated that the formulations according to US 6,878,767 do nőt allow an optimál piatelet orientation, thus reducing the waterproofing effect the platelets are added fór. By microscopic analysis, particularly Transmission Electron Microscopy (TEM), and permeation measurements it has been possible to verify that the order and the alignment at nanométer level of the nanoclays are disturbed due to the excessive formulation viscosity, resulting in a lower barrier effect to the humidity and oxygen and consequently an increased corrosion. This results from the fact that, because of their shape with a particularly extended surface in respect to thickness (high aspect ratio), the platelets added to paint polymeric resins are easily immobilized by polymer molecules.

[0008] In the light of above, it is apparent the need to provide a formulation fór anticorrosion paints and coatings containing nanometric sízed platelets overcoming the limitations of the formulations according to US 6,878,767.

[0009] In this context it is offered the problem solution according to the present invention, aiming to provide a formulation fór anticorrosion paints and coatings containing nanoclays, wherein said nanoclays are chemically treated and the viscosity is controlled in such way tofavourthe alignment of nanoclays parallel to the substrate the formulation is applied on.

[0010] The object of the present invention is therefore to provide a formulation fór anticorrosion paints and coatings containing nanoclays and a process fór the production thereof allowing the limitations of the Solutions according to known technology to be eliminated and previously described. technical results to be obtained [0011] Afurtherobject of the invention is that said formulation and process can be carried out at substantially reduced, both production and operating, costs.

[0012] Nőt last object of the invention is to propose a formulation and a process substantially simple, safe and reliable. [0013] It is therefore a first specific object of the present invention a formulation fór anticorrosion paints and coatings, based on epoxy, polyurethane, acrylic, alkydic, polyesterand mixtures thereof, dissolved in organic or inorganic solvents, and comprising a multitude of nanoparticles mostly bi-dimensionally developed, with a few hundred and about one nanométer as to lateral dimensions and thickness, respectively, wherein the rotational viscosity of the formulation at 10rpm, measured according to ASTM D4212 is lower than 55000 mPa-s and preferably is lower than 40000 mPas. [0014] In particular, according to the invention, the amount of said nanoparticles is lower than 2% by weight, based on totál weight of the formulation, preferably is lower than 1% by weight, based on totál weight of the formulation and most preferably is equal to 0,5% by weight, based on totál weight of the formulation.

[0015] Particularly, according to the invention, said nanoparticles consist of materials containing ions available fór ion exchange reactions, previously treated by ion exchange reaction with ions of long chain molecules, preferably of at least 16 carbon in orderto achieve both: good intercalation of the Na+ nanoparticles and physical compatibility with diglycidic ether of bis-phenol A mátrix.

EP 2 352 789 Β1 [0016] Always according to the invention, preferably said nanoparticles consist of silico-aluminate based materials, still more preferably montmorillonite.

[0017] Moreover, again according to the present invention, said ionsof long chain molecules areobtained by proton ising amines or other compounds compatible with other formulation components.

[0018] The invention now will be described by an illustrative, bút nőt limitative way, particularly with reference to preferred embodiments and somé illustrative examples.

[0019] According to the present invention, the platelets the formulation is made of are chemically treated in order to facilitate their orientation according to parallel direction of substrate the paint is applied on, thus increasing the platelets intermolecularforces. Moreover, the viscosity is controlled in order nőt to reach values preventing the platelets to move easily within the mátrix consisting of polymeric paint, that is to align parallel to the metallic substrate (and therefore to offer as high as possible corrosion protection) as a result of the mechanical action carried out by devices used to spread the paint layer on the substrate. Further, in order to obtain low enough viscosities it is possible to add solvents to the paint (that are evaporated during drying) or reduce the solid content of the epoxy (like: calcium carbonate, metál oxides and other solids that are used in conventional paints).

Example 1. Nanoclay preliminary treatment [0020] 50g of Cloisite Na nanoclays (NC-Na), CAS N. 1318-93-0; 95Meq/100g, from Southern Clay Products, have been dispersed in 1500ml of water at room temp. fór 30 minutes and the resulting dispersion then has been heated at 85°C and hold standing fór 2 hours.

[0021] Apart a second solution, obtained by dissolving in 1300ml of water, at temperature of 85°C, 19g of octadecylamine (ODA), C₁₈H_3gN, CAS N. 124-30-1, FW=269,51, from Fluka, cat N. 74752, has been prepared. Then hydrochloric acid (HCI) at 37% has been added up to pH 4,5, FW=36,5, and the solution stirred fór 0,3 hours.

[0022] Then this solution has been added to the water nanoclay dispersion by mixing at 85°C fór 1 hour, subsequently allowing to cool.

[0023] In these conditions, a white colour precipitate has been formed, then separated from clarified liquid and successively washed, firstly with ethanol and then, fór three times, with water.

[0024] Solid precipitate then has been collected and dried by heating at 80°C fór 15 hours and successively at 110°C fór 2 hours.

[0025] Dried precipitate consisting of plateletshaped Cloisite Nafunctionalised nanoclays isreadyto be added to paints. [0026] The principle of nanoclays treatment is to allow Na⁺ ion exchange (or other ion occurring within the nanoclays to be treated) with a long chain containing ion to be carried out. In this way the distance among the platelets forming the structure of ceramic nanoclays is increased, thus facilitating the de-lamination of the nanoclays resulting in single nanoclays (1 nm thick).

[0027] As a long chain containing ion can be used an amine, protonised with a such acid amount to allow the protonization to be carried out, that is, an ammonium ion which is exchanged with Na+ ion (specifically fór example 1 octadecylamine is protonised with hydrochloric acid).

[0028] When the protonised amine solution is added to the water dispersion of ceramic nanoclays the ion exchange occurs. Resulting precipitate consist of ODA (which is hydrophobic) treated nanoclays.

Example 2. Preparation of a priming formulation (primer) containing functionalised nanoclays [0029] Nanoclays obtained according to example 1 have been added to an epoxy priming formulation (primer), depending on various compositions as reported in table 1 and mixed until an uniform dispersion has been obtained. [0030] Various primer obtained compositions have been individually applied to identical metallic substrates, then analysed, with the results reported in table 1.

Table 1

<td> % NC</td><td> Viscosity mPaS</td><td> Thickness pm</td><td> No. of bubbles</td><td> Resistance Ω cm²</td>

<td> 0</td><td> 27000</td><td> 150</td><td> 4</td><td> 9x107</td>

<td> 0,5</td><td> 32000</td><td> 140</td><td> 0</td><td> 8x109</td>

<td> 1,0</td><td> 37100</td><td> 140</td><td> 2</td><td> 5x109</td>

<td> 2,0</td><td> 52400</td><td> 142</td><td> 2</td><td> 1x109</td>

[0031] Particularly, in table 1, %NC shows the nanoclay percentage on the totál of the formulation, viscosity is rotational

ΕΡ 2 352 789 Β1 viscosity at 10 rpm, measured according to ASTM D4212, bubble numberhas been measured after700 hoursof exposure to saline sprays (salt spray test: ASTM B117) and resistance has been measured after 700 hours of exposure and thickness of 80 |im according to Electrochemical Impedence Sprectoscopy: ISO 16773-3:2009.

Example 3. Preparation of a painting formulation containing functionalised nanoclays [0032] Nanoclays obtained according to example 1 have been added to an epoxy painting formulation, depending on the various compositions as reported in table 2, and mixed until an uniform dispersion has been obtained.

[0033] Various paint obtained compositions have been individually applied to identical metallic substrates, then analysed, with the results reported in table 1..

Table 2

<td> % NC</td><td> Viscosity mPaS</td><td> Thickness μπι</td><td> No. of bubbles</td><td> Resistance Ω cm²</td>

<td> 0</td><td> 26600</td><td> 160</td><td> 20</td><td> 2x10¹⁰</td>

<td> 0,5</td><td> 39000</td><td> 130</td><td> 0</td><td> 11x10¹²</td>

<td> 1,0</td><td> 51400</td><td> 135</td><td> 3</td><td> 8x10¹¹</td>

<td> 2,0</td><td> 85700</td><td> 130</td><td> 5</td><td> 1x10¹¹</td>

[0034] Particularly, in table 2, %NC shows the nanoclay percentage on the totál of the formulation, the viscosity is rotational viscosity at 10 rpm, measured according to ASTM D4212, the bubble number has been measured after 700 hours of exposure to saline sprays (salt spray test: ASTM B117) and resistance has been measured after 700 hours of exposure and thickness of 150 μπι according to Electrochemical Impedence Sprectoscopy: ISO 16773-3:2009.

Example 4. Comparative evaluation of detachment strength of painting formulation containing functionalised nanoclays [0035] Nanoclays obtained according to example 1, and other closite nanoclays (30 B closite) nőt subjected to the same treatment, have been added to an epoxy painting formulation, according to various compositions as reported in table 3 (the first line of the table referring to a nőt nanoclay added formulation); individually applied to identical metallic substrates (toform a low thickness coating), and successively subjected to adhesion tests, by means of pull-off analysis, with results as reported in table 3.

[0036] Pull-Off test is a direct method, according to EN ISO 4624, aiming to check the quality of a coating and it is carried out by a destructive test allowing the detachment strength of the paint coating layer to be evaluated. Fór each formulation two adhesion tests in dry and one in wet conditions have been carried out.

Table 3

<td></td><td colspan="3"> Dry adhesion (MPa)</td><td> Wet adhesion (MPa)</td>

<td></td><td> Value 1</td><td> Value 2</td><td> Average</td><td></td>

<td> Without nanoclays</td><td> 17,0</td><td> 17,0</td><td> 17,0</td><td> 12,0</td>

<td> 1% Example 1</td><td> 13,4</td><td> 15,0</td><td> 14,2</td><td> 16,4</td>

<td> 1% Closite 30 B</td><td> 5,2</td><td> 6,0</td><td> 5,6</td><td> 3,6</td>

<td> 2% Example 1</td><td> 15,0</td><td> 17,0</td><td> 16,0</td><td> 19,0</td>

<td> 2% Closite 30 B</td><td> 5,0</td><td> 5,0</td><td> 5,0</td><td> 4,8</td>

[0037] The examples allow to verify that the new formulation as described in the present invention inhibits the humidity and oxygen permeation through the protective coatings on the metallic surface, so as to minimize the corrosion effects. Such inhibition occurs as a result from the ordered and parallel orientation of surface extended inorganic nanoclays obtained by means ofthe treatment according to example 1.

[0038] Moreover, the examples show higher effectiveness of functionalised nanoclays added anticorrosion formulations according to the present invention than nőt functionalised nanoclays added formulations.

[0039] With reference to the amount of nanoclays added to the formulation fór anticorrosion paints and coatings according to the present invention, the amount of nanoclays to be used must be such nőt to result in an undesired

ΕΡ 2 352 789 Β1 viscosity increase. In order the viscosity objectives to be reached, the paint formulation can conveniently be diluted with nőt reacting reagents (organie or water based) reducing the viscosity level and evaporating after the coating curing. [0040] Pull-Off test is a direct method, according to EN ISO 4624, aiming to check the quality of a coating and it is carried out by a destructive test allowing the detachment strength ofthe paint coating layer to be evaluated. Fór each formulation two adhesion tests in dry and one in wet conditions have been carried out.

Table 3

<td></td><td colspan="3"> Dry adhesion (MPa)</td><td> Wet adhesion (MPa)</td>

<td></td><td> Value 1</td><td> Value 2</td><td> Average</td><td></td>

<td> Without nanoclays</td><td> 17,0</td><td> 17,0</td><td> 17,0</td><td> 12,0</td>

<td> 1% Example 1</td><td> 13,4</td><td> 15,0</td><td> 14,2</td><td> 16,4</td>

<td> 1% Closite 30 B</td><td> 5,2</td><td> 6,0</td><td> 5,6</td><td> 3,6</td>

<td> 2% Example 1</td><td> 15,0</td><td> 17,0</td><td> 16,0</td><td> 19,0</td>

<td> 2% Closite 30 B</td><td> 5,0</td><td> 5,0</td><td> 5,0</td><td> 4,8</td>

[0041] The examples allow to verify that the new formulation as deseribed in the present invention inhibits the humidity and oxygen permeation through the protective coatings on the metallic surface, so as to minimize the corrosion effects. Such inhibition occurs as a result from the ordered and parallel orientation of surface extended inorganic nanoclays obtained by means ofthe treatment according to example 1.

[0042] Moreover, the examples show higher effectiveness of functionalised nanoclays added anticorrosion formulations according to the present invention than nőt functionalised nanoclays added formulations.

[0043] With reference to the amount of nanoclays added to the formulation fór anticorrosion paints and coatings according to the present invention, the amount of nanoclays to be used must be such nőt to result in an undesired viscosity increase. In order the viscosity objectives to be reached, the paint formulation can conveniently be diluted with nőt reacting reagents (organie or water based) reducing the viscosity level and evaporating after the coating curing. [0044] The present invention has been deseribed by an illustrative, bút nőt limitative way, according to preferred embodiments thereof, bút it is to be understood that variations and/or modifications could be carried out by those skiIled in the art without departing from the scope thereof, as defined in enclosed claims.