CORROSION RESISTANT COMPOSITIONS AND METHODS

Abstract

Coatings for a substrate include a paint or a lacquer and about 0.1% or more particles of a bi-axially oriented metalized polymer film. The film may not be soluble in a solvent or a dispersion medium of the paint or the lacquer. Coatings may be formed by bi-axially orienting a polymer film to obtain a bi-axially oriented polymeric film having thickness of at least 1 followed by a vacuum metalizing to obtain a bi-axially oriented metalized polymer film, shredding the bi-axially oriented metalized polymer film to form the particles to at least 11 mm, selecting a solvent as system or a dispersion medium of paint in which the particles of the polymer film is not substantially soluble, preparing a paint or a coating composition by using selected solvent, and dispersing the shredded particles of oriented metalized polymer film in the paint as a primer, under coat, or top coat.

Claims

1. A corrosion-resistant coating composition comprising: a paint or a lacquer; and at least 0.1% particles of a bi-axially oriented metalized polymer film, wherein the film is not soluble in a solvent or a dispersion medium of the paint or the lacquer.

2. The composition of claim 1, wherein the particles of the film are up to 10% of the composition.

3. The composition of claim 1, wherein the thickness of the film is at least 1.

4. The composition of claim 1, wherein the thickness of the film is in the range of about 1 to about 200.

5. The composition of claim 4, wherein the thickness of the film is in the range of about 1 to about 5.

6. The composition of claim 4, wherein the particles of the film have dimensions of at least 11 mm.

7. The composition of claim 1, wherein the polymer of the film is at least one of, polyethylene terephthalate, aliphatic or aromatic polyamides, aliphatic or aromatic polyimides, polysulfones, polypropylene, high, low, or medium density polyethylene, linear low-density polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, PVDF, and PTFE.

8. The composition of claim 1, wherein the polymer of the film is bi-axially oriented and further metalized with vacuum or electro deposition or electroless coating.

9. The composition of claim 1, wherein the metal of the film is at least one of, aluminium, copper, nickel, silver, gold, palladium, platinum, iridium, titanium, niobium, zirconium, hafnium or molybdenum, titanium nitride, silicon carbide, or tungsten carbide, and diamond or graphene.

10. The composition of claim 1, wherein the solvent or the dispersion medium is at least one of, water, mineral turpentine, xylene, toluene, CIX fraction, butanol, butyl acetate, ethanol, ethyl acetate, methyl ethyl ketone, cyclohexanone, methyl iso-butyl ketone, isophorone, mesityl oxide ethylene glycol mono ethyl ether, ethylene glycol mono butyl ether, and acetates of mesityl oxide ethylene glycol mono ethyl ether and ethylene glycol mono butyl ether, dimethylformamide, dimethylacetamide, sulfolane, dimethylsulfoxide, ethyl lactate, dioxane, tetrahydrofuran, alpha-pinene, delta(3)cerene, longifolin or solvents from esters, and ester alcohol acetates, alcohol propylene glycol ethers, and acetates of ester alcohol acetates and alcohol propylene glycol ethers.

11. A method manufacturing corrosion-resistant coating composition having a paint or a lacquer and at least 0.1% particles of a bi-axially oriented metalized polymer film, the film not being soluble in a solvent or a dispersion medium of the paint or the lacquer, the method comprising: bi-axially orienting a polymer film to obtain a bi-axially oriented polymeric film having thickness of at least 1 followed by a vacuum metalizing to obtain a bi-axially oriented metalized polymer film; shredding the bi-axially oriented metalized polymer film to form the particles to at least 11 mm; selecting a solvent as system or a dispersion medium of paint in which the particles of the polymer film is not substantially soluble; preparing a paint or a coating composition by using selected solvent; and dispersing the shredded particles of oriented metalized polymer film in the paint as a primer, an under coat, or a top coat.

12. The method of claim 11, wherein the paint as the primer has a pigment volume concentration of about 40%, the paint as the under coat has a pigment volume concentration of about 30%, and the paint as the top coat has a pigment volume concentration of about 15% to about 20%.

13. The method of claim 12, wherein the pigments include at least one of, titanium dioxide or iron oxide, calcium carbonate, talc, or silica extenders, a film former resin of alkyd resin, nitro cellulose, epoxy, polyester, chlorinated rubber, or vinyl resins, and a binder derived from natural vegetable oils or petroleum products.

14. The method of claim 11, wherein the solvent or the dispersion medium is at least one of, water, mineral turpentine, xylene, toluene, CIX fraction, butanol, butyl acetate, ethanol, ethyl acetate, methyl ethyl ketone, cyclohexanone, methyl iso-butyl ketone, isophorone, mesityl oxide ethylene glycol mono ethyl ether, ethylene glycol mono butyl ether, and acetates of mesityl oxide ethylene glycol mono ethyl ether and ethylene glycol mono butyl ether, dimethylformamide, dimethylacetamide, sulfolane, dimethylsulfoxide, ethyl lactate, dioxane, tetrahydrofuran, alpha-pinene, delta(3)cerene, longifolin or solvents from esters, and ester alcohol acetates, alcohol propylene glycol ethers, and acetates of ester alcohol acetates and alcohol propylene glycol ethers.

15. The method of claim 11, wherein the paint or coating composition includes additives of a thixotropic agent, associative thickeners and/or a drying agent.

16. A coated substrate comprising: the substrate; a paint or a lacquer; and at least 0.1% particles of a bi-axially oriented metalized polymer film, wherein the film is not soluble in a solvent or a dispersion medium of the paint or the lacquer, wherein the substrate has corrosion resistance of at least 500 hours by the ASTM B 117 salt spray test.

17. The substrate of claim 16, wherein the substrate is at least one of mild steel, aluminium, copper, silver, and wood.

Description

DETAILED DESCRIPTION

[0023] Because this is a patent document, general, broad rules of construction should be applied when reading it. Everything described and shown in this document is an example of subject matter falling within the scope of the claims, appended below. Any specific structural and functional details disclosed herein are merely for purposes of describing how to make and use examples. Several different embodiments and methods not specifically disclosed herein may fall within the claim scope; as such, the claims may be embodied in many alternate forms and should not be construed as limited to only examples set forth herein.

[0024] It will be understood that, although the ordinal terms first, second, etc. may be used herein to describe various elements, these elements should not be limited to any order by these terms. These terms are used only to distinguish one element from another; where there are second or higher ordinals, there merely must be that many number of elements, without necessarily any difference or other relationship. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments or methods. As used herein, the term and/or includes all combinations of one or more of the associated listed items. The use of etc. is defined as et cetera and indicates the inclusion of all other elements belonging to the same group of the preceding items, in any and/or combination(s).

[0025] It will be understood that when an element is referred to as being connected, coupled, mated, attached, fixed, etc. to another element, it can be directly connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as being directly connected, directly coupled, etc. to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., between versus directly between, adjacent versus directly adjacent, etc.).

[0026] As used herein, the singular forms a, an, and the are intended to include both the singular and plural forms, unless the language explicitly indicates otherwise. Indefinite articles like a and an introduce or refer to any modified term, both previously-introduced and not, while definite articles like the refer to the same previously-introduced term. It will be further understood that the terms comprises, comprising, includes, and/or including, when used herein, specify the presence of stated features, characteristics, steps, operations, elements, and/or components, but do not themselves preclude the presence or addition of one or more other features, characteristics, steps, operations, elements, components, and/or groups thereof.

[0027] As used herein, the term substrate refers to a structure having a surface that can be cleaned and/or protected and/or modified to provide corrosion resistance and barrier properties. Substrate is not limited to any particular type of material, despite some example embodiments using metal substrates. Corrosion-inhibiting coatings can also be applied to other substrates, such as a polymeric substrate, for example, a coated metallic substrate.

[0028] As used herein, the terms coating and painting are interchangeable. As used herein, the term coating refers to an organic or inorganic polymeric material that can be applied as liquid (e.g., paint) and/or solid (e.g., powder) to a substrate to form a polymeric film. Example polymeric materials include powder coatings, paints, sealants, conducting polymers, sol gels, etc. A coating includes a mixture of binders, solvents, pigments and/or additives. Coatings may have one or more substances from each of the four categories. Some coating properties, such as gloss and colour, are related to the film surface, i.e., as a two-dimensional entity. Other bulk properties of a coating are related to its three-dimensional structure. Phase continuity is a volume concept, and the coating performance is dependent on the integrity of the binder phase.

[0029] As used herein, the term not substantially soluble refers to a solubility level of less than about one (1) mmol/L. As used herein, the term weight percent (wt %) when used without qualification, refers to the weight percent of a particular solid component, e.g., pigment, extender, etc., compared with all solid components present, excluding polymeric resins and solvents.

[0030] As used herein, the terms paint formulation and coating composition refer to a list of ingredients and/or components and/or a list of instructions for preparing and mixing together the ingredients and/or components to make the same. As used herein, the term curing refer to evaporation of solvent. The term includes drying or curing either naturally or by accelerated means for example, an ultraviolet light cured system to form a film or cured paint.

[0031] The structures and operations discussed below may occur out of the order described and/or noted in the figures. For example, two operations and/or figures shown in succession may in fact be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Similarly, individual operations within example methods described below may be executed repetitively, individually or sequentially, to provide looping or other series of operations aside from single operations described below. It should be presumed that any embodiment or method having features and functionality described below, in any workable combination, falls within the scope of example embodiments.

[0032] The Inventor has newly recognized that there is a need to provide corrosion resistant coatings that are effective, yet not based on chromates. Corrosion of a substrate may be reduced by reducing the permeability of water and oxygen. While a coating with particles of bi-axially fully-oriented metalized film may provide the same, the Inventor has recognized that the film should not be soluble, swollen, or otherwise affected by the solvent system. Example embodiments described below address these and other problems recognized by Inventor with unique solutions enabled by example embodiments.

[0033] The present invention is corrosion-resistant coating compositions, substrates treated with the same, and methods of forming the same. In contrast to the present invention, the few examples discussed below illustrate just a subset of the variety of different configurations that can be used as and/or in connection with the present invention.

[0034] Example embodiment coatings have excellent corrosion resistance performance, while maintaining acceptable levels of paint adhesion properties. Coating compositions are useful in many industries, including, but not limited to, the shipping, aerospace and aircraft industries.

[0035] Highly-oriented films from linear film forming polymers produce films with very low permeability for different gases. They may have high barrier properties and be useable in packaging of industrial and food products. Orientation of films involves stretching the film in two directions. It may be in the form of continuous films or even bottles that are formed by blowing a heated pre-form. The bi-axial orientation of polymers results in increased density due to better packing of the molecules and the permeation properties of the product improve 15- to 20-fold. In some cases, these films are still left with permeability. To reduce it further, the films may be metalized with metals such as aluminum, copper, chromium, palladium, and/or platinum. When the contents are corrosive or the diffusivity of the gases is high (due to their solubility in the polymer), the surface may be coated with diamond-like films. Reduction in permeability may also be achieved by coating these surfaces by continuous diamond like films, called diamond like coatings (DLC) of thickness of the order of few angstroms, which make internally-coated bottles suitable for packaging of carbonated beverages and beer, which are otherwise stored in completely impervious glass bottles.

[0036] The polymers used may be polyethylene terephthalate, polyamide, polyimide, polystyrene, polysulfone, polyethylene, and/or polypropylene, and the metal coating may be aluminum. To prevent corrosion of aluminum, the metalized surface may be further coated with low-thickness of lacquer. In view of the properties of the oriented polymer films metalized with corrosion resistant metals a paint chemist wishes these properties could be attained in a coating film. The same is not possible because the polymer films need stretching several folds in two directions; that is, directions substantially perpendicular, nearing or at 90, to each other, referred to as bi-axial orientation. In this process, the length and breadth of the film increase three to five times and thickness reduces. Several properties change as a result of orientation. Permeability is one major such property. Metallization is used to further reduce the permeability.

[0037] In an example embodiment, there is provided a corrosion-resistant coating composition including particles of bi-axially oriented metalized polymer film along with paint and other additives. The film should not be soluble in the solvent or dispersion medium of the paint. The composition optionally includes a lacquer.

[0038] The coating composition may include at least 0.1% of the particles of a bi-axially oriented metalized polymer film along with a paint or a lacquer and other additives. For example, the coating composition may include 0.1 to 10% of the particles of the bi-axially oriented metalized polymer film along with the paint or the lacquer and other additives.

[0039] The oriented metalized polymer film may have low thickness of at least 1. For example, thickness of the oriented metalized polymer film may be in the range of 1 to 200, such as 1 to 5. The particles of the oriented metalized polymer film have dimensions of at least 11 mm. For example, dimension of the particles of the oriented metalized polymer film may be in the range of 1 to 6 mm1 to 6 mm, such as 11 mm to 22 mm. The metalized film particles (LBT=1-1.2 mm1-1.2 mm X=1 to 30 microns (0.001 to 0.03 mm) have been used as decorative materials for various objects where no protection is intended. Their concentration is rather low (1-2 g per litre).

[0040] The particles of the oriented metalized polymer film are added in the range of at least equivalent to two times the surface area required to be coated. For example, the particles of the oriented metalized polymer film may be added in the range of at least twice to four times surface area required to be coated, so that there is adequate overlap of the films and no part of the coating is deficient in the oriented film.

[0041] The polymer may be selected from polyethylene terephthalate; aliphatic or aromatic polyamides; aliphatic or aromatic polyimides; polysulfones; polypropylene; high, low or medium density polyethylene; linear low density polyethylene; polystyrene; polyvinyl chloride; polyvinylidene chloride; PVDF; PTFE; etc.

[0042] The polymer may be bi-axially oriented and further metalized with or without vacuum or electro deposition, or electroless coating. The metal used for the metallization of the film is selected from aluminum, copper, nickel, noble metals such as silver gold, palladium, platinum, iridium, osmium or other corrosion resistant metals such as titanium, niobium, zirconium, hafnium and also, tungsten, molybdenum, or other compounds of metals deposited by chemical vapour deposition such as titanium nitride, silicon carbide, tungsten carbide or films deposited by methane plasma such as diamond like films or graphene.

[0043] The selection of solvent may achieve excellent corrosion and barrier properties. The polymer may not be soluble or sensitive to solvents in solvent-based coating compositions.

[0044] Example embodiments further include a substrate coated with the corrosion-resistant coating composition and prepared according to example methods, the substrate has improved corrosion resistance of at least 500 hours by the American Society for Testing Materials Standard Practice B117 for Operating Salt Spray (Fog) Apparatus (hereinafter ASTM B 117), incorporated by reference herein in its entirety.

[0045] Preferably, the substrate has improved corrosion resistance of 500 to 1800 hours by the ASTM B 117 salt spray test.

[0046] The substrates that need corrosion protection and coated with the corrosion-resistant composition could be, for example, mild steel, aluminum, copper, silver or wood.

[0047] Example methods include manufacturing corrosion-resistant coating compositions with excellent corrosion resistance and barrier properties,

[0048] Example processes may include, [0049] a. bi-axially orienting a polymer film to obtain a bi-axially oriented polymeric film having thickness of at least 1 followed by a vacuum metalizing to obtain an oriented metalized polymer film; [0050] b. shredding the oriented metalized polymer film of step (a) to form the particles having dimension of at least 11 mm; [0051] c. selecting a solvent as system or dispersion medium of paint in which the particles of the polymer film of step (b) are not substantially soluble; [0052] d. preparing a paint or a coating composition by using selected solvent of step (c); and [0053] e. dispersing the shredded particles of oriented metalized polymer film of step (b) in the paint which could be a composition suited for a primer, an under coat or a top coat.

[0054] The paint as a primer, an under coat or a top coat having a pigment volume concentration in the range of 40%, 30% or 15 to 20%, respectively. The solvent or the dispersion medium is selected from water, mineral turpentine, xylene, toluene, CIX fraction, butanol, butyl acetate, ethanol, ethyl acetate, methyl ethyl ketone, cyclohexanone, methyl iso-butyl ketone, isophorone, mesityl oxide ethylene glycol mono ethyl ether, ethylene glycol mono butyl ether and their acetates, dimethylformamide, dimethylacetamide, sulfolane, dimethylsulfoxide, ethyl lactate, dioxane, tetrahydrofuran, alpha-pinene, delta(3)cerene, longifolin, or solvents from esters, ester alcohol acetates, alcohol propylene glycol ethers, and their acetates.

[0055] The paint comprising pigments selected from the group consisting of titanium dioxide, or iron oxide; extenders selected from the group consisting of calcium carbonate, talc, or silica; a film former resin selected from the group consisting of alkyd resin, nitro cellulose, epoxy, polyester, chlorinated rubber, or vinyl resins; or a binder derived from natural vegetable oils or petroleum products.

[0056] The paint or coating composition further comprising additives selected from the group consisting of thixotropic agent, associative thickeners and drying agent.

[0057] The bi-axial orientation, the metallization or the vacuum metallization, the shredding, the preparing paint/coating formulation of the polymer film is carried out by conventional process.

[0058] The selected pigments such as titanium dioxide, iron oxide and extenders such as calcium carbonate, talc, silica are first dispersed and ground to the required finenesses in conventional equipment such as a ball mill, a keddy mill, a sand mill or attritor mill. The mill base is made up with the film former resin such as alkyd resin, nitro cellulose, epoxy, polyester, chlorinated rubber, vinyl resins or any other suitable binder derived from natural vegetable oils or petroleum products. The viscosity of the composition is adjusted by addition of additives for building thixotropy, such as with organically modified clays or associative thickeners, and necessary additives required to assist drying i.e. drying agent. Depending on the thickness of the coating required on the surface, the spreading power of the coating varies from 2 to 5 m.sup.2/litre. Accordingly 4 to 10 m.sup.2 film is added to every liter of the paint in the form of 11 mm particles. The thickness of the film decides the weight of the film per unit area. For a polymer with density of 1 g/cc, the weight per m.sup.2/micron thickness is 1 gram. Thus if a film of 10 micron is selected, its weight per m.sup.2 would be 10 g. Thus, for 4 m.sup.2, 40 g of film particles would be required. For higher spreading rate coating 100 g of 10 micron thick film would be required/liter of the paint.

[0059] Thus, in a coating made from chlorinated rubber with 30% pigment volume concentration, which has a spreading rate of 2 m.sup.2 per litre, 40 g of 10 micron thick polyester film metalized with aluminium 1 mm1 mm pieces were added per litre. The coating was applied on a primed panel with a brush and the performance of the coating was compared with a panel with same painting system without the added film pieces. The panels were tested for corrosion resistance following the procedure of ASTM B 117. The panel containing film pieces outperformed the standard by more than three times (1500 hours against complete failure at the end of 500 hours)

[0060] Example embodiments may be simple yet effective for coatings with excellent corrosion resistance and barrier properties. In application, the area of the film approximately equal to two to three times the surface to be protected is acceptable. Example embodiment coatings may have lower permeability of at least three to four orders of magnitude which reduces the corrosion. This innovation is a very cost effective solution. The glass flakes have high density usually used in conventional techniques to reduce permeability and help in achieving corrosion resistance, but they have limited supply and high cost. Their addition rate is also high due to higher density of glass, such as 2 to 2.2 times more than oriented polymer films. Glass flakes are brittle and need careful handling. These are also very hard and can cause injury to the workmen if adequate care is not exercised while applying the coating. Therefore, example embodiments may be cost effective and user-friendly solutions.

[0061] Example embodiments can be illustrated with the below mentioned example but not by way of limitations. Example embodiments may be formulated and rendered by example methods described in the following examples.

Example 1

[0062] A top coat was formulated according to the parameters given in Table 1.

TABLE-US-00001 TABLE 1 Top Coat Formulation Sr. No. Components Quantity 1 Chlorinated rubber 170 g 2 Titanium dioxide 100 g 3 Talc 80 g 4 Xylene 650 ml

[0063] The solid content of the coating was 35%, density was 1.04 to 1.05 kg per litre. It's spreading rate to build a 30 dry film of thickness was 3.3 m.sup.2 per litre.

Example 2

[0064] A top coat with anti-corrosion additive namely glass flakes.

[0065] A top coat was prepared according to Table 1 having solid content of coating of 35% and density of 1.04 to 1.05 kg per litre. To one litre of this paint, 2% of 10 thick glass flakes were added. The coating was applied by brush on metal panel.

Example Method

[0066] To one litre of this paint, 52 g of 1 mm1 mm particles of 7 micron thickness of metalized film were added according to table 2.

TABLE-US-00002 TABLE 2 Top Coat Formulation Paint Metalized film 1 mm 1 mm particles and formulation Paint 7 micron thickness A Top Coat of 52 g of 1 mm 1 mm particles of 7 micron example 1, thickness of polyethylene terephthalate 1 litre paint metalized (100 A thickness) with aluminium. B Top Coat of 35 g of bi-axially oriented metalized example 1, polypropylene film metalized (100 A 1 litre paint thickness) with aluminium. C Top Coat of 35 g of bi-axially oriented high density example 1, polyethylene film metalized (100 A 1 litre paint thickness) with aluminium. D Top Coat of 35 g of bi-axially oriented high density example 1, polyethylene film metalized (100 A 1 litre paint thickness) with aluminium E Top Coat of 50 g of bi-axially oriented polyamide 6 example 1, film metalized (100 A thickness) with 1 litre paint aluminium F Top Coat of 35 g of bi-axially oriented polyamide 66 example 1, film metalized (100 A thickness) with 1 litre paint aluminium
The above-mentioned coatings of the Table 2 were applied by brush on metal panel.

[0067] The corrosion test was performed by conducting the salt spray test (ASTM B 117) for Examples 1 and 2. The barrier properties are tested by performing salt spray test. The results of the salt spray and barrier properties are tabulated (Table 3) below:

TABLE-US-00003 TABLE 3 Salt spray and barrier properties Paint Formulation Salt spray Barrier Properties Reference Blisters developed after Corrosion observed after Example 1 100 hours removal of paint from the surface Reference Blisters developed after Corrosion observed after Example 2 800 hours removal of paint from the surface A Blisters not developed till Slight corrosion observed 500 hours after removal of paint from the surface B No blisters observed till Clean metal surface found 1500 hrs on removal of the coating. C No blisters observed till Clean metal surface found 1000 hrs on removal of the coating. D No blisters observed till Clean metal surface found 1000 hrs on removal of the coating. E No blisters observed till Clean metal surface found 1200 hrs on removal of the coating. F No blisters observed till Clean metal surface found 1200 hrs on removal of the coating.

[0068] The coated panel were subjected to salt spray test for 1500 hours to compare the performance of example embodiment coatings of reference example 1 and 2. According to the results, blisters are developed in the coating of reference example 1 after 400 hours and in the coating of reference example 2 after 800 hours. This represents a 3-fold improvement. Development of blisters are indication of corrosion and hence failure of the coating.

[0069] Example embodiments may eliminate corrosion and associated problems with metalized bi-axially oriented films thereby providing surface coating with excellent corrosion resistance, barrier properties, etc. by reducing water and oxygen permeability.

[0070] Example embodiment coatings may be uniform and efficient with particles of oriented metalized film that is not soluble or swollen or shrivelled in the solvent system of the composition. Example methods create example embodiment coating compositions that allow for coating a surface of the substrate with improved corrosion resistance, barrier properties, etc. by reducing water and oxygen, hydrogen sulphide, and carbon dioxide permeability.

[0071] Example embodiments and methods thus being described, it will be appreciated by one skilled in the art that example embodiments may be varied and substituted through routine experimentation while still falling within the scope of the following claims. For example, although some substrates are used in examples, it is understood that any substrate are useable in example embodimentsand fall within the scope of the claims. Such variations are not to be regarded as departure from the scope of these claims.