Technical Field

[0001] The present disclosure relates in general to a sealant and, in particular, to a composition of the sealant for preventing corrosion.

Background

[0002] Typically, metal substrates or substrates with metal coatings may be prone to corrosion due to exposure to atmosphere. In an example, mirrors supplied in standard sizes may be cut into different sizes and shapes based on the end user requirement. In some cases, the mirrors without any frames around the edges may also be used. In other cases, the mirrors may be installed on plywood or other substrates of choice. The edges of the mirror may be exposed to atmospheric conditions, e.g., moisture that may lead to corrosion of the edges of the mirror.

[0003] Moreover, cutting of glass substrates may cause the coating layer to chip- off thereby exposing silver or other corresponding metals coated on the glass substrate to moisture and other environmental conditions. As such, a chipped off portion of the coated surface that is adjacent to the edge may also be prone to corrosion along with the edge of the mirror. During the course of time, black spots may develop around the edges of the mirrors due to atmospheric corrosion. As such, the edges and the portion of the coated surface adjacent to these edges may need to be protected from corrosion. Various other substrates may also be corroded which may reduce the life of a substrate.

[0004] For reference, U.S patent 5,389,301 is related to a lead-free anticorrosive formulation applied in layer form for the protection of metal films applied to transparent supports. The formulation comprises a binder consisting of at least one resin selected from the group consisting of isomerized rubber, urethane oil, alkyd, modified alkyd, acrylic, phenol and epoxy resins; at least one melamine resin; a corrosion-inhibiting pigment consisting cyanoacetylurea; fillers; metal oxides; at least one solvent; and adhesion promoting additives. Said formulation being particularly useful with mirrors, reflective surfaces and the like. [0005] The above cited reference discloses a metal based composition that is applied to the entire surface of the mirror and hence does not have any targeted action over the edges and is less effective in preventing corrosion over the edges. Since the edges of the mirrors are more prone to corrosion it is necessary to protect the edges. Therefore, a need for a cost-effective and easy-to-use composition to prevent corrosion continues to exist.

Summary of the Disclosure

[0006] In one aspect of the present disclosure, a composition for preventing corrosion of a substrate, the composition a mixture, a random copolymer, a block copolymer, a homopolymer, a ter-polymer, or a blend of A, B and C, wherein

and wherein Rj = H or CH ₃ ; R ₂ = C1-C4; R ₃ = C1-C3; and R4 = C1-C2.

[0007] In another aspect of the present disclosure, a composition for preventing corrosion of a substrate is provided. The composition consists essentially of a mixture, a random copolymer, a block copolymer, a homopolymer, a ter-polymer, or a blend of 15% to 35% of a C1-C6 alkyl acrylate; 15% to 35% of a C1-C3 alkyl methacrylate; 0.1% to 10% of a C1-C4 alkyl acrylate; 0.1% to 2% of an adhesion promoting agent; and a medium.

[0008] In yet another aspect of the present disclosure, a composition for preventing corrosion of a substrate is provided. The composition includes a butyl acrylate having a weight percentage in a range of 15 to 35. The composition also includes a methyl methacrylate having a weight percentage in a range of 15 to 35. The composition further includes an ethyl acrylate having a weight percentage in a range of 0.1 to 10.

[0009] In another aspect of the present disclosure, a glass substrate is provided. The glass substrate includes a coated surface and a composition for preventing corrosion. The corrosion preventing composition is disposed at least around an edge of the coated surface. The composition includes a butyl acrylate having a weight percentage in a range of 15 to 35. The composition also includes a methyl methacrylate having a weight percentage in a range of 15 to 35. The composition further includes an ethyl acrylate having a weight percentage in a range of 0.1 to 10.

[0010] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

[0011] Embodiments are illustrated by way of example and are not limited in the accompanying figures.

[0012] FIG. 1 illustrates a microscopic view of an exemplary substrate.

[0013] FIG. 2 illustrates a microscopic view of the surface of a substrate with a sealant applied thereon, according to an embodiment of the present disclosure.

[0014] Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention. Detailed Description

[0015] Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Embodiments disclosed herein are related to a composition of a sealant for preventing corrosion on a substrate. In one embodiment, the substrate may be a glass material. The glass material may include a coated surface. In one example, the coated surface may include Ag. In other examples, the coated surface may include one or more of Ag, Ni, Cu, Al, Ti and the like. Accordingly, a suitable applicator may be used for applying the sealant on the substrate for preventing corrosion. One such applicator is disclosed in an Indian patent application number 4954/CHE/2015 to Saint-Gobain Glass France and the same is incorporated herein as reference. In one aspect, the sealant may be applied at least partly on each of the coated surface and the surfaces that are adjacent to the coated surface.

[0016] In other embodiments, the substrate may be a solar panel, a magnetron coater product, a fiber-reinforcement, a plywood, a metal, a glass and the like. However, a person of ordinary skill will recognize that the sealant may be used on any other substrates that are prone to corrosion.

[0017] In an embodiment, the composition of the sealant includes acrylates A, B and C, wherein

Ft

Ft

[0018] In one embodiment, Rj may represent H. In another embodiment, Rj may represent CH ₃ . For example, Rj of a compound A may be H while Rj of a compounds B and C may be CH ₃ . In an embodiment, R2 may represent any of CI to C4 alkyl groups. Further, R2 may represent any of CI to C3 alkyl groups. Further, R3 may represent any of CI to C2 alkyl groups.

[0019] The composition may include at least one of a mixture, a random copolymer, a block copolymer, a homopolymer, a ter-polymer, and a blend of the compounds. In an embodiment, the composition may include a blend of a copolymer formed from A, B or a co-polymer formed from B, C. In another embodiment, the composition may include a blend of A, B and C. In yet another embodiment, the composition may include a blend or a mixture of a homopolymers of each of A, B and C.

[0020] In another embodiment, the compound A may be a C1-C6 alkyl acrylate, the compound B may be a C1-C3 alkyl methacrylate and the compound C may be a C1-C4 alkyl acrylate.

[0021] In an embodiment, a weight percentage of the compound A may be in a range of 15% to 35%. In another embodiment, the weight percentage of the compound A may be in a range of 10% to 30%. In an embodiment, a weight percentage of the compound B may be in a range of 15% to 35%. In another embodiment, the weight percentage of the compound B may be in a range of 10% to 30 %. In an embodiment, a weight percentage of the compound C may be in a range of 0.1% to 10%. In another embodiment, the weight percentage of the compound C may be in a range of 0.2% to 8%.

[0022] In an example, the composition may include a butyl acrylate, a methyl methacrylate and an ethyl acrylate. The weight percentage of butyl acrylate may be in a range of 15% to 13%. The weight percentage of methyl methacrylate may be in a range of 15% to 13%. Further, the weight percentage of methyl methacrylate may be in a range of 0.1% to 10%.

[0023] The composition may further include a medium. In one example, the medium may be water. In other examples, the medium may include at least one of water, alcohol, ether, ester or hydrocarbon based compounds. In an embodiment, a weight percentage of the medium may be in the range of about 40% to 60%.

[0024] In an embodiment, the composition may also include an adhesion promoting agent. The adhesion promoting agent may have a weight percentage in a range of about 0.1% to 2% of the composition. In an embodiment, the adhesion promoting agent may be a silane based adhesion promoter e.g., Epoxy silane (3- Glycidyloxypropyl) trimethoxysilane. Other types of suitable adhesion promoting agents may also be contemplated for use in the sealant.

[0025] The sealant with the above described compositions may be hydrophobic in nature thereby preventing moisture to pass therethrough. Moreover, the sealant may have a contact angle of water with respect to air in a range of 75 to 95 degrees.

[0026] In an experiment, edges of a mirror are coated with the sealant. The hydrophobic nature of the sealant may be measured by measuring the contact angle on the edges of the mirror through sessile drop method. Table 1 gives the details of contact angles for different weight percentages of the components of the sealant composition.

Table 1 : Contact angle for varied weight percentages of components of sealant composition

[0027] The substrate has a contact angle of 46 without the application of the sealant. As such, the substrate without the sealant may come in contact with moisture from the atmosphere and may be prone to corrosion. However, a transparent film resulting from the sealant composition is found to have a contact angle of water with respect to air greater than 75 degrees thereby exhibiting hydrophobicity. The hydrophobicity may enable the sealant to prevent water seepage. As such, corrosion of the substrate that may occur with exposure to moisture may be prevented with the use of the sealant. Moreover, by adding a suitable adhesion promoting agent, better contact angles for the transparent film may be obtained. Further, with the use of the sealant, according to various embodiments of the present disclosure, the corrosion on the substrate may be delayed thereby improving a life of the corresponding substrate.

[0028] The sealant of the present disclosure forms a solid transparent film at room temperature. As such, upon application of the sealant on the substrate, aesthetic features of the substrate may not be affected.

[0029] Example 1

[0030] Sealant Preparation

[0031] The sealant was applied on a substrate, e.g., mirror and the mirror was subjected to various tests to evaluate the performance of the sealant. Table 2 shows the composition of the sealant.

Table 2: Composition of Sealant

[0032] Accelerated Aging Field Test

[0033] To gauge corrosion resistance of the sealant, an on-field accelerated test was performed on a mirror with and without sealant for 4 weeks. Mirrors of a predetermined size (1*1 ft) were mounted on marine plywood in an open area with good ventilation. Freshly prepared sodium sulphide (Na2S of 0.2M) solution was sprayed on all the edges of mirrors to accelerate corrosion. Nearly 3-4ml of the solution was sprayed on the edges of the mounted mirrors 3 times a day for a period of 4 weeks.

[0034] Continuous monitoring of the mirrors was made to check the effect of the chemicals being sprayed. Corrosion levels were measured using optical microscopy, where the highest penetration distance of corrosion from the edges was measured. FIG. 1 shows an image of the mirror without the sealant. FIG. 2 shows an image of the mirror with the composition applied. As can be seen from the images in FIG. 1 & FIG. 2, there was a difference between the mirror with the sealant and the mirror without the sealant.

[0035] In an embodiment, a maximum penetration level for each of the mirrors was measured as an indication of corrosion level. The corrosion levels in both the images were measured using optical microscopy. For the mirror without the composition, the maximum penetration level was found to be 2452 micrometers. However, for the sealant with the composition applied thereon, the maximum penetration level was found to be only 761 micrometers. The substrate coated with the sealant composition exhibited a meagre corrosion percentage of approximately around 30 % when compared with a substrate without the sealant composition (that exhibited a corrosion percentage of about 100 %).

[0036] Taber Test

[0037] To further gauge the performance of the sealants, Taber test was performed on the substrate to evaluate the durability of the sealant on the substrate. In an example, the sealant was coated on the substrate upto a thickness of 20 microns. The coating was allowed to dry for about 2 hours at room temperature. The weight of the coated substrate was measured accurately upto 3 decimals. Further, using a Taber Abraser, the substrate was subjected to a number of abrasion cycles. Thereafter, the weight of the substrate may be measured. Further, it was determined that there is no substantial weight loss between the substrates before and the after subjecting the substrate upto 200 cycles. With such a test, it was found that the sealant was considerably resistant to abrasion and capable of withstanding upto 200 abrasion cycles for the mentioned thickness. Moreover, by adding the adhesion promoting agent, a better adhesion resistance was be obtained.

[0038] Adhesion Test [0039] A peel off test was performed on the substrate coated with the sealant to evaluate the durability. A tape was attached on the sealant uniformly and then pulled off. The substrate was then checked for any sealant removal and also the tape was checked for traces of the sealant stuck on the tape. However, the sealant of the present disclosure was found to withstand the peel off test without any substantial removal of the sealant from the substrate along with the tape.

[0040] The sealant of the present disclosure can use water as a medium instead of organic solvents thereby reducing the overall cost of the composition. Further, the sealant may dry off and form a solid film on the substrate at room temperature. As such, no extra curing or increased temperature may be needed with use of the sealant of the present disclosure.

[0041] Results

[0042] The results of the test carried out are tabulated in Table 3 as shown below.

Table 3: Test results

[0043] In an embodiment, as described above, the sealant may be used for preventing corrosion of mirrors. Typically, as the mirror is cut into required shapes, the edges adjacent to the coated surface of the mirror and, a portion of the coated surface around the edge may be prone to corrosion. As such, the sealant may be applied on surfaces around the edges that are adjacent to the coated surface of the mirror thereby delaying the process of corrosion of the mirror. [0044] Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.

[0045] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

[0046] The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Certain features, that are for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in a sub combination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

[0047] The description in combination with the figures is provided to assist in understanding the teachings disclosed herein, is provided to assist in describing the teachings, and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

[0048] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0049] Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

[0051] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.