MXPA06015041A - Antigraffiti coating from a aqueous-based polyurethane composition. - Google Patents

Abstract

The present disclosure refers to a polymer composition based on wax, water, crosslinking agents, stabilizers and rheology modifying agents for generating an effective antigraffiti coating.

Description

ANTI-GRAFFITI COATINGS FROM A COMPOSITION OF AQUEOUS BASE POLYURETHANE FIELD OF THE INVENTION The present invention relates to an aqueous base liquid composition for generating an effective anti-graffiti coating. Such a coating has the ability to resist conventional solvents present in paints.

BACKGROUND OF THE INVENTION Within the scope of the present invention, Patent JP09206667, (SK KAKEN KK), which describes the use of two layers, the first based on a waterproof elastic paint that is covered with a second layer made of polyurethane, was granted. .

Said invention differs from the present invention in that two layers are needed to act as an anti-graffiti coating. While in the present invention, the coating is made of a single layer that is generated from an aqueous polyurethane dispersion.

Another relevant document is that of the publication WO200372667, (HILLER, W: MAIER A; STADLER R; STEIDL N, OLFERTSTETTER F (Degussa), which uses a fluoromodified polyol polymer to react with a polyurethane functionalized with OH and / or with a polyamine component The fluoromodified polymer is a water-soluble material While in the present invention a material based on a polyurethane component is used alone or in combination with an acrylic component, such material may, optionally, react with an aziridine polyfunctional or with a polymeric amine that imparts a better crosslinked coating that resists the penetration of conventional oil paints used for graffiti.

Patent US 5631042 (BECKER FS; MAIER BR), describes the use of polyvinyl alcohol / silicone and / or PTFE, which differs from the present invention, since in it a different polymeric base is used.

WO200354093 A2 (WILLIAMS N), discloses the use of an acrylic-urethane hybrid polymer, which reacts with a polyurethane polymer. The compound claimed in the application of the publication WO 0200354093 is different from that proposed in the present invention, since no reaction is carried out with a polyurethane-based material.

Patent EP 1225187 (DAMS R; DA S RJ), describes a fluorochemical composition comprising an organic solvent. This composition exhibits water and oil repellency, therefore it can be used as an anti-graffit coating i. However, such an invention differs from the present in that it is a solvent-based formulation, in addition to the use of different chemical species.

The publication "Polyméres contre graffiti" by Saidi, S., Guittard, F. and Géribaldi, S, in L'Actualité Chimique, March 2001, pp. 3-14, gives an account of the strategies followed up to that moment, globally, to solve the problem of graffiti. In this publication, the difference between temporary and permanent coatings is marked. In storms it indicates the use of acrylic polymers, especially poly (methyl methacrylate) base, polymethyl acrylamides, ethyl polyacrylates and mixtures thereof with polyvinyl alcohol or a functionalized vinylidene polymer or a vinyl chloride-acetate terpolymer. vinyl-acid malefic While in permanent coatings, the use of conventional polyurethanes is mentioned, that is to say of two components, functionalized polysiloxanes, poly (fluoro ethers), or perfluoroalkylalkoxysilane. Unlike the present invention, the aforementioned publication does not refer to the use of aqueous polyurethane dispersions or their combination with aqueous acrylic dispersions or wax emulsions, as is the case of the present invention.

BRIEF DESCRIPTION OF THE INVENTION In Mexico, the anti-graffiti protection that has been conventionally used is based on two-component polyurethanes that are not necessarily water-based. If the material is used as a transparent varnish, the original color of the facade is respected, for example, but if the varnish itself is given color, a reduced variety of colors has been detected, as in the case of the "Deletum 3000" product, which is of two components that have to be mixed prior to its application and for this reason its open life is reduced, since once the components are mixed, its polymerization is irreversible.

In addition, it should be mentioned that in the market there are some solvent based coatings that interact with graphics inks, such is the case of some products of the Dupont brand. However, the liquid composition of the present invention does not require a premixing of two components and water-based, unlike competitive products. This also makes it more environmentally friendly and also towards the user because of its reduced VOC (Volatile Organic Compound). Another advantage of the present invention is that the varnish is re-paintable, which allows to modify the color of the substrate if desired.

Because the composition does not require prior mixing, there is an open or working time, long enough so that the user is not pressured to finish his application and the product is not wasted.

Another advantage of the invention is that the combination of polyurethane dispersions with polyethylene and / or polyethylene / PTFE dispersions in the prior art has not been detected.

Furthermore, the liquid composition of the present invention is sufficiently flexible, without sacrificing its chemical resistance, which can be applied on flexible substrates such as PVC used in the production of spectacular advertisements, without exhibiting fractures and without interacting with the inks of the graphics. that give rise to the imperfection of these. It has the ability to be repainted and has excellent adhesion in acrylic paints Other advantages are that it is resistant to water, once it is well dried, and is easy to clean with conventional paint solvents, that is, citrus cleaners and mineral oils, the latter known as turpentine.

Therefore, the composition of the present invention can be used in the protection of vehicle graphics, it also has an improved brightness, is easy to apply and has no interaction with the inks of the graphics used in the advertisements. Also, the composition of the present invention can be used to protect rigid substrates such as walls, facades, against graffiti, since it can be cleaned easily with citrus cleaners or with the solvent called turpentine.

The thickness of the protective film generated from the application of the liquid composition on the material to be protected, by means of a process of sprinkling or by means of the use of brushes or rollers, is selected in such a way that it allows the film of protection tolerate at least 5 cleaning cycles with the cleaning solvents referred to above.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a liquid composition that can be applied by spraying, brushing, roller or dipping, among other conventional coating methods.

Once the liquid composition has been applied and allowed to dry, a film is generated, which exhibits resistance to solvents such as turpentine, citrus-based cleaner, or alcohols such as ethanol or methanol, which are capable of cleaning the paints Traditionally they are used for graffiti. This movie can be used in the protection of rigid substrates such as facades of masonry, brick and other materials conventionally used in construction; as well as for the protection of advertisements or promotional exhibits at bus stops, subway, freight fleets, etc.

The liquid composition may comprise only an aliphatic and functionalized polyurethane dispersion, the mixture of different types of polyurethanes dispersed in water; or a mixture of said polyurethane with other polymers, especially with those having mechanical strength characteristics, and with those that provide flexibility and chemical resistance.

The liquid composition of the present invention comprises an aqueous dispersion of aliphatic polyurethane and functionalized with carboxyl groups, which can be polyester base, polyether, or have a structure with polycarbonate units, which give characteristics of chemical and mechanical resistance to the film generated after drying The content of the aqueous dispersion of aliphatic polyurethane in the liquid composition of the present invention, it is in the range of 50 to 100% by weight, preferably 60 to 90% by weight and more preferably 75 to 85% by weight, based on the total weight of the liquid composition.

Among the materials considered, to be combined with the polyurethane dispersion, is an aqueous dispersion of acrylic polymer, which confers chemical resistance to the generated film. In this case, the content of this material in the liquid composition of the present invention is preferred in the range of 10 to 80% by weight, preferably 15 to 60% by weight, and more preferably 20 to 50% by weight , based on the total weight of the liquid composition.

Another component of the liquid composition of the present invention is a wax, which is a dispersion of oxidized polyethylene. This material gives mechanical and chemical resistance to the film generated. The amount of this material in the liquid composition is in the range of 5% to 30% by weight, preferably 7 to 25% by weight, and more preferably 9 to 20% by weight, based on the total weight of the composition liquid Another component of the liquid composition of the present invention is a crosslinking agent. The crosslinking agent is a compound capable of reacting with the functional groups of the polyurethane or other components containing functional groups, generating a protective film with improved characteristics of chemical and mechanical resistance. Examples of crosslinking agents include, but are not limited to, melamines, aziridines, epoxysilanes, carbodiimides, polymeric amines such as polyethylene imines, polyurethanes or water-dispersible isocyanates. In the case of the present invention, the use of polyaziridine, methyl glycidoxypropyl diethoxy silane, polyethylene imines and isocyanate dispersible in water is preferred. The content of the crosslinking agent in the formulation of the liquid composition of the present invention is in the range of 1 to 15% by weight, preferably 1.5 to 10% by weight, and more preferably 2 to 6% by weight, with based on the solids content of the polyurethane dispersion and the solids content of any other component containing functional groups. In the isocyanate dispersible in water, the amount preferably ranges from 1 to 10% by weight, and more preferably from 2 to 6% by weight, with respect to the total formulation.

Another component of the liquid composition of the present invention is a combination of polyethylene with polytetrafluoroethylene, which facilitates the application of the liquid composition but also provides resistance to scratches and weathering, without losing the flexibility of the film that is generated. The amount of this component in the liquid composition of the present invention ranges from 0.2 to 5%, preferably from 1 to 4% and more preferably from 2 to 3% by weight with respect to the total content of the formulation.

Due to the fact that polymeric materials are generally degraded when exposed to the weather, due to the effect of ultraviolet light and / or ozone, it is advisable to add ultraviolet light stabilizers, since these additives can impart a significant reduction, or even the removal, of the yellowing of the coating protective film. Some examples of such stabilizers are: the mixture of bis- (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate, methyl- (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate, 3- (2H-benzotriazol-2-yl) -5- (1, 1- dimethylethyl) -4-hydroxybenzene propanoic acid, C7-C9-branched alkyl esters, and dimethyl sebacate. The amounts of stabilizer used in the liquid composition of the present invention range from 0.2 to 7% by weight, preferably from 0.2 to 5% by weight, and more preferably from 0.5 to 3% by weight, based on the total solids content of the liquid composition of the invention.

Other components of the liquid composition of the present invention are rheology modifying agents, known as thickeners or dispersants, and whose main function is to prevent, or minimize, the runoff of the material when it is applied, obtain films with greater thickness, or achieve a better dispersion of fillings or materials within the formulation. The amount of these additives in the liquid composition is in the range of 0.01% to 2% by weight, preferably 0.03 to 1.0% by weight, and more preferably 0.05 to 0.5% by weight, based on the total weight of the composition liquid Other components of the liquid composition of the present invention may be additives traditionally used in the coating industry, such as the case of foaming or moisturizing. The amount of these additives in the liquid composition is in the range of 0.01% to 2% by weight, preferably 0.03 to 1.0% by weight, and more preferably 0.05 to 0.5% by weight, based on the total weight of the composition liquid In the case of the protection of materials used in the construction, for example of facades or walls in general, it is preferred to obtain a matte coating, that is, with low gloss. Therefore, other components that can be part of the formulation of the liquid composition of the present invention are preferably mineral-type fillers, such as calcium carbonate or talc. The amount of said fillers in the liquid composition can be in the range of 1 to 30%, preferably 2 to 25% and more preferably 3 to 20% by weight, based on the total content of the formulation.

In accordance with the standard AST D6578-00, the anti-graffiti coating presents the typical characteristics shown in Table 1.

TABLE 1 Can not clean: Graffiti still remains or the brightness ratio is less than 0.8, or delta E of the cleaned surface compared to an unmarked area is greater than 1.0. b) number of cycles with total removal and level of cleanliness for the last cycle where the graffiti was completely removed.

Examples of the formulation of the present invention are presented below, without this being restricted to said examples: EXAMPLE 1 Aqueous dispersion of polyurethane 1: 73 to 93% (w / w) Aqueous dispersion of acrylic: 5 to 19% (w / p) Crosslinking agent: 1 to 6% Anti-foam: 0.15% (w / w) Polyethylene wax with polytetrafluoroethylene: 1 to 4% (P / P) 1 carboxylated aliphatic polyurethane base polyester Example 2 Aqueous polyurethane dispersion Aqueous polyurethane dispersion Crosslinking agent: 0.5 Anti-foam: 0.15% (w / w) Water: 2 to 5% (w / w) Polyethylene wax with polytetrafluoroethylene: 1 to 4% (P / P) 1 carboxylated aliphatic polyurethane base polyester base 2 carboxylated aliphatic polyurethane base polycarbonate Example 3 Aqueous dispersion of carboxylated aliphatic polyurethane base polyester: 56 to 90% (w / w) Aqueous acrylic dispersion: 5 to 19% (w / w) Aqueous dispersion of oxidized polyethylene: 5 to 25% (w / w) Cross-linking agent: 1 to 6% (w / w) Anti-foaming: 0.15% (w / w) Thickener: 0.01 to 0.5% (w / w) Example 4 Aqueous dispersion of polyurethane 1: 60 to 94% (w / w) Aqueous dispersion of polyurethane2: 1 to 15% (w / w) Aqueous dispersion of oxidized polyethylene: 5 to 25% (w / w) Crosslinking agent: 0.5 - 6% (w / w) Anti-foam: 0.15% (w / w) Thickener: 0.01 to 0.5% (w / w) 1 carboxylated aliphatic polyurethane base polyester 2 carboxylated aliphatic polyurethane base polycarbonate Example 5 Aqueous dispersion of polyurethane 1: 70 to 94% (w / w) Aqueous dispersion of oxidized polyethylene: 5 to 15% (w / w) Talc: 1 to 15% Cross-linking agent: 0.5 - 6% (w / w) Anti-foam: 0.15% (w / w) Thickener: 0.01 to 0.5% (w / w) Dispersant: 0.01 to 0.5% (w / w) 1 aliphatic polyurethane carboxylated base polyester It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (2)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property

1. A liquid composition characterized in that it comprises the following components: a) an aqueous dispersion of aliphatic polyurethane and functionalized with carboxyl groups, b) Aqueous dispersion of acrylic polymer, c) Aqueous dispersion of oxidized polyethylene, d) crosslinking agents, e) a combination polyethylene with polytetrafluoroethylene, f) rheology modifying agents

2. The liquid composition according to claim 1, characterized in that the aliphatic polyurethane can be polyester base, polyether, or have a structure with polycarbonate units or the mixture of aliphatic polyurethanes of different base or different physicochemical characteristics such as molecular weight, vitreous transition temperature and content of functional groups The liquid composition according to claim 1, characterized in that it contains ultraviolet light stabilizers. The liquid composition according to claim 1, characterized in that it contains additives traditionally used in the coatings industry such as anti-foaming agents and / or wetting agents. The liquid composition according to claim 1, characterized in that it contains fillers such as calcium carbonate or talc. The liquid composition according to claim 1, characterized in that the aliphatic and functionalized polyurethane content is in the range of 50 to 100% by weight, preferably 60 to 90% by weight, based on the total weight of the liquid composition. The liquid composition according to claim 1, characterized in that the amount of acrylic polymer is preferred in the range of 10 to 80% by weight, preferably 15 to 60% by weight, based on the total weight of the liquid composition. The liquid composition according to claim 1, characterized in that the dispersion of oxidized polyethylene is in the range of 5% to 30% by weight, preferably 7 to 25% by weight, and more preferably 9 to 20% by weight, based on the total weight of the liquid composition. The liquid composition according to claim 1, characterized in that the crosslinking agent includes, but is not limited to melamines, aziridines, epoxysilanes, carbodiimides, amines and / or imines and their derivatives such as polyethyleneimine, polyurethanes or isocyanates dispersible in water, preferably polyaziridine, methyl glycidoxypropyl diethoxy silane and isocyanate dispersible in water. The liquid composition according to claim 1, characterized in that the crosslinking agent is in the range of 1 to 15% by weight, preferably 1.5 to 10% by weight, and more preferably 2 to 6% by weight, based on to the solids content of the polyurethane dispersion and the solids content of any other component containing functional groups, or to the total weight of the formulation, in the case of water-dispersible isocyanates. The liquid composition according to claim 1, characterized in that the combination of polyethylene with poly (tetrafluoroethylene), is from 0.2 to 5%, preferably from 1 to 4% and more preferably from 2 to 3% by weight with respect to the total content of the formulation. The liquid composition according to claim 3, characterized in that it comprises ultraviolet light stabilizers which are the mixture of bis- (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate, methyl- (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate, 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxybenzene propanoic acid, C7 -C9-alkyl branched esters, and dimethyl sebacate. The liquid composition according to claim 3, characterized in that the ultraviolet light stabilizers are in an amount of 0.2 to 7% by weight, preferably 0.2 to 5% by weight, and more preferably 0.5 to 3% by weight, with based on the total solids content of the liquid composition of the invention. The liquid composition according to claim 1, characterized in that the rheology modifying agent is in an amount from 0.01% to 2% by weight, preferably from 0.03 to 1.0% by weight, and more preferably from 0.05 to 0.5% by weight, based on the total weight of the liquid composition. The liquid composition according to claim 5, characterized in that the filler, such as calcium carbonate or talc, is in a amount from 1% to 30% by weight, preferably from 2 to 25% by weight, and more preferably from 3 to 20% by weight, based on the total weight of the liquid composition. The liquid composition according to claim 4, characterized in that the anti-foaming agent and / or the wetting agent are in an amount of 0.02% to 2% by weight, preferably 0.04 to 1.5% by weight, and more preferably 0.05 to 0.05% by weight. 1.2% by weight, based on the total weight of the liquid composition. The use of the liquid composition according to claim 1, to effectively protect flexible substrates, such as polyvinyl chloride, against graffiti since graffiti can be easily removed with solvents such as turpentine or those made with citrus. The use of the liquid composition according to claim 1, to effectively protect flexible substrates used for the generation of spectacular advertisements or propaganda vehicles, such as poly (vinyl chloride), against graffiti, without affecting the inks used in the graphic. The use of the liquid composition according to claim 1, to effectively protect rigid substrates such as masonry facades, brick or some other material conventionally used for this purpose, are coated with or without acrylic paint. The liquid composition according to claim 1, characterized in that once it is dry and has generated the protection film against graffiti, it is capable of being coated or painted, with paints conventionally used for this purpose, such as, for example, paints acrylics; without exhibiting problems of adhesion or anchoring of said paints.