WO2012156172A1

WO2012156172A1 - Ultrahydrophobic coating composition

Info

Publication number: WO2012156172A1
Application number: PCT/EP2012/057241
Authority: WO
Inventors: Anton Harjanto; Chunbo Ran; Xiaoliang Wang; Xuemei ZHONG
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Unilever Limited
Priority date: 2011-05-16
Filing date: 2012-04-20
Publication date: 2012-11-22
Also published as: BR112013027965A2

Abstract

Ultrahydrophobic coating compositions comprising an overprint varnish and particles are described. The coating composition may be applied to substrates, like consumer product packaging, to prevent ice crystal formation thereon and to make the substrate at least ultrahydrophobic.

Description

ULTRAHYDROPHOBIC COATING COMPOSITION

FIELD OF THE INVENTION The present invention is directed to a coating composition useful as an overprint varnish as well as coated substrates coated with the same. The coating composition is versatile and suitable to coat a variety of substrates, especially the interior and/or exterior of consumer product packages. The coating composition of this invention comprises particles that surprisingly render the composition at least ultrahydrophobic upon drying while not negatively impacting characteristic properties generally desired when using overprint varnishes.

BACKGROUND OF THE INVENTION Varnishes are typically useful as coatings on wood, plastic and metal-based products. They have also been used to provide protection to decorative prints. In fact, varnishes may be applied to base sheets of material that later are used to make an article of choice. While overprint varnishes do exist, when applied to substrates and exposed to water and/or climate changes, the varnish-coated substrates can "fog". In the case of packaging, for example, fogging may occur on the inside and/or outside of the package making visibility of the product contained therein poor. In the case of frozen food packaging, water and temperature changes can result in ice crystal formation on the interior and exterior of the package. If ice crystals form inside, the visibility and quality of the product contained therein is often compromised. If ice crystals form on the outside, product appears unattractive to the consumer and typically is not selected for purchase leading to spoilage and a waste of food. A need exists for an ideal coating composition that can protect substrates yet at the same time render substrates at least ultrahydrophobic so that they may remain free of, for example, fog and water build-up as well as ice crystal formation.

This invention, therefore, is directed to a coating composition useful as a varnish. The coating composition comprises particles that surprisingly render the

composition at least ultrahydrophobic upon drying or curing while not negatively impacting characteristic properties generally desired when using overprint varnishes.

Efforts have been disclosed for making varnishes. In U.S. Patent No. 7,608,312 B1 , printed anti-fog films with a reactive ink system are described. Other efforts have been disclosed for making coating compositions. In U.S.

Patent Nos. 6,746,736 and 6,706,389, described are oil and grease resistant coating compositions and fog-resistant packaging films, respectively.

Even other efforts have been disclosed for making coating compositions. In U.S. Patent Application No. 2005/0238898 A1 and U.S. Patent No. 3,355,313, overprint varnishes and methods of rendering thermoplastic materials anti-fogging are disclosed, respectively.

None of the above documents describe a coating composition suitable for use as an overprint varnish wherein the composition has particles that render the composition at least ultrahydrophobic upon curing while not negatively impacting the characteristic overprint varnish properties of the same. SUMMARY OF THE INVENTION

In a first aspect, the present invention is directed to a coating composition, the coating composition comprising:

a) particles, a premix comprising particles and oil, and/or a premix

comprising particles and emulsion; and

b) an overprint varnish,

the coating composition being ultrahydrophobic upon curing and capable of overprinting printed subject matter wherein the particles are dispersed in the overprint varnish.

In a second aspect, the present invention is directed to a method of coating a substrate with the composition of the first aspect of this invention. In a third aspect, the present invention is directed to the coated substrate of the second aspect of this invention.

At least ultrahydrophobic, as used herein, means having a contact angle against water of at least 120° where contact angle means the angle at which a

water/vapor interface meets a solid surface, preferably the contact angle is measured at a temperature of 25 °C. Such an angle may be measured with a goniometer or a Kruss drop shape analysis system. At least ultrahydrophobic is meant to include coatings that are superhydrophobic such as those that form a contact angle against water from 140° to 158°, and preferably, from 145° to 158°. Overprint varnish means a varnish or coating suitable for overprinting on to printed subject matter wherein the same can be a solution or made with emulsifiers. The coating composition of this invention comprises an overprint varnish, as well as particles, a premix of particles and oil, and/or a premix of particles and emulsion wherein the coating composition is unexpectedly after applying and curing suitable to render a substrate at least ultrahydrophobic while simultaneously being capable of overprinting printed subject matter (i.e., being applied to printed subject matter during printing or as a second off-line process). The coating composition of this invention, therefore, may also be characterized as an overprint varnish after application and curing wherein the same is suitable to prevent ice crystal formation. Premix as used herein means a mixture of particles and oil as well as a mixture of particles and emulsion. Hydrophilic, as used herein, means preferring an aqueous phase over an oil phase at a water/oil interface.

Hydrophobic means preferring the oil phase over an aqueous phase at a water/oil interface. Particle, as used herein, means a particle (including a single

agglomerate of particles) having a diameter from 0.5 nm to 150 microns where diameter is meant to mean the largest measurable distance of a cross-section of the particle.

All ranges defined herein are meant to include all ranges subsumed therein.

Comprising, as used herein, is meant to include consisting essentially of and consisting of. The coating composition of this invention, therefore, may consist essentially of or consist of overprint varnish, and particle and/or premix.

It should be noted that in specifying any range of values, any particular upper value can be associated with any particular lower value.

The disclosure of the invention as found herein is to be considered to cover all embodiments as found in the claims as being multiply dependent upon each other irrespective of the fact that claims may be found without multiple dependency or redundancy.

Where a feature is disclosed with respect to a particular aspect of the invention (for example a composition of the invention), such disclosure is also to be considered to apply to any other aspect of the invention (for example a method of the invention) mutatis mutandis. Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use may optionally be understood as modified by the word "about".

All amounts are by weight of the final coating, unless otherwise specified.

BRIEF DESCRIPTION OF THE FIGURES

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention may be best understood by reference to the following description taken in conjunction with the accompanying figures in which:

Figure 1 A depicts a conventional paper-based package not having been subjected to the coating composition of this invention;

Figure 1 B depicts a paper-based package that has been subjected to the coating composition of this invention;

Figure 1 C depicts a paper-based package having portions that were subjected to the coating composition of this invention; and Figures 2A and 2B show photographs of packages having water droplets thereon where Figure 2B has been coated with a coating composition made consistent with this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The only limitation with respect to the type of particles that may be used in this invention is that the same are suitable for addition to an overprint varnish. The particle that may be used in this invention can be hydrophobic or hydrophilic. Illustrative yet non-limiting examples of the types of hydrophobic particle suitable for use in this invention include carbon, hydrocarbons, halocarbons, silicones, silanes, siloxanes or mixtures thereof. Illustrative yet non-limiting examples of the types of hydrophilic particles suitable for use in this invention include silica, titania, iron oxide, nickel oxide, calcium carbonate, zinc oxide, calcium phosphate, silicates, aluminum oxide, cerium oxide as well as mixtures thereof.

It is also within the scope of this invention to employ particles that are hydrophobic but comprise hydrophilic cores that are coated with a hydrophobic coat. Still further it is within the scope of this invention to use particles that are hydrophilic but comprise hydrophobic cores that are coated with a hydrophilic coat.

In a preferred embodiment, the particle used in this invention comprises at least 0.1 % by weight silicon dioxide (i.e., silica), and preferably, at least 25% by weight silicon dioxide, and most preferably, at least 50% to 100% by weight silicon dioxide, based on total weight of particle used and including all ranges subsumed therein. In a most preferred embodiment, the particle used is silica, especially pyrogenically produced silica comprising at least one of the following groups:

- O - Si (CH₃)₃ , (I)

or

O— Si— C ₈ H

(HI)

Such silicas are described, for example, in United States Patent No. 7,282,236 and made commercially available from suppliers like Evonik Degussa GmbH under the names Aerosil R812, R812S, R202, MS202 and R805. Silica of the octylsilane type and comprising the group represented by formula III is sold under the name Aerosil R805 and is sometimes preferred.

Other particles suitable for use in this invention are made commercially available from suppliers like Nyacol Nano Technologies, Inc. and Aldrich. Coated particles can, if desired, be made via known techniques that include dry particle coating methods, as well as spray coating techniques.

Typically, the particles of this invention are from 0.5 nm to 150 microns in diameter, and preferably, from 1 to 700 nm in diameter, and most preferably, from 7 to 99 nm in diameter, including all ranges subsumed therein and where diameter is, again, meant to mean the longest measurable distance of a cross-section of the particle.

When combined with overprint varnish to make the coating composition of this invention, the particles may typically make up from 0.02 to 10 percent, and preferably, from 0.05 to 7 percent, and most preferably, from 0.75 to 6 percent by weight of the total weight of the coating composition, including all ranges subsumed therein. In an often desired embodiment, from 75 to 100 percent, and preferably, from 85 to 100 percent, and most preferably, from 95 to 100 percent by weight of the particles used are smaller than 100 nm (i.e., nanoparticles and preferably from 0.5 to 85 nm, and most preferably, from 1 to 70 nm) when a transparent coating composition is desired. Larger particles may be employed to produce translucent or opaque coating compositions, often desired when it is ideal to hide or conceal product in see-through packaging and/or when abundant protection from ultraviolet light is desired.

In the case of non-aqueous compositions (i.e., compositions having less than 5% by weight total water, and preferably, from 0 to less than 2.5 percent by weight total water), the same may be light (i.e., UV or radiation cured) or heat cured wherein cured as used herein can be interchanged with dried. When the coating compositions are non-aqueous as defined herein, particles may be added directly thereto and mixed in order to yield the desired composition. In a preferred embodiment, however, particle is first mixed in oil or emulsion to form a premix and subsequently added to overprint varnish in order to generate the coating composition of this invention.

When oil is employed to make a particle comprising premix, particle typically makes up from 5 to 95 percent, and preferably, from 25 to 85 percent, and most preferably, from 40 to 80 percent by weight of the premix, including all ranges subsumed therein. Oil, therefore, can make up from 5 to 95 percent, and preferably, from 15 to 75 percent, and most preferably, from 20 to 60 percent by weight of the premix, including all ranges subsumed therein.

The oil selected is limited only to the extent that the same may be used to disperse particles in the coating composition of this invention. Illustrative yet non- limiting examples of the types of oils that may be used in this invention include petroleum by-products like mineral oil, and sunflower oil, cotton oil, soybean oil, borage oil, jojoba oil, mixtures thereof or the like.

Oils often preferred for use are represented by formula IV:

wherein each R is independently H or a Ci_-4 alkyl (preferably methyl); each R¹ is independently OR, CMS alkyl (preferably methyl) or an aryl group (preferably phenyl) where R is as previously defined; and n is an integer from 1 to 1 ,200.

In an especially preferred embodiment, such polydimethylsiloxanes or its derivatives (as represented by Formula IV) are made commercially available from suppliers like Dow Corning as DC-1401 and DC-1501 , Bluestar Silicones as Rhodersil BP 9400, and Wacker Chemie AG as AK 1000. It should be known that cross-linking agents may optionally be used in the coating compositions of this invention in order to initiate or accelerate the curing of polydimethylsiloxanes when used. Illustrative examples of such cross-linking agents that may be used include, for example, agents that comprise Si-H groups (like Syl-Off 7367 made commercially available by Dow Corning), metal salts or chelators (like dibutyltin dilaurate), organic peroxides (like t-butyl perbenzoate), mixtures thereof or the like.

When used, such cross-linking agents typically make up from 0.01 to 5 percent, and preferably, from 0.1 to 3.5 percent, and most preferably, from 0.3 to 3 percent by weight of the total weight of oil and cross-linking agent and including all ranges subsumed therein.

Other oils suitable for use include those generally classified as silicone

elastomers.

Preferred silicone elastomers are organopolysiloxanes available under the INCI names of dimethicone/vinyl dimethicone crosspolymer, dimethicone crosspolymer and Polysilicone-1 1 . Ordinarily these materials are provided as a 1 -30% crosslinked silicone elastomer dissolved or suspended in a dimethicone fluid (usually cyclomethicone). For purposes of definition "crosslinked silicone elastomer" refers to the elastomer alone rather than the total commercial compositions which also include a solvent (e.g., dimethicone) carrier. Dimethicone/vinyl dimethicone crosspolymers and dimethicone crosspolymers are available from a variety of suppliers including Dow Corning (9040, 9041 , 9045, 9506 and 9509), Shin Etsu (KSG-15, 16, 18 [dimethicone/phenyl vinyl

dimethicone crosspolymer]), and Grant Industries (Gransil™ line of materials). Lauryl dimethicone/vinyl dimethicone crosspolymers suitable for use are supplied by Shin Etsu (e.g., KSG-31 , KSG-32, KSG-41 , KSG-42, KSG-43 and KSG-44). Other suitable commercially available silicone elastomers include vinyl

dimethicone/methicone silesquioxane crosspolymers from Shin-Etsu sold as KSP- 100, KSP-101 , KSP-102, KSP-103, KSP-104, KSP-105, and hybrid silicone powders that contain a fluoroalkyl group or a phenyl group sold by Shin-Etsu as respectively KSP-200 and KSP-300.

The weight values of oils exclude any solvent such as cyclomethicone found in commercial "elastomer" silicones such as the Dow Corning products 9040 and 9045. For instance, the amount of crosslinked silicone elastomer in 9040 and 9045 is between 12 and 13% by weight.

Most preferred as the silicone elastomer (i.e., oil) is 9045 which has a D5 cyclomethicone swelled elastomer particle size (based on volume and calculated as spherical particles) which averages 38 microns, and may range from 25 to 55 micron.

Viscosity modifier, such as C_4-12 alkanes, benzene, derivatives of benzene and alkanols may be used along with the oils and/or for emulsion formation or as diluants to modify viscosity. Hexane, octane and/or toluene are often preferred for mixing with oil when forming emulsions. Alcohol, and especially isopropyl alcohol, is preferred when formulating non-aqueous compositions.

Typically, the amount of viscosity modifier used will be a function of the desired viscosity of the coating composition. Often, however, viscosity modifier makes up form 20 to 60 percent, and preferably, from 25 to 55 percent, and most preferably, from 30 to 50 percent by weight of the total weight of the coating composition, including all ranges subsumed therein. The premix is preferably oil based when the overprint varnish is non-aqueous. In a preferred embodiment, however, when emulsion is used for premix formation, the overprint varnish is aqueous and the emulsion is one which is classified as oil- in-water based. The oils which may be used to form the oil-in-water emulsion can be the same as the oils suitable for mixing with particle.

The emulsifiers suitable for use in order to form the emulsion used to make premix are limited only to the extent that the same may be combined with overprint varnish to generate the ultrahydrophobic composition of this invention.

Illustrative examples of the types of emulsifiers which may be used include glycerol monostearate, glycerol monoleate, glycerol monopalmitate, glycerol monolaurate, polyoxyethylene octylphenol ether, polyoxyethylene sorbitan monooleate, sorbitan monostearate, mixtures thereof or the like. In a preferred embodiment, the emulsifier used is polyoxyethylene octylphenol ether (e.g., OP- 10 made available by Tianjin Hero-Land S&T Development Co.), sorbitan monostearate (Span 60), polyoxyethylene sorbitan monooleate (polysorbate 80 or Tween) or a mixture thereof. Typically such oil-in-water emulsions are from 10 to 90 percent, and preferably, from 15 to 45 percent and most preferably, from 15 to 35 percent by weight water based on total weight of oil and water and including all ranges subsumed therein. Emulsifier typically makes up from 1 to 10 percent, and preferably, from 1 .5 to 8 percent, and most preferably, from 2 to 6 percent by weight of the total weight of premix comprising emulsion and particles, and including all ranges subsumed therein. As is the case when particle is added to oil to make a premix, particle typically makes up from 5 to 95 percent, and preferably, from 25 to 85 percent, and most preferably, from 40 to 80 percent by weight of the oil in the emulsion used to make the premix, including all ranges subsumed therein. When a premix is used, the same may make up from 0.5 to 55 percent, and preferably, from 1 to 30 percent, and most preferably, from 1 to 12 percent by weight of the total weight of the coating composition, including all ranges subsumed therein. Overprint varnish typically makes up from 15 to 99.98 percent, and preferably, from 25 to 85 percent, and most preferably, from 30 to 75 percent by weight of the coating composition, including all ranges subsumed therein.

In the case of oil-based compositions, including those which may be light or heat cured, particles added to the same should be hydrophobic if added directly thereto. In cases where the surface of the particles is not hydrophobic, the particles should first be added to oil including the oil in an oil-in-water emulsion before being combined with ingredients to make the compositions of this invention and regardless if an aqueous or non-aqueous composition is desired. This will ensure that the surface of the particles is coated with a hydrophobic coating such as oil and prior to use.

The overprint varnish that may have particle or premix added thereto as described in this invention is only limited to the extent that it is one suitable for use with consumer products, and preferably, one which may come into contact with food in a consumer product package (like a paper, paper-based or paperboard package).

Illustrative yet non-limiting examples of the types of overprint varnishes that may be used in this invention include those formed by reacting hydroxy-containing fatty acid ester with ethylenically unsaturated isocyanate. Others which may be used include layers comprising a polymer having mer units derived from ethylene, such as ethylene homopolymers and/or heteropolymers. Exemplary ethylene heteropolymers include those that include mer units derived from one or more of C3-C2o alpha-olefins, vinyl acetate, (meth)acrylic acid, and C1-C20 esters of

(meth)acrylic acid. As used herein, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid; and "(meth)acrylate" means an ester of (meth)acrylic acid. In an especially preferred embodiment, the aqueous based overprint varnish employed in this invention comprises resins which include alkyds, polyacrylate, polyacetate, polyolefin, polyurethane, epoxy and blends, mixtures and copolymers of the same. Resin typically makes up from 10 to 90 percent, and preferably, from 15 to 80 percent, and most preferably, from 20 to 65 percent by weight of the varnish as commercially supplied, including all ranges subsumed therein. Such aqueous overprint varnishes are commercially available from suppliers like M. Create International Co., Ltd. as W-190, Weilburger Graphics GmbH and sold under the name Senolith^® and Mouben^® Shanghai Mouben Printing Materials Co., Ltd. as MB-308 (all about 15-40% by weight acrylic-based resin in water).

Preferred non-aqueous varnishes suitable for use include those having resins similar to those described for the aqueous based varnishes. These varnishes typically comprise solvent like C_4-s alcohols, aliphatic hydrocarbons, aromatic hydrocarbons, esters, ethers, ketones, aldehydes, mixtures thereof or the like, and are made commercially available from suppliers like Dainippan Ink and

Chemicals, Inc. under the GOP^® name. It is within the scope of this invention to employ optional additives to the coating composition of this invention. While not required, such additives include defoamers, anti-settling agents, coalescing agents, catalysts, UV absorbers, dispersing agents, drying agents, plasticizers, coloring agents, fragrances, preservatives, antimicrobial agents, mixtures thereof or the like. Typically, when used, such an optional additive or additives make up from 0.1 to 15%, and preferably from 1 to 10 percent by weight of the coating composition, including all ranges subsumed therein. A more detailed description of the types of varnishes that may be used in order to generate the ultrahydrophobic coating composition of this invention may be found in U.S. Patent Nos. 4,204,010, 5,616,364, 5,623,041 , and U.S. Application Publication No. 2005/0019533 A1 . When making the at least ultrahydrophobic coating composition of the present invention, particle is added to conventional overprint varnish unless a premix is desired wherein the premix is first prepared prior to combining the same with varnish.

The contents used to prepare the at least ultrahydrophobic coating composition may be mixed under conditions of moderate shear and at atmospheric pressure and ambient temperature. The resulting ultrahydrophobic composition typically has a viscosity (prior to curing) in the range of 1 to 5000 cps, and preferably, from 10 to 1000 cps, and most preferably, from 50 to 500 cps, including all ranges subsumed therein where viscosity is taken at 25°C with a Brookfield Viscometer RVF No. 6 Spindle at 20 rpm and further where viscosity is obtained after two (2) minutes.

When applying the coating composition of this invention, the same may be applied via conventional techniques which include brushing, printing, dipping, pouring or spraying steps. In a most preferred embodiment, the composition is sprayed on or into the desired substrate after printing. Such a substrate may be, for example, wood, metal, glass, paper-based or polymeric in nature but is preferably paper or polymeric-based and a consumer product package. In another most preferred embodiment, the coating composition of the present invention is applied during printing via printing machines like those made available commercially and classified as relief, offset, gravure or screen printers.

When applied and cured, the coating composition of this invention is typically from 0.5 to 30 microns thick, and preferably, 1 to 20 microns thick, and most preferably, 2 to 10 microns thick, including all ranges subsumed therein. Curing time varies but is typically from 10 seconds to 1 .5 hours, and preferably, from 10 seconds to one (1 ) hour, including all ranges subsumed therein. Turning to the figures, Figure 1A depicts a paper-based carton with logo 10 (e.g., a carton, suitable for freezing, and with a logo, like an ice cream carton with logo) not treated with the coating composition of this invention and having ice crystals 12 frozen thereon. The ice crystals 12 are the result of ice formation on the carton 10 after the same has been subjected to moisture and freezing conditions in a freezer (not shown) wherein freezing as used herein means placed in a freezer cabinet for four (4) days at -20 degrees centigrade, the freezer having its door opened automatically one time per hour.

Figure 1 B depicts a coated paper-based carton 14 coated with coating

composition 16 of this invention (as described and made in Example 1 ) applied thereon wherein the coating composition 16 results in a coated surface 18 that is substantially free (at least 80%, preferably, at least 90% less ice crystals when compared to packaging subjected to similar conditions but free of the coating composition of this invention) of ice crystal formation (i.e., having a very visible printed pattern) for a sale cycle on the order of 1 to 2 weeks after the coated paper-based carton 14 has been subjected to freezing conditions as previously described.

Figure 1 C depicts a partially coated paper-based carton 20 having a first portion 22 free of coating composition of this invention but with ice crystals 12 thereon that abut a coated second portion (i.e., a logo portion) 24. Such ice crystals formed after the partially coated paper-based carton 20 has been subjected to moisture and freezing conditions as previously described. Second portion 24 shows a portion of the partially coated paper-based carton having coating composition 16 of this invention (also as described and made in Example 1 ) coated thereon resulting in the second portion 24 being substantially free of ice crystals 12 after being subjected to such moisture and freezing conditions. Fig. 1 C, therefore, depicts an often preferred embodiment of this invention wherein coating composition 16 may be partially and selectively applied in order to create an ice crystal containing portion and an ice crystal free portion on consumer good packaging in order to attract the interest of consumers purchasing products that often look very similar while shopping in a supermarket, especially in the frozen goods section.

The following examples are provided to facilitate an understanding of the present invention. The examples are not provided to limit the scope of the claims. Example 1

Fifty (50) grams of silica, made commercially available by Evonik Degussa GmbH as Aerosil R812 (particle size about 7 nm), were combined with fifty (50) grams of polydimethylsiloxane made commercially available by Bluestar Silicones under the Bluestar BP9400 name and one (1 ) liter of isopropyl alcohol. The resulting combination was vigorously mixed to produce a diluted hydrophobic premix wherein mixing was achieved under conditions of standard temperature and pressure. The premix was added to one (1 ) kilogram of commercially available non-aqueous overprint varnish, GOP-190, made available by Dainippan Ink and Chemicals, Inc. and thoroughly mixed.

The resulting ultrahydrophobic coating composition consistent with this invention was applied to a paper-based ice cream carton having print thereon. Application was achieved with a Roland gravure-type printer wherein the coating applied cued in about 15 minutes and was about three (3) microns thick.

Water was sprinkled onto a paper-based ice cream package having traditional overprint varnish free of particles and, therefore, inconsistent with this invention (Figure 2A). Water was also sprinkled onto a paper-based ice cream package coated with the coating composition of this invention (Figure 2B). A Kruss 100 drop shape analysis system was used to determine the contact angle of the water droplets (5 microliter in volume). Surprisingly, not only was the coating composition of this invention easily applied to packaging, the same resulted in a surface, after curing, with a contact angle against water (WCA) (Figure 2B) of about 148°.

The contact angle for the surface against water when using conventional overprint varnish was about 96° (Figure 2A).

Example 2

The coating composition of this example was made in a manner similar to the one described in Example 1 except that twenty five (25) grams of silica (Aerosil R812, particle size 7 nm) was used with twenty-five (25) grams of titanium dioxide (particle size 100 nm). The resulting coating composition, after applying and curing on the paper-based carton, resulted in a surface having a contact angle against water of 148°. Example 3

The coating compositions of this example was made in a manner similar to the one described in Example 1 except that twenty-five (25) grams of D5 silicone made available from Dow Corning was used in lieu of fifty (50) grams of polydimethylsiloxane made available by Bluestar. The resulting coating

composition, after applying and curing on the paper-based carton, resulted in a surface having a contact angle against water of 152°. Example 4

The coating composition of this example was made in a manner similar to the one described in Example 1 except that ten (10) grams of D200 silicone, made commercially available by Dow Corning, was used in lieu of the

polydimethylsiloxane made available by Bluestar. The resulting coating

composition, after applying and curing on the paper-based carton, resulted in a surface having a contact angle against water of 155°. Example 5

The coating composition of this example was made in a manner similar to the one described in Example 1 except that fifty (50) grams of silicone (SL-7588 made commercially available by Dow Corning) and two (2) grams of silane-based cross- linking agent was used. The resulting coating composition was applied to a paper-based ice cream carton. Water droplets were placed thereon and the contact angles of the same were assessed by using a Kruss analysis system. The resulting contact angle assessed was 149°. Example 6

In this example, fifty (50) grams of silica (R812S), fifty (50) grams of silicone (Bluestar BP9400), two hundred (200) grams of octane and fifteen (15) grams of OP-10 emulsifier were combined with one hundred (100) grams of water and vigorously mixed under atmospheric conditions and ambient temperature in order to produce an emulsion having particles dispersed therein. The particles dispersed within the emulsion (i.e., oil-in-water emulsion) were then combined with one (1 ) kilogram of aqueous varnish sold under the Mouben® name as MB- 308. The resulting mixture was vigorously stirred in order to produce the coating composition of the present invention. The coating composition was applied (about three (3) microns thick) to a paper-based ice cream package via a conventional printing machine. Five (5) micron water droplets were applied to the surface after the coating composition cured (about one (1 ) hour subsequent to application). Analysis with a Kruss analysis system revealed the contact angle against water for the surface was 150°.

Example 7

Ten (10) grams of silica (R812S) were combined with twenty (20) grams of silicone (Dow Corning D5), fifty (50) grams of octane and five (5) grams of OP-10 surfactant along with fifty (50) grams of water to establish the desired premix. The contents were vigorously mixed and combined with one (1 ) kilogram of the

Mouben® varnish. The contents were again vigorously mixed to produce the coating composition of the present invention. The same was applied to a paper- based ice cream package (in a manner similar to the one described in Example 6) after which water droplets (about 5 microliters) were applied thereon. The contact angle against water for the surface was assessed with a Kruss analyzer wherein the water contact angle was 140°. The results above indicate that the coating compositions of the present invention, surprisingly, may be applied in a manner identical to those used to apply traditional overprint varnish compositions while at the same time yielding surfaces that are at least ultrahydrophobic, and more surprisingly, superhydrophobic in nature.

Claims

CLAIMS:

1 . A coating composition comprising:

a) particle, a premix comprising particle and oil and/or a premix comprising particle and emulsion;

b) an overprint varnish,

the coating composition being ultrahydrophobic after curing and capable of overprinting printed subject matter wherein the particles are dispersed in the overprint varnish.

2. The coating composition according to claim 1 wherein particle is

hydrophobic or hydrophilic and the hydrophilic particle is in a premix.

3. The coating composition according to claim 2 wherein the hydrophobic particle is in a premix.

4. The coating composition according to claim 2 wherein the hydrophilic

particle is silica, titania, iron oxide, nickel oxide, calcium carbonate, zinc oxide, calcium phosphate, silicate, aluminum oxide, cerium oxide or a mixture thereof.

5. The coating composition according to claim 2 wherein the hydrophobic particle is carbon, hydrocarbon, halocarbon, silicone, silane, siloxane, a particle with a hydrophobically coated hydrophilic core or a mixture thereof and the overprint varnish comprises alkyd, polyacrylate, polyacetate, polyolefin, polyurethane, epoxy, or a blend, mixture or copolymer thereof .

6. The coating composition according to any one of the preceding claims wherein the composition has, after curing, a contact angle against water of at least 120 degrees.

The coating composition according to claim 6 wherein the coating composition has, after curing, a contact angle against water from 140 to 158 degrees.

The coating composition according to any one of the preceding claims wherein the coating composition is capable of being applied to the interior, exterior or interior and exterior of consumer product packaging.

The coating composition according to any one of the preceding claims wherein the particle comprises silica.

The coating composition according to any one of the preceding claims wherein particle makes up from 0.02 to 10 percent by weight of the coating composition.

The coating composition according to any one of the preceding claims wherein the composition, after curing, is transparent or translucent.

The coating composition according to claim 1 1 wherein the composition is transparent and 75 to 100 percent by weight of the particle used is smaller than 100 nm.

The coating composition according to any one of the preceding claims wherein the coating composition is capable of being applied over printed subject matter during a printing process or in a separate offline process.

14. The coating composition according to any one of the preceding claims wherein the oil comprises silicone and the emulsion is an oil-in-water emulsion.

15. A substrate coated with the coating composition of any one of the preceding claims.

16. The substrate according to claim 15 wherein the coating composition is heat or light cured.

17. The substrate according to one of claims 15 or 16 wherein the substrate comprises paper.

18. The substrate according to any one of claims 15 to 17 wherein the

substrate is consumer goods package where the entire package is coated or a portion of the package is coated.

The substrate according to any one of claims 16 to 18 wherein cured coating composition on the substrate results in an ultrahydrophobic surface.

20. A method for coating a substrate comprising the step of applying to the substrate the coating composition of any one of claims 1 to 14 and the composition is heat or light cured.