BACKGROUND OF THE INVENTION

{011 The present invention relates generally to primary packaging for detergent products and the like, and in particular to packaging substrates for containing colored detergent compositions especially in bar form.

[02] Aesthetics of consumer products such as bar soaps have significant impact on tiie consumers' perception of the products, which will in turn determine the acceptability of the products by the consumers. Soap bars traditionally are packaged in paperboard cartons, paper composites and paper composites with a paperboard stiffener. However, paper packaging requires the use of mold inhibiting chemicals or other antimicrobial agents since paper and paperboard provide a good medium for mold growth and other microbiological activity. Mold growth, in particular, can progress to the point at which it discolors the packaging material, possible contaminating the soap wrapped therein and in any event rendering the product unattractive and unfit for sale. Another common problem with bar soaps is from dye "bleeding ^* which results from coloring dye migration from the soap composition into the surrounding packaging and leaves visible stains on the paper which negatively impacts the consumer's perception of the soap product.

SUMMARY OF THE INVENTION

{03] The present invention is directed to packaging substrates for bar soaps or other solid detergent products which exhibit antimicrobial, antibacterial, antiviral, or antifungal activity, and are stain resistant Towards this end, the packaging laminates of the present invention include a clay-coated or clay-free ceilulosic material having first and second surfaces, a biocidal coating applied to the first surface of the cellulosic material; and a stain-resistant coating comprising a styrene-olefin copolymer applied to the biocidal coating.

[04] In some preferred embodiments, the cellulosic material is a paper or a cellulose fiber-containing substrate which is wrapped around a bar soap composition. Generally paper is composed of a single layer and has an area weight of less than 200 g/m ² (sometimes referred to as "grammage"), preferably less than 150 g/m ² . more preferably, less than 100 g/m ² , and most preferably, less than 50 g/m ² . Typically, most papers have thicknesses of between 2.54 and 254 pm (0.1 and 10 mil), while paperboard is generally thicker than paper has thicknesses of at least 305 (12 mil). Suitable papers for use in the present invention include, but are not limited to Kraft paper, medical grade paper, bleached paper, vegetable parchment, water, grease and oil-resistant paper, waxed paper, specialty-treated paper, wet-strength paper, absorbent paper, tissue paper and coated paper. (See Brody, et al, "Paper" and "Paperboard", The Wiley Encyclopedia of Packaging Technology, Second Edition, 1997, pp. 714-723 (John Wiley & Sons, Inc., New York, New York), which is incorporated in its entirety in this application by this reference.). Cellulose fiber-containing substrates may include non-woven cellulosic and synthetic fibers.

[05] In some preferred embodiments, the cellulosic material is a paperboard or boxboard which is folded into a carton or box configuration to contain a bar soap composition. In contrast to paper, paperboard, cartonboard and boxboard usually consist of two or three layers and have an area weight of 200 g/m ² or more, in some such preferred embodiments, the paperboard, cartonboard or boxboard has a grammage of between 200 g/m ² and 400g/m ² In other preferred embodiments, the paperboard or boxboard has bending stiffnesses of between 5 milliNewton/meter and 50 milliNewton/meter. Suitable paperboard, cartonboard or boxboard for use in the present invention include, but are not limited to those sold by Metsa Board Corporation (MetsS, Finland) and Grupo Suzano (Sao Paulo, Brazil).

|06] An important aspect of the present invention is that the packaging substrates include a biocidal coating applied to at least one surface of the cellu!osic material. In some preferred embodiments, the biocidal coating comprises a bactericide, a fungicide, a pesticide, a moldicide, a milicide or a viructde. In other preferred embodiments, the biocidal coating is a fungicide. Suitable fungicides for use in tine present invention include, but are not limited to, 1- ((diiodomethyl)sulfbnyl)-4Hfnethylbenzene (commonly referred to a p-toyl diiodomethyl sulfone), 2,4,5,6-tetrachloroisophthaionitrile (commonly referred to as ch!orothalonil) and mixtures of 1-((dtiodomethyl)sutfonyf)-4-methylbenzene and 2,4,5,6-tetrachloroisophthalonitrile. Such fungicides may be blended with water-based or solvent-based binders for ease of printing onto the cellufosic material. One such mixture is a blend of a water-based acrylic resin, 1- ((diiodomethy1)sulfonyi)-4-methy1benzene and 2,4,5,6-tetrachloroisophthalonitrite which is commercially available from intace S.A. (Paris, France) under the trade name INTACE B-6773. Another preferred fungicide comprises methyl N-(1H- benzimidazol-2-yi)carbamate (commonly referred to as carbendazim) which is also commercially available from Intace S.A. (Paris, France) under the trade name INTACE B-350.

[07] In some preferred embodiments, the paper, paperboard, cartonboard and boxboard may include a clay coating on one or both of its two surfaces. In some embodiments, the biocidal coating would be applied directly onto to the clay coating or directly onto a clay-free surface of the celluiosic material.

[08] Another important aspect of the present invention is that the packaging substrates include a stain-resistant coating applied over the biocidal coating applied to at least one surface of the celluiosic material. Surprisingly, it was discovered that a coatings of styrene-olefin copolymer acts as a chemical barrier against the migration of colored dyes from the soap composition to the packaging material. In some preferred embodiments, the styrene-olefin copolymer includes between 45 wt.% and 50 wt.% styrene moiety and between 50 wt.% and 55 wt.% olefin moiety. In such embodiments, the styrene-olefin copolymer may further include about 1 wt.% carboxylic acid moiety. An example of one such styrene- olefin copolymer having about 1 wt.% carboxylic acid moiety is VINNACOAT ^® LL8100 sold by Wacker Chemie AG (Munchen, Germany). This material may be easily dissolved in a hydrocarbon solvent mixture to facilitate its printing onto the packaging substrates of the present invention.

[091 "Bar soaps" as used herein refers to solid or semi-solid articles tor washing, battling, and cleaning that contain either soap surfactants, synthetic surfactants, or mixtures thereof (i.e., semi-synthetics) as described hereinafter. A bar soap as used herein is not limited to a bar shape but can have any regular or irregular shape, including but not limited to: cubic, rectangular, spherical, oval, cylindrical, pyramidal and the like. The bar soaps of tie present invention are preferably, but not necessarily, characterized by a volume ranging from 1 cm ³ to 1,000 cm ³ , more preferably from 10 cm ³ to 500 cm ³ , and most preferably from 50 cm ³ to 200 cm ³ , and a weight ranging from 0.5 g to 5 Kg, more preferably from 1 g to 1 Kg, and most preferably from 10 g to 500 g.

BRIEF DESCRIPTION OF THE DRAWINGS

[10] Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

FIG. 1 illustrates a schematic of one embodiment of a packaging substrate according to the present invention.

|12] FIG. 2 illustrates a schematic view of another embodiment of a packaging substrate according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[13] The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout

[14] One preferred embodiment of a packaging substrate 10 of the present invention is illustrated in FIG. 1. Generally, substrate 10 includes at least celluiosic material 101 having a first surface 101a and a second surface 101b. In this particular embodiment, celluiosic material 101 is a cartonboard having a grammage of 250g/m ² , a bending stiffness of 9.1 milliNewton/meter in the transverse direction, a bending stiffness of 16.9 milliNewton/meter in the machine direction, and a thickness of 0.425 mm. An example of such a material which is commercially available is sold under the trade name AVANTA PRIMA by Metsa Board. To the first surface 101a of celluiosic material 101 there is a biocidal coating 102 applied by the use of rotogravure printing methods, in this particular embodiment, the biocidal coating 102 was a mixture of 25 wt.% water-based acrylic resin and 10 wt.% of a fungicide (INTACE B-6673) in water. After the water was removed by drying, the amount of coating remaining on the celluiosic material 101 corresponded to between 3 g/m ² to 5 g/m ² dry coating weight. It is contemplated that the total amount of fungicide in the acrylic resin/water mixture can vary between 5 wt.% to 20 wt.%. A strain-resistant coating 103 was applied by rotogravure printing methods to the biocidal coating 102. in this particular embodiment, strain-resistant coating 103 was a mixture of 26 wt.% VINNACOAT LL8100 and 74 wt.% a solvent, methyl ethyl ketone. The excess solvent was removed by drying leaving a dry coating weight of between 3 g/m ² to 4 g/m ² of stain-resistant coating. It is aiso contemplated that biocidal coating 102 and strain-resistant coating 103 may each be applied using flexographic printing techniques and equipment. Flexographic and rotogravure printing technologies are well known in the arts.

[15] Another preferred embodiment of the present invention is shown in FIG. 2. In this particular embodiment, packaging substrate 20 is illustrated having a second biocidal coating 102 applied to the second surface 101b of the cei!uiosic material 101. In some preferred embodiments, the cellulosic material 101 may include a clay coating (not shown) which would be present between the cellulosic material and the biocidal coating. Clay coatings are known in the art which may be present on commercially available cellulosic materials such as the AVANTA PRIMA materials sold by Metsa Board. In this particular embodiment, the biocidal coating 102 was a fungicide having an identical composition as that used in packaging substrate 10 described above. It is also contemplated that printed indicia (not shown) may be applied directly to the second surface 101b of cellulosic material prior to coating the biocidal coating to same. Over tilts second biocidal coating 102 was applied an over-varnish 104. Any over-varnish known in the art may be used. In some preferred embodiments, the over-varnish 104 has resistance to abrasion and moisture resistance. In such embodiments, the over-varnish comprises a phenolic resin and paraffin wax. An example of a suitable commercially available over-varnish is BARRIER LACQUER 10VC04 BR sold by Sun Chemical de Brazil, Ltd. (Sao Paulo, Brazil). Over-vanish may be mixed with any suitable solvent to dilute its viscosity to facilitate its printing onto biocidal coating 102. in this particular embodiment, over-varnish 104 was applied in such a manner to a coating weight of 2 g/m ² to 2.5 g/m ² .

WORKING EXAMPLES

[10] In the following Examples 1-9 there is described various embodiments of a packaging substrate having a structure similar to that described above for substrate 20 as illustrated in FIG. 2. In all these examples, the surface 101b of the cellulosic material is clay coated and the opposing surface 101a is bleached and does not have a clay coating. Surface 101b of cellulosic material was printed with graphics and coating with a biocidai coating 102 using roto-gravure printing methods and the excess solvent was removed by drying in a drying oven. Surface 101a of the cellulosic material 101 was also coated with a biocidai coating 102 by roto-gravure printing methods. Next, the excess solvent was removed by drying in a drying oven. After the biocidai coating was dried, a stain- resistant coating 103 was applied directly over the biocidai coating 102 on surface 101a of the cellulosic material. An over-varnish 104 was then applied directly over the biocidai coating 102 on surface 101b of the cellulosic material.

Example 1

Example 1 is one preferred embodiment of packaging substrate 20 of the present invention as illustrated in FIG. 2 having a structure and layer compositions as described below. Reported below is a top-down description of layer compositions in the structure. For this example, a smoothing bar was used after the biocidai coatings were applied to remove any imperfections, but no smoothing bar was used after application of the stain-resistant coating.

Layer 104: 100 wL-% of an over-varnish-Barrier Lacquer 10VC04 BR (Sun

Chemical do Brazil, Guarulhos, Brazil)

Layer 102: 100 wt.~% of a biocidai coating-lmacryi Imper 20 (Imagraf Industrie de Tintas Ltd., Mairinque, Brazil)

Layer 101: 100 wt-% of a cellulosic material-Super 6 Plus ^® paper (240 grammage) (Grupo Suzano, Sao Paulo, Brazil}

Layer 102: 100 wt.-% of a biocidai coating-lmacryi imper 20 (Imagraf Industrie de Tintas Ltd., Mairinque, Brazil) Layer 103: 100 wt-% of a stain resistant coating- V!NNACOAT ^® 1X8100

(Munchen, Germany) It should be noted that this material is a polymer composition of between 45-50 wt.-% polystyrene, between 50-55 wt-% polyolefin and about 1 wt-% carboxylic acid.

Example 2

[18] Example 2 is another preferred embodiment of packaging substrate 20 of the present invention as illustrated in FIG. 2. Example 2 had the same structure and layer compositions as Example 1, except for the cellulosic material was AVANTA PRIMA (250 grammage) by Metsa ^" Board. For mis example, a smoothing bar was used after the biocidal coatings were applied to remove any imperfections in the coating, but no smoothing bar was used after application of the stain-resistant coating.

Example 3

[19] Example 3 is one comparative embodiment of packaging substrate 20 as illustrated in FIG. 2 having a structure and layer compositions as described below. Reported below is a top-down description of layer compositions in the structure.

Layer 104: 100 wt-% of an over-varnish-Barrier Lacquer 10VC04 BR (Sun

Chemical do Brazil, Guarulhos, Brazil)

Layer 102: 100 wt.-% of a biocidal coating-lmacryi tmper 20 (Imagraf Industrie de Tintas Ltd., Mairinque, Brazil)

Layer 101 : 100 wt.-% of a cellulosic material-AVANTA PRIMA (250 grammage) paper (240 grammage) Metsa Board Corporation (MetsS, Finland)

Layer 102: 100 wt-% of a biocidal coating-lmacryi Imper 20 (Imagraf IndCistria de Tintas Ltd., Mairinque, Brazil) Layer 103: 100 wt.~% of a stain resistant coating- it should be noted that this material is an isocyanate polymer.

Example 4

[20] Example 4 is another comparative embodiment of packaging substrate 20 as illustrated in FIG. 2. Example 4 had the same structure and layer compositions as Example 3, except for the ceiiulosic material was Super 6 Plus ^® paper (240 grammage) Grupo Suzano (Sao Paulo, Brazil)

Example 5

[21} Example 5 is one comparative embodiment of packaging substrate 20 as illustrated in FIG. 2 having a structure and layer compositions as described below. Reported below is a top-down description of layer compositions in the structure. For this example, a smoothing bar was used after the biocidal coatings were applied to remove any imperfections in the coating, but no smoothing bar was used after application of the stain-resistant coating.

Layer 104: 100 wt-% of an over-varnish-Barrier Lacquer 10VCO4 BR (Sun

Chemical do Brazil, Guarulhos, Brazil)

Layer 102: 100 wt.-% of a biocidal coating-lmacryi Imper 20 (Imagraf Industria de Tintas Ltd., Mairinque, Brazil)

Layer 101: 100 wt-% of a ceiiulosic material- Super 6 Plus* paper (240 grammage) (Grupo Suzano, Sao Pauio, Brazil)

Layer 102: 100 wt.-% of a biocidal coating-lmacryl imper 20 (Imagraf Industria de Tintas Ltd., Mairinque, Brazil)

Layer 103: 100 wt-% of a stain resistant coating- IMACOB-09 (Imagraf

Industria de Tintas Ltd., Mairinque, Brazil) It should be noted that this material is a highly hydrophobic acrylic varnish. [22] Example 6 is another comparative embodiment of packaging substrate 20 as illustrated in FIG. 2. Example 6 had the same structure and layer compositions as Example 5, except for a smoothing bar was used after the biocidai and stain- resistant coatings were applied to remove any imperfections.

Example 7

|23] Example 7 is another comparative embodiment of packaging substrate 20 as illustrated in FIG. 2. Example 7 had the same structure and layer compositions as Example 6, except for the cellulosic material was AVANTA PRIMA (250 grammage) paper (240 grammage) Metsd Board Corporation (Metsa, Finland). For this example, a smoothing bar was used after the biocidai and stain-resistant coatings were applied to remove any imperfections.

Example 8

[24] Example 8 is another comparative embodiment of packaging substrate 20 as illustrated in FIG. 2. Example 8 had the same structure and layer compositions as Example 7, except for the stain-resistant coating was DYNAPOL ^® L206 Degussa AG (Mart, Germany). It should be noted that DYNAPOL ^® L206 is a saturated high molecular linear copolyester. For this example, a smoothing bar was used after applying the biocidai coating, but not after the application of the stain-resistant coating.

Example 9

[25] Example 9 is another comparative embodiment of packaging substrate 20 as illustrated in FIG. 2. Example 8 had the same structure and layer compositions as Example 8, except for the stain-resistant coating was VINNOL ^® H 30/48 M- Wacker Chemie AG (Munchen, Germany). It should be noted that VINNOL* H 30748 M is a carboxylate-containing terpolymer of approximately 70 wt.-% vinyl chloride, 29 wt.-% vinyl acetate and 1 wt.-% dicarboxyiic acid. For this example, a smoothing bar was used after applying the biocldal coating, but not after the application of the stain-resistant coating.

The above packaging substrates Examples 1-9 were tested for stain resistance by placing a synthetically colored soap bar (DOVE* from Unilever) into a package formed from the substrates and kept undisturbed for twelve weeks under different temperatures and atmospheric moisture. After such time and temperature/moisture conditions, the packages were opened and visually inspected. The stain-resistance was rated 1 through 4 with 1 = stainless; 2 = light stain; 3 = medium stain; and 4 = strong stain. The results of the testing are reported below in TABLE 1.

[27] As can be seen from the above test results, optimal stain-resistance, particularly at elevated temperatures and humidity, is achieved by the use of a stain-resistant coating composed of a styrene-olefin copolymer, preferably, a styrene-olefin copolymer comprising between 45 wt.% and 50 wt% styrene moiety, more preferably, a styrene-olefin copolymer comprising between 45 wt.% and 50 wt.% styrene moiety and between 50 wt.% and 55 wt.% olefin moiety, and most preferably, a styrene-olefin copolymer comprising between 45 wt.% and 50 wt.% styrene moiety, between 50 wt.% and 55 wt.% olefin moiety and about 1 wt.% carboxyiic acid moiety.

[28] The above description and examples illustrate certain embodiments of the present invention and are not to be interpreted as limiting. Selection of particular embodiments, combinations thereof, modifications, and adaptations of the various embodiments, conditions and parameters normally encountered in the art will be apparent to those skilled in the art and are deemed to be within the spirit and scope of the present invention.