WO2000014169A1

WO2000014169A1 - Composition and method of use for bleachable, transfer resistant pigmented ink

Info

Publication number: WO2000014169A1
Application number: PCT/US1999/019309
Authority: WO
Inventors: Roy Flint; Gary M. Pool; James C. Daw
Original assignee: A.J. Daw Printing Ink Co., Inc.
Priority date: 1998-09-04
Filing date: 1999-08-25
Publication date: 2000-03-16
Also published as: AU5899599A; WO2000014169A9

Abstract

A pigment based ink composition comprised of a bleachable pigment, and a vehicle containing a polyamide amine resin binder. The pigment based ink composition is bleachable, bleed-fast, and is resistant to transfer and upon drying either when exposed to household chemicals or mechanical processes. A method of using the pigment based ink to print on cellulose substrate is provided together with a method of subsequently decolorizing the ink using a bleaching agent.

Description

DESCRIPTION

Composition And Method Of Use For Bleachable, Transfer Resistant Pigmented Ink

Field of the Invention The present invention relates to a bleachable pigmented ink system to be utilized in the printing and /or decorating of cellulose printing substrates.

Background of the Invention The following factors are inherent to a printing ink and affect print quality: transfer resistance, fade resistance, and bleed resistance. Transfer resistance is the ability of ink, when printed on a substrate, to resist transfer to another object either by mechanical rubbing (i.e., dry rub resistance) or exposure to liquids including water and household chemicals (i.e., chemical fastness). Fade resistance is the ability of ink to maintain the color of the ink over time and exposure to light. Bleed resistance concerns the edge definition of a printed pattern or visual print quality. A printed ink is bleed resistant if the ink does not spread on the printing substrate when wet (i.e., "wick" or "bleed"), thereby exhibiting high visual print quality. Bleachability is another factor inherent to a printing ink. A printed ink is considered bleachable if the ink substantially decolorizes upon exposure to common bleaching agents such as sodium or potassium hypochlorite .

Industrial ink compositions are formulated from either water-soluble dyes or water and solvent insoluble pigments. The properties of dye based ink compositions are especially a problem for inks used on paper towels or other rough cellulose substrates. These cellulose products are routinely exposed to a variety of solvents and common household chemicals such as those used in cleaning formulations (e.g., ammonia, soap, and acetic acid employed in window cleaners) , vinegar, other washing solutions, grease, oil, etc.. Paper towels and other cellulose substrates printed with ink compositions manufactured frorn_^ water-soluble dyes are generally not chemical fast (i.e., the dye based ink formulations used to print on these substrates will transfer to other surfaces when exposed to household chemicals) . Pigment based ink compositions are more transfer resistant than dye based formulations upon exposure to household chemicals, but there is still a need for an improved pigment based ink composition that is resistant to liquids, chemicals and oils and additionally, is bleachable.

Dry rub resistance, another inherent quality of an ink composition, is important to the overall quality of a printing ink. A printing ink is substantially rub resistant if upon application to a printing substrate and drying, the ink adheres to the printing substrate and does not transfer to another surface or is not otherwise removed when exposed to mechanical rubbing. For example, U.S. Patent No. 4,505,944 describes a fugitive ink composition that is substantially removed upon exposure to mechanical processing. Ink compositions such as this are often considered unsuitable as printing ink compositions as they may be removed from the printing substrate by mechanical processing.

Print quality is another important aspect of a printing ink. Ink with high print quality will exhibit sharp visual edge definition of a printed pattern. A component of high print quality is bleed resistance. An ink that does not spread on the printing substrate when wet (i.e., "wick" or "bleed"), exhibits a higher visual print quality. Inks made from water-soluble dyes tend to wick and bleed when printed on uncoated or rough cellulose printing substrates due to the variability in the size and texture of the raw cellulose used to make these products. Low print quality is thus observed in printings with dye-based inks in general and rough cellulose printing substrates in particular. Insoluble pigment based ink compositions generally have higher visual print quality (e.g., bleed resistance) than, dye based ink compositions.

Although the inherent qualities of an ink (e.g., transfer resistance, bleed resistance, and visual print quality) are related to the type of colorant used, whether dye based or pigment based, the quality of a printing ink is also highly dependent on the vehicle that is used. The vehicle may be comprised of various binders, fixatives, and additives (including surfactants, defoamers, and grind aids) , which in combination with the diluting agents and colorants, constitute the ink composition. The selection of the vehicle in combination with the diluting agent and colorant is critical to the inherent quality of the ink

(e.g., transfer resistance, bleed resistance, and visual print quality) . For example, without a binder that adheres a colorant to the printing substrate, the ink composition typically will simply rub off. Similarly, the selection of binder contributes to the chemical resistance and visual print quality of the ink composition. Without the appropriate binder selection, an ink may transfer to other surfaces when exposed to household chemicals or will undesirably wick and bleed when printed.

With a growing emphasis on recyclable consumer products, bleachability is another desirable aspect of an ink formulation. This is especially true for inks used in the printing of paper products. Conventional paper- recycling processes employ sodium or calcium hypochlorite as a bleaching agent. Use of these conventional agents requires that the substrate to be bleached be printed with water- soluble cationic or anionic dyes, which bleach in the presence of hypochlorite. These dye based ink compositions do not have as good a print quality as pigment based ink compositions, may bleach at inappropriate times (e.g., upon exposure to the sunlight) , or may not fully decolorize by the subsequent recycling process of the printed substrate. Known bleachable pigment based ink formulations achieve bleachability by chemical alteration of the pigment prior to_ printing to make it ionic and water-soluble. These ink formulations have many of the same visual print quality and transfer resistance problems associated with dye based ink formulations .

Water based pigmented inks are known, but the desired qualities of an ink composition described herein (e.g., transfer resistance (i.e., chemical fastness and dry rub resistance) , bleachability, and bleed resistance) , have not simultaneously been achieved in a pigmented ink composition. In fact, pigment based ink compositions (i.e., ink compositions based on water insoluble colorants as described in the "The Colour Index," 3^rd Ed., and supplements, The Society of Dyers and Colourists, and The American Association of Textile Chemists and Colorists (1971) ) , are generally considered incompatible with industrial paper bleaching processes.

Pigmented inks for printing on cellulose print substrates that are transfer resistant (i.e., chemical fast and dry rub resistant) , bleachable and have high print quality are not presently known. For example, U.S. Pat. No. 4,505,944 describes an ink composition that employs a complex between a polyvalent metal and tannic acid as the organic pigment and a water insoluble binding agent (e.g. an acrylic polymer) . Although this patent describes a "bleachable" pigmented ink, this ink formulation is brittle upon drying such that it may be removed by mechanical processing (i.e., the ink is not transfer resistant) and the "pigment" is not a colored pigment such as described in "The Colour Index," 3^rd Ed., and supplements, The Society of Dyers and Colourists, and The American Association of Textile Chemists and Colorists (1971) . Further, U.S. Pat. No. 5,746,817 describes a pigment-based ink jet composition, which employs preferably a phthalate based plasticizer as a binding agent, but this ^Λ817 patent does not disclose the additional properties of superior bleachability, and transfer resistance.

There is a need in the printing industry for ink that possesses a high degree of transfer resistance, good visual print quality, and compatibility with common industrial paper bleaching processes especially for printing on rough cellulose substrates such as paper towels.

Summary of the Invention

Therefore, it is an object of the present invention to provide ink that is bleachable, and transfer resistant upon exposure to water, household chemicals or mechanical processes, and provides good visual print quality. A bleachable ink of the present invention, for marking a cellulose substrate, is comprised of a water insoluble bleachable pigment which is dispersable in a transfer resistant vehicle. The vehicle is capable of bonding to the substrate and upon drying, the mark resists transfer upon exposure to mechanical methods, liquids, or household chemicals and is yet discolored upon exposure to a bleaching agent .

In another aspect of the invention a method of providing and removing a bleed-resistant mark on a substrate is described. The method comprises the steps of contacting the substrate with a bleachable, transfer resistant ink; drying the ink to provide a mark that is transfer resistant upon exposure to mechanical processes or liquids, for example household chemicals, and exposing the mark to a bleaching agent to decolorize the ink.

Brief Description of the Drawings

Figure 1 shows a graphical comparison of ink quality between the bleachable pigmented ink composition of the present invention and other pigmented and dye based ink compositions .

Detailed Description of the Invention The ink of the present invention described herein includes a combination of various binders, fixatives, and additives (including surfactants, defoamers, and grind aids) , which in combination with diluting agents constitute a transfer resistant vehicle. When the transfer resistant vehicle is used in combination with bleachable pigments, an ink that is bleachable, transfer resistant, and exhibits good visual print quality when printed on a cellulose substrate is formulated. Examples of such cellulose substrates include but are not limited to paper, paper towels, napkins, facial tissue, toilet paper, paper plates, cardboard, crepe paper, tissue paper, wrapping paper, cards, and envelopes . The inks are bleachable upon treatment with common cellulose bleaching agents such as sodium and potassium hypochlorite (Na⁺0C1^~ and K⁺0C1^") . In addition, these inks exhibit high visual print quality (e.g., resistance to bleeding) and are transfer resistant upon exposure to liquids including household chemicals and mechanical processes including rubbing.

Print quality represents different qualities of a printed ink such as transfer resistance (e.g., dry rub resistance and chemical fastness), and bleed resistance. Dry rub resistance is characterized by the ability of an ink to adhere to a printed substrate. Bleed resistance is characterized by the ability of an ink to resist wicking, bleeding, or feathering onto a printed substrate. Low visual print quality is characteristic of non-bleed resistant ink as exemplified by broad printed line width and edge raggedness. As used herein, the term chemical fast describes the ability of a dry printed ink to remain bound to a printed substrate and not transfer to other substrates or surfaces upon exposure to liquids, chemicals, fats, and oils. The inks of the present invention are especially chemical fast upon exposure to household liquids, chemicals, fats, and oils. Examples of such liquids, chemicals, fats and oils include but are not limited to water, vinegar,_^ alcohol, ammonia, strong and mild soap solutions, cleaning formulations, window cleaners, perfumes, waxes, furniture polishes and cleaners, oils including mineral oils, silicone oils, synthetic oils, cooking oils and vegetable oils, fats including lard, synthetic greases, and bacon grease including hot bacon grease.

The preferred embodiments of the ink of the present invention contain a water insoluble pigment in an amount up to about 15% by weight of the total composition. A preferred range of pigment is from 3 to 12% by weight of the total ink composition. The preferred pigments employed in the ink compositions are water insoluble organic or metallo- organic pigments, which are bleachable when printed on cellulose in combination with the vehicles described herein. The term "pigment" refers to a water insoluble colorant as described in the "The Colour Index," 3^rd Ed., and supplements, The Society of Dyers and Colourists, and The

American Association of Textile Chemists and Colorists

(1971) . A variety of these pigments may be selected to make the ink compositions. Preferred pigments include, but are not limited to pigments from the phthalocyanine, indigoid, and aminonapthalimide family of colorants which, when printed upon a cellulose substrate, bleach with common bleaching agents and are transfer resistant when used in combination with the vehicles of the present invention. More preferred pigments include: C.I. Pigment Red 122 (C.I. No. 73915, e.g., PV Fast Pink E-01™, manufactured by Hoechst Celanase) , C.I. Pigment Red 207 (e.g., Scarlet RT-788-D™, manufactured by Ciba Specialty Chemicals Corporation), C.I. Pigment Blue 17 (C.I. No. 74180, e.g., Sky Blue™, commercially available from H&C Industries), C.I. Pigment Blue 17.1 (C.I. No. 74180:1), C.I. Pigment Yellow 185 (C.I. No. 56290, e.g., Paliotol Yellow D 1155™, manufactured by BASF Corporation), C.I. Pigment Yellow 139 (C.I. No. 56298, e.g., Yellow L 2140 HD™, manufactured by BASF Corporation), C.I. Pigment Orange 64 (C.I. No. 12760, e.g., Cromophtal- Orange GP™, manufactured by Ciba-Geigy Corporation), C.I. Pigment Violet 19 (C.I. No. 73900, e.g., Violet R RT-301-D™, manufactured by Ciba-Geigy Corporation), and C.I. Pigment Violet 5 (C.I. No. 58055:1, e.g., Alizarine Maroon™ manufactured by Paul Uhlich and Co) . Ink compositions of the invention described herein further contain a transfer resistant vehicle which may include various binders, fixatives, and additives (including surfactants, defoamers, and grind aids) , and diluting agents which in combination with bleachable pigments constitutes the bleachable, transfer resistant inks. The additives may include various surfactants, defoamers and other additives, which improve the consistency of the ink composition. Preferred additives include acetylenic diols, such as Surfynol 440™ available from Air Products and Chemicals, Inc., polyoxyalkylene polymers, siloxane glycol copolymers, polyglycols, organosiloxane copolymers and mixtures thereof such as DEE FO 3010E/50™ and DEE FO PI-35™ available from Ultra Additives Inc., DF-66™ available from Air Products and Chemicals, Inc., and FOAM BURST 338™ available from Ross Chem, Inc. In a preferred aspect, the additives including surfactants, defoamers comprise up to about 10% total combined weight of the ink composition. In a more preferred aspect, an ink composition consists of a surfactant including one of Surfynol CT-131™ Grind Aid, Triton X-405™ from Union Carbide Corporation, and PDA-2000™ from Spartec, Inc., in 1-6% by weight, and an organosiloxane copolymer surfactant including DEE FO 3010E/50™ and DF-66™ in 0.10- 1.0% by weight, and an ethoxylated acetylenic diol surfactant such as Surfynol 440™ in 0.10-1.0% by weight. In a most preferred aspect, the ink composition comprises PDA- 2000™ surfactant (2.8% by weight), an organosiloxane copolymer surfactant (0.50% by weight, e.g., DF-66™), and an ethoxylated acetylenic diol defoamer (0.50% by weight).

The ink composition may additionally contain in the vehicle binders such as polyamide amine resin solution. (e.g., Cartaretin F4™ liquid available from Clariant Corporation in a 30% solution) , and oxyalkylene polymers including polyethylene glycol (e.g., Carbowax P.E.Glycol 300™, available from Union Carbide Corporation, also referred to as "Polyglycol 300") . In a preferred aspect, the ink composition consists of 10-30% of an approximately 30% polyamide amine resin solution (about 3-9% of a polyamide amine resin total) by weight of the total composition, and an oxyalkylene polymer in 3-18% by weight of the total composition. In a more preferred aspect, the ink composition consists of a 30% polyamide amine resin solution (e.g., Cartaretin F4 Liquid™ resin solution), in about 13-16% by weight of the total composition and an oxyalkylene polymer such as polyethylene glycol in about 4- 13% by weight of the total composition. The ink composition may include various diluting agents that serve to adjust the concentration of the ink composition and to allow for an ideal consistency for specific printing or decorating purposes. The diluting agent may include water, alcohols, glycols, ethers, and other organic solvents suitable for ink compositions and mixtures thereof. The amount of diluting agent added is preferably about 50 to 80% by weight.

Further according to a preferred embodiment, the ink composition may contain various additives for the purpose of improving various properties of the ink composition, such as antiseptic agents, mildew proofing agents, pH adjustors, dye dissolution assistants, antioxidants, conductivity modifiers, surface tension modifiers, and oxygen-absorbing agents. Examples of the antiseptic and mildew proofing agents include but are not limited to sodium benzoate, sodium pentachlorophenol , sodium 2-pyridinethiol-l-oxide, sodium sorbicate, sodium dehydroacetate and 1,2- dibenzothiazolin-3-one. Examples of the pH adjustor, dye dissolution assistant, and antioxidant include amines, inorganic salts, such as potassium hydroxide, sodium_^ hydroxide, and lithium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, carbonates and phosphates, such as potassium carbonate, sodium carbonate, and lithium carbonate, or ureas such as urea, thiourea, tetramethylurea, and others . In addition, various viscosity modifers may be added to the ink composition. Examples of viscosity modifers include, rosins, alginic acids, polyvinyl alcohol, celluloses (e.g., hydroxypropyl cellulose, carboxymethyl cellulose, and methyl cellulose) , polyacrylates polyvinylpyrrolidone, gum arabic starch, and others.

A fixative may additionally be employed in the vehicle. Examples of fixatives include copolymers from the Guanidine, cyano- family of polymers (e.g., dicyandiamide- diethylenetriamine copolymer) . For example, Neofix RP-70™, available from Nicca USA, Inc., a dicyandiamide- diethylenetriamine copolymer, is used in a preferred embodiment in about 1-4% by weight of the total composition. In a most preferred aspect, Neofix RP-70™ is used in about 2% by weight of the total composition. Ink compositions are produced according to a preferred method. In a preferred method, diluting agents, surfactants, additives, and pigment are combined in a mixer to form the pigment concentrate. Additional diluting agents and surfactants are then mixed with the pigment mixture to form an ink composition with a proper consistency for a desired application by standard industry methods . In a preferred embodiment, water (in the range of 25-30% by weight) , Spartec PDA-2000™ (about 3% by weight) , DF-66™

(about 0.5% by weight), polyethylene glycol (about 5% by weight), polyamide amine resin solution (30%) (about 15.5% by weight) , and pigment (about 6% by weight) are combined on a mixer. Additional water (about 32-41% by weight) and Surfynol 440™ (about 0.5% by weight) is then added with further mixing.

Ink compositions may be mixed with additives or extenders to form a secondary color ink composition (i.e., a second color resulting from the combined colors of the primary inks) . For example, gold ink can be prepared by combining yellow and red ink compositions with an extender varnish. In a preferred embodiment, about 66% by weight of a yellow ink composition is combined with about 8% of a red ink composition, about 14% extender varnish and about 2% fixative, 7% Carbowax Polyethylene Glycol 300™ (polyethylene glycol) , 1% Cartaretin F4 Liquid™ (polyamide amine resin solution (30%)) and 1% defoamer to form a gold ink. The extender varnish is a mixture of surfactants, additives, and diluting agents. In a preferred embodiment, an extender varnish contains 10-20% by weight of a polyamide amine resin solution, 60-90% by weight of a diluting agent, 3-7% of an oxyalkylene polymer, and 0.2-2.0% of a defoamer. In a more preferred embodiment, an extender varnish contains about 17% by weight of a polyamide resin solution (30%) , 77% by weight of water, about 5% by weight of polyethylene glycol, about 0.5% of an organic defoamer, and about 0.5% of an ethoxylated acetylenic diol. Additionally, colored inks may be combined in varied amounts to produce inks with hues dependant on the ratio of primary colored ink added to the mixture. For example, mixing a large amount of red ink with a small amount of yellow ink and a small amount of blue ink forms mauve ink. Further, mixing a large amount of blue ink with a small amount of yellow ink and a smaller amount of red ink produces a medium shade green ink. Decreasing the ratio of yellow ink to blue ink and slightly increasing the amount of red ink produces a medium shade blue ink. In a preferred embodiment, mauve ink is produced by combining about 76% by weight of a red ink, about 9% by weight of a yellow ink, about 5% by weight of a blue ink and about 2% fixative, 7% Carbowax Polyethylene Glycol 300™ (polyethylene glycol) , 1% polyamide amine resin solution (30%) and 1% defoamer. Another preferred embodiment produces medium shade green ink by combining about 73% by weight of a blue ink, about 14% by weight of a yellow ink, and about 3% by weight of a red ink, and about 2% fixative, 7% Carbowax Polyethylene Glycol 300™ (polyethylene glycol) , 1% polyamide amine resin solution (30%) and 1% defoamer.

Another preferred embodiment produces a medium shade blue ink by combining about 81% by weight of a blue ink, about 8% by weight of a red ink, and about 1% by weight of a yellow ink, and about 2% fixative, 7% Carbowax Polyethylene Glycol 300™ (polyethylene glycol), 0.5% polyamide amine resin solution (approximate 30% solution ) and 0.3% defoamer. In addition, other colors may be combined in the manner set out above to form additional secondary colors and various shades of existing colors and the above examples are provided to illustrate the invention and do not limit the invention.

The suitability of a particular pigment, and vehicle including additives, surfactants, defoamers and binders for use in the present invention is readily determinable by one skilled in the art given the present disclosure and the following examples are provided merely as examples to further illustrate the invention. It should be understood that the examples provided below do not limit the invention to the formulations provided therein. INK FORMULATION EXAMPLES

Example 1. RED INK

Material Weight

Water 29.90

Spartec PDA-2000™ (Grind Aid) 2.80

DF-66™ 0.50

Polyglycol 300 5.00

Cartaretin F-4 Liquid™ 15.00

PV Fast Pink E-01™ 5.60

Water 40.70

Surfynol 440™ (Surfactant) 0.50

Example 2. YELLOW INK

Material Weight Water 31.71

Spartec PDA-2000™ (Grind Aid) 2.97

DF-66™ 0.53

Polyglycol 300 5.30

Cartaretin F-4 Liquid™ 15.91 Paliotol Yellow D 1155™ 5.94

Water 37.12

Surfynol 440™ (Surfactant) 0.53 Example 3. BLUE INK

Material Weight

Water 30.98

Spartec PDA-2000™ (Grind Aid) 4.04 DF-66™ 0.52

Polyglycol 300 5.18

Cartaretin F-4 Liquid™ 15.54

C.I. Pigment Blue 17 10.78

Water 32.44 Surfynol 440™ (Surfactant) 0.52

In Examples 1-3, Surfynol CT-131™ may be substituted for Spartec PDA-2000™ in the corresponding percent weight of the total composition. Additionally, in Examples 1-3, DEE FO 3010™ may be substituted for DF-66 in the corresponding percent weight of the total composition.

Example 4. EXTENDER VARNISH

Material Weight

Cartaretin F-4 Liquid™ 16.70

Water 33.40

Polyglycol 300 5.60

Foam Burst 338™ 0.50

Water 43.30

Surfynol 440™ (Surfactant) 0.50 Example 5. GOLD INK

Material Wei .qht

Yellow Ink (Example 2) 66 . 51

Red Ink (Example 1) 8 . 28

Extender Varnish (Example 4) 14 . 21

Mix Well

Then add slowly one at a time while mixing

Neofix RP-70™ 2.00

Carbowax™ P.E. Glycol 300 7.50

Polyamide amine (Cartaretin F-4™) .50

Surfynol DF-66™ (Defoamer) 1.00

Example 6. MAUVE INK Material Weight

Yellow Ink (Example 2) 8.59 Red Ink (Example 1) 75.69 Blue Ink (Example 3) 5.42 Mix Well

Then add slowly one at a time while mixing

Neofix RP-70™ 2.00 Carbowax™ P.E. Glycol 300 6.80 Polyamide amine (Cartaretin F-4™) .50 Surfynol DF-66™ (Defoamer) 1.00 Example 7. MEDIUM SHADE GREEN INK.

Material Wei .qht

Blue Ink (Example 3) 73 . 30 Yellow Ink (Example 2) 13 . 70 Red Ink (Example 1) 2 . 70

Mix Well

Then add slowly one at a time while mixing

Neofix RP-70™ 2.00 Carbowax™ P.E. Glycol 300 6.80

Polyamide amine (Cartaretin F-4™) .50 Surfynol DF-66™ (Defoamer) 1.00

Example 8. MEDIUM SHADE BLUE INK. Material Weight

Blue Ink (Example 3) 80 . 57

Yellow Ink (Example 2) 1 . 13

Red Ink (Example 1) 8 . 00

Mix Well Then add slowly one at a time while mixing

Neofix RP-70™ 2.00

Carbowax™ P.E. Glycol 300 7.50

Polyamide amine (Cartaretin F-4™) .50 Surfynol DF-66™ (Defoamer) .30 Ink Comparison Tests.

Fastness to household chemicals, bleachability, rub resistance and print quality were tested on the ink compositions described herein and on comparison examples as shown in Table 2. Each of the ink compositions shown in Examples 1-3 and 5-8 and ink compositions prepared with preferred pigments according to the preferred embodiments were tested as described below against other dye and non- bleachable ink compositions with the chemicals shown in Table 1. The ink compositions of the present invention were the only compositions to simultaneously exhibit superior bleachability, visual print quality, mileage, strength, odor, clean-up, reducibility, dry rub, water bleed, vinegar bleed, alcohol bleed, mild soap bleed, and strong soap bleed.

The printed test proofs were prepared in the following manner using commercially available paper towel stock such as Sparkle™ from Georgia Pacific Corporation; Hi-Dry™ and Scott™, both from Kimberly-Clark Corporation; and Mardi Gras™ from Fort James Corporation. The experiments were conducted using a 186 line anilox hand proofer to make a print of the test ink on the towel stock. The printed proofs were dried for twenty-four (24) hours.

The chemical resistance tests were performed in the following manner. A 1.5" x 1" section of the printed towel sample was placed print side down on a Filter Paper

(Standard Grade #201, 5" round) . The back side of the printed sample was saturated with the designated household test material. The saturated back of the printed towel sample was covered with filter paper and then a 5" plastic sheet. The plastic sheet was covered with a 3 x 4 glass panel and a 2 lb weight was allowed to set on the sample for 30 minutes. The filter paper was then observed for transfer of the printed ink. The procedure was then repeated with a different household test material. The results are shown in Table 1. Table 1.

Household Test Materials Water Vinegar Vodka Windex Formula 409

Ivory Soap (5% aqueous solution) Milk Hot Bacon Grease

The ink compositions as shown in Examples 1-3 and 5-8 as well as ink compositions prepared with the additional preferred pigments according to the preferred embodiments were tested with the household test materials shown in Table 1. Excellent resistance to transfer of the printed ink onto the filter paper was observed for all samples as shown in Table 2. In addition, comparison tests with the household test materials shown in Table 1 with commercially available cationic (e.g., Hydroply 510 Series™, manufactured by A.J. Daw Printing Ink Co., hereafter "Daw Ink") and acidic pigment compositions (e.g., Hydroply 560 Series™ manufactured by Daw Ink), as well as anionic (e.g., Hydroply 500 Series™, manufactured by Daw Ink) and alkaline dye compositions (e.g., Fastisol™ manufactured by BASF Corporation) were performed according to the procedure described above. The results of the comparison tests are displayed in Table 2. Figure 1 is a graphical representation of selected results.

The ink compositions of Examples 1-3 and 5-8 and ink compositions prepared with preferred pigments according to the preferred embodiments were tested for bleachability using the following procedure. An explosion proof hot plate was set to 110°F. A beaker of 142.5 g of hot water and 7.5 g of liquid bleach (e.g., Chlorox™) was placed on the hot plate, covered and then heated for 15 minutes. A sample proof, as prepared above, was added to the solution. The proof was cooked for 30 minutes and then removed from the hot bleach solution and allowed to fully dry. The bleached ink sample proof was compared to an unprinted standard and ranked from 1-6 (l(fair) - 6 (excellent) ) . The ink compositions as shown in Examples 1-3 and 5-8 as well as inks prepared according to the invention with other preferred pigments fully bleached as compared to the unprinted standard. The results are shown in Table 2. Comparison tests for bleachability with commercially available alkaline and acidic pigment compositions as well as commercially available anionic dye compositions and cationic dye compositions were performed according to the procedure described above and ranked according to the same scale. The results are also shown in Table 2. As shown in Table 2, and displayed graphically in figure 1, other commercially available pigmented ink compositions (e.g., Hydroply 500 Series™ and Hydroply 510 Series™ both from Daw Ink) did not bleach when exposed to the test conditions as described above, and commercially available cationic (e.g., Fastisol™ from BASF Corporation) and anionic (e.g., Hydroply 560 Series™ from Daw Ink) dye based ink compositions showed similar or lesser bleaching properties.

Other desirable ink qualities were examined with ink compositions of the present invention such as visual print quality, dry rub, mileage, strength, odor, clean-up, and reducibility and compared to commercially available pigmented and dye based ink compositions. The results of these tests also are shown in Table 2. The bleachable ink compositions of Examples 1-3 and 5-8 and ink compositions prepared with preferred pigments according to the preferred embodiments tested remarkably well in all categories. Of the ink compositions tested, only the ink composition of the current invention (e.g., Examples 1-3 and 5-8), possessed exemplary visual print quality, bleachability, and transfer resistance. Selected results are displayed graphically in Figure 1.

While the description herein provides various examples_^ of formulations and methods within the present invention, it will be understood that these are examples only, and that the scope of the invention is as set forth in the following claims including lawful equivalents thereof.

Table 2. TOWEL AND TISSUE INK COMPARISON CHART Ink Comparison Data

Alkaline PH

Bleachable

Pigment

Cationic Anionic Acidic pH Alkaline pH (Ex. 1-3 an

Dve- Dve¹ Piαment- Pigment- 5-8) *

PH 3, .5- -4 .0 7. .0-8.0 6.2-6.7 8.2-8.7 7.5-8 3

BLEACHABLE 4 .5 5 0 0 5

VISUAL PRINT QUALITY 3 4 5 5 5

MILEAGE 5 5 4.5 4.5 4 5

STRENGTH 3 4.6 5 5 4 5

ODOR 1 5 5 5 5

CLEAN-UP 3 4 4 5 5

REDUCIBILITY 4 .5 4.5 4 4 4

DRY RUB 4 4 5 5 5

- Cationic Dye such as Fastosol™ from BASF Corporation.

- Anionic Dye such as Hydroply 560 Series™ from Daw Ink.

- Acidic pH Pigment Ink such as Hydroply 500 Series™

- Alkaline pH Pigment Ink such as Hydroply 510 Series™ from Daw Ink.

- The ink compositions of Examples 1-3 and 5-8 as well as ink prepared with preferred pigments 'according to the present invention were all tested and displayed similar results.

Table 2. TOWEL AND TISSUE INK COMPARISON CHART (cont'd.)

Ink Comparison Data

Alkaline pH Bleachable Pigment

Cationic Anionic Acidic pH Alkaline pH (Ex. 1-3 an Dye Dye Pigment Pigment 5-8)

Household Chemical Tests

WATER BLEED 4 4 5 5 5

VINEGAR BLEED 4 4 5 5 5

ALCOHOL BLEED 4 4 5 5 5

MILD SOAP BLEED 5 5 5 5 6

STRONG SOAP BLEED 3 3.5 4.5 4.5 4.5

(1) FAIR to (6) EXCELLENT

Claims

Claims :

1. A bleachable, transfer resistant ink for marking a cellulose substrate comprising: a transfer resistant vehicle capable of bonding to the substrate and drying; and a water insoluble bleachable pigment dispersible in said vehicle, wherein the mark, when dry, resists transfer upon exposure to mechanical methods and liquids, and the mark is substantially decolorized upon exposure to a bleaching agent .

2. The ink of claim 1, where said liquids are household chemicals.

3. The ink of claim 1, wherein the vehicle contains a polyamide amine resin.

4. The ink of claim 3, wherein the vehicle contains an approximately 30% polyamide amine resin solution in an amount from about 10 to about 30% of the total composition.

5. The ink of claim 1, wherein the water insoluble bleachable pigment is selected from the group consisting of:

C.I. Pigment Red 122, C.I. Pigment Red 207, C.I. Blue 17, C.I. Blue 17.1, C.I. Pigment Yellow 185, C.I. Pigment Yellow 139, C.I. Pigment Orange 64, C.I. Pigment Violet 19, and C.I. Pigment Violet 5.

6. The ink of claim 1, wherein the amount of water- insoluble bleachable pigment is by weight about 3% to about 12 % of the total composition.

7. The ink of claim 1, wherein the vehicle contains a polyamide amine resin and the pigment is C.I. Blue 17.

8. The ink of claim 1, wherein the vehicle contains a polyamide amine resin and the pigment is C.I. Blue 17.1.

9. A method of providing and substantially decolorizing a transfer resistant mark on a substrate comprising the steps of: providing a bleachable pigmented, transfer- resistant ink, a substrate and a bleaching agent; contacting the substrate with the bleachable pigmented, transfer-resistant ink; drying the ink to provide a mark that is transfer resistant upon exposure to mechanical methods and liquids; and exposing the mark to a bleaching agent to decolorize the ink.

10. The method of claim 9, wherein the bleaching agent is at least one of sodium and potassium hypochlorite.

11. A method of providing a bleachable pigmented, transfer-resistant mark on a substrate comprising the steps of: providing a bleachable pigmented, transfer- resistant ink and a substrate; contacting the substrate with the bleachable, transfer resistant ink; drying the ink to provide a bleachable mark that is transfer resistant upon exposure to at least one of liquids and mechanical methods.

12. The method of claim 11, wherein said substrate is a cellulose substrate.

13. The method of claim 11, wherein said substrate is selected from the group consisting of paper, paper towels, napkins, facial tissue, toilet paper, paper plates, cardboard, crepe paper, tissue paper, wrapping paper, cards, and envelopes .

14. The method of claim 11, wherein said substrate is a paper towel.

15. The method of claim 11, wherein said liquid is a household chemical.

16. The method of claim 11, including a step of exposing the mark and substrate to a bleaching agent to decolorize the mark.