AU749524B2 - Additives for printing inks that provide release - Google Patents

Description

WO 00/02966 PCT/US99/05309 -1- Additives for Printing Inks That Provide Release Field of the Invention This invention relates to printing inks, particularly to additives for printing inks that provide a low energy surface and articles using printing inks with additives.

Background of Invention Repositionable note pads, tapes and linerless labels typically consist of sheets of stock (paper, films, etc.) coated with pressure sensitive adhesive (and optionally a primer) on one side of the sheet and a release coating (also referred to as "low adhesion backsize" or "LAB") on the other side. In either pad (stacked sheets) or roll form, the release coating is in contact with the adhesive. In pad form, the release coating is used to lower the force required to remove the adhesive from the adjacent sheet in order to facilitate dispensing and minimize stock deformation or curl. In roll form, the release coating is used to ensure easy unwind during processing and dispensing.

Lithographic, flexographic, or gravure printing processes are often used to prepare printed repositionable notes, tapes and linerless labels. Often, the printing process is separate from and subsequent to the process that applies the adhesive and release coating.

In such situations, a roll of stock that has been pre-coated with adhesive and a release material is routed through a printing press, ink is printed on top of the release coating, and the printed material is immediately either rolled back up or cut into a stack of discrete sheets. Printing of ink over the release coating renders the release coating ineffective.

Undesirable adhesive-ink interactions are also formed which results in poor release (high unwind, tear outs, poor dispensing) and transfer of ink from the printed stock to the adhesive. Such "ink transfer" damages the printed image and contaminates the adhesive.

Common release materials that are used with pressure sensitive adhesives (PSAs) are typically based on moieties that have low surface energies such as aliphatic compounds, silicones and fluorochemicals. Traditional ink additives that are used to lower the "tack" of printed inks include polyethylene, polypropylene or polytetrafluoroehtylene (such as Teflon®) particles or waxes. These have been found to be relatively ineffective at reducing PSA/ink interactions. Silicone additives are generally avoided as they can cause WO 00/02966 PCT/US99/05309 -2ink-wetting problems on the print rollers or plates and adversely affect transfer of ink from the printing plate to the substrate and print quality.

Recently, the addition of organopolysiloxanes that contain mercapto groups to ultraviolet (UV)-curable lithographic inks has been reported (Japanese Kokai: J.P. Sho.

56-118472) for use in the printing of polyethylene or polypropylene coated papers. The addition of the mercapto containing silicone reduces the tendency of printed sheets to fuse together after exposure to excessive heat and pressure. In contrast, no desired improvements are observed when mercapto-containing silicones are added to air-curable lithographic inks.

To date, it is believed that no references describe the addition of organopolysiloxanes that contain mercapto groups to lithographic inks in order to improve the properties of printed PSA products such as repositionable notes, tapes arid linerless labels. It may be considered advantageous to have ink that would not form undesirable adhesive-ink interactions, and, preferably, would act as a release material. Such ink may 5 eliminate the aforementioned problems of poor release and high "ink transfer" and allow for the manufacture of improved (better release, less ink transfer) printed repositionable notes, tapes and linerless labels.

Summary of Invention Briefly in one aspect of the present invention, releasable lithographic inks that provide release characteristics to printed inks are provided comprising UV-curable or air-curable printing inks and a release additive. The preferred additives to the UV- S curable or air-curable inks are mercaptopolydiorganosiloxane copolymers.

Inks containing additives such as mercaptopolydiorganosiloxane copolymers can be advantageously used in products that have pressure sensitive adhesives (PSAs) in 25 contact with the printed inks in order to reduce undesirable PSA/ink interactions.

Undesirable PSA/ink interactions that are avoided by this invention include "ink transfer" from the printed image to the adhesive which results in damage to the printed image and adhesive contamination, and high release forces during unwind or sheet removal which can cause damage to the backing or render the product unusable.

Another class of additives that may provide good properties for UV-curable inks are acrylate terminated silicones ("silicone macromers"). An example of such materials is WO 00/02966 PCT/US99/05309 -3- Silicone "Plus" HG-10 Siloxane, which is commercially available from 3M Company, St.

Paul, MN. Silicone "Puls" HG-10 is a methacrylate terminated poly(dimethylsilicone) polymer having a number average molecular weight of 10,000.

In another aspect of the present invention, adhesive coated articles are provided comprising a backing substrate having a front and back surface, a layer of pressure sensitive adhesive on at least one portion of the back surface of the backing substrate, and indicia on the front surface of the backing substrate, wherein the indicia is printed using lithographic inks having release characteristics.

Furthermore, in yet another aspect of the present invention, a pad assembly is provided comprising a multiplicity of flexible sheets each having similarly sized body portion that have pressure sensitive adhesive on the back surface and indicia printed on the front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when a sheet is removed from the pad assembly, the sheet is easily removable and the lithographic ink is not transferred from the front of the sheet of a 15 first sheet to the back of the sheet of second sheet overlaying the first sheet. The multiplicity of sheets have pressure sensitive adhesive coated onto the back surface of the sheets and the sheets are disposed in a stack with the corresponding peripheral edges of the body portions of the sheets aligned and the pressure sensitive adhesive of each sheet adhering that sheet to the adjacent sheet in the stack. Such products include printed repositionable note pads (such as 3M Post-it® Notes), linerless labels, printed pressure sensitive tapes, adhesive coupons, and the like.

Advantageously, using lithographic inks having release characteristics may s provide a construction that eliminates the need of providing a release coating on sheets having indicia printed on the front of them.

25 In a further aspect of the present invention. a method of using lithographic inks having release characteristics are providing comprising the steps of: blending a UV-curable or air-curable printing ink with an appropriate weight percent of an additive that functions as a release coating; printing the blended ink onto a substrate having a front and back surface, such that the printing is positioned on the front surface of the substrate coincident with the adhesive coating applied on the back surface of the substrate; -4stacking the printed substrates into a pad or winding the printed substrate onto a roll core.

More specifically, the invention as claimed hereinafter provides in one aspect, a releasable lithographic ink composition comprising an air-curable printing ink and (b) mercaptopolydiorganosiloxane copolymer additive having the following general formula: R4 R6 RS

CH

2

I

SH

wherein: y ranges from 0.5 to about 80% of (x y); RI, Rz and R 3 are monovalent moieties that can independently be the same or different 15 and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R4, Rs, and R6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

In another aspect, the invention as claimed provides an adhesive coated article comprising a backing substrate having a front and back surface, a layer of pressure sensitive adhesive on at least one portion of the back surface of the backing substrate, and 25 indicia on the front surface of the backing substrate, wherein the indicia is printed using a releasable lithographic ink comprising an ultraviolet curable printing ink or an air-curable printing ink and mercaptopolydiorganosiloxane copolymer additive having the following general formula: 4a- R R2R3Si--OSi Si- OSiRiR 2

R

3 Rs CH 2

SH

SH

wherein: y ranges from 0.5 to about 80% of (x y);

R

1 Rz and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups;

R

4 Rs, and R 6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; 15 z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

Additionally, the invention as claimed provides a pad assembly comprising a multiplicity of flexible sheets each having similarly sized body portion that have pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when a sheet is removed from the pad assembly, the sheet is easily removable and the lithographic ink is not transferred from the front of the sheet of a first sheet to the back of S* the sheet of second sheet overlaying the first sheet, wherein the lithographic ink comprises an ultraviolet curable printing ink or an air-curable printing ink and (b) mercaptopolydiorganosiloxane copolymer having the following general formula: R4 R 6 RIR2R3Si-- OSi x Si- OSiRiR2R3 Rs CH2 S SH 4b wherein: y ranges from 0.5 to about 80% of(x y); RI, R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R4, Rs, and R6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

In a further aspect, the invention as claimed provides a roll of adhesive coated material comprising a substrate having at least one portion that has a pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when the material is unrolled from the roll, the material is easily removable and the lithographic ink is not transferred from the front of the substrate, wherein the lithographic ink comprises an ultraviolet curable printing ink or an air-curable printing ink and (b) mercaptopolydiorganosiloxane copolymer having the following general formula: R4 R6

RR

2 R :Si- OSi- -OSiRR 2

R

2) z

SH

***wherein: y ranges from 0.5 to about 80% of (x y); RI, R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R4, Rs, and 1R are monovalent moieties that can independently be the same or different 4cand are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from I to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

In another aspect, the invention as claimed provides a pad assembly comprising a multiplicity of flexible sheets each having similarly sized body portion that have pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when a sheet is removed from the pad assembly, the sheet is easily removable and the lithographic ink is not transferred from the front of the sheet of a first sheet to the back of the sheet of second sheet overlaying the first sheet, wherein the lithographic ink comprises an ultraviolet curable printing ink and a methacrylate-terminated poly(dimethylsiloxane) having a number average molecular weight in the range of 5,000 15 to 50,000.

Additionally, the invention as claimed provides a roll of adhesive coated material •comprising a substrate having at least one portion that has a pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when the material is unrolled form the roll, the material is easily removable and the lithographic ink is not transferred from the front of the substrate, wherein the lithographic ink comprises an ultraviolet curable printing ink or an air-curable printing ink and a methacrylateterminated poly(dimethylsiloxane) having a number average molecular weight in the range of 5,000 to 50,000.

S.Description of the Preferred Embodiment(s) In this invention, ink additives have been discovered that eliminate the aforementioned problems of poor release and high "ink transfer". The additives can be blended with commercially available UV or air-curable lithographic inks and the resultant inks printed on standard lithographic printing presses.

4d- While not to be bound by theory, it is believed that the mercapto group of the additive enters into the curing processes of both air-curable and UV-curable lithographic inks and becomes covalently bound to the cured ink. The bound additive will not transfer to and contaminate pressure sensitive adhesives that may come in contact with the ink.

Additive Types Preferred additives are mercaptopolydiorganosiloxane copolymers that are described by the following general formula R4 R 6

R

1

R

2

R

3 S-i- OSi OSi OSiRR 2

R

3 1 x y

R

5

CH

2

SH

wherein: 15 y can range from 0.5 to about 80% of (x preferably from 1-20% of (x y) and most preferably from 3.5 14% of (x y); RI, R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups and are most preferably alkyi moieties:

R

4 Rs, and R 6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, and are most preferably alkyl moieties; z can range from I to about 16, preferably from 1 to 5 and is most preferably 3.

WO 00/02966 PCTIUS99/05309 x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

The molecular weight of the additive can range from about 1000 to about 200,000.

The preferable range is from about 5000 to about 50,000. In these preferred ranges the additive has a viscosity which is desirable for blending into inks. The molecular weight can also affect additive effectiveness. Optimal molecular weights will be dependent on additive and ink type.

A most preferred additive is commercially available from Shin-Etsu, Inc. (1150 Damer Drive, Akron, OH 44305 under the commercial designation of "X-22-980") wherein RI, R 2

R

3

R

4 Rs, and R 6

CH

3 y 3.5 4.5% of (x z 3, and the number average molecular weight (Mn) 8000. Most preferably, any cyclic material that may be present is removed prior to use by such methods as evaporation under vacuum at elevated temperatures (for example, 150 0 C, 200 mm Hg). Additional most preferred additives of varying values of R, x, y and z are available from Huls America Inc. (Piscataway,

NJ).

The additive is added to the ink in amounts ranging from 0.1 to 15% by weight of the ink and most preferably between 1 and The optimum additive amount will be dependent on the strength of the pressure sensitive adhesive and desired release value in the printed product. Addition of too much additive can cause wetting problems on the print rollers and blankets and adversely affect the printing process. The upper limit of additive ranges between about 5 and 15% depending on the printing press type, roller and blanket materials, and ink formulation.

The mercapto content (weight percent SH moieties based on weight of additive) in the additive can range from about 0.1 to about 20 weight percent. Most preferable mercapto contents range from 0.35 to about 4 weight Additive effectiveness appears to decrease at very high levels of SH. For example, poly(mercaptopropylmethylsiloxane) (26 wt% SH) is not a very effective additive.

Another class of additives that provide good properties for UV-curable inks are acrylate terminated silicones ("silicone macromers"). An example of such materials is Silicone "Plus" HG-10 Siloxane, which is commercially available from 3M Company St.

Paul, MN. Silicone "Puls" HG-10 is a methacrylate terminated poly(dimethylsilicone) polymer having a number average molecular weight of 10,000.

Traditional ink additives such as polyolefin and polytetrofluoroethylene (such as Teflon®) waxes and particles have been found to be ineffective. Also ineffective are WO 00/02966 PCTIUS99/05309 -6fluoroacrylate compounds such as FluoradTM FX-189, FluoradTM FX-13 and FluoradTM FX-14 that are commercially available from 3M Company, St. Paul, MN.

Ink Types Preferable lithographic inks are curable by UV irradiation although lithographic inks that are curable by air-oxidation may also be used. Typical lithographic inks that are commercially available from common ink suppliers can be used.

Suitable UV-curable lithographic inks include UV 1/D process inks from Kohl and Madden Corporation (Minneapolis, MN), and UVALUX process inks from Zeller Interchem Corporation (2205 Tomlynn Street, Richmond, VA 23230).

Suitable air-curable lithographic inks include soy-based process inks from Kohl and Madden Corporation such as Lithographic Soy ABDT Black MSP-42200-D-STG-5 (tack 16), PMS-185-ABD (OFF-ABD-STD-RED), and MSP-42200-D-STG-S

(OFF-

SOY-ABDT-BLACK). Additional examples of suitable inks include Note Pad Process Black K52-3444-22 commercially available from Central Ink Corporation (Plymouth,

MN).

Printing Process Standard lithographic printing presses can be used. Such presses for air-curable inks include: Didde's (Emporia, Kansas) Webcom and Apollo presses and printing presses available from Stevens International (Fort Worth, Texas). Laboratory presses include the Little Joe Proving Press (Little Joe Color Swatcher, Somerville, NJ). UV Presses include those available from Sanden (Cambridge, Ontario) and Mueller Martini (New York).

This invention is further illustrated by the following examples that are not intended to limit the scope of the invention. In the examples, all parts, ratios and percentages are by weight unless otherwise indicated. The following test methods were used to evaluate and characterize the printing ink with additives compositions produced in the examples. All materials are commercially available, for example from Aldrich Chemicals (Milwaukee, WI), unless otherwise indicated or described.

WO 00/02966 PCT/US99/05309 -7- Examples Test Methods Compounding of Additives with the Inks Additives were added to the base ink and mixed with a wood applicator until uniform. The amount of additive is reported as weight based on the mass of base ink used.

Printing Procedure using a Little Joe Lithographic Proving Press Printing was carried out using a Little Joe Lithographic Proving Press (Little Joe Color Swatcher, Somerville, NJ) according to the following procedure. Brayers and print blankets designed specifically for either air-curable or UV-curable inks were used.

1) A 0.6 cc portion of ink was applied to the 28 x 25 cm stainless steel "inking plate".

2) The ink was then distributed uniformly across the plate via the use of a hand brayer (rubber roller).

3) The brayer, which was saturated with ink, was then rolled once across the x 15 cm "printing plate" in order to transfer ink to the printing plate.

4) The brayer was used, once again, to uniformly redistribute the ink over the inking plate.

Another coat of ink was applied to the printing plate with the ink saturated brayer.

6) The printing "blanket" was rolled across the printing plate and then across the non-adhesive side of Post-it® Note paper (yellow Ashdown paper) in order to make print #1.

7) Print #1 was discarded.

8) Repeating steps 4-6 made prints #2-6.

9) Print #2 was discarded. Prints 3-6 were retained and evaluated.

For air-curable inks, the prints were hung on a wall and allowed to dry for at least 24 hours prior to testing.

For UV-curable inks, each printed sample was immediately attached to a piece of cardboard and passed through an ultraviolet curing unit (Fusion UV Curing WO 00/02966 PCT/US99/05309 -8- Systems, Rockville, MD, F300 ultraviolet lamp system, MC-6R conveyor) at a speed of approximately 15 feet (4.57 meters) per minute.

The proving press was thoroughly cleaned prior to the printing of another sample.

Samples were tested after equilibration in a controlled temperature and humidity room for at least 24 hours.

"Peel Adhesion"of 3M 810 MagicTM Tape to a Substrate This test is similar to TAPPI test method UM-504. A 25 mm wide strip of 3M 810 MagicTM Tape was applied to a substrate. A 2 kg roller was rolled over the tape on the substrate (two passes) in order to adhere the tape to the substrate. One end of the tape was attached to a tensile tester. The tape was peeled from the surface at a 90 degree angle at 12" (30.48 cm)/min. The force in g/l" (2.54 cm) was recorded. The tape was saved and used in the re-adhesion test. The test was carried out on prints 3-6. The average of these tests was reported and is referred to as "peel adhesion" in the Examples.

Re-Adhesion Re-adhesion is a qualitative measure of the amount of adhesive contamination that occurs when 3M 810 MagicTM Tape is peeled from a substrate. In this test, the tape that was used in the Peel Adhesion test is applied to the non-adhesive side of unprinted Postit® Note paper (yellow Ashdown paper). Peel Adhesion was measured and the tape strip was retained for evaluation of ink transfer. The test was carried out on prints 3-6. The average of these tests is reported. The "re-adhesion value" was compared to the Peel Adhesion of fresh 3M 810 MagicTM Tape to the non-adhesive side of unprinted Post-it® Note paper (yellow Ashdown paper) (Table 1, Cl). A value that was similar to that of Cl indicated little or no contamination, whereas a value significantly less than Cl indicated a reduction in adhesion due to contamination of the adhesive with the ink or ink additive.

Ink Transfer Ink transfer is the amount of ink that transfers to the 3M 810 MagicTM Tape that is used in the Peel Adhesion test. The amount of ink transfer was evaluated visually after lamination of the tape to white bond paper. Ratings were made on a scale of 0 to 3 where 0 "no ink transfer", 1 "very little", 2 "some" and 3 "a lot" were used.

WO 00/02966 PCT/US99/05309 -9- Print Quality Print quality was evaluated visually. Ratings of "good" (uniform image of desired color density) and "poor" (non-uniform image or low color density) were used Sheet Removal Force Sheet removal force is the force required to remove the top sheet from a pad of repositionable notes such as Post-it@ Notes. This test was carried out by cutting a one inch (2.54 cm) wide strip across the top sheet of the note pad such that the strip was perpendicular to the adhesive stripe. The adhesive-free end of the strip was attached to a tensile tester. The strip was peeled from the surface at a 90 degree angle at 12" (30.48 cm)/min. The force in g/1" (2.54 cm) was recorded. The test was repeated and the average of the trials was reported.

Examples with Air-Curable Inks The following examples illustrate the improved properties that are obtained with this invention when using air-curable inks.

Comparative Examples C1-C3 Comparative examples C1-C3 showed the detrimental effect of printing a typical air-curable lithographic ink onto a paper coated with a release coating.

In examples C1-C3, peel adhesion of 3M 810 Magic'T Tape to printed and unprinted standard Post-it@ Note paper (coated with adhesive, primer and release coating) was measured. In addition, "re-adhesion" of the 810 MagicTM Tape was measured in order to detect any contamination of the adhesive by the printed surface. Print quality and amount of ink transferred to the Magic'T Tape were noted.

Results (Table 1) for C1-C2 show that peel adhesion increased from 140 to 242 g/1.25" (3.175 cm) when red ink was printed on top of Post-it® Note paper. A peel adhesion value of 317 g/1.25" (3.175 cm) was observed when black ink was used (C3).

Re-adhesion values were significantly lower (117 and 105 g/1.25" (3.175 cm)) than 140 g/1.25" (3.175 cm), which indicates that contamination of the adhesive with ink was significant. Ink transfer was high for both C2 and C3.

Comparative Examples C4-C12 Comparative examples C4-C6 (Table 1) showed that use of typical ink additives such as polyethylene and polytetrafluoroethylene (such as Teflon®) waxes did not improve WO 00/02966 PCT/US99/05309 release and cause adhesive contamination as indicated by the high peel adhesion and low re-adhesion values. Comparative examples C7-C12 showed that stearic acid, fluorine containing monomers, a methacrylate terminated silicone "silicone macromer", and polyethylene glycol monomethacrylate also provided poor results.

JM410-9, 410-8, and 413-3 are typical waxes that are used in lithographic inks.

They were obtained from Kohl Madden Corporation, Minneapolis, MN. JM410-9 is commercially available as "Super Poly 4" from Lawter International, Pleasant, WI.

JM410-8 is commercially available as "CC5510-D" and JM413-3 is commercially available as "PROTECH 200" both materials are available from Carrol Scientific, Countryside, IL.

Stearic Acid was obtained from Aldrich Chemical Co. FluoradTM FX-13, FluoradTM FX-189 and FluoradTM FX-14 were obtained from 3M Company (Industrial Chemical Products Division, St. Paul, MN). CW-750 is polyethylene glycol monomethacrylate 10 moles, EO obtained from Polysciences, Inc., Warrington, PA (Cat.

#16713).

Comparative Examples C13-C14 Comparative examples C13 and C14 showed that using mercaptan-free polydimethylsiloxanes that did not have mercaptan functionality did not provide improved properties. In these examples, polydimethylsiloxane (trimethylsiloxy terminated, CAS No.

[63148-62-9]) of varying molecular weight were evaluated. They were obtained from Huls America as PS041.2 (MW 9430, viscosity 200) and PS042 (MW 17,250, viscosity 500). High peel adhesion, high ink transfer and low re-adhesion values were observed.

Examples 1-10 Examples 1-8 (Table 1) showed that the addition of 1-3 wt of the mercaptopolydiorganosiloxane ("X-22-980" where RI, R 2

R

3

R

4 Rs, and R 6

CH

3 z 3, y 3.5-4.5% of (x Mn 8000, commercially available from Shin-Etsu, Inc.) reduced ink/adhesive interactions, as indicated by the decrease in peel adhesion of MagicTM Tape to the printed ink. Very little adhesive contamination was observed and re-adhesion values were high. Ink transfer was greatly reduced as well and essentially eliminated at X-22-980 levels of WO 00/02966 PCT/US99/05309 -ll- -Il- Examples 9 and 10 showed that poor print quality was obtained if 3.75% or 5% of X-22-980 was used. This indicated that print quality could be affected on certain printing presses if relatively high levels of X-22-980 were used. It should be noted, however, that Didde Webcom lithographic printing presses were found to successfully print ink containing 5% X-22-980 and that an upper limit for X-22-980 level was dependent on press type.

WO 00/02966 PCTIUS99/05309 12 Additi in Ink Table 1 Air-curable Lithographic Inks (Little Joe Proving Press) ye Peel Re-adhesion Adhesion g/2.54 cm 4 g/2.54 cm 147 144 242 117 317 105 none Red Black Black Red Red Red Red Red Red Red Red Red Red Red Red Print 2?uality good good Ink Transfer to MagiCTM Tape 2.5% X-22-980 2.5% X-22-980 2.5% X-22-980 2.5% X-22-980 1% X-22-980 1.75% X-22-980 2% X-22-980 3% X-22-980 3.75% X-22-980 5% X-22-980 2.5% JM410-8 2.5% JM410-9 2.5% JM413-3 56 34 27 24 129 70 45 25 34 259 239 215 243 280 262 300 212 248 226 218 good good good good good good good good poor did not print' good good good good good good good good good good C7 Red 2.5% Stearic Acid C8 Red 2.5% Fluorad FX- 13 C9 Red 2.5% Fluorad FX- 14 CIO Red 2.5% Fluorad FX- 189 CII Red 2.5% Silicone Macromer C12 Red 2.5% CW-750 C13 Red 2.5% PSO41.2 C14 Red 2.5% PS042

I

good 'Ink did not wet out the inking plate or printing plate very well.

WO 00/02966 PCT/US99/05309 13- Inks were obtained from Kohl Madden Printing Ink Corp (Minneapolis, MN). Red ink was labeled PMS-185-ABD (OFF-ABD-STD-RED).

Black Ink was labeled MSP-42200-D-STG-S

(OFF-SOY-ABDT-BLACK).

Examples with UV-Curable Inks The following examples illustrate the improved properties that were obtained with this invention when using UV-curable inks.

Comparative Examples C00-C101 Comparative examples C100-C101 were carried out in a similar fashion as examples C1-C3. The high peel adhesion value in C101 illustrated the detrimental PSA/ink interactions that resulted when printing a typical UV-curable lithographic ink onto a paper coated with a release coating. In contrast to air-curable inks, low ink transfer and low adhesive contamination were observed when using UV-curable inks and proper curing conditions.

Comparative Examples C103-C109 Comparative examples C 107-C 109 (Table 2) showed that typical ink additives, such as polyethylene and polytetrofluoroethylene (such as Telfon®) waxes did not improve release. Comparative examples C103-C106 showed that fluorine-containing monomers and polyethylene glycol monomethacrylate were also ineffective at reducing PSA/ink interactions.

JM410-9, 410-8, and 413-3 are typical waxes that are used in lithographic inks.

They were obtained from Kohl Madden Corporation, Minneapolis, MN. JM410-9 is commercially available as "Super Poly 4" from Lawter International, Pleasant, WI.

JM410-8 is commercially available as "CC5510-D" from Carrol Scientific, Countryside, IL. JM413-3 is commercially available as "PROTECH 200" from Carrol Scientific, Countryside, IL. FluoradTM FX-13, FluoradTM FX-189 and FluoradTM FX-14 were obtained from 3M Company (Industrial Chemical Products Division, St. Paul, MN). CW-750 is polyethylene glycol monomethacrylate 10 moles, EO obtained from Polysciences, Inc., Warrington, PA (Cat. #16713).

Comparative Examples C11O and Cl11 Comparative examples C 110 and C 111 show that the use of mercaptan-free polydimethylsiloxanes that do not have the mercaptan functionality do not provide WO 00/02966 PCTIUS99/05309 -14improved properties. In these examples, polydimethylsiloxane (trimethylsiloxy terminated, CAS No. [63148-62-9]) of varying molecular weight were evaluated. They were obtained from Huls America as PS041.2 (MW 9430, viscosity 200) and PS042 (MW 17,250, viscosity 500). High peel adhesion values were observed which indicate that poor release results when no mercaptan functionality is present.

Examples 100-108 The peel adhesion values for Examples 100-108 (Table 2) show that X-22-980 reduces PSA ink interactions. Peel adhesion decreases as X-22-980 levels are increased from 1 to 6 wt%. The high re-adhesion values indicate that adhesive contamination is low.

Examples 109 and 110 show that poor print quality is obtained if 7.5% or 10% X- 22-980 is used. This indicates that print quality can be affected on certain printing presses if relatively high levels of X-22-980 are used.

Examples 109-116 Examples 109-116 (Table 2) illustrate the positive affects of additives with various amounts of mercapto content and variations in polymer structure. Except for PS927 and PS405, the additives are dimethylsiloxy 3 -mercaptopropylmethylsiloxy copolymers of varying comonomer ratios and molecular weights. PS927 is the homopolymer based on a 3 -mercaptopropylmethylsiloxy repeat unit. PS405 is described as "polydimethylsiloxane, mercaptopropyl t-structure with branch points" by Huls America. The additives are described in detail in Table 3.

WO 00/02966 PCTIUS99/05309 Table 3 Ex. Additive z I 1 Q0*y/ (x y)

R

4 to wt% SH Molecular Relative

R

6 in weight Viscosity fLfllj 11 109 110

III

112 113 114 115 PS850.5 PS850 GP-7 I1- PS849 PS405 PS848 GP-72ss 3 14 3 5-10 3 4

CH

3

CH

3

CH

3

CR

3

NA

CH

3

CH

3 3.6 1 na 0.5 0.38 3 2 NA NA 2 1.4 na 6600 na na na 13,000 100-200 na 200 100-200 na 116 PS927 100 CR 3 26 na na Example 117 Example 117 illustrated that methacrylate-terminated poly(dimethylsi lox ane) of a number average molecular weight of 10,000 (Silicone PLUS HG-10. commercially available from 3M) was an effective additive.

WO 00/02966 PCT/US99/05309 16- Table 2.

Results with UV-curable lithographic inks using Little Joe Proving Press.

Ex. Ink wt additive in ink Peel C100 C101 100 101 102 103 104 105 106 107 none red red red red red red red red red None 1% X-22-980 2% X-22-980 2.5% X-22-980 3% X-22-980 4% X-22-980 5% X-22-980 6% X-22-980 7.5% X-22-980 Adhesion g/l" (2.54 cm) 147 264 105 48 39 32 24 20 16 Re- Print Ink adhesion Quality Transfer to g/1" (2.54 MagicT cm) Tape 144 139 good 0 132 good 0 135 good 0 138 good 0 143 good 0 134 good 0 139 good 0 132 good 0 did not printa did not print a 108 red 10% X-22-980 109 red 2.5% PS850.5 30 137 good 0 110 red 2.5% PS850 34 127 good 0 111 red 2.5% GP-71-SS 49 147 good 0 112 red 2.5% PS849 67 131 good 0 113 red 2.5% PS405 75 131 good 0 114 red 2.5% PS848 133 137 good 0 115 red 2.5% GP-72-SS 178 143 good 0 116 red 2.5% PS927 237 139 good 0 117 red 2.5% Silicone 160 140 good 0 PLUS C103 red 2.5% Fluorad 283 148 good 0 FX-189 C104 red 2.5% Fluorad 274 149 good 0 FX-14 C105 red 2.5% Fluorad 266 146 good 0 FX-13 red 2.5% PEG 260 151 good 0 C107 red 2.5% JM 410-8 251 146 good 0 C108 red 2.5% JM 410-9 254 145 good 0 C109 red 2.5% JM 413-3 228 152 good 0 C110 Red 2.5% PS041.2 220 160 good 0 Clll Red 2.5% PS042 197 160 good 0 Iank did not wet out the inking plate or printing plate very well.

Inks were obtained from Zeller and Gmelin.

Red Ink was labeled UVALUX US423185 LD UN RED.

WO 00/02966 PCT/US99/05309 17- Comparative Example C200 and Examples 130-135 These examples were carried out on a Sanden Varicom printing press equipped with five ultra-violet curing stations. Rolls of adhesive (coated in 1.25 inch (3.175 cm) wide stripes) and release coated (coated over entire paper surface) Post-it® Note paper was routed through the press at 500 feet (152.4 meters) per minute, printed on (printing pattern was a 2 x 9 inch (5.08 x 22.86 cm) rectangle, 100% ink coverage), routed through the UV curing stations (UV light intensity 600 watts/inch (2.54 cm) for each light), cut into 12 x 18 inch (30.48 x 45.72 cm) sheets and stacked. Individual 3 x 5 inch (7.62 x 12.70 cm) Post-it® Note pads were prepared by cutting stacks of 12 inch x 18 inch (30.48 x 45.72 cm) sheets with a guillotine. Samples were tested for peel adhesion, re-adhesion, sheet removal force and ink transfer.

Inks used in these examples were obtained from Zeller Interchem Corporation.

Black ink was labeled UVALUX US4826LD; yellow ink was labeled UVALUX US4825LD. Ink additive "X-22-980" was added to the inks at 1, 3 and 5 weight percent based on the weight of the ink. Black ink was cured with 4 lights whereas the yellow ink was cured with one UV light.

Results in Table 4 show that addition of X-22-980 lowered both peel adhesion and sheet removal force (SRF) for both the black and yellow inks. The improvements were more pronounced with the black inks that illustrated that ink type can be important. The reduction of SRF in repositionable notes was a significant quality improvement as lower SRF values reduce paper deformation (curl) that was caused during removal of the top sheet. Print quality was good for all samples. No ink transfer was observed in these examples.

WO 00/02966 PCT/US99/05309 18- Table 4.

Results with UV-curable lithographic inks using a Sanden press.

Ex. Ink wt Peel

SRF

X-22-980 Adhesion g/1" (2.54 cm) Added g/1" (2.54 cm) C200 None 192 48 130 Black 1 102 131 Black 3 24 13 132 Black 5 13 6 133 Yellow 1 204 37 134 Yellow 3 113 37 135 Yellow 5 71 33 Examples with Products Other Than Repositionable Notes Examples C200-C203 and 201-202 Examples C200-C203 and 201-202 demonstrate that the additives described in this invention can be used to make printed tapes that have good release characteristics. Printing was carried out on the non-adhesive side of several strips of 1" (2.54 cm) wide ScotchTM MagicTM Tape (810 tape, commercially available from 3M company, St. Paul, MN) in a similar manner as Cl and C100. The several strips of ScotchTM MagicTM Tape were laminated next to each other onto bond paper prior to printing in order to create a large area for printing. Results in Table 5 show that addition of 2.5% of X-22-980 results in low ink transfer and low peel adhesion for both UV and air-curable inks.

WO 00/02966 PCT/US99/05309 -19- Table Results when printing on the non-adhesive side of Scotch

T

Magic'T Tape.

Ex. Ink Wt Peel Re- Print Ink X-22-980 Adhesion adhesion Quality Transfer In ink g/l" (2.54 g/1" (2.54 to cm) cm) MagicTM Tape C200 none 121 good C201 UV 0 273 159 good 0 201 UV 2.5 21 133 good 0 C202 Air-curable 0 0 good 3+ 202 Air-curable 2.5 24 133 good 1 the value was very low due to complete ink transfer during the peel adhesion test.

UV-curable ink UVALUX US423185 LD UN RED obtained from Zeller and Gmelin. Air-curable ink PMS-185-ABD (OFF-ABD-STD-RED) obtained from Kohl and Madden Corp.

Examples C210-C213 and 211-212 Examples C210-C213 and 211-212 demonstrate that the additives described in this invention can be used to make printed labels that have good release characteristics.

Printing was carried out on the non-adhesive side of 1" x 2 5/8" (2.54 x 6.66 cm) address labels that were on an 8.5" x 11" (21.59 x 2.54 cm) liner in a similar manner as Cl and C100. The labels are commercially available as "Laser Labels" product #5160 from Avery Dennison Office Products (Diamond Bar, CA). Results in Table 6 show that addition of 2.5% of X-22-980 results in low ink transfer and low peel adhesion for both UV and aircurable inks.

WO 00/02966 PCT/US99/05309 Table 6.

Results when printing on the non-adhesive side of Avery Laser Labels.

Ex. Ink Wt Peel Re- Print Ink X-22-980 Adhesion adhesion Quality Transfer to In ink g/1" (2.54 g/l" (2.54 MagicM cm) cm) Tape C210 none NA 343 133 NA NA C211 UV 0 310 147 good 0 211 UV 2.5 45 132 good 0 C212 Air-curable 0 287 139 good 0 212 Air-curable 2.5 62 159 good 0 0S@O 0

S..

O

OS

0S@@

S

0 0O55 0 S. 0 5 0 0@

S

S

S

S

UV-curable ink UVALUX US423185 LD UN RED obtained from Zeller and 5 Gmelin. Air-curable ink PMS-185-ABD (OFF-ABD-STD-RED) obtained from Kohl and Madden Corp.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative 10 embodiments set forth hereinabove. All publications and patents are incorporated herein by reference to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as an acknowledgment or any form of suggestion that prior art forms part of the common general knowledge in Australia.

Claims (9)

1. A releasable lithographic ink composition comprising an air-curable printing ink and mercaptopolydiorganosiloxane copolymer additive having the following general formula: R4 Re RI R2R3Si- si OSOSi i-S OSiRRgR I X /y R( CH 2 SH wherein: y ranges from 0.5 to about 80% of (x y); Ri, R 2 and are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R 4 R 5 and R 6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, S 15 hydroxyl, hydrogen, fluoroalkyl; z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater.

2. The releasable lithographic ink composition according to claim 1 wherein y 20 ranges from 1-20% of (x y).

3. The releasable lithographic ink composition according to claim 1 wherein y ranges from 3.5 14% of (x y).

4. The releasable lithographic ink composition according to claim 1 wherein the molecular weight of the additive is in the range from about 1000 to about 200,000. WO 00/02966 PCTIUS99/05309 -22- The releasable lithographic ink composition according to claim 1 wherein the additive is present in the composition in amounts ranging from 0.1 to 15 by weight of the ink.

6. The releasable lithographic ink composition according to claim 1 wherein RI, R2, R 3 R 4 Rs, and R 6 CH 3 y 3.5 to 4.5 of (x z 3 and the number average molecular weight (Mn) 8000.

7. An adhesive coated article comprising a backing substrate having a front and back surface, a layer of pressure sensitive adhesive on at least one portion of the back surface of the backing substrate, and indicia on the front surface of the backing substrate, wherein the indicia is printed using a releasable lithographic ink comprising (a) an ultraviolet curable printing ink or an air-curable printing ink and (b) mercaptopolydiorganosiloxane copolymer additive having the following general formula: R4 R6 RiR 2 R 3 OSOSi-- OSiR 1 R 2 R 3 R s (CH 2 SH wherein: y ranges from 0.5 to about 80% of (x y); RI, R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R4, Rs, and R 6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater. WO 00/02966 PCT/US99/05309 -23-

8. The adhesive coated article according to claim 7 wherein the molecular weight of the additive is in the range from about 1000 to about 200,000.

9. The adhesive coated article according to claim 7 wherein the additive is present in the composition in amounts ranging from 0.1 to 15 by weight of the ink. The adhesive coated article according to claim 7 wherein R, R, R, R, R, and R 6 CH 3 y 3.5 to 4.5 of (x z 3 and the number average molecular weight

8000. 11, A pad assembly comprising a multiplicity of flexible sheets each having similarly sized body portion that have pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when a sheet is removed from the pad assembly, the sheet is easily removable and the lithographic ink is not transferred from the front of the sheet of a first sheet to the back of the sheet of second sheet overlaying the fi'st sheet, S.wherein the lithographic ink comprises an ultraviolet curable printing ink or an air- curable printing ink and mercaptopolydiorganosiloxane copolymer having the following general formula: S 20 R4 R6 S R 2 RR 3 Si- OSi /x OS OSiRiR2R3 Rs CH 2 I SH SH .e wherein: y ranges from 0.5 to about 80% of(x y); oo *o WO 00/02966 PCT/US99/05309 -24- R 1 R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R 4 Rs, and R1 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from 1 to about 16; x and y are integers of at least one and the sum of x y is an integer of 10 or greater. 12. The pad assembly according to claim 11 wherein the molecular weight of the additive is in the rage from about 1000 to about 200,000. 13. The pad assembly according to claim 11 wherein the additive is present in the composition in amounts ranging from 0.1 to 15% by weight of the ink. 14. The pad assembly according to claim 11 wherein RI, R 2 R 3 R 4 Rs, and R CH 3 y 3.5 to 4.5% of(x z 3 and the number average molecular weight 8000. 15. A roll of adhesive coated material comprising a substrate having at least one portion that has a pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when the material is unrolled from the roll, the material is easily *removable and the lithographic ink is not transferred from the front of the substrate, wherein the lithographic ink comprises an ultraviolet curable printing ink or an air- curable printing ink and mercaptopolydiorganosiloxane copolymer having the following general formula: -0 12 WO 00/02966 I CTIUS99/05309 RIR2R3Si .{oS t0oSi.); OSiRIRR3 R 5 CH 2 SH wherein: y ranges from 0.5 to about 80% of (x y); R, R 2 and R 3 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl, divalent linking groups; R 4 Rs, and R6 are monovalent moieties that can independently be the same or different and are selected from the group consisting of alkyl, aryl, alkaryl, alkoxy, alkylamino, hydroxyl, hydrogen, fluoroalkyl; z can range from I to about 16; x and y are integers of at least one and the sum ofx y is an integer of 10 or greater. 16. A releasable lithographic ink composition comprising an ultraviolet- curable printing ink and a methacrylate-terminated poly(dimethylsiloxane) having a number average molecular weight in the range of 5,000 to 50,000. 17. A pad assembly comprising a multiplicity of flexible sheets each having similarly sized body portion that have pressure sensitive adhesive on a back surface and 20 indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when a sheet is removed from the pad assembly, the sheet is easily removable and the lithographic ink is not transferred from the front of the sheet of a first sheet to the back of the sheet of second sheet overlaying the first sheet, wherein the lithographic ink comprises an ultraviolet curable printing ink and a methacrylate-terminated poly(dimethylsiloxane) having a number average molecular weight in the range of 5,000 to 50,000. WO 00/02966 PCT/US99/05309 -26- 18. A roll of adhesive coated material comprising a substrate having at least one portion that has a pressure sensitive adhesive on a back surface and indicia printed on a front surface, wherein the indicia is printed with lithographic inks having release characteristics, such that when the material is unrolled from the roll, the material is easily removable and the lithographic ink is not transferred from the front of the substrate, wherein the lithographic ink comprises an ultraviolet curable printing ink or an air- curable printing ink and a methacrylate-terminated poly(dimethylsiloxane) having a number average molecular weight in the range of 5,000 to 50,000. 19. Additives for printing inks that provide a low surface energy, or articlesl treated with such inks, substantially as herein described with reference to the accompanying Examples. DATED THIS 22nd day of April, 2002. MINNESOTA MINING AND MANUFACTURING COMPANY By Its Patent Attorneys f DAVIES COLLISON CAVE 0* 0 oS 0 0. 0