WO2008094863A1

WO2008094863A1 - Lithographic printing ink

Info

Publication number: WO2008094863A1
Application number: PCT/US2008/052202
Authority: WO
Inventors: Mathew C. Mathew; David Anthony Biro
Original assignee: Sun Chemical Corp
Current assignee: Sun Chemical Corp
Priority date: 2007-01-29
Filing date: 2008-01-28
Publication date: 2008-08-07
Anticipated expiration: 2009-07-29

Abstract

When used as a component in lithographic inks, a gel containing a hydroxyl- containing hard organic resin and an alkoxylated (meth)acrylate provides improved lithographic performance. The inks provide enhanced emulsion capacity, print transfer and reduced misting. The lithographic ink generally contains colorant, vehicle and the gel, and may contain other conventional additives.

Description

LITHOGRAPHIC PRINTING INK

BACKGROUND OF THE INVENTION

Printing inks generally include one or more vehicles and one or more colorants as principal components. The printing ink vehicles must meet a number of performance requirements that include both requirements related to the particular printing process being employed, such as suitable consistency and tack for sharp, clean images, suitable length to avoid fly or mist, or proper drying characteristics, and requirements related to the printed image, such as gloss, chemical resistance, durability or color. In general, the ink vehicles include one or more materials such as vegetable oils or fatty acids, resins, and polymers that contribute to the end product properties, and may include other components such as organic solvents, water, rheology modifiers, and so on, that may affect body, tack, or drying characteristics.

In lithographic printing, use is made of plates having hydrophobic image areas and hydrophilic non-image areas. In a typical lithographic printing process, the plate cylinder first comes in contact with dampening rollers that transfer an aqueous fountain formulation to the hydrophilic non-image areas of the plate. Typical damping processes utilizing a water or aqueous fountain solution are described in U.S. Pat. Nos. 3,877,372; 4,278,467; and 4,854,969. Upon damping, water forms a film on the hydrophilic areas (the non-image areas) of the printing plate, but contracts into tiny droplets on the oleophilic areas (the image areas) of the plate. The dampened plate contacts an inking roller to apply an the oil based ink. When the inked roller containing the oil based ink is passed over the damped plate, it is unable to ink the areas covered by the water film (the non-image areas), but will emulsify the droplets on the water repellant areas (the image areas), causing such area to accept the ink. The inked plate is then contacted with the substrate to be printed in order to transfer the desired image to that substrate. In the process of "offset lithography," the inked image on the plate does not directly print onto the paper or other substrate, but is first "offset" onto a rubber blanket, and then transferred from the blanket onto the paper substrate.

The lithographic printing process has always presented unique challenges to ink formulators, since such process utilizes a planographic printing plate in which the image and non-image areas are in the same plane on the image carrier, and two fluids are concurrently utilized to insure that ink adheres only to the image area, and not to the non-image area. Establishing and maintaining a correct ink/water balance during the printing process is critical, and requires a high level of skill.

A large variety of lithographic printing inks are known. The requisite properties for such lithographic inks include sufficient adherence to the image areas, non- adherence to the non-image areas, and, in addition to these obviously fundamental properties, suitable levels of properties which relate to flow, interfacial behavior, and drying. Especially in lithographic printing, the greasy ink is required to maintain an adequate balance between the ink-water interfacial tension and the surface tensions of both phases, because otherwise there will occur gradual enlargement or, conversely, disappearance of the image areas, emulsification of the ink, and a phenomenon of scumming during the printing of thousands or tens of thousands of copies with the alternate feeding of a greasy ink and water which is repeated for each copy.

The lithographic ink generally contains colorant and a vehicle, and may include one or more additives such as, for example, plasticizers, stabilizers, driers, thickeners, dispersants, and fillers.

A lithographic printing process using UV/EB curable inks is not as robust as the process using conventional sheetfed and heat set lithographic inks. As a result, there is a desire for materials which will enhance the viscosity and emulsified ink characteristics of UV/EB inks closer to that of a heatset or sheetfed ink. It has now been found that a gel-like additive such as a gel containing cellulose acetate butyrate or polyvinyl butyral or related materials is useful for that purpose. Surprisingly, the use of a relatively small amount of the gel-like additive in the ink can produce a significant change in the ink's press performance, rheology and/or emulsified ink viscosity. It can also be used in conventional sheetfed and heat set lithographic inks.

Cellulose acetate butyrate resins are known as dispersing materials for many ink and coating applications, particularly for color concentrates. Cellulose ester resins are also used in the furniture industry in base coat formulations as they provide good holdout and adhere well to many surfaces. CAB resins are used with urea formaldehyde resins, polyurethanes and acrylics as seal coatings. Paper coatings derived from alcohol soluble solutions of CAB and urea formaldehyde resins yield films that exhibit scuff resistance, flexibility and ultraviolet light stabilization. Cellulose ester resins are noted to be useful in printing inks. Eastman Chemicals, technical data sheet, CAB-553-0.4 and CAP-482-0.5. The use of the CAB resin in UV/EB coating formulations has been described by Nowak, Radiation Curing (1982), 9(3), 29-36, in the context of its solubility with an acrylate monomer and other solvents. Japanese Patent 05-345874, (1993) describes an the use of a low molecular weight acylation cellulose of a non-film forming nature in an actinically cured ink containing metal powders for the purpose of increasing the storage time stability of the ink by retarding gel formation. Kamen, WO 03/006562 Al, describes UV cured UV blocking ink compositions which are silk screen applied to transparent substrates for the purpose of blocking UV light transmitted from 325 to about 415 nanometers. While a solution of CAB is present in the working examples, the reason for its presence is not described. Walter et al. (DE 4308766) describe a cationically cured UV flexographic ink wherein the CAB resin is used as a polyfunctional hydroxyl material which will react with the cycloaliphatic epoxies in the ink. SUMMARY OF THE INVENTION

A gel-like additive is used as a component in lithographic inks to provide improved lithographic performance as reflected in the change in emulsion capacity (%EC) and frequently also by the lithographic performance index (LPI). The additive contains a hydroxyl-containing organic hard resin which is soluble in an alkoxylated (meth) aery late, and the alkoxylated (meth) aery late. The inks provide enhanced print transfer and reduced misting. The lithographic ink generally contains colorant, vehicle and the gel-like additive, and may contain other conventional additives.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the effect on CAB on neat and emulsified ink viscosity. Fig. 2 shows the emulsion capacity of ink with and without CAB.

DESCRIPTION OF THE INVENTION

In accordance with the invention, the lithographic ink generally contains colorant, vehicle and the gel, and may contain other conventional additives. The vehicle in a preferred embodiment is actinic, ultraviolet or energy beam curable.

The emulsion capacity of the ink has a large impact on the press behavior and the print result. The higher the emulsion capacity, the better is the transfer on the press and a wider amount of water can be used. If the emulsion capacity of the ink is too low, it can lead to unstable ink behavior making regular press control necessary. It has been observed that whether or not the gel causes a significant increase in ink viscosity, it surprisingly increases the ability of the ink to tolerate ("fight") water as reflected in a larger emulsion capacity. For example, Figure 2 shows the gel containing ink tolerates more water than its base ink. In general, the inks of the invention exhibit a change in emulsion capacity (relative to the base ink) of at least about five (5) percentage points.

The inks of the invention generally have a LPI of at least 0.5, preferably at least 0.6, and most preferably at least 0.8. Preferably, the LPI is not greater than 1. The LPI is dependent on the hydroxyl content of the hydroxyl-containing organic resin used to make the gel and the higher the content, the higher the LPI and the ink viscosity. Also, the presence of the gel also decreases the misting of the ink, which allows for wider operating conditions on a printing press.

The gel is a combination of hydroxyl-containing organic resin which is soluble in an alkoxylated (meth)acrylate at low concentration and forms a gel as the concentration is increased, and which, with the alkoxylated (meth) aery late monomer adds hardness to the ink. The resin provides an element with which reactive monomers and oligomers in the ink can cross-link or entangle. The relative increase in cross-link density results in the increased hardness.

In one preferred embodiment, a cellulose ester is employed. In general, the cellulose ester will usually have a molecular weight of about 10,000 to 100,000, and preferably about 12,000 to 70,000, and a hydroxyl content of at least about 2%, more preferably at least about 2.5% and most preferably at least about 4%. Examples of usable cellulose ester resins include commercial organic cellulose esters of carboxylic acids, such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate and the like. The use of cellulose acetate butyrate (CAB) is preferable.

In another preferred embodiment, the hydroxyl-containing organic resin is polyvinyl butyral. Nevertheless, other hydroxyl-containing organic resin can be used as long as they are solid at room temperature, soluble in the alkoxylated (meth) aery late, form a gel when combined with the alkoxylated (meth)acrylate, and when the gel is subjected to actinic radiation, form a thermoplastic or thermosetting polymer that is substantially void of (meth)acrylate functionality.

The (meth)acrylate monomer which is alkoxylated is not limited. A preferred class is the (meth)acrylic esters of polyols, including but not limited to, materials such as trimethylolpropane triacrylate (TMPTA); trimethylolpropane trimethacrylate; ethoxylated trimethylolpropane triacrylate; glyceryl propoxy triacrylate; propylene glycol diacrylate; ethylene glycol diacrylate; ethylene glycol dimethacrylate; ethylene glycol diacrylate; tetraethylene glycol diacrylate; triethylene glycol dimethacrylate; tripropylene glycol dimethacrylate; polypropylene glycol diacrylate; polyethylene glycol diacrylate; butanediol diacrylate; butanediol dimethacrylate; pentaerythritol triacrylate; pentaerythritol tetraacrylate; ethoxylated bisphenol A diacrylate; hexane diol diacrylate; dipentaerythritol monohydroxypentaacrylate; neopentyl glycol diacrylate; neopentyl glycol dimethacrylate; tris(2-hydroxyethyl)isocyanurate triacrylate and the like. Of these, trimethylolpropane triacrylate is preferred. Each alkoxy unit generally contains about 1 to 10 carbon atoms, preferably about 2-3 carbon atoms, and is present in an amount of about 1 to 15 mole percent, preferably about 2 to 9 mole percent, and most preferably about 3 to 6 mole percent. Ethoxylated and propoxylated trimethylolpropane triacrylate (EOTMPTA and POTMPTA) containing 3 or 6 ethoxy and/or propoxy units are preferred. The alkoxylated monomers are commercially available.

The gel is prepared by dissolving the hydroxyl-containing organic resin in the alkoxylated monomer in a concentration which forms a gel rather than a solution. In general, the resin will be about 5 to 25% of the combination, and preferably about 8 to 15%, although other amount can be used. The amount necessary for gel formation will vary depending on hydroxyl concentration. Speed of dissolution can be increased by employing an elevated temperature of, for instance, about 90 to 125⁰C, preferably about 100-110⁰C, and a gel will form when the solution is returned to ambient temperature. If elevated temperature is employed, the use of a polymerization inhibitor is advisable.

The gel is present in the lithographic ink in an effective amount to realize the improved properties. This is usually an amount sufficient to have the hydroxyl- containing organic resin concentration of about 0.1 to 2.5% in the ink, preferably about 0.5-1.2% of the ink and most preferably about 0.7-1% of the ink. As apparent, the greater is the concentration of the hydroxyl-containing organic resin in the gel, the lower is the amount of gel in the ink necessary to achieve the same properties.

The balance of the ink is the convention lithographic ink formulation of colorant, vehicle and additives. The colorant may any pigment that can be employed in lithographic printing inks of the prior art. It may be organic or inorganic and may be a dye or pigment. Typical examples of useable colorants include, but are not limited to, inorganic pigments, such as Pigment White 6 (Titanium Dioxide), Pigment Black 7 (carbon black), Pigment Black 11 (Black Iron Oxide), Pigment Red 101 (Red Iron Oxide) and Pigment Yellow 42 (Yellow Iron Oxide), and organic pigments such as Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 37, Pigment Yellow 63, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 106, Pigment Yellow 114, Pigment Yellow 121, Pigment 26Yellow 126, Pigment Yellow 136, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 112, Pigment Red 146, Pigment Red 170, Pigment Red 196, Pigment Red 210, Pigment Red 238, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Violet 23 and the like. The major component of a lithographic ink composition is known as a lithographic ink varnish or vehicle, which comprises a resin and an oil component. The oil component primarily acts as a carrier for the resin component, although it has other actions as well, such as an effect on the drying time of the ink composition. The resin component binds the various ink components together and to the substrate once the ink is dried, and also imparts other properties, such as hardness, wear resistance, and drying time. The lithographic ink varnishes of the invention are dried by radiation curing, such as UV or electron beam. The resins and oils in the oleoresinous varnish component of the present invention are well known and may include any natural and/or synthetic resins and oils appropriate for use in lithographic inks. A detailed description of the ink varnish will therefore not be set forth since numerous publications are available that teach in detail the equipment, procedures, and materials used in a lithography printing operation. Two such publications are The Printing Ink Manual, 4th Edition (1988), published by Van Nostrand Reinhold (International) Co. Ltd., and The Lithographers Manual, 7th Edition (1983), published by The Graphics Arts Technical Foundation, Inc., both of which are incorporated herein by reference.

The preferred vehicles contain oligomers or monomers, or both, at least one of which contains α,(3-ethylenic unsaturation. The oligomers may be members of any of the acrylate, polyester, urethane or other systems. The preferred oligomers in accordance with the present invention, however, are acrylate formulations. Examples include the acrylate esters and specifically epoxy acrylates, polyester acrylates, unsaturated polyesters and urethane acrylates. The monomers include tripropylene glycol diacrylate (TPGDA), n-vinyl pyrollidone, trimethylol propane triacrylate (TMPTA) and the like. If ultraviolet (UV) radiation curing is to be used, a photoinitiator is required in the varnish. If electron beam (EB) curing is utilized, photoinitiators are not needed. The vehicle typically includes a variety of organic components such as one or more organic solvents, monomers, oligomers, crosslinking agents, and the like, all selected for their contribution to application-specific ink properties.

The ink composition may also contain additional additives such as but are not limited to, waxes, for example, Jon Wax 26, Jon Wax 120 (available from S. C. Johnson & Sons, Inc., Racine, Wis., U.S.A.), or Van Wax 35 (available from Vantage, Garfield, N.J., U.S.A.); modifiers such as, for example, defoamers such as Resydrol (available from Vantage); Carbowet 990 (available from Vantage); Aerosol (available from Mclntyre, Chicago, 111., U.S.A.); alcohols such as N-propyl alcohol, isopropyl alcohol, propylene glycol, ethylene glycol monobutyl ether, or ethylene glycol; biocides; talc; silica; pH stabilizers; fatty acid esters; gellants; driers; dispersants; and thickeners such as acrysol RM-825 (available from Rohm and Haas, Philadelphia, Pa., U.S.A.).

In order to further illustrate the invention, several non-limiting examples are set forth below. In these, and throughout this specification and claims, all parts and percentages are by weight and all temperatures are in degrees Centigrade, unless otherwise indicated.

Example 1

Eight parts of CAB (molecular weight Mn = 14,313; hydroxyl content 4.8%), 91 parts of EOTMPTA and 1 part of polymerization inhibitor (equal parts of p-methoxy phenol and alumina nitrosohydroxy amine) was placed in a container under constant agitation. The temperature was slowly raised to 100-110⁰C, and held within this range until all the CAB had dissolved in the EOTMPTA. The resulting solution was allowed to cool to room temperature to thereby realize a gel.

The resulting gel was used to prepare inks, described below in Examples 2-5, in order to compare the performance of basic ink formulations with and without the gel. Example 2

A lithographic ink was produced by milling the following on a three roll mill:

Rubine Base 34.0 Color concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin Solution 28.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0 Photo initiator 4.5 Photomer 4028 13.0 Epoxy Acrylate EOTMPTA 4.0 Monomer

Talc 3.5 PE Wax 1.0 Silica 1.0 Claytone HY LO Clay 100 Example 3

A lithographic ink was produced by milling the following on a three roll mill:

Rubine Base 34.0 Color concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 13.0 Epoxy Acrylate

Example 1 gel 10.0

Talc 3.5

PE Wax 1.0

Silica 1.0

Claytone HY LLOO Clay

100 Example 4

A lithographic ink was produced by milling the following on a three roll mill:

Rubine Base 34.0 Color Concentrate Ebecryl 657 2.0 Polyester acrylate Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 13.0 Epoxy Acrylate

EOTMPTA 10.0 Monomer

Talc 3.5

PE Wax 1.0

Silica 1.0

Claytone HY LO Clay 100.00

Example 5

A lithographic ink was produced by milling the follov

Rubine Base 34.0 Color Concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 10.0 Epoxy Acrylate

Epotuf 91275-00 3.0 Epoxy Acrylate

Example 1 gel 10.0

Talc 3.5

PE Wax 1.0 Silica 1.0

Claytone HY LO Clay

100

Example 6

The inks of Examples 2-4 were evaluated for lithographic performance indicator (LPI), emulsion capacity (EC%), tack, misting and gloss as follows.

LPI

To establishing the LPI criteria of the rheological performance of the ink of the present invention, 10 parts of the ink is emulsified with 1 part of water or any commercially available fountain solution on a DAC 150 FVZ speed mixer for 1 minute at 3000 rpm. Viscosities are recorded on a stress-controlled rheometer, model ARlOOO from TA instruments using a 2 cm 0.5° cone. The stress is ramped in intervals from 0.01 to 10000 Pa and the viscosity is recorded versus stress. For each stress value, the relative viscosity is calculated by dividing the viscosity of the emulsified ink by the viscosity of the neat ink.

Emulsion Capacity

The emulsion capacity of the ink when water is emulsified in it is measured using a Novamatics HS Lithotronic FI Emulsification Tester which measures the torque needed at given rpm speeds.

The measurement procedure consists of two phases: preconditioning and measurement. During preconditioning, the sample is sheared at a high constant speed (2000 rpm) and heated to 40° C. The end of preconditioning phase is when the sample has reached a stable viscosity. At that moment, controlled metering (4 grams/minute) of fountain solution into the ink is started. The changes of applied torque (and hence viscosity) versus time and emulsion capacity are recorded. When the maximum emulsion capacity is reached, a drop in torque is usually experienced because of the free water in the container. The emulsion capacity is expressed as the percentage of water delivered per weight of the ink.

As used herein, "change in emulsion capacity" is the numeric change (number of percentage points) in emulsion capacity of the gel-containing ink relative to its base ink (i.e., essentially the same formulation without the gel but possibly containing alkoxylated (meth)acrylate).

Tack

Tack is measured on Thwing-Albert model 106 electronic inkometer at 1200 RPM, 90° F for 1 minute.

Misting

Misting is measured by quantifying the amount of ink mist deposited on a sheet of paper supported behind a Thwing-Albert model 106 electronic inkometer at 1200 rpm, 90° F (about 32 ° C) for 2 minutes. The results are reported on a scale of 1-5, with 1 being the best result (no misting), and the ink of Example 2 arbitrarily deemed a median (3) result.

Gloss

Gloss is measured using a Byk TRI Micro gloss meter at 60°. The results of the evaluation are set forward in the following table:

The effect of the gel on ink viscosity is shown in Figure 1. The neat ink of Example 2 and the ink with CAB of Example 3 differ in the presence or absence of the gel. Figure 1 shows the neat ink with the gel had a higher viscosity than the ink without the gel at all shear rates applied. When emulsified, the ink without gel exhibits much more of a thixotropic behavior.

Two commercially available energy curable lithographic inks, namely ArrowStar 7700 (Flint Ink) and Sicura (Sicpa) had LPIs of 0.42 and 0.45, respectively.

Example 7

A commercially available UV magenta ink and the same formulation in which the gel of Example 1 replaced monomer in an amount such that the CAB content was 0.8% of the ink were tested for emulsion capacity. The results are shown in Figure 2. It is seen that ink with the gel is much more tolerant of the water content of the damping composition, thereby giving the printer more freedom in the selection and use of such damping compositions.

Example 8 Example 1 is repeated using a CAB having a molecular weight (Mn) of 16,000 and a hydroxyl content of 1.5% and then the ink formulation of Example 3 was formulated substituting this gel for the gel of Example 1.

Example 9

Example 1 is repeated using a CAB having a molecular weight (Mn) of 30,000 and a hydroxyl content of 1.5% and then the ink formulation of Example 3 was formulated substituting this gel for the gel of Example 1.

Example 10

Example 1 is repeated using a cellulose acetate propionate (CAP) having a hydroxyl value of 2.6% and a melt point of 188 - 210⁰C . A lithographic ink was produced by milling the following on a three roll mill:

Rubine Base 34.0 Color concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 10.0 Epoxy Acrylate

Ebecryl 3700 3.0 Epoxy acrylate

Gel 10.0

Talc 3.0

PE Wax 1.0

Silica 1.0

Claytone HY LO Clay

100 Example 11

For the purpose of comparison to Example 10 above, a lithographic ink was produced by milling the following on a three roll mill:

Rubine Base 34.0 Color concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 10.0 Epoxy Acrylate

Ebecryl 3700 3.0 Epoxy acrylate

EOTMPTA 10.0 monomer

Talc 3.0

PE Wax 1.0

Silica 1.0

Claytone HY LO Clay

100

The results of the evaluation are set forward in the following table:

The results show that the cellulose acetate propionate (CAP) containing gel improved the lithographic performance of the UV ink. Example 12

A lithographic ink was produced by milling the following on a three roll mill:

Cyan Base 35.0 Color concentrate Ebecryl 657 5.5 Polyester acrylate

Resin Solution 17.0 Hydrocarbon resin in TMPTA Soya Based Additive 8.0 Photo initiator 4.2

Photomer 4028 9.8 Epoxy Acrylate

Ebecryl 3700 4.0 Epoxy Acrylate

Example 1 gel 10.0 gel Talc 3.5

PE Wax 1.0

Silica 1.0

Claytone HY ZO Clay

100

Example 13

For the purpose of comparison with the ink of Example 12, a lithographic ink was produced by milling the following on a three roll mill:

Cyan Base 35.0 Color concentrate

Ebecryl 657 5.5 Polyester acrylate

Resin Solution 17.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photoinitiator 4.2

Photomer 4028 9.8 Epoxy Acrylate

Ebecryl 3700 4.0 Epoxy Acrylate

EOTMPTA 10.0 monomer

Talc 3.5 PE Wax 1.0

Silica 1.0 Claytone HY ZO Clay 100 The results of the evaluation are set forward in the following table:

The Example 12 ink (with the gel) exhibited better properties than the ink without the gel.

Two commercially available energy curable lithographic inks, namely ArrowStar 7700 (Flint Ink) and Sicura (Sicpa) had LPIs of 0.36 and 0.42, respectively.

Example 14

Ten parts of polyvinyl butyral (Pioloform® BL 18), 90 parts of EOTMPTA and 1 part of polymerization inhibitor (equal parts of p-methoxyphenol and alumina nitrosohydroxy amine) was placed in a container under constant agitation. The temperature was slowly raised to 100-110⁰C, and held within this range until all the PVB had dissolved in the EOTMPTA. The resulting solution was allowed to cool to room temperature to thereby realize a gel. A lithographic ink was produced using this gel by milling the following on a three roll mill:

Rubine Base 34.0 Color concentrate

Ebecryl 657 2.0 Polyester acrylate

Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0 Photo initiator 4.5

Photomer 4028 13.0 Epoxy Acrylate

PVB Gel 10.0

Talc 3.5

PE Wax 1.0

Silica 1.0

Claytone HY LO Clay

100

This ink had an LPI of 0.75 and a positive change in emulsion capacity value as indicated by an increase of low shear viscosity of the emulsified ink (483 Pa. sec) relative to the base ink of Example 2 (162.7 Pa. sec).

Example 15

Thirty-Two parts of styrene allyl alcohol copolymer (SAA-100™; 6.2% OH content), 68 parts of EOTMPTA and 1 part of polymerization inhibitor (equal parts of p- methoxy phenol and alumina nitrosohydroxy amine) was placed in a container under constant agitation. The temperature was slowly raised to 100-110⁰C, and held within this range until all the SAA had dissolved in the EOTMPTA. The resulting solution was allowed to cool to room temperature to thereby realize a gel.

A lithographic ink was produced using this gel by milling the following on a three roll mill: Rubine Base 34.0 Color concentrate Ebecryl 657 2.0 Polyester acrylate Resin Solution 22.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.5

Photomer 4028 13.0 Epoxy Acrylate

SAA Gel 10.0

Talc 3.5

PE Wax 1.0

Silica 1.0

Claytone HY LO Clay

100

The ink had a LPI of 0.82 and a low shear viscosity of the emulsified ink of 356 Pa. sec.

Example 16

A lithographic ink was produced by milling the following on a three roll mill:

Cyan Base 35.0 Color concentrate Ebecryl 657 5.5 Polyester acrylate Resin Solution 25.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.2

Photomer 4028 13.8 Epoxy Acrylate

TMPTA 2.0 Monomer

Talc 3.0

PE Wax 0.5

Silica 1.0

Claytone HY ZO Clay

100 The ink had a LPI of 0.62 and a positive change in emulsion capacity value as indicated by an increase of low shear viscosity of the emulsified ink (437 Pa. sec) relative to its base ink.

Example 17

A lithographic ink was produced by milling the following on a three roll mill:

Cyan Base 35.0 Color concentrate Ebecryl 657 5.5 Polyester acrylate Resin Solution 17.0 Hydrocarbon resin in TMPTA Soya Based Additive 8.0 Photo initiator 4.2 Photomer 4028 9.8 Epoxy Acrylate Ebecryl 3700 4.0 Epoxy Acrylate PVB Gel 10.0 Talc 3.5 PE Wax 1.0 Silica 1.0 Claytone HY ZO Clay 100

The ink had a LPI of 0.62 and a positive change in emulsion capacity value as indicated by an increase of low shear viscosity of the emulsified ink (695.1 Pa. sec) relative to its base ink.

Example 18

A lithographic ink was produced by milling the following on a three roll mill:

Cyan Base 35.0 Color concentrate

Ebecryl 657 5.5 Polyester acrylate Resin Solution 17.0 Hydrocarbon resin in TMPTA

Soya Based Additive 8.0

Photo initiator 4.2 Photomer 4028 9.8 Epoxy Aery late Ebecryl 3700 4.0 Epoxy Acrylate SAA Gel 10.0 Talc 3.5 PE Wax 1.0 Silica 1.0 Claytone HY ZO Clay 100

The ink had a LPI of 0.71 and a positive change in emulsion capacity value as indicated by an increase of low shear viscosity of the emulsified ink (240.9 Pa. sec) relative to its base ink.

Various changes and medications can be made without departing from the spirit and scope of this invention. The embodiments herein were set forth in order to illustrate the invention and are not intended to limit it.

Claims

What is claimed is:

1. A lithographic ink comprising colorant, vehicle and gel, wherein the gel comprises a hydroxyl-containing hard organic resin which is soluble in an alkoxylated (meth) aery late monomer cellulose ester and an alkoxylated (meth)acrylate monomer, and the gel has a change in emulsion capacity value of at least about five percentage points.

2. The ink of claim 1 wherein the hydroxyl-containing hard resin is a cellulose ester.

3. The ink of claim 2 wherein the amount of cellulose ester is about 0.1 to 2.5% in the ink.

4. The ink of claim 1 wherein the amount of cellulose ester is about 0.7 to 1% of the ink.

5. The ink of claim 1 wherein the hydroxyl-containing hard resin is polyvinyl butyral.

6. The ink of claim 1 wherein the hydroxyl-containing hard resin is a hydroxyl- containing styrene allyl alcohol copolymer.

7. The ink of claim 1 wherein the alkoxylated (meth)acrylate monomer is an acrylate monomer containing about 3 to 15 mole percent alkoxy groups.

8. The ink of claim 7 wherein each alkoxy group contains about 2 to 10 carbon atoms.

9. The ink of claim 8 wherein the alkoxy groups are ethoxy or propoxy or combinations thereof.

10. The ink of claim 1 wherein the alkoxylated (meth)acrylate monomer is trimethylol triacrylate containing about 3 to 6 ethoxy or propoxy groups or a combination thereof.

11. The ink of claim 10 wherein the cellulose ester is cellulose acetate butyrate.

12. The ink of claim 11 wherein the amount of cellulose acetate butyrate is about 0.1 to 2.5% in the ink.

13. The ink of claim 12 wherein the vehicle comprises a compound having at least one α,β-ethylenically unsaturated double bond.

14. The ink of claim 13 wherein the vehicle compound is a monomer or oligomer or both.

15. The ink of claim 14 wherein the amount of resin is about 0.6 to 1.2% of the ink.

16. The ink of claim 15 wherein the amount of resin is about 0.7 to 1% of the ink.

17. The ink of claim 1 wherein the cellulose ester is cellulose acetate propionate.

18. The ink of claim 1 wherein the amount of cellulose acetate propionate is about 0.1 to 2.5% in the ink.

19. The ink of claim 1 wherein the vehicle comprises a compound having at least one α,β-ethylenicaUy unsaturated double bond.

20. The ink of claim 10 wherein the vehicle compound is a monomer or oligomer or both.

21. The ink of claim 20 wherein the amount of resin is about 0.6 to 1.2% of the ink.

22. The ink of claim 21 wherein the amount of resin is about 0.7 to 1% of the ink.