MXPA96002193A

MXPA96002193A - Ink litograf

Info

Publication number: MXPA96002193A
Application number: MXPA/A/1996/002193A
Authority: MX
Inventors: H Boutier Robert; K Mceuen Bruce; F Heilman Michael
Original assignee: Elf Atochem North America Inc
Priority date: 1995-06-07
Filing date: 1996-06-06
Publication date: 1998-04-01

Abstract

The present invention relates to a lithographic printing ink composition comprising: a) as a dispersant, at least one carboxyl-modified copolymer containing ester, being a reaction product of a long-chain alcohol, containing from 6 to 22 atoms of carbon and a styrene-maleic anhydride copolymer, in which at least 35% of the carboxyl groups of styrene-maleic anhydride copolymer are esterified to form the reaction product, b) a solvent selected from the group consisting of animal oils, vegetable oils and mixtures thereof, d) a liquid carrier resin selected from the group consisting of alkyd resins, phenolic resins and mixtures thereof, and e) at least one pigment

Description

LITOGRAPHIC INK Field of the Invention The present invention relates to a lithographic printing ink containing an additive, which provides improved pigment dispersion, more particularly, to a lithographic printing ink containing an additive, which is the product of an esterification reaction of a carboxyl-containing copolymer with a long-chain alcohol, and process for preparing the ink. BACKGROUND OF THE INVENTION Printing inks are mixtures of dispersed or dissolved coloring agents as a liquid carrier or carrier, which forms a gel or paste that can be printed on a substrate and dried. In general, printing inks can be divided into four classes: 1) typographical; 2) lithographic; 3) flexographic; and 4) rotogravure. A varnish is a resinous solution that is sprayed on wood or metal surfaces, in order to provide a generally transparent, hard and lustrous coating, for protection. Lithographic printing inks are used in a number of printing processes, such as photolithography, in which the image areas of a plate are treated to accept greasy inks and repel water, while the non-image areas of the plate, accept water and repel ink. A lithographic printing ink is preferably soluble in organic solvents and strongly hydrophobic. Normally, the coloring agents used in inks are pigments, tints, and colorants, or combinations thereof. The coloring agents provide contrast against a substrate background, on which the inks are printed. A liquid resin, is often used, on a vehicle or carrier for the coloring agents during printing operations, and, in most cases, serves to bind the coloring agents to the substrate. One of the most important functions of the liquid resin carrier is to promote pigment dispersion. The traditional practice in the field of lithographic ink formulation, has been to combine a linseed oil with an alkyd resin or phenolic resin, in order to improve the dispersion of pigments. For these purposes, sulfonated castor oil and naphthenic soaps have also been used, but to a lesser extent. Previous efforts to modify resins have not been successful, in order to improve the dispersion of the pigments. Efforts to modify resins, to date, have resulted in resins exhibiting improved pigment dispersion, but also exhibit reduced hydrophobicity. Consequently, there is a need for an additive for Mtographic printing inks that improves the dispersion of pigments, without adversely affecting the hydrophobicity of the resin carrier. Summary of the Invention The present invention relates to a lithographic printing ink containing an additive, which improves the dispersion of pigments and a process for preparing the improved lithographic printing ink. The lithographic printing ink composition includes, as a dispersant, a modified carboxyl-containing copolymer. The ester-modified carboxyl, containing copolymers, is a reaction product of a long-chain alcohol and styrene-maleic anhydride copolymer, wherein at least about 35% of the carboxyl groups of the styrene-maleic anhydride copolymer are esterified to form the reaction product. The ink further includes a solvent selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, and mixtures thereof, together with a modifying oil, such as those derived from animal oils, vegetable oils, and mixtures thereof. A liquid carrier resin, and a pigment, are also provided in the printing ink. In a preferred process for producing the improved lithographic printing ink, a styrene-maleic anhydride copolymer is reacted, with a long chain alcohol, to produce a reaction product. At least about 35%, more preferably about 40%, of the carboxyl groups of the styrene-maleic anhydride copolymer are esterified to form the reaction product. In an even more preferred process, about 50% of the carboxyl groups of styrene-maleic anhydride copolymer are esterified to form the reaction product. The reaction product is then combined with a solvent and / or modifying oil, to form a relatively thick solution. The carrier of liquid resin and pigment are then introduced into the thick solution. The resulting solution is milled, and subsequently diluted with additional solvent and / or modifying oil to produce a lithographic printing ink with improved pigment dispersion. Detailed Description of the Invention The present invention is a lithographic printing ink having an additive, in which the lithographic printing ink exhibits improved dispersion of pigments without losing hydrophobicity. The improved lithographic printing ink contains an ester-modified carboxyl-containing copolymer dispersant, a hydrocarbon solvent, and an oil-modifying solvent, a liquid resin carrier, and various coloring agents or pigments, as required. An advantage that results from the incorporation of a dispersant in a lithographic printing ink is that the time required to grind and disperse coloring agents is significantly reduced. In addition, the amount of pigment that must be incorporated into the resulting lithographic printing ink is also reduced without losing tone, clarity, or depth of coloration. A dispersant, as used in the present invention, which provides greater toning, depth, and clearly without increasing the viscosity of an ink, is a significant advance.

The carboxyl-containing copolymer, used in the present invention to prepare the dispersant, is preferably prepared by polymerizing predetermined proportions of maleic anhydride and styrene monomer to produce styrene-maleic anhydride copolymers. The molar ratio of styrene monomer to maleic anhydride is preferably from about 3: 1 to about 1: 1. More preferably, a molar ratio of about 3: 1 is used. These substantially amorphous copolymers are commonly available or prepared by well-known polymerization techniques. Preferred styrene-maleic anhydride copolymers contemplated in the practice of the present invention are characterized by having an average molecular weight number less than 2000, relatively high melting temperatures, high thermal stability, and high melt viscosities. Examples of preferred styrene-maleic anhydride copolymers, listed in descending order of preference, are EAM 3000, EAM 2000, and EAM 1000, which are commercially available from "Elf Atochem North America, I nc.", Philadelphia, PA, E . U .A. The EAM 1000 is a copolymer prepared from a mixture of styrene monomer and maleic anhydride, having a molar ratio of about 1.3 moles of styrene monomer to about 1 mole of maleic anhydride. The EAM 1000 has a melting point scale of about 150 ° C to about 170 ° C, a glass transition temperature of about 154 ° C, and an acid number of about 465 to 495, and a viscosity of approximately 28 centipoise (20% ammonia solution at 30 ° C). The EAM 2000, is a copolymer prepared from a mixture of styrene monomer and maleic anhydride, having a molar ratio of approximately 2 moles of styrene for each mole of maleic anhydride. The EAM 2000, has a melting point scale of about 140 ° C, at about 160 ° C, a glass transition temperature of about 124 ° C, and an acid number of about 335 to 375, and a viscosity of approximately 136 centipoise (20% ammonia solution at 30 ° C). The EAM 3000, is a copolymer prepared from a mixture of styrene monomer and maleic anhydride, having a molar ratio of approximately 3 moles of styrene for each mole of maleic anhydride. The EAM 3000, has a melting point scale of about 1 15 ° C, at about 130 ° C, a glass transition temperature of about 125 ° C, and an acid number of about 265 to 305. The EAM 3000, is the most preferred copolymer, because its esterification product exhibits the highest levels of solubility in hydrocarbon and oil solvents commonly used to formulate lithographic printing inks. The carboxyl-containing copolymers, such as styrene-maleic anhydride copolymer, are substantially amorphous solids which are relatively insoluble in aliphatic hydrocarbons and oils. In order to increase its solubility, the carboxyl-containing copolymer is reacted with a long-chain alcohol in an esterification reaction. The ester modified carboxyl, containing copolymer additive, must contain in ester form, an amount to improve the solubility of an aliphatic alcohol of C6 or more, preferably, a C10-22 alcohol or mixtures thereof, more preferably a C? 2-? ß > alcohol or mixtures thereof. The esterification products of alcohols having less than about six carbon atoms do not exhibit sufficient solubility in aliphatic hydrocarbons or oils for the purposes of the present invention. Since the copolymer product of the esterification reaction described below, it must remain in solution to provide the desired, improved pigment dispersion, alcohols having less than six carbon atoms, are not preferred reagents in the esterification reaction. The alcohol compounds which can be reacted with the carboxyl-containing copolymers, to form the ester functions, include primary, secondary, and tertiary alcohols of C6 or more, including hexanol, isohexanol, 2-ethylhexanol, t-octanol, isooctanol, decanol, octadecanol (lauryl alcohol), tetradecyl alcohol, oleyl alcohol, stearyl alcohol. The most preferred alcohols are oleyl alcohol and stearyl alcohol. These alcohols are well known and are commonly formed by a variety of processes, including the process of "oxo" alcohols or hydroformylation. A preferred method for producing the ester modified carboxyl-containing copolymer additive, for use in the present invention, is to react a long chain alcohol, more preferably C12 to C? 8, with a carboxyl-containing copolymer, such as styrene-maleic anhydride copolymer, in a reaction vessel at an elevated temperature. To make the lithographic printing inks, the ester-modified carboxyl-containing copolymer additive is then dissolved in solvent and / or modifying oil. The coloring agents and a liquid carrier resin are then combined with the mixture. The resulting mixture is then pulverized to produce a pigment dispersion. The pigment dispersion, subsequently, is diluted with additional solvent and / or oil modifier, to produce a lithographic printing ink. In the esterification reaction, a long-chain alcohol is introduced into a reaction vessel maintained by an external heat source at a slightly elevated temperature between 40 ° C and 70 ° C. If the long chain alcohol is amorphous at room temperature, it is allowed to melt before introducing any additional components into the reaction vessel. The alcohol component is maintained at the elevated temperature, while a carboxyl-containing copolymer, preferably styrene-maleic anhydride, is slowly introduced into the reaction vessel. The long chain alcohol component is preferably contacted with between 1.3 and 0.9 molar equivalents, more preferably 1 .1 and 0.95 molar equivalents, of the carboxyl-containing copolymer. Preferably, at the conclusion of the esterification reaction, at least about 35%, more preferably about 50% of the carboxyl groups on the carboxyl-containing copolymer, are esterified to form the reaction product. As the carboxyl-containing copolymer is introduced into the reaction vessel, the reaction vessel is continuously heated by the external heat source at an elevated temperature between 140 ° C and 180 ° C, more preferably, about 170 ° C. The esterification reaction between the long chain alcohol and the carboxyl-containing copolymer is carried out at the elevated temperature. Depending on the purity, concentration, temperature and other reaction conditions, the esterification reaction may take from 30 minutes to 12 hours, more preferably from 1 to 3 hours. Common esterification catalysts can optionally be used to promote the esterification reaction. Examples of common esterification catalysts include sulfuric acid, sulfonic acid, and lithium acetate. The esterification conditions described above are well known to those skilled in the art. The product of the esterification reaction can be separated from any volatile materials or excess alcohol at the end of the esterification reaction. Solvents suitable for use in lithographic printing inks are well known to those skilled in the art. Examples of solvents that can be used in lithographic printing inks are high-boiling aliphatic hydrocarbons., normally containing more than 10 carbon atoms, aromatic hydrocarbons, and mixtures thereof. A preferred solvent is an aliphatic hydrocarbon oil, such as a white oil, technical grade, high boiling, containing 14 carbon atoms and more, and having a molecular weight of about 200-250. One of said available solvents is "Magic 470 Oil", available from "Magie Brothers". Examples of modifying oils are vegetable oils, animal oils, and mixtures thereof. A preferred modifying oil is flaxseed oil, liquid carrier resins are well known to those skilled in the art. Examples of suitable liquid resin carriers are alkyd resins or phenolic resins. Pigments are incorporated into a lithographic ink, in order to provide contrast against a substrate, on which the ink is placed. Examples of pigments that can be provided in a lithographic printing ink are titanium dioxide, carbon black, zinc oxide, lead titanate, potassium titanate, antimony oxide, lithopon, phthalocyanine blue, quinacridone, ferrate hydrates, and similar. The hue, depth, and clarity of the color contrast, becomes color, increases as the amount of pigment incorporated in the lithographic ink is increased. Similarly, the viscosity of a lithographic printing ink increases as the amount of pigment is increased. At a certain point, the viscosity of a lithographic printing ink can be very high to be commercially acceptable, which effectively limits the amount of pigment that can be provided in a lithographic ink. In order to prepare a lithographic printing ink having improved pigment dispersion, a predetermined amount of the ester modified copolymer dispersant is combined with a predetermined amount of a hydrocarbon solvent and modifying oil. The ester modified copolymer dispersant, initially, is preferably combined with a modifying oil to form a solution in which the weight fraction of the ester modified copolymer dispersant is from about 10% to about 50%, more preferably, about 30%. Solutions having more than about 50% by weight of the ester modified copolymer dispersant are difficult to completely dissolve. The ester-modified copolymer dispersant, and the modifier oil solution, are combined with additional oil, solvent, coloring agents and liquid resin carriers. The resulting mixture is sprayed to produce a pigment dispersion, and subsequently diluted with solvent and / or additional modified oil, to produce a lithographic printing ink with improved pigment dispersion. The weight ratio of the modifying oil to pigment in the pigment dispersion is preferably in the range of about 2: 1 to 0.5: 1, more preferably about 1: 1. The weight ratio of pigment to additive in the dispersion of pigments, preferably is in the range of about 300: 1 to 50: 1, more preferably 200: 1 to 75: 1, more preferably about 100: 1. Pigment dispersions are commonly diluted or adjusted by end users with resins liquid, solvents, and / or modifying oils, in order to produce a lithographic printing ink, having a desired viscosity. The desired viscosity of any particular lithographic printing ink depends on the characteristics of the printing equipment and substrate. A well-established practice for determining the uniformity and finer dispersion of pigments in an ink formulation is "ASTM D-1210-79" entitled Normal Test for "Fineness of Dispersion of Pigment-Vehicle Systems". This method measures the degree of dispersion of a pigment in a vehicle-pigment system. An ink that has a uniform dispersion of fine particles, normally has a reading on the Hegman scale of approximately 6.5 to 7.5. An ink that has a poorly dispersed mixture of particles, usually has a reading on the Hegman scale in the vicinity of 1 or 2. The most commercial lithographic inks, must have a reading on the Hegman scale above 6.5. Preparative Examples 1 and 2 illustrate a preferred process for preparing the ester-modified carboxyl-containing copolymer, which acts as a dispersant in the present invention. Examples 3 to 10 illustrate preferred methods for preparing the present invention, in which the dispersants have been prepared in a similar manner, but not necessarily identical, for the procedures described in Preparation Examples 1 and 2. Examples 3 to 6 , illustrate the formulation of pigment dispersions, with a variety of preferred dispersants, in which the pigment was carbon black. Examples 7 to 10 illustrate the formulation of pigment dispersions with a variety of preferred dispersants, in which the pigment was titanium dioxide. Comparative Examples 1 and 2 illustrate the formulation of pigment dispersions having no dispersants provided therein, wherein the pigments are carbon black and titanium dioxide, respectively. In accordance with the procedures described in "ASTM-D-121 0- 79", the pigment dispersion formulations described below were sprayed by means of a scraper along a calibrated tapered track. A Hegman scale, numbered from 1 to 8, was provided along the length of the tapered track. As the printing ink formulations were sprayed, along the tapered path, the particles in the ink formed a discernible pattern. A direct reading of the Hegman scale was then made, at the point where the particles formed the discernible pattern. The results of the observations are tabulated later in Table I, entitled, Smoke Black Coloring Agent, and Table II, entitled, Titanium Dioxide Dyeing Agent. PREPARATIVE EXAMPLE I 1044 grams of liquid oleyl alcohol (melting point -7.5 ° C, boiling point 195 ° C to 8 torr), weighed in a 5 liter reaction vessel. The reaction vessel was heated using an external heat source at about 170 ° C, while the alcohol contained in the vessel was continuously stirred. 956 grams of EAM 1000, were slowly introduced into the reaction vessel using a powder funnel, while maintaining the reaction vessel at 170 ° C. The reaction vessel was continuously maintained at 170 ° C for 2 hours, at which time, the external heat source was removed. The reactor vessel was disassembled, and, using insulating gloves, the molten mixture was poured into a tray covered with aluminum foil for cooling, in order to form an ester modified copolymer product. PREPARATIVE EXAMPLE 2 1048 grams of crystalline stearyl alcohol, solid, (melting point 59 ° C, boiling point 210 ° C to 15 torr), weighed in a 5 liter reaction vessel. The reaction vessel was heated using an external heat source at about 60 ° C, to melt the stearyl alcohol in the reaction vessel. 952 grams of EAM 1000, were slowly introduced into the reaction vessel using a powder funnel, while maintaining the reaction vessel at 60 ° C. The reaction vessel was continuously maintained at about 170 ° C for 2 hours. After the external heat source was removed, the reactor vessel was disassembled, and, using insulating gloves, the molten mixture was poured into a tray covered with aluminum foil for cooling, in order to form a modified copolymer product with ester. EXAMPLE 3 1.17 grams of a solution of 30% by weight of an esterification product of EAM 1000, and oleyl alcohol in boiled linseed oil, were combined with 50 grams of boiled linseed oil. 50 grams of flaxseed alkyd resin, 35 grams of "Raven 1200", a carbon black coloring agent, and 100 grams of ceramic beads, were then introduced into the mixture, to form a pigment dispersion designated below as " 178-2". The pigment dispersion "178-2" was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79". EXAMPLE 4 1.17 grams of a solution of 30% by weight of an esterification product of EAM 3000, and oleyl alcohol in boiled linseed oil, were combined with 50 grams of boiled linseed oil. 50 grams of flaxseed alkyd resin, 35 grams of "Raven 1200", a carbon black coloring agent, and 100 grams of ceramic beads, were then introduced into the mixture, to form a pigment dispersion designated below as " 178-3". The pigment dispersion "178-3" was milled in a known manner and periodically subjected to a Hegman grind analysis, in accordance with "ASTM D-1210-79". EXAMPLE 5 1.17 grams of a solution of 30% by weight of an esterification product of EAM 1000, and stearyl alcohol, were combined with 50 grams of boiled linseed oil. 50 grams of flaxseed alkyd resin, 35 grams of "Raven 1200", a carbon black coloring agent, and 100 grams of ceramic beads, were then introduced into the mixture, to form a pigment dispersion designated below as " 178-4". The pigment dispersion "178-4" was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79". EXAMPLE 6 1.17 grams of a solution of 30% by weight of an esterification product of EAM 3000, and stearyl alcohol, were combined with 50 grams of boiled linseed oil. 50 grams of flaxseed alkyd resin, 35 grams of "Raven 1200", a carbon black coloring agent, and 100 grams of ceramic beads, were then introduced into the mixture, to form a pigment dispersion designated below as " 178-5". The pigment dispersion "178-5" was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79". COMPARATIVE EXAMPLE 1 50 grams of boiled linseed oil, 50 grams of flaxseed alkyd resin, 35 grams of "Raven 1200", a coloring agent of carbon black, and 100 grams of ceramic beads, were combined in a container to form a pigment dispersion designated hereafter, as Control-1. The Control-1 pigment dispersion was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79" . EXAMPLE 7 1.67 grams of a solution of 30% by weight of an esterification product of EAM 1000, and oleyl alcohol, were combined with 25 grams of boiled linseed oil. 25 grams of soya alkyd resin 157A, and 50 grams of "TiPure R960-48HG", a titanium dioxide coloring agent, were then introduced into the mixture, to form a pigment dispersion designated below as "170-2" . The pigment dispersion "170-2" was milled in a known manner and periodically subjected to a Hegman grind analysis, in accordance with "ASTM D-1210-79". EXAMPLE 8 1.67 grams of a solution of 30% by weight of an esterification product of EAM 3000, and oleyl alcohol, were combined with 25 grams of boiled linseed oil. 25 grams of soy alkane resin 157A, and 50 grams of "TiPure R960-48HG", a titanium dioxide coloring agent, were then introduced into the mixture, to form a pigment dispersion designated below as "170-3" . The dispersion of pigments "170-3" was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79". EXAMPLE 9 1.67 grams of a solution of 30% by weight of an esterification product of EAM 1000, and stearyl alcohol, were combined with 25 grams of boiled linseed oil. 25 grams of soybean 157A alkyd resin, and 50 grams of "TiPure R960-48HG", a titanium dioxide coloring agent, were then introduced into the mixture, to form a pigment dispersion designated below as "170-4" . The dispersion of pigments "170-4" was milled in a known manner and subjected periodically to a Hegman Grinding analysis, in accordance with "ASTM D-1210-79".

EXAMPLE 10 1.67 grams of a solution of 30% by weight of an esterification product of EAM 3000, and stearyl alcohol, were combined with 25 grams of boiled linseed oil. 25 grams of soybean 157A alkyd resin, and 50 grams of "TiPure R960-48HG", a titanium dioxide coloring agent, were then introduced into the mixture, to form a pigment dispersion designated below as "170-5" . The pigment dispersion "170-5" was milled in a known manner and subjected periodically to a Hegman grind analysis, in accordance with "ASTM D-1210-79". COMPARATIVE EXAMPLE 2 25 grams of boiled linseed oil, 25 grams of soybean resin 157A, and 50 grams of "TiPure R960-48HG", a coloring agent of titanium dioxide, were combined in a vessel to form a pigment dispersion designated hereinafter, as Control-2. The Control-2 pigment dispersion was milled in a known manner and subjected periodically to a Hegman grind analysis, according to "ASTM D-1210-79".

TABLE I - SMOKE BLACK COLORING AGENT Dispersion of pigments Units Hegman Time (min.) 178-2 (Example 3) - 6.3 5 178-3 (Example 4) - 5.5 5 178-4 (Example 5) - 6.3 5 178-5 (Example 6) - 8.0 5 Control-1 (Comparative 1) - 3.0 5 178-2 (Example 3) - 8.0 10 178-3 (Example 4) 8.0 10 178-4 (Example 5) 8.0 10 178-5 (Example 6) 8.0 10 Control-1 (Comparative 1) 3.5 10 178-2 (Example 3) 8.0 15 178-3 (Example 4) Not measured1 15 178-4 (Example 5) Not measured 15 178-5 (Example 6) Not measured 15 Control-1 (Comparative 1) 4.5 15 178-2 (Example 3) Not measured 20 178-3 (Example 4) Not measured 20 178-4 (Example 5) Not measured 20 178-5 (Example 6) Not measured 20 Control-1 (Comparative 1) 6.5 20 178-2 (Example 3) Not measured 25 178-3 (Example 4) Not measured 25 178-4 (Example 5) Not measured 25 178-5 (Example 6) Not measured 25 Control-1 (Comparative 1) 6.8 25 1 The pigment dispersions were no longer measured once the readings on the Hegman scale reached 8.0. TABLE 2 - TITANIUM DIOXIDE COLORING AGENT Dispersion of pigments Units Hegman Time (min.) 170-2 (Example 7) - 7.4 5 170-3 Example 8) 6.5 5 170-4 Example 9) 6.4 5 170-5 Example 10) 8.0 5 Control -2 (Comparative 2 ) 3.6 5 170-2 Example 7) 7.6 10 170-3 Example 8) 7.4 10 170-4 Example 9) 7.3 10 170-5 Example 10) Not measured2 10 Control -2 (Comparative 2) 3.6 10 170-2 Example 7 ) Not measured 1 5 170-3 Example 8) Not measured 1 5 170-4 Example 9) Not measured 1 5 170-5 Example 10) Not measured 1 5 Control-2 (Comparative 2) 6.4 1 5 170-2 Example 7) Not measured 20 170-3 Example 8) Not measured 20 170-4 Example 9) Not measured 20 170-5 Example 10) Not measured 20 Control -2 (Comparative 2) 7.2 20 170-2 Example 7) Not measured 25 170-3 Example 8) Not measured 25 170-4 Example 9) Not measured 25 170-5 Example 10) Not measured 25 Control-2 (Comparative 2) 7.5 25 2 Samples of pigment dispersions were no longer measured once the readings on the Hegman scale reached 8.0. The present invention can be incorporated into other specific forms, without departing from the spirit or essential attributes thereof, and, consequently, reference should be made to the appended claims, rather than to the previous specification, since they indicate the scope of the invention. the invention.

Claims

CLAIMS 1. A lithographic printing ink composition comprising: a) as a dispersant, at least one ester-modified carboxyl-containing copolymer, being a reaction product of a long-chain alcohol, and a styrene-maleic anhydride copolymer, in the which at least 35% of the carboxyl groups of styrene-maleic anhydride copolymer are esterified to form the reaction product; b) a solvent selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons and mixtures thereof, c) a modifying oil; d) at least one liquid carrier resin; and e) at least one pigment.
2. A lithographic printing ink, as defined in claim 1, wherein the long chain alcohol is a straight or branched chain C mono-22 monohydric alcohol.
3. A lithographic printing ink, as defined in claim 1, wherein the long chain alcohol is a straight or branched chain monohydric C? 2-? 8 alcohol.
4. A lithographic printing ink, as defined in claim 1, wherein the long chain alcohol is selected from the group consisting of oleyl alcohol, stearyl alcohol, and mixtures thereof.
5. A lithographic printing ink, as defined in claim 1, wherein the liquid resin of the carrier is selected from the group consisting of an alkyd resin, a phenolic resin, and mixtures thereof.
6. A lithographic printing ink, as defined in claim 4, wherein the modifying oil is a linseed oil.
7. A lithographic printing ink, as defined in claim 7, wherein at least about 40% of the carboxyl groups of styrene-maleic anhydride are esterified to form the reaction product.
A lithographic printing ink, as defined in claim 1, wherein the weight ratio of pigment to additive is between about 300: 1 to about 50: 1.
9. A lithographic printing ink, as defined in claim 1, wherein the weight ratio of the pigment to additive is between about 200: 1 to about 75: 1.
10. A lithographic printing ink, as defined in claim 10, wherein the weight ratio of the pigment to additive is about 100: 1. 1.
A pigment dispersant for lithographic printing inks, comprising a reaction product of a C 1 to C 22 alcohol, and styrene-maleic anhydride copolymer containing carboxyl, having an average molecular weight number less than 2,000, in which, by at least 35% of the maleic styrene-anhydride carboxyl groups are esterified to form the reaction product.
12. A pigment dispersant, as defined in claim 11, wherein at least 40% of the carboxyl groups of styrene-maleic anhydride are esterified to form the reaction product.
13. A pigment dispersant, as defined in claim 12, wherein about 50% of the styrene-maleic anhydride carboxyl groups are esterified to form the reaction product.
14. A process for forming the improved lithographic printing ink, comprising: a) reacting a styrene-maleic anhydride copolymer with a long-chain alcohol to produce a reaction product, in which at least one % of the carboxyl groups of styrene-maleic anhydride copolymer are esterified to form the reaction product; b) combining the reaction product with a solvent selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, and mixtures thereof, together with a modifying oil to form a solution; c) combine the solution from step (b) with at least one carrier liquid resin, and at least one pigment.
15. A process as defined in claim 14, wherein the liquid resin of the carrier is selected from the group consisting of an alkyd resin, a phenolic resin, and mixtures thereof.
16. A process as defined in claim 14, wherein the long chain alcohol is a straight or branched chain C10-22 monohydric alcohol.
17. A process as defined in claim 16, wherein the long chain alcohol is a straight or branched chain C12-18 monohydric alcohol.
18. A process as defined in claim 14, wherein the long chain alcohol is selected from the group consisting of oleyl alcohol, stearyl alcohol, and mixtures thereof.
19. A process as defined in claim 18, wherein the modifying oil is linseed oil.
20. A process as defined in claim 19, wherein about 50% of the carboxyl groups of styrene-maleic anhydride copolymer are esterified to form the reaction product. twenty-one .
A process as defined in claim 14, wherein the weight ratio of pigment to additive is between about 300: 1 to about 50: 1.
22. A process as defined in claim 21, wherein the weight ratio of pigment to additive is between about 200: 1 to about 75: 1.
23. A process as defined in claim 20, wherein the weight ratio of pigment to additive is between about 100: 1.