MXPA97009969A - Compositions of pigmen - Google Patents

Abstract

The present invention provides the use of a resin pigment in which from 10 to 100% of the resin proportion of the product is a resin ester, as a colorant in a lithographic printing ink.

Description

Pigment Compositions The present invention relates to pigment compositions suitable for use in lithographic printing inks. Pigment compositions, for use in the manufacture of lithographic printing inks, typically contain additives to improve the wetting and dispersion characteristics of the pigment in the ink vehicle. You can also modify other ink properties such as rheology and brightness. Such additives are usually resins and modified resins such as, for example, hydrogenated resins, disproportionated resins and maleic acid resins. These are normally incorporated as their aqueous solutions in dilute alkali during the pigment synthesis, then precipitated with the pigment by the addition of acid, a metal salt, eg, calcium salt, aluminum or amine / quaternary ammonium. However, with the arrival of the replacement, for ecological reasons, of the lower aliphatic alcohols in the traditional ink fountain solutions, for example, glycols, surfactants, etc., said pigment additives as described above, may interfere with the lithographic printing process, interrupting the delicate aqueous / non-aqueous balance of the ink source and ink solutions, influencing the pH instability of the ink source. Therefore, when such pigments are used in lithographic inks it is found that the pH of the ink source solution is significantly raised, e.g., from about 5 to about 7 or even higher. When this happens, the ink and the temp source solution begin to mix and this results in poorer printing performance, e.g., printing definition, especially when using modern fast printing presses. This phenomenon has been known for a few years and the use of an oil-soluble pH buffer has been proposed to reduce the pH change in EP0315844. We have now found that the undesirable pH upshift of the solution that provides the ink can be significantly reduced or even eliminated by replacing traditionally used acids and resin salts with resins in which the carboxylic acid group (s) they have been reacted partially or completely with alcohols, polyols or phenols to form insoluble resin esters. The resultant pigment compositions, as well as being easily incorporated into the lithographic ink, impart improved printing properties to the ink characterized by better ink source / balance balance, reduced ink fountain pH change and, consequently, better transfer of ink and print definition. The resin esters do adversely affect the color properties of the pigment and can improve said properties by rheology and gloss. Accordingly, the present invention provides the use of a resin pigment in which from 10 to 100%, preferably from 40 to 100% by weight of the resin proportion of the product is a resin ester, as a colorant in a lithographic printing ink. The base pigments to which this invention refers are any of those that can be employed in lithographic inks, e.g., azo lacquer pigments such as Red Pigments 48, 52, 53, 57, diarylide pigments such as Pigments. Yellows 12, 13, 14 and orange pigment 34 and phthalocyanines such as Pigment Blue 15: 3. The resin esters used can be, for example, esters of resin acids, or of modified resin acids (hydrogenated, disproportionate, maleated, polymerized, phenolic modified). The alcohols used for esterification can usually have from 1 to 20 carbon atoms and can optionally be substituted with said groups as halogen, e.g. chlorine, or amino groups. Suitable polyols can have from 2 to 10 OH groups such as glycerol and pentaerythritol. Suitable phenols include phenol and cresol by themselves. Optionally, other additives such as surface active agents can be added to help synthesize the pigment according to known technology. Such agents may include nonionic, anionic, amphoteric and cationic surfactants, eg, ethoxylated alcohols, phenyls, acids, amines, resins and salts of modified resin acids, alkyl sulphates, alkyl sulfosuccinates, arylalkyl aryl sulfonic acids. , amine salts and quaternary ammonium. However, care must be taken to choose the type and quantity of said auxiliaries to ensure that their use does not negate the value of the main additive, the resin ester. The pigment product is used in a lithographic ink. Vehicles for such inks include aromatic petroleum hydrocarbon resins, alkali refined linseed oil, pentaerythritol esters of phenolic modified resins, maleic acid modified ester ester and mixtures thereof with each other and with wood. The invention also provides a lithographic printing ink, comprising a lithographic printing ink vehicle, a resin pigment in which from 10 to 100%, preferably 40 to 100% by weight of the resin proportion of the product is a resin ester. The invention is illustrated by the following Examples. Example 1 35.9 g of 4-amino-toluene-3-sulfonic acid (98.2%) are dissolved in 26.5 ml of water using 16.2 g of 47% sodium hydroxide liquor with stirring. The temperature of the solution is reduced to 0-5 ° C by the addition of ice before adding 12.2 g of sodium nitrite which was previously dissolved in 50 l of water. 38 ml of concentrated hydrochloric acid (35%) was added to the solution with stirring to form the diazo salt. The volume of the suspension was adjusted to 750 ml at 0-5 ° C by the addition of ice. The diazo component was added to the resin / resin ester / BONA suspension for a period of 40 minutes with mechanical stirring and maintaining a temperature of 0-5 ° C and pH of 10.8-11. After the coupling process was complete, the suspension was stirred for an additional 15 minutes to the above conditions before adding 33.2 g of calcium chloride (80%). The suspension was maintained under the above conditions for 30 minutes in order to ensure complete lacquering. The pH of the suspension was adjusted to 7.0 using dilute hydrochloric acid (10%) before heating with steam to 80CC. The suspension is rinsed at 65 ° C and the free salt is filtered and washed. The product is dried overnight at 90 ° C before grinding it to a powder. 20g of the finished powder is incorporated into 80g of ink varnish consisting of 1 part distillate (known as PKWF 4/7 New and supplied by Halterman), 2 part resin (known as Sparkle 93 and supplied by Lawter International) and 3.25 parts of hard gelled resin (known as Luminex 55 and supplied by Lawter International). The mixing is carried out on the back rollers of a Buhler SDY-200 mill at 23 ° C and pressure of 10 bar for 5 minutes. The mixture that is then provided with 3x10 bar, passes over the three roller mill at 23 ° C (with 2 minutes of mixing with the rear rollers between each pass) before it is allowed to drop to 18% pigmentation using an apparatus of mace crusher, with more ink varnish. The sample observes comparable color resistance, significantly improved brightness and improved low shear flow when compared to a normal pigment (free resin ester) described in Example 4. The effect of this ink on the pH decrease of a solution The ink souused in a lithographic printing process is evaluated according to the following method. 50 of the ink are placed in a plastic container together with 150 ml of normal ink fountain solution (Fountsol F5, supplied by Inkland Ltd) and a double-vane mixer VOSS is used to stir the mixture (150 ml) for one 1 hour period. The ink sousolution is separated from the ink and the pH is measured. The results are recorded in Table 1. This sample observes a significantly better decrease in pH compared to an ink comprising a resin-free pigment (Example 4): Example 2 A pigment was prepared as in Example 1 except 3.8 g of the Recoldis A resin is solubilized with 1.04 g of sodium hydroxide liquor (47%) and a 30.4 g dispersion of Tacolyn 153 resin ester is used. When incorporated into a hot ink varnish and test as in Example 1, this sample observes equivalent color strength, significantly improved brightness, low shear flow and reduced pH change (table 1) when compared to an ink comprising a resin-free pigment (Example 4) ).

Example 3 A pigment was prepared as in Example 1, except that Recoldis A resin was not used, but instead 38g of the Tacolyn 153 ester resin dispersion (50% w / w) was incorporated into the product. When this powder was incorporated into a hot varnish as in Example 1, the final ink shows equivalent strength and significantly improved gloss, low shear flow and reduced pH change (Table 1) when compared to an ink comprising a pigment free of resin ester (Example 4). Example 4 A pigment was prepared as in Example 1, except that 19 g of Recoldis A resin was solubilized with 5.2 g of sodium hydroxide liquor (47%) and no resin ester was incorporated into the product. The pH change results from ink prepared as in Example 1, but the use of this product is recorded in Table 1. Table 1. The pH change of the ink fountain solution after shaking with the ink for one hour using a double-vane mixer VOSS: Example 1 Example 2 Example 3 Example 4 Initial pH 4.6 4.6 4.6 4.6 Final pH 5.8 5.7 5.7 7.6 Change + 1.2 + 1.1 +1.1 +3.0

Claims (3)

1. CLAIMS 1. The use of a resin pigment in which from 10 to 100% by weight of the resinated proportion of the product of a resin ester, as a colorant in a lithographic printing ink.
2. 2. The use according to claim 1, wherein from 40 to 100% by weight of the resin proportion of the product is a resin ester. 3. The use according to claim 1 or 2, wherein the resin ester is derived from a resin by esterifying free acid groups on the resin with an optionally substituted alcohol or polyol. 4. The use according to claim 3, wherein the queen is a wood resin, a gum resin, a bait oil resin or a product derived from any of these by hydrogenation, disproportionation or polymerization. 5. The use according to claim 3 or 4, wherein the resin ester is derived from a resin by esterifying free acid groups on the resin with glycerol or pentaerythritol. 6. A lithographic ink comprising an ink vehicle and a resin pigment as defined in any of the preceding claims. The use according to claim 1, substantially as described above with reference to any of the above Examples 1 to 3. 8. A lithographic ink substantially as described above with reference to any of the above Examples 1 to
3. 3.