LED-curable offset printing inks containing aluminum additives

Abstract

An LED-curable offset printing ink comprises: 25-85% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate; 0-20% of one or more photoinitiators; 5-60% of one or more rosin-modified polyester resins, wherein the rosin-modified polyester resins have a molecular weight of 5,000 to 35,000 Daltons; 0.2-5% of one or more aluminum additives; 0.1-5% of one or more polymerization stabilizers; and 0-50% of colorant.

Description

Technical Field

[0001] This invention relates to LED-curable printing ink or varnish compositions suitable for offset printing. In particular, this invention relates to LED-curable varnishes and inks applied by offset printing that contain aluminum additives.

[0002] The inks and varnishes of this invention are more sustainable than conventional UV-curable inks and varnishes because they can be cured with LED light, which requires less energy.

[0003] Furthermore, the present invention relates to printed matter comprising or derived from the ink or varnish composition of the present invention, which is suitable for graphic applications and packaging applications. Background Technology

[0004] The use of UV-LED lamps for curing is increasing due to the technology's various advantages, such as energy efficiency, longer lifespan than conventional UV bulbs, and a safe, mercury-free product. Furthermore, unlike typical mercury UV bulbs, which have been at the forefront of UV technology for many years, UV-LED lamps do not produce ozone.

[0005] Therefore, in the field of graphic arts, printing presses are increasingly being equipped with or retrofitted with compact UV-LED dryers. State-of-the-art LED dryers typically emit LED light with peak wavelengths of 365-405nm.

[0006] LED offset printing inks represent a state-of-the-art technology, which can be used, for example, on sheet-fed or web-fed printing presses equipped with LED dryers. Compared to solvent-based inks or oil- or mineral-based inks, they combine the aforementioned advantages of LED drying (i.e., LED curing) with sustainable (A-free, i.e., solvent-free) applications and rapid drying (high productivity).

[0007] However, similar to UV inks, UV-LED inks typically exhibit poorer lithographic press performance compared to conventional inks based on vegetable or mineral oils. One reason for this behavior is that acrylates are more polar than oils, which makes UV-LED inks even more polar, thus adversely affecting lithographic processes and jet interactions.

[0008] Another drawback of UV-LED technology may be poor surface curing due to oxygen inhibition. Oxygen inhibition refers to the fact that oxygen, as a diradical, can readily react with and deactivate free radicals formed by photoinitiators, monomers, or on the growing polymer chains (usually in the form of peroxide derivatives). This can lead to insufficient drying of ink or coating surfaces in oxygen-dominated conditions. This is particularly problematic for commercially available long-wavelength UV-LED light dryers emitting light in the 365-405 nm range, due to the lack of shorter wavelengths (which are highly beneficial for good surface curing and activating photoinitiator free radicals on or near the surface).

[0009] This can usually be counteracted by using highly reactive, multifunctional monomers, such as dipentaerythritol hexaacrylate, thereby increasing the polymerization rate rather than the oxygen-inhibiting process.

[0010] However, the widespread use of multifunctional monomers (such as dipentaerythritol hexaacrylate) imparts a high crosslinking density, which often makes the ink brittle, adversely affecting adhesion. Furthermore, these acrylate monomers can also lead to poor printability.

[0011] To impart better lithographic printing performance and reduce brittleness to UV inks, rosin resins that have been successfully used in conventional inks can also be used in UV inks (such as those in US 5,212,213 or US 7,232,861 and EP3433711), provided that they show sufficient solubility in acrylates.

[0012] US 5,212,213 mentions the use of fully fumarate-treated rosin and / or fully maleate-treated rosin to produce a higher softening point and allow the production of 100% solid resin. In this invention, due to the higher risk of polymerization during the ink or varnish manufacturing process caused by high temperatures or prolonged dissolution times, the temperature is kept as low as possible while still remaining above the threshold used to dissolve rosin in acrylates.

[0013] US 7,232,851 discloses an electron beam and / or UV curable lithographic printing ink composition and printing method that uses only rosin, which is generally soluble in acrylates. However, this invention requires that the rosin also exhibit good solubility in highly functional acrylates, particularly suitable for LED inks such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. Specifically, the rosin used in this invention exhibits good solubility in pentaacrylates and hexaacrylates, such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. As will be discussed in more detail below, the solubility in these pentafunctional and hexafunctional acrylates is achieved without the use of high temperatures (i.e., temperatures above 135°C).

[0014] Another issue related to the printing press performance of UV and LED inks is so-called ink fly. During the printing process, small ink droplets escape from the rapidly rotating rollers as a mist due to the strong centrifugal force of the fast-rotating rollers and the limited cohesive force of the ink, contaminating the printing press and causing frequent large-scale cleaning operations and production stoppages. Typical measures to reduce ink fly include increasing the solids content of the ink by adding fillers or increasing pigment deposition.

[0015] However, high solids content often leads to adverse effects, such as ink buildup on rollers and plates due to particle agglomeration caused by high solids content.

[0016] EP3434711 mentions the use of rosin esters in potentially amount-cured (EC) inks. It does not mention LEDs, aluminum additives, or improvements to fly inks via aluminum additives. Summary of the Invention

[0017] The purpose of this application is to provide an LED-curable offset printing ink that exhibits low ink splatter tendency on offset printing presses while maintaining excellent printing press performance and LED drying performance.

[0018] References to or identification of any document in this application do not imply an admission that such document represents prior art of the present invention. Attached Figure Description

[0019] Figure 1 This is a spider diagram comparing the ink of the present invention (with aluminum additive, outer curve shape) with a comparative ink (without aluminum additive, inner curve shape). Specifically, the spider diagram shows the ink performance scores of Examples 2A-5A and Comparative Examples 2B-5B of the present invention. Detailed Implementation

[0020] The present invention is further illustrated by the following set of embodiments and combinations thereof, which arise from, for example, the indicated dependencies and reverse references. In particular, it should be noted that in each instance in which a series of embodiments is referenced, for example in the context of terms such as “the method of any one of embodiments 1 to 5,” each embodiment within that scope is explicitly disclosed to a person skilled in the art that the wording of the term should be understood as synonymous with “the method of any one of embodiments 1, 2, 3, 4, and 5.”

[0021] This invention provides a printing ink or varnish composition comprising:

[0022] 25-85% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate;

[0023] 0-20% of one or more photoinitiators;

[0024] 5-60% of one or more rosin-modified polyester resins, wherein the rosin-modified polyester resin has a molecular weight of 5,000 to 35,000 Daltons;

[0025] 0.2-5% of one or more aluminum additives;

[0026] 0.1-5% of one or more polymerization stabilizers; and

[0027] 0-50% colorant.

[0028] The ink or varnish composition according to the present invention is suitable for curing by UV-LED radiation.

[0029] In one aspect, the present invention provides a varnish composition comprising:

[0030] 25-85% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate;

[0031] 0-20% of one or more photoinitiators;

[0032] 5-60% of one or more rosin-modified polyester resins, wherein the rosin-modified polyester resin has a molecular weight of 5,000 to 35,000 Daltons;

[0033] 0.2-5% of one or more aluminum additives; and

[0034] 0.1-5% of one or more polymerization stabilizers.

[0035] In another aspect, the present invention provides an ink composition comprising the varnish of the present invention and 0-50% (preferably 5-40%) of a colorant. Advantageously, LED-curable inks containing aluminum-modified acrylate varnishes exhibit excellent lithographic printing performance and lower ink splatter tendency, while maintaining or even exceeding performance on a printing press, and exhibiting excellent LED curing performance.

[0036] The ink is suitable for printing on any substrate that is offset printed, such as graphic paper, packaging paper, and packaging applications on cardboard and foil.

[0037] Preferably, the LED-curable ink or varnish of the present invention comprises the following materials:

[0038] 25-85% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate;

[0039] 0.5-20% photoinitiator;

[0040] 5-60% of rosin-modified polyester resin, wherein the rosin-modified polyester resin has a molecular weight of 5,000 to 35,000 Daltons;

[0041] 0.2-5% aluminum additive;

[0042] 0.1-5% polymerization stabilizer;

[0043] 0-50% colorant.

[0044] acrylate

[0045] In one embodiment, the (meth)acrylic acid (i.e. (meth)acrylate) monomers suitable for use in the present invention include esters of acrylic acid or methacrylic acid having a defined structure.

[0046] Non-limiting examples of (meth)acrylate monomers suitable for use in this invention include n-octyl acrylate, isooctyl acrylate, n-decyl acrylate, lauryl acrylate, stearyl acrylate, ethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, ethoxylated neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, tripropylene glycol diacrylate, bisphenol A diacrylate, ethoxylated bisphenol A diacrylate, and bisphenol A diglycidyl ether diacrylate. Ester, ethoxylated bisphenol A diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol triacrylate, ethoxylated pentaerythritol triacrylate, propoxylated pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, bis(trimethylolpropane)tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, or mixtures thereof.

[0047] In one embodiment, the LED-curable varnish or ink of the present invention comprises alkoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol tetraacrylate, bis(trimethylolpropane) tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, alkoxylated dipentaerythritol hexaacrylate, or mixtures thereof.

[0048] In one embodiment, the ink of the present invention may further comprise acrylate oligomers. In one embodiment, the ink of the present invention may further comprise acrylated oligomers with a number average molecular weight of about 400-5,000 Daltons and an acrylate functionality ≥2, such as, for example, epoxy acrylates, polyester acrylates, acrylated polyurethanes, fatty acid-modified polyester acrylates, and acrylated polyethers, to impart rheological properties, pigment wettability, transferability, gloss, chemical resistance, and other film properties.

[0049] Preferably, the ink or varnish composition of the present invention comprises: pentaacrylate or hexaacrylate, and at least one other acrylate selected from those acrylates described herein. More preferably, the ink or varnish composition of the present invention comprises: hexaacrylate, and at least one other acrylate selected from those acrylates described herein.

[0050] Preferably, the ink or varnish composition of the present invention comprises: dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate, and at least one other acrylate selected from those acrylates described herein. More preferably, the ink or varnish composition of the present invention comprises: dipentaerythritol hexaacrylate, and at least one other acrylate selected from those acrylates described herein.

[0051] Preferably, the ink or varnish composition of the present invention comprises a hexaacrylate and at least one other acrylate, wherein the at least one other acrylate is selected from alkoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol tetraacrylate, bis(trimethylolpropane) tetraacrylate, dipentaerythritol pentaacrylate, or mixtures thereof. More preferably, the ink or varnish composition of the present invention comprises dipentaerythritol hexaacrylate and at least one other acrylate, wherein the at least one other acrylate is selected from alkoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol tetraacrylate, bis(trimethylolpropane) tetraacrylate, dipentaerythritol pentaacrylate, alkoxylated dipentaerythritol hexaacrylate, or mixtures thereof.

[0052] Preferably, the ink or varnish composition of the present invention contains 30-70% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate.

[0053] Preferably, the ink or varnish of the present invention contains 25-60% pentaacrylate or hexaacrylate.

[0054] Photoinitiator

[0055] The radiation-curable ink of the present invention contains a photoinitiator that absorbs in the UVA region at 320-400 nm, such as, for example, substituted benzophenones, aminoalkylphenyl ketones, acylphosphine oxides, and thioxanthones, such as 4-thienylbenzophenone, 4,4'-bis(diethylamino)-benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-but-1-one, 2-methyl-1-[4(methoxythio)-phenyl]-2-morpholinoprop-2-one, diphenylacylphenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, ketocoumarin, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, or mixtures thereof.

[0056] Preferably, the ink or varnish composition of the present invention comprises one or more photoinitiators selected from phosphine oxides, acetophenone (including aminoacetophenone), aminobenzoic acid esters, thioxanone, and combinations thereof.

[0057] For inks designed for use in food packaging, migratory low molecular weight monomer photoinitiators are advantageously minimized, or even more advantageously replaced entirely by oligomeric or polymeric photoinitiators (such as IGM Resins' trademarked Omnipol TX).

[0058] Preferably, the ink or varnish composition according to the invention contains 0.5-20% of one or more photoinitiators, more preferably 3-18% of one or more photoinitiators, and even more preferably 5-15% of one or more photoinitiators.

[0059] rosin resin

[0060] Rosin resins, such as maleic acid-modified rosin esters or phenolic resin-modified rosin resins, are widely used as printing ink media in flexographic and gravure printing inks. Maleic acid-modified rosin esters generally exhibit good pigment wetting, gloss retention, color retention, and adhesion, and typically show better solution performance in acrylates compared to phenolic resin-modified rosin resins. Rosin esters can be synthesized from commercial rosin (such as Chinese rosin, wood rosin, or tall oil rosin) with bifunctional acids (such as maleic acid, fumaric acid, itaconic acid) and trifunctional or tetrafunctional hydroxyl compounds (such as glycerol, trimethylolpropane, pentaerythritol). Rosin esters are commercially available and can be prepared according to the descriptions in "Printing Ink Manual," 5th edition, Blueprint, London. For example, the preparation of maleic acid-modified rosin esters is specifically described in Example 1 of US2007232786. Typically, modified rosin esters are prepared by heating commercial rosin (e.g., rosin resin) with a bifunctional acid (e.g., maleic acid) and a hydroxyl compound (e.g., pentaerythritol) until the desired acid value (also known as acid number) is obtained.

[0061] However, although rosin esters are known in the art, the rosin resin used in this application should be soluble not only in general acrylates but also in highly functional acrylates particularly suitable for LED inks, such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. As used herein, the rosin resin exhibits good solubility in highly functional acrylates when a 30% by weight (preferably 40% by weight, even more preferably 50% by weight) solution of the rosin resin in a highly functional acrylate (especially dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate) does not show visible precipitation at room temperature (i.e., 20°C). This can be achieved, for example, by appropriately selecting acids (such as maleic acid or maleic anhydride or cyclohexene dicarboxylic anhydride or methylcyclohexene dicarboxylic anhydride) and polyols (such as glycerol and trimethylolpropane) to provide better solubility and by limiting molecular weight and softening point. To limit the molecular weight and provide excellent solubility in acrylates, monofunctional acids such as benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphtholic acid, or fatty acids such as linoleic acid can be added to the reaction mixture to control the condensation reaction and molecular weight.

[0062] Preferably, the rosin resin used in this invention is derived from i) rosin, wood rosin or tall oil rosin; ii) one or more difunctional acids or anhydrides; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols or tetrafunctional polyols; and iv) one or more monofunctional acids.

[0063] Preferably, the difunctional acid or anhydride is selected from maleic acid, maleic anhydride, cyclohexene dicarboxylic acid dianhydride, or methylcyclohexene dicarboxylic acid dianhydride. More preferably, the difunctional acid or anhydride is selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride.

[0064] Preferably, the one or more monofunctional polyols, difunctional polyols, trifunctional polyols or tetrafunctional polyols are selected from glycerol or trimethylolpropane.

[0065] Preferably, the one or more monofunctional acids are selected from benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphthoic acid, and linoleic acid. More preferably, the one or more monofunctional acids are selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid. Even more preferably, the one or more monofunctional acids are benzoic acid.

[0066] Preferably, the rosin resin used in this invention is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphtholic acid, and linoleic acid. More preferably, the rosin resin used in this invention is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid.

[0067] Preferably, the rosin resin used in this invention is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from maleic acid, maleic anhydride, cyclohexene dicarboxylic acid dianhydride, or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphthoic acid, and linoleic acid. More preferably, the rosin resin used in this invention is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid.

[0068] Preferably, the rosin resin used in this invention is derived from i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols selected from glycerol or trimethylolpropane; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid.

[0069] Furthermore, to provide a hydrophobic / hydrophilic balance during offset printing, rosin resin should possess some polar acid groups in addition to nonpolar (hydrophobic) rosin units. Typically, an acid value of 5-50 mg KOH / g (preferably 10-30 mg KOH / g) is suitable for rosin resin. More preferably, the rosin resin has an acid value of 12-25 mg KOH / g.

[0070] Furthermore, the softening point of rosin resin is important. The dropping point refers to the temperature at which the first drop of molten material is dispensed from a standard cup with a defined orifice under controlled test conditions in an oven. For example, it can be measured using automated equipment such as the Mettler Toledo DP70. Due to the risk of acrylate polymerization at higher temperatures, the temperature range in which the inks or varnishes of this invention can be prepared is limited. If the rosin ester has a high softening point, such as >135°C, it is difficult to dissolve in acrylate below 100°C, or it takes a very long time. Unlike non-polymer materials, polymers do not dissolve instantaneously; dissolution is controlled by the disentanglement of polymer chains. This means that the polymer must expand before it can dissolve, which is more difficult below the softening point (Koening et al., “A review of polymer dissolution,” Vol. 28, No. 8, August 2003, pp. 1223-1270).

[0071] Therefore, the risk of polymerization during ink or varnish manufacturing is higher due to high temperatures or prolonged dissolution times. Preferably, the softening point of the rosin resin is in the range of 70-135°C or 85-110°C.

[0072] Before use, the suitability of rosin resin should be tested to confirm that it has sufficient solubility to manufacture inks or varnishes. Generally, the solubility of rosin resin should allow for stable inks or varnishes in dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate at concentrations >30% by weight or >40%. Stability indicates no resin precipitation at lower storage temperatures and no polymerization of inks or varnishes at higher storage temperatures.

[0073] Preferably, the ink or varnish composition of the present invention contains 5-50%, preferably 10-40%, of rosin resin.

[0074] Surprisingly, the rosin resin used in this invention is soluble in pentaacrylate and hexaacrylate monomers (e.g., dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate) without the need for high temperatures (i.e., temperatures above 135°C). Preferably, the rosin resin is soluble in pentaacrylate and hexaacrylate monomers (e.g., dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate) at ≤120°C, preferably ≤100°C.

[0075] Preferably, the rosin resin has a molecular weight of 8,000-35,000 Daltons, more preferably 10,000-35,000 Daltons.

[0076] Rosin resins suitable for this application that exhibit good solubility in dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate generally have a molecular weight of 5,000-35,000 or 5,000-30,000 Daltons as measured by size exclusion chromatography; a softening point of 70-135°C or 85-110°C; and an acid value of 5-50 mg KOH / g, 10-30 mg KOH / g, or 12-25 mg KOH / g. Preferably, the rosin resin has a molecular weight of 5,000-35,000 Daltons, a softening point of 85-110°C, and an acid value of 10-30 mg KOH / g. More preferably, the rosin resin has a molecular weight of 5,000-35,000 Daltons, a softening point of 85-110°C, and an acid value of 12-25 mg KOH / g.

[0077] The rosin resins used in this invention typically have an ethanol value >4 g / 10 g. For example, the rosin resins used in this invention typically have an ethanol value of 4-10 g / 10 g. As understood in the art, the ethanol value (EN) provides a measure of the resin's tolerance to ethanol, and thus provides an indication of the resin's polarity.

[0078] Aluminum Additives

[0079] The aluminum additives suitable for this application are aluminum alkoxides, aluminum chelates, or aluminum carboxylate. Suitable aluminum alkoxides include aluminum monopropoxy, aluminum dipropoxy, or aluminum tripropoxy; aluminum monoisopropoxy, aluminum diisopropoxy, or aluminum triisopropoxy; aluminum monobutyrate, aluminum dibutyrate, or aluminum tributyrate; aluminum monoisobutyrate, aluminum diisobutyrate, or aluminum triisobutyrate, or blends thereof. Suitable aluminum chelates include chelates of ethyl aluminum monoacetoacetate with diisopropanol, dichelates and trichelates of aluminum with alkyl acetoacetate or alkyl diketone, or blends thereof. Suitable aluminum carboxylate includes the group selected from aluminum triacetate or aluminum tripropionate and blends thereof.

[0080] Preferably, the aluminum additive is an aluminum chelate. More preferably, the aluminum additive is selected from chelates of ethylaluminum monoacetoacetate and diisopropanol; dichelates and trichelates of aluminum with alkyl acetoacetate esters or alkyl diketones, or blends thereof.

[0081] Preferably, the aluminum additive is aluminum acetoacetate diisopropoxy (CAS No. 14782-75-3).

[0082] Most of these aluminum additives are commercially available. To better handle moisture-sensitive additives (such as diisopropanol chelates, which may be referred to as alkoxides) and to avoid hydrolytic decay, the aluminum additive can be pre-dissolved in a small amount in an inert solvent, such as sunflower oil. Therefore, in a preferred aspect of the invention, the aluminum additive is an aluminum alkoxide, aluminum chelate, or aluminum carboxylate in an inert solvent. When the aluminum additive is in an inert solvent (such as sunflower oil), the weight ratio of the aluminum additive to the inert solvent is 1:1.

[0083] Suitable inert solvents include mineral oils and vegetable oils, such as sunflower oil. Preferably, the inert solvent is sunflower oil.

[0084] Preferably, the aluminum additive is present in the sunflower oil in a 1:1 weight ratio.

[0085] Preferably, the aluminum additive is an aluminum chelate in an inert solvent. More preferably, the aluminum additive is a chelate of ethylaluminum monoacetoacetate and a diisopropanol compound in an inert solvent; a dichelate and a trichelate of aluminum with alkyl acetoacetate esters and alkyl diketones, or blends thereof.

[0086] Preferably, the aluminum additive is an aluminum chelate in sunflower oil. More preferably, the aluminum additive is a chelate of ethylaluminum monoacetoacetate and a diisopropanol compound in sunflower oil; a dichelate and a trichelate of aluminum with alkyl acetoacetate esters and alkyl diketones, or blends thereof.

[0087] Preferably, the aluminum additive is ethyl acetoacetate diisopropoxyaluminum in an inert solvent. More preferably, the aluminum additive is ethyl acetoacetate diisopropoxyaluminum in sunflower oil.

[0088] In this application, during the production of inks or varnishes at high temperatures of 80-120°C, aluminum additives can react with hydroxyl, carboxyl, and amine groups in the inks or varnishes. This has a positive effect on rheology, particularly on the structure or so-called bulk (viscosity at low shear rates, i.e., D = 2 1 / s) of the inks made therefrom, and affects the cohesiveness of the inks.

[0089] In this invention, the aluminum additive is present at 0.2-5% of the ink or varnish composition. Preferably, the aluminum additive is present at 0.5-5%, more preferably 0.5-3%, of the ink or varnish composition.

[0090] Preferably, the ink or varnish composition of the present invention contains 0.2-5% aluminum additive in an inert solvent such as sunflower oil. Preferably, the weight ratio of aluminum additive to inert solvent is 1:1, such that the composition contains 0.1-2.5% aluminum additive and 0.1-2.5% inert solvent.

[0091] Polymerization stabilizers (also referred to as polymerization inhibitors in this article)

[0092] The inks of this invention may also contain stabilizers to ensure a good shelf life. Examples of such polymerization inhibitors include nitroso-based stabilizers, such as nitrosophenylhydroxylamine; phenolic stabilizers, such as hydroquinone (HQ), methyl ether hydroquinone (MEHQ), butylated hydroxytoluene (BHT), and 2,6-di-tert-butyl-N,N-dimethylamino-p-cresol, phenothiazine, and nitrosophenylhydroxylamine stabilizers; and stabilizers based on copper thiocarbamate and zinc thiocarbamate. This component can be used in varnishes and inks because long-wavelength absorbing photoinitiators suitable for LED drying also absorb visible light, making them prone to premature polymerization.

[0093] Preferably, the ink or varnish composition contains 0.5-5% of one or more polymerization stabilizers.

[0094] Varnish preparation

[0095] For example, the varnish of the present invention is prepared, for instance, by adding a liquid component and a stabilizer to a stirred tank heated to 80-120°C, followed by the addition of solid rosin resin and optional other solid additives. Once the rosin resin has dissolved, an aluminum additive is added, the mixture is stirred at a temperature for a defined time, filtered, and then it can be used to manufacture LED-curable inks. The varnish is characterized by its viscosity at high and low shear rates (D = 50 lb / s and D = 2 lb / s, respectively), as measured by a rheometer, and can be further characterized by oscillation experiments to determine the storage modulus, loss modulus, and the ratio of storage modulus to loss modulus (tanδ), thereby describing the viscous and elastic portions of the varnish. A lower tanδ indicates a higher degree of reactivity with the aluminum additive. Typically, 0.5-5.0 wt% of the aluminum additive is added, depending on the desired viscosity and rheological properties of the varnish.

[0096] Preferably, the varnish composition of the present invention exhibits a viscosity of 40-150 Pa·s and a shear rate of D = 50 1 / s at 23°C, more preferably a viscosity of 60-100 Pa·s and a shear rate of D = 50 1 / s at 23°C, and even more preferably a viscosity of 60-80 Pa·s and a shear rate of D = 50 1 / s at 23°C.

[0097] For example, the ink of this invention can be made by a two-step process: preparation of a premix and milling. A premix is ​​prepared by loading the varnish of this invention and additional monomers into a mixing vessel; stirring is then initiated and solid components such as colorants, fillers, and additional additives are added. During mixing, the temperature is raised to 40-70°C and maintained at the mixture temperature until all pigments are wetted. The premix is ​​then transferred to a milling process (e.g., a three-roll mill or bead mill) and milled until the desired fineness is achieved as measured by a milling instrument (e.g., an NPI gauge).

[0098] Colorant

[0099] The ink of the present invention may further contain one or more colorants dispersed therein in the form of dyes or pigments. Pigments suitable for use in the present invention include conventional organic or inorganic pigments. Representative pigments may be selected, for example, from Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, 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 111, Pigment Yellow 114, Pigment Yellow 121, Pigment Yellow 126, Pigment Yellow 127, Pigment Yellow 136, Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Yellow 194, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Orange 36, Pigment Orange 61, Pigment Orange 62, Pigment Orange 64, Pigment Red 2, Pigment Red 9, Pigment... Pigment 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 48:2, Pigment Red 53:1, Pigment Red 57:1, Pigment Red 81:1, Pigment Red 112, Pigment Red 122, Pigment Red 170, Pigment Red 184, Pigment Red 210, Pigment Red 238, Pigment Red 266, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 5:4, Pigment Blue 61, Pigment Green 7, Pigment Green 36, Pigment Violet 1, Pigment Violet 19, Pigment Violet 23, Pigment Black 7, and the group consisting of titanium dioxide, zinc oxide, barium sulfate, zinc sulfide, zinc barium white, or calcium carbonate modified with anatase or rutile.

[0100] Preferably, the ink composition according to the invention contains 5-40% of one or more colorants, more preferably 10-30% of one or more colorants.

[0101] additive

[0102] The LED-curable inks of this invention may also contain additives commonly used in the art to modify the flowability, surface tension, gloss, fluidity, pigment wetting, and abrasion resistance of the cured coating or printing ink. Such additives in inks or varnishes are typically surfactants, waxes (e.g., PE waxes), shelf-life stabilizers, and combinations thereof. These additives can be used as leveling agents, shelf-life stabilizers, wetting agents, slip agents, flow agents, dispersants, and degassing agents. In some embodiments, the additives include fluorocarbon surfactants, silicones, and organic polymer surfactants. Examples include the Tegorad product line (Tegorad is a trademark and a commercially available product of Tego Chemie GmbH, Essen, Germany) and the Solsperse product line (Solsperse is a trademark and a commercially available product of Lubrizol GmbH).

[0103] The LED-curable ink of the present invention may also contain expanders commonly used in the art, such as clay, talc (e.g., micronized talc), calcium carbonate, magnesium carbonate, or silica, to adjust water absorption and color intensity. The ink of the present invention may also contain additives to modify the properties of the printing ink, such as surface tension, gloss, flowability, pigment wetting, and abrasion resistance.

[0104] Preferably, the ink or varnish composition of the present invention contains no more than 5% by weight of vegetable oil and / or mineral oil. More preferably, the ink or varnish composition of the present invention contains no more than 3% by weight, and even more preferably no more than 1.5% by weight of vegetable oil and / or mineral oil.

[0105] Unless otherwise stated, "vegetable oil" and "mineral oil" refer to non-functionalized oils. That is, unless a vegetable oil is described as functionalized (e.g., acrylated epoxidized vegetable oil), the term "vegetable oil" refers to oil derived from other parts of seeds or fruits that have not been functionalized (e.g., through chemical reactions) to include portions that can participate in polymerization processes. Similarly, the term "mineral oil" refers to petroleum hydrocarbon oils that have not undergone any functionalization (e.g., through chemical reactions) to include portions that can participate in polymerization processes.

[0106] Preferably, the ink or varnish composition of the present invention contains no more than 5% by weight of vegetable oil, said vegetable oil being selected from soybean oil, linseed oil, castor oil, or combinations thereof. More preferably, the ink or varnish composition of the present invention contains no more than 3% by weight, or even more preferably no more than 1.5% by weight of vegetable oil, said vegetable oil being selected from soybean oil, linseed oil, castor oil, or combinations thereof.

[0107] Preferably, the ink or varnish composition of the present invention contains no more than 5% by weight of mineral oil. More preferably, the ink or varnish composition of the present invention contains no more than 3% by weight, and even more preferably no more than 1.5% by weight of mineral oil.

[0108] Preferably, the ink or varnish composition of the present invention contains no more than 15% by weight of an organic solvent commonly used in UV-curable ink compositions. For example, the ink or varnish composition of the present invention contains no more than 15% by weight of an alcohol solvent, such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerol, or combinations thereof.

[0109] Typically, the ink of this invention exhibits a viscosity of approximately 5-100 Pa·s and a shear rate of D = 50 1 / s at 23°C, measured using a commercial cone-plate rheometer, such as the Physika RCS 300 from Anton Paar GmbH (a typical stress rheometer widely used in quality control and R&D). Preferably, the ink has a viscosity of approximately 40-60 Pa·s and a shear rate of D = 50 1 / s at 23°C.

[0110] Measured with a tilted aluminum plate containing 1cc of ink, the typical value of ink flow (tilt plate flow) after 15 minutes is approximately 3-15 cm.

[0111] Preferably, the ink of the present invention exhibits an tackiness of 200-450 units, measured using a "tack-o scope" instrument (model 2001) of the Dutch IGT testing system, known to those skilled in the art. More preferably, the tackiness is about 230-350 units. Darker colors are generally adjusted to achieve higher tackiness.

[0112] The radiation-curable ink of the present invention can be cured by LED light. The wavelength of the applied LED irradiation can be in the range of about 200 to 500 nm or about 320 to 400 nm. Preferably, the LED energy is about 30 to 1000 mJ / cm². 2 Within the range, or approximately 50 to 500 mJ / cm 2 Within the relevant UVA region. The values ​​are measured using a calibrated radiometer, such as the Powerpuck II from EIT, which exhibits good response in the associated UVA region. Furthermore, the LED source can be appropriately selected based on the absorption spectrum of the radiation-curable composition. Additionally, the ink of this invention can be cured under inert conditions or as an ink laminated with a plastic foil.

[0113] In another embodiment, the photoinitiator can be removed, and the varnishes and inks of the present invention can be cured by electron beam radiation (EB) (i.e., the ink or varnish composition contains 0% photoinitiator). Commercially available EB dryers are available, for example, from Energy Science, Inc., Wilmington, Massachusetts, or Advanced Electron Beams Inc., Wilmington, Massachusetts. The absorbed energy, also known as the dose, is measured in kilogrelides (kGy), where 1 kGy equals 1000 joules per kilogram. Typically, for complete curing, the electron beam dose should be in the range of 10 kGy to about 40 kGy. In the case of the radiation-curable compositions of the present invention, a radiation dose of 20-30 kGy is generally sufficient to obtain dry, solvent-resistant inks at an oxygen level of <200 ppm.

[0114] Unless otherwise stated, all percentages (%) are by weight.

[0115] Substrate

[0116] The substrate to be printed can be made of any typical substrate material, such as paper, plastic, metal and composite materials.

[0117] Test methods

[0118] molecular weight

[0119] Typically, molecular weight can be measured using techniques known in the art, such as gel permeation chromatography. For example, molecular weight determination can be performed on a HP 1050 Series HPLC system equipped with two GPC Ultrastyragel 103 columns and... (5 μm mix, 300 mm × 19 mm, Waters Millipore Corporation, Milford, Massachusetts, USA) and THF as the mobile phase. Molecular weight can be calculated by comparison with polystyrene standards. Those skilled in the art will understand that this definition of molecular weight applies to polymeric materials that typically have a molecular weight distribution. Generally, unless otherwise specified, the reported molecular weight (or average molecular weight) is weight-average molecular weight (Mw).

[0120] Acid value of rosin resin

[0121] Weigh 0.2–1.0 g of sample into a clean 50 ml Erlenmeyer flask. Dissolve the sample in acetone (10–20 ml). Carefully check that all sample material has dissolved. Add 3–5 drops of 1% ethanol phenolphthalein solution. More indicator solution may be needed for colored solutions. Titrate with standardized 0.1 N potassium ethanol hydroxide (KOH) until the first pink color appears, which lasts for 15 seconds. Record the volume of KOH solution used (ml).

[0122] calculate:

[0123]

[0124] Softening point of rosin resin

[0125] Mettler Drop Point Softening Point (MDSP): The softening point can be measured using a Mettler Toledo DP70 automatic softening point detector. Alternatively, the softening point is determined using the Durand method: 3 g of rosin resin is placed in a 17 × 50 ml test tube and heated to melt the resin. After the resin has cooled to room temperature, 50.0 g of mercury is added to the test tube, and a thermometer is inserted into the mercury. The test tube is heated in a bath at a rate of approximately 2 °C / min. The temperature at which the resin first appears above the surface of the mercury is taken as the softening point.

[0126] ethanol value

[0127] Unless otherwise specified, the ethanol value can be measured by weighing 10g of test resin into an Erlenmeyer flask. The resin is then dissolved in 50g of toluene at a high temperature of ≤80°C. Once all the resin has dissolved, the solution is cooled to room temperature (23°C), and the Erlenmeyer flask is weighed to obtain “Weight 1” (in grams). The Erlenmeyer flask is placed on a piece of white paper with text on it. Ethanol is then added dropwise to the Erlenmeyer flask at room temperature with stirring until the solution becomes cloudy and the text on the paper is no longer visible. When the text is no longer visible, the titration is stopped, and the Erlenmeyer flask is weighed again to obtain “Weight 2” (in grams). The ethanol value is then calculated by subtracting “Weight 1” from “Weight 2” and is expressed as g / 10g (i.e., grams of ethanol per 10g of resin).

[0128] Fineness of ink grinding

[0129] Ensure the grinding gauge (25μm / 0-10NIPRI) is clean and dust-free; it must be wiped with a solvent-soaked cloth before starting the test. Apply paint in both channels at 25μm marks. Ensure the color sample is free of any skin or large particles. The grinding gauge block should be placed on a flat surface, not sliding. Place the scraper vertically on the grinding gauge block, with your hands at right angles to the block. Then slowly pull the paint down to the end of the grinding gauge. The blade should be pressed against the grinding gauge to almost completely remove ink from both sides. Record the μm reading on the grinding gauge; at this reading, at least four scratches caused by larger ink particles should appear.

[0130] Viscosity

[0131] Unless otherwise specified, the viscosity of varnishes and inks was measured using a Physika 300 cone-plate rheometer from Anton Paar at a shear rate of D = 2-100 1 / s. Viscosity values ​​(Pa·s) were recorded at shear rates of D = 2 1 / s (low shear) and D = 50 (high shear). Unless otherwise specified, viscosity was measured at 23°C at a shear rate of D = 50 1 / s.

[0132] Adhesion

[0133] Adhesion was measured using a calibrated "Tack-o-scope" instrument (model 2001) from IGT Testing Systems, Netherlands. 1 ml of ink was placed on an EPDM rubber dispensing roller at 30°C and dispensed for 90 seconds at a roller speed of 50 rpm, followed by 30 seconds at a roller speed of 300 rpm. Adhesion values ​​were then measured at a roller speed of 150 rpm.

[0134] Ink Flow

[0135] The flowability was measured using vertically arranged aluminum plates. 1 ml of ink was placed on each plate. The distance (in cm) the ink flowed down the plate after 15 minutes was recorded.

[0136] Printing press performance and verification of the ink of this invention

[0137] To further demonstrate the printing press performance and printing performance of the ink of the present invention compared with that of the comparative ink, the ink was printed on a ManRoland 700 4-color sheet-fed offset UV printing press from AMS equipped with two LED dryers (power: 17W / cm). 2(At wavelengths of 385-395nm). The printing test format (the motivation for the printing plate) is a multicolor design with different images, reflecting the challenges that offset printing may face (e.g., high ink coverage, low ink coverage, grayscale, color intensity, clear printing, etc.). The special images used were provided by the FOGRA Institute of Graphic Arts in Munich, Germany. The target optical density was: black = 1.75; cyan = 1.40; magenta = 1.40; yellow = 1.30). For the printing test, an optical density of 130g / m² was selected. 2 Arto magic gloss graphic paper with a gram weight.

[0138] The printing press performance was evaluated by the press operator using a scoring system. 100 points signified excellent performance. For each printing problem that occurred on the press, the operator deducted points. Finally, all remaining points were added together to arrive at the final score. The tests included LED drying performance, print quality, and press performance, which will be described in detail below.

[0139] The drying performance, solvent resistance, permanganate staining, and ink smudging of LED inks were tested and rated.

[0140] Solvent resistance

[0141] Solvent resistance is assessed by rubbing the cured ink onto the printed material with a damp cotton cloth soaked in isopropyl alcohol until the ink layer is worn through. The more rubbings required to wear through the ink, the better the solvent resistance and curing performance, and the higher the score. The test stops at 100 rubs, as this indicates near-perfect curing results and is awarded 100 points. The worst score is solvent resistance at 0-5 rubs, resulting in a deduction of 20 points from 100 for each color.

[0142] Potassium permanganate staining

[0143] Place a drop of aqueous potassium permanganate solution (5%) on a selected color area on a substrate that has been printed and dried with LEDs for 5 seconds. Then, wipe off the drop and measure the optical density of the remaining stain. The darker the stain (density), the more uncured residual double bonds remain in the dried color. No staining means no penalty; for a spot with an optical density >0.25, deduct 25 points from 100.

[0144] Anti-sticking and dirt resistance

[0145] After the LEDs have dried, place counter paper on the printing surface at 10t / cm. 2The pressure is applied to the printed material. Then, the counting paper is removed and the ink smudges on the paper are inspected. No ink smudges are considered excellent, and ink smudges with a density >0.2 are considered poor results. No points are deducted for no ink smudges; the worst score is a smudge density >0.2, and 20 points are deducted from 100. More detailed smudge scoring is shown in Table 1.

[0146] Table 1: Stickiness Score

[0147]

[0148] For the quality of printed materials, assess their abrasion resistance and gloss.

[0149] abrasion resistance

[0150] The printed ink was placed on a Sutherland abrasion tester and rubbed against the surface with counting paper for a defined period of time. The amount of ink rubbed off was visually inspected, and a score was given using a comparison method from excellent to worst. The lower the ink damage and the less ink rubbed off, the higher the score. Results were rated from 0 (best) to 10 (worst). 0 or 1 indicates no points are deducted, and 10 indicates 20 points are deducted from 100 for each ink. More detailed abrasion resistance ratings are shown in Table 2.

[0151] Table 2: Abrasion Resistance Rating

[0152]

[0153]

[0154] gloss

[0155] Gloss was measured using a BYK mini gloss meter at 60°. Higher gloss results in a higher score. One unit of gloss on the gloss meter equals one score point. The average value for all four process colors was recorded.

[0156] Ink performance on a printing press is evaluated by assessing ink pipe flow, ink splatter, and overall offset printing performance.

[0157] Pipeline fluidity

[0158] Pipe flowability is assessed based on the degree to which ink exits the ink pipe without additional forced agitation. If ink does not exit the ink pipe correctly, its delivery through the ink roller system may be slowed or interrupted. Ink pipe flowability is rated by printing press operators in the art from 0 (best) to 5 (worst). The better the ink pipe flowability, the higher the score. For excellent flowability exiting the ink pipe, no points are deducted from 100; for poor flowability, 22 points are deducted from 100 for each ink. More detailed pipe flowability ratings are shown in Table 3.

[0159] Table 3: Pipeline Flowability Score

[0160]

[0161] Feimo

[0162] Ink splatter can be a serious problem during printing operations, as it contaminates the printing press, leading to frequent production stops for cleaning. Furthermore, it can pose a health hazard when tiny acrylic droplets enter the air. While press setup and roller diameter can play a role, the chemistry of the ink is considered a crucial factor. Ink splatter is determined by placing a blank paper substrate close to a selected roller and allowing a defined amount of time for the ink mist generated from the roller to deposit on the blank paper. The amount of ink on the paper is then determined by visual comparison or by measuring with a densitometer. The less ink mist deposited on the paper, the better the "ink splatter" performance, and the higher the score. Ink splatter is rated from 0 (best) (meaning no points are deducted) to 5 (worst) (where -20 points are deducted from 100 for each color). More detailed ink splatter ratings are shown in Table 4.

[0163] Table 4: Feimo Rating

[0164]

[0165] Lithographic printing performance

[0166] Overall offset printing performance is assessed based on key requirements and potential printing problems that may occur on sheet-fed offset presses, such as ink / water balance, scumming, picking, smudging by another color, over-emulsification, ink in the dampening train, framing, and ink buildup, as described below. These problems are known to those skilled in the art and are rated by comparison, with scores assigned based on the procedures mentioned below. Finally, the scores for each offset printing-related result are summed to obtain the overall offset printing performance score. The various requirements for offset printing performance are described below.

[0167] Ink / Water Balance

[0168] The goal is to print offset inks with the lowest possible amount of dampening solution while the printing plate remains free-flowing. Ink / water balance can also be described using the term "water window." It is identified by the maximum possible range of ink and water settings on the printing press within which the ink can still operate stably. Ink / water balance is rated by the printing press operator on a scale of 0-5, where zero (best) deducts no points; 5 (worst) means deducting 20 points from 100 for each color.

[0169] Blur

[0170] Dampening occurs when the dampening solution fails to keep the non-image areas of the printing plate clean. Dampening is rated by the printing press operator on a scale of 0-5, with 0 (best) indicating no damage and no points deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0171] La Mao

[0172] Roughing refers to ink tearing off fibers or the paper coating from the paper substrate. Roughing is rated by printing press operators on a scale of 0-5, with 0 (best) indicating no roughing and no points deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0173] Dirty by another color

[0174] During printing tests, one ink may be contaminated by another, which can result in a hue shift that can be detected on the printout via a shift in chromaticity data. Contamination is rated from 0 to 5 by the printing press operator, where zero (best) indicates no contamination and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0175] Over-emulsification

[0176] If the ink absorbs too much water, it will produce a frayed ink coating on the ink train rollers. Over-emulsification is rated by printing press operators on a scale of 0-5, where zero (best) means no over-emulsification and therefore no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0177] Ink in the dampening wheel system

[0178] The ink in the dampening wheel system is visually inspected, and the printing press operator rates it from 0 to 5, where 0 (best) means there is no ink in the dampening wheel system, so no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0179] Frame

[0180] Framed printing refers to the visible ink outside and around the area to be printed. Framed printing is rated by the printing press operator on a scale of 0-5, where 0 (best) means no framed printing and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0181] Ink buildup

[0182] Ink can accumulate on rollers, blankets, and plates, resulting in dried ink build-ups. Accumulation is rated by the printing press operator on a scale of 0-5, where zero (best) indicates no accumulation and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0183] As mentioned earlier, the score points for each test result are summed to obtain the overall final score. For better visual understanding, the individual results can be depicted in a spider diagram.

[0184] like Figure 1 As shown, the spider diagram illustrates the ink performance scores of Examples 2A-5A and the comparative examples of the present invention. Actual scores are also given in the examples.

[0185] The present invention is further described by the following numbered paragraphs:

[0186] 1. A printing ink or varnish composition comprising:

[0187] 25-85% of one or more acrylates;

[0188] 0-20% of one or more photoinitiators;

[0189] 5-60% of one or more rosin-modified polyester resins;

[0190] 0.2-5% of one or more aluminum additives;

[0191] 0.1-5% of one or more polymerization stabilizers; and

[0192] 0-50% colorant.

[0193] 2. The composition according to paragraph 1, wherein the composition is curable by UV-LED radiation.

[0194] 3. The composition according to paragraph 1 or 2, wherein the composition comprises 0.5-20% of one or more photoinitiators.

[0195] 4. The composition according to paragraph 1, wherein the photoinitiator is removed and the composition is curable by electron beam radiation.

[0196] 5. The composition according to the preceding paragraph, wherein the composition is offset printing ink or varnish.

[0197] 6. The composition according to any one of the preceding paragraphs, wherein at least one of the photoinitiators is selected from the group consisting of thioxanthone, acylphosphine oxide, aminobenzophenone, aminoalkylphenyl ketone, ketocoumarin, or mixtures thereof.

[0198] 7. The composition according to any one of the preceding paragraphs, wherein the aluminum additive is selected from the group consisting of aluminum alkoxides, aluminum chelates, aluminum carboxylate, or blends thereof.

[0199] 8. The composition according to paragraph 7, wherein the aluminum additive is an aluminum alkoxide selected from the group consisting of aluminum monopropoxy, aluminum dipropoxy, or aluminum tripropoxy; aluminum monoisopropoxy, aluminum diisopropoxy, or aluminum triisopropoxy; aluminum monobutyrate, aluminum dibutyrate, or aluminum tributyrate; aluminum monoisobutyrate, aluminum diisobutyrate, or aluminum triisobutyrate; and blends thereof.

[0200] 9. The composition according to paragraph 7, wherein the aluminum additive is an aluminum chelate selected from the group consisting of chelates of ethylaluminum monoacetoacetate with diisopropanol; dichelates and trichelates of aluminum with alkyl acetoacetate esters or alkyl diketones, and blends thereof; or

[0201] 10. The composition according to paragraph 7, wherein the aluminum additive is aluminum carboxylate, the aluminum carboxylate being selected from the group consisting of aluminum triacetate or aluminum tripropionate and blends thereof.

[0202] 11. The composition according to paragraphs 1-7 or 9, wherein the aluminum additive is aluminum acetoacetate diisopropoxy.

[0203] 12. The composition according to any one of the preceding paragraphs, wherein the rosin-modified polyester resin is derived from the group consisting of: lipid rosin, tall oil rosin, monofunctional polyol, difunctional polyol, trifunctional polyol or tetrafunctional polyol, monofunctional acid, difunctional acid, trifunctional acid or tetrafunctional acid or anhydride, and blends thereof.

[0204] 13. The composition according to any one of paragraphs 1-11, wherein the rosin-modified polyester resin is derived from a source selected from the group consisting of rosin, maleic anhydride, fumaric acid, glycerol, pentaerythritol and blends thereof.

[0205] 14. The composition according to any one of paragraphs 1-11, wherein the rosin-modified polyester resin is derived from a source selected from the group consisting of tetrahydrophthalic anhydride, glycerol, aromatic monofunctional acids, monofunctional alcohols and blends thereof.

[0206] 15. The composition according to any one of the preceding paragraphs, wherein the rosin-modified polyester resin has a molecular weight of 2,000-100,000 Daltons.

[0207] 16. The composition according to any one of the preceding paragraphs, wherein the rosin-modified polyester resin has an acid value of 5-50 mg KOH / g.

[0208] 17. The composition according to any one of the preceding paragraphs, wherein the softening point of the rosin is in the range of 70-135°C or 85-110°C.

[0209] 18. An LED-curable offset printing ink or coating composition, which is or comprises the composition described in any one or more of paragraphs 1-17.

[0210] 19. The composition according to paragraph 18, comprising one or more colorants.

[0211] 20. The composition according to paragraph 18 or 19, wherein the composition comprises 25-85% of the varnish according to any one or more of paragraphs 1-17.

[0212] 21. The composition according to any one of the preceding paragraphs has an improvement of ≥5% in ink and printing press performance scores compared to a comparative example without aluminum additives.

[0213] 22. The composition according to any one of the preceding paragraphs has an improvement of ≥10% in ink and printing press performance scores compared to a comparative example without aluminum additives.

[0214] 23. The composition according to any one of the preceding paragraphs has an improvement of ≥15% in ink and printing press performance scores compared to a comparative example without aluminum additives.

[0215] 24. A printed article comprising the composition according to any one or more of paragraphs 1-23.

[0216] 25. A method for preparing printed matter, comprising:

[0217] Applying the composition according to any one or more of paragraphs 1-23 onto a substrate by offset printing; and

[0218] The composition is cured by UV-LED or electron beam.

[0219] The present invention, including its various embodiments, has been described in detail. However, it should be understood that those skilled in the art, upon considering this disclosure, can make modifications and / or improvements to the invention within its scope and spirit.

[0220] Example

[0221] The invention is further described by way of the following non-limiting embodiments, which further illustrate the invention and are not intended to, nor should be construed as, limiting the scope of the invention.

[0222] Rosin solubility

[0223] Prior to preparing the varnish and ink compositions of the present invention, the solubility of various rosin resins was determined. As can be seen from the data in Table 5 below, while rosin resins with molecular weights of 50,000 and 40,000 Daltons are soluble in bis(trimethylolpropane)tetraacrylate (DiTMTPA), they are insoluble in dipentaerythritol hexaacrylate (DPHA). Only when the molecular weight decreases are rosin resins soluble in hexafunctional acrylates and dipentaerythritol hexaacrylate.

[0224] Table 5: Rosin Solubility

[0225]

[0226]

[0227] 1 The rosin resin is described as soluble, wherein a 50% by weight solution of the rosin resin in the functional acrylate at room temperature (i.e., 20°C) did not show visible precipitation after 24 hours.

[0228] The inks of this invention and the comparative inks of this application are prepared by a two-step process: a premix is ​​prepared at 40-60°C as described, followed by milling on a three-roll mill until a suitable pigment particle size (bulk particles <10 μm) is achieved. After milling, the inks are ready for printing. The inks of this invention and the comparative inks have a viscosity of 40-60 Pa·s, a tilt plate flowability of 3-15 cm, and an adhesion of 230-330 units.

[0229] Table 6: Comparison of the varnish of the present invention in Example 1A and that in Example 1B (materials are expressed in weight %)

[0230]

[0231] The varnish of Comparative Example 1B has a viscosity of about 65 Pa·s, exhibiting almost Newtonian behavior, while the varnish of Example 1A of the present invention has a slightly higher viscosity of about 75 Pa·s and exhibits even higher viscosity at low shear rates (“more structure”).

[0232] Table 7: Yellow ink Example 2A of the present invention and comparative yellow ink Example 2B

[0233]

[0234]

[0235] Table 8: Example 3A of the Magenta Ink of the Present Invention and Example 3B of the Comparative Magenta Ink

[0236]

[0237] Table 9: Cyan ink Example 4A and comparative cyan ink Example 4B of the present invention

[0238]

[0239]

[0240] Table 10: Example 5A of the black ink of the present invention and Example 5B of the comparative black ink

[0241]

[0242]

[0243] Table 11 summarizes the performance scores of Examples 2A-5A and Comparative Examples 2B-5B of the present invention.

[0244] Table 11: Printing press performance and printing performance (scores) of the ink examples of the present invention (containing aluminum additive) and the comparative ink examples (without aluminum additive).

[0245]

[0246] Table 11 clearly shows that, compared to the comparative inks, the aluminum additive improves overall performance (particularly lithographic printing performance) and reduces ink fly (higher score) in the inks of this invention. Although the aluminum additive is incorporated into the varnish in the examples, it should be understood that aluminum can be readily added directly to the ink itself.

[0247] To provide a better visual understanding, the results can be depicted in a spider diagram. The spider diagram illustrates the ink performance scores of Examples 2A-5A and Comparative Examples 2B-5B of the present invention.

[0248] exist Figure 1 In the spider diagram, it can be clearly observed that the four-color ink set of the present invention (outer curve shape) containing aluminum additives covers more graph space compared to the comparative ink set (inner curve shape), which means that it is a better performing ink, especially in terms of ink splatter, lithographic printing performance and ink drying, as evaluated by solvent resistance and smudge tests.

[0249] The present invention, including its various embodiments, has been described in detail. However, it should be understood that those skilled in the art, upon considering this disclosure, can make modifications and / or improvements to the invention within its scope and spirit.

Claims

1. A printing ink or varnish composition comprising: 25-85% of one or more acrylates, wherein at least one acrylate is a pentaacrylate or a hexaacrylate; 0-20% of one or more photoinitiators; 5-60% of one or more rosin-modified polyester resins, wherein the rosin-modified polyester resin has a molecular weight of 5,000 to 35,000 Daltons. 0.2-5% of one or more aluminum additives; 0.1-5% of one or more polymerization stabilizers; and 0-50% colorant; The rosin-modified polyester resin is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid.

2. The composition according to claim 1, wherein the rosin-modified polyester resin has an acid value of 10-30 mgKOH / g.

3. The composition according to claim 1 or 2, wherein the rosin-modified polyester resin has a softening point of 85-110°C.

4. The composition according to claim 1, wherein the rosin-modified polyester resin has a molecular weight of 5,000 to 35,000 Daltons, an acid value of 10-30 mgKOH / g, and a softening point of 85-110°C.

5. The composition according to claim 1, wherein the composition comprises not more than 5% vegetable oil and / or mineral oil.

6. The composition according to claim 1, wherein at least one acrylate is a pentaacrylate.

7. The composition according to claim 6, wherein the pentaacrylate is dipentaerythritol pentaacrylate.

8. The composition according to claim 1, wherein at least one acrylate is a hexaacrylate.

9. The composition according to claim 8, wherein the hexaacrylate is dipentaerythritol hexaacrylate.

10. The composition according to claim 1, wherein the composition is curable by UV-LED radiation.

11. The composition according to claim 1, wherein the composition comprises 0.5-20% of one or more photoinitiators.

12. The composition of claim 1, wherein the composition contains 0% photoinitiator (i.e., the composition does not contain photoinitiator), and the composition is curable by electron beam radiation.

13. The composition according to claim 1, wherein the composition is offset printing ink or varnish.

14. The composition according to claim 1, wherein at least one of the photoinitiators is selected from the group consisting of thioxanthone, acylphosphine oxide, aminobenzophenone, aminoalkylphenyl ketone, ketocoumarin, or mixtures thereof.

15. The composition according to claim 1, wherein the aluminum additive is selected from the group consisting of aluminum alkoxides, aluminum chelates, aluminum carboxylate, or blends thereof.

16. The composition according to claim 15, wherein the aluminum additive is: (a) An aluminum alkoxide selected from the group consisting of aluminum monopropoxy, aluminum dipropoxy or aluminum tripropoxy; aluminum monoisopropoxy, aluminum diisopropoxy or aluminum triisopropoxy; aluminum monobutyrate, aluminum dibutyrate or aluminum tributyrate; aluminum monoisobutyrate, aluminum diisobutyrate or aluminum triisobutyrate; and blends thereof. (b) An aluminum chelate, said aluminum chelate being selected from the group consisting of chelates of ethylaluminum monoacetoacetate with diisopropanol; dichelates and trichelates of aluminum with alkyl esters or alkyl diketones of acetoacetate, and blends thereof; or (c) Aluminum carboxylate, wherein the aluminum carboxylate is selected from the group consisting of aluminum triacetate or aluminum tripropionate and blends thereof.

17. The composition according to claim 1, wherein the aluminum additive is aluminum acetoacetate diisopropoxy.

18. The composition of claim 1, wherein the aluminum additive is in an inert solvent, wherein the inert solvent is selected from mineral oil or vegetable oil.

19. The composition according to claim 18, wherein the inert solvent is sunflower oil.

20. The composition according to claim 19, wherein the aluminum additive is ethyl acetoacetate diisopropoxyaluminum in sunflower oil.

21. The composition according to claim 1, wherein the rosin-modified polyester resin is derived from: i) rosin, wood rosin, or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols, or tetrafunctional polyols selected from glycerol or trimethylolpropane; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid, and tert-butylbenzoic acid.

22. The composition of claim 21, wherein the rosin-modified polyester resin is derived from: i) rosin or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols or tetrafunctional polyols selected from glycerol or trimethylolpropane; and iv) one or more monofunctional acids selected from benzoic acid, methylbenzoic acid and tert-butylbenzoic acid.

23. The composition of claim 21, wherein the rosin-modified polyester resin is derived from: i) rosin or tall oil rosin; ii) one or more difunctional acids or anhydrides selected from cyclohexene dicarboxylic acid dianhydride or methylcyclohexene dicarboxylic acid dianhydride; iii) one or more monofunctional polyols, difunctional polyols, trifunctional polyols or tetrafunctional polyols selected from glycerol or trimethylolpropane; and iv) benzoic acid.

24. The composition according to claim 1, wherein: (a) The rosin-modified polyester resin has a molecular weight of 8,000-35,000 Daltons; and / or (b) The rosin-modified polyester resin has an acid value of 12-25 mg KOH / g.

25. The composition of claim 1, wherein the rosin-modified polyester has an ethanol value of >4 g / 10 g.

26. The composition of claim 25, wherein the rosin-modified polyester has an ethanol value of 4-10 g / 10 g.

27. The composition according to claim 1, compared with a comparative example without aluminum additive, has an improvement of ≥5% in ink and printing press performance scores.

28. The composition according to claim 27, compared with a comparative example without aluminum additive, has an improvement of ≥10% in ink and printing press performance scores.

29. The composition according to claim 28, compared with a comparative example without aluminum additive, has an improvement of ≥15% in ink and printing press performance scores.

30. An LED-curable offset printing ink or coating composition, which is or comprises a varnish composition according to any one of claims 1-29.

31. The ink or coating composition according to claim 30, comprising 5-40% of one or more colorants.

32. The ink or coating composition according to claim 30 or 31, comprising 25-85% of the composition according to any one of claims 1-29.

33. A printed article comprising the composition according to any one of claims 1-32.

34. A method for preparing printed matter, comprising: The composition according to any one of claims 1-32 is applied to a substrate by offset printing; and The composition is cured by UV-LED or electron beam.

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