LED curable offset inks containing aluminum additives

Abstract

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

Description

Technical Field

[0001] The present invention relates to LED-curable printing ink or varnish compositions suitable for offset printing. In particular, the present invention relates to LED-curable varnishes and inks applied by offset printing comprising an aluminum additive.

[0002] The inks and varnishes of the present 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 products comprising or derived from the ink or varnish composition of the present invention, which are suitable for graphic applications and packaging applications. Background Art

[0004] The use of UV-LED lamps for curing has increased as the technology offers various advantages such as: energy saving; extended life compared to conventional UV bulbs; and a safe, mercury-free product. In addition, UV-LED lamps do not produce ozone, in contrast to typical mercury UV bulbs that have been the state-of-the-art in UV technology for many years.

[0005] In the graphic arts sector, printing presses are therefore increasingly equipped or retrofitted with compact UV-LED dryers. State-of-the-art LED dryers typically emit LED light with a peak wavelength of 365-405nm.

[0006] LED offset inks are state-of-the-art technology that can be printed, for example, on sheet-fed or web-fed presses equipped with LED dryers. Compared to solvent-based inks or inks based on vegetable or mineral oils, they combine the above-mentioned advantages of LED drying (i.e. LED curing) with sustainable (A-free, i.e. solvent-free) application and fast drying (high productivity).

[0007] However, similar to UV inks, UV-LED inks generally exhibit poor lithographic press performance compared to conventional inks based on vegetable or mineral oils. One reason for this behavior is attributed to the higher polarity of acrylates compared to oils, which makes UV-LED inks more polar, adversely affecting the lithographic process and jet interaction.

[0008] Another disadvantage of UV-LED technology can also be poor surface curing caused by oxygen inhibition. Oxygen inhibition refers to the fact that oxygen, as a diradical, can easily react with radicals formed by the photoinitiator or on the monomer or growing polymer chain and deactivate them (usually in the form of peroxide derivatives). This can lead to insufficient drying of the ink or coating surface where oxygen dominates. This is particularly problematic for commercial long wavelength UV-LED light dryers emitting at 365-405nm, because the shorter wavelengths (which are very helpful for good surface curing and activation of photoinitiator radicals at or near the surface) are missing.

[0009] This can often be counteracted by using a very reactive multifunctional monomer such as dipentaerythritol hexaacrylate, thereby increasing the polymerization rate rather than oxygen inhibiting the process.

[0010] However, the widespread use of multifunctional monomers (such as dipentaerythritol hexaacrylate) imparts high crosslink density, which usually makes the ink brittle, which has an adverse effect on adhesion. In addition, such acrylate monomers can also lead to poor printing performance.

[0011] In order to give UV inks better lithographic properties and reduce brittleness, rosin resins successfully used in conventional inks can also be used in UV inks (such as in US 5,212,213 or US 7,232,861 and EP 3433711), provided that they show sufficient solubility in acrylates.

[0012] US 5,212,213 mentions the use of fully fumarated rosin and / or fully maleated rosin to produce higher softening points and allow the production of 100% solid resins. In the present invention, the risk of polymerization during the ink or varnish manufacturing process is higher due to high temperatures or extended dissolution times, so the temperature is kept as low as possible while still remaining above the threshold for dissolving the rosin in the acrylate.

[0013] US 7,232,851 mentions an electron beam and / or UV curable lithographic ink composition and printing method which uses only rosin which is generally soluble in acrylates, but the present invention requires that the rosin also exhibits good solubility in high-functional acrylates which are particularly suitable for LED inks, such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. Specifically, the rosin used in the present 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 using high temperatures (i.e., temperatures above 135° C.).

[0014] Another problem associated with the press performance of UV and LED inks is the so-called ink flying. During the printing process, due to the strong centrifugal forces of the rapidly rotating rollers and the limited cohesion of the ink, small ink droplets escape from the fast-running rollers in the form of mist and contaminate the printing press, resulting in frequent large-scale cleaning work and production stops. Typical measures to reduce ink flying are to increase the solid content of the ink by adding fillers or increasing the pigmentation.

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

[0016] EP3434711 mentions the use of rosin esters in energy curable (EC) inks. There is no mention of LEDs, aluminum additives, or improvement of ink flying by aluminum additives. Summary of the invention

[0017] The object of the present application is to provide an LED curable offset printing ink which exhibits a low tendency to fly off the offset printing press while maintaining excellent press performance and LED drying properties.

[0018] Citation or identification of any document in this application does not constitute an admission that such document represents prior art to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a spider web plot of the inventive ink (with aluminum additive, outer curve shape) and the comparative ink (without aluminum additive, inner curve shape). In particular, the spider web plot shows the ink performance scores of the inventive examples 2A-5A and the comparative examples 2B-5B. DETAILED DESCRIPTION

[0020] The present invention is further illustrated by the following set of embodiments and combinations of embodiments, which are generated by, for example, the indicated dependencies and back-references. In particular, it should be noted that in each case where a series of embodiments is mentioned, for example in the context of a term such as "the method of any one of embodiments 1 to 5", each embodiment within the scope is meant to be clearly disclosed to the skilled person, i.e. the skilled person should understand the wording of the term as synonymous with "the method of any one of embodiments 1, 2, 3, 4 and 5".

[0021] The present 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 polymeric stabilizers; and

[0027] 0-50% colorant.

[0028] The ink or varnish composition according to the 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 polymeric stabilizers.

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

[0036] The inks are suitable for printing onto any lithographic substrate such as graphic papers, wrapping papers, and packaging applications on carton board and foils.

[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 a 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% of polymer stabilizer;

[0043] 0-50% colorant.

[0044] Acrylate

[0045] In one embodiment, (meth)acrylic acid (ie, (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 the present 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, bisphenol A diglycidyl ether diacrylate. Acid ester, ethoxylated bisphenol A diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, ethoxylated pentaerythritol triacrylate, propoxylated pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate or a mixture thereof, etc.

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

[0048] In one embodiment, the ink of the present invention may further comprise an acrylate oligomer. In one embodiment, the ink of the present invention may further comprise an acrylated oligomer having 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, acrylated polyethers, to impart rheology, pigment wetting, transfer, gloss, chemical resistance and other film properties.

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

[0051] Preferably, the ink or varnish composition of the present invention comprises hexaacrylate and at least one other acrylate selected from alkoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol tetraacrylate, ditrimethylolpropane 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 selected from alkoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, alkoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, alkoxylated dipentaerythritol hexaacrylate or mixtures thereof.

[0052] Preferably, the ink or varnish composition of the present invention comprises 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 invention comprises 25-60% of pentaacrylate or hexaacrylate.

[0054] Photoinitiator

[0055] The radiation curable ink of the present invention contains a photoinitiator absorbing in the UVA region at 320-400 nm, such as, for example, substituted benzophenones, aminoalkylphenyl ketones, acylphosphine oxides and thioxanthones, for example 4-thienylbenzophenone, 4,4'-bis(diethylamino)-benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-methyl-1-[4(methoxythio)-phenyl]-2-morpholinopropan-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, acetophenones (including aminoacetophenones), aminobenzoates, thioxanthones and combinations thereof.

[0057] For inks designed for food packaging, migratory low molecular weight monomeric photoinitiators are advantageously minimized or, more advantageously, replaced entirely by oligomeric or polymeric photoinitiators such as IGM Resins' Omnipol TX trademark.

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

[0059] Rosin resin

[0060] Rosin resin, such as for example maleic acid modified rosin ester or rosin resin modified by phenolic resin is widely used as printing ink medium in flexographic printing and gravure printing ink.Rosin ester modified by maleic acid usually shows good pigment wettability, glossiness retention, color retention and adhesion, and usually shows better solution in acrylate compared with rosin resin modified by phenolic resin.Rosin ester can be synthesized by commercial rosin (such as Chinese gum rosin, wood rosin or tall oil rosin) and difunctional acid (such as maleic acid, fumaric acid, itaconic acid) and trifunctional or tetrafunctional hydroxyl compound (such as glycerol, trimethylolpropane, pentaerythritol) etc.Rosin ester is commercially available, and can be prepared according to the description in " Printing Ink Manual ", the fifth edition, Blueprint, London.For example, the preparation of maleated rosin ester is specifically described in Example 1 of US2007232786. Typically, modified rosin esters are prepared by heating commercial rosin (eg, gum rosin) with a difunctional acid (eg, maleic acid) and a hydroxyl compound (eg, pentaerythritol) until the desired acid value (also called acid number) is obtained.

[0061] However, although rosin esters are known in the art, the rosin resin used in the present application should be soluble not only in general acrylates but also in high-functional acrylates particularly suitable for LED inks, such as dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate. As used herein, when a 30 wt % (preferably 40 wt %, even more preferably 50 wt %) solution of the rosin resin in a high-functional acrylate (particularly dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate) shows no visible precipitation at room temperature (i.e., 20° C.), the rosin resin has good solubility in the high-functional acrylate. For example, this can be achieved by appropriately selecting an acid (such as maleic acid or maleic anhydride or cyclohexene dicarboxylic dianhydride or methylcyclohexene dicarboxylic dianhydride) and a polyol (such as glycerol and trimethylolpropane) to provide better solubility and by limiting the molecular weight and softening point. To limit molecular weight and provide excellent solubility in acrylates, monofunctional acids such as benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphthoic acid or fatty acids such as linoleic acid may be added to the reaction mixture to control the condensation reaction and molecular weight.

[0062] Preferably, the rosin resin used in the present invention is derived from i) gum 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 dianhydride or methylcyclohexene dicarboxylic dianhydride. More preferably, the difunctional acid or anhydride is selected from cyclohexene dicarboxylic dianhydride or methylcyclohexene dicarboxylic 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. Still more preferably, the one or more monofunctional acids are benzoic acid.

[0066] Preferably, the rosin resin used in the present invention is derived from: i) gum 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, methyl benzoic acid, tert-butyl benzoic acid, naphthoic acid and linoleic acid. More preferably, the rosin resin used in the present invention is derived from: i) gum 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, methyl benzoic acid and tert-butyl benzoic acid.

[0067] Preferably, the rosin resin used in the present invention is derived from: i) gum 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, methyl benzoic acid, tert-butyl benzoic acid, naphthoic acid and linoleic acid. More preferably, the rosin resin used in the present invention is derived from: i) gum 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, methyl benzoic acid and tert-butyl benzoic acid.

[0068] Preferably, the rosin resin used in the present invention is derived from i) gum 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, methyl benzoic acid and tert-butyl benzoic acid.

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

[0070] In addition, the softening point of the rosin resin is important. The dropping point refers to the temperature at which the first drop of a molten material drips out of a standard cup with a defined orifice under controlled test conditions in a furnace. For example, it can be measured with an automated device such as DP70 from Mettler Toledo. Due to the risk of polymerization of acrylates at higher temperatures, the temperature range in which the ink or varnish of the present invention can be prepared is limited. If the rosin ester has a higher softening point, such as >135°C, it is difficult to dissolve in acrylates below 100°C, or it takes a long time. Unlike non-polymer materials, polymers do not dissolve instantly, and dissolution is controlled by the disentanglement of polymer chains. This means that the polymer must first swell 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 extended 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 the rosin resin should be tested to confirm that it has sufficient solubility to make inks or varnishes. Generally, the solubility of the rosin resin should be such that stable inks or varnishes are possible in dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate at concentrations >30 wt% or >40%. Stable means that there is no precipitation of the resin at lower storage temperatures and no polymerization of the ink or varnish at higher storage temperatures.

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

[0074] Surprisingly, the rosin resin used in the present invention is soluble in pentaacrylate and hexaacrylate monomers (e.g., dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate) without using 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, preferably 10,000-35,000 Daltons.

[0076] Rosin resins suitable for use in the present application that exhibit good solubility in dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate typically have a molecular weight of 5000-35000 or 5000-30000 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 5000-35000 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 5000-35000 Daltons, a softening point of 85-110° C., and an acid value of 12-25 mg KOH / g.

[0077] The rosin resin used in the present invention generally has an ethanol value of >4 g / 10 g. For example, the rosin resin used in the present invention generally has an ethanol value of 4-10 g / 10 g. As understood in the art, the ethanol value (EN) provides a measure of the tolerance of the resin to ethanol, and therefore provides an indication of the polarity of the resin.

[0078] Aluminum Additives

[0079] Aluminum additives suitable for the present application are aluminum alkoxides, aluminum chelates or aluminum carboxylates. Suitable aluminum alkoxides include monopropoxy aluminum, dipropoxy aluminum or tripropoxy aluminum, monoisopropoxy aluminum, diisopropoxy aluminum or triisopropoxy aluminum, monobutyrate aluminum, dibutyrate aluminum or tributyrate aluminum, monoisobutyrate aluminum, diisobutyrate aluminum or triisobutyrate aluminum, or blends thereof. Suitable aluminum chelates include chelates of monoethylaluminum acetoacetate and diisopropoxide, dichelates and trichelates of aluminum with alkyl acetoacetate or alkyl diketone, or blends thereof. Suitable aluminum carboxylates include the group consisting of 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 the group consisting of chelates of ethyl aluminum monoacetoacetate with diisopropoxide; di- and tri-chelates of aluminum with alkyl acetoacetates or alkyl diketones, or blends thereof.

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

[0082] Most of these aluminum additives are commercially available. In order to better handle moisture-sensitive additives (e.g., diisopropyl alcoholate chelates, which may be referred to as alcoholates) and to avoid hydrolysis decay, the aluminum additive may be pre-dissolved in an inert solvent, such as sunflower oil, in a small amount. Therefore, in a preferred aspect of the present invention, the aluminum additive is an aluminum alkoxide, an aluminum chelate or an aluminum carboxylate in an inert solvent. In the case of the aluminum additive in an inert solvent (such as sunflower oil), the weight ratio of the aluminum additive and the inert solvent is 1:1.

[0083] Suitable inert solvents include mineral oil 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 weight ratio of 1:1.

[0085] Preferably, the aluminum additive is an aluminum chelate in an inert solvent. More preferably, the aluminum additive is a chelate of ethylaluminum monoacetoacetate with diisopropoxide in an inert solvent; a di-chelate and tri-chelate of aluminum with alkyl acetoacetate, alkyl diketone, or a blend thereof.

[0086] Preferably, the aluminum additive is an aluminum chelate in sunflower oil. More preferably, the aluminum additive is a chelate of ethyl aluminum monoacetoacetate with diisopropoxide in sunflower oil; a di-chelate and a tri-chelate of aluminum with alkyl acetoacetate, alkyl diketone, or a blend 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 the present application, during the production of the ink or varnish at high temperatures of 80-120°C, the aluminum additive is able to react with hydroxyl, carboxyl and amine groups in the ink or varnish, which has a positive effect on the rheology, in particular on the structure or so-called bulk (viscosity at low shear rates, i.e. D=2 1 / s) of the ink made therefrom, and affects the cohesion of the ink.

[0089] In the present invention, the aluminum additive is present in 0.2-5% of the ink or varnish composition. Preferably, the aluminum additive is present in 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 comprises 0.2-5% of an aluminum additive in an inert solvent such as sunflower oil. Preferably, the weight ratio of the aluminum additive to the inert solvent is 1:1, so that the composition comprises 0.1-2.5% of an aluminum additive and 0.1-2.5% of an inert solvent.

[0091] Polymerization Stabilizers (also referred to herein as Polymerization Inhibitors)

[0092] The ink of the present invention may also contain a stabilizer to ensure a good shelf life. Examples of such polymerization inhibitors include nitroso-based stabilizers such as nitroso-phenylhydroxylamine; 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 nitroso-phenylhydroxylamine stabilizers; and stabilizers based on copper thiocarbamate and zinc thiocarbamate. Such components are useful as varnishes and inks because long-wave absorbing photoinitiators suitable for LED drying also absorb visible light, making them susceptible to premature polymerization.

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

[0094] Varnish preparation

[0095] For example, the varnish of the present invention is made, for example, by adding the liquid components and stabilizers to a stirred tank heated to 80-120°C, followed by the addition of solid rosin resin and optionally other solid additives. When the rosin resin is dissolved, the aluminum additive is added, the mixture is stirred for a defined time at a temperature, filtered, and can then be used to make LED-curable inks. The varnish is characterized by the viscosity at high and low shear rates measured with a rheometer (D=50 1 / s and D=2 1 / s, respectively), and can be further characterized by oscillation experiments to determine the storage modulus, loss modulus, and the ratio of storage modulus to loss modulus (tan δ), thereby describing the viscous and elastic parts of the varnish. The lower the tan δ, the higher the degree of reaction with the aluminum additive. Typically, 0.5-5.0 wt. % of the aluminum additive is added, depending on the desired viscosity and rheology of the varnish.

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

[0097] For example, the inventive ink of the present application can be made by a two-step process: preparation of a premix and grinding. The premix is ​​made by charging the varnish of the present invention and additional monomers into a stirred tank; stirring is initiated and then solid components such as colorants, fillers and additional additives are added. During mixing, the temperature is raised to 40-70°C and the mixture temperature is maintained until all pigments are wetted. The premix is ​​then transferred to a milling process (e.g., a three-roll mill or a bead mill) and ground until the desired fineness of grind as measured by a grinder (e.g., an NPIRI gauge) is achieved.

[0098] Colorants

[0099] The ink of the present invention may also contain one or more colorants dispersed therein in the form of dyes or pigments. Suitable pigments for use in the present invention include conventional organic or inorganic pigments. Representative pigments may be, for example, selected 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 Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 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, the group consisting of titanium dioxide modified with anatase or rutile thereof, zinc oxide, barium sulfate, zinc sulfide, lithopone or calcium carbonate.

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

[0101] additive

[0102] The LED-curable ink of the present invention can also contain additives commonly used in the art to change the fluidity, surface tension, glossiness, fluidity, pigment wettability and abrasion resistance of cured coating or printing ink. Such additives contained in ink or varnish are usually surfactants, waxes (such as PE wax), shelf life stabilizers, etc. and combinations thereof. The additive can be used as leveling agent, shelf life stabilizer, wetting agent, slip agent, flow agent, dispersant and degassing agent. In some embodiments, the additive includes fluorocarbon surfactant, silicone and organic polymer surfactant. Example includes Tegorad product line (Tegorad is a trademark, and is a commercially available product of Tego Chemie company in Essen, Germany) and Solsperse product line (Solsperse is a trademark, and is a commercially available product of Lubrizol company).

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

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

[0105] Unless otherwise indicated, "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 seeds or other parts of a fruit without having been functionalized (e.g., by chemical reaction) to include moieties that can participate in the polymerization process. Likewise, the term "mineral oil" refers to a petroleum-based hydrocarbon oil without having been functionalized (e.g., by chemical reaction) to include moieties that can participate in the polymerization process.

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

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

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

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

[0110] Typical values ​​for ink flow (tilted plate flow) are about 3-15 cm after 15 minutes, measured with a tilted aluminum plate holding 1 cc of ink.

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

[0112] The radiation curable ink of the present invention can be cured by LED light. The wavelength of the applied LED radiation 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 / cm 2 In the range of about 50 to 500 mJ / cm 2 The values ​​are measured by a calibrated radiometer with a good response in the relevant UVA region, such as the Powerpuck II of EIT. Furthermore, the LED source can be appropriately selected depending on the absorption spectrum of the radiation curable composition. Furthermore, the ink of the present invention can be cured under inert conditions or as an ink laminated by 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). Commercial EB-dryers can be obtained, for example, from Energy Science, Inc., Wilmington, Massachusetts, or Advanced Electron Beams Inc., Wilmington, Massachusetts. The absorbed energy, also known as dose, is measured in kilograys (kGy), with 1 kGy equal to 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 a dry, solvent-resistant ink at oxygen levels of <200 ppm.

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

[0115] Substrate

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

[0117] Test Method

[0118] Molecular weight

[0119] Typically, molecular weight can be measured by those techniques known in the art, such as gel permeation chromatography. For example, molecular weight determination can be performed on a Hewlett-Packard 1050 series HPLC system equipped with two GPC Ultrastyragel columns 103 and (5 μm mixed, 300 mm×19 mm, Waters Millipore Corporation, Milford, Massachusetts, USA) and THF as the mobile phase. Molecular weights can be calculated by comparison with polystyrene standards. Those skilled in the art will appreciate that this definition of molecular weight applies to polymeric materials that typically have a distribution of molecular weights. Typically, unless otherwise stated, the molecular weight (or average molecular weight) reported is the 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 conical flask. Dissolve the sample in acetone (10-20 ml). Double check that all sample material has dissolved. Add 3-5 drops of 1% ethanolic phenolphthalein solution. More indicator solution may be needed for colored solutions. Titrate with standardized 0.1 N ethanolic potassium hydroxide (KOH) to the first pink color, which lasts for 15 seconds. Record the ml of KOH solution used.

[0122] calculate:

[0123]

[0124]

[0125] Softening point of rosin resin

[0126] Mettler Dropping Softening Point (MDSP): The softening point can be measured with an automatic softening point detector DP70 from Mettler Toledo. Alternatively, the softening point is determined by 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 is 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 about 2° C. / min. The temperature (° C.) at which the resin first appears above the mercury surface is taken as the softening point.

[0127] Ethanol value

[0128] Unless otherwise stated, the ethanol value can be measured by weighing 10 g of the test resin in a conical flask. The resin is then dissolved in 50 g of toluene at an elevated temperature of ≤80°C. Once all the resin is dissolved, the solution is cooled to room temperature (23°C) and the conical flask is weighed to obtain "weight 1" (in grams). The conical flask is placed on a white paper with text on it. Ethanol is then added dropwise to the conical 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 conical flask is weighed again to obtain "weight 2" (in grams). The ethanol value is then calculated by subtracting "weight 1" from "weight 2" and quoted as g / 10g (i.e. grams of ethanol per 10 grams of resin).

[0129] Fineness of ink grinding

[0130] Make sure that the grinding gauge (25μm / 0-10NIPRI) is clean and dust-free, it must be wiped with a rag soaked in solvent before starting the test. Apply the paint at the 25μm mark in both channels. It must be ensured that the color sample does not contain any skin or larger particles. The grinding gauge block should be placed on a flat surface and cannot slide on the ground. Place the scraper vertically on the grinding gauge block with both hands at right angles to the grinding gauge block. Then slowly pull the paint down to the end of the grinding gauge. The blade should be pressed onto the grinding gauge so that the ink is almost completely removed on both sides. Record the μm reading on the grinding gauge where at least four scratches caused by larger ink particles appear.

[0131] Viscosity

[0132] Unless otherwise stated, the viscosity of the varnishes and inks was measured with a Physika 300 cone-plate rheometer from Anton Paar at a shear rate of D = 2-100 1 / s. The viscosity values ​​(Pa.s) were recorded at a shear rate of D = 2 1 / s (low shear) and D = 50 (high shear). Unless otherwise stated, the viscosity was measured at a shear rate of D = 50 1 / s at 23°C.

[0133] Adhesion

[0134] Tack was measured using a calibrated "Tack-o-scope" instrument (model 2001) from IGT Testing Systems, The 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 and then for 30 seconds at a roller speed of 300 rpm. Tack values ​​were then taken at a roller speed of 150 rpm.

[0135] Ink fluidity

[0136] The fluidity was measured using a vertically arranged aluminum plate, on which 1 ml of ink was placed. The distance (cm) that the ink flowed down the plate after 15 minutes was recorded.

[0137] Printing press performance and verification of the ink of the present invention

[0138] In order to further demonstrate the press performance and printing performance of the ink of the present invention and the comparative ink, the ink was printed on a "ManRoland 700" 4-color sheet-fed offset UV printer from AMS equipped with two LED dryers (power: 17 W / cm 2, at a wavelength of 385-395nm). The print test format (motive for the printing plate) was 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 for Graphic Arts in Munich, Germany. The target optical densities were: black = 1.75; cyan = 1.40; magenta = 1.40; yellow = 1.30). For the print test, a 130 g / m 2 Arto magic gloss, a graphic paper with a grammage of 1.

[0139] The press performance is evaluated by the press operator using a scoring system. 100 points means excellent performance. For every printing problem that occurs on the press, the operator deducts points. Finally, all remaining points are added together to give the final score. The tests include LED drying performance, print quality and press performance, which are described in detail below.

[0140] LED ink drying performance, solvent resistance, permanganate staining and ink set-off were tested and rated.

[0141] Solvent resistance

[0142] Solvent resistance is evaluated by rubbing the print cured on the ink with a damp cotton cloth soaked in isopropyl alcohol until the ink layer is rubbed through. The more rubs required to rub the ink through, the better the solvent resistance and cure, and the higher the score. The test is stopped at 100 rubs, as this indicates an almost perfect cure result, and 100 points are given. The worst score is 0-5 rubs of solvent resistance and results in 20 points being deducted from 100 for each color.

[0143] Potassium permanganate staining

[0144] A drop of aqueous potassium permanganate solution (5%) is placed on the selected color area on the printed and LED dried substrate for 5 seconds. The drop is then wiped off and the optical density of the remaining stain is measured. The darker the color (density) of the stain, the more uncured residual double bonds there are in the dried color. No staining means no penalty, and for spots with an optical density > 0.25 formed, 25 score points are deducted from 100.

[0145] Anti-sticking

[0146] After the LED is dried, a counter paper is placed on the printed surface at 10 t / cm 2The pressure of 100% was pressed onto the print. Then, the counting paper was removed and the ink set on the counting paper was checked. No ink set was considered excellent and ink set of >0.2 optical density was considered a poor result. No ink set was deducted; the worst score was a set density >0.2 and 20 points were deducted from 100. More detailed set-off scores are shown in Table 1.

[0147] Table 1: Score of stickiness

[0148]

[0149] Regarding the quality of the print, its rub resistance and glossiness were evaluated.

[0150] Friction resistance

[0151] The ink print is placed on a "Sutherland" rub tester and a counting paper is rubbed on the surface for a defined period of time. The amount of ink rubbed off is visually inspected and a score is given by comparison means from excellent to worst. The lower the ink damage and the smaller the amount of ink rubbed off, the higher the score. The results are rated from 0 (best) to 10 (worst). 0 or 1 means no score points are deducted, 10 means 20 score points are deducted from 100 for each ink. More detailed rub resistance scores are shown in Table 2.

[0152] Table 2: Abrasion resistance rating

[0153]

[0154]

[0155] Glossiness

[0156] Gloss is measured by a BYK Micro Glossmeter at 60°. The higher the gloss, the higher the score. One gloss unit on the glossmeter is equal to one score point. The average value of all four process colors is recorded.

[0157] The ink performance on the press is evaluated by ink channel flow, ink flying and overall lithographic performance.

[0158] Pipeline Liquidity

[0159] The pipeline fluidity is evaluated based on the degree to which the ink leaves the ink pipeline without additional forced stirring. If the ink does not leave the ink pipeline correctly, the transmission through the ink roller system may be slowed or interrupted. By comparison, the ink pipeline fluidity is rated from 0 (best) to 5 (worst) by the printing press operators in the field. The better the ink pipeline fluidity, the higher the score. For excellent fluidity coming out of the ink pipeline, no score points are deducted from 100, and for poor fluidity, 22 points are deducted from 100 for each ink. More detailed pipeline fluidity scores are shown in Table 3.

[0160] Table 3: Pipeline Liquidity Scores

[0161]

[0162] Flying Ink

[0163] During a printing operation, ink flying can be a serious problem because it can contaminate the printing press, resulting in frequent production stops to clean the printing press. In addition, when tiny droplets of acrylate mist enter the air, this can also pose a health hazard. Although the printing press settings and roller diameter can play a role, the chemical properties of the ink are considered to be an important factor. Ink flying is determined by placing a blank paper substrate at a close distance to the selected roller and allowing the ink mist generated from the roller to deposit on the blank paper for a defined time. Then, the paper with ink mist on it is compared by eye or measured with a densitometer to determine the amount of ink on the paper. The less ink mist is deposited on the paper, the better the "ink flying" performance and the higher the score. Ink flying is rated from 0 (best) (meaning no score points are deducted) to 5 (worst) (where -20 score points are deducted from 100 for each color). More detailed ink flying scores are shown in Table 4.

[0164] Table 4: Feimo score

[0165]

[0166] Lithographic printing performance

[0167] The overall lithographic performance is evaluated by the main requirements and printing problems that may occur on a sheet-fed offset printing press, such as ink / water balance, scumming, picking, smudging by another color, overemulsification, ink in the dampening train, framing, ink accumulation, as described below. These problems are known to those skilled in the art and are ranked by comparison and scored based on the procedure mentioned below. Finally, the scores of the individual scoring results related to lithography are added to obtain an overall lithographic performance score. In the following, the individual requirements for lithographic performance are described.

[0168] Ink / water balance

[0169] The goal is to print the offset ink with the lowest amount of fountain solution while the printing plate still runs freely. The ink / water balance can also be described by the expression "water window". It is identified by the maximum possible range of ink and water settings on the printing press within which the ink still runs stably. The ink / water balance is rated by the press operator on a scale of 0-5, where zero (best) means no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0170] Blurred version

[0171] Smudging is the inability of the fountain solution to keep the non-image areas of the plate clean. Smudging is rated by the press operator on a scale of 0-5, with zero (best) meaning no smudging and no deduction of points; and 5 (worst) meaning 20 points are deducted from 100 for each color.

[0172] Rag

[0173] Picking is when the ink tears fibers from the paper substrate or pulls off the paper coating. Picking is rated by the press operator on a scale of 0-5, with zero (best) meaning no picking and no deduction of points; and 5 (worst) meaning 20 points are deducted from 100 for each color.

[0174] Stained by another color

[0175] During a print test, one ink may be smeared by another ink, which may cause a hue shift on the print that can be detected by a shift in the colorimetric data. Smudging is rated by the press operator on a scale of 0-5, where zero (best) means no smudging, resulting in no deduction of points; 5 (worst) means 20 points are deducted from 100 for each color.

[0176] Over-emulsification

[0177] If the ink absorbs too much water, it can produce a fur-like coating of ink on the inking train rollers. Overemulsification is rated by the press operator on a scale of 0-5, where zero (best) means no overemulsification and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0178] Ink in the dampening wheel train

[0179] The ink in the dampening train is visually detected and rated by the press operator on a scale of 0-5, where zero (best) means no ink in the dampening train and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0180] Frame

[0181] Framing refers to visible ink outside and around the area to be printed. Framing is rated by the press operator on a scale of 0-5, where zero (best) means no framing and no points are deducted; 5 (worst) means 20 points are deducted from 100 for each color.

[0182] Ink accumulation

[0183] Ink may accumulate on rollers, blankets and plates, resulting in dry accumulation of ink. Accumulation is rated by the press operator on a scale of 0-5, where zero (best) means no accumulation, resulting in no deduction of points, and 5 (worst) means 20 points are deducted from 100 for each color.

[0184] As mentioned before, the scoring points for each test result are added together to give an overall final score. For a better visual understanding, the individual results can be depicted in a spider web graph.

[0185] like Figure 1 As shown, the spider web graph depicts the ink performance scores of Examples 2A-5A of the present invention and the comparative examples. The actual scores are also given in the examples.

[0186] The present invention is further described by the following numbered paragraphs:

[0187] 1. A printing ink or varnish composition comprising:

[0188] 25-85% of one or more acrylates;

[0189] 0-20% of one or more photoinitiators;

[0190] 5-60% of one or more rosin-modified polyester resins;

[0191] 0.2-5% of one or more aluminum additives;

[0192] 0.1-5% of one or more polymeric stabilizers; and

[0193] 0-50% colorant.

[0194] 2. The composition according to paragraph 1, wherein the composition is curable by UV-LED radiation.

[0195] 3. The composition of paragraph 1 or 2, wherein the composition comprises 0.5-20% of one or more photoinitiators.

[0196] 4. The composition of paragraph 1, wherein the photoinitiator is removed and the composition is curable by electron beam radiation.

[0197] 5. The composition according to the preceding paragraph, wherein the composition is an offset ink or a varnish.

[0198] 6. The composition according to any of the preceding paragraphs, wherein at least one of the photoinitiators is selected from the group consisting of thioxanthones, acylphosphine oxides, aminobenzophenones, aminoalkylphenyl ketones, ketocoumarins, or mixtures thereof.

[0199] 7. The composition according to any of the preceding paragraphs, wherein the aluminum additive is selected from the group consisting of aluminum alkoxides, aluminum chelates, aluminum carboxylates, or blends thereof.

[0200] 8. The composition of paragraph 7, wherein the aluminum additive is an aluminum alkoxide selected from the group consisting of mono-, di-, or tripropoxy aluminum; mono-, di-, or tripropoxy aluminum; mono-, di-, or tripropoxy aluminum; mono-, di-, or tripropoxy aluminum; mono-, di-, or tripropoxy aluminum; mono-, di-, or tripropoxy aluminum; and blends thereof.

[0201] 9. The composition of paragraph 7, wherein the aluminum additive is an aluminum chelate selected from the group consisting of chelates of ethylaluminum monoacetoacetate with diisopropoxide; di- and tri-chelates of aluminum with alkyl acetoacetates or alkyl diketones, and blends thereof; or

[0202] 10. The composition of paragraph 7, wherein the aluminum additive is an aluminum carboxylate selected from the group consisting of aluminum triacetate or aluminum tripropionate and blends thereof.

[0203] 11. The composition of paragraphs 1-7 or 9, wherein the aluminum additive is diisopropoxyaluminum ethyl acetoacetate.

[0204] 12. The composition of any of the preceding paragraphs, wherein the rosin-modified polyester resin is derived from a source selected from the group consisting of gum rosin, tall oil rosin, mono-, di-, tri- or tetra-functional polyols, mono-, di-, tri- or tetra-functional acids or anhydrides, and blends thereof.

[0205] 13. The composition of any of paragraphs 1-11, wherein the rosin-modified polyester resin is derived from a source selected from the group consisting of gum rosin, maleic anhydride, fumaric acid, glycerol, pentaerythritol, and blends thereof.

[0206] 14. The composition of any 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.

[0207] 15. The composition of any of the preceding paragraphs, wherein the rosin-modified polyester resin has a molecular weight of 2,000 to 100,000 Daltons.

[0208] 16. The composition of any of the preceding paragraphs, wherein the rosin-modified polyester resin has an acid value of 5-50 mg KOH / g.

[0209] 17. The composition of any of the preceding paragraphs, wherein the rosin has a softening point in the range of 70-135°C or 85-110°C.

[0210] 18. An LED-curable offset ink or coating composition which is or comprises a composition according to any one or more of paragraphs 1-17.

[0211] 19. The composition of paragraph 18 comprising one or more colorants.

[0212] 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.

[0213] 21. The composition of any of the preceding paragraphs, having ≥ 5% improvement in ink and press performance scores compared to a comparative example without the aluminum additive.

[0214] 22. The composition of any of the preceding paragraphs, having ≥ 10% improvement in ink and press performance scores compared to a comparative example without the aluminum additive.

[0215] 23. The composition of any of the preceding paragraphs, having ≥ 15% improvement in ink and press performance scores compared to a comparative example without the aluminum additive.

[0216] 24. A printed article comprising a composition according to any one or more of paragraphs 1-23.

[0217] 25. A method for preparing a printed matter, comprising:

[0218] applying the composition according to any one or more of paragraphs 1 to 23 to a substrate by offset printing; and

[0219] The composition is cured by UV-LED or electron beam.

[0220] The present invention has been described in detail, including various embodiments thereof. However, it should be appreciated that those skilled in the art, after considering this disclosure, may modify and / or improve the present invention within the scope and spirit of the present invention.

[0221] Example

[0222] The present invention is further described by the following non-limiting examples, which further illustrate the invention and are not intended, nor should they be construed, to limit the scope of the invention.

[0223] Rosin Solubility

[0224] 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 having molecular weights of 50,000 and 40,000 Daltons are soluble in ditrimethylolpropane tetraacrylate (DiTMTPA), they are insoluble in dipentaerythritol hexaacrylate (DPHA). Only when the molecular weight is reduced does the rosin dissolve in the hexafunctional acrylate, dipentaerythritol hexaacrylate.

[0225] Table 5: Rosin Solubility

[0226]

[0227]

[0228] 1 The rosin resin is described as soluble, wherein a 50 wt % solution of the rosin resin in the functional acrylate at room temperature (ie, 20° C.) shows no visible precipitation after 24 hours.

[0229] The inventive inks and comparative inks of this application were made in a two-step process by preparing a premix at 40-60°C as described, followed by grinding on a 3-roll mill until the appropriate pigment particle size was achieved (bulk particles <10 μm). After grinding was complete, the inks were ready for printing. The inventive inks and comparative inks had a viscosity of 40-60 Pa·s, a tilted plate flowability of 3-15 cm, and a tack of 230-330 units.

[0230] Table 6: Varnish according to the invention of Example 1A and comparative varnish of Example 1B (materials expressed in % by weight)

[0231]

[0232] The varnish of Comparative Example 1B has a viscosity of about 65 Pa·s and exhibits an almost Newtonian behavior, whereas the varnish of Inventive Example 1A has a slightly higher viscosity of about 75 Pa·s and has a higher viscosity at low shear rates ("more structure").

[0233] Table 7: Inventive Yellow Ink Example 2A and Comparative Yellow Ink Example 2B

[0234]

[0235]

[0236] Table 8: Inventive Magenta Ink Example 3A and Comparative Magenta Ink Example 3B

[0237]

[0238] Table 9: Inventive Cyan Ink Example 4A and Comparative Cyan Ink Example 4B

[0239]

[0240]

[0241] Table 10: Inventive Black Ink Example 5A and Comparative Black Ink Example 5B

[0242]

[0243]

[0244] Table 11 gives a summary of the performance scores of Inventive Examples 2A-5A and Comparative Examples 2B-5B.

[0245] Table 11: Printing press performance and printing performance (scores) of ink examples of the present invention (containing aluminum additives) and comparative ink examples (without aluminum additives)

[0246]

[0247] Table 11 clearly shows that the aluminum additive improves the overall performance (especially lithographic performance) and reduces ink flying (higher score) of the inks of the present invention relative to the comparative inks. Although the aluminum additive is incorporated into the varnish in the examples, it should be understood that the aluminum can be easily added directly to the ink itself.

[0248] For better intuitive understanding, each result can be depicted in a spider web graph. The spider web graph shows the ink performance scores of Examples 2A-5A of the present invention and Comparative Examples 2B-5B.

[0249] exist Figure 1 In the spider web plot, it can be clearly observed that the four-color ink set of the present invention containing aluminum additive (outer curve shape) covers more chart space than the comparative ink set (inner curve shape), which means it is a better performing ink, especially in terms of ink flight, lithographic printing performance and ink drying, as evaluated by solvent resistance and set-off tests.

[0250] The present invention has been described in detail, including various embodiments thereof. However, it should be appreciated that those skilled in the art, after considering this disclosure, may modify and / or improve the present invention within the scope and spirit of the present invention.

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 polymeric stabilizers; and 0-50% colorant.

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 any one of the preceding claims, wherein the rosin-modified polyester resin has a softening point of 85-110°C.

4. The composition of any one of the preceding claims, 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. A composition according to any one of the preceding claims, wherein the composition comprises no more than 5% vegetable oil and / or mineral oil.

6. The composition according to any one of the preceding claims, wherein the at least one acrylate is a pentaacrylate.

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

8. The composition according to any one of claims 1 to 5, 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 any one of the preceding claims, wherein the composition is curable by UV-LED radiation.

11. The composition according to any one of the preceding claims, wherein the composition comprises 0.5-20% of one or more photoinitiators.

12. The composition of any one of claims 1 to 10, wherein the composition comprises 0% photoinitiator (ie, the composition is free of photoinitiator) and the composition is curable by electron beam radiation.

13. The composition according to the preceding claim, wherein the composition is an offset ink or a varnish.

14. The composition according to any one of claims 1-11 or 13, wherein at least one of the photoinitiators is selected from the group consisting of thioxanthones, acylphosphine oxides, aminobenzophenones, aminoalkylphenyl ketones, ketocoumarins or mixtures thereof.

15. The composition according to any one of the preceding claims, wherein the aluminum additive is selected from the group consisting of aluminum alkoxides, aluminum chelates, aluminum carboxylates, or blends thereof.

16. The composition of claim 15, wherein the aluminum additive is: (a) an aluminum alkoxide selected from the group consisting of mono-propoxy-aluminum, di-propoxy-aluminum, or trip-propoxy-aluminum; mono-iso-propoxy-aluminum, di-iso-propoxy-aluminum, or tri-iso-propoxy-aluminum; mono-butyrate-aluminum, di-butyrate-aluminum, or tri-butyrate-aluminum; mono-iso-butyrate-aluminum, di-iso-butyrate-aluminum, or tri-iso-butyrate-aluminum, and blends thereof; (b) an aluminum chelate selected from the group consisting of chelates of ethylaluminum monoacetoacetate with diisopropoxide; di- and tri-chelates of aluminum with alkyl acetoacetates or alkyl diones, and blends thereof; or (c) Aluminum carboxylates selected from the group consisting of aluminum triacetate or aluminum tripropionate and blends thereof.

17. The composition of any one of claims 1-16, wherein the aluminum additive is diisopropoxyaluminum ethyl acetoacetate.

18. The composition according to any one of the preceding claims, wherein the aluminum additive is in an inert solvent, wherein the inert solvent is selected from mineral oil or vegetable oil.

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

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

21. The composition of any one of the preceding claims, wherein the rosin-modified polyester resin is derived from: (a) a source selected from the group consisting of gum rosin, tall oil rosin, a mono-, di-, tri- or tetra-functional polyol, a mono-, di-, tri- or tetra-functional acid or anhydride, and blends thereof; (b) a source selected from the group consisting of gum rosin, maleic anhydride, fumaric acid, glycerol, pentaerythritol, and blends thereof; or (c) a source selected from the group consisting of tetrahydrophthalic anhydride, glycerol, aromatic monofunctional acids, monofunctional alcohols, and blends thereof.

22. A composition according to any one of the preceding claims, wherein the rosin-modified polyester resin is derived from: i) gum rosin, wood rosin or tall oil rosin, ii) one or more difunctional acids or anhydrides selected from maleic acid, maleic anhydride, cyclohexene dicarboxylic dianhydride or methylcyclohexene dicarboxylic 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, methyl benzoic acid, tert-butyl benzoic acid, naphthoic acid and linoleic acid.

23. The composition of claim 22, wherein the rosin-modified polyester resin is derived from: i) gum 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, methyl benzoic acid, tert-butyl benzoic acid, naphthoic acid and linoleic acid.

24. The composition of claim 22 or 23, wherein the rosin-modified polyester resin is derived from: i) gum 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, difunctional, trifunctional or tetrafunctional polyols selected from glycerol or trimethylolpropane; and iv) benzoic acid.

25. A composition according to any one of the preceding claims, 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.

26. The composition according to any one of the preceding claims, wherein the rosin-modified polyester has an ethanol value of >4 g / 10 g, preferably 4-10 g / 10 g.

27. An LED-curable offset ink or coating composition which is or comprises the varnish composition according to any one or more of claims 1 to 26.

28. The ink or coating composition of claim 27 comprising 5-40% of one or more colorants.

29. An ink or coating composition according to claim 27 or 28, comprising 25-85% of a composition according to any one or more of claims 1-26.

30. A composition according to any one of the preceding claims, which has ≥5% improvement in ink and press performance scores compared to a comparative example without an aluminum additive, preferably, the composition has ≥10% improvement in ink and press performance scores compared to a comparative example without an aluminum additive, more preferably, the composition has ≥15% improvement in ink and press performance scores compared to a comparative example without an aluminum additive.

31. A printed article comprising a composition according to any one or more of claims 1 to 30.

32. A method for preparing a printed matter, comprising: Applying the composition according to any one or more of claims 1 to 30 to a substrate by offset printing; and The composition is cured by UV-LED or electron beam.

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