WO2023218168A1 - Encres pour jet d'encre à faible brillant - Google Patents

Encres pour jet d'encre à faible brillant Download PDF

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Publication number
WO2023218168A1
WO2023218168A1 PCT/GB2023/051193 GB2023051193W WO2023218168A1 WO 2023218168 A1 WO2023218168 A1 WO 2023218168A1 GB 2023051193 W GB2023051193 W GB 2023051193W WO 2023218168 A1 WO2023218168 A1 WO 2023218168A1
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WO
WIPO (PCT)
Prior art keywords
ink
light source
led
range
acrylate
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PCT/GB2023/051193
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English (en)
Inventor
Shaun Herlihy
Thomas BUDDEN
Steve Hall
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Sun Chemical Corporation
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Publication of WO2023218168A1 publication Critical patent/WO2023218168A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M7/00—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock
    • B41M7/0081—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock using electromagnetic radiation or waves, e.g. ultraviolet radiation, electron beams

Definitions

  • the present invention relates to low gloss inkjet inks and a method of reducing gloss of a printed surface.
  • WO 2010/150023 mentions that exposure to high power mercury lamps will cause cure before spreading, leading to a highly roughened surface with diffuse reflectance that gives a matte image affect.
  • the solution to this problem in WO 2010/150023 is to use an LED pinning lamp followed by a final xenon or krypton flash lamp to achieve full cure.
  • WO 2010/150023 is therefore based around the need to control image quality through the use of an LED pinning lamp.
  • US 9,260,616 defines gloss controllable UV-curable inkjet inks through the use of increasing pinning LED dose. It mentions how higher energy results in lower gloss due to low drop spread. However, it is not noted that the lower gloss values come at the expense of print quality because the driving force for lowering the gloss is to minimize the drop spread and create an uneven surface layer of cured drops.
  • the reference describes how gloss variation in an image is a problem that is solved through the selection of photoinitiators used relative to the pigment chromophore in the particular ink, caused by the differing drop spread characteristics of different inks containing different pigments.
  • EP 3,822,085 mentions the need for UV inkjet inks with adjustable gloss levels to suit particular markets; high gloss levels for outdoor applications, and low gloss levels for indoor applications. This is achieved by the use of an ink set together with the nonpigmented ink that are applied in multiple layers with ink dispersed with nonpigmented ink such that the effect is to produce low gloss levels.
  • the drop spread of the ink is controlled through the use of a gel and material which increases rapidly in viscosity when cooled, similar to a hotmelt ink.
  • waxes, hydrocarbons and ketones As would be appreciated by those skilled in the art, the inclusion of wax or hydrocarbon type compounds would be detrimental to the physical properties of the cured ink. No such measurements of the cure properties were however made in this reference.
  • the present invention differs from EP 3,822,085 in that no additional additive chemistries are required to control the gloss levels and no additional nonpigmented inks are introduced in order to achieve the effect.
  • the reference also fails to achieve a low level of gloss ( ⁇ 20-30 gloss units) until a relatively large proportion of the nonpigmented ink is used; roughly the same as each of the individual CMYK and RGB colors.
  • GB 2,520,595 refers to how the level of LED pinning is critical to the achievement of good print quality.
  • Low print quality is produced by too low a level of pinning that allows drop spread to cause inter-color bleed.
  • Levels of pinning that are too high result in a poor image quality due to reduced color density and exposed substrate. Where the ink is printed at higher density low gloss results through the generation of a roughened surface.
  • the reference aims to resolve these problems through the use of tailored photoinitiator packages, where black and yellow have lower reactivity and require a higher LED sensitivity photoinitiator package than cyan and magenta.
  • GB 2,520,595 mentions low gloss as a problem to be solved and relates this to the need for a low level of LED pinning, balanced against excessive drop spread.
  • the present invention differs significantly in that selection of the suitable LED pinning lamp and the use of high-power can be used to create low gloss ink surfaces without any loss in print resolution because the drop spread aspect is largely independent of it. https://futureprint.tech/the-futureprint-blog/êtwerk-and-uv-inkjet-mat-varnish mentions a product offering from Siegwerk which uses very fine particles in an inkjet varnish to create a matte coating effect.
  • Excimer lamps have been used for a large number of years to create matte effect coatings, their use is well accepted for use in coatings only and relies on the provision of an inert nitrogen blanket to allow the cure to take place. It differs from the present invention in that the excimer lamp excites the acrylate groups directly and there is no involvement by photoinitiator in this process.
  • the surprising aspect of the present invention is that matting of an ink by a UVB or UVC UV-LED lamp (preferably a 280 nm LED lamp) is achieved while still retaining some level of overall cure, compared to 172 nm excimer lamp where the accepted penetration distance is extremely low, leading to a surface cured skin that swims on a layer of uncured liquid coating.
  • the level of matting obtained with 280 nm LED is also particularly surprising because of the amount of 280 nm wavelength and below light that is contained within the emissions of a normal medium pressure mercury arc lamp.
  • Figure 1 is a graphic illustrating set off migration. DETAILED DESCRIPTION
  • the present invention provides a method of reducing the gloss of a printed UV-curable ink or coating comprising; a. printing one or more ink layers or coatings onto a substrate; b. curing the one or more ink layers or coatings using a UVB or UVC UV- LED light source; and c. curing the one or more ink layers or coatings using a UV-LED light source in the 365-405 nm range or a doped or undoped medium pressure mercury lamp.
  • the present invention also provides a method of preparing a printed substrate, said method comprising: a. printing one or more UV-curable inks or coatings onto the substrate; b. curing the one or more UV-curable inks or coatings using a UVB or UVC UV-LED light source; and c. curing the one or more UV-curable inks or coatings using a UV-LED light source in the 365-405 nm range or a doped or undoped medium pressure mercury lamp.
  • step b. is performed before step c in the method of the invention.
  • the advantage of the method of the present invention is that it simultaneously pins the ink and provides the low gloss surface.
  • the time interval between printing and pinning can be optimized for the image quality whereas with existing technologies the accepted problem is that in order to achieve low gloss this would be through the use of a short time interval between jetting and pinning, with a consequential loss in image quality due to insufficient drop spread.
  • the present invention provides an inkjet ink and lamp package which is able to deliver the highest levels of print quality, but also with varying levels of gloss, which can be obtained partially through control of the UVC/UVB LED lamp and partially through the ability to control the level of gloss reduction with the photoinitiator and monomer package for each color.
  • UVB LED lamps are typically in 280-320 nm range; UVC LED lamps are typically in the 250-280 range.
  • the UV LED light source used in step b. of the method of the invention is a UV LED lamp in the range of 250-320 nm, preferably a UV LED lamp in the range of greater than 250-320 nm. More preferably, the UV LED light source used in step b. of the method of the invention is a UV LED lamp in the range of 270-320nm, preferably a UV LED lamp in the range of 270-290 nm. Most preferably, the UV LED light source used in step b. of the method of the invention is a 280 nm LED lamp.
  • UV-light sources include: low pressure mercury bulbs (i.e., lamps), medium pressure mercury bulbs (i.e., lamps), xenon bulb (i.e., lamps), excimer lamps, carbon arc lamp, metal halide bulb (i.e., lamps), UV-LED lamp or sunlight.
  • any UV light source may be used to cure compositions prepared according to the present invention; however, in order to achieve low gloss, curing is performed using a UVB or UVC UV-LED light source followed by a UV-LED light source in the 365-405 nm range or a doped or undoped medium pressure mercury lamp as claimed.
  • mercury pressure lamps are polychromatic.
  • the mercury spectrum has strong emission lines (peaks) at 184, 254, 365 (I-line), 405 (H-line), 436 (G-line), 564 and 578 nm.
  • the lines between 200 and 600 nm are present, i.e. medium pressure mercury lamps emit light in the range of 200-600nm.
  • the emission of the mercury lamp can be influenced by doping. Typical dopants include iron, gallium, lead, tin, bismuth and indium.
  • medium pressure mercury lamps operate at 80 to 240 W/cm, more typically 80 to 200 W/cm.
  • Medium pressure lamps operating at 80 W/cm, 160 W/cm or 200 W/cm are suitable for use in the present invention (with lamps operating at 200 w/cm being particularly suitable); although the invention is not limited to the use of lamps operating at this power.
  • the method of the present invention comprises curing with a medium pressure mercury lamp operating at 80-100% power level.
  • UV pinning refers to partially or completely immobilizing a newly jetted ink in place usually by the action of a relatively low power LED lamp (e.g. a 4W/cm LED lamp), typically 395 nm, prior to being fully cured with a more powerful lamp.
  • the full cure can be provided by a range of medium pressure, doped medium pressure, LED or electronbeam radiation sources.
  • the time between pinning and full cure generally being a factor of both time elapsed and the drop spread characteristics of the inks being jetted.
  • UV-LED lamps operating at 4W/cm are suitable for use in the present invention; although the invention is not limited to the use of lamps operating at this power.
  • the method of the present invention comprising curing with a UVB or UVC UV-LED lamp operating at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% 90% or 100% power.
  • the present invention involves the use of a UVB/UVC wavelength LED pinning lamp, typically around 280 nm emission wavelength.
  • This wavelength suitably provides cure throughout the bulk of the ink layer, but at the same time is differentially much more active at the surface of the ink due to the strong UV absorbing characteristics of many of the components used in the inks, particularly the photoinitiators and pigments.
  • the differential cure at the surface is sufficient to cause micro-wrinkling of the uppermost layer and a loss of gloss as a result.
  • More typical longer wavelength LED light sources (typically 365 nm-405 nm as known by those skilled in the art) have little effect on the overall gloss level because of the more even cure through the profile of the ink. This is also independent of the dose and intensity of the typical LED lamps used, from low-power pinning lamps up to 395 nm LED lamps with power ratings of 12-16 W/cm 2 running at full power.
  • the present invention also involves the use of a 2 nd more powerful lamp to effect full cure of the ink.
  • This can either be a doped or undoped medium pressure mercury arc lamp or an additional longer wavelength (typically 365-405 nm) LED lamp operating at a power level suitable for the achievement of full ink cure.
  • the method according to the present invention does not use a flash lamp.
  • flash lamps are not continuous. Consequently, there will typically be dose variations along a web path depending on the flash frequency. More preferably, the method of the invention does not use a xenon or krypton flash lamp.
  • the 280 nm wavelength LED can provide significant curing, the overall ink properties are still insufficient for commercial use and would typically require more cure nearer the bottom of the film to generate sufficient resistance and adhesion properties.
  • the highly cured surface of the ink film resulting from the 280 nm wavelength LED also then provides a significant oxygen barrier such that the UV output dose from the 2 nd lamp need not be as significant as that which would be normally required when using a more conventional longer wavelength LED pinning lamp.
  • the invention extends to a disclosure of particular preferred photoinitiator compounds which have strong UV chromophores in the 280 nm wavelength region and as such are capable of fine tuning the level of gloss such that the resultant combination of inks do not have significant gloss level variations across a printed image.
  • the UV curing inks have been demonstrated to have controlled gloss through the application of 280 nm LED at different power levels.
  • beneficial effect of the invention is not specifically tied to this wavelength.
  • the beneficial effect of the invention may be achieved with wavelengths down to 250nm and as high as 320 nm.
  • the competing effect with alternate wavelengths is one of ozone generation at shorter wavelengths and a greater level of UV light penetration at longer wavelengths.
  • 280 nm is particularly preferred, but wavelength range of 250-320 nm may also be used, preferably 270-320nm.
  • the methods of the present invention comprise printing one or more UV-ink curable inks or coatings to a substrate wherein the thickness of the printed ink or coating is 4-40 microns.
  • compositions prepared according to the current invention are particularly suited to curing under the action of UV light. Although an enhanced effect may be achieved through specific selection of photoinitiators, there is no particular restriction on the type, blend or concentration of photoinitiator used. Those used would be well known to those skilled in the art and can include any of, but not limited to the following (and combinations thereof):
  • a-hydroxyketones such as; 1-hydroxy-cyclohexyl-phenyl-ketone; 2-hydroxy-2- methyl- 1 -phenyl- 1 -propanone; 2-hydroxy-2-methyl-4’ -tert-butyl-propiophenone; 2-hydroxy-4’-(2-hydroxyethoxy)-2-methyl-propiophenone; 2-hydroxy-4’-(2- hydroxypropoxy)-2-methyl-propiophenone; 1 -Propanone, 1 , 1 '-(oxydi-4, 1 - phenylene)bis[2-hydroxy-2-methyl-; l-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2- methylpropanone); oligo 2-hydroxy-2-methyl-l-[4-(l-methyl- vinyl)phenyl]propanone; bis[4-(2-hydroxy-2-methylpropionyl)phenyl]methane; 2- Hydroxy-l-[l-[4-(2-hydroxy-2-methylpropano
  • acylphosphine oxides such as; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; ethyl (2,4,6-trimethylbenzoyl)phenyl phosphinate; and bis-(2,4,6- trimethylbenzoyl)-phenylphosphine oxide; a-aminoketones such as; 2-methyl-l- [4-methy lthio)phenyl] -2-morpholinopropan- 1 -one; 2-benzyl-2-dimethylamino- 1 - (4-morpholinophenyl)-butan -1-one; and 2-dimethylamino-2-(4-methyl-benzyl)- 1 -(4-morpholin-4-yl-phenyl)-butan- 1 -one;
  • thioxanthones such as; N,N-diisobutyl-7-methyl-9-oxo-9H-thioxanthene-3- carboxamide; 2-4-diethylthioxanthone, isopropylthioxanthone, 2- chlorothioxanthone, and 1 -chloro-4-propoxythioxanthone;
  • benzophenones such as; such as benzophenone, 4-phenylbenzophenone, and 4- methylbenzophenone; methyl-2-benzoylbenzoate; 4-benzoyl-4-methyldiphenyl sulphide; 4-hydroxybenzophenone; 2,4,6-trimethyl benzophenone, 4,4- bis(diethylamino)benzophenone; benzophenone-2-carboxy(tetraethoxy)acrylate; 4-hydroxybenzophenone laurate and l-[-4-[benzoylphenylsulpho]phenyl]-2- methyl-2-(4-methylphenylsulphonyl)propan- 1 -one;
  • phenylglyoxylates such as; phenyl glyoxylic acid methyl ester; oxy-phenyl-acetic acid 2- [hydroxyl-ethoxy] -ethyl ester, or oxy-phenyl-acetic acid 2-[2-oxo-2- phenyl-acetoxy-ethoxy] -ethyl ester; and
  • oxime esters such as; 1 -phenyl- l,2-propanedione-2-(O-ethoxycarbonyl)oxime; [1- (4-phenylsulfanylbenzoyl)heptylideneamino]benzoate, or [l-[9-ethyl-6-(2- methylbenzoyl)carbazol-3-yl]-ethylideneamino]acetate.
  • the UV-curable ink or coating of the present invention comprises one or more photo initiator(s) having a UV chromophore in the 270 - 290 nm wavelength region.
  • a blend of photoinitiators refers to one or more photoinitiators.
  • the UV-curable ink or coating of the present invention comprises two or more photoinitiators.
  • At least a portion of the photoinitiators in the ink or coating are selected from the group consisting of 1 -Propanone, 1, 1 '-oxydi-4, 1 -phenylene)bis[2-hydroxy-2-methyl-), 1 -[4-(2-hydroxyethyl)-phenyl]-2- hydroxy-2-methylpropanone), and N,N-diisobutyl-7-methyl-9-oxo-9H-thioxanthene-3- carboxamide.
  • photoinitiators examples include diethoxy acetophenone; benzil; benzil dimethyl ketal; titanocen radical initiators such as titanium-bis(p 5-2,4-cyclopentadien-l- yl)-bis- [2, 6-difluoro-3-(lH- pyrrol- l-yl)phenyl]; 9-fluorenone; camphorquinone; 2-ethyl anthraquinone; and the like.
  • amine synergist e.g. a polymeric aminoacrylate
  • Suitable examples of amine synergists include, but are not limited to, the following:
  • Aromatic amines such as; 2-(dimethylamino)ethylbenzoate; N-phenyl glycine; benzoic acid, 4-(dimethylamino)-, l,r-[(methylimino)di-2,l -ethanediyl] ester; and simple alkyl esters of 4-(N,N-dimethylamino)benzoic acid, with ethyl, amyl, 2-butoxy ethyl and 2- ethylhexyl esters being particularly preferred; other positional isomers of N,N-dimethylamino)benzoic acid esters are also suitable;
  • Aliphatic amines such as N-methyldiethanolamine, triethanolamine and triisopropanolamine
  • Polymeric photoinitiators and sensitizers are also suitable, including, for example, polymeric aminobenzoates (GENOPOL AB-1 or AB-2 from RAHN, Omnipol ASA from IGM or Speedcure 7040 from Lambson), polymeric benzophenone derivatives (GENOPOL BP-1 or BP-2 from RAHN, Omnipol BP, Omnipol BP2702 or Omnipol 682 from IGM or Speedcure 7005 from Lambson), polymeric thioxanthone derivatives (GENOPOL TX-1 or TX-2 from RAHN, Omnipol TX from IGM or Speedcure 7010 from Lambson), polymeric aminoalkylphenones such as Omnipol 910 from IGM; polymeric benzoyl formate esters such as Omnipol 2712 from IGM; and the polymeric sensitizer Omnipol SZ from IGM.
  • polymeric aminobenzoates GOPOL AB-1 or AB-2 from RAHN, Omnipol ASA from IGM or Speedcure 7040 from Lambson
  • compositions of the current invention are used in low migration applications it is preferred that photoinitiators having low migration potential are used. Therefore, polymeric, polymerizable and multifunctional types are preferred.
  • the UV-curable ink or coating used in the present invention comprises from about 0.5% to about 30% by weight of photoinitiator blend, more preferably from about 3% to about 25% by weight of photoinitiator blend, even more preferably from about 7% to about 20% by weight of photoinitiator blend.
  • compositions according to the invention may comprise any amount of any blend (i.e., one or more) of free radically polymerizable monomers and/or oligomers, preferably any blend (i.e. one or more) of monomers optionally with one or more oligomers, though preferably the amount of those monomers having an average molecular weight less than 1000 Daltons is greater than 10% (w/w) of the total composition.
  • the free radically polymerizable monomers and oligomers suitable for use in the present invention are ethylenically unsaturated monomers.
  • ethylenically unsaturated monomers can be monofunctional or multifunctional.
  • Suitable monofunctional ethylenically unsaturated monomers include but are not limited to the following (and combinations thereof), where the terms ethoxylated refers to chain extended compounds through the use of ethyleneoxide, propoxylated refers to chain extended compounds through the use of propylene oxide, and alkoxylated refers to chain extended compounds using either or both ethyleneoxide and propylene oxide.
  • Equivalent methacrylate compounds are also capable of being used, although those skilled in the art will appreciate that methacrylate compounds have lower reactivity than their equivalent acrylate counterparts: isobutyl acrylate; cyclohexyl acrylate; iso-octyl acrylate; n-octyl acrylate; isodecyl acrylate; iso-nonyl acrylate; octyl/decyl acrylate; lauryl acrylate; 2- propyl heptyl acrylate; tridecyl acrylate; hexadecyl acrylate; stearyl acrylate; iso-stearyl acrylate; behenyl acrylate; tetrahydrofurfuryl acrylate; 4-t.butyl cyclohexyl acrylate; 3,3,5- trimethylcyclohexane acrylate; isobornyl acrylate; dicyclopentyl acrylate
  • Suitable multifunctional ethylenically unsaturated monomers include but are not limited to the following (and combinations thereof), where the terms ethoxylated refers to chain extended compounds through the use of ethyleneoxide, propoxylated refers to chain extended compounds through the use of propylene oxide, and alkoxylated refers to chain extended compounds using either or both ethyleneoxide and propylene oxide.
  • Equivalent methacrylate compounds are also capable of being used, although those skilled in the art will appreciate that methacrylate compounds have lower reactivity than their equivalent acrylate counterparts:
  • the UV-curable ink or coating used in the present invention comprises one or more multifunctional ethylenically unsaturated monomers such as a di-functional, trifunctional, tetra-functional, penta-functional or hexa-functional ethylenically unsaturated monomers. More preferably, the UV-curable ink or coating used in the present invention comprises one or more hexa-functional ethylenically unsaturated monomers such as dipentaerythritol hexaacrylate or ethoxylated dipentaerythritol hexaacrylate.
  • Examples of monomers comprising free-radically polymerizable groups other than acrylate include N-vinyl amides.
  • N- vinyl amides include but are not limited to N- vinylcaprolactam (NVC), N-vinyl pyrollidone (NVP), diacetone acrylamide, N- vinyl oxazolidinone or N-vinyl methoxazolidinone, N-vinyl carbazole, N- acryloxyoxyethylcyclohexanedicarboximide, N-vinyl imidazole, N-vinyl-N- methylacetamide (VIMA) or acryloyl morpholine (ACMO).
  • NVC N- vinylcaprolactam
  • NDP N-vinyl pyrollidone
  • diacetone acrylamide N- vinyl oxazolidinone or N-vinyl methoxazolidinone
  • N-vinyl carbazole N- acryloxyoxyethylcyclohexan
  • Vinyl ethers such as 2-(2- vinyloxyethoxy)ethyl(meth)acrylate (VEEA, VEEM), diethylene glycol divinyl ether(DVE2), triethylene glycol divinyl ether (DVE3), ethyl vinyl ether, n-butyl vinyl ether, iso-butyl vinyl ether, tert-butyl vinyl ether, cyclohexyl vinyl ether (CHVE), 2- ethylhexyl vinyl ether (EHVE), dodecyl vinyl ether (DDVE), octadecyl vinyl ether(ODVE), 1-2-butanediol divinyl ether(BDDVE), 1-4, cyclohexanedimethanol divinylether (CHDM-di), hydroxybutyl vinylether (HBVE), 1-4- cyclohexanedimethanolmono vinylether (CHDM-mono), 1,2,4-trivinylcyclohexan
  • inventive compositions may also be compounded with any concentration and type of free-radically polymerizable oligomer, including but not restricted to polyurethane acrylates, polyester acrylates, poly ether acrylates and epoxy acrylates.
  • the UV-curable ink or coating used in the present invention comprises 5-75% by weight multifunctional monomer, more preferably 7-50% by weight. More preferably, the UV-curable ink or coating used in the present invention comprises 5-75% by weight hexa-functional monomer, more preferably 7-50% by weight.
  • compositions of the current invention are used for applications requiring low migration it is preferred that the total concentration of monofunctional monomer is less than 10% (w/w), preferably less than 5% (w/w) and most preferably essentially free of any monofunctional monomer.
  • suitable colorants include, but are not limited to organic or inorganic pigments and dyes.
  • the dyes include but are not limited to azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof and the like.
  • the colorant(s) is a pigment.
  • Organic pigments may be one pigment or a combination of pigments, such as for instance Pigment Yellow Numbers 12, 13, 14, 17, 74, 83, 114, 126, 127, 150, 174, 180, 188; Pigment Red Numbers 2, 22, 23, 48: 1, 48:2, 52, 52:1, 53, 57: 1, 112, 122, 166, 170, 184, 202, 266, 269; Pigment Orange Numbers 5, 16, 34, 36, 71; Pigment Blue Numbers 15, 15:3, 15:4; Pigment Violet Numbers 3, 19, 23, 27; and/or Pigment Green Number 7, 36.
  • Pigment Yellow Numbers 12, 13, 14, 17, 74, 83, 114, 126, 127, 150, 174, 180, 188 Pigment Red Numbers 2, 22, 23, 48: 1, 48:2, 52, 52:1, 53, 57: 1, 112, 122, 166, 170, 184, 202, 266, 269
  • Pigment Orange Numbers 5, 16, 34, 36, 71 Pigment Blue Numbers 15, 15:3, 15:
  • Inorganic pigments may be one of the following non-limiting pigments: iron oxides, titanium dioxides, chromium oxides, ferric ammonium ferrocyanides, ferric oxide blacks, Pigment Black Number 7 and/or Pigment White Numbers 6 and 7.
  • Other organic and inorganic pigments and dyes can also be employed, as well as combinations that achieve the colors desired.
  • the pigments are used as an acrylate dispersion.
  • the energy-curable compositions of the invention may also contain other components which enable them to perform in their intended application.
  • these other ink components include, but are not restricted to; stabilizers, wetting aids, slip agents, inert resins, antifoams, fillers, rheological aids, amine synergists, etc.
  • the energy-curable compositions of the invention may also optionally comprise any blend (i.e., one or more) of acrylic polymer or copolymer which is dissolved into it.
  • acrylic polymer or copolymer which is dissolved into it.
  • These polymers are usually prepared by the (thermal) free radical polymerization of blends of monomers including, but not restricted to, styrene, butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, isobutyl (meth)acrylate.
  • the acrylic polymer preferably has an average molecular weight of less than 20,000 g/mole and more preferably less than 10,000 g/mole. The molecular weight of such polymers can be measured by those techniques known in the art such as gel permeation chromatography. Examples of acrylic polymers include those supplied from Dianal, Elvacite Rohm and Haas and DSM, amongst others.
  • the acrylic polymer is preferably present in the compositions at
  • compositions of the current invention are preferably essentially free of any solvent. However, if required, compositions of the current invention can be diluted with solvents. Both organic and aqueous solvents may be used to dilute the curable compositions of the invention. The preferred maximum amount of any solvent that could be included in an ink composition is 10% (w/w).
  • the energy-curable compositions prepared according to the invention are particularly suited to the preparation of inkjet and screen printing inks. They are also particularly effective in the preparation of energy-curable primers and overprint varnishes.
  • photoinitiators having recognized low migration potential are used for low migration UV-curable compositions. Any combination and concentration of low migration potential photoinitiators may be used and types include, but are not restricted to; polymeric, polymerizable, difunctional, multifunctional photoinitiators. Both type I and type II photoinitiators within those classes are suitable. Suitable polymeric photoinitiators have previously been described.
  • photoinitiators suitable for low migration applications include bis(2,4,6-trimethylbenzoyl) phosphine oxide, l-[4-(2- Hy dr oxy ethoxy)-phenyl]-2-hydroxy-2-methy 1-1 -propane- 1 -one, Oligo- [2-Hy dr oxy-2- methyl-1- ((4-(l-methylvinyl)phenyl) propanone], Poly(oxy-1,2 ethanedyil)-alpha-(4- (dimethylamino)benzoyl)-omega-((4-(dimethylamino)benzoyl)oxy)-(9Cl), 2-Hydroxy-l- ⁇ 4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl ⁇ -2-methyl-propan-l-one, 2- hydroxy-1 -[4-(4-(2-hydroxy-2-methylpropionyl)phenoxy)phen
  • photoinitiator suitable for low migration applications can also be used in the present invention.
  • an amine synergist such as an aminoacrylate can be combined with any photoinitiator suitable for low migration applications.
  • photoinitiators may include any of those listed in EUPIA’s ‘Suitability List of Photoinitiators for Low Migration UV Printing Inks and Varnishes’, especially those in Group 1A and IB.
  • EUPIA has recommended that Article 3 of this provision be followed when producing printed matter for food packaging and has produced a detailed guideline for the selection of raw materials intended for printing inks for food packaging, along with guidelines on the testing of printed matter to ensure that regulatory requirements are achieved. Where no SML exists for a specific component then the following migration limits apply;
  • a target migration limit of no concern for non-evaluated substances of 10 ppb is the ultimate objective, to be consistent with other food contact materials.
  • a substance is acceptable if its specific migration does not exceed:
  • EUPIA also provides guidelines on how to measure the potential level of migratables arising from printed matter.
  • the non-food contact surface of packaging i.e. the outer surface
  • the primary packaging or secondary packaging labels and sleeves
  • the most likely route for migratable species from the ink contaminating the foodstuff is by what is known as set-off migration. This is where printed matter is stacked or reeled prior to it being filled with food.
  • set-off migration This is where printed matter is stacked or reeled prior to it being filled with food.
  • the ink comes into contact with what will be the food-contact surface of the package and migratable components of the ink can diffuse into this surface.
  • any energy-curable fluid which is applied to either the primary or secondary packaging of foodstuff should not result in contamination of that foodstuff at levels exceeding the limits detailed above.
  • molecular weight may be determined by gel permeation chromatography (GPC) with a monodisperse polystyrene equivalent molecular weight calibration standard and GPC columns (manufactured by PSS (Polymer Standards Service-USA, Inc), applied column combination: SDV 5 pm 1000A, SDV 5 pm 500A, SDV 5pm 100 A).
  • the flow rate in the columns is 1.0 ml/min, eluent: tetrahydrofuran, column temperature: 40°C, a differential refractive index detector (RI) and a UV-detector (254nm) were used.
  • the molecular weight of polymeric and oligomeric compounds is the number average molecular weight.
  • a method of reducing the gloss of a printed UV-curable ink comprising; a. printing one or more ink layers or coatings onto a substrate; b. curing the one or more ink layers or coatings using a UVB or UVC UV-LED light source; and c. curing the one or more ink layers or coatings using a UV-LED light source in the 365-405 nm range or a doped or undoped medium pressure mercury lamp.
  • step b. is performed with an LED light source in the range of 270-290 nm range.
  • step b. is performed with an LED UVB light source in the range of 280-320 nm range. 4. The method of paragraph 1, wherein step b. is performed with an LED UVC light source in the range of 250-280 nm range.
  • the photoinitiators in the one or more ink layers or coatings are selected from the group consisting of 1-Propanone, l,l'-oxydi-4,l-phenylene)bis[2-hydroxy-2-methyl-), l-[4- (2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropanone), and N,N-diisobutyl-7- methyl-9-oxo-9H-thioxanthene-3-carboxamide.
  • step b. is performed at a power level selected from the group consisting of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% 90% or 100%.
  • step c. is performed at 80-100% power.
  • UV curable inks or coatings comprise multifunctional monomer(s).
  • % and class of pigment is given for all of the pigment concentrates throughout the application. In each case the pigment is dispersed in an acrylate system.
  • Examples 1A-1D use a 4W/cm 280nm Phoseon FL400 LED pre-cure lamp followed by Integration Technology VZero2 200 W/cm medium pressure mercury final cure lamp.
  • Examples 1A-1D use a conventional Phoseon FireJet FJ200 12W 395nm LED pre-cure lamp followed by Integration Technology VZero2 200 W/cm medium pressure mercury final cure lamp.
  • Table 2 shows that the use of the 280 nm LED lamp (inventive) in contrast to the 395 nm LED lamp (comparative), has the desired effect of reducing gloss levels.
  • Example 1A-1D formulations were Jetted onto “Maxigloss” coated paper substrate using a Konica Minolta KM1024 printhead attached to an IIJ XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types (UV LED and Mercury Vapor - HG)
  • the gloss level using typical longer wavelength LED light sources has little effect on the overall gloss level of a print because of the relatively even cure profile through the ink. This is also independent of the dose and intensity of the typical LED lamps used, from low-power pinning lamps up to 395 nm LED lamps with power ratings of 12-16 W/cm2 running at full power.
  • Examples 1A-1D were printed using the same substrate and printhead as described in Example 2.
  • curing was carried out using the Phoseon 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2).
  • the irradiated prints were tested by rubbing a finger across the ink surface and looking for whether there is any ink smear or evidence of poor cure, and if passed whether they are resistant to fingernail scratch and thumb twist tests, which are well known to those skilled in the art.
  • Example 5 Print Test Examples 4A-4E were Jetted onto “Maxigloss” coated paper 5 substrate using a Konica Minolta KM1024 printhead attached to an IIJ XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types.
  • the two lamps used were the Phoseon 4W/cm 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2). 0
  • the gloss level at 60° Angle was recorded for each print after cure and detailed in Table 5.
  • the photoinitiator JRCURE 1901 (1-Propanone, l,P-(oxydi-4,l-phenylene)bis[2- hydroxy-2-methyl-), more commonly known as Esacure KIP 160, is very effective at bringing down the gloss levels because it has a strong UV chromophore centered at 280nm.
  • Omnirad 2959 (l-[4-(2-hydroxyethyl)- phenyl]-2-hydroxy-2-methylpropanone), with a strong chromophore at 275nm
  • Esacure 1100 N,N-diisobutyl-7-methyl-9-oxo-9H-thioxanthene-3-carboxamide
  • This beneficial effect is not exclusively tied to these materials, but by virtue of their Chromophore intensity and wavelength they are particularly preferred.
  • Example 6 Print Test - Gloss reduction through ink with composite colors
  • Example 6D Black black is a layer each of 70% deposition of 4D yellow, 4B magenta, 4A cyan and 4E black
  • Examples 6A-6D were Jetted onto “Maxigloss” coated paper substrate using a Konica Minolta KM1024 printhead attached to an IIJ XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types.
  • the two lamps used were the Phoseon 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2).
  • Table 6 Shows results for printing the ink combinations of the previously described inks 4 A, 4B, and 4D and 4E printed as composite colors (100% application of each of the 2 color combinations, with black being a 4-layer print of 70% each of Yellow, Magenta, Cyan and Black)
  • Example 8 Print Test Examples 7A-7D were Jetted onto “Maxigloss” coated paper substrate using a Konica Minolta KM1024 printhead attached to an II J XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types.
  • the two lamps used were the Phoseon 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2).
  • Example 8 Print Test Gloss reduction effect of additional ink colors other ink colors.
  • a UV curable inkjet coating was prepared according to the compositions in Table 9.
  • Esacure KIP 1 OOF has the same chemical structure as JRCURE 1901, photoinitiator.
  • Example 9 was Jetted onto “Maxigloss” coated paper substrate using a Konica Minolta KM1024 printhead attached to an IIJ XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types.
  • the two lamps used were the Phoseon 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2).
  • Example 11 A-l ID - UV curable inkjet inks with variable composition
  • Example 11A-11D were jetted onto “Maxigloss” coated paper substrate using a Konica Minolta KM1024 printhead attached to an IIJ XY200 printer operating at a printhead temperature of 38°C, print speed of 24m/min, printhead gap of 1mm and a distance of 30cm between the 2 lamp types.
  • the two lamps used were the Phoseon 280nm LED followed by a 200 W/cm medium pressure mercury lamp (Integration Technology VZero2).
  • Table 12 Gloss reduction effect of additional ink formulation styles
  • Example 1 ID a formulation containing a higher level of multifunctional monomers provides lower gloss on cure.
  • Example 11C a formulation containing a higher level of a hexafunctional monomer (SR399J) provides lower gloss on cure.
  • SR399J hexafunctional monomer
  • Examples 13A-13B were printed onto “Maxigloss” coated paper substrate using different K-bars to give different film thicknesses.
  • the two lamps used were the Phoseon 280nm LED followed by a 160 W/cm medium pressure mercury lamp, both at 100% power, fitted to a UV conveyor from Jenton International at a speed of 80 m/min.
  • Examples 13A (Comparative) and 13B (Comparative) are where no 280nm LED lamp was used, and where curing was using only the medium pressure mercury lamp at 100% power and 80 m/min line speed. Table 14. Gloss reduction effect with Film Thickness

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Electromagnetism (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)

Abstract

L'invention concerne une encre pour jet d'encre et un boîtier de lampe qui est capable de fournir les niveaux les plus élevés de qualité d'impression, mais également avec des niveaux variables de brillant.
PCT/GB2023/051193 2022-05-11 2023-05-05 Encres pour jet d'encre à faible brillant WO2023218168A1 (fr)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005031572A1 (de) * 2004-07-30 2006-03-23 Heidelberger Druckmaschinen Ag Verfahren zum Drucken und Nachbehandeln eines Aufdrucks
WO2010150023A2 (fr) 2009-06-25 2010-12-29 Sericol Limited Procédé d'impression
US20130083129A1 (en) * 2011-09-29 2013-04-04 Xerox Corporation Pre-treatment methods, apparatus, and systems for contact leveling radiation curable gel inks
GB2520595A (en) 2013-09-17 2015-05-27 Sericol Ltd Printing method
US9260616B2 (en) 2012-02-29 2016-02-16 Electronics For Imaging, Inc. Gloss-controllable, radiation-curable inkjet ink
WO2018060189A1 (fr) * 2016-09-30 2018-04-05 Agfa Nv Procédés d'impression à jet d'encre pour des surfaces décoratives
US20180298219A1 (en) * 2015-10-13 2018-10-18 Agfa Nv Uv curable inkjet inks
EP3822085A1 (fr) 2019-11-12 2021-05-19 Canon Production Printing Holding B.V. Procédé de controle de la brillance en impression jet d'encre

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005031572A1 (de) * 2004-07-30 2006-03-23 Heidelberger Druckmaschinen Ag Verfahren zum Drucken und Nachbehandeln eines Aufdrucks
WO2010150023A2 (fr) 2009-06-25 2010-12-29 Sericol Limited Procédé d'impression
US20130083129A1 (en) * 2011-09-29 2013-04-04 Xerox Corporation Pre-treatment methods, apparatus, and systems for contact leveling radiation curable gel inks
US9260616B2 (en) 2012-02-29 2016-02-16 Electronics For Imaging, Inc. Gloss-controllable, radiation-curable inkjet ink
GB2520595A (en) 2013-09-17 2015-05-27 Sericol Ltd Printing method
US20180298219A1 (en) * 2015-10-13 2018-10-18 Agfa Nv Uv curable inkjet inks
WO2018060189A1 (fr) * 2016-09-30 2018-04-05 Agfa Nv Procédés d'impression à jet d'encre pour des surfaces décoratives
EP3822085A1 (fr) 2019-11-12 2021-05-19 Canon Production Printing Holding B.V. Procédé de controle de la brillance en impression jet d'encre

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Title
"Extract from EuPIA Guideline on Printing Inks applied to the non-food contact surface of food packaging materials and articles", EFSA GUIDELINES, September 2009 (2009-09-01)

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