WO2023079296A1 - Jeu d'encres pour jet d'encre - Google Patents

Jeu d'encres pour jet d'encre Download PDF

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Publication number
WO2023079296A1
WO2023079296A1 PCT/GB2022/052783 GB2022052783W WO2023079296A1 WO 2023079296 A1 WO2023079296 A1 WO 2023079296A1 GB 2022052783 W GB2022052783 W GB 2022052783W WO 2023079296 A1 WO2023079296 A1 WO 2023079296A1
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Prior art keywords
ink
inks
ink set
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ppm
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PCT/GB2022/052783
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English (en)
Inventor
Angelique Runacre
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Fujifilm Speciality Ink Systems Limited
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Publication of WO2023079296A1 publication Critical patent/WO2023079296A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/10—Printing inks based on artificial resins
    • C09D11/101—Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/10—Printing inks based on artificial resins
    • C09D11/102—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/32—Inkjet printing inks characterised by colouring agents
    • C09D11/322—Pigment inks
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/40—Ink-sets specially adapted for multi-colour inkjet printing

Definitions

  • the present invention relates to a printing ink set and in particular to an aqueous compostable inkjet ink set.
  • BS EN 13432 The compostability of packaging items is now an important consideration resulting in a British Standard for compostability of packaging, BS EN 13432.
  • Packaging products that conform to the compostable criteria of this standard are suitable for composting.
  • BS EN 13432 provides five compostable criteria, where each test is undertaken according to the test methods specified in BS EN 13432. Only if a material passes every test requirement is it deemed compostable.
  • the five compostable criteria of BS EN 13432 are as follows:
  • Disintegration - the packaging sample is mixed with organic waste and maintained under test scale composting conditions for 12 weeks after which time no more than 10% of material fragments are allowed to be larger than 2 mm.
  • Biodegradability a measure of the actual metabolic, microbial conversion, under composting conditions, of the packaging sample into water, carbon dioxide and new cell biomass. Within a maximum of 6 months, biodegradation of the test sample must generate an amount of carbon dioxide that is at least 90% as much as the carbon dioxide given off from the control/reference material.
  • the composted packaging material must not have adverse effect on the bulk density, pH, salinity, volatile solids, total nitrogen, total phosphorus, total magnesium, total potassium and ammonium nitrogen characteristics of the compost.
  • the substrate is typically the main focus when considering compostability of packaging as the substrate is the largest component of the item.
  • the present inventors have now considered however the effect of the printed ink layer on compostability.
  • the printed ink layer has minimal effect on the physical degradation of the packaging as it contributes a small amount to the overall mass of the item.
  • the present inventors have found however that the printed ink layer can have an effect on the levels of heavy metals in the produced compost.
  • the present inventors considered the components of aqueous inkjet inks and found that the choice of pigment can have an effect on the compostability of the printed article having the inkjet ink set printed thereon.
  • pigments remain in the dried ink film.
  • Pigments can be a source of heavy metals, particularly copper, and hence can be the cause of an accumulation of heavy metals in the resulting compost. Heavy metals of course need to be restricted according to BS EN 13432.
  • the present invention provides an aqueous inkjet ink set comprising four or more aqueous inkjet inks, each aqueous inkjet ink comprising a pigment, water and an aqueous polyurethane (meth)acrylate dispersion, which is redispersible in water after thermal drying and before curing, wherein the inkjet ink set includes a blue and/or cyan ink, a yellow ink, a magenta ink and a black ink, and wherein the total amount of copper present in the inks of the ink set combined is 10,000 ppm or less.
  • the present inventors have found that the aqueous inkjet ink set of the present invention, which comprises inkjet inks as claimed, having a restricted amount of copper present therein and an aqueous polyurethane (meth) acrylate dispersion, which is redispersible in water after thermal drying and before curing, does not compromise the compostability of the printed item and is thus useful for packaging, particularly food packaging.
  • the aqueous inkjet ink set of the present invention comprises four or more aqueous inks.
  • the inkjet ink set includes a blue and/or cyan ink, a magenta ink, a yellow ink and a black ink.
  • This is a multi-chromatic inkjet ink set.
  • An ink set containing a blue and/or cyan ink, a magenta ink, a yellow ink and a black ink are often termed a so-called trichromatic set.
  • the inks in a trichromatic set can be used to produce a wide range of colours and tones.
  • a blue ink contains a blue pigment
  • a cyan ink contains a cyan pigment
  • a magenta ink contains a magenta pigment
  • a yellow ink contains a yellow pigment.
  • a black ink contains a black pigment or two or more non-black pigments which in combination provide a black colour.
  • the inks can be categorised on the CIELAB (Z_*a*b*) colour space system.
  • the red/green opponent colours are represented along the a* axis, with green at negative a* values and red at positive a* values.
  • the yellow/blue opponent colours are represented along the b* axis, with blue at negative b* values and yellow at positive b* values.
  • the cyan ink has a* value from -60 to -10 and b* value from -70 to -20, preferably a* value from -55 to -15 and b* value from -65 to -25, more preferably a* value from -50 to -20 and b* value from -60 to -30.
  • the L* value will depend on the lightness of the cyan ink.
  • the cyan ink may have L* value from 35 to 69, preferably 40 to 67, more preferably 42 to 65.
  • the cyan ink may be a lighter cyan and have L* value from 71 to 105, preferably 73 to 100, more preferably 75 to 95.
  • the cyan ink preferably contains the dispersible pigments PB16, PB27, PB29 or PB79.
  • the blue ink has a* value from -40 to 35 and b* value from -75 to -20, preferably a* value from -35 to 30 and b* value from -70 to -25, more preferably a* value from -30 to 25 and b* value from -65 to -30.
  • the L* value will depend on the lightness of the blue ink.
  • the blue ink may have L* value from 5 to 69, preferably 10 to 67, more preferably 15 to 65.
  • the blue ink may be a lighter blue and have L* value from 71 to 105, preferably 73 to 100, more preferably 75 to 95.
  • the blue ink preferably contains the dispersible pigments PB25, PB56, PB60 or PB61 .
  • the magenta ink has a* value from 55 to 105 and b* value from -40 to 10, preferably a* value from 60 to 100 and b* value from -35 to 5, more preferably a* value from 65 to 95 and b* value from -30 to 0, most preferably a* value from 70 to 90 and b* value from -25 to -5.
  • the L* value will depend on the lightness of the magenta ink.
  • the magenta ink may have L* value from 30 to 64, preferably 35 to 62, more preferably 40 to 60. Or the magenta ink may be a lighter magenta and have L* value from 66 to 100, preferably 68 to 95, more preferably 70 to 90.
  • the magenta ink preferably contains the dispersible pigments PR122, PR57.1 or PV19.
  • the yellow ink has a* value from -40 to 10 and b* value from 70 to 120, preferably a* value from -35 to 5 and b* value from 75 to 1 15, more preferably a* value from -30 to 0 and b* value from 80 to 110, most preferably a* value from -25 to -5 and b* value from 85 to 105.
  • the L* value will depend on the lightness of the yellow ink.
  • the yellow ink may have L* value from 70 to 104, preferably 75 to 102, more preferably 80 to 100. Or the yellow ink may be a lighter yellow and have L* value from 106 to 140, preferably 108 to 135, more preferably 110 to 130.
  • the yellow ink preferably contains the dispersible pigments PY74, PY120, PY151 , PY155 or PY180.
  • the black ink has a* value from -25 to 25 and b* value from -20 to 30, preferably a* value from -20 to 20 and b* value from -15 to 25, more preferably a* value from -15 to 15 and b* value from - 10 to 20, most preferably a* value from -10 to 10 and b* value from -5 to 15.
  • the L* value will depend on the lightness of the black ink.
  • the black ink may have a L* value from 6 to 30, preferably 8 to 25, more preferably 10 to 20.
  • the black ink may be a lighter black and have L* value from 35 to 75, preferably 40 to 70, more preferably 45 to 65.
  • the black ink preferably contains the dispersible pigment PBk7.
  • the black ink comprises two or more non-black pigments which in combination provide a black colour, wherein the black ink has L*a*b* values as described above for the black ink.
  • Examples of combinations of two or more non-black pigments that in combination can provide a black colour include blue and orange, red and green, yellow and purple, and blue and brown.
  • Examples of combinations of three or more non-black pigments that in combination can provide a black colour include cyan, magenta and yellow, yellow, cyan and violet, yellow, green and violet, yellow, blue and orange, green, orange and violet, red, cyan and yellow, and red, green and blue.
  • a preferred combination of three or more non-black pigments that in combination can provide a black colour include blue/cyan, magenta and yellow.
  • Preferred non-black pigments for use in a black ink comprising two or more non-black pigments which in combination provide a black colour include cyan, magenta, yellow, blue, brown, green, orange, red, violet and white.
  • Preferred cyan, blue, magenta and yellow pigments for use in a black ink comprising two or more non- black pigments which in combination provide a black colour are as described above for the cyan, blue, magenta and yellow inks.
  • Preferred green pigments for use in a black ink comprising two or more non-black pigments which in combination provide a black colour are Verona green, PG8, PG23, PG24 and PG54.
  • Preferred orange pigments for use in a black ink comprising two or more non-black pigments which in combination provide a black colour are dispersible pigment orange 43 and dispersible pigment orange 36, more preferably Kenalake Orange HPRLO.
  • Preferred violet dispersible pigments for use in a black ink comprising two or more non-black pigments which in combination provide a black colour are dispersible pigment violet 23, more preferably Hostaperm Violet RL-NF.
  • Other pigments that could be used include pigment violet 22 and pigment violet 122.
  • Preferred white dispersible pigments for use in a black ink comprising two or more non-black pigments which in combination provide a black colour are dispersible pigment white 6, more preferably Tipaque CR-60-2.
  • the aqueous inkjet inks of the aqueous inkjet ink set of the present invention each comprise one or more pigments.
  • the one or more pigments are dispersed in the liquid medium of the ink.
  • the one or more pigments are typically water-based pigment dispersions, which are combined with the other components of the ink by mixing.
  • pigments can greatly affect the compostability of the printed article having the inkjet ink set printed thereon.
  • Pigments can be a source of heavy metals, and hence can be the cause of an accumulation of heavy metals in the resulting compost.
  • Heavy metals need to be restricted according to BS EN 13432.
  • Particularly problematic pigments include phthalocyanine pigments, which are commonly employed for blue, cyan and green inks, owing to the presence of copper, and pigment yellow 150 which contains nickel.
  • Other pigments that are commonly used in the market, while not being based on heavy metals, may also contain trace amounts of heavy metals that will contribute to the total amount of heavy metal content in the printed item.
  • the total amount of copper present in the inks of the ink set combined is 10,000 ppm or less.
  • the total amount of copper in all of the inks of the ink set combined is 10,000 ppm or less.
  • the total amount of copper present in the inks of the ink set combined is 5,000 ppm or less, most preferably 1 ,000 ppm or less.
  • the total amount of copper in all of the inks of the ink set combined is preferably 5,000 ppm or less, most preferably 1 ,000 ppm or less.
  • Copper-based phthalocyanine pigments are hence preferably absent in the inks of the ink set of the present invention.
  • the inks of the ink set are free of copper-based phthalocyanine pigments.
  • the total amount of nickel in the inks of the ink set is also restricted.
  • the total amount of nickel in the inks of the ink set combined is 3,000 ppm or less.
  • the total amount of nickel present in the inks of the ink set combined is 2,000 ppm or less, most preferably 1 ,000 ppm or less.
  • the total amount of nickel in all of the inks of the ink set combined is preferably 2,000 ppm or less, most preferably 1 ,000 ppm or less.
  • the total amount of cadmium in the inks of the ink set is also restricted.
  • the total amount of cadmium in the inks of the ink set combined is 100 ppm or less.
  • the total amount of cadmium present in the inks of the ink set combined is 50 ppm or less, most preferably 25 ppm or less.
  • the total amount of cadmium in all of the inks of the ink set combined is preferably 50 ppm or less, most preferably 25 ppm or less.
  • the total amount of zinc, chromium, lead, molybdenum, cadmium, mercury, selenium and arsenic is also restricted.
  • the total amount of zinc in the inks of the ink set combined is 10,000 ppm or less, preferably 5,000 ppm or less and most preferably 1 ,000 ppm or less;
  • the total amount of chromium in the inks of the ink set combined is 5,000 ppm or less, preferably 2,000 ppm or less and most preferably 1 ,000 ppm or less;
  • the total amount of lead in the inks of the ink set combined is 5,000 ppm or less, preferably 2,000 ppm or less and most preferably 1 ,000 ppm or less;
  • the total amount of molybdenum in the inks of the ink set combined is 100 ppm or less, preferably 50 ppm or less, more preferably 25 ppm or less;
  • the total amount of molybdenum, cadmium, mercury, selenium and arsenic in the inks of the ink set combined is 100 ppm or less, more preferably 50 ppm or less and most preferably 25 ppm or less.
  • the total amount of heavy metals per se is restricted and in a preferred embodiment, the inks of the ink set are free of heavy metals.
  • the aqueous inkjet ink set as claimed which comprises inkjet inks having a restricted amount of copper present therein, preferably a restricted amount of copper and nickel, more preferably a restricted amount of copper, nickel and cadmium, and most preferably a restricted heavy metal content, does not compromise the compostability of the printed item.
  • ICP inductively coupled plasma atomic emission spectroscopy
  • the total heavy metal content present in each pigment and hence the ink as a whole can be determined by the following method:
  • the powder pigments are digested in a mixture of hydrochloric and nitric acids to ensure that the total metal content, rather than the free metal levels in the samples are correctly determined. This is achieved by gently heating a mixture of the pigment with a 33%v/v solution of HCI and HNO3 (ratio of acids 1 :3) on a hotplate until the pigment is dissolved.
  • a calibration standard is used for each metal. Suitable certified ICP-OES metal standards can be obtained from Sigma. It is necessary to take into account the various interference bands of each metal and ensure the concentration range brackets the concentrations relevant to the application.
  • a known amount of the prepared pigment sample is combined with a known amount of deionised water to create a solution that will position the concentration of metals present roughly into the centre of the calibration range.
  • the analysis can then be conducted on a suitable ICP unit, for examples a Thermo ICS-5000 ICP-OES. Both the dual radial and axial detectors are used. First, the calibration is run, followed by a period of blank deionised water to flush the system, the samples are then run in duplicate. Using the calibration, it is then possible to calculate the concentration of metals present.
  • Dispersible pigments are well-known in the art and are commercially available, for example, under the tradenames Paliotol (available from BASF pic), Cinquasia, I rgalite (both available from Ciba Speciality Chemicals) and Hostaperm (available from Clariant UK).
  • Aqueous pigment dispersions are commercially available, for example, under the tradenames Projet ADP (Fujifilm FFIC), Hostajet (Clariant) and SP (Fuji pigments).
  • the yellow pigment is an azo pigment, such as pigment yellow 151 , pigment yellow 155, pigment yellow 74, pigment yellow 13, pigment yellow 120 and pigment yellow 83.
  • the magenta pigment is a quinacridone pigment, such as Pigment violet 19 or Pigment red 122, or a mixed crystal quinacridone, such as Cromophtal Jet magenta 2BC and Cinquasia RT.
  • the black pigment is a carbon black pigment, such as pigment black 7.
  • the cyan pigment is a non-copper-based phthalocyanine pigment, such as PB16 and PB79.
  • the blue pigment is a non-copper-based phthalocyanine pigment, such as PB60.
  • Blue pigments PB22, PB24, PB25, PB28, PB50, PB56, PB60, PB61 , PB61 :1 , PB66, PB73, PB75, PB80, PB81 , PB82, PB84 and PB86.
  • Such pigments are not copper based.
  • Preferred examples include PB25, PB56, PB60 and PB61.
  • pigments, including PB15.4 and PB15.3 are not suitable pigments for use in the inkjet ink set of the present invention as these pigments are phthalocyanine-based pigments and have a high copper content.
  • Cyan pigments PB16, PB27, PB29 and PB79. Such pigments are not copper based.
  • Yellow pigments PY1 , PY1 :1 , PY2, PY3, PY4, PY5, PY6, PY9, PY10, PY12, PY13, PY14, PY16, PY17, PY21 , PY42, PY43, PY44, PY45, PY46, PY47, PY48, PY55, PY61 , PY62, PY62:1 , PY63 PY65, PY73, PY74, PY75, PY77, PY81 PY83, PY87, PY93, PY94, PY95, PY97, PY98, PY100, PY101 , PY104, PY105, PY108, PY109, PY110, PY111 , PY112, PY113, PY1 15, PY120, PY126, PY127, PY127:1 PY128, PY130, PY133, PY134, PY136, PY137, P
  • Magenta pigments PR122, PR57.1 and PV19.
  • Black pigments PBk6 and PBk7.
  • Pigment particles dispersed in the ink should be sufficiently small to allow the ink to pass through an inkjet nozzle, typically having a particle size less than 8 pm, preferably less than 5 pm, more preferably less than 1 pm and particularly preferably less than 0.5 pm.
  • the pigment is preferably present in each inkjet ink in an amount 0.5 to 15% by weight, more preferably from 0.5 to 5% by weight, based on the total weight of the ink.
  • a lighter colour ink will contain less pigment than a darker colour ink.
  • the inkjet ink set may further comprise additional colour inks, including a white ink, an orange ink, a green ink, a violet ink, a red ink and mixtures thereof.
  • a white ink contains a white pigment and so on.
  • the inkjet ink set further comprises a green ink.
  • a green ink contains a green pigment.
  • Green inks can often contain copper and/or cadmium and hence can also be a cause of an accumulation of heavy metals in the resulting compost.
  • the total amount of copper present in the inks of the ink set is restricted.
  • the total amount of cadmium present in the inks of the ink set is also restricted. Thus, the compostability of the printed item is improved.
  • the green pigment is an algae-based pigment or an inorganic pigment, such as Green earth or Verona green.
  • Green earth is known commercially as PG23 and is composed of ferrous and ferric silicates of potassium, manganese and aluminium.
  • Verona green is an inorganic pigment derived from the minerals celadonite and glauconite, which has the chemical formula K[(AI,Fe3 + ),(Fe2 + ,Mg](AISi3,Si4)Oio(OH)2.
  • the green ink has a* value from -105 to -55 and b* value from -15 to 35, preferably a* value from -100 to -60 and b* value from -10 to 30, more preferably a* value from -95 to -65 and b* value from -5 to 25, most preferably a* value from -90 to -70 and b* value from 0 to 20.
  • the green ink has L* value from 40 to 80, preferably 45 to 75, more preferably 50 to 70.
  • the green ink preferably contains dispersible pigment green 8, pigment green 23 or dispersible pigment green 54. Commercially-available pigments classified according to Colour Index International according to the following tradenames are preferred non-limiting examples of green pigments that can be used in the ink of the present invention: PG8, PG23, PG24 and PG54.
  • Additional colour inks include a white ink, an orange ink, a violet ink, a red ink and mixtures thereof.
  • the orange ink has a* value from 25 to 75 and b* value from 55 to 105, preferably a* value from 30 to 70 and b* value from 60 to 100, more preferably a* value from 35 to 65 and b* value from 65 to 95, most preferably a* value from 40 to 60 and b* value from 70 to 90.
  • the orange ink has L* value from 50 to 90, preferably 55 to 85, more preferably 60 to 80.
  • the orange ink preferably contains the dispersible pigment orange 43 or dispersible pigment orange 36, more preferably Kenalake Orange HPRLO.
  • the violet ink has a* value from 35 to 85 and b* value from -90 to -40, preferably a* value from 40 to 80 and b* value from -85 to -45, more preferably a* value from 45 to 75 and b* value from - 80 to -50, most preferably a* value from 50 to 70 and b* value from -75 to -55.
  • the violet ink has L* value from 10 to 50, preferably 15 to 45, more preferably 20 to 40.
  • the violet ink preferably contains the dispersible pigment violet 23, more preferably Hostaperm Violet RL-NF. Other pigments that could be used include pigment violet 22 and pigment violet 122.
  • the white ink has a* value from -25 to 25 and b* value from -20 to 30, preferably a* value from -20 to 20 and b* value from -15 to 25, more preferably a* value from -15 to 15 and b* value from - 10 to 20, most preferably a* value from -10 to 10 and b* value from -5 to 15.
  • the white ink has L* value from 81 to 99, preferably 83 to 97, more preferably 85 to 95.
  • the white ink preferably contains the dispersible pigment white 6, more preferably Tipaque CR-60-2.
  • the red ink has a* value from 50 to 100 and b* value from 20 to 75, preferably a* value from 60 to 90 and b* value from 30 to 65, more preferably a* value from 65 to 80 and b* value from 40 to 60.
  • the red ink has L* value from 30 to 65, preferably 35 to 62, more preferably 40 to 60.
  • Orange pigments PO1 , PO2, PO 3, PO 5, PO 13, PO15, PO16, PO 22, PO 34, PO 36, PO 38, PO 40, PO 41 , PO43, PO 46, PO 47, PO 48, PO 49, PO 51 , PO 52, PO 53, PO 60, PO 61 , PO 62, PO 64, PO 66, PO 67, PO 69, PO 71 , PO 72, PO 73, PO 74, PO 75, PO 77, PO 78, PO 79, PO 80, PO 81 , PO 82, PO 85 and PO 84.
  • Red pigments PR1 , PR2, PR3, PR4, PR5, PR6, PR7, PR8, PR9, PR12, PR13, PR14, PR15, PR17, PR19, PR21 , PR22, PR23, PR31 , PR32, PR38, PR47, PR48, PR48:2, PR48:3, PR48:4, PR49, PR49:1 , PR49:2, PR52:1 , PR52:2, PR53:1 , PR57, PR57:2, PR58:4, PR60:1 , PR61 , PR62, PR63, PR63:1 ,
  • PR101 1 , PR102, PR1 12, PR114, PR1 19, PR120, PR123, PR139, PR144, PR146, PR147, PR148,
  • PR21 1 PR212, PR213, PR214, PR216, PR220, PR221 , PR223, PR224, PR226, PR231 , PR232,
  • PR259 PR260, PR262, PR264, PR265, PR266, PR268, PR269, PR270, PR272, PR273, PR274,
  • PR275 PR276, PR279, PR282, PR286, PR287 and PR288.
  • Violet pigments PV3:3, PV5, PV5:1 , PV7, PV13, PV15, PV18, PV22, PV23, PV25, PV29, PV31 , PV32, PV36, PV37, PV42, PV44, PV50, PV55, PV58, PV122 and PV171.
  • White pigments PW6, PW6:1 , PW12, PW24, PW25, PW26, PW27, PW28, PW30, PW32 and PW33.
  • the white pigment is a titanium dioxide pigment.
  • the aqueous inkjet inks of the aqueous inkjet ink set of the present invention each comprise water.
  • the total amount of water present in each inkjet ink is preferably 40 to 90%, more preferably 50 to 70% by weight, based on the total weight of the ink.
  • the water may solely come from that already contained in the aqueous polyurethane (meth)acrylate dispersion or may be additionally and separately added water.
  • aqueous inkjet inks of the aqueous inkjet ink set of the present invention each comprise an aqueous polyurethane (meth)acrylate dispersion (PUD), which is redispersible in water after thermal drying and before curing.
  • PID polyurethane
  • Aqueous PUD in dispersed form is a high molecular weight material suspended in an aqueous continuous phase and, as such, the viscosity and molecular weight are largely decoupled.
  • PUDs are known for application in the wood-coating industry.
  • PUDs for the wood industry need to dry to a resilient film via water loss during an initial thermal drying process. This limits potential for damage during transportation of coated materials prior to (UV) cure which gives a final boost to the film toughness and chemical resistance.
  • this physical drying prior to (UV) cure is highly undesirable for the inkjet process and would lead to inks drying into printhead nozzles that would become permanently blocked.
  • dispersible aqueous PUDs suitable for the present invention are redispersible in water after thermal drying and before (UV) curing meaning that it is easier to clean the inkjet printer. This property allows removal of any ink deposits from inkjet printheads that may build up during the printing process. The ink deposits are easily removable by water after thermal drying and before curing without the formation of solid particulates that could block the printhead nozzles.
  • the PUD is aqueous. It is redispersible in water after thermal drying and before curing.
  • resolubility and resoluble are terms often used in the art to mean redispersibility and redispersible, respectively.
  • redispersibility of the inks of the ink set in water after thermal drying and before curing is controlled by the selection of the PUD.
  • PUDs are characterised by their physical drying properties. Most PUDs dry to a highly resilient film solely by water loss, where the final UV curing stage is only required to increase the final chemical resistance of the film. This characteristic makes the majority of PUDs unsuitable for inkjet application.
  • the test to measure the suitability of an aqueous PUD for use in the inks of the ink set of the present invention involves measuring the redispersibility of a PUD in water after thermal drying and before curing.
  • the aqueous PUD under test is blended with an aqueous pigment dispersion, such as Projet APD 1000 blue pigment dispersion (available from Fujifilm imaging colorants) , to facilitate observation of film redispersion and removal.
  • a surfactant such as fluoro surfactants Capstone FS31 , Capstone FS30 or Capstone FS34 (available from Dupont), is added to reduce surface tension and to allow wetting onto a suitable test substrate.
  • the composition is coated onto a suitable test substrate to produce a wet film.
  • the wet film is thermally dried and then cooled to room temperature. Redispersibilty of the thermally dried ink film in water can then be assessed by a water rub test.
  • the water rub test is well known in the art.
  • One then carries out a single rub where the saturated cloth is applied to one side of the dried PUD film and under light pressure, traverses the length of the dried PUD film in a single stroke.
  • the PUD In order for the PUD to be suitable for use in the present invention, the PUD must be dispersible in water after thermal drying and before curing. Put anotherway, the PUD film should be cleanly removed from the substrate surface leaving no residual staining visible to the naked eye after a single rub. The presence of the pigment in the film helps to determine if this requirement has been met as the substrate should become visible when the colour is removed. Further, no particulate matter visible to the naked eye should be transferred to the wiping cloth or to the substrate at the end of the wiping area.
  • the PUD after thermal drying and before curing can be redispersed in water in a single rub of the water rub test.
  • a PUD is water-dispersible after thermal drying and before curing if it maintains its water sensitivity/compatibility after thermal drying and before curing.
  • a water-sensitive functionalised PUD In order to maintain this water sensitivity/compatibility in a PUD after thermal drying and before curing, it is necessary to maintain a water-sensitive functionalised PUD after thermal drying and before curing.
  • Such functionality must be water-sensitive and therefore hydrophilic, and often includes ionic groups.
  • An example of a PUD having ionic functionality which is maintained after thermal drying and before curing is a PUD which has carboxylic acid functional groups which are neutralised with an alkali metal hydroxide, such as NaOH, to produce a metal salt.
  • Such a PUD maintains water dispersibility after thermal drying and before curing because the PUD salt is stable and compatible with water.
  • An example of a PUD having nonionic functionality which maintains oxygen functionality after thermal drying and before curing is a PUD having non-ionic blocks in the PUD chain of the polymer, such as polyether blocks.
  • Such redispersibility of the PUD in water after thermal drying and before curing allows for easy cleaning of the nozzles of an inkjet printer.
  • a PUD is not water-dispersible after thermal drying and before curing if it has reduced water sensitivity/compatibility after thermal drying. This occurs if the water-sensitive functional groups are lost during thermal drying of the ink to produce a thermally dried film.
  • a PUD has carboxylic acid functional groups and is neutralised with an amine salt as opposed to for example an alkali metal hydroxide
  • on thermal drying of an ink comprising such a functionalised PUD this results in the breaking down of the amine salt.
  • This amine salt is driven off during thermal drying and hence the ionic character of the PUD is lost and a PUD with carboxylic acid groups remains, which is not redispersible in water.
  • PUDs for use in the present invention which are redispersible in water after thermal drying and before curing, are available commercially, for example, from BASF.
  • the PUD which is redispersible in water after thermal drying and before curing preferably has a number average molecular weight of over 1 ,200 Daltons.
  • the PUD has a number average molecular weight of 1 ,200 to 20,000, preferably 1 ,500 to 10,000, and most preferably 2,500 to 5,000, as measured by Infinity 1260 supplied by Agilent technologies, using gel permeation chromatography calibrated against polystyrene standards.
  • the aqueous PUD which is redispersible in water after thermal drying and before curing is in dispersed form and preferably has a particle size of less than 200 nm as measured by Zeta PALS provided by Brookhaven Instruments Corporation.
  • the aqueous PUD which is redispersible in water after thermal drying and before curing with actinic (preferably UV) radiation, is non-dispersible in water after curing with actinic (preferably UV) radiation.
  • the aqueous PUD is crosslinkable when exposed to UV radiation as it is acrylate functionalised. This helps to provide the physical film properties required, such as chemical and scratch resistance.
  • the inks of the ink set of the present invention each comprise 20 to 80%, more preferably 30 to 70% and most preferably 40 to 60 % by weight of aqueous PUD, which is redispersible in water after thermal drying, based on the total weight of the ink.
  • the aqueous PUD typically contains around 40% solids in 60% water.
  • the inks of the ink set each preferably comprise 20 to 80% by weight of aqueous PUD, which is redispersible in water after thermal drying, based on the total weight of the ink, this means that the inks of the ink set each preferably comprise 8 to 32% solids and 12 to 48% water from the aqueous PUD, based on the total weight of the ink.
  • each aqueous inkjet ink comprises an aqueous polyurethane (meth) acrylate dispersion, which is redispersible in water after thermal drying and before curing, exhibits both the physical film properties required, such as chemical and scratch resistance, but, still has the desired low migration/odour properties and viscosity required for inkjet and packaging (preferably food packaging) application. It is thus useful for industrial applications, including packaging for indirect food contact, and single pass printing.
  • the PUD remains in the dried ink film.
  • the effect on compostability is minimal as only small amounts are present and thus, the presence of the PUD does not affect compostability.
  • the aqueous polyurethane (meth)acrylate dispersion is in capsule form.
  • the PUD is in the form of polymeric shell surrounding a core.
  • the capsules are dispersed in the aqueous medium.
  • the core preferably contains one or more of the components of the ink.
  • the core preferably contains the radiation-curable material and/or the photoinitiator when present. Further details of such microcapsules are provided in WO 2015/158745. If the ink is cured by exposure to a source of actinic radiation without an inert environment, one or more photoinitiators will be required. If the ink is cured by exposure to a source of low-energy electron beam radiation or a source of actinic radiation in an inert environment, the ink may still contain a photoinitiator, although photoinitiators are not required.
  • the inks of the ink set of the present invention each further comprise a water-dispersible or water-soluble photoinitiator.
  • the water-dispersible or water-soluble photoinitiator can be selected from any of those known in the art.
  • free radical photoinitiators such as, for example, Irgacure 2959 and 2-hydroxy- 1- ⁇ 4-[2-(2-hydroxyethoxy)ethoxy]phenyl ⁇ -2-methylpropan-1-one (PM10028).
  • photoinitiators are known and commercially available.
  • Polymeric photoinitiators are also preferred.
  • the ink comprises a plurality of free radical photoinitiators.
  • the total number of free radical photoinitiators present is preferably from one to five, and more preferably, two or more free radical photoinitiators are present in the ink.
  • the photoinitiator if present, is present in an amount of 1 to 10% by weight, preferably 2 to 5% by weight, based on the total weight of the ink.
  • a photoinitiator is optional as it is not necessary to include a photoinitiator in the inks of the ink set in order to achieve a thorough cure of the ink. This is because the ink can cure without the presence of a photoinitiator by curing with a low-energy electron beam or curing by actinic radiation in an inert environment.
  • the photoinitiator is present in an amount of less than 10% by weight, preferably less than 5% by weight, more preferably less than 3%, more preferably less than 1 %, based on the total weight of the ink.
  • the inks of the ink set may be substantially free of photoinitiator.
  • substantially free is meant that no photoinitiator is intentionally added to the inks.
  • minor amounts of photoinitiator which may be present as impurities in commercially available inkjet ink components, are tolerated.
  • the inks may comprise less than 0.5% by weight of photoinitiator, more preferably less than 0.1 % by weight of photoinitiator, most preferably less than 0.05% by weight of photoinitiator, based on the total weight of the ink.
  • the inks may also be free of photoinitiator.
  • an inkjet ink that is cured with a low-energy electron beam or actinic radiation in an inert environment may still contain a small amount of photoinitiator such as 1 to 5% by weight of a photoinitiator, based on the total weight of the ink.
  • the aqueous inkjet inks of the aqueous inkjet ink set of the present invention may each comprise an organic solvent.
  • the organic solvent is in the form of a liquid at ambient temperatures and is capable of acting as a carrier for the components of the ink.
  • the organic solvent may be a single solvent or a mixture of two or more solvents.
  • the organic solvent is required to evaporate from the printed ink, typically on heating, in order to allow the ink to dry.
  • the solvent can be selected from any solvent commonly used in the printing industry, such as glycol ethers, glycol ether esters, alcohols, glycols, ketones and esters.
  • the majority of the organic solvents are evaporated from the ink film. Traces of the solvents can remain in the ink film after drying however.
  • the solvents are biodegradable solvents and so do not negatively affect compostability.
  • co-solvents suitable for the present invention are water-soluble polyols or glycols.
  • glycerol polyethylene glycol
  • polypropylene glycol examples of co-solvents suitable for the present invention.
  • the organic solvent is preferably present in each inkjet ink in an amount of 1 % to 40 % by weight, more preferably 5% to 15% by weight, based on the total weight of the ink.
  • the aqueous inkjet inks of the aqueous inkjet ink set of the present invention may each comprise a radiation-curable material.
  • the radiation-curable material preferably comprises a radiation-curable monomer, and more preferably a (meth)acrylate monomer.
  • the radiation-curable material is not particularly limited and the formulator is free to include any such radiation-curable material in the inks to improve the properties or performance of the ink.
  • This radiation- curable material can include any radiation-curable material readily available and known in the art in inkjet inks.
  • radiation-curable is meant a material that polymerises and/or crosslinks upon irradiation, for example, when exposed to actinic radiation, in the presence of a photoinitiator.
  • the amount of radiation-curable material is not limited other than by the constraints imposed by the use in an inkjet ink, such as viscosity, stability, toxicity etc.
  • the inkjet inks each comprise 5 to 50%, more preferably 5 to 20%, by weight of radiation-curable material, preferably a radiation-curable monomer, based on the total weight of the ink.
  • the inkjet inks of the ink set of the present invention each comprise a radiation-curable monomer.
  • monomers may possess different degrees of functionality, which include mono, di, tri and higher functionality monomers.
  • the inks each comprise a di- and/or multifunctional radiation-curable monomer.
  • mono and difunctional are intended to have their standard meanings, i.e. one ortwo groups, respectively, which take part in the polymerisation reaction on curing.
  • Multifunctional (which does not include difunctional) is intended to have its standard meaning, i.e. three or more groups, respectively, which take part in the polymerisation reaction on curing.
  • the radiation-curable monomer is a di-, tri-, tetra-, penta- or hexa- functional monomer, i.e. the radiation-curable monomer has two, three, four, five or six functional groups.
  • the inks each comprise a difunctional monomer and/or a multifunctional monomer, preferably a difunctional monomer.
  • the inkjet inks each comprise at least two di- and/or multifunctional radiation-curable monomers and more preferably, at least two difunctional monomers.
  • the functional group of the di- and/or multifunctional radiation-curable monomer, which is utilised in the inks may be the same or different but must take part in the polymerisation reaction on curing.
  • Examples of such functional groups include any groups that are capable of polymerising upon exposure to radiation and are preferably selected from a (meth) acrylate group and a vinyl ether group.
  • the di- and/or multifunctional radiation-curable monomer may possess different degrees of functionality, and a mixture including combinations of di, tri and higher functionality monomers may be used.
  • the substituents of the di- and/or multifunctional radiation-curable monomer are not limited other than by the constraints imposed by the use in an ink-jet ink, such as viscosity, stability, toxicity etc.
  • the substituents are typically alkyl, cycloalkyl, aryl and combinations thereof, any of which may be interrupted by heteroatoms.
  • Non-limiting examples of substituents commonly used in the art include C1-18 alkyl, C3-18 cycloalkyl, Cs-io aryl and combinations thereof, such as CB- aryl- or C3-18 cycloalkylsubstituted C1-18 alkyl, any of which may be interrupted by 1-16 heteroatoms, such as oxygen or nitrogen, with nitrogen further substituted by any of the above described substituents.
  • the substituents may together also form a cyclic structure.
  • the inks each comprise 5 to 50%, more preferably 5 to 20%, by weight of a di- and/or multifunctional radiation-curable monomer, based on the total weight of the ink.
  • di- and/or multifunctional radiation-curable monomer examples include difunctional (meth)acrylate monomers, multifunctional (meth)acrylate monomers, divinyl ether monomers, multifunctional vinyl ether monomers and di- and/or multifunctional vinyl ether (meth)acrylate monomers. Mixtures of di- and/or multifunctional radiation-curable monomers may also be used.
  • the radiation-curable material comprises a (meth)acrylate monomer, more preferably a di- and/or multifunctional (meth) acrylate monomer.
  • the inkjet inks comprise a difunctional (meth) acrylate monomer.
  • (meth)acrylate is intended herein to have its standard meaning, i.e. acrylate and/or methacrylate.
  • Difunctional (meth)acrylate monomers are well known in the art and a detailed description is therefore not required. Examples include hexanediol diacrylate (HDDA), 1 ,8-octanediol diacrylate, 1 ,9- nonanediol diacrylate, 1 ,10-decanediol diacrylate (DDDA), 1 ,11-undecanediol diacrylate and 1 ,12- dodecanediol diacrylate, polyethylene glycol diacrylate (for example tetraethylene glycol diacrylate, PEG200DA, PEG300DA, PEG400DA, PEG600DA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), tricyclodecane dimethanol diacrylate (TCDDMDA), neopentylglycol diacrylate, 3-methyl-1 ,5-pentanediol diacrylate (3-MPDA),
  • esters of methacrylic acid such as hexanediol dimethacrylate, 1 ,8-octanediol dimethacrylate, 1 ,9-nonanediol dimethacrylate, 1 ,10-decanediol dimethacrylate, 1 ,11-undecanediol dimethacrylate and 1 ,12-dodecanediol dimethacrylate, triethyleneglycol dimethacrylate, diethyleneglycol dimethacrylate, ethyleneglycol dimethacrylate, 1 ,4-butanediol dimethacrylate and mixtures thereof.
  • 3-MPDA is particularly preferred as this monomer further improves adhesion to the substrate. Therefore, in a preferred embodiment, the inks each comprise 3-MPDA.
  • the inks each comprise 5 to 50% by weight, more preferably 5 to 40% by weight and most preferably 5 to 20% by weight of a difunctional (meth) acrylate monomer, based on the total weight of the ink.
  • the inks each comprise a multifunctional (meth)acrylate monomer.
  • Suitable multifunctional (meth)acrylate monomers include tri-, tetra-, penta-, hexa-, hepta- and octa-functional monomers.
  • multifunctional acrylate monomers examples include trimethylolpropane triacrylate, dipentaerythritol triacrylate, tri(propylene glycol) triacrylate, bis(pentaerythritol) hexaacrylate, and the acrylate esters of ethoxylated or propoxylated glycols and polyols, for example, ethoxylated trimethylolpropane triacrylate and ethoxylated pentaerythritol tetraacrylate (EOPETTA, also known as PPTTA), and mixtures thereof.
  • Suitable multifunctional (meth)acrylate monomers also include esters of methacrylic acid (i.e.
  • the inks each comprise ethoxylated trimethylolpropane triacrylate.
  • the amount of the multifunctional (meth)acrylate monomer, when present, is preferably 5-35%, more preferably 5-20%, by weight, based on the total weight of the ink.
  • the di- and/or multifunctional radiation-curable monomer may have at least one vinyl ether functional group.
  • the inks each comprise a divinyl ether monomer, a multifunctional vinyl ether monomer, a difunctional vinyl ether (meth)acrylate monomer and/or a multifunctional vinyl ether (meth)acrylate monomer.
  • the inks each comprise a difunctional vinyl ether (meth)acrylate monomer and/or a divinyl ether monomer.
  • the inks each comprise 1 to 40% by weight, preferably 2 to 30% by weight, more preferably 5 to 20% by weight of a divinyl ether monomer, a multifunctional vinyl ether monomer, a difunctional vinyl ether (meth) acrylate monomer and/or a multifunctional vinyl ether (meth)acrylate monomer, based on the total weight of the ink.
  • a divinyl ether monomer preferably 2 to 30% by weight, more preferably 5 to 20% by weight of a divinyl ether monomer, a multifunctional vinyl ether monomer, a difunctional vinyl ether (meth) acrylate monomer and/or a multifunctional vinyl ether (meth)acrylate monomer, based on the total weight of the ink.
  • Examples of a divinyl ether monomer include triethylene glycol divinyl ether (DVE-3), diethylene glycol divinyl ether, 1 ,4-cyclohexanedimethanol divinyl ether, bis[4-(vinyloxy)butyl] 1 ,6- hexanediylbiscarbamate, bis[4-(vinyloxy)butyl] isophthalate, bis[4-(vinyloxy)butyl] (methylenedi-4,1- phenylene)biscarbamate, bis[4-(vinyloxy)butyl] succinate, bis[4-(vinyloxy)butyl]terephthalate, bis[4- (vinyloxymethyl)cyclohexylmethyl] glutarate, 1 ,4-butanediol divinyl ether and mixtures thereof.
  • Triethylene glycol divinyl ether (DVE-3) is particularly preferred. Therefore, in a preferred embodiment, the inks each
  • An example of a multifunctional vinyl ether monomer is tris[4-(vinyloxy)butyl] trimellitate.
  • Examples of a vinyl ether (meth)acrylate monomer include, 2-(2-vinyloxy ethoxy)ethyl methacrylate (VEEM), 2-(2-vinyloxy ethoxy)ethyl acrylate (VEEA) and mixtures thereof.
  • VEEM 2-(2-vinyloxy ethoxy)ethyl methacrylate
  • VEEA 2-(2-vinyloxy ethoxy)ethyl acrylate
  • the inks each comprise VEEA.
  • the di- and/or multifunctional radiation-curable monomer is selected from 1 ,10-decanediol diacrylate (DDDA), hexanediol diacrylate (HDDA), polyethylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), 3-methyl 1 ,5- pentanediol diacrylate (3-MPDA), dipropylene glycol diacrylate (DPGDA), tricyclodecane dimethanol diacrylate (TCDDMDA), propoxylated neopentyl glycol diacrylate (NPGPODA), trimethylolpropane triacrylate (TMPTA), di-trimethylolpropane tetraacrylate (DiTMPTA), di-pentaerythritol hexaacrylate (DPHA), ethoxylated trimethylolpropane triacrylate (EOTMPTA), ethoxylated pentaerythritol tetra
  • the difunctional monomer is selected from 1 ,10-decanediol diacrylate (DDDA), hexanediol diacrylate (HDDA), polyethylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), 3-methyl 1 ,5- pentanediol diacrylate (3-MPDA), dipropylene glycol diacrylate (DPGDA), tricyclodecane dimethanol diacrylate (TCDDMDA), propoxylated neopentyl glycol diacrylate (NPGPODA), triethylene glycol divinyl ether (DVE-3), 2-(2-vinyloxy ethoxy)ethyl acrylate (VEEA) and mixtures thereof.
  • DDDA 1 ,10-decanediol diacrylate
  • HDDA hexanediol diacrylate
  • TPGDA tripropylene glycol diacrylate
  • the difunctional monomer comprises 3-methyl 1 ,5-pentanediol diacrylate (3-MPDA).
  • Monomers typically have a molecular weight of less than 600, preferably more than 200 and less than 450. Monomers are typically added to inkjet inks to reduce the viscosity of the inkjet ink. They therefore preferably have a viscosity of less than 150 mPas at 25°C, more preferably less than 10OmPas at 25°C and most preferably less than 20 mPas at 25°C. Monomer viscosities can be measured using an ARG2 rheometer manufactured by T.A. Instruments, which uses a 40 mm oblique 12° steel cone at 25°C with a shear rate of 25 s 1 . Accordingly, monomer viscosities can be measured using a rotational rheometer having a 40 mm diameter / 2° steel cone at 25°C with a shear rate of 25 s 1 .
  • the inks of the ink set of the present invention may further comprise a monofunctional monomer, such as a monofunctional (meth) acrylate monomer.
  • a radiation-curable monofunctional monomer has one functional group, which takes part in the polymerisation reaction on curing.
  • the polymerisable groups can be any group that are capable of polymerising upon exposure to radiation and are preferably selected from a (meth)acrylate group and a vinyl ether group.
  • the substituents of the monofunctional monomer are not limited other than by the constraints imposed by the use in an inkjet ink, such as viscosity, stability, toxicity etc.
  • the substituents are typically alkyl, cycloalkyl, aryl and combinations thereof, any of which may be interrupted by heteroatoms.
  • Non-limiting examples of substituents commonly used in the art include C1-18 alkyl, C3-18 cycloalkyl, Cs- aryl and combinations thereof, such as CB- aryl- or C3-18 cycloalkyl-substituted C1-18 alkyl, any of which may be interrupted by 1-10 heteroatoms, such as oxygen or nitrogen, with nitrogen further substituted by any of the above described substituents.
  • the substituents may together also form a cyclic structure.
  • the amount of monofunctional monomer, when present, is preferably 1-30% by weight, more preferably 5-20% by weight, based on the total weight of the ink.
  • the inks may each comprise a monofunctional (meth) acrylate monomer, which are well known in the art and are preferably the esters of acrylic acid. A detailed description is therefore not required. Mixtures of (meth)acrylates may also be used.
  • the substituents of the monofunctional (meth)acrylate monomer are not limited other than by the constraints imposed by the use in an inkjet ink, such as viscosity, stability, toxicity etc.
  • the monofunctional (meth)acrylate monomer may be a cyclic monofunctional (meth)acrylate monomer and/or an acyclic-hydrocarbon monofunctional (meth)acrylate monomer.
  • the monofunctional (meth)acrylate monomer may comprise a cyclic monofunctional (meth)acrylate monomer.
  • the substituents of the cyclic monofunctional (meth)acrylate monomer are typically cycloalkyl, aryl and combinations thereof, any of which may be interrupted by heteroatoms and/or substituted by alkyl.
  • substituents commonly used in the art include C3-18 cycloalkyl, Cs- aryl and combinations thereof, any of which may substituted with alkyl (such as C1-18 alkyl) and/or any of which may be interrupted by 1-10 heteroatoms, such as oxygen or nitrogen, with nitrogen further substituted by any of the above described substituents.
  • the substituents may together also form a cyclic structure.
  • the cyclic monofunctional (meth)acrylate monomer may be selected from isobornyl acrylate (IBOA), phenoxyethyl acrylate (PEA), cyclic TMP formal acrylate (CTFA), tetrahydrofurfuryl acrylate (THFA), (2- methyl-2-ethyl-1 ,3-dioxolane-4-yl)methyl acrylate (MEDA/Medol-10), 4-te/Y-butylcyclohexyl acrylate (TBCHA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), benzyl acrylate (BA) and mixtures thereof.
  • the cyclic monofunctional (meth)acrylate monomer comprises benzyl acrylate (BA).
  • the monofunctional (meth)acrylate monomer may comprise an acyclic-hydrocarbon monofunctional (meth)acrylate monomer.
  • the substituents of the acyclic-hydrocarbon monofunctional (meth)acrylate monomer are typically alkyl, which may be interrupted by heteroatoms.
  • a non-limiting example of a substituent commonly used in the art is C1-18 alkyl, which may be interrupted by 1-10 heteroatoms, such as oxygen or nitrogen, with nitrogen further substituted.
  • the acyclic-hydrocarbon monofunctional (meth) acrylate monomer contains a linear or branched C6-C20 group. It may be selected from octadecyl acrylate (ODA), 2-(2-ethoxyethoxy)ethyl acrylate, tridecyl acrylate (TDA), isodecyl acrylate (IDA), lauryl acrylate and mixtures thereof.
  • ODA octadecyl acrylate
  • TDA tridecyl acrylate
  • IDA isodecyl acrylate
  • lauryl acrylate and mixtures thereof.
  • the acyclic-hydrocarbon monofunctional (meth)acrylate monomer contains a linear C6-C20 group.
  • the acyclic-hydrocarbon monofunctional (meth)acrylate monomer comprises lauryl acrylate.
  • the monofunctional (meth) acrylate monomer is selected from isobornyl acrylate (IBOA), phenoxyethyl acrylate (PEA), cyclic TMP formal acrylate (CTFA), tetrahydrofurfuryl acrylate (THFA), (2-methyl-2-ethyl-1 ,3-dioxolane-4-yl)methyl acrylate (MEDA/Medol- 10), 4-terf-butylcyclohexyl acrylate (TBCHA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), benzyl acrylate (BA), octadecyl acrylate (ODA), 2-(2-ethoxyethoxy)ethyl acrylate, tridecyl acrylate (TDA), isodecyl acrylate (IDA), lauryl acrylate and mixtures thereof.
  • IBOA isobornyl acrylate
  • PEA phenoxyethyl
  • the inks each comprise a monofunctional (meth)acrylate monomer present in 1-30% by weight, more preferably 5-20% by weight, based on the total weight of the ink.
  • the inks may further each include at least one N-vinyl amide monomer and/or N-(meth)acryloyl amine monomer.
  • N-Vinyl amide monomers are well-known monomers in the art.
  • N-Vinyl amide monomers have a vinyl group attached to the nitrogen atom of an amide which may be further substituted in an analogous manner to the (meth)acrylate monomers.
  • Preferred examples are N-vinyl caprolactam (NVC), N-vinyl pyrrolidone (NVP), N-vinyl piperidone, N-vinyl formamide and N-vinyl acetamide.
  • N-acryloyl amine monomers are also well-known in the art.
  • N-Acryloyl amine monomers also have a vinyl group attached to an amide but via the carbonyl carbon atom and again may be further substituted in an analogous manner to the (meth)acrylate monomers.
  • a preferred example is N- acryloylmorpholine (ACMO).
  • the inks preferably comprises at least one of NVC and/or ACMO.
  • N-Vinyl amide monomers are particularly preferred, and most preferably NVC.
  • the inks each comprise at least one N-vinyl amide monomer and/or N- (meth)acryloyl amine monomer present in 5-30% by weight, more preferably 5-20% by weight, based on the total weight of the ink.
  • the inks may also each comprise one or more N-vinyl monomers other than an N-vinyl amide monomer and/or N-(meth)acryloyl amine monomer.
  • N-vinyl monomers other than an N-vinyl amide monomer and/or N-(meth)acryloyl amine monomer. Examples include N-vinyl carbazole, N-vinyl indole and N- vinyl imidazole.
  • the amount of monofunctional monomers present in the inks is restricted as monofunctional monomers are more likely to migrate for packaging for indirect food contact. Accordingly, in a preferred embodiment, the inks each contain less than 5% by weight, more preferably less than 2% by weight, more preferably less than 1 % by weight and most preferably is substantially free of monofunctional monomer, where the amounts are based on the total weight of the ink.
  • substantially free is meant that only small amounts will be present, for example as impurities in the radiation-curable materials present or as a component in a commercially available pigment dispersion.
  • no monofunctional monomer is intentionally added to the inks.
  • the inks may each comprise less than 0.5% by weight of monofunctional monomer, more preferably less than 0.1% by weight of monofunctional monomer, most preferably less than 0.05% by weight of monofunctional monomer, based on the total weight of the ink.
  • the inks are each free of monofunctional monomer.
  • the radiation-curable monomer is selected from lauryl acrylate, IBOA, CTFA, DDDA, PEG200DA, PEG400DA, PEG600DA, NPGPODA, TMPTA, DPHA and mixtures thereof.
  • Such monomers have a high bio-content and so do not negatively affect compostability.
  • the inks each further comprise a radiation-curable (i.e. polymerisable) oligomer, such as a (meth)acrylate oligomer.
  • a radiation-curable (i.e. polymerisable) oligomer such as a (meth)acrylate oligomer.
  • Any radiation-curable oligomer that is compatible with the other ink components is suitable for use in the inks of the ink set of the present invention.
  • the inks each comprise a (meth)acrylate oligomer.
  • curable oligomer has its standard meaning in the art, namely that the component is partially reacted to form a pre-polymer having a plurality of repeating monomer units, which is capable of further polymerisation.
  • the oligomer preferably has a molecular weight of at least 600.
  • the molecular weight is preferably 4,000 or less.
  • Molecular weights (number average) can be calculated if the structure of the oligomer is known or molecular weights can be measured using gel permeation chromatography using polystyrene standards.
  • the oligomers may possess different degrees of functionality, and a mixture including combinations of mono, di, tri and higher functionality oligomers may be used.
  • the degree of functionality of the oligomer determines the degree of crosslinking and hence the properties of the cured ink.
  • the oligomer is preferably multifunctional meaning that it contains on average more than one reactive functional group per molecule.
  • the average degree of functionality is preferably from 2 to 6.
  • Oligomers are typically have a viscosity of 150 mPas or above at 25°C.
  • Preferred oligomers for inclusion in the inks have a viscosity of 0.5 to 10 Pas at 50°C.
  • Oligomer viscosities can be measured using an ARG2 rheometer manufactured by T.A. Instruments, which uses a 40 mm oblique I 2° steel cone at 60°C with a shear rate of 25 s 1 . Accordingly, oligomer viscosities can be measured using a rotational rheometer having a 40 mm diameter 12° steel cone at 60°C with a shear rate of 25 s 1 .
  • Radiation-curable oligomers comprise a backbone, for example a polyester, urethane, epoxy or polyether backbone, and one or more radiation-curable groups.
  • the polymerisable group can be any group that is capable of polymerising upon exposure to radiation.
  • the oligomers are (meth)acrylate oligomers.
  • the oligomer may include amine functionality, as the amine acts as an activator without the drawback of migration associated with low-molecular weight amines.
  • the radiation-curable oligomer is amine modified.
  • the radiation-curable oligomer is an amine-modified (meth)acrylate oligomer.
  • Particularly preferred radiation-curable oligomers are di-, tri-, tetra-, penta- or hexa-functional acrylates.
  • the radiation-curable oligomer is an amine-modified acrylate oligomer.
  • a suitable amine-modified polyester acrylate oligomer is commercially available as UVP6600.
  • a suitable amine- modified polyether acrylate oligomer is commercially available as CN3715LM.
  • radiation-curable oligomers include epoxy based materials such as bisphenol A epoxy acrylates and epoxy novolac acrylates, which have fast cure speeds and provide cured films with good solvent resistance.
  • the amount of radiation-curable oligomer, when present, is 0.1-10% by weight, preferably 0.1 to 6% by weight, based on the total weight of the ink.
  • each ink of the inkjet ink set of the present invention preferably further comprises a surfactant.
  • surfactants are well-known in the art and a detailed description is not required.
  • suitable surfactant include Surfynol 440 and Capstone FS-1 .
  • Adjustment of the surface tension of the inks allows control of the surface wetting of the inks on various substrates, for example, plastic substrates. Too high a surface tension can lead to ink pooling and/or a mottled appearance in high coverage areas of the print. Too low a surface tension can lead to excessive ink bleed between different coloured inks.
  • the surface tension is preferably in the range of 20-40 mNm 1 and more preferably 25-35 mNm 1 .
  • the surfactant is present in each inkjet ink in an amount of 0.01 to 5% by weight, based on the total weight of the ink.
  • the inks of the ink set of the present invention preferably each further comprise a humectant.
  • humectant can be any material that acts to retain water in the system, which are well-known in the art.
  • humectants suitable for the present invention are water-soluble polyols or glycols.
  • glycerol polyethylene glycol
  • polypropylene glycol polypropylene glycol
  • the most preferred humectant is 2- methyl 1 ,3 propanediol.
  • the inks each contain 0.1 to 10% by weight humectant, more preferably 0.1 to 6% by weight humectant, based on the total weight of the ink.
  • the inks of the ink set of the present invention optionally each further comprise a thickener, more preferably a synthetic thickener to facilitate the adjustment of the ink viscosity. Thickeners and more specifically, synthetic thickeners, are well-known in the art and a detailed description is therefore not required.
  • the ink each contain 0.1 to 5% by weight thickener, more preferably 0.1 to 2% by weight thickener, based on the total weight of the ink.
  • the ink is free from thickener.
  • the synthetic thickener when present, has Newtonian rheology.
  • the synthetic thickener is not thixotropic and does not cause shear thinning of the ink.
  • the thickener is a polyurethane thickener.
  • Polyurethane thickeners are water- soluble polyurethane polymers which comprise the simultaneous presence of linear or branched polymers which contain hydrophilic segments (for example, polyether chains containing at least 5 alkylene oxide units, preferably ethylene oxide units), hydrophobic segments (for example, hydrocarbon segments containing at least 6 carbon atoms) and urethane groups.
  • a preferred example of a thickener material for suitable for use in the present invention is Additol VXW 6360, which is a polyether polyurethane thickener partly dissolved in deionized water and butyl diglycol, having an active content 30%, supplied by Allnex.
  • the inks each comprise fumed silica, preferably 0.2 to 2.0% by weight of fumed silica, based on the total weight of the ink. In a preferred embodiment, the inks each comprise 0.5 to 1 .5% by weight of fumed silica, based on the total weight of the ink.
  • the fumed silica is dispersed in the inkjet inks.
  • Fumed silica (also known as pyrogenic silica) exists in the form of microscopic particles of amorphous silica fused into three-dimensional secondary particles, which then agglomerate into tertiary particles.
  • the primary particle size is 5-50 nm.
  • Fumed silica is commercially available, for example from Evonik under the trade name Aerosil® and from Cabot under the trade name Cab-o-sil®.
  • the fumed silica comprises hydrophilic fumed silica and/or hydrophobic fumed silica.
  • the fumed silica is hydrophilic fumed silica.
  • the amounts by weight provided herein are based on the total weight of the ink.
  • the inkjet ink preferably exhibits a desirable low viscosity (100 mPas or less, more preferably 50 mPas or less and most preferably 35 mPas or less at 25°C).
  • the ink most preferably has a viscosity of less than 20 mPas at 25°C. Viscosity may be measured using a rotational viscometer fitted with a thermostatically controlled cup and spindle arrangement, running at 20 rpm at 25°C.
  • Other components of types known in the art may be present in the ink to improve the properties or performance. These components may be, for example, pH buffers, defoamers, dispersants, synergists, stabilisers against deterioration by heat or light, reodorants, flow or slip aids, biocides and identifying tracers.
  • the inks of the inkjet ink set may be prepared by known methods such as stirring with a high-speed water-cooled stirrer, or milling on a horizontal bead-mill.
  • the ink of the present invention may be suitable for food packaging applications but the ink is not limited to this application.
  • Other examples include low and high productivity graphic arts applications, single pass printing and packaging other than food packaging applications.
  • the present invention also provides a method of inkjet printing comprising the following steps: inkjet printing the inkjet ink set as defined herein onto a substrate and, in either order, drying and curing the ink.
  • the inkjet ink set is dried first, followed by curing the ink. Drying followed by curing ensures that good film resistance properties are achieved.
  • the inkjet ink set is inkjet printed onto a substrate.
  • the printing is performed by inkjet printing, e.g. on a single-pass inkjet printer, for example for printing (directly) onto packaging, or a multiple-pass printer where the image is built up in print swathes.
  • inkjet printing is well-known in the art and a detailed description is not required.
  • the ink is jetted from one or more printing heads through narrow nozzles on to a substrate to form a printed image.
  • Print heads account for a significant portion of the cost of an entry level printer and it is therefore desirable to keep the number of print heads (and therefore the number of inks in the ink set) low. Reducing the number of print heads can reduce print quality and productivity. It is therefore desirable to balance the number of print heads in order to minimise cost without compromising print quality and productivity.
  • the substrate is not limited but include those for packaging applications. Examples include substrates composed of polyvinyl chloride (PVC), polystyrene, polyester, polyethylene terephthalate (PET), polyethylene terephthalate glycol modified (PETG) and polyolefin (e.g. polyethylene, polypropylene or mixtures or copolymers thereof). Further substrates include all cellulosic materials such as paper and board, ortheir mixtures/blends with the aforementioned synthetic materials. In a preferred embodiment, the substrate is a compostable substrate. A substrate is compostable if it meets the criteria as set out in BS EN 13432.
  • compostable substrates examples include Sustainex (supplied by Mondi as an alternative to PE packaging material) and Nativa (a compostable bioplastic polylactic acid (BoPLA) derived from plant sugars, supplied by Taghleef).
  • Nativa can be derived from any sugar, such as corn starch, cassava, sugar cane, or sugar beet.
  • the surface which is most important since it is the surface which is wetted by the ink.
  • the surface of substrate is composed of the above-discussed material.
  • the inks are dried.
  • drying it is meant the removal of the water (and optional solvent) by evaporation. Evaporation of the water can occur simply by exposure of the inks to the atmosphere, but the inks may also be heated to accelerate evaporation.
  • the inks are cured.
  • the inks are cured by exposing the inkjet ink to a curing source.
  • curing it is meant exposure to any curing means known in the art, such as exposure to actinic radiation or low- energy electron beam, to polymerise and/or crosslink the radiation-curable material.
  • the present invention provides a method of inkjet printing comprising the following steps: inkjet printing the inkjet ink set as defined herein onto a substrate and, in either order, evaporating the water (and optional solvent) and exposing the ink to a curing means to cure the ink.
  • the inkjet ink set is dried first, followed by curing the ink.
  • the ink is cured by exposing the printed ink to a source of actinic radiation, such as UV, x-ray, electron beam etc., although UV curing is preferred.
  • a source of actinic radiation such as UV, x-ray, electron beam etc., although UV curing is preferred.
  • the source of actinic radiation can be any source of actinic radiation that is suitable for curing radiation- curable inks but is preferably a UV source. Suitable UV sources are well-known in the art and a detailed description is not required. These include mercury discharge lamps, fluorescent tubes, light emitting diodes (LEDs), flash lamps and combinations thereof. One or more mercury discharge lamps, fluorescent tubes, or flash lamps may be used as the radiation source.
  • the source of actinic radiation is a mercury discharge lamp and/or LEDs.
  • LEDs are used, these are preferably provided as an array of multiple LEDs.
  • UV light source used to cure inkjet inks is a mercury discharge lamp. These lamps operate by creating a plasma between two electrodes in a high pressure mercury gas contained in a quartz envelope. Although these lamps have some drawbacks in terms of their operational characteristics, no other UV light source has yet managed to challenge their position in terms of UV output performance. LEDs are increasingly used to cure inkjet inks. UV light is emitted from a UV LED light source. UV LED light sources comprise one or more LEDs and are well-known in the art. Thus, a detailed description is not required.
  • UV LED light sources emit radiation having a spread of wavelengths.
  • the emission of UV LED light sources is identified by the wavelength which corresponds to the peak in the wavelength distribution.
  • UV LED light sources emit UV radiation over a narrow range of wavelengths on the wavelength distribution.
  • the width of the range of wavelengths on the wavelength distribution is called a wavelength band. LEDs therefore have a narrow wavelength output when compared to other sources of UV radiation.
  • a narrow wavelength band it is meant that at least 90%, preferably at least 95%, of the radiation emitted from the UV LED light source has a wavelength within a wavelength band having a width of 50 nm or less, preferably, 30 nm or less, most preferably 15 nm or less.
  • At least 90%, preferably at least 95%, of the radiation emitted from the UV LED light source has a wavelength in a band having a width of 50 nm or less, preferably 30 nm or less, most preferably 15 nm or less.
  • the wavelength of the UV LED source substantially matches the absorption profile of the ink.
  • the wavelength distribution of the UV LED light peaks at a wavelength of from 360 nm to 410 nm.
  • the wavelength distribution of the UV LED light peaks at a wavelength of around 365 nm, 395 nm, 400 nm or 405 nm.
  • the wavelength distribution of the UV LED light peaks at a wavelength of from 360 nm to 410 nm, and at least 90%, preferably at least 95%, of the radiation has a wavelength in a band having a width of 50 nm or less, preferably 30 nm or less, most preferably 15 nm or less.
  • the wavelength distribution of the UV LED light peaks at a wavelength of around 365 nm, 395 nm, 400 nm or 405 nm, and at least 90%, preferably at least 95%, of the radiation has a wavelength in a band having a width of 50 nm or less, preferably 30 nm or less, most preferably 15 nm or less.
  • LEDs have a longer lifetime and exhibit no change in the power/wavelength output over time. LEDs also have the advantage of switching on instantaneously with no thermal stabilisation time and their use results in minimal heating of the substrate.
  • the ink is cured by exposing the printed ink to low-energy electron beam (ebeam).
  • ebeam low-energy electron beam
  • the source of low-energy electron beam can be any source of low-energy electron beam that is suitable for curing radiation-curable inks.
  • Suitable low-energy electron beam radiation sources include commercially available ebeam curing units, such as the EB Lab from ebeam Technologies with energy of 80-300 keV and capable of delivering a typical dose of 30-50 kGy at line speeds of up to 30 m/min.
  • low-energy for the ebeam, it is meant that it delivers an electron beam having a dose at the substrate of 100 kGy or less, preferably 70 kGy or less.
  • Ebeam curing is characterised by dose (energy per unit mass, measured in kilograys (kGy)) deposited in the substrate via electrons. Electron beam surface penetration depends upon the mass, density and thickness of the material being cured. Compared with UV penetration, electrons penetrate deeply through both lower and higher density materials. Unlike UV curing, photoinitiators are not required for ebeam curing to take place.
  • Ebeam curing is well-known in the art and therefore a detailed explanation of the curing method is not required.
  • the ink of the invention is exposed to the ebeam, which produces sufficient energy to instantaneously break chemical bonds and enable polymerisation or crosslinking.
  • the dose is more than 10 kGy, more preferably more than 20 kGy, more preferably more than 30 kGy and most preferably more than 40 kGy.
  • the dose is less than 100 kGy, more preferably less than 90 kGy, more preferably less than 80 kGy and most preferably less than 70 kGy.
  • the dose is more than 30 kGy but less than 70 kGy, more preferably more than 30 kGy but less than 60 kGy and most preferably, more than 30 kGy but 50 kGy or less. Doses above 50 kGy may cause damage to the substrate and so doses of 50 kGy or less are preferred.
  • the energy associated with these doses is 80-300 keV, more preferably 70-200 keV and most preferably 100 keV.
  • the ink cures to form a relatively thin polymerised film.
  • the ink set of the present invention typically produces a printed film having a thickness of 1 to 20 pm, preferably 1 to 10 pm, for example 2 to 5 pm. Film thicknesses can be measured using a confocal laser scanning microscope.
  • the present invention also provides a printed substrate obtainable by the method of inkjet printing according to the present invention.
  • the printed substrate having the inkjet ink set of the present invention printed and dried thereon has a maximum amount of copper of 50 ppm.
  • the printed substrate having the inkjet ink set of the present invention printed and dried thereon has a maximum amount of copper of 50 ppm and nickel of 25 ppm.
  • the printed substrate having the inkjet ink set of the present invention printed and dried thereon has a maximum amount of copper of 50 ppm, nickel of 25 ppm, zinc of 150 ppm, cadmium of 0.5 ppm, lead of 50 ppm, mercury of 0.5 ppm, chromium of 50 ppm, molybdenum of 1 ppm, selenium of 0.75 ppm and arsenic of 5 ppm.
  • the present invention also provides a printed substrate having the inkjet ink set as defined herein printed thereon.
  • the substrate is preferably as discussed hereinabove.
  • the substrate is a compostable substrate.
  • a substrate is compostable if it meets the criteria as set out in BS EN 13432.
  • the inkjet ink set is particularly suitable for composting. Accordingly, the present invention further provides a method of composting a printed substrate having the inkjet ink set as defined herein printed thereon comprising composting the printed substrate.
  • the criteria for composting is set out in BS EN 13432.
  • Example 1 preparation of a aqueous PUD test sample
  • the PUD under test is blended with an aqueous pigment dispersion to facilitate observation of film redispersion and removal.
  • a surfactant is added to reduce surface tension and to allow wetting onto a suitable test substrate.
  • the PUD test composition therefore comprises the components as set out in Table 1 .
  • Table 1 The components of Table 1 are accurately weighed into a mixing vessel and stirred with a flat bladed impeller stirrer at 800 rpm for 20 minutes to ensure the composition is fully homogeneous. After mixing, the composition is allowed to stand for 24 hours to deaerate.
  • the PUD test composition is then coated onto a 220 micron gloss PVC (Genotherm, as supplied by Kldckner Pentaplast) using a number 2 K bar. A wet film is deposited of approximately 12 microns. The ink film is then dried by placing in an oven set at 60°C for three minutes.
  • the redispersibility of the thermally dried ink film is assessed.
  • the corner of a sheet of E Tork paper towel (supplied by Tork UK) is wetted with 1 ml of deionised water and placed over the tip of the index finger.
  • the wetted corner of the paper towel is brought into contact with the thermally dried PUD film at the left hand side of the printed film and drawn across the printed film in single stroke with a light pressure. The stroke is continued until the wetted paper towel has completely traversed the printed film
  • the ink film is cleanly removed from the substrate surface leaving no residual staining visible to the naked eye. Further, there is no particulate matter, visible to the naked eye, transferred to the wiping paper or to the substrate at the end of the wiping area.
  • An ink was prepared according to the formulation set out in Table 2.
  • the inkjet ink formulation was prepared by mixing the components in the given amounts. Amounts are given as weight percentages based on the total weight of the ink.
  • Projet APD 1000 blue is an aqueous pigment dispersion and contains 15.9% PB60 pigment, based on the total weight of the pigment dispersion.
  • the ink therefore contains 2.53% PB60 pigment based on the total weight of the ink.
  • the pigment dispersion was prepared by mixing the components in the given amounts and passing the mixture through a bead mill until the dispersion had a particle size of less than 0.3 microns.
  • Ucecoat 2802 is an aqueous PUD dispersion, which is redispersible in water after thermal drying and before curing in a single rub of the water rub test, and contains 40% solid polymer content, based on the total weight of the resin dispersion.
  • PB60 pigment has a heavy metal content as set out in Table 3, as determined by ICP. Specifically, the total heavy metal content was determined by the following method:
  • the powder pigments are digested in a mixture of hydrochloric and nitric acids to ensure that the total metal content, rather than the free metal levels in the samples are correctly determined. This is achieved by gently heating a mixture of the pigment with a 33%v/v solution of HCI and HNO3 (ratio of acids 1 :3) on a hotplate until the pigment is dissolved.
  • a calibration standard is used for each metal. Suitable certified ICP-OES metal standards can be obtained from Sigma. It is necessary to take into account the various interference bands of each metal and ensure the concentration range brackets the concentrations relevant to the application.
  • a known amount of the prepared pigment sample is combined with a known amount of deionised water to create a solution that will position the concentration of metals present roughly into the centre of the calibration range.
  • the analysis can then be conducted on a suitable ICP unit, for examples a Thermo ICS-5000 ICP-OES. Both the dual radial and axial detectors are used. First, the calibration is run, followed by a period of blank deionised water to flush the system, the samples are then run in duplicate. Using the calibration, it is then possible to calculate the concentration of metals present.
  • the copper content of a compostable substrate (1 m 2 and 500 pm thick) having the ink of Table 2 printed thereon to produce a 5 pm dried film weight was calculated, where the substrate and dried ink film density was 1.1 g/cm 3 .
  • the copper content (ppm) of the print was then calculated.
  • the weight of the pigment in the film 0.56 g was divided by the total weight of the printed substrate of 555.5 g, and then multiplied by 1 .08 ppm copper content in the pigment to provide a copper content in the printed substrate of 0.00109 ppm copper in printed substrate.
  • a comparative ink was prepared according to the formulation set out in Table 4.
  • the inkjet ink formulation was prepared by mixing the components in the given amounts. Amounts are given as weight percentages based on the total weight of the ink.
  • Projet APD 1000 cyan is an aqueous pigment dispersion and contains 14% PB15.3 pigment, based on the total weight of the pigment dispersion.
  • the ink therefore contains 2.23% PB15.3 pigment based on the total weight of the ink.
  • the pigment dispersion was prepared by mixing the components in the given amounts and passing the mixture through a bead mill until the dispersion had a particle size of less than 0.3 microns.
  • Pigment PB 15.3 contains 11 % Cu atoms, and as such contains 110,000 ppm Cu.
  • the weight of the pigment in the film 0.56 g was divided by the total weight of the printed substrate of 555.5 g, and then multiplied by 110,000 ppm copper content in the pigment to provide a copper content in the printed substrate of 110.9 ppm copper in printed substrate.
  • the ink of the invention provides a 5 pm film which falls within the limits set out in BS EN 13432 for the copper content of 50 ppm, as it has a copper content in the printed film of 0.00109 ppm.
  • This is in marked contrast to the comparative ink which provides a 5 pm film which falls outside the limits set out in BS EN 13432 for the copper content of 50 ppm, as it has a copper content in the printed film of 110.9 ppm.

Abstract

La présente invention concerne un jeu d'encres aqueuses pour jet d'encre comprenant quatre encres aqueuses pour jet d'encre ou plus, chaque encre aqueuse pour jet d'encre comprenant un pigment, de l'eau et une dispersion aqueuse de poly((méth)acrylate d'uréthane) qui peut se redisperser dans l'eau après séchage thermique et avant durcissement, le jeu d'encres pour jet d'encre comprenant une encre bleue et/ou cyan, une encre jaune, une encre magenta et une encre noire, et la quantité totale de cuivre présente dans la totalité des encres du jeu d'encres étant de 10 000 ppm ou moins.
PCT/GB2022/052783 2021-11-05 2022-11-04 Jeu d'encres pour jet d'encre WO2023079296A1 (fr)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
EP2159271A1 (fr) * 2008-08-25 2010-03-03 Seiko Epson Corporation Ensemble d'encres
WO2011010164A2 (fr) * 2009-07-24 2011-01-27 Natural Adcampaign Limited Supports d'affichage et publicitaire imprimables
WO2015158745A1 (fr) 2014-04-15 2015-10-22 Agfa Graphics Nv Encres pour imprimantes à jet d'encre à base de résine aqueuse
WO2015189639A2 (fr) * 2014-06-12 2015-12-17 Fujifilm Speciality Ink Systems Limited Encre d'impression
WO2017103603A1 (fr) * 2015-12-16 2017-06-22 Fujifilm Speciality Ink Systems Limited Encre d'impression

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2159271A1 (fr) * 2008-08-25 2010-03-03 Seiko Epson Corporation Ensemble d'encres
WO2011010164A2 (fr) * 2009-07-24 2011-01-27 Natural Adcampaign Limited Supports d'affichage et publicitaire imprimables
WO2015158745A1 (fr) 2014-04-15 2015-10-22 Agfa Graphics Nv Encres pour imprimantes à jet d'encre à base de résine aqueuse
WO2015189639A2 (fr) * 2014-06-12 2015-12-17 Fujifilm Speciality Ink Systems Limited Encre d'impression
WO2017103603A1 (fr) * 2015-12-16 2017-06-22 Fujifilm Speciality Ink Systems Limited Encre d'impression

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Title
C.Y. BAI ET AL.: "A new UV curable waterborne polyurethane: Effect of C=C content on the film properties", PROGRESS IN ORGANIC COATINGS, vol. 55, 2006, pages 291 - 295, XP025044369, DOI: 10.1016/j.porgcoat.2005.12.002

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