(19)
(11)EP 3 134 471 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
18.03.2020 Bulletin 2020/12

(21)Application number: 15783305.4

(22)Date of filing:  21.04.2015
(51)Int. Cl.: 
C08K 5/11  (2006.01)
(86)International application number:
PCT/US2015/026807
(87)International publication number:
WO 2015/164331 (29.10.2015 Gazette  2015/43)

(54)

A PROCESS FOR PREPARING POLYESTER RESINS FROM POLYETHYLENE TEREPHTHALATE AND ENERGY CURABLE COATING COMPOSITIONS

VERFAHREN ZUR HERSTELLUNG VON POLYESTERHARZEN AUS POLYETHYLENTEREPHTHALAT UND ENERGIEHÄRTBARE BESCHICHTUNGSZUSAMMENSETZUNGEN

PROCÉDÉ PERMETTANT LA PRÉPARATION DE RÉSINES DE POLYESTER À PARTIR DE POLY(TÉRÉPHTALATE D'ÉTHYLÈNE) ET DE COMPOSITIONS DE REVÊTEMENT DURCISSABLES PAR APPLICATION D'ÉNERGIE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 23.04.2014 US 201461983201 P
23.04.2014 US 201461983015 P

(43)Date of publication of application:
01.03.2017 Bulletin 2017/09

(73)Proprietor: Sun Chemical Corporation
Parsippany, NJ 07054 (US)

(72)Inventors:
  • GAUDI, Kai-Uwe W.
    63755 Alzenau (DE)
  • DIEKER, Jürgen
    64291 Hesse (DE)
  • JUREK, Michael J.
    Oak Ridge, NJ 07438 (US)
  • KELLER, Lars
    63110 Hesse (DE)

(74)Representative: Carpmaels & Ransford LLP 
One Southampton Row
London WC1B 5HA
London WC1B 5HA (GB)


(56)References cited: : 
EP-A1- 0 558 906
US-A- 6 127 436
US-A1- 2012 245 246
EP-B1- 1 044 232
US-A1- 2009 121 363
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] The present invention is directed to polyester resins which are prepared by depolymerizing virgin, scrap, recycled or reclaimed polyethylene terephthalate (PET) via an alcoholysis reaction with one or more polyhydric alcohols to form a depolymerization product and esterifying the depolymerization product with one or more polybasic carboxylic acids and/or anhydrides and optionally polyhydric alcohol to form a polyester polyol. The polyester may then be acrylated with acrylic acid to form a polyester acrylate resin.

    [0002] The polyester resins are then used in energy curable coating compositions or inks and in particular, the polyester acrylate resin is suitably used as a reactive binder/oligomer.

    BACKGROUND OF THE INVENTION



    [0003] Recycling of waste PET, either post-consumer or non-post-consumer, is a worldwide concern due to its environmental impact and the increasing volume of these materials being produced by society.

    [0004] Furthermore, energy curable coating compositions and inks, in particular, ultraviolet (UV) curable coating compositions and inks have become increasingly popular because they do not employ volatile organic solvents and thus avoid the associated health and environmental concerns. Furthermore they are applicable in a wide range of printing techniques and cure rapidly upon irradiation.

    [0005] Curing of energy curable coating compositions and inks predominantly proceeds via a radical polymerization mechanism. Thus, the binder/resin material of the coating compositions and inks advantageously must comprise functional groups which are capable of undergoing radical polymerization. Typically, these functional groups are unsaturated groups such as acrylate groups.

    [0006] US 6,127,436 is directed to a method of depolymerizing reclaimed, recycled or virgin PET via an alcoholysis reaction using glycols and polyhydric alcohols. The depolymerizied product is then esterified with polybasic carboxylic acids, anhydrides or acyl halides to produce a composition containing inert oligomeric binders which are useful in curable coatings. EP0558906 A1 relates to a non-aqueous coating composition prepared from PET. EP1044232 A1 relates to an organic binder produced by depolymerizing virgin, scrap, recycled or reclaimed PET.

    [0007] David E. Nikles, Medhat S. Farahat - Macromol. Mater. Eng. 2005, 290, 13-30 - New Motivation for the Depolymerization Products Derived from Poly(Ethylene Terephthalate) (PET) Waste: a Review; discloses that PET waste can be converted to acrylate-terminated PET low molecular weight oligomers by a two-stage process, first glycolysis with diethylene glycol followed by reaction with acryloyl chloride which can be cured by UV radiation.

    [0008] Consequently it is an object of the present invention to provide a polyester acrylate resin which is derived from substantial amounts of reclaimed, recycled or virgin PE, that is advantageously highly energy curable and has a sufficiently high molecular weight such that it can be suitably incorporated into coating compositions or inks.

    SUMMARY OF THE INVENTION



    [0009] The present invention is defined by the claims.

    [0010] The present invention provides a process for preparing a polyester acrylate resin having a number average molecular weight (Mn) of at least 800 Da comprising
    1. a) reacting polyethylene terephthalate (PET) with one or more polyhydric alcohols to provide a depolymerization product;
    2. b) reacting the depolymerization product with a polybasic carboxylic acid and/or anhydride and optionally a polyhydric alcohol to form a polyester polyol and
    3. c) reacting the polyester alcohol with acrylic acid to provide a polyester acrylate resin;
    wherein the number average molecular weight is measured according to the method described in paragraphs [00091] to [00092] of the description.

    [0011] In a particular embodiment steps (a) and (b) of the process of the can be combined into a single step and thus the present invention further provides a process for preparing a polyester acrylate resin having a number average molecular weight (Mn) of at least 800 Da comprising
    1. a) reacting polyethylene terephthalate (PET) with one or more polyhydric alcohols and a polybasic carboxylic acid and/or anhydride to form a polyester polyol and
    2. b) reacting the polyester polyol with acrylic acid to provide a polyester acrylate resin.


    [0012] Furthermore the present invention provides a polyester acrylate resin prepared by the above mentioned process.

    [0013] Additionally, the present invention provides an energy curable coating composition or ink comprising the polyester acrylate resin of the invention.

    [0014] Finally the present invention also provides an energy curable coating composition or ink comprising between 2 to 40 wt% of an inert polyester resin,
    wherein the inert polyester resin comprises a polyethylene terephthalate oligomer having about 40 to 70 wt% recurring ethylene terephthalate units, recurring units of C3+ alpha alkylene terephthalate, hydroxy alkylene terephthalate and pendant units of polybasic aliphatic, alicyclic or aromatic monocarboxylate and
    wherein the inert polyester resin is prepared by reaction steps (a) and (b);
    and further comprising a polyester acrylate resin according to the invention.

    [0015] These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the methods and formulations as more fully described below.

    DETAILED DESCRIPTION OF THE INVENTION



    [0016] It has been found that an energy curable polyester acrylate resin having a number average molecular weight (Mn) of at least 800 Da prepared by depolymerizing, esterifying and acrylating PET can be suitably incorporated into energy curable coating compositions and inks.

    [0017] These energy curable coating compositions and inks exhibit improved cure and thus are particularly useful for printing applications where high speed printing is desired such as lithographic inks.

    [0018] Furthermore it has been found that between 2 to 40 wt% of an inert polyester resin comprising a polyethylene terephthalate oligomer having about 40 to 70 wt% recurring ethylene terephthalate units, recurring units of C3+ alpha alkylene terephthalate, hydroxy alkylene terephthalate and pendant units of polybasic aliphatic, alicyclic or aromatic monocarboxylate prepared by depolymerizing and esterifying PET can also be suitably incorporated into energy curable coating compositions and inks.

    [0019] These energy curable coating compositions or inks exhibit improved deinking properties and improved solvent resistance.

    [0020] The PET may be derived from polymerizing terephthalic acid and ethylene glycol (virgin PET), but is preferably derived from waste material generated in the PET production process and waste materials generated in the production of PET molded articles (pre-consumer scrap). Advantageously, the PET is derived from PET molded articles (post-consumer scrap).

    [0021] Typically the waste PET comprises regrinds which are obtained by physically and mechanically grinding PET bottles into chips, powder, pellets or flakes.

    [0022] The process according to the present invention is advantageous in that even low quality and/or low molecular weight PET can be used given that the initial step requires depolymerization.

    [0023] Furthermore in addition to polymers consisting only of terephthalic acid and ethylene glycol the PET as described herein may also comprise a modifying co-monomer such as cyclohexanedimethanol, isophthalic acid, and/or naphthalenedicarboxylic acid.

    [0024] Additionally, the PET may be transparent or non-transparent, clear or colored or have printing thereon.

    [0025] The polyhydric alcohols used in step (a) have at least two hydroxyl groups and are typically selected from 1,2-ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, polyethylene glycol, polypropylene glycol, 2-methyl-1,3-propanediol, 1,2-butandiol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol (2,2-dimethyl-1,3-propandiol), 2-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-petanediol, 3-methyl-1,5-petanediol, ethoxylated neopentylglycol, propoxylated neopentylglycol, 1,4-cyclohexanedimethanol, bisphenol-A, ethoxylated bisphenol-A, hydrogenated bisphenol A, an alkylene oxide adduct of hydrogenated bisphenol A, and trifunctional or higher functional polyhydric alcohols, such as glycerol, trimethylolpropane, ethoxylated trimethylolpropane, propoxylated trimethylolpropane, propoxylated glycerol, pentaerythritol, ethoxylated pentaerythritol, propoxylated pentaerythritol, ditrimethylolpropane, di-pentaerythritol, ethoxylated dipentaerythritol and sorbitol.

    [0026] Advantageously, the polyhydric alcohols are neopentyl glycol and/or trimethylolpropane.

    [0027] Preferably, the weight % ratio of PET to the polyhydric alcohol in the depolymerization step is between 20:1 to 1:10, and most preferably between 10:1 to 1:1.

    [0028] Advantageously, a catalyst is used in step (a) to promote the depolymerization reaction.

    [0029] Suitable catalysts include organic acid salts, alkoxides or chelates of metals and preferably the catalyst is a titanium or a tin compound, particularly a titanium alkoxide e.g. tetraisopropyltitanate or titanium(IV) butoxide.

    [0030] Typically the amount of the catalyst used is between 0.01 to 2.50wt% based on the total weight of reaction mixture.

    [0031] The depolymerization reaction is preferably carried out at a temperature of between 160 to 260°C, preferably between 190°C to 230°C and most preferably between 215 to 225°C.

    [0032] Typically, the depolymerization reaction occurs over a period of between 1 to 12 hours, preferably between 2 to 4 hours e.g. 3 hours. Advantageously, the deploymerization reaction is carried out until the solid PET and polyhydric alcohol mixture is converted to a clear or homogeneous mixture or a melt solution that contains no visible PET particles.

    [0033] The depolymerization reaction can be carried out at atmospheric, subatmospheric or supra-atmospheric pressures, but is preferably is carried out at atmospheric pressure.

    [0034] The depolymerization product (PET polyol) can range from a polymeric glass to a viscous liquid.

    [0035] Furthermore the color of the depolymerisation product depends on the quality of the PET material used.

    [0036] Typically, if low quality PET is used, for example post-consumer PET bottles with a large amount of insoluble impurities such as paper labels on the bottles or rub-off parts collected in the process of mechanical cutting of the bottles, the depolymerization product is filtered after step (a).

    [0037] The depolymerisation product is then esterified in step (b) with a polybasic carboxylic acid and/or anhydride and optionally a polyhydric alcohol.

    [0038] Typically, the polybasic carboxylic acids and/or anhydrides include unsaturated polybasic acids, such as maleic acid, maleic anhydride, fumaric acid, and itaconic acid; aliphatic saturated polybasic acids, such as malonic acid, succinic acid, adipic acid, azelaic acid, and sebacic acid; aromatic saturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, 2,6-naphthalenedicarboxylic acid; alicyclic polybasic acids, such as tetrahydrophthalic anhydride, hexahydro-4-methylphthalic anhydride (MHHPA), 1,2-hexahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, and nadic acid. A preferred acid derivative is a di-carboxy aromatic carboxylic acid anhydride.

    [0039] Preferably, the polybasic carboxylic acids and/or anhydrides are selected from phthalic acid anhydride (PAA) or methylhexahydrophthalic acid anhydride (MHHPA) and advantageously mixtures of PAA and MHHPA are used.

    [0040] The polybasic carboxylic acids and/or anhydrides are preferably added in an amount of less than 60wt% based upon the weight of the depolymerization product and advantageously added in an amount of between 5 to 60wt%.

    [0041] In a preferred embodiment of the present invention, polyhydric alcohols are also added to the reaction mixture in step (b) in order to form a polyester-polyol.

    [0042] The polyhydric alcohol(s) used in step (b) may be the same as those polyhydric alcohols used step (a).

    [0043] Preferably, the polyhydric alcohols used in step (b) are tri functional or higher functional polyhydric alcohols such as trimethylol propane, alkoxylated trimethylolpropane, ditrimeylolpropane or pentaerythritol.

    [0044] Advantageously, the polyhydric alcohol used in step (b) is neopentyl glycol.

    [0045] Typically, the polyhydric alcohol(s) used in step (b) are added in an amount of 20wt% or less based on the weight of the depolymerization product and advantageously added in an amount of between 3 to 20wt%.

    [0046] Furthermore, a monofunctional acid, such as benzoic acid, may also be added to the reaction mixture during step (b).

    [0047] The esterification reaction of step (b) is preferably carried out at a temperature of between 180°C to 220°C and preferably carried out in an inert atmosphere, such as nitrogen or argon.

    [0048] Typically the esterification reaction is carried out at pressure of between 5,000 to 150,000 Pa, preferably between 10,000 to 120,000 Pa and most preferably at atmospheric pressure.

    [0049] Typically, the esterification reaction is carried out until the acid value of the reaction mixture is reduced to between 2 to 50 mg KOH/g and preferably to between 2 to 30 mg KOH/g.

    [0050] The polyester polyol produced in step (b) may be in the form of a clear viscous liquid or hard solid resin.

    [0051] Typically, the polyester polyol has a number average molecular weight (Mn) of between 850 to 5,000 Da and a weight average molecular weight (Mw) of between 1,500 to 25,000 Da.

    [0052] Additionally, the hydroxyl value of the polyester polyol is preferably at least 100, more preferably between 150 to 600 and most preferably between 250 to 500.

    [0053] In a preferred embodiment the polyester polyol has a substantial proportion of primary alcohol groups to facilitate the acrylation reaction of step (c).

    [0054] The polyester-polyol is then acrylated in step (c) with acrylic acid.

    [0055] The acrylation of step (c) is preferably done in the presence of an acidic catalyst, such as methane sulfonic acid and advantageously carried out in the presence of a polymerization inhibitor.

    [0056] Suitable inhibitors include phenols, such as 4-methoxyphenol or a copper or an aluminum based inhibitor.

    [0057] The acrylation of step (c) is carried out at a temperature of between 80 to 130°C, preferably between 90 to 110°C.

    [0058] The polyester acrylate resin produced may be a solid or a viscous liquid and is typically pale yellow to green to light brownish in color.

    [0059] The polyester acrylate resin usually has a number average molecular weight (Mn) of between 800 to 20,000 Da, a weight average molecular weight (Mw) of between 2000 to 25,000 Da and an acrylic acid ester group content of between 1 to 6 mmol/g.

    [0060] Preferably the polyester acrylate resin has an acid value of between 2 to 50mg KOH/g.

    [0061] The present invention also provides an energy curable coating composition or ink comprising an inert polyester resin and/or a polyester acrylate resin.

    [0062] When the coating compositions or inks contain a polyester acrylate resin this is typically present in an amount of between 1 to 80wt%, preferably between 5 to 70wt%, more preferably between 10 to 60wt% and advantageously between 15 to 50wt%.

    [0063] When the compositions contain an inert polyester resin this is present in an amount of between 2 to 40wt%, preferably between 5 to 30wt%, and advantageously between 15 to 25wt%.

    [0064] The energy curable coating compositions or inks may additionally contain other acrylated oligomers, typically with an acrylate functionality ≥ 2, such epoxy acrylates, polyester acrylates, acrylated polyurethanes, acrylated polyacrylates, acrylated polyethers, acrylated oils based on linseed oil, soybean or castor oil and mixtures thereof.

    [0065] The weight average molecular weight (Mw) of the other acrylated oligomers is usually between 400 to 3000 Da.

    [0066] The other acrylated oligomers are incorporated in the coating compositions or inks to impart rheology, pigment wetting, transfer, gloss, chemical resistance and other film properties.

    [0067] Furthermore the energy curable coating compositions or inks may additionally contain acrylic monomers and are typically esters of acrylic acid having a functionality ≥ 2.

    [0068] The weight average molecular weight (Mw) of the acrylic monomers is usually between 200 to 800 Da.

    [0069] Typically the energy coating compositions and inks contain between 15 to 45wt% of acrylic monomers, preferably between 20 to 40wt% and most preferably between 25 to 35wt%.

    [0070] These acrylic monomers are incorporated into the coating compositions or inks to impart curing speed, solvent resistance, hardness and allow viscosity adjustment.

    [0071] The acrylated oligomers and acrylic monomers may be selected from 1,2-ethylene glycol diacrylate, 1,4-butandiol diacrylate, 1,6-hexandiol diacrylate, dipropylene glycol diacrylate, neopentylglycol diacrylate, ethoxylated neopentylglycol diacrylates, propoxylated neopentylglycol diacrylates, tripropylene glycol diacrylate, bisphenol-A diacrylate, ethoxylated bisphenol-A-diacrylates, bisphenol-A-diglycidylether diacrylate, ethoxylated bisphenol-A-diacrylates, poly(ethylene)glycol diacrylates, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylates, propoxylated trimethylolpropane triacrylates, propoxylated glycerol triacrylates, pentaerythritol triacrylate, ethoxylated pentaerythritol triacrylates, propoxylated pentaerythritol tetraacrylates, ethoxylated pentaerythritol tetraacrylates, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate ethoxylated dipentaerythritol hexaacrylates or mixtures thereof, and are preferably ethoxylated trimethylolpropane triacrylates, ethoxylated pentaerythritol triacrylates and propoxylated pentaerythritol tetraacrylates.

    [0072] In particular, when the coating composition or ink is formulated for food packaging, multifunctional acrylates such ethoxylated pentaerythritol tetraacrylates, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated dipentaerythritol hexaacrylates or mixtures thereof are preferred.

    [0073] The energy curable coating compositions or inks may also contain one or more colorants in the form of a dye or pigment dispersed therein. Suitable pigments include conventional organic or inorganic pigments. Representative pigments may, for example, be selected from the group of Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 63, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 106, Pigment Yellow 111, Pigment Yellow 114, Pigment Yellow 121, Pigment Yellow 126, Pigment Yellow 127, Pigment Yellow 136, Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Yellow 194, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Orange 36, Pigment Orange 61, Pigment Orange 62, Pigment Orange 64, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 48: 2, Pigment Red 53: 1, Pigment Red 57: 1, Pigment Red 81: 1, Pigment Red 112, Pigment Red 122, Pigment Red 170, Pigment Red 184, Pigment Red 210, Pigment Red 238, Pigment Red 266, Pigment Blue 15, Pigment Blue 15: 1, Pigment Blue 15: 2, Pigment Blue 15: 3, Pigment Blue 15: 4, Pigment Blue 61, Pigment Green 7, Pigment Green 36, Pigment Violet 1, Pigment Violet 19, Pigment Violet 23, and Pigment Black 7.

    [0074] The energy curable coating compositions or inks are advantageously UV curable and typically contain photoinitiators, such as for example benzophenones, benzilketales, dialkoxy acetophenones, hydroxyalkyl-acetophenones, aminoalkylphenones, acylphosphinoxides and thioxanthones, for example benzophenone, methylbenzophenone, 4-phenylbenzophenone, 4,4'-bis(dimethylamino)-benzophenone, 4,4'-bis(diethylamino)-benzophenone, 2,2-dimethoxy-2-phenylacetophenone, dimethoxyacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-methyl-1-[4(methoxythio)-phenyl]-2-morpholinopropan-2-one, diphenylacylphenyl phosphinoxide, diphenyl(2,4,6-trimethylbenzoyl) phosphinoxide, 2,4,6-trimethylbenzoylethoxyphenyl phosphinoxide, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dimethylthioxanthone or mixtures thereof.

    [0075] Furthermore the energy curable coating compositions or inks may further contain the usual additives to modify flow, surface tension, gloss, pigment wetting and abrasion resistance of the cured coating or printed ink. Such additives include surface active agents, waxes, shelf-life stabilizers, and combinations thereof.

    [0076] These additives may function as leveling agents, shelf-life stabilizers, wetting agents, slip agents, flow agents, dispersants and de-aerators. Preferred additives include fluorocarbon surfactants, silicones and organic polymer surfactants. Examples include the Tegorad product lines (Tegorad are trademarks and are commercially available products of Tego Chemie, Essen, Germany) and Solsperse product lines (Solsperse are trademarks and are commercially available products of Lubrizol Company).

    [0077] Furthermore the energy curable coating compositions or inks may further contain the usual extenders such as clay, talc, calcium carbonate, magnesium carbonate or silica to adjust water uptake, misting and color strength.

    [0078] Typically, the energy curable coating compositions or inks have a viscosity of between 5 to 100 Pas, preferably between 20 to 50 Pas at a shear rate of D = 50 1/s, flow values of between 3 to 15 cm, and a tack of between 200-450 units, preferably between 250-350 units.

    [0079] The present invention also provides articles coated with the coating compositions or inks. The coating compositions or inks are typically applied to the articles using inkjet, flexo, gravure, screen, and litho printing and are subsequently cured.

    [0080] The articles may be composed of any typical substrate such as paper, plastics, metals and composites. The substrate may be paper print stock typically used for publications or may be a packaging material in the form of a cardboard sheet or corrugated board.

    [0081] Furthermore, the substrate may be a polyolefin, such as a polyethylene or a polypropylene, a polyester such as polyethylene terephthalate, or a metalized foil such as an laminated aluminum foil or a metalized polyester.

    [0082] The coating compositions or inks may be cured using an electron beam (EB) but are preferably cured using ultraviolet light (UV).

    [0083] The compositions may be cured by an actinic light source, such as for example UV-light, provided by a high-voltage mercury bulb, a medium-voltage mercury bulb, a xenon bulb, a carbon arc lamp, a metal halide bulb, a UV-LED lamp, a uv laser, such as a semiconductor laser or an eximer laser or sunlight.

    [0084] The wavelength of the applied radiation is preferably within a range of between 200 to 500 nm, more preferably between 250 to 350 nm.

    [0085] Advantageously, the energy curable coating compositions or inks are energy curable lithographic inks.

    [0086] The present invention has been described in detail, including the preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention that fall within the scope of the invention.

    [0087] The invention is further described by the examples given below.

    EXAMPLES



    [0088] The following examples illustrate specific aspects of the present invention and are not intended to limit the scope thereof in any respect and should not be so construed.

    Testing Methods and Definitions:


    Method of Determining the Acid Value:



    [0089] 0.2-1.0g of sample was placed into a 50ml Erlenmeyer and dissolved in 10-20ml of acetone (10-20 ml). 3 drops of 1% alcoholic phenolphthalein solution was added and this was titrated with standardized 0.1 N alcoholic potassium hydroxide (KOH) to obtain a pink color lasting for 15 seconds and the number of mls of KOH solution used was recorded.

    [0090] The acid value was calculated as follows;


    Method of Determining the Molecular Weight:



    [0091] The number average molecular weight (Mn) and weight average molecular weight (Mw) were determined by size exclusion chromatography (GPC) with monodisperse polystyrene equivalent molecular weight calibration standard and GPC columns (manufactured by Tosoh Corp., G1000HXL, G500HXLx1, G100HXLx1).

    [0092] A flow rate of 1.0 ml/min, an tetrahydrofurane eluent, a column temperature of 40°C, a differential refractive index detector (RI) and a UV-detector (254nm) was used.

    [0093] The dispersability was calculated from the measurement results. The formula for Polydispersity (D) is Mw/Mn.

    Method of Determining the Color:



    [0094] The color of the resins was measured using the Lovibond 2000 Comparator with Daylight color measuring system. The samples (50 wt% solution in ethyl acetate) were visually matched against calibrated, color stable glass standards in test discs. The scale discs color standards used were the Gardner 4/30AS (with the colors 1 to 9) and the Gardner 4/30BS (with the colors 10 to 18).

    Method of Determining Viscosity:



    [0095] The viscosity was determined with a Physika 300 cone and plate rheometer from Anton Parr GmbH at a shear rate of D = 2-100 1/s. The viscosity value at D = 50 1/s was recorded.

    Method of Determining Tack:



    [0096] Tack was measured with a calibrated "Tack-o-scope" instrument (Model 2001) from IGT testing systems, Netherlands. 1 ml of sample was placed on the EPDM rubber distribution roller 30°C, distributed for 90 seconds at a roller speed of 50 rpm, then 30 seconds at 300 rpm. Then the tack value is taken at a roller speed of 150 rpm.

    Method of Determining Flow:



    [0097] The flow was measured with a vertically arranged aluminum plate on which 1ccm of sample was placed. The distance that the sample travelled down the plate over a period of 15 minutes was recorded.

    Method of Determining UV-cure:



    [0098] The extent of UV-cure is assessed by a thumb twist test and a solvent resistance test with isopropanol (IPA). Such a test is well known in the art and is, for example, described on page 74 of Test Methods for UV and EB Curable Systems, C. Lowe & P.K.T Oldring, SITA Technology, 1994, ISBN 0 947798 07 2.

    [0099] Good cure can be defined as the degree of cure in which no ink is transferred to the thumb and the ink has a solvent resistance of at least 10 IPA double-rubs. The press operator notes the lamp settings at which good cure is observed:
    • 1 lamp low (best cure)
    • 1 lamp high (good cure)
    • 1 lamp high, 1 lamp low (fair-good cure)
    • 2 lamps high (fair)

    Method of Determining Misting:



    [0100] Misting is assessed at different places on the press, usually near an ink duct and a printing plate. A white piece of paper is placed in a defined distance from the ink rollers and the press is run for a defined period of time at a defined speed and temperature. Then, the ink mist which is transferred to the paper is assessed by visual comparison to a master example or by measurement with a densitometer. Very little ink on the paper means that the ink has very low misting and low tendency to contaminate the printing press and press room with ink mist. Visual assessment of misting can be described as follows:
    • Very good (ink mist is undetectable or minimal)
    • Good (small amount of ink mist is deposited on the paper)
    • Bad (large amount of ink mist is deposited on the paper).

    Method of Determining Lithographic Performance:



    [0101] This was done with a high speed lithotronic emulsification tester (Novocontrol GmbH, Germany).The lithotronic tester can perform emulsification tests at high speed and shear stress.

    Method of Determining Press Performance:



    [0102] To test the press performance of inks they were printed with a "Didde" web offset UV-press (Graphic system services, U.S.A.) equipped with two UV-dryers having high pressure mercury bulbs.

    Method of Determining Set-off:



    [0103] Set-off is defined as the tendency of ink to transfer from a freshly printed surface to another paper when pressed without any friction. Set-off is an unwanted behavior of paper and ink. It is influenced by the characteristics of the paper and ink: a porous paper surface absorbs the ink fast results in lesser set-off, as do inks that dry (or set) quickly. The higher the speed of the press, the higher the set-off will be.

    [0104] Set-off is measured at two different time intervals, 0.35s and 3s. A freshly printed surface is pressed against a paper after 0.35s and after 3s. Then the set-off density is measured. The two time periods allows the set-off to be determined when the materials are used in a high-speed press and a low-speed press. Samples were measured on a prüfbau Deltack at a single time using curing energy to determine the reduction in the set-off time.

    [0105] UV cured prints of inks, which were printed with a comparable density of 1.55 to 1.60, were covered with a white counter paper. Then, with a pressure of 10 tons, both the printed substrate and the plan counter paper were pressed together. Then, the counter paper was removed from the print and the amount of transferred ink on the counter paper was measured by a densitometer. The lower the amount of transferred ink provides lower readings on the densitometer which represent better cure.

    Method of Determining Deinking:



    [0106] The 'International Association of the Deinking industry (INGEDE) has developed a set of methods to simulate the common operating condition of the relevant process steps in an industrial deinking plant under standard conditions in a laboratory scale. This estimates the relative challenge a printed product means to a deinking plant. The INGEDE method has been developed for the assessment of the de-inkability of individual printed products, (see: Ingede Method 11, July 2012: Assessment of Print Product Recyclability: Deinkability Test; INGEDE e. V. Bietigheim-Bissingen, Germany).

    [0107] The INGEDE method describes a procedure to evaluate the deinkability of printed paper products by means of alkaline flotation deinking. Flotation is the most widely used technology for ink removal in the paper recycling process. It can be used for any kind of printed paper product. The method in a laboratory scale defines the essential steps of the flotation deinking process, namely pulping and flotation.

    [0108] Method 11 was used and the deinkability is assessed by an optical evaluation. The deinked pulp is filtered, and by doing so, a sample is obtained. The sample is dried and the color strength is measured using a SpectroEye from Gretag AG. As a rule, if a lower color strength is measured, the pulp released a higher amount of ink which means that a better de-inkability is observed.

    [0109] The color strength is defined as a pigments or dyes ability to change the color of an otherwise colorless material. Strength indices are used to compare a reference standard and a sample and define the ratio of the sample strength in relation to the reference standard. Strength indices illustrate how strong or weak a sample is in comparison to the reference standard.

    Interpretation:



    [0110] 
    • Percent color strength >100 = deinked cellulose is stronger in color than the reference standard
    • Percent color strength <100 = deinked cellulose is weaker in color than the reference standard
    • Percent color strength =100 = deinked cellulose and the reference standard have the same color strength

    IPA rubs test:



    [0111] The extent of UV-cure is assessed by a solvent resistance test with isopropanol (IPA). Such a test is well known in the art and is, for example, described on page 74 of Test Methods for UV and EB Curable Systems, C. Lowe & P.K.T Oldring, SITA Technology, 1994, ISBN 0 947798 07 2.

    Ink duct setting:



    [0112] This equates to the size of the opening through which the ink enters the ink train.

    Printing speed:



    [0113] This is the velocity of the moving web (substrate) in feet per minute.

    Water window:



    [0114] The water window gives a range of the fountain solution settings for which a targeted print density can be achieved. The larger the water window, the more robust lithography is anticipated.

    Printed optical density:



    [0115] This is the achieved optical density of the cured prints under the given ink duct settings and fountain settings when measured inline with a mounted densitometer.

    Example 1 Synthesis of an inert polyester resin from recycled PET



    [0116] Reclaimed or scrap PET (52.5 parts), 1,2-propanediol (4.0 parts), glycerol (9.6 parts) and Tyzor TBT catalyst (0.4 parts, available from Dorf Ketal, Tyzor ® TBT is a trademark of Dorf Ketal) were charged to a dry reactor. The mixture was agitated and heated to between 215 and 220°C under nitrogen and held at this temperature for about 4 hours whereby all the PET was dissolved. Benzoic acid (8.8 parts) and phthalic anhydride (22.8 parts) were added over a 1 hour period and the temperature was increased to 230°C. The temperature was further increased to 240°C and maintained until the acid number was no longer decreasing linearly with time. The binder resin had an acid value of 36 mg KOH per gram, a number average molecular weight (Mn) of 1300 and a weight average molecular weight (Mw) of 6000. The Tg was determined to be 48°C. The hydroxyl value was 115.

    Example 2 Synthesis of a polyester acrylate resin from recycled PET



    [0117] A process for preparing a polyester acrylate resin according to the present invention was carried out as follows. Reaction steps (a) (b) and (c) are carried out in the same reactor as follows without further purification between the steps.

    Step (a) Depolymerization



    [0118] 232.8 g (1.21 mol) of PET flakes (obtained from stf-recycling GmbH, grade: clear) 47.4 g (0.46 mol) of neopentyl glycol (2,2-Dimethyl-1,3-propanediol), 82.7 g (0.62 mol) of trimethylolpropane (2-ethyl-2-(hydroxymethyl)-1,3-propanediol) and 0.3 g Tyzor TBT catalyst were placed in a 1-liter glass flask equipped with a thermometer, an inlet nitrogen, a Dean-Stark apparatus equipped with reflux condenser, and a mechanical stirrer. The reaction mixture was heated in a nitrogen stream up to 230°C, and maintained at that temperature for about three hours. As temperature increased the PET gradually dissolved and the reaction mixture formed into a slurry which was stirred until it became transparent.

    Step (b) Esterification



    [0119] The reaction mixture was cooled to 125°C, and 140.3 g (0.95 mol) of phthalic acid and 81.8 g (0.79 mol) of neopentyl glycol, were added to the flask and heated under nitrogen to 240°C. The reaction was continued until the acid value dropped below 10 mg KOH/g. The resultant polyester polyol resin had a number average molecular weight (Mn) of 1000 and a weight average molecular weight (Mw) of 1800. The hydroxyl value was 300.

    Step (c) Acrylation



    [0120] The temperature was then lowered to 100°C and 0.32 g of 4-methoxyphenol, 0.28 g of methane sulfonic acid, 10 ml of toluene and 10 ml of heptane was added to the flask. The nitrogen was shut off and air was bubbled through the reaction mixture. 120.0 g (1.67 mol) of acrylic acid was then added and the reaction mixture was heated to reflux. The reaction was continued until the acid value dropped below 10 mg KOH/g. Then, vacuum (100 mbar) was applied and the volatile materials were stripped off to provide a viscous liquid. The product yield was 528g.

    Characterization:


    Molecular weight:



    [0121] 

    Number average molecular weight (Mn): 1550

    Weight average molecular weight (Mw): 3500

    Color: 3-4 Gardner

    Acid value: 6 mg KOH/g

    Viscosity of a varnish containing 36% of the polyester acrylate obtained after step (c) and 64% trimethylol propane triacrylate: 65.4 Pa·s @ 25°C


    Examples 3 & 4: Two ink formulations Examples 3 & 4 are shown in Table 1. The two cyan lithographic energy curable packaging inks were made on a three roll mill 3 passes at IMPa (25°C), having the following composition and properties:



    [0122] 





    [0123] The viscosity for Examples 3 and 4 are similar and both are suitable for use as energy curable lithographic printing inks.

    [0124] Regarding water uptake, scumming, tinting and shear stress values under emulsification, the ink of Example 4 behaved very similar compared to commercial UV offset inks from the Sun Chemical Suncure product portfolio and is therefore would be expected to perform similar on an offset press.
    Table 2: Press Performance at 400 ft./min. - the inks were tested on a Didde web offset press equipped with two UV-dryers.
    Printing Press results low speedExample 3Example 4
    Ink duct setting in units 1.75 1.25
    Printing speed (feet per minute) 400 400
    Water window in % 20-30 24-44
    Printed optical density in units 1.58/1.56 1.57/1.56/1.48
    UV-cure results 1 lamp high - Good 1 lamp high - Good
    Misting properties Good Good
    Fountain solution: Rycoline ACFS 193; 5 ounces to each gallon of tap water.
    Substrate: CIS (coated one side) paper.


    [0125] Table 2 shows with a reduced ink duct setting (less ink needed), Example 4 exhibits a higher water window and equivalent optical density than Example 3.
    Table 3: Press Performance at 1000 ft./min. The inks were tested on a Didde web offset press equipped with two UV-dryers.
    Printing Press results high speedExample 3Example 4
    Ink duct setting in units 1.75 1.25
    Printing speed (feet per minute) 1000 1000
    Water window in % 20% 24%
    Printed optical density in units 1.56 1.52
    UV-cure results 1 lamp high - Good 1 lamp low-fair cure 1 lamp high - Good 1 lamp low - Good cure
    Misting properties Good Good


    [0126] Table 3 shows that Example 4 exhibits a slightly wider water window, reduced duct setting and comparable optical density when compared to Example 3.

    [0127] Furthermore Example 4 exhibited a better UV-cure, than Example 3 which showed slightly limited cure properties if the press was run at high speed. Both Example 3 and Example 4 exhibited good lithographic performance on the Didde press trial.

    [0128] The following exemplifies that steps (a) and (b) of the process can be combined into a single step;

    Example 5: Combination of Steps (a) and (b) into a Single Step



    [0129] Reclaimed or scrap PET (58.6 parts), diethylene glycol (24.9 parts), phthalic anhydride (15.8 parts) were charged to a dry reactor. The mixture was agitated and heated to between 210 and 220°C under nitrogen and held at this temperature for about 1.5 hours whereby all PET dissolved. Tyzor TBT catalyst (0.2 parts, available from Dorf Ketal, Tyzor ® TBT is a trademark of Dorf Ketal) was added rapidly and the temperature was increased to 220-230°C for 6 hours. The binder resin had an acid value of 0.02 mg KOH per gram and a molecular weight of Mn = 1200 and Mw 2200.

    Example 6: Combination of Steps (a) and (b) into a Single Step Followed by Acrylation Step



    [0130] Reclaimed or scrap PET (54.7 parts), 1,2-propanediol (16.7 parts), phthalic anhydride (25.1 parts) were charged to a dry reactor. The mixture was agitated and heated to between 210 and 220°C under nitrogen and held at this temperature for about 1.5 hours whereby all PET dissolved. Tyzor TBT catalyst (1.0 parts, available from Dorf Ketal, Tyzor ® TBT is a trademark of Dorf Ketal) was added rapidly and the temperature was increased to 220-230°C for 7 hours, during which time a small amount of water was removed via a Dean-Stark trap.

    [0131] Next, an air flow replaced the nitrogen stream for 1 hour and the temperature was lowered to 120C. An amount of ethoxylated trimethylolpropane triacrylate (EO-TMPTA) (Sartomer) to make a 40-60 wt% solids solutions was added and homogenized for 2 hours. Acrylic acid, 2.5 parts, was added dropwise with 0.1 part of methane sulfonic acid. After 2 hrs., a light brown solution was obtained with Mn = 3400 and Mw = 4670.

    Examples 7 & 8: Two ink formulations Examples 7 & 8 are shown in Table 4. The two lithographic energy curable packaging inks were made on a three roll mill, 3 passes at IMPa (25°C), having the following composition and properties:



    [0132] 
    Table 4: An energy curable lithographic ink (Inventive Example 8) was made comprising the polyester acrylate resin derived from Example 6 and was compared to Example 7.
    MaterialExample 7 (Comparative)Example 8 (Inventive)
    Varnish with inert formaldehyde resin in EO-TMPTA (48%) 45.00 -
    Varnish with polyester acrylate resin of Example 6 in EO-TMPTA (36%) - 43.00
    Multifunctional acrylate monomer blend (Sun) 15.50 17.50
    Flow agent (Tego) 0.50 0.50
    Stabilizer (Rahn group) 1.00 1.00
    Photoinitiator blend, based on aminobenzoates & benzophenones & aminoketones (Sun) 13.00 13.00
    Blue pigment 15:3 (Sun) 22.00 22.00
    Inorganic filler (Emerys) 3.00 3.00
    Total 100.00 100.00
    Set-off test @ OD ∼1.5    
     - 33mJ/cm2 0.19 0.05
     -66mJ/cm2 0.09 0.01
     -100mJ/cm2 0.05 0.00
     -133mJ/cm2 0.01 0.00
    Color strength (%) 100.0 102.7


    [0133] Prints (50µm) were prepared using a prüfbau Deltack on a PE-board to measure the color density and set-off. The coatings were cured with UV-light irradiation (Fusion H-bulb ∼200W/cm) using H-bulb.

    [0134] Table 4 shows that the UV-cure measured by set-off test was considerably better for Inventive Example 8 vs. Comparative Example 7 (a lower figure set-off figure indicates reduced ink transfer, indicating improved cure).

    [0135] Inventive Example 8 also exhibited slightly improved color strength as measured using a Gretag-Macbeth CE 2180 color computer.

    Examples 9 & 10: Two lithographic UV-curable ink formulations Examples 9 and 10 are shown in Table 5. A cyan UV-curable ink (Example 10) was made on a three roll mill, 3 passes at IMPa (25°C), having the following composition and properties and compared to a standard energy curable offset ink (Example 9 - Suncure Starluxe, Sun Chemical Corp.).



    [0136] 







    [0137] The viscosity and tack of Example 10 are comparable to the Example 9 commercial UV offset ink Suncure Starluxe process cyan.

    [0138] Furthermore Example 10 exhibits a better cure than Example 9, which is assessed by the set off test and the solvent resistance (lower set-off values and higher solvent rubs observed)

    [0139] Example 10 also shows better deinking properties (lower color density of recycled deinked paper) than the Example 9. This test is described in detail in Example 13.

    [0140] Example 10 unexpectedly exhibits a high level of resin speck removal and brightness required to create recyclable paper and this is a further advantage in addition to the fact that such an ink can be made from a substantial amounts of material that otherwise may be disposed as waste.

    [0141] Furthermore Example 10 ink shows better ink transfer measured by the weight of ink transferred from the printing plate to the blanket under defined conditions than the Example 9 comparative ink. This test is described in detail in Example 12.

    [0142] Example 10 also shows better solvent resistance than Example 9.

    Example 11:



    [0143] To further demonstrate the press performance of inks of the present invention, inks of Example 9 and Example 10 were printed with a "Didde" web offset UV-press (Graphic system services, U.S.A.) equipped with two UV-dryers having medium pressure mercury bulbs. Both inks of Example 9 and Example 10 exhibited good lithographic performance on the Didde press trial.

    Example 12: Lithographic Performance & Ink transfer:



    [0144] 1 kg of experimental ink (Example 10) was placed into the ink duct of an "Ink evaluation unit" KGB-0024 from Mitsubishi Heavy Industries Ltd. Fountain solution: de-ionized water, Sunfount 480 (3%) from Sun Chemical Company, isopropyl alcohol (5%) and rehardener (0.5%). The roller speed was set to 300 meters per minute, roller temperature was 30°C. The ink was run for approximately 20 minutes (starting dampening settings 35%, ink settings constant @ 8%) in order to achieve a constant film weight of approximately 2.5µm, measured at ink weight sensor near the printing plate.

    [0145] Then, the fountain solution setting was decreased by 5% and 10% every 2 minutes. Then, the fountain solution was further increased by 10% and further increased by 3%, 6%, 9%, and 12% every 2 minutes and back to starting dampening settings and the change of film weight and water was detected. The amount of transferred ink was measured in grams.

    [0146] During the experiment, the ink weight and water conditions were monitored. The target was to obtain a stable ink film weight near the printing plate throughout the whole experiment, which illustrates a robust lithographic performance, which was the case for Example 10. The same experiment with the same settings was conducted with the ink of Example 9, with similar results as Example 10, showing that the inks of the present invention have good lithographic performance and are equivalent to a commercial UV lithographic ink

    Example 13: Deinking:



    [0147] Preparation of printed sheets of paper which are later used for the de-inking evaluation:
    50 to 55g paper (STD-LWC 70g/m2) was full-surface printed with an ink prepared as described in Example 9 (comparative) and Example 10 (inventive) on a single side of the paper using a Peach Proofer (Rycobel group). The instrument consists of two parts: the inker and the printer unit. The inker is a three roller system, made of a driving roller, an oscillating roller and a rubber distribution roller which transfers ink to the print disc. The print disc is then transferred to the printer unit. The material to be printed is clipped on to the substrate carrier and placed on the printing ledge of the printer. The print disc is then lowered into position and a print produced. The parameters were adjusted to produce prints with a cyan density of 1.2 to 1.6 measured with a SpectroEye of Gretag AG densitometer. The prints were torn into pieces using a paper shredder producing stripes of (0.4 x 20) cm. The preparation and dosing of chemicals was done as given in INGEDE Method 11:

    Preparation of Deinking Solution A:



    [0148] 6g of sodium hydroxide was dissolved in 1.31 of de-ionized water and heated slightly to approximately 60°C. 8g of oleic acid was then added. The mixture was stirred until the solution became clear, then 18g of sodium silicate was added. Finally de-ionized water was added until the solution volume reached 21.

    Preparation of Deinking Solution B:



    [0149] 100ml of hydrogen peroxide solution was used for each test. This was prepared by adding 4g of hydrogen peroxide solution (35% in water) to de-ionized water.

    [0150] During sample preparation, a constant temperature of 45°C was maintained. The dilution water is therefore stored in a water bath whose temperature is controlled accordingly.
    Table 6: The de-inking mixture was prepared according to the following recipe:
    Printed paper, printed as described above: 50g
    Deionized water: 208g
    Deinking solution A: 100g
    Deinking solution B: 25g
    Deionized water: 117g


    [0151] The mixture was stirred in a Dissolver for 20 minutes resulting in a homogenous pulp. About 350g water, which was pre-heated to 45°C before addition, is added to make stirring of the mass easier. After 20 minutes, the pulp is filled up with 45°C hot water so that the sum of mass of all ingredients is 1,050g. The pulp is stored for 60 minutes in a water bath at 45°C.

    [0152] Next, the pulp was poured into the pre-treated flotation cell as described in 5.13 in the INGEDE Method 11. Parameters (e.g. air supply rate and stirrer speed were used as given in 5.13.1 of the Method). During the entire flotation process, the froth was removed.

    [0153] After a flotation period of 10 minutes the air supply and the stirrer were switched off.

    [0154] A specimen is obtained by filtration of the pulp. Values obtained by measurement of the color strength of the specimen where Ink of Example 9 (comparative) was used was compared with the color strength of the specimen where Ink of Example 10 (inventive) was used.

    Example 14: Performance of lithographic inks containing inert polyester resin derived from recycled PET on press



    [0155] The two cyan UV-curable inks of Example 9 and 10 were tested on a Didde narrow web offset press equipped with two UV-dryers @ 240 Watts / cm. Fountain solution: Rycoline ACFS 193; 5 ounces to each gallon of tap water. Substrate: C1S (coated one side) paper
    Table 7: Lithographic performance
    Printing press results:Ink of Example 9 (comparison)Ink of Example 10 (inventive)
    Printing speed (feet per minute) 400 400
    Printed optical density in units 1.60 1.58
    UV-lamp energy / UV-cure results 1 lamp high - Good 1 lamp high - Good
    Misting properties Good Good


    [0156] The ink with inert polyester resin derived from recycled PET was comparable to the standard. Both inks showed a good performance on the press.

    Example 15: Energy-curable flexographic consumer product packaging inks.



    [0157] The inert polyester resin produced in Example 1 was incorporated into an energy-curable flexographic consumer product packaging inks as follows;

    [0158] Ebecryl LEO 10501 from Allnex company was heated with Genopol 16 stabilizer to a temperature of 90°C and the inert polyester resin produced in Example 1 was periodically added as the mixture was stirred until all resin material was fully dissolved, resulting in a clear and homogenous solution. The mixture was then filtered through a clean 100µm brass filter. The formulation is shown in Table 8.
    Table 8:
    MaterialWeight %
    inert polyester resin derived 45.0
    from recycled PET  
    Ebecryl LEO 10501 (Allnex) 54.0
    Genorad 16 (Rahn group) 1.0
    Total 100
    Viscosity 40.1 Pas@ 25°C (Shear rate D = 1/50 seconds)
    Color 5-6 Gardner


    [0159] To make an UV-curable reflex blue flexographic ink, the resin solution was added to other ink components and the mixture was rendered into a flexographic ink by the typical procedures known in the art, such as pre-dispersing in a dissolver, three-roll milling or bead-milling or combination milling, until the desired degree of grinding was achieved. The formulation is shown in Table 9. The ink was applied in different coating weights with an Erichsen printing proofer, Model 628 on Aluminum substrate, suitable for yoghurt cup lids.
    Table 9.
    Raw MaterialWeight (g)
    rPET-Polyester solution 17.50
    Genorad 16 (Rahn group) 2.00
    EFKA 7701 (BASF) 7.50
    Raylack 19 (Sunchemical) 25.00
    SR 494 LM (Allnex) 32.0
    Ebecryl Leo 10502 5.00
    Airex 920 (Evonik) 0.10
    Twin 4000 (Evonik) 0.20
    Esacure 1001 (Lamberti) 2.00
    Photoinitiator solution (40%) 18.50
    Tego Wet 500 (Evonik) 1.00
    Helogenblue D7110 (BASF) 23.50
    Hostapermviolett PL-R (Clariant) 17.50
    Total 151.80
       
    Viscosity @ D = 2 s-1 [Pas] 6.10
    Viscosity @ 100 s-1 [Pas] 1.42
    Viscosity @ 2 s-1 [Pas] repeat 2.21
    Appearance of print on aluminum (glossy) ok
    Ink Transfer high
    Solvent resistance versus ethyl acetate 15 double-rubs


    [0160] The present invention has been described in detail, including the preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention that fall within the scope and spirit of the invention.


    Claims

    1. A process for preparing a polyester acrylate resin having a number average molecular weight (Mn) of at least 800 Da comprising

    (a) reacting polyethylene terephthalate (PET) with one or more polyhydric alcohols to provide a depolymerization product;

    (b) reacting the depolymerization product with a polybasic carboxylic acid and/or anhydride and optionally a polyhydric alcohol to form a polyester polyol and

    (c) reacting the polyester polyol with acrylic acid to provide a polyester acrylate resin;

    wherein the number average molecular weight is measured according to the method described in paragraphs [00091] to [00092] of the description.
     
    2. A process according to claim 1 wherein the PET in step (a) is derived from waste material generated in the production of PET or the production of PET molded articles, optionally wherein the PET is derived from waste PET molded articles.
     
    3. A process according to any one of the preceding claims wherein the polyhydric alcohol is neopentyl glycol and/or trimethyolpropane.
     
    4. A process according to any one of the preceding claims wherein the wt% ratio of PET to polyhydric alcohol in step a) is between 20:1 to 1:10.
     
    5. A process according to any one of the preceding claims wherein a catalyst is used in step (a) to promote the depolymerization reaction, optionally wherein the catalyst is tetraisopropyltitanate or titanium(IV) butoxide, and/or the amount of the catalyst is between 0.01 to 2.50 wt% based on the total weight of reaction mixture.
     
    6. A process according to any one of the preceding claims wherein the reaction of step (a) is carried out at a temperature of between 160 to 260°C.
     
    7. A process according to any one of the preceding claims wherein the polybasic carboxylic acids and/or anhydrides in step (b) are phthalic acid anhydride (PAA) and/or methylhexahydrophthalic acid anhydride (MHHPA) and/or wherein the polybasic carboxylic acids and/or anhydrides are added in an amount of less than 60 wt% based upon the weight of the depolymerization product.
     
    8. A process according to any one of the preceding claims wherein a polyhydric alcohol is added to the reaction mixture in step (b), optionally wherein the polyhydric alcohol is neopentyl glycol, and/or wherein the polyhydric alcohol used in step (b) is added in an amount of 20 wt% or less based on the weight of the depolymerization product.
     
    9. A process according to any one of the preceding claims wherein a monofunctional acid is added to the reaction mixture during step (b).
     
    10. A process according to any one of the preceding claims wherein the esterification reaction of step (b) is carried out at a temperature of between 180°C to 220°C and/or is carried out until the acid value of the reaction mixture is reduced to between 2 to 50 mgKOH/g.
     
    11. A process according to any one of the preceding claims wherein the polyester polyol has a number average molecular weight (Mn) of between 850 and 5,000 Da, and/or a weight average molecular weight (Mw) of between 1500 and 25,000 Da.
     
    12. A process according to any one of the preceding claims wherein the acrylation of step (c) is carried out in the presence of:

    (i) an acidic catalyst, optionally wherein the acid catalyst is methane sulfonic acid; and/or

    (ii) a polymerization inhibitor, optionally wherein the inhibitor is a phenol, or a copper or an aluminium based inhibitor.


     
    13. A process according to any one of the preceding claims wherein the acrylation of step (c) is carried out at a temperature of between 80 to 130°C.
     
    14. A process according to any one of the preceding claims wherein steps (a) and (b) are carried out simultaneously.
     
    15. A polyester acrylate resin prepared by a process according to any one of the preceding claims, optionally wherein said polyester acrylate resin has:

    (i) a glass transition temperature of at least 20°C; and/or

    (ii) an acid value less than 50 mg KOH/g; and/or

    (iii) a number average molecular weight (Mn) of 800 to 5,000 Da; and/or

    (iv) a weight average molecular weight (Mw) of 2000 to 25,000 Da.


     
    16. An energy curable coating composition or ink comprising a polyester acrylate resin according to claim 15, optionally wherein said composition or ink comprises between 15 to 50 wt% of said polyester acrylate resin.
     
    17. An energy curable coating composition or ink comprising:

    i) between 2 to 40 wt% of an inert polyester resin wherein the inert polyester resin comprises a polyethylene terephthalate oligomer having about 40 to 70 wt% recurring ethylene terephthalate units, recurring units of C3+ alpha alkylene terephthalate, hydroxy alkylene terephthalate and pendant units of polybasic aliphatic, alicyclic or aromatic monocarboxylate, wherein the inert polyester resin is prepared by process steps (a) and (b) according to any one of claims 1 to 14; and

    ii) comprising a polyester acrylate resin according to claim 15.


     
    18. A coating composition or ink according to claim 16 or claim 17 comprising:

    (i) a further acrylated oligomer; and/or

    (ii) an acrylic monomer, optionally wherein the acrylic monomer is trimethylolpropane tri acrylate (TMPTA), alkoxylated trimethylolpropane tri acrylate, propoxylated pentaerythritol tetraacrylate (PPTTA) and mixtures thereof; and/or

    (iii) an organic or inorganic pigment; and/or

    (iv) a photoinitiator.


     
    19. A coating composition or ink according to any one of claims 16 to 18 wherein the coating composition or ink is a lithographic energy curable coating composition or ink.
     
    20. A process for preparing an article with a coating or an ink printed thereon comprising

    a) applying the coating composition or ink according to any one of the preceding claims 16 to 19 to a surface of an article and

    b) curing the coating composition or ink; optionally

    wherein the article is a food packaging article.
     
    21. An article with a cured coating or ink thereon comprising a cured coating composition or ink according to anyone of claims 16 to 19 on a surface of the article.
     


    Ansprüche

    1. Verfahren zur Herstellung eines Polyesteracrylatharzes mit einem zahlenmittleren Molekulargewicht (Mn) von mindestens 800 Da, das Folgendes umfasst:

    (a) Umsetzen von Polyethylenterephthalat (PET) mit einem oder mehreren mehrwertigen Alkoholen zur Bereitstellung eines Depolymerisationsprodukts;

    (b) Umsetzen des Depolymerisationsprodukts mit einer mehrbasigen Carbonsäure und/oder einem Anhydrid und gegebenenfalls einem mehrwertigen Alkohol zur Bildung eines Polyesterpolyols und

    (c) Umsetzen des Polyesterpolyols mit Acrylsäure zur Bereitstellung eines Polyesteracrylatharzes;

    wobei das zahlenmittlere Molekulargewicht gemäß der in den Absätzen [00091] bis [00092] der Beschreibung beschriebenen Methode gemessen wird.
     
    2. Verfahren nach Anspruch 1, wobei sich das PET in Schritt (a) von bei der Herstellung von PET oder der Herstellung von PET-Formkörpern anfallendem Abfallmaterial ableitet, gegebenenfalls wobei sich das PET von Abfall-PET-Formkörpern ableitet.
     
    3. Verfahren nach einem der vorhergehenden Ansprüche, wobei es sich bei dem mehrwertigen Alkohol um Neopentylglykol und/oder Trimethylolpropan handelt.
     
    4. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Gew.-%-Verhältnis von PET zu mehrwertigem Alkohol in Schritt a) zwischen 20:1 bis 1:10 liegt.
     
    5. Verfahren nach einem der vorhergehenden Ansprüche, wobei in Schritt (a) ein Katalysator zur Förderung der Depolymerisationsreaktion verwendet wird, gegebenenfalls wobei es sich bei dem Katalysator um Tetraisopropyltitanat oder Titan(IV)-butoxid handelt, und/oder die Menge des Katalysators zwischen 0,01 bis 2,50 Gew.-%, bezogen auf das Gesamtgewicht der Reaktionsmischung, liegt.
     
    6. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Umsetzung von Schritt (a) bei einer Temperatur zwischen 160 bis 260 °C durchgeführt wird.
     
    7. Verfahren nach einem der vorhergehenden Ansprüche, wobei es sich bei den mehrbasigen Carbonsäuren und/oder Anhydriden in Schritt (b) um Phthalsäureanhydrid (PAA) und/oder Methylhexahydrophthalsäureanhydrid (MHHPA) handelt und/oder wobei die mehrbasigen Carbonsäuren und/oder Anhydride in einer Menge von weniger als 60 Gew.-%, bezogen auf das Gewicht des Depolymerisationsprodukts, zugegeben werden.
     
    8. Verfahren nach einem der vorhergehenden Ansprüche, wobei in Schritt (b) ein mehrwertiger Alkohol zu der Reaktionsmischung gegeben wird, gegebenenfalls wobei es sich bei dem mehrwertigen Alkohol um Neopentylglykol handelt, und/oder wobei der in Schritt (b) verwendete mehrwertige Alkohol in einer Menge von 20 Gew.-% oder weniger, bezogen auf das Gewicht des Depolymerisationsprodukts, zugegeben wird.
     
    9. Verfahren nach einem der vorhergehenden Ansprüche, wobei während Schritt (b) eine monofunktionelle Säure zur Reaktionsmischung gegeben wird.
     
    10. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Veresterungsreaktion von Schritt (b) bei einer Temperatur zwischen 180 °C bis 220 °C durchgeführt wird und/oder durchgeführt wird, bis die Säurezahl der Reaktionsmischung auf zwischen 2 bis 50 mg KOH/g verringert ist.
     
    11. Verfahren nach einem der vorhergehenden Ansprüche, wobei das Polyesterpolyol ein zahlenmittleres Molekulargewicht (Mn) zwischen 850 und 5000 Da und/oder ein gewichtsmittleres Molekulargewicht (Mw) zwischen 1500 und 25.000 Da aufweist.
     
    12. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Acrylierung von Schritt (c) in Gegenwart von

    (i) einem sauren Katalysator, gegebenenfalls wobei es sich bei dem sauren Katalysator um Methansulfonsäure handelt; und/oder

    (ii) einem Polymerisationsinhibitor, gegebenenfalls wobei es sich bei dem Inhibitor um ein Phenol oder einen Inhibitor auf Kupfer- oder Aluminiumbasis handelt,

    durchgeführt wird.
     
    13. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Acrylierung von Schritt (c) bei einer Temperatur zwischen 80 bis 130 °C durchgeführt wird.
     
    14. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Schritte (a) und (b) gleichzeitig durchgeführt werden.
     
    15. Polyesteracrylatharz, hergestellt durch ein Verfahren nach einem der vorhergehenden Ansprüche, gegebenenfalls wobei das Polyesteracrylatharz

    (i) eine Glasübergangstemperatur von mindestens 20 °C und/oder

    (ii) eine Säurezahl von weniger als 50 mg KOH/g und/oder

    (iii) ein zahlenmittleres Molekulargewicht (Mn) von 800 bis 5000 Da und/oder

    (iv) ein gewichtsmittleres Molekulargewicht (Mw) von 2000 bis 25.000 Da

    aufweist.
     
    16. Energiehärtbare Beschichtungszusammensetzung oder Tinte, umfassend ein Polyesteracrylatharz nach Anspruch 15, gegebenenfalls wobei die Zusammensetzung oder Tinte zwischen 15 bis 50 Gew.-% des Polyesteracrylatharzes umfasst.
     
    17. Energiehärtbare Beschichtungszusammensetzung oder Tinte, umfassend:

    i) zwischen 2 bis 40 Gew.-% eines inerten Polyesterharzes, wobei das inerte Polyesterharz ein Polyethylenterephthalat-Oligomer mit etwa 40 bis 70 Gew.-% Ethylenterephthalat-Wiederholungseinheiten, Wiederholungseinheiten von C3+-alpha-Alkylenterephthalat, Hydroxyalkylenterephthalat und seitenständige Einheiten von mehrbasigem aliphatischem, alicyclischem oder aromatischem Monocarboxylat umfasst, wobei der inerte Polyester durch Verfahrensschritte (a) und (b) nach einem der Ansprüche 1 bis 14 hergestellt wird; und

    ii) ein Polyesteracrylatharz nach Anspruch 15.


     
    18. Beschichtungszusammensetzung oder Tinte nach Anspruch 16 oder Anspruch 17, umfassend:

    (i) ein weiteres acryliertes Oligomer und/oder

    (ii) ein Acrylmonomer, gegebenenfalls wobei es sich bei dem Acrylmonomer um Trimethylolpropantriacrylat (TMPTA), alkoxyliertes Trimethylolpropantriacrylat, propoxyliertes Pentaerythrittetraacrylat (PPTTA) und Mischungen davon handelt; und/oder

    (iii) ein organisches oder anorganisches Pigment und/oder

    (iv) einen Photoinitiator.


     
    19. Beschichtungszusammensetzung oder Tinte nach einem der Ansprüche 16 bis 18, wobei es sich bei der Beschichtungszusammensetzung oder Tinte um eine lithographische energiehärtbare Beschichtungszusammensetzung oder Tinte handelt.
     
    20. Verfahren zur Herstellung eines Artikels mit einer Beschichtung oder einer darauf aufgedruckten Tinte, das Folgendes umfasst:

    a) Aufbringen der Beschichtungszusammensetzung oder Tinte nach einem der Ansprüche 16 bis 19 auf eine Oberfläche eines Artikels und

    b) Härten der Beschichtungszusammensetzung oder Tinte;

    gegebenenfalls wobei es sich bei dem Artikel um einen Lebensmittelverpackungsartikel handelt.
     
    21. Artikel mit einer gehärteten Beschichtung oder Tinte darauf, umfassend eine gehärtete Beschichtungszusammensetzung oder Tinte nach einem der Ansprüche 16 bis 19 auf einer Oberfläche des Artikels.
     


    Revendications

    1. Procédé pour la préparation d'une résine polyester acrylate possédant un poids moléculaire moyen en nombre (Mn) d'au moins 800 Da comprenant

    (a) la mise en réaction de poly(téréphtalate d'éthylène) (PET) avec un ou plusieurs alcools polyhydriques pour obtenir un produit de dépolymérisation ;

    (b) la mise en réaction du produit de dépolymérisation avec un acide carboxylique polybasique et/ou un anhydride polybasique et éventuellement un alcool polyhydrique pour former un polyester polyol et

    (c) la mise en réaction du polyester polyol avec de l'acide acrylique pour obtenir une résine polyester acrylate ;

    le poids moléculaire moyen en nombre étant mesuré conformément au procédé décrit dans les paragraphes [00091] et [00092] de la description.
     
    2. Procédé selon la revendication 1, le PET dans l'étape (a) étant issu de déchets générés dans la production de PET ou dans la production d'articles moulés en PET, éventuellement le PET étant issu de déchets d'articles moulés en PET.
     
    3. Procédé selon l'une quelconque des revendications précédentes, l'alcool polyhydrique étant le néopentylglycol et/ou le triméthylolpropane.
     
    4. Procédé selon l'une quelconque des revendications précédentes, le rapport de % en poids de PET à alcool polyhydrique dans l'étape a) étant compris entre 20:1 et 1:10.
     
    5. Procédé selon l'une quelconque des revendications précédentes, un catalyseur étant utilisé dans l'étape (a) pour promouvoir la réaction de dépolymérisation, éventuellement le catalyseur étant du titanate de tétraisopropyle ou du butoxyde de titane (IV), et/ou la quantité du catalyseur étant comprise entre 0,01 et 2,50 % en poids sur la base du poids total du mélange réactionnel.
     
    6. Procédé selon l'une quelconque des revendications précédentes, la réaction de l'étape (a) étant mise en œuvre à une température comprise entre 160 et 260 °C.
     
    7. Procédé selon l'une quelconque des revendications précédentes, les acides carboxyliques polybasiques et/ou les anhydrides polybasiques dans l'étape (b) étant l'anhydride de l'acide phtalique (PAA) et/ou l'anhydride de l'acide méthylhexahydrophtalique (MHHPA) et/ou les acides carboxyliques polybasiques et/ou les anhydrides polybasiques étant ajoutés en une quantité de moins de 60 % en poids sur la base du poids du produit de dépolymérisation.
     
    8. Procédé selon l'une quelconque des revendications précédentes, un alcool polyhydrique étant ajouté au mélange réactionnel dans l'étape (b), éventuellement l'alcool polyhydrique étant le néopentylglycol, et/ou l'alcool polyhydrique utilisé dans l'étape (b) étant ajouté en une quantité de 20 % en poids ou moins sur la base du poids du produit de dépolymérisation.
     
    9. Procédé selon l'une quelconque des revendications précédentes, un acide monofonctionnel étant ajouté au mélange réactionnel pendant l'étape (b).
     
    10. Procédé selon l'une quelconque des revendications précédentes, la réaction d'estérification de l'étape (b) étant mise en œuvre à une température comprise entre 180 °C et 220 °C et/ou étant mise en œuvre jusqu'à ce que l'indice d'acide du mélange réactionnel soit réduit jusqu'à une valeur comprise entre 2 et 50 mg de KOH/g.
     
    11. Procédé selon l'une quelconque des revendications précédentes, le polyester polyol possédant un poids moléculaire moyen en nombre (Mn) compris entre 850 et 5000 Da, et/ou un poids moléculaire moyen en poids (Mw) compris entre 1500 et 25 000 Da.
     
    12. Procédé selon l'une quelconque des revendications précédentes, l'étape (c) d'acrylation étant mise en œuvre en présence de :

    (i) un catalyseur acide, éventuellement le catalyseur acide étant l'acide méthanesulfonique, et/ou

    (ii) un inhibiteur de polymérisation, éventuellement l'inhibiteur étant un phénol, ou un inhibiteur à base de cuivre ou à base d'aluminium.


     
    13. Procédé selon l'une quelconque des revendications précédentes, l'étape (c) d'acrylation étant mise en œuvre à une température comprise entre 80 et 130 °C.
     
    14. Procédé selon l'une quelconque des revendications précédentes, les étapes (a) et (b) étant mises en œuvre simultanément.
     
    15. Résine polyester acrylate préparée par un procédé selon l'une quelconque des revendications précédentes, éventuellement ladite résine polyester acrylate possédant :

    (i) une température de transition vitreuse d'au moins 20 °C ; et/ou

    (ii) un indice d'acide inférieur à 50 mg de KOH/g ; et/ou

    (iii) un poids moléculaire moyen en nombre (Mn) de 800 à 5000 Da ; et/ou

    (iv) un poids moléculaire moyen en poids (Mw) de 2000 à 25 000 Da.


     
    16. Composition de revêtement ou encre durcissable par énergie comprenant une résine polyester acrylate selon la revendication 15, éventuellement ladite composition ou encre comprenant entre 15 et 50 % en poids de ladite résine polyester acrylate.
     
    17. Composition de revêtement ou encre durcissable par énergie comprenant :

    i) entre 2 et 40 % en poids d'une résine polyester inerte, la résine polyester inerte comprenant un oligomère de poly(téréphtalate d'éthylène) possédant environ 40 à 70 % en poids de motifs répétitifs de type téréphtalate d'éthylène, des motifs répétitifs de type téréphtalate de C3+ alpha alkylène, de téréphtalate d'hydroxy alkylène et des motifs pendants de monocarboxylate polybasique aliphatique, alicyclique ou aromatique, la résine polyester inerte étant préparée par les étapes de procédé (a) et (b) selon l'une quelconque des revendications 1 à 14 ; et

    ii) comprenant une résine polyester acrylate selon la revendication 15.


     
    18. Composition de revêtement ou encre selon la revendication 16 ou la revendication 17 comprenant :

    (i) un oligomère acrylé supplémentaire ; et/ou

    (ii) un monomère acrylique, éventuellement le monomère acrylique étant le triacrylate de triméthylolpropane (TMPTA), le triacrylate de triméthylolpropane alcoxylé, le tétraacrylate de pentaérythritol propoxylé (PPTTA) et des mélanges correspondants ; et/ou

    (iii) un pigment organique ou inorganique ; et/ou

    (iv) un photoinitiateur.


     
    19. Composition de revêtement ou encre selon l'une quelconque des revendications 16 à 18, la composition de revêtement ou l'encre étant une composition de revêtement ou une encre lithographique durcissable par énergie.
     
    20. Procédé pour la préparation d'un article comportant un revêtement ou une encre imprimée dessus comprenant

    a) l'application de la composition de revêtement ou de l'encre selon l'une quelconque des revendications précédentes 16 à 19 à une surface d'un article et

    b) le durcissement de la composition de revêtement ou de l'encre ; éventuellement l'article étant un article d'emballage de produit alimentaire.


     
    21. Article comportant un revêtement ou une encre durci(e) dessus comprenant une composition de revêtement ou une encre selon l'une quelconque des revendications 16 à 19 durci(e) sur une surface de l'article.
     




    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description




    Non-patent literature cited in the description