Radiation curable oligomers

Abstract

The present invention relates to radiation curable composition, wherein the composition comprises at least one urethane acrylate according to formula (I), wherein - R1 represents a residue of a polyisocyanate; - R2 represents a residue of a polyol; - the sum of n1 to n12 is from 16 to 100; - the sum of m1 to m12 is from 6 to 60; - the sum of n1 to n12 is greater than the sum of m1 to m12; and - o is from 0 to 3.

Description

[0001] 2024PF30127fc 1

[0002] RADIATION CURABLE OLIGOMERS

[0003] Field of the invention

[0004]

[0001] The present invention relates to certain radiation curable oligomers suitable for use in radiation-curable compositions. The present invention also relates to radiation-curable compositions comprising such oligomers, such as coating or ink compositions, as well as to articles comprising a substrate that is at least partially coated with a coating obtained by radical curing the radiation curable composition.

[0005] Background

[0006]

[0002] Nowadays coatings are used every day. Examples are items like coatings for transparent food packages, thin foils, coatings for flooring paints, and car part finishes. " Radiation curable" compositions, as used herein, refers to compositions that require radiation to initiate crosslinking to transform a liquid (uncured) composition to a solid (cured) coating. UV curing or free radical photopolymerization is the fastest growing curing technique, with a continuously increasing number of applications. UV curing saves energy and reduces or eliminates solvent emission in comparison with solvent-based systems because most radiation-curable formulations are 100% solid formulations containing reactive oligomers and diluents. The mechanical properties of the cured formulations are generally determined by the oligomers and diluents. For UV curing, photoinitiators are one of the key components for every photopolymerizable formulation as they generate upon light exposure radicals, which trigger the polymerization.

[0007]

[0003] " Low gloss" surfaces give products a much sought-after aesthetic effect, especially in the wood-furniture, flooring and wall covering industry, because they can create a very natural appearance that contribute to giving greater emphasis to the materiality of the article. At present, the creation of matte surfaces frequently involves the use of coating products the formulation of which contains matting agents made from organic and / or inorganic substances which, by positioning themselves on the coated surface and / or emerging on it, are able to act on the degree of reflection of light, giving the observer the visual sensation of a low gloss surface. However, the use of matting agents produces a worsening of the surface performance of the coating since, not being involved in the cross-linking and polymerization process, they lead to a significant reduction of stain resistance. Further there is a tendency for the matting agent to migrate to the coating surface after application and consequently the matting agent might get lost upon mechanical deformation, caused by for example scratch, resulting in an increase of gloss.

[0008]

[0004] WO-A-2013 / 092521 describes a process for the production of homogeneous matted coatings on flat surfaces based on a so-called 100% radiation-curable coating compositions. In this method, first, the 100% radiation-curable coating composition, that contains a low 2024PF30127fc 2

[0009] molecular weight, radiation-curable oligomer as binder and optionally one or more reactive diluents to reduce the viscosity, is coated on the surface of a flat substrate with a spiral blade. This wet paint layer is subsequently irradiated with UV light with a wavelength of from 200 to 420 nm and a radiation dose of 25 to 120 mJ / cm2 resulting in partial gelation of the coating composition. Then the so-obtained coating is irradiated with UV light from an Excimer lamp having a wavelength from 120 nm to 230 nm under inert 10 gas, followed by finish curing using conventional UV emitters. A disadvantage of the method described in WO-A-2013 / 092521 is that the viscosity of 100% radiation-curable coating composition is usually high making some application techniques, such as spraying, for example, difficult or impossible to use to apply the coating composition to the substrate. Spraying applications can advantageously be used to apply coating composition on substrates with more complex shapes, such as for example furniture or decorative frames. The viscosity of 100% radiation-curable coating composition can be reduced by adding diluents with low molecular weight. However, most used industrial (meth)acrylate reactive diluents are petroleum-based. In addition to the environmental concerns associated with the manufacture and use of such products, some of them also possess cytotoxicity profiles which make them undesirable for several end-use applications.

[0010]

[0005] This is especially the case with several multifunctional acrylates which are used as reactive diluents. For example trimethylolpropane triacrylate (TMPTA) is already labeled as: eye and skin irritant, sensitization, carcinogenic, and having acute and chronic aquatic toxicity. An other example is the mixture of tri- and tetraacrylates from pentaerytritol (PETIA) which is orally toxic, a skin irritant, can cause eye damage, a sensitizer, and is chronically hazardous to the aquatic environment.

[0011]

[0006] Thus, there exists a desire to reduce the viscosity of radiation-curable compositions in a different way than by increasing the amount of reactive diluent. It would also be desirable to provide radiation curable compositions which can provide a matte surface with sufficient high hardness, while also having a certain degree of flexibility since for many applications flexible cured materials are needed.

[0012]

[0007] W0-A1 -2023 / 227680 describes a process for preparing low gloss coatings from aqueous radiation-curable coating compositions comprising a water-dispersible polyurethane, a radiation-curable diluent and water. The process comprises applying the coating composition on a substrate, drying the coating composition to obtain an at least partially dried coating composition, irradiating the at least partially dried coating composition with UV light having a wavelength of < 220 nm under inert atmosphere, followed by irradiating with UV light having a wavelength of > 300 nm or E-beam. EP-A1-4183808 is directed to an active energy ray-curable composition comprising urethane (meth)acrylate obtained by reacting a polyisocyanate, a 2024PF30127fc 3

[0013] monofunctional (meth)acrylate having a hydroxy group, a polyfunctional (meth)acrylate having a hydroxy group, preferably pentaerythritol tri(meth)acrylate, and a polyfunctional

[0014] (meth)acrylate having no hydroxy group, preferably pentaerythritol tetra(meth)acrylate. WO- Al-2015 / 057439 discloses an agrochemical formulation containing polyoxyethylenepolyoxypropylene sorbitan fatty acid monoester and an agrochemical active.

[0015] Summary of the invention

[0016]

[0008] The invention relates to radiation curable compositions, wherein the composition

[0017] comprises at least one urethane acrylate according to formula (I):

[0018]

[0019] (I),

[0020] wherein

[0021] Ri represents a residue of a polyisocyanate;

[0022] R2 represents a residue of a polyol;

[0023] the sum of n₁ to n₁₂ is from 16 to 100;

[0024] the sum of m1to m12is from 6 to 60;

[0025] the sum of n1to n12is greater than the sum of m1to m12; and

[0026] o is from O to 3.

[0027]

[0009] The invention further relates to an article comprising a substrate at least partially coated

[0028] with a coating or ink obtained by radical curing of such a radiation curable composition.

[0029]

[0010] The invention further relates to an urethane acrylate oligomer according to the following formula (I):

[0030]

[0031] wherein

[0032] Ri represents a residue of a polyisocyanate;

[0033] R2 represents a residue of a polyol;

[0034] the sum of n₁ to n₁₂ is from 16 to 100;

[0035] the sum of mi to m is from 6 to 60; 2024PF30127fc 4

[0036] the sum of n₁ to n₁₂ is greater than the sum of m₁ to m₁₂; and

[0037] o is from 0 to 3.

[0038] Detailed Description of the invention

[0039]

[0011] The specification provides definitions for certain technical terms used in the specification and / or the claims. Any other technical term used in the specification and / or the claims that is not defined in the specification has the meaning attributed to it by one of ordinary skill in the art.

[0040]

[0012] For all upper and lower boundaries of any parameters given herein, the boundary value is included in each range for each parameter. All combinations of minimum and maximum values of the parameters described herein may be used to define the parameter ranges for various embodiments and preferences of the invention.

[0041]

[0013] As used herein, the acrylate functionality of a compound is the number of acrylate functional groups per molecule of the compound. An acrylate functional group has the following formula: CH2=CH-C(O)O-.

[0042]

[0014] The present invention is directed to a radiation curable composition, wherein the composition comprises at least one urethane acrylate according to formula (I):

[0043]

[0044] wherein

[0045] Ri represents a residue of a polyisocyanate;

[0046] R₂ represents a residue of a polyol;

[0047] the sum of n₁ to n₁₂ is from 16 to 100;

[0048] the sum of m1to m12is from 6 to 60;

[0049] the sum of n1to n12is greater than the sum of m1to m12; and

[0050] o is from O to 3.

[0051]

[0015] In an embodiment of the present invention, the radical curable composition is a coating or ink composition.

[0052]

[0016] The present invention is also directed to an urethane acrylate according to formula (I): 2024PF30127fc 5

[0053]

[0054] (I),

[0055] wherein

[0056] Ri represents a residue of a polyisocyanate;

[0057] R2 represents a residue of a polyol;

[0058] the sum of n₁ to n₁₂ is from 16 to 100;

[0059] the sum of mi to m is from 6 to 60;

[0060] the sum of to nn is greater than the sum of mi to mn; and

[0061] o is from O to 3.

[0062]

[0017] It has surprisingly been found that the urethane acrylate oligomers according to formula

[0063] (I) have a low viscosity and are able to provide radiation curable compositions with a low

[0064] viscosity, despite their relative high molar mass and functionality. An additional advantage of

[0065] the radiation curable compositions according to the invention is that they can produce, upon

[0066] curing, more flexible coatings with lower gloss.

[0067] Urethane acrylate according to formula (I)

[0068]

[0018] The sum of n₁ to n₁₂ is preferably equal to or greater than 20, more preferably equal to or greater than 30. The sum of n₁ to n₁₂ is preferably equal to or smaller than 90, more preferably

[0069] equal to or smaller than 80.

[0070]

[0019] The sum of m₁ to m₁₂ is preferably equal to or greater than 12. The sum of m₁ to m₁₂ is preferably equal to or smaller than 20.

[0071]

[0020] The sum of mi, m2, m3, iru, ms, me, m?, ms, mg, mio, mu, mn, ni, m, ns,, ns, ne, n?, ns, n9, nio, nn, andnn is preferably equal to or greater than 30. More preferably, the sum of mi, m2, m3, m4, ms, me, m?, ms, mg, mio, mu, mn, ni, n2, ns,, ns, ne, n?, ns, ng, nio, nn, andnn is equal to or greater than 40. The sum of mi, m2, m3, n, ms, me, m?, ms, mg, mio, mn, mn, ni, n2, ns,

[0072] n4, ns, ne, n?, ns, ng, nio, nn, andnn is preferably equal to or smaller than 100. More preferably, the sum of mi, m2, m3, m4, ms, me, m?, ms, mg, mio, mn, mn, ni, n2, ns,, ns, ne, n?, ns, ng, nw, nn, andnn is equal to or smaller than 80.

[0073]

[0021] The integer o is 0, 1, 2 or 3. Preferably, o is 0 or 1. In case o is 0, the urethane acrylate according to formula (I) contains one Ri and no R2. In case o is 1, the urethane acrylate

[0074] according to formula (I) contains two Ri’s and one R2. 2024PF30127fc 6

[0075]

[0022] Ri represents a residue of a polyisocyanate. As used herein, the residue of a polyisocyanate refers to a structure left after reacted isocyanate groups (-N=C=O) are removed from the polyisocyanate. Preferably, Ri represents a residue of a diisocyanate. More preferably, Ri is independently selected from the group consisting of the residue of pentane diisocyanate (PDI), hexane diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), meta-tetramethylenexylylene diisocyanate (TMXDI), toluene diisocyanate (TDI), dicy cl ohexylmethane-4, 4’ -diisocyanate (H12MDI), and methylenebisphenyl diisocyanate (MDI). Even more preferably, Ri is independently a C4-C12 divalent non-cyclic aliphatic hydrocarbon group or a Ce-Cis divalent aliphatic hydrocarbon group comprising at least one cycloaliphatic group. Even more preferably, Ri independently represents a residue of pentane diisocyanate (PDI), hexane diisocyanate (HDI), isophorone diisocyanate (IPDI), and

[0076] dicy cl ohexylmethane-4, 4’ -diisocyanate (H12MDI).

[0077]

[0023] R2 represents the residue of a polyol. As used herein, the residue of a polyol refers to a structure left after reacted hydroxyl groups (-OH) are removed. Preferably, R2 represents a residue of a polyol which is independently selected from the group consisting of polyether polyols, polyester polyols, and polycarbonate polyols. More preferably, R2 represents a residue of a polyol which is independently selected from the group consisting of polyether polyols and polycarbonate polyols. Even more preferably R2 is the residue of one or more polyether polyols. The polyol preferably has a number average molecular weight Mn, determined with the method as described further herein, of from 500 to 2500 g / mol. The polyol is preferably a diol. Most preferably R2 is independently selected from the group consisting of polypropylene glycols and polytetrahydrofurans.

[0078]

[0024] The urethane acrylate according to formula (I) preferably has a theoretical molar mass equal to or greater than 4000 g / mol, more preferably equal to or greater than 4500 g / mol. The urethane acrylate according to formula (I) preferably has a theoretical molar mass equal to or smaller than 7000 g / mol, more preferably equal to or smaller than 6500 g / mol, even more preferably equal to or smaller than 6000 g / mol. The theoretical molar mass of the urethane acrylate is the calculated molar mass obtained by adding the atomic masses of all atoms present in the idealized chemical formula (I) of the urethane acrylate.

[0079]

[0025] The urethane acrylates according to formula (I) can be prepared by a hexa-hydroxy functional core preferably based on sorbitol or mannitol, which is subsequently alkoxylated. The alkoxylation is performed using first propylene oxide followed by using ethylene oxide according to methods for alkoxylation that are well known in the art, for example under pressure at elevated temperatures using a base like KOH as catalyst. Alternative catalysts can be used as well. The so formed hexa-hydroxy functional oligomers can subsequently be esterified using 2024PF30127fc 7

[0080] well known procedures like for example acid catalyzed using azeotropic conditions to obtain oligomers with five acrylate functional groups and one hydroxy functional group, which are further reacted with polyisocyanate and optionally polyol to obtain urethane acrylates according to formula (I).

[0081] Radiation-curable composition

[0082]

[0026] The radiation-curable composition of the present invention comprises at least one urethane acrylate according to formula (I) in an amount of preferably at least 5% by weight, or at least 10% by weight, or at least 25% by weight, or at least 35% by weight, or at least 40% by weight, relative to the weight of the entire composition. The at least one urethane acrylate according to formula (I) is preferably present in the radiation-curable composition in an amount of at most 85% by weight, or at most 80% by weight, or at most 75% by weight, or at most 70% by weight, or at most 65% by weight, or at most 60% by weight, relative to the weight of the entire composition.

[0083]

[0027] The radiation-curable composition of the present invention preferably further comprises one or more radiation-curable diluents with an acrylate functionality of from 2 to 6 and preferably with a molar mass of less than 750 g / mol. With radiation-curable diluent (also referred to as reactive diluent) is meant a compound being able to reduce the viscosity of the composition while being able to free radically copolymerize. Examples of suitable radiation curable acrylate-functional diluent are trimethylolpropane diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,6-hexane diol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, glycerol propoxylate triacrylate, ethoxylated trimethylolpropane triacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexa-acrylate, and if applicable, their ethoxylated and / or propoxylated versions, and any mixture thereof. Preferably, at least one of the radiation-curable diluents has an acrylate functionality of 2 or 3, as this advantageously may result in a more pronounced matting effect. In a preferred embodiment, the radiation-curable composition of the present invention comprises at least two radiation-curable diluents and the radiation-curable diluents present in the radiation-curable -composition have an average acrylate functionality according to formula f = wkof from 2

[0084]

[0085] to 5, preferably from 2 to 4, in which Wk is the amount of acrylate functional radiation-curable diluents in g present in the radiation-curable composition with a molar mass Mk and with an acrylate functionality fk. Preferably, the radiation-curable composition of the present invention comprises monofunctional radiation-curable diluent in an amount less than 7 wt.%, more 2024PF30127fc 8

[0086] preferably at less than 5 wt.%, more preferably less than 3 wt.% and more preferably less than 1 wt.%, and especially preferred less than 0.5 wt.%, relative to the weight of the entire radiation-curable composition.

[0087]

[0028] If the radiation-curable composition of the present invention is a radiation-curable ink composition, it contains at least one pigment. Preferably, the amount of pigment based on the total weight of the radiation-curable ink composition is preferably from 0.5 to 50% by weight, more preferably from 2 to 30% by weight and more preferably from 3 to 20% by weight. The pigments which can be used in the radiation curable ink composition are those generally used in inks. A list of such pigments can be found in the Color Index.

[0088]

[0029] In case the radiation-curable composition of the invention is cured by ultraviolet light, the radiation-curable composition comprises at least one photoinitiator in an amount sufficient to obtain the desired cure response. Preferably, the one or more photo-initiators are present in an amount, relative to the entire weight of the radiation-curable composition, of from 0.25 to 20% by weight, or from 0.5 to 10% by weight, more preferably from 0.5 to 8 % by weight and even more preferably from 1 to 5 % by weight. The photoinitiators usable in the compositions of the invention are well known in the art. They can be chosen from a-hydroxyketones, a-aminoketones, benzildimethyl-ketals, (bis)acyl phosphine oxides, benzophenone derivatives, thioxanthones and blends of these. Photoinitiator aids are generally selected from the group of tertiary amines.

[0089]

[0030] The radiation-curable composition of the present invention may further comprise one or more additives such as stabilizers, inhibitors, dispersing agents, etc. The total amount does usually not exceed 5% by weight of the radiation-curable composition.

[0090]

[0031] The radiation-curable composition of the present invention may further comprise one or more fillers such as calcium carbonate, talc, aluminosilicate, silicium dioxide, etc. The amount of fillers is usually at most 15% by weight of the radiation-curable composition.

[0091]

[0032] Typically, the radiation-curable compositions of the present invention are not water- or solvent-based compositions, i.e., typically the radiation-curable composition of the present invention is 100% radiation-curable. A 100% radiation-curable composition refers to a composition which is substantially free of water and non-polymerizable volatile compounds. As used herein, substantially free of water and non-polymerizable volatile compounds means that the composition contains at most 5% by weight, more preferably at most 3% by weight, more preferably at most 1% by weight of water and non-polymerizable volatile compounds, relative to the entire weight of the radiation-curable composition of the present invention. A non-polymerizable volatile compound is a compound having an initial boiling point less than or equal to 250° C measured at a standard atmospheric pressure of 101.3 kPa. 2024PF30127fc 9

[0092]

[0033] The present invention is also directed to a coating or ink obtained by

[0093] (1) Preparing or providing a radiation curable coating or ink composition according to the invention,

[0094] (2) Applying the radiation curable coating or ink composition to at least part of a substrate,

[0095] (3) Radiation curing of the radiation curable coating or ink composition with a light source.

[0096]

[0034] The present invention is also directed to articles comprising a substrate that is at least partially coated with a coating or ink obtained by radical curing of the radiation curable composition as described herein above.

[0097]

[0035] The present invention is now illustrated by reference to the following examples. Unless otherwise specified, all parts, percentages and ratios are on a weight basis.

[0098] Examples

[0099] Synthesis of SorPO₂₄EO₈OH₆

[0100]

[0036] Under a nitrogen atmosphere, a 2 liter laboratory autoclave was charged with 163 gram sorbitol solution (70wt%, 0.626 mol) and 5.38 gram KOH solution (44.8wt%, 0.043 mol). The water was removed at 115°C under stirring, reducing the pressure slowly and employing a slight nitrogen stream (50ml / min). After 3 hours, the water was completely removed and a pressure of 120 mbar was obtained. Next the temperature was raised to 150°C and 872.8 gram propylene oxide (15.03 mol) was metered into the reactor during 3 hours (using an absolute pressure of 0.05 bar). After the addition, stirring was continued for 45 minutes. Next, using nitrogen, the reactor pressure was raised to 2.75 bar and 220 gram of ethylene oxide (4.99 mol) was likewise metered into the reactor during 3 hours. Next the stirring was continued for 3 hours at 2.75 bar after which the pressure was reduced to 10 mbar during 30 min. After cooling down to 80°C, 120 ml water and 17.4 g aqueous sulfuric acid (0.0215 mol) were added slowly and the reaction mixture was stirred for another 30 minutes before discharging into a glass flask. After removal of the water in vacuum (18 mbar, 1 hour 25°C, 3 hours 115°C) and filtration through a depth filter (T750, Seitz), compound with the idealized structure SorPO₂₄EO₈OH₆ was obtained as a clear product with a viscosity of 843 mPa.s.

[0101] Synthesis of SorPO₂₄EO₈Ac₅OH₁

[0102]

[0037] A 500 ml reactor equipped with a stirrer, nitrogen inlet, and Dean-Stark set-up was charged with 96.3 g (0.05mol) SorPO₂₄EO₈OH₆, obtained as described above, 18 g (0.25 mol) acrylic acid, 240 g toluene and 0.7 g methane sulphonic acid. The reaction was heated to reflux under a gentle stream of nitrogen and kept at this temperature until reaction water was no longer formed (4hr). After cooling down the reaction mixture was washed 3 times with a Na2COs 2024PF30127fc 10

[0103] solution followed by washing with water. After drying over Na2SO4 and filtration, the toluene was removed by distillation under reduced pressure yielding 110 g (97%) of oligomer with idealized structure SorPO₂₄EO₈Ac₅OH₁.

[0104] Synthesis of urethane acrylate oligomers

[0105] Example 1: Synthesis of SorPO₂₄EO₈Ac₅-IPDI-SorPO₂₄EO₈Ac₅ (1:0.6 ratio)

[0038] First, the 500 ml reactor equipped with a stirrer, air inlet, dropping funnel, and condenser was purged with dry lean air. Then 0.6 g BHT was added before 6.7g (0.03 mol) isophorone diisocyanate and 0.08 g of acrylic acid were charged into a reactor. After charging, the reactor was heated to 45 °C. Then the catalyst (Coscat® 83, 0.08g) was added followed by 219.6g (0.1 mol) of SorPO₂₄EO₈Ac₅OH₁ obtained as described above whilst stirring. After waiting one (1) hour for the reaction to commence, the temperature was then raised to 60°C. After 1 hr at 60°C, the temperature was raised to 85°C which was then further maintained for two (2) additional hours.

[0106]

[0039] After these two (2) additional hours of reaction time, the quantity of isocyanate (NCO) content was measured by a potentiometric titrator to ensure it was lower than 0.1% relative to the entire weight of the composition. If the isocyanate content was not lower than this value, the reaction was continued for an additional hour and checked again. This step was repeated until the isocyanate content fell to within the desired range. Finally, the resulting synthesized oligomer was cooled slowly and discharged yielding a mixture of 60 mol% of oligomer with idealized structure SorPO₂₄EO₈Ac₅-IPDI-SorPO₂₄EO₈Ac₅ (theoretical molar mass =4614) and 40 mol% of oligomer with idealized structure SorPO₂₄EO₈Ac₅OH₁.

[0107] Example 2: Synthesis of SorPO₂₄EO₈Ac₅-IPDI-SorPO₂₄EO₈Ac₅ (1:1 ratio)

[0108]

[0040] First, the 500 ml reactor equipped with a stirrer, air inlet, dropping funnel, and condenser was purged with dry lean air. Then 0.6 g BHT was added before 11.1g (0.05 mol) isophorone diisocyanate and 0.08 g of acrylic acid were charged into a reactor. After charging, the reactor was heated to 45 °C. Then the catalyst (Coscat® 83, 0.08g) was added followed by 219.6g (0.1 mol) SorPO₂₄EO₈Ac₅OH₁ obtained as described above whilst stirring. After waiting one hour for the reaction to commence, the temperature was then raised to 60°C. After 1 hr at 60°C the temperature was raised to 85°C which was then further maintained for two additional hours.

[0109]

[0041] After these two additional hours of reaction time, the quantity of isocyanate (NCO) content was measured by a potentiometric titrator to ensure it was lower than 0.1% relative to the entire weight of the composition. If the isocyanate content was not lower than this value, the reaction was continued for an additional hour and checked again. This step was repeated until the isocyanate content fell to within the desired range. Finally, the resulting synthesized 2024PF30127fc 11

[0110] oligomer was cooled slowly and discharged yielding SorPO24EO8Ac5-IPDI-SorPO24EO8Ac5(theoretical molar mass =4614) as idealized structure.

[0111] Example 3: Synthesis of SorPO24EO8Ac5-IPDI-pTHF650-IPDI-SorPO24EO8Ac5

[0112]

[0042] First, the 500 ml reactor equipped with a stirrer, air inlet, dropping funnel, and condenser was purged with dry lean air. Then 0.6 g BHT was added before 22.2g (0.1 mol) isophorone iisocyanate and 0.08 g of acrylic acid were charged into a reactor. After charging, the reactor was heated to 45 °C. Then 0.08g catalyst (Coscat® 83) was added followed by 32.5 g (0.05mol) polyTHF650 whilst stirring. After waiting one hour for the reaction to commence, the temperature was then raised to 60°C. At 60 °C 219.6g (0.1 mol) SorPO24EO8Ac5OH1obtained as described above and 0.07g Coscat® 83 were added after which the reaction temperature was raised to 85°C which was then further maintained for two additional hours.

[0113]

[0043] After these two additional hours of reaction time, the quantity of isocyanate (NCO) content was measured by a potentiometric titrator to ensure it was lower than 0.1% relative to the entire weight of the composition. If the isocyanate content was not lower than this value, the reaction was continued for an additional hour and checked again. This step was repeated until the isocyanate content fell to within the desired range. Finally, the resulting synthesized oligomer with the idealized structure SorPO24EO8Ac5-IPDI-pTHF650-IPDI-SorPO24EO8Ac5(theoretical molar mass of 5486) was cooled slowly and discharged.

[0114] Comparative example A: Synthesis of PentaAcs-IPDI-PentaAcs (1:0.6 ratio)

[0044] First, the 500 ml reactor equipped with a stirrer, air inlet, dropping funnel, and condenser was purged with dry lean air. Then 0.6 g BHT was added before 67g (0.3 mol) isophorone diisocyanat and 0.08 g of acrylic acid were charged into a reactor. After charging, the reactor was heated to 45 °C. Then the catalyst (Coscat® 83 0.08g) was added followed by 298 g (1 mol) pentaerythritol triacrylate (PentaAcsOHi) whilst stirring. After waiting one hour for the reaction to commence, the temperature was then raised to 60°C. After 1 hr at 60°C the temperature was raised to 85°C which was then further maintained for two additional hours.

[0115]

[0045] After these two additional hours of reaction time, the quantity of isocyanate (NCO) content was measured by a potentiometric titrator to ensure it was lower than 0.1% relative to the entire weight of the composition. If the isocyanate content was not lower than this value, the reaction was continued for an additional hour and checked again. This step was repeated until the isocyanate content fell to within the desired range. Finally, the resulting synthesized oligomer was cooled slowly and discharged yielding a mixture of 60 mol% of oligomer with idealized structure PentaAcs-IPDI-PentaAcs (theoretical molar mass =818) and 40 mol% of pentaerythritol triacrylate. 2024PF30127fc 12

[0116] Comparative example B: Synthesis of PentaAcs-IPDI-pTHFeso-IPDI-PentaAcs (in 20% DPGDA)

[0117]

[0046] First, the 21 reactor equipped with a stirrer, air inlet, dropping funnel, and condenser was purged with dry lean air. Then 0.6 g BHT and 174g dipropyleneglycol diacrylate (DPGDA) were added before 222g (1 mol) isophorone diisocyanate and 0.08 g of acrylic acid were charged into a reactor. After charging, the reactor was heated to 45 °C. Then 0.08g catalyst (Coscat® 83) was added followed by 650 g (1 mol) polyTHF650 whilst stirring. After waiting one hour for the reaction to commence, the temperature was then raised to 60°C. At 60 °C 298 g pentaerythritol triacrylate and 0.07g Coscat® 83 were added after which the reaction temperature was raised to 85°C which was then further maintained for two additional hours.

[0118]

[0047] After these two additional hours of reaction time, the quantity of isocyanate (NCO) content was measured by a potentiometric titrator to ensure it was lower than 0.1% relative to the entire weight of the composition. If the isocyanate content was not lower than this value, the reaction was continued for an additional hour and checked again. This step was repeated until the isocyanate content fell to within the desired range. Finally, the resulting synthesized oligomer with the idealized structure PentaAc3-IPDI-pTHF650-IPDI-PentaAc3 with theoretical molar mass of 1690 was cooled slowly and discharged in 20 wt.% DPGDA.

[0119]

[0048] Note: due to the very high viscosity of this oligomer this synthesis had to be performed diluted (20wt% DPGDA).

[0120] Determination of viscosity

[0121]

[0049] Viscosities were determined on a BROOKFIELD DVNXB5CBG rheometer equipped with 2.5cm diameter / l° cone / plate geometry at 25°C at a shear rate of 100s-1. CPA-40Z spindle (2.4 cm diameter / 0.8° cone / plate geometry) was used for samples with viscosity between 0.65 and 25 Pa.s; CPA-52Z spindle (1.2 cm diameter / 3° cone / plate geometry) was used for sample with viscosity from 25-800 Pa.s.

[0122] Determination of molecular weight by GPC

[0123]

[0050] The number-average molecular weight (Mn) and the weight-average molecular weight (Mw) were measured via SEC calibrated with a set of polystyrene standards with a molecular weight range of from 500 up to 7 x106g / mol and using as an eluent stabilized tetrahydrofuran [THF with 0.007- 0.015% w / w butyl-hydroxytoluene (BHT)] modified with 0.8 % acetic acid, at a flow rate of 1 mL / min at 40 °C.

[0124] More specifically, 50 mg of oligomer (as described below) was dissolved in 5 mL eluent for 16 hours at room temperature without shaking. 10 pL of the solution thus prepared were injected into the system for the measurement. 2024PF30127fc 13

[0125] The SEC measurements were carried out on a Waters GPC system which consisted of: i) a Waters 2414 refractive index detector at 40°C, ii) a Waters Shodex packed Column at 40°C -with four different Shodex packed columns (5000A, 500A, 150A and 50A pore size) with I / d = 300 / 8 mm and are filled with particles having a particle size of 10 (the 5000A column) or 6 pm (the 500A, 150A and 150A column) (1 pm= 1x10-6m), (supplied by Waters), iii) a Waters 2707 Autosampler - injection system and iv) a Waters 1515 -Isocratic HPLC pump. The Mnand Mwwere determined by the use of Empower 3 software from Waters.

[0126] Mandrel bend test

[0127]

[0051] Formulations were prepared using 95 parts of the various oligomers (as described below), 4.5 parts of Omnirad 1173 (2-hydroxy-2-methyl-l -phenylpropanone, CAS NO. 7473-98-5, obtained from IGM Resins) and 0.5 parts of Omnirad 907 (2 -methyl- 1 -[4-(methylthio)phenyl]-2-morpholinopropan-l-one, CAS NO. 71868-10-5, obtained from IGM Resins). Film was coated on stainless steel thicker panels (0.8mm thickness) and cured using a Fusion UV Rig equipped with a Fusion F600 H bulb employing a total dose of 1 J / cm2. The cured specimens were tested according to ISO 1520:2011 using TQC Sheen Cylindrical Mandrel Bend Tester.

[0128] Gloss measurements

[0129]

[0052] The gloss was determined according to ISO2813 in the direction of the drawdown and is expressed in gloss units (GU).

[0130] Preparation of formulations

[0131]

[0053] Unless otherwise specified, each of the formulations described were prepared by a conventional method by using a 50 ml mixing cup suitable for use with a Speedmixer™. The components, adding up to around 10 g in total, were added in the mixing cup. The cup was then closed and vigorously mixed in a Speedmixer™ DAC150FVZ for 5 minutes, stopped, and mixed again for 5 additional minutes via the same method.

[0132] Formulations 1.1, 1.2, 1.3, l. A, and l. B

[0133]

[0054] 80 parts of the oligomers prepared as described above (Examples 1-3 and Comparative Examples A and B) were mixed with 20 parts dipropyleneglycol diacrylate and 5 parts Omnirad 1173 to obtain formulations 1.1, 1.2, 1.3, l. A, and l. B.

[0134]

[0055] Of the oligomers of Examples 1-3 and of the oligomers of Comparative Examples A and B, the Mn, Mwand the neat viscosity were determined. Also the viscosity of the formulations prepared with these oligomers was determined. The results are presented in Table 1. 2024PF30127fc 14

[0135] Table 1

[0136] Mn(kg / mol) Mw(kg / mol) Neat viscosity Viscosity of (mPa.s) formulation Example 1 3.3 7.2 2500 602 Example 2 5.1 16.9 10460 2006 Example 3 5.3 41.1 83380 10720

[0137] Comparative 0.72 1.3 72420 3389 Example A

[0138] Comparative 1.1 4.9 24870 (20% 15210* Example B DPGDA)

[0139]

[0140] * the oligomer already contains 20wt% DPGDA

[0141]

[0056] A comparison between Example 1 and Comparative Example A, as well as between Example 3 and Comparative Example B, demonstrates that the urethane acrylate oligomers of the present invention exhibit a surprisingly lower viscosity despite having a significantly higher molecular weight. This unexpected property is observed both in the neat oligomer state and in formulated compositions.

[0142] Preparation of low gloss films applying Excimer cure

[0143] Formulations 2.1, 2.2, 2.3, 2. A, and 2. B

[0144]

[0057] 48 parts of the oligomers prepared as described above (Examples 1-3 and Comparative Examples A and B) were mixed with ethoxylated pentaerythritol tetraacrylate (EO5), 3.5 parts Acemat OK607 and 0.5 parts Omnirad 1173 to obtain formulations 2.1, 2.2, 2.3, 2. A, and 2. B.

[0145]

[0058] The formulations 2.1, 2.2, 2.3, 2. A, and 2. B were applied as 12 micron thick films on a Leneta card and cured using a 172nm eximer lamp (7mJ / cm2, Ushio Inc. Excimer - Light Emission System) followed by a mercury bulb (350 mJ / cm2). The gloss and the flexibility of the cured films were measured. The results are shown in Table 2. 2024PF30127fc 15

[0146] Table 2

[0147] Formulation 2.1 2.2 2. A 2.4 2. B Oligomer Ex 1 Ex 2 Comp A Ex 3 Comp B Idealized SorPO24EO8Ac5- SorPO24EO8Ac5-IPDI- PentaAcs- SorPO24EO8Ac5-IPDI- PentaAc3- IPDI-SorPO24EO8Ac5SorPO24EO8Ac5(1:1 IPDI- pTHF650-IPDI- IPDI- structure (1:0.6 ratio) ratio) PentaAc3SorPO24EO8Ac5pTHF650- IPDI- PentaAc3Gloss black 0.3 0.2 1.52 0.2 0.3 20°

[0148] Gloss black 3.7 3 11.6 2.7 3.5 60°

[0149] Gloss black 6.3 3.8 18.4 3.3 5.5 85°

[0150] Gloss white 1.5 1.4 2.4 1.4 1.5 20°

[0151] Gloss white 5.6 4.6 11.7 4.4 5.5 60°

[0152] Gloss white 7.0 3.7 17.9 3.2 6.8 85°

[0153] Flexibility ~10 mm 16mm >32mm 16mm >32mm (Mandrel

[0154] bend)

[0155]

[0156]

[0059] A comparative analysis of Examples 1 and 2 with Comparative Experiment A, and Example 3 with Comparative Experiment B, clearly demonstrates that employing the urethane acrylates of the present invention results in a lower gloss finish. Moreover, these examples and their respective comparatives show that the urethane acrylates of the present invention yield significantly higher flexibility. This outcome is particularly noteworthy given the high functionality of these oligomers, i.e., 10 functional groups, compared to 6 functional groups in the comparative examples. Conventionally, higher functionality would be expected to result in reduced flexibility.

Claims

2024PF30127fc 16What is claimed is:

1. A radiation curable composition, characterized in that the composition comprises at least one urethane acrylate according to formula (I):whereinRi represents a residue of a polyisocyanate;R2 represents a residue of a polyol;the sum of n1to n12is from 16 to 100;the sum of m1to m12is from 6 to 60;the sum of n1to n12is greater than the sum of m1to m12; ando is from O to 3.

2. The composition according to claim 1, characterized in that the sum of n1to n12is equal to or greater than 20, preferably equal to or greater than 30, and preferably equal to or smaller than 90, more preferably equal to or smaller than 80.

3. The composition according to claim 1 or 2, characterized in that the sum of m1to m12is equal to or greater than 12, and preferably equal to or smaller than 20.

4. The composition according to any of the preceding claims, characterized in that o is 0 (zero) or 1.

5. The composition according to any of the preceding claims, characterized in that Ri is the residue of a diisocyanate, preferably said diisocyanate is independently selected from the group consisting of pentane diisocyanate (PDI), hexane diisocyanate (HDI), isophorone diisocyanate (IPDI), and di cy cl ohexylmethane-4, 4’ -diisocyanate (H MDI).

6. The composition according to any of the preceding claims, characterized in that R2 is the residue of a polyol which is independently selected from the group consisting of polyether polyols, polyester polyols, and polycarbonate polyols, preferably R2 is the residue of a polyol which is independently selected from the group consisting of polyether polyols and polyester polyols, more preferably R2 is the residue of one or more polyether polyols.2024PF30127fc 177. The composition according to any of the preceding claims, characterized in that the polyol has a number average molecular weight Mn, determined with the method as described in the description, of from 500 to 2500 g / mol.

8. The composition according to any of the preceding claims, characterized in that the polyol is a diol.

9. The composition according to any of the preceding claims, characterized in that R2 is the residue of at least one polypropylene glycol (PPG) and / or at least one polytetrahydrofuran (pTHF).

10. The composition according to any of the preceding claims, characterized in that the urethane acrylate according to formula (I) has a theoretical molar mass in the range of from 4000 to 7000 g / mol, preferably from 4500 to 6500 g / mol, more preferably from 4500 to 6000 g / mol.

11. The composition according to any of the preceding claims, characterized in that the sum of m1, m2, m3, m4, m5, m6, m7, m8, m9, m10, m11, m12, n1, n2, n3, n4, n5, n6, n7, n8, n9, n10, n11, and n12is equal to or greater than 30, preferably equal to or greater than 40.

12. The composition according to any of the preceding claims, characterized in that the sum of m1, m2, m3, m4, m5, m6, m7, m8, m9, m10, m11, m12, n1, n2, n3, n4, n5, n6, n7, n8, n9, n10, n11, and n12is equal to or smaller than 100, preferably equal to or smaller than 90, more preferably equal to or smaller than 80.

13. The composition according to any of the preceding claims, characterized in that the one or more urethane acrylates according to formula (I) are present in an amount of at least 5% by weight and of at most 85% by weight, or at least 10% by weight and at most 80% by weight, or at least 25% by weight and at most 80% by weight, or at least 35% by weight and at most 75% by weight, or at least 40% by weight and at most 70% by weight, or at least 40% by weight and at most 65% by weight, or at least 40% by weight and at most 60% by weight, relative to the weight of the entire composition.

14. The composition according to any of the preceding claims, characterized in that the composition further comprises one or more radiation curable acrylate functional diluents with an acrylate functionality of from 2 to 6.

15. The composition according to claim 14, characterized in that the composition further comprises one or more radiation curable acrylate functional diluents having a molar mass of less than 750 g / mol.

16. The composition according to any of the preceding claims 1 to 12 or 14 or 15, characterized in that the composition comprises2024PF30127fc 18(A) from 10 to 70% by weight of one or more urethane acrylate according to formula (I),(B) from 15 to 80% by weight of one or more radiation curable diluent, and(C) from 0.5 to 10% by weight of one or more photoinitiator,wherein the amounts are given relative to the weight of the entire composition.

17. The composition according to any of the preceding claims, wherein the radiation-curable composition is 100% radiation curable.

18. The composition according to any of the preceding claims, wherein the radiation curable composition is a coating or ink composition.

19. An urethane acrylate according to formula (I) as defined in any of claims 1 to 12.

20. An article comprising a substrate at least partially coated with a coating or ink obtained by radical curing of the coating or ink composition of claim 18.

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