Sugar alcohol-based reactive diluents and their use

Abstract

The present invention relates to oligomers (A) according to formula (I) RCH2(CHR)nCH2R (I), wherein n is 3 or 4; and each R is independently selected from, wherein represents a point of attachment, and wherein (3) at least one p is greater than 0, at least one t is greater than 0, and the sum of all the p's is greater than the sum of all the t's, and (4) each X is independently selected from or, with the proviso that, in case n is 3 at least 3 X's are, and in case n is 4 at least 4 X's are.

Description

[0001] 2024PF30088fc 1

[0002] SUGAR ALCOHOL-BASED REACTIVE DILUENTS AND THEIR USE

[0003] Field of the invention

[0004]

[0001] The present invention relates to certain sugar alcohol -derived oligomers suitable for use as radiation-curable diluent in radiation-curable compositions, the radiation-curable compositions, and the use of such oligomers as radiation-curable diluent in radiation-curable compositions.

[0005] Background

[0006]

[0002] Nowadays coatings are used every day. Examples are items like coatings for transparent food packages, thin foils, paints, and car part finishes. 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] Reactive diluents are used in a wide variety of UV-curing systems for applications including but not limited to a variety of coatings, paints, adhesives, and 3D printing. With reactive diluent (also referred to as radiation-curable diluent) is meant a compound being able to reduce the viscosity of the formulation while being able to free radically copolymerize. In addition to reducing the viscosity of the composition or resin with which such diluents are associated, they should be reactive in the sense that they contribute to polymerization and / or cross-linking reactions that occur after their associated composition or resin is subjected to actinic radiation of a sufficient wavelength and intensity. Furthermore, depending on the intended end-use application, such diluents must be fast-curing and be able to impart or contribute to the formation of desired physical properties in the object or coating cured therefrom. Yet other selection criteria include volatility and compatibility in the accompanying composition or resin. Of course, it is desired that such diluents are capable of being produced in a cost-effective manner on an industrial scale as well.

[0008]

[0004] Reactive diluents based upon a number of different chemical genera exist, including those based on styrenes, epoxides, and acrylics, to name a few. Acrylic-based reactive diluents, such as acrylates or methacrylates, are useful in a plethora of applications given their versatility in creating objects with a wide range of physical properties. Such acrylates and methacrylates 2024PF30088fc 2 are also typically highly reactive, and are known to form cured products having the desired endstate properties in a relatively short period of time. For that reason, they are used in UV-curing applications where rapid network build-up is of paramount importance, such as in 3D printing applications or processes for coating optical fibers. Acrylates are described in, Acrylate Polymers for Advanced Applications, edited by Angel Serrano-Aroca, Published: May 6th 2020, ISBN: 978-1-78985-184-7 (and in particular, the chapter titled “Properties and Applications of Acrylates” by Kingsley Kema Ajekwene).

[0009]

[0005] Although versatile and fast-curing, most commonly 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]

[0006] 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]

[0007] Thus, there exists a desire for alternative reactive diluents with a more benign cytotoxic profile. This might be achievable by increasing the molecular weight, as acrylates with a molecular weight above 1000 Dalton are generally considered to be safe and / or by increasing the functionality, i.e., reducing the risk of being extracted. Generally, however, by increasing the molecular weight, the viscosity increases making them less suitable as reactive diluents.

[0012] Increasing the functionality has a similar effect. Moreover, increasing the functionality normally reduces the flexibility significantly and for many applications flexible cured materials are needed. Next to this a lower water sensitivity, as indicated by the water absorption, is preferred as that would minimize the risks for the aquatic environment. Furthermore, for an efficient process the reactive diluents should be fast curing.

[0013]

[0008] Thus, there exists a heretofore unmet need for the provision of reactive diluents suitable for use in radiation-curable compositions which simultaneously possess relatively high functionality (>3), low viscosity and fast curing properties and which yield, upon curing, flexible layers with low water absorption.

[0014] Summary of the invention

[0015]

[0009] The invention relates to an oligomer (A), suitable for use as radiation-curable diluent in a radiation-curable composition, according to the following formula (I): 2024PF30088fc 3

[0016] RCH2(CHR)nCH2R (I); wherein n is 3 or 4, and each R is independently selected from, wherein represents a point of attachment, and wherein

[0017] (1) at least one p is greater than 0, at least one t is greater than 0, and the sum of all the p’s is greater than the sum of all the t’ s, and

[0018] O

[0019] (2) each X is independently selected from with the proviso that, in

[0020]

[0010] The invention further relates to an oligomer (A), suitable for use as radiation-curable diluent in a radiation-curable composition, according to the following formula (II): wherein

[0021] Xi, X2, X3, X4, X5 and Xe are independently selected from , with the proviso that at least 4 of Xi, X2, X3, X4, X5, and Xe are , wherein represents a point of attachment; the sum of mi to me is greater than 0; the sum of m to ne is greater than 0; and the sum of m to ne is greater than the sum of mi to me.

[0022] [OH] The invention further relates to a radiation-curable composition comprising at least one of such an oligomer (A), particularly to a radiation-curable ink or coating composition comprising such a radiation-curable composition. 2024PF30088fc 4

[0023]

[0012] The invention further relates to the use of such an oligomer (A) as radiation-curable diluent in a radiation-curable composition.

[0024] Detailed Description of the invention

[0025]

[0013] 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.

[0026]

[0014] 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.

[0027]

[0015] The present invention is directed to an oligomer (A), suitable for use as radiation-curable diluent in a radiation-curable composition, of the following formula (I): RCH2(CHR)nCH2R (I), wherein n is 3 or 4, and each R is independently selected from k(OCH2CH(CH3))p(OCH2CH2)tX , wherein represents a point of attachment, and wherein

[0028] (1) at least one p is greater than 0, at least one t is greater than 0, and the sum of all the p’s is greater than the sum of all the t’ s, and

[0029] O

[0030] (2) each X is independently selected from from sH0HOr , with the proviso that,

[0031]

[0016] Preferably n is 4.

[0032]

[0017] The present invention is preferably directed to an oligomer (A), suitable for use as radiation-curable diluent in a radiation-curable composition, of the following formula (II): 2024PF30088fc 5 wherein

[0033] O

[0034] Xi, X2, X3, X4, X5 and Xe are independently selected from °Hor with the proviso that at least 4 of Xi, X2, X3, X4, X5, and Xe are wherein5represents a point of attachment; the sum of mi to me is greater than 0; the sum of to ne is greater than 0; and the sum of to ne is greater than the sum of mi to me.

[0035]

[0018] It has surprisingly been found that the oligomers (A) according to the invention are capable to effectively function as diluent (i.e., significantly reducing the viscosity of the composition or resin to which they are added), despite their relatively high molar mass, exhibit rapid curing characteristics, i.e., are able to impart a rapid modulus buildup into the cured product(s) created therefrom. An additional advantage of the oligomers (A) according to the invention is that they can produce, upon curing, flexible layers with low water absorption.

[0036]

[0019] The present invention is also directed to a radiation-curable composition comprising at least one oligomer (A) according to formula (I). Preferably, the radiation-curable composition comprises at least one oligomer (A) according to the following formula (II): wherein 2024PF30088fc 6

[0037] O

[0038] Xi, X2, X3, X4, X5 and Xe are independently selected from fOHor with the proviso that at least 4 of Xi, X2, X3, X4, X5, and Xe are wherein5represents a point of attachment; the sum of mi to me is greater than 0; the sum of m to ne is greater than 0; and the sum of m to ne is greater than the sum of mi to me.

[0039]

[0020] The present invention is also directed to a radiation-curable composition comprising at least one oligomer (A) according to formula (II).

[0040]

[0021] It has surprisingly been found that radiation-curable compositions as described in the claims and disclosed in the specification are suitable for application as binders in radiation curable coatings or inks. The radiation curable-compositions as described in the claims and disclosed in the specification can afford, upon curing, flexible layers with low water absorption.

[0022] The invention therefore further relates to a radiation-curable coating or ink composition comprising such a radiation-curable composition.

[0041]

[0023] The invention further also relates to the use of an oligomer (A) according to formula (I) as radiation-curable diluent in a radiation-curable composition. Preferably, the oligomer (A) is according to formula (II): wherein

[0042] O

[0043] Xi, X2, X3, X4, X5 and Xe are independently selected from f°Hor with the proviso that at least 4 of Xi, X2, X3, X4, X5, and Xe are wherein5represents a point of attachment; the sum of mi to me is greater than 0; the sum of to ne is greater than 0; and the sum of to ne is greater than the sum of mi to me. 2024PF30088fc 7

[0044]

[0024] The invention further also relates to the use of an oligomer (A) according to formula (II) as radiation-curable diluent in a radiation-curable composition.

[0045]

[0025] US 11046813B2 is directed to agrochemical formulations comprising an agricultural active and an adjuvant. The adjuvant comprises a residue of sorbitan or sorbitan derivative having ate least one active hydrogen atom replaced to form an ethyloxylated or propoxylated ester. US 9102791B2 discloses alkoxylated sorbitan ester compounds useful in emulsion breaking applications relating to the production, transportation, storage, and separation of crude oil and natural gas. US 2010 / 261863 Al discloses multibranched polyoxyalkylene compounds having one functional group X capable of reacting with an amino group, a mercapto group, an aldehyde group, a carboxyl group, a triple bond, or an azide group to form a chemical bond. US 10633406B1 describes batch water processes for producing high functionality polyether polyols from polyhydroxyl compounds that are solid at ambient conditions, such as sorbitol.

[0046] Oligomeric reactive diluent

[0047]

[0026] The oligomer (A) as described in the claims and disclosed in the specification preferably has a structure according to formula (II) as shown above.

[0048]

[0027] The oligomers (A) according to the invention preferably have a theoretical molar mass of at least 1000 g / mol, more preferably at least 1200 g / mol, even more preferably at least 1400 g / mol, even more preferably at least 1500 g / mol, even more preferably at least 1750 g / mol. The oligomers (A) according to the invention preferably have a theoretical molar mass of at most 5000 g / mol, more preferably of at most 4500 g / mol, and even more preferably of at most 4000 g / mol. The oligomers (A) according to the invention preferably have a theoretical molar mass in the range of from 1000 to 5000 g / mol, more preferably from 1500 to 4500 g / mol, and even more preferably from 1750 to 4000 g / mol. The theoretical molar mass of the oligomer (A) is the calculated molar mass obtained by adding the atomic masses of all atoms present in the idealized chemical formula of the oligomer (A).

[0049]

[0028] Preferably, the sum of to ne is greater than 8. Preferably, the sum of m to ne is less than 50, more preferably less than 45, more preferably less than 40.

[0050]

[0029] Preferably, the sum of mi to me is greater than 6. Preferably, the sum of mi to me is less than 30, more preferably less than 20.

[0051]

[0030] The sum of mi, m2, m3, nu, me, me, ni, n2, ns, , ns, and ne is preferably less than 50, more preferably less 40.

[0052]

[0031] The oligomers (A) according to the invention preferably have a hydroxyl value of less than or equal to 75 mg KOH / g, more preferably less than or equal to 60 mg KOH / g, even more preferably less than or equal to 50 mg KOH / g, and even more preferably less than or equal to 50 2024PF30088fc 8 mg KOH / g, whereby the hydroxyl value is determined titrimetrically according to ISO 4629: 1- 2016.

[0053]

[0032] The oligomers (A) according to the invention preferably have a theoretical molar mass per acrylate group of at least 225 g / mol, more preferably of at least 250 g / mol, even more preferably of at least 275 g / mol, and even more preferably of at least 300 g / mol. The oligomers (A) according to the invention preferably have a theoretical molar mass per acrylate group of at most 900 g / mol, more preferably of at most 800 g / mol, even more preferably of at most 700 g / mol.

[0054]

[0033] The oligomers (A) according to the invention can be prepared by using a five-hydroxy functional (when n=3) or a hexa-hydroxy functional core (when n=4), preferably the hexahydroxy functional core is 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 five-hydroxy functional oligomers or hexa-hydroxy functional oligomers can subsequently be esterified using well known procedures like for example acid catalyzed using azeotropic conditions.

[0055] Radiation-curable composition

[0056]

[0034] The radiation-curable composition of the present invention comprises at least one oligomer (A) according to the present invention in an amount of preferably at least 1% by weight, or 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, and in an amount of preferably 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.

[0035] The radiation-curable composition of the present invention preferably further comprises:

[0057] (i) one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups, preferably having one or more (meth)acryol or vinyl groups, and

[0058] (ii) one or more photoinitiators,

[0059] (iii) optionally, one or more additives.

[0060]

[0036] The one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups preferably have a number-average molecular weight (Mn) equal to or higher than 800 g / mol, more preferably equal to or higher than 1000 g / mol; and preferably lower than or equal to 15000 g / mol, more preferably lower than or equal to 5000 g / mol, whereby the number-average molecular weight Mnis determined as described herein below. 2024PF30088fc 9

[0061]

[0037] The one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups are preferably present in the radiation-curable composition in an amount of from 10% by weight to 85% by weight, preferably from 15 to 75% by weight, more particularly from 20 to 70% by weight, relative to the entire weight of the radiation-curable composition.

[0038] Preferably the radiation-curable oligomers (B) are selected from the group consisting of urethane (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates and any mixture thereof. More preferably the radiation-curable oligomers are selected from the group consisting of urethane acrylates, epoxy acrylates, polyester acrylates, and any mixture thereof. Even more preferably the one or more oligomers having one or more radiation-curable ethylenically unsaturated groups are urethane acrylate oligomers.

[0062]

[0039] The (meth)acrylate-functionalized oligomer may be selected in order to enhance the flexibility, strength and / or modulus, among other attributes, of a cured polymer prepared using the radiation-curable composition of the present invention. The (meth)acrylate functionalized oligomer may have 1 to 18 (meth)acrylate groups, in particular 2 to 6 (meth)acrylate groups, more particularly 2 to 6 acrylate groups. The (meth)acrylate functionalized oligomer may have a number-average molecular weight equal of more than 800 g / mol, in particular from 800 to 15000 g / mol, more particularly from 1000 to 5000 g / mol. In particular, the (meth)acrylate- functionalized oligomers may be selected from the group consisting of (meth)acrylate- functionalized urethane oligomers (sometimes also referred to as "urethane (meth)acrylate oligomers," "polyurethane (meth)acrylate oligomers" or "carbamate (meth)acrylate oligomers"), (meth)acrylate-functionalized epoxy oligomers (sometimes also referred to as "epoxy (meth)acrylate oligomers"), (meth)acrylate-functionalized polyether oligomers (sometimes also referred to as "polyether (meth)acrylate oligomers"), (meth)acrylate-functionalized polydiene oligomers (sometimes also referred to as "polydiene (meth)acrylate oligomers"), (meth)acrylate- functionalized polycarbonate oligomers (sometimes also referred to as "polycarbonate (meth)acrylate oligomers"), and (meth)acrylate-functionalized polyester oligomers (sometimes also referred to as "polyester (meth)acrylate oligomers"), acrylic (meth)acrylate oligomers and mixtures thereof. Preferably, the (meth)acrylate-functionalized oligomer comprises a (meth)acrylate-functionalized urethane oligomer, more preferably an acrylate-functionalized urethane oligomer. Advantageously, the (meth)acrylate-functionalized oligomer comprises a (meth)acrylate-functionalized urethane oligomer having two (meth)acrylate groups, more preferably an acrylate-functionalized urethane oligomer having two acrylate groups.

[0063]

[0040] Exemplary polyester (meth)acrylate oligomers include the reaction products of acrylic or methacrylic acid or mixtures or synthetic equivalents thereof with hydroxyl group-terminated polyester polyols. The reaction process may be conducted such that all or essentially all of the 2024PF30088fc 10 hydroxyl groups of the polyester polyol have been (meth)acrylated, particularly in cases where the polyester polyol is difunctional. The polyester polyols can be made by polycondensation reactions of polyhydroxyl functional components (in particular, diols) and polycarboxylic acid functional compounds (in particular, dicarboxylic acids and anhydrides). The polyhydroxyl functional and polycarboxylic acid functional components can each have linear, branched, cycloaliphatic or aromatic structures and can be used individually or as mixtures.

[0064]

[0041] Examples of suitable epoxy (meth)acrylate oligomers include the reaction products of acrylic or methacrylic acid or mixtures thereof with an epoxy resin (polyglycidyl ether or ester). The epoxy resin may, in particular, by selected from bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol 6 diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, epoxy novolak resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3, 4-epoxy cyclohexylmethyl 3',4’epoxycyclohexanecarboxylate, 2-(3,4- epoxycyclohexyl-5,5-spire-3,4-epoxy)cyclohexane-l,4- dioxane, bis(3,4- epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide, 4-vinylepoxy cyclohexane, bis(3,4- epoxy-6-methylcyclohexylmethyl)adipate,3,4-epoxy-6-methylcyclohexy l-3',4uepoxy-6u methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di (3, 4-epoxy cyclohexylmethyl) ether of ethylene glycol, ethylenebis(3, 4- epoxy cyclohexanecarboxylate), 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyglycidyl ethers of a polyether polyol obtained by the addition of one or more alkylene oxides to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol, and glycerol, diglycidyl esters of aliphatic long-chain dibasic acids, monoglycidyl ethers of aliphatic higher alcohols, monoglycidyl ethers of phenol, cresol, butyl phenol, or polyether alcohols obtained by the addition of alkylene oxide to these compounds, glycidyl esters of higher fatty acids, epoxidized soybean oil, epoxybutylstearic acid, epoxy octyl stearic acid, epoxidized linseed oil, epoxidized polybutadiene, and the like.

[0065]

[0042] Suitable polyether (meth)acrylate oligomers include, but are not limited to, the condensation reaction products of acrylic or methacrylic acid or synthetic equivalents or mixtures thereof with polyetherols which are polyether polyols (such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol). Suitable polyetherols can be linear or branched substances containing ether bonds and terminal hydroxyl groups. Polyetherols can be prepared by ring opening polymerization of cyclic ethers such as tetrahydrofuran or alkylene oxides (e.g., ethylene oxide and / or propylene oxide) with a starter molecule. Suitable starter molecules include water, polyhydroxyl functional materials, polyester polyols and amines. 2024PF30088fc 11

[0066]

[0043] Polyurethane (meth)acrylate oligomers (sometimes also referred to as "urethane (meth)acrylate oligomers") suitable for use in the radiation-curable compositions of the present invention include urethanes based on aliphatic, cycloaliphatic and / or aromatic polyester polyols and polyether polyols and aliphatic, cycloaliphatic and / or aromatic diisocyanates and capped with (meth)acrylate end-groups. Suitable polyurethane (meth)acrylate oligomers include, for example, aliphatic polyester-based urethane di- and tetra-acrylate oligomers, aliphatic polyether- based urethane di- and tetra-acrylate oligomers, as well as aliphatic polyester / polyether-based urethane di- and tetraacrylate oligomers. The polyurethane (meth)acrylate oligomers may be prepared by reacting aliphatic, cycloaliphatic and / or aromatic polyisocyanates (e.g., diisocyanate, triisocyanate) with OH group terminated polyester polyols, poly ether polyols, polycarbonate polyols, polycaprolactone polyols, polyorganosiloxane polyols (e.g., polydimethylsiloxane polyols), or polydiene polyols (e.g., polybutadiene polyols), or combinations thereof to form isocyanate-functionalized oligomers which are then reacted with hydroxyl-functionalized (meth)acrylates such as hydroxyethyl acrylate or hydroxyethyl methacrylate to provide terminal (meth)acrylate groups. For example, the polyurethane (meth)acrylate oligomers may contain two, three, four or more (meth)acrylate functional groups per molecule. Other orders of addition may also be practiced preparing the polyurethane (meth)acrylate, as is known in the art. For example, the hydroxyl-functionalized (meth)acrylate may be first reacted with a polyisocyanate to obtain an isocyanate-functionalized (meth)acrylate, which may then be reacted with an OH group terminated polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polydimethysiloxane polyol, polybutadiene polyol, or a combination thereof. In yet another embodiment, a polyisocyanate may be first reacted with a polyol, including any of the aforementioned types of polyols, to obtain an isocyanate-functionalized polyol, which is thereafter reacted with a hydroxyl-functionalized (meth)acrylate to yield a polyurethane (meth)acrylate Alternatively, all the components may be combined and reacted at the same time.

[0067]

[0044] Suitable acrylic (meth)acrylate oligomers (sometimes also referred to in the art as "acrylic oligomers") include oligomers which may be described as substances having an oligomeric acrylic backbone which is functionalized with one or (meth)acrylate groups (which may be at a terminus of the oligomer or pendant to the acrylic backbone). The acrylic backbone may be a homopolymer, random copolymer or block copolymer comprised of repeating units of acrylic monomers. The acrylic monomers may be any monomeric (meth)acrylate such as Ci-Ce alkyl (meth)acrylates as well as functionalized (meth)acrylates such as (meth)acrylates bearing hydroxyl, carboxylic acid and / or epoxy groups. Acrylic (meth)acrylate oligomers may be prepared using any procedures known in the art, such as by oligomerizing monomers, at least a 2024PF30088fc 12 portion of which are functionalized with hydroxyl, carboxylic acid and / or epoxy groups (e.g., hydroxyalkyl(meth)acrylates, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized oligomer intermediate, which is then reacted with one or more (meth)acrylate containing reactants to introduce the desired (meth)acrylate functional groups.

[0068]

[0045] The radiation-curable composition of the invention may comprise from 10 to 80% by weight, in particular from 15 to 75% by weight, more particularly from 20 to 70% by weight (meth)acrylate-functionalized oligomer (B), relative to the entire weight of the radiation-curable composition.

[0069]

[0046] The weight ratio of the oligomers (A) to the oligomers (B) in the composition preferably ranges from 0.1 : 1 to 10: 1. More preferably, this ratio is from 0.15: 1 to 8: 1, and even more preferably from 0.2: 1 to 6: 1.

[0070]

[0047] 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.

[0071]

[0048] 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 0.25 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.

[0072]

[0049] 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.

[0073]

[0050] 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.

[0074]

[0051] 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 2024PF30088fc 13 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.

[0075]

[0052] 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.

[0076] Examples

[0077] Determination of viscosity

[0078]

[0053] 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.

[0079] Determination of molecular weight by GPC

[0080]

[0054] 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 xlO6g / 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.

[0081] More specifically, 50 mg of oligomeric reactive diluent (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.

[0082] 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 Ed = 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= IxlO'6m), (supplied by Waters), iii) a Waters 2707 2024PF30088fc 14

[0083] Autosampler - injection system and iv) a Waters 1515 -Isocratic HPLC pump. The Mnand Mwwere determined by the use of Empower 3 software from Waters.

[0084] Dynamic mechanical thermal analysis (DMT A)

[0085]

[0055] For DMT A, formulations were prepared using 95 parts of the various oligomeric reactive diluents (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-l-[4-(methylthio)phenyl]-2-morpholinopropan-l-one, CAS NO. 71868-10-5, obtained from IGM Resins). Films were prepared and cured using a Fusion UV Rig equipped with a Fusion F600 H bulb employing a total dose of 2 J7cm2. A 20 mm by 7 mm specimen of these films were analyzed using a PerkinElmer DMA8000 to determine cured film modulus and glass transition temperature Tg.

[0086] Determination of reactivity using RT-DMA: Maximum Modulus (GJ and T30%, modulus max values

[0087]

[0056] For RT-DMA, formulations were prepared using 95 parts of the various oligomeric reactive diluents (as described below), 4.5 parts Omnirad 1173 and 0.5 part Omnirad 907. These formulations were analyzed on a TA instruments Rheometer (HR20) equipped with UV curing accessories (320-500 nm, OmniCure® Series 2000). The UV output intensities were calibrated at the sample position using an external radiometer. For the light guide accessory, the intensity (25_mW / cm2) was applied and recorded as total intensity without any filter. Thickness of the sample was 0.25 mm and a single frequency oscillatory measurement was carried out under a control strain of 1% at 5 Hz. Dynamic time sweep experiments were used to monitor the curing process.

[0088] Illumination started after 60 sec of measuring. Reported herein are the maximum modulus and the time to reach 30% of the maximum modulus after start of illumination as measure of cure speed.

[0089]

[0057] The shrinkage was determined on these specimens as well, i.e., shrinkage = (thickness before curing - thickness after curing) / thickness before curing.

[0090] Water absorption test

[0091]

[0058] For the water absorption test, formulations were prepared using 38 parts NeoRad™ U-25 (urethane acrylate with a theoretical molar mass of 1300 g / mol and a theoretical functionality of 2, obtained from Covestro), 57 parts of the various (oligomeric) reactive diluents (as described below) and 5 parts of Omnirad 1173. Films were prepared and cured using a Fusion UV Rig equipped with a Fusion F600 H bulb employing a total dose of 2 J / cm2. Next, 4 g of these films were immersed in boiling water for 2 hours. Next the films were taken out, dried and cooled 2024PF30088fc 15 down for 2 hours at room temperature and 50% relative humidity after which the weight was determined again.

[0092] Mandrel bend test

[0093]

[0059] Formulations were prepared using 95 parts of the various oligomeric reactive diluents (as described below), 4.5 parts of Omnirad 1173 (2 -hydroxy -2 -m ethyl- 1 -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 1519:2011 using TQC Sheen Cylindrical Mandrel Bend Tester.

[0094] Pencil hardness

[0095]

[0060] Formulations were prepared using 95 parts of the various oligomeric reactive diluents (as described below), 4.5 parts of Omnirad 1173 (2 -hydroxy -2 -m ethyl- 1 -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 ABS sheet and cured using a Fusion UV Rig equipped with a Fusion F600 H bulb employing a total dose of 1 J / cm2. Th cured films were tested according to ISO 15184: 2020 using an Elcometer 501 Pencil hardness tester set. The pencils varying in lead hardness from 6B (softest) through 6H (hardest) are pushed into the film, and the hardest pencil that will not penetrate the film is noted.

[0096] Hydroxyl and acid value

[0097]

[0061] The acid and hydroxyl value were determined titrimetrically according to ISO 2114-2000 and ISO 4629: 1-2016, respectively.

[0098] Synthesis of oligomeric reactive diluents Typical alkoxylation procedure: Synthesis of SorP M- dMIH,

[0099]

[0062] 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 2024PF30088fc 16 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), oligomer with the idealized structure SorPC^EOsOEfc was obtained as a clear product with a viscosity of 843 mPa.s.

[0100]

[0063] In a similar way oligomers with the idealized structure SorPO24OHe, SorECEoOHe, GPO24EO8OH6, DPE(EO)24OHe, DPE(EO)i3OHe were prepared using sorbitol (Sor), glycerol (G) and dipentaerythritol (DPE) as starter molecules.

[0101] Typical esterification procedure: Synthesis ofSorlT^ldTAe

[0102]

[0064] A 500 ml reactor equipped with a stirrer, nitrogen inlet, and Dean-Stark set-up was charged with 96.3 g (0.05mol) SorPC^EOsOEE obtained as described above, 21.6 g (0.3mol) 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 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 SorPC^ECEAe.

[0103]

[0065] The oligomeric reactive diluents of Example 2 and Comparative Experiments C5-11 were prepared in a similar way employing the appropriate acrylate stoichiometries using the alkoxylated sorbitol (Sor), glycerol (G) and dipentaerythritol (DPE) prepared as described above.

[0104] Preparation of formulations

[0105]

[0066] 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. 2024PF30088fc 17

[0106] Table 1: Theoretical molar mass and viscosity of oligomeric reactive diluents according to the invention and of commercially available, low molecular weight multifunctional reactive diluents.

[0107]

[0067] Table 1 shows that the multifunctional acrylate oligomers (A) according to the invention surprisingly have a low viscosity despite having a significant higher molecular weight compared to commercially available, low molecular weight multifunctional acrylate oligomers.

[0108] 2024PF30088fc 18

[0109] Table 2: Characterization of various oligomeric reactive diluents

[0110] 2024PF30088fc 19

[0111]

[0068] For further reference, when utilizing propoxylated (PO3) glycerol triacrylate (GPO3A3), the water absorption of the formulation was measured at 1.71%. This results further demonstrates that the water absorption of formulations employing reactive diluents according to the invention is surprisingly low.

[0112]

[0069] A comparison of Example 1 with Comparative Example 5, and of Example 2 with Comparative Example 6, show that the oligomeric reactive diluents (A) according to the invention exhibit both faster curing rates and lower water absorption. The reduced water absorption is particularly noteworthy, considering that ethoxylation typically results in increased water sensitivity. Moreover, the accelerated curing speed is unexpected, as higher molecular weight compounds generally lead to decreased cure rates. This is also shown by the comparison of Example 1 with Comparative Example 9.

[0113]

[0070] A comparative analysis of Example 1 and Comparative Example 7 against Comparative Example 10 and Comparative Example 11 demonstrates that the use of the hexafunctional core as utilized in the present invention, i.e., sorbitol, yields an unexpected increase in flexibility. This enhanced flexibility is evidenced by the results of the Mandrel test.

[0114]

[0071] A comparative analysis of Example 1 versus Comparative Example 7, and Example 2 versus Comparative Example 8, clearly demonstrates the superior performance of the oligomeric reactive diluents (A) according to the present invention. Specifically, these comparisons reveal a significant reduction in shrinkage when utilizing the inventive oligomeric reactive diluents (A).

[0115] Example 3 and Comparative Example 12

[0116]

[0072] A formulation (Example 3) was prepared using 30 parts Neorad™ U-25, 70 parts the hexafunctional oligomeric reactive diluent according to the invention (i.e., of Example 1) and 5 parts Omnirad 1173. This formulation was analyzed using RT-DMA and 30% of the maximum modulus was obtained in 1.6 seconds and the shrinkage was measured at 4.3%. A comparative formulation (Comparative Example 12) was made using dipentaerythritol hexaacrylate as hexafunctional reactive diluent being a well-known fast curing reactive diluent. For this formulation, achieving 30% of the maximum modulus required 1.9 seconds, and the shrinkage was measured at 10.4%.

[0117]

[0073] The comparison between Example 3 and Comparative Example 12 further demonstrates the superior performance of the oligomeric reactive diluents (A) according to the invention. Specifically, the inventive formulation exhibits faster curing rates and significantly lower shrinkage compared to the formulation using a conventional fast-curing reactive diluent

Claims

2024PF30088fc 20What is claimed is:

1. An oligomer (A) according to formula (I)RCH2(CHR)nCH2R (I), wherein n is 3 or 4; and each R is independently selected from (OCH2CH(CH3))p(OCH2CH2)tX , wherein represents a point of attachment, and wherein(1) at least one p is greater than 0, at least one t is greater than 0, and the sum of all the p’s is greater than the sum of all the t’s, andO(2) each X is independently selected from f°Horwith the proviso that, in case n is 3 at least 3 X’s areand in case n is 4 at least 4 X’s2. The oligomer according to claim 1, wherein the oligomer is according to formula (II)whereinXi, X2, X3, X4, X5 and Xe are independently selected fromwith the proviso that at least 4 of Xi, X2, X3, X4, X5, and Xe are, wherein represents a point of attachment; the sum of mi to me is greater than 0; the sum of m to ne is greater than 0; and2024PF30088fc 21 the sum of to ne is greater than the sum of mi to me.

3. The oligomer of claim 2, wherein the sum of m to ne is greater than 8 and less than 50, preferably less than 45, more preferably less than 40.

4. The oligomer according to claim 2 or 3, wherein the sum of mi to me is greater than 6 and less than 30, preferably less than 20.

5. The oligomer according to any one of claims 2 to 4, wherein the sum of mi, m2, m3, nu, ms, me, ni, n2, ns, , ns, and ne is less than 50, preferably less 40.

6. The oligomer according to any one of the preceding claims, wherein the oligomer has a hydroxyl value of less than or equal to 75 mg KOH / g, preferably less than or equal to 60 mg KOH / g, more preferably less than or equal to 50 mg KOH / g, whereby the hydroxyl value is determined titrimetrically according to ISO 4629: 1-2016.

7. The oligomer according to any one of the preceding claims, wherein the oligomer has a theoretical molar mass in the range of from 1000 to 5000 g / mol, preferably from 1500 to 4500 g / mol, more preferably from 1750 to 4000 g / mol.

8. The oligomer according to any one of the preceding claims, wherein the oligomer has a theoretical molar mass per acrylate group of at least 225 g / mol, preferably of at least 250 g / mol, more preferably of at least 275 g / mol, even more preferably of at least 300 g / mol, and the oligomer has a theoretical molar mass per acrylate group of at most 900 g / mol, preferably of at most 800 g / mol, more preferably of at most 700 g / mol.

9. A radiation-curable composition comprising at least one oligomer (A) according to any one of the preceding claims in an amount of at least 1% by weight, or 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, and 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.

10. The radiation-curable composition according to claim 9, wherein the radiation-curable composition further comprises:(a) one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups, preferably having one or more (meth)acryol or vinyl groups, and(b) one or more photoinitiators.

11. The radiation-curable composition according to claim 10, wherein the one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups are independently selected from urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether (meth)acrylate oligomers and epoxy (meth)acrylate oligomers,2024PF30088fc 22 more preferably the one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups are independently selected from urethane acrylate oligomers, polyester acrylate oligomers and epoxy acrylate oligomers, even more preferably the one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups are urethane acrylate oligomers.

12. The radiation-curable composition according to claim 10 or 11, wherein the one or more oligomers (B) having one or more radiation-curable ethylenically unsaturated groups are present in the radiation-curable composition in an amount of from 10% by weight to 85% by weight and the oligomers (A) according to any of claims 1-7 are present in the radiation-curable composition in an amount of from 5% by weight to 85% by weight, relative to the weight of the entire composition.

13. The radiation-curable composition according to any one of claims 10 to 12, wherein the weight ratio of the amount of the oligomers (A) according to any of claims 1-7 present in the radiation-curable composition to the amount of the oligomers (B) having one or more radiation-curable ethylenically unsaturated groups present in the radiation-curable composition is from 0.1:1 to 10:1, preferably from 0.15:1 to 8:1, more preferably from 0.2:1 to 6:1.

14. The radiation-curable composition according to any one of claims 9 to 13, wherein the radiation-curable composition is 100% radiation-curable.

15. The radiation-curable composition according to any one of claims 9 to 14, wherein the radiation-curable composition is a coating or ink composition.

16. Use of the oligomer (A) according to any one of claims 1 to 8 as radiation-curable diluent in radiation-curable compositions.

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