CN121889435A - Photoinitiator for photocurable compositions - Google Patents

Abstract

The present invention relates to a low light concentration initiating resin, wherein the low light concentration initiating resin comprises m end groups according to formula (I) and n end groups according to formula (II): Wherein m is equal to or greater than 1, n is equal to or greater than 2, m+n is equal to or greater than 4, R ₁ is hydrogen, straight chain C ₁-C₆ alkyl or branched C ₃-C₆ alkyl, X ₁、X₂、X₃、X₄ and X ₅ are independently selected from hydrogen, straight chain C ₁-C₆ alkyl, branched C ₃-C₆ alkyl, C ₅-C₇ cycloalkyl, phenyl, C ₁-C₄ alkoxy, C ₅-C₇ cycloalkoxy or phenoxy, or X ₁ and X ₂ together may form an aromatic ring, or X ₂ and X ₃ together may form an aromatic ring, and each symbol Represents a junction point, and wherein the low light condensation initiating resin has a weight average molecular weight M _w of greater than 1100 g/mol, whereby the weight average molecular weight Mw is determined as described in the specification.

Description

Photoinitiator for photocurable compositions

Technical Field

This invention relates to photoinitiating resins, which can be used as photoinitiators in radical-curable compositions, such as radical-curable coatings and ink compositions. The invention further relates to radical-curable compositions comprising such photoinitiating resins. Furthermore, the invention relates to objects coated with such radical-curable compositions.

background

Paints are used every day today. Examples include coatings used in transparent food packaging, foil, paints, and car part finishes. UV curing, or free radical photopolymerization, is the fastest-growing curing technology with an ever-increasing number of applications. Compared to solvent-based systems, UV curing saves energy and reduces or eliminates solvent emissions because most radiation-curable formulations are 100% solid formulations containing reactive oligomers and diluents. The mechanical properties of the cured formulation are typically determined by the oligomers and diluents. Photoinitiators are one of the key components of every photopolymerizable formulation because they generate free radicals that initiate polymerization upon light exposure.

A major drawback of most photopolymerizable formulations is the amount of unreacted photoinitiator molecules remaining in the cured polymer material. High conversion rates over very short periods mean that only a small number of initiator molecules can covalently bond to the polymer network. Solutions include, for example, irradiating for very long periods or using small amounts of initiator. Neither of these approaches is suitable for industrial-scale applications because short exposure times ensure the required high throughput. A reasonable conversion rate is usually achieved by increasing the percentage of photoinitiator, resulting in the aforementioned increased amount of unreacted photoinitiator in the cured formulation. In addition to migration out of the cured formulation, residual photoinitiator can cause yellowing and generate various byproducts, such as benzaldehyde, which also migrate out of the cured formulation. Migration is particularly problematic when protective and decorative coatings are applied to food packaging, healthcare, and other 24/7 use items that may come into contact with people.

Benzophenone and its derivatives are more commonly used as photoinitiators in the packaging field. However, there is ample evidence of carcinogenicity in animal studies for benzophenone, and it may be carcinogenic to humans (International Agency for Research on Cancer, “some chemicals present in industrial and consumer products, food and drinking water”, Vol. 101, pp. 285-301). In fact, a study (R. Z. Liu, S. A. Mabury, “First Detection of Photoinitiators and Metabolites in Human Sera from United States Donors”, Environmental Science and Technology, Vol. 52(17), pp. 10089-10096, 2018.) revealed the presence of photoinitiators and co-initiators in every single serum sample, indicating that photoinitiators and their photoproducts are ubiquitous contaminants. This suggests a need for radical-curable formulations, in which particularly alternative oligomeric photoinitiators are used. By using oligomeric photoinitiators, migration is significantly reduced. An example of such oligomeric photoinitiators is given in WO2021/259924. However, in that application, the basis of the oligomeric photoinitiator remains a benzophenone derivative.

The purpose of this invention is to provide an oligomer photoinitiator that is not derived from benzophenone and that possesses both good reactivity and low migration potential.

Overview

This document describes several aspects and embodiments of the invention. The first aspect is an oligomeric photoinitiating resin comprising a plurality of end groups according to formula (I):

and multiple end bases according to formula (II)

Wherein, according to formula (I), the number of terminal groups is m and m is equal to or greater than 1; according to formula (II), the number of terminal groups is n and n is equal to or greater than 2; the total amount of m and n (m + n) is equal to or greater than 4; _R1 in formula (I) is hydrogen or a straight-chain _C1 - _C6 alkyl or a branched _C3 - _C6 alkyl; _X1 , _X2 , _X3 , _X4 and _X5 in formula (II) are independently selected from hydrogen, a straight-chain _C1 - _C6 alkyl, a branched _C3 - _C6 alkyl, a _C5 - _C7 cycloalkyl, a phenyl, a _C1 - _C4 alkoxy, a _C5 - _C7 cycloalkoxy or a phenoxy, or _X1 and _X2 together can form an aromatic ring, or _X2 and _X3 can form an aromatic ring; each symbol The term represents the connection point; and the oligomeric photoinitiating resin has a weight-average molecular weight _Mw greater than 1100 g/mol, wherein the weight-average molecular weight Mw is determined as further described herein.

A second aspect of the invention is a free-radical curable composition comprising at least one oligomeric photoinitiating resin according to any embodiment of the first aspect of the invention. In one embodiment of the second aspect of the invention, the free-radical curable composition is a coating or ink composition.

A third aspect of the present invention is a coating or ink obtained as follows:

(1) To prepare or provide a free radical curable coating or ink composition according to one of the embodiments of the second aspect of the present invention,

(2) Apply the free radical curable coating or ink composition to a substrate, and

(3) Curing the free radical curable coating or ink composition with a light source free radical.

Detailed Explanation

For any range given in this document, all upper and/or lower bounds are included within the given range unless otherwise specified. Therefore, when referring to x to y, it means including x and y as well as all intermediate values.

The first aspect of the present invention is an oligomeric photoinitiating resin, wherein the oligomeric photoinitiating resin comprises m end groups according to formula (I) and n end groups according to formula (II):

in

m is equal to or greater than 1, preferably m is equal to or greater than 2.

n is equal to or greater than 2,

m + n is equal to or greater than 4

_R1 is hydrogen, a straight-chain _C1 - _C6 alkyl group, or a branched _C3 - _C6 alkyl group.

_X1 , _X2 , _X3 , _X4 , and _X5 are independently selected from hydrogen, straight-chain _C1 - _C6 alkyl, branched _C3 - _C6 alkyl, _C5 - _C7 cycloalkyl, phenyl, _C1 - _C4 alkoxy, _C5 - _C7 cycloalkoxy, or phenoxy, or _X1 and _X2 together can form an aromatic ring, or _X2 and _X3 together can form an aromatic ring, and

Each symbol Represents the connection point, and

The oligomeric photoinitiating resin has a weight-average molecular weight _Mw greater than 1100 g/mol, wherein the weight-average molecular weight Mw is determined as described in the specification.

It has been surprisingly found that the photoinitiators according to the invention exhibit enhanced reactivity in radical-curable compositions, particularly compared to ethoxylated analogs, thus resulting in higher curing rates for the radical-curable compositions, typically explained by higher conversion rates of the radical-curable groups. Even more surprisingly, it has been found that the oligomeric photoinitiators according to the invention exhibit enhanced reactivity in radical-curable compositions compared to ethoxylated analogs, while also possessing increased stability compared to ethoxylated analogs. The photoinitiators according to the invention can be particularly advantageously applied to radical-curable coatings and ink compositions in which low migration of chemicals is required.

Considering the reduced mobility, the oligomeric photoinitiator resin according to the invention preferably has a weight-average molecular weight _Mw greater than 1200 g/mol, more preferably greater than or equal to 1500 g/mol. Preferably, the oligomeric photoinitiator resin according to the invention preferably has a weight-average molecular weight _Mw of up to 15000 g/mol, more preferably up to 12000 g/mol, and even more preferably up to 10000 g/mol. As used herein, the weight-average molecular weight _Mw is determined using the methods further described herein.

The oligomeric photoinitiator resin according to the present invention comprises at least one end group according to formula (I):

Wherein _R1 is hydrogen or a straight-chain _C1 - _C6 alkyl or a branched _C3 - _C6 alkyl, preferably, _R1 is hydrogen or methyl, more preferably, _R1 is hydrogen. When _R1 is methyl, the oligomeric photoinitiator resin according to the invention contains methacrylate end groups as free radical polymerization groups. When _R1 is hydrogen, the oligomeric photoinitiator resin according to the invention contains acrylate end groups as free radical polymerization groups. The oligomeric photoinitiator resin according to the invention preferably contains at least two end groups of formula (I).

The oligomeric photoinitiator resin according to the present invention comprises at least one end group according to formula (II), preferably at least two end groups according to formula (II):

_X1 , _X2 , _X3 , _X4 , and _X5 are independently selected from hydrogen, straight-chain _C1 - _C6 alkyl, branched _C3 - _C6 alkyl, _C5 - _C7 cycloalkyl, phenyl, _C1 - _C4 alkoxy, _C5 - _C7 cycloalkoxy, or phenoxy, or _X1 and _X2 together can form an aromatic ring, or _X2 and _X3 together can form an aromatic ring. In the case where _X1 and _X2 together form an aromatic ring, preferably, the group according to formula (II) is derived from 1-naphthylacetaldehyde. In the case where _X2 and _X3 together form an aromatic ring, preferably, the group according to formula (II) is derived from 2-naphthylacetaldehyde. Preferably, _X1 , _X2 , _X3 , _X4 , and _X5 are hydrogen; or _X1 , _X2 , _X4 , and _X5 are hydrogen, and _X3 is a _C1 - _C4 alkoxy, preferably methoxy, or phenyl; or _X2 and _X3 together form an aromatic ring. More preferably, _X1 , _X2 , _X3 , _X4 , and _X5 are hydrogen.

The sum of the terminal numbers (i.e., m) according to equation (I) and the terminal numbers (i.e., n) according to equation (II), i.e., m + n, is equal to or greater than 4. Preferably, m + n is equal to or greater than 5.

The oligomeric photoinitiator resin of the present invention can be obtained by a method comprising at least the following steps:

(1) Provide a propoxylated core oligomer having at least m + n (m + n ≥ 4, preferably m + n ≥ 5) terminal OH functional groups,

(2) Esterification (exchange) of the m terminal OH functional groups of the propoxylated core oligomer with the compound according to formula (Ib) and esterification (exchange) of the n terminal OH functional groups of the propoxylated core oligomer with the compound according to formula (IIb):

_R2 and _R6 are independently hydrogen or _C1 - _C4 alkyl; and _R1 , _X1 , _X2 , _X3 , _X4 and _X5 are as described above.

This esterification (ester exchange) is typically carried out using catalysts known to those skilled in the art, such as acid catalysts, for example, methanesulfonic acid or sulfuric acid. The resulting water (in the case of _R2 = H and _R6 = H) or the resulting small alcohol (in the case of _R2 = _C1 - _C4 alkyl and _R6 = _C1 - _C4 alkyl) (methanol, ethanol, etc.) can be removed physically by means of an entrainer, such as toluene, a nitrogen stream, or vacuum. In a preferred embodiment, _R2 = H and _R6 = _C1 - _C4 alkyl, preferably methyl or ethyl. In a more preferred embodiment, _R2 = H and _R6 = H.

Epoxy resins, such as Epikote™ 828 available from Hexion, can be used to remove acid catalysts. Alternatively, the resin can be washed to remove the acid catalyst.

The propoxylated core oligomer preferably has at least m + n (m + n ≥ 4, preferably m + n ≥ 5) end groups having formula (IV):

To incorporate multiple functional groups (including at least m end groups having formula (I) and n end groups having formula (II), the propoxylated core oligomer is preferably a branched oligomer, more preferably a highly branched oligomer, and even more preferably a hyperbranched oligomer. Using branched, highly branched, or hyperbranched oligomers as the core oligomer has the advantage that they can have multiple end groups, preferably hydroxyl end groups, which can be readily modified to obtain the oligomeric photoinitiator resin according to the invention. In the context of this invention, a highly branched oligomeric photoinitiator resin is understood to be an oligomer having a branched structure and a high density of functional groups of formulas (I) and (II). In the context of this invention, a hyperbranched oligomeric photoinitiator resin is understood to be an oligomer having a branched structure and an even higher density of functional groups of formulas (I) and (II).

core oligomers

The core oligomer can be a polyether, polyester, polycarbonate, polyamide, or polyacrylic acid-based oligomer, and may optionally further include urethane linkages. Preferred core oligomers are polyether oligomers optionally further including urethane linkages or polyester oligomers optionally further including urethane linkages.

Polyether core oligomers include, for example, those derived from ethoxylated or propoxylated glycerol, ethoxylated or propoxylated trimethylolpropane, ethoxylated or propoxylated pentaerythritol, ethoxylated or propoxylated bis(trimethylolpropane), ethoxylated or propoxylated dipentaerythritol, ethoxylated or propoxylated sorbitol, and/or ethoxylated or propoxylated sucrose.

The polyester core oligomer can be derived, for example, from diacids and/or tricarboxylic acids or their esters together with polyols such as diols, triols, tetraols, hexaols, and/or octaols. Examples of diacids are adipic acid, succinic acid, ketoglutaric acid, malonic acid, maleic acid, fumaric acid, and itaconic acid. An example of a tricarboxylic acid is trimellitic acid (or anhydride). Preferred polyols are propoxylated forms of butanediol, hexanediol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, di(trimethylolpropane), dipentaerythritol, sorbitol, and sucrose.

Clearly, hydroxy acids and/or esters can also be used to obtain polyester core oligomers, examples of which are linear hydroxy acids such as lactic acid, γ-hydroxybutyric acid, and caprolactone, and branched hydroxy acids such as citric acid or 2,2-dimethylolpropionic acid. The latter can be used to prepare branched core oligomers, with Boltorn ^™ H2004 and H311 being examples. The core containing a branched amide is, for example, the Hybrane™ core.

Polyester core oligomers can also be obtained via a so-called anhydride oxetane reaction. One example of such core oligomers can be obtained by combining trimellitic anhydride with trimethylolpropane.

As previously mentioned, the core oligomer can also be an acrylic oligomer having multiple hydroxyl groups. These hydroxyl-functionalized oligomers can be prepared, for example, by free radical polymerization of hydroxyethyl (meth)acrylate. Those skilled in the art will recognize that other hydroxyl-functionalized unsaturated compounds can also be used. Examples include hydroxybutyl monovinyl ether, hydroxyethyl maleimide, caprolactone acrylate, ethoxylated or propoxylated acrylic acid. The hydroxyl-functionalized unsaturated compounds can undergo oligomerization/polymerization or copolymerization on their own. For this copolymerization, many other unsaturated compounds are available, such as various (meth)acrylates, styrene, acrylonitrile, and vinyl ethers.

The oligomeric photoinitiating resin according to the present invention can also be obtained by one-pot synthesis, wherein at least one or more compounds having formula (Ib), one or more compounds having formula (IIb), and one or more propoxylated polyols having at least m + n (m + n ≥ 4, preferably m + n ≥ 5) terminal OH functional groups, and optionally one or more diacids and/or tricarboxylic acids or their esters, are reacted in one step. Preferred propoxylated polyols have at least m + n (m + n ≥ 4, preferably m + n ≥ 5) terminal OH functional groups, said polyols being propoxylated forms of butanediol, hexanediol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, bis(trimethylolpropane), dipentaerythritol, sorbitol, and/or sucrose. The one or more propoxylated polyols have at least m + n (m + n ≥ 4, preferably m + n ≥ 5) terminal OH functional groups, and preferably have at least m + n (m + n ≥ 4, preferably m + n ≥ 5) end groups having formula (IV):

.

Preferred propoxylated polyols having at least m + n (m + n ≥ 4, preferably m + n ≥ 5) end groups of formula (IV) are propoxylated forms of pentaerythritol, bis(trimethylolpropane), dipentaerythritol, sorbitol and/or sucrose.

The inventors have further discovered that it may be advantageous for the oligomeric photoinitiator resin according to the invention to contain at least one end group of formula (III).

_R8 , _R9 , and _R10 are independently selected from hydrogen or methyl. More preferably, _R8 , _R9 , and _R10 are hydrogen. When _R8 , _R9 , and _R10 are hydrogen, pyruvate derived from the following formula according to one or more end groups of formula (III)

.

The oligomeric photoinitiator resin according to the present invention preferably contains a plurality of propoxy groups, wherein the number of propoxy groups is preferably at least 4, more preferably at least 5, even more preferably at least 8, and preferably at most 200, more preferably at most 100, and most preferably at most 80.

A second aspect of the invention is a free radical curable composition comprising at least one oligomeric photoinitiating resin as described above.

The amount of the oligomeric photoinitiator resin according to the invention in the composition can vary over a wide range, such as from 0.001 wt% to 99 wt%. Preferably, the amount of the oligomeric photoinitiator resin according to the invention is between 0.05 wt% and 50 wt% relative to the total weight of the radical-curable composition. The amount of the oligomeric photoinitiator resin according to the invention is preferably greater than 0.1 wt%, more preferably greater than 0.5 wt%, or greater than 1 wt%, or greater than 2 wt%, and preferably less than 40 wt%, or less than 35 wt%, or less than 30 wt% relative to the total weight of the radical-curable composition. Higher amounts of the oligomeric photoinitiator resin can also be suitably used depending on the amount of radical-curable groups in the oligomeric photoinitiator resin. For example, when the oligomeric photoinitiator resin according to the invention contains two or more acrylate end groups, the oligomeric photoinitiator resin itself can be considered a radical-curable oligomer and can be used in an amount of 20 to 70 wt%.

Although other radically polymerizable compounds are not required when the oligomeric photoinitiator resin contains radically polymerizable groups, the radically curable composition preferably further comprises one or more radically curable olefinic unsaturated groups, preferably radically curable oligomers having one or more (meth)acryloyl or vinyl groups. The one or more oligomers having one or more radically curable olefinic unsaturated groups preferably have a number-average molecular weight (Mn) of 800 g/mol or higher, more preferably 1000 g/mol or higher; preferably less than or equal to 15000 g/mol, more preferably less than or equal to 5000 g/mol, whereby _the number-average molecular weight _Mn is determined as described below.

The one or more oligomers having one or more free radical curable olefinic unsaturated groups are present in the free radical curable composition in an amount preferably at least 10% by weight, or at least 15% by weight, or at least 20% by weight, and at most 80% by weight, or at most 75% by weight, or at most 70% by weight, relative to the total weight of the free radical curable composition.

Preferably, the free radical curable oligomer is selected from urethane (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, and any mixture thereof. More preferably, the free radical curable oligomer is selected from urethane acrylates, epoxy acrylates, polyester acrylates, polyether acrylates, and any mixture thereof.

(Meth)acrylate-functionalized oligomers can be selected to enhance properties such as flexibility, strength, and/or modulus of cured polymers prepared using the free radical curable compositions of the present invention. The (meth)acrylate-functionalized oligomers may have 1 to 18 (meth)acrylate groups, particularly 2 to 6 (meth)acrylate groups, more particularly 2 to 6 acrylate groups. The (meth)acrylate-functionalized oligomers may have a number average molecular weight greater than 800 g/mol, particularly 800 to 15000 g/mol, more particularly 1000 to 5000 g/mol. In particular, the (meth)acrylate-functionalized oligomers may be selected from (meth)acrylate-functionalized urethane oligomers (sometimes also referred to as "urethane(meth)acrylate oligomers", "polyurethane(meth)acrylate oligomers" or "carbamate(meth)acrylate"). (Meth)acrylate-functionalized epoxy oligomers (sometimes also called "epoxy (meth)acrylate oligomers"), (meth)acrylate-functionalized polyether oligomers (sometimes also called "polyether (meth)acrylate oligomers"), (meth)acrylate-functionalized polydiene oligomers (sometimes also called "polydiene (meth)acrylate oligomers"), (meth)acrylate-functionalized polycarbonate oligomers (sometimes also called "polycarbonate (meth)acrylate oligomers"), and (meth)acrylate-functionalized polyester oligomers (sometimes also called "polyester (meth)acrylate oligomers"), acrylic (meth)acrylate oligomers, and mixtures thereof. Preferably, the (meth)acrylate-functionalized oligomers comprise (meth)acrylate-functionalized urethane oligomers, more preferably acrylate-functionalized urethane oligomers. Advantageously, (meth)acrylate-functionalized oligomers comprise (meth)acrylate-functionalized urethane oligomers having two (meth)acrylate groups, more preferably acrylate-functionalized urethane oligomers having two acrylate groups. Exemplary polyester (meth)acrylate oligomers comprise the reaction product of acrylic acid or methacrylic acid or mixtures or synthetic equivalents thereof with a hydroxyl-terminated polyester polyol. The reaction process can be carried out such that all or substantially all hydroxyl groups of the polyester polyol have been (meth)acrylated, particularly when the polyester polyol is bifunctional. The polyester polyol can be produced by the polycondensation reaction of a polyhydroxy functional component (particularly a diol) and a polycarboxylic acid functional compound (particularly a dicarboxylic acid and anhydride). The polyhydroxy functional component and the polycarboxylic acid functional component can each have a linear, branched, alicyclic, or aromatic structure, and can be used alone or as a mixture.

Examples of suitable epoxy (meth)acrylate oligomers include reaction products of acrylic acid or methacrylic acid or mixtures thereof with epoxy resins (polyglycidyl ethers or esters). Epoxy resins may be particularly 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 phenolic varnish resins, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, 2-(3,4-epoxy... Cyclohexyl-5,5-spiro-3,4-epoxycyclohexane-1,4-dioxane, bis(3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl 1-3',4-epoxy-6-methylcyclohexane carboxylate, methylene bis(3,4-epoxycyclohexane), Dicyclopentadiene diesteroxide, ethylene glycol di(3,4-epoxycyclohexylmethyl) ether, ethylene bis(3,4-epoxycyclohexane carboxylate), 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 ether of polyether polyols obtained by adding one or more epoxides to aliphatic polyols such as ethylene glycol, propylene glycol and glycerol, diglycidyl esters of aliphatic long-chain dicarboxylic acids, monoglycidyl ethers of aliphatic higher alcohols, monoglycidyl ethers of phenol, cresol, butylphenol, or polyether alcohols obtained by adding epoxides to these compounds, glycidyl esters of higher fatty acids, epoxidized soybean oil, epoxidized butyl stearic acid, epoxidized octyl stearic acid, epoxidized linseed oil, epoxidized polybutadiene, etc.

Suitable polyether (meth)acrylate oligomers include, but are not limited to, the condensation products of acrylic acid or methacrylic acid or their synthetic equivalents or mixtures with polyether alcohols, wherein the polyether alcohol is a polyether polyol (such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol). Suitable polyether alcohols can be straight-chain or branched substances containing ether bonds and terminal hydroxyl groups. Polyether alcohols can be prepared by ring-opening polymerization of cyclic ethers such as tetrahydrofuran or epoxides (e.g., ethylene oxide and/or propylene oxide) with primer molecules. Suitable primer molecules include water, polyhydroxy functional materials, polyester polyols, and amines.

Polyurethane (meth)acrylate oligomers (sometimes also referred to as "urethane (meth)acrylate oligomers") suitable for the curable compositions of the present invention comprise urethanes based on aliphatic, alicyclic, and/or aromatic polyester polyols and polyether polyols, as well as aliphatic, alicyclic, and/or aromatic diisocyanates and end-capped with (meth)acrylate groups. Suitable polyurethane (meth)acrylate oligomers include, for example, urethane diacrylate and tetraacrylate oligomers based on aliphatic polyesters, urethane diacrylate and tetraacrylate oligomers based on aliphatic polyethers, and urethane diacrylate and tetraacrylate oligomers based on aliphatic polyester/polyethers. Polyurethane (meth)acrylate oligomers can be prepared by reacting an aliphatic, alicyclic, and/or aromatic polyisocyanate (e.g., diisocyanate, triisocyanate) with an OH-terminated polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polyorganosiloxane polyol (e.g., polydimethylsiloxane polyol) or polydiene polyol (e.g., polybutadiene polyol) or a combination thereof to form an isocyanate-functionalized oligomer, which is then reacted with a hydroxyl-functionalized (meth)acrylate, such as hydroxyethyl acrylate or hydroxyethyl methacrylate, to provide terminal (meth)acrylate groups. For example, the polyurethane (meth)acrylate oligomer may contain two, three, four, or more (meth)acrylate functional groups per molecule. Other addition sequences can also be used to prepare polyurethane (meth)acrylates, as is known in the art. For example, hydroxyl-functionalized (meth)acrylates can be reacted first with polyisocyanates to obtain isocyanate-functionalized (meth)acrylates, which can then be reacted with OH-terminated polyester polyols, polyether polyols, polycarbonate polyols, polycaprolactone polyols, polydimethylsiloxane polyols, polybutadiene polyols, or combinations thereof. In yet another embodiment, polyisocyanates can be reacted first with polyols (including any of the types described above) to obtain isocyanate-functionalized polyols, which are then reacted with hydroxyl-functionalized (meth)acrylates to produce polyurethane (meth)acrylates. Alternatively, all components can be combined and reacted simultaneously.

Suitable acrylic (meth)acrylate oligomers (sometimes referred to in the art as "acrylic oligomers") include oligomers that can be described as having an oligomeric acrylic backbone functionalized with one or more (meth)acrylate groups (which may be terminal or side-attached to the acrylic backbone of the oligomer). The acrylic backbone can be a homopolymer, random copolymer, or block copolymer composed of repeating units of acrylic monomers. The acrylic monomers can be any monomeric (meth)acrylate, such as _C1 - _{C6 alkyl} methacrylates, and functionalized (meth)acrylates, such as (meth)acrylates with hydroxyl, carboxylic acid, and/or epoxy groups. Acrylic (meth)acrylate oligomers can be prepared using any procedure known in the art, such as by oligomerizing a monomer, functionalizing at least a portion of the monomer with hydroxyl, carboxylic acid and/or epoxy groups (e.g. hydroxyalkyl (meth)acrylate, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized oligomer intermediate, which is then reacted with one or more reactants containing (meth)acrylate to introduce the desired (meth)acrylate functional group.

The curable composition of the present invention may contain 10 to 80% by weight, particularly 15 to 75% by weight, and more particularly 20 to 70% by weight (meth)acrylate functionalized oligomers relative to the total weight of the free radical curable composition.

For viscosity reasons, the use of reactive diluents may be advantageous. Reactive diluents are compounds that can reduce the viscosity of a formulation while also enabling free radical copolymerization. Therefore, the present invention also relates to free radical curable compositions comprising reactive diluents. The one or more diluents having one or more, preferably two or more, free radical curable olefinic unsaturated groups may be present in the free radical curable composition in an amount of at least 1% by weight, or at least 5% by weight, or at least 10% 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, relative to the total weight of the free radical curable composition.

As reactive diluents, various acrylic, methacrylate, or vinyl functional monomers can be used. Suitable examples are, for instance, diacrylates or dimethacrylates of glycols or polyether glycols, such as propoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), diethylene glycol diacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, neopentyl glycol diacrylate, 1,4-butanediol diacrylate (e.g., SR213), alkoxylated aliphatic diacrylates (e.g., SR9209A), and alkoxylated hexanediol diacrylates (e.g., from Sartamomer Co., Inc.'s SR561, SR562, SR563, SR564), polyethylene glycol (200) diacrylate (SR259), polyether glycol-200-diacrylate, PEG300-diacrylate, polypropylene glycol diacrylate, ethoxylated (3) bisphenol-A-diacrylate, BDDA butanediol diacrylate, BDDMA butanediol dimethacrylate or higher functional acrylates, such as trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate. Esters, TMP3EOTA ethoxylated (3)trimethylolpropane triacrylate, TMP6EOTA ethoxylated (6)trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol (4)-propoxylated triacrylate, pentaerythritol tetraacrylate, ethoxylated or propoxylated neopentyl glycol, propoxylated (4) glycerol triacrylate, trifunctional monomers such as Laromer type from BASF or Ebecryl 2047 or Ebecryl 12 from Allnex, di-trimethylolpropane tetraacrylate, dipentaerythritol-pentaacrylate (Di-PEPA), dipentaerythritol hexaacrylate (DPHA). Examples of vinyl compounds are compounds such as butanediol divinyl ether or N-vinylcaprolactam as a monofunctional compound. Although monofunctional (meth)acrylates, such as lauryl (meth)acrylate and phenoxyethyl (meth)acrylate, are also possible, reactive diluents having at least two free-radical curable olefinic unsaturated groups are preferred for low migration. Obviously, mixtures can also be used.

In a preferred embodiment of the invention, the oligomeric photoinitiator resin further comprises one or more free radical curable olefinic unsaturated groups, preferably one or more (meth)acryloyl or vinyl groups, more preferably at least two (meth)acryloyl groups, and even more preferably at least two acryloyl groups; and

The free radical curable composition optionally further comprises one or more olefinic unsaturated groups having one or more free radical curable olefinic groups, preferably oligomers having one or more (meth)acryloyl or vinyl groups; and

The radical-curable composition further comprises one or more diluents having one or more radical-curable olefinic unsaturated groups, preferably, the one or more diluents having at least two radical-curable olefinic unsaturated groups; and

Free radical curable compositions contain

The oligomeric photoinitiating resin is used in amounts of 3 to 70% by weight.

The oligomer is present in amounts of 0 to 80% by weight.

The diluent is used in amounts of 10 to 70% by weight.

The quantities thus described are given relative to the total weight of (i) to (iii).

To further improve the curing speed, acrylate functional groups, which are free radical curable olefinic unsaturated groups, are preferred over methacrylate functional groups.

According to another aspect, the present invention relates to a free radical curable ink composition or a free radical curable coating composition comprising: a) at least one binder, b) at least one olefinic unsaturated compound selected from monomers and/or oligomers, and c) one or more oligomeric photoinitiating resins of the present invention.

If the free radical curable composition is a free radical curable ink composition, it contains at least one pigment. Preferably, based on the total amount of the free radical curable ink composition (i.e., the composition before curing), the amount of pigment is preferably 0.5 to 50% by weight, more preferably 3 to 20% by weight. The cured ink composition preferably contains 0.5 to 50% by weight, more preferably 3 to 20% by weight of pigment.

In addition to the oligomeric photoinitiating resin according to the invention, other initiators can be used with a variety of other additives. Examples of such additives are those selected from rheology modifiers, adhesion promoters, defoamers, slip additives, wetting agents, leveling agents, gloss additives, waxes, wetting agents, curing agents, chelating agents, additional photoinitiators, amine synergists, inhibitors, desiccants, stabilizers, emulsifiers, abrasion-resistant additives, plasticizers, antistatic additives, matting agents, and any combination of two or more of the above additives.

Free radical curable ink compositions or free radical curable coating compositions can be formulated to suit any known printing technology, such as offset printing, lithography, intaglio printing, flexographic printing, gravure printing, screen printing, digital printing, inkjet printing, pad printing, transfer printing, lettering printing, etc.

Another aspect of the present invention is a method for free radical curing the free radical curable composition of the present invention, comprising the following steps:

(1) Prepare or provide the free radical curable composition as described above, and

(2) The free radical curable composition is cured by light source free radical.

The light source is preferably a UV light source that emits UV light in at least one range of UVA, UVB and UVC, or an LED light source that emits light in the range of 350 to 450 nm.

The method preferably includes the step of applying the free radical curable composition to the substrate prior to free radical curing.

Another aspect of the present invention is a coating or ink obtained as follows:

(1) Prepare or provide the free radical curable coating or ink composition as described above,

(2) Apply the free radical curable coating or ink composition to a substrate, and

(3) Curing the free radical curable coating or ink composition with a light source free radical.

The following examples further illustrate the invention, but should not be construed as limiting its scope in any way.

Example

These examples illustrate embodiments of the present invention. Table 1 describes the various components used in preparing the oligomeric photoinitiator resin and the free radical curable composition used in the embodiments of the present invention. Table 2 describes the relative amounts of the reagents described in Table 1 used in synthesizing the oligomeric photoinitiator resin used in the embodiments of the present invention. Tables 3 to 6 report the photoreactivity of the oligomeric photoinitiator resin. Unless otherwise stated, all parts, percentages, and ratios are by weight.

Table 1 – Components of the Formulation

Components Chemical description Supplier/Manufacturer Ad Adipic acid; CAS no. 124-04-9 BASF PhG Phenylglyoxylic acid; CAS no. 611-73-4 Sigma-Aldrich Py Pyruvic acid; CAS no. 127-17-3 Sigma-Aldrich Ac Acrylic acid; CAS no. 79-10-7 Evonik PP Pentaerythritol propoxylate (5/4 PO/OH); CAS no. 9051-49-4 Sigma-Aldrich PE Pentaerythritol ethoxylate (5/4 EO/OH); CAS no. 42503-45-7 Sino-Japan Chemical SPa Sorbitol propoxylate ( _Mn 2000); CAS no. 52625-13-5 Covestro AG SPb Sorbitol propoxylate ( _Mn 650); CAS no. 52625-13-5 Covestro AG SE Sorbitol ethoxylate ( _Mn 1300); CAS no. 53694-15-8 Sino-Japan Chemical Methoxyphenol; CAS no. 150-76-5 Sigma-Aldrich BHT Butylated hydroxytoluene; CAS no. 128-37-0 Sigma-Aldrich Toluene; CAS no. 108-88-3 ExxonMobil MSA Mesylate; CAS no. 75-75-2 BASF Epikote™ 828 Epoxy resin _Mn 350; CAS no. 68038-82-4 Hexion Specialty Chemicals Inc. DBTDL Dibutyltin dilaurate; CAS no. 77-58-7 Valtris Specialty Chemicals Ltd. Neorad™ U25-20D urethane acrylate resin diluted with HDDA Covestro AG Acclaim® 4200 (PPG4000) Bifunctional polypropylene glycol; molecular weight approximately 4000 Covestro AG

Table 1 (continued)

Components Chemical description Supplier/Manufacturer TDI Toluene diisocyanate; CAS no. 584-84-9 BASF HEA 2-Hydroxyethyl acrylate; CAS no. 818-61-1 Nippon Shokubai CO. Ltd. PEA 2-Phenoxyethyl Acrylate Covestro AG Agisyn™ 2844 Ethoxylated (EO) 5-pentaerythritol tetraacrylate; CAS no. 51728-26-8 Covestro AG Agisyn ^™ 717 Polyester acrylate modified with hexafunctional fatty acids Covestro AG Agisyn ^™ 670A2 Hexafunctional aromatic carbamate acrylates Covestro AG Agisyn ^™ 2830 Dipentaerythritol hexaacrylate; CAS no. 29570-58-9 Covestro AG ASP ^™ 200 Aluminum silicate BASF Ceraflour 950 Micronized wax Byk Genorad 16 stabilizer Rahn AG Solsperse™ 3900 dispersant Lubrizol Irgalite® Rubine D 4240 magenta pigment BASF/Sun Chemical Omnipol ASA Amine synergist CAS no. 71512-90-8 IGM Resins Omnipol TX Sensitizer; CAS no. 813452-37-8 IGM Resins Omnirad TPO-L Photoinitiator CAS no. 84434-11-7 IGM Resins

Preparation of formulation

Unless otherwise stated, each formulation described is prepared by conventional methods using a 50 ml mixing cup suitable for use with Speedmixer™. Add the components to the mixing cup, bringing the total amount to approximately 10 g. Then seal the cup and vigorously mix in the Speedmixer™ DAC150FVZ for 5 minutes, stop, and mix again for another 5 minutes using the same method.

Viscosity determination

Viscosities were determined at 25°C and a shear rate of 100 ^s⁻¹ on a BROOKFIELD DVNXB5CBG rheometer equipped with a 2.5 cm diameter/1° cone/plate geometry. A CPA-40Z rotor (2.4 cm diameter/0.8° cone/plate geometry) was used for samples with viscosities between 0.65 and 25 Pa·s; a CPA-52Z rotor (1.2 cm diameter/3° cone/plate geometry) was used for samples with viscosities between 25 and 800 Pa·s.

Molecular weight determined by GPC

Number-average molecular weight ( _Mn ) and weight-average molecular weight ( _Mw ) were measured by SEC, calibrated with a set of polystyrene standards ranging from 500 to 7 x ^10⁶ g/mol, and eluent was obtained using stabilized tetrahydrofuran modified with 0.8% acetic acid [THF with 0.007-0.015% w/w butyl-hydroxytoluene (BHT)] at a flow rate of 1 mL/min at 40 °C.

More specifically, 50 mg of oligomeric photoinitiator resin was dissolved in 5 mL of eluent at room temperature without shaking for 16 hours. 10 µL of the solution thus prepared was injected into the system for measurement.

SEC measurements were performed on a Waters GPC system consisting of: i) a Waters 2414 refractive index detector at 40 °C; ii) a Waters Shodex packed column at 40 °C – featuring four different Shodex packed columns (5000 Å, 500 Å, 150 Å, and 50 Å pore sizes), I/d = 300/8 mm, and filled with particles of 10 (5000 Å) or 6 μm (500 Å, 150 Å, and 150 Å columns) (1 µm = 1 x 10⁻⁶ m) supplied by Waters; iii) a Waters 2707 autosampler-injection system; and iv) a Waters 1515 isocratic HPLC pump. _Mn and _Mw were determined using Empower 3 software from Waters.

Reactivity was determined using UV Rig.

A 12-micron-thick film was prepared from the formulation on a glass plate and cured on a Fusion UV Rig equipped with a Fusion F600 H lamp (1 W/ ^cm² ), using a total dose of 0.8 J/ ^cm² , as determined by EIT Power Puck II. After curing, the acrylate conversion was determined using infrared spectroscopy. The error in the conversion measurement is estimated to be approximately + 5%.

Photoreactivity was determined using the standard procedure of optical DSC.

These analyses were performed using a Mettler Toledo DSC3+ in a nitrogen atmosphere with approximately 30 mg of the formulation, fitted with a PhotoDSC fixture equipped with an Excelitas Omnicure LX 500 385nm LED light source (1.7W/ ^cm² ).

The following procedure was used: After calibrating the sample under nitrogen for 150 seconds, the sample was irradiated for 150 seconds. This was followed by a 50-second dark period, and then a second irradiation for 50 seconds. The second irradiation was performed to verify that complete conversion had been achieved during the first irradiation. Reactivity is expressed as the time (seconds) to reach maximum heat flux and the maximum rate of double bond conversion (in mmol ^{s⁻¹ l⁻¹} , calculated from the maximum heat flux (W/g), using 78.5 kJ/mol as the enthalpy of reaction of the acrylate and an assumed density of 1 kg/l).

Reactivity was determined using RT-DMA: maximum modulus (G’) and T30%, maximum modulus value.

For RT-DMA, formulations were prepared using 70 parts of urethane oligomer 1 (prepared as described below), 30 parts of 2-phenoxyethyl acrylate, and 5 parts of oligomeric photoinitiator resin (prepared as described below). These formulations were analyzed on a TA Instrument Rheometer (HR20) equipped with a UV curing accessory (320–500 nm, OmniCure® Series 2000). The UV output intensity was calibrated at the sample location using an external radiometer. For the photoconductor accessory, this intensity (25 mW/ ^cm² ) was applied and recorded as the total intensity without any filters. The sample thickness was 0.25 mm, and single-frequency oscillation measurements were performed at 5 Hz with a controlled strain of 1%. The curing process was monitored using dynamic time-scan experiments.

Illumination was initiated 60 seconds after measurement. This paper reports the maximum modulus and the time to reach 30% of the maximum modulus after the start of irradiation as measures of curing speed.

Synthesis of Oligomer Photoinitiating Resins OIR 1-10 – Typical Procedure

Synthesis of OIR 1

Step 1) Load 14.6 g adipic acid (Ad), 85.2 g pentaerythritol propoxylate (PP), 240 g toluene, and 0.74 g methanesulfonic acid (MSA) into a 500 ml reactor equipped with a stirrer, nitrogen inlet, and Dean-Stark apparatus. Heat the reaction to reflux under a gentle nitrogen flow and maintain this temperature until no more reaction water forms (4 hours).

Next (Step 2), 60.0 g of phenylglyoxylic acid (PhG), 14.4 g of acrylic acid (Ac) (and optionally pyruvic acid (Py)) were added, and the reaction mixture was heated to reflux under a gentle nitrogen flow and maintained at this temperature until no more reactive water was formed (4 hours). Next, all toluene was removed by distillation under reduced pressure at 95°C. Then, 2.7 g of Epikote™ 828 was added, and the reaction was stirred for another 30 minutes, cooled, and OIR 1 with a viscosity of 34.4 Pa·s was obtained.

Synthesis of OIR 2-10 and C1-C3

The synthesis of OIR 2-10 and C1-C3 is similar to that of OIR 1, prepared using the amounts described in Table 2.

For example, the structural formula of OIR 2 with the idealized structure Ad ₁ PP ₂ Py ₂ PhG ₂ Ac ₂ is:

Where p + q + x + y equals 5.

Table 2 : Amounts used in the synthesis of OIR1-10 and OIR C1-C3, their molecular weights and viscosities

Synthesis of carbamate oligomer 1

First, a 1 L reactor (equipped with a stirrer, air inlet, dropping funnel, and condenser) was purged with dry-lean air. Then, 2.19 parts of BHT were loaded into the reactor, followed by 52.76 parts of TDI and then 0.02 parts of acrylic acid. After loading, the reactor was heated to 45°C. Then, half the specified amount of catalyst (i.e., 0.06 g of bismuth neodecanoate) and then 35.43 parts of HEA were loaded into the reactor while stirring. After waiting for one (1) hour to allow the reaction to begin, the temperature was then raised to 60°C. At 60°C, 700 parts of PPG4000 and the second part of catalyst (i.e., 0.07 g) were added, after which the reaction temperature was raised to 85°C and held for another two (2) hours.

After this additional two (2) hours of reaction time, the amount of isocyanate (NCO) was measured by potentiometric titration to ensure it was below 0.1% relative to the total weight of the composition. If the isocyanate content was not below this value, the mixture was returned to the reaction chamber in 15-minute increments (again at 85°C) and checked again, repeating this step until the isocyanate content was reduced to the desired range. Finally, the resulting synthetic oligomer 1 with the idealized structure HEA-TDI-PPG4000-TDI-HEA was slowly cooled and discharged for use.

Examples 1-4 and Comparative Experiments A-C

A formulation for RT-DMA analysis was prepared using 70 parts of urethane oligomer 1, 30 parts of 2-phenoxyethyl acrylate, and 5 parts of oligomeric photoinitiator resin. The curing results using RT-DMA are shown in Table 3.

Formulations for clear varnish OPV were prepared using 36 parts Neorad™ U25-20D, 59 parts Agisyn™ 2844, and 10 parts oligomeric photoinitiator resin. These formulations were cured in air (H-bulb) on a UV Rig, and the conversion efficiency was determined by IR. The curing results are also shown in Table 3.

Table 3

OIR T30% sec Maximum modulus G’ MPa OPV % Conversion Rate Ex 1 1 Ad ₁ PP ₂ PhG ₄ Ac ₂ 15.7 0.86 85 CEx A C1 Ad ₁ PE ₂ PhG ₄ Ac ₂ 17.7 0.82 70 Ex 2 2 Ad ₁ PP ₂ Py ₂ PhG ₂ Ac ₂ 18.8 0.76 75 CEx B C2 Ad ₁ PE ₂ Py ₂ PhG ₂ Ac ₂ 24.4 0.86 65 Ex 3 4 SPa ₁ Py ₂ PhG ₂ Ac ₂ 21.1 0.64 70 CEx C C3 SE ₁ Py ₂ PhG ₂ Ac ₂ 33.7 0.68 45 Ex 4 5 SPb ₁ Py ₂ PhG ₂ Ac ₂ 18.7 0.79 90

These examples and comparative experiments demonstrate that propoxylated oligomeric photoinitiators achieve higher curing efficiency compared to ethoxylated oligomeric photoinitiators. This is reflected in both a shorter time to reach 30% of maximum modulus using RT-DMA and a higher conversion rate when curing OPV in air using a UV rig.

This is particularly surprising because the comparative experiment had a lower molecular weight, meaning there was a higher molar amount of chromophore, so the expected result was exactly the opposite.

As shown in Table 4, the viscosity stability of the oligomeric photoinitiating resin was tested at 75°C for 7 days.

Table 4

These experiments demonstrate that the OIR according to the present invention exhibits surprisingly higher stability compared to ethoxylated oligomer photoinitiating resins. This is particularly surprising because Table 3 shows that propoxylated oligomer photoinitiating resins exhibit increased reactivity compared to ethoxylated oligomer photoinitiating resins.

Examples 5-10

The preparation and curing of the formulations were carried out in a manner similar to that of Examples 1 to 4. The results are shown in Table 5.

Table 5

Example OIR Idealized structure T30% sec Maximum modulus G' MPa OPV % conversion rate 5 3 SPa ₁ Py ₁ PhG ₃ Ac ₂ 19 0.64 75 6 6 Ad ₁ SPb ₂ Py ₁ PhG ₃ Ac ₂ 18 0.76 90 7 7 Ad ₁ SPb ₂ Py ₁ PhG ₄ Ac ₂ 18 0.78 90 8 8 Ad ₁ SPb ₂ Py ₁ PhG ₅ Ac ₂ 17 0.81 90 9 9 Ad ₁ SPb ₂ Py ₃ PhG ₃ Ac ₂ 19 0.64 85 10 10 Ad ₁ SPb ₂ Py ₁ PhG ₃ Ac ₃ 20 0.81 85

These examples further demonstrate that different amounts of phenylglyoxylic acid and acrylic acid moieties can be present in the oligomeric photoinitiating resin according to the invention.

Example 11 and Reference Example: Preparation of Magenta Ink Formulation

Clay and wax paste were prepared using a high-speed mixer with 22.5 parts ASP™ 200, 2.5 parts Ceraflour 950, and 75 parts Agisyn™ 2830.

A magenta ink formulation was prepared using 24.75 parts Agisyn™ 717, 17.55 parts Irgalite® Rubine D 4240, 0.45 parts Genorad 16, and 2.25 parts Solsperse™ 39000. This mixture was converted into a pigment paste using a three-roll mill. Next, 25 parts of the clay and wax paste prepared as described above and 30 parts Ad ₁ SPb ₂ Py ₁ PhG ₃ Ac ₃ were added, and the formulation was mixed using a high-speed mixer. Ad ₁ SPb ₂ Py ₁ PhG ₃ Ac ₃ was prepared as described above, except that the reaction with Epikote™ 828 was omitted and replaced with washing with an aqueous sodium sulfate solution. The amount of free acid was found to be low, as indicated by the presence of less than 100 ppm of free acrylic acid.

The reference ink formulation was prepared as described above; however, 20 parts of Agisyn™ 670A2, 4.6 parts of Omnipol ASA, 3.3 parts of Omnipol TX, 2.0 parts of Omnirad TPO-L, and 0.1 parts of Genorad 16 were used instead of 30 parts of Ad ₁ SPb ₂ Py ₁ PhG ₃ Ac ₃ .

Lithographic printing behavior was evaluated using LithoTack II (Novomatics) with CTP300 dampening solution. Offset prints were prepared using an IGT C1-5, 300N (IGT testing system) equipped with rubber cloth rollers, and subsequently cured with Hg lamps at various belt speeds. The results are reported in Table 6.

Table 6

The results shown in Table 6 demonstrate that offset printing inks with good curing properties can be prepared using the oligomeric initiator resin according to the present invention, especially since the reference example contains 10% by weight of photoinitiator.

Claims (17)

1. An oligomeric photoinitiating resin, wherein the oligomeric photoinitiating resin comprises m end groups according to formula (I) and n end groups according to formula (II): in m is equal to or greater than 1, preferably m is equal to or greater than 2. n is equal to or greater than 2, m + n is equal to or greater than 4 _R1 is hydrogen, a straight-chain _C1 - _C6 alkyl group, or a branched _C3 - _C6 alkyl group. _X1 , _X2 , _X3 , _X4 , and _X5 are independently selected from hydrogen, straight-chain _C1 - _C6 alkyl, branched _C3 - _C6 alkyl, _C5 - _C7 cycloalkyl, phenyl, _C1 - _C4 alkoxy, _C5 - _C7 cycloalkoxy, or phenoxy, or _X1 and _X2 together can form an aromatic ring, or _X2 and _X3 together can form an aromatic ring, and Each symbol Represents the connection point, and The oligomeric photoinitiating resin has a weight-average molecular weight _Mw greater than 1100 g/mol, wherein the weight-average molecular weight Mw is determined as described in the specification. 2. The photoinitiating resin according to claim 1, wherein the weight-average molecular weight _Mw of the photoinitiating resin is greater than 1200 g/mol, more preferably greater than or equal to 1500 g/mol. 3. The photoinitiating resin according to claim 1 or 2, wherein _R1 is hydrogen or methyl, more preferably _R1 is hydrogen. 4. The photoinitiating resin according to any one of the preceding claims, wherein _X1 , _X2 , _X3 , _X4 and _X5 are hydrogen, or _X1 , _X2 , _X4 and _X5 are hydrogen and _X3 is alkoxy or phenyl, or _X2 and _X3 together form an aromatic ring, more preferably, _X1 , _X2 , _X3 , _X4 and _X5 are hydrogen. 5. The photoinitiating resin according to any one of the preceding claims, wherein m + n is equal to or greater than 5. 6. The photoinitiating resin according to any one of the preceding claims, wherein the number of propoxy groups in the photoinitiating resin is at least 4, more preferably at least 5, even more preferably at least 8, and preferably at most 200, more preferably at most 100, and most preferably at most 80. 7. A free radical curable composition comprising at least one oligomeric photoinitiating resin according to any one of claims 1 to 6. 8. The free radical curable composition according to claim 7, wherein the oligomeric photoinitiator resin is present in an amount of 0.05 to 50% by weight, preferably 0.1 to 40% by weight, more preferably 0.1 to 30% by weight, relative to the total weight of the free radical curable composition. 9. The radical-curable composition according to claim 7 or 8, wherein the radical-curable composition further comprises one or more olefinic unsaturated groups having one or more radical-curable olefinic groups, preferably oligomers having one or more (meth)acryloyl or vinyl groups. 10. The free radical curable composition according to claim 9, wherein the one or more oligomers having one or more free radical curable olefinic unsaturated groups are independently selected from urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyether (meth)acrylate oligomers, polyester (meth)acrylates, and any mixture thereof; more preferably, the one or more oligomers having one or more free radical curable olefinic unsaturated groups are urethane (meth)acrylate oligomers; and even more preferably, the one or more oligomers having one or more free radical curable olefinic unsaturated groups are urethane acrylate oligomers. 11. The radical-curable composition according to claim 9 or 10, wherein the one or more oligomers having one or more radical-curable olefinic unsaturated groups have a number-average molecular weight ( _Mn ) of 800 to 15000 g/mol, preferably 1000 to 5000 g/mol, wherein the number-average molecular weight _Mn is determined as described in the specification. 12. The radical-curable composition according to any one of claims 9 to 11, wherein, relative to the total weight of the radical-curable composition, the one or more oligomers having one or more radical-curable olefinic unsaturated groups are present in the radical-curable composition in an amount of at least 10% by weight, or at least 15% by weight, or at least 20% by weight and at most 80% by weight, or at most 75% by weight, or at most 70% by weight. 13. The radical-curable composition according to any one of claims 7 to 12, wherein the radical-curable composition further comprises one or more diluents having one or more radical-curable olefinic unsaturated groups, preferably at least two radical-curable olefinic unsaturated groups. 14. The free radical curable composition according to claim 13, wherein, relative to the total weight of the free radical curable composition, the one or more diluents having one or more free radical curable olefinic unsaturated groups are present in the free radical curable composition in an amount of at least 1% by weight, or at least 5% by weight, or at least 10% by weight and in an amount of at most 85% by weight, or at most 80% by weight, or at most 70% by weight. 15. The free radical curable composition according to claim 7, wherein... The photoinitiating resin contains one or more olefinic unsaturated groups that can be cured by free radicals, preferably one or more (meth)acryloyl or vinyl groups, more preferably at least two (meth)acryloyl groups; The free radical curable composition optionally further comprises one or more olefinic unsaturated groups having one or more free radical curable olefinic groups, preferably oligomers having one or more (meth)acryloyl or vinyl groups; and The free radical curable composition further comprises one or more olefinic unsaturated groups having one or more free radical curable olefinic unsaturated groups, preferably a diluent having at least two free radical curable olefinic unsaturated groups; and wherein... The free radical curable composition contains (i) 3 to 70% by weight of the photoinitiating resin. (ii) 0 to 80% by weight of the oligomer, (iii) 10 to 70% by weight of the diluent, The quantities thus described are given relative to the total weight of (i) to (iii). 16. The free radical curable composition according to any one of claims 7 to 15, wherein the free radical curable composition is a coating or ink composition. 17. A coating or ink obtained by: (1) To prepare or provide a free radical curable coating or ink composition according to claim 16; (2) Applying the free radical curable coating or ink composition to a substrate; and (3) Curing the free radical curable coating or ink composition with a light source free radical.