The present invention relates to novel compounds which are useful as functionalized photoinitiators which may be used directly or after further functionalization in various photo- curable coating compositions including varnishes, lacquers, printing inks and the like, especially varnishes as well as to a process to prepare such novel compounds. The invention also provides radiation-curable surface coating compositions which include at least one of the compounds of the present invention as a photoinitiator.

Background

Photoinitiators used in photo-curable compositions such as coating compositions need to ensure good cure speed, low volatility, low yellowing and good solubility, in particular in the coating compositions. Furthermore, increasing health awareness led to lower legal limits in extractables in particular where photocured coatings are likely coming or intended to come into contact with food or food ingredients.

Another requirement, in order for the photoinitiators to be useful in practice, it is necessary that such compounds are accessable via efficient large scale processes and allow easy processing and long term stability in coating compositions. For the latter it is desired that the photoinitiators are low viscuous liquids which are highly compatible with other ingredients of photocurable compositions and thus do not give rise to flocculation or similar forms of deposit formation upon longer storage. Benzophenone is known for its capability to allow fast curing, having a good solubility and showing a low degree of yellowing while being cheap and widely available. The drawbacks associated with its use however are an undesireable high degree of extractability and migration as well as its strong odour which prevents it from being used in modern packaging industry.

Another material that has an absorption maximum making it in principle useful to be utilized as photoinitiator is 4-hydroxybenzophenone. Due to its poor solubility in UV curable formulations and its lower reactivity it is, however, rarely used for that purpose.

There were made several attempts to overcome this drawbacks by using functionalized benzophenones such as benzophenone -2-methyl ester (Speedcure MBB ex Lambson) and acrylated benzophenone (IRR261 ex UCB). Even though the aformentioned compounds are less volatile and thus cause less odour their activity as photoinitiator is significantly lower compared to benzophenone.

Further known examples include benzophenone derivatives bound to a poly butandiol ether backbone via carboxymethoxy moities which are described in detail in WO 03/033452 Al and commercially available under the tradename Omnipol BP.

However, the synthesis of these products starting from 4-hydroxybenzophenone requires several tedious reaction and isolation steps thus rendering the overall efficiency low.

Furthermore, the products are typically wax-like or highly viscous and thus hard to handle. Another disadvantage is that they still exhibit a substantial migration level when applied in coating compositions. In addition to that such products not compatible with photocurable compositions over the whole desired range and may form deposits upon longer storage.

Another attempt to overcome the problems of migration and odour was made by binding inter alia 4-benzophenonecarboxylic esters to a polymeric backbone bearing several hydroxy groups such as polyethylene glycol. Such compounds are for example disclosed in EP 2 394 676 Al and commercially available under the tradename Genopol BP.

The disadvantages of these compounds are, however, that the carboxy substituted benzophenone derivatives have reduced reactivity.

EP 632 329 A and EP 2 617 705 disclose photoinitiators of the benzophenone, acetophenone or hydroxyacetophenone type which were functionalized with diisocyanates. Such products may be further functionalized with hydroxyalkyl(meth)acrylates to obtain photoiniitators which are capable of being incorporated into a polymer upon irradiation.

DE 10 2006 047 863 A discloses Photoinitiators inter alia of the hydroxy benzophenone type which are substituted by various ether functionalities.

WO03/064061 A discloses as two single compounds acrylic esters of ethoxylated 4-hydroxy- benzophenone with chain lengths of n=l and n=4. The synthesis of such compounds is, however, according to own investigations, tedious and thus is not suitable to allow large scale and/or efficient manufacturing. DE 102012216170 A discloses photoreactive polymers prepared from a monomer selected from (meth)acrylic esters of ethoxylated 2,5-dimethyl-4-hydroxy-benzophenone with chain lengths of 1 to 30, preferably 5 to 20.

The synthesis of such monomers shown in example 3 of DE 102012216170 A for n=9 proceeds via tosylation of the respective polyhydroxyethylacrylate and coupling of said activated ester with 2,5-dimethyl-4-hydroxy-benzophenone and thus is quite inefficient in terms of aiding agents.

The monomers as such were not employed as photoinitiators.

W099/47176 A discloses a PEG200 ethoxylated 4-hydroxymethyl-benzophenone as starting material for further functionalisation. It is not used as photoinitiator.In view of the aforementioned there was still a need for improved photoinitiators having low odour, good reactivity, particularly good surface curing, and a limited tendency to migrate and be extracted and which does not yellow on cure. It is further desired that such photoinitiators are easy to prepare, allow easy processing and show high compatibility with typical ingredients of photocurable compositions.

The invention therefore relates to mixtures comprising compounds of formula (IV)

wherein the arrows denote substitution at the aromatic ring without specifically indicating the relative position to the depicted keto-group if not mentioned otherwise hereinafter and wherein is either missing and the two aromatic rings are then therefore substituted with hydrogen, or where n or m are not zero alternatively also with R ¹ or R ² respectively, at the position where B is depicted to be bound at the aromatic ring or is sulfur or oxygen, whereby B is preferably missing or sulfur and more preferably B is missing is 0, 1 or 2, preferably 0 or 1 and more preferably 0 is independently of other substituents R ¹ which may be present selected from the group consisting of Ci-Ci8-alkyl, C2-Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio C6-Ci4-aryl, C6-Ci4-aryloxy, C6-Ci4-arylthio, -N(R ⁵ )2, fluoro, chloro and COOR ⁵ with R ⁵ being hydrogen or Ci-Ci8-alkyl is 0, 1 or 2, preferably 0 or 1 and more preferably 0 is independently of other substituents R ² which may be present selected from the group consisting of Ci-Ci8-alkyl, C2-Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio, C6-Ci4-aryl, C6-Ci4-aryloxy, C6-Ci4-arylthio, -N(R ⁵ )2, fluoro, chloro and COOR ⁵ , with R ⁵ being hydrogen or Ci-Ci8-alkyl and v is 0 or 1, preferably 0 and the substituents L-Het[[CHR ³ CHR ⁴ 0] _P -H] _t if present and L-Het-[CHR ³ CHR ⁴ 0] _q -H] _t independently of each other occupy the ortho-, meta or the para-position, more preferably the ortho- or the para-position and even more preferably the para-position at their respective aromatic ring and with respect to the keto-function depicted in formula (IV) and wherein

L is independently missing or a methylene group, i.e. Het is either directly bound to the aromatic ring or via a methylene group

Het is independently sulphur, oxygen, N(Ci-Ci8-Alkyl), or N, preferably oxygen t is 1 for Het = sulphur, oxygen, N(Ci-Ci8-Alkyl) and is 2 for for Het = N R ³ and R ⁴ are either identically hydrogen or one of R ³ and R ⁴ is hydrogen and the other is methyl, whereby, in a preferred embodiment R ³ and R ⁴ are identically hydrogen and p and q independently of each other represent an integer of 0 or more, preferably 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 wherein with respect to the number of repeating units p and q, however, at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (IV) within the mixture are those of formula (IV) wherein · q, where v is 0 and t is 1 or

• at least one of p and q, where both t are 1 or

• at least one of all q, where v=0 and t is 2 or

• at least one of all p and all q, where v=l and where at least one t is 2 is 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 wherein none of the single compounds of formula (IV) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (IV) in the mixture or alternatively wherein with respect to the number of repeating units p and q, however, at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (IV) within the mixture are those of formula (IV) wherein

at least one of p and q where both t are 1 or of all p and all q where at least one t is 2, is 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (IV) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (IV). Detailed description of the Invention

The invention also encompasses all combinations of preferred embodiments, ranges parameters as disclosed hereinafter with either each other or the broadest disclosed range or parameter.

In another embodiment none of the single compounds of formula (IV) is present in an amount of more than 45 wt.-%, preferably not more than 40 wt.-% with respect to the total weight of compounds of formula (IV) in the mixture.

In one embodiment the total amount of compounds of formula (IV) present in the mixture comprising compounds of formula (IV) having at least one of q or where present p and q being 5 or larger is 20 wt.-% or less, preferably 15 wt.-% or less and more preferably 12 wt.-% or less.

The weight of compounds of formula (IV) with respect to the total weight of the mixture according to the invention is from 10 to 100 wt.-%, preferably 80 to 100 wt.-%, more preferably 90 tolOO wt.-% and even more preferably 95 to 100 % wt.-%.

The remainder to 100 wt.-% if present may comprise for example the respective ketals of compounds of formula (IV) i.e. compounds of formula (III), unreacted compounds of formula (II) and their ketals, solvents or catalyst residues.

In a preferred embodiment the compounds of formula (IV) in the mixtures according to the invention are those of formula (IVa)

(IVa) wherein the arrows, B, n, R ¹ , m, R ² , R ³ , R ⁴ and L have the same meaning as set forth for formula (IV) above including their preferred embodiments and q represents an integer of 0 or more, preferably 1 or more, preferably of from 1 to

20, more preferably of from 1 to 10 wherein with respect to the number of repeating units q at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (IVa) within the mixture are those of formula (IVa) having a number of repeating units q of 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (IVa) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (IVa). In one embodiment the total amount of compounds of formula (IVa) present in the mixture comprising compounds of formula (IVa) wherein q is 5 or larger is 20 wt.-% or less, preferably 15 wt.-% or less and more preferably 12 wt.-% or less.

In another embodiment none of the single compounds of formula (IVa) is present in an amount of more than 45 wt.-%, preferably not more than 40 wt.-% with respect to the total weight of compounds of formula (IVa) in the mixture.

The weight of compounds of formula (IVa) with respect to the total weight of the mixture according to the invention is from 10 to 100 wt.-%, preferably 80 to 100 wt.-%, more preferably 90 to 100 wt.-% and even more preferably 95 to 100 % wt.%.

The remainder to 100 wt.-% if present may comprise for example the respective ketals of compounds of formula (IVa) and catalyst residues.

In a particularly preferred embodiment the compounds of formula (IV) in the mixtures according to the invention are those of formula (IVb)

wherein L, R ³ and R ⁴ have the meaning including their preferred embodiments set forth above for formula (IV) and

q represents an integer of 0 or more, preferably 1 or more, preferably of from 1 to

20, more preferably of from 1 to 10 wherein with respect to the number of repeating units q at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (IVb) within the mixture are those of formula (IVb) having a number of repeating units q of 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (IVb) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (IVb).

In one embodiment the total amount of compounds of formula (IVb) present in the mixture comprising compounds of formula (IVa) wherein q is 5 or larger is 20 wt.-% or less, preferably 15 wt.-% or less and more preferably 12 wt.-% or less.

In another embodiment none of the single compounds of formula (IVb) is present in an amount of more than 45 wt.-%, preferably not more than 40 wt.-% with respect to the total weight of compounds of formula (IVb).

In another preferred embodiment L is missing. The invention further relates to compounds of formula (I) that can form part of mixtures of compounds of formula (IV), (IVa) or (IVb)

[L-Het-[[CHR ³ CHR 0] _r -H] _t ] _v L-Het-[[CHR ³ CHR ⁴ 0] _s -H] _t

(I) wherein the arrows, B, n, R ¹ , m, R ² , R ³ and R ⁴ , v, L, Het and t have the same meaning as set forth for formula (IV) above including their preferred embodiments and the substituents L-Het[[CHR ³ CHR ⁴ 0] _r -H] _t if present and L-Het-[CHR ³ CHR ⁴ 0] _s -H] _t independently of each other occupy the ortho-, meta or the para-position, more preferably the ortho- or the para-position and even more preferably the para-position at their respective aromatic ring and with respect to the keto-function depicted in formula (I) and if t is 1 for both substituents L-Het[[CHR ³ CHR ⁴ 0] _r -H] _t and L-Het-[CHR ³ CHR ⁴ 0] _s -H] _t either r or s is an integer of 3 or more, preferably of from 3 to 20, more preferably of from 3 to 10 and even more preferably 3, 4, 5, 6, 7 or 8 and the respective other of r or s is an integer of 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 and even more preferably 3, 4, 5, 6, 7, 8 or 9, with 3 being even more preferred or if t is 2 for one or both substituents L-Het[[CHR ³ CHR ⁴ 0] _r -H] _t and L-Het-[CHR ³ CHR ⁴ 0] _s -H] _t at least one r or s is an integer of 3 or more, preferably of from 3 to 20, more preferably of from 3 to 10 and even more preferably 3, 4, 5, 6, 7 or 8 and the other residues r and/or s are an integer of 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 and even more preferably 3, 4, 5, 6, 7, 8 or 9 with 3 being even more preferred.In another embodiment t is r and s are independently of one another an integer of 3 or more, preferably of from 3 to 20, more preferably of from 3 to 10 and even more preferably 5, 6, 7 or 8 or 3.

As used herein, and unless specifically stated otherwise, Ci-Ci8-alkyl, Ci-Ci8-alkoxy and Ci- Ci8-alkylthio, include straight-chained or, for C3-C18 also cyclic either in part or as a whole, branched or unbranched alkyl, alkoxy and alkylthio substituents having the given number of carbon atoms in the substituent as such.

As used herein, and unless specifically stated otherwise, C2-Ci8-alkenyl include straight- chained or, for C5-C18 also cyclic either in part or as a whole, branched or unbranched alkenyl, having the given number of carbon atoms in the substituent as such.

As used herein, and unless specifically stated otherwise, C6-Ci4-aryl, C6-Ci4-aryloxy and Ce- Ci4-arylthio denote carbocyclic aromatic substituents having six to fourteen carbon atoms within the aromatic system as such, i.e. without carbon atoms of substituents, preferably phenyl (Ce), naphthyl (C10), phenanthrenyl and anthracenyl (each C14), whereby said carbocyclic, aromatic substituents are either unsubstituted or substituted by up to five identical or different substituents per cycle. For example and with preference, the substituents are selected from the group consisting of fluoro, chloro, Ci-Ci8-alkyl, Ci-Ci8-alkoxy, C6-Ci4-aryl.

In a more preferred embodiment the carbocyclic, aromatic substituents are unsubstituted.

Specific examples of Ci-Ci8-alkyl are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert- butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, n-hexyl, n-heptyl, n-octyl and isooctyl, n-decyl, n-dodecyl n-hexadecyl, n-octadecyl.

Specific examples of are methoxy, ethoxy, isopropoxy, n-propoxy, n-butoxy, sec.-butoxy, tert-butoxy and cyclohexyloxy.

Specific examples of are methylthio abnd ethylthio.

Specific examples of C6-Ci4-aryl are phenyl, o-,m-and p-tolyl.

A specific example of an C6-Ci4-aryl -substituent is phenoxy.

A specific example of an C6-Ci4-aryl -substituent is phenylthio.

In one embodiment n is 0 or 1,

R ¹ is independently of other substituents R ¹ which may be present selected from the group consisting of Ci-Ci8-alkyl, Ci-Ci8-alkoxy, C6-Ci4-aryl and chloro m is 0 or 1 R ² is independently of other substituents R ² which may be present selected from the group consisting of Ci-Ci8-alkyl, Ci-Ci8-alkoxy, C6-Ci4-aryl and chloro.

In a preferred embodiment n and m are 0.

Particularly preferred compounds of formula (I) are those of formula (la)

(la) wherein the arrows, B, R ¹ , n, R ² , m, R ³ and R ⁴ , L have the meaning including their preferred embodiments set forth above for formula (I) and s is an integer of 3 or more, preferably of from 3 to 20, more preferably of from 3 to 10 and even more preferably represents 5, 6, 7 or 8. In a further preferred embodiment in formula (la) the arrow for L-0-[CHR ³ -CHR ⁴ -0] _s -H denotes substitution at ortho- or para position, preferably at para position at the aromatic ring relative to the depicted keto- group and

B is missing n and m are 0

L is missing

R ³ and R ⁴ are either identically hydrogen or one of R ³ and R ⁴ is hydrogen and the other is methyl, whereby, in a preferred embodiment R ³ and R ⁴ are identically hydrogen and an integer of 3 or more, preferably of from 3 to 20, more preferably of from 3 to 10 and even more preferably represents 5, 6, 7 or 8 or 3.

Even more preferred compounds of formula (I) are those of formula (lb)

wherein L, R ³ and R ⁴ and s have the meaning including their preferred embodiments set forth above for formula (I) and formula (la).

The compounds of formula (I) or the mixtures of compounds of formula (IV) may be prepared by a process comprising at least the step of reacting one or more compounds, preferably one compound of formula (II)

with ethylene oxide and/or propylene oxide in the presence of a catalyst or in the absence of a catalyst, whereby the presence of a catalyst is preferred. Compounds of formulae (la) and (IVa) are accordingly accessible from compounds of formula (Ila)

(Ila) wherein the arrows, B, R ¹ , n, R ² , m and L have the meaning including their preferred embodiments set forth for formulae (la) and (IVa) above.

Compounds of formulae (lb) and (IVb) are accordingly accessible from 4- hydroxybenzophenone and 4-hydroxymethylbenzophenone. Specific starting materials of formula (II) include 2-hydroxythioxanthen-9-one, 4,4'-dihydroxybenzophenone, 4- hydroxybenzophenone and 4-hydroxymethylbenzophenone, whereby 4-hydroxybenzophenone is preferred.

The process according to the invention may be carried out as a continuous or batch process.

In one embodiment ethylene oxide is used. In another embodiment propylene oxide is used. In a further embodiment a mixture of ethylene oxide and propylene oxide is used.

In a preferred embodiment ethylene oxide is used.

The molar ratio of ethylene oxide, propylene oxide or the sum thereof to the compound(s) of formula (II) depends on the desired number of repeating units (p, q, r, s) . To e.g. obtain compounds of formula (I) or mixtures of compounds according to formula (IV) in a sufficient amount the above molar ratio should be at least 2.5, preferably at least 3, more preferably at least 3.5 per substituent L-Het-H if Het is oxygen, sulphur or N(Ci-Ci8-Alkyl) or the respective double amounts per substituent if Het is N.

In another embodiment the molar ratio of ethylene oxide, propylene oxide or the sum thereof to the compound(s) of formula (II) is from (r+s)+0.01 to (r+s)+1.0, preferably (r+s)+0.1 to (r+s)+1.0, wherein r and s are the desired number of repeating units and whereby (r+s) refers to the sum of all repeating units bound to Het in the molecule of formula (I).

Accordingly, where compounds of formula (Ha) are used as starting material the molar ratio of ethylene oxide, propylene oxide or the sum thereof to the compound(s) of formula (Ha) is from s+0.01 to s+1.0, preferably from s+0.1 to s+1.0, wherein s is the desired number of repeating units.

Analogously In another embodiment the molar ratio of ethylene oxide, propylene oxide or the sum thereof to the compound(s) of formula (II) is from (p+q)+0.01 to (p+q)+1.0, preferably from (p+q)+0.1 to (p+q)+1.0, wherein p and q are the desired number of repeating units and whereby (p+q) refers to the sum of all repeating units bound to Het in the molecules of formula (IV).

Accordingly, where compounds of formula (Ila) are used as starting material the molar ratio of ethylene oxide, propylene oxide or the sum thereof to the compound(s) of formula (Ila) is from q+0.01 to q+1.0, preferably from q+0.1 to q+1.0, wherein q is the desired number of repeating units.

In one embodiment of the invention the process is effected using a flow-through reactors, stirred tank reactors, tubular reactor, gas-liquid stirred reactors, Venturi-loop reactors or spray tower loop reactors.

In one embodiment the process is carried out at a temperature in the range of 20°C to 200°C, preferably in the range of 60°C to 180 °C and even more preferably in the range of 80°C to 150°C .

The reaction pressure is typically from 500 to 200,000 hP, preferably from 1,000 to 100,000 hPa, more preferably from 1,500 to 50,000 hPa and even more preferably from 2,000 to 30,000 hPa.

The process according to the invention is either carried out in an organic diluent or without organic diluent, whereby organic diluent is meant to be an organic compound which is liquid at 25°C which does virtually not react with ethylene oxide or propylene oxide at temperatures of up to 200°C.

In particular where no organic diluent is employed the process is preferably carried out above the melting point of the compound of formula (II) or the employed mixture of compounds of formula (II). Suitable diluents, where desired, include aliphatic hydrocarbons or any mixture thereof such isoaliphatic hydrocarbons according to CAS 64741 -65-7, particular aliphatic hydrocarbons including hydrocarbons such as methycyclopentane, 2-methylpentane, 3-methylpentane, n- hexane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene, ortho- xylene, para-xylene and meta-xylene and ethers such as 1,4-dioxane.

In one embodiment the reaction time is from 2 min to 24 h, preferably from 10 min to 16 h and more preferably from 3 to 12 h.

The process may be carried out batchwise or continuously. Where a continuous reaction is performed the reaction time given above represents the average residence time.

The reaction is either carried out in the presence of a catalyst or not.

In one embodiment no catalyst added.

In another embodiment a catalyst is added.

Catalysts may be be acidic or basic, preferably basic. Examples of acidic catalysts include Bronsted acids and Lewis acids and may be either inorganic or organic. Specific examples of Bronsted acids include sulfuric acid, hydrochloric or phosphoric acid, a sulphonic acid, such as p-toluenesulphonic acid or methanesulphonic acid;

Specific examples of Lewis acid include aluminium chloride, boron trifluoride or an organotitanate.

Examples of basic catalysts include sodium or potassium hydroxide.

Byproducts that may be formed during the process according to the invention are compounds of formula (III)

wherein the arrows, B, R ¹ , n, R ² , m, R ³ , R ⁴ , L, Het, v, t, r and s have the meaning including their preferred embodiments set forth for formula (I) above and wherein s denotes q and r denotes p where mixtures of compounds of formula (IV) including their preferred embodiments are concerned.

Since they are typically formed in a minor amount compared to their non ketalized analogoues of formula (I) and (IV) respectively removal is typically not required to fulfil the intended purpose. In the event pure compounds of formula (I) are desired, the ketals may be removed by reacting the compounds of formula (III) with an acid in the presence of water.

As a potential starting material for compounds of formulae (I) and (IV) the compounds of formula (III) are also encompassed by the invention.

In strict analogy compounds of formula (Ilia) are formed as byproducts during the process according to the invention to prepare compounds of formulae (la) and (IVa) starting from compounds of formula (Ila)

(Ilia) In formula (Ilia) the arrows, B, R ¹ , n, R ² , m , R ³ , R ⁴ , s and L have the meaning including their preferred embodiments set forth for formula (la) above and wherein s denotes q where mixtures of compounds of formula (IVa) including their preferred embodiments are concerned.

It is known to those skilled in the art, that when the compounds of formula (I) are prepared to the process described above mixtures of several compounds in which the number of repeating units of the ethylene oxide and/or propylene oxide moieties differs (mixtures of compounds of formula IV).

Isolation of pure compounds of formula (I) may be effected by chromatographic methods such as flash chromatography, preparative HPLC, and simulated moving bed chromatography. However, it was found that the mixtures of compounds of formula (IV) are not only preferred due to lack of workup and purification steps while providing the same advantages as compounds of formula (I) but provide further advantages, i.e. lower viscosity and thus even better processing in combination therewith. It was found that the compounds of formula (I) or mixtures comprising compounds of formula (IV) may further be functionalized.

Therefore the invention further encompasses compounds of formula (VI)

wherein the arrows denote substitution at the aromatic ring without specifically indicating the relative position to the depicted keto-group if not mentioned otherwise hereinafter and wherein

B is either missing and the two aromatic rings are then therefore substituted with hydrogen, or where n or m are not zero alternatively also with R ¹ or R ² respectively, at the position where B is depicted to be bound at the aromatic ring or is sulfur or oxygen, whereby B is preferably missing or sulfur and more preferably B is missing n is 0, 1 or 2, preferably 0 or 1 and more preferably 0

R ¹ is independently of other substituents R ¹ which may be present selected from the group consisting of hydrogen, Ci-Ci8-alkyl, C2-Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio C ₆ -Ci4-aryl, C ₆ -Ci ₄ -aryloxy, C ₆ -Ci ₄ -arylthio, -N(R ⁵ ) ₂ , fluoro, chloro and COOR ⁵ with R ⁵ being hydrogen or Ci-Ci8-alkyl m is 0, 1 or 2, preferably 0 or 1 and more preferably 0

R ² is independently of other substituents R ² which may be present selected from the group consisting of hydrogen, Ci-Ci8-alkyl, C2-Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio,

C ₆ -Ci4-aryl, C ₆ -Ci ₄ -aryloxy, C ₆ -Ci ₄ -arylthio, -N(R ⁵ ) ₂ , fluoro, chloro and COOR ⁵ , with R ⁵ being hydrogen or Ci-Ci8-alkyl and wherein v is 0 or 1 , preferably 0 the substituents L-Het-[[CHR ³ CHR ⁴ 0] _y i-E] where present and L-Het-[[CHR ³ CHR ⁴ 0] _y2 -E] independently of each other occupy the ortho-, meta or the para-position, more preferably the ortho- or the para-position and even more preferably the para-position at their respective aromatic ring and with respect to the keto-function depicted in formula (I) and wherein L is independently missing or a methylene group, i.e. Het is either directly bound to the aromatic ring or via a methylene group

Het is independently sulphur, oxygen, N(Ci-Ci8-Alkyl), NH or N, preferably oxygen t is 1 for Het = sulphur, oxygen, N(Ci-Ci8-Alkyl), NH and is 2 for for Het = N R ³ and R ⁴ are either identically hydrogen or one of R ³ and R ⁴ is hydrogen and the other is methyl, whereby, in a preferred embodiment R ³ and R ⁴ are identically hydrogen and if t is 1 yl and y2 independently of each other represent an integer of 0 or more, preferably 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 and even more preferably 3 to 10, whereby the sum of yl and y2 is at least 1 for v = 1, or y2 is at least 1 where v = 0 if t is 2 all yl and y2 independently of each other represent an integer of 0 or more, preferably 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 and even more preferably 3 to 10, whereby the sum of all yl and all y2 is at least 1 for v = 1, or the sum of all y2 is at least 1 where v = 0 and

E independently, preferably identically represents H2C=CH-CO-, (CH3)HC=CH-CO- or H ₂ C=C(CH ₃ )-CO-, whereby H ₂ C=CH-CO- and H ₂ C=C(CH ₃ )-CO- are preferred and H2C=CH-CO- is even more preferred.

The preparation of compounds of formula (VI) may be effected by standard esterification procedures known to those skilled in the art, which include for example and as an exemplary embodiment contacting the compounds of formula (I) or mixtures of compounds of formula (IV) with acids E-H in the presence of an acid such as a mineral acid such as sulfuric or hydrochloric acid or a organic sulfonic acid such as p-toluene sulfonic acid and removing water e.g. via distillation. Alternatively compounds of formula (I) or mixtures of compounds of formula (IV) can be treated with acid halides E-Hal, with Hal being CI or Br, in the presence of a base such as an amine.

Preferred compounds of formula (VI) are those of formula (Via)

wherein the arrows, B, R ¹ , n, R ² , m, L, R ³ , R ⁴ and E have the meaning including their preferred embodiments set forth above for formula (VI) and y2 represents an integer of 1 or more, preferably 1 to 20, more preferably 2 to 10, and yet even more preferably 2, 3, 4, 5 or 6.

Particularly preferred compounds of formula (VI) are compounds of formula (VIb)

Wherein L, R ³ and R ⁴ have the meaning including their preferred embodiments set forth above for formula (VI)

y2 represents an integer of 1 or more, preferably 1 to 20, more preferably 2 to 10, and yet even more preferably 2, 3, 4, 5 or 6 and

E represents H ₂ C=CH-CO- or H ₂ C=C(CH ₃ )-CO-, preferably H ₂ C=CH-CO-.

In another preferred embodiment L is missing.

The invention further encompasses mixtures comprising compounds of formula (VI), wherein with respect to the number of repeating units yl and y2 at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (VI) within the mixture are those of formula (VI) wherein

• y2, where v is 0 and t is 1 or · at least one of yl and y2, where both t are 1 or

• at least one of all y2, where v=0 and t is 2 or

• at least one of all yl and all y2, where v=l and where at least one t is 2 is 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (VI) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (VI) in the mixture or alternatively wherein with respect to the number of repeating units yl and y2 at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (VI) within the mixture are those of formula (VI) wherein at least one of yl and y2 where both t are 1 or of all p and all q where at least one t is 2, is 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (VI) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (VI) In another embodiment none of the single compounds of formula (VI) is present in an amount of more than 45 wt.-%, preferably not more than 40 wt.-% with respect to the total weight of compounds of formula (VI).

In preferred embodiment the invention further encompasses mixtures comprising compounds of formula (Via), more preferably compounds of formula (Vlb), wherein with respect to the number of repeating units y2. at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (Via) resp. formula (Vlb) within the mixture are those of formula (Via) resp. formula (VIb) having a number of repeating units y2 of 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (Via) resp. (VIb) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (Via) resp. (VIb).

In one embodiment the total amount of compounds of formula (IVa) resp. (VIb) present in the mixtures comprising compounds of formula (IVa) wherein q is 5 or larger is 20 wt.-% or less, preferably 15 wt.-% or less and more preferably 12 wt.-% or less.

The weight of compounds of formula (VI) resp. (Via) resp (VIb) with respect to the total weight of the mixture according to the aformentioned embodiments of the invention is from 10 to 100 wt.-%, preferably 80 to 100 wt.-%, more preferably 90 tolOO wt.-% and even more preferably 95 to 100 % wt.%.

The remainder to 100 wt.-% if present may comprise for example the respective ketals, unreacted compounds and their ketals, solvents or catalyst residues. However, it was surprisingly found that during functionalization with compounds of formula E- H or E-Hal as described above the respective ketals are reacted to form additional compounds of formula (VI) resp. (Via) resp (VIb) with the ethylene glycol released forming the respective mono and double esters, particularly double esters.

It was found that the compounds of formula (la) or mixtures comprising compounds of formula (IVa) may further be functionalized in an alternative way.

Therefore the invention further encompasses compounds of formula (Vila)

(Vila) wherein arrows denote substitution at the aromatic ring without specifically indicating the relative position to the depicted keto-group if not mentioned otherwise hereinafter and wherein is either missing and the two aromatic rings are then therefore substituted with hydrogen, or where n or m are not zero alternatively also with R ¹ or R ² respectively, at the position where B is depicted to be bound at the aromatic ring or is sulfur or oxygen, whereby B is preferably missing or sulfur and more preferably B is missing is 0, 1 or 2, preferably 0 or 1 and more preferably 0

R ¹ is independently of other substituents R ¹ which may be present selected from the group consisting of hydrogen, Ci-Cis-alkyl, C ₂ -Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio C ₆ -Ci4-aryl, C ₆ -Ci ₄ -aryloxy, C ₆ -Ci ₄ -arylthio, -N(R ⁵ )¾ fluoro, chloro and COOR ⁵ with R ⁵ being hydrogen or Ci-Ci8-alkyl is 0, 1 or 2, preferably 0 or 1 and more preferably 0 is independently of other substituents R ² which may be present selected from the group consisting of hydrogen, Ci-Ci8-alkyl, C2-Ci8-alkenyl, Ci-Ci8-alkoxy, Ci-Ci8-alkylthio, Ce- Ci4-aryl, C6-Ci4-aryloxy, C6-Ci4-arylthio, -N(R ⁵ ) ₂ , fluoro, chloro and COOR ⁵ , with R ⁵ being hydrogen or Ci-Ci8-alkyl and wherein the substituent L-0[CHR ³ CHR ⁴ 0] _y 3- occupies the ortho-, meta or the para-position, more preferably the ortho- or the para-position and even more preferably the para-position at the aromatic ring and with respect to the keto-function depicted in formula (Vila) and wherein

L is independently missing or a methylene group, i.e. Het is either directly bound to the aromatic ring or via a methylene group

R ³ and R ⁴ are either identically hydrogen or one of R ³ and R ⁴ is hydrogen and the other is methyl, whereby, in a preferred embodiment R ³ and R ⁴ are identically hydrogen and y3 represents an integer of 1 or more, preferably of from 1 to 20, more preferably of from 1 to 10 and even more preferably 3 to 10 w is an integer of 2 or more, preferably 2, 3 or 4 and

R ^z represents R(CO) _x with R being an x-valent organic residue with 1 or more, preferably 1 to 30 carbon atoms.

Preferred compounds of formula (Vila) are those wherein the arrows, B, R ¹ , n, R ² , m, R ³ and R ⁴ and L have the meaning including their preferred embodiments set forth above for formula (Via) and y3 has the same meaning as y2 in formula (Via). w is 2 and R ^z is a residue derived from terephthalic, phthalic, crotonic, itaconic, succinic, maleic or fumaric acid by abstraction of all OH-groups of the respective carboxylic functions.

The preparation of compounds of formula (Vila) may be effected by standard esterification procedures known to those skilles in the art, which include for example and as an exemplary embodiment contacting the compounds of formula (I) or mixtures of compounds of formula (IV) with acids R-(COH) _x in the presence of an acid such as a mineral acid such as sulfuric or hydrochloric acid or a organic sulfonic acid such as p-toluene sulfonic acid and removing water e.g. via distillation. Alternatively compounds of formula (I) or mixtures of compounds of formula (IV) can be treated with acid halides R-(COHal) _x , with Hal being CI or Br, in the presence of a base such as an amine.

The invention further encompasses mixtures comprising compounds of formula (Vila), wherein with respect to the number of repeating units y3 at least 50 wt.-%, preferably at least 55 wt.-% and even more preferably at least 60 wt.-% of the total weight of compounds of formula (Vila) within the mixture are those of formula (Vila) having a number of repeating units y3 of 3 or more, preferably of 3 to 20, even more preferably 3 to 10 and yet even more preferably 3, 4, 5, 6, 7 or 8 and wherein none of the single compounds of formula (Vila) is present in an amount of more than 50 wt.-% with respect to the total weight of compounds of formula (Vila).

The weight of compounds of formula (Vila) with respect to the total weight of the mixture according to the aformentioned embodiments of the invention is from 10 to 100 wt.-%, preferably 80 to 100 wt.-%, more preferably 90 tolOO wt.-% and even more preferably 95 to 100 % wt%. The remainder to 100 wt.-% if present may comprise for example the respective ketals, unreacted compounds and their ketals, solvents or catalyst residues.

The compounds of formula (I), as well as the specified mixtures comprising compounds of formula (IV), the compounds of formula (VI) or mixtures thereof as specified above or compounds of formula (Vila) or mixtures thereof as specified above each including their preferred embodiments are particularly useful as photoinitiators and for use in photo-curable compositions in particular coating compositions, including varnishes, lacquers and printing inks, wood coatings, furniture coating, floor coatings, UV curable adhesives and UV curable resins as well as in other drying or curing compositions such as water-borne or solvent containing UV-curable formulations.

They are further useful as photoinitiators in heterophase polymerizations such as emulsion polymerizations.

Accordingly, the present invention also relates to photo-curable compositions, comprising

(a) at least one ethylenically unsaturated component and

(b) at least one compound of formula (I) or

a mixture comprising compounds of formula (IV) as specified above or at least one compound of formula (VI) or mixtures thereof as specified above or at least one compound of formula (Vila) or mixtures thereof as specified above.

Where mixtures of compounds of formula (VI) are present the term ethylenically unsaturated compound preferably denotes a compound other than a compound of formula (VI).

Whereever reference is made to compounds of formula (I) or mixtures of compounds of formula (IV), or compounds of formula (VI) or mixtures of compounds of formula (VI) in the photo-curable compositions and their applications and uses the preferred embodiments described above for such compounds and mixtures shall accordingly apply thereto.

Suitable ethylenically unsaturated components include mono(meth)acrylates, aliphatic or aromatic urethane (meth)acrylates, polyether (meth)acrylates, polyester (meth)acrylates and epoxy (meth)acrylates (such as bisphenol A epoxy acrylate).

Examples of suitable mono(meth)acrylates include methylacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, butyl acrylate and butyl methacrylate.

Polyester (meth)acrylates include dipropylene glycol diacrylate, pentaerytritol tetraacrylate, di- pentaerytrityl hexaacrylate, di-, tri- and tetra-ethylenglycol diacrylate, hexanediol diacrylate, trimethylolpropane triacrylate, di-trimethylolpropane tetra-acrylate, di-pentaerythritol pentaacrylate.

Polyether acrylates include ethoxylated trimethylol propane triacrylate, glycerol propoxylate triacrylate, ethoxylated pentaerythritol tetraacrylate.

Epoxy acrylates include dianol diacrylate (= the diacrylate of 2, 2-bis [4-(2-hydroxyethoxy) phenyl] propane, e.g. Ebecryl 150 from UCB) and glycol diacrylates such as tripropylene glycol diacrylate, epoxidized soy bean oil acrylate.

Preferably the photo-curable compositions contain at least one synergist.

Suitable synergists include but are not limited to 2-ethylhexyl-4-dimethylamino benzoate, ethyl 4-(dimethylamine) benzoate, N-methyl diethanolamine, 2-dimethylamino ethylbenzoate, butoxyethyl-4-dimethylamino benzoate, as well as C373, CN383, CN384, CN386 and CN 371, all available from Sartomer; Ebecryl PI 04, Ebecryl PI 15, Ebecryl 7100 all available from Allnex; and Roskydal UA XP 2299 available from Bayer, or the acrylated synergists such as Genomer 5142 and Genomer 5161 available from Rahn. Further components which may be additionally present in the photo-curable compositions or not are:

• isocyanates and/or polyisocyanates

• flattening agents

· matting agents,

• defoamer

• anti-friction agents such as silicon containing antifriction agents,

• surfactants

• resins such as formaldehyde resins, polyurethan resins, polyacrylates, cellulosic resins and sucrose benzoate

• further photoinitiators, including but not limited to Norrish Type I initiators such as 2- hydroxy- 1 - {4- [4-(2-hydroxy-2-methyl-propionyl)-benzyl] -phenyl} -2-methyl-propan- 1 - one (Irgacure 127), 2-hydroxy-l-[4-(2-hydroxyethoxy)-phenyl] -phenyl] -2- methylpropan-l-one (Irgacure 2959), 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), 2-hydroxy-2-methyl-l -phenyl- 1-propanone (Irgacure 1173), benzildimethylketal and oligo[2-hydroxy-2-methyl-l-[4-(l-methylvinyl)phenyl]propanon e] (Esacure KIP 150 from Lamberti) as well as mono- or bisacylphosphinoxides such as phenyl - bis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl-(2,4,6- trimethylbenzoyl)phosphine oxide and ethyl-(2,4,6-trimethylbenzoyl)phenyl phosphinate.

Although the compounds of the present invention are especially useful as photoinitiators for use in the production of varnishes, they may also be used with advantage in many other kinds of energy-curable coating compositions. For example, although yellowing is not such a problem with printing inks, it may still be advantageous to have a photoinitiator which does not result in yellowing on cure or on ageing, since this gives the ink formulator a much greater degree of freedom in choosing the other ingredients of the ink, including the pigment.

The amounts of ethylenically unsaturated components, photoinitiators, and optional other ingredients will vary according to the type of composition, the particular equipment to be used to apply it and the application. However, typically, the amount of photoinitiator within the composition is in the range of from 0.5 to 12 wt.-%, preferably 2 to 10 wt.-%, more preferably 4 to 9 wt.-%. In particular where isocyanates and/or polyisocyanates are intended to be used as further component the compounds of formula (I) or the mixtures comprising compounds of formula (IV) are of particular advantage since they are capable of reacting with isocyanates.

Therefore a further aspect of the invention relates to compounds obtainable by reaction of compounds of formula (I) or mixtures comprising compounds of formula (IV) with isocyanates and/or polyisocyanates.

As used herein, the term polyisocyanates encompasses polyisocyanates comprising isocyanurate groups, uretdiondiisocyanates, polyisocyanates comprising biuret groups, polyisocyanates comprising urethane and/or allophanate groups, polyisocyanates comprising oxadiazintrione groups.

Specific examples of isocyanates and polyisocyanates include compounds of formulae (Va), (Vb) and (Vc)

OCN-R ⁵ -NCO (Va)

OCN-R ⁵ -NH(CO)-N[(CO)NHR ⁵ -NCO]- R ⁵ -NCO (Vb)

[OCN-R ⁵ -N(CO)] ₃ (Vc)

wherein

R ⁵ is a divalent hydrocarbon group having from 1 to 20 carbon atoms, preferably 2 to 13 carbon atoms, and in an exemplary embodiment 6 carbon atoms such as 1,6-hexanediyl or 13 carbon atoms such as 4,4'-dicyclohexylmethyl.

In one embodiment the compounds of formula (I) or the specific mixtures comprising compounds of formula (IV) as specified above or the mixture obtainable by the process according to the invention may directly be reacted within the photo-curable composition, thus omitting a separate reaction and isolation or workup step. The ethylenically unsaturated compounds such as acrylates may serve as diluent and component of the photo-curable composition simultaneously. The invention further relates to a process for preparing a cured composition by exposing the photo-curable compositions according to the present invention to electromagnetic radiation, preferably ultraviolet radiation.

Suitable sources of electromagnetic radiation UV lamps like low-pressure, medium-pressure, high-pressure and super-high-pressure mercury lamps which can be undoped or doped e.g. with gallium iodide, thallium iodide or other metal halides; blue, violet-blue or UV-LEDs; concentrated, direct or indirect sunlight; xenon or xenon mercury arc lamps such as continuous- output xenon short- or long-arc lamps, flash lamps such as xenon or xenon mercury flash lamps; microwave-excited metal vapour lamps; excimer lamps, superactinic fluorescent tubes; fluorescent lamps; and noble gas incandescent lamps.

Preferred sources are UV lamps like low-pressure, medium-pressure, high-pressure and super- high-pressure mercury lamps which can be undoped or doped e.g. with gallium iodide, thallium iodide or other metal halides; blue, violet-blue or UV-LEDs, xenon or xenon mercury arc lamps such as continuous -output xenon short- or long-arc lamps.

Specific examples include H-UV lamps from Komori and LE-UV lamps from 1ST.

The cured compositions may be produced by all printing methods known to those skilled in the art including flexography, rotagravure, roller printing and screen printing, ink jet whereby the printed materials include paper, board, paperboard, plastic films and articles e.g. from polypropylene, polyethylene, polyethyleneterephthalate, polyvinylchloride, polystyrene, aluminium, would, laminate, tin or other metals, multi-layer substartes, or mixtures thereof,

Said printed materials are particular useful to be applied in articles comprising said printed materials e.g. fine arts, pictures, newspapers, magazines, packaging, in particular packaging for food, tobacco and tobacco products, cosmetics, pharmaceuticals and the like.

The photo-curable compositions may also be used in other fields where UV-curing technologies are applied, such as other coating techniques like roller coating, curtain coating, spray coating, 3-D printing, molding compounds and the like.

The invention therefore encompasses printed materials comprising the cured compositions according to the invention and articles comprising said printed materials.

The advantage of the invention is that the compounds provided based on readily available compounds of formula (II) as starting materials meet the high solubility in coating formulations, especially UV-curable formulations, very good reactivity and in some cases significantly higher reactivity than some of the commonly used benzophenone derivatives commercially available today. The claimed photoinitiators are easy processible since liquid and available via a versatile and efficient process. They further exhibit a much lower tendency to migrate and be extracted than most benzophenone derivatives in particular when reacted with other components of classical photo-curable compositions. The invention is hereinafter further explained by the examples without being limited thereto. Experimental section:

Example 1

In a reactor 1,000 kg [5.05 mol] of 4-hydroxybenzophenone were placed in a reaction vessel and 600 wt.-ppm KOH based on 4-hydroxybenzophenone were added. The reaction chamber was flushed with nitrogen. The mixture was reacted with 3.5 molar equivalants of ethylene oxide at temperatures of 130 to 150°C for 5 hours at pressures of max. 0,6 MPa.

The crude reaction mixture was analyzed by GC. The composition of the reaction mixture obtained thereby is listed in table 1.

*noise calibrated

The amount of compounds of formula (I, IV) (3 < q < 5) was 75.51 wt.-%. Further compounds of formula (I, IV) could be detected having up to 10 EO units, however their combined intensities were lower than 2 wt.-% based on the sum (100 wt.-%) of compounds indicated in table 1. Compounds having more than 10 EO units were not detected. None of the single compounds of formula (I, IV) had a share of 50 wt.-% or more. The amount of compounds of formula (I, IV) in the mixture of compounds of formula (I, IV) was above 90 wt.-%. The amount of compounds of formula (I,IV) with any t being 5 or more (q > 5) was less than 11 wt.-%.

The product appeared as a yellowish liquid having a viscosity of 2.5 Pa*s at 23°C as measured by Thermo HAAKE Rheostress RS 1.

An analogous reaction with propylene oxide resulted in a mixture of very similar composition having a viscosity of 1.86 Pa*s.

Both products showed superior processability and long term stability when employed in photocurable compositions. The 4-benzophenonecarboxylic esters disclosed in EP 2 394 676 Al and commercially available under the tradename Genopol BP exhibits a viscosity of around 100 Pa*s.

Another product commercially available under the tradename Omnipol exhibits a viscosity of 200 Pa*s.

Example 2

In order to decompose the ketals 1 g of the mixture obtained according to example 1 was dissolved in 50 ml tetrahydrofurane: water 1 : 1 (v/v) and stirred for 24 h at room temperature after addition of 50 mg para-toluene sulfonic acid.

After addition of 100 ml of toluene, the organic phase was seperated, washed with brine, dried with magnesium sulfate and the solvent evaporated. No acetals could be detected by GC any more.

Example 3

20 grams (about 58 mmol) of the crude reaction mixture of example 1 and 0.1 g of DABCO (l,4-diazabicyclo[2.2.2]octane) were dissolved in lOg of propoxylated glycerol triacrylate (OTA 480, Cytec). 7.8 g H12MDI (4,4'-Diisocyanatodicyclohexylmethane) were added and the reaction temperature controlled at 60°C for about 6h. The reaction product obtained was obtained as a highly viscous, pale brown liquid. Example 4 20g (about 58 mmol) of the mixture obtained according to Example 1 and 8.4g (92 mmol) acryloylchloride were dissolvedjn 120 mL tetrahydrofurane (THF) at room temperature. 9.37g (93mmol) triethylamine were added dropwise over a period of 5h. The mixture was neutralized by adding 5mL HC1 (35% in H ₂ 0) and 200 mL water were added. After seperating the layers, the organic phase was washed with 3 times with saturated NaCl solution, dried with MgS0 ₄ and the solvent was evaporated under reduced pressure.

The originally present respective ketals were found to fully react to form the respective non- ketalized acyloylesters, while the ethylene glycol released formed the respective ethylene glycol diacrylate.

Yield: 92 % of theory.

The mixture obtained showed neglectable signals of non-acrylated substance in MALDI-TOF measurements. The viscosity of the mixture was found to be even lower than the viscosity of the starting material (1.17 Pa*s at 23°C).

Example 5

68g (202mmol) of the mixture obtained according to example 1 were dissolved in 400 mL tetrahydrofurane ( THF) and 22g (108mmol) terephtaloyl chloride were added under stirring. 25g (247 mmol) triethylamine were dissolved separately in 70mL THF and the solution was added dropwise to the reaction mixture over a period of 3h and the mixture was further stirred for 4h. To the mixture 700mL distilled water and 20mL HC1 (35%) were added. After seperating the layers, the organic phase was washed with 3 times with saturated NaCl solution, dried with MgS0 ₄ and the solvent was evaporated under reduced pressure.

Yield: 90% of theory.

The IR spectrum did not show any broad OH-signal anymore at 3464 cm Hndicating complete conversion. A strong signal for the ester resonance at 1716cm ^"1 was detected.

Example 6 - Reactivity Comparison

The reacticvity of the mixture obtained according to Example 1 was tested in equal wt.- amounts versus Omnipol BP and Genopol BP and other benzophenones. The tested varnish was formulated as follows:

Genomer 5161 (Rahn AG) 9.21 parts, OTA-480 (Allnex) 55.25 parts; Miramer M300 (Rahn AG) 27.62 parts, Irgacure 127 (BASF) 0.92 parts, Tego Rad 2011 (Evonik Industries) 0.46 parts; Photoinitiator (Example 1 or Omnipol BP or Genopol BP) 6.54 parts.

For comparison with low molecular weight benzophenone-derivatives only 4 parts were used to reflect comparison of actual chromophore concentration.

Parts refer to parts by weight.

The mixture according to example 1 showed superior behavior in mixing and homogenizing compared to the more viscuous Omnipol BP and Genopol BP.

On a black printed carton the varnish was applied in about 4g/m ² and passed under a UV

Hg-lamp 200 W/cm, 50% in tensity) at 80m/min. several times. The curing was determined by applying fine talcum powder on the surface and carefully wiping it of. The sample was fully cured when no talcum powder sticked to the surface. The number of passes for each varnish is given in table 1.

Varnish Number of passes until fully cured

Varnish with Genopol BP 6

Varnish with Omnipol BP 4

Varnish with Mixture of Example 1 4

Varnish with 4-Hydroxybenzophenone 7

Example 7 - Leaching behaviour: Varnishes comprising of same components as in example 6 with Omnipol BP, Genopol BP, the mixtures of examples 1, and in two further runs the mixtures of examples 3 and 4 were each applied with 10g/m ² on a polyester foil an passed under a standard mercury lamp (200 W/cm) with 20m/min. 1 dm ² of the sample was extracted with Ethanol (95 vol.-%) for 24h at room temperature and the extracted amount of photoinitiator was determined accordingly. The following leaching rates were found: Genopol BP: 50 μg/ dm ²

Omnipol BP: 39 dm ²

Mixture of Example 1 *: 1445 μg/ dm ²

Mixture of Example 3*: 37 μg/ dm ²

Mixture of Example 4**: 10 μg/ dm ²

* measured amount of compounds of Example 1)

** measured amount of compounds of Example 4).

Example 4 was detected in significant lower amounts than compared to all other tested photoinitiators despite having a comparably low molecular weight which indicates superior usability in application such as food packaging were low leaching levels are more than desirable.

Example 8

In a reactor 20g [88mmol] of 2-hydroxythioxanthen-9-one were placed in a reaction vessel and 600 wt.-ppm KOH (based on 2-hydroxythioxanthen-9-one) were added together with 100 g isoaliphatic naphta. The reaction chamber was flushed with nitrogen. The mixture was reacted with 3.5 molar equivalants of ethylene oxide at temperatures of 130 to 150°C for 3 hours at pressures of max. 0,6 MPa. The crude reaction mixture was analyzed by MALDI-TOF.:

Mn=460 was calculated based on the mass count distribution