POLYCYCLIC GLYOXYLATES AS PHOTOINITIATORS

Abstract

The present invention relates to photoinitiator compounds of the formula (1) wherein X is O, S or a direct bond; Y is O, S or CR.sub.9R.sub.10; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.18alkyl, C.sub.5-C.sub.10cycloalkyl, C.sub.2-C.sub.18alkenyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4-alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (2) provided that one or more than one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2); R.sub.9, R.sub.10 independently of each other are hydrogen, C.sub.1-C.sub.18alkyl, C.sub.2-C.sub.12alkenyl, C.sub.5-C.sub.10ocycloalkyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring; and R.sub.11 is hydrogen, C.sub.1-C.sub.18alkyl, C.sub.5-C.sub.10cycloalkyl, C.sub.2-C.sub.12alkenyl, phenyl-C.sub.1-C.sub.4alkyl or phenyl.

##STR00001##

Claims

1. A photopolymerizable composition comprising: (A) at least one ethylenically unsaturated photopolymerizable compound and (B) at least one photoinitiator compound of formula (1) ##STR00036## wherein X is O, S or a direct bond; Y is O, S or CR.sub.9R.sub.10; R.sub.1, R.sub.2, R.sub.3, Ra, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.18alkyl, C.sub.5-Ciocycloalkyl, C.sub.2-C.sub.18alkenyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4-alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (2) ##STR00037## provided that one or more than one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2); R.sub.9, R.sub.10 independently of each other are hydrogen, C.sub.1-C.sub.18alkyl, C.sub.2-C.sub.12alkenyl, C.sub.5-C.sub.10cycloalkyl, phenyl-C.sub.1-Caalkyl, phenyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring; and R.sub.11 is hydrogen, C.sub.1-C.sub.18alkyl, C.sub.5-C.sub.10cycloalkyl, C.sub.2-C.sub.12alkenyl, phenyl-C.sub.1-C.sub.4alkyl or phenyl.

2. The photopolymerizable composition according to claim 1, wherein the photoinitiator of formula (1) is a compound of formula (3): ##STR00038## wherein; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.6, R.sub.9, and R.sub.10 are as defined in claim 1.

3. A The photopolymerizable composition according to claim 1 or 2, wherein: (i) one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2); or (ii) one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 is a group of formula (2) and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2).

4. The photopolymerizable composition according to claim 1, wherein R.sub.1 to R.sub.4 and R.sub.5 to R.sub.8 being different from a group of formula (2) are independently of each other hydrogen, halogen, C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy, C.sub.1-C.sub.4alkylthio, N-morpholinyl or N-piperidinyl.

5. The photopolymerizable composition according to claim 1, which additionally to the component (B) comprises: (x) at least one further photoinitiator (C); (xi) at least one further coinitiator (D); (xii) at least one other additive (E); or (xii) a combination of (x) and (xi) or a combination of (x) and (xii) or a combination of (x) and (xi) and (xii).

6. A The photopolymerizable composition according to claim 1, which comprises 0.05 to 15% by weight , of the photoinitiator compound of formula (1), based on the total composition.

7. A process for the photopolymerization of monomeric, oligomeric or polymeric compounds containing at least one ethylenically unsaturated double bond, which comprises: adding to the monomeric, oligomeric or polymeric compounds at least one photoinitiator of formula (1); ##STR00039## wherein; X is O, S or a direct bond; Y is O, S or CR.sub.9Rio; R.sub.1, R.sub.2, R.sub.3, Ra, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently of each other are hydrogen, halogen, C.sub.1-C.sub.18alkyl, C.sub.5-C.sub.10cycloalkyl, C.sub.2-C.sub.18alkenyl, phenyl, C.sub.1-C.sub.4alkoxy, C.sub.5-C.sub.7cycloalkoxy, phenoxy, C.sub.1-C.sub.4-alkylthio, C.sub.5-C.sub.7cycloalkylthio, phenylthio, di(C.sub.1-C.sub.4alkyl)amino, di(C.sub.5-C.sub.7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (2) ##STR00040## provided that one or more than one of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2); R.sub.9, R.sub.10 independently are hydrogen, C.sub.1-C.sub.18alkyl, C.sub.2-C.sub.12alkenyl, C.sub.5-C.sub.10cycloalkyl, phenyl-C.sub.1-C.sub.4alkyl, phenyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring; and R.sub.11 is hydrogen, C.sub.1-C.sub.18alkyl, C.sub.5-C.sub.10cycloalkyl, C.sub.2-C.sub.12alkenyl, phenyl-C.sub.1-C.sub.4alkyl or phenyl; and irradiating the resulting composition with electromagnetic or particulate radiation.

8. A The process according to claim 7, wherein the at least one photoinitiator of formula (1) is a compound of formula (3): ##STR00041## wherein: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, and R.sub.10 are as defined in claim 7.

9. The process according to claim 7 wherein the monomeric, oligomeric or polymeric compounds and the at least one photoinitiator are provided in a preparation of pigmented and nonpigmented paints and varnishes, powder coatings, printing inks, screen printing inks, inks for offset-, flexo- or inkjet printing, printing plates, adhesives, sealings, potting components, dental compositions, foams, moulding compounds, composite compositions, glass fibre cable coatings, screen printing stencils, compositions for producing three-dimensional objects by means of stereolithography, image recording material, photoresist compositions, decolorizing materials, decolorizing materials for image recording materials, or image recording materials using microcapsules.

10-12. (canceled)

13. A coated substrate coated on at least one surface with a composition according to claim 1.

14. Article comprising a polymerized or crosslinked composition obtained by curing a polymerizable composition according to claim 1.

15. The photopolymerizable composition according to claim 2, wherein R.sub.9, and R.sub.10 independently are hydrogen, C.sub.1-C.sub.18alkyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring; and R.sub.11 is C.sub.1-C.sub.18alkyl.

16. The photopolymerizable composition according to claim 2, wherein; R.sub.9, R.sub.10 independently are hydrogen or methyl; and R.sub.11 is methyl or ethyl.

17. The photopolymerizable composition according to claim 3, wherein; R.sub.1 to R.sub.4 and R.sub.5 to R.sub.8 being different from a group of formula (2) are hydrogen.

18. The photopolymerizable composition according to claim 6, which comprises 0.1 to 10% by weight of the photoinitiator compound of formula (1).

19. The process according to claim 8, wherein; (i) one of R.sub.1, R.sub.2, R.sub.3, Ra, R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2); or (ii) one of R.sub.1, R.sub.2, R.sub.3 or R.sub.4 is a group of formula (2) and one of R.sub.5, R.sub.6, R.sub.7 or R.sub.8 is a group of formula (2)

20. The process according to claim 8, wherein R.sub.1 to R4 and R.sub.5 to R.sub.8 are different from a group of formula (2) are independently of each other hydrogen, halogen, C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy, C.sub.1-C.sub.4alkylthio, N-morpholinyl or N-piperidinyl.

Description

A) SYNTHESIS EXAMPLES

Example 1

Ethyl 2-[7-(2-ethoxy-2-oxo-acetyl)-9H-xanthen-2-yl]-2-oxo-acetate (compound 1)

[0123] ##STR00023##

[0124] Xanthene (15.03 g, 0.082 mol) was dissolved in 65 g of 1,2-dichloroethane and cooled in an ice bath. Aluminium chloride (54.40 g, 0.408 mol) was then added under stirring to form a brown solution. Within 1 hour a solution of ethyl chlorooxoacetate (48.10 g, 0.352 mol) in 28 g of 1,2-dichloroethane was charged at 5 C. The resulting mixture was stirred for 20 hours at 20 C. and was thereafter slowly poured into a stirred mixture of 254.2 g of ice, 254.8 g of water, 51.6 g of 32% hydrochloric acid and 170.0 g of 1,2-dichloroethane. The organic layer was separated, washed twice with 50 mL of water, dried over Na2SO4 and evaporated. The residue was dissolved in 40 g of ethyl acetate, washed twice with 50 mL of water, dried over Na.sub.2SO.sub.4, filtrated over a small pad of silica gel and evaporated to afford 4.2 g of compound 1 as a yellowish solid, mp. 103-109 C.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.41 (t, 6H), 4.20 (s, 2H), 4.48 (q, 4H), 7.20 (d, 2H), 7.94-7.96 (m, 4H).
.sup.13C-NMR (75.5 MHz, CDCl.sub.3), [ppm]: 14.1, 27.14, 62.5, 117.5, 120.3, 128.3, 131.6, 134.8, 155.9, 163.8, 184.4.

[0125] UV-Vis (acetonitrile): .sub.max=322 nm.

Example 2

Ethyl 2-(9,9-di methylxanthen-2-yl)-2-oxo-acetate (compound 2)

[0126] ##STR00024##

[0127] 9,9-Dimethyl xanthene (4.50 g, 21 mmol) was dissolved in 37.5 g of 1,2-dichloroethane. Ethyl chlorooxoacetate (6.14 g, 45 mmol) was added at room temperature. The resulting yellow mixture was cooled to -5 C. Aluminium chloride (6.28 g, 47 mmol) was then added under stirring to form a dark red solution. After stirring for 20 hours at 23 C. an additional amount of ethyl chlorooxoacetate (0.64 g, 4.6 mmol) was added and reaction continued at room temperature. A TLC analysis after 2 hours indicated full conversion of 9,9-dimethyl xanthene. The mixture was then slowly poured into 150 g of ice under stirring. After addition of 50 mL of 1,2-dichloroethane and 150 mL of water the organic layer was separated, washed with 150 mL of water, dried over MgSO.sub.4 and evaporated. Column chromatography (55 g of silica gel, eluent 1:500 mL of ethyl acetate, eluent 2: dichloromethane) afforded 0.5 g of compound 3 and 2.5 g of the desired compound 2.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.46 (t, 3H), 1.72 (s, 6H), 4.48 (q, 2H), 7.08-7.11 (m, 1H), 7.14-7.18 (m, 2H), 7.23-7.28 (m, 1H), 7.45 (d, 1H), 7.89 (d, 1H), 8.21 (s, 1H).

Example 3

Ethyl 2-[7-(2-ethoxy-2-oxo-acetyl)-9,9-dimethyl-xanthen-2-yl]-2-oxo-acetate (compound 3)

[0128] ##STR00025##

[0129] Compound 2 (2.45 g, 8 mmol) was dissolved in 32.3 g of 1,2-dichloroethane and 1 g of sulfolane. A solution of ethyl chlorooxoacetate (4.38 g, mmol) dissolved in 4.13 g of 1,2-dichloroethane was added at room temperature. The resulting greenish mixture was cooled to 3 C. Aluminium chloride (2.38 g, 18 mmol) was then added under stirring to form a dark red mixture. After stirring for 20 hours at 23 C. an additional amount of aluminium chloride (4.00 g, 30 mmol) was added and the reaction mixture stirred for 30 hours at room temperature. The mixture was then slowly poured into 150 g of ice under stirring. After addition of 30 mL of 1,2-dichloroethane and 90 mL of 32% hydrochloric acid the organic layer was separated, washed twice with 100 mL of brine, dried over MgSO.sub.4 and evaporated. Column chromatography (30 g of silica gel, eluent:cyclohexane/ethyl acetate 9.5:0.5) afforded 1.0 g of the title compound as a yellowish solid.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.46 (t, 6H), 1.72 (s, 6H), 4.49 (q, 4H), 7.20 (d, 2H), 7.94 (dd, 2H), 8.22 (d, 2H).
.sup.13C-NMR (75.5MHz, CDCl.sub.3), [ppm]: 14.1, 32.9, 34.2, 62.4, 117.4, 128.8, 129.5, 130.3, 130.7, 154.3, 163.7, 184.6.

[0130] UV-Vis (MeOH): .sub.max=319 nm.

Example 4

Ethyl 2-oxo-2-thianthren-2-yl-acetate (compound 4)

[0131] ##STR00026##

[0132] Compound 4 was prepared from thiantrene in analogy to compound 2 in 68% yield.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.44 (t, 3H), 4.47 (q, 2H), 7.25-7.29 (m, 2H), 7.44-7.50 (m, 2H), 7.57 (d, 1H), 7.89 (d, 1H), 8.11 (s, 1H).
(compound 5)

##STR00027##

[0133] 0.1g of compound 5 in form of a yellow solid were isolated during column chromatography as a by-product, mp =123-129 C.

[0134] UV-Vis (Ethyl acetate): .sub.max=288 nm and 327 nm.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.45 (t, 6H), 4.47 (q, 4H), 7.60 (d, 2H), 7.95 (d, 2H), 8.11 (s, 2H).

Example 5

Ethyl 2-[8-(2-ethoxy-2-oxo-acetyl)thianthren-2-yl]-2-oxo-acetate (compound 5)

[0135] ##STR00028##

[0136] Aluminium chloride (37.00 g, 277 mmol) was added in portions into a mixture of ethyl chlorooxoacetate (34.70 g, 254 mmol) and sulfolane (0.60 g) in 100 g of 1,2-dichloroethane. A solution of thiantrene (10.00 g, 46 mmol) in 120 g of 1,2-dichloroethane was added into the red-orange mixture within 1 hour and stirred at room temperature. A TLC analysis indicated a full conversion of thiantrene after 1 hour. The reaction mixture was poured into water/ice under stirring. The organic layer was separated, washed three times with water and evaporated. After column chromatography (silica gel, eluent: cyclohexane/ethyl acetate 9:1) the crude product was obtained. A second column chromatography (silica gel, eluent: toluene/cyclohexane 1:1) was performed to isolate 0.40 g of the desired compound 5 as a yellowish solid, mp =123-129 C.

[0137] UV-Vis (Ethyl acetate): .sub.max=288 nm and 327 nm.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.45 (t, 6H), 4.47 (q, 4H), 7.60 (d, 2H), 7.95 (d, 2H), 8.11 (s, 2H).

Example 6

Ethyl 2-[8-(2-ethoxy-2-oxo-acetyl)dibenzo-p-dioxin-2-yl]-2-oxo-acetate and/or ethyl 2-[7-(2-ethoxy-2-oxo-acetyl)dibenzo-p-dioxin-2-yl]-2-oxo-acetate (compound 6)

[0138] ##STR00029##

[0139] Ethyl chlorooxoacetate (74.7 g, mol) and 0.6 g of sulfolane were dissolved in 100 g of 1,2-dichloroethane. Aluminium chloride (37.0 g, mol) was added carefully in portions resulting in a red-orange mixture. A solution of dibenzodioxine (5.0 g, 0.03 mol) in 120 g of 1,2-dichloroethane was added within 1 hour. The resulting blue-violet mixture was stirred for 1.5 hours at 25 C. and was then poured into a stirred mixture of 150 g of ice, 100 g of water and 50 g of 32% hydrochloride acid.

[0140] The organic layer was separated, washed three times with water and dried over Na.sub.2SO.sub.4. The solvents were evaporated under vacuum yielding 11.4 g of the crude product which still contained residual sulfolane. By taking up the crude product in 1,2-dichloroacetate and washing twice with water (150 g and 80 g) the residual amounts of sulfolane were removed. The organic phase was dried over Na.sub.2SO.sub.4 and evaporated. The residue (11 g) was purified by column chromatography (100 g of silica gel, eluent: cyclohexane:ethyl acetate 4:1) to afford 6.0 g of compound 6 as yellowish crystals, mp 133-138 C.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.44 (t, 6H), 4.46 (q, 4H), 6.99 (dd, 2H), 7.62 (s, 2H), 7.71 (d, 2H).
.sup.13C-NMR (75.5MHz, CDCl.sub.3), [ppm]: 14.1, 62.5, 116.9, 118.1, 128.1, 129.1, 141.4, 146.9, 163.1, 183.6.

[0141] UV-Vis (ethyl acetate): .sub.max=288 nm, 326 nm.

Example 7

Ethyl 2-[8-(2-ethoxy-2-oxo-acetyl)phenoxathiin-2-yl]-2-oxo-acetate (compound 7)

[0142] ##STR00030##

[0143] Compound 7 was prepared from phenothriazine in analogy to compound 1 in 2.3% yield. Brown-reddish, strong viscous oil.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.45 (t, 6H), 4.67 (q, 4H), 7.11 (d, 2H), 8.10-8.15 (m, 4H).

Example 8

Ethyl 2-oxo-2-[8-(2-oxopentanoyl)dibenzofuran-2-yl]acetate (compound 8)

[0144] ##STR00031##

[0145] Compound 8 was prepared from dibenzofurane in analogy to compound 1. Colorless solid

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.50 (t, 6H), 4.54 (q, 4H), 7.76 (d, 2H), 8.30 (d, 2H), 8.79 (s, 2H).

[0146] UV-Vis (Ethyl acetate): .sub.max=257 nm and 287 nm.

Example 9

Ethyl 2-[9,9-dimethyl-7-(2-oxopentanoyl)fluoren-2-yl]-2-oxo-acetate (compound 9)

[0147] ##STR00032##

[0148] Dimethylfluorene (4.93 g, 26 mmol) and aluminium chloride (21.00 g, 154 mmol) were mixed in 200 g of 1,2-dichloroethane and 0.34 g of sulfolane. Ethyl chlorooxoacetate (19.36 g, 142 mmol) was added under stirring. The resulting black reaction mixture was stirred at room temperature. A TLC analysis after 2.5 hours indicated full conversion of dimethylfluorene. The reaction mixture was thereafter slowly poured into a stirred mixture of 300 g of ice/water. After addition of 50 mL of 1,2-dichloroethane and 1 L of water the organic layer was separated, dried over MgSO.sub.4 and evaporated. The residue (9.27 g) was purified by column chromatographie (120 g silica gel, eluent 1: toluene/cyclohexane 7:3, eluent 2: toluene/ethyl acetate 9.5:1.5) yielding 4.5 g of the crude product. Another purification by column chromatography (65 g silica gel, eluent 1: toluene, eluent 2: toluene/ethyl acetate 9:1) was performed to yield 4.63 g of compound 9 as a dark yellow, very viscous oil.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.46 (t, 6H), 1.61 (s, 6H), 4.51 (q, 4H), 7.93 (d, 2H), 8.05 (d, 2H), 8.17 (s, 2H). UV-Vis (acetonitrile): .sub.max=333 nm.

Example 10

Ethyl 2-oxo-2-[7-(2-oxopentanoyl)-9H-fluoren-2-yl]acetate (compound 10)

[0149] ##STR00033##

[0150] Fluorene (15.00 g, 90 mmol) and sulfolane (1.16 g) were mixed in 100 mL of 1,2-dichloroethane. Aluminium chloride (42.20 g, 316 mmol) was added slowly under stirring. The resulting mixture was cooled to 0 C. Ethyl chlorooxoacetate (37.00 g, 271 mmol) was added within 90 minutes. The resulting red reaction mixture was stirred at room temperature for 24 hours. The reaction mixture was thereafter slowly poured onto ice and slowly warmed up to room temperature overnight. The organic layer was separated, washed three times with water and evaporated. The residue (9.27 g) was purified by flash chromatography (silica gel, eluent: hexane/ethylacetate 4:1) to afford 2.7 g of the title compound as a yellowish solid.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.46 (t, 6H), 4.50 (q, 4H), 7.83 (d, 2H), 8.00 (d, 2H), 8.14 (s, 2H).

[0151] UV-Vis (acetonitrile): .sub.max=335 nm.

Example 11

Ethyl 2-(9H-fluoren-2-yl)-2-oxo-acetate (compound 11)

[0152] ##STR00034##

[0153] Ethyl chlorooxoacetate (37.2 g, 270 mmol) and 1.10 g of sulfolane were mixed in 200 mL of 1,2-dichloroethane. Aluminium chloride (42.10 g, 316 mmol) was added at 5 C. slowly in portions. A solution of fluorene (15.0 g, 90 mmol) in 80 mL of 1,2-dichloroethane was added carefully. The resulting red mixture was stirred for 4.5 hours at 25 C. and was then poured into a stirred mixture of 100 g of ice, 150 g of water and 50 g of 32% hydrochloride acid.

[0154] The organic layer was separated, washed twice with water and dried over Na2SO4. The solvents were evaporated under vacuum. The residue (28.6 g) was purified by column chromatography (silica gel, heptane : ethyl acetate 9:1) to afford 18.4 g of the crude product. The crude product was further purified by column chromatography (silica gel, heptane/toluene 7:3) to afford 15 g of compound 11 as an off-white solid.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.48 (t, 3H), 3.98 (s, 2H), 4.51 (q, 2H), 7.38-7.50 (m, 2H), 7.62 (d, 1H), 7.88 (d, 2H), 8.07 (d, 1H), 8.20 (s, 1H).
.sup.13C-NMR (75.5MHz, CDCl.sub.3), [ppm]: 14.2, 37.0, 62.3, 120.0, 121.3, 125.4, 126.6, 127.2/128.7, 129.7, 130.8, 143.5, 144.7, 148.4, 164.3, 186.3.

[0155] UV-Vis (acetonitrile): .sub.max=324 nm.

Example 12

Ethyl 2-dibenzofuran-2-yl-2-oxo-acetate (compound 12)

[0156] ##STR00035##

[0157] Ethyl chlorooxoacetate (24.4 g, 270 mmol) and 1.0 g of sulfolane were mixed in 200 mL of 1,2-dichloroethane. Aluminium chloride (27.8 g, 316 mmol) was added at 0 C. slowly in portions. A solution of dibenzofurane (10.0 g, 90 mmol) in 50 mL of 1,2-dichloroethane was added carefully. The resulting red mixture was stirred for 1 hour at 5 C. and was then poured into a stirred mixture of 150 g of ice, 100 g of water and 50 g of 32% hydrochloride acid.

[0158] The organic layer was separated, washed twice with water and once with brine. The solvents were evaporated under vacuum. The residue was dissolved in ethyl acetate and the resulting organic phase was washed twice with water and once with brine. The solvents were evaporated under vacuum. The residue (13.5 g) was purified twice by column chromatography (column 1: silica gel, heptane : ethyl acetate 9:1; column 2: silica gel, heptane : toluene 7:3) to afford 3.9 g of the title compound as an off-white solid.

.sup.1H-NMR (400 MHz, CDCl.sub.3), [ppm]: 1.49 (t, 3H), 4.54 (q, 2H), 7.40-7.45 (m, 1H), 7.52-7.56 (m, 1H), 7.60-7.65 (m, 2H), 8.02 (d, 2H), 8.18 (d, 1H), 8.68 (s, 1H). UV-Vis (acetonitrile): A.sub.max=260 nm, 276 nm, 312 nm (shoulder).

B) Application Examples

Materials

[0159] photoinitiator Irgacure 819 from BASF SE [0160] photoinitiator Irgacure TPO from BASF SE [0161] photoinitiator Irgacure TPO-L from BASF SE [0162] photoinitiator SpeedCure CPTX from Lambson Ltd [0163] polymeric amine modified polyether acrylate Laromer PO 9139 from BASF SE [0164] trifunctional monomer acrylate Laromer LR 8863 from BASF SE [0165] substrate Melinex 506 transparent polyester film with a thickness of 175 m from DuPont Teijin Films [0166] spiral bar coater from BYK-Gardner GmbH for realizing a theoretical wet film thickness of 6 m

Equipment

[0167] conveyor belt driven UV dryer from IST METZ GmbH equipped with a FirePower FP300 UV LED from Phoseon having an emission wavelength of 365 nm and an irradiance of 12 W/cm.sup.2 (gap UV LEDsubstrate surface always adjusted to 10 mm) [0168] conveyor belt driven UV dryer from IST METZ GmbH equipped with a medium pressure mercury lamp M-300-U2H from IST METZ GmbH with an electrical input power of 200 W/cm [0169] colorimeter LICO 200 from Dr. Bruno Lange [0170] I.C.I. cone & plate viscometer from Research Equipment Ltd

Test Methods

[0171] reactivity was determined as the conveyor belt speed of the UV dryer, where immediately after UV curing under air the film could not be damaged anymore by scratching with a fingernail [0172] MEK (methyl ethyl ketone) resistance was determined for films 24 h after UV curing as the number of double rubs with a cotton pad soaked with MEK causing no visible damage of the film surface anymore [0173] viscosity was measured at 23.0 C. and a shear rate of 10000 sec.sup.1 [0174] APHA color was evaluated by colorimetry

Test Formulations

[0175]

TABLE-US-00001 Test Test Test Test Test Test Formulation Formulation Formulation Formulation Formulation Formulation Component 1 2 3 4 5 6 Laromer 45.0% 45.0% 45.0% 45.0% 45.0% 45.0% PO 9139 (w/w) (w/w) (w/w) (w/w) (w/w) (w/w) Laromer 50.0% 50.0% 51.5% 50.0% 49.0% 50.0% LR 8863 (w/w) (w/w) (w/w) (w/w) (w/w) (w/w) Irgacure 5.0% TPO (w/w) Irgacure 5.0% TPO-L (w/w) Irgacure 3.5% 819 (w/w) SpeedCure 5.0% CPTX (w/w) Example 11 5.0% (w/w) Example 3 5.0% (w/w)

Characterization of Test Formulations

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TABLE-US-00002 Test Formulation Viscosity APHA Color 1 570 mPa .Math. s 369 2 580 mPa .Math. s 527 3 630 mPa .Math. s .sup.>900 4 580 mPa .Math. s .sup.>900 5 610 mPa .Math. s 711 6 700 mPa .Math. s 462

UV Reactivity and MEK Resistance of Test Formulations

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TABLE-US-00003 Test Formulation Radiation Source Reactivity MEK Resistance 1 365 nm UV LED .sup.<3 m/min 2 365 nm UV LED .sup.<3 m/min 3 365 nm UV LED .sup.<3 m/min 4 365 nm UV LED 45 m/min >200 double rubs 5 365 nm UV LED 10 m/min >200 double rubs 6 365 nm UV LED 10 m/min >200 double rubs

[0178] The inventive photoinitiators of Example 11 and Example 3 are promoting proper surface cure under UV LED radiation along with thioxanthone and 4,4-bis(dialkylamino)benzo-phenone derivatives being the only 2 commercially available photoinitiator classes up to now imparting surface cure under UV LED radiation. In contrast to that acylphosphine oxide photoinitiators known to provide through cure under UV LED radiation do not show any surface cure at all under the same conditions, even when corresponding prints were passed several times under the UV LED radiation source. These results were confirmed by MEK resistance tests, where the inventive photoinitiators resulted in excellent solvent resistance of the UV cured prints parallel to that of the thioxanthone and 4,4-bis(dialkyl-amino) benzophenone ones.

TABLE-US-00004 Test Formulation Radiation Source Reactivity MEK Resistance 1 medium pressure 65 m/min >200 double rubs mercury lamp 2 medium pressure 40 m/min >200 double rubs mercury lamp 3 medium pressure 40 m/min >200 double rubs mercury lamp 4 medium pressure 80 m/min >200 double rubs mercury lamp 5 medium pressure 80 m/min >200 double rubs mercury lamp 6 medium pressure 35 m/min >200 double rubs mercury lamp

[0179] The inventive photoinitiators of Example 11 and Example 3 are not only promoting proper surface cure under monochromatic UV LED radiation, but are also very reactive under a polychromatic medium pressure mercury lamp leading to excellent solvent resistance of corresponding UV cured prints as well.

Application Example in Photopolymer for 3D Printing

[0180] The inventive photoinitiators of Example 11 was tested at 1.5 wt-% in an acrylate-based photopolymer for 3D printing, e.g. stereolithography, consisting of two urethane acrylates and one monofunctional monomer. The polymerization heat and the glass transition temperature of the resulting polymer, shown in FIG. 1, were determined by means of photo-DSC and DSC (TGA/DSC 1, Mettler Toledo) after irradiation with a 365 nm LED (40 mW).

[0181] Test specimen (2 mm thickness) for determination of the mechanical properties (tensile test, DIN ISO 527-1, specimen type 5A, Zwick tensile testing equipment, speed 50 mm/min) of the cured polymer were prepared using home-made silicon molds in a two-step curing process: 1. pinning under UVA fluorescent tube (60 s, Sylvania Blacklight 368, F40W, T12, distance to sample 11 cm), 2. curing under 385 nm LED (two-sided curing, total UV dose 2500 mJ/cm.sup.2). The determined values are shown in the table below.

TABLE-US-00005 E modulus [MPa] Stress at break [MPa] Strain at break [%] 827 112 27 39