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EP-4555025-B1 - PHOTOINITIATOR PACKAGE COMPRISING SPECIALISED BISACYLPHOSPHINE OXIDE PHOTOINITIATORS, FURTHER ACYLPHOSPHINE OXIDE PHOTOINITIATORS AND OPTICAL BRIGHTENER SENSITIZERS

EP4555025B1EP 4555025 B1EP4555025 B1EP 4555025B1EP-4555025-B1

Inventors

  • MORONE, Marika
  • CREMONA, EMILIO
  • PASQUALI, Ilaria
  • CASATI, MARCO

Dates

Publication Date
20260513
Application Date
20241002

Claims (15)

  1. A photoinitiator package comprising, more preferably consisting of: a) one or more bisacylphosphine oxide photoinitiators, each having a structure according to formula (I): wherein each instance of R is independently selected from the group consisting of C 1 -C 4 alkyl; wherein X is selected from the group consisting of direct single bond, O, S, NR 3 , -CH 2 CO 2 -, and -CH 2 CH 2 CO 2 -; wherein R 1 is selected from the group consisting of C 1 -C 40 alkyl and interrupted C 2 -C 40 alkyl being interrupted by one or more O or C 3 -C 8 cycloalkylene, wherein said C 1 -C 40 alkyl or interrupted C 2 -C 40 alkyl may be unsubstituted or substituted by one or more groups selected from OH and R 2 ; wherein R 2 is wherein R 3 is selected from the group consisting of hydrogen, (CO)R 4 , phenyl, C 1 -C 12 alkyl, C 2 -C 12 alkyl being interrupted by one or more O, wherein said C 1 -C 12 alkyl or interrupted C 2 -C 12 alkyl is unsubstituted or substituted by one or more C 3 -C 7 cycloalkyl, OH or by NCO, C 3 -C 12 cycloalkyl which is unsubstituted or substituted by one or more C 1 -C 4 alkyl, C 1 -C 4 alkoxy, OH or by NCO; and wherein R 4 is selected from the group consisting of C 1 -C 12 alkyl or C 2 -C 12 alkyl which is interrupted by one or more O, wherein said C 1 -C 12 alkyl or interrupted C 2 -C 12 alkyl is unsubstituted or substituted by one or more C 3 -C 7 -cycloalkyl, OH, NCO or by phenyl which is substituted by NCO; C 3 -C 12 cycloalkyl; C 2 -C 10 alkenyl which is unsubstituted or substituted by one or more C 1 -C 4 alkyl, OH or C 1 -C 4 alkoxy; C 6 -C 14 aryl which is unsubstituted or substituted by C 1 -C 12 alkyl, C 1 -C 12 alkoxy, NCO or by NCO-substituted C 1 -C 12 alkyl. b) one or more further acylphosphine oxide photoinitiators having a structure not according to formula (I); c) one or more optical brightener sensitizers; and d) optionally one or more amines, wherein the photoinitiator package is a blend that is liquid at 25 °C and standard pressure.
  2. The photoinitiator package according to claim 1, wherein each instance of R is Me.
  3. The photoinitiator package according to either claim 1 or claim 2, wherein X is selected from the group consisting of direct single bond, O, -CH 2 CO 2 -, and -CH 2 CH 2 CO 2 -, more preferably is selected from the group consisting of direct single bond -CH 2 CO 2 -, and -CH 2 CH 2 CO 2 -, most preferably is a direct single bond.
  4. The photoinitiator package according to any one of the preceding claims, wherein R 1 is selected from the group consisting of C 1 -C 20 alkyl, -(CH 2 CH 2 O-) n CH 3 , and -(CH 2 CH 2 O-) n H, wherein n is an integer in the range from 1 to 20, more preferably R' is C 1 -C 20 alkyl.
  5. The photoinitiator package according to any one of claims 1 to 4, wherein R 1 has a structure according to formula (II): wherein each instance of M is independently selected from (CH 2 CH 2 O) and (CH 2 CH(CH 3 )O); wherein each instance of Y is independently selected from hydrogen and C 1 -C 4 alkyl; wherein each instance of Z has the structure CH 2 (M 1 ) c R 2 ; wherein each instance of M 1 is independently selected from (OCH 2 CH 2 ) and (OCH(CH 3 )CH 2 ) wherein a is an integer in the range from 0 to 15; wherein b is an integer in the range from 0 to 6; wherein each instance of c is independently an integer in the range from 0 to 15; wherein m is an integer in the range from 0 to 2; and wherein each instance of X is independently selected from the group consisting of -CH 2 CO 2 -, and -CH 2 CH 2 CO 2 -.
  6. The photoinitiator package according to any one of the preceding claims, wherein at least one of the one or more optical brightener sensitizers has a structure according to formula (III): wherein R 3a is selected from the group consisting of hydrogen, C 1 -C 10 alkyl, C 6 -C 14 aryl, and C 6 -C 14 heteroaryl, R 4a is selected from the group consisting of hydrogen, C 1 -C 10 alkyl, wherein said C 1 -C 10 alkyl may be substituted by one or more fluorine atoms, and OR 1a , and each of R 5a to R 8a is independently selected from the group consisting of hydrogen, halogen, C 1 -C 10 alkyl, OR 1a , and NR 2a 2 ; wherein each instance of R 1a is independently selected from hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl, and each instance of R 2a is independently selected from hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl, wherein each instance of R 1a to R 8a may optionally be joined to one or more further instances of R 1a to R 8a to form one or more 5-membered or 6-membered rings.
  7. The photoinitiator package according to any one of the preceding claims, wherein at least one of the one or more optical brightener sensitizers has a structure according to formula (IV): wherein each of R 1b to R 4b is independently selected from the group consisting of hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl, wherein R 1b and R 2b may be joined to form a 6-membered saturated or unsaturated ring, which may be substituted by one or more substituents selected from the group consisting of hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl, and wherein R 3b and R 4b may be joined to form a 6-membered ring, which may be substituted by one or more substituents selected from the group consisting of hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl; and wherein A represents a linking group represented by any of the following formulas (V) to (IX): wherein each * represents a bonding position of A in each formula
  8. The photoinitiator package according to claim 7, wherein at least one of the one or more optical brightener sensitizers has a structure according to formula (X): wherein each of R 1c to R 8c is independently selected from the group consisting of hydrogen, C 1 -C 10 alkyl and C 6 -C 14 aryl.
  9. The photoinitiator package according to any one of the preceding claims, wherein the one or more one or more further acylphosphine oxide photoinitiators having a structure not according to formula (I) comprises one or more monoacylphosphine photoinitiators and one or more bisacylphosphine oxide photoinitiators having a structure not according to formula (I).
  10. The photoinitiator package according to any one of the preceding claims, wherein the photoinitiator package comprises, more preferably consists of: a) an amount in the range from 15 to 40 wt.-%, more preferably in the range from 18 to 35 wt.-%, most preferably in the range from 19 to 30 wt.-%, relative to the total weight of the photoinitiator package, of the one or more bisacylphosphine oxide photoinitiators having a structure according to formula (I); b) an amount in the range from 30 to 75 wt.-%, more preferably in the range from 40 to 70 wt.-%, most preferably in the range from 50 to 60 wt.-%, relative to the total weight of the photoinitiator package, of the one or more further acylphosphine oxide photoinitiators having a structure not according to formula (I); c) an amount in the range from 5 to 30 wt.-%, more preferably in the range from 10 to 25 wt.-%, most preferably in the range from 15 to 22 wt.-%, relative to the total weight of the photoinitiator package, of the one or more optical brightener sensitizers; and d) optionally, an amount in the range from 1 to 30 wt.-%, more preferably in the range from 3 to 25 wt.-%, most preferably in the range from 5 to 20 wt.-%, relative to the total weight of the photoinitiator package, of one or more amines.
  11. A photopolymerizable composition, comprising: a) one or more ethylenically unsaturated, free-radical polymerizable compounds; b) the photoinitiator package according to any one of claims 1 to 10.
  12. The photopolymerizable composition according to claim 11, wherein the photopolymerizable composition comprises: a) an amount in the range from 30 to 99.0 wt.-%, more preferably in the range from 50 to 95.0 wt.-%, most preferably in the range from 70 to 90 wt.-%, relative to the total weight of the photopolymerizable composition, of the one or more ethylenically unsaturated, free-radical polymerizable compounds; b) an amount in the range from 0.5 to 50 wt.-%, more preferably in the range from 0.8 to 40 wt.-%, most preferably in the range from 1.0 to 30 wt.-%, relative to the total weight of the photopolymerizable composition, of the photoinitiator package according to any one of claims 1 to 10.
  13. The photopolymerizable composition according to claim 11 or claim 12, wherein the photopolymerizable composition further comprises one or more, of the following components: c) an amount in the range from 0.5 to 30 wt.-%, more preferably in the range from 0.8 to 20 wt.-%, most preferably in the range from 1.0 to 15 wt.-% of one or more further photoinitiators, one or more photosensitizers and/or one or more co-initiators; d) an amount in the range from 0.1 to 30 wt.-%, more preferably in the range from 1.0 to 25 wt.-%, most preferably in the range from 10 to 20 wt.-%, relative to the total weight of the photopolymerizable composition, of one or more pigments; e) an amount in the range from 5.0 to 60 wt.-%, more preferably in the range from 8.0 to 50 wt.-%, most preferably in the range from 10 to 40 wt.-%, relative to the total weight of the photopolymerizable composition, of one or more binders; and f) an amount in the range from 0.01 to 10 wt.-%, more preferably in the range from 0.01 to 8.0 wt.-%, most preferably in the range from 0.01 to 5.0 wt.-%, relative to the total weight of the photopolymerizable composition, of one or more additives.
  14. A method for photocuring photopolymerizable compositions, coatings, adhesives and inks, said method comprising the following steps in the given order: a) coating or printing the photopolymerizable composition according to any one of claims 11 to 13 onto a substrate, and b) photopolymerizing said coated or printed composition with a light source on said substrate.
  15. A use of the photoinitiator package according to any one of claims 1 to 10 in the production of printing inks, screen-printing inks, gravure printing inks, solder masks, etch offset-printing inks, flexographic- printing inks, gravure printing inks, ink jet inks, resist material, insulators, encapsulants, image-recording material, solder mask, passivation layer, protective coating, 3D-printing objects and molds, holographic applications, optical fiber coating, waveguide and lens, overprint varnish, wood, vinyl, metal and plastic coatings.

Description

Field of the Invention The present invention relates to a photoinitiator package comprising one or more bisacylphosphine oxide photoinitiators, one or more further acylphosphine oxide photoinitiators, one or more optical brightener sensitizers, and optionally one or more amines, wherein the photoinitiator package is a blend that is liquid at 25 °C and standard pressure, a photopolymerizable composition comprising the photoinitiator package and suitable polymerizable compounds, a method for polymerizing the photopolymerizable composition and a use of the photoinitiator package in photopolymerization applications. Background to the Invention Photoinitiators for promoting the radical polymerisation of ethylenically unsaturated compounds may be classed as either Norrish Type-I, wherein an electronically excited photoinitiator fractures to form a free radical that acts to initiate the radical polymerisation, or Norrish Type-II, wherein an electronically excited photoinitiator abstracts a hydrogen radical from a further molecule to form a free radical from said further molecule, said free radical acting to initiate the radical polymerisation. Whilst Type-II photoinitiators require the presence of certain additives/co-initiators, these additives/co-initiators are not generally required for Type-I photoinitiators. The development of new Type-I photoinitiators is a key area of research in the field of resin curing. In addition to the provision of novel Type-I photoinitiators, the provision of Type-I photoinitiator packages, wherein the activity of the Type-I photoinitiator is enhanced by the presence of other compounds, such as photosensitizers. These compounds absorb light at a different wavelength to that of the photoinitiator itself and transfer energy to the photoinitiator, improving the energy absorption by the photoinitiator. Phosphine oxides are a well-known family of Type-I photoinitiators that provide excellent activity due to the highly reactive phosphinoyl radical formed upon fragmentation. Whist excellent photoinitiators in deep-cure systems, they are notoriously much less effective at achieving surface curing. As such, blends of phosphine oxide photoinitiators with other photoinitiators known to be more effective at surface curing are often used to ensure a thorough cure. Relevant prior art represents US 2015/353751 A1, which discloses a curable coating composition comprising a mixture of ITX (isopropylthioxanthone), TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) and IRGACURE 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide). How well different Type-I photoinitiators interact with sensitizers is difficult to predict and often depends on the structure and energy levels of the photoinitiator. The provision of highly active photoinitiator packages is desirous as improved photopolymerization may be achieved without the need to develop new photoinitiators. In particular, an improvement of the surface curing abilities of phosphine oxide photoinitiators would allow these powerful photoinitiators to be more broadly applied. Summary of the Invention The present observation is based on the observation that combinations of sensitizers and photoinitiator blends that comprise certain bisacylphosphine oxide photoinitiators have unexpectedly excellent photoinitiator properties, including surface curing ability. The present invention, in a first aspect, is thus directed to a photoinitiator package comprising, more preferably consisting of: a) one or more bisacylphosphine oxide photoinitiators, each having a structure according to formula (I): wherein each instance of R is independently selected from the group consisting of C1-C4 alkyl;wherein X is selected from the group consisting of direct single bond, O, S, NR3, -CH2CO2-, and -CH2CH2CO2-;wherein R1 is selected from the group consisting of C1-C40 alkyl and interrupted C2-C40 alkyl being interrupted by one or more O or C3-C8 cycloalkylene, wherein said C1-C40 alkyl or interrupted C2-C40 alkyl may be unsubstituted or substituted by one or more groups selected from OH and R2;wherein R2 is wherein R3 is selected from the group consisting of hydrogen, (CO)R4, phenyl, C1-C12 alkyl, C2-C12 alkyl being interrupted by one or more O, wherein said C1-C12 alkyl or interrupted C2-C12 alkyl is unsubstituted or substituted by one or more C3-C7 cycloalkyl, OH or by NCO, C3-C12 cycloalkyl which is unsubstituted or substituted by one or more C1-C4 alkyl, C1-C4 alkoxy, OH or by NCO;wherein R4 is selected from the group consisting of C1-C12 alkyl or C2-C12 alkyl which is interrupted by one or more O, wherein said C1-C12 alkyl or interrupted C2-C12 alkyl is unsubstituted or substituted by one or more C3-C7-cycloalkyl, OH, NCO or by phenyl which is substituted by NCO; C3-C12 cycloalkyl; C2-C10 alkenyl which is unsubstituted or substituted by one or more C1-C4 alkyl, OH or C1-C4 alkoxy; C6-C14 aryl which is unsubstituted or substituted by C1-C12 alkyl, C1-C12 alkoxy, NCO or by N