NEW TRIAZINE AS PHOTO INITIATORS AND THEIR PREPARATION

Abstract

The present invention relates to new triazine photoinitiators, a new process for their preparation, and a photopolymer composition comprising a photopolymerizable component and the new triazine photoinitiators. Further aspects of the present invention are a photopolymer comprising said photopolymer composition, a holographic medium which comprises such a photopolymer, a hologram comprising the holographic medium, and a device such a display, chip card, security document, bank note and/or holographic optical element comprising said hologram.

Claims

1.-14. (canceled)

15. A triazine photoinitiator of the formula (I) ##STR00006## in which A represents chlorine, B represents fluorine, R.sup.1-R.sup.5 independently represent hydrogen, halogen alkyl, alkoxy, alkenyl, alkynyl, alkylthio, alkylseleno, nitro group with R.sup.1 and R.sup.2 and/or R.sup.2 and R.sup.3 and/or R.sup.3 and R.sup.4 and/or R.sup.4 and R.sup.5 optionally form a 3 to 5 membered saturated or unsaturated ring which is optionally substituted with up to 2 hetero atoms and/or COOR.sup.6, COR.sup.7, CONHR.sup.8 radicals, whereby R.sup.6, R.sup.7, R.sup.8 all independently from one another represent hydrogen, halogen and/or C1-C10-alkyl and/or C.sub.1-C.sub.10-alkoxy-substituted linear C.sub.5-C.sub.20-alkyl, in which up to 6 carbon atoms may be substituted with oxygen with the prerequisite that each two oxygen atoms are entangled by at least 2 carbon atoms and R.sup.6, R.sup.7, R.sup.8 start with at least 2 carbon atoms and the terminal group of the C.sub.5-C.sub.20-alkyl group is a methyl group.

16. Triazine photoinitiator according to claim 15, wherein R.sup.3 represents a hydrogen, methyl, halogene, methoxy, cyano, carboxylate, nitro or a methyl trihalogeno radical, while R.sup.1, R.sup.2, R.sup.4 and R.sup.5 independently represent hydrogen, halogen, alkyl, alkoxy, alkenyl, alkynyl, alkylthio, alkylseleno, nitro group with R.sup.1 and R.sup.2 and/or R.sup.2 and R.sup.3 and/or R.sup.3 and R.sup.4 and/or R.sup.4 and R.sup.5 optionally form a 3 to 5 membered saturated or unsaturated ring which is optionally substituted with up to 2 hetero atoms and/or COOR.sup.6, COR.sup.7, CONHR.sup.8 radicals while R.sup.6, R.sup.7, R.sup.8 represent all independently from one another hydrogen, halogen and/or C.sub.1-C.sub.10-alkyl and/or C.sub.1-C.sub.10-alkoxy-substituted linear C.sub.5-C.sub.20-alkyl, in which up to 6 carbon atoms may be substituted with oxygen with the prerequisite that each two oxygen atoms are entangled by at least 2 carbon atoms and R.sup.6, R.sup.7, R.sup.8 start with at least 2 carbon atoms and the terminal group of the C.sub.5-C.sub.20-alkyl group is a methyl group.

17. Triazine photoinitiator according to claim 15, wherein R.sup.1, R.sup.2, R.sup.4 and R.sup.5 represent a hydrogen atom.

18. Triazine photoinitiator according to claim 15, wherein R.sup.1, R.sup.2, R.sup.4 and R.sup.5 represent a hydrogen atom and R.sup.3 represents a hydrogen atom, a methyl, fluorine or methoxy radical.

19. Process for the preparation of a triazine according to claim 15 comprising the steps of a) Reacting the respective benzamidine hydrochloride of formula (II) with trihalogenoacetonitrile in the presence of a catalyst and ##STR00007## b) Reacting the resulting N-(benzamidyl) trihalogenoacetamidine with trihalogenoacetic anhydride, wherein the radicals of R.sup.1 to R.sup.5 are those as defined for formula (I) in claim 15, whereby the trihalogenoacetonitrile of a) carries three halogen atom different from the three halogen atoms of the trihalogenoacetic anhydride of b); wherein the benzamidine hydrochloride is reacted with trichloroacetonitrile and the resulting N-(benzamidyl) trichloroacetamidine is reacted with trifluoroacetic anhydride.

20. (canceled)

21. Photopolymer composition comprising a photopolymerizable component and a photo initiator system, wherein the photo initiator system comprises a triazine according to claim 15.

22. Photopolymer composition according to claim 21, wherein it comprises 0.01 to 20 weight of the triazine.

23. Photopolymer composition according to claim 21, wherein the photo initiator system further comprises at least one co-initiator, selected from borate initiators, trichloromethyl initiators, aryloxide initiators, bisimidazole initiators, ferrocene initiators, aminoalkyl initiators, oxime initiator, thiol initiators, peroxide intiators.

24. Photopolymer composition according to claim 21, wherein it further comprises matrix polymers.

25. Photopolymer composition according to claim 24, wherein the matrix polymers are three dimensional cross-linked.

26. Holographic media wherein it comprises a photopolymer composition according to claim 21.

27. Hologram comprising a holographic medium according to claim 26.

28. (canceled)

Description

EXAMPLES

[0128] The invention will be described in more detail by the following examples without restricting it thereto.

[0129] FIG. 1 shows the geometry of a holographic media tester (HMT) at =532 nm (DPSS laser).

[0130] FIG. 2 shows the measured transmitted power P.sub.T (right-hand y-axis) plotted as a solid line against the angle detuning and the measured diffraction efficiency (left-hand y-axis) is plotted as filled circles against the angle detuning .

[0131] FIG. 3 shows the photopolymerization conversion in % of photopolymer formulations comprising Triazine 1 and Triazine TA against the irradiation exposure time t in sec.

STARTING MATERIALS

[0132] Starting materials to synthesize compounds of formula (II) were prepared according to procedures reported in the literature or purchased.

[0133] The reagents and solvents used were acquired commercially.

TABLE-US-00001 Trichloroacetonitrile purchased from ABCR GmbH & CO. KG, Karlsruhe, Germany. Trifluoroacetic purchased from Sigma-Aldrich, Taufkirchen, Anhydride Germany. Benzamidine*HCl purchased from ABCR GmbH & CO. KG, Karlsruhe, Germany. CGI-909 Tetrabutylammonium tris(3-chloro-4-methylphenyl) (hexyl)borate, [1147315-11-4] is a product produced by BASF SE, Basle, Switzerland. SR 349 Ethoxylated (3) Bisphenol A Diacrylate, a product produced by Sartomer Americas, 502 Thomas Jones Way, Exton, PA 19341, USA. Safranine O purchased from Sigma-Aldrich, Taufkirchen, Germany. Triazine-A [3584-23-4] purchased from Midori Kagaku Co. Ltd, Tokyo Japan. Product no. TAZ-104. Dye 1 Preparation of Dye 1, 3H-Indolium, 2- [2-[4-[(2-chloroethyl)ethyl-amino]phenyl]ethenyl]- 1,3,3-trimethyl-, salt with 1-(2-ethylhexyl) 4- (1-ethylpentyl) 2-sulfobutanedioate (1:1) [1374689-58-3] is described in EP 2450893 A1. Desmorapid Z Dibutyltin dilaurate [77-58-7], product from Bayer MaterialScience AG, Leverkusen, Germany. Desmodur Product from Bayer MaterialScience AG, N 3900 Leverkusen, Germany, hexane diisocyanate-based polyisocyanate, iminooxadiazinedione content at least 30%, NCO content: 23.5%. Fomrez UL 28 Urethanization catalyst, commercial product of Momentive Performance Chemicals, Wilton, CT, USA.

[0134] Test Methods:

[0135] Isocyanate Content (NCO Value)

[0136] The isocyanate contents reported were determined according to DIN EN ISO 11909.

[0137] Determination of Photo Sensitivity

[0138] The photosensitivity of the compounds was measured by preparing a photosensitive formulation as described below and measuring photopolymerization using FTIR. Thus, the photosensitive formulation was coated with a thickness of 25 m onto a polyethylene film and covered with a further polyethylene film to prevent oxidation by oxygen from the air. The respective samples were measured by Real-Time FTIR (Vertex 70 FTIR spectrometer, Bruker Optik) using a 532 nm laser diode as an irradiation source with the irradiance intensity at the surface of the sample adjusted to 10 mW/cm.sup.2. The kinetics of the polymerization was measured by following the decay of the acrylic double bond at 1635 cm.sup.1. The degree of acrylate double bond conversion C(%) was calculated from the decrease of the area of the IR absorption peak at 1635 cm.sup.1 of the sample after exposure using the following equation:

C(%)=(A.sub.0A.sub.t)/A.sub.0100

[0139] A.sub.0 represent the initial peak area before irradiation and A.sub.t represent the peak area of the acrylic double bond at t time.

[0140] Holographic Testing:

[0141] Measurement of the Holographic Properties of Diffraction Efficiency DE and Refractive Index Contrast n of the Holographic Media by Means of Twin-Beam Interference in a Reflection Arrangement.

[0142] A holographic test setup as shown in FIG. 1 was used to measure the diffraction efficiency (DE) of the media. The beam of a DPSS laser (emission wavelength 532 nm) was converted to a parallel homogeneous beam with the aid of the spatial filter (SF) and together with the collimation lens (CL). The final cross sections of the signal and reference beam are fixed by the iris diaphragms (I). The diameter of the iris diaphragm opening is 0.4 cm. The polarization-dependent beam splitters (PBS) split the laser beam into two coherent beams of identical polarization. By means of the /2 plates, the power of the reference beam was set to 0.87 mW and the power of the signal beam to 1.13 mW. The powers were determined using the semiconductor detectors (D) with the sample removed. The angle of incidence (.sub.0) of the reference beam is 21.8; the angle of incidence (.sub.0) of the signal beam is 41.8. The angles are measured proceeding from the sample normal to the beam direction. According to FIG. 2, therefore, .sub.0 has a negative sign and .sub.0 a positive sign. At the location of the sample (medium), the interference field of the two overlapping beams produced a pattern of light and dark strips parallel to the angle bisectors of the two beams incident on the sample (reflection hologram). The strip spacing , also called grating period, in the medium is 188 nm (the refractive index of the medium assumed to be 1.504).

[0143] FIG. 1 shows the geometry of a holographic media tester (HMT) at =532 nm (DPSS laser): M=mirror, S=shutter, SF=spatial filter, CL=collimator lens, /2=/2 plate, PBS=polarization-sensitive beam splitter, D=detector, I=iris diaphragm, .sub.0=21.8, .sub.0=41.8 are the angles of incidence of the coherent beams measured outside the sample (outside the medium). RD=reference direction of the turntable.

[0144] Holograms were recorded in the medium in the following manner: [0145] Both shutters (S) are opened for the exposure time t. [0146] Thereafter, with the shutters (S) closed, the medium is allowed 5 minutes for the diffusion of the as yet unpolymerized writing monomers.

[0147] The holograms recorded were then reconstructed in the following manner. The shutter of the signal beam remained closed. The shutter of the reference beam was opened. The iris diaphragm of the reference beam was closed to a diameter of <1 mm. This ensured that the beam was always completely within the previously recorded hologram for all angles of rotation () of the medium. The turntable, under computer control, swept over the angle range from .sub.min to .sub.max with an angle step width of 0.05. is measured from the sample normal to the reference direction of the turntable. The reference direction of the turntable is obtained when the angles of incidence of the reference beam and of the signal beam have the same absolute value on recording of the hologram, i.e. .sub.0=31.8 and .sub.0=31.8. In that case, .sub.recording=0. When .sub.0=21.8 and .sub.0=41.8, .sub.recording is therefore 10. In general, for the interference field in the course of recording of the hologram:

.sub.0=.sub.0+.sub.recording.

[0148] .sub.0 is the semiangle in the laboratory system outside the medium and, in the course of recording of the hologram:

[00001]${}_0=\frac{{}_0-{}_0}{2}.$

[0149] Thus, in this case, .sub.0=31.8. At each setting for the angle of rotation , the powers of the beam transmitted in the zeroth order were measured by means of the corresponding detector D, and the powers of the beam diffracted in the first order by means of the detector D. The diffraction efficiency was calculated at each setting of angle as the quotient of:

[00002]$=\frac{P_D}{P_D+P_T}$

[0150] P.sub.D is the power in the detector for the diffracted beam and P.sub.T is the power in the detector for the transmitted beam.

[0151] By means of the process described above, the Bragg curve, which describes the diffraction efficiency as a function of the angle of rotation for the recorded hologram, was measured and saved on a computer. In addition, the intensity transmitted into the zeroth order was also recorded against the angle of rotation and saved on a computer.

[0152] The maximum diffraction efficiency (DE=.sub.max) of the hologram, i.e. the peak value thereof, was determined at .sub.reconstruction. In some cases, it was necessary for this purpose to change the position of the detector for the diffracted beam in order to determine this maximum value.

[0153] The refractive index contrast n and the thickness d of the photopolymer layer were now determined by means of coupled wave theory (see: H. Kogelnik, The Bell System Technical Journal, Volume 48, November 1969, Number 9 page 2909-page 2947) from the measured Bragg curve and the variation of the transmitted intensity with angle. In this context, it should be noted that, because of the shrinkage in thickness which occurs as a result of the photopolymerization, the strip spacing of the hologram and the orientation of the strips (slant) can differ from the strip spacing of the interference pattern and the orientation thereof. Accordingly, the angle .sub.0 and the corresponding angle of the turntable .sub.reconstruction at which maximum diffraction efficiency is achieved will also differ from .sub.0 and from the corresponding .sub.recording. This alters the Bragg condition. This alteration is taken into account in the evaluation process. The evaluation process is described hereinafter:

[0154] All geometric parameters which relate to the recorded hologram and not to the interference pattern are shown as parameters with primes.

[0155] For the Bragg curve () of a reflection hologram, according to Kogelnik:

[00003]$=\{\begin{array}{cc}\frac{1}{1-\frac{1-{\left(/\right)}^2}{{\sin }^2\left(\sqrt{{}^2-{}^2}\right)}},& \mathrm{for}.Math..Math.{}^2-{}^2<0\\ \frac{1}{1+\frac{1-{\left(/\right)}^2}{{\sin }^2\left(\sqrt{{}^2-{}^2}\right)}},& \mathrm{for}.Math..Math.{}^2-{}^{2}0\end{array}.Math..Math.\mathrm{with}.Math.\text{:}.Math..Math..Math.+\frac{.Math..Math..Math.n.Math.d^{}}{.Math.\sqrt{l.Math..Math.c_s.Math.c_r.Math.}}.Math..Math.=-\frac{d^{}}{2.Math.c_s}.Math.\mathrm{DP}.Math..Math.c_s=\cos \left({}^{}\right)-\cos \left({}^{}\right).Math.\frac{}{n.Math.{}^{}}.Math..Math.c_r=\cos \left({}^{}\right).Math..Math.\mathrm{DP}=\frac{}{{}^{}}.Math.\left(2.Math.\cos \left({}^{}-{}^{}\right)-\frac{}{n.Math.{}^{}}\right).Math..Math.{}^{}=\frac{{}^{}+{}^{}}{2}.Math..Math.{}^{}=\frac{}{2.Math.n.Math.\cos \left({}^{}-{}^{}\right)}$

[0156] In the reconstruction of the hologram, as explained analogously above:

.sub.0=.sub.0+

sin(.sub.0)=n.Math.sin()

[0157] Under the Bragg condition, the dephasing DP=0. And it follows correspondingly that:

.sub.0=.sub.0+.sub.reconstruction

sin(.sub.0)=n.Math.sin()

[0158] The as yet unknown angle can be determined from the comparison of the Bragg condition of the interference field in the course of recording of the hologram and the Bragg condition in the course of reconstruction of the hologram, assuming that only shrinkage in thickness takes place. It then follows that:

[00004]$\sin \left({}^{}\right)=\frac{1}{n}.Math.\left[\sin \left({}_0\right)+\sin \left({}_0\right)-\sin .Math..Math.\left({}_0+{}_{\mathrm{reconstruction}}\right)\right]$

[0159] v is the grating thickness, is the detuning parameter and is the orientation (slant) of the refractive index grating which has been recorded. and correspond to the angles .sub.0 and .sub.0 of the interference field in the course of recording of the hologram, except measured in the medium and applying to the grating of the hologram (after shrinkage in thickness). n is the mean refractive index of the photopolymer and was set to 1.504. is the wavelength of the laser light in the vacuum.

[0160] The maximum diffraction efficiency (DE=.sub.max), when =0, is then calculated to be:

[00005]$\mathrm{DE}={\tanh }^2\left(v\right)={\tanh }^2\left(\frac{.Math..Math..Math.n.Math.d^{}}{.Math.\sqrt{\cos \left({}^{}\right).Math.\cos \left({}^{}-2.Math.\right)}}\right)$

[0161] FIG. 2 shows the measured transmitted power P.sub.T (right-hand y-axis) plotted as a solid line against the angle detuning ; the measured diffraction efficiency (left-hand y-axis) is plotted as filled circles against the angle detuning (to the extent allowed by the finite size of the detector), and the fitting to the Kogelnik theory as a broken line (left-hand y-axis).

[0162] The measured data for the diffraction efficiency, the theoretical Bragg curve and the transmitted intensity are, as shown in FIG. 2, plotted against the centered angle of rotation .sub.reconstruction=.sub.0.sub.0, also called angle detuning.

[0163] Since DE is known, the shape of the theoretical Bragg curve, according to Kogelnik, is determined only by the thickness d of the photopolymer layer. n is corrected via DE for a given thickness d such that measurement and theory for DE are always in agreement. d is adjusted until the angle positions of the first secondary minima of the theoretical Bragg curve correspond to the angle positions of the first secondary maxima of the transmitted intensity, and there is additionally agreement in the full width at half maximum (FWHM) for the theoretical Bragg curve and for the transmitted intensity.

[0164] Since the direction in which a reflection hologram also rotates when reconstructed by means of an scan, but the detector for the diffracted light can cover only a finite angle range, the Bragg curve of broad holograms (small d) is not fully covered in an scan, but rather only the central region, given suitable detector positioning. Therefore, the shape of the transmitted intensity, which is complementary to the Bragg curve, is additionally employed for adjustment of the layer thickness d.

[0165] FIG. 2 shows the plot of the Bragg curve according to the coupled wave theory (broken line), the measured diffraction efficiency (filled circles) and the transmitted power (black solid line) against the angle detuning .

[0166] For a formulation, this procedure was repeated, possibly several times, for different exposure times t on different media, in order to find the mean energy dose of the incident laser beam in the course of recording of the hologram at which DE reaches the saturation value. The mean energy dose E is calculated as follows from the powers of the two component beams assigned to the angles .sub.0 and .sub.0 (reference beam where P.sub.r=0.87 mW and signal beam where P.sub.s=1.13 mW), the exposure time t and the diameter of the iris diaphragm (0.4 cm):

[00006]$E.Math..Math.\left(\mathrm{mJ}/{\mathrm{cm}}^2\right)=\frac{2.Math.\left[P_r+P_s\right].Math.t\left(s\right)}{.Math.{0.4}^2.Math..Math.{\mathrm{cm}}^2}$

[0167] The powers of the component beams were adjusted such that the same power density is attained in the medium at the angles .sub.0 and .sub.0 used.

[0168] In an alternative setup according to FIG. 1 a DPSS laser with an emission wavelength of 473 nm could be used. In this case .sub.0=21.8 and .sub.0=41.8 are same as if using the emission wavelength =532 nm but the reference beam power was set to P.sub.r=1.31 mW and signal beam power was set to P.sub.s=1.69 mW.

[0169] Preparation of Triazines:

Synthesis of Triazine 1: 2-Phenyl-4-trichloromethyl-6-trifluoromethy-s-triazine

[0170] Step a

[0171] To a solution of 25.0 g of benzamidine hydrochloride and 100 mL of Methanol, 33.2 g of 25% solution of NaOMe were added drop wise with stirring at zero degree. After addition, the mixture was stirred for 30 min, then 22.2 g of trichloroacetonitrile were added at zero degree during 30 min. After the addition, the cooling bath was removed and the reaction mixture was continued to stir overnight. 100 mL of ethyl acetate was added to the reaction mixture and the solid that precipitates in the flask was removed by filtration. The filtered solution was evaporated and 300 mL of cyclohexane was added. After heating the mixture to reflux for 30 min, upper part of solution was removed by decantation and lower part was evaporated to yields N-(benzamidyl) trichloroacetamidine as oil. Yields 29.2 g.

[0172] Step b

[0173] 10.0 g of N-(benzamidyl) trichloroacetamidine in 10 mL of tetrahydrofuran were added drop wise carefully to a cooed solution of 17.5 g of trifluoroacetic anhydride in 50 mL of tetrahydrofuran during 60 min and the mixture was continued to stirring overnight. After the reaction mixture was heated to reflux for 15 min, it was poured carefully into 500 mL of water. After stirring for 30 min, crystals were precipitated and collected by filtration and dried in air to obtain 5.7 g of 2-phenyl-4-trichloromethyl-6-trifluoromethy-s-triazine as white crystals. Recrystallization from acetonitrile yields 4.8 g of pure crystals.

[0174] .sup.13C NMR (176 MHz, CDCl.sub.3) 94.66 (CCl.sub.3), 118.52 (CF.sub.3, q, 277.2 Hz), 129.28 (Ar), 130.15 (Ar), 132.97 (Ar), 135.17 (Ar), 166.30 (q, 39.0 Hz, CCF.sub.3), 174.99, 175.18 (CAr, CCCl.sub.3).

Synthesis of Triazine 2: 2-(p-Fluorophenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine

[0175] Step a

[0176] To a solution of 10 g of p-fluorobenzamidine hydrochloride and 100 mL of Methanol, 10.3 g of 30% solution of NaOMe were added drop wise with stirring at zero degree. After addition, the mixture was stirred for 30 min, then 8.23 g of trichloroacetonitrile were added at zero degree during 30 min. After the addition, the cooling bath was removed and the reaction mixture was continued to stir overnight. 100 mL of ethyl acetate was added to the reaction mixture and the solid that precipitated in the flask was removed by filtration. The filtered solution was evaporated to yield N-(p-fluorobenzamidyl) trichloroacetamidine as oil. Yields 11.2 g.

[0177] Step b

[0178] 10.0 g of N-(p-fluorobenzamidyl) trichloroacetamidine in 50 mL of tetrahydrofuran were added drop wise carefully to a cooled solution of 16.35 g of trifluoroacetic anhydride in 50 mL of tetrahydrofuran during 60 min and the mixture was continued to stirring overnight. After the reaction mixture was heated to reflux for 15 min, it was poured carefully into 500 mL of water. After stirring for 30 min, crystals were precipitated and collected by filtration. Recrystallization from methanol yielded 7.9 g of pure crystals of 2-(p-fluorophenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine.

[0179] .sup.13C NMR (176 MHz, CDCl.sub.3) 94.56 (CCl.sub.3), 116.61 (Ar), 116.74 (Ar), 118.46 (CF.sub.3, q, 277 Hz), 129.26 (Ar), 132.84 (Ar), 166.33 (q, 39.2 Hz, CCF.sub.3), 167.33 (d, 257.8 Hz, ArF), 173.88, 175.22 (CAr, CCCl.sub.3).

Synthesis of Triazine 3: 2-(p-Methylphenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine

[0180] Step a

[0181] To a solution of 10.0 g of p-methylbenzamidine hydrochloride and 100 mL of Methanol, 10.3 g of 30% solution of NaOMe were added drop wise with stirring at zero degree. After addition, the mixture was stirred for 30 min, then 8.46 g of trichloroacetonitrile were added at zero degree during 30 min. After the addition, the cooling bath was removed and the reaction mixture was continued to stir overnight. 100 mL of ethyl acetate was added to the reaction mixture and the solid that precipitates in the flask was removed by filtration. The filtered solution was evaporated to yield N-(p-methylbenzamidyl) trichloroacetamidine as oil. Yields 18.8 g.

[0182] Step b

[0183] 10.0 g of N-(p-methylbenzamidyl) trichloroacetamidine in 50 mL of tetrahydrofuran were added drop wise carefully to a cooled solution of 16.59 g of trifluoroacetic anhydride in 50 mL of tetrahydrofuran during 60 min and the mixture was continued to stirring overnight. After the reaction mixture was heated to reflux for 15 min, it was poured carefully into 500 mL of water. After stirring for 30 min, the water solution was extracted with 300 mL of ethyl acetate. The organic layer was separated and evaporated to give oil. After column chromatography with silica gel (cyclohexane/ethyl acetate=16/5), 2-(p-methylphenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine as pure solid. Yields 1.4 g.

[0184] .sup.13C NMR (176 MHz, CDCl.sub.3) 22.00 (CH.sub.3), 94.74 (CCl.sub.3), 118.54 (CF.sub.3, q, 278 Hz), 130.06 (Ar), 130.20 (Ar), 130.35 (Ar), 146.55 (CH.sub.3Ar), 166.15 (q, 38.7 Hz, CCF.sub.3), 174.87, 174.98 (CAr, CCCl.sub.3).

Synthesis of Triazine 4: 2-(p-methoxylphenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine

[0185] Step a

[0186] To a solution of 10.0 g of p-methoxybenzamidine hydrochloride and 100 mL of Methanol, 10.3 g of 30% solution of NaOMe were added dropwise with stirring at zero degree. After addition, the mixture was stirred for 30 min, then 7.73 g of trichloroacetonitrile were added at zero degree during 30 min. After the addition, the cooling bath was removed and the reaction mixture was continued to stir overnight. 100 mL of ethyl acetate was added to the reaction mixture and the solid that precipitates in the flask was removed by filtration. The filtered solution was evaporated to yield N-(p-methoxylbenzamidyl) trichloroacetamidine as oil. Yields 15.9 g.

[0187] Step b

[0188] 10.0 g of N-(p-methoxylbenzamidyl) trichloroacetamidine in 50 mL, of tetrahydrofuran were added drop wise carefully to a cooled solution of 16.69 g of trifluoroacetic anhydride in 50 mL of tetrahydrofuran during 60 min and the mixture was continued to stirring overnight. After the reaction mixture was heated to reflux for 15 min, it was poured carefully into 500 mL of water. After stirring for 30 min, the water solution was extracted with 300 mL, of ethyl acetate. The organic layer was separated and evaporated to give oil. After column chromatography with silica gel (Cyclohexane/Ethyl acetate=16/5), 2-(p-methoxylphenyl)-4-trichloromethyl-6-trifluoromethy-s-triazine as pure solid. Yields 3.5 g.

[0189] .sup.13C NMR (176 MHz, CDCl.sub.3) 55.70 (OCH.sub.3), 114.70 (Ar), 118.58 (CF.sub.3, q, 277 Hz), 125.49 (Ar), 132.52 (Ar), 165.52 (CH.sub.3Ar), 166.00 (q, 38.7 Hz, CCF.sub.3), 174.20, 174.77 (CAr, CCCl.sub.3).

[0190] Measurement of Photosensitivity:

Example 1

[0191] Photosensitive formulation was prepared by mixing 2 mg of Safranine O, 20 mg of CGI909, 20 mg of triazine 1, 200 mg of DMSO, 2.0 g of SR 349 and stirring overnight to ensure complete mixing. The photosensitive formulation was coated with a thickness of 25 m onto a polyethylene film and covered with a further polyethylene film protect against oxygen from air. Then the sample was measured by Real-Time FTIR and the result is shown in FIG. 3. The polymerization conversion after 40 sec irradiation was 53.2%.

Example 2

[0192] Example 2 was performed using the same procedure as example 1 using triazine 2, instead of triazine 1. The polymerization conversion after 40 sec irradiation was 53.5%.

Example 3

[0193] Example 3 was performed using the same procedure as example 1 using triazine 3, instead of triazine 1. The polymerization conversion after 40 sec irradiation was 53.5%.

Comparative Example 1

[0194] Comparative example 1 was performed using the same procedure as example 1 using commercially available Triazine-A instead of Triazine 1. Conversion during irradiation was determined using Real-Time FTIR and results are shown in FIG. 3. The polymerization conversion after 40 sec irradiation was 49.8%.

TABLE-US-00002 TABLE 1 Result of conversion in photopolymerisation experiment Conversion after 40 s Example Triazine [%] 1 1 53.2 2 2 53.5 3 3 53.5 Comparative Example 1 Triazine-A 49.8

[0195] The examples 1-3 show a higher conversion rate after 40 s than the comparative example 1 thus demonstrating the higher efficiency of the triazines 1-3 compared to triazine A. In a direct comparison, example 1 shows a higher conversion rate than the comparative example 1 during the whole recordings period (FIG. 3).

[0196] Preparation of Photopolymer Compounds:

Preparation of Polyol 1

[0197] In a 1 L flask, 0.18 g of tin octoate, 374.8 g of -caprolactone and 374.8 g of a difunctional polytetrahydrofuran polyetherpolyol (equivalent weight 500 g/mol of OH) were initially charged and heated up to 120 C. and maintained at that temperature until the solids content (proportion of nonvolatile constituents) was 99.5% by weight or higher. This was followed by cooling to obtain the product as a waxy solid.

Preparation of Acrylate 1: (phosphorus thioyltris(oxy-4,1-phenyleneiminocarbonyloxy-ethane-2,1-diyl) triacrylate)

[0198] In a 500 mL round-bottom flask, 0.1 g of 2,6-di-tert-butyl-4-methylphenol, 0.05 g of dibutyltin dilaurate (Desmorapid Z, Bayer MaterialScience AG, Leverkusen, Germany) and also and 213.07 g of a 27% solution of tris(p-isocyanatophenyl) thiophosphate in ethyl acetate (Desmodur RFE, product from Bayer MaterialScience AG, Leverkusen, Germany) were initially charged and heated to 60 C. Thereafter, 42.37 g of 2-hydroxyethyl acrylate were added dropwise and the mixture was further maintained at 60 C. until the isocyanate content had dropped below 0.1%. This was followed by cooling and complete removal of the ethyl acetate under reduced pressure to obtain the product as a partly crystalline solid.

Preparation of Acrylate 2: 2-({[3-(methylsulphanyl)phenyl]carbamoyl}oxy)ethyl prop-2-enoate)

[0199] In a 100 mL round-bottom flask, 0.02 g of 2,6-di-tert-butyl-4-methylphenol, 0.01 g of Desmorapid Z, 11.7 g of 3-(methylthio)phenyl isocyanate were initially charged and heated to 60 C. Thereafter, 8.2 g of 2-hydroxyethyl acrylate were added dropwise and the mixture was further maintained at 60 C. until the isocyanate content had dropped below 0.1%. This was followed by cooling to obtain the product as a pale yellow liquid.

Preparation of Additive 1: (Bis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl) 2,2,4-trimethylhexane-1,6-diyl biscarbamate)

[0200] In a round-bottom flask, 0.02 g of Desmorapid Z and 3.6 g of 2,4,4-trimethylhexanes 1,6-diisocyanate were initially charged and heated to 70 C. This was followed by the dropwise addition of 11.39 g of 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptan-1-ol and the mixture was further maintained at 70 C. until the isocyanate content had dropped below 0.1%. This was followed by cooling to obtain the product as a colorless oil.

[0201] Preparation of Holographic Media:

[0202] Example Medium 1 (M1)

[0203] 3.38 g of polyol component 1 were mixed with 2.00 g of acrylate 1, 2.00 g of acrylate 2, 1.50 g of additive 1, 0.10 g of CGI 909 (product from BASF SE, Basle, Switzerland), 0.018 g of Dye 1, 0.09 g of example 1 and 0.35 g of ethyl acetate at 40 C. to obtain a clear solution. The solution was then cooled down to 30 C., 0.65 g of Desmodur N3900 (commercial product from Bayer MaterialScience AG, Leverkusen, Germany, hexane diisocyanate-based polyisocyanate, portion on iminooxadiazinedione at least 30%, NCO content: 23.5%) was added before renewed mixing. Finally, 0.01 g of Fomrez UL 28 (urethanization catalyst, commercial product of Momentive Performance Chemicals, Wilton, Conn., USA) was added and again briefly mixed in. The mixed photopolymer formulation was applied on 36 m thick polyethylene terephthalate film. The coated film was dried for 5.8 minutes at 80 C. and finally covered with a 40 m polyethylene film. The achieved photopolymer layer thickness was around 14 m.

[0204] Example medium 2 (M2) was prepared as described above but with 0.09 g of example 3 instead of example 1.

[0205] Reference medium (RM 1) was prepared as described above but with 0.09 g of triazine A instead of example 1. The media obtained as described were subsequently tested for their holographic properties in the manner described above using a measuring arrangement as FIG. 1. The following measurements were obtained for n at dose E [mJ/cm.sup.2]:

TABLE-US-00003 TABLE 2 Result of holographic experiment Laser used to record Hologram Dose Example Triazine (nm) DE n (mJ/cm.sup.2) M1 1 532 0.84 0.024 31.8 M2 3 532 0.85 0.023 31.8 RM 1 Triazine-A 532 0.84 0.022 31.8

[0206] The above experimental data shows that the inventive photopolymer is useful to write bright holograms.