DE1572136B1 - Photopolymerizable mixture - Google Patents

Description

The invention relates to a new photopolymerizable mixture with at least one non-gaseous, ethylenically unsaturated, free-radically polymerizable Compound, at least one amine, in particular a tertiary amine, an amine-substituted Leuco dye, in particular a dialkylamino-substituted leuco dye, one Mixture of a leuco dye and a photo-reducible dye, a mixture from a leuco dye and triethanolamine, a photolytic halogen compound, Ascorbic acid, 2-allylthiourea or thiourea as a free-radical electron donor, a photosensitive, radical-donating polymerization initiator, optionally a sensitizing dye and optionally an oxygen-eliminating dye Link.

It is known to use photopolymerizable mixtures as image-forming systems in photographic recording materials. These recording materials are suitable for the production of relief printing plates, as described in detail in U.S. Patents 2,760,863 and 2,791,504 , or for the production of image reproductions, as in U.S. Patents 3,060,023, 3,060,024, 3,060,025 and 3,060,026. In these processes, the photopolymerizable recording materials are generally exposed imagewise in contact with a master copy or a stencil to actinic radiation until the exposed parts of the image are essentially fully polymerized. In the process, an addition polymer is formed, while essentially no polymerization takes place in the unexposed adjacent complementary image parts. After exposure, the recording materials are z. B. developed by washing with a solvent, thermal transfer, transfer by pressure, dusting with pigments of different adhesion of the exposed to the unexposed areas, either an image on an image receiving material or a suitable for copying or printing relief is formed.

During the photopolymerization of ethylenically unsaturated compounds According to the patents mentioned, there are many initiators for increasing the Polymerization rate known. The use of these known initiators usually limited the application of the photopolymerizable layers to the Exposure through the shorter, higher energy wavelengths, d. H. Ultraviolet- and blue light with wavelengths below 450 nm.

With the advent of dye-sensitized photopolymerization visible light could be used to initiate the polymerization. the U.S. Patents 2,850,445, 2,875,047, and 3,097,096 describe the use various photo-reducible dyes in combination with mild reducing agents to initiate the polymerization of liquid, photopolymerizable or organic Vinyl monomers.

Disadvantages of the known photopolymerizable recording materials is their relatively low spectral sensitivity, and is also photographic Sensitivity generally low, so enlargement copies and recordings are hardly possible with the camera.

The object of the invention is to provide a photopolymerizable mixture of improved indicate spectral and photographic sensitivity. There is also a drying system instead of a liquid system, it is desirable for these recording materials.

The object of the invention is based on a photopolymerizable Mixture with a) at least one non-gaseous, ethylenically unsaturated, free radical polymerizable compound, b) at least one amine, in particular a tertiary one Amine, an amine-substituted leuco dye, especially a dialkylamino-substituted one Leuco dye, a mixture of a leuco dye and a photo reducible dye Dye, a mixture of a leuco dye and triethanolamine, a photolytic one Halogen compound, ascorbic acid, 2-allylthiourea or thiourea as a radical donor Electron donor, c) a light-sensitive, radical-providing polymerization initiator, d) optionally a sensitizing dye and e) optionally an oxygen switching off compound, and is characterized in that it is used as a polymerization initiator contains a photolytic 2,4,5-triphenylbis-imidazolyl derivative.

The bisimidazole derivatives consist of two imidazolyl rings linked by a covalent bond and have the formula wherein the imidazole rings each have two double bonds in conjugated position and are bound to one another via the free valence - which can be located on each of the 5 ring atoms. The phenyl groups can be substituted.

The structurally isomeric bisimidazolyl derivatives mentioned exist in Solution partly in an equilibrium side by side, so that an exact definition the structure of the isomeric 2,4,5-triphenyl-bisimidazolyl derivative contained in each case in the photosensitive mixture is not always possible (cf. White and Sonnenberg, "Oxydation of Triarylimidazols" in "Abstracts of Papers", 114, Meetin American Chemical Society, Los Angeles, p. 55 M / 56 M, 1963).

True, below is within the scope of the formulas and nomenclature listed of bis-imidazolyl derivatives with the covalent bond in the 1,1'-position, However, this should not be associated with a commitment to this particular constitution, since the position of the covalent bond plays no role in the context of the invention. To Irradiation of the bisimidazolyl derivatives with actinic light these dissociated into free radicals. This free door created by dissociation Iphenylimidazolyl radicals react with the radical donating electron donor with the formation of such radicals that trigger addition polymerization.

The 2,4,5-triphenyl-bis-imidazolyl derivatives, which contain an o-substituent on the 2-phenyl ring, have proven to be particularly valuable components of the initiator system because of their stability. Examples of such compounds are 2-o-chlorophenyl-4,5-diphenyl-1,1-bis-imidazole or 2- (o-fluorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl or 2- (o-methoxyphenyl) -4,5-diphenyl-1,1'-bis-imidazolyl Other unsubstituted or substituted bis-imidazolyl compounds also prove to be suitable. Under certain conditions, e.g. B. when using a salt form of leukotriphenylmethanfarbstofl's as a free-radical electron donor, these bis-compounds proved to be unstable, that is, they enter into a dark reaction with the free-radical electron donor, whereby part of the initiator system is consumed and thus the concentrations are reduced and in certain cases Cases polymerization is caused during aging in the dark. Examples of these other bis-imidazolyl compounds are 2- (p-methoxyphenyl) -4,5-diphenyl-1,1'-bis-imidazolyl 2,4- (p-Dimethoxyphenyl) -5-phenyl-1,1'-bis-imidazolyl 2- (2,4-Dimethoxyphenyl) -4,5-diphenyl-1,1'-bis-imidazolyl 2- (p-methylmercaptophenyl) -4,5-diphenyll, l'-bis-imidazolyl 2,4,5-triphenyl-1,2'-bis-imidazolyl = isomer A Maximum at 270 m; .. 2,4,5-triphenyl-4,4'-bis-imidazolyl = isomer B Maximum at 280 mu Compounds that generate a radical-donating electron donor must be used which form a stable system with the bisimidazolyl derivative in the dark. Amines are suitable for this, e.g. B. tertiary amines. The amine-substituted leuco dyes, in particular those with at least one dialkylamino group, are very useful. Any leukotriphenylamine dyes or various salts of the dye, e.g. B. the chloride of the blue leuco dye can also be used. Suitable leuco dyes are, for example, tris (4-N, N-diethylamino-o-tolyl) methane trihydrochloride Bis- (4-NN-diiitlivl; imino-o-tolyl) -thienyl-2-metal Bis (4-N, N-diethyliamino-o-tolyl) -dioxymethylene-3,4-phenyl) -methane Bis- (4-N, N-diethylamino-o-tolyi) -benzyl-thiophenylmethane as a leuco dye with a neutral shade Leucomalachite green (CI basic green 4), 4,4'-bis-dimethylainino-triphenyl-methane Leuco crystal violet (C.1: Basic violet 3), 4,4 ', 4 "-Tris-dimethylamino-triphenyl-methane and brilliant green (C. 1. basic green 1), Victoria green 3 B (CI basic green 4), acid green GG (C. 1. acid green 3. methyl violet (CI basic violet 1), rosaniline (CI basic violet 14) B. The chloride, salts with Lewis acids, sulfuric acid salts or p-toluenesulfonic acid salts of the leuco dye can be used better than the free base, since the quantum yield of color formation is highest in an acidic medium.

The following further compounds are, for example, suitable as radical-providing electron donors: carbon tetrabromo; Bromoform, triethanolamine, N-phenylglycine, 6-Br-piperonal / N, N-dimethylaniline, ascorbic acid, 2-allylthiourea, thiourea; Sarcosine, _KN - dimethylglycine, N, N-diethylglycine. Tri-N-hexylamine, tri-N-octylamine, diethylcyclohexylamine, N, N, N ', N' - tetramethylenediamine, tetramethylethylenediamine, 2-dimethylaminoethanol, 3-dimethylamino-1-propanol, 1 - dimethylamino - 2 - propanol, 2 - Diethylaminoethanol, N, N, N ', N'-tetramethyl-1,3-butanediamine. The tertiary amino compounds are preferred. The preparation of the substituted bis-imidazolyl connections is described in British patent specification 997 396 and Canadian patent specification 731663 . It is also stated here that triarylimidazolyls can be coupled to the bis-imidazolyl compounds (cf. also Z Immermann et al., "Angewandte Chemie", 73, p. 808 [1961]).

Suitable ethylenically unsaturated compounds that have a through Free radical initiated, chain-like propagating addition polymerization Ability to form polymers are in U.S. Patent 3,060,026, column 4, Line 56 through column 5, line 32. Other suitable compounds are in U.S. Patents 2,929,710 and 3,043,805, where the single compound can be present both as a monomer and as a polymer, since the ethylenic Double bond is present as an extralinear substituent attached to the thermoplastic linear polymers is bound. Polyoxyethylated trimethylolpropane triacrylate or Polytetramethylene glycol diacrylate are also suitable.

Examples of such monomers are pentaerythritol triacrylate, polyethylene glycol dimethacrylate. Crosslinkable polymers can also be used in place of the combination of monomers and Binders are used.

In the case of the three-component systems, it was found that the photographic Sensitivity or the rate of polymerization of the concentration of the Bis-imidazolyl compound and the free-radical electron donor depends. It was found that the sensitivity or the rate of polymerization up to a certain concentration of the bis-imidazolyl derivative and the radical donor Electron donor increases and the concentration increases beyond this amount no further increase in sensitivity or the rate of polymerization and in certain cases the sensitivity is even reduced. For example, if a leuco dye was used as a radical donating electron donor with a ratio of leuco dye to the bis-imidazolyl derivative of 1: 2 the best results in terms of photographic sensitivity and aging behavior obtain. For example, in a 5.0 g mixture of monomers and Binder in acetone has the maximum photographic sensitivity with a concentration achieved by 80 mg of leukotriphenylmethane dye and 160 mg of the dimer. At higher Concentrations, the sensitivity was lower.

According to one embodiment of the invention, the photopolymerizable Mixture of the bis-imidazolyl derivative, a leukotriphenylmethane dye that delivers free radicals Electron donor and a sensitizing dye (4-component system). the Adding the sensitizing dye extends the spectral sensitivity of the Three-component system in the visible spectral range and also increases the rate of polymerization. This four-component system can only polymerize by exposure to visible Trigger light and does not lose sensitivity with aging. In the four-component system energy absorption by the dye induces the same reaction with the bis-imidazolyl derivative like its direct exposure in the three-component system.

The dyes are suitable as energy-transferring sensitizer dyes of the xanthene class, e.g. B. Fluorescein (C.I. Acid Yellow 73), 4,5-dibromofluorescein, Eosin Y (C. I. Acid Red 87), Erythrosin B (C. I. Acid Red 51), Rose Bengal (C. I. Acid red 94), phloxin (Lauth-Violett, C. I. 5200) and dyes of the acridine class, like acriflavine. The spectral sensitivity can be increased by using a dye, like riboflavin, can be further expanded to longer wavelengths (450 nm). the An important requirement or function of the dye is that it has the energy of visible light to the ultraviolet light absorbing bis-imidazolyl derivative effectively transmits. It is particularly advantageous to use these dye mixtures in systems where panchromatic sensitivity is desired.

Photo reducible dyes which are described above Ability to transmit light energy are used as sensitizer dyes also suitable.

The photographic sensitivity of the four component system is largely on the concentration of the bis-imidazolyl derivative of the leuco dye and the energy transferring sensitizer dye. As with the Three-component system is achieved when maximum photographic sensitivity the weight ratio of leuco dye to bis-imidazolyl derivative is 1: 2. If this ratio is kept constant, the optimum concentration of the energy transfer sensitizing dye designed for maximum sensitivity will. If the concentration of the sensitizer dye is too high, it will to an inhibitor, possibly through strong attenuation of actinic light or by self-damping. For example, they were made in a coating solution Monomers, binders or solvents of 5.0 g the maximum sensitivity to visible light and the highest photographic sensitivity with a Concentration of 10 mg of the sensitizer dye (erythrosine), 80 mg of the leuco dye and 160 mg of the 2,4,5-triphenyl-bis-imidazolyl derivative.

A photopolymerizable recording material based on the four-component initiator system is suitable for taking pictures with the camera. For example, at an exposure 17 seconds at f / 3.5 in bright sunlight, a high-contrast image when developed obtained by thermal transfer. The system is also suitable for magnification copying, d. H. for enlarging microfilm originals with usual Tungsten filament lamps. One embodiment of this system was after exposure and thermal transfer development, an ASA sensitivity value of 0.004 established.

In a further embodiment of the invention, the photopolymerizable Mixture of the bisimidazolyl derivative, a leukotriphenylmethane dye as a radical donor Electron donor, a sensitizing dye and a fifth component, which serves as a compound that switches off or binds oxygen, e.g. B. 2-allylthiourea, Dimethyl sulfoxide or tin (II) chloride (five-component system). the The compound which switches off or binds the oxygen switches the in general any induction period present in a photopolymerization reaction is deactivated or shortened they, possibly due to the consumption of oxygen in the shift the exposure. It is believed that this reaction mechanism is the same is like the four-component system, with the fifth component doing its special job the partial or complete dark consumption of soluble oxygen is met. The use of this fifth component has a large increase in the rate of polymerization 20 times the result. The five component initiator system, however, is general not as stable as the other systems. It can be made through the fifth component lose achieved additional sensitivity during aging. For example In one of these systems, the sensitivity decreased after an aging period of lost a week at room temperature.

The sensitivity of the five component system is proportional to the Concentration of the oxygen-eliminating compound, however, takes place above a certain concentration (e.g. 600 mg 2-allylthiourea to 5.0 g coating solution) Crystallization of the oxygen-consuming compound or thermal polymerization instead of.

When the photopolymerizable layer is exposed in the fresh state the rate of polymerization is an ASA sensitivity value of 0.10, d. H. an exposure in the camera of 3 / .l seconds at f / 3.5, in bright Sunlight equivalent.

The monomer-binder combination is used to produce a recording material in a suitable solvent, d. H. Acetone, methanol, methylene chloride or Water, dissolved and the bis-imidazolyl derivative and the free-radical electron donor added in dissolved form.

After the monomer-binder solution containing the bis-imidazolyl derivative and contains the radical-forming electron donor, has been sufficiently stirred the solution is applied to a layer support and left to dry. The mixtures can be mixed well with conventional mixers or mills. Possibly a cover sheet, as described, for example, in US Pat. No. 3,060,026, can be coated on the photopolymerizable layer, or the layer can be coated with a layer of wax, as described in U.S. Patent 3,203,805. The photopolymerizable recording material is then ready for exposure. The multi-component system enables photopolymerization with blue light and ultraviolet light.

The photopolymerizable mixture can be used as a thermoplastic layer be applied. It then preferably consists of a) a thermoplastic polymer Compound that is solid at 50 ° C, b) an ethylenically unsaturated compound with a softening effect on the thermoplastic compound, the component being a) in an amount of 3 to 97 parts by weight and component b) in an amount is present from 97 to 3 parts by weight. The molecular weight of the ingredient b) is preferably below 1500.

These mixtures are such that they can be used at temperatures below 40 ° C does not soften and no significant change in the softening temperature takes place when it is up to 15 seconds at the original softening temperature of the mixture are kept. A preferred photopolymerizable mixture can furthermore, from 0.001 to 2.0 parts by weight of an inhibitor for thermal addition polymerization contain per 100 parts by weight of components a) and b).

The polymerized binders are suitable as thermoplastic macromolecular binders Methyl methacrylates, polyvinyl acetals, such as polyvinyl butyral and polyvinyl formal, Vinylidene chloride copolymers, butadiene acrylonitrile copolymers, chloro-2-butadiene-1,3 polymers, Cellulose esters, polyvinyl esters, polyvinyl chloride and vinyl chloride copolymers, polyurethanes or polystyrene.

A photopolymerizable layer of the above is used for imaging exposed to actinic light until substantial addition polymerization in the exposed parts of the image and practically no polymerization in the unexposed image parts of the layer takes place, whereupon the latter Parts are removed by a development process. The development can go through Washing with a solvent, thermal transfer, transfer by pressure, Application of pigments to the unpolymerized parts of the image or through different ones Adhesion of the exposed to the unexposed parts of the image take place. In the Development creates either a relief surface or an image on a separate one Image receiving material.

Suitable as inhibitors that prevent thermal polymerization in the photopolymerizable mixtures p-methoxyphenol, hydroquinone and alkyl and acrylic-substituted hydroquinones and quinones, t-butylcatechol, pyrogallol, copper resinate, Naphthylamine, ß - naphthol, copper (I) chloride, 2,6-di-t-butyl-p-cresol, phenthiazine, Pyridine, nitrobenzene, dinitrobenzene, p-toluenequinone and chloranil as well as thiazine dyes, z. B. Thionine Blue G (C. 1. Basic Blue 25) and Toluidine Blue O (C. 1. Basic Blue 17).

Various dyes, pigments, and thermographic compounds color-forming components can be added to the photopolymerizable mixtures, to get different results after developing. These additives are allowed however, do not absorb excessive amounts of radiation at the wavelength of exposure or inhibit the polymerization reaction. They are in U.S. Patent 3,060 026, column 6, lines 4 to 47.

The photopolymerizable recording materials can be applied by application of layers of the mixtures on any substrate. Usual Interlayers can be used to make up the photopolymerizable layers to be anchored to the substrate. A wide variety of dyes, Pigments, anchoring agents, e.g. B. Si0 # z, be present.

As can be seen from the examples, the polymerization with the initiator systems described not only by exposure to ultraviolet light, but also by exposure to light sources, predominantly or exclusively emit visible rays. For example, ordinary daylight are sufficient for the photopolymerization of many of the mixtures described here. Suitable are also light sources of moderate intensity, which generate a high proportion of radiation emit in the visible spectrum. Light with a high proportion of violet light is also suitable.

The invention achieves that a dry photopolymerizable Recording material becomes available that has enhanced sensitivity in the visible Areas of the spectrum has. This enables printing inks of various kinds to be copied Shades and color reproductions. With the invention, so much becomes photographic Sensitivity achieved that the photopolymerizable materials for enlargement copying and can be used to produce recordings in cameras.

Due to the fast and high quality image production and the extreme Contrast that is possible with the materials of the invention have applications in the graph, d. H. in high contrast reproduction photography.

The photopolymerizable recording materials which contain the initiator systems of the mixtures according to the invention are also suitable for the production of printing plates, as described in U.S. Patents 2,760,863 and 2,791,504 , and also for copying for office purposes. Thermal transfer can transfer images to an image receiving material. A larger number of prints can be made here. A large number of copies can also be made of the transferred image. The recording materials can also be used for the production of multicolor reproductions. Example 1 A standard solution was prepared from the following ingredients: 110.0 g of a 10 weight percent solution of cellulose acetate butyrate in acetone, 32.5 g of a 10 weight percent solution of cellulose acetate in acetone, 30.0 g of pentaerythritol triacrylate, 2.0 g of polyethylene oxide with an average molecular weight of 400 in 14 ml of ethanol and acetone in the amount required to make up to 200.0 g. The cellulose acetate butyrate contained 20.5% acetyl groups, 260% butyryl groups, 2.5% hydroxyl groups and had a viscosity of 9.0 to 13.5 poise, determined according to ASTM - method D-1343-54T in a solution which was given as formula A , ASTM Method D-871-54T. The cellulose acetate contained 39.4% acetyl groups and 550/0 bound acetic acid and had a viscosity of 130 to 182 poise, determined according to ASTM method D-1343-56 in a solution which is available as formula A, ASTM method D-871- 56, is designated.

80 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl were added to 5.0 g of this solution and 100 mg of carbon tetrabromide. The solution was then stirred and reduced to a 25 #Lm thick substrate made of polyethylene terephthalate with a thickness of 0.15 mm (when wet). The support was made with an intermediate layer made from a copolymer of vinylidene chloride, methyl acrylate and itaconic acid, as described in U.S. Patent 2,779,684. After the drying time of 30 Minutes at room temperature was a 25 μm thick film made of polyethylene terephthalate applied to the photopolymerizable layer.

The layer structure was placed on a master copy and for 30 seconds exposed with a flood lamp from a distance of 16 inches. The layers of the exposed sample were then separated, whereupon, as in U.S. Pat 3 060 023 described, was developed by thermal transfer. The sample was then placed on an image-receiving sheet of paper and between two rollers carried out, which were heated to 125 ° C.

The underexposed parts of the photopolymer layer came on Over the image-receiving sheet, leaving a black, high-contrast image on the paper was obtained. This result shows that a 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl compound in combination with carbon tetrabromide; that is a radical donating electron donor compound which triggers photopolymerization. Example 2 A standard solution was based on the prepared in the manner described in Example 1 with the exception that 52.5 g of cellulose acetate solution, 30 g pentaerythritol triacrylate together with 100 mg erythrosine (C.I. Acid Red 51) be used.

A sample A was prepared by adding 5.5 g of this standard solution 0.15 g of 2-allylthiourea in 1 ml of acetone were added and the resulting solution was stirred. This sample served as a control as it was an example of a known one Combination of a photo-reducible dye with a reducing agent.

A sample B was prepared by adding an additional 5.5 g of the standard solution 0.15 g of 2-allylthiourea in 1 ml of acetone, 80 mg of the leuco dye tris (4-N, N-diethylamino-o-tolyl) methane trihydrochloride in 1 ml of methanol and 60 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl in 1 ml of acetone.

A sample C was prepared by adding an additional 5.5 g of the standard solution 0.15 g of 2-allylthiourea in 1 ml of acetone, 40 mg of the leuco dye tris (4-N, N-diethylamino-o-tolyl) methane trihydrochloride in 1 ml of methanol and 150 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl in 1 ml of acetone.

Sample D was prepared in the same manner as Sample B. with the exception that 5 mg of erythrosine (C.I. Acid Red 51) are used before coating Solution were given.

Another solution was made by adding 5 mg erythrosine, 40 mg of the leuco dye in methanol, 80 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl in acetone were added to 6.5 g of the standard solution. To this solution, which is available as a Solution E, 600 mg .2b-allyl; thiourea in acetone was added.

After the addition, the above solutions were stirred for 2 hours. They were then separately applied to a 25 μm thick film support made of polyethylene terephthalate, which contained the intermediate layer mentioned in Example 1, in a thickness (in the wet state) of 0.15 mm using a doctor blade. After a drying time of 30 minutes at room temperature, during which the solvents were evaporated, a 25 µm thick film of polyethylene terephthalate was applied to the coating, as described in US Pat. No. 3060026.

The samples were then heated with a carbon arc of 220V and 70A exposed from a distance of 16 inches. The photopolymerizable recording material was in a copy frame with a glass wall behind a sensitometer gray wedge attached, the illuminance of which increased by a factor of `2 from step to step. After exposure and development, a relative exposure number is based on determines the amount of light required to prevent thermal transmission. This figure is valuable for comparing the sensitivities caused by the different Initiator systems are produced, especially with regard to development through thermal transfer.

This arbitrary speed number or minimum relative exposure is defined as I '- t (seconds), where I' is the light intensity that caused polymerization in t seconds. The attenuation of light by the sensitometer wedge was expressed as log I '= log I-D , where 1 is the arbitrary light intensity of the carbon arc set at 100 and D is the density of the wedge at the boundary between transferred area and untransferred area during thermal transfer development . Thus I '= antilog (2-0.05 N), where N is the number of polymerized stages and 0.05 is the density difference between any two successive stages of the wedge.

The intensity values for the 30 steps of the wedge are summarized in the following table. I'-values: Light attenuation due to the gray wedge with an increase in illuminance by a factor of 2: I '= Antilog (2-0.05N). N I ' 1 89.2 2 79.5 3 70.8 4 63.1 5 56.3 6 50.1 7 44.6 8 39.9 9 35.5 10 31.7 11 28.2 12 25.2 13 2 ', 4 14 20.0 15 17.8 16 15.4 17 14.2 18 12.9 19 11.3 20 10.0 21 8.9 22 8.0 23 7.1 24 6.3 N 25 5.6 26 5.0 27 4.5 28 4.0 29 3.5 30 3.2 It can be seen that the scale is reversed: the lower the speed number, the faster the rate of polymerization.

The exposures were up to full power of the coal arc as well Also made through a Wratten # 12 gelatin filter, all of the light sieved below 500 nrn. The exposure at full power was 1/2 second and through the filter 2 seconds.

The exposed samples were then split and thermally Transmission developed. The split samples were layered side up laid down on the sheet to be picked up and with it through two hot rollers (125 to 140 ° C) out, which exerted a pressure of 0.54 kg / cm. The not polymerized Portions of the layer were transferred to the image-receiving sheet while those polymerized Parts of the layer remained on the polyethylene terephthalate substrate.

The exposure numbers were determined in the manner described. The results are given below. Relative Sample initiator system exposure number without filter Filter # 12 A 2-allylthiourea Erythrosine ......... 147 306 B- 2-allylthiourea Erythrosine leuco color stofl-bis-imidazolyl- Connection ........ 6 31 C2-allylthiourea Erythrosine leuco color substance-bis-imidazolyl- Connection ........ 4 31 1) 2-Allvlthiourea Ervthrosine Leuco Color stofi-bis-imidazolyl- Connection ........ 7 20 E 2-Allylthiocarbon Erythrosine Leukof- # trb- SUBSTANCES bis-imidazolyl- Connection ........ 1.8 39.9 Other coatings identical to sample B. have been produced. One layer was held in the copy frame in which the step wedge was copied on by reflex exposure with a flash of an electronic flash unit (power consumption 45 W-sec.) At 5 cm. The thermal transfer development of the film revealed. that the lightning triggered the polymerization. Another layer was used to record an original in a camera, which consisted of white strips of paper on a black background. The picture was taken in direct sunlight at f / 3.5 with exposure times between 15 and 30 seconds. After thermal transfer development, prints of the original were made on an image-receiving sheet of paper.

Another layer was produced by a slide through a 750 W projector, Focal length 30.5 cm, lens f / 3.5, exposed for 5 seconds from a distance of 1.83 m. After development by thermal transfer, a reproduction of the slide was made obtained in 4x magnification on the image receiving material.

On a layer that was identical to sample l) was with a Camera recorded a magazine page. The exposure was 1 minute in light Sunlight, f / 3.5. Thermal transfer development gave a Reproduction of the page. Example 3 A coating solution was made up of the following Ingredients produced: 0.14 g of a 10 weight percent solution of cellulose acetate butyrate in acetone (see Example 1), 0.09 g of a 10 weight percent solution of cellulose acetate in acetone (see Example 1), 0.45 g of pentaerythritol triacrylate, 0.02 g of polyethylene oxide of the average molecular weight 4000 in methanol and acetone in the missing 2.75 g Lot.

To this solution, 35 mg of the free base of the leuco dye bis - (4 - N, N - diethylaminoo-tolyl) benzylthiophenylmethane with a neutral hue in methanol and 76 mg of 2,4,5-triphenyl-4,4'-bis- imidazolyls (isomer B) i, "ax = 280 nm, in methylene chloride. The solution was stirred, applied to -n layer support and exposed as in Example 2 with the exception that the filter used (No. 2 C) under the radiation 400 nm filtered out. After exposure, the layer was developed by thermal transfer in the manner described in Example 1.

The result showed that the polymerization by the combination triggered by leuco dye and bisimidazolyl compound. The exposure number for the direct exposure was 4.0, while for the .exposure through the Filter # 2 was C 16. These relative exposure numbers show that this two component material has an approximate ASA Sensitivity Number of 0.002. Example 4 A standard solution was prepared in the manner described in Example 2 with the exception that 200 mg of erythrosine (C.I. Acid Red 51) were used in place of 100 mg. to 5.5 g of the standard solution, 5 mg of erythrosine in 1 ml of methanol, 160 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bisimidazolyl in 2 ml of methanol and 80 mg of the blue leuco dye tris (4-N, N-diethylamino-o-tolyl) -methanirihydrochlorid given. In this example the chloride of the leuco dye was used. This Salt was produced by bubbling HCl gas through an ethereal solution containing the contained the dye. The ether was evaporated and the crystals obtained dried over phosphorus pentoxide (P205).

The resulting solution was used for coating, exposure and development made in the manner described in Example 2. The relative exposure number for direct exposure of this three-component initiator system was 2.5, and when the No. 12 filter was used, it was 44.6. The relative exposure number 2.5 corresponds approximately to an ASA sensitivity number of 0.004.

More samples were made. With one of these samples a Microfilm recorded by a 750 W projector with an exposure time of 2 minutes. This produced a sharp image with a 9x magnification of the original microfilm received a recording material.

Another sample was in a camera for 17 seconds at f / 3.5 in exposed to bright sunlight, leaving a high-contrast image after thermal transfer was obtained. Example 5 A standard solution was based on that described in Example 1 Way made. To 2.75 g of this solution, 5 mg of erythrosine in methanol, 35 mg of the hydrochloride of the leuco dye bis (4 - N, N - diethylamino - o - tolyl) - benzylthiophenylmethane (neutral shade), in methylene chloride and 88 mg of 2,4- (p-dimethoxyphenyl) -5-phenyl-1,1'-bisimidazolyl given in methylene chloride. The solution obtained was based on that described in Example 2 Way layered on the substrate. The layer was dried at room temperature and aged for a day. The layer was then applied to that described in Example 2 Way exposed with the exception that a filter No. 2 C, as described in example s, was used and the exposure time was 0.25 seconds.

The relative exposure number for direct exposure was 1, and when exposed through No. 2 C filter, it was 2. The ASA speed number this initiator system is thus approximately 0.01.

Additional samples of this layer were taken in a camera at exposure times exposed between 5 and 10 seconds and f / 3.5 in 'bright sunlight. The development thermal transfer gave the samples sharp images on the image receiving materials. Example 6 About the advantage of various photo-reducible dyes in the four-component system To illustrate, the following experiment was carried out: A standard solution was prepared in the manner described in Example 1. To 2.75 g of this solution 40 mg of 2- (o-chlorophenyl) -4,5-diphenyl-1,1'-bis-imidazolyl in methanol and 20 mg of the chloride of the blue leuco dye tris (4-N, N-diethylamino-o-tolyl) methane trihydrochloride given in methanol.

To two further parts of 2.75 g each of the standard solution were added 40 mg of the bis-imidazolyl compound, 20 mg of the leuco dye and 5 mg of two energy transferring substances Given sensitizer dyes. The added dyes are below in the table of results. . To three other parts of each 2.75 g were 160 mg of the bis-imidazolyl compound, 80 mg of the leuco dye and 2.5 mg of other energy transfer sensitizer dyes given. lot The type of dyes added are given in the table below.

The individual solutions were coated onto the layer support, exposed for 1 second directly through the carbon sheet and developed as described in Example 2. The following results were obtained: Energy transferring Relative load Sensitizer dye amount luminous number - 63 Erythrosine (CI Acid Red 51) 5 mg 25 Methylene blue (CI basic blue .................. 5 mg 41 Phloxin B (CI Acid Red 92) 2.5 mg 10 Eosin Y (CI Acid Red 87) 2.5 mg 11 4,5-dibromofluorescein ..... 2.5 mg 10 Example 7 In order to illustrate the use of the various dimers with the leuko dye in the salt form, the following experiment was carried out: A coating solution was prepared in the manner described in Example 1. Part of this solution was divided into seven parts of 2.75 g each. 10 mg of erythrosine and 40 mg of the hydrochloride of the blue leuco dye tris (4-N, N-diethylaminoo-tolyl) methane trihydrochloride in methanol were added to each of these seven parts. A different dimer in methylene chloride was added to each sample. The dimer added is shown in the table of results.

The seven parts were coated onto the support, exposed and developed as described in Example 2. The following results were obtained: Quantity Relative exposure number Dimer filter filter mg direct 2 C # 12 2- (o-chlorophenyl) - 4,5-diphenyl-. 1,1'-bis-imidazolyl 80 15 41 80 2- (o-fluorophenyl) - 4,5-diphenyl- 1,1'-bis-imidazolyl 76 25 80 290 2- (o-methoxyphenyl) - 4,5-diphenyl- 1,1'-bis-imidazolyl, 78 13 41 80 2- (p-methoxyphenyl) - 4,5-diphenyl- 1,1'-bis-imidazolyl 82 70 160 2000 2- (p-methyl mercapto- phenyl) -4,5-di- phenyl-1,1'-bis- imidazolyl ...... 84 15 61 2000 2,4,5-triphenyl 1,2'-bis-imidazolyl (Isomer A) ..... 76 22 42 92 Dark amount Relative exposure number Filter filter mg direct 2 C # 12 2,4,5-triphenyl 4,4'-bis-imidazolyl (Tsomeres B) ..... 76 160 560 2000 Example 8 In order to illustrate the use of the various bisimidazolyl compounds with the free base of the leuco dye, the following experiment was carried out: A standard solution was prepared in the manner described in Example 1. Of this, 3 parts of 2.75 g were removed. 5 mg of erythrosine and 35 mg of the free base of the leuco dye bis (4-N, N-diethylamino-o-tolyl) -benzylthiophenylmethane (neutral shade) were added to each of the 3 parts. A different bis-imidazolyl compound in methylene chloride was added to each of these parts. The respective bis-imidazolyl compound is given in the table.

The 3 parts were applied to the substrate, exposed and developed as described in Example 2. The following results were obtained Relative exposure number Dimer amount direct filter filter mg 2 C # 12 2,4- (p-dimethoxy) - 5-phenyl-1,1'-bis- imidazolyl ....... 88 12 45 148 2- (p-methyl mercapto- phenyl) -4,5-di- phenyl-1,1'-bis- imidazolyl ....... 84 7 20 70 2,4,5-triphenyl 4,4'-bis-imidazolyl (Isomer B) ..... 76 17 64 2000 Example 9 A standard solution was prepared in the manner described in Example 1. 5 mg of erythrosine and 80 mg of 2- (o - chlorophenyl) - 4,5 - diphenyl-1,2'-imidazolyl in methylene chloride were added to 4 parts of 2.75 g each of the standard solution. A different leuco dye was added as the free base in methanol to each of these parts. The particular dye added is shown in the table.

The samples were applied to the support, exposed through filters No. 2 C and No. 12 and developed as described in Example 2. The following results were obtained: Relative exposure number Leuco dye amount without filter filter mg filter 2 C # 12 Tris- (4-N, N-Di- ethylamino o-tolyl) methane trihydrochloride 40 17 32 80 continuation Relative exposure number Leuco dye amount without filter filter mg filter 2 C # 12 Bis- (4-N, N-diethyl- amino-o-tolyl) - thienylmethane .. 28 28.5 92 560 Bis- (4-N, N-diethyl- _amino-o-tolyl) - methylenedioxy phenylmethane .. 30 36 133 723 Bis- (4-N, N-diethyl- amino-o-tolyl) - benzylthiophenyl methane. . . . . . . . 35 36 105 663 Example 10 Four coating solutions were prepared with different polymerizable monomers from the following ingredients: 1. 0.5 g polyethylene glycol diacrylate, 0.5 g of a 10 weight percent solution of Cellulose acetate in acetone, 2.0 g of a 10 weight percent solution of Cellulose acetate butyrate in acetone, 10 mg erythrosine, 40 mg blue leuco dye hydrochloride Tris - (4 - N, N - diethylamino - o - tolyl) - methane in methanol, 80 mg des 2 - (o - chlorophenyl) 5 - diphenyl 1,1'-bis-imidazolyls. 2. 0.5 g triethylene glycol diacrylate, 0.5 g of a 10 weight percent solution of Cellulose acetate in acetone, 2.0 g of a 10 weight percent solution of Cellulose acetate butyrate in acetone, 10 mg erythrosine, 40 mg hydrochloride of the same blue leuco dye in methanol, 80 mg of the same bis-imidazolyl compound in methylene chloride. 3. 0.5 g of polyoxyethylated trimethylolpropane tri acrylate (average molecular weight 1500), 1.0 g 10% solution of cellulose acetate in Acetone, 2.0 g 10% solution of cellulose acetate buty- rat in 'acetone, 10 mg erythrosine, 40 mg hydrochloride of the leuco dye, 80 mg of the bis-imidazolyl compound corresponds to chend l., 0.0005 g p-methoxyphenol. 4. 0.6 g polytetramethylene glycol diacrylate, CHt = CHCO (- OCH2CH2CH2CH2) n OCOCH = CH2 (n = 16, average molecular weight 1400), 1.5 g 10 weight percent cellulose acetate butyrate, 1 ml acetone, 10 mg erythrosine, 40 mg hydrochloride of the leuco dye, 80 mg of the bis-imidazolyl compound corresponds to corresponding 1., 0.0006 g p-methoxyphenol. The same cellulose acetate and cellulose acetate butyrate as in Example 1 were used. The four solutions were applied to the support, exposed directly through the carbon sheet and developed as described in Example 2, the following results being obtained: Layers Relative exposure number 1 80 2 61 3 470 4 160 These results show that the three-component system is able to initiate all monomers. The lower sensitivities in layers 3 and 4 are due to the presence of p-methoxyphenol as an inhibitor of thermal polymerization.

Example 11 A standard solution was prepared in the manner described in Example 1. The following additives were added to 15.0 g of this solution: 30 mg erythrosine, 120 mg of blue leuco hydrochloride dye Tris - (4 - N, N - diethylamino- o-tolyl) methane trihydrochloride in methane thenol, 240 mg des 2 - (o - chlorophenyl) - 4,5 - diphenyl bis-1,1'-imidazolyls in acetone, 90 mg stannous chloride, Methanol and acetone to make up to 20.0 g. A second coating solution, Solution B, was prepared by adding the following additives to 2.75 g of the standard solution: 0.10 g polyethylene glycol diacrylate, 10 mg erythrosine, 70 mg of the free base of the neutral leuco color substance bis- (4-N, N-diethylamino-o-tolyl) - benzylthiophenylmethane in methanol, 160 mg des 2 - (o - chlorophenyl) - 4,5 - diphenyl bis-1,1'-imidazolyls in acetone, 30 mg stannous chloride. The two solutions were applied to the layer support, exposed and developed as described in Example 2. Sample B was only exposed directly through the carbon arc, while sample A was also exposed through filter # 12. The following results were obtained Relative exposure number layer without filter filter no.12 A 0.4 3; 2 B 0.18 - With a layer identical to the sample A, an object was photographed with a camera. The conditions were as follows: Exposure time: 6 seconds, cloudy sky, f / 3.5. Thermal transfer development resulted in a reproduction of the subject.

Another layer, which was identical to sample A, was used with exposed on the carbon arc for 1/2 second from a distance of 16 inches. The sample was placed in a copy frame and used to hold a negative with continuous Tonal values used. The thermal transfer development gave a reproduction of the negative.

A step wedge was copied onto further layers, which were identical to sample A, in a lightning sensitometer, in which the illuminance levels increased by a factor of V-2 from step to step. In the case of one exposure, the exposure time was Ihow seconds at 7000 meter candles / second. Another layer was exposed twice at 1/10000 second at 130 meter candles / second. Polymerization was initiated by both exposures.

With a layer that was identical to sample B, in one Camera at f / 3.5 and 3 seconds took a picture, taking a picture after thermal Transfer was received. Two flood lamps were used for the exposure.

The ASA sensitivity number for the five component system samples using stannous chloride as the fifth component is about 0.1.

Claims (1)

Claim: Photopolymerizable mixture with a) at least one non-gaseous, ethylenically unsaturated, free-radically polymerizable compound, b) at least one amine, in particular a tertiary amine, an amine-substituted one Leuco dye, in particular a dialkylamino-substituted leuco dye, one Mixture of a leuco dye and a photo-reducible dye, a mixture from a leuco dye and triethanolamine, a photolytic halogen compound, Ascorbic acid, 2-allylthiourea or thiourea as a free-radical electron donor, c) a light-sensitive, radical-donating polymerization initiator, d) optionally a sensitizing dye and e) optionally an oxygen-eliminating dye Compound, characterized in that it is a photolytic polymerization initiator Contains 2,4,5-triphenyl-bis-imidazolyl derivative.