JPH0241734B2 - - Google Patents

Description

Claim 1: a) a polymeric binder, b) a bleachable or leuco dye, c) a nitrate and d) a photosensitive diazonium salt, wherein the imageable layer is heated for no more than 60 seconds and no more than 200°C. When heated, the nitrates in this layer are converted into oxidized amounts of HNO ₃ , NO,
Imageable layer capable of releasing _NO2 or _{N2O4 .} 2 the leuco dye is present as at least 0.3% by weight of the layer, the nitrate is present in a molar ratio to the leuco dye of at least 0.1 nitrate/0.1 dye, the diazonium salt is present as at least 0.1% by weight of the layer, and the binding agent is at least 25% by weight of the layer
The layer according to claim 1 comprising: 3. A dye having an oxidation potential of +1.0 or less is present such that there is an optical density of at least 0.1 in the layer from the dye, and nitrate ions are present in a molar ratio to said dye of at least 0.1 nitrate/1.0 dye. The layer according to claim 1. 4. Claim 1, wherein an acid is also present in said layer.
Term, 2nd term or 3rd term layer. 5. The layer of claim 4, wherein said acid is an organic carboxylic acid. 6. Claim 1, 2, 3 or 4, wherein the nitrate ion is present as a metal nitrate.
layer of terms. 7. The layer of claim 6, wherein said metal nitrate is present as a hydrated metal nitrate. 8. Claims 1 and 2, wherein the metal nitrate is at least one hydrated metal nitrate from the group consisting of zinc, cadmium, nickel, aluminum, iron, tin, copper, magnesium, chromium, cobalt, and calcium. Or the layer in Section 3. 9 said leuco dye is present in at least one of said layers
% by weight and wherein said nitrate provides at least 0.5 moles of nitrate ions per mole of leuco dye. 10. The layer of claim 3, wherein said dye comprises at least 1% by weight of said layer and said nitrate provides at least 0.5 moles of nitrate ion per mole of dye. 11 The above leuco dye consists of leuco crystal violet, leucomalachite green, leucomalachite blue and 1(2-(1,3,3-trimethylindolyl))-2-(p-morpholinyl phenyl)ethene. The layer of claim 9 selected from the types. 12 The binder comprises at least one of the imageable layers.
Claim 9 or 11 constituting 70% by weight
layer of terms. 13 The binder comprises at least one of the imageable layers.
A layer according to claim 4 comprising 70% by weight. 14. Said binder comprises at least one of the imageable layers.
A layer according to claim 8 comprising 70% by weight. 15 Claim 1, in which an antioxidant is present;
2nd, 3rd, 4th or 9th layer. FIELD OF THE INVENTION This invention relates to photosensitive imaging systems. More particularly, the present invention relates to photosensitive, thermally developable diazonium salt imaging systems. SUMMARY OF THE INVENTION The present invention is directed to an imaging system that includes 1) a polymeric binder resin, 2) any bleachable or leuco dye, 3) a nitrate salt, and 4) a photosensitive diazonium salt. Besides these active ingredients, materials that supply hydrogen ions, such as acidic materials, and especially acids, are desirable ingredients. Both positive and negative acting systems can be created. After exposing the system, application of heat develops the image by either bleaching the dye or oxidizing the leuco dye in either the exposed and unexposed areas more rapidly. The presence of acidic materials promotes bleaching or color development. When a leuco dye is used instead of a dye, the leuco dye is oxidized upon application of heat to form a colored dye. A positive or negative working system results because of the different rates of oxidation that occur in exposed and unexposed areas.

[Detailed description of the invention]

There are a minimum of four components in the imaging system of the present invention, and five components in the preferred configuration. The four necessary ingredients are 1) a bleachable or leuco dye, 2) a nitrate, 3) a photosensitive diazonium salt, and 4) a polymeric resin. Acidic materials constitute a preferred fifth component. Binders Natural or synthetic polymeric binders can be used in the practice of this invention. It has been found that the PH of the resin only affects the rate of bleaching or coloring effect. If this speed is not critical, any resin can be used. Organic polymeric resins, preferably thermoplastic resins (although thermoset resins can also be used) are generally preferred. If speed is more important, a more acidic resin should be used, or acid should be added to the system to lower the PH and increase the rate of bleaching or coloring (i.e., leuco dye oxidation). . These resins, such as polyvinyl acetals, polyesters, polyvinyl resins, polyvinylpyrrolidone, polyesters, polycarbonates, polyamides, polyvinyl butyrals, polyacrylates, cellulose esters, copolymers and blends of these types of resins, etc. have been used with good results. ing. Natural polymeric materials such as gelatin and gum arabic can also be used. If the dye to nitrate ratio and activity require specific development times and temperatures, the resin must withstand these conditions. Generally, this polymer is heated at 200〓(93
It is preferred not to decompose or lose its structural integrity at 260 °C (127 °C) for 30 seconds, and most preferably not to decompose or lose its structural integrity at 260 °C (127 °C) for 30 seconds. Beyond these minimum requirements, there is nothing critical in the choice of binder. In fact, transparency and translucency are not necessary, although they are desirable.
For example, if the polymer itself is opaque white, the areas that are bombarded with light and heat treated with the decolorizable system will become white and the untreated areas will remain the color of the dye. This binder serves a number of further important purposes in the configuration of the present invention. The imaging material is protected from ambient conditions such as moisture. The consistency of the coating and its image quality are improved. The durability of the final image is also significantly improved. This binder is added to the layer at least
25% by weight component, more preferably 50% by weight
and most preferably at least 70% by weight of dry ingredients (i.e. excluding solvent in the layer)
It should exist. Nitrates Nitrates themselves are well known. It is provided in the form of various compounds, preferably as a metal salt, and optimally as a hydrated metal salt. Other ions that are normally good oxidizing ions such as nitrite, chlorate, iodate, perchlorate, periodate and persulfate do not give comparable results. Very active oxidizing agents, such as iodates, do not behave nearly as well as nitrate ionic compositions, even when used in relatively small proportions, to prevent complete and direct oxidation or decolorization of the dye. The performance of nitrate is superior to any other ion and is clearly unique in the practice of this invention. Some good acid ions other than nitrate will yield an image maximum density (Dmax) of about 0.90 and a minimum density of 0.25 in its best configuration, while good configurations with nitrate ions will have a Dmax of 1.0 or higher.
and can have a Dmin of 0.20 or 0.10 or less. Most means of providing nitrate ions to the composition are satisfactory. Metal salts, acids, acid salts and other means of providing this ion are useful. For example, zinc, cadmium, potassium, calcium, zirconium, nickel, aluminum, chromium,
Nitrates of iron, copper, tin, magnesium, lead, silver and cobalt, ammonium nitrate, and ceric ammonium nitrate were used. The nitrate component of the present invention has a concentration of 200% in the imaging layer.
at a temperature not greater than 160 °C and for not more than 60 seconds, more preferably at a temperature not greater than 160 °C and for not more than 60 seconds and most preferably 30
The amount of oxidation when heated no greater than seconds
It must be present in such a form that HNO ₃ , NO, NO ₂ or N ₂ O ₄ is supplied into the bed. This is done with many different types of salts, organic and inorganic, and with a variety of different types of configurations. The reason why the heating of the imaging system is specified to be no more than 200° C. and no more than 60 seconds is based on the rational selection of the general requirements of the imaging system. It is known that heating energy can adversely affect the imaging system when heated above 200° C. for longer than 60 seconds. Heating can physically damage (eg, wrinkle or distort) the supporting substrate and the imaging layer itself. It may also cause thermal degradation of the dye beyond the imaging mechanism of the present invention. Therefore, a necessary requirement for the release of nitrogen-oxygen compounds is that the imaging mechanism of the present invention must be able to be activated with heating energy that does not harm the imaging system, and the above conditions are not specified. It was done. The most convenient way to provide this thermal oxidant feed nitrate is to provide a hydrated nitrate, such as aluminum nitrate nonahydrate (Al(NO ₃ ) _{2.9H 2} O).
When heated in a binder, this salt forms in varying amounts.
Produces HNO ₃ , NO, NO ₂ and/or N ₂ O ₄ . The binder should not have a pH so high that the released nitric acid is quickly neutralized, as this will adversely affect the oxidation performance of the system. Although it is not essential that a completely acidic or neutral PH environment be provided, a PH of 8.5 or higher often completely inhibits oxidation. It is therefore desirable that the nitrate-containing layer have a PH of 7.5 or less, preferably less than or equal to 7.0, and more preferably less than or equal to 6.5. In addition to the hydrated nitrate, the unhydrated salt has a pH below 7.5 and is preferably in a layer of acidic environment, including HNO ₃ in an amount sufficient to provide the oxidation performance necessary for the practice of the present invention. NO, _NO2 and/or _N2O4 can _be provided. For example, ammonium nitrate is 8.0
An imaging system that does not allow good oxidation in the present invention in layers with a PH of 7.0 or higher, but is very acceptable when a mild strength organic acid such as phthalic acid is added to bring the PH below 7.0. is served. In addition to the generally inorganic types of salts mentioned above, organic salts in non-alkaline environments are also very useful in the practice of this invention. In particular, quaternary ammonium nitrate salts, such as guanadinium nitrate, work extremely well in acidic environments, but with an alkaline pH of 8.0 or higher.
The level does not provide any useful imagery. Due to the alkaline environment, any oxidizing agents (e.g. HNO ₃ , NO, NO ₂ and/or N ₂ O ₄ ) released from the nitrates react selectively with hydroxy ions or neutralizing moieties to inhibit dye oxidation. It seems that it is caused to do something. for this reason
It is preferred to have the nitrate environment at a pH of no greater than 7.0, and more preferably less than or equal to 6.5. One additional consideration should be taken in the selection of nitrates, and this is the selection of salts whose cations are non-reactive with the dye. A non-reactive salt is defined in the practice of this invention as a salt whose cation does not spontaneously oxidize the dye with which it is formulated at room temperature. This is easily determined in many ways. For example, a dye and a non-nitrate salt of a cation (preferably a halide) can be co-dissolved in the solution. If this salt oxidizes the dye spontaneously (within 2 minutes) at room temperature, it is a reactive salt. Salts such as silver nitrate, where the cation is itself a strong oxidizing agent, are reactive salts. Ceric nitrate is also reactive, whereas hydrated ceric nitrate is not reactive. Preferred salts are hydrated metal salts such as nickel 6 nitrate.
hydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, ferric nitrate nonahydrate, cupric nitrate trihydrate, zinc nitrate nonahydrate, cadmium nitrate tetrahydrate, These include bismuth nitrate pentahydrate, thorium nitrate tetrahydrate, cobalt nitrate hexahydrate, gadolinium nitrate or lanthanum nonahydrate, and mixtures of these hydrated nitrates. Non-hydrated or organic nitrates can be mixed with these. Organic nitrates are also extremely useful in the practice of this invention. These nitrates are usually in the form of quaternary nitrogen-containing compounds, such as guanadinium nitrate, pyridinium nitrate, and the like. Nitrating dyes are also useful, but again they must be released in an environment that does not neutralize the released HNO ₃ , NO, NO ₂ and/or N ₂ O ₄ . It is preferred to have at least 0.10 moles of nitrate ions per mole of dye. It is even more preferred to have at least 0.30 or 0.50 moles of ions per mole of dye. Even amounts of 1.0 to 100 moles of nitrate ion per mole of dye have been found useful. For dyes with relatively higher oxidation potentials, more nitrate is desirable. Dyes The dyes useful in the bleachable systems of the present invention are any bleachable dyes. In some configurations it is preferable to use an oxidation potential less than or equal to +1.0. These dyes can be selected from any type of dye. These types include methine, indamine, anthraquinone, triarylmethane, benzylidene, monoazo, oxazine, azine, thiazine, xanthene, idigoid, oxonol, cyanine, merocyanine, phenol, naphthol, pyrazolone, etc.
Although not limited to this, most of them are classified using a color index system. Measuring oxidation potential is well known to those skilled in the art. The measurements of the present invention are obtained by measuring the voltage and current transmitted between carbon and platinum electrodes through a suitable solution. The standard solutions used for the measurements given here using a saturated calomel electrode were the appropriate dyes 1-
in absolute methanol with 10 mmol/l
It was 0.1M lithium chloride. Having enough decolorizable dye in the binder before imaging so that at least 15% of the incident radiation (including ultraviolet and infrared) in the 50 nm range is absorbed through the 0.5 mm layer of binder and dye. is preferred. Preferably at least 50 or 75% of the incident radiation is absorbed in the 20 nm range. These ranges must of course be chosen within the spectral absorption region of the particular dye, but absorption in any part of the spectrum is useful. In terms of weight percentages, it is preferred to have at least 0.30% by weight of colorable (ie leuco dyes) or decolorizable dyes compared to the binder. Preferably, there should be at least 0.50% dye by weight of binder and most preferably at least 1% dye, up to 10% or more dye by weight of binder in the layer. . Leuco dyes are well known to those skilled in the art. These are colorless dyes that form colored dyes when subjected to oxidation reactions. These leuco dyes are well known to those skilled in the art (e.g., The Theory of The
Photographic Process, 3rd edition, with Mees
James, pp. 283-4, 390-1, Macmillan Publishing.
NY and Light-sensitive Systems, Kosar, No.
367, 370-380, pp. 406, (1965) Willey and Sons, NY). Among the best known leuco dyes are leucomalachite blue, leuco crystal violet, leucomalachite green and 1(2-(1,3,3-trimethylindolyl))-2-(p-morpholinyl). phenyl)-ethene. Only leuco dyes that can be converted to colored dyes by oxidation are useful in the practice of this invention. Acid or base sensitive dyes such as phenolphthalein and other indicator dyes are not useful in this invention unless they are oxidizable to a colored state. Indicator dyes only form temporary images or are too sensitive to change in the environment. Dyes specifically shown to work with the bleachable systems of the present invention include, but are not limited to: R ₂ = C ₂ H ₅ ; C ₇ E ₁₅ ; (CH ₂ ) ₅ COOH; C ₈ H ₁₇ ;
CH ₂ CH ₂ 0; or CH ₂ COOH R ₃ = H; C ₂ H ₅ O; or C1 R ₄ = C ₂ H ₅ ; or CH ₂ CH ₂ C ₆ H _{5 R2} =H; _-CH2COOH ;also- _CH2CH = _CH2 In the formula, R ₁ = C ₂ H ₅ ; n-C ₃ H ₇ = R ₂ In the formula, R ₁ = H; or -CN R ₂ = -CN; or -SO ₂ CF ₃ = R ₃ R ₂ = H; CH ₃ = R ₃ R ₄ = C ₂ H ₅ ; CH ₂ CH=CH ₂ ; or
CH ₂ CH ₂ CO ₂ C ₂ H ₅ R ₅ = −C ₂ H ₅ ; −CH ₂ CH−CH ₂ ; or −C ₇ H ₁₅ R ₆ = −CH ₂ COOH; −CH ₂ CH=CH ₂ ; or −
_{( CH2} ) _2SO3H In the formula, R ₁ = -C ₂ H ₅ ; -C ₇ H ₁₅ ; or -CH ₂ CH=CH ₂ R ₂ ==S; or C(CN) ₂ R ₃ = -CH ₃ ; or -C ₂ H ₅ In the formula, R ₁ = −C ₂ H ₅ ; −(CH ₂ ) ₂ OH; −(CH ₂ ) ₂ COOH;
−CH ₂ COOH; or −(CH ₂ ) ₃ SO ₃ − R ₂ = −C ₂ H ₅ ; −(CH ₂ ) ₂ OH; −(CH ₂ ) ₂ COOH;
_-CH2COOH ; or _-CH3R3 = _H ; _-CH3 ; _-SCH3 ; or _{-C2H5R4 =} H _; -CH3; Br; or _-N ( _{C2H5 ) 2R 5} = H; _-CH3 ; or -Br In the formula, R ₁ = -CH ₃ ; -C ₂ H ₅ = R ₂ = R ₃ In the formula, R ₁ = -CH ₃ ; or CH ₃ O- R ₂ = -C ₂ H ₅ ; or -C ₇ H ₁₅ In the formula _{, R1} =-OH; _-NH2 ; _-NHC2H5R2 =H; _-OH ; _-OCH3R3 = _H ; _-OH ; or _-NHC2H5 In the formula _{, R1 = H; -CH3; or -C2H5R2 =H; -C2H5 ; or -CH2COOH R3 == S ; or} = _CHNO2 In the formula, R ₁ = H; or CH ₃ O− R ₂ = −C ₂ H ₅ ; −CH ₂ CO ₂ ⁻ (C ₂ H ₅ ) ₃ N ⁺ H In the formula, R ₁ = H; -N(CH ₃ ) ₂ R ₂ = H; -C1 The following two dyes cannot be conveniently classified by the color index system. These examples are not intended to indicate the limitations of the invention. Any dye with an oxidation potential of +1.0 or less can work in the present invention. The structure of the substituents and dyes is not critical. The decolorizable dyes of the invention are preferably colored, i.e. in the visible region of the electromagnetic spectrum (approximately 400 to
700nm), but also absorbs in the infrared region of the electromagnetic spectrum (700-1100nm) and in the ultraviolet region (310nm).
400 nm) and may be colorless. Images in which colorless dyes are used must then be viewed through a filter with an ultraviolet or infrared sensitizer or with some enhancement technique. There is also an optical density of at least 0.1 in the visible part of the spectrum, or sufficient bleachable dye is present in the layer of the invention such that at least 15% of the incident colorless light (including ultraviolet or infrared radiation) is absorbed. You can say that you should. at least 0.5
or an optical density of 0.8 is preferably obtained,
And most preferably there will be enough dye so that an optical density of at least 1.0 is obtained in the layer.
For colorless dyes (e.g. ultraviolet and infrared absorbing dyes) it is preferred that at least 20-40% of the incident radiation is absorbed, and most preferably
At least 60-90% of incident colorless light within 20nm range
should be absorbed. The leuco dye is present at least as much as about 0.3% by weight of the total amount of the photosensitive binder layer, preferably at least 1% by weight, and most preferably at least 2% to 10% or more (e.g. 15%) by dry weight of the imaging layer. Should. This weight percentage is also useful in determining the minimum amount for decolorizable dye. The ratio of nitrate ions and decolorizable dye is 30 seconds
Heating this layer at 260° C. (127° C.) is such that there is at least a 20% reduction in optical density in the exposed areas of the positive working system or the unexposed areas of the negative working system. For mechanical observation of images, lower reductions in optical density are useful. Depending on the relative ease of decolorizing the particular dye chosen, the relative ratio of nitrate ions to dye will vary. Generally, at least 0.1 mole of nitrate ion per mole of dye (either colorable (ie, leuco dye) or decolorizable dye) is desirable in the practice of this invention. More preferred is at least 0.3 or 0.5 mole nitrate per mole of dye, and at least 0.7 or 0.9 mole per mole of dye.
Most preferred is molar nitrate. It is usually desirable for the decolorizable layer of the present invention to provide a 20% or more reduction in optical density when exposed and developed. A reduction in optical density of at least 50% or 60% is preferred, and at least 90% or 95% most preferred. These reductions can be measured in the development temperature for the imaging material, e.g. 130°C for 60 seconds or 155°C for 45 seconds.
seconds. Useful acids that may be present in the present invention are those generally known to chemists of skill in the art. Although organic acids are preferred, inorganic acids (generally in relatively small amounts) are also useful. Also useful are organic acids with carboxyl groups. This acid can be present in a ratio of 0 to 10 times the amount of nitrate ion. More preferably it is present in an amount of 0.2 to 2.0 times the amount of nitrate ion. In forming or coating the imageable layer on the substrate, temperatures that completely color or bleach the layer or decompose the diazonium salt during manufacture should of course not be used. Some coloration or bleaching can be tolerated with initial dyes or leuco dyes selected to allow predictable changes. However, it is preferred that there is little or no oxidation of the leuco dye or dye during formation or coating so that a more standardized layer can be formed. Depending on the expected development temperature, the coating or forming temperature can be varied. Therefore, if the expected development temperature is e.g. 350〓(167℃)
In this case, the drying temperature is 280°C (138°C). It is therefore unlikely that the layer will gain or lose much of its optical density at drying temperatures within 4-5 minutes. Such changes may be tolerated by correspondingly increasing the amount of leuco dye or dye. A reasonable developing temperature range is 180〓 (82℃) to 380〓
(193℃) and a reasonable residence time is 5 seconds ~
5 minutes, preferably 220〓(105℃)~350〓(167℃)
°C) and 10 to 180 seconds, longer times seem to be highly correlated with lower development temperatures. Therefore, absorbance properties should be considered in relation to the generally useful development range of 82-193°C. Photosensitive diazonium salts are well known to those skilled in the art.
These salts contain a photosensitive aromatic nucleus with an outer diazonium group and an anion attached thereto (e.g., Light-Sensitive Systems, Kosar, No. 202).
−214 pages, John Willy and Size, 1965,
NY; and Photographic Chemistry, Vol.
P. Grafkides, pp. 709-725, Furantemp Press, London). These generally have the formula: ArN ⁺ NX ^- (where Ar is the aromatic nucleus and X ^- is the anion) Any anion can be used in the diazonium salt. A variety ^of anions can be used, such as zinc chloride, tri-impropylnaphthalene sulfonate, fluoroborate (i.e., _BF4- ), and bis(perfluoroalkylsulfonyl)methide. Changes in the anion affect the speed of the imaging layer, but not its operation. Any photosensitive aromatic diazonium nucleus known to those skilled in the art can also be used in the practice of this invention. These nuclei are well known to those skilled in the art and include, for example, P-anilinobenzene; N-(4-diazo-
2,4-dimethoxyphenyl)pyrrolidine; 1-
Diazo-2,4-diethoxy-4-morpholinobenzene; 1-diazo-4-benzoylamino-
2,5-diethoxybenzene; 4-diazo-2,
5-dibutoxyphenylmorpholino; 4-diazo-
1-dimethylaniline; 1-diazo-N,N-dimethylaniline; 3-methyl-4-pyrrolidonebenzene; 1-diazo-4-N-methyl-N-hydroxyethylaniline, etc. Photosensitive oligomeric diazonium resins as known to those skilled in the art (e.g., U.S. Pat. No. 2,714,066) are useful and in particular these are simply condensation products of salts (with aldehydes such as formaldehyde) and their photosensitive properties. It is included within the definition of a diazonium salt because it retains its properties and activity. These salts should be present as at least 0.1% by weight of the dry imaging layer, up to 15% or more. Preferably they are present as 0.3-10% by weight of the layer, and most preferably 0.5-5% by weight of the layer and in at least equimolar ratio to the dye or leuco dye. Additional components such as surfactants, antistatic agents,
Flow control aids, antioxidants (eg hindered phenols, phenidone and ascorbic acid) and other common acids may be present in the imaging layer. All this will be more fully understood by considering the example below. Example 1 18 66.67 g of a 15% solution of cellulose acetate butyrate (in a solvent solution containing 10 parts of methyl isobutyl ketone, 20 parts of methanol and 55 parts of acetone) was mixed with 0.05 g of phenidone A, 0.15 g of phthalic acid, 0.49 g of benzotriazole, 1 -Diazo-2,5-dimethoxy-4-morpholinobenzene zinc chloride 0.38 g,
A reference coating solution was prepared by mixing 0.335 g of leuco crystal violet, 4.43 g of methanol, 12.50 g of acetone and 5.00 g of tetrahydrofuran. The indicated amounts of each nitrate as shown in the table below were dissolved in methanol to a total weight of 1 g and added to 9 g of the reference coating. Each final solution was coated onto polyethylene terephthalate film to a 4 mil wet thickness and dried at 71°C for 4 minutes. Each coated film was imagewise exposed to ultraviolet light until the diazonium salt in the photo-shocked area decomposed. A portion of each film was developed at 99° C. and another sample at 139° C. for various times and visually determined when optimal development occurred. The optical densities of the light-shocked (LS) and non-light-shocked (NLS) regions were recorded. The results are shown below, with all development times reported in seconds.

Table: In addition to exhibiting a general usefulness for all the various forms of nitrate, certain unusual properties are observed. Most examples showed little or negligible negative image formation as heated to 9°C. Most examples are
It showed positive image formation when heated to 139°C. Thus, both positive and negative images can be produced from most of the imaging systems of this invention, depending on the development temperature. Example 19 45 Two separate solutions were prepared. One is methanol
19.77g contained 0.23g of Al(NO ₃ ) _{2.9H 2} O. The rest was the same as the reference solution of Example 1-18, except that no diazonium salt was present and only 3.81 g of methanol was added (except that resin was already used). Various diazonium salts in equimolar ratios with the dye were added to the nitrate solution and dissolved. 2 g of this was then combined with 8 g of the dye-containing solution and coated and dried as in the previous example.
The same exposure, development and recording was carried out as in the previous example and the results are shown below.

【table】

Table: Phthalene Sulfonate + Formaldehyde Again, this result indicates general utility for photosensitive diazonium salts. Some are clearly more effective than others and are still capable of producing negative and positive imaging. Example 46 55 Al(NO ₃ ) ₃・9H ₂ O0.23 in 19.77 g of methanol
A nitrate solution was prepared containing g. Adding the selected diazonium salt to this solution to form a 2 g portion;
This was then added to an 8 g portion of the reference coating solution of Example 19-45. These were then coated and dried as in the previous example. Again, the diazonium salt was added to the dye in roughly equimolar ratios. The coated films were exposed, developed and evaluated as in the previous examples.

[Table] Linobenzene sulfate * Polymer salt example 55 A photosensitive system according to the present invention was constructed in the following manner. A solution was prepared by mixing the following components: 0.01 g phenidone A (1-phenyl-3-pyrazolidinone), reducing agent used as stabilizer 0.10 g benzotriazole (stabilizer) 0.03 g bis(perfluoromethylsulfonyl) Methane (CF ₃ SO ₂ ) ₂ CH ₂ 0.06 g 1-Diazo-2,5-diethoxyphenylmorpholinotetrafluoroborate 1.0 g Acetone 0.70 g Ni(NO ₃ ) ₂ ·6H ₂ O in methanol
4.76% by weight solution 3.2g 2.15% by weight solution of leuco crystal violet in acetone and 15g 15% by weight solid solution of cellulose acetate in a 10:20:50 solution of methyl isobutyl ketone, methanol and acetone each. This solution was coated onto polyester to a wet thickness of 31/2 mils and then dried at 71°C for 4 minutes. The dried coated film was imagewise exposed to ultraviolet light to decompose the diazonium salt in the imaged areas. The exposed film was then developed by heating to 139°C with a heated roller. A strong negative image was produced, where the color density was at its maximum at the point of light bombardment. Example 56 Three solutions were prepared. The first one is 0.10 g of crystal violet, 5 ml of methanol and N-
5 ml of methyl-pyrrolidone was added. A second solution was made from magnesium nitrate hexahydrate (Mg(NO ₃ ) _{2.6H 2} O) and 75 ml of methanol. The third solution contained 20 g of cellulose acetate, 10 ml of methyl isobutyl ketone and 70 ml of acetone. First solution 3
ml was mixed with 3 ml of the second solution and 12.5 g of the third solution. To this was added 0.03 g of 3-methyl-4-pyrrolidine-benzene tetrafluoroborate.
This solution was coated onto clear polyethylene tetraphthalate film to a 4 mil wet thickness and dried at 70°C for 4 minutes. The dried film was imagewise exposed to ultraviolet light until the diazonium salt decomposed in the light bombardment zone. Upon heating to 130° C. for 40 seconds, a readable image developed. The dye is bleached more in the light-shocked areas than in the non-light-shocked areas to provide a positive image. Example 58 The previous example was repeated, but instead of crystal violet, an equal amount of malachite green was used. Almost similar results were obtained, but less dense images were produced with malachite green compared to crystal violet. Example 59 Example 55 was repeated, but with an equal amount of leuco dye 1
(2-(1,3,3-trimethylindolyl))-2
-(p-morpholinyl phenyl)ethene was used. Almost similar results were obtained, except that the image was negative, red and slightly less dense. Example 60 Example 55 was repeated, but instead of leuco crystal violet, an equal amount of leucomalachite green was used. After exposure and development as in Example 59, a green positive image was obtained. Example 61 Example 55 was repeated, but instead of leuco crystals, equimolar amounts of leuco dye: It was used. After exposure and development as in Example 55, a pale blue positive image resulted. It is important to note that the development process by which image formation occurs is not understood. Even the positive or negative nature of the imaging system cannot be predicted. For example, the imaging sheet of Example 61 produced a negative image when left at ambient conditions for three days and then exposed and developed. Example 62 Example 55 was repeated, except that the cellulose acetate butyrate solution was replaced with 15 g of a 30% by weight solution of cellulose acetate propionate in a 10:20:40 solution of the same solvent. When imaged and then developed at 99°C, a strong negative image was produced. Example 63 Example 55 was repeated, but in place of leuco crystal violet, equimolar ratios of the following dyes were used: 63 Dye No. 64 Dye No., where R ₁ is and R ₂ is C ₂ H ₅ . 65 Dye No. 66 Dye No. 67 Dye No. 68 Dye No. 69 Dye No. 70 Dye No.XI 71 Dye No., where R ₁ is C ₂ H ₅ , r ₂ is s, and _R3 is _CH3 . 72 Dye No. 73 Dye No.XI 74 Dye No. 75 Dye No. 76 Dye No.XI, where R ₁ is NH ₂ and R ₂
and R ₃ is H. 77 Dye No. 78 Dye No. 79 Dye No. 80 Dye No. L 81 Dye No. L 82 Dye No. ⁾ L 83 Dye No. L 84 Dye No. L 85 Dye No. L Provides high quality images Therefore, no other photosensitizers are required in the construction of the present invention other than those mentioned above. Other ingredients besides those specified herein can, of course, be added as they prove useful. The sheet was coated and dried as in Example 55. Each of the coated polyester sheets was first colored by the presence of dye. Exposure and development were the same as in this example, but the image was now generally positive and the color density was lowest where the light struck. The imaging layer of the present invention must permit reactive bonding between the active ingredients to enable imaging. That is, the individual components cannot be separated by impermeable barriers within the layer, as in a dispersed immiscible phase. Generally, the active ingredients are homogeneously mixed within the layer (eg, a molecular mixture of the ingredients). These are dispersed or mixed within the layer and held individually in a heat softenable binder that softens upon heating to allow movement of the components, but this requires longer development times. The imaging layer of the invention can contain a variety of materials in combination with the essential components of the invention. For example, lubricants, coating aids, antioxidants (e.g. ascorbic acid,
In addition to sterically hindered (hindered) phenols, phenidone, etc. in amounts that do not inhibit oxidation of the heated dye), surfactants, antistatic agents, nitrates, slow oxidizing agents and brighteners are used in the practice of this invention. It can be used without any negative effects. The imaging layer of the present invention must permit reactive binding of the active ingredient to enable imaging. That is,
As with dispersed immiscible phases, the individual components cannot be separated by impermeable barriers within the layer. Generally, the active ingredients are homogeneously mixed within the layer (eg, a molecular mixture of the ingredients). These can be dispersed or mixed within the layer and held individually in a heat-softening binder that softens on heating to allow movement of the components, but this requires longer development times. A rationale for determining the acidity of a coating composition (eg, whether it is below PH 7.0, as discussed below) is to evaluate the stability of the particular diazonium salt in the composition. Using the particular salt of Example 19, if more than 25% by weight of the diazonium salt decomposes, the PH will likely be greater than 7.0. One valuable property of this system is the expansion of the latent image. Expansion in leuco dye-containing compositions means that one or more molecules of dye are formed for each absorbed proton of radiation. degree of expansion,
That is, the ratio of the number of dye molecules formed to the protons absorbed is as high as 1×10 ³ .