Title:
SPEED INCREASING ADDITIVES FOR NON-SILVER LIGHT SENSITIVE SYSTEMS
United States Patent 3660096
Abstract:
Non-silver photographic compositions of the type described in U.S. Pat. No. 3,481,739 issued Dec. 2, 1969, are increased in photographic speed by the addition of one or more compounds from the group consisting of merocyanine dyes, polyphenylmethane carbinol bases and N-methyl diphenyl amines.
US Patent References:
DYE SENSITIZATION OF LIGHT SENSITIVE SYSTEMS
Yamada et al. - March 1970 - 3503745
DYE SENSITIZATION OF LIGHT SENSITIVE SYSTEMS
Yamada et al. - March 1970 - 3503745
Inventors:
Wainer, Eugene (Shaker Heights, OH)
Petro, Victor P. (Brecksville, OH)
Fox, Robert D. (University Heights, OH)
Shirey, John E. (Wickliffe, OH)
Smerillo, John A. (Cleveland, OH)
Petro, Victor P. (Brecksville, OH)
Fox, Robert D. (University Heights, OH)
Shirey, John E. (Wickliffe, OH)
Smerillo, John A. (Cleveland, OH)
Application Number:
04/746008
Publication Date:
05/02/1972
Filing Date:
07/19/1968
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
430/344
International Classes:
G03C1/675; G03C1/73; G03C1/52
Field of Search:
96/90
Primary Examiner:
Torchin, Norman G.
Assistant Examiner:
Winkelman, John
Claims:
We claim
1. In a photosensitive composition comprising:
2. leuco di- and tri-phenylmethanes; and
3. 9,10-dihydroanthracenes represented by the general formula ##SPC1##
4. The composition of claim 12 wherein the N➝ 0 compound is one represented by the general formula R-N➝ 0 wherein R represents an organic moiety such that the resulting compound is an N-oxide selected from the group consisting of tertiary amines, nitrones, and di-nitrones.
5. The composition of claim 12 wherein the N➝ 0 compound is one represented by the general formula
6. The composition of claim 1 wherein the activator is a bromine substituted alkane.
7. The composition including both a leucoanthracene and a merocyanine dye according to claim 1.
8. The combination of claim 5 wherein the merocyanine dye is 5-[3-ethyl-2(3H)- H)-benzoxazolylidene)-ethylidene] -3-phenyl-2-phenylimino-4-thiazolidinone.
9. The composition of claim 1 wherein there are between 0.1 and 2 parts by weight of N➝ O compound for each part by weight of color forming compound.
10. The composition of claim 1 which includes, in addition, a film forming resin binder.
11. The composition of claim 1 wherein R" and R'" are all CH3 groups in the anthracene.
1. In a photosensitive composition comprising:
2. leuco di- and tri-phenylmethanes; and
3. 9,10-dihydroanthracenes represented by the general formula ##SPC1##
4. The composition of claim 12 wherein the N➝ 0 compound is one represented by the general formula R-N➝ 0 wherein R represents an organic moiety such that the resulting compound is an N-oxide selected from the group consisting of tertiary amines, nitrones, and di-nitrones.
5. The composition of claim 12 wherein the N➝ 0 compound is one represented by the general formula
6. The composition of claim 1 wherein the activator is a bromine substituted alkane.
7. The composition including both a leucoanthracene and a merocyanine dye according to claim 1.
8. The combination of claim 5 wherein the merocyanine dye is 5-[3-ethyl-2(3H)- H)-benzoxazolylidene)-ethylidene] -3-phenyl-2-phenylimino-4-thiazolidinone.
9. The composition of claim 1 wherein there are between 0.1 and 2 parts by weight of N➝ O compound for each part by weight of color forming compound.
10. The composition of claim 1 which includes, in addition, a film forming resin binder.
11. The composition of claim 1 wherein R" and R'" are all CH3 groups in the anthracene.
Description:
This invention relates to non-silver photosensitive compositions and to films comprised of such compositions and to their use in photographic processes. More particularly, it relates to improvements to the non-silver photosensitive compositions described in U.S. Pat. No. 3,481,739 issued Dec. 2, 1969, whereby the photographic speed has been greatly increased.
The compositions described in that patent application consisted of at least three constituents, namely: at least one color-forming compound, such as a leuco di-or tri-aryl methane or leuco dye base; at least one activator for accelerating a color change in said compound, for example CBr 4 ; and at least one N➝ 0 compound.
An exemplary composition according to that patent application contained 100 mg of Leuco Crystal Violet, 1.4 grams of CBr 4 , and 15 mg. of 4 -picoline-N-oxide, dispersed in a film of polystyrene. The L.E.S. of this composition approximated 5 × 10 4. L.E.S. stands for Light Exposure Speed and is defined as the reciprocal of the exposure, expressed in meter candle second, which is required to produce a density (diffuse transmission density) of 0.2 density units above the density of base plus fog (see Photographic Science and Engineering, Vol. 8, 1964, page 98, last paragraph).
Briefly, it has been found that the addition of one or more sensitivity dyes and/or polyphenylmethane carbinol bases and/or tertiary amines to the non-silver photosensitive compositions of the types described in U.S. Pat. No. 3,481,739 enhances the sensitivity of the composition and improves the photographic speed thereof. These additives may be used either singly or in combination with one another to produce the enhanced photographic speeds characteristic of the present invention. In addition, N-vinyl carbazole may be added to increase the contrast (gamma) and maximum density.
It has been found that the speed of compositions of the type described in the above noted patent application, the disclosure of which is intended to be incorporated by reference herein, could be significantly increased by the addition of various kinds of materials in suitable amounts, as will appear from the following formulations each of which is exemplary of the addition of various classes of photocatalysts and/or photosensitizers to compositions of the type described in said application.
The compositions hereinafter described are prepared in the same manner as those described in the above-noted patent application and in Photographic Science and Engineering, Vol. 5, number 2, Mar.-April 1961, pp. 98 et seq.
The compositions are each prepared by bringing the constituents together in a suitable solvent-binder solution under a safelight or in total darkness, each of the constituents usually being added to the solution in the order set forth in the examples, then mixed to effect solution before addition of the next named constituent. After thorough mixing, the composition is applied to a suitable substrate which may be baryta paper or a film of polyester, glass or other support.
After the composition has been laid down as a thin film, it is permitted to dry in air in the dark or under a safelight, drying here meaning the elimination of the solvent(s) from the composition by evaporation. Then the composition is photographically exposed for a time sufficient to produce at least a latent image in the composition.
After this photographic exposure, the latent image in the film is developed by exposing the entire film to radiant energy of an appropriate intensity (e.g.) 50 watt tungsten light source) and suitable wavelength (e.g. between about 600 and 900 μ). The films are then fixed by means of a solvent rinse consisting of 4 parts of petroleum ether and 1 part of acetone.
A composition of the type described in the above noted U.S. Patent is as follows:
100 mg. Leuco Crystal Violet 5 mg. 4 -picoline-N-oxide 1 g. Carbon tetrabromide 4 cc. Polystyrene (10 % solution in benzene)
This composition was coated 0.0015 inch on unsubbed 300 -D Mylar. After photographic exposure, the composition was developed with light filtered through a Corning glass filter No. 2412. The formulation produced D max of 0.62 and base plus fog of 0.20 and a photographic speed of 1.9 × 10 - 3 L.E.S.
EXAMPLE 1
The addition of 6 mg. of Rhodamine B base of the above formulation produced a speed of 0.013 L.E.S., D max of 1.32 and base plus fog 0.36. This illustrates the benefits of adding a dye to such a composition.
EXAMPLE 2
A photographic speed of 0.04 L.E.S. with acceptable base plus fog levels was achieved by the addition of minor amounts of merocyanine dyes with or without xanthene type dyes (Rhodamine B, etc.). In addition, it was found that carbinol compounds of the leuco triphenylmethane derivatives appear to be beneficial and increase the density of the image formed. The following composition produced photographic speeds of 0.04 L.E.S.:
12 mg. Leuco Crystal Violet 5 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] -3 -phenyl- 2 phenylimino- 4 -thiazolidinone, a merocyanine dye 10 mg. Carbinol opal blue 1.4 g. Carbon tetrabromide 4 cc. 10 % Polystyrene in benzene
This composition was coated 0.0015 inch on unsubbed 300 -D Mylar. After photographic exposure, the image was developed with light filtered through a Corning glass filter No. 2030. This composition produced maximum densities as high as 1.7 with a base plus fog of 0.20.
EXAMPLE 3
A photographic speed of 0.1 L.E.S. with acceptable base plus fog levels was achieved by the addition of 5 mg of Crystal Violet carbinol to the formulation represented in Example 2. One composition producing photographic speeds of 0.1 L.E.S. was as follows:
12 mg. Leuco Crystal Violet (stabilized) 5 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] 3 -phenyl- 2 phenylimino- 4 -thiazolidinone, a merocyanine dye 5 mg. Carbinol Crystal Violet (stabilized) 1 mg. Carbinol Opal Blue (stabilized) 1.4 g. Carbon tetrabromide 4 cc. 10 % Polystyrene in benzene
The composition was coated 0.0015 inch on unsubbed 300 -D Mylar. The development light source was filtered through a 2030 Corning glass filter. This composition produced a maximum density of 1.06 with a base plus fog of 0.35.
EXAMPLE 4
The addition of a small quantity of a tertiary amine, such as N-methyldiphenylamine, to the composition of Example 3 produced a further increase in speed. A composition was prepared as in Example 3 and 3 drops of a N-methyldiphenylamine solution containing 1 drop of the amine in 5 cc of acetone were added thereto. The resulting composition was coated 0.0015 inch on unsubbed 300 -D Mylar and after photographic exposure, was developed using light filtered through a Corning glass filter No. 2030. This composition exhibited a photographic speed (L.E.S.) of 0.30, base plus fog of 0.32, D max of 1.09.
EXAMPLE 5
It was further found that the addition of a leuco anthracene further increased the maximum density and speed of the film. The composition of Example 4 was modified by the addition of 2 mg of 2,7 -bis(dimethylamino)- 10 -p-dimethylamino-phenyl- 9,10-dihydro- 9,9-dimethylanthracene to the composition of Example 4. The resulting composition was coated 0.0015 inch on unsubbed 300 -D Mylar, exposed and then optically developed with light filtered through a Corning glass filter No. 2030. This composition exhibited photographic speeds in the range of 0.5 to 0.7 L.E.S., a base plus fog of 0.20, and a D max of 1.4.
EXAMPLE 6
The addition of 5 mg. of N-vinylcarbazole to the formulation of Example 5 increased the maximum density to 2.0 and increased the gamma (slope of H & D plot) of the film.
EXAMPLE 7
A substantial improvement was obtained by the increased amounts of both the leuco anthracene and carbinol of crystal violet and omitting the leuco crystal violet, as shown in the following formula:
5 mg. 2,7 -bis(dimethylamino)- 10 -p-dimethylamino phenyl- 9,10 -dihydro- 9,9 -dimethylanthracene 10 mg. Carbinol Crystal Violet 1 mg. Carbinol Opal Blue 7 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene]- 3 -phenyl- 2 -phenylimino- 4 -thiazolidinone 3 drops Amine solution (1 drop N-methyldiphenylamine in 5 cc. acetone) 1.4 g. Carbon tetrabromide 4.5 cc. 10 percent polystyrene in benzene
This composition produced photographic speeds of 1.0 L.E.S., base fog 0.14, with D max rendition of 1.46.
EXAMPLE 8
Still a further improvement in speed is attained with the following which exhibits an L.E.S. of 2.0 to 4.0, a maximum density of 1.4 and a base plus fog of 0.2:
15 mg. 2,7 -bis(dimethylamino)- 10 -p-dimethylaminophenyl- 9,10 -dihydro- 9,9 -dimethylanthracene 5 mg. 5-[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] -3 -phenyl- 2 phenylimino- 4 -thiazolidinone 2 mg. 4 -picoline-N-oxide 10 mg. Carbinol of crystal violet (stabilized*) 1.3 mg. Carbinol of opal blue (stabilized*) 6 drops N-methyldiphenylamine solution** 1.4 g. Carbon tetrabromide - 4.5 cc. 10 % polystyrene in benzene
The stabilization of the carbinols and leucos in the above formulations is accomplished by digestion of the carbinols or leucos with an alkali metal hydroxide, as described in U.S. patent application Ser. No. 711,832 filed Mar. 11, 1968, the disclosure of which is incorporated herein by reference.
It will be readily appreciated that in the above formulations, given by way of example, other materials may be used in place of the specific ingredients exemplified in the formulations. For example, other carbinols may be used in place of the carbinols of crystal violet or opal blue, and other organic halogen compounds of the type described in U.S. Pat. No. 3,095,303 and in the U.S. patents listed therein, preferably those in which three halogen atoms are attached to a terminal carbon atom, may be used in place of CBr 4 , iodoform being a particularly preferred replacement for CBr 4 .
A clear distinction must be kept in mind between the "activator" described in U.S. Pat. No. 3,481,739 and the sensitizers described in the present application. An activator assists in the rapid production of color from the color-forming compound whereas a sensitizer extends the range of actinic radiation to which the composition is sensitive.
Each of the compositions described in the preceding examples is utilized by exposing the same to a pattern of radiation and then developing a visible image by a blanket exposure to radiation in a narrow band corresponding to that region to which the composition has been sensitized by the dye formed during the photographic exposure.
In addition, particular note should be made that in Example 8 the amount of N-oxide has been considerably diminished as compared with the amounts utilized in the earlier indicated U.S. patent, this being due in part to the use of a combination of sensitizers as described.
The purpose of the addition of the sensitizing dye such as a merocyanine dye is to increase the absorption of visible light so as to increase the photographic speed.
The purpose of the addition of the polyphenylmethane carbinols is to increase the photographic speed by an increase in the quantum yield of dye, i.e., by an increase in the inherent sensitivity of the system to an absorbed photon of visible light.
The purpose of the addition of the tertiary amine is to reduce formation of dye from the color-former by thermal reactions with atmospheric ingredients or with other ingredients of the film coating.
The amounts of the additives should be as follows for the best results:
Sensitizing dye 2 to 10 mg./4 cc. Carbinol 1 to 10 mg./4 cc. tertiary amine 1 to 10 drops of a 1 % solution (by vol) in acetone/4cc.
The compositions described in that patent application consisted of at least three constituents, namely: at least one color-forming compound, such as a leuco di-or tri-aryl methane or leuco dye base; at least one activator for accelerating a color change in said compound, for example CBr 4 ; and at least one N➝ 0 compound.
An exemplary composition according to that patent application contained 100 mg of Leuco Crystal Violet, 1.4 grams of CBr 4 , and 15 mg. of 4 -picoline-N-oxide, dispersed in a film of polystyrene. The L.E.S. of this composition approximated 5 × 10 4. L.E.S. stands for Light Exposure Speed and is defined as the reciprocal of the exposure, expressed in meter candle second, which is required to produce a density (diffuse transmission density) of 0.2 density units above the density of base plus fog (see Photographic Science and Engineering, Vol. 8, 1964, page 98, last paragraph).
Briefly, it has been found that the addition of one or more sensitivity dyes and/or polyphenylmethane carbinol bases and/or tertiary amines to the non-silver photosensitive compositions of the types described in U.S. Pat. No. 3,481,739 enhances the sensitivity of the composition and improves the photographic speed thereof. These additives may be used either singly or in combination with one another to produce the enhanced photographic speeds characteristic of the present invention. In addition, N-vinyl carbazole may be added to increase the contrast (gamma) and maximum density.
It has been found that the speed of compositions of the type described in the above noted patent application, the disclosure of which is intended to be incorporated by reference herein, could be significantly increased by the addition of various kinds of materials in suitable amounts, as will appear from the following formulations each of which is exemplary of the addition of various classes of photocatalysts and/or photosensitizers to compositions of the type described in said application.
The compositions hereinafter described are prepared in the same manner as those described in the above-noted patent application and in Photographic Science and Engineering, Vol. 5, number 2, Mar.-April 1961, pp. 98 et seq.
The compositions are each prepared by bringing the constituents together in a suitable solvent-binder solution under a safelight or in total darkness, each of the constituents usually being added to the solution in the order set forth in the examples, then mixed to effect solution before addition of the next named constituent. After thorough mixing, the composition is applied to a suitable substrate which may be baryta paper or a film of polyester, glass or other support.
After the composition has been laid down as a thin film, it is permitted to dry in air in the dark or under a safelight, drying here meaning the elimination of the solvent(s) from the composition by evaporation. Then the composition is photographically exposed for a time sufficient to produce at least a latent image in the composition.
After this photographic exposure, the latent image in the film is developed by exposing the entire film to radiant energy of an appropriate intensity (e.g.) 50 watt tungsten light source) and suitable wavelength (e.g. between about 600 and 900 μ). The films are then fixed by means of a solvent rinse consisting of 4 parts of petroleum ether and 1 part of acetone.
A composition of the type described in the above noted U.S. Patent is as follows:
100 mg. Leuco Crystal Violet 5 mg. 4 -picoline-N-oxide 1 g. Carbon tetrabromide 4 cc. Polystyrene (10 % solution in benzene)
This composition was coated 0.0015 inch on unsubbed 300 -D Mylar. After photographic exposure, the composition was developed with light filtered through a Corning glass filter No. 2412. The formulation produced D max of 0.62 and base plus fog of 0.20 and a photographic speed of 1.9 × 10 - 3 L.E.S.
EXAMPLE 1
The addition of 6 mg. of Rhodamine B base of the above formulation produced a speed of 0.013 L.E.S., D max of 1.32 and base plus fog 0.36. This illustrates the benefits of adding a dye to such a composition.
EXAMPLE 2
A photographic speed of 0.04 L.E.S. with acceptable base plus fog levels was achieved by the addition of minor amounts of merocyanine dyes with or without xanthene type dyes (Rhodamine B, etc.). In addition, it was found that carbinol compounds of the leuco triphenylmethane derivatives appear to be beneficial and increase the density of the image formed. The following composition produced photographic speeds of 0.04 L.E.S.:
12 mg. Leuco Crystal Violet 5 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] -3 -phenyl- 2 phenylimino- 4 -thiazolidinone, a merocyanine dye 10 mg. Carbinol opal blue 1.4 g. Carbon tetrabromide 4 cc. 10 % Polystyrene in benzene
This composition was coated 0.0015 inch on unsubbed 300 -D Mylar. After photographic exposure, the image was developed with light filtered through a Corning glass filter No. 2030. This composition produced maximum densities as high as 1.7 with a base plus fog of 0.20.
EXAMPLE 3
A photographic speed of 0.1 L.E.S. with acceptable base plus fog levels was achieved by the addition of 5 mg of Crystal Violet carbinol to the formulation represented in Example 2. One composition producing photographic speeds of 0.1 L.E.S. was as follows:
12 mg. Leuco Crystal Violet (stabilized) 5 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] 3 -phenyl- 2 phenylimino- 4 -thiazolidinone, a merocyanine dye 5 mg. Carbinol Crystal Violet (stabilized) 1 mg. Carbinol Opal Blue (stabilized) 1.4 g. Carbon tetrabromide 4 cc. 10 % Polystyrene in benzene
The composition was coated 0.0015 inch on unsubbed 300 -D Mylar. The development light source was filtered through a 2030 Corning glass filter. This composition produced a maximum density of 1.06 with a base plus fog of 0.35.
EXAMPLE 4
The addition of a small quantity of a tertiary amine, such as N-methyldiphenylamine, to the composition of Example 3 produced a further increase in speed. A composition was prepared as in Example 3 and 3 drops of a N-methyldiphenylamine solution containing 1 drop of the amine in 5 cc of acetone were added thereto. The resulting composition was coated 0.0015 inch on unsubbed 300 -D Mylar and after photographic exposure, was developed using light filtered through a Corning glass filter No. 2030. This composition exhibited a photographic speed (L.E.S.) of 0.30, base plus fog of 0.32, D max of 1.09.
EXAMPLE 5
It was further found that the addition of a leuco anthracene further increased the maximum density and speed of the film. The composition of Example 4 was modified by the addition of 2 mg of 2,7 -bis(dimethylamino)- 10 -p-dimethylamino-phenyl- 9,10-dihydro- 9,9-dimethylanthracene to the composition of Example 4. The resulting composition was coated 0.0015 inch on unsubbed 300 -D Mylar, exposed and then optically developed with light filtered through a Corning glass filter No. 2030. This composition exhibited photographic speeds in the range of 0.5 to 0.7 L.E.S., a base plus fog of 0.20, and a D max of 1.4.
EXAMPLE 6
The addition of 5 mg. of N-vinylcarbazole to the formulation of Example 5 increased the maximum density to 2.0 and increased the gamma (slope of H & D plot) of the film.
EXAMPLE 7
A substantial improvement was obtained by the increased amounts of both the leuco anthracene and carbinol of crystal violet and omitting the leuco crystal violet, as shown in the following formula:
5 mg. 2,7 -bis(dimethylamino)- 10 -p-dimethylamino phenyl- 9,10 -dihydro- 9,9 -dimethylanthracene 10 mg. Carbinol Crystal Violet 1 mg. Carbinol Opal Blue 7 mg. 4 -picoline-N-oxide 5 mg. 5 -[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene]- 3 -phenyl- 2 -phenylimino- 4 -thiazolidinone 3 drops Amine solution (1 drop N-methyldiphenylamine in 5 cc. acetone) 1.4 g. Carbon tetrabromide 4.5 cc. 10 percent polystyrene in benzene
This composition produced photographic speeds of 1.0 L.E.S., base fog 0.14, with D max rendition of 1.46.
EXAMPLE 8
Still a further improvement in speed is attained with the following which exhibits an L.E.S. of 2.0 to 4.0, a maximum density of 1.4 and a base plus fog of 0.2:
15 mg. 2,7 -bis(dimethylamino)- 10 -p-dimethylaminophenyl- 9,10 -dihydro- 9,9 -dimethylanthracene 5 mg. 5-[3 -ethyl- 2 (3 H)-benzoxazolylidene-ethylidene] -3 -phenyl- 2 phenylimino- 4 -thiazolidinone 2 mg. 4 -picoline-N-oxide 10 mg. Carbinol of crystal violet (stabilized*) 1.3 mg. Carbinol of opal blue (stabilized*) 6 drops N-methyldiphenylamine solution** 1.4 g. Carbon tetrabromide - 4.5 cc. 10 % polystyrene in benzene
The stabilization of the carbinols and leucos in the above formulations is accomplished by digestion of the carbinols or leucos with an alkali metal hydroxide, as described in U.S. patent application Ser. No. 711,832 filed Mar. 11, 1968, the disclosure of which is incorporated herein by reference.
It will be readily appreciated that in the above formulations, given by way of example, other materials may be used in place of the specific ingredients exemplified in the formulations. For example, other carbinols may be used in place of the carbinols of crystal violet or opal blue, and other organic halogen compounds of the type described in U.S. Pat. No. 3,095,303 and in the U.S. patents listed therein, preferably those in which three halogen atoms are attached to a terminal carbon atom, may be used in place of CBr 4 , iodoform being a particularly preferred replacement for CBr 4 .
A clear distinction must be kept in mind between the "activator" described in U.S. Pat. No. 3,481,739 and the sensitizers described in the present application. An activator assists in the rapid production of color from the color-forming compound whereas a sensitizer extends the range of actinic radiation to which the composition is sensitive.
Each of the compositions described in the preceding examples is utilized by exposing the same to a pattern of radiation and then developing a visible image by a blanket exposure to radiation in a narrow band corresponding to that region to which the composition has been sensitized by the dye formed during the photographic exposure.
In addition, particular note should be made that in Example 8 the amount of N-oxide has been considerably diminished as compared with the amounts utilized in the earlier indicated U.S. patent, this being due in part to the use of a combination of sensitizers as described.
The purpose of the addition of the sensitizing dye such as a merocyanine dye is to increase the absorption of visible light so as to increase the photographic speed.
The purpose of the addition of the polyphenylmethane carbinols is to increase the photographic speed by an increase in the quantum yield of dye, i.e., by an increase in the inherent sensitivity of the system to an absorbed photon of visible light.
The purpose of the addition of the tertiary amine is to reduce formation of dye from the color-former by thermal reactions with atmospheric ingredients or with other ingredients of the film coating.
The amounts of the additives should be as follows for the best results:
Sensitizing dye 2 to 10 mg./4 cc. Carbinol 1 to 10 mg./4 cc. tertiary amine 1 to 10 drops of a 1 % solution (by vol) in acetone/4cc.