Polyester film with anthroquinone dye for a photographic film support

Abstract

A polyethylene terephthalate film for an X-ray photographic film support colored blue by one or more anthraquinone dyes represented by the general formula ##SPC1## Wherein X represents a hydrogen atom; an alkyl group having 1-15 carbon atoms; a cycloalkyl group; an aryl group; an aryl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom; an aralkyl group; or an aralkyl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polyester film to be used as a support in a light-sensitive photographic film, and more particularly, to a polyester film for a photographic film support colored blue by an anthraquinone dye.

2. Description of the Prior Art

Light-sensitive photographic films having a colored support are known. It is desirable that in light-sensitive photographic materials, particularly in X-ray photographic films, the film support be colored blue to facilitate the discrimination of photographic images. The photographic image formed on an X-ray photographic film prepared by coating an X-ray photographic emulsion on a colorless support film has a soft, poor black tone, and hence it is not easy to clearly see the images formed thereon. This means that when the spectral absorption of the developed silver of the X-ray film is measured, the absorption in the short wave length region is large.

Accordingly, to correct this fault, the support film is typically colored using a blue dye having absorption in the long wave length region. That is to say, the image of an X-ray photographic film having a support film colored with a blue dye has a sharp or clear black tone, and can be easily distinguished.

Further, when a support film colored using a dye having absorption in the short wave length region is used as the support for an X-ray photographic film of the type where a photographic emulsion such as a gelatino silver iodobromide emulsion is coated on both surfaces thereof, a filter desensitization action occurs at X-raying.

For the above purposes, the dyes used for coloring a polyester film for an X-ray photographic film support are required to satisfy various requirements, i.e., to have good heat resistance, sublimation resistance, miscibility with the support film and to have a proper color hue (less yellow component). Further, they must be inactive to the gelatino silver halide emulsion to such an extent that they do not have any harmful influence on the photographic properties thereof, such as sensitivity, gamma, fog, etc.

As described in U.S. Pat. Nos. 2,071,250 and 2,905,707, colored polyester films can be prepared by conducting the polycondensation of the components forming the polyester after adding a dye to at least one component prior to the polycondensation, or by mixing a powdery, chip-like or pellet-like polyester with a dye in any proper manner, extruding the mixture into a colored molten sheet by melt extrusion to form a substantially amorphous non-oriented film, biaxially stretching the sheet to about 2.5 times its original dimensions, and heat-treating to provide a film having dimensional stability. Such a method as described above in which the molten material is colored before it is formed into a sheet or film is excellent as compared to other methods in the point that a uniformly colored polyester film is obtained.

Since the industrial production of polyester films is conducted by a melt extruding method with heating, the coloring dye used is required to have good heat resistance, i.e., it should be capable of enduring temperatures of 270.degree.C to 320.degree.C. A polyester film has a stable physical structure and hence it is not easy to color the film by dyeing. Therefore, it is preferred, as mentioned above, to employ the method in which the coloring matter is dispersed or dissolved in the polyester by adding it during the synthesis of the polymer or at melting the polymer during heating for molding or fabrication. Therefore, the coloring dye used is required to have a high heat stability so as to endure molding temperatures of 270.degree.C to 320.degree.C and not decompose and fade. The above-mentioned method of coloring a polyester before it is formed into a sheet or film also has the advantage that it does not need an additional coloring step because the coloring is conducted in the molding step.

Polyester is formed into film through the steps of drying, melting by heating, extruding, stretching and heat-treating. Among those steps, the drying step is preferably conducted under reduced pressure at temperatures of 135.degree.C to 210.degree.C (as described in the specification of Japanese patent publication No. 618/1953). If a drying step is not employed in the case of forming a polyester film, hydrolysis occurs upon melting the polyester by heating, which results in making the formation of a film impossible or producing a film having poor properties, e.g., low strength.

On the other hand, a polyester film is usually produced using a tenter system, and hence edge loss is inevitable. For reuse of the cut-off edges of the polyester film, they are collected, pulverized, and dried with fresh polyester chips. When the polyester film has been colored with a dye having poor sublimation resistance, the dye used for the coloring sublimates from the cut-off edges during drying. Consequently, not only is dye lost by sublimation, but the dye thus sublimated stains the dryer, and further the sublimed dye is deposited on the inside wall of the dryer and falls down therefrom to cause uneven coloring.

Furthermore, when extruding polyethylene terephthalate from an extrusion die onto a die casting drum for cooling, the die is apt to sublimate.

Also, when polyester is colored with a prior art coloring matter or dye as described above, the coloring matter or dye sublimates at extruding to stain the casting drum to give an uneven dye density in the colored film. Therefore, it is necessary to color polyesters using coloring matter or a dye which has good sublimation resistance.

When coloring a molten polyester, it is necessary that the coloring dye be easily and uniformly dispersed or dissolved in the polyester and, in particular when the colored polyester is used as a support for a photographic film, the polyester is required to provide a film having high transparency and a surface free of optical defects. Therefore, turbidity cannot be formed in the support film caused by insufficient dispersion of the coloring matter or foreign matter present in the support film.

As is well known, in order to obtain a polyester film having useful properties it is necessary that an amorphous, non-oriented polyester film prepared by melting and extruding be subjected to stretching and a heat treatment under proper temperature conditions, and even if coloring matter has been uniformly dispersed without reducing the transparency of the film in the amorphous and non-oriented film, it sometimes happens that spaces are formed between the fine dispersed particles of the dye or coloring matter which do not undergo plastic deformation when the polyester itself undergoes plastic deformation in the subsequent stretching step, which results in increasing light scattering to causes turbidity or clouding of the film.

Therefore, in the case of producing a film support for photographic films, care must be taken so that the coloring matter is dispersed in the polyester as very fine particles or is dissolved in the polyester as a molecular dispersion to prevent the formation of spaces which increase the scattering of light in the film in the stretching step.

Typical of the processes use to produce polyester films in accordance with the present invention are those described in U.S. Pat. No. 3,488,195 Hunter and the references described therein. This reference discloses various extrusion, biaxial orientation and like procedural steps, especially at column 2, which can be used with the film of the present invention. See especially U.S. Pat. No. 2,779,684 Alles and U.S. Pat. No. 2,823,421 Scarlett, cited in this patent.

SUMMARY OF THE INVENTION

One object of this invention is thus to provide a coloring matter or a dye for coloring a polyester for use as the support of a photographic material satisfying the heretofore described severe conditions regarding photographic properties, heat resistance, sublimation resistance and color hue.

That is to say, according to this invention there is provided a polyester film for use as a support of a photographic film comprising a substantially homogeneous mixture of a polyester and a 1,4-diarylaminoanthraquinone dye.

In greater detail, the inventors discovered that the coloring matter or dye represented by general formula I satisfies the above-described requirements necessary for photographic films, in particular, X-ray photographic films: ##SPC2##

wherein X represents a hydrogen atom; an alkyl group having 1-15 carbons atoms, a cycloalkyl group; an aryl group; an aryl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom; an aralkyl group or an aralkyl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom.

Most highly preferred of the cycloalkyl groups are those having 5 or 6 carbon atoms, and of the aryl or aralkyl groups most highly preferred are those which are monoaryl and, for aralkyl, where the alkyl moiety has 1 or 2 carbon atoms. Within the classes cycloalkyl, aryl or monoaryl, this narrow class offers superior results.

The dye used in this invention is stable even if it is heated for several hours at temperatures above 270.degree.C and further is not decomposed even if the dye is heated while dispersed in a molten polyester for more than 3 hours in the absence of air.

Also, it has been confirmed that the dye in this invention has a particularly high sublimation resistance and that the uneven dyeing occurring in the case of using ordinary dyes does not occur under polymerization reaction condition (see U.S. Pat. No. 2,823,421 to Scarlett) in which the polycondensation is conducted under high vacuum after dispersing the dye in the components forming the polyester or during the step of dispersing the dye in a molten polyester at a high temperature under a high vacuum.

Still further, the dye of this invention is readily-soluble in ordinary organic solvents such as petroleum saturated hydrocarbons, aromatic hydrocarbons, aliphatic or aromatic halogenated hydrocarbons, ethers, ketones and esters, and hence the dye is suitable for producing an excellent colored support for photographic films by using an ordinary colored subbing layer as described in Japanese Pat. No. 13826/1968 on a transparent synthetic high molecular weight film.

Specific examples of such solvents are benzene, toluene, chloroform, methylene chloride, ethyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetate and butyl acetate.

DETAILED DESCRIPTION OF THE INVENTION

The polyester used in this invention includes not only those consisting of only repeating units of ethylene terephthalate but also those containing up to about 2% of another component or components in addition to the repeating units of ethylene terephthalate. As such other components there can be illustrated isophthalic acid, phthalic acid, adipic acid, diethylene glycol, triethylene glycol, propylene glycol, cyclohexane dimethanol, and HO--CH.sub.2 --OH, where n is 3 or 8.

Specific examples of the dyes used in this invention are given below, but the invention is not to be limited thereto.

Compound 1: 1,4-bis(2',6'-dimethyl-4'-hydroxyanilino)-anthraquinone,

Compound 2: 1,4-bis(2',6'-dimethyl-4'-methoxyanilino)-anthraquinone,

Compound 3: 1,4-bis(2',6'-dimethyl-4'-n-decyloxyanilino)-anthraquinone,

Compound 4: 1,4-bis(2',6'-dimethyl-4'-bezyloxyanilino)-anthraquinone,

Compound 5: 1,4-bis[2',6'-dimethyl-4'-(p-methyl)benzyloxyanilino]anthraquinone,

Compound 6: 1,4-bis[2',6'-dimethyl-4'-(o-methyl)benzyloxyanilino]anthraquinone,

Compound 7: 1,4-bis[2',6'-dimethyl-4'-(o-chloro)benzyloxyanilino]anthraquinone,

Compound 8: 1,4-bis(2',6'-dimethyl-4'-phenethyloxyanilino)-anthraquinone,

Compound 9: 1,4-bis(2',6'-dimethyl-4'-phenoxyanilino)-anthraquinone,

Compound 10: 1,4-bis[2' ,6'-dimethyl-4'-(p-tert-octyl)-phenoxyanilino]anthraquinone,

Compound 11: 1,4-bis[2' ,6'-dimethyl-4'-(p-carboxy)-phenoxyanilino]anthraquinone,

Compound 12: 1,4-bis(2' ,6'-dimethyl-4'-cyclohexyloxyanilino)-anthraquinone.

The dye, or a combination of the dyes of this invention, gives an excellent color to a support for photographic films when it (or they) is used in an amount of about 0.01 to about 0.5 g per kilogram of the polyester chips. As one strays further and further outside this preferred range, the excellent results obtainable begin to decrease in effect. Accordingly, it is best to be within the range 0.01 to 0.5 g per kilogram recited.

Most preferred polyester materials as are used in the present invention have an intrinsic viscosity of about 0.55 to about 0.70, determined in a mixture of phenol and tetrachloroethane (1:1 by weight) at 25.degree.C. While it will be obvious to one skilled in the art that this is not a limitative range, polyester materials meeting this criterion are very suitable for use in forming photographic film supports.

When the aminoanthraquinone dyes of the present invention are used in dispersed form in the polyester, best results in forming a photographic film support are obtained when the size thereof is less than the wave length of visible light, most preferably, when the diameter of any vacant spaces formed between the polyester matrix and the particles of the dyes or coloring material is less than one tenth the wave length of visible light (less than about 125 angstroms). Such a product illustrates amazingly low haze, and while this parameter is not limitative, since final product qualities will vary depending on the user, such a product is highly preferred.

Many aminoanthraquinone dyes capable of giving a blue tone when used for coloring molten polyester are known as described in, e.g., British Pat. Nos. 1,137,595 and 1,196,707, but dyes satisfying the three factors of heat stability, sublimation resistance and color hue in the case of coloring molten polyesters and in the steps of stretching and heat treatment of the polyester film are scarcely found among such known dyes. In particular, a preferred blue dye used for coloring the support of an X-ray photographic film is one having low absorption in the yellow region in the spectral absorption spectra of the colored film. A dye having high absorption in the yellow region is undesirable since the film support colored by such a dye shows a yellowish blue-green hue and loses its purity. From such view points, there are significant restrictions on the selection of prior art dyes giving a desired color.

As 1,4-diaminoanthraquinone dyes among the aminoanthraquinone dyes useful for a support for a photographic film, the following dyes are described in, e.g., U.S. Pat. No. 3,488,195, Japanese patent publication No. 15187/1970, British Pat. No. 1,137,595 and Belgian Pat. No. 700,302;

Compound A: 1,4-bis(2',6' -diethylanilino)anthraquinone

Compound B: 1,4-bis(2',6' -trimethylanilino)anthraquinone and the following dyes are described in British Pat. No. 1,196,707 and Belgian Pat. No. 715,614.

Compound C: 1,4-(2',6' -triethylanilino)anthraquinone,

Compound D: 1,4-bis(2',3' ,5' ,6' -tetramethylanilino)anthraquinone,

Compound E: 1,4-bis(2',3' ,4' ,5' ,6' -pentamethylanilino)anthraquinone.

As is clear from the results of sublimation resistance comparison tests made using typical examples of the dyes of this invention and the aforesaid known dyes, the 1,4-diarylaminoanthraquinone dyes used in this invention are superior to known 1,4-bis(alkyl-substituted anilino)anthraquinone dyes as shown above, and hence the dyes of this invention do not cause uneven coloring in the coloring of molten polyesters.

The sublimation resistance of the dyes was tested in the following manner: 2 mg of the dye was placed in the bottom of a hard glass test tube having an inside diameter of 18 mm and a length of 200 mm, and then 10 g of polyethylene terephthalate chips (4 mm .times. 4 mm .times. 2.5 mm) was placed on the dye. Several of such test tubes, each containing a different dye, were prepared, connected to vacuum pipe lines and evacuated for 5 minutes under a pressure of 0.1 mm.

Then, while connected to the vaccum pipe lines, the test tubes were immersed in an oil bath heated to 180.degree.C .+-. 2.degree.C to 2/3 the whole length of the tubes, and after continuing the evacuation and heating for 4 hours, the test tubes were withdrawn.

In all cases, it was observed that the dye had migrated up the stack of polythylene terepthalate chips placed on the dye, with a dye density distribution from the bottom of the polyethylene terephthalate in contact with the dye to the top of the polyethylene terepthalate chips. This was due to the sublimation of the dye and absorption of the dye by the polythlene terepthalate The more the dye had moved up the layer of polyethylene terepthalate chip the greater the degree of sublimation. The results are shown in the following table, which shows the dyes of this invention are excellent in sublimation resistance.

Comparison of Sublimation Resistances of Dyes ______________________________________ Tested dyes Sublimation resistance (distance the sublimated dye moved) ______________________________________ Dye of this invention Compound 1 4 mm Compound 3 5 mm Compound 4 6 mm Compound 6 5 mm Compound 8 4 mm Comparison dye Compound A 50 mm Compound B 48 mm Compound C 40 mm Compound D 43 mm ______________________________________

Synthesis examples of typical dyes used in this invention are described below:

SYNTHESIS EXAMPLE 1

Synthesis of 1,4-bis(2',6' -dimethyl-4'-hydroxyanilino)anthraquinone (Compound 1):

A mixture of 9.0 g of 1,4,9,10-tetrahydroxyanthracene, 4.2 g of 2,6-dimethyl-4-hydroxyaniline, 4.2 g of boric acid, and 40 ml of n-butanol was refuxed at normal pressure for 25 hours in an oil bath at 100.degree.-115.degree.C. The reaction product was cooled to room temperature and after adding thereto 3 ml of 6 N hydrochloric acid followed by stirring, the solid product was collected by filtration, washed with water and dried. The crude product was purified by means of column chromatography using silica gel (Merck Kieselgel-60) and recrystallized from chloroform-methanol (1:1 volume) to provide compound 1 as blue-violet crystals. The amount of the crystals was 6.8 g and their melting point was above 320.degree.C.

Visible absorption spectrum: .lambda..sub.max.sup.acetone : 375 nm, 543 nm (sh), 586 nm, and 631 nm.

Elementary analysis: Found: C; 75.15%, H; 5.56%, N; 5.85%. Calculated as C.sub.30 H.sub.26 O.sub.4 N.sub.2 : C; 75.29%, H; 5.48%, N; 5.85%.

From the results of the above analyses and the results of measurements of the nuclear magnetic resonance absorption spectra and mass spectra, it was confirmed that the compound prepared in this synthesis example was 1,4-bis(3',6' -dimethyl-4'-hydroxyanilino)anthraquinone.

SYNTHESIS EXAMPLE 2

Synthesis of 1,4-bis(2',6' -dimethyl-4'-n-decyloxyanilino)anthraquinone (Compound 3):

1. Synthesis of 2,6-dimethyl-4-n-decyloxyaniline:

After dissolving 6 g of metallic sodium in 300 ml of absolute ethanol, 40 g of 2,6-dimethyl-4-hydroxyaniline was added to the solution. Then, while refluxing the solution at normal pressure while heating, 55 g of decyl bromide was added dropwise to the solution over a period of 30 minutes and the mixture was heated at the boiling point of the solvent at normal pressure for 2 hours. After removing ethanol by distillation at normal pressure, the residue was dissolved in ethyl ether. The solution was washed with a 0.1 N aqueous sodium hydroxide solution and then water and dried over Glauber's salt. After distilling away ether, the residue was distilled at 162.degree.-163.degree.C at 0.5 mm Hg and a liquid having a boiling point of 162.degree.-163.degree.C/0.5 mm Hg was obtained.

(2) Synthesis of 1,4-bis(2',6' -dimethyl-4'-n-decyloxyanilino)anthraquinone:

A mixture of 4.8 g of 1,4,9,10-tetrahydroxyanthracene, 9.5 g of 2,6-dimethyl-4-n-decyloxyaniline and 4.0 g of boric acid was refluxed for 48 hours at normal pressure in an oil bath at 140.degree.-160.degree.C under a nitrogen gas blanket. The reaction product was cooled and dissolved in 100 ml of chloroform. The solution was washed with 6 N hydrochloric acid and then the chloroform layer thus formed was washed with water until it became neutral, dried over Glauber's salt, and concentrated by reduced pressure disillation. By recrystallizing the residue from ethanol, 6.5 of the compound was obtained as blue-violet crystals. The melting point was 100.degree.-101.degree.C.

Visible absorption spectrum: .lambda..sub.max.sup.acetone : 544 nm(sh), 584 nm and 628 nm.

Elementary analysis: Found: C; 79.21%, H; 8.85%, N; 3.77%. Calculated as C.sub.50 H.sub.66 O.sub.4 N.sub.2 : C; 79.11%, H; 8.76%, N; 3.69%.

From the above results, it was confirmed that the compound prepared in this synthesis example was 1,4-bis(2',6' -dimethyl-4'-n-decyloxyanilino)anthraquinone.

SYNTHESIS EXAMPLE 3

1,4-bis(2',6' -dimethyl-4'-benzyloxyanilino)anthraquinone (Compound 4):

(1) Synthesis of 2,6-dimethyl-4-benzyloxyaniline:

40 g of 2,6-dimethyl-4-hydroxyaniline was added to a solution of 6 g of metallic sodium in 250 ml of anhydrous ethanol and after dropwise adding 32 g of benzyl chloride to the solution during 1 hour at refluxing temperature, the mixture was further heated under reflux for 2 hours. The reaction mixture above obtained was worked up similar to this method described in Example 2 - (1), and the residue was distilled to give a fraction having a boiling point of 145.degree.C/0.5 mm Hg. The product was allowed to stand and solidified. The melting point thereof was 71.degree. - 72.degree.C.

2,6-Dimethyl-4-benzyloxyaniline was also produced by the following method.

A mixture of 51 g of the 2,6-dimethyl-4-hydroxy-4'-sulfoazobenzene (Compound 2) prepared according to the method described in Example 1, 13.3 g of sodium hydroxide, 250 ml of ethanol, and 250 ml of water was heated to 45.degree. - 50.degree.C, and, while stirring the homogeneous solution thus prepared, 32 g of benzyl chloride was added to the solution. The resulting mixture was reluxed for 1.5 hours, whereby a solid precipitated. After distilling away ethanol under reduced pressure, the precipitate was collected by filtration, washed with water and dried to give 54.5 g of the sodium salt of 2,6-dimethyl-4-benzyloxy-4'-sulfoazobenzene.

The product was added to 2000 ml of water containing 60 g of sodium hydroxide and after heating the mixture to 40.degree.-50.degree.C, 200 g of sodium hydrosulfite was added. After heating at 80.degree. - 90.degree.C for a further 2 hours, the reaction mixture was cooled and extracted twice with 300 ml of ethyl ether. The ether layer separated was washed with water, dried over anhydrous sodium sulfate, and ether was evaporated.

By recrystallizing the residue from benzene-petroleum ether (1:2 by weight), 25 g of the desired product was obtained as acicular crystals having a melting point of 73.degree.-74.degree.C.

Elementary analysis: C; 79.19, H; 7.55, N; 5.99% (calculated for C.sub.15 H.sub.17 NO: C; 79.26, H; 7.54, N; 6.16%).

(2) Synthesis of 1,4-bis(2',6' -dimethyl-4'-benzyloxy-anilino) anthraquinone:

A mixture of 2.4 g of 1,4,9,10-tetrahydroxyanthracene, 9.0 g of 2,6-dimethyl-4-benxyloxyaniline and 2.0 g of boric acid was heated at 160.degree.C for 16 hours and the reaction mixture thus obtained was treated in the same manner as described in Example 2. Then, by purifying the crude dye obtained by column chromatography using SiO.sub.2 and recrystallizing it from ethanol, 3.7 g of Compound 4 was obtained as blue-violet acicular crystals. The melting point of the dye was 193.degree.-194.degree.C.

Visible absorption spectra: .lambda..sub.max.sup.acetone : 544 nm (sh), 582 nm, and 626 nm.

Elementary analysis: C; 80.45%, H; 5.71%, N; 4.11% (calculated for C.sub.44 H.sub.38 O.sub.4 N.sub.2 : C; 80.22%, H; 5.81%, N; 4.25%).

Infrared absorption spectra: .nu. : 1580 cm.sup..sup.- 1, 1491cm.sup.-.sup.1, 1256 cm.sup.-.sup.1, 1158 cm.sup.-.sup.1.

Nuclear magnetic resonance spectra (in deutero-chloroform) (.delta.,ppm):

2.17 (singlet) Ar--CH.sub.3 5.02 (singlet) --OCH.sub.2 Ar 6.55 (singlet) anthraquinone nucleus H 6.73 (singlet) aniline nucleus Ar--H 7.38 (singlet) benzyl nucleus Ar--H 7.71 (multiplet) anthraquinone nucleus H 8.41 (multiplet) anthraquinone nucleus H 11.69 (broad singlet) NH

From the above results, the compound obtained in this example was confirmed to be 1,4-bis(2',6' -dimethyl-4'-benzyloxyanilino)anthraquinone.

SYNTHESIS EXAMPLE 4

1,4-bis(2',6' -dimethyl-4'-phenethyloxyanilino)anthraquinone (Compound 8):

(1) Synthesis of 2,6-dimethyl-4-phenethloxyaniline:

The same procedure as in Example 3-(1) was conducted using 46 g of phenethyl bromide in place of benzyl chloride and the reaction mixture was then treated by an ordinary method as in Example 2. By recrystallizing the crude product thus obtained from benzene, 2,6-dimethyl-4-phenethyloxyaniline having a melting point of 60.degree.-61.degree.C was obtained.

(2) Synthesis of 1,4-bis(2',6' -dimethyl-4'-phenethyloxyanilino)anthraquinone:

The same procedure as described in Example 3-(2) was followed using 9.6 g of 2,6-dimethyl-4-phenethyloxyaniline in place of 2,6-dimethyl-4-benzyloxyaniline, and the reaction mixture obtained was subjected to a similar treatment to the method as in Example 2-(2). The crude product obtained was purified by column chromatography using SiO.sub.2 and recrystallized from ethanol to give 4.9 g of anthraquinone dye as blue-violet crystals. The melting point of the compound was 136.0.degree.-137.0.degree.C.

Visible absorption spectra: .lambda..sub.max.sup.acetone : 544 nm (sh), 582 nm, 626 nm.

Elementary analysis of the compound: C, 80.73%, H, 6.15%, N, 4.13% (calculated for C.sub.46 H.sub.42 O.sub.4 N.sub.2 : C, 80.44%, H, 6.16%, N, 4.08%).

Infrared absorption spectra: .lambda. : 1580 cm.sup.-.sup.1, 1495 cm.sup.-.sup.1, 1264 cm.sup.-.sup.1, 1160 cm.sup.-.sup.1.

Nuclear magnetic responance spectra (in deutero-chloroform solution) (.delta., ppm): ##EQU1##

From the above results, the compound obtained in this example was confirmed to be 1,4-bis(2' ,6'-dimethyl-4'-phenethyloxyanilino)anthraquinone.

The following examples are intended to illustrate the present invention but not to limit it in any way. In all examples, unless otherwise indicated, polyethylene terephalate having an intrinic viscosity of [.eta.] = 0.67 was employed.

EXAMPLE 1

The dye (Compound 4 ) prepared in Synthesis example 3-(2) was mixed with polyethylene terephthalate chips (the chips had a size of 4 mm .times. 4 mm .times. 2.5 mm; chips of this size were used in all examples where chips were used, unless otherwise indicated) and the mixture was kneaded and formed into a film by melt extrusion at 290.degree.C so that the film prepared contained 0.025 weight % dye. The film was then stretched to give a blue film having a thickness of 0.180 mm. The stretching conditions were: first step, 3.5 times at 85.degree.C; second step, 3.5 times at 100.degree.C. No reduction in transparency and no formation of clouds or turbidity due to nondispersed particles was observed in the film. The casting drum was also not stained by the dye during the formation of the film.

Both surfaces of the film were irradiated with ultraviolet rays for 1 minute at 80.degree.C in air by means of a 1 KW quartz mercury lamp as described in Japanese patent publication No. 2603/1968, and then a gelatin dispersion having the following composition was coated on the surfaces and dried for 2 minutes at 120.degree.C to give a gelatin dispersion layer about 6 microns thick.

______________________________________ Gelatin 1 part by weight Acetic acid 1 " Methanol 20 " Acetone 60 " Methylene chloride 10 " Trichloroethane 5 " Phenol 5 " ______________________________________

A gelatino silver iodobromide emulsion for X-ray photographic film containing 100 g of silver iodobromide, 30 g of gelatin and 1 mol% of silver bromide was coated on the subbing layers to give a medical X-ray photographic film. The emulsion layer thickness was 6 microns. The image obtained by X-raying through a human body using the medical X-ray film and developing it could be easily distinguished as a clear image, and the photographic properties such as sensitivity, gamma and fog were not affected.

When the X-ray photographic film was stored under severe temperature and humidity conditions, no change was observed in the color of the support of the photographic film before and after the development.

EXAMPLE 2

Both surfaces of a polyethylene terephthalate film having a thickness of 180 microns were irradiated with ultraviolet rays for 1 minute at 80.degree.C. in air using a 1 KW quartz mercury lamp as described in Japanese patent publication No. 2603/1968, and thereafter a gelatin dispersion having the following composition was immediately applied to the surfaces and dried for 2 minutes at 120.degree.C.

______________________________________ Gelatin 1 part by weight Water 1 " Salicylic acid 0.3 " Methanol 20 " Acetone 60 " Benzyl alcohol 3 " Methylene chloride 14 " o-Chlorophenyl 3 " 1,4-Bis(2',6'-dimethyl-4'- phenethyloxyanilino)- anthraquinone (compound 8) 0.2 " ______________________________________

a gelatino silver iodobromide X-ray photographic emulsion containing 100 g of silver iodide, 60 g of gelatin and 3 mol% of bromine was coated on the surfaces of the colored subbing layers which had been applied to both surfaces of the polyethylene terephthalate film to yield a medical X-ray film. The thickness of the emulsion layer was 7 microns. No harmful influence was observed on the photographic characteristics of the X-ray photograph obtained by X-raying through a human body using the X-ray film. Also, no stains were observed on the developing machine or in the developer used.

On the other hand an X-ray film was prepared in the same way using a comparison dye, 1,4-bis(2' ,4' ,6'-trimethylanilino)-anthraquinone (Compound B) in place of the dye of the invention in the composition of the subbing layer, and the film developed in an automatic developing machine. In this case the developer was colored blue.

EXAMPLE 3

A mixture of 7 parts by weight of the dye (Compound 8) prepared in Synthesis Example 4 and 3 parts of 1,4-bis[2' ,4' ,6'-trimethyl-3'-(cyelohexylamido)sulfoanilino]anthraquinone was mixed [The chips and dye were blended in the dry state and melt extruded 290.degree.C.] with polyethylene terephthalate chips so that the film prepared from the mixture contained 0.025% dyes and then an oriented polyethylene terephthalate film colored blue-violet and having a thickness of 0.180 mm was prepared as in Example 1.

The film thus obtained had high transparency and a slightly reddish blue-violet color as compared with the film obtained in Example 1. No stains on the casting drum were observed at the formation of the film.

Both surfaces of the film thus prepared were irradiated with ultraviolet rays in the manner described in Example 1 and coated with a subbing layer coating composition having the same composition as in Example 1, followed by drying. Then, a gelatino silver iodobromide emulsion for an X-ray photographic film containing 100 g of silver iodobromide, 60 g of gelatin, and 3 mol% of silver iodide was coated thereon to give a medical X-ray film. The silver image obtained by X-raying a human body using the X-ray film could easily be distinguished as a clear image, and the photographic characteristics such as sensitivity, gamma and fog did not change as compared with those of a control film.

EXAMPLE 4

A mixture of 9.5 parts of the dye (Compound 3) prepared in Synthesis Example 2 and 0.5 part of 4,8-dihydroxy-1,5-bis(2' ,4' ,6'-trimethylanilino)anthraquinone was mixed with polyethylene terephthalate chips so that the film prepared from the mixture contained 0.020% dyes, and an oriented film colored blue-violet of a thickness of 0.180 mm was prepared by the same casting method as in Example 1.

The film thus obtained had uniformly dispersed dyes therein and high transparency. Then, a medical X-ray film was prepared by forming subbing layers on both surfaces of the film and then applying to the subbing layers the gelatino silver iodobromide emulsion for X-ray film used in Example 1 in the same manner as in Example 1.

By ordinary exposure and development, the medical X-ray film gave an image which could quite easily be distinguished as a clear image, and the photographic characteristics were almost the same as those of a control film.

Also, the color of the support film did not change when the photographic film was stored for a long period of time or when the photographic film was developed.

EXAMPLE 5

A mixture of 8.7 parts of [1,4-bis(2' ,6'-dimethyl-4'-benzyloxyanilino)anthraquinone] (Compound 4) and 1.3 parts of 1-p-phenethloxyanilino-4-hydroxyanthraquinone was mixed with polyethylene terephthalate chips as in Example 1 so that the film prepared from the mixture contained 0.020% dyes, and an oriented film, which was colored blue and had a thickness of 0.180 mm was prepared from the mixture as in Example 1.

The colored film thus obtained had the same properties as those of the film obtained in Example 4.

EXAMPLE 6

A colored polyethylene terephthalate film was prepared using a mixture of 8.8 parts of [1,4-bis(2' ,6'-dimethyl-4'-benzyloxyanilino)anthraquinone] (Compound 4) and 1.2 parts of 1-p-benzyloxyanilino-4-hydroxyanthraquinone according to the procedure of Example 5. The colored film thus obtained had the same properties as those of the film prepared in Example 4.

EXAMPLE 7

A colored film was prepared using a mixture of 5.5 parts of 1,4-bis(2' ,6'-dimethyl-4'-phenethyloxyanilino)anthraquinone (Compound 8) and 4.5 parts of 1,4-bis[2' ,6'-dimethyl-4'-(o-methyl)benzyloxyanilino]anthraquinone (Compound 6) according to the procedure of Example 5. The colored film thus obtained had properties the same as those of the film prepared in Example 4.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims

What we claim is:

1. A photographic film having a support comprising a polyethylene terephthalate film containing at least one compound represented by the formula: ##SPC3##

wherein X represents a hydrogen atom; an alkyl group having 1-15 carbon atoms; a cycloalkyl group; an aryl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom; an aralkyl group; or an aralkyl group substituted by an alkyl group having 1-10 carbon atoms, a carboxyl group, or a halogen atom, the size of said compound being less than the wave length of visible light and said compound having been mixed with said polyethylene terephthalate under melting condition and a silver halide light-sensitive emulsion layer coated on said support.

2. A support as claimed in claim 1 wherein the cycloalkyl group has 5 or 6 carbon atoms, the aryl group is monaryl and the aralkyl group is monoaryl wherein the alkyl moiety has one or two carbon atoms.

3. A support as claimed in claim 1 wherein from about 0.01 to about 0.5 g of the at least one compound represented by the general formula is present per kilogram of the polyethylene terephthalate film.

4. A support as claimed in claim 3 wherein the polyethylene terephthalate has an intrinsic viscosity of from about 0.55 to about 0.70, determined in a 1:1 by weight mixture of phenol and tetrachloroethane at 25.degree.C.