JPH07120018B2 - Image receiving element for thermal transfer with improved whiteness - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermal transfer image-receiving element with improved whiteness.

BACKGROUND OF THE INVENTION Photosensitive materials (heat-developable photosensitive materials) for obtaining an image easily and quickly by performing a dry process with heat are known, and the heat-developable photosensitive materials and image forming methods are disclosed in, for example, Japanese Patent Publication No. 43-4921, 43-4924, pages 553 to 555 of Fundamentals of Photographic Engineering (published by Corona Publishing Co. in 1979), and Research Disclosure, June 1978, pages 9 to 15 (RD
-17029) etc.

In recent years, attempts have been made to develop a heat-developable color light-sensitive material capable of forming a color image using various dye-donor substances. Among these, the method of releasing or forming a diffusible dye by heat development and then transferring the dye to obtain a color image is advantageous in terms of stability and vividness of the image and easiness and speed of processing. It is excellent. This transfer type heat-developable color photosensitive material and image forming method are described in, for example, JP-A-59-12431 and 59-59.
-159159, 59-181345, 59-229556, 60-
2950, 61-52643, 61-61158, 61-61157
No. 59-180550, No. 61-132952, No. 62-139842
U.S. Patents 4,595,652, 4,590,154 and 4,584,
No. 267 etc.

When the image obtained by transfer onto the image receiving element is a reflection type, that is, when the image is formed on a white background, the whiteness of the background is a factor that greatly affects the color reproducibility of the image and the image quality. Is one of.

In the case of an image receiving element used for a photothermographic material, improvement in whiteness is also desired.

As a method of improving whiteness as a background, there is a method of using a fluorescent whitening agent. This is an effective method that absorbs ultraviolet light and emits visible light (especially blue light) to increase the reflectance of apparent light, and further adjusts the balance of the reflection spectrum to improve whiteness.

However, when a fluorescent whitening agent is added to the image receiving layer in the image receiving element, its whiteness is lowered after thermal development and thermal transfer. If the addition amount is increased, coagulation occurs to reduce the surface gloss, and further stains which are considered to be caused by the fluorescent whitening agent are generated, which is not preferable.

OBJECTS OF THE INVENTION Accordingly, a first object of the present invention is to provide an image receiving element for thermal transfer having improved whiteness.

A second object of the present invention is to provide a thermal transfer image receiving element having improved whiteness without adversely affecting maximum density photographic properties.

[Constitution of the Invention] An object of the present invention is to use an image-receiving element for a photothermographic material of a transfer system in which an image is obtained by releasing or forming a diffusible dye path by heat development and then transferring the dye by heating. A thermal transfer image-receiving element having at least a white reflective layer and an image-receiving layer, wherein the image-receiving element for thermal transfer contains a whitening layer or an intermediate layer between the white reflective layer and the image-receiving layer.

[Specific Structure of the Invention] In the present invention, a whitening layer in the image receiving element or an intermediate layer between the white reflecting layer and the image receiving layer contains a fluorescent whitening agent. Compared with the case where the agent is contained, the effect of improving whiteness is large, and the decrease in whiteness is small even after thermal development and thermal transfer, which is excellent. This is because the fluorescent whitening agent diffuses from the image receiving layer toward the photothermographic material during thermal transfer, and additives in the photothermographic material and various impurities generated by thermal development are transferred to the image receiving layer. It may be possible that the fluorescent whitening agent has a quenching effect, but it is not clear.

The thermal transfer image-receiving element of the present invention basically comprises a support and an image-receiving layer. The white reflective layer exists between the support and the image receiving layer, but when the support has a white surface, the support can also serve as the white reflective layer.

The fluorescent whitening agent is added to the white reflective layer, the support also serving as the white reflective layer, or the intermediate layer provided between these and the image receiving layer.
The optical brightener is preferably prevented from diffusing into the image receiving layer.

The fluorescent whitening agent used in the present invention is not particularly limited and all known ones can be used.

As the fluorescent whitening agent, diaminostilbene type, distyrylbenzene type, benzidine type, diaminocarbazole type,
Triazole-based, imidazole-based, thiazole-based, triazine-based, imidazolone-based, dihydropyridine-based, coumarin-based, carbostyryl-based, diaminodibenzothiophene dioxide-based, diaminofluorene-based, oxacyanine-based, aminonaphthalimide-based, pyrazoline-based, oxadi There are azole type, acetylene type, etc., for these, U.S. Patent Nos. 2,571,706, 2,581,057, 2,618,
636, 2,702,296, 2,713,054, 2,715,630
No., No. 2,723,197, No. 3,269,840, No. 3,513,102,
Same 3,615,544, same 3,615,547, same 3,684,729, same 3,7
88,854, 3,789,012, British Patents 669,590, 672,
No. 803, No. 712,764, Dutch patent 74,109, German patent 911,368, German publication (OLS) 2,525,680, Japanese Patent Publication No. 34-7127 and "Dye Handbook" (published by Maruzen Co., Ltd.)
Etc.

The preferred fluorescent whitening agent used in the present invention is represented by the following general formula [I].

General formula [I] Where X ₁ and X ₂ are respectively Represents a group or R ₃ —CO— group. Here, R ₁ , R ₂ and R ₃ are respectively a hydroxyl group, a halogen atom (chlorine, bromine, etc.), a morpholino group, an alkoxy group (for example, a methoxy group, an ethoxy group, a methoxyethoxy group, etc.), an aryloxy group ( For example, phenoxy group, p-sulfophenoxy group etc.), alkyl group (eg methyl group, ethyl group etc.), aryl group (eg phenyl group, methoxyphenyl group etc.), amino group, alkylamino group (eg methylamino group, Ethylamino group, propylamino group, dimethylamino group, diethylamino group, cyclohexylamino group, β-hydroxyethylamino group), di (β-hydroxyethyl) amino group, β-sulfoethylamino group,
N- (β-sulfoethyl) -N′-methylamino group, N
-(Β-hydroxyethyl-N'-methylamino group etc.), or an arylamino group (for example, anilino group,
o-, m-, p-sulfoanilino group, 2,5-disulfoanilino group, o-, m-, p-chloroanilino group, o-,
m-, p-toluidino group, o-, m-, p-carboxyanilino group, o-, m-, p-hydroxyanilino group,
Sulfonaphthylamino group, o-, m-, p-aminoanilino group, o-, m-, p-anisidino group and the like).
M represents a hydrogen atom or a cation.

Particularly preferred fluorescent brighteners used in the present invention are those represented by the general formula [I] in which X ₁ and X ₂ are respectively It is shown by.

Specific compound examples are shown in the table below.

In addition to the above compounds, JP-A Nos. 55-166644 and 58-
221845, 59-71049, 59-71050, 59-1111
The diaminostilbene compound shown in No. 47 can also be preferably used.

There is no limitation on the amount of the optical brightener used in the present invention, but usually 0.01 g / m ^{2 to} 0.5 g / m ² , preferably 0.02 g / m ^{2 to} 0.2.
It is 0 g / m ² .

Any method can be used as a method of adding the optical brightener. That is, a method of adding by dissolving in water or an organic solvent, a method of pulverizing and dispersing by a ball mill or a colloid mill, a method of dissolving in a high boiling point solvent and mixing with a hydrophilic colloid solution, and adding as an oil-in-water dispersion And a method in which the polymer latex is impregnated and added.

The support used for the image receiving element of the present invention is preferably one that is not deformed and altered by heat. For example, a transparent support such as a polyethylene terephthalate film, a polycarbonate film, a polyimide film, a glass plate, a paper, a baryta paper, a coated paper, or a white pigment (for example, titanium dioxide, barium sulfate, calcium carbonate, talc) in the support. There is a white support such as one to which is added.

The image receiving element of the present invention has a white reflective layer. The white reflective layer is a layer having a white pigment in a binder (eg, gelatin, gelatin derivative, cellulose derivative, polysaccharides such as gum arabic, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, etc.). Is. The white support can also serve as the white reflective layer and the support.

The image-receiving layer used in the image-receiving element of the present invention may have a function of receiving the dye in the thermo-phenomenon photosensitive layer that is released or formed by a thermo-phenomena, and may be, for example, a tertiary amine or a quaternary ammonium salt. Polymers containing U.S. Pat.
Those described in No. 690 are preferably used. As a typical image-receiving layer for diffusion transfer, an ammonium salt,
It is obtained by mixing a polymer containing a tertiary amine or the like with gelatin, polyvinyl alcohol or the like and coating the mixture on a support. Another useful dye receiving material is JP-A-57-20.
Glass transition temperature of 40 ° C or higher, 250
Those formed of a heat-resistant organic polymer substance having a temperature of not higher than 0 ° C. may be mentioned.

These polymers may be carried on a support as an image receiving layer, or may be used as a support itself.

Examples of the heat-resistant organic polymer substance include polystyrene, polyvinylcyclohexane, polydivinylbenzene, polyvinylpyrrolidone, polyvinylcarbazole,
Polyacetals such as polyallylbenzene, polyvinyl alcohol, polyvinyl formal and polyvinyl butyral, polyvinyl chloride, chlorinated polyethylene, polytrifluoroethylene, polyacrylonitrile, poly-N, N-dimethylallylamide, p-cyanophenyl group , Polyacrylate having pentachlorophenyl group and 2,4-dichlorophenyl group, polyacrylchloroacrylate, polymethylmethacrylate, polyethylmethacrylate, polypropylmethacrylate, polyisopropylmethacrylate, polyisobutylmethacrylate, poly-tert-butylmethacrylate, polycyclohexyl Methacrylate, polyethylene glycol dimethacrylate, poly-2-cyano-ethyl methacrylate, polyethylene terephthale Examples thereof include polyesters such as polyester, polysulfone, polycarbonates such as bisphenol A polycarbonate, polyanhydrides, polyamides, and cellulose acetates. Also, Polymer Handbook Second Edition (edited by Jay Brand Wrap, EH Inmargat) John Willy and Sons {Polymer Handbo
ok 2nd ed. (J, Brandrup, EHImmergut) Joun Wiley
& Sons} synthetic polymers having a glass transition temperature of 40 ° C. or higher are also useful. Generally, 2,000 to 200,000 is useful as the molecular weight of the polymer substance. These polymeric substances may be used alone or as a mixture of two or more kinds, or may be used as a copolymer by combining two or more kinds.

Particularly preferred image-receiving layers include the layer composed of polyvinyl chloride described in JP-A-59-223425 and the layer composed of polycarbonate and a plasticizer described in JP-A-60-19138.

In the image receiving layer of the present invention, JP-A-59-158289 and JP-A-59-1827 are used.
No. 85, No. 60-130735, No. 61-118748, No. 61-153638
No. 61-159644, the ultraviolet absorber and the anti-fading agent may be contained.

In the present invention, an optical brightening agent is added to the white reflective layer, or an intermediate layer is provided between the white reflective layer and the image receiving layer or between the white support and the image receiving layer, and the intermediate layer is provided with the fluorescent whitening agent. Although an agent is added, the intermediate layer in this case basically consists of a binder (same as the above-mentioned binder) and a fluorescent whitening agent, and in addition, it is a surfactant, a hardener, and a fluorescent color enhancer. The mordant, the high boiling point solvent and the like may be added.

In addition, usually a white reflective layer (including the case of also serving as a support)
Alternatively, the effect of the present invention is sufficient if the fluorescent whitening agent is added to any one of the intermediate layers, but it may be added to both the white reflective layer and the intermediate layer.

The image-receiving element of the present invention may be provided with a protective layer.

Various additives used in the field of photography can be used in the protective layer. Examples of the additive include various matting agents, colloidal silica, sliding agents, organic fluoro compounds (particularly fluorine-based surfactants), antistatic agents, ultraviolet absorbers, high boiling organic solvents, antioxidants, hydroquinone derivatives, polymers. Examples thereof include latex, surfactants (including polymer surfactants), hardeners (including polymer hardeners), organic silver salt particles, non-photosensitive silver halide particles, and the like.

These additives are described in Research Disclosure Vol.170, June 1978 No.17029, Japanese Patent Application No. 60-2766.
It is described in JP-A-15.

The layer constitution of the image-receiving element of the present invention is in the order of transparent support-white reflective layer-image-receiving layer, transparent support-white reflective layer-intermediate layer-image-receiving layer-protective layer, white support-image-receiving layer, white support-. Intermediate layer-image receiving layer, white support-image receiving layer-protective layer, white support-
White reflective layer-image receiving layer, white support-white reflective layer-intermediate layer-image receiving layer-protective layer, transparent support-image receiving layer-white reflective layer,
Transparent support-image receiving layer-intermediate layer-white reflective layer, transparent support / image receiving layer-white reflective layer, transparent support / image receiving layer-intermediate layer-
There is a white reflective layer.

The image-receiving element of the present invention comprises a non-peelable monosheet photothermographic material (at least a photosensitive layer, a white reflective layer,
It can also be applied to a photothermographic material having an image receiving layer).

For non-peelable monosheet photothermographic material, see RD-15
108, JP-A-61-80148, "(Title of Invention) Mono-sheet type photothermographic material, (Applicant) Konishi Roku Photo Industry Co., Ltd. (Date of application: October 25, 1986)" Has been done.

The basic layer structure of the non-peelable monosheet photothermographic material is
An undercoat layer, a photosensitive layer (having 1 or 2 or more layers, and may have an intermediate layer in the case of 2 or more layers), a white reflective layer, an image receiving layer, and a protective layer in this order from the support. The fluorescent whitening agent used in the present invention can be added to the white reflective layer or an intermediate layer between the white reflective layer and the image receiving layer.

The image-receiving element of the present invention can be used as an image-receiving element of the above-mentioned transfer type heat-developable color photosensitive material. Alternatively, it can also be used as an image receiving element of a system in which a dye or a dye is transferred to a transfer paper having a pigment or a dye by thermal information from a thermal head or the like to obtain an image on the image receiving element.

[Specific effects of the invention] The image-receiving element for heat transfer of the present invention is epoch-making in that the whiteness is improved and the whiteness is favorably maintained after the heat development transfer, and the maximum density photograph is obtained. It does not adversely affect the characteristics.

[Examples] Specific examples of the present invention are shown below, but the present invention is not limited to these and the embodiments of the present invention.

Example-1 (Preparation of Photothermographic Material) <Preparation of Photosensitive Silver Halide Emulsion> Preparation of Silver Iodobromide Emulsion at 50 ° C., as shown in JP-A-57-92523 and 57-92524. Ossein gelatin 20 using mixed stirring
g, 1,000 ml of distilled water and 500 ml of an aqueous solution containing 11.6 g of potassium iodide and 130 g of potassium bromide in A solution containing dissolved B, and 500 ml of an aqueous solution containing 1 mol of silver nitrate and ammonia. Solution C was added at the same time while keeping pAg and pH constant. Further, by controlling the addition rates of the solutions B and C, a core emulsion having a silver iodide content of 7 mol%, a regular hexahedron and an average grain size of 0.25 μm was prepared. Then, in the same manner as described above, a shell of silver halide having a silver iodide content of 1 mol% was coated to give a regular hexahedron with an average grain size of 0.3 μm.
A core / shell type silver halide emulsion having a shell thickness of 0.05 μm was prepared. (The monodispersity was 8%.) The above emulsion was washed with water and desalted to obtain a yield of 700 ml.

<Preparation of green-sensitive silver halide emulsion> Said silver iodobromide 700 ml 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene 0.4 g Gelatin 32 g Sodium thiosulfate 10 mg Sensitizing dye (a) shown below Methanol 1 wt% liquid 80 ml Distilled water 1200 ml <Preparation of Dye-Donating Substance Dispersion> 44.4 g of the following dye-donating substance, 5.00 g of 2,5-di-t-octylhydroquinone and 2.2 g of the following antifoggant were added to 200 ml of ethyl acetate.
It was dissolved in ml, mixed with 720 ml of 4.24% gelatin aqueous solution containing 124 ml of 5 wt% alkanol XC (manufactured by DuPont) and dispersed with an ultrasonic homogenizer. After distilling off ethyl acetate, water was added to make 795 ml.

[Dye donating substance]

[Antifoggant] <Preparation of Organic Silver Salt and Hot Solvent Dispersion> 5-Methylbenzotriazole silver 72.0 obtained by reacting 5-methylbenzotriazole and ammoniacal silver nitrate under an ultraviolet light source (Neolmi Super Yellow 40W, Mitsubishi Electric) g and hot solvent p-toluamide 138 g and phenylcarbamoylated gelatin (Ruslaw, type 1781)
1,100 ml of a 1 wt% aqueous solution of 9PC) was mixed and dispersed in an alumina ball mill for 24 hours.

<Reducing agent solution> Water was added to 31.8 g of the following reducing agent and 1.0 g of the following surfactant to dissolve them, and the pH was adjusted to 6.0 with an aqueous citric acid solution to obtain 150 ml of a solution.

Reducing agent Surfactant <Preparation of coating solution for heat-developable photosensitive layer> The following additives were mixed to prepare a coating solution.

Dye-donor dispersion 39.75 ml Gelatin solution (10 wt% aqueous solution) 9.75 ml Polyvinylpyrrolidone (K-30) solution (10 wt% aqueous solution) 17.3 ml Reducing agent solution 7.5 ml Organic silver salt and hot solvent dispersion 65.3 ml Green-sensitive halogenation Silver emulsion 12.0 ml Hardener liquid (* 1) 4.9 ml 5-methylbenzotriazole liquid 4.0 ml Preparation water (adjusted to pH 6.0) 1.4 ml (* 1) Tetra (vinylsulfonylmethyl) methane and taurine 1 : 0.75 (molar ratio) reacted and added to a 1% by weight PC gelatin aqueous solution so that the reaction product becomes 3.0% by weight.

The above coating solution was applied onto a 180 μm thick transparent polyethylene terephthalate film for photography having an undercoat layer to obtain a wet film thickness of 8
After coating at 3.3 μm and drying, aging was performed for 14 hours in an atmosphere of 40 ° C. and 80% PH.

(Preparation of Image-Receiving Element-1) A coating solution for an intermediate layer containing a fluorescent whitening agent was applied on a photographic baryter paper in a wet film thickness of 45.7 μm and dried.

<Intermediate layer coating solution> Fluorescent whitening agent FB-1 of the present invention FB-1 0.48 g Vinylpyrrolidone-vinyl acetate (7: 3) copolymer (weight average molecular weight 220,000) 0.88 g Water 400 ml Furthermore, the following image receiving layer coating solution The wet film thickness 137.2
It was applied in a thickness of μm and dried.

<Image-receiving layer coating solution> Polycarbonate pellets (L-1250, Teijin Chemicals) 21g UV absorber (* 2) 0.8g Browning inhibitor (* 3) 0.8g Ethylene chloride 190ml (Preparation of Image Receiving Element-2) In Image Receiving Element-1, the fluorescent whitening agent FB from the intermediate layer coating solution
What removed -1 was prepared.

(Preparation of Image Receiving Layer-3) In the image receiving layer-2, the fluorescent whitening agent FB-1 was added to the image receiving layer coating liquid.
Was added (the coating amount of FB-1 per m ² is the same as that of the image receiving element-1). However, in that case, a solution of a small amount of polycarbonate dissolved in ethylene chloride and the fluorescent whitening agent powder are mixed, and then they are mixed with an alumina ball mill.
After dispersing for 16 hours, the remaining polycarbonate, UV absorber and browning inhibitor were added.

Through the step wedge through the photothermographic material,
A tungsten light exposure of 0 CMS was applied, and the image-receiving elements-1, 2, and 3 were superposed on the coated surfaces respectively, and preheated at 100 ° C. for 4 seconds, and then pressure-bonded at 150 ° C. for 60 seconds. The preheating and pressure heating are disclosed in JP-A-61-153651.
No. 2 of the publication No. 2 was used.

A sample having a magenta image on the surface of the image-receiving element when the photothermographic material and the image-receiving element were quickly peeled off after heating.
1,2,3 were obtained.

<Evaluation of Photographic Properties> The maximum reflection density and the minimum reflection density of the obtained magenta image are measured with a Sakura densitometer PDA-65 (manufactured by Konishi Roku) with green light. The results are shown in Table 1 below.

Sample-3, in which the optical brightener was added to the image receiving layer, was not preferable because the maximum density was lowered.

<Evaluation of Relative Fluorescence Intensity> Color analyzer (6
The reflection density was measured in the range of 380 nm to 780 nm using 07 type, manufactured by Hitachi, Ltd.). Next, install a colored glass filter (UV-39, Toshiba Electric Co., Ltd.) on the light source of this analyzer,
The reflection density of each sample was measured through the filter. The difference in reflection density between the case where the light source has a filter and the case where there is no filter was measured, and the difference in reflection density at the maximum fluorescence wavelength of the fluorescent whitening agent was defined as the fluorescence intensity. Fluorescence intensity of unused image receiving element-1
The relative fluorescence intensity when 100 is shown in Table 2 below.

<Evaluation of brownish whiteness> For the minimum density portion of the sample after thermal transfer, the visual whiteness was evaluated in the standard light source device (CIE D65 standard light source F65D-A type, Suga Test Instruments Co., Ltd.). It was As a result, Sample-2 appeared light brown, Sample-3 appeared light pink, and Sample-1 of the present invention appeared white.

Example-2 Instead of the optical brightener FB-1 of Example-1, an equal amount of FB-1 was used.
3, the sample shown in Table 3 below was prepared using FB-19, and the same operations and evaluations as in Example-1 were carried out, and the sample of the present invention containing the optical brightener in the intermediate layer was The whiteness was superior to that contained in the image receiving layer.

Example 3 The following white reflective layer and image receiving layer were coated on a 180 μm thick transparent polyethylene terephthalate film having an undercoat layer and dried.

(White reflective layer) Titanium dioxide (RN-43, Ishihara Sangyo Co., Ltd.) 22g / m² Gelatin 2.7g / m² Carboxymethyl cellulose 0.2g / m² Sodium dodecyl sulfate 0.08g / m² (Image-receiving layer) Polycarbonate 13g / m² UV absorber (the same as in Example-1) 0.65 g / m² Browning inhibitor (the same as in Example-1) 0.65 g / m  Fluorescent brightener FB-1 in white reflective layer 0.07g / m²Added
(Sample-8), 0.07g / m in the image receiving layer Added (Sample-
9) made.

Hereinafter, the same operation as in Example-1 was performed to obtain a sample.
The maximum and minimum reflection densities of 8, 9 and the relative fluorescence intensities in the unused condition and after thermal transfer are shown in Table 4 below.

It can be seen that the one having the whitening layer added with the fluorescent whitening agent exhibits excellent whiteness after the thermal transfer, as compared with the one having the fluorescent whitening agent added to the image receiving layer.

Example-4 Example-4 except that FB-4, FB-12, FB-13, FB-17, and FB-20 were used in place of the fluorescent whitening agent FB-1 of Sample-8 in Example-3. Perform the same operation as in 3 to prepare samples-10,11,1.
Made 2,13,14. Then, when the same heat development and thermal transfer as in Example-1 were performed, all showed excellent whiteness almost equal to that of Sample-1.

Claims (1)

[Claims] 1. An image receiving element used in a photothermographic material of a transfer system, wherein an image is formed by releasing or forming a diffusible dye by heat development and then transferring the dye by heating, which is at least white reflection. An image receiving element for heat development transfer, comprising a layer and an image receiving layer, wherein the image receiving element for heat development transfer comprises a whitening layer or an intermediate layer between the white reflecting layer and the image receiving layer.