JPH08286345A - Photosensitized sheet of instant film - Google Patents

Abstract

PURPOSE: To retain shading capability and whiteness even if usual resin-coating paper is used, and be capable of disposing of a photosensitized sheet by breaking or folding up. CONSTITUTION: Two layer co-extruded film 35 comprising a white PE layer 36 and a black PE layer 37 is stuck on the one surface of resin coating paper 31 so that the white PE layer 36 comes in contact with the resin coating paper 31. A photosensitive emulsion layer 38 is formed on the other surface of the resin coating paper 31. The resin coating paper 31 is constituted with a base paper layer 32 and PE layers 33, 34 formed on both surfaces of the base paper layer 32. The PE layer 33 on which the photosensitive emulsion layer 38 is formed is made white by including 10-15wt.% titanium oxide, and the PE layer on the opposite side is made transparent. The co-extruded film 35 is formed in an inflation method so that the thickness of the white PE layer 36 is 10-30μm, the content of titanium oxide is 40-65wt.%, the thickness of the black PE layer 37 is 10-30μm, and the content of carbon is 15-35wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peel apart type instant film photosensitive sheet, and more particularly to a layer structure of a photosensitive sheet for high sensitivity.

[0002]

2. Description of the Related Art FIG. 3 shows the construction of a monochrome peel-apart type instant film unit (hereinafter, simply referred to as a film unit). The drawing sheet 2 is joined to the front end side of the photosensitive sheet 1, and the short skirt 3 for receiving the excess developing solution is joined to the rear end side thereof. The drawer sheet 2 and the skirt 3
In order to eliminate surface reflection, black carbon mixed paper or white paper coated with black ink is used. Further, a developer pod 4 containing a developer is provided on the rear end side of the pull-out sheet 2 beside the photosensitive sheet 1.
And a funnel 5 for guiding the developer flowing out from the developer pod 4 toward the photosensitive sheet 1, and a joint portion 6a of the tab 6 is joined to the tip end side thereof.

The image receiving sheet 7 is for recording a final photographic image and is bonded to the lower surface of the mask 8. The mask 8 is formed with an opening 8a corresponding to the screen size, and its tip is joined to the drawer sheet 2. Band-shaped rails 9 and 10 made of relatively thick paper are adhered to both sides of the opening 8a. Two plate-like projections 11 and 12 are joined to the rear ends of the rails 9 and 10 in order to secure a space for containing the excess developer.

A plurality of film units are housed in a film pack, and the film pack is loaded into the camera. After the exposure of the photosensitive sheet 1, the pull-out sheet 2 is pulled out together with the tabs 6 by pulling out the tabs 6 coming out of the film pack by hand. At this time, the mask 8 moves toward the exit of the film pack while gradually overlapping with the pull-out sheet 2 from the tip side thereof. When the photosensitive sheet 1 is pulled out by the pull-out sheet 2,
The image is inverted and overlapped on the image receiving sheet 7. Since a pair of developing rollers are arranged near the exit of the film pack, the developing pod 4 is cleaved when passing between them, and the jelly-like developing solution flows out. This developer is
The liquid is spread by a developing roller with a uniform liquid thickness between the photosensitive sheet 1 and the image receiving sheet 7 which are sequentially superposed from the leading end side. This developing solution transfers a negative image recorded as a latent image on the photosensitive sheet 1 to the image receiving sheet 7 as a positive image.
When the image receiving sheet 7 is peeled off after the time required for this transfer has elapsed, an instant photograph having a positive photographic image recorded thereon can be obtained.

Currently, in monochrome film units,
High sensitivity, for example, ISO 3000 is required. To obtain such a highly sensitive film unit,
In addition to the improvement of the light-sensitive emulsion, it is necessary to make effective use of light. For that purpose, it is preferable that the light which has passed through the light-sensitive emulsion layer is returned to the light-sensitive emulsion layer and further exposed to light. Therefore, as shown in FIG. 4, the support 20 is made of white PET (polyethylene terephthalate) containing about 15% by weight of titanium oxide, and the photosensitive emulsion layer 21 is formed on one side of the support 20 and the other side is formed on the other side. The photosensitive sheet 1 having the back layer 22 layered on its surface is used. Such white P
In the case of the photosensitive sheet 1 using ET, since the support 20 has a high reflectance, there is an advantage that the light transmitted through the photosensitive emulsion layer 21 can be effectively used, and it is advantageous for high sensitivity.

[0006]

However, when the white PET is used as the support 20, even if the photosensitive sheet 1 is torn or folded after being photographed for disposal, it cannot be easily torn and can be folded. There is a drawback that you cannot do it.

Further, when the photosensitive sheet 1 is burnt as waste, the thermal power of PET tends to be strong and shunned. Therefore, as disclosed in Japanese Patent Laid-Open No. 28858/1990, a paper using a paper as a support for the photosensitive sheet has been proposed. In this case, as shown in FIG.
PE with gray base paper layer 23 containing carbon and titanium oxide
A support 26 having a three-layer structure sandwiched between (polyethylene) layers 24 and 25 is used. Then, a photosensitive emulsion layer 27 is coated on the upper PE layer 24, and a back layer 28 for light shielding is coated on the lower PE layer 25.

However, in this case, since the base paper layer 23 contains carbon in order to improve the light-shielding property,
Due to the influence of the gray base paper layer 23, the reflectance of the PE layer 24 becomes low, and there is a drawback that it is not suitable for use in a highly sensitive photosensitive sheet. When it is desired to reduce the carbon addition rate of the base paper layer 23 to prevent a decrease in reflectance, the base paper layer 2
There is a problem that the shading ability of No. 3 is lowered. Furthermore, when the carbon content is reduced and the thickness of the base paper layer 23 is increased by that amount, the thickness of the photosensitive sheet increases, and it becomes impossible to load a specified number of film units in a film pack having a predetermined thickness. There's a problem.

To return the light to the photosensitive emulsion layer 27, the reflectance of the PE layer may be further increased. For that purpose, the PE layer 2
The amount of titanium oxide added to 4 may be increased.
However, if the amount of titanium oxide added is increased, film cracking occurs during PE extrusion, so the T-die method has a titanium oxide content of about 17% by weight.
% By weight. Therefore, there is a limit to increase the reflectance of the upper PE layer 24.

The present invention is intended to solve the above-mentioned problems, and an instant which is capable of improving the reflectance of the support and securing the light-shielding property without increasing the thickness of the film unit. The purpose is to manufacture a photosensitive sheet of a film at a low cost.

[0011]

In order to achieve the above object, an instant film photosensitive sheet according to a first aspect of the present invention comprises a resin-coated paper having one surface and two layers of a white layer and a black layer. The co-extrusion film is attached with its white layer side as the bonding surface, and a photosensitive emulsion layer is formed on the other surface of this resin-coated paper. The resin-coated paper preferably has a thickness of 55 to 125 μm, is composed of a base paper layer and PE layers formed on both sides of the base paper layer, and the PE layer on the side where the photosensitive emulsion layer is formed is titanium oxide. Is used, and the PE layer on the opposite side is transparent. Such resin-coated paper is most widely used as a base member for printing paper and the like, and by using it, a low-cost photosensitive sheet can be obtained.

The white layer of the coextrusion film contains 40 to 65% by weight of titanium oxide and has a thickness of 10 to 30 μm.
The black layer preferably contains 15 to 35% by weight of carbon and has a thickness of 10 to 30 μm. When a PE film is produced by the conventional T-die method, the pigment concentration is limited to 17% by weight for titanium oxide and 7% by weight for carbon. . Therefore, as a result of repeated experiments by the inventor to produce a film having a high pigment concentration by various film forming processing methods, in the case of a coextrusion film produced by the inflation method, about 60% by weight of titanium oxide and about 32% of carbon are used. It has been found that high pigment concentrations of wt% can be obtained. By using the film produced by this inflation method, a thin film film having an increased content of titanium oxide or carbon can be easily obtained.

[0013]

The two-layer coextrusion film consisting of the white layer and the black layer is attached to one surface of the resin-coated paper with the white layer side as the joining surface. The white layer increases the whiteness of the resin-coated paper and improves the reflectance. In addition, the black layer ensures a sufficient light-shielding property. Therefore, carbon can be removed from the base paper layer of the resin coated paper, and the reflectance of the surface of the resin coated paper coated with the photosensitive emulsion layer can be improved. Further, the thickness of the base paper layer can be made smaller than that of the conventional one, and the film unit can be made thinner.

[0014]

1 shows a photosensitive sheet 30 of the present invention. As the support, an ordinary resin-coated paper 31 using white plain base paper to which carbon is not added is used. This resin coated paper 3
1 comprises a plain base paper layer 32 having a thickness of 70 μm, a white PE layer 33 layered on the surface of the plain base paper layer 32, and a transparent PE layer 34 layered on the back side of the plain base paper layer 32. . The white PE layer 33 has a thickness of 20 μm, 12% by weight of titanium oxide is added, and is formed in white.
The transparent PE layer 34 is transparent and has a thickness of 15 μm.

Transparent PE of resin coated paper 31
Two layers of coextrusion film 35 are attached to the layer 34 side. The coextrusion film 35 is formed into a film by a well-known inflation method. Coextrusion film 3
5 is composed of a white PE layer 36 and a black PE layer 37. The white PE layer 36 has a thickness of 10 μm, contains 60% by weight of titanium oxide, and has improved whiteness. Also,
The black PE layer 37 has a thickness of 20 μm, contains 16% by weight of carbon, and is formed in black.

The resin-coated paper 31 and the coextrusion film 35 are attached to each other by a known method such as thermocompression bonding or an adhesive layer. After that, a well-known photosensitive emulsion layer 38 is formed on the white PE layer 33 of the resin coated paper 30.
Are layered.

In the above embodiment, the resin coated paper 31 is 105 μm, and the coextrusion film 35 is used.
Was 30 μm, but the thickness of each layer of the paper 31 and the film 35 and the content rates of titanium oxide and carbon are not limited thereto. For example, the resin coated paper 31 has a thickness of 55 to 125 μm, and the coextrusion film 35 has a white PE layer 36 of 10 to 30 μm and a black PE.
The layer 37 has a thickness of 10 to 30 μm, and the white PE layer 3
Content of titanium oxide of 6 is 40 to 65% by weight, black PE
By setting the carbon content of the layer 37 to 15 to 35% by weight, the whiteness can be improved and the light-shielding property can be secured without increasing the thickness of the entire film unit. Also,
The transparent PE layer 34 may be a white layer containing titanium oxide instead of the transparent PE layer.

In the above embodiment, the coextrusion film 35 is composed of the PE layer 36 containing titanium oxide and the PE layer 37 containing carbon, but polypropylene may be used instead of PE. Further, as the pigment contained in each of these layers, zinc oxide, magnesium carbonate, barium sulfate, calcium carbonate or the like may be used in addition to titanium oxide in order to increase the whiteness. Further, in the case of improving the light-shielding property, a black pigment such as ferric tetroxide may be used in addition to carbon.

By changing the thickness of each of the layers 36 and 37 and the content of the pigment and the like depending on the resin coating paper 31 used, it is possible to obtain desired whiteness and light-shielding properties according to various thicknesses. For example, when the thickness of the resin-coated paper 31 is reduced, the white PE layer 36 of the coextrusion film 35 is increased in content of titanium oxide, or the white PE layer 36 is increased in thickness to improve the whiteness. With increasing the temperature, the content of carbon in the black PE layer 37 of the coextrusion film 35 is increased, and the thickness of the black PE layer 37 is increased to enhance the light shielding property.

In the above embodiment, the coextrusion film 3 is used.
Although 5 has a two-layer structure, it may have a structure of three or more layers. For example, the black PE layer 3 containing the above carbon
As shown in FIG. 2, PE layers 37a and 37b may be used instead of 7 as shown in FIG. The same components as those in the embodiment shown in FIG. 1 are designated by the same reference numerals. In this case, using a well-known multi-layer inflation film molding device, white PE
By the layer 36 and the two black PE layers 37a and 37b,
A film is formed on a coextrusion film 39 having a three-layer structure of white, black and black. Further, the white PE layer 36 is not limited to one layer and may have a structure of two or more layers.

[0021]

According to the present invention, a two-layer coextrusion film consisting of a white layer and a black layer is laminated on one surface of a resin-coated paper with the white layer side as the bonding surface, so that the base paper layer is formed. A high-sensitivity instant film photosensitive sheet can be prepared using a general carbon-free resin-coated paper. That is, conventionally, the base paper layer was made to contain carbon to enhance the light-shielding property, but by providing the black layer, the light-shielding property can be enhanced by the black layer, so that a normal resin-coated paper can be used. . Moreover, since the white layer is provided between the black layer and the base paper layer, the influence of the black layer on the whiteness of the base paper layer can be reduced as compared with the case where the black layer is directly joined to the base paper layer. The whiteness and reflectance of the layer can be increased. This makes it possible to form a highly sensitive photosensitive sheet using resin-coated paper. Therefore, it is possible to improve the disposal suitability as compared with the case where the white PET is used as in the conventional case, and the photosensitive sheet can be broken or folded and disposed of, and also incinerated as a normal combustible waste. It will be possible.

The thickness is 55 to 125 μm,
It is composed of a base paper layer and PE layers formed on both sides of the base paper layer. The PE layer on the side where the photosensitive emulsion layer is formed contains 10 to 15% by weight of titanium oxide, and the PE layer on the opposite side is transparent. Since the resin-coated paper is used, a general resin-coated paper can be used as the support of the photosensitive sheet, and thus the suitability for disposal can be improved and the manufacturing can be performed at a low cost. Further, a white layer of the coextrusion film was formed to a thickness of 10 to 30 μm by containing 40 to 65% by weight of titanium oxide, and a black layer and a carbon layer
.About.35% by weight and formed to a thickness of 10 to 30 .mu.m, the desired whiteness and reflectance and the degree of light shielding can be obtained within a predetermined thickness range even if a resin coated paper with a reduced carbon content is used. You will be able to get it. Therefore, a highly sensitive film unit can be configured without reducing the number of film units stored in the film pack.

Further, since the coextrusion film is a PE film made by the inflation method, the content of titanium oxide or carbon can be increased more than that of the conventional one, and the film unit can be made thinner.

[Brief description of drawings]

FIG. 1 is a sectional view showing a photosensitive sheet of an instant film embodying the present invention.

FIG. 2 is a sectional view showing a photosensitive sheet according to another embodiment.

FIG. 3 is a perspective view showing an outline of a monochrome film unit.

FIG. 4 is a sectional view showing an example of a conventional photosensitive sheet.

FIG. 5 is a cross-sectional view showing an example of another conventional photosensitive sheet.

[Explanation of symbols]

 30 resin coated paper 31 plain base paper layer 32 white PE layer 33 transparent PE layer 35 coextrusion film 36 white PE layer 37, 37a, 37b black PE layer

Claims (4)

[Claims] 1. A two-layer coextrusion film consisting of a white layer and a black layer is attached to one surface of a resin-coated paper with the white layer side as a joint surface, and the other surface of the resin-coated paper is exposed to light. An instant film photosensitive sheet having an emulsion layer. 2. The instant film photosensitive sheet according to claim 1, wherein the resin-coated paper has a thickness of 55 to 125 μm, and comprises a base paper layer and polyethylene layers formed on both sides of the base paper layer. An instant film photosensitive sheet, wherein the polyethylene layer on the side where the emulsion layer is formed contains 10 to 15% by weight of titanium oxide. 3. The instant film photosensitive sheet according to claim 1, wherein the white layer of the co-extruded film contains 40 to 65% by weight of titanium oxide and has a thickness of 10 to 30 μm.
and a black layer containing 15 to 35% by weight of carbon and having a thickness of 10 to 30 μm, an instant film photosensitive sheet. 4. The instant film photosensitive sheet according to claim 3, wherein the co-extrusion film is an inflation method polyethylene film.