JPS5935798B2 - heat sensitive recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material having a heat insulating layer, and more particularly to a heat-sensitive recording material that is less prone to fogging.

Thermal recording materials do not need to be handled in a dark room or under safe light as do silver halide photographic materials, and are generally similar to silver halide photographic materials, such that the image forming process provides a directly visible image, for example by application of a thermal pattern. Many thermal recording materials and methods have been proposed as being faster and easier than photosensitive materials and therefore suitable for a wide variety of practical purposes.

For example, Japanese Patent Publication No. 44-9718 proposes increasing the swelling degree and dissolution rate in water of the recording portion of a thermal recording layer containing gelatin as the main ingredient. Further, Japanese Patent Publication No. 46-27919 describes a method of selectively removing heated portions of a heat-sensitive layer by washing or rubbing with a liquid that selectively permeates the heated portions. On the other hand, Japanese Patent Publication No. 44-22957 discloses that a light-absorbing substance that converts absorbed light into heat and hydrophobic thermoplastic polymer particles dispersed in a hydrophilic binder at a ratio of more than 1:1 are disclosed. A method is described in which a heat-sensitive layer containing the photosensitive layer is exposed to light to obtain an image based on differences in hydrophilicity, water permeability, and water solubility. These recording materials can be subjected to contact exposure using a xenon lamp, halogen lamp, tungsten lamp, or the like as a light source.

However, when performing close exposure using the light source as described above,
With materials that become insolubilized in heated areas, heat conduction from the image area of the original image causes the temperature to rise even in the non-exposed areas of the recording material, and the heat-sensitive layer remains in the non-image areas even after development, causing fog. be.

Conversely, heat conduction occurs from the heated portion to the non-image portion of the original, and a large amount of energy may be required for insolubilization. For materials where the heated part becomes solubilized,
Similarly, fog may occur due to insufficient temperature rise in the exposed area,
The temperature of the non-exposed area increases and the solubility increases, and a sufficient image may not be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-sensitive recording material that prevents heat conduction from the original image and is less likely to cause capri.

Other objects of the invention will become apparent from the following description of the specification.

The above-mentioned object of the present invention is to provide a heat-sensitive recording material having a heat-sensitive layer on a support whose solubility or swellability in a developing solution changes when heated by light exposure. This is achieved by a heat-sensitive recording material characterized by having a heat insulating layer.

Here, the heat insulating layer refers to a layer that prevents heat conduction from the original image, and preferably uses a material with low thermal conductivity, such as resin, and further has a hollow structure. More preferably, the original image is partially held by the material forming the heat insulating layer at the contact surface between the heat insulating layer and the original image, and other parts are in contact with gas. The heat insulating layer of the present invention can be applied to any heat-sensitive recording material having a heat-sensitive layer on a support.

That is, the heat-sensitive recording material according to the present invention basically has a heat-sensitive layer provided on a support, and the heat-insulating layer of the present invention is provided as the uppermost layer. As the support, a dimensionally stable plate-like material can be suitably used.

Supports used in the present invention include paper, paper laminated with plastics (e.g. polyethylene, polypropylene, polyethylene, etc.), aluminum, zinc,
Metal plates such as copper, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate/butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene,
Examples include plastic films such as polycarbonate and polyvinyl acetal.

Among these supports, polyethylene terephthalate,
Paper laminated with polyethylene or aluminum plate is preferred. The support is surface-treated if necessary.

For example, the aluminum plate is preferably subjected to surface treatment such as graining treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, or the like, or anodization treatment. In the case of a support having a plastic surface, the surface is preferably subjected to a surface treatment such as chemical treatment, discharge embedding, flame treatment, ultraviolet treatment, high frequency glow discharge treatment, or activated plasma treatment.

Further, an intermediate layer made of gelatin, casein, polyvinyl alcohol, ethyl cellulose, phenolic resin, diazoresin, styrene-maleic anhydride copolymer, polyacrylic acid, etc. may be optionally provided between the support and the heat-sensitive layer. It can be provided for the purpose of improving the adhesiveness of the heat-sensitive layer or preventing pinholes.

Furthermore, if necessary, an intermediate layer made of the gelatin or the like may be provided between the heat insulating layer and the heat sensitive layer of the present invention. As the heat-sensitive layer provided on the support, any layer whose solubility or swelling property in a developer can be changed by heating with photoelectric light can be used.

Preferred are heat-sensitive recording materials having a heat-sensitive layer using gelatin (Japanese Patent Publication No. 44-9718), heat-sensitive recording materials having a heat-sensitive layer containing a novolac-type phenol resin and carbon black (Japanese Patent Application No. 144-337-1977). etc. These are useful as positive heat-sensitive recording materials that become soluble when heated. Also, heat-sensitive recording materials containing thermoplastic polymer particles in a hydrophilic binder (Japanese Patent Publication No. 44-229
No. 57), heat-sensitive recording materials using resol-type phenolic resins (Japanese Patent Application No. 144338/1983), and the like are useful as negative-tone heat-sensitive recording materials that become insoluble when heated.
Particularly preferred is a heat-sensitive recording material having a heat-sensitive layer containing an ionomer resin (Japanese Patent Application No. 55-53739).
It is.

That is, a preferred example in this case is that the ionomer resin is a copolymer of α-olefin (especially ethylene) and α/β monounsaturated carboxylic acid (especially acrylic acid or methacrylic acid), and metal ions (especially Na+, Mg+゛, Zn++) is an ionically cross-linked resin,
In addition, this heat-sensitive layer uses a water-soluble polymer compound (
Polyvinyl alcohol is preferred, especially 85-90%
(preferably those containing vinyl alcohol units), and furthermore, the ratio of the ionomer resin to the water-soluble polymer compound is 2:3 to 9:1 by weight. The heat-sensitive recording material used in the present invention basically has a heat-sensitive layer as described above on a support, but a heat-sensitive intermediate layer may be provided between the heat-sensitive layer and the support. . Specifically, Special Public Interest Publication No. 45-39239
There are some that are listed in the publication. It is desirable to use an ionomer resin for such an intermediate layer as well. The heat insulating layer of the present invention, which is provided as the uppermost layer of the heat-sensitive recording material, can be provided by any method.

For example, when the heat insulating layer is formed by coating, the heat insulating layer forming coating solution applied to the surface of the heat sensitive layer can be easily removed during development without substantially having any adverse physical or chemical effects on the heat sensitive layer. Any material may be used as long as it is compatible with the developer and does not react with the developer used. The heat insulating layer of the present invention may be removed at least above the non-image area of the heat sensitive layer by a developer during development.

According to a preferred embodiment of the invention, the heat insulating layer is mechanically matted or a resin layer containing a matting agent.

Matting agents include silicon dioxide, zinc oxide, titanium oxide,
Includes zirconium oxide, glass particles, alumina, starch, polymer particles (e.g. particles of polymethyl methacrylate, polystyrene, phenolic resins, etc.) and matting agents as described in U.S. Pat. It will be done. Two or more of these can be used in combination. The resin used in the heat insulating layer of the present invention, which can contain a matting agent, is appropriately selected depending on the combination with the developing solution (heat-sensitive layer removing solution) used. Specifically, for example, gum arabic, glue, gelatin,
Casein, celluloses (e.g., viscose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc.), starches (e.g., soluble starch, modified starch, etc.), polyvinyl alcohol, polyethylene oxide, Examples include acrylic acid, polyacrylamide, polyvinyl methyl ether, polyvinylpyrroli, polyamide, epoxy resin, phenolic resin, and polyvinyl butyral. These can also be used in combination of two or more types. Methods for mechanically mattifying the surface of the heat insulating layer include (1) applying the heat insulating layer so as to obtain a coating layer with an uneven pattern; and (2) mechanically matting the surface of the heat insulating layer after applying the heat insulating layer. There is a method of obtaining a coating layer having a concavo-convex pattern.

As a specific example of (1), the heat insulating layer can be obtained by applying the heat insulating layer with a roller having unevenness.

On the other hand, as a specific example of (2), after providing a heat insulating layer,
There is a method in which fine particles having a hardness higher than that of the heat insulating layer are coated on a sheet having a smooth surface such as paper, cloth, or plastic film, and a matrix is used, which is then pressed with a pressure roller to form a mat. In the heat-sensitive recording material of the present invention, the thickness of the heat insulating layer is preferably 3 to 30 microns.

If the heat insulating layer is thinner than 3μ, the heat insulating effect is not sufficient. Also 30. “If it is thicker, the adhesion to the original image will be incomplete and a clear image will not be obtained.It may also have a negative effect on developability.When using a matting agent, the diameter of the particles of the matting agent is 3~30μ due to the above-mentioned inconvenience.
It is appropriate that the thickness be in the range of 4 to 20 μm, and particularly preferably in the range of 4 to 20 μm.

In order to incorporate such a matting agent into the heat-insulating layer, the matting agent is dispersed in a solution of a suitable solvent containing the resin to be dispersed therein, and this is applied to the surface of the heat-sensitive recording material. Common.

The above-mentioned solvent is selected from those that are poor solvents for the matting agent and do not substantially dissolve the surface of the heat-sensitive recording material. Such a solvent can be easily selected once the uppermost layer of the heat-sensitive recording material before coating the heat-insulating layer, the presence or absence and type of matting agent in the heat-insulating layer, and the type of resin are determined. When contact exposure is performed on the heat-sensitive recording material according to the present invention, no special measures are required due to the provision of the heat insulating layer.

The heat-sensitive recording material according to the present invention can be subjected to contact exposure using a xenon lamp, halogen lamp, tungsten lamp, etc. as a light source, but preferably the luminescence time is about 1
/100 seconds or less and a flash light source with high light intensity in the infrared region is preferred.

The present invention has industrial advantages such as being able to obtain a high-resolution lithographic film at low cost and also being able to obtain a lithographic master. In the present invention, directly on the surface of the heat-sensitive layer,
Alternatively, by providing a heat insulating layer as the uppermost layer via an intermediate layer or the like, it is possible to prevent heat conduction from the original image and obtain a heat-sensitive recording material that is less prone to fogging.

In addition, when the heat-insulating layer of the present invention is provided, the heat-sensitive layer will not be damaged even when heat-sensitive recording materials are stacked.
Further, it is possible to obtain the effect that adjacent heat-sensitive recording materials do not come into close contact with each other and cause difficulty in handling.

Furthermore, when the surface of this heat-insulating layer is roughened, when the original image is brought into close contact with the heat-sensitive recording material, suction is uniformly performed, and the original image can be completely brought into close contact with the entire surface of the heat-sensitive recording material in a short time. Next, the details of the present invention will be explained in more detail with reference to Examples, but these are not intended to limit the present invention in any way.

Example 1 A composition according to the above weight ratio was dispersed for 30 minutes using glass beads, and then spread onto a polyethylene terephthalate (PEL) film having a thickness of 100μ with a gelatin undercoat layer using a wire bar to give a weight after drying of about 40/D7Fl'. I applied it to make it look like this.

This heat-sensitive recording material was dried at 50°C or lower. On top of this
As a heat insulating layer, the following composition has a dry weight of 51119/
It was applied so that it became Dd.

This heat-sensitive recording material was dried at 50° C. or lower to prepare a sample of the present invention. A negative original was superimposed on this sample of the present invention, and a xenon flash light source (manufactured by Riso Kagaku Kogyo Co., Ltd., RISO) was used.
TORAPENUPFX-120), 0.9J/
The document side was exposed to Cd energy.

Next, the above-mentioned sample of the present invention was immersed in water and the heat-sensitive layer was rubbed with a sponge to dissolve and remove the unexposed areas, and a clear black positive image was obtained. It was confirmed that the provision of the heat insulating layer had no effect on the image. On the other hand, when a comparative sample without such a heat insulating layer was exposed and developed in the same manner, fog remained in spots in areas that should be dissolved and removed during development.

Example 2 The composition according to the above weight ratio was dispersed for 3 minutes using an ultrasonic dispersion machine, and then dried using a wire bar on a polyethylene terephthalate (PET) film having a thickness of 100μ and having a gelatin undercoat layer so that the weight after drying was about 10~/Dd. It was applied and dried at below 50°C.

On top of this, the following composition was dispersed as a heat-sensitive layer using glass beads for 60 minutes, and after drying with a wire bar, the weight was approximately 40 r! It was applied at a rate of 1 g/di.

A composition similar to that of Example 1 was applied thereon as a heat insulating layer using a wire bar so that the film thickness after drying was about 5W9/Dm', and dried at 50° C. or lower to obtain a sample of the present invention.

Next, this sample was exposed to light and developed in the same manner as in Example 1, and a clear positive print was obtained.

It was confirmed that the provision of the heat insulating layer had no effect on the image. Example 3 A composition having the above weight ratio was dispersed for 10 minutes using glass beads, and a polyethylene terephthalate (P) having a thickness of 75μ was dispersed.
ET) Apply onto the film using a wire bar so that the weight after drying is 60η/di, dry in a dryer at 90°C for about 5 minutes, and then heat dry in a dryer at 50°C for 1 day. A sample was prepared.

A heat insulating layer was provided on this sample in the same manner as in Example 1 to obtain a sample of the present invention.

Next, the sample of the present invention was exposed in the same manner as in Example 1,
When immersed in a 20 times diluted solution of SDP-1 (sodium silicate aqueous solution, manufactured by Konishiroku Photo Industry Co., Ltd.) for 30 seconds and rubbing the heat-sensitive layer with a sponge, the exposed areas are dissolved and removed, leaving a clear black color. A negative image was obtained.

It was confirmed that the provision of the heat insulating layer had no effect on the image. Example 4 A thermosensitive layer similar to Example 1 was provided on a polyethylene terephthalate (PET) film with a gelatin subbing layer.

A heat insulating layer having a thickness of 20 .mu.m was formed by applying the following composition as a heat insulating layer using a textured roller so that the film thickness after drying was 5 to 1/d.

Next, this sample was exposed and developed in the same manner as in Example 1, and a clear positive image was obtained.

Example 5 A thermosensitive layer similar to Example 1 was provided on a polyethylene terephthalate (PET) film with a gelatin subbing layer.

On top of this, as a heat insulating layer, the following composition was applied with a dry weight of 10
WII! /d and dried to prepare a sample.

The thickness of the heat insulating layer at this time was about 50μ. Next, this sample was exposed and developed in the same manner as in Example 1.

When the halftone dot area of this sample was measured using Area Dac 1000 (manufactured by Konishiroku Photo Industry Co., Ltd.), it was found that where the halftone dot area was small, the halftone dot area was significantly smaller than that of the original, and where the halftone dot area was large, the halftone dot area of the original was It was observed that the dot area of

Claims (1)

[Scope of Claims] 1. In a heat-sensitive recording material having a heat-sensitive layer on a support whose solubility or swelling property in a developing solution changes when heated by light exposure, the uppermost layer has a heat-sensitive layer that is removed by the developing solution. A heat-sensitive recording material characterized by having a heat insulating layer. 2. The heat-sensitive recording material according to claim 1, wherein the heat insulating layer has a rough surface. 3. The heat-sensitive recording material according to claim 1 or 2, wherein the heat insulating layer contains a matting agent. 4. The heat-sensitive recording material according to claim 1, 2, or 3, characterized in that the heat insulating layer is formed by applying it with an uneven roller. 5. The heat-sensitive recording material according to claim 1, 2, 3, or 4, wherein the heat insulating layer has a thickness of 3 to 30 μm.