JP2653894B2 - Thermal recording material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-sensitive recording material, and more particularly to a diazo-based heat-sensitive recording material that can be fixed.

(Prior Art) A technique using microcapsules for a diazo-based heat-sensitive recording material is known. Even in the heat-sensitive recording material obtained by this microencapsulation method, the preservability before heat recording and the heat response during high-speed recording were not sufficient. The present inventors have solved the above problem by adding amides to the recording layer in the recording material, and have applied for a patent. However, the image stability after thermal recording is not sufficiently satisfactory, and further improvement has been desired.

(Object of the Invention) Accordingly, an object of the present invention is to provide a heat-sensitive recording material having excellent raw storability, fast thermal response and good image stability after thermal recording.

(Means for Solving the Problems) As a result of intensive studies, the present inventors have found that a thermosensitive recording material comprising a recording layer containing a diazo compound and a coupling component on a support and a protective layer provided on the recording layer. The above object was achieved by using a heat-sensitive recording material characterized in that the recording layer contained α- (4-ethoxyphenoxy) acetamide.

In the present invention, it is preferable to provide a protective layer on the recording layer, particularly in order to improve running properties, durability, raw storage stability, and image stability over time after thermal recording. Examples of the protective layer used here include silicon-modified polyvinyl alcohol and colloidal silica, which are described in detail in Japanese Patent Application No. 63-169371. In the present invention, two or more protective layers of different components can be provided.

The present inventors, among various amides as additives,
It has been found that α- (4-ethoxyphenoxy) acetamide specifically satisfies the above object.

In the present invention, when plastic films are used in place of paper as the support, by incorporating the above components, the improvement in the stability of the image portion over time is more remarkable as compared with the prior art. It is.

The diazo compound used in the present invention has the general formula ArN ₂ ⁺ X ⁻
(Wherein, Ar represents an aromatic moiety, N ₂ ⁺ represents a cyazonium group, and X ⁻ represents an acid anion.) A diazonium salt represented by the following formula ^: And compounds that can be decomposed by light.

The coupling component used in the present invention is one that forms a dye by coupling with a diazo compound (diazonium salt) in a basic atmosphere. In combination with the diazo compound, these compounds are described in, for example, 63−
No. 169371 and JP-A-63-154393.

It is preferable to add a basic substance to the heat-sensitive recording material of the present invention in order to promote color formation. Examples of the basic substance include a poorly water-soluble or water-insoluble basic substance and a substance that generates an alkali by heating. Used.

As the diazo compound, the coupling component, and the optional basic substance used as the main components used in the present invention, one of them is used as the core substance of the microcapsule, or two kinds are used, or three kinds are used. Can be used. When two types are contained in the core material of the microcapsules, the same microcapsules or separate microcapsules may be used. When three kinds are contained in the core material of the microcapsule, three kinds cannot be contained simultaneously in the same microcapsule, but there are various combinations. Other components not contained in the core material of the microcapsule are used in the heat-sensitive layer outside the microcapsule.

The heat-sensitive recording material of the present invention has high heat sensitivity, can perform low-temperature high-speed heat recording, and can be fixed by heating and exposing to decompose unreacted diazo compounds after heating printing, so that it is suitable for various heat-sensitive recordings. Can be used for

(Examples) Examples will be shown below, but the present invention is not limited thereto. "Parts" indicating the amount of addition represents "parts by weight".

(Examples of the Invention) Examples The following diazo compound (3.45 parts) and 18 parts of (3: 1) adduct of xylylene diisocyanate and trimethylolpropane were added to a mixed solvent of 24 parts of tricresyl phosphate and 5 parts of ethyl acetate, and dissolved. did. This solution of the diazo compound was mixed with an aqueous solution in which 5.2 parts of polyvinyl alcohol was dissolved in 58 parts of water, and emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 2.5 μm. 100 parts of water was added to the obtained emulsion, and the mixture was heated to 60 ° C. with stirring, and after 2 hours, a capsule solution containing a core substance in a diazo compound was obtained.

Next, 10 parts of 2-hydroxy-3-naphthoic acid anilide and 10 parts of triphenylguanidine were added to 100 parts of a 5% aqueous polyvinyl alcohol solution and dispersed for about 24 hours by a sand mill. A guanidine dispersion was obtained.

Further, α- (4-ethoxyphenoxy) acetamide 20
Was dispersed in a paint shaker containing 100 parts of a 4% aqueous solution of polyvinyl alcohol and 100 parts of water for 2 hours, and the average particle size was 3 μm.
m was obtained.

Capsule liquid of diazo compound obtained as described above
Coating solution A was prepared by adding 50 parts of a coupling component, 24 parts of a dispersion of triphenylguanidine, and 28 parts of a dispersion of α- (4-ethoxyphenoxy) acetamide.

The coating solution A was applied on an 80 μm polyacetylene terephthalate film so as to have a dry weight of 10 g / m ² and dried at 25 ° C. for 30 minutes. forming a protective layer of m ^2, and to obtain a heat-sensitive material.

Preparation of protective layer coating solution Silica-modified polyvinyl alcohol (PVA R2105 manufactured by Kuraray Co., Ltd.) 1 part (solid content) Colloidal silica (Snowtex 30 manufactured by Nissan Chemical Co., Ltd.) 1.5 parts (solid content) Zinc stearate (Chukyo Oil & Fat) 0.02 parts (solid content) of paraffin wax (Hydrin P-7 manufactured by Chukyo Yushi Co., Ltd.) 0.02 parts (solid content) (Test method) GIII mode thermal printer (Hyfax 700; manufactured by Hitachi, Ltd.), and the whole surface was exposed and fixed by using Ricopy Super Dry 100 (manufactured by Ricoh). The blue density of the obtained recorded image was measured by a Macbeth reflection densitometer. The yellow density of the background was also measured.

Next, in order to examine the decrease in the optical density of the colored portion due to long-term storage after thermal recording, the recorded image of
After storing in a dark place at 16 ° C. for 16 hours and performing a forced deterioration test, the surface shape of the recorded image was observed.

As a result, a clear blue image was obtained in the printed area, image density> 1.2, background yellowing density <0.10, no change in the surface shape of the image area after the forced deterioration test, and excellent characteristics showed that.

Comparative Example 1 A heat-sensitive material was obtained in the same manner as in Example, except that α- (4-methoxyphenoxy) acetamide was used instead of α- (4-ethoxyphenoxy) acetamide in Example. When the recording material was tested in the same manner as in the example,
Although the image density and the background yellowing density were the same as those of the example, it was found that the surface shape of the image portion over time deteriorated.

Comparative Example 2 A heat-sensitive material was tested in the same manner as in Example, except that the protective layer was not used, and the image density and the background yellowing density were equivalent to those of the example. It was found that the surface shape of the image portion was significantly deteriorated.

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Claims (1)

(57) [Claims] 1. A heat-sensitive recording material comprising a recording layer containing a diazo compound and a coupling component on a support and a protective layer provided on the recording layer, wherein the recording layer is formed of α- (4-ethoxyphenoxy) acetamide. A heat-sensitive recording material comprising: