JPS6235876A - Photo-fixable type thermal recording medium - Google Patents

Abstract

PURPOSE:To achieve both high heat sensitivity and excellent preservation stability, by using an alkyl-subst. guanidine or salt thereof which is insoluble or difficultly soluble in water as a basic substance, in a photo-fixable type thermal recording medium comprising a diazonium salt, a coupler and a basic substance as main constituents. CONSTITUTION:The recording medium is produced by dissolving or dispersing a diazonium salt, a coupler a basic substance and other required constituents in water or a solvent, and applying the resultant liquid to a substrate together with a binder. An alkyl-subst. guanidine or salt thereof which is insoluble or difficultly soluble in water is used as the basic substance. The alkyl-subst. guanidine is a guanidine having at least one 8-24C alkyl, for example, octylguanidine, nonylguanidine or N,N-didecylguanidine. Examples of the acidic substance which can be used for forming a salt with the alkyl-subst. guanidine include benzenesulfonic acid, trichloroacetic acid, lactic acid and carbonic acid. Accordingly, both high heat sensitivity and excellent raw preservation stability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light-fixing type thermosensitive recording medium that performs recording by heating and fixing non-recorded areas by irradiating light, and more specifically, it is capable of thermal recording with high sensitivity and is stable in storage. The present invention relates to a photofixable thermosensitive recording medium with excellent properties.

<Prior Art> Recently, thermal recording methods have become widely used in facsimile machines, printers, etc. due to their advantages such as the ability to reduce the size and weight of devices and to perform noiseless recording. However, currently available dye-colored thermal recording paper that utilizes the reaction between a donating substance and an electron-accepting substance can be colored by reheating or using an organic solvent, or can be colored by using an adhesive or cellophane tape. There was a problem of color fading.There is a fixable heat-sensitive recording paper that solves these drawbacks and uses a heat-developable diazo method.When using this heat-developable diazo paper as a heat-sensitive record paper, First, recording is performed using heat, and then fixing is performed using light.Heating is performed by a thermal head in an extremely short time of several milliseconds, so the thermal sensitivity is superior to that of the conventional thermal development diazo method. In addition, in order to be used in the same way as current dye-colored thermal recording paper, it will need excellent shelf life, including in high-temperature, high-humidity environments.

Many proposals have been made regarding the heat development diazo method. However, nothing has yet been produced that satisfies both the high thermal sensitivity recordable by a thermal head and sufficient storage stability.

<Problems to be Solved by the Invention> The present invention has been made to solve the above-mentioned drawbacks. That is, the present invention provides a photofixable thermosensitive recording medium that satisfies both high thermal sensitivity and excellent raw storage stability.

<Means for Solving the Problems> The present invention solves the problems by using a new basic substance. That is, the photofixable heat-sensitive recording medium of the present invention is characterized in that the main components are a diazonium salt, a coupler, and a basic substance, and the basic substance is an alkyl-substituted guanidine or a salt thereof that is insoluble or sparingly soluble in water. It is said that

The argyl-substituted guanidine of the present invention has at least one C8 to C24 argyl group.

Examples of alkyl-substituted guanidines include octylguanidine, nonylguanidine, decylguanidine, undecylguanidine, laurylguanidine, tridecylguanidine, myristylguanidine, hexadecylguanidine, octadecylguanidine, icosylguanidine, tocosylguanidine, dioctylguanidine, Dioctadecylguanidine, N-methyl-N-octadecylguanidine, N-methyl-N-decylguanidine, N.

Examples include N-siderguanidine.

On the other hand, examples of acidic substances that can form salts with alkyl-substituted guanidines include benzenesulfonic acid, trichloroacetic acid, oxalic acid, glycerophosphoric acid, malonic acid, phosphoric acid, citric acid, maleic acid, tartaric acid, malic acid, Examples include lactic acid and carbonic acid.

Furthermore, the alkyl-substituted guanidine salt used in the present invention can be synthesized by a known method. That is, a solution prepared by dissolving alkyl-substituted guanidine in a suitable solvent is heated to 500 C, and while stirring, the solution is weighed in advance into a stoichiometric amount, and the dissolved solution is added dropwise. By continuing stirring for about 10 minutes after the completion of the dropwise addition, a yield of about 100% can be obtained.

These alkyl-substituted guanidines and their salts can effectively form a basic atmosphere at temperatures near their melting points, and can form an azo dye by coupling the diazonilla salt with a coupler. All of these guanidine derivatives are stable at room temperature, and require much longer time for decomposition during storage than conventionally known urea, imidazole derivatives, and the like. Furthermore, most of the conventionally known basic substances have very high water solubility, which has the disadvantage that the heat-sensitive layer develops color during storage under the influence of moisture in the air. However, since the guanidine derivative used in the present invention is insoluble or poorly soluble in water, it has excellent storage stability.

The diazonium salt used in the present invention is a conventionally known diazonium salt. That is, P-N, N-
Dimethylaminobenzenediazonium chloride zinc chloride, 4-benzamide-2゜5-jethoxybenzenediazonium chloride zinc chloride, 4-morpholino-2,
5-dibutoxybenzenediazonium zinc chloride, 4. −
(P-tolylmercapto)-2,5-jethoxybenzenediazonium chloride and zinc chloride. These zinc chloride type diazonium salts are water-soluble, but in order to improve storage stability under high temperature and high humidity, water-insoluble or slightly water-soluble ones are preferable, and they are the anion components of the above-mentioned conventionally known diazonium salts. can be obtained by changing into a special anion. The anion that makes the diazonium salt water-insoluble or poorly water-soluble is B F % T.
iF c ”, SnF6”, ZIIF4, PF6, SC
Examples include N, phosphotungstate ion, phosphomolybdate ion, arylsulfonate ion, and the like.

Here, specific examples of arylsulfonic acid ions are shown below.

The method for synthesizing water-insoluble or poorly water-soluble diazonium is as follows. That is, conventionally known water-soluble diazonium salts,
For example, an aqueous solution of PN,N-dimethylbenzenediazonium zinc chloride and an aqueous solution of a compound that liberates the above-mentioned special anion in the aqueous solution, such as KPF, are mixed and stirred. Since the precipitate formed in the aqueous solution is the desired water-insoluble or poorly water-soluble diazonium salt, it may be filtered.

As the coupler, a conventionally known coupler that forms a dye even when coupled with a diazonium salt is used. Examples of water-soluble couplers include resorcinol, phloroglucin, sodium l-hydroxynaphthalene-4-sulfonate, sodium 2,3-dihydroxynaphthalene-6-sulfonate, sodium 2,7-dihydroxynaphthalene-3,6-disulfonate, Examples include acetoacetanilide. Examples of water-insoluble or poorly water-soluble couplers include O-hydroxydiphenyl, 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2゜7-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, naphthol AS, naphthol AS-D1 Examples include 2-hydroxy-3-naphthoic acid derivatives such as naphthol AS-BO.

The binders used in the present invention include conventionally known water-soluble binders such as polyvinyl alcohol (hereinafter abbreviated as PVA), starch, isobutylene-maleic anhydride copolymer salt, and polyacetic acid. Examples include various emulsions such as vinyl, polyacrylic ester, polyurethane, and styrene-butadiene latex, and various solvent-soluble binders such as polyester, polyvinyl, polyurethane, cellulose, and rubber.

In addition, in the present invention, inorganic pigments such as silica, aluminum hydroxide, and calcium carbonate, organic pigments such as crosslinked styrene fine particles, urea-formalin resin fine particles, and benzoguanamine resin fine particles, antioxidants such as thiourea ascorbic acid, and color development sensitivity Also, various waxes can be used as coloring density improvers, and aluminum tripolyphosphate can be used to improve storage stability.

As the substrate in the present invention, high-quality paper, coated paper, synthetic resin film, woven fabric sheet, metal, glass, etc. can be used.

The recording medium of the present invention is prepared by dissolving or dispersing a diazonium salt, a coupler, a basic substance, and other necessary components in water or a solvent, and coating the solution together with a binder on the above-mentioned substrate. Here, the diazonium salt, coupler, and basic substance may all be contained in one layer or separated into two or more layers, and in the latter case, many combinations can be taken. .

<Example> Next, the specific production of the photofixable heat-sensitive recording medium of the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Example 1 High-quality paper coated with PVA to prevent solvent penetration, basis weight 6
0g/n? A dispersion having the following formulation was applied onto a pre-coated paper using a wire bar and dried at 70°C in a hot air circulation constant temperature dryer. The dry coating amount was 3 g/i.

On top of this, apply a photosensitive solution with the following composition with a wire bar, 60
Dry at °C. The dry coating amount was 1.5 g/d.

This photofixable thermosensitive recording medium was placed on a hot plate at a predetermined temperature for 5 seconds at 100 g/cn? When the color was developed by applying a pressure of 1/2, the color developed blue, and the maximum density was 1.02, and the color density was 78° C. when the temperature that gave 1/2 of the maximum density was defined as the color density. Applied voltage 16V1 Pulse width 3
．． When recording with a thermal head under printing conditions of 0m5ec, 0
．． A concentration of 89 was obtained. Even when recording was performed by varying the applied voltage and pulse width, the color tone produced was always pure black.

This light-fixing type thermosensitive recording medium is left for about 1 hour under room light, or is heated to a distance of m 2 using two 85W ultraviolet fluorescent lamps.
When exposed to light at cm, fixing was completed in about 10 seconds and had extremely excellent fixing properties. It was confirmed that the background color after fixing was white and had excellent naturalness as a record, and no color developed even when heated after fixing.

On the other hand, regarding storage stability, unrecorded media can be stored at 20°C and 60% relative humidity for 6 months under light shielding, or at 40°C and 90% relative humidity.
After standing for 24 hours under 0% light shielding, the soil concentration was measured and found to be 20.0.23 for each //1 area. After photofixing, the background color appeared slightly bluish.

Note that all the various concentrations were measured using a visual filter of a Macbeth densitometer (RD514).

Example 2 A light-fixable heat-sensitive recording medium was prepared by sequentially laminating and coating the following paints on high-quality paper weighing 55 g/I.

■ Lower layer paint coating amount 2.5g/n? l Diazonium chloride zinc chloride ■ Upper layer paint Coating amount: 1.5 glt&L cyclohexane 30 g This light-fixable thermosensitive recording medium was examined in the same manner as in Example 1, and it was found that a blue color was formed at a temperature of 83°C and a thermal head recording density of 1.02. It showed color development.

A 24-hour storage stability test at 40° C. and 90% relative humidity showed a soil concentration of 0.18.

Example 3 A photofixable heat-sensitive recording medium was prepared by sequentially laminating and coating the following paints on high-quality paper with a basis weight of 55 g/a.

■ Lower layer paint coating amount 3 g/n? L polyvinyl acetate emulsion (30%) 15g upper layer paint
Coating amount: 1.0 g/J When this photofixable thermosensitive recording medium was examined in the same manner as in Example 1, the color development starting temperature was 80°C.
, the thermal head exhibited blue color development with a recording density of 1.06.

A 24-hour storage test at 40°C and 90% relative humidity gave a soil concentration of 0.21.

Example 4 The following coatings were sequentially laminated and coated on a milky white polyethylene terephthalate film having a thickness of 188 um to produce a photofixable heat-sensitive recording medium.

(2) Lower layer paint: Coating thickness: 3 μIn; (2) Upper layer paint: Coating thickness: 2 μm. This light-fixing type heat-sensitive recording medium exhibited good characteristics almost equivalent to those of the above examples.

Example 5 The following coating material was applied to a milky white polyethylene terephthalate film having a thickness of 188 um to prepare a photofixable heat-sensitive recording medium. The amount of coating was 4 g/+J.

[60 g of cyclohexane When this photofixable thermosensitive recording medium was examined in the same manner as in Example 1, the color development start temperature was 77°C, and the thermal head recording density was 1.
．． 15 blue color was developed.

The 24-hour storage test at 40℃ and 90% relative humidity was
It was 11 degrees and 0.23.

<Effects of the Invention> As explained above, the photofixable thermosensitive recording medium of the present invention was able to achieve both high thermal sensitivity and excellent storage stability by using a specific basic substance. .

Claims (1)

[Claims] A photofixable thermosensitive recording medium containing a diazonium salt, a coupler, and a basic substance as main components, characterized in that an alkyl-substituted guanidine or a salt thereof that is insoluble or sparingly soluble in water is used as the basic substance. recoding media.