JPS61220889A - Photo-fixable type thermal recording medium - Google Patents

Abstract

PURPOSE:To provide a photo-fixable type thermal recording medium capable of forming a color with a pure black tone constantly under any heating conditions, by providing a combination of a specified diazonium salt, a specified blue color forming coupler and a specified yellow - red color forming coupler. CONSTITUTION:At least one compound selected from compounds of general formula (I) and/or (II) as a diazonium salt, at least one compound selected from compounds of general formula (III) as a blue color forming coupler and at least one compound selected from compounds of general formula (IV) as a yellow - red color forming coupler, are used. In the formulas, each of R1 and R2 is hydrogen or subst. or unsubst. alkyl, with the proviso that R1 and R2 are not simultaneously hydrogen, R3 is 1-18C alkyl or alkoxy, R4 is 1-18C alkyl, X is paired anion component, R5 is subst. or unsubst. aromatic ring or subst. or unsubst. alkyl, R6 is subst. or unsubst. alkyl or alkoxy, and R7 is subst. or unsubst. alkyl.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a light-fixing type thermal recording medium that performs recording by heating and fixes non-green areas by light irradiation. The present invention relates to a black coloring light-fixing type heat-sensitive recording medium which is capable of printing and has excellent storage stability.

<Prior Art> The thermal recording method has recently come into widespread use in facsimile machines, printers, etc. due to its advantages such as being able to reduce the size and weight of the device and recording without noise. However, the currently widely used dye-colored thermal recording paper that utilizes the reaction between an electron-donating substance and an electron-accepting substance cannot be colored by reheating or organic solvents, or can be colored by using adhesives or cellophane tape. There was a problem with the color fading. There is a fixable heat-sensitive recording paper that solves these drawbacks and utilizes a heat-developable diazo method. When this heat-developable diazo paper is used as a heat-sensitive recording paper, recording is first performed using heat, and then fixing is performed using light. Various color tones can be obtained by selecting the coupler, but pure black color tone is particularly desired.

Conventionally, phloroglucin has been widely used to obtain a black color tone. However, recording paper containing phloroglucin as a coupler is prone to pre-coupling at high temperatures (and has the disadvantage that the background tends to change color in bright places even after fixing. A method using a mixture of yellow to red couplers of diazonium salts or active methylene series is also used.However, in this case, the coupling speed varies depending on the combination of diazonium salt and coupler, so black is always produced under any coloring conditions. It is very difficult to find a combination of a mixture of a diazonium salt and a coupler that can produce color.Also, many proposals have been made regarding the thermal development diazo method.However, the high No material has yet been produced that satisfies both thermal sensitivity and sufficient storage stability.

<Problems to be Solved by the Invention> The present invention has been made in order to solve the above-mentioned drawbacks, and its purpose is to provide a light-fixing type thermosensitive material that always exhibits a good pure black tone under any heating conditions. The goal is to provide recording media.

Means for Solving the Problems> The present invention uses three color-forming couplers: a diazonium salt, a blue color-forming coupler, and a yellow to red color-forming coupler, in order to produce a light-fixable heat-sensitive recording medium that exhibits a good pure black color. A particular combination of ingredients was discovered. That is, at least one compound selected from the following general formula (1) and/or (II> as a diazonium salt, at least one compound selected from the following general formula (III) as a blue color-forming coupler, and a yellow The object of the present invention is achieved by using at least one compound selected from the following general formula (IV) as a red color-forming coupler.

[In the formula, R5 and R2 represent hydrogen or a substituted or unsubstituted alkyl group. However, R8 and R2 are not hydrogen atoms at the same time. Y represents hydrogen or halogen. ]0~ (In the formula, R3 represents a C7-C+e alkyl group or an alkoxyl group, and R represents a C5-C+a alkyl group.

X represents a counter anion component. ) [In the formula, R6 represents a substituted or unsubstituted aromatic ring or a substituted or unsubstituted alkyl group. [In the formula, R6 represents a substituted or unsubstituted alkyl group or alkoxyl group, and R7 represents a substituted or unsubstituted alkyl group.

] Specific examples of the diazonium salt represented by the general formula (1) used in the present invention are shown below.

Specific examples of the diazonium salt represented by the general formula (II) used in the present invention include the following.

In order to improve the shelf life of the photofixable thermosensitive recording medium of the present invention at high temperatures, it is desirable to select a diazonium salt that is insoluble or poorly soluble in water. For this purpose, preferred anion components of the diazonium salt include BP, ,P
F, and organic boron ions represented by the following general formula.

[However, RII to R+a each represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, a heterocyclic group, or a cyano group. ] A specific example is shown below.

Specific examples of the blue color-forming coupler represented by the general formula ([[[)] used in the present invention are shown below.

CH3 Specific examples of the yellow to red color-forming coupler of general formula (rV) used in the present invention include the following.

The mixing ratio of the above-mentioned blue color-forming coupler and yellow to red color-forming coupler is usually 10=1 to 1:10, preferably 5:1 to 1:2 in terms of molar ratio. The molar ratio of the diazonium salt to the coupler mixture is suitably 1:1 to 1:5.

In the medium of the present invention, a basic substance is also preferably used to create a basic atmosphere suitable for the coupling reaction between the diazonium salt and the coupler during heating. Conventionally, water-soluble basic substances such as urea and its derivatives, inorganic and organic ammonium salts, and organic amines have been used. However, it is preferable to use a water-insoluble or sparingly water-soluble basic substance in order to improve raw storage stability under high humidity conditions. Examples of this include distearylamine, 2-phenylimidazole, 3-di-0-tolylguanidine and 1.2
．． Examples include 3-triphenylguanidine.

In the present invention, in order to further improve storage stability at high humidity,
An organic boron salt having the following general formula, which is an agent for making a diazonium salt water insolubilizing or water-poorly solubilizing, can be used.

[However, R11 to R4 are each an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, a heterocyclic group,
Or represents a cyano group. M represents a beam or Na.

] A specific example of this is shown below.

These organic boron salts are added to the paint as a solution, but the amount used is 0.1 - diazonium salt in solid form.
1000% weight part, more preferably 10-300%
% parts by weight.・As the binder used in the present invention, conventionally known polyvinyl alcohol (hereinafter, PV
A), starch, water-soluble binders such as isobutylene-maleic anhydride copolymer salts, various emulsions such as polyvinyl acetate, polyacrylic esters, polyurethane, styrene-butadiene latex, polyesters, Polyvinyl, polyurethane, cellulose,
Examples include various solvent-soluble binders such as rubber-based binders.

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, benzoguanamine resin fine particles, and acid stabilizers such as oxalic acid, tartaric acid, and triclochloric acid are used. , antioxidants such as thiourea ascorbic acid, various waxes as agents for improving color development sensitivity and color density, and aluminum tripolyphosphate for improving storage stability.

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

The recording medium of the present invention is produced by dissolving or dispersing the diazonium salt, the coupler mixture, 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, the coupler mixture, and if necessary the basic substance are all contained in one layer or are present in two or more layers; in the latter case, many combinations are possible. can.

<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 A paint having the following formulation was prepared, applied onto high-quality paper with a weight of 64 g/j using a wire bar, and dried at 55°C.

The dry coating amount was 4.5 g/fJ.

When this light-fixing thermosensitive recording medium was pressed against a hot plate at a predetermined temperature for 5 seconds under a pressure of 100 g/- to develop color, the maximum density of black was 1.32, which was 1/2 of the maximum density.
The color density was 78°C, which was defined as the temperature that gave the density of . Furthermore, the color tone did not change depending on the temperature of the hot plate and always showed a pure black tone.

A density of 1.10 was obtained when recording was performed with a thermal head under printing conditions of an applied voltage of 16 V, a pulse width of 3, and 0 m5 ec. 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 can be left for about 1 hour under indoor light, or it can be heated at a distance of 2cm using two 85W ultraviolet fluorescent lamps.
When exposed at m+, fixing was completed in about lθ seconds and had extremely excellent fixing properties. It was confirmed that the background color after fixing was also white, giving it excellent naturalness as a recording paper, and that 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 concentrations were measured and found to be 0.20 and 0.23, respectively. After light fixation, the background color appeared slightly grayish.

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

Example 2 A paint having the following formulation was coated on a high-quality paper weighing 64 g/- with a wire bar and dried at 120°C to produce a pre-coated paper. The dry coating amount was 3.5 g/J.

A diazo dye having the following formulation was applied onto this precoated paper using a wire bar and dried at 60°C. Dry application amount is 2.8
g/-.

Furthermore, a coupler paint having the following formulation was applied onto this diazo layer using a wire bar and dried at 55°C. Dry application amount is 3.
It was 5g/-.

When this photofixable thermosensitive recording medium was examined in the same manner as in Example 1, it exhibited pure black tone color development with a color development start temperature of 81° C. and a thermal head recording density of 1.07.

A 24-hour storage stability test at 40°C and 90% relative humidity gave a soil concentration of 0.18. In addition, the light fixing time was approximately 1 in Example 1.
/2, and the background color after fixing was sufficiently white and natural.

Example 3 A product was prepared in the same manner as in Example 2 except that the diazonium salt in Example 2 was changed to the following.

OC store.

This photofixable thermosensitive recording medium exhibited almost the same good characteristics as Example 2.

<Effects of the Invention> As explained above, the photofixable thermosensitive recording medium of the present invention has the following effects:
By combining the diazonium salt of the present invention and a coupler, very good black coloring could be achieved.

Patent application, Tomoekawa Paper Mill Co., Ltd.

Claims (1)

[Scope of Claims] A photofixable heat-sensitive recording medium containing a diazonium salt and a coupler as main components, in which at least one diazonium salt selected from the following general formulas (I) and/or (II) is added to the recording medium. compound, at least one compound selected from the following general formula (III) as a blue color-forming coupler, and the following general formula (I) as a yellow to red color-forming coupler.
V) A photofixable heat-sensitive recording medium, comprising at least one compound selected from V). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the formula, R_1 and R_2 represent hydrogen and a substituted or unsubstituted alkyl group. However, R_1 and R_2 are not hydrogen atoms at the same time. Y represents hydrogen or halogen. ] ▲ There are numerical formulas, chemical formulas, tables, etc. ▼... (II) [In the formula, R_3 represents an alkyl group or an alkoxyl group of C_1 to C_1_8, and R_4 represents an alkyl group of C_1 to C_1_8. X represents a counter anion component. [In the formula, R_5 represents a substituted or unsubstituted aromatic ring or a substituted or unsubstituted alkyl group. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(IV) [In the formula, R_6 represents a substituted or unsubstituted alkyl group or alkoxy group, and R_7 represents a substituted or unsubstituted alkyl group. ]