JPS5993385A - Light fixing type thermal recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal recording medium excellent in heat sensitivity and preservation stability and used for a facsimile, a printer or the like, comprising a water-insoluble of sparingly soluble diazonium salt, a coupler and a specified water-insoluble or sparingly soluble sensitizer. CONSTITUTION:The recording medium comprises a water-insoluble or sparingly soluble diazonium salt (e.g., a slat of p-N,N-dimethylaminobenzenediazonium or the like as a cation with BF<->4, SCN<-> or the like as an anion), a water-insoluble or sparingly soluble coupler (e.g., o-hydroxydiphenyl) and at least one water- soluble or sparingly soluble sensitizer selected from the group consisting of sensitizers of formulas I (wheren each of R1-R3 is H, alkyl; R4 is H, halogen, alkyl), II [wherein each of R1-R4 is H, OH, (substituted) alkoxy], III (wherein R1 is H, OH, alkyl or the like; R2 is alkyl, aryl or the like), IV (wherein each of R1-R10 is H, alkyl, alkoxy, halogen), V (wherein R11 is H, alkyl or the like) and VI [wherein each of R1-R4 is H, OH, halogen or the like; R5 is (ar)alkyl].

Description

Detailed Description of the Invention Regarding the thermal recording medium of the present invention, which records by heating and fixes the non-recorded portion by light irradiation, it is possible to perform thermal recording with high sensitivity between groups, and it has good storage stability. Concerning an excellent thermosensitive recording medium.

The thermal recording method has recently become widely used in facsimile machines, printers, etc. due to its advantages such as the ability to reduce the size and weight of the device and the ability to perform recording without noise.

However, the color-forming thermal recording paper that utilizes the reaction between an electron-receiving substance and an electron-accepting substance, which is currently widely used, cannot be colored by reheating, organic solvents, or adhesives. Coloring or decoloring with cellophane tape, etc. 1
There were some drawbacks.

There is a fixable Hiko thermosensitive recording paper that solves these drawbacks and utilizes a heat development 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.

Although many proposals have been made for conventional heat development diazo systems, no one has yet been created that combines high thermal sensitivity that can be recorded with a thermal head and sufficient storage stability.

The present inventors previously applied for a patent regarding a light-fixing thermosensitive recording medium with excellent heat sensitivity and storage stability, which contains a water-insoluble or poorly water-soluble diazonium salt and a water-insoluble or poorly water-soluble coupler as main components. did.

The present invention was developed as a result of repeated research aimed at further increasing the thermal sensitivity of this photofixable thermosensitive recording medium.

That is, the photofixable thermosensitive recording medium of the present invention contains a water-insoluble or poorly water-soluble diazonium salt, a water-insoluble or poorly water-soluble coupler, and a water-insoluble or poorly water-soluble compound represented by the following general formulas (1) to (6). It is characterized by containing.

General formula (wherein R,, R2, R3 are hydrogen or alkyl groups, R4
represents hydrogen, halogen or alkyl group. ) (In the formula, R,, R2, R3, and R4 represent hydrogen, a hydroxyl group, and a substituted or unsubstituted alkoxy group, and at least one of R2゜5-R3 represents a hydroxyl group or an alkoxy group.) (Formula Among them, R3 is hydrogen, hydroxyl group, argyl group, allyl group,
Indicates an alkoxy group, aryl group, aralkyl group, R2
represents an alkyl group, an aryl group, or an aralkyl group. ) (4) (In the formula, R1 to R1o represent hydrogen, an alkyl group, an alkoxy group, or a halogen.) (In the formula, R1 to R10 represent hydrogen, an alkyl group, a 6-alkoxy group, or a halogen, and R1, (Represents hydrogen, an alkyl group, an aryl group, an aralkyl group.) (In the formula, R1-R4 represent hydrogen, a hydroxyl group, a halogen, an alkoxy group, an alkyl group, an aryl group, an aralkyl group, and R5 represents an alkyl group, an aryl group, (Indicates an aralkyl group.) Most of the conventional heat development diazo methods use diazonium salts,
Since the coupler and at least one component of the basic substance are provided on the substrate in a dissolved state, coupling reactions often occur during storage. Many attempts have been made to prevent this, but as a result, the thermal sensitivity is now significantly reduced. However, the photofixable thermosensitive recording medium according to the present invention has extremely excellent storage stability because the water-insoluble or poorly water-soluble diazonium salt and the water-insoluble or poorly water-soluble coupler are provided in a dispersed state on the substrate. Furthermore, by including the water-insoluble or poorly water-soluble compounds represented by the above general formulas (1) to (6), the thermal sensitivity is significantly improved. These heat-sensitizing sensitizers melt when heated and have the property of making the diazonium salt, coupler, and basic substance used as necessary compatible with each other, and for this reason, remarkable heat sensitization can be obtained. .

Furthermore, these sensitizers are water-insoluble or poorly water-soluble and do not impair the storage stability of the recording medium.

Next, each component used in the present invention will be explained.

The water-insoluble or slightly water-soluble diazonium salt used in the present invention is obtained by changing the anion component of a conventionally known diazonium salt to a special anion. All conventionally known diazonium cations can be used, such as p-N, N-dimethylaminobenzenediazonium, 4-benzamido-2,5-jethoxybenzenediazonium, 4-morpholino-2,5-dibutoxy Benzenediazonium, etc. Examples of anions that make the diazonium salt water-insoluble or poorly soluble are BP4-, TIFs"-8nF
62-, ZnP2. Examples include pF6-, 5CN-, phosphotungstate ion, phosphomolybutylene/acid ion, arylsulfonate ion, organic boron ion, and analogs thereof.

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

Here, the 2,3-dihydroxynaphthalene-6-sulfonic acid ion also has a function as a coupler.

Next, specific examples of organic boron ions will be shown.

The method for synthesizing the water-insoluble or poorly water-soluble diazonium of the present invention is as follows. That is, a conventionally known water-soluble diazonium salt, for example p=14. An aqueous solution of N-dimethylaminebenzenediazonium chloride-10=dozinc chloride and an aqueous solution of a compound that liberates the above-mentioned special anion in the aqueous solution, such as KPF6, are mixed and stirred. Since the precipitate formed in the aqueous solution is the desired water-insoluble or poorly water-soluble diazonium salt, it is sufficient to collect as much of it as possible.

As the coupler in the present invention, any water-insoluble or poorly water-soluble coupler can be used. For example, 2-hydroxy-3-naphthoic acid derivatives such as 0-hydroxydiphenyl, 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2,7-cyhydrogizonaphthalene, naphthol AB, naphthol AS-D, naphthol AS-BO, etc. etc.

The heat sensitivity sensitizer, which is the most important component in the present invention, includes the following compounds.

A specific example is 0 t-C, H9 can be mentioned.

A specific example is H3 Ho% cooCH2 m, p, 1.10℃-13
- Specific examples include: 0 -14- OOH H Specific examples and I-: OH3 These compounds are required to be water-insoluble or poorly water-soluble from the viewpoint of storage stability of the recording medium.

In addition, in the present invention, a basic substance that melts, dissolves, decomposes, reacts, etc. when heated and creates a basic atmosphere suitable for the coupling reaction between the diazonium salt and the coupler can be used. As this basic substance, a water-insoluble or poorly water-soluble substance is selected from conventionally known substances.

Examples include organic amines such as distearylamine, nitrogen-containing heterocyclic compounds such as 2-phenylimidazole, and guanidine derivatives. Examples of guanidine derivatives suitable as basic substances in the present invention include 1,3-diphenylguanidine, 1,3-di-0-tolylguanidine, and 1,3-di-0-tolylguanidine.
Di-p-methoxyphenylguanidine, 1.2.3-)
Examples include diphenylguanidine, c(triphenylguanidino)methane, and the like.

In the present invention, it is possible to use a water-insoluble or poorly water-soluble substance that has the dual functions of a coupler and a basic substance. Examples of couplers having this basic residue include 17-.

In order to further improve the storage stability of the photofixable thermosensitive recording medium according to the present invention, a water insolubilizing agent or a water hardly solubilizing agent of diazonium salt can be used.

- The water-insolubilizing agent or water-poorly solubilizing agent for the diazonium salt is water-soluble, and a substance that liberates the anion component mentioned above for the diazonium salt in an aqueous solution is used. For example, H.B.
F4. H2TiF6. H2TiF6゜H2TiF6
．． Acids such as HpF6 and their salts, phosphotungstic acid,
Examples include heteropolyacids such as phosphomolybdic acid and silicotungstenic acid and salts thereof, thiocyanic acid and salts thereof, arylsulfonic acids and salts thereof, and organic boron salts.

Specific examples of the arylsulfonic acids and their salts mentioned as the water insolubilizing agents or water-poorly solubilizing agents for the above-mentioned diazonium salts are shown below.

Specific examples of the organic boron salts listed as water insolubilizers or poorly water-solubilizing agents for diazonium salts, components of diazonium salts, couplers, basic substances, water insolubilizers or poorly water-solubilizing agents for diazonium salts, and sensitizers are: It is possible to select and use only one type from among those explained above, or to use a combination of two or more types.

The binders used in the present invention include conventionally known water-soluble binders such as polyvinyl alcohol, starch, inbutylene-maleic anhydride copolymer salt, polyvinyl acetate,
Examples include emulsions such as polyacrylic acid ester and styrene-butadiene latex.

-20- In addition, in the present invention, pigments such as silica, aluminum hydroxide, and calcium carbonate, antioxidants such as thiourea and ascorbic acid, and various waxes as coloring sensitivity and coloring density improvers may be used. can.

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

A method for producing the photofixable thermosensitive recording medium of the present invention will be explained. The diazonium salt, coupler, basic substance, and sensitizer are each dispersed in water alone or in combination of two or more components. Dispersion is carried out using various devices such as a ball mill, and various dispersants can be used as necessary. A water insolubilizing agent or a water hardly solubilizing agent for the diazonium salt, a binder, a pigment, and various additives can be added before or after dispersion. A paint is prepared by adding and mixing these dispersions with a water-insolubilizing agent or a water-poorly solubilizing agent for diazonium salts, a binder, and various additives, if necessary, in an appropriate order. The photofixable heat-sensitive recording medium of the present invention can be obtained by coating or impregnating a substrate with this coating material by an appropriate method. In addition, in order to further improve storage stability, each dispersion can be divided into two or more layers.

Next, the specific production of the photofixable thermosensitive recording medium of the present invention will be explained with reference to Examples.

Examples 1 to 6 Paints having the following formulations were prepared, applied onto high-quality paper with a basis weight of 64 t/m' using a wire bar, and dried at 55°C. The dry coating amount was 5.0 g/m'.

-22-! 6 using 20 parts by weight of a 20% aqueous dispersion of a sensitizer
The types of sensitizers are shown in Table 1 along with the color development properties of their recording media. The color development characteristics of this photofixable thermosensitive recording medium are expressed by the color development temperature by hot plate color development and the printing record by the thermal head. Hot plate color development involves pressing the recording medium against a hot plate at a predetermined temperature for 5 seconds under a pressure of 400 ii'/l-++1 to develop color.The temperature that gives a density of /2 of the maximum color density is called the color development temperature. shall be. Further, the recording density with the thermal head is shown under the printing conditions of an applied voltage of 16v1 and a pulse width of 2.3m-5ec.

COMPARATIVE EXAMPLE A recording medium having the same formulation as in the example was prepared except that the sensitizer in the example was omitted. The coloring characteristics of this recording medium are also shown in Table 1.

In both Examples and Comparative Examples, the storage stability of the unrecorded and unfixed media was good, and they were stored for 6 months at a relative temperature of 20°C and 60°C under light shielding.
Almost no ground fogging was observed even when the film was left for 24 hours under light shielding at a relative temperature of 40°C and 90°C. Further, almost no deterioration in recording properties was observed under these storage conditions.

As explained above, the photofixable thermosensitive recording medium according to the present invention is an extremely practical photofixable thermosensitive recording medium that has both extremely high thermal sensitivity and excellent storage stability.

Table 1 thermal head printing patent applicant Tomoekawa Paper Mill Co., Ltd. Nippon Telegraph and Telephone Corporation -25-

Claims (1)

[Scope of Claims] A photofixable heat-sensitive recording medium containing a diazonium salt and a coupler as main components, a water-insoluble or poorly water-soluble diazonium salt, a water-insoluble coupler, and the following general formulas (1) to
A photofixable thermosensitive recording medium comprising at least one water-insoluble or poorly water-soluble compound represented by (6). General formula (wherein R1, R2, R3 are hydrogen or alkyl groups, R4
represents hydrogen, halogen or alkyl group. ) (wherein, R
1, R2, R3, and R4 represent hydrogen, a hydroxyl group, or a substituted or unsubstituted alkoxy group, and at least one of R2°R3 represents a hydroxyl group or an alkoxy group. ) (3) R] (wherein R1 is hydrogen, hydroxyl group, alkyl group, allyl group,
Indicates an alkoxy group, aryl group, aralkyl group, R2
represents an alkyl group, an aryl group, or an aralkyl group. ) (4) (In the formula, R1 to R1o represent hydrogen, an alkyl group, an alkoxy group, or a halogen.) (In the formula, R1 to R10 represent hydrogen, an alkyl group, an alkoxy group, or a halogen, and R11 represents hydrogen or an alkyl group. group, aryl group, aralkyl group) (in the formula) ~R4 represents hydrogen, hydroxyl group,...rogen, alkoxy group, alkyl group, aryl group, aralkyl group, and R5 represents an alkyl group, aralkyl group. show.)