JPS5882789A - Diazo heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To prevent the decoloration of the ground texture of non-printing part in a diazo heat-sensitive recording material by adding a maleic anhydride-based resin to a heat-sensitive chromogenic layer composed of a diazo compound and a coupler. CONSTITUTION:A heat-sensitive chromogenic layer composed of a diazo compound, a coupler, and a heat-meltable substance is formed on the surface of a supporter. As a binder for the heat-sensitive chromogenic layer, a maleic anhydride-based resin (e.g., maleic anhydride-butadiene copolymers, maleic anhydride-isobutylene copolymers, etc., containing maleic anhydride as a copolymerizable monomer) is used mainly. The use of a heat-meltable substance of a softening point of 50-250 deg.C, e.g., 2-tribrome ethanol, 2,2-dimethyltrimethylene glycol, etc., results in the enhancement of the storage stability of products as well as the improvement of heat respondency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, particularly a heat-sensitive recording material that can be photofixed. That is, the present invention relates to a diazo-based thermosensitive recording material that develops color when recorded with a thermal head at a certain temperature, loses its ability to develop color in non-printed areas when further irradiated with light, and does not recolor when heat is applied again. It is.

In addition to being used as copy paper for books and documents, thermosensitive recording materials are also used as output recording paper for computers, facsimile machines, medical measuring machines, etc., as well as thermal recording magnetic ticket paper and thermal recording label paper. be done. In addition, heat-sensitive recording materials are also being considered for use as paper for creating securities, gift certificates, admission tickets, certificates, slips, etc. by taking advantage of their ease of automatic recording. In order to obtain high recording reliability, the heat-sensitive recording material must be able to be fixed.

Conventionally, as fixable heat-sensitive recording materials, diazo-based materials that utilize a color-forming reaction between a diazo compound and a coupler are known. However, from a practical point of view, the conventional ones have the disadvantage of poor background discoloration.

Here, background discoloration refers to the degree of discoloration of the background portion of diazo thermal paper that has been subjected to optical fixing after heating printing with a thermal head.

The inventors of the present invention have completed the present invention as a result of intensive research aimed at solving the problem of skin fading.

That is, according to the present invention, in the heat-sensitive color forming layer containing a diazo compound and a coupler provided on a support, a maleic anhydride resin is used as at least a part of the binder in the heat-sensitive color forming layer. A diazo-based heat-sensitive recording material is provided.

In addition, the heat-sensitive color forming layer as used in the present invention refers to one layer or a multilayer of two or more layers formed to support heat-sensitive color forming layer forming components such as a diazo compound, a coupler, and a thermofusible substance on a support. This means the entire coating layer. Therefore, the thermosensitive color forming layer forming components are simultaneously contained in one coating layer, or
Alternatively, it is appropriately divided and contained in two or more multilayer coating layers.

In the present invention, a maleic anhydride resin is used as a binder applied to the heat-sensitive coloring layer, but it is unexpected that the use of such a special resin significantly improves the fading of the background color of the product. . As maleic anhydride resin,
In addition to maleic anhydride resins, various copolymers containing maleic anhydride as a comonomer, such as maleic anhydride/butadiene copolymers, maleic anhydride/imbutylene copolymers, maleic anhydride/isoprene copolymers, etc. can be mentioned. Although these maleic anhydride resins are used alone as a binder, they can be used in combination with other conventional binders as long as they do not particularly impede the purpose of the present invention.

Further, when the heat-sensitive coloring layer has a laminated structure of two or more layers, the maleic anhydride resin may be applied to at least a portion of each layer.

The diazo compound and coupler used in the present invention are those commonly used in diazo photosensitive paper, and include, for example, those shown below.

Diazo Compound: As the diazo compound used in the present invention, a commonly used diazo compound, for example, one represented by the following general formula is used.

1 9 However, in general formula (1), l] and s, R1e R
6R8 is hydrogen, halogen, C1-CB alkyl group is also R
3, R, Id, hydrogen, halogen, self to C5 alkyl group or alkoxyl group% R4+ R5 is the same - or 0
1 to C3 alkyl group or alkoxyl group, or halogen), R7 is hydrogen, halogen, trifluoromethyl group, Ci to C5 alkyl group or AlR+a:
(same as R13), M, , M2, M3 are acid residues or acid residues forming a double salt with a metal salt. In this case, the acid residue and 1. Then, halogen ions, BFi, PFi
It is preferable to use fluorine-containing inorganic acid ions such as
Examples of metal salts that form double salts with acid residues include ZnCl2 +CdCl2.5nC12.

Y represents -CH2- or -CO-, and n is 0 or 1.

Specific examples of those corresponding to general formula (1) include the following.

CH3 0C, Hs CH3 0C2H5 Specific examples of those falling under the general formula include the following: 1 OC2H.

Specific examples of things that fall under the category of general screams include the following:

LJL; 2tiB CH3 In the present invention, in order to obtain a product with further improved long-term shelf life, the diazo compound may be used in the form of a water-insoluble salt such as a fluorine-containing salt such as -BF4 or -PF. is advantageous.

Katupura m: Couplers used in the present invention include phenol, resorcin, methylresorcin, 4,4-bis1/turcin, phloroglucin, resorcinic acid, phlorocrusic acid,
2-methyl-5-methoxy-1,3-dihydroxybenzene, 5-methoxy-1,3-dihydroxybenzene,
4-N,N-dimethylphenol, 2,6-dimethyl-1,3,5-trihydroxybenzene, 2,6-dihydroxybenzoic acid, 2,6-cyhydroxy-3,5-dibromo-4-methoxybenzoic acid, etc. phenol derivatives,
α-naphthol, β-naphthol, 4-methoxy-1-
naphthol, 2,3-hydroxynaphthalene, 2,3-
Sodium dihydroxynaphthalene-6-sulfonate, 2-
Hydroxy-3-propylmorpholinonaphthoic acid, 2-
Examples include naphthol derivatives such as hydroxyl 3-naphtho-0-toluicide and 2-hydroxy-3-naphthoic acid morpholinopropylamide, but are of course not limited to these. Anything that can act as a kagura is optionally applied.

In the present invention, a thermofusible substance is applied to the thermosensitive coloring layer as necessary in order to enhance its high-speed coloring property. Examples of the thermofusible substance in this case include the following.

Alcohol derivatives such as 2-tribromoethanol, 2,2-dimethyltrimethylene glycol, l,2-cyclohexanediol, acid derivatives such as malonic acid, mertaric acid, maleic acid, methylmaleic acid, and animals such as beeswax and shellac wax. waxes, vegetable waxes such as carnauba wax, mineral waxes such as montan wax,
Petroleum waxes such as paraffin wax and microcrystalline wax, other synthetic waxes such as polyhydric alcohol esters of higher fatty acids, higher amines, higher amides, condensates of fatty acids and amines, condensates of aromatics and amines, synthetic paraffins, Chlorinated paraffin, metal salts of higher fatty acids, higher linear glycols, dialkyl 3,4-epoxyhexahydrophthalate, N-alkylcarbamoylbenzene, etc.

The thermofusible substance used in the present invention preferably has a melting point or softening point in the range of 50 to 250°C.

If the melting point or softening point is less than 50°C, the shelf life of the product tends to decrease, and these thermofusible substances used in 250 are It is used in an amount of 2 to 30 parts by weight, preferably 5 to 10 parts by weight, per 1 part by weight of the diazo compound. If this density is less than the above range, the color development will be insufficient and the resulting product will be unsuitable as a recording material for high-speed recording. In the case of the present invention, it is particularly preferable to use 5 parts by weight or more for high-speed output recording such as facsimile. On the other hand, if the amount added is too large, blurring of the image may occur during color development by heating, which is undesirable. Therefore, in the case of the present invention, it is preferable to maintain the amount of the thermofusible substance added within the above range. If the thermosensitive coloring layer has a laminated structure of two or more layers, the thermofusible substance may be added to at least one of the layers.

Further, in the present invention, the heat-sensitive coloring layer may further contain acidic substances, basic substances, fillers, and other substances as auxiliary components, if necessary.

Acidic substance: An acidic substance is added as necessary to prevent a coupling reaction and for storage stability, and examples thereof include the following.

Tartaric acid, citric acid, boric acid, lactic acid, gluconic acid, sulfuric acid, etc.

Basic substance: A basic substance is added as necessary to cause a coupling reaction during heating, and examples thereof include the following.

Caustic alkalis and alkali carbonates such as sodium hydroxide, calcium hydroxide, potassium carbonate, etc.

Substances that generate basicity when heated include urea, thiourea and their derivatives, alkali salts of trichloroacetic acid, ammonium chloride/ammonium sulfate, and ammonium citrate.

Filler: A filler is added to improve the matching property to a thermal head when heating is performed by a thermal head, and examples of such fillers include the following.

Organic and inorganic solid particles such as styrene resin particles, urea-formalin condensate resin particles, aluminum hydroxide, magnesium hydroxide, calcium carbonate, titanium, talc, kaolin, silica, and alumina.

As other auxiliary ingredients, zinc chloride, zinc sulfate, sodium citrate, guanidine sulfate, calcium gluconate, sorbitol, saccharose, etc. are used to suppress or assist color development.

In order to obtain the heat-sensitive recording material according to the present invention, a layer-forming coating solution is prepared by dissolving or dispersing each of the above-mentioned components in an appropriate solvent, and this coating solution is applied to paper, synthetic paper, plastic film, metal laminate, etc. A coupler layer and a diazo compound layer are coated on a conventional support to form a single layer or a laminated layer and dried.

In the present invention, the solvent for dissolving or dispersing the layer-forming components is appropriately selected depending on the properties of the layer to be formed and the purpose of formation. Examples of such solvents include water, an aqueous solvent prepared by dissolving an organic solvent in water, benzene, toluene, xylene, n-hexane, and the like.

Examples include nonpolar organic solvents such as n-hebutane, cyclohexane, and kerosene, and polar organic solvents such as methyl isobutyl ketone, methyl cellosolve, acetone, methyl ethyl ketone, and dimethyl ether.

According to a preferred embodiment of the present invention, a structure is provided in which a coupler layer and a nanoazo compound layer are laminated. In this case, in the diazo compound layer formed on the support,
The coupler or diazo compound contained in each layer may be present in the layer in either a discontinuous or continuous particle state.

In order to obtain a product with balanced thermochromic properties and shelf life, it is preferred that one of the diazo compound layer and the coupler layer be a discontinuous particle layer, and the other be a continuous particle layer. If both of them are discontinuous particle layers, thermal coloring properties tend to decrease, while if both of them are continuous particle layers, thermal coloring properties tend to become too large and long-term storage stability tends to decrease.

The heat-sensitive recording material of the present invention can be advantageously applied in various fields of heat-sensitive recording, particularly as output recording paper for facsimile machines, electronic computers, etc. that require high-speed recording, and in the case of the present invention, the surface The characters and images recorded in
After the image is formed by heating, it can be fixed by decomposing the unreacted diazo compound with light.

Further, the heat-sensitive recording material of the present invention utilizes its fixing properties,
It can be applied to recording and creating necessary information for securities, gift certificates, admission tickets, certificates, slips, etc.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 ■ Liquid stearamide 10/
/water
57〃The above composition was dispersed for 24 hours using a ball mill to prepare a solid liquid.

(2) Liquid naphthol AS-D 3 parts by weight N-octadecylcarbamoylbenzene
10 1 ammonium chloride
10 〃Maleic anhydride-ammonia aqueous solution,
30# (20%) Water 47 parts by weight The above composition was dispersed for 24 hours using a ball mill to prepare a liquid (9).

Prison liquid stearamide 10
Ammonium chloride 10
〃water
47〃The above composition was dispersed for 24 hours using a ball mill to prepare a prison liquid.

(2) Liquid naphthol AS 3
Part by weight Stearamide
10 Ammonium chloride
10 Silica
3 Water
44 parts by weight of the above composition was dispersed for 24 hours using a ball mill to prepare a liquid (b).

For comparison of bacterial liquids, a polyvinyl alcohol (1(1) solution) was used instead of an ammonia solution of maleic anhydride-butadiene copolymer in the solid liquid.

■For liquid comparison, polyvinyl alcohol (10%) was used instead of maleic anhydride-ammonia aqueous solution in (6) liquid.
A solution was used.

For comparison, a polyvinyl alcohol-y (tol) solution was used in place of the ammonia solution of maleic anhydride-butadiene copolymer in the prison liquid.

After applying and drying each of the above-mentioned liquids on the surface of high-quality paper (approximately 5077 m'') to form a first layer with an adhesion amount of 5 fP/rrL'' (solid content), magnesium stearate was added on top of the first layer. 〃
Polystyrene resin (-mi800) 2tt
MW' Hexane 91〃
A photosensitive solution consisting of the following was previously dispersed for 24 hours using a ball mill, applied, and dried to provide a photosensitive layer having a coating weight of IP/m''.

The heat-sensitive recording material thus obtained was used as a sample, and after printing in Cut mode using a Rifax 303 (manufactured by Ricoh), it was completely exposed and fixed using a Ricobee 7 Ystart type (manufactured by Ricoh). These materials did not develop color even when reheated, and the images did not disappear when exposed to organic solvents.

Next, the heat-sensitive recording material obtained above was tested for color density and background color fading. The results are shown in Table-1.

In addition, the color density is the solid print density in Rifax 3030G-■ mode using a Macbeth densitometer (RD-514).
It was measured with In addition, as for the fading property, the samples were irradiated with white light for 5 hours using a commercially available fade meter (manufactured by Suga Test Instruments), and the background density was measured before and after the test. It can be confirmed that the fading property is improved.

Example 2 A liquid obtained by mixing the photosensitive liquid of Example 1 with liquid A (using hexane solvent instead of water) shown in Example 1 was coated on high-quality paper (approx.
The mixture was coated on a surface of 7 m'' and dried to obtain a heat-sensitive recording material having a single-layer heat-sensitive color layer.

Regarding this heat-sensitive recording material, a background color fading test was conducted in the same manner as in Example 1, and the result was a pre-test density of 0.12 and a post-test density of 0.23! Obtained.

Patent applicant Ricoh Co., Ltd. Agent: Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) A diazo in which a thermosensitive coloring layer containing a diazo compound and a coupler is provided on a support, wherein the thermosensitive coloring layer uses a maleic anhydride resin as at least a part of the binder. thermosensitive recording material.