JPH074974B2 - Diazo thermosensitive recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a diazo thermosensitive recording medium having high thermal sensitivity and excellent photofixing sensitivity, and in particular, a ticket,
The thermal recording method is intended to be applied to applications such as commuter passes that require image storability.

(B) Conventional technology In recent years, the number of passengers such as passenger tickets and commuter tickets has increased remarkably in passenger transportation by rail. Therefore, it has been considered to sell cards such as passenger tickets automatically. It has reached the stage of practical application.

In addition, automatic sales of admission tickets for movie theaters, exhibition halls, etc. and dining tickets for dining halls are being considered, and some have reached the stage of practical application.

The electrophotographic method, the electrostatic recording method, and the general printing method have been conventionally adopted as the printing and recording methods for these applications, but there is a drawback that the apparatus is generally complicated and large, and the machine cost increases. is there. Further, there is a disadvantage that a consumable agent such as powder or liquid developer is required, and maintenance management accompanying it is complicated. Further, the conventional printing method has a drawback that semi-dry ink adheres to the hand and stains clothes.

On the other hand, the heat-sensitive recording method has the advantage that it is not so complicated in terms of equipment, rather it can be designed compactly and is maintenance-free, and since the thermal reaction takes place in the heat-sensitive layer, other base materials There is also an advantage that the abrasion resistance of the recorded image is excellent as compared with the method of directly printing on the above.

However, the thermochromic substances that have been conventionally used for the thermosensitive recording material include dye-based substances and metal chelate-based substances composed of a color former such as a leuco dye and a color developer such as a phenol compound. In the case of the heat-sensitive recording medium, if the print is erroneously heated after printing, the background may be colored to make the print unreadable, or the print may be tampered with after printing. Further, the commuter pass is usually stored in, for example, a leather wallet having a transparent window of polyvinyl chloride film, a commuter pass, etc., but the validity period of these is as long as 3 months or 6 months, during which the transparent window of polyvinyl chloride is provided. The disadvantage that the plasticizers contained in, such as dioctyl phthalate (DOP) and dioctyl adipate (DOA), penetrate into the thermosensitive coloring layer and erase the colored image in the printed area especially when the thermosensitive recording material is used for the leuco dye system. was there.

In order to overcome such a drawback, various attempts have been made to improve chemical resistance by providing an overcoat layer made of a polymer compound on the heat-sensitive recording layer even in the heat-sensitive recording body using the conventional leuco dye. In any case, if the image is heated by mistake because it cannot be fixed after heating and printing,
There was a drawback that the background became colored and the print became unreadable.

On the other hand, in the case of a diazo thermosensitive recording medium that utilizes the coupling reaction of a diazonium compound and a coupler compound,
Since the diazonium salt can be photolyzed by exposing after printing, it has the advantage that the non-printed portion can be fixed and the tampering resistance after printing is excellent. Further, the azo dye that is produced also has an advantage that it is generally superior in chemical resistance of an image as compared with a leuco dye.

(C) Problems to be Solved by the Invention Generally, it can be said that azo dyes are superior in chemical resistance to leuco dyes because they do not undergo decolorization or fading with chemicals such as plasticizers, and are superior in chemical resistance. Depending on the type, the generated azo dye is dissolved, so that the image bleeding or the azo dye is partially dissolved in a chemical, which may cause a decrease in the density of the image area, and a solution to this point has been demanded.

In order to solve such problems, various attempts have been made in diazo heat-sensitive recording materials, such as the use of carboxy-modified PVA as an overcoat agent in JP-A-60-162687 and JP-A-59-104994. Has been done.

However, the purpose of providing the overcoat layer on the diazo heat-sensitive layer as described above does not fully utilize the advantages of the azo dye, which is originally excellent in chemical resistance, and in order to form the overcoat layer also in the process. This is not preferable because it increases the number of steps.

On the other hand, as the thermal recording speed increases, higher thermal sensitivity is required.Therefore, the coating amount of the diazonium salt must be increased in order to increase the color density. Since it takes time and does not lead to the reduction of the ticket issuing time per sheet, it is required to improve the optical fixing sensitivity as well as the high thermal sensitivity.

(D) Means for Solving Problems The present invention intends to solve all the problems of the related art at once.

That is, a fine particle dispersion of a coupler compound, a color-forming aid and a color developer, and, if necessary, an inorganic or organic pigment added together with these dispersions in order to prevent sticking or sticking is used. Also scatters or absorbs a part of the light for decomposing the diazonium salt, which tends to cause a decrease in the photodecomposition efficiency of the diazonium salt. From the viewpoint of fixing sensitivity, the diazonium salt is coated with the fine particle dispersion described above. It is preferably located above the layer.

However, if only the water-soluble polymer compound is used as the binder material for the overcoat layer containing the diazonium salt,
Sufficient chemical resistance and water resistance cannot be obtained, and when a hydrophobic polymer compound is used as the binder material, chemical resistance and especially water resistance are further improved, but on the contrary, sticking due to poor heat resistance. Deteriorates the head matching property.

Therefore, it is preferable to use a water-soluble polymer compound and a hydrophobic polymer compound in combination as a binder material for a photosensitive layer and an overcoat layer containing a diazonium salt, and in particular, the hydrophobic polymer compound in the overcoat layer is water-soluble. It is preferable to add 5 to 50% by weight to the hydrophilic polymer compound.

That is, if the amount is 5% by weight or less, the chemical resistance and water resistance are unsatisfactory even if a commonly used water-proofing agent is added to the water-soluble polymer compound, and if it is 50% by weight or more, dust, sticking, etc. This causes deterioration of head matching.

(E) Action As the water-soluble polymer compound for forming the overcoat layer of the present invention, cornstarch, gum arabic, glue, gelatin, casein, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyacrylamide, carboxymethylstarch , Starch such as starch such as dialdehyde starch, or modified products and derivatives thereof, polyvinyl alcohol or modified products and derivatives thereof, polyvinylpyrrolidone, isobutylene-maleic anhydride copolymer, polyacrylic acid salt, styrene-maleic anhydride copolymer Things etc. are mentioned.

As the hydrophobic polymer compound used together with these water-soluble polymer compounds, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene rubber (=
SBR), methacrylate butadiene rubber (= MBR), nitrile butadiene rubber (= NBR), polymethyl methacrylate, polypropylene, polyacrylonitrile, synthetic resin emulsions such as acrylic acid ester, and the like,
These binder materials can be used alone or as a mixture.

Also, formalin, glyoxal, chrome alum, glutaraldehyde, melamine / formalin resin, urea /
It is also possible to use a water resistant agent that is usually used for a water-soluble polymer binder material such as formalin resin.

Further, in the overcoat layer of the present invention, if necessary, a pigment usually used in the field of thermal paper can be used, and specific examples thereof include kaolin, calcined kaolin, talc, wax,
Diatomaceous earth, styrene resin particles, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin filler, cellulose filler, aluminum oxide, and the like, but thermal heads such as dust and sticking. From the viewpoint of matching property, JP-A-53-118059, 54-25845, 54-1
18846, 54-118847 oil absorption as described in JIS K5101 it is desirable to use 80ml ~ 500ml / 100g oil-absorbing pigment in the measuring method specified, especially in the layer in direct contact with the thermal head, calcined kaolin, urea -It is desirable to use an oil-absorbing pigment having the above-mentioned oil absorption amount, such as formalin filler.

Other auxiliary components include zinc chloride, zinc sulfate, sodium citrate, guanidine thiourea sulfate, calcium gluconate, and sorbitol for color development suppression and color development assistance.
Sugars such as saccharose are used, and if necessary, an anti-UV agent or an antioxidant can be added, and waxes and metallic soaps can be used for the purpose of further improving sticking and color development sensitivity. .

Specific examples of the waxes include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide, lauryl amide, myristyl amide, hardened beef fatty acid amide, and palmitic acid amide. Examples thereof include oleic acid amide, acetamide, coconut fatty acid amide, methylol compounds of these fatty acid amides, methylene bis stearamide, ethylene bis stearamide, and higher fatty acid esters.

Examples of the metal soap include higher fatty acid polyvalent metal salts, that is, zinc stearate, aluminum stearate, calcium stearate, zinc oleate and the like.

As the diazonium salt used in the present invention, any of the compounds used in conventionally known diazo-type copying materials can be optionally used. For example, the following compounds can be particularly preferably used.

Specific examples include 4-N, N-dimethylaminobenzenediazonium chloride, 3-chloro-4-N, N-dimethylaminobenzenediazonium chloride, 4-N, N-diethylaminobenzenediazonium chloride, 2,5-diethoxy- 4-N, N-diethylaminobenzenediazonium chloride, 4-N-ethyl-N-hydroxyethylaminobenzenediazonium chloride, 4-N, N-diethoxyaminobenzenediazonium chloride, 4-phenylaminobenzenediazonium chloride, 4-N -(P
-Methoxyphenyl) -aminobenzenediazonium chloride, 4-morpholinobenzenediazonium chloride, 2,5-diethoxy-4-morpholinobenzenediazonium chloride, 4-oxazolidinobenzenediazonium chloride, 3-methyl-4-piperidino Examples thereof include benzenediazonium chloride, 4-ethylcapto-2,5-diethoxybenzenediazonium chloride, 4-tolylmercapto-2,5-diethoxybenzenediazonium chloride and 4-benzylmercapto-2,5-dimethoxybenzenediazonium chloride.

It is preferable that the diazonium salt is contained in an amount of 5 to 50% by weight based on the total amount of the binder components including the water-soluble polymer compound and the hydrophobic polymer compound in the overcoat layer.

That is, when the diazonium salt is contained in an amount of 50% by weight or more based on all the binder components in the overcoat layer, the chemical resistance of the color image is poor and the overcoat layer cannot serve as the overcoat layer. % Is less than 100%, it is not preferable because it causes a decrease in color developing sensitivity.

Further, an acid compound may be used in the overcoat layer for stabilizing the diazonium salt and preventing precoupling, but any organic or inorganic acid compound used in conventionally known diazo type copying materials may be used. It can be used, and specific examples thereof include tartaric acid, citric acid, boric acid, lactic acid, glycolic acid, phosphoric acid, trichloroacetic acid, dichloroacetic acid, cyanoacetic acid, oxalic acid, malonic acid, and maleic acid. used.

The weight ratio of these acid compounds to organic basic compounds is
It is preferably used within the range of 1.0% to 30%, and more preferably within the range of 5% to 15%.

As the coupler compound contained in the heat-sensitive layer of the present invention, any compound can be used as long as it is a compound capable of coupling with the above-mentioned diazonium salt. Examples of these compounds include phenol derivatives, oxynaphthalene derivatives, and compounds containing an active methylene group. Specific examples of these compounds include the following compounds.

(1) Phenol derivative Pyrocatechol Resorcin Phloroglysin Pyrogallol Metaaminophenol Paraaminophenol Diethylaminophenol N-lauryl-paraaminophenol N-acyl-metaaminophenol 3,3 ', 5-trihydroxydiphenyl 3,3'5,5' -Tetrahydroxydiphenyl α-resorcinic acid β-resorcinic acid γ-resorcinic acid phloroglucin carboxylic acid gallic acid diresorcin sulfide diresorcin sulfoxide 3,5-resorcinic acid ethanolamide 2,4-resorcinic acid ethanolamide 4-promresorcinol 4-chlororesocin 2-methylresorcin 3,3'-butylenedioxydiphenol 3,3 'ethylenedioxydiphenol bisphenol A (2) oxynaphthalene derivative 2,3-dihydroxyna Talene β-naphthol α-naphthol 1,6-dihydroxynaphthalene 2,3-dihydroxynaphthalene-6-sulfonic acid 2-naphthol-3,6-disulfonic acid 1,8-dihydroxynaphthalene-8-sulfonic acid 2-hydroxy-3 -Naphthoic acid-N-β-hydroxyethyl-amide 2-hydroxy-3-naphthoic acid-N, N, -bis β-hydroxyethyl amide 5- (paranitro) -benzamide-1-naphthol 1-naphthol-3- ( N-β-hydroxyethyl)-
Sulfone-amide 2-hydroxy-3-propylmorpholinonaphthoic acid 2-hydroxy-3-naphtho-0-toluidide 2-hydroxy-3-naphthoic acid morpholinopropylamide 2-hydroxy-3-naphthoic acid-4'-chloroanilide 2 -Hydroxy-3-naphthoic acid-5'-chloro-
2 ', 4'-di-methoxyanilide 2-hydroxy-3-naphthoic acid-2', 5'-dimethoxyanilide 2-hydroxy-3-naphthoic acid-2'-ethoxyanilide 2-hydroxy-3-naphthoic acid- 2'-Methoxyanilide 2-hydroxy-3-naphthoic acid-phenyl ester 2-hydroxy-3-naphthoic acid-4'-phenoxyanilide 2-hydroxy-3-naphthoic acid-4'-benzyloxyanilide 2-hydroxy- 3-naphthoic acid-4'-phenethyloxyanilide 2-hydroxy-3-naphthoic acid-2'-benzyloxyanilide 2-hydroxy-3-naphthoic acid-2 ', 5'-dimethylanilide 2-hydroxy-3- Naphthoic acid-4'-methoxyanilide (3) Compound containing active methylene group 1-phenyl-3-methyl-pyrazo (5) acetoacetic acid anilide 1-phenyl-3-carboxypyrazolone acetoacetic acid cyclohexyl amide acetoacetic acid benzyl amide cyanoacetanilide cyanoacetomorpholine 4-carboxy-acetoacetanilide These coupler compounds are ball milled and sand glider. It can be incorporated in the heat-sensitive layer as a fine particle dispersion having a particle size of 10 μm or less by using a dispersing means such as an attritor.

Further, the coupler compound may be used alone or in combination of two or more kinds to form a dye showing desired spectral absorption characteristics.

In addition, when dispersing, the coupler compound may be dispersed alone, but may be co-dispersed with an organic basic compound and, if necessary, other additives.

If the organic basic compound used as a developer is soluble in the water used as the solvent for the coating solution when applied to the support, the pH of the coating solution rises, causing fog on the background and deterioration of storage stability. Therefore, it is desirable that it exists as a discontinuous fine particle dispersion in the coating layer, and its solubility in water at 20 ° C is 1.0 g.
/ If the following is also good moisture and heat storage stability, aliphatic amines and pyrrolidine derivatives, imidazole derivatives, imidazoline derivatives, piperidine derivatives and the like can also be suitably used heterocyclic compounds, especially the following general formula [I] And [I
When the hydrophobic guanidine derivative of [I] is used as a color developer, it is possible to obtain a diazo fixing type thermosensitive recording medium which is excellent in storage preservability under high temperature and high humidity and excellent in image preservability which develops color with high sensitivity. Can be done. Also, the developer has a melting point of 100-170.
Those in the range of ° C can be particularly preferably used.

The developer may be dispersed alone by a dispersing means such as a ball mill, a sand grinder or an attritor, or may be co-dispersed with a coupler compound and optionally additives.

General formula [I] Or the general formula [II] [Wherein R ₁ , R ₂ , R ₃ R ₄ and R ₅ represent hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl, aralkyl, amino, alkylamino, acylamino, carbamoylamino, and a heterocyclic residue, R ₆ is lower alkylene, phenylene, naphthylene or (Wherein X represents lower alkylene SO ₂ , S ₂ , S, O, —NH— or a single bond), and the aryl group in the formula is a lower alkyl, alkoxy, nitro, acylamino, alkylamino group or halogen. Those having a selected substituent are also included.] Typical examples thereof are shown in Table 1, but the present invention is not limited thereto. In the table Represents a cyclohexyl group.

These guanidine derivatives shown above can be easily synthesized by a known method or a method similar thereto.

Also, as a sensitizer for improving color development sensitivity, the melting point is 90 to 150.
It is also possible to use a substance having a good compatibility with an organic basic compound, a coupler compound or the like when heated at a temperature of ° C.

Any of these substances may be used as long as they have good compatibility when heated, but in particular, a benzene ring in one molecule,
A substance having a naphthalene ring and also having a polar group such as an ether bond or a carbonyl group (ketone group, ester group) can be preferably used. Specific examples thereof include dimethyl terephthalate, dibenzyl terephthalate, 1-methoxynaphthalene, 1,4-diethoxynaphthalene, and benzyl ether of P-hydroxybenzoic acid benzyl ester.

These can be used alone as dispersed, but can also be used as co-dispersed with an organic basic compound, a coupler compound and the like.

(F) Examples Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 A coating solution for the heat-sensitive layer was prepared according to the following formulation, coated on a support so that the coating amount after drying was 5.0 g / m ² , and dried. The unit is parts by weight.

The liquids A and B were prepared by pulverizing and dispersing the following components for 48 hours in a ball mill.

A coating solution for an overcoat layer having the following composition was adjusted on the heat-sensitive layer so that the coating amount after drying was adjusted to 1.5 g / m ² , and the coating and drying were carried out to prepare a diazo heat-sensitive recording medium of the present invention. did.

Example 2 Instead of using 15 parts by weight of 40% SBR latex in Example 1, 40% styrene-acrylate emulsion 20
A diazo thermosensitive recording medium was prepared in the same manner as in Example 1 except that parts by weight were used.

Comparative Example 1 A diazo thermosensitive recording medium was prepared in the same manner as in Example 1 except that SBR latex was not added.

Comparative Example 2 A coating solution is prepared according to the following formulation, and the diazonium salt is coated on the support so that the coating amount of the dried diazonium salt is the same as in Example 1, and dried to prepare a diazo thermosensitive recording medium. The unit is parts by weight.

The liquids A and B were prepared by pulverizing and dispersing the following components for 48 hours in a ball mill.

The thus-obtained diazo thermosensitive recording medium was subjected to thermosensitive printing using a facsimile (Toshiba KD-4800), and then the diazonium salt was decomposed and fixed by exposing the whole surface to ultraviolet rays.

The print density obtained as described above is measured by a Macbeth densitometer (RD
-514) and the values are shown in Table-2.

Regarding the fixing sensitivity, Examples 1 and 2 and Comparative Examples 1 and 2
The value of the highest paper feed speed that can completely decompose the diazonium salt by the commercially available diazo copying machine (4 Shoshodo pd-521: 80W fluorescent lamps) prepared by the method (M / h).

Regarding the chemical resistance of the image of the diazo thermosensitive recording medium, after printing with a facsimile, the printing density and each drop of ethyl alcohol and dioctyl phthalate (DOP) were dropped on the printing section and the printing section was rubbed 10 times with gauze. The residual rate of the image density of was measured.

The above results are shown in Table 2 below.

(G) Effect of the invention As is clear from Table 2, in order to prevent fine particle dispersion or dust and sticking of coupler compounds, color-developing aids, color developers, etc. that scatter or absorb light for decomposing diazonium salts. By providing a photosensitive layer and overcoat layer containing a diazonium salt on a heat-sensitive layer containing an added inorganic or organic pigment, not only the fixing sensitivity and color developing sensitivity can be significantly improved, but also the overcoat layer By using a water-soluble polymer compound and a hydrophobic polymer compound together as a binder, a diazo thermosensitive recording medium having excellent chemical resistance could be obtained. Azo dyes have low solubility in solvents with relatively low polarity such as dioctyl phthalate (DOP) and are stable because they do not decolorize like leuco systems, but azo dyes against polar solvents such as ethyl alcohol. Since it has a high solubility, it was possible to obtain a diazo heat-sensitive recording material excellent in chemical resistance even with a polar solvent by using the constitution of the present invention.

Claims (3)

[Claims] 1. A heat-sensitive layer and a water-soluble polymer in which a coupler compound, a color-developing aid, and an organic basic compound which is melted by heat and exhibits a basic atmosphere as a fine particle dispersion are each contained on a support. A diazo thermosensitive recording medium comprising a compound and an overcoat layer containing a diazonium salt as a main component in order, wherein the overcoat layer further contains a hydrophobic polymer compound. 2. A diazo heat-sensitive recording material according to claim 1, wherein the hydrophobic polymer compound in the overcoat layer is contained in an amount of 5 to 50% by weight based on the water-soluble polymer compound. . 3. The diazo heat-sensitive recording material according to claim 1 or 2, wherein the hydrophobic organic basic compound is a hydrophobic guanidine derivative represented by the following general formula [I] or [II]. General formula [I] General formula (II) [Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ represent hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl, aralkyl, amino, alkylamino, acylamino, carbamoylamino, and a heterocyclic residue. , R ₆ is lower alkylene, phenylene, naphthylene or (Wherein X is a lower _{alkylene, SO 2, S 2, S} , O, -NH-
Or a single bond), and the aryl group in the formula includes those having a substituent selected from lower alkyl, alkoxy, nitro, acylamino, alkylamino group and halogen. ]