JPS59192592A - Two-color heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To improve color separation and prevent colors from being mixed into a developed color image formed at a high temperature, by a method wherein an intermediate layer comprising an encapsulated material of at least one selected from the group consisting of an adipic acid derivative, an azelaic acid derivative and a sebacic acid derivative is intermediately provided between a high-temperature color forming layer and a low-temperature color forming layer as a decolorizing layer. CONSTITUTION:The high-temperature color forming layer and a low-temperature color forming layer different from each other in color forming temperature and formed color tone are provided on a base, while the intermediate layer comprising an encapsulated material of at least one selected from the group consisting of an adipic acid derivative, an azelaic acid derivative and a sebacic acid derivative is intermediately provided between the color forming layers. Organic acid derivatives are used as organic plasticizers, in which leuco dyes and color developers easily dissolve, so that the organic plasticizer functions as a favorable decolorizing agent for a color forming system consisting of a leuco dye and a color developer. A wall forming agent for encapsulation may be protein, plant rubber, a cellulose, a synthetic polymer, a glass or the like, and the structure of capsules may be one of monolayer-3-layer structure. Aliphatic and aromatic esters of an organic acid are preferably used as the organic plasticizer. In the concrete, an adipic acid derivative or a sebacic acid derivative is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a leuco two-color heat-sensitive recording material.

[Prior art] A thermosensitive recording material is a material in which a thermosensitive coloring layer that can form a colored image by heating is provided on a support such as paper, and a thermal printer equipped with a thermal head is widely used for heating. It is being

These conventional heat-sensitive recording materials include a colorless or light-colored leuco dye (color-forming main agent) having rough 1-rings, lactam rings, spiropyran rings, etc. in the heat-sensitive coloring layer, and coloring occurs when the leuco dye reacts with this leuco dye when heated. Those containing a color developer (color development aid) are widely used because they have clear color tones and cause less fogging.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying books, documents, etc., but are also used in various fields such as computer, facsimile, telex, and other fields for recording various types of information and measuring equipment. However, depending on the purpose of recording, in order to display particularly necessary data and numbers more clearly, the coloring of that part (
It goes without saying that it is desirable to be able to record with the display color (displayed color) different from the developed color of other parts.

In order to meet such demands, much research and development is being carried out everywhere, and several multicolor thermosensitive recording materials have been proposed accordingly. For example, Tokuko Sho 49-2
No. 7708 and Japanese Unexamined Patent Publication No. 15540/1989 propose a multi-layered support in which a heat-sensitive coloring layer containing a leuco dye and a phenolic substance as main components is provided. However, these conventional multicolor heat-sensitive recording materials have the disadvantage that the resulting multicolor images have poor color separation, and high-temperature colored images cause color mixture and become unclear.

[Objective] An object of the present invention is to provide a leuco-based two-color thermosensitive recording material that has improved color separation properties and does not cause color mixture in high-temperature colored images.

[Constitution] According to the present invention, a high-temperature color-forming layer and a low-temperature color-forming layer each having a different coloring temperature and producing different color tones are formed on a support, and an adipic acid derivative is encapsulated between the coloring layers; A leuco-based two-color thermosensitive recording material is provided, which is characterized in that it is provided with an intermediate layer containing an encapsulated product of at least one selected from azelaic acid derivatives and sebacic acid derivatives.

゛ Original □,,) 2-color heat-sensitive and border materials, 3 and 5
, A. Decoloring an intermediate layer containing at least one encapsulated substance selected from encapsulated adipic acid derivatives, azelaic acid derivatives, and sebacic acid derivatives between the high-temperature coloring layer and the low-temperature coloring layer. It is characterized by being interposed as a layer.

The above organic acid derivatives used in the present invention are all used as organic plasticizers, and leuco dyes and color developers are well dissolved in these organic acid plasticizers, and the color forming system consisting of leuco dyes and color developers is It acts as a good decolorizer. However, since these organic plasticizers are liquid at room temperature, they could not be used directly as decolorizing agents. In the present invention, these organic plasticizers are applied in the form of encapsulates. As the encapsulation method in this case, various conventionally known methods are applied, including chemical methods (e.g. interfacial polymerization method), physicochemical methods (e.g. submerged drying method), or mechanical methods (e.g. spray drying method). ), but any method may be used as long as it can preserve the liquid within the solid wall for a long time. As an encapsulating wall agent,
Various conventionally known materials are used, such as proteins, vegetable rubbers, celluloses, synthetic polymers (thermoplastic resins), and glass. A double or triple structure can be adopted. As the organic plasticizer, aliphatic and aromatic esters of the organic acids are preferably used, and specific examples thereof are as follows.

Adipic acid derivatives di-n-butyl adipate, di(2-ethylhexyl) adipate, diisodecyl adipate, di(n-octyl or n-decyl)adipate 1-, benzyl-n-
Butyl adipate, benzyl octyl adipate, di(butoxy, ethoxy or ethyl) adipate, etc.

Azelaic acid derivatives di-(2-ethylhexyl) azelate, diisooctyl azelate, di-2-ethylhexyl-4-thioazelate, di-n-hexyl azelate, and the like.

Sebacic acid derivatives di-n-butyl sebacate, di(2-ethylhexyl) sebacate, di-C7-9 alcohol sebacate, etc.

=4= Next, a specific example of a process for manufacturing an encapsulated product using the plasticizer as a raw material will be shown. In this case, the manufacturing process consists of (i) a manufacturing process for the uncured encapsulated product, and (ii) a curing process for the uncured encapsulated product.

(i) Production of uncured encapsulated product A plasticizer, which is a core material, is emulsified and dispersed in an aqueous gelatin solution at 40°C containing sodium dodecyl sulfate as a surfactant using an ultrasonic emulsifier.

The particle size of the plasticizer is measured by a light scattering method, and the plasticizer is emulsified and dispersed to maintain a constant particle size. Next, this emulsion is quickly dispersed in an aqueous gum arabic solution at 40°C to bring the whole to IQ. When the PL+ of the system is lowered to below the isoelectric point of gelatin with a 2.5% acetic acid aqueous solution while stirring, coacervation occurs, and a coacervate phase consisting of gelatin and gum arabic precipitates around the plasticizer droplets, forming a film. to form uncured microcapsules.

(ii) Curing treatment of uncured capsules After the uncured microcapsules produced above were set at 20°C below the setting point of the gelatin, 1 mQ of a 37% formalin aqueous solution was added to the system, and then the pl+ When the temperature is raised to 8°5 with a 2.5% aqueous solution of sodium carbonate, the gelatin hardens and becomes insoluble in water. After centrifuging this capsule dispersion,
The obtained capsule thriller is dried by spray drying to obtain a cured capsule in which the desired plasticizer is encapsulated.

The two-color thermosensitive recording material of the present invention has a structure in which a high-temperature coloring layer and a low-temperature coloring layer are laminated on a support with a layer containing a microcapsule of the plasticizer interposed therebetween. In this case, the high temperature coloring layer is generally provided as a lower layer of the low temperature coloring layer. Further, the high-temperature coloring layer and the low-temperature coloring layer each contain a leuco dye and a color developer.

The leuco dye used in the present invention may be used alone or in combination.''
The leuco dyes used in this type of heat-sensitive material can be used as a mixture, and for example, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, Leuco compounds of spiropyran-based dyes are preferably used. Specific examples of such leuco dyes include:
For example, the following can be mentioned.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as Crystal Violet I-
lactone), 3.3-bisCP-dimethylaminophenyl)-6-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorphthalide, 3.3-bis(p-dibutylaminophenyl) phthalide , 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-ph-ly-N-ethylamino)-6-me7
- thyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-1~lifluoromethylphenyl)amino)-6-ethylamino Fluorane, 2-(3
, 6-bis(diethylamino)9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-1-lichloromethylanilino)fluoran, 3-diethylamino-7-( o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N- diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, 8-benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylosvirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2 '-Hydroxy-4'-dimethylaminophenyl')-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide,3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide,3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-( N-benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(O-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-( α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-5-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

Further, as the color developer used in the present invention, various electron-accepting substances that react with the leuco dye and develop color when heated are used, and specific examples thereof include phenol as shown below. Examples include acidic substances, organic or inorganic acidic substances, and salts thereof.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-diterL
-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis( 2,6-dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4゜4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2 , 6-dimethimephenol),
4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-5ee-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methylphenol) ), /I-tert-butylphenol,
4-phenylphenol, 4-hydroxy11-sidiphenoxide, α-naphthol, β-naphthol,
3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2-thiobis(4,6
-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycin, phloroglycincarboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol)
, 2,2'-methylenebis(4-methyl-6-tert
-butylphenol), 2゜2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, p
-Benzyl hydroxybenzoate, p-hydroxybenzoate-P-chlorobenzyl, p-hydroxybenzoic acid-0
-chlorobenzyl, p-methylbenzyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate,
Benzoic acid, zinc salicylate, 1-hydroxy-2-naph)-diacid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-6-naph 1-dioxyacid, 4-hydroxydiphenylsulfone, 4-hydroxy -4'-ri-12-lorodiphenyl sulfone, bis(4-hydroxyphenyl) sulfide, 2-hydroxy-P-1-ruylic acid,
Zinc 3,5-t,ert-butylsalicylate, 3.
tin 5-di-tert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, cellulose, hydroxyethylcellulose, carboxymethylcellulose,
Cellulose derivatives such as methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone,
Acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, poly Acrylamide, sodium alginate, gelatin,
In addition to water-soluble polymers such as casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate Latexes such as copolymers, styrene/butadiene/acrylic copolymers, etc. can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances ( or lubricant), etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. In addition, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned.
Examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts, as well as various waxes,
Condensate of aromatic carboxylic acid and amine, benzoic acid phenyl ester, higher linear glycol, 3,4-epoxy-
Examples include dialkyl hexahydrophthalate, higher carbons, and other heat-fusible organic compounds having a melting point of about 50 to 200°C.

[Effect] The two-color thermosensitive recording material of the present invention has the above-mentioned structure, and when coloring is performed at a high temperature, the plasticizer is released from the microcapsules, acts on the coloring reaction system of the low-temperature coloring layer, and forms a low-temperature coloring image. Make it fade. Therefore, the two-color image formed by the heat-sensitive recording material of the present invention has good color separation and provides a clear low-temperature color image and a high/111i color image.

[Example] Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Examples 1 to 3 Uncured microcapsules containing a plasticizer were formed according to the microencapsulation method (coacervation method) shown above, and this was hardened to form a plasticizer with a particle size of 1 to 3μ. Microcapsules 15- were obtained.

Next, Solutions A to F having the following component compositions were prepared.

Liquid A Plasticizer microcapsules shown in Table 1 below 15 parts Methyl cellulose 5% aqueous solution 15! I water
2o! ! This composition was mixed with a stirrer to obtain a liquid A.

B liquid crystal violet lactone 10 parts hydroxyethyl cellulose 10% aqueous solution 10! ! water 3
o/I This composition was dispersed in a ball mill for 20 hours to obtain liquid B.

Solution C 3-diethylamino-7-chlorofluorane 10 parts Hydroxyethylcellulose 10% aqueous solution 101I Water
301116- This composition was dispersed in a ball mill for 15 hours to obtain liquid C.

D-liquid calcium carbonate 15 parts Methylcellulose 5% aqueous solution 15II Water
20I! This composition was dispersed in a ball mill for 10 hours to obtain Liquid D.

B liquid stearic acid amide 10 parts Methyl cellulose 5% aqueous solution 101! water
, 30/+ This composition was dispersed in a ball mill for 15 hours to obtain liquid B.

F liquid Bisphenol A 15 parts Hydroxymethylcellulose 10% aqueous solution 15n Water 2
07/This composition was dispersed in a ball mill for 15 hours to obtain liquid F.

A high-temperature coloring liquid, an intermediate liquid, and a low-temperature coloring liquid having the following component compositions were prepared using the A-F liquids.

High temperature coloring liquid C liquid lO part F liquid 201! D liquid
15I/Polyvinyl alcohol (PVA) 1.0% aqueous solution 1011 Intermediate solution A, '° part PVA
10% aqueous solution 15! I Low temperature coloring solution B solution 10 parts F solution
2QuE liquid
20u PVAIO% aqueous solution 10u Next, basis weight 50g/
After applying and drying a high-temperature colored N7 colored liquid at a dry coating weight of 4.5 g/m2 on a commercially available high-quality paper of 2 m2, a high-temperature coloring layer was formed.
An intermediate layer (erasing layer) was provided by applying and drying the intermediate layer, and a low-temperature coloring liquid was further applied thereon at a drying weight of 3.5 g/m and drying to provide a low-temperature coloring layer. Next, the coated surface was supercalendered to obtain a two-color heat-sensitive recording material of the present invention.

Table 1 Comparative Example Using the high-temperature coloring liquid and low-temperature coloring liquid shown in Examples 1 to 3 above, first apply the high-temperature coloring liquid to commercially available high-quality paper with a basis weight of 50 g/m2 at a dry coating amount of 4.5 g/m2. After coating and drying with +n2, apply low temperature coloring liquid to the - with a dry coating amount of 3.5g/m
2 and dried. Next, this coated surface was subjected to supercalender treatment to obtain a two-color heat-sensitive recording material for comparison.

The two-color thermal recording paper obtained as described above was measured using a thermal inclinometer (manufactured by Toyo Seiki Co., Ltd.) 19-1 with a built-in thermal head at a head temperature of 70 to 150°C, a crimping time of 1 second, and a crimping pressure of 2 J/am. The color tone, color separation, etc. of the low-temperature and high-temperature colored images were tested by printing under various conditions.As a result, the comparative example caused color mixing and only gave an unclear high-temperature colored image, whereas the product of the present invention did not cause color mixing. It gave clear low-temperature and high-temperature colored images.

Patent applicant Rico Co., Ltd. - Agent Patent attorney Toshiaki Ikeura 20 -

Claims (1)

[Claims] (1) An adipic acid derivative, an azelaic acid derivative, and a high-temperature color-forming layer and a low-temperature color-forming layer, each having a different coloring temperature and developing a different color tone, encapsulated between the coloring layers on a support. A leuco-based two-color heat-sensitive recording material, characterized in that it is provided with an intermediate layer containing at least one encapsulated material selected from sebacic acid derivatives.