JPS6174885A - Two-color developable thermal recording paper - Google Patents

Abstract

PURPOSE:To obtain two-color thermal recording paper improved in the color separability to heating temp., excellent in the storage stability of an image and having thermal sensitivity, by successively providing a first color forming layer, a second color forming layer and a coupler layer on a support. CONSTITUTION:A first color forming layer 1 is provided on a support 4 in such a state that a coupler 6, that is, a phenolic substance and/or acidic substance and a colorless or light-colored leuco dye 5 capable of forming a color through the reaction of said coupler at the time of heating are dispersed throughout a binder as main components. A second color forming layer 2 comprises a composition wherein a colorless or light-colored leuco dye 5 capable of forming a color different from that of the leuco dye of the first color forming layer 1 is dispersed in the binder as a main component. A coupler layer 3 is formed by dispersing the coupler 6, that is, the phenolic substance and/or acidic substance and a sensitizer 7 are dispersed in the binder. When this thermal transfer recording paper is developed at low temp., the sensitizer and coupler in the coupler layer are melted by heating and acted on the leuco dye in the second color forming layer to instantaneously dissolve and develop said leuco dye while the second color forming layer inhibits heat conductance to the first color forming layer and, therefore, a sharp image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (First Field of Use in Vegetables) The present invention relates to a two-color thermosensitive recording material that develops two different colors at different heating temperatures.

(Conventional 1' branch technique) In recent years, there have been attempts to record monochromatic images using chemical or physical changes in substances caused by thermal energy.
Because it has advantages over other recording methods, such as being less likely to generate noise and not requiring development and fixing, it can be used not only for recording books, documents, etc., but also for recording equipment, computer output printers, Records of facsimile machines, automatic ticket vending machines, etc. (this is being applied).

Furthermore, Uchika also attempted to obtain multicolored five-color records by utilizing differences in heating temperature and thermal energy. '
Various multicolor thermosensitive recording materials have been proposed according to L.

An example of a multicolor thermosensitive recording material is a recording material in which two different coloring components that develop different tones at different coloring temperatures are mixed in the same thermosensitive coloring layer (Japanese Patent Publication No. 49-69).
(see publication), depending on the coloring temperature of the coloring component,
They were used separately for the high-temperature thermosensitive coloring layer and the low-temperature thermosensitive coloring layer, respectively. A recording material in which layers are sequentially stacked on a support (
JP-A No. 48-15540 (3), between the heat-sensitive coloring buds at the pan temperature and low temperature, the color development in the corresponding low-temperature heat-sensitive coloring layer is performed except for the image forming area on one surface of the high-temperature heat-sensitive coloring layer. In contrast, three-layer grooved recording materials provided with a color erasing layer exhibiting a color erasing effect (see Japanese Patent Laid-Open No. 48-8251), or so-called color erasing-coloring systems using an organic base (specially Kosho 5
1-29024).

However, all of these multicolor thermosensitive recording materials have several drawbacks and are not fully satisfactory.

(Problems to be solved by the invention) In any of the multicolor thermosensitive recording materials up to this point,
When coloring is carried out at a low temperature, it is unavoidable that the coloring is caused by force regardless of the high-temperature coloring layer, and the disadvantage is that the color separation property with respect to heating temperature is poor. In addition, the recording material 2 provided with a color erasing layer (agent) and the recording material having a color erasing/coloring system have poor image storage stability, which poses a practical problem. In addition, as thermal recording speeds have increased in recent years, it has become necessary to smooth the surface of the recording paper and make the heat-sensitive material finer in order to ensure close contact between the recording head and the recording paper. As a result, fogging (background stains) is likely to occur on the surface of the thermal recording paper.

The object of the present invention is to provide a two-color thermal recording paper which overcomes all of the drawbacks of conventional materials, has clear images, has excellent storage stability, and has high heat sensitivity.

(Means for Solving the Problems) The two-color thermosensitive recording paper of the present invention has a first coloring layer that develops color at a relatively high temperature, a second coloring layer that develops a color at a relatively low temperature, which are formed on a support. This first color-developing layer consists of a phenolic substance and/or an acidic substance and a colorless or light-colored leuco dye, each separately dispersed in a binder. The second coloring layer is made of a colorless or light-colored leuco dye dispersed in a binder.
The developer layer is composed of a phenolic substance and/or an acidic substance and a sensitizer dispersed in a binder.

A conceptual cross-sectional view of the thermal recording paper of the present invention is shown in FIG.

The first color-developing layer (1) is provided on the support (4), and contains a color developer (6), that is, a phenolic substance and/or an acidic substance, which reacts with this color developer during heating to form a color. It is formed by dispersing a colorless to light-colored leuco dye (5) in a binder. The second coloring layer (2) is made of a colorless to light-colored leuco dye (5) that can develop a color different from the leuco dye of the first coloring layer (1) and is dispersed in a binder. It consists of a color developer layer (three layers, a color developer (
6, i.e. phenolic substances and/or acidic substances;
It is formed by dispersing the sensitizer (7) in a binder.

Examples of colorless to flame-colored leuco dyes used in the present invention include triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based leuco dyes, such as crystal hiolet ratatone 3.3- Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide 3.3-Bis(p-dimethylaminophenyl)phthalide 3.3-Bis(p-dimethylaminophenyl)-6-dimethylaminophenyl 3.3 -bis(p-dimethylaminophenyl)-6-talolophthalide 3-CN-p-tolyl-N-ethylamine)-6-methyl-7-(N-phenylamino)fluoran 3-diethylamino-7,8-be/sufluorane 3-citalohex/ruamino-6-methylfluoran 3-diethylamino-6-methyl-7-chlorofluoranopensoyl leucometherene blue 6'-taloro 87
-Medoxypenozoindolinopyrillospiran 6'-Bromo-87-Medoxybenzoindolinopyrillospiran 2-(3,6-bis(diethylamino)-9-(0-taloloanilino)xanthyl]utatum benzoate And so on.

As the leuco dye of the second coloring layer of the present invention, a dye that develops a color such as red or green in the evening can be used, and as the leuco dye of the first coloring layer, a leuco dye that is combined with the leuco dye of the second coloring layer can be used. In this case, a leuco dye of any tone can be used as long as it has a color similar to black G. Naturally, a black coloring dye can also be used.

The phenolic substance used as a color developer is α-
Naphthol, β-naphtho-nov, 4-t-phterphenol, 4-t-octylphenol, 4-phenylphenol, 2.2'-bis(p-hydroxyphenyl)flopa/, 2.2'-his( p-hydroquinphenyl)phthane, 4,4'-7talohek/litendiphenonou, 2,2'-bis(2°5-dibromo-4-hydroxyphenyl)furopano, 4,4'-isopropyl Redenbis(2-t-butylphenol L2,2'-methylenebis(4-chlorophenol), be/zyl p-hydroquinobenzoate, etc.) are present.

Acidic substances include boric acid, oxalic acid, maleic acid, tartaric acid, Tae/acid, succinic acid, benzoic acid, stearic acid,
gallic acid, salicylic acid, 4-okino-2-naphthoic acid,
0-oxybenzoic acid [night, 2-oxo-p-toluic acid,
Sensitizers such as m-oxybenzoic acid and 4-ox7phthalic acid (all known substances conventionally used for this purpose can be used;
Terephthalic acid esters, aromatic ring derivatives, piphenyl compound derivatives, aromatic-amide compound derivatives, etc. can be used. For example, stearic acid amide, dibenzyl terephthalate, dibenzyl terephthalate, benzyl naphthyl ether, benzyl naphthyl methyl ether,
Examples include be/zylpiphenyl, naphthylbiphenyl, be/zenesulfonamide, and the like.

After separately grinding and dispersing these components together with bonding rows and surfactants into fine particles using a dispersing machine such as a ball mill, attritor, or sand mill, they are mixed into a support such as paper, film, or synthetic paper according to the recipe. A first coloring layer, a second coloring layer, and a color developer layer are coated on top in this order to form a two-color thermosensitive recording paper. Fillers, brighteners, wetting agents, lubricants, sensitizers, etc. can be added to each layer as necessary.Also, if chemical resistance is required, the coating surface of the developer layer A chemical resistant layer may also be applied.

(Operations and Effects) The heat-sensitive recording paper of the present invention solves the problems of color separation, storage, annotation, and dirt, which have been the problems described above. However, it exhibits even higher thermal sensitivity.

When the heat-sensitive recording paper of the present invention is colored at a low temperature, for example, 70-80°C, the sensitizer and color developer in the color developer layer are melted by heating and the second color is formed. The leuco dye in the layer acts to instantly dissolve and develop color, while the second coloring layer inhibits heat transfer to the first coloring layer, resulting in a clear image. The temperature can be changed by using a sensitizer or a color developer having a different melting point, and it is possible to sufficiently cope with high-speed thermal recording.

In the case of heating at a high temperature, for example, 100°C or higher, the thermal engineering energy must be sufficiently transmitted to the first coloring layer without being inhibited by the formation of the second coloring layer. Color development takes place.If necessary, a sensitizer may be included in the first color development layer to adjust the sensitivity.

The thermosensitive recording paper of the present invention does not require a decoloring agent, so there is no problem with storage stability.

Further, since there is no substance having a color developing effect in the second color forming layer components, it is possible to obtain a thermosensitive recording paper with high whiteness and no sporadic color development.

The effects of the present invention include the following points: (1) A two-color thermosensitive recording paper with excellent two-way color separation property can be obtained.

(2) Since the dye layer and the color developer layer are separated, a thermal recording paper with no background stains and high whiteness can be obtained.

(3) Since no decolorizing agent is used, a two-color thermosensitive recording paper with excellent storage stability can be obtained.

Example Examples are shown below.

Implementation (Siri l.

The mixture consisting of the missing ingredients was milled using a ball mill (trowel) for 1 minute at ILq4 [A] to produce 3 g of CB'.

[, D 10% polyvinyl alcohol 50.9 Water, liquid water 35
i [B] Liquid composition 10% - Polyvinyl alcohol 50.9 Water 1 @ Keisui 3
50.9 Also, a mixture consisting of the following proportions was ground in a sand mill to produce [CD, [D'3 liquids].

[CD Iki 6 and Sei 2, 2-His(p-Hito'oki'/100
,9 Phenyl 2-propa/10%-Polyvinyl alcohol 50.9 Bath liquid water 350
I [D] Liquid composition p-be/diru biphenyl 100I water
350g then [B
] Solution 30.9 and [C"J solution 60.9 were mixed and stirred with 10 g of 45% SBR Latintas and 10 y of water to prepare the first coloring layer coating solution. The coating was applied using a Mayer bar such that the dry coating amount was approximately 39/m2.On the coated paper obtained, CA>a 30
g, 20% polyvinyl alcohol aqueous solution 20I, water 1
A second coloring layer was formed by applying a first coloring layer coating solution prepared by mixing and stirring 0.9 and 0.9 to a dry coating amount of about 2 coats/m2.

After calendering this coated paper, [CD liquid 30.
9 Cf) J'H30F with 55% lucium carbonate dispersion Ti, 1op, 21% zinc stearate dispersion 3112
A color developer layer coating solution obtained by mixing 111 parts of 0% polyvinyl alcohol aqueous solution and 10 parts of water was applied at a dry coating rate of approximately 2.9/m.
A two-color thermosensitive recording paper was obtained by coating, drying, and further applying a carrier/dar. Using a 7mm tester made by Facility, the voltage was set to 1.9Vi and the current conduction time was recorded at 1.5m and 8gC [where - is 1#]
A clear blue record was obtained.

Further, recording was performed by changing the current application time by 3.8 m5ecI (a clear black recording was obtained when the voltage was negative).

2- Using benzyl p-hydroxyquinobenzoate as a substitute for CD solution (2,2-bis(p-hydroquinphenyl) 70 ropan) in Example 1 C″J Kei, and the rest are 1- as in Example 1+S1, and two-color heat-sensitive tomography.
I got a replacement.

This two-color thermosensitive recording was recorded under the conditions of low voltage 16V and energization time 1.8m5ec, and the clear H color 5
A personal record was obtained.

-1. When the current application time was changed by 4m5eci and recorded, a clear black record was obtained.

Example a CD of Example 2] Using dibenzyl terephthalate [D
A two-color thermosensitive recording paper was obtained using the same procedure as in Example 2, except for the liquid '3' and the liquid '1-'.

When recording was carried out on this two-color thermosensitive recording paper under the same conditions as in Example 2, clear blue and black recorded images were obtained.

Example 3 was added to [D'3 of Example 3 in the first coloring layer head fabric solution of Example 3
Two colors were prepared in the same manner as in Example 3, except that 10.9 g of the liquid was added to form the first coloring layer coating liquid, and the dry coating amount of the second coloring layer in Example 3 was changed to about 4.5 i/m2. A colored thermosensitive recording paper was obtained.

This two-color thermosensitive recording paper was applied at a voltage of 16 V' and for a duration of 1.
When recording was carried out under the conditions of 8 m5 ec, a clear blue record was obtained. When recording was carried out with the energization time limited to 3.5 m5ec, a clear black record was obtained.

Comparative Example 1゜The first coloring layer coating solution of Example 1 was dried in a pot weight of about 3 g/m.
2 (10 g each of Solution A, D and 20 g of Solution C from Example 1, and the same additives, polyvinyl alcohol, and water solution as in Example 1, were coated on a well-coated paper. Added to form a second coloring layer coating solution, dry coating amount is approximately 3g/rn2
Apply one coat, dry, and apply a rough calender to create a two-color thermosensitive record.

When recording was carried out in the same manner as in Example 1, it was possible to obtain two distinct colors.

As a comparative example, when 20 liters of liquid [C] was added to the coating solution for the second coloring layer of Example 1, the color development was positive, and it was not possible to obtain a practically usable result.

Table 1 shows the recording results and storage stability of Examples and Comparative Examples (40
℃-90%Rn 1 day) test results are shown below.

Whiteness ◎ Particularly good ○ Good X Poor xx Particularly bad

[Brief explanation of drawings]

FIG. 1 is a conceptual cross-sectional view of the two-color thermosensitive recording paper of the present invention. 1 First coloring layer 2 Second coloring layer 3 Color developer layer 4 Support 5 Leuco dye 6 Color developer 7 Sensitizer patent applicant Oji Paper Co., Ltd. (1 other person) Figure 1

Claims (1)

[Claims] On the support, a phenolic substance and/or an acidic substance,
A first color-forming layer containing a colorless or light-colored leuco dye that can react with the phenolic substance and/or acidic substance to form a color when heated is provided, and further thereon, a color tone of the first color-forming layer is provided. A second coloring layer containing the same leuco dye as described above that develops a different color, and a color developer layer containing a phenolic substance and/or an acidic substance and a sensitizer as constituents are provided in this order. A two-color thermal recording paper that is characterized by: