JPS59150792A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a multicolor image high in color separation, by a method wherein an intermediate layer comprising a trichloroacetate is provided between heat-sensitive color forming layer, in a multicolor thermal recording material wherein a plurality of heat-sensitive color forming layers comprising a leuco dye as a main constituent are laminated. CONSTITUTION:A plurality of heat-sensitive color forming layers capable of forming colors of different tones are sequentially laminated on a base such as a paper, a synthetic paper or a resin film, with an intermediate layer comprising a trichloroacetate as a main constituent intermediately provided between the color forming layers. An alkali metal salt of trichloroacetic acid such as sodium trichloroacetate, potassium trichloroacetate or lithium trichloroacetate or the like is used as the trichloroacetate, in such a quantity as to substantially neutralize the color developer contained in the upper, low-temperature color forming layer. A binder used in the color forming layers and the intermediate layer may be polyvinyl alcohol, methoxy cellulose or the like which is conventionally used.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a multicolor heat-sensitive recording material, and the details are different/ζ
The present invention relates to a multicolor heat-sensitive material in which a plurality of heat-sensitive coloring layers are laminated to develop different colors depending on the heating temperature.

[Prior art]

A thermosensitive recording material is a material in which a thermosensitive coloring layer capable of forming 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.

These conventional heat-sensitive recording materials include a colorless or light-colored leuco dye (color-forming main agent) having a lactone ring, a lactam ring, a spiropyran ring, etc. in the heat-sensitive coloring layer, which reacts with the leuco dye during heating to develop color. Those containing a color developer (color development aid) are often used because they have a clear color tone and less smearing phenomenon.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying drawings, documents, etc., but also for recording the output of various types of information and measuring equipment such as computers, facsimiles, and telecommunications. However, depending on the purpose of recording, in order to display particularly necessary data or numbers more clearly, it is possible to record by changing the color of that part (display color) from the color of other parts. Of course, it is desirable to be able to do so. - In order to meet these demands, much research and development is being carried out everywhere, and several multicolor sensitive thermal recording materials have been proposed. However, when testing the multicolor heat-sensitive recording materials that have been reported so far, there were problems with color separation, such as color bleed.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems found in the prior art and to provide a multicolor thermal recording material that can produce multicolor images with improved color separation.

〔composition〕

According to the present invention, in a multicolor thermosensitive recording phase in which a plurality of heat-sensitive coloring layers each containing a leuco dye and a color developer as main components are superimposed, an intermediate layer containing trichloroacetate as a main component is provided between the heat-sensitive coloring layers. A multicolor heat-sensitive recording material is provided.

4 = The inventive multicolor heat-sensitive recording material consists of a support such as paper, synthetic paper, resin film, etc., and a heat-sensitive coloring layer with a number of different color tones, with trichloroacetate as the main component in the middle. It has a structure in which the layers are sequentially laminated with an intermediate layer interposed between them, and by printing at different heating temperatures, a multicolor image of two colors, three colors, etc. is formed depending on the number of heat-sensitive coloring layers. be able to. In this case, a stack of heat-sensitive coloring layers Itli! The first place goes to 11j, which has a higher heat-sensitive temperature and is closer to the support.
This is the first order.

The intermediate layer containing trichloroacetate as a main component used in the present invention exhibits the effect of improving color separation of multicolor images. That is, when heating printing from the surface of the multicolor thermosensitive recording material of the present invention, if the heating is performed at a low temperature, the low temperature thermosensitive coloring layer on the surface selectively develops color; When the heating is performed at a temperature higher than that for coloring the high temperature thermosensitive coloring layer located below the low temperature thermosensitive coloring layer (on the support side), the high temperature thermosensitive coloring layer develops color. In this case, in the present invention, an intermediate layer containing trichloroacetate is provided, and when this intermediate layer is heated to a high temperature, the trichloroacetate contained therein decomposes and becomes alkaline. During heating,
Due to heat transfer from the surface part to the support (n11), melting contact between the low-temperature thermosensitive coloring layer and the intermediate layer first occurs, and as a result, color development of the low-temperature thermosensitive coloring layer is inhibited by the alkali action of the intermediate layer, and then high temperature thermosensitive coloring occurs. Color development occurs in the layer. Therefore, in the case of the present invention, when heated at high temperature, the effect of the intermediate layer is
Color development in the low-temperature heat-sensitive coloring layer is suppressed, and only the high-temperature heat-sensitive coloring layer can be selectively colored, making it possible to obtain a multicolor image with good color separation.

If no intermediate layer is used, both the low-temperature thermosensitive coloring layer and the high-temperature thermosensitive coloring layer will develop color when heated to high temperatures, making it impossible to obtain a multicolor image with good color separation.

The trichloroacetate used as the intermediate layer component in the present invention is neutral under normal conditions and is very stable, so it does not have any particular adverse effect on the shelf life of the product. However, this trichloroacetate is used at high temperatures (usually 1
When heated to 30° C. or higher, the carboxyl group is decomposed and becomes alkaline. The decomposition temperature in this case varies depending on the alkaline component forming the trichloroacetate. Specific examples of the 11 trichloroacetic acid products preferably applied in the present invention include alkali metal salts of trichloroacetic acid such as sodium trichloroacetate, potassium trichloroacetate, and lithium trichloroacetate.

The trichloroacetate contained in this intermediate layer should be present in an amount sufficient to substantially neutralize the color developer contained in the low-temperature heat-sensitive color forming layer that is the upper layer.

The leuco dyes used in the present invention include, for example, triphenylmethane-based, fluoran-based, phenothiazine-based,
Leuco bodies such as auramine and spiropyran,
Representative examples of these include, for example, 3.3-bis(p-)methylaminophenyl)=6-
dimethylaminophthalide 3, a-bis(p-dimethylaminophenyl)phthalide 3.3-bis(p=+dimethylaminophenyl)-6-
dimethylaminophenyl 3,3-bis(p-)methylaminophenyl)-6-
Chlorophthalide 3- (N-p-tolyl-N-ethylamino)-6-methyl-7-(N-phenylamino)fluoran 3-, Sol-6'-chloro-8'-methoxy~inzoindolinobirilospirane 2-[3,6'-bis(noethylamine)-9-(0-
Examples include lactam benzoate.

As for the leuco dye, it is preferable to use a leuco dye that develops a color such as red or green in the evening as a low-temperature thermosensitive coloring layer near the surface (upper thermosensitive coloring layer). On the other hand, as the main coloring agent in the high temperature thermosensitive coloring layer (lower thermosensitive coloring layer) closer to the support,
Leuco dye that can develop a color that is black or close to black, or
Any leuco dye that can develop a color tone different from that of the upper thermosensitive coloring layer can be used.

The color developer used in the present invention is an electron-accepting substance such as a phenolic compound, an organic acid, or a derivative thereof. For example, α-naphthol, β-naphthol, 4-naphthol,
1erl-butylphenol, 4-', 1-octylphenol, 4-phenylphenol, 2127-bis(p-hydroxyphenyl)pron1.2.2'-
Bis(p-hydroxyphenyl)butane 1.4.4'-
Cyclohexylidene diphenol, 2,2'-bis(2
,5-dibromo-4-hydroxyphenyl)pro/8-one, 4',4'-isozolobylidene bis(2-1ert-
butylphenol), 2,2'-methylenebis(1-chlorophenol), and phenolic compounds such as
In addition, oxalic acid, maleic acid, tartaric acid, citric acid, phosphoric acid, benzoic acid, stearic acid, gallic acid, salicylic acid,
4-oxy-2-naphthoic acid 1.0-oxybenzoic acid,
2-ogine-p-toluic acid, l11-oxybenzoic acid
, 4-oxyphthalic acid, benol p-hydroxybenzoate, or derivatives thereof.

Conventional binders are used for the heat-sensitive coloring layer and the intermediate layer, such as polyvinyl alcohol, methoxycellulose, hydroxycellulose, carboxymethylcellulose, carboxy/ethylcellulose, polyvinylpyrrolidine, H9 lyacrylamide, and polyacrylic. Examples include acids, starches, and gelatin. In addition, in combination with these water-soluble resins, for example, styrene-citadiene copolymer, vinyl chloride-vinyl acetate copolymer? Latexes such as polyvinyl acetate, polyacrylic ester, and polymethacrylic ester such as polyzotyl methacrylate may also be used. Furthermore, silica, magnesia, talc, calcium carbonate, parium sulfate! 1. It is desirable to improve the matching property with the print head by adding fine powder such as urea-formalin resin or styrene resin. When coating and forming a thermosensitive coloring layer, antifoaming agents, wetting agents (surfactants),
□Waxes, softening point regulators, etc. can be added to improve coatability and thermal response.

Actually, in order to prepare the multicolor heat-sensitive recording material of the present invention, a leuco dye and a color developer are separately added together with a binder and other additives.
After pulverizing and dispersing into fine particles using a dispersing machine such as a sail mill, attritor, or sand mill, these are mixed to prepare each heat-sensitive coloring layer forming solution, and this is used to form several heat-sensitive coloring layers on a support. They may be laminated with an intervening intermediate layer containing IJ dichloroate.

〔effect〕

The multicolor heat-sensitive recording material of the present invention has an intermediate layer containing trichloroacetate interposed between each sensitive and color-forming layer.
A multicolor image with good color separation can be formed.

〔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.

The component compositions of liquids A to Gi shown below are as follows.

[Liquid A]

10% hydroxyethyl cellulose water 'fB liquid 150/
/water
200//[Liquid B] 3-diethynochemino-6-methyl-7-chloro 150
￥＄Fluorane lO% Hydroxyethyl Cell Self-Soluble in #15
0 parts water
2°. 7゜ [0 liquid] ・Q Lahydroki 7 benzoic acid benzyl ester 12
0 parts lO% hydroxyethyl cellulose-': water soluble'/I
t 120 tt water
160//[1) Liquid] Bisphenol A 120 people 1×1
0% aqueous ethyl cellulose solution 120 u water
160'/[1 (#:] 5% methyl cellulose aqueous solution 8011 water
. 40.7 [F solution] 4-7 Togincarpo nil sprout cudecylben 8
゜icB Zuami I・ゝ5% methylcellulose water distillate 80
//water
240//aluminum carbonate
80 parts zinc stearate 4011
5% methyl cellulose 40
1/Wed 1
240//Example 1 20 parts of the above liquid A, 60 parts of liquid I, 30 parts of a 10% polyvinyl alcohol aqueous solution, and 90 parts of water were mixed and stirred for 44' to form the first layer (high temperature coloring layer). Make a liquid, apply it on high-quality paper (standard basis weight 52 y 7 m2) with a wire parr, dry it, and get a dry weight of about 4.5 t/m2.
A first thermosensitive coloring layer (high temperature coloring layer) was formed. This first
On the heat-sensitive coloring layer, 10 parts of sodium trichloroacetate,
Mix and stir 20 parts of a 10% polyvinyl alcohol aqueous solution and 70 parts of water. The intermediate layer solution was applied with a wire paper and dried to form an intermediate layer of about 0.6 f/7n2. Next, 20 parts of liquid 3, 60 parts of liquid C, 80 parts of liquid G, 40 parts of 10% polyvinyl alcohol aqueous solution, and 50 parts of water.
A second layer of low-temperature heat-sensitive coloring layer forming liquid obtained by mixing and stirring the liquid was applied with a wire spar and dried to a dry coating weight of about 2.
5g/? A second thermosensitive coloring layer (low-temperature coloring layer) of 7Z2 was formed, and a two-color sensitive i recording material system was created. Next, this is calendered and the smoothness is Beck smoothness 600~8
Surface treatment was performed so that the time was 0.00 seconds.

Example 2 In Example 1, sodium trichloroacetate↓mlO part,
25 parts of liquid F, 25 parts of 10% polyvinyl alcohol aqueous solution, and 40 parts of water were mixed and stirred for 41 minutes, and the obtained intermediate layer liquid was applied with a wire spar and dried to give a dry coating weight of about 0, 397 m.
A two-color thermal gain was obtained in exactly the same manner as in Example 1, except that the intermediate layer No. 2 was formed.

Example 3 A first thermosensitive coloring layer was formed in the same manner as in Example 1. The intermediate layer forming solution of Example 2 was applied on the first heat-sensitive coloring layer in a dry amount of about 0.8 g/? An intermediate layer was formed by coating and drying with n2. Next, 20 parts of liquid B, 60 parts of liquid I), 5 ONS of liquid 1
10 liquid 40 parts, 10% polyvinyl alcohol aqueous solution 50 parts
A second heat-sensitive coloring layer forming liquid obtained by mixing and stirring 50 parts of water and 50 parts of water was applied with a wire parlor and dried to give a dry coating weight of about 2.0. ? A 7 m2 second heat-sensitive coloring layer was formed to produce a two-color heat-sensitive recording material. Next, apply this to a calender to obtain a smoothness of 600 to 80 in Bekk smoothness.
The surface was treated so that the time was 0 seconds.

Comparative Example 1 A two-color heat-sensitive recording material was prepared in the same manner as in Example 1 except that the intermediate layer was not provided.

A two-color thermosensitive recording material was prepared in the same manner as in Example 3 except that 1. the companion layer was not provided.

Each of the heat-sensitive recording materials obtained above was recorded with an amplitude of 40.0 mm using a two-color recorder (manufactured by Watanabe Sokki Co., Ltd., two-color Suzuz coder) equipped with a thick-film resistor-type thermal pen. Record a mm triangular wave,
Check its color separation and color mixing properties.

The results are shown in Table 1, and it was confirmed that those using the intermediate layer of the present invention had good color separation and were able to prevent color mixing. Furthermore, when we investigated the storage stability of images and backgrounds of the multicolor heat-sensitive recording materials of the present invention, no deterioration was observed due to the provision of the intermediate layer.

It was a black color with a lot of color, and the color separation from the red color was poor compared to the examples, and the clarity was poor.

Patent applicant Ricoh Co., Ltd. −Representative Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) In a multicolor thermosensitive recording material in which a plurality of heat-sensitive color-forming layers containing a leuco dye and a color developer as main components are stacked, an intermediate layer containing trichloroacetate as a main component is provided between the heat-sensitive color-forming layers. A multicolor heat-sensitive recording material characterized by: