JPS591295A - Multicolor heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To contrive to improve color separation, ground fogging, head matching property or the like, by a method wherein a base with a filler-containing polymer resin layer provided on its surface is used, and an intermediate layer of a water-soluble polymer is provided between a plurality of heat-sensitive color forming layers laminated on the base. CONSTITUTION:A polymer resin layer containing an inorganic or organic filler such as silica, magnesia or aluminum stearate is provided on the surface of an ordinary base in an amount of 0.5-10g/m<2>. An emulsion-type alkyd resin, a styrene/butadiene copolymer or the like may be used as a polymer resin. A low- temperature color forming layer comprising a leuco dye and a color developer as main constituents and a high-temperature color forming layer are laminated on the base, in which case the intermediate layer comprising a water-soluble polymer such as polyvinyl alcohol or methoxy cellulose is provided between the upper layer and the lower layer, in the amount of 0.5-7g/m<2> in an usual case.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multicolor heat-sensitive recording material, and more particularly to a multicolor heat-sensitive material in which a plurality of heat-sensitive coloring layers that develop different colors at different heating temperatures are laminated.

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, lactam ring, spiropyran ring, etc. in the heat-sensitive coloring layer, and a color developer that develops color by reacting with this leuco dye when heated. Agent (color development aid)
Those containing the above are widely used because they have a clear color tone 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 also for recording various types of information such as electronic computers, facsimiles, telex machines, and output records of measuring machines. It is used in various fields, but 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.

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. However, when we tried the multicolor heat-sensitive recording materials that have been reported so far, we found that
There are problems with color separation such as color mixing and bleeding, and there are also problems with background fog during storage, image stability liquid capri, and head matching due to energy control of the heating element. It became clear that there was something left.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor heat-sensitive recording material that solves the above-mentioned problems and allows high-quality multicolor images to be obtained.

That is, the present invention provides a multicolor heat-sensitive recording material in which a plurality of heat-sensitive coloring layers mainly composed of a leuco dye and a color developer therefor are laminated on a support, and each heat-sensitive coloring layer is made of a water-soluble polymer. The object of the present invention is to provide a multicolor heat-sensitive recording material, which is separated by an intermediate layer and uses a support having a polymer resin layer containing an inorganic or organic filler formed on its surface.

In the heat-sensitive recording material of the present invention, the low-temperature coloring layer (upper layer) and the high-temperature coloring layer (lower layer) are separated by providing an intermediate layer;
The intermediate layer in this case is formed using a water-soluble polymer. Examples of this water-soluble polymer include polyvinyl alcohol, methoxycellulose, hydroxycellulose,
Examples include carboxymethylcellulose, 3-carboxyethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, and gelatin.

In the case of the present invention, it is preferable to use a material having a somewhat high softening point (1501Z' or higher). Further, auxiliary components used in this type of heat-sensitive recording material, such as inorganic or organic fillers, image stabilizers, decolorizers, sensitizers, etc., can be added to this intermediate layer, if necessary.

The amount of the intermediate layer deposited is usually preferably in the range of 0.5 to 7 g/m2.

In the present invention, the support contains an inorganic or organic filler that forms an undercoat layer for the heat-sensitive coloring layer on the surface of a normal support (paper, synthetic paper, resin film, etc.). A material with a polymer resin layer is used.

As the polymer resin in this case, a polymer resin having a lower softening point than that used for the intermediate layer or a hydrophobic resin having poor permeability into paper is preferably used. For example, preferred examples include emulsion type alkyd resins, styrene/butadiene copolymers, vinyl chloride/vinyl acetate copolymers, polyvinyl acetates, polyacrylic esters, polymethacrylic esters such as polybutyl methacrylate, and low molecular weight Examples include polyethylene. The resin layer provided on this support has a coating weight of 0.5 to 10 g/m2.
It is preferable to set it within the range of .

Note that the above-mentioned inorganic or organic fillers include silica,
Magnesia, talc, calcium carbonate, barium sulfate,
Fine powder of aluminum stearate, aluminum hydroxide, urea-formalin resin, styrene resin, etc., kaolin, titanium oxide, zinc oxide, alumina, silica, calcium chloride, clay, styrene-methacrylate copolymer fine powder, calcium carbonate organic acids, or fine powders of resin-coated modified products.

In the multicolor heat-sensitive recording material of the present invention, a resin layer containing an inorganic or organic filler is provided as an undercoat layer on the lower surface of the high-temperature coloring layer, so that the thermal sensitivity of the high-temperature coloring layer is improved, and the high-temperature coloring layer is improved. Since the intermediate layer is provided between the layer and the low-temperature color-forming layer thereon, the color-forming properties of the high-temperature color-forming layer are controlled and bleeding and color mixing during color development are prevented. That is, the multicolor heat-sensitive material of the present invention has good high-temperature color development at high speeds and improved brown color separation.

As the leuco dye used in the present invention, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based leuco dyes are preferably used. Specific examples of these leuco dyes are shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide 3,3 2s(p-dimethylaminophenyl) = 6-
cyphtylaminophthalide (also known as crystal violet lactone) 3,3 e -His(p-cyphthylaminophenyl)phthalide 3-cyclohexylamino-6-chlorofluoran 3-(N,N-diethylamino)-5-methyl-'1-
(N,N-dibenzylamino)fluoran 3-dimethylamino-5,7-cyphthylfluoran 3-diethylamino-7-methylfluoran 3-diethylamine-7,8-benzfluoran 3-diethylamino-6-methyl- 7-Chlorfluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 2i'N-(3'-')IJ fluoromethylphenyl)
amine)-6-ethylaminofluorane 2-(3,6
-Bis(diethylamino)-9-(0-chloroanilino)xantyl)benzoic acid lactam 3-diethylamino-? -(o-chloroanilino)fluoran 3-dibutylamino-7-(o-chloroanilino)fluoran 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluoran 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran 3- (2'-hydroxy-4'-dimethylaminophenyl) -3-(2'-methoxy- 5'-Chlorphenyl)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-57
-Methylphenyl)phthalide As the main coloring agent, it is preferable to use a leuco dye that develops blue, red, green, etc. as a heat-sensitive coloring layer near the surface (upper heat-sensitive coloring layer).

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 the following phenolic dyes. Examples include substances, inorganic acidic substances, organic acidic substances, and salts thereof.

Phenolic substances; 3.5-xylenol, thymol, p-tert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4 -tcrt-octylcatechol, 4,4-sec-butylidenephenol, 2,2'-dihydroxydiphenyl, 2,2-
Methylenebis(4-methyl-6-jerj-butylphenol), 2,2-bis(4-hydroxyphenyl)propane, 4゜4-impropylidene-bis(2-ter
t-butylphenol), 4.4-see-butylidene diphenol, hyrogallol, phloroglucin, phloroglucincarboxylic acid, 4-tert-octylphenol, 4-phenylphenol, 2,2-bis(p-hydroxyphenyl)butane 1 4+ 4'-cyclohexylidene diphenol, 212-bis(2+ s 7
From-4-hydroxyphenyl)propane, 4.4'
-inpropylidenepis (2-jcrt-butylphenol), 2,2'-methylenebis(4-chlorophenol), etc.

Acidic substances or salts thereof; benzoic acid, gallic acid, salicylic acid, zinc salicylate, 1
-Hydroxy-2-naphthoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, benzyl p-hydroxybenzoate, 2-hydroxy-p-)ruylic acid, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid,
4-oxycyphthalic acid, boric acid, etc.

In the present invention, the binder to be applied to the thermosensitive coloring layer is as follows:
Commonly used water-soluble resins are preferably used, such as polyvinyl alcohol, methoxycellulose, hydroxycellulose, carboxymethylcellulose, carboxyethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, and the like. In addition, in combination with these water-soluble resins, latexes such as styrene-butadiene copolymers, vinyl chloride-vinyl acetate copolymers, polyvinyl acetates, polyacrylic esters, and polymethacrylic esters such as polybutyl methacrylate can be used in combination with these water-soluble resins. can also be used.

The heat-sensitive coloring layer further contains silica, magnesia, talc,
It is desirable to improve the clarity of colored images by adding fine powders of calcium carbonate, barium sulfate, aluminum stearate, urea-formalin resin, styrene resin, and the like.

When forming a twisted heat-sensitive coloring layer on a support or an intermediate layer, antifoaming agents, wetting agents (surfactants), waxes, softening point regulators, etc. are added to the heat-sensitive coloring layer forming liquid. hand,
Coating properties and thermal response can be improved.

In order to actually produce the multicolor heat-sensitive recording material of the present invention, the leuco dye and color developer are separately pulverized and dispersed together with a binder and other additives into fine particles using a dispersing machine such as a ball mill, attritor, or sand mill. A heat-sensitive color forming layer forming solution is prepared by mixing these components, and a plurality of heat-sensitive color forming layers may be formed on a support using this liquid.

According to the multicolor heat-sensitive recording material thus obtained, the objects of the present invention can be fully achieved.

Next, examples and comparative examples will be shown.

(Liquid A) 5% hydroxyethyl cellulose aqueous solution 1
50g water
A mixture consisting of 450 g was ground in a magnetic ball mill for 24 hours to prepare Solution A.

(Liquid B) 5% hydroxyethyl cellulose aqueous solution 1
50g water
A mixture consisting of 450 g was ground in a magnetic ball mill for 24 hours to prepare Solution B.

(Liquid C) Parabenzoic acid benzyl ester 1
20g 5% hydroxyethylcellulose aqueous solution
120g water
A mixture consisting of 360 g was ground with an attritor for 3 hours to prepare Solution C.

(D) Liquid bisphenol 120 g 5% hydroxyethyl cellulose aqueous solution 1
20g water
A mixture consisting of 360g was mixed with an attritor 3
A solution D was prepared by grinding for a time.

5% methylcellulose aqueous solution
80g water
Mixture consisting of 240g was mixed with attritor 3
A solution E was prepared by grinding for a time.

(F solution) Monomethyl terephthalic acid stearylamide
80g 5% methylcellulose aqueous solution
80g water
A mixture consisting of 240 g was ground with an attritor for 3 hours to prepare Solution F.

Example 1 A styrene-butidiene copolymer emulsion and a styrene-methacrylate copolymer fine powder dispersion were mixed and stirred with water to prepare an undercoat layer forming liquid, which was coated on high-quality paper (standard basis weight 53 g/m2). It was coated on top with a wire bar and dried to form an undercoat layer of 2-3 g/m2.

On this undercoat layer, 20g of liquid A, 80g of liquid
% oxidized starch aqueous solution and 30 g of water were mixed and stirred,
Pour the first layer of thermosensitive coloring layer forming liquid, and spread it on high-quality paper (
Apply with a wire bar on the standard basis weight 53 g/m2),
It was dried to form a first thermosensitive coloring layer with a weight of about 5 g/m2.

A 5% aqueous methyl cellulose solution was applied onto the first thermosensitive coloring layer using a wire bar and dried to form an intermediate layer of about t, F) g/m2.

After forming the intermediate layer, 20 g of liquid B, 3 og of liquid 0, 120 g of oxidized starch aqueous solution, and aog of water were mixed and stirred to form a heat-sensitive coloring layer forming liquid for the uppermost layer, which was applied onto the intermediate layer with a wire bar and dried. A two-color heat-sensitive recording material was prepared by forming an uppermost color-forming layer having a weight of about 2.0 g/m2. Subsequently, this was subjected to calendering to perform a surface treatment such that the smoothness became Bekk smoothness of 600 seconds.

Example 2 An undercoat layer was formed in the same manner as in Example 1, and then 20 g of liquid A, sog of liquid D, 40 g of liquid F, 20 g of a 20% oxidized starch aqueous solution, and 30 g of water were mixed and stirred to form the first layer. Prepare a thermosensitive coloring layer forming liquid and apply it to high-quality paper (standard basis weight 5
Apply 3g/m with a wire bar and dry to about 5.
A first thermosensitive coloring layer of 5 g/m2 was formed.

A 5% aqueous methyl cellulose solution was applied onto the first thermosensitive coloring layer using a wire bar and dried to form an intermediate layer of about 1.5 g/m2.

After forming the intermediate layer, 20 g of the above liquid B, ]) liquid sog, 4 liquid E
0g, 20g of oxidized starch aqueous solution and 30g of water are mixed and stirred, the uppermost layer of heat-sensitive coloring layer forming liquid is scooped out, coated on the middle layer with a wire bar, and dried to form a final layer of approximately 2.0g/m2. An upper coloring layer was formed to produce a two-color heat-sensitive recording material.

Subsequently, this was subjected to a calender to perform a surface treatment such that the smoothness became Bekk's smoothness of 600 to 800 seconds.

Example 3 In place of the 5% methylcellulose aqueous solution used for the intermediate layer, 1
A two-color heat-sensitive recording material was obtained in the same manner as in Example 1, except that a 0% modified polyvinyl alcohol aqueous solution was coated with a wire bar to give a weight of 1.5 g/m 2 when dried.

Comparative Example 1 20g of A liquid, 80g of O liquid and 20g of 20% oxidized starch aqueous solution
and water aog are mixed and stirred to make a first layer thermosensitive coloring layer forming liquid, and this is coated on high-quality paper (standard basis weight 53 g/m2).
Apply on top with a wire bar and dry to about 5.5g/m2
A first thermosensitive coloring layer was formed.

A 5% aqueous methylcellulose solution was applied onto the first thermosensitive coloring layer using a wire bar and dried to form an intermediate layer having a weight of about 1.5 g/m2.

After forming the intermediate layer, mix and stir 20 g of liquid B, sog of O liquid, 20 g of oxidized starch aqueous solution, and 30 g of water to prepare a thermosensitive coloring layer forming liquid for the uppermost layer, apply it on the intermediate layer with a wire bar, and dry. A two-color heat-sensitive recording material was prepared by forming an uppermost color-forming layer of about 2.0 g/m2 and having a Bekk smoothness of 600.
The surface was treated by calendering for ~800 seconds.

Tests were conducted on these heat-sensitive recording materials in terms of storage stability, liquid dynamic color development, color separation, etc., and it was found that the product of the present invention had good color development at high speeds in the first color development layer (lower layer black color development), and The color separation was good. Due to the effect of the intermediate layer, there was no bleeding or color mixing at low speeds.

Table 1 shows the results of recording a triangular wave with an amplitude of 4011 using a two-color recorder (two-color servo coder manufactured by Watanabe Sokki Co., Ltd.) with a thick-film resistor-type thermal pellet, and examining its two-color separation and color development. Shown below.

Table-1 Note) O is good for both two-color separation and color development properties ×
Δ is defective. Normally, as shown in the coating-1 above, the product of the present invention shows two separate colors without color mixing even under low-speed and high-speed conditions, but in contrast, the product of the comparative example has no undercoat. Since there was no layer, the two-color separation property and color development were poor.

Claims (1)

[Claims] (1) In a multicolor heat-sensitive recording material in which a plurality of heat-sensitive coloring layers mainly composed of a leuco dye and a color developer for the leuco dye are laminated on a support, each heat-sensitive coloring layer is formed by an intermediate layer of a water-soluble polymer. 1. A multicolor heat-sensitive recording material characterized by using a material having a polymeric resin layer containing an inorganic or organic filler formed on the surface as a support.