JPH01101187A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a high-reliability, high-sensitivity thermal recording material which is free from decoloring of a coloring portion and coloring of a ground portion even if brought into contact with a plasticizer, oil and water, by providing a protection layer mainly consisting of basic zirconium compound and water soluble resin having a given functional group on a thermal coloring layer. CONSTITUTION:A thermal coloring layer mainly containing leuco dye and developer is placed on a supporter and on which a protection layer consisting of basic zirconium compound and water soluble resin is provided. The water soluble resin contains at least one functional group selected from a group of carboxyl, hydroxyl, amino, amide, imino and imido groups. The basic zirconium compound is preferably zirconylammonium carbonate, the water soluble resin is, e.g., polyvinyl alcohol, starch and its derivative, methoxycellulose, polyacrylamide, casein, polyethylenimine and polyethylenamine. The weight ratio of basic zirconium compound to water soluble resin is preferably 1.5-0.1:1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, and particularly to a heat-sensitive recording material that has excellent image reliability and high sensitivity.

[Prior art]

In recent years, with the increase in the amount of information, and social demands such as resource saving, labor saving, and pollution-free production, various recording methods have been put into practical use and improved in the information recording field. Among them, thermal recording materials The thermal recording method uses (1) primary color development that does not require a developing process, (2) the hardware is simple and compact, and maintenance costs are low; (3) the sheet itself has a feel similar to that of plain paper. Due to its relatively low cost, it is widely used in computer output, medical measurement recorder fields, facsimile fields, printer fields, PO5
It has been put to practical use in travel labels, tickets for vending machines, etc. A heat-sensitive recording material used in such a method includes a heat-sensitive coloring layer containing a colorless or light-colored leuco dye having a lactone, lactam, or spiropyran ring and an acidic substance 1, such as an organic acid or a phenolic compound, on a support. (Special Publication No. 43-4160, No. 45-1)
No. 4039, various publications, etc.) are publicly known. However, the above-mentioned leuco-based heat-sensitive recording materials have the drawbacks of poor stability of recorded images and easy discoloration.
For example, there is a problem in which recorded images become discolored when they come into contact with oil or plasticizers (dioctyl phthalate, etc.) in plastic films, and solving this problem has become a major technical challenge for this type of recording material. There is.

Several methods have been proposed in the past to solve this problem, such as increasing the stability of the heat-sensitive coloring layer by incorporating a large amount of resin with good water and chemical resistance into the heat-sensitive coloring layer. In addition to those in which a heat-sensitive coloring layer contains a resin that hardens by heat or light to increase the stability of the heat-sensitive coloring layer, a protective layer is formed on the surface of the heat-sensitive coloring layer and the heat-sensitive coloring layer is cured with chemicals. There are also those that are protected from the effects of water.

The binder constituting this protective layer is a water-soluble polymer compound such as polyvinyl alcohol, starch, or those into which a functional group such as a carboxyl group is introduced, and a curing agent such as glyoxal, an epoxy compound, an isocyanate compound, or a methylol compound. Many combinations have been proposed.

However, these protective layers have the drawback that the crosslinking reaction is insufficient because they must be dried at a low temperature at which the heat-sensitive layer does not develop color, and that the protective layer tends to dissolve when immersed in water.

There are also proposals to use polystyrene or styrene/vinyltoluene copolymers dissolved in organic solvents, but these do not satisfy all chemical resistance such as plasticizer resistance and alcohol resistance. However, a protective layer that satisfies all the characteristics has not yet been obtained.

〔the purpose〕

An object of the present invention is to provide a highly reliable and highly sensitive heat-sensitive recording material that does not cause decoloring of colored areas or color development of background areas even when in contact with plasticizers, oil, water, etc.

〔composition〕

According to the present invention, in a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer as main components is provided on a support, a basic zirconium compound and a carboxyl group, a hydroxyl group, A heat-sensitive recording material is provided with a protective layer mainly composed of a water-soluble resin containing at least one functional group selected from the group consisting of an amino group, an amide group, an imino group, and an imide group. provided.

That is, the heat-sensitive recording material of the present invention has a heat-sensitive coloring layer containing a leuco dye and a color developer as main components on a support, and a protective layer containing a basic zirconium compound and the water-soluble resin as main components thereon. However, because of the above configuration, it is highly sensitive and highly reliable as it does not discolor the coloring area or develop color in the background area even if it comes into contact with plasticizers, oil, water, etc. Become.

It is well known that zirconium compounds, as stable and highly active crosslinking agents, are effective in stabilizing, insolubilizing, and curing emulsion resins, etc. However, when used as heat-sensitive recording materials, they have poor head matching properties. However, it has not yet been put into practical use due to its reliability and reliability. However, the present inventors particularly selected basic zirconium compounds among zirconium compounds as the protective layer of the heat-sensitive recording material, and selected basic zirconium compounds from the group consisting of carboxyl groups, hydroxyl groups, amino groups, amide groups, imino groups, and imido groups. It has been found that by using the present invention in combination with a water-soluble resin containing at least one selected functional group, a recording material with sufficient matching and high reliability can be obtained.

As the basic zirconium compound used in the protective layer of the present invention, zirconyl ammonium carbonate is particularly preferred. Further, the water-soluble resin used in the protective layer of the present invention is not necessarily limited to one type, and two or more types can be used in combination as necessary. Specific examples include polyvinyl alcohol, starch, etc. and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, polyvinylpyrrolidone.

Examples include acrylamide/acrylic acid ester copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, casein, polyethyleneimine, polyethyleneamine, and the like.

The weight ratio of the basic zirconium compound and the water-soluble resin used in the protective layer of the present invention can be arbitrarily determined depending on the selected components, but is preferably in the range of 1.5 to 0.1:1. The coating amount of the layer is usually 1 g/rd or more, which is effective, but preferably 2 g/rd or more. Note that two or more protective layers can be provided as necessary.

Further, in the present invention, various thermofusible substances (or lubricants), fillers, surfactants, etc. can be added to the protective layer in order to prevent stickiness and debris adhesion during thermal head recording. In this case, the thermofusible substances include, for example, higher fatty acids or their esters, amides, or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, etc. , 3.4-Epoxy-hexahydrophthalate dialkyl.

50-2 of higher ketones, other thermofusible organic compounds, etc.
Examples of fillers include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated fillers. Examples include inorganic fine powders such as calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin.

The leuco dyes used in the present invention may be applied singly or in a mixture of two or more types. As such leuco dyes, those applied to this type of heat-sensitive material can be arbitrarily applied. For example, triphenyl Leuco compounds of methane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(p-dimethylaminophenyl)-6-dibutylaminophenyl, 3.3- Bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-N-methyl-N-imbutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane , 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-
6-methyl-7-chlorofluorane, 3-(N-ρ-toly-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam).

3-diethylamino-6-methyl-7-(m-trichloromethylanilino)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-diethylamino-6-methyl-7-(2' , 4'-
dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(
N,N-dibenzylamino)fluorane.

Benzoylleucomethylene blue.

6'-Chloro-8'-methoxybenzoindolinopyrillospiran.

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)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluorane, 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-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3.6-bis (dimethylamino)fluorene spiro(9
゜3')-6'-dimethylaminophthalide, 3-(N-
benzyl-N-cyclohexylamino)-5,6-pendi-2α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-7nilinofluorane, 3-N-ethyl-N-(2 -ethoxypropyl)amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-fumesitidino 4', 5'-benzofluorane, and the like.

In addition, as the color developer used in the present invention, various electron-accepting compounds that cause the leuco dye to undergo catalytic color development are preferably used, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids, and metal salts thereof. applied,
Specific examples include those shown below.

4.4'-isopropylidene bisphenol, 4.4
′ -isopropylidene bis(0-methylphenol)
, 4.4'-Secondary-butylidene bisphenol 4.4'-Isopropylidene bis(2-tert-
butylphenol), 4.4'-cyclohexylidene diphenol, 4.4
′ -isopropylidene bis(2-chlorophenol)
, 2.2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-methylenebis(4-ethyl-6-tert-butylphenol), 4.4'-butylidenebis(6-tert-butyl- 2-methylphenol), 1.1.3-tris(2-methyl-4-hydroxy-5
-tert-butylphenyl)butane, 1.1.3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane.

4.4'-thiobis(6-tert-butyl-2-
methylphenol).

4.4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4.4'-diphenolsulfoxide, isopropyl P-hydroxybenzoate, P- Benzyl hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis(4-hydroxyphenylthio)-3,5
-dioxahebutane, 1,5-bis(4-hydroxyphenylthio)-3-oxapentane, 1,3-bis(4-hydroxyphenylthio)-propane.

1.3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'-diphenylthiourea, N,N'-di(m-chlorophenyl)thiourea, salicylanilide.

5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium.

Bis-(4-hydroxyphenyl)acetic acid methyl ester.

Bis-(4-hydroxyphenyl)acetic acid benzyl ester.

1.3-bis(4-hydroxycumyl)benzene, 1.
4-bis(4-hydroxycumyl)benzene, 2.4'
-diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone.

α,α-bis(4-hydroxyphenyl)-α-methyltoluene.

Antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, etc.

In the present invention, the developer is generally used in an amount of 1 to 10 parts by weight, preferably 2 to 6 parts by weight, per 1 part by weight of the leuco dye.

In the present invention, various conventional binders can be used as appropriate to bind and support the leuco dye and color developer on the support. Specific examples of such binders include polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic Acid ester copolymer, acrylamide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, In addition to water-soluble polymers such as casein, emulsions such as polyvinyl acetate, polyurethane, polyacrylic ester, polymethacrylic ester, vinyl chloride/vinyl acetate copolymer, ethylene/vinyl acetate copolymer, and styrene/butadiene copolymer Examples include polymers, latexes such as styrene/butadiene/acrylic copolymers, and the like.

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, may be used.

A surfactant, a thermofusible substance (or lubricant), etc. can be used in combination. Specific examples of the filler and thermofusible substance in this case include the same ones as exemplified in connection with the protective layer.

In the present invention, it is also possible to provide an undercoat layer between the support and the thermosensitive coloring layer, if necessary. In this case, the components constituting the undercoat layer include the filler and binder described above.

A thermofusible substance, a surfactant, etc. can be used.

The heat-sensitive recording material of the present invention is prepared by applying and drying a heat-sensitive color forming layer coating solution containing each of the above-mentioned components onto the surface of a support such as paper 1 synthetic paper or a plastic film, and applying the above-mentioned basic zirconium compound and water-soluble resin thereon. It is manufactured by applying and drying a protective layer coating solution containing.

The heat-sensitive recording material of the present invention can be used in various fields, but in particular, it can be used as a heat-sensitive recording label sheet or a heat-sensitive magnetic ticket paper by taking advantage of the above-mentioned excellent colored images and stability of the background part. It can be used to advantage. In the case of a heat-sensitive recording type label sheet, a heat-sensitive coloring layer containing the above-mentioned leuco dye and color developer and the above-mentioned protective layer are provided on one side of the support, and an adhesive layer is provided on the other side of the support. In the case of magnetic ticket paper, a magnetic recording layer containing a ferromagnetic material and a binder as main components may be provided in place of the release mount.

〔effect〕

The heat-sensitive recording material of the present invention has a protective layer mainly composed of the above-mentioned basic zirconium compound and water-soluble resin on the heat-sensitive coloring layer. It has improved reliability and high sensitivity, with no color fading or color development on the background.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. still,
All parts and 2 shown below are by weight.

Examples 1 to 4 A mixture consisting of the following ingredients was ground in a sand grinder for 2 to 4 minutes.
Solutions A)-(D) were prepared in a time-dispersed manner.

[A] 40% dispersion of liquid polystyrene resin 75.0 parts Water 18
．． 7 parts CB) Liquid Polyvinyl alcohol 10% aqueous solution 25.0 parts Water 50
．． 0 parts (C) Liquid En-◎-Ki C9α1□Fusabatake ◎-OH75, 0 parts Calcium carbonate 125.0 parts Polyvinyl alcohol 10% aqueous solution 300.0 parts Water
450.0
Part (1)) Liquid zinc stearate 20.0 parts Methyl cellulose brocade aqueous solution - 6.0 parts water
74.0 parts A mixture consisting of the following components was stirred with an agitator to prepare (E)-(
G) Solution was prepared.

[E] Liquid polyacrylamide 30% aqueous solution 8.0 parts Water 23
．． 5 parts (F) liquid water
23.5 parts (G) liquid water 2
3.5 parts then CB]: (C) = 1:10 (
Liquid B) and liquid [C] are mixed and stirred to form a heat-sensitive coloring layer coating liquid [
B'] was prepared.

Also (E): (D)=(F): (D)=(G)
: CD) = 25: 1 with (E) solution, [F
] and CG) were mixed and stirred with solution (D) to prepare protective layer coating solutions [F'], [F'] and [G'].

Next, the obtained undercoat layer coating liquid [A], heat-sensitive coloring layer coating liquid [B'] and protective layer coating liquid (E'), (F') or [G'] were coated with a fine material with a basis weight of 52 g/-. Coat the paper with the contents shown in Table 1 so that the undercoat layer is 3 g/n (, the heat-sensitive coloring layer is 6.5 g/rd, and the protective layer is 3.5 g/n), and after drying, Beck smoothing is applied. Degree is 500-200
The heat-sensitive recording material of the present invention was obtained by calendering to a temperature of 0 seconds.

Table 1 Comparative Example 1 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1 except that the protective layer was removed.

Comparative Example 2 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1, except that the protective layer coating liquid [E'] was replaced with the following liquid (H).

(H) Liquid silica 1.2 parts Glyoxal 0.6 parts Water
18.2 parts Comparative Example 3 In Example 2, the protective layer coating solution was changed from [E'] solution to (H).
A comparative heat-sensitive recording material was obtained in the same manner as in Example 2 except that the liquid was used instead.

The heat-sensitive recording material obtained as described above was measured using a thermal inclinometer with a built-in thermal head (Toyo Seiki Seisakusho Layer) at a temperature of 70-150°C, a crimping time of 1 second, and a crimping pressure of 2 kg/cm.
Printing was carried out under the conditions of AT to test the storage stability of the image area and the background area. The results are shown in Table-2. In addition, the concentration value is Macbeth concentration meter RD-914 type, and the filter is w-t'
These are the measurement results using OS.

The test conditions for the test items are as follows.

(1) Plasticizer resistance test: A polyvinyl chloride sheet containing a plasticizer is superimposed on the colored area printed at 150℃, a load of loOg/ai is applied, and the sheet is stored at 40℃ under dry conditions for 15 hours. Measure the subsequent concentration.

(2) Oil resistance test: The colored area printed at 150°C is coated with cottonseed oil, and the density is measured after storage at 40°C under dry conditions for 15 hours.

(3) Water resistance test: Put 90 g of water in a 100 cc glass beaker, immerse the colored sample printed at 150°C in it, and measure the density after storage at 20°C for 15 hours.

Table 2 From Table 2, it can be seen that the heat-sensitive recording material of the present invention has better reliability in the image area and the background area against plasticizers, oil, water, etc. compared to the comparative products.

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer as main components is provided on a support, a basic zirconium compound and a carboxyl group, a hydroxyl group, an amino group, 1. A heat-sensitive recording material comprising a protective layer containing as a main component a water-soluble resin containing at least one functional group selected from the group consisting of an amide group, an imino group, and an imide group.