JPS61169279A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance oil resistance and prevent development of ground color, by producing a thermal recording material by supporting a leuco dye and a color developer such as a barium salt of hydroxynaphthoic acid in a bound state on a base. CONSTITUTION:A thermal recording layer forming coating liquid comprising a leuco dye, a color developer, a binder and the like is prepared. The coating liquid is applied to a base such as a paper, a synthetic paper and a plastic film, followed by drying to produce a thermal recording material. The leuco dye is, for example, 3,3-bis(p-dimethylaminophenyl)phthalide. The color developer is, for example, a barium salt, a strontium salt or a magnesium salt of hydroxynaphthoic acid. The binder may be a polyvinyl alcohol, starch, a derivative thereof, methoxy cellulose or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and more specifically, the present invention relates to a heat-sensitive recording material, and more specifically, a combination of a leuco dye that is colorless or slightly pale at room temperature, and a color developer that reacts with the leuco dye when heated to develop a color. This invention relates to the improvement of heat-sensitive recording materials that utilize color-forming reactions between the two.

[Prior art]

Thermosensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film provided with a thermosensitive coloring layer containing a thermochromic composition as a main component.
A colored image can be obtained by heating with a strobe lamp or the like. Compared to other recording materials, this type of recording material
It has the advantages of being able to obtain records in a short time with a relatively simple device without complicated processes such as fixing, generating less noise and polluting the environment, and being inexpensive.
In addition to being used for copying books, documents, etc., it is also widely used as a recording material in a wide variety of applications, including electronic computers, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a coloring agent and a color developer that causes the coloring agent to develop color when heated.
As the color former, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring is used, and as a color developer, an organic acid or a phenolic substance is conventionally used. This recording material that combines a color forming agent and a color developing agent has the advantage that the resulting image has a particularly clear color tone, has a high background whiteness, and has excellent light resistance, and is widely used. It's being used.

Conventionally, bisphenol A and p-hydroxybenzoic acid esters have been used as color developers for leuco dyes, but these phenols have high color density but lack the stability of colored images, so they cannot be left alone. In addition to the problem that the concentration decreases when it comes into contact with oils and fats such as fingerprints, the concentration also decreases. These phenomena occur not only when using phenols but also when general organic acids are used, and there is a strong desire to overcome them. As seen in JP-A-59-38094, the use of metal compounds such as aluminum chloride has been proposed as a color developer that provides images with good stability; however, when this is applied to heat-sensitive recording materials, Although the image is stabilized, it is currently difficult to apply it to heat-sensitive recording materials because of the initial background color development.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to overcome the problems of the prior art, that is, to provide a heat-sensitive recording material with improved oil resistance, almost no background coloration, and improved reliability.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, the color developer may be a barium salt of hydonic acid sidef-1-dioic acid, a strontium salt, or A heat-sensitive recording material characterized in that it uses at least one kind selected from magnesium salts is provided.

The color developer used in the present invention is barium salt of nara 1 to engineering acid,
The salt is selected from salts of rontium 1 to rontium and salts of magnesilla 11. Specific examples of such salts include, for example, 2
-Hydroxy-1-nano-1-diacid barium, 2-hydroxy-1-nano-1-chloronthiram, magnesium 2-hydroxy-1-naphthoate, barium 1-hyroxy-2-naphthoate, Strontium 1-hydroxy-2-nanol-diacid, Magnesium 1-hydroxy-2-naphthoate, Barium 2-hydroxy-3-naphthoate, 2-hydroxy-3-nano-l-steronate 1- Examples include, but are not limited to, rontium, 2-hydroxy-3-naph) to magnesium chloride, and the like.

Further, in the present invention, at least one metal compound selected from zinc, aluminum, and tin is used as an auxiliary component for the color developer, if necessary, such as, for example, Examples include various organic and inorganic metal compounds as shown below.

Zinc, aluminum or saturated or unsaturated carboxylic acids such as stearic acid, palmitic acid, myristic acid, lauric acid, behenic acid, acetic acid, caproic acid, octylic acid, propionic acid, linoleic acid, oleic acid, sebacic acid, sorbic acid, etc. Tin salts; zinc, aluminira 11 or tin salts of polyhydric carboxylic acids such as malonic acid, oxalic acid, succinic acid, tartaric acid; zinc, aluminum or tin salts of polymeric acids such as polyacrylic acid and styrene-acrylic acid copolymers Salt; benzoic acid, naph 1
Zinc, aluminum or tin salts of aromatic carboxylic acids such as helical acid; zinc, aluminum or tin salts of sulfonic acids such as benzenesulfonic acid; zinc oxide, zinc hydroxide, zinc carbonate,
Zinc sulfooxylate, zinc sulfite, zinc sulfate, zinc thiosulfate, zinc dithionate, zinc trithionate, zinc nitrate,
Zinc hydroxylamine carbonate, zinc phosphate, zinc amine sulfate, basic zinc amine sulfate, zinc phosphite, zinc pyrophosphate.

Zinc halides such as zinc chloride and zinc bromide, and various compounds such as hydroxides, oxides, and inorganic acid salts of aluminum and tin similar to those for zinc.

The zinc, aluminum or tin compound used as an auxiliary component in the present invention has a molar ratio of 0.1 to 0.1 to the color developer.
It is preferable to use the range of IO times.

The leuco dye used in the present invention can be applied in one or two combinations, and any leuco dye that has been applied to this type of heat-sensitive material can be used, for example, 1-rephenylmethane series, fluorane series, phenothiazine series, auramine series, spiropyran series,
Leuco compounds of dyes such as indolinophthalide 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- Chlorfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-lyrolofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-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-1-lichloromethylanilino)fluoran, 3-diethylamino-7- (o-chloroanilino)fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-tuanilinofluorane, 3-N-methyl-N-cyclo Hexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino) fluorane, benzoylleucomethyl non-blue, 6'-chloro-8'-methyl-xy-benzoindolino-
Pyrillospiran, 6'-bromo-37-methyl-oxy-benzoindolino-
Pyrylospiran, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-me1-xy5'-chlorphenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl) )-3-(2'-methoxy-5'-21-phenyl)phthalide, 3-(2'-hydroxy-47-dibutylaminophenyl)-3-(2'-methoxy-5'-methylphenyl ) phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-1-lifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7 -(N-benzyl-1-lifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-P-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino ) fluoran, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(0-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-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane, 3.6-simethoxyfluorane, 3-(P-dimethylaminophenyl)-3-phenylphthalide, 3-di(1-ethyl-2-methylyldol)-3 -yl-phthalide, 3-diethylamino-6-phenyl-7-azafluorane.

3.3-bis(p-diethylaminophenyl)-6-dimethylaminophthalide, 2-bis(p-dimethylaminophenyl)methyl-5-
Dimethylamino-benzoic acid, 3-(p-dimethylaminophenyl)-3-(p-dibenzylaminophenyl)phthalide, 3-(N-ethyl-Nn-amyl)amino-6-methyl-7- Anilitufluoran et al.

As the color developer used in the present invention, in addition to the metal salt of hydroxynaphthoic acid, if necessary, color developers made of conventionally known phenolic substances, inorganic/organic acidic substances, and derivatives thereof may be used. They can also be used together. The color developer used in the present invention 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. A color developer consisting of a metal salt is
20% or more of the total color developer, preferably 50% by weight
That's all.

In the present invention, as the color developer that can be used in combination with the metal salt of hydroxynaphthoic acid, various electron-accepting substances that react with the leuco dye to develop color when heated are used. , phenolic substances, organic or inorganic acidic substances, or their esters and salts as shown below.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-di-tert
-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-dimethylphenol),
4,4'-isopropylidene bis(2-tert, -butylphenol), 4,4'-5ec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methyl Phenolphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3
, 5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyace=12-1~phenone, novolak type phenolic resin, 2,2'
-thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-her7-
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, benzyl p-hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, p
-0-chlorobenzyl p-hydroxybenzoate, p-methylbenzyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, benzoic acid, 1-hydroxy-
2-naphthoic acid, 2-hydroxy-6-naph I-Nikai,
4-hydroxydiphenylsulfone, 4-hydroxy-
4'-chlorodiphenylsulfone sulfide, 2-hydroxy-p-+ruyl acid, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivatives, 4- Hydroxythiophenol derivatives, etc.

In the present invention, in order to bind and support the leuco dye and color developer to the support, various commonly used binders can be used as appropriate, and specific examples thereof include the following: be able to.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer.

Water-soluble acrylic acid amide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to polyvinyl acetate,
Polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc.

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, inorganic fine powders such as calcium carbonate, silica, titanium oxide, barium sulfate, clay, talc, and surface-treated calcium and silica, as well as urea-formalin resin, styrene/methacrylic acid, etc. Organic fine powders such as polymers and polystyrene resins can be mentioned. Examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts, as well as various waxes, aromatic carboxylic acids, and the like. Condensation products with amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-epoxyhexahydrophthalates, higher ketones,
Examples include other thermofusible organic compounds having a melting point of about 50 to 200°C.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying it. It is used in the field of recording, especially as a heat-sensitive recording material for high-speed recording that requires high image stability.

The heat-sensitive recording material of the present invention is used in various fields, but in particular, it takes advantage of the above-mentioned excellent color image stability,
It can be advantageously used as heat-sensitive recording type label sheet 1 - or heat-sensitive recording type magnetic ticket paper. In the case of a heat-sensitive recording type label sheet, a heat-sensitive color forming layer containing the above-mentioned leuco dye and color developer is provided on one side of the support, and a release mount is placed on the other side of the support through an adhesive layer. 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.

Further, in the present invention, the leuco dye, the color developer, and the auxiliary component used as necessary can be contained in the same coating layer, or can be contained in separate coating layers.

〔effect〕

The heat-sensitive recording material of the present invention uses hydroxynaf (
- By using at least one of double-baked barium salt, strontium salt, and magnesium salt, image decolorization due to oil, etc. is reduced compared to conventional heat-sensitive recording materials, and image reliability is significantly improved. It is.

〔Example〕

The present invention will now be described in more detail with reference to Examples.

Note that all parts and percentages below are based on weight.

Example 1 [Liquid A] 3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-anirite fluorane 10 parts 10% aqueous solution of hydroxyethylcellulose 10 parts water
80
Part [Liquid B] Barium 2-hydroxy-3-naphthoate 10 parts Calcium carbonate 20 parts 10% polyvinyl alcohol aqueous solution 10 parts Water
f30
Part [Liquid C] N-stearylbenzamide 10 parts
% polyvinyl alcohol aqueous solution 10 parts water
80
Sand glider
Grind and disperse for 2 to 4 hours with
Solution C] was prepared.

Next, the weight ratio of [liquid A], [liquid B], and [liquid C] is 1:3.
Mix and stir to obtain a ratio of :3 to prepare a heat-sensitive coating liquid.
A dry coating weight of 6.2 g/m (basis weight) commercially available high-quality paper was applied. Jin/
Apply Lab Coach in Blonde and let it dry. This coated paper has a surface smoothness of 700 to 1200 seconds.
A heat-sensitive recording material of the present invention was prepared by calendering so that the temperature was as follows.

Example 2 The present invention was carried out in the same manner as in Example 1, except that 2-hydroxy-3-nano 1-2m barium in [Liquid B] was replaced with 2-hydroxy-1-naph I-sulfonate 1-rontium. A heat-sensitive recording material of the invention was obtained.

Example 3 The method of the present invention was carried out in the same manner as in Example 1, except that the barium 2-hydroxy-3-nano-acid dioate in [Liquid B] was replaced with magnesium 1-hydroxy-2-naph I-acid diacid. A thermosensitive recording material was obtained.

Example 4 A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that the following [Liquid D] was used instead of [Liquid B].

[Liquid D]

Strontium 2-hydroxy-3-naphthoate, 7 parts P
-Benzyl hydroxybenzoate 3 parts Calcium carbonate 30 parts 10% polyvinyl alcohol 10 parts Comparative Example 1 In Example 1, barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with benzyl P-hydroxybenzoate. A comparative heat-sensitive recording material was obtained in the same manner.

Comparative Example 2 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1, except that barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with bisphenol A.

Comparative Example 3 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1, except that barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with zinc 2-hydroxy-3-naphthoate.

The above heat-sensitive recording materials were tested for image density, background density, and decolorability with oil.

The results are shown in Table-1. In addition, each test method was performed as follows.

(1) Image density...Using a commercially available thermal gradient tester,
It was heated at 150° C. for 1 second under a load of g/cnW, and the colored area at that time was measured using a McMess densitometer RD-514 (filter: 1l-106).

2O- (2) Background density: The uncolored area was similarly measured using a Macbeth densitometer.

(3) Oil resistance..." Cottonseed oil was applied to the sample whose image density was measured in Section 1 (1) using absorbent cotton, and the density in the image area and background area was measured after being left at 40°C for 24 hours. .

Table 1 As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has better image and background stability than conventional materials.

Example 5 In Example J, the following [liquid c'] was used instead of [liquid C].
A heat-sensitive recording material of the present invention was obtained in the same manner except that the coating amount was 8.0 g/rrr.

(Liquid C') N-stearylbenzamide 10 parts Zinc stearate 10 parts 10% polyvinyl alcohol aqueous solution 20 parts Water
60 parts Example 6 In Example 5, barium 2-hydroxy-3-nano-diacid diacid in [Liquid B] was replaced with rontium 2-hydroxy-1-nano-1-diacid diacid, and [Liquid C' A heat-sensitive recording material of the present invention was obtained in the same manner except that zinc stearate was replaced with aluminum benzoate.

Example 7 In Example 5, barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with magnesium 1-hydroxy-2-naphthoate, and zinc stearate in [Liquid C'] was replaced with dibasic sulfate. A heat-sensitive recording material of the present invention was obtained in the same manner except that tin was used.

Example 8 In Example 5, barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with strontium 2-hydroxy-3-nano-1-naphthoate, and zinc stearate in [Liquid C'] was replaced with xanthate. A heat-sensitive recording material of the present invention was obtained in the same manner except that zinc was used.

Comparative Example 4 A comparative heat-sensitive recording material was obtained in the same manner as in Example 5, except that barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with benzyl P-hydroxybenzoate.

Comparative Example 5 A comparative heat-sensitive recording material was obtained in the same manner as in Example 5, except that barium 2-hydroxy-3-naphthoate in [Liquid B] was replaced with bisphenol A.

Comparative Example 6 A comparative heat-sensitive recording material was obtained in the same manner as in Example 5, except that barium 2-hydroxy-3-naphthoate was replaced with 2-hydroxy-3-nano-1-2-zinc in [Liquid B]. Ta.

The above thermal recording sheet was printed at 150°C for 1 second using a commercially available thermal gradient tester, and the image density and background density were measured using a Macbeth densitometer RD'-5.
14 (Furter: υ-106). Each of these colored samples was tested for decolorization by oil and plasticizer as follows. The results are shown in Table-2.

(1) Oil resistance: Cottonseed oil was applied to the above colored sample using absorbent cotton, and the density of the image area and background area after being left at 40° C. for 24 hours was measured.

(2) Plasticizer resistance: Dioctyl adipate (DOA) was applied to the above colored sample using absorbent cotton, and the density of the image area and background area after being left at 40° C. for 24 hours was measured.

=24-Table-2 As is clear from the results in Table-2, the heat-sensitive recording material of the present invention has better image and background stability than conventional materials.

Claims (2)

[Claims] (1) In a heat-sensitive recording material that utilizes a color reaction between a leuco dye and a color developer, at least one selected from barium salts, strontium salts, and magnesium salts of hydroxynaphthoic acid is used as the color developer. A heat-sensitive recording material characterized by: (2) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, at least one selected from barium salts, strontium salts, and magnesium salts of hydroxynaphthoic acid is used as the color developer, A heat-sensitive recording material characterized in that at least one metal compound selected from zinc, aluminum and tin is used as an auxiliary component.