JPS62279982A - Tehrmal recording material - Google Patents

Abstract

PURPOSE:To contrive higher image preservation stability and fingerprint resistance, by using a novolak-type resin of p-phenylphenol having a softening point of not lower than 100 deg.C as a color developer. CONSTITUTION:A novolak-type resin of p-phenylphenol having a softening point of not lwoer than 100 deg.C is used as a color developer, in a thermal recording material which comprises on a base a thermal color forming layer comprising a leuco dye and the color developer as main constituents. The resin is ordinarily used in an amount of 0.1-10 pts.wt., preferably, 1-4 pts.wt. per 1 pts.wt. of the leuco dye. The thermal color forming layer comprising the leuco dye and the color developer as main constituents may further comprises a novolak-type resin of p-phenylphenol having a softening point of not lower than 100 deg.C as an auxiliary constituent, in an amount of ordinarily 0.01-10 pts.wt., preferably, 0.05-1 pts.wt. per 1 pts.wt. of the leuco dye.

Description

[Detailed description of the invention] 3. Detailed description of the invention 〔Technical field〕 The present invention relates to heat-sensitive recording materials, and more particularly.

This invention relates to an improvement in a heat-sensitive recording material provided on a support with a heat-sensitive color-forming layer containing as a color-forming component a leuco dye that is colorless or slightly light-colored at room temperature and a color developer that develops color by reacting with the leuco dye when heated.

(Prior art) Thermosensitive recording materials generally have a thermosensitive coloring layer containing a thermochromic composition as a main component on a support such as paper, synthetic paper, or plastic film. A colored image can be obtained by heating with a .Compared to other recording materials, this type of recording material does not require complicated processes such as development and fixing, and can be produced in a short time using relatively simple equipment. , low noise generation and environmental pollution.

Due to its low cost and other advantages, it is used not only for copying books and documents, but also as a recording material in a wide range of applications such as electronic computers, facsimiles, 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, and the coloring agent includes:
For example, colorless or light-colored leuco dyes having a lactone, lactam or spiropyran ring are used, and various acidic substances such as organic acids and phenolic substances are used as color developers. Recording materials that combine this color forming agent and color developer have the advantage that the resulting image has a particularly clear color tone, has a high background whiteness, and has excellent weather resistance, and is widely used. has been done.

Conventionally, bisphenol A, p-hydroxybenzoic acid esters, and the like have been used as color developers for leuco dyes;

Although the color density is high, the stability of the color image is lacking, so there is a problem that the density decreases when left alone, and also when it comes into contact with oils and fats such as fingerprints, plasticizers, etc.

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.

In the field of pressure-sensitive paper, it has been proposed to use metal compounds of aromatic carboxylic acids as color developers that provide images with good stability, as seen in Japanese Patent Publication No. 1327/1983.
When applied to thermal paper, although the image is stabilized, the non-image area (background area) develops color due to contact with oils and fats, making it difficult to read the image. At present, it is difficult to apply it in practice. Also,
Aromatic oxycarboxylic acids (e.g. salicylic acid, 2
-Oxy-3-naphthoic acid, etc.) has been proposed as a color developer, but this also has the drawback that non-image areas develop strong color upon contact with oils and fats, reducing contrast. There is.

〔the purpose〕

The present invention overcomes the problems of the prior art, that is, provides a heat-sensitive recording material with improved image storage stability, excellent fingerprint resistance, high sensitivity, almost no background coloring, and improved reliability. The purpose is to

〔composition〕

According to the present invention, as a first invention, in a heat-sensitive recording material provided with a heat-sensitive color forming layer containing a leuco dye and a color developer as main components on a support, the color developer has a softening point of 100°C or higher. A heat-sensitive recording material characterized by using a paraphenylphenol novolac type resin is provided, and as a second invention, a heat-sensitive coloring layer containing a leuco dye and a color developer as main components is provided on a support. The present invention provides a heat-sensitive recording material characterized in that a novolac-type resin of paraphenylphenol having a softening point of 100° C. or more is further used as an auxiliary component.

In the present invention, a paraphenylphenol novolac type resin with a softening point of 100°C or higher is used as a color developer and an auxiliary component, so it is a thermosensitive resin with high sensitivity, excellent image stability, and good fingerprint resistance. Recording materials can be obtained.

In the present invention, when the paraphenylphenol novolac type resin is used as a color developer, the amount used is usually 0.1 to 10 parts by weight, preferably 1 to 4 parts by weight, per 1 part by weight of the leuco dye.

In addition, when the paraphenylphenol novolak type resin is used as an auxiliary component, the amount used is usually 0.01 to 10 parts by weight, preferably 0.05 to 1 part by weight, per 1 part by weight of the leuco dye. It's good.

In addition, in the present invention, the novolak type resin of paraphenylphenol has a softening point of 1 from the viewpoint of color development and shelf life.
It is preferable to use a temperature range of 00-150°C.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

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-dimethylaminophenyl.

3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5, 7-dimethylfluorane.

3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-
6-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane , 2-(N-(3'-)-lifluoromethylphenyl)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-(0-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-(N,N- diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane.

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)fluoran.

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)fluoran, 3-(N-ethyl-ρ-toluidino)-7-(α-phenylethylamino)fluoran, 3- Diethylamino-7-(0-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-〇-butylanilino)fluoran, 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-N-n-amyl)amino-6-methyl-7- Anilitufluoran et al.

In the present invention, other color developers that can be used in combination with the paraphenylphenol novolac type resin include:
Color developers made of conventionally known phenolic substances, inorganic/organic acidic substances, and derivatives thereof can be used. Specific examples thereof include phenolic substances, organic or inorganic acidic substances, and esters and salts thereof as shown below.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-Cyclohexylsalicylic acid, 3,5-ter
t-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-tart-butylphenol), 4.4'-5
ec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α -naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone,
Novolak type phenolic resin, 2゜2'-thiobis(4
, 6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycine, phloroglycincarboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis( 4-methyl-6-tar
t-butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate,
ρ-Benzyl hydroxybenzoate, P-hydroxybenzoic acid-P-chlorobenzyl, p-hydroxybenzoic acid-
〇-Chlorbenzyl, p-methylbenzyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, benzoic acid, zinc salicylate, 1-hydroxy-2-
Naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 2- hydroxynyl-toluic acid, 3,5-di-t
Zinc ert-butylsalicylate, 3,5-di-tert
-tin butylsalicylate, 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 on the support, various commonly used binders can be used as appropriate, and specific examples thereof include the following: Can be done. polyvinyl alcohol,
Starch and its derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose,
Cellulose derivatives such as methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone,
Acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, poly Acrylamide, sodium alginate, gelatin,
In addition to water-soluble polymers such as casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, and 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, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of thermofusible substances include 1, for example, higher fatty acids or their esters, amides, or metal salts. In addition, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organic compounds. Examples include those 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 a heat-sensitive recording type label sheet or a heat-sensitive recording type magnetic ticket paper. In the case of a heat-sensitive functional label sheet, a heat-sensitive coloring layer containing the above-mentioned leuco dye, color developer, and metal compound is provided on one side of the support, and a heat-sensitive coloring layer containing the above-mentioned leuco dye, color developer, and metal compound is provided on the other side of the support through an adhesive layer. A release mount may be provided, and 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.

It is also possible to use the above-mentioned leuco dye, color developer and metal compound as a heat-sensitive transfer material, each provided on a separate support.

〔effect〕

The heat-sensitive recording material of the present invention is a heat-sensitive recording material provided with a color-forming layer containing a leuco dye and a color developer as main components. Since we used
Compared to conventional heat-sensitive recording materials, the color image has a high sensitivity, and the color image and the background have excellent storage stability and finger squeeze resistance.

〔Example〕

The invention will be explained in more detail by the following examples.

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

[Liquid A]

3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-anirite fluorane 20 parts 10% aqueous solution of hydroxyethylcellulose 20II water
60 total
100 [Liquid B] Paraphenylphenol novolac type resin (softening point 1
05°C) 15 parts parabenzylbiphenyl 15 Calcium carbonate 15 Zinc stearate 5 10% polyvinyl alcohol aqueous solution 15 Water
35/! total
100//Disperse A liquid and B liquid in a ball mill to reduce the average particle size to 5 μI or less, and then [A liquid) 1. (
Solution B] Mix and stir uniformly at a ratio of 4 parts, and apply the resulting coating solution to a high-quality paper with a basis weight of 50 g/rri with a dry weight of 6 g/nf.
A heat-sensitive layer was provided by coating and drying to obtain a heat-sensitive recording material of the present invention.

Example 2 In Example 1, instead of the novolac type resin of paraphenylphenol (softening point 105°C) in [Liquid B], a softening point of 1 was used.
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that a material having a temperature of 20°C was used.

Example 3 [Liquid A'] 3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-anilite fluorane 20 parts 10% aqueous solution of hydroxyethylcellulose 20 parts water
60 total
10011CB' liquid] Benzyl P-hydroxybenzoate 20 parts Novolac of paraphenylphenol 5/! Mold resin (
Softening point: 105°C) Calcium carbonate 25 Zinc stearate 5 Polyvinyl alcohol 10% aqueous solution 25 Water
70 total
150 (Liquid A'), (Liquid B').

Disperse with a ball mill to reduce the average particle size to 5μ11 or less, (
A' liquid] 1, (B' liquid mixed in 4 proportions, stirred uniformly,
The resulting coating solution was coated on a high-quality paper having a basis weight of about 50 g/day so that the dry weight was 6 g1rd, and dried to form a heat-sensitive layer, thereby obtaining a heat-sensitive recording material of the present invention.

Example 4 The present invention was carried out in the same manner as in Example 3 except that instead of the paraphenylphenol novolac type resin (softening point 105°C) in Example 3 (liquid B'), a resin with a softening point of 120°C was used. A heat-sensitive recording material was obtained.

Example 5 Except for using bisphenol A in place of benzyl P-hydroxybenzoate in [Liquid B'] in Example 4,
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 4.

Comparative Example 1 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1 except that paraphenylphenol was used in place of the novolac type resin of paraphenylphenol in [Liquid B].

Comparative Example 2 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1, except that bisphenol A was used in place of the paraphenylphenol novolak type resin of [Liquid B] in Example 1.

Comparative Example 3 A comparative sample was prepared in the same manner as in Example 3, except that 3.3',5.5'-tetrabromobisphenol S was used in place of the paraphenol novolak type resin of the CB' liquid in Example 3. A thermosensitive recording material was obtained.

Comparative Example 4 In Example 3, 1,1
A comparative heat-sensitive recording material was obtained in the same manner as in Example 3 except that -bis(4-hydroxyphenyl)-cyclohexane was used.

The heat-sensitive recording paper thus obtained was subjected to comparative tests for color development sensitivity, whiteness of the background area, fingerprint resistance of the color development area, moisture resistance, and color fading resistance. The results are shown in the table.

The color sensitivity was determined by measuring the color density of an image area recorded using a Gm-type practical high-speed thermal facsimile (model RIFAX 130, manufactured by Ricoh Co., Ltd.) using a Macbeth densitometer (model RD-100R, manufactured by Macbeth Co., Ltd.). In addition, the whiteness was measured using a Hunter whiteness meter. Fingerprint resistance was evaluated by attaching a fingerprint to the resulting image area, and after one month at room temperature, the degree of discoloration of the area was visually judged using the following evaluation criteria. Regarding moisture resistance and fading resistance, the obtained image area was left at room temperature for one month, and then the density of the image area was measured using a Macbeth densitometer, and the density before and after storage was determined according to the evaluation criteria below. It was judged.

Fingerprint resistance evaluation criteria O: The degree of discoloration is extremely small.

0: There is some color erasure, but the image can be read.

×...The image is largely erased and cannot be read.

Evaluation criteria for moisture fading resistance O...Concentration difference less than 0.05 o...Same as above 0.05-0.15 ×・・・Same as above 0.15 or more Table - ■

Claims (2)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive color forming layer containing a leuco dye and a color developer as main components is provided on a support, a paraphenylphenol novolac type resin with a softening point of 100°C or higher is used as the color developer. A heat-sensitive recording material characterized by: (2) 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 paraphenylphenol novolak type resin having a softening point of 100° C. or higher is further used as an auxiliary component. A heat-sensitive recording material characterized by: