JPS6235875A - heat sensitive recording material - Google Patents

Abstract

PURPOSE:To prevent overlapped feed from occurring even under high-humidity conditions when feeding a thermal recording material one sheet at a time with an automatic paper-supplying mechanism, by providing a thermal color forming layer comprising a leuco dye and a color developer on the face side of a base, and providing a backcoat layer comprising an alkyl ketene dimer on the back side of the base. CONSTITUTION:The thermal color forming layer comprising a leuco dye and a color developer is provided on the face side of the base such as a paper, a synthetic paper and a resin film, and the backcoat layer comprising an alkyl ketene dimer of general formula (I), wherein each of R and R' is hydrogen or an aliphatic group such as alkyl, is provided on the back side of the base. The color developer is used in an amount of 0.1-10pts.wt. per 1pt.wt. of the leuco dye. Accordingly, overlapped feed is prevented from occurring even under high-humidity conditions at the time of automatic paper supply, and extremely favorable automatic paper supply can be performed.

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.

[Prior art]

A thermosensitive recording material is a recording material having a structure in which a so-called thermosensitive coloring layer that develops color when heated is formed on a support such as paper, synthetic paper, or resin film, and a thermal head is used for heating to develop the color. A built-in thermal printer is used. Compared to other recording materials, such recording materials can produce records in a short time using relatively simple equipment without complex processes such as development and fixing, and are less likely to generate noise or pollute the environment. Due to its advantages such as the absence of paper and low cost, 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, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a color former and a color developer that causes the color former to develop specific heat color. As the color former, for example, a composition having a lactone, lactam or spiropyran ring is used. Colorless or light-colored leuco dyes are used, and various acidic substances such as organic acids and phenolic substances are used as color developers. A recording material that combines a color former and a color developer has the advantage that the resulting image has a particularly clear color tone, a white background, and the image (dye image) has excellent weather resistance. , is widely used.

Even with a certain amount of force, such heat-sensitive recording materials can be thermally printed one sheet at a time using a recording device with an automatic paper feeding mechanism.
Static electricity is generated by friction between heat-sensitive recording materials and they become electrically charged. For this reason, when feeding paper, 2 to 4 sheets may be fed in layers, causing the thermal head section and paper feeding section to
Failure may occur due to the multilayer feeding.

This phenomenon is known to occur significantly in humid conditions, and it was hoped that this problem could be solved.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that does not cause multilayer feeding even under humid conditions when performing thermal printing while feeding sheets one by one using an automatic paper feeding mechanism.

〔composition〕

According to the present invention, a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on the surface of a support, and a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on the back surface of the support.
A heat-sensitive recording material is provided which is characterized by being provided with a back coat layer made of an alkyl ketene dimer.

Since the heat-sensitive recording material of the present invention is provided with a back coat layer made of an alkyl ketene dimer represented by the following general formula (1), there is no problem in multilayer feeding even under humid conditions during paper feeding. Does not occur.

(In the formula, R and R' are hydrogen or an aliphatic group such as an alkyl group.) The alkyl ketender is a conventionally known substance, and preferred examples include methyl ketene dimer, dimethyl ketene dimer, and ethyl ketene dimer. Examples include dimer, diethyl ketene dimer, and the like. The amount of the alkyl ketene dimer deposited on the support is preferably about 0.1 to 10 g/- on a dry deposition basis.

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:
Any dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran 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(ρ- Dimethylaminophenyldimethylaminophenyl, 3,3-bis(p-dimethylaminophenyl)-6=chlorphthalide.

3,3-bis(p-dimethylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran.

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-dithylamino)-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-(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)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)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-〇-butylanilino)fluoran, 3-(N-benzyl-cyclohexylamino)-5,6
-Penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

Further, as the color developer used in the heat-sensitive coloring layer of the present invention, various electron-accepting substances that react with the leuco dye and color it when heated are used, and specific examples thereof are as follows. Examples include phenolic substances, organic or inorganic acidic substances, and salts thereof as shown below.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-di-sier
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-dimethimephenol)
, 4,4'-isopropylidene bis(2-tert-butylphenol), 4.4'-7sec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methyl phenol), 4-tert-butylphenol,
4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-thiobis (4,6-dichlorophenol), catechol, resorcinol, hydroquinone,
Pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-tert-octylcatechol, 2.2'-
Methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6tert-butylphenol), 2゜2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, ρ-hydroxybenzoate Butyl acid, benzyl p-hydroxybenzoate, p-lylorbenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, P-methylbenzyl p-hydroxybenzoate, P-
n-octyl hydroxybenzoate.

Benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone , bis(4-hydroxyphenyl) sulfide,
2-hydroxy-p-toluic acid, 3,5-jer
Zinc t-butylsalicylate, tin 3,5-jert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, etc.

In the present invention, the ratio of the leuco dye and color developer used in the thermosensitive coloring layer is 0.1 to 10 parts by weight, preferably 1 to 4 parts by weight, per 1 part by weight of the leuco dye. It is.

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, such as 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, polybutyl methacrylate, ethylene/vinyl acetate copolymer, etc. Polymers, latexes such as styrene/butadiene/acrylic copolymers, etc. can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components 1 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 higher fatty acids or their esters, amides, or metal salts. In addition, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organics. Examples include compounds having a melting point of about 50 to 200°C.

〔Example〕

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.

Example 1 [Liquid A] 3-N-methyl-3-cyclohexylamino-6-methyl-7-anilinofluorane 300 parts 10%
Polyvinyl alcohol aqueous solution 300 water
400〃
[Liquid B] Benzyl p-hydroxybenzoate 150 parts Calcium carbonate 151! Zinc stearate 2,51110% polyvinyl alcohol aqueous solution 1601/water
672.5 I
I Each of the above mixtures was mixed in a sander blinder for 2
The mixture was pulverized and dispersed for ~4 hours to prepare liquids A and B.

Next, the A and B solutions were mixed and stirred so that the weight ratio was A:B=16 to prepare a heat-sensitive coating solution, which was adhered to the surface of commercially available high-quality paper (basis weight 50 g/rrr) during drying. Amount 5g/
The mixture was coated and dried to form a heat-sensitive coloring layer.

Next, on the back side of the heat-sensitive recording paper obtained above, the following back coat layer coating liquid was applied and dried to form a back coat layer at a dry coating weight of 0.5 g/rrr, and then calendered to form a product. did.

[Back coat layer coating liquid]

Alkyl ketene dimer Australian product name: Acopel 12, manufactured by Deitzk Hercules ■) Example 2 The following composition was stirred in an agitator to prepare an undercoat layer coating solution, and coated on commercially available high-quality paper (50 g/m). The undercoat layer is provided by coating and drying so that the weight after drying is 4 g/n.

[Undercoat layer coating liquid]

Calcium carbonate 30 parts Zinc oxide 10! ! 20% starch aqueous solution 'lQn styrene-butadiene latex (48%) lQI + water
30 Next, on this undercoat layer, the heat-sensitive coating liquid of Example 1 was applied and dried under the same conditions, and then the heat-sensitive coating liquid was applied and dried under the same conditions, and then the following was applied on the heat-sensitive coloring layer. An overcoat layer coating solution was applied and dried at a dry adhesion Jt of 2 g/rrr to form an overcoat layer.

Next, the coating liquid for the back coat layer on the back side of the heat-sensitive recording paper obtained above was applied and dried at a dry adhesion amount of 0.5 g/r&.

After forming the back coat layer, the product was subjected to calender treatment.

[Overcoat layer coating liquid]

20% polyvinyl alcohol aqueous solution 5.0 parts 12
．． 5% polyamide resin aqueous solution 8.0 parts water
87
．． 0 parts [Backcoat layer coating liquid] Alkyl ketene dimer 1 ■Product name: Accorpel 360 1), polyvinyl alcohol layer (comparative example 2)
, an oxidized starch layer (Comparative Example 3), an acrylic resin layer (Comparative Example 4), and a styrene-maleic anhydride copolymer alkali salt layer (Comparative Example 5). Got paper.

The products of the present invention and comparative products obtained as described above were fed using an automatic paper feeding mechanism (
2,000 sheets of planographic size A-4) were printed at a temperature of 30°C.

A paper feeding test was conducted under conditions of 85% humidity. The results are shown in the table below.

Table 1 [Effects] From the results shown above, it can be seen that the product of the present invention has very good automatic paper feeding properties, with almost no multilayer feeding even in humid conditions. it is obvious.
Further, even when the heat-sensitive recording material of the present invention was printed at high speed using a Ricoh facsimile machine (RIFAX 120), the high-speed running was not hindered, and a clear black image with high density was provided.

Claims (1)

[Claims] (1) A heat-sensitive recording material characterized in that a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on the surface of a support, and a back coat layer made of an alkyl ketene dimer is provided on the back surface of the support. .