JPS60176794A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To provide a thermal recording paper suitable for recording in high density at high speed, producing developed color images which are stable even when hair treatment toiletries or oils and fats are adhered thereto and capable of clear recording even with a minute amount of heat, wherein a basic colorless dye and an organic color developer containing a specified sulfonate compound are incorporated. CONSTITUTION:A composition comprising a basic colorless dye and an organic color developer containing a sulfonate compound of formula I , wherein each of R1 and R2 is 1-12C alkyl, 3-10C cycloalkyl, 7-10C aralkyl, formula II (wherein A is H, lower alkyl, lower alkoxy, nitro, halogen, hydroxyl or the like, and (m) is 0-3), formula III (wherein B is the same as A, and (n) is 0-3), formula IVor the like, is applied to a base paper to provide a color forming layer, thereby obtaining the objective thermal recording paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording paper, and more particularly to a thermal recording paper that is suitable for high-density and high-speed recording, and that provides stable colored images even when hair styling products and oils and fats are attached.

Thermal recording paper that utilizes the heating color reaction between a so-called basic colorless dye, which is usually colorless or light-colored, and an organic color developer such as a phenol or an organic acid, is disclosed in Japanese Patent Publication No. 43-4160 and Japanese Patent Publication No. 45.
-14039, Japanese Patent Application Laid-Open No. 48-27736, etc., and has been widely put into practical use.

Generally, thermal recording paper is produced by grinding and dispersing a basic colorless dye and an organic color developer into fine particles, then mixing the two and adding a binder, filler, sensitivity improver, lubricant, and other auxiliaries. The resulting coating liquid is applied to a support such as paper or film, and a color record is obtained through an instantaneous chemical reaction caused by heating.

In this case, various hues can be obtained by selecting a variety of colorless dyes.

Thermal recording paper can be heated by contacting a heating element or by being heated by specific light energy.
Color develops and records are obtained. A thermal head is a small resistor placed on a substrate, and by passing current in short cycles of usually 0.5 to 20 milliseconds,
By repeating heating and cooling, the coloring layer of the thermosensitive recording paper is melted by the amount of heat generated by the thermal head, and then a coloring reaction occurs to obtain a record. Thermal heads have been developed with a wide variety of materials and shapes, and each has its own performance, control method, recording conditions (applied voltage, pulse width, temperature, pressure, recording speed, and content of recorded information). ), etc., so it is important to match the requirements for thermal recording, but recently, as applications have become more diversified and higher performance has been achieved, the quality required for the thermal recording paper used has also become more advanced. It's becoming a thing.

The thermal energy of the thermal heads of these high-density and high-speed recording devices is becoming smaller and smaller, so the thermal recording paper used for these devices has become difficult to obtain clear colored records even with a small amount of heat. It is required to have sufficient color development sensitivity.

For this purpose, it is necessary for the colorless dye or organic color developer contained in the coloring layer to melt with a small amount of heat and cause a coloring reaction, and if possible, it is desirable to develop color at a temperature of 70 to 120°C. The melting point of color-forming colorless dyes having structures such as lactones, lactams, and spiropyrans used in thermal recording paper is usually 160 to 240°C;
Bistunol A, which is most widely used as an organic color developer, has a melting point of 156 to 158°C.

The coloring temperature of thermal recording paper depends on the melting of both or one of the coloring materials consisting of a coloring dye and an organic color developer. If a substance is allowed to coexist and the substance melts, thereby dissolving the coloring agent, it becomes possible to cause a coloring reaction even at low temperatures.

For this reason, JP-A-53-39139, JP-A-53-2
No. 6139, JP-A-53-5636, JP-A-53-1
No. 1036, etc., various waxes '1 FAJ] Low melting point heat-melting substances such as fatty acid amides, alkylated bifunyls, substituted bif-dial alkanes, coumarin compounds, and diphenylamines are added as sensitizers or melting point depressants. It is proposed that.

These heat-fusible substances are uniformly recognized to have sensitization properties in terms of static color density obtained by pressing a hot plate at a specific temperature for a certain period of time. However, the quality of heat-sensitive recording paper used in high-speed facsimiles, where color is generated using minute thermal energy, cannot be accurately evaluated depending on the conditions of static color development. In other words, the general static color development conditions are 7
The color develops by pressing a metal plate heated to 0 to 150℃ for a few seconds, so it is a popular type that instantly raises minute thermal hects to 200 to 400℃.Dynamic coloring for stains, stains, etc. The conditions are clearly different from those described above, and the heating time is significantly longer, and the total amount of thermal energy given to the thermal recording paper is also much larger.

Therefore, even with thermal recording paper that develops color at 80 to 90 degrees Celsius according to static color development, when actually using thermal hect, the color density is often insufficient even when a low voltage is applied. .

As a result of examining various melting point depressing substances based on dynamic color development conditions, the present inventors found that they can be used as sensitizers by melting at a relatively low temperature and adding color-forming colorless dyes and organic color developers to the melt. It has been found that not only are both easily soluble, but also high solubility and high dissolution rate are extremely important quality determining factors.

A sensitizer with high solubility and high dissolution rate σ not only accelerates the time point at which color development starts but also improves the maximum concentration 6 reached.

Only one of the colorless dye and the organic color developer was dissolved, and the sensitizer has insufficient solubility and has a slow dissolution rate, so it is necessary to add a large amount of the sensitizer, even if color development starts at a low temperature in static color development. If the color is too thin, a sufficient sensitizing effect cannot be obtained, and particularly in high-speed printing with short pulses, desired color density cannot often be obtained. For example, in the case of wax-based sensitizers such as waxes having nitrogen-containing substituents, fatty acid amine condensates, fatty acid amides, and methylolated fatty acid amides, their melts contain color-forming dyes. It has almost no ability to dissolve, and only dissolves Bistunol A. Therefore, even if the temperature at which color development starts can be lowered, the desired effect cannot be obtained unless the blending amount is increased.

For this reason, not only is it not possible to obtain a sufficient thermal response to the minute amount of heat in the thermal head, but also problems such as lees adhesion and bleeding of the thermal head, K pull #, and ghost fat tend to occur.

In addition, because thermal recording paper functions as information recording paper, it is unavoidable that it comes into contact with human hands, but the hands and fingers of those who handle it may be exposed to hair products used on a daily basis, oils and fats contained in skin sweat, etc. Since thermal recording paper is often contaminated with oily substances, there are many opportunities for thermal recording paper to become contaminated with these oily substances.

However, thermal recording paper generally does not have sufficient stability against these oily substances, and the density of the colored image in the contaminated area may decrease or disappear, and the color may change if the white background area becomes contaminated. Therefore, the object of the present invention is to provide a heat-sensitive coloring layer containing a basic colorless dye and an organic color developer that has a sufficient dynamic coloring density and that does not allow hair conditioners or oils to adhere. Another object of the present invention is to provide a heat-sensitive recording material with stable colored images.

The present invention is characterized in that a sulfonate compound represented by the following general formula (1) is contained in a heat-sensitive coloring layer containing a basic colorless dye and an organic color developer.

几1-802 0-R2・・・・・・・・・・ （I）(
In the formula, R1 and R2 may each be an alkyl group of 01 to C12, or a 7-chloroalkyl group of 03 to Cto. However, A and B are hydrogen atoms.

Lower alkyl group, lower alkoxy group, nitro group.

Halogen atom, hydroxyl group. Low R alkylsulfonyl group, phenylsulfonyl group. Low i alkylcarbonyl group. Phenylcarbonyl group, lower alkoxycarbonyl group. Phenoxycarbonyl group.

Phenyl group, alkenyl group, benzyloxycarbonyl group, phenylsulfonyloxy group. lower alkylsulfonyloxy s. It represents a lower alkoxysulfonyl group, a funoxysulfonyl group, or a benzyloxysulfonyl group, and A and B may be the same group. m and nV
i is an integer from O to 3, and m and n may be the same. Furthermore, when substituent A is included in both R1 and R2, these two A do not have to be the same group.

The same applies to substituent B and the number of substituents m and n.

) In the explanation of the above general formula (1), the term "lower" which defines an alkyl group and an alkoxy group usually indicates a group containing 1 to 5 carbon atoms. Examples of lower alkyl groups include methyl group, ethyl group, and n-propyl group.

Inglovir group, n-butyl group, 5ec-butyl group.

A tert-butyl group is exemplified, and examples of the lower alkoxy group include a methquine group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and a tert-butoxy group.

Furthermore, in the general formula (1), the alkyl group may be linear or branched, such as a methyl group, an ethyl group, an n-
Propyl group, isopropyl group, n-butyl group, inbutyl group, 5ec-butyl group, hexyl group, octyl group,
Iso-octyl group, nonyl group or dodecyl group are exemplified, and examples of cycloalkyl group include cyclohentyl group, cycloalkyl group p-t
Examples include crt-butylcyclohexyl group and 2-ethylcyclohexyl group.

When considering the melting point range as a heat-sensitive recording material, preferred sulfonate compounds are compounds in which mol and R2 are 7.

Furthermore, when melting point, sensitization and oil resistance are considered, the following types of sulfonate compounds are most preferred.

@)m(l()n Typical sulfonate compounds used in the present invention include, but are not limited to, the following.

3o-sO2-o-@-@ 25 CH3+So2-0 +C1 26CH3+ 802-0 +No2 28 CH3+SOz O〇H2C) 1329 CH
3-@)-802-0 (XOCHs45 Φ and 802-
0 +C/ 66 C/+802-o@ 67 Cl-◇)-8Oz-0sha ct 68 C/+5Oz-0+N0z 70 C1 (X802-0sha CH2CH371Cl +
802-0-@)-0CH373cz 802-0 regret These sulfonate compounds can be used alone or in combination of two or more. In addition, other sensitizers (e.g. dibenzyl terephthalate, benzyl P-benzyloxybenzoate, di-P-tolyl carbonate, P-benzylbiphenyl), stabilizers (e.g. phthalate monoester #gold, salts, P - tertiary-butylbenzoic acid metal salt,
It may be used in combination with nitrobenzoic acid metal salts).

The basic colorless dye used in the present invention is not particularly limited, but trimenylmethane-based, fluoran-based, azaphthalide-based dyes, etc. are preferable, and specific examples thereof are shown below.

Dimethylaminophthalide (also known as crystal violet lactone) Fluoran leuco dye 3-diethylamino-6-methyl-7-anilinoFluorane 3-(N-ethyl-p-tolubuino)-6-methyl-7-anilino Fluoran 3- (N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7-(0,p-dimethylanilino)fluoran 3-pyrrolidino 6- Methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3-dibutylamino-7
-(+1-Chloranilino)fluoran 3-diethylamine-6-methyl-chlorofluoran 3-diethylamino-6-methyl-fluoran 3-cyclohexylamino-6-chlorofluoran 3-diethylamino-7-(o
-Chloranilino)fluorane(3-diethylamino-benzoCa)-fluoranemethothenyl)-3-(
1-x(y-2-methylindol-3-yl)-4-
Azapthalide These dyes can be used alone or in combination of two or more.

On the other hand, examples of organic color developers include Bistunol A, 4-
Hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis-(hydroxyphenyl) sulfides, 4-hydroxy 7-
2-arylsulfone M, 4-hydroxyphenylarylsulfonates, 1,3-di[2-(hydroxyphenyl)-2-propyl]-benzenes, and other color developers are preferred, and specific examples thereof are shown below. shows.

Bisphenol A 4.4'-Impropylidene difunol (0 Nickname: Bisphenol A) 4.4'-Cyclohequinylidene difunol p, p'-
(1-methyl-n-hexylidene) sif-nol 4
-benzyl hydroxybenzoate 4-ethyl hydroxybenzoate 4-propyl hydroxybenzoate 4-ingropyl oxybenzoate 4-butyl hydroxybenzoate 4-butyl oxybenzoate 4-methylbenzyl oxybenzoate 4- and droxyphthalic acid diesters 4-hydroxyphthalic acid dimethyl 4-hydroxyphthalic acid diisoprozel 4-hydroxyphthalic acid dibenzyl 4-hydroxyphthalic acid dihexyl phthalic acid monoesters phthalic acid monobenzyl ester phthalic acid monomonochlorohexyl ester phthalic acid monoester Phenyl esters Phthalic acid monomethyl phenyl ester Phthalic acid monoethyl hunyl ester Staric acid monoalkyl benzyl ester Phthalic acid monohalogen benzyl ester Staric acid monoalkoxybenzyl ester Bis-(hydroxy7jL-nyl)sulunides Bis-(4-hydroxy-3- teri-butyl-6
-methylphenyl) sulfide bis-(4-hydroxy-2,5-dimethylphenyl)
Sulfide bis-(4-hydroxy-2-methy/l/-5-ethylphenyl) sulfide bis-(4-hydroxy-2-methyl-5-inglobylphenyl) sulfide bis-(4-hydroxy-2,3- (dimethyl-7)
Sulfide bis-(4-hydroxy-2,5-diethyl7-yl)
Sulfide bis-(4-hydroxy-2,5-diisopropylphenyl) sulfide bis-(4-hydroxy-2.3.6-)limethylphenyl) sulfide bis-(2,4,5-)lihydroxyphenyl) sulfide Bis-(4-hydroxy-2-cyclohexyl-5
7 -Nil)
Sulfide bis-(4-hydroxy-2~tcrt-octyl-5
-methylphenyl) sulfide 4-hydroxytuniaryl sulfones 4-hydroxy-4'-isopropoxysulfone 4-hydroxy-4'-methyldiphenyl sulfone 4-hydroxy-4'-n-7'' thyloxydiphenyl sulfone 4
-Hydroxyphenylbenzene sulfonate 4-Hydroxy 7-enyl p-tolylsulfonate 4-Hydroxy 7-yl mesotylene sulfonate 4-Hydroxyphenyl p-chlorobenzenesulfonate 4-Hydroxyphenyl-p-tert-butylbenzenesulfonate 4-hydroxyphenyl-p-impropoxybenzenesulfonate 4-hydroxytunyl-1'-naphthalenesulfonate 4-hydroxyphenyl-2'-naphthalenesulfonate tulobil]-benzene 1,3-di( :2-(4-hydroxy-3-alkylphenyl)-2-propyl]-benzene 1,3-di(2-(2,4-dihydroxy7-nyl)-
2-1a pyru]-benzene 1.3-di[2-(2-hydroxy-5-methylphenyl)-2-glovyl]-benzene and others - p-tert-butylphenyl 2.4-dihydroxybenzophenone novolak type phenolic resin 4-hydroxyacetophenone p-phenylphenol benzyl-4-human mixyphenylacetate p-benzyl 7-nol These color developers can be used alone or in combination of two or more.

The features of the heat-sensitive recording paper containing a sulfonate compound in the heat-sensitive recording layer are summarized as follows.

It has excellent thermal response to the small amount of heat produced by short pulses.

■Compared to conventional wax-based sensitizers, a sufficient sensitizing effect can be obtained with a smaller amount.

6) The image is stable against adhesion of hair styling products and oils and fats.

(4) The ground color is stable.

The above-mentioned organic color developer, basic colorless dye, and sulfonate compound are atomized to a particle size of several microns or less using a grinder such as a thorn mill, attritor, or sand grounder, or an appropriate emulsifier, and then used for the purpose. Depending on the application, various additive materials may be added to form a coating liquid. This coating liquid usually contains polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, tenranes, styrene-maleic anhydride copolymer, buvinyl acetate maleic anhydride copolymer, styrene-xtadiene copolymer. binders such as kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, calcium carbonate,
Inorganic or organic fillers such as magnesium carbonate and aluminum hydroxide are added, but mold release agents such as fatty acid metal salts, lubricants such as waxes, and ultraviolet absorbing agents such as pensifunone and triazole are used. A water-proofing agent, a dispersing agent, an antifoaming agent, etc. can be used. By applying the coating liquid to paper and various films, the desired heat-sensitive recording paper can be obtained.

The amount of the sulfonate compound and the types and amounts of other various components used in the present invention are determined according to the required performance and recording suitability, and are not particularly limited, but usually for 1 part of the basic colorless dye, The organic color developer is 3 to 10 parts, the sulfonate compound is 0.5 to 10 parts, and the filler is 1 to 2 parts.
0 part is used, and the binder is suitably 10 to 25 parts based on the total solid content.

Next, typical examples will be described to specifically explain the present invention.

[Example 1] Solution A (dye dispersion) Bi (developer dispersion) Solution C (sensitizer dispersion) The canned solution of the above composition was ground with an attritor to a particle size of 3 microns.

Next, the dispersion liquid is mixed in the proportions shown below to prepare a coating liquid.

The amount of the above coating liquid applied to one side of the 50g/m" base paper was approximately 6.
．． 0g/? The sheets were coated and dried so as to have a smoothness of 200 to 600 seconds using a super calender. Shown in 1.

[Example 2] Solution D (dye dispersion) Solution E (developer dispersion) Grade 1 (sensitizer dispersion I) Each solution of the above composition was ground with an attritor to a particle size of 3 microns. Next, mix the dispersion liquid in the following ratio to make a coating liquid.The above coating liquid is applied to one side of a 50g/m" base paper in an amount of approximately 6.
．． 0 g/m' and dried, and the smoothness was 200 to 600 using a Lasper calender.
Processed to be seconds. A quality performance test was conducted on the obtained black-colored thermal recording paper. Color density: Measured with a Macbeth densitometer (RD-, using a 104° amber filter. The same applies hereinafter) Note (2) Static color development Concentration: 1 on a hot plate heated to 105°C
Press for 5 seconds at a pressure of 0 g/cdl and measure the color developed using a Macbeth densitometer. - Note (3) Dynamic color density; Tokyo Shibaura Electric - Heat-sensitive facsimile IJ ('P-480OA is used, pulse width 0.
The image density recorded in G If mode for 7 ms was measured using a Macbeth densitometer.

Note (4) Ground color: Measure the uncolored area with a Macbeth densitometer.

Note 6) Heat resistance: Ground color density after being left for 24 hours under high temperature drying conditions at 60°C.

Note (6) Humidity resistance: Ground color density after being left for 24 hours under high humidity conditions of 40°C, 90%R).

Note (7) Color density after oil treatment: After spreading a droplet of castor oil (0, smg) dropped onto a glass plate with a syringe to a size of 40 cm, use a 1 cm and 1.5 crn rubber stamp to measure the above. (3) The color was transferred to the printed surface. After being left for 71 days, the color density and strength of the metastatic area was measured using a Macbeth densitometer.

Note 8: Remaining rate of color density; calculated using the formula below.

Tables 1 and 2 show that the thermal recording paper of the present invention using a sulfonate compound has significantly higher dynamic color density and better ground color and ground color storage stability than the comparative example using stearic acid namide. It can be seen that the oil resistance is also excellent.

Patent applicant: Jujo Paper Co., Ltd.

Claims (1)

[Scope of Claims] (1) A heat-sensitive recording sheet provided with a coloring layer containing a basic colorless dye and an organic five-color agent, in which the coloring layer contains a sulfonate compound represented by the following general formula (I). A thermal recording paper characterized by:几1-802-OR2・・・・・・・・・(I) (In the formula, 几l and R2 are each an alkyl group of Cl-012 + a cycloalkyl group of L3 to Cto. am and 几2 are the same may be a group.However, A and B are a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, a halogen atom, a hydroxyl group, a low i alkylsulfonyl group. Low i alkylcarbonyl group, phenylcarbonyl group, low M flucooxycarbonyl group, phenoxycarbonyl group. Phenyl group, alkenyl group, benzyloxycarbonyl group, phenylsulfonyloxy group. Lower alkylsulfonyloxy group, lower alkoxysulfonyl group, phenoxy Represents a sulfonyl group or a benzyloxysulfonyl group. A and B may be the same group. m and n are integers of θ to 3, and m, ni
j. They may be the same. Furthermore, when substituent A is included in both R1 and R2, these two A do not have to be the same group. The same applies to substituent B and the numbers m and n of substituents. )(2) The heat-sensitive recording paper according to claim 1, characterized in that it is represented by the sulfonate represented by the general formula (1). (3) The heat-sensitive recording paper according to claim 1, characterized in that it is represented by the sulfonate represented by the general formula (1). (k) The heat-sensitive recording paper according to claim 1, characterized in that it is represented by a sulfonate represented by the general formula (I).