JPS61181680A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To improve the handleability and running property of a thermal record ing paper by discretely including a composition containing cellulose powder and an oil absorptive pigment in thermal color-forming layer. CONSTITUTION:A cellulose powder, whose grain size is such as to pass 90% or more through a screen (elutriation) of 250 mesh, preferably through a screen of 300 mesh, and an oil absorptive pigment, whose oil absorption is 30ml/100g or more (by JIS-K-5101) preferably, are mixed. The composition so formed is further mixed with a colorant, a developer, and a heat meltable substance as needed in an amount of corresponding to 10-200wt% of the total amount of colorant, developer, and heat meltable substance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a thermal recording paper, and more particularly, it uses an electron-donating dye precursor and an electron-accepting compound that develops a color by reacting with the dye precursor. Regarding thermal recording paper.

(Prior Art) Thermosensitive recording paper is a paper that records images by utilizing physical and chemical changes in substances caused by thermal energy, and a large number of processes are being studied.

So-called wax-type thermal recording paper has been known for a long time as a paper that takes advantage of the physical changes in substances caused by heat, and is used for things such as heart drawings. Further, as for those utilizing chemical changes caused by heat, those based on a special coloring mechanism have been proposed, and in particular, one called two-component coloring type thermosensitive recording paper is representative.

Two-component color-forming thermosensitive recording paper is made by dispersing two types of heat-reactive compounds in the form of fine particles, mixing them with a binder, etc., so that the two types of heat-reactive compounds are separated by the binder, etc., and forming a support. One or both of them are melted and brought into contact with each other by heating, and the coloring reaction that occurs is used to obtain records. These two types of heat-reactive compounds are
Generally speaking, these compounds are called electron-donating compounds and electron-accepting compounds.

These two-component color-forming thermal recording papers are: (1) secondary coloring and no need for color printing, (2) paper quality close to ordinary paper, and (3)
) It has many advantages as a recording sheet, such as being easy to handle. In particular, those using dye precursors as electron-donating compounds have further advantages such as (4) high color density, and (5) ease of producing thermal recording paper with various color hues, and have great utility value. Hey. Therefore, it is most commonly used as a heat-sensitive recording material.

In recent years, with the development of electronic technology, facsimiles, measuring instruments,
Thermosensitive recording paper is attracting attention as a means for printing out information using printers and the like.

As facsimile recording devices have become faster at printing, faster printouts have been achieved using heat-sensitive elements, and devices have become more compact, heat-sensitive recording sheets are required to respond in a shorter time, that is, to have higher recording sensitivity.

In accordance with the demand for improved recording sensitivity of heat-sensitive recording sheets, there are increasing demands for quality improvements in handling and running properties.

Handling performance refers to "friction fog," which develops color when fingernails rub against it and stains the recording surface, and "pressure fog," which develops color when the recording surface is pressed with a calender roll, etc. Runability refers to fax machines, printers, etc. When continuous printing is carried out, color-forming substances that are molten when heated are transferred and adhered to the thermal head (so-called 1-head contamination), "deterioration of the printed image" that occurs as a result of increased head contamination, and printing problems caused by the thermal head being applied and recording. This refers to the so-called "sticking sound", which is an abnormal sound that occurs during running due to adhesion between sheets of paper.

Various known methods have been proposed to improve the handling and running properties.

The surface of the heat-sensitive recording layer is coated with wax (
Special public Sho g@-27♂? θ) Method of overcoating the surface of the heat-sensitive recording layer with wax and polymer (Japanese Patent Application Laid-Open No. 417-3
/ Riyo No. 2) Method of containing heat-sensitive recording sheet wax and amide (Special Publication Sho!/-27t99) Method of containing X-class fatty acid metal salt (JP-A No. 14-10 Data θ) Method of adding starch particles (Tokukosho!/-694t7)
Method containing urea resin particles (JP-A-ShojK-, 2j♂4
tf) Oil absorption amount? Otd // A method of containing a highly oil-absorbing pigment with θθ of 7 or more (% Kaisho!!-74229), a method of containing calcium carbonate and kaolin as the pigment (Japanese Patent Kokai Sho, f4-273ri No. 3), etc. .

However, these methods lower the print density as a heat-sensitive recording material, reduce the drying properties of the water-based stamp ink on the surface of the recording layer, deteriorate the abrasion resistance of the thermal head, and reduce the storage stability of the printed area. It cannot be said to be sufficient because it has disadvantages such as a decrease in friction and an increase in sticking noise, and the effect of preventing friction fogging cannot necessarily be said to be sufficient.

(Objective of the Invention) The object of the present invention is to provide a thermal recording material with improved handleability and runnability while meeting the various requirements for thermal recording paper as described above, especially various performances such as print density. It is.

(Structure of the Invention) An object of the present invention is to provide a heat-sensitive recording material in which a support is provided with a heat-sensitive recording layer containing an electron-donating dye precursor and an electron-accepting compound, on the surface of a cellulose paratate layer and/or a heat-sensitive coloring layer. This was achieved by making them exist discontinuously.

The cellulose powder used in the present invention is generally made by mechanically shredding pulp or by mechanically shredding pulp after acid hydrolysis, but either method can be used. .

The particle size of cellulose powder is a particularly important characteristic in the present invention. Specifically, the sieve passing rate by the water sieve method is 2!0.
The mesh sieve passing rate is 0 or more, preferably 300 mesh sieve passing rate? θ% or more is preferable. In terms of bulk specific gravity, θ is preferably 2j51/cc or more, preferably o, 3py/cc or more.

The amount of cellulose powder applied is 0.2F/m
2 or more, preferably 0, j F / m 2 ~ j
F / m 2 Te with θ / P / rn 2 or less, the effect on the purpose of the present invention becomes small, ry /
mz or more is not preferable because the print density decreases significantly due to a decrease in flatness, and the viscosity of the coating liquid also increases, resulting in a decrease in manufacturing suitability.

The oil absorption amount used in combination with the above cellulose powder is 3 owt/1o according to JIS-t/θ/.
oy or more, and the amount added is preferably /Q to 00% by weight of the total of the color former, color developer, and thermofusible substance.

Specific examples of oil-absorbing pigments include calcium carbonate, aluminum hydroxide, barium carbonate, barium sulfate, talc,
waxite, kaolin, calcined kaolin, calcium silicate,
Examples include aluminum silicate, zinc oxide, diatomaceous earth, amorphous silica, lithopone, titanium oxide, urea-formalin resin filler, polyethylene filler, and the like.

Next, the judgment regarding the thermal paper of the present invention will be described.

The thermal paper of the present invention is produced by separately applying an electron-donating dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer) to a ball mill, a sand mill, an attritor, a three-roller mill, or the like. is used to disperse the particles to an average particle size of 0.7 to 10 microns in a water-soluble polymer solution. Also, when it is necessary to improve thermal sensitivity, the melting point is j00C or more/! A thermofusible substance having a temperature of θ0C or less is dispersed in a similar manner. The thermofusible substance may be mixed and dispersed with a color former or developer.

A color forming agent, a color developer, and a thermofusible substance if necessary are mixed after being dispersed, and then the cellulose powder of the present invention and an oil-absorbing pigment are mixed. The cellulose powder may be mixed in advance after being dispersed in an aqueous medium.

Further, a colorless to light-colored wax dispersion, a mold release agent dispersion, etc. are added as necessary.

The preferred ratio of color former and color developer during mixing is /:
θ,! No/:! It is. Further, when a thermofusible substance is added, it is preferably added in an amount of jo to 200% by weight based on the color developer.

When adding wax or mold release agent, use the coloring agent! Weight percent to 300 weight percent is preferred.

Examples of the coloring agent used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds. Some examples of these include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e. crystal violet lactone);
j,j-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(/.

conemethylindol-3-yl)phthalide, 3-(
p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3-bis -(/,2-dimethylindol-3-yl)-! -dimethylaminophthalide, 3
,3-bis(/,2-dimethylindol-3-yl)
-6=dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-r-dimethylaminophthalide, 3,3-bis-(2-phenylindole-3
-yl)-yo-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(/-methylpyrrole-choyl)-ot-dimethyl-aminophthalide 3-diethylamine-7-medoxyfluorane, 3-diethylamine −
6-Medoxyfluorane, 3-diethylamine-7-cybenzylaminofluorane, 3-diethylamino-go-
Methyl-7-anilinofluorane, 3-N-ethyl-N
-tolylamino-ot-methyl-7-anilinofluorane, 3-N-methyl-N-tolylamino-bu-methyl-7
-anilinofluorane, 3-piperidino-6-methyl-
7-anilinofluorane, 3-diethylamino-ot-chloro-7-anilinofluorane, 3-N-cyclohexyl-N-methylamino-ot-methyl-7-anilinofluorane, 3-piperazino- ≦-Methyl-7-(p-methylanilino)fluoran, 3-diethylamine-7-(
o-chloroanilino)fluoran, 3-diethylamino-7-butylaminofluoran, 3-diethylamine-
7-diphenethylaminofluorane, 3,7-bis(methyltolylamino)fluorane, 3-piperidino-7-
Phenethylaminofluorane, 3-diethylamino-2
-Phenylfluorane, 3 diethyl 7mi/-7,! - Benzofluorane, etc.

These may be used alone or in combination for the purpose of color tone adjustment.

The color developer used in the present invention includes a fetol compound,
Examples include hydroxybenzoic acid derivatives and salicylic acid derivatives. Examples include co,2-bis(ri'-hydroxyphenyl)propane (bisphenol k), 2,2-bis(4t-hydroxyphenyl)pentane, co,2-bis(4tF-hydroxy-3p,6p -dichlorophenyl)propane, /, /-bis(4t'-hydroxyphenyl)cyclohexane, λ, 2-bis(ri'-hydroxyphenyl)hexane, /, /-bis(Z'-hydroxyphenyl)propane, /, / -bis(4t/-hydroxyphenyl)butane, /,/-bis(qt-hydroxyphenyl)pentane, /,/-bis(ri'-hydroxyphenyl)hexane, /,/-bis(4t r-hydroxyphenyl) Hebutane, /,/-bis(4t'-hydroxyphenyl)octane, /,/-bis(ri'-hydroxyphenyl)-2-methyl-pentane, /,/-bis(couhydroxyphenyl)-coethylhexane ,/.

/-bis(4t/-hydroxyphenyl)dodecane p-
') Milphenol, p-phenylphenol, benzyl p-hydroxybenzoate, butyl p-hydroxybenzoate, phenethyl p-hydroxybenzoate, 3. j-di-tert-butylsalicyl M, 3. Examples include r-di-α-methylbenzylsalicylic acid and 3-α-methylbenzylsalicylic acid. Zinc and aluminum salts can also be used as salicylic acid derivatives.

Examples of the thermofusible substance used in the present invention include higher fatty acid amides, benzoic acid ester derivatives, naphthol derivatives, naphthoic acid derivatives, and urea derivatives. Specifically, stearic acid amide, palmitic acid amide, oleic acid amide, erucic acid amide, ethylene bisstearamide, benzyl p-benzyloxybenzoate, henzyl p-butoxybenzoate, β-naphthol benzyl ether, α- Naphthol benzyl ether, α-hydroxy-
β-naphthoic acid phenyl ester, β-hydroxy-α
-naphthoic acid phenyl ester, β-naphthoic acid phenyl ester, β-naphthol-(p-chlorobenzyl)
Examples include ether.

Specific examples of wax include polyethylene wax, paraffin wax, microcrystalline wax, carnauba wax, and the like.

As the mold release agent, metal salts of higher fatty acids are preferred, such as zinc stearate, aluminum stearate, calcium stearate, and the like.

When dispersing color formers and color developers, water-soluble polymers are added as protective colloids. Compounds that dissolve at least 10% are desirable, and specific examples include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, and styrene.
Maleic anhydride copolymer salt, ethylene-maleic anhydride copolymer salt, inbutylene-maleic anhydride copolymer salt, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acrylic amide copolymer, methacrylic amide copolymer Examples include coalescence, polyamide resin, etc.

These water-soluble polymers also serve as a binder when coating a heat-sensitive material on a support.

The heat-sensitive coating liquid prepared as described above is applied onto a support to form heat-sensitive recording paper.

The preferred coating weight is 3 y/m 2 to 205 y/m 2 as solid content! /m2, more preferably 4ty/m2
It is ♂ri/m2.

Supports include base paper, coated paper coated with pigments, synthetic paper, and film. The heat-sensitive coating liquid is applied and dried by a conventional coating method such as a bar coater, blade coater, air knife coater, roll coater, Clavia coater, etc., and is finished by calendering if necessary.

Calendaring is particularly important in the present invention.

Calendaring is carried out using a machine calender, supercalender, or thermopressure. When calendering is used, the smoothness of the coated surface must be 20θ seconds or more, 2.
000 seconds or less, more preferably 000 seconds or more/000 seconds or less.

(Examples of the Invention) Examples of the present invention are shown below, but the present invention is not limited thereto.

Example/ As an electron-donating dye, =-anilino-3-chloro-6
-Dinithylaminofluorane 209L! Disperse with Tivoli vinyl alcohol (Kuraray PVA/θri aqueous solution 1007 in a Pall mill overnight) to obtain Solution A.

2.2-bis(p-hydroxyphenyl)furopane j0
y! Tivolivinyl alcohol aqueous solution O0θ is mixed with stearic acid amide toyokoichiseiyo to obtain liquid B.

Cellulose para9'- (Sanyo Kokusaku Pulp■ KC-Flock W-3oo Bulk specific gravity 0.3♂y/c c3θ
30 pieces (90 pieces or more of the amount passing through the mesh) were dispersed with 200 jl of 7% sodium hexametaphosphate aqueous solution using a homogenizer to obtain liquid G.

Calcined kaolin (Engelhardt Ansilex90
Oil absorption, rtvt/10 oy) toy was dispersed with a 720 g of sodium hexametaphosphate solution using a homogenizer to obtain liquid D.

Mix A liquid, B liquid, G liquid, and D liquid and prepare 3014 dispersion of zinc stearate (Chukyo Yushi Hydrin Z-7) 40
Add p to make a heat-sensitive coating liquid. This is the basis weight! Coat with a Meyer bar so that the dry coating amount is 3.717 m2 on high-quality paper with a 7 m2 of θ. It was dried at 0°C for 1 minute, calendered, and finished to a surface smoothness of 600 seconds (Beck).

Example 20 cocellulose powder (Sanyo Kokusaku Pulp ■ Pulp floc W-a bulk specific gravity 0.4t≦p/CC4θ0 mesh passing rate 90% or more) was dispersed with a homogenizer together with sodium hexamecrate/thi aqueous solution 3θθ to make Solution E. shall be.

Calcium carbonate (Shiraishi Calcium ■Univer 70 oil absorption rrMl/10Oy)≦θ1 is dispersed with sodium hexametaphosphate/thi aqueous solution/2θ in a homogenizer to obtain liquid F.

Mix A liquid, B liquid, E liquid, and F liquid described in Example/,
30-dispersion of zinc stearate (Chukyo Yushi Co., Ltd.)
Add Hydrin Z-7) toy to make a heat-sensitive coating liquid. The dry coating amount of this on high-quality paper with a tsubo of 1 lOy/m2!
, y/m 2 with a Mayer bar and dried for 1 minute at to 0c. Surface temperature! ! Surface treatment was performed by passing the paper through a pressure device (linear pressure KP/em) consisting of a combination of a hard chrome plated roll and a hard rubber roll (Shore hardness 10) heated to 0C so that the coated surface was in contact with the chrome plated roll. I did it. The surface smoothness is 4t! It was θ seconds (Beck).

Example 3 Cellulose powder (Yamaba Kokusaku pulp #KC-flock w-4too bulk specific gravity o, 4t317cc4t00 mesh passing amount 90 cm or more) j0 was mixed with sodium hexametaphosphate/thi aqueous solution 3! Disperse with a homogenizer along with θ to obtain liquid G.

Calcined kaolin (Nilgerhard Ansilex 90)
209. Calcium silicate (Mizusawa Chemical ■Mizukashiru P/
j (oil absorption/30 dl/100 y) 207 is dispersed with a homogenizer together with 10 ops of sodium hexametaphosphate/thi solution to prepare H solution.

Mix the A liquid, the B liquid, the G liquid, and the H liquid described in Example/,
Zn stearate 3o @ dispersion (Chukyo Yushi Hydrin Z-7) toy 3c dispersion emulsion of paraffin wax (Chukyo Yushi Hydrin D-337) 1
Add 0θ to make a heat-sensitive coating liquid. This is the basis weight "j'
/ m 2 on high-quality paper with a dry coating weight of 4.197
m2 with a wire bar, dried at RO 0C for 1 minute, and supercalendered (linear pressure/04
/cm) and the surface smoothness is 00 seconds (Beck).
It was finished so that.

Example: Electron-donating dye front body, no-anilino-3-methyl-
-N-Cyclohexyl-N-methylaminofluorane/θ-,/θ-polyvinyl alcohol (degree of saponification 9/H, degree of polymerization 10θ0) aqueous solution -239F and 22R of water were dispersed in a ball mill overnight to form a dispersion. I got an A.

Similarly, benzyl p-oxybenzoate 10y, 2゜2'-
methylene-bis-(gu-methyl-t-tert-butylphenol) ty1 calcium carbonate (Shiraishiko $ Brilliant/J)/, tll, 10% polyvinyl alcohol (saponification degree 9!, polymerization degree 1000) aqueous solution 25 ml Both water toy and L were dispersed in a ball mill overnight and the dispersion liquid (
B) was obtained.

The dispersion liquid (A) and the dispersion liquid (B) are mixed at a weight ratio of /:3, and further, the zinc stearate dispersion liquid is added at a ratio of /% to the mixed liquid -○○no. 1 was added and sufficiently dispersed to prepare a heat-sensitive coating liquid.

The prepared coating liquid was applied onto a base paper having a basis weight of 4175E/m20 so that the solid content was 7m2, and
The mixture was dried at °C for 7 minutes to form a base thermosensitive recording paper.

On this heat-sensitive coloring layer, a coating layer coating solution prepared as below was applied so as to obtain a coating amount of 2゜P/m2 in terms of solid content. Dry at θ0C for 2 minutes to form a coating layer, perform calendering, and achieve smoothness! θ seconds (JIS
A thermal recording paper of the present invention having P♂//9) was obtained.

Preparation of coating layer coating solution Silicon-modified polyvinyl alcohol aqueous solution 70y (copolymer of vinyltrimethoxysilane and vinyl acetate, 0° silicon as vinylsilane unit! Contains molti,
Degree of saponification of vinyl acetate units r.

3chi, degree of polymerization approximately! θθ) 20% colloidal silica /2,17 (Nichiro Kagaku Kogyo ■Snowtex C) 60% kaolin dispersion jl (Kaolin oil absorption 3t/y) -2/chiparaffin wax dispersion Ko,! (average carbon number 30) 30% zinc stearate dispersion / Ono Example 3
A coating layer coating liquid was prepared by mixing 20y or more of the cellulose powder dispersion shown above.

Comparative Example/Example/Example/Examples were carried out in the same manner as in Comparative Example/Example/ except for the following changes.

Coating amount (solid content) without calcined kaolin added: 4t, ♂y/m 2 Comparative Example λ The same procedure as in Example 1 was carried out except for the following changes.

Coating amount (solid content) without addition of cellulose powder: j, 617 m2 Comparative experiments Comparative experiments on the heat-sensitive recording papers obtained in Examples and Comparative Examples were conducted as follows.

1) Chromogenic main scanning! Macbeth R
The color former density (initial density) after recording of D-rt4 was measured using a type reflection densitometer (using a visual filter).

2) Handling friction fog ◎Even if thermal paper is rubbed on a hard object such as a glass plate, almost no color develops.

○Do not rub it on a glass plate, etc. Crab color develops, but soft paper such as cardboard If you rub it on a seafood No color develops.

ΔDo not rub it on cardboard, etc. Crab color develops.

×Color develops by rubbing it on cardboard, etc. do.

3) Printing characteristics Stain caused by printing When printing was performed using a facsimile machine, the presence or absence of a trail-shaped stain that appeared in the unprinted area after the colored area was visually determined.

4) Running suitability of thermal facsimile Running suitability Thermal recording paper made from a thermal facsimile (Matsushita Densen UP-920) was tested for printing, running sound, and adhesion to the head.

The stains caused by the above printing, running noise, and adhesion to the head were evaluated in the following stages.

◎Extremely good ○ Good △　No head closure in practice × Practical problems Table 7 shows the evaluation results of the thermal recording paper according to the present invention.

It can be seen that extremely excellent results are shown.

Claims (1)

[Claims] In a thermosensitive recording paper provided on a support with a thermosensitive coloring layer containing as a main component an electron-donating dye precursor and an electron-accepting compound that reacts with the dye precursor to form a color, in the thermosensitive coloring layer and/or The surface of the heat-sensitive coloring layer contains cellulose powder and the oil absorption amount according to JIS K-5101 method is 30ml/10
A heat-sensitive recording paper characterized in that a composition containing 0 g or more of an oil-absorbing pigment is discontinuously present.