JPS63222888A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having favorable dot reproduction properties and high printing quality, by incorporating a heat-fusible substance having a melting point not lower than a specified temperature in each of an undercoat layer and a thermal color forming layer. CONSTITUTION:A heat-fusible substance having a melting point of at least 50 deg.C is incorporated in each of an undercoat layer and a thermal color forming layer, in a thermal recording material comprising the undercoat layer with a pigment and a binder as main constituents on a base and the thermal color forming layer on the undercoat layer. The pigment may be calcium carbonate, barium sulfate, a polyethylene resin powder or the like, while the binder may be a water-soluble high molecular weight compound or a water-insoluble binder. The amount of the binder used is 3-100% based on the pigment. The heat- fusible substance may be beta-naphthyl benzyl ether, paraffin wax, 1,1,3-tris(2- methyl-4-hydroxy-5-t-butylphenyl)butane or the like, and the amount of the heat fusible substance to be added is preferably 0.5-20wt.% based on the undercoat layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having a heat-sensitive coloring layer and an undercoat layer.

(Prior Art) Regarding thermal recording, many methods have been known for a long time. For example, heat-sensitive recording materials using electron-donating dye precursors and electron-accepting compounds are
It is disclosed in Tokko Sho≠j-4'/No. 60, etc. In addition, heat-sensitive recording materials using diazo compounds are produced by Tokukai Sho! It is disclosed in the 1996 issue of Tar 1yort et al. In recent years, these thermal recording systems have been applied to a wide range of fields such as facsimiles, printers, and labels, and the needs for them have been expanding. Along with this, characteristics that were not so required in the past have come to be required for thermosensitive recording. One of these is the reproducibility of printed dots. Generally, thermal recording paper.

Printing is performed by heating with a tiny heating element called a thermal head, which is about 100 μm x 200 μm corner.
At this time, it has been found that it is important to be able to faithfully reproduce the shape of the micro heating element as a color forming element in order to obtain high printing quality. This is called print dot reproducibility.

(Object of the Invention) An object of the present invention is to provide a heat-sensitive recording material with good dot reproducibility and high printing quality.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material in which an undercoat layer containing a pigment and a binder as main components is provided on a support, and a heat-sensitive coloring layer is provided on the nine undercoat layers. Melting point for both heat-sensitive coloring layers! This is achieved by a heat-sensitive recording material characterized by containing a thermofusible substance with a temperature of O0C or higher.

As pigments that can be used in the undercoat layer of the present invention, all general organic or inorganic pigments can be used, but special KJIS pigments can be used.
- Oil absorption defined by Kj101 is 4AOω/ / 00
7 or more is preferred, and specific examples include calcium carbonate, barium sulfate, titanium oxide, talc, waxite, kaolin, calcined kaolin, aluminum hydroxide, amorphous silica, urea-formalin resin powder, polyethylene resin powder, etc. Can be mentioned.

Binders used in the undercoat layer include water-soluble polymers and water-insoluble binders, and the binders may be used alone or in combination of two or more.

Examples of water-soluble polymers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, and Butylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol,
Examples include carboxy-modified polyvinyl alcohol and polyacrylamide.

Examples of water-insoluble binders include synthetic rubber latex or synthetic resin emulsion, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. It will be done.

The amount of binder used is 3 to io relative to the pigment.

h, preferably j-10%.

Specific examples of organic compounds having a melting point of IO"c or higher used in the present invention are shown below. Ether, ester, and amide compounds R3C0NHR4 (III) represented by the following general formulas (I) to (Ill/), in which R1, R2 and R3 are an alkyl group or an aryl group,
R4 is a hydrogen atom, an alkyl group or an aryl group, Rs is a divalent group, A and B may be the same or different < 0
* Co 2 + or S, X, Y.

z, x', y', and z' may be the same or different and represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, a halogen atom, an alkyloxycarbonyl group, an acyloxy group, or an alkylthio group.

Further, X and Y, or X' and Y' may be connected to form a ring.

In addition, an alkyl group represents a saturated or unsaturated alkyl group or a cycloalkyl group, and these have a substituent such as an aryl group, an alkoxy group, an aryloxy group, a halogen atom, an acylamino group, an aminocarbonyl group, or a cyano group. Also, the aryl group represents a phenyl group, a naphthyl group, or a heteroaromatic ring group, and these represent an alkyl group, an alkoxy group, an aryloxy group, a halogen atom,
Nitro group, cyano group, substituted carbamoyl group, substituted sulfamoyl group, substituted amino group, substituted oxycarbonyl group,
It may have a substituent such as a substituted oxysulfonyl group, thioalkoxy group, arylsulfonyl group, f or phenyl group.

Among the groups represented by R1, R2, R3, and R4 in the above formula,
An alkyl group which may have a substituent having a carbon number/-20 and an aryl group which may have a substituent having 6 to 20 carbon atoms are preferred, and examples of the substituent include an aryl group, an alkyl group, Alkoxy group, aryloxy group,
Among the groups represented by R5, rogene atoms etc. are preferable,
An alkylene group, an alkylene group having an ether bond, an alkylene group having a carbonyl group, an alkylene group having a halogen atom, an alkylene group having an unsaturated bond, and more preferably an alkylene group and an alkylene group having an ether bond.

Specifically, p-benzyloxybenzoic acid pencil, β
-f7f rubenzyl ether, β-naphthoic acid phenyl ester, l-hydroxyconaphthoic acid phenyl ester, β-naphthol (p-chlorobenzyl) ether, β-naphthol (p-methylbenzyl) ether,
α-Naphthylbenzyl ether, l, ≠-butanediol-p-methylphenyl ether, /, heaptanediol-p-inpropylphenyl ether, l.

Hiro-butanediol-p-t-octylphenyl ether, -monophenoxy-/-p-)lyluoxyethane, l-7 dinoxy 2-(Hiro-ethylphenoxy)ethane, l-7 dinoxycor (≠-chloro phenoxy)ethane, /, 4A-butanediol diphenyl ether,
(4A, l -methoxyphenylthio)ethane, phenyl benzoate x sulfur, p-methoxyphenyl benzoate? /', Am, I fragrant-p-/lorophenyl ester.

Terephthalic acid dibe/dyl ester, benzoic acid (β-p-
phenylphenoxyethyl) ester, phenoxyacetic acid-p-/rollophenyl ester, phenoxyacetic acid-p-
Methyl phenyl ester, phenoxyacetic acid-β-naphthyl ester, N-benzylbenzamide, N-octadecylbenzamide, N-benzylphenyl acetate amide,
Examples include N-phenylstearic acid amide.

Waxes. Specifically, polyethylene wax, carnauba wax, PA? Examples include fin wax, microcrystalline wax, camphoria wax, and montan wax.

Preferred examples of phenol derivatives, particularly hindered phenol compounds, include compounds represented by the following general formulas (V) to (■).

(In the formula, R1 is a branched alkyl group having 3 to 1 carbon atoms, R2 is hydrogen or a branched alkyl group having 3 to 3 carbon atoms, R3 is hydrogen or an alkyl group having 1 to 3 carbon atoms, R number represents hydrogen or an alkyl group having 1 to 3 carbon atoms, R5, R,, R7 represents hydrogen or an alkyl group having 1 to 3 carbon atoms, and R8 represents hydrogen or an alkyl group having 1 to 3 carbon atoms. , R3 is a branched alkyl group having 3 to r carbon atoms.

R2 and R4 represent an alkyl group having 1 to t carbon atoms, a baytelene group or a cyclohexylene group, n is an integer of Q to 3, R5 and R6 are hydrogen or an alkyl group having a carbon number of /~ represents. ) (In the formula, R1 and R4 are branched alkyl groups having 3 or more carbon atoms, and R2, R3, R,, R, are hydrogen or alkyl groups having /~r carbon atoms.

m is an integer between θ and 3.

R7 and R8 represent hydrogen, an alkyl group having /-r carbon atoms, or a cyclic tamethylene group formed by bonding R7 and R8. ) (In the formula, R1 and R2 are branched alkyl groups having 3 to t carbon atoms, Z is -NH-1-0 (CH2)n- (where n is /
-j represents an integer), i represents an integer /-4C. However, when i=/, W represents an alkyl group having a carbon number of /-/r, R4 when i=co represents hydrogen or an alkyl group having a carbon number of /-r, and j represents an integer from 0 to r. ), i-3, W is )CRs (where R
5 represents hydrogen or an alkyl group having carbon number/-4. )
, i=Hirono's and representative examples of phenol derivatives represented by the above general formulas (V) to (■) are shown below.

(A) The phenol derivative represented by the general formula (V) is 1,/,! −) Lis(comethyl-≠-hydroxy-j
-tert-butylphenyl)butane, l.

1I3-tris(2-ethyl-≠-hydroxy-j-t
ert-butylphenyl)butane, /, 1°3-tris(3,!-di-tert-butylphenyl-hydroxyphenyl)butane, l,! , 3-tris(comethyl-≠-
Examples include hydroxy-t-tert-butylphenyl)pro/contain.

(B) As the phenol derivative represented by the general formula (M), co, co'-methylenebis(4-tert-butyl-≠
-methylphenol), Kotsu2'-methylene bis(4
-tert-butyl-Hiro-ethylphenol) and the like.

(C) As the phenol derivative represented by the general formula (■), ≠1μ'-butylidene-bis(A-teft-butyl-
3-methylphenol)4A, φ'-thiobis(3-
methyl-4tert-butylphenol).

(D) Examples of the phenol derivative represented by the general formula (■) include the following.

The thermofusible substances may be used alone or in combination. The amount of these thermofusible substances added is determined by the Q of the undercoat υ layer.
, j weight percent or more and 20 weight percent or less. A surfactant or the like may be further added to the undercoat layer.

Next, a typical thermosensitive color forming layer of the present invention will be described.

-For example, in a system using an electron-donating dye precursor (hereinafter referred to as a color former) and an electron-accepting compound (hereinafter referred to as a color developer), the color former and color developer are each separately processed by a ball mill, a sand mill, etc. A heat-sensitive coating liquid can be obtained by dispersing to micron size or less and mixing.

The color former, color developer, and the thermofusible substance of the present invention are generally dispersed with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol. In addition to this, it may also be dispersed at the same time.

These dispersions are mixed after first dispersion, and if necessary, oil-absorbing pigments, surfactants, binders, metal soaps,
Add antioxidants, ultraviolet absorbers, etc. to make a heat-sensitive coating liquid.

The obtained heat-sensitive coating liquid is coated on the above-mentioned undercoat layer and dried, and then subjected to a calender treatment to impart smoothness to the desired heat-sensitive recording material.

The color former used in the present invention includes triarylmethane compounds and diphenylmethane compounds.

Examples include xanthine compounds, thiazine compounds, and spiropyran compounds. Some examples of these include 3.3-bis(p-dimethylaminophenyl)-6-
Dimethylamino-7thalide (i.e. crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(≠-dietheramino-coethoxy7-enyl)-j-(t-ethyl-cotatylindole-3 Examples of diphenylmethane-based compounds include Hiro, Hiro'-bis -dimethylaminobenzhydrin benzyl ether, N-halophenyl-leukoolamine, N --z *≠+ z
-) ') Chlorophenyl leuco auramine, etc.
Examples of xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, cokebenzylamino-6-diethylaminofluoran,
co-anilino 6-diethylaminofluorane, co-anilino 3-methyl-6-dinithylaminofluorane,
Coanilino 3-methyl-4-N-cyclohexyl-
N-methylaminofluorane, 3,6-bisdiphenylaminofluorane, co-anilino 3-methyl-j-
N-Ethyl-N-ynamylaminofluorane, 2-〇-chloroanilino-t-diethylaminofluorane1.
2-m-chloroanilino-t-diethylaminofluorane, co(39 μm dichloroanilino)-t-diethylaminofluorane, 2-octylamino-6-diethylaminofluoran, co-dihexylamino-t-diethylaminofluorane, 2-m -Trichloromethylanilino-t-diethylaminofluorane, λ-butylamino-3-chloro-t-diethylaminofluorane, 2-x
Toxyethylamino-3-chloro-t-diethylaminofluorane, co-anilino 3-chloro-1-diethylaminofluoran, co-phenylamino-6-dietheraminofluorane, co-anilino 3-methyl-6-
Siphenylaminofluora 7.2-7ni/J-methyl-! -dichloro-6-dinithylaminofluoran-coanilino-3-methyl-t-diethylamino-7-methylfluoran, 2-anilino-3-methoxy-6-sibutylaminofluorane, 2-〇-dichloroanilino-6 −
Cyptylaminofluoran λ-p-chloroanilino 3
-Ethoxy-6-diethylaminofluorane, 2-phenyl-4-diethylaminofluorane,! -0-chloroanilino 4-p-butylanilinofluorane, coanilino 3-pentadecyl-t-diethylaminofluorane, coanilino 3-ederut-t-dibutylaminofluorane, coanilino 3-ethyl-A -N-ethyl-N - In-amylaminofluorane, λ-anilino-3-methyl-j-N-ethyl-N-γ-methoxypropylaminofluorane, co-anili/ -J-phenyl-4-diethylaminofluorane, co-ethylamino-3-phenyl- Examples of dithiazine compounds such as 6-diethylaminofluoran and co-anilino 3-methyl-4-N-isoamyl-N-ethylaminofluorane include benzoyl leucomethylene blue and p-nitrobenzyl leucomethylene blue; spiro compounds include is 3-mesolousspiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-cyclospirodinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran , 3-propyl-spiro-dibenzopyran, and the like. These are used alone or in combination to adjust hue or improve image preservation.

The color developer used in the present invention includes co, 2-bis(4c
/-hydroxyphenyl)furopane (bisphenol A), co, corbis(≠-hydroxyphenyl)pentane, co, 2-bis(φ'-hydroxy-3/, 11
-dichlorophenyl) flononin, /, l-bis(≠'
-hydroxy7enyl)cyclohexane, co, λ-bis(hiro'-hydroxyphenyl)hexane, t, i-bis(4c/-hydroxyphenyl)furo/qn, /, I
-bis(styl-hydroxyphenyl)butane, /, /
-his(roxyphenyl)pentane, /, l
- to his(4L'-hydroxyphenyl)"?'l'.

i, i-bis(thin'-hydroxyphenyl)hebutane,
/, /-His(Hydroxyphenyl)octane,
l,/-bis(4C/-hydroxyphenyl)-comethyl-intane, /,/-his(4cm hydroxyphenyl)-λ-ethylhexane, /,/-his(ref'-
hydroxyphenyl)dodecane, /, 44-bis(p-
hydroxyphenylcumyl)benzene, l,3-bis(
p-hydroxyphenylcumyl)benzene, bis(E)
-hydroxyphenyl)sulfone, bis(3-allyl-
≠-Hydroxyphenyl) sulfone, bis(p-hydroxyphenyl)acetic acid benzyl ester bisphenols.

3,! -D-α-methylbenzyl salicylic acid, 31j-
salicylic acids such as di-tert-butylsalicylic acid, 3-α,α-dimethylbenzylsalicylic acid, ≠-(β-p-methoxyphenoxyethoxy)salicylic acid, or polyvalent metal salts thereof (particularly preferred are zinc and aluminum); p-? : )”Roxyamne, t+tV acid benzyl ester, p-hydroxybenzoin [-λ-ethylhexyl ester, β-resorcin e-<2-phenoxyethyl)
Oxybenzoic acid esters such as esters, p-phenylphenol, 3. Examples include phenols such as j-diphenylphenol and cumylphenol, but bisphenols are preferred.

The thermofusible substance added to the thermosensitive coloring layer may be the same as or different from that added to the undercoat layer.

As the binder and pigment, water-soluble polymers, water-insoluble binders,
and pigments.

As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, aluminum stearate, and the like.

(Examples of the Invention) Examples are shown below, but the present invention is not limited thereto. Each heat-sensitive recording material was obtained by coating each support with a heat-sensitive coating liquid using a wire paper so that the dry coating amount was At/n'', and drying in an oven at jOoC.

(Preparation of heat-sensitive coating liquid) 2-anilino-3-methyl-N-methyl-N-cyclohexylaminofluorane as a coloring agent.

20P each of bisphenol A as a color developer and β-7terbenzyl ether as a sensitizer were dispersed in a ball mill overnight with an aqueous solution of 700P of j% polyvinyl alcohol (Cran PVA = 10) to give a volume average particle size of 3 μm.
The following was made. Calcium carbonate (Unibu
r70 (Shiraishi Kogyo), and the toy was dispersed with a homogenizer together with a hexametaphosphoric acid powder O1J solution/407. Each dispersion prepared as described above is
-Anilino 3-methyl-J-N-methyl-N-cyclohexylaminofluorane dispersion jP.

Bispheno-^A dispersion lQP, β-su7terbenzyl-ter dispersion ioy, calcium carbonate dispersion/jrf
A zinc stearate emulsion of 3% was further added.

(Example/) A method for preparing an undercoated base paper is shown below. Calcined kaolin (Ansile) (RiQ manufactured by Engelhard) is used as the pigment! Sodium hexametaphosphate 0, j% solution /
It was dispersed with a homogenizer together with lOf. A coating liquid obtained by adding 4 tt% styrene-butadiene latex (manufactured by Sumitomo Naugatac Co., Ltd.) ty and a β-naphthyl benzyl ether dispersion ty to this dispersion g0P was applied to the basis weight to
Dry coating amount on y/rn2 high quality paper is A 1p/m
2 using a wire spar, and dried in a jooc oven to obtain an undercoat base paper. The heat-sensitive coating liquid was applied to this undercoated paper to obtain a heat-sensitive recording material.

(Example 2) 3Q% Norafin wax dispersion (Hid
rin P-7) Addition of phosphorus to make residual undercoat paper,
A thermosensitive recording material was obtained.

(Example 3) Example υ of the β-naphthylbenzyl ether dispersion
/, /, J-) Lis(Comethyl-≠-Hydroxy-
r-te, t--! An undercoat base paper (P4) was prepared using the (terphenyl)butane dispersion to obtain a heat-sensitive recording material.

(Comparative Example 1) An undercoated base paper was prepared using the β-naphthylbenzyl ether component of Example 1 without adding a liquid, and a heat-sensitive recording material was obtained.

(Comparative Example 2) A heat-sensitive recording material was obtained using high-quality paper with a basis weight of z OP/m 2 . The color density was measured by printing with a Kyocera printing tester at a printing energy of JOmJ/W2 and using a Macbeth density needle.

Dot reproducibility is determined by printing dots using a Kyocera printing tester at a printing energy cost of "JmJ/wx", determining the area of each dot using an image analysis device, and calculating the standard deviation of that area ÷
The average value was taken as the value of dot reproducibility. The smaller this value is, the better the dot reproducibility is.

The above results are shown in Table 1.

Claims (1)

[Claims] In a heat-sensitive recording material in which an undercoat layer containing a pigment and a binder as main components is provided on a support, and a heat-sensitive coloring layer is provided on the undercoat layer, both the undercoat layer and the heat-sensitive coloring layer contain heat having a melting point of 50°C or higher. A heat-sensitive recording material characterized by containing a fusible substance.