JP2984005B2 - Thermal recording medium - Google Patents

Description

The present invention relates to a thermosensitive recording medium, and particularly relates to a high recording density, excellent print pixel reproducibility, and extremely low whiteness of the recording medium and adhesion of scum to a thermal head. It relates to an excellent thermal recording medium.

"Prior art" Conventionally, a thermosensitive recording in which a color-forming image is obtained by contacting both color-forming substances by heat using a color-forming reaction between a color-forming agent and a color-forming agent that forms a color in contact with the color-forming agent. The body is well known. Such a thermosensitive recording medium is relatively inexpensive, and its recording equipment is compact and its maintenance is relatively easy. Therefore, it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields.

With the versatility of applications, thermal recording media with excellent print pixel reproducibility in any region from low density to high density and capable of obtaining high-quality recorded images comparable to silver halide photographs Are increasing. Further, with the increase in the speed of the recording apparatus, there is an increasing demand for a thermosensitive recording medium having excellent dynamic recording sensitivity.

In order to obtain such a high-sensitivity, high-quality heat-sensitive recording medium, an intermediate layer made of an oil-absorbing pigment may be provided (see JP-A-59-5959).
Nos. 155097 and 61-44683), and a method of improving smoothness and heat insulation by combining these layers in multiple layers (Japanese Patent Application Laid-Open Nos. 61-11286 and 61-193880) has been proposed. ing.

However, when inorganic pigments such as amorphous silica or calcined clay are used as oil-absorbing pigments, if super calendering is performed to smooth the thermosensitive recording medium, the whiteness decreases or the specific surface area of these pigments decreases. There was a disadvantage that the paper surface strength was reduced due to the large size.

"Problems to be Solved by the Invention" The present invention specifies a material constituting an intermediate layer provided between a support and a heat-sensitive recording layer, thereby achieving high recording density, excellent print pixel reproducibility, and recording. It is an object of the present invention to provide an extremely excellent heat-sensitive recording material having little whiteness of the body and little adhesion of scum to a thermal head.

"Means for Solving the Problems" The present inventors, in a thermosensitive recording medium provided with a heat-sensitive recording layer containing a color former and a color former that comes into contact with the color former on the support, By providing an intermediate layer containing a spherical or hollow organic pigment having an average particle diameter of 0.8 to 1.2 μm and a coefficient of variation of 30% or less between the support and the heat-sensitive recording layer, it is extremely efficient. The inventors have found that the problem is solved, and have completed the present invention.

"Action" As described above, the heat-sensitive recording medium of the present invention has a spherical or hollow type having an average particle diameter of 0.8 to 1.2 μm and a variation coefficient of 30% or less between the support and the heat-sensitive recording layer. The thermosensitive recording medium is characterized by providing an intermediate layer containing an organic pigment.The coefficient of variation referred to here is the standard deviation of the organic pigment particle diameter divided by the average particle diameter and expressed as a percentage. For example, when this value is increased at a constant average particle size, the dispersion of the particles is increased, which indicates that pigments of various sizes are present. According to detailed studies by the present inventors, when the coefficient of variation is larger than 80%, small pigment particles enter between large pigment particles, and the porosity between the pigment particles is reduced. As a result, the heat insulating property of the intermediate layer is reduced. And the oil absorbency is reduced, and the desired effects of the recording density and print image quality at the time of thermal recording cannot be obtained, and the adhesion of scum to the thermal head is not improved. For this reason, the coefficient of variation is desirably 80% or less, more preferably 50% or less, and most preferably 30% or less.

Further, if the average particle size is 0.8 μm or less, even if the coefficient of variation is 80% or less, the voids between the pigment particles are small. The average particle size is preferably 8 μm or less in consideration of the smoothness of the intermediate layer surface. Therefore, the range of 0.8 to 8 μm is a preferable range of the particle size in the present invention.

The average particle size and the coefficient of variation were calculated by measuring with a Coulter Multisizer (manufactured by Coulter Counter).

As the organic pigment used in the present invention, for example, phenolic resin, urea resin, melamine resin, polyethylene resin, polystyrene resin, polypropylene resin, methacrylic resin, polyurethane resin, styrene-acrylic resin,
Styrene / methacrylic resin, acrylic / urethane resin, and the like. As the shape of the pigment, a spherical shape or a hollow shape is effective.

As the binder used in combination with the organic pigment of the specific composition of the present invention, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol,
Acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt And various natural or synthetic polymers such as styrene / butadiene copolymer emulsion, urea resin emulsion, melamine resin emulsion, amide resin emulsion, colloidal silica particle composite styrene / acrylate copolymer emulsion and the like.

The combination ratio of the organic pigment having a specific composition and the binder in the present invention is not particularly limited,
It is desirable to adjust the amount in the range of 8 to 30 parts by weight based on 100 parts by weight of the organic pigment. If the amount of the binder is larger than the above range, the porosity of the intermediate layer is reduced, so that the heat insulating property is lowered and a desired recording sensitivity cannot be obtained, and the amount of scum adhered to the thermal head also increases. On the other hand, if the amount of the binder is less than the above range, the adhesive strength is lowered, and paper powder is generated when the recording medium is cut, and the heat-sensitive recording layer is peeled off when the recording medium is bent.

As long as the effects of the present invention are not impaired, the specific organic pigments of the present invention include, for example, common organic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, amorphous silica, and activated clay. Inorganic pigments may be added.

Various assistants can be added to the intermediate layer of the present invention as needed. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate and fatty acid metal salts, ultraviolet absorbers such as triazoles, other defoamers, fluorescent dyes, coloring dyes And the like.

The forming method is not particularly limited. For example, it is formed by a method in which a coating solution is coated on a support and dried by a coating apparatus having an appropriate coater head such as an air knife coater or a blade coater. Also, the amount of the coating solution applied is not particularly limited, and it is desirable to appropriately control the coating amount in the range of ^{3 to} 25 g / m ² , more preferably 5 to 15 g / m ² . Incidentally, two or more intermediate layers may be provided.

The support is also not particularly limited, and high quality paper, medium quality paper,
Base paper, single-side gloss base paper, double-side gloss base paper, cast coated paper, art paper, coated paper,
Paper such as medium coated paper and lightly coated paper, synthetic fiber paper, synthetic resin film and the like are appropriately used.

On the intermediate layer thus formed, a heat-sensitive recording layer is applied,
Although the heat-sensitive recording material of the present invention is produced by drying, the combination of the color former and the color former contained in the recording layer is not particularly limited, and the two are brought into contact by heat. Any combination can be used as long as it causes a color reaction, for example, a combination of a colorless or pale-colored basic dye and an inorganic or organic acidic substance, or a metal salt of a higher fatty acid such as ferric stearate. And a phenol such as gallic acid. Further, the present invention can be applied to various kinds of heat-sensitive recording media in which a recorded image is obtained by heat, such as a heat-sensitive recording material in which a diazonium compound, a coupler and a basic substance are combined.

However, the specific intermediate layer of the present invention provided on the support exhibits an excellent effect particularly in the combination of a basic dye and an acidic substance, and is therefore preferably applied particularly to such a combination.

In the heat-sensitive recording material of the present invention, various types of colorless or light-colored basic dyes that constitute a recording layer together with a specific coloring agent and a heat-fusible substance are known, and examples thereof include the following. You.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2 -Dimethylindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-methylindol-3-yl) phthalide, 3,3-
Bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide,
3-bis (9-ethylcarbazol-3-yl) -6
Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide,
Triallylmethane dyes such as 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydryl benzyl ether, Diphenylmethane dyes such as N-halophenyl-leuco auramine and N-2,4,5-trichlorophenyl leuco auramine; thiazine dyes such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue; 3-methyl-spiro-dinaphthopyran , 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-
Spiro dyes such as benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B anilinolactam, rhodamine (p-nitroanilino) lactam, Lactam dyes such as rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-
Methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluoran, 3- (N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-7-N-acetyl-N-methylaminofluoran, 3-diethylamino-
7-N-methylaminofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-N-methyl-N-benzylaminofluoran,
3-diethylamino-7-N-chloroethyl-N-methylaminofluoran, 3-diethylamino-7-N-diethylaminofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluor Orane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3
-Diethylamino-7- (2-carbomethoxy-phenylamino) fluoran, 3- (N-cyclohexyl-N
-Methylamino) -6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran, 3-piperidino-6-methyl-7-
Phenylaminofluoran, 3-diethylamino-6-
Methyl-7-xylidinofluoran, 3-diethylamino-7- (o-chlorophenylamino) fluoran, 3
-Dibutylamino-7- (o-chlorophenylamino)
Fluoran, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran, 3-diethylamino-
7- (o-fluorophenylamino) fluoran, 3-
Dibutylamino-7- (o-fluorophenylamino)
Fluoran, 3-dibutylamino-6-methyl-7-phenylaminofluoran, 3-dipentylamino-6
Methyl-7-phenylaminofluoran, 3- (N-methyl-NNn-amyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-Nn-amyl) amino- 6-methyl-7-phenylaminofluoran, 3- (N-ethyl-N-isoamyl) amino-6
-Methyl-7-phenylaminofluoran, 3- (N-
Methyl-Nn-hexyl) amino-6-methyl-7-
Phenylaminofluoran, 3- (N-ethyl-Nn
And fluoran dyes such as -hexyl) amino-6-methyl-7-phenylaminofluoran and 3- (N-ethyl-N-β-ethylhexyl) amino-6-methyl-7-phenylaminofluoran. . In addition, these basic dyes can be used in combination of two or more as necessary.

Various materials are also known as the inorganic or organic acidic substance which forms a color upon contact with the basic dye as described above, for example, activated clay, attapulgite, colloidal silica, inorganic acidic substances such as aluminum silicate, 4-tert-butylphenol , 4-hydroxydiphenoxide, α-naphthol,
β-naphthol, 4-hydroxyacetophenol, 4
-Tert-octylcatechol, 2,2'-dihydroxydiphenol, 4,4'-isopropylidenebis (2-tert
-Butylphenol), 4,4'-sec-butylidenediphenol, 4-phenylphenol, 4,4'-isopropylidenediphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2 '-Methylenebis (4-chlorophenol), hydroquinone, 4,4'-
Cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4,4 '-Tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate Benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, 4-
Phenethyl hydroxybenzoate, 4-hydroxybenzoic acid-p-chlorobenzyl, 4-hydroxybenzoic acid-p
A phenolic compound such as methoxybenzyl, a novolak type phenol resin, a phenol polymer, benzoic acid, p
-Tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid,
3-cyclohexyl-4-hydroxybenzoic acid, 3,5-
Dimethyl-4-hydroxybenzoic acid, 3-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3,5-di- aromatic carboxylic acids such as tert-butylsalicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4′-dihydroxydiphenylsulfone, Hydroxy-4'-isopropyloxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-
4-hydroxydiphenylsulfone derivatives such as methyldiphenylsulfone, 3,4-dihydroxydiphenylsulfone, and 3,4-dihydroxy-4'-methyldiphenylsulfone; bis (3-tert-butyl-4-hydroxy-6
-Methylphenyl) sulfide, bis (2-methyl-4)
-Hydroxy-6-tert-butylphenyl) sulfide and the like, and furthermore, these phenolic compounds, aromatic carboxylic acids and the like and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel. And organic acid substances such as an ampiline complex of zinc thiocyanate.

The use ratio of the basic dye and the colorant is not particularly limited as it is appropriately selected depending on the type of the basic dye and the colorant used. 1 to 50 parts by weight, preferably about 2 to 10 parts by weight of a color former is used.

Paints containing these substances are generally prepared by using water as a dispersion medium and dispersing them with a stirring / pulverizer such as a ball mill or a sand mill.

In such a coating solution, usually as a binder starches, hydroxyethylcellulose, methylcellulose,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene
Maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene
Butadiene copolymer emulsion, urea resin, melamine resin, amide resin, colloidal silica particle composite styrene / acrylate copolymer emulsion and the like are 10 to 40% by weight, preferably 15 to 30% by weight based on the total solid content of the coating solution. It is blended in an amount of about% by weight. Furthermore, various auxiliaries can be added to the coating liquid as needed, such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, sodium salt, fatty acid metal salt, etc. Agents, ultraviolet absorbers such as benzophenones, other antifoaming agents, fluorescent dyes, coloring dyes, and the like are appropriately added.

Also, if necessary, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, waxes such as ester wax,
It is also possible to add inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, amorphous silica, activated clay, etc., and it is also possible to use a sensitizer in combination according to the purpose. . Specific examples of the sensitizer include fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, and the like, and 2,2′-methylenebis (4-methyl-6-tert-amide). Butylphenol), 4,
4'-butylidenebis (6-tert-butyl-3-methylphenol), 2,2'-methylenebis (4-ethyl-6
-Tert-butylphenol), hindered phenols such as 2,4-di-tert-butyl-3-methylphenol,
UV absorbers such as 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone, 1,2-di (3-methylphenoxy) ethane, 1,2-di Phenoxyethane, 1
Phenoxy-2- (4-methylphenoxy) ethane,
1- (1-methylphenoxy) -2- (4-methoxyphenoxy) ethane, dimethyl terephthalate, dibutyl terephthalate, dibenzyl terephthalate, dibutyl isophthalate, phenyl 1-hydroxynaphthoate, benzyl- Examples thereof include 4-methylthiophenyl ether and various known heat-fusible substances.

The use amount of these sensitizers is not particularly limited, but it is generally preferable to adjust the sensitizer within a range of about 400 parts by weight or less based on 100 parts by weight of the color former.

The method for forming the recording layer is not particularly limited. For example, a recording layer coating solution is applied onto the intermediate layer of the present invention by an appropriate application method such as air knife coating, variver blade coating, pure blade coating, or short dwell coating. , Formed by drying. The coating amount of the coating liquid is not particularly limited, and is usually 2 to 12 g / dry weight.
m ² , preferably in the range of about 3 to 10 g / m ² .

After the application and drying of the intermediate layer and the recording layer, a smoothing treatment such as super calendering can be performed as necessary. Further, it is possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer, etc., and various known techniques in the heat-sensitive recording material field such as providing a backing layer on a support or processing an adhesive label. Can be added.

"Examples" Hereinafter, the present invention will be described in more detail with reference to Examples, but it is needless to say that the present invention is not limited to these, and unless otherwise specified, parts and% in Examples are parts by weight and% by weight, respectively. Show.

Example 1 [Preparation of Intermediate Layer Coating Solution-1] Styrene / acrylic resin having a solid concentration of 31% (trade name: XKP
-403, manufactured by Mitsui Toatsu Chemicals, average particle size 1.2 μm, coefficient of variation
80 parts SBR latex (solid content 50%) 10 parts Oxidized starch aqueous solution (solid content 20%) 50 parts A mixture having the above composition was prepared to have a solid content concentration of 20%.

(Formation of intermediate layer)

The obtained intermediate layer coating liquid-1 was applied to a high-quality paper having a basis weight of 50 g / m ^{2 with} an air knife coater so that the coating amount after drying was 8 g / m ² , followed by drying.

[Preparation of Recording Layer Coating Solution] Preparation of Solution A 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluoran 10 parts 1,2-di (3-methylphenoxy) ethane 20 parts 15% aqueous solution of methylcellulose 15 parts Water 80 parts This composition was pulverized by a sand mill until the average particle diameter became 1 μm.

Solution B Preparation 4,4'-isopropylidene diphenol 30 parts Methyl cellulose 5% aqueous solution 30 parts Water 70 parts This composition was pulverized with a sand mill until the average particle diameter became 2 μm.

Liquid A 125 parts, Liquid B 130 parts, silicon oxide pigment (oil absorption 180ml /
100 g) 30 parts, 150 parts of a 20% oxidized starch aqueous solution and 55 parts of water were stirred and mixed to prepare a coating liquid for a recording layer.

(Formation of recording layer)

The resulting recording layer coating liquid onto the intermediate layer, the coating amount after drying coated with an air knife coater so that the 5 g / m ^2,
After drying, a thermosensitive recording paper was obtained.

Example 2 Styrene / acrylic resin having a solid concentration of 31% of Example 1 (trade name: XKP-403, manufactured by Mitsui Toatsu Chemicals, Inc., average particle size 1.2 μm)
m, coefficient of variation 20%, spherical shape: 80 parts styrene-acrylic resin (solid name: 28%) (trade name: ROPAKE HP-91, ROHM
Thermal recording paper was obtained in the same manner as in Example 1 except that 80 parts of And Haas Japan Co., Ltd., average particle size 1.0 μm, coefficient of variation 24%, hollow type) was used.

Comparative Example 1 The styrene-acrylic resin of Example 1 (average particle size 1.2 μm)
m, coefficient of variation 20%, spherical) was replaced with calcined clay to obtain a thermosensitive recording paper in the same manner as in Example 1.

Comparative Example 2 Styrene / acrylic resin of Example 1 (average particle size 1.2 μm)
m, coefficient of variation 20%, spherical) was replaced with styrene / acrylic resin (average particle size 0.4 μm, coefficient of variation 21%, spherical) to obtain a thermosensitive recording paper in the same manner as in Example 1.

Comparative Example 3 Styrene / acrylic resin of Example 1 (average particle size 1.2 μm)
m, variation coefficient 20%, spherical) was replaced with styrene / acrylic resin (average particle size 0.5 μm, variation coefficient 34%, hollow type) in the same manner as in Example 1 to obtain a thermosensitive recording paper.

Comparative Example 4 Styrene / acrylic resin of Example 1 (average particle size 1.2 μm)
m, coefficient of variation 20%, spherical) was replaced with styrene / acrylic resin (average particle size 2.3 μm, coefficient of variation 89%, spherical) to obtain a thermosensitive recording paper in the same manner as in Example 1.

Comparative Example 5 Styrene / acrylic resin of Example 1 (average particle size 1.2 μm)
m, coefficient of variation 20%, spherical) was replaced with styrene / acrylic resin (average particle size 4.4 μm, coefficient of variation 114%, spherical) to obtain a thermosensitive recording paper in the same manner as in Example 1.

Comparative Example 6 The styrene-acrylic resin of Example 1 (average particle size 1.2 μm)
m, coefficient of variation 20%, spherical) was replaced with styrene / acrylic resin (average particle size 0.7 μm, coefficient of variation 77%, spherical) to obtain a thermosensitive recording paper in the same manner as in Example 1.

The heat-sensitive recording paper thus obtained is subjected to a pulse voltage of 16 using a heat-sensitive simulator (a Kyocera simulator).
V, 5msec pulse cycle and 0.35msec print pulse time
Record at 0.5msec and measure the color density by Macbeth densitometer (RD
-100R type, using an amber filter), and the results are shown in Table 1. In addition, the reproducibility, whiteness, and scum adhesion of the printing pixels were also evaluated, and the results are shown in Table 1.

The reproducibility of the print pixels was evaluated by the ratio of the area of the print dots to the area of one dot of the thermal head (dot reproducibility), and the evaluation criteria were as follows.

86: 86% or more ○: 76 to 85% △: 70 to 75% ×: 69% or less The whiteness was measured by a digital hunter (manufactured by Toyo Seiki Seisaku-sho, Ltd.).

Further, the adhesion of the residue was evaluated by using NEFAX-27 (manufactured by NEC) and observing the condition of the residue after 10 copies were made at a printing rate of 100%. The evaluation criteria were as follows.

 ◎: No head residue is seen at all.

 …: Head scum is slightly observed.

 X: Head scum is remarkable.

"Effects" As is clear from the results in Table 1, the thermosensitive recording medium of the present invention has a high recording density, has excellent print pixel reproducibility in any of low to high density areas, and further has a whiteness. In addition, the recording medium was excellent in adhesion of scum.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-113282 (JP, A) JP-A-2-164580 (JP, A) JP-A-3-21488 (JP, A) JP-A-3-3-1 33296 (JP, A) JP-A-61-139485 (JP, A) JP-A-62-138286 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5 / 28-5 / 34

Claims (1)

(57) [Claims] 1. A thermosensitive recording medium comprising a support and a heat-sensitive recording layer containing a color former and a color former which forms a color in contact with the color former, wherein between the support and the heat-sensitive recording layer. Average particle size is 0.
A heat-sensitive recording material comprising an intermediate layer containing a spherical or hollow organic pigment having a thickness of 8 to 1.2 μm and a coefficient of variation of 30% or less.