JPH0361078A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To ensure that a high-quality recorded image is obtained using a highly sensitive thermal recording medium by using a combination of appropriate blending selection of a coating liquid for an intermediate layer provided between a support and a recording layer and a specific coating technique. CONSTITUTION:An intermediate and a thermal recording layer are provided sequentially on a support. More than two layers containing pigment at 80cc/100g or more of oil absorption measured in compliance with JIS K-5101 method are prepared as the intermediate layer. In addition, at least one layer of these two layers is formed using roll-coating technique. The recommendable pigment is one having a specific oil absorption selected from among, for example, baked clay, aluminum oxide, titanium oxide, magnesium carbonate, diatomite, amorphous silica, aluminum silicate, magnesium silicate, calcium silicate and magnesium aluminosilicate.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that has high recording sensitivity and can provide recorded images of high quality.

"Prior Art" Conventionally, heat-sensitive recording utilizes a coloring reaction between a coloring agent and a coloring agent that develops color when it comes into contact with the coloring agent, and brings a recoloring substance into contact with heat to obtain a colored image. The body is well known. Such a thermal recording medium is relatively inexpensive, and the recording device is compact and its maintenance is relatively easy.
It is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields.

As recording equipment speeds up, there is an increasing demand for heat-sensitive recording materials with excellent dynamic recording sensitivity. In addition, with the diversification of uses, there is an increasing demand for thermosensitive recording materials that can provide high-quality recorded images in any range from low density to high density.

"Problems to be Solved by the Invention" In order to meet the above demands, methods have been proposed to provide a plurality of intermediate layers between the support and the recording layer.
(Japanese Patent Application Laid-Open No. 62-42878), detailed studies and research on the coating liquid formulation and coating method have not been sufficiently conducted. For this reason, the current situation is that the effects of the intermediate layer cannot be fully demonstrated.

In view of the current situation, the present inventors have conducted extensive research on the coating method (formation method) of the intermediate layer provided between the support and the recording layer, and have found that appropriate selection of coating liquid formulation and specific coating method have been carried out. By combining these methods, the effect of the intermediate layer can be fully demonstrated, and as a result, a thermal recording medium with extremely excellent recording sensitivity and high quality recorded images has been completed. Ta.

"Means for Solving the Problems" The present invention provides a heat-sensitive recording body δ in which an intermediate layer and a heat-sensitive recording layer are sequentially provided on a support, and a JIS
Oil absorption measured according to K-5101 method is 80cc/
2. An intermediate layer containing 100 g or more of a pigment.
The heat-sensitive recording material is characterized in that it has at least one layer, and at least one of the layers is formed by roll coating.

"Function" As described above, the heat-sensitive recording material of the present invention has two or more intermediate layers containing a specific oil-absorbing pigment between the support and the recording layer, and at least one of the intermediate layers is formed by roll coating. It is characterized by being formed by.

Therefore, the oil absorption amount based on the JIS K-5101 method is 80
Examples of facets with cC/100g or higher include: aluminum oxide, aluminum oxide, titanium oxide, magnesilla carbonate 11
, diatom, amorphous silica, aluminum silicate, silicate magnesi shim, silicate calcilla 13, magnesium alkinosilicate, etc., which have the above-mentioned specific oil absorption amount. Furthermore, inorganic or organic pigments obtained by physically or chemically processing general pigments to have a specific oil absorption capacity as described in "2" may also be used. Among these various pigments, calcined clay and amorphous wrinkle strength are particularly preferred because they have excellent heat insulating properties and have a large effect on improving recording sensitivity.

The addition rate of a specific oil-absorbing pigment is not particularly limited, but if the amount added is too large, the adhesive force of the pigment particles will decrease and paper dust will be generated when cutting the recording medium.
Usually, it is desirable to adjust the total solid content within a range of about 50 to 95% by weight.

Note that it is necessary to add a binder to the coating liquid for forming the intermediate layer, and examples of the binder include starch, casein, polyvinyl alcohol, methyl cell "1-su",
Water-soluble polymers such as carbo-1-dimethylcellulose, hydroxyethylcellulose, polyacrylic acid, styrene-butadiene copolymers, styrene-acrylic acid copolymers, acrylonitrile-butadiene copolymers, colloidal silica particle composites styrene, etc. Examples include various synthetic resin emulsions such as acrylic acid ester copolymers and acrylic acid copolymers.

Further, it is also possible to appropriately add ordinary pigments, dispersants, antifoaming agents, colored dyes, fluorescent dyes, ultraviolet absorbers, etc. to the coating liquid for forming the intermediate layer, within a range that does not impede the desired effect. .

When forming the intermediate layer in the heat-sensitive recording material of the present invention, it is important to provide at least two or more intermediate layers, and the coating composition of each intermediate layer does not necessarily have to be the same, and the coating method Of course, it is possible to change it as appropriate depending on the purpose.

That is, as described above, the intermediate layer constituting the heat-sensitive recording material of the present invention is formed by coating two or more layers, and at least one of the layers is formed by applying U-ru coating. However, since such roll coating is a coating method that transfers the coating liquid, the porosity of the coating layer decreases because there is little penetration of the coating liquid into the support or the underlying intermediate layer. is high;
Easy to form bulky structure. Moreover, since a layer with a uniform thickness and high surface smoothness is formed, this is preferable from the viewpoint of obtaining a heat-sensitive recording medium with high recording sensitivity and high image quality. Therefore, in order to cover the unevenness of the base paper as much as possible and obtain a recording layer with good smoothness, it is a more preferable embodiment to adopt a roll coating method for forming the lowest intermediate layer, but this is not necessarily limited. do not have. A second intermediate layer is further provided on one of the first intermediate layers obtained in this way, and if necessary, a third intermediate layer, etc.
For the intermediate layer, the same coating composition as the first intermediate layer may be used, but if possible, a KJI composition containing components with high heat insulation properties may be used. It is desirable to suitably change the composition of the coating liquid to obtain a combination that will yield a heat-sensitive recording material with higher sensitivity and higher image quality.

The coating method applied to obtain the heat-sensitive recording material of the present invention includes, for example, KCM Coating, Matsusei Coater, Hagorton Roll Coating, Gate Roll Coating - 13 reverse: 1-tar, 4 The present invention is not limited to coating using a roll coater such as the present reverse coater, but also includes coating using a press roll on a paper machine.

Note that various methods can be used to form the intermediate layer outside the layer plate formed by roll coating, depending on the purpose, and there are no particular limitations on the method. Forming the layer with <-h by blade coating is one of the particularly preferred embodiments because the surface smoothness of the coating layer is excellent.

Suppose that in order to obtain a heat-sensitive recording material with high sensitivity and high image quality, the coating amount of the intermediate layer required for obtaining a heat-sensitive recording material with high sensitivity and high image quality is to be reduced by using only one layer of the I-coating method ()↓J1.1. Defects such as a streaky roll pattern and orange peel, which are unique to I-ru coating, occur, making it impossible to obtain the desired quality. Therefore, in the present invention, the coating amount by roll coating is 1 to 15 g/n? The required quality can be obtained by forming two or more intermediate layers.

Further, the coating amount of each layer of the intermediate layer is not particularly limited, and is appropriately adjusted within a range of about 1 to 15 g/m' depending on the intended characteristics of the heat-sensitive recording material.

The coating liquid for the intermediate layer may be applied using either an on-machine coater or an off-machine coater installed on the paper machine, or a combination of both may be used. It is not limited.

The heat-sensitive recording layer of the present invention is produced by coating and drying the heat-sensitive recording layer on the intermediate layer thus formed. However, the combination of the color former and the color former contained in the recording layer is particularly There are no limitations, and any combination can be used as long as the two come into contact with each other due to heat and cause a coloring reaction. For example, a colorless or light-colored basic dye and an inorganic or organic acidic substance can be used. Combinations of higher fatty acid metal salts such as ferric stearate and phenols such as gallic acid are exemplified. Furthermore, it is also possible to apply the present invention to various heat-sensitive recording bodies in which a recorded image is obtained by heat, such as a heat-sensitive recording body in which a diazonium compound, a coupler, and a basic substance are combined. However, the specific intermediate layer in the heat-sensitive recording material of the present invention is more preferably applied, especially in the case of a combination of a basic dye and an acidic substance, since it exhibits particularly excellent effects.

Various types of colorless to light-colored basic dyes are known to be used in the present invention, and the following are exemplified.

3.3-His<p-dimethylaminophenyl)6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindole) -3-yl)phthalide, 3-(p-dimethylagodiphenyl)-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-dimethylagonoklide, 3,3-bis( 9-Ethylcarbazol-3-yl)-6-dimethylasoftinophthalite, 3,3-bis(2-
phenylindol-3-yl)-6-dimethyla5-nophthalide, 3-p-dimethylaminophenyl-3-(1
-Methylpyrrol-3-yl)-6-dimethyla 5-knocklide and other triallylmethane-based dyes 1.4.4'bis-dimethyla-5-nohenshydrylhenzyl ether, N
-halophenyl-lokotagon, N-2,4,5-1
-IJ/diphenylmethane dyes such as lorophenyl leuco auramine, hendiyl leucomethylene blue, p-
Thiazine dyes such as nitrohenduylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-hensyl-spiro-dinaphthopyran, 3-methyl- Spiro-based dyes such as naphtho-(6'-methoxyhenzo)spiropyran, 3-propyl-spirodihenzopyran, rhodamine B anilinolactam, rhodatin (p-21-roanilino)lactam, loaf yin (0
-lactam dyes such as chloro(niline)lactam, 3-dimethylamino-7-meadow-1-cyfluorane, 3-diethylamino-6-methoxyfluorane, 3-ethylamino-7
-Medoxyfluorane, 3-di:L-chlorofluorane, 3-diethylamino-6-methyl-7
-Chlorofluorane, 3-diethylano6.7-dimethylfluorane, 3-(N-ethyl-p-toluidino)-7methylfluorane, 3-diethyla2no7-N
Acetyl-N-methylaminofluorane, 3-diethylamine-7-N-methylaminofluorane, 3-diethylamino-7-dihendylaminofluorane, 3-diethylamino-? -N-Methyl-N-benzylaminofluorane, 3-shetylar 7-N-chloroethyl-
N-methylaminofluorane, 3-diethylamino-7
-N-diethylaminofluorane, 3-(N-ethyl-p
~toluidino)-6-methyl-7-phenylaminofluorane, 3-(N-fuclobenyl-N ethylamino)
-6-Methyl-7-anilituf 1 luoran, 3-(N-ethyl-p-1-luidino)6-
Methyl-7-(pl-luidino)fluorane, 3-diethylamino-6-methyl-7-phenylachofluorane, 3-diethylamino-7(2-carbomethoxy-
phenylamino)fluorane, 3-(N-ethyl-N-
isoamylamino)-6-methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamine)-6-methyl-7-phenyla[nofluorane,
3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl 7-phenylaminofluorane, 3-diethylamino-6-methyl-7-
Xylidinofluorane, 3-diethylamino-7-(o
-chlorophenylamino)fluoran, 3-dibutylamino-7(O-chlorophenylamino)fluoran, 3
Pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3-N-methyl-N-terahydrofurfuryl fluorane, 6-methyl-7-anilite fluorane,
Fluoran dyes such as 3-N-ethyl-N-tetylhydrofurfurylamino-6-methyl-7-anilite fluoran.

Furthermore, various types of inorganic or organic acidic substances that develop color upon contact with basic dyes are known, and examples thereof include the following.

Inorganic acidic substances such as activated clay, acid clay, acpulgite, bentonite, colloidal silica, aluminum silicate, 4-tert~butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4- tert-octylcatechol, 2゜2'-dihydroxydiphenol, 2,2'-methylenebis(4-methyl-5-tert)
L-butylphenol), 4.4'-isopropylidenebis(2tert-butylphenol), 4. 4
'-5ec butylidene diphenol, 4-phenylphenol, 4,4'-isopropylidene diphenol (
Bisphenol A), 2,2'-methylenebis(4-chlorophenol), hydroquinone, 44'-cyclo.
＼Phenolic compounds such as xylidene diphenol, 4=h3-droxybenzoic acid hensyl, dimethyl 4-hydroxyphthalate, hydroquinone monohensyl ether, novolak type phenolic resin, phenol polymer, benzoic acid, pter t-butylbenzoic acid, Trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-
4-Hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropyl salicylic acid, 3-tert-butylsalicylic acid, 3-hensylsalicylic acid, 3-(α-methylhensyl)salicylic acid, 3- Chloro-5-(α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5-(α,α-dimethylhensyl)salicylic acid,
3. Aromatic carboxylic acids such as 5-di-α-methylbenzylsalicylic acid, and their phenolic compounds, aromatic carbonic acids and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. Examples include organic acidic substances such as salts with

In the present invention, the usage ratio of the coloring agent and the coloring agent in the recording layer is appropriately selected based on the type of coloring agent and coloring agent used, and is not particularly limited. When a colorless dye and an acidic substance are used, the acidic substance is generally used in an amount of 1 to 50 parts by weight, preferably 2 to 10 parts by weight, based on 1 part by weight of the basic colorless dye.

To prepare a coating liquid containing these substances, the coloring agent and the coloring agent are generally dispersed together or separately using water as a dispersion medium and stirring or grinding using a ball grater, attritor, sand mill, etc. , prepared as a coating liquid.

Such coating liquids usually contain starches, human loxyethyl cellulose, methyl cellulose,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene
Maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, natural rubber emulsion, styrene/butadiene copolymer emulsion , acrylonitrile/butadiene copolymer emulsion, methyl methacrylate/butadiene copolymer emulsion, polychloroprene emulsion, vinyl acetate emulsion, ethylene/vinyl acetate emulsion, etc. account for 10 to 70% by weight of the total solids, preferably 15 to 50% by weight. It is added to a certain extent.

Furthermore, various auxiliary agents can be added to the coating liquid as necessary, such as sodium dioctyl sulfosuccinate, sulfur and lithium dodecyl hanzene sulfonate,
Examples include dispersants such as sodium lauryl alcohol sulfate ester, alginates, and fatty acid metal salts, ultraviolet absorbers such as benzophenone and 1-riazole, foaming agents thereof, fluorescent dyes, and colored dyes.

In addition, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, calcium carbonate, zinc oxide, 6-aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, halide sulfate, etc. , zinc sulfate, curcum, kaolin, clay, calcined clay, colloidal silica and other inorganic pigments, styrene microballs, nylon powder, polyethylene powder, urea/formalin resin filler, raw starch and other organic pigments, stearic acid amide, stearin Fatty acid amides such as acid methylene bisamide, oleic acid amide, palmidic acid akoto, coconut fatty acid amide, dihenzylterefukle-1, ■, 2-cy(3-methylphenoxy)ethane, 1,2-diphenoxyethane, 4.4'
-dilenedioxy-bis-benzoic acid diphenylmethyl ester, i, i, 3-tris (2=methyl-
4-hydroxy-5-tert-butylphenyl)butane, 2,2'-methylenebis(4methyl-6-tert)
-butylphenol), 44'-butyrindenbis(6
Hindered phenols such as (tert-butyl-3-methylphenol) and various known thermofusible substances can also be added.

7. When an inorganic or organic pigment is contained in the recording layer, it is preferable to use a pigment with a particle size as small as possible, and it is particularly desirable to use a pigment with an average particle size of 2 μm or less.

In the present invention, the method for forming the recording layer is not particularly limited, and the coating liquid for the recording layer is coated onto the intermediate layer using a coating device equipped with a suitable coater head such as an air knife coater or a blade coater. , formed by drying method. Further, the coating amount of the coating liquid is not particularly limited, and is usually 2 to 12 g/bo, preferably 3 g/bo in terms of dry weight.
It is adjusted within a range of about 10 g/m'.

In addition, the support is not particularly limited, and may include high-quality paper, medium-quality paper, base paper made with a Yankee machine, single-sided gloss base paper,
Papers such as double-sided glossy base paper, Castco I paper, art paper, coated paper, medium quality coated paper, synthetic fiber paper, synthetic resin film, etc. are used as appropriate.

Incidentally, after coating and drying the intermediate layer and the recording layer, smoothing treatment such as super calendering may be performed if necessary. Furthermore, it is possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer, etc. Various known techniques in the field of heat-sensitive recording materials, such as providing a backing layer on the back surface of the support, can be used as appropriate. It can be added.

"Example" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these.

In addition, unless otherwise specified, parts and percentages in examples do not indicate parts by weight and percentages by weight, respectively.

Example 1 [Preparation of coating liquid for intermediate layer-■] Calcined clay (trade name: Anthylenox, Oil Absorbent-110)
cc/100 g, manufactured by Engelhard) 100 parts styrene-butadiene copolymer latex (trade name: D
15 parts Polyvinyl alcohol water 227 parts 9 The above compositions were mixed to prepare intermediate layer coating $-1.

[Preparation of coating liquid-H for intermediate layer]

Coating liquid for intermediate layer - Blend amount of LJ filtrate in preparation of (1) 22
Coating liquid for intermediate layer -■ except that the amount was reduced from 7 parts to 175 parts
Intermediate layer coating liquid-■ was prepared in the same manner as above.

[Formation of intermediate layer]

The coating liquid for the intermediate layer thus obtained was coated with a paper machine using a roller coater installed on the second side of the paper machine.
g/g” Nisshogi, the coating amount after drying is 2g/m’
The mixture was coated and dried to form an intermediate layer (■).

Next, using a blade coater installed on the paper machine, coat the intermediate layer coating liquid -■ on the intermediate layer so that the coated amount after drying is 6 g/bo, and dry to coat the intermediate layer. -H was formed.

In this way, a support for a heat-sensitive recording material provided with an intermediate layer consisting of two layers was obtained.

[Preparation of coating liquid for recording layer]

0 ■ A wave preparation 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane
10
Parts 1,2-bis(3-methylphenoxy)ethane 15 parts Methylcellulose 5% aqueous solution 15 parts Water
80 parts of the above Mi powder was ground in a sand mill until the average particle size was 3 μm.

■ Preparation of Solution B 4-4'-Isopropylidene Schiff J4 Nor 30 parts Methyl cellulose 5% water? '4 liquid 30 parts water
70 parts of the above composition was ground in a Sun mill to an average particle size of 3 μm.

120 parts of liquid A, 130 parts of liquid B, 30 parts of amorphous silica, 1
A recording layer coating liquid was prepared by stirring and mixing 100 parts of a 5% polyvinyl alcohol aqueous solution and 130 parts of water.

[Formation of recording layer]

The thus obtained recording layer coating liquid was applied to the intermediate layer-L of the heat-sensitive recording support at a coating amount of 5 g/n (after drying).
It was coated with an air knife coater, dried, and subjected to super calendering to obtain thermal recording paper.

Example 2 [Preparation of coating liquid for intermediate layer-■] Amorphous silica (oil absorption: 200 cc/100 g
/ n ( ) 70 parts calcium carbonate (oil absorption: 43 cc/100 g
/rd) 30 parts styrene-butadiene copolymer latex (trade name.
I) 014-157L Solid content: 48%, manufactured by Asahi Kasei Corporation)
15 parts polyvinyl alcohol 12% water? 6'/&2
58t (water
227 parts The above composition was mixed to prepare an intermediate layer coating liquid -■
was prepared. Next, in the formation of the intermediate layer in Example 1, Kanjuku I self-ripped nails were prepared in the same manner as in Example 1, except that Intermediate layer coating liquid-III was used instead of Intermediate layer coating liquid-H. (I got it.

Example 3 Thermal recording paper was prepared in the same manner as in Example 1, except that in the formation of the second intermediate layer (upper layer) in Example 1, a second coater was used. I got it.

Example 4 [Braking of coating liquid for intermediate layer-IV] In the preparation of coating liquid for intermediate layer-■, the blending amount of water was 227
Coating liquid for intermediate layer -■ was prepared in the same manner as coating liquid for intermediate layer -■ except that the amount was reduced to 157 parts.

[Preparation of coating liquid for intermediate layer -■]

In the preparation of intermediate layer coating liquid-■, the amount of water mixed is 227
Intermediate layer coating liquid-■ was prepared in the same manner except that the amount was increased to 300 parts.

[Formation of intermediate layer]

The thus obtained intermediate layer (with 7 & - + V of the paper machine)
-0, the basis weight is 50 g/r + (soil 1'l 21E L, 2 t: + throat plate = + - Coating after drying with ``$'', the amount is 6 g/n (coating and drying) Middle layer-III
(first intermediate layer) was formed.

Next, on a paper machine, the coating liquid for the intermediate layer -■ was coated on the intermediate layer -■ using a Hamilton roll coater so that the coating amount after drying was 2 g/m, and dried to form the intermediate layer -■ ( Second
intermediate layer) was formed.

[Formation of recording layer]

Intermediate layer-I of support for thermosensitive recording material obtained as above
A recording layer was coated on the V in the same manner as in Example 1 to complete a heat-sensitive recording paper.

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that a rod blade coater was used instead of the Hamilton roll coater in forming the intermediate layer in Example 1.

Comparative Example 2 [Preparation of interlayer coating liquid-■] Calcium carbonate (oil absorption: 43 cc/100 g/r&
) 100 parts styrene-butadiene copolymer latex (trade name;
T) OW-1571, solid content: 48%, manufactured by Asahi Kaoru Co., Ltd.) 1
5 parts Polyvinyl alcohol water 140 parts The above composition was mixed to prepare a coating liquid for intermediate layer - (1).

[Preparation of coating liquid for intermediate layer -■]

In the preparation of intermediate layer coating liquid-■, the amount of water mixed is 140
Intermediate layer coating liquid-■ was prepared in the same manner except that Mffl was changed to 90 parts.

In the formation of the intermediate layer in Example 1, coating liquid for intermediate layer -■
Coating liquid for intermediate layer -Vl instead of , coating liquid for intermediate layer -
Thermal Record 81 was obtained in the same manner as in Example 1, except that intermediate layer coating liquid - (2) was used instead of (2).

Comparative Example 3 [Preparation of Coating Liquid for Intermediate Layer - ■] In the preparation of Coating Liquid for Intermediate Layer - ■, the blending amount of water was 227.
Intermediate layer coating liquid-■ was prepared in the same manner except that the amount was reduced to 143 parts.

5 [Formation of intermediate layer] The thus obtained coating liquid for the intermediate layer - ■ is heated to 100 m² on a paper machine.
Intermediate layer V was formed by coating and drying f50 g/ni high-quality paper using a rod blade coater so that the coating amount after drying was 8 g/rrf.

[Formation of recording layer]

The recording layer coating liquid used in Example 1 was applied to the intermediate layer -Vl.
After drying, it was coated with an air knife coater so that the coating amount after drying was 51;/rrl, and then subjected to super calendering to obtain a heat-sensitive recording paper.

The seven types of thermal recording paper obtained in this way were printed using a thermal printer, and the color density was measured using a Maches densitometer (R
D-100 R type/manufactured by Maches Co., Ltd.). Furthermore, the recorded image quality was evaluated and the results are shown in a table.

The recorded image quality was determined by visual inspection of the recorded image using the A/1 value, and the evaluation criteria were as follows.

◎...Extremely excellent ○...Excellent △...Inferior 6 ×...Extremely inferior "Effect" As is clear from the results in Table-■, Examples of the present invention The thermal recording paper obtained had a high recording density and an extremely excellent recorded image quality.

Claims (1)

[Claims] In a heat-sensitive recording material in which an intermediate layer and a heat-sensitive recording layer are sequentially provided on a support, as the intermediate layer, JISK-510
It is characterized by having two or more intermediate layers containing a pigment with an oil absorption amount of 80 cc/100 g or more measured according to Method 1, and at least one of the intermediate layers being formed by roll coating. Heat sensitive recording material.