JPH02220888A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material excellent in the reproduction of the printing pixel within a region from low density to high density, having high whiteness and generating no paper powder by providing an intermediate layer containing an amino resin filler having oil absorbancy of a specific value or more between a support and a thermal recording layer. CONSTITUTION:An intermediate layer containing an amino resin filler having oil absorbancy of 200ml/100g or more is provided between a support and a thermal recording layer. The amino resin filler consists of a urea resin and a melamine resin and one having a pigment form can be designated and urea/ formalin resin pigment is pref. used. In this thermal recording material, the heat-meltable substance formed in the thermal recording layer at the time of recording is effectively absorbed by the intermediate layer and no head refuse is generated. Further, since the intermediate layer has heat holdability, recording density or image quality is excellent and there is also no problem generating fog color development. The above mentioned amino resin filler is pref. contained in the intermediate layer in an amount of 1-20% by wt. of the total solid of the layer.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a thermal recording medium, and in particular to a thermal recording medium that has excellent print pixel reproducibility, high recording density, and excellent whiteness of the recording medium. be.

``Prior Art'' Conventionally, heat-sensitive recording materials that utilize the reaction between a color-forming agent and a color-forming agent that develops color upon contact with the color-forming agent to bring both substances into contact with heat to obtain a colored image are well known. Are known. Such heat-sensitive recording media are relatively inexpensive, and the recording equipment is compact and maintenance is relatively easy, so they are used not only as recording media for facsimile machines and various computers, but also in a wide range of fields.

As the applications have become more diverse, thermal recording materials have excellent reproducibility of printed pixels in all areas from low density to high density, and can produce recorded images of high quality comparable to silver halide photography. The demand for this is increasing. Furthermore, as recording equipment becomes faster, there is an increasing demand for heat-sensitive recording materials with excellent dynamic recording sensitivity.

In order to obtain such a high-sensitivity, high-quality thermal recording medium,
An intermediate layer made of an oil-absorbing inorganic pigment is provided (Japanese Patent Laid-Open No. 59
-155097, No. 61-44683), or a recording medium with improved smoothness and heat insulation by having a multi-layered intermediate layer (Japanese Patent Laid-open No. 11286/1986, No. 61-193880)
) etc. have been proposed.

However, if an intermediate layer is formed mainly of inorganic pigments with high oil absorption such as amorphous silica or calcined clay, it tends to cause color fog in the heat-sensitive recording layer, resulting in low whiteness. Only records can be obtained. Furthermore, the strength of the coating layer was poor, and when the recording medium was cut with a cutter, a large amount of paper dust was generated.

[Problems to be Solved by the Invention] The present invention has excellent reproducibility of printed pixels in all areas from low density to high density, and can obtain recorded images of high quality, has high whiteness, and is The purpose of the present invention is to provide a heat-sensitive recording material that does not generate powder.

"Means for Solving the Problems" The present invention provides a heat-sensitive recording material in which a heat-sensitive recording layer is provided on a support, and an oil absorption amount (JIS) between the support and the heat-sensitive recording layer.
5101 method) is 200mj! This is a heat-sensitive recording material characterized by providing an intermediate layer containing an amino resin filler of /100g or more.

Further, in the present invention, in the above structure, the intermediate layer has an oil absorption amount (JI
5101 method) amino resin filler with an oil absorption of 200 mlf/100 g or more and an oil absorption amount of 200 mlf/10
A heat-sensitive recording material containing less than 0 g of inorganic filler or organic filler.

[Function j] The amino resin filler is made of urea resin, melamine resin, etc., and can be exemplified in the form of a pigment.

Among these, urea-formalin resin pigments are preferably used because they exhibit particularly excellent effects. As described above, the heat-sensitive recording material of the present invention has an oil absorption amount (J) between the support and the heat-sensitive recording layer.
IS K 5101 method) is a heat-sensitive recording material that has an intermediate layer containing an amino resin filler of 200m2, 17100g or more, and therefore the intermediate layer effectively absorbs the heat-melting substance formed in the heat-sensitive recording layer during recording. , there are no problems such as the generation of head scum, and it has excellent equipment suitability, and since the intermediate layer has heat retention properties, it has excellent recording density and image quality. Moreover, unlike an intermediate layer containing only an inorganic pigment as a main component, there is no drawback such as fogging or coloring in the heat-sensitive recording layer. Incidentally, if an intermediate layer is formed using an organic filler such as polystyrene other than amino resin, the whiteness will be better than that of an intermediate layer whose main component is an inorganic pigment, but a large amount of paper dust will be generated when cutting with a cutter. There are drawbacks to doing so.

It is preferable when the amino resin filler is in the form of a pigment forming secondary particles because the heat retention ability of the intermediate layer becomes even more excellent and the recording density is significantly improved.

Generally, coating liquids containing a large amount of filler with high oil absorption tend to have poor fluidity, and are often inferior in coating suitability with a coater. Furthermore, if the content of the specific filler is small, a sufficient improvement effect cannot be obtained, so in the present invention, the amino resin filler having the above oil absorption amount is preferably 0.5 to 30% by weight in the total solid content of the intermediate layer. More preferably 1 to 20%
Contain.

Further, by using an inorganic filler or an organic filler having an oil absorption of less than 200 ml/100 g in the intermediate layer, it is possible to improve the coating suitability of the intermediate layer paint without impairing recording performance or other suitability.

Examples of such inorganic fillers include inorganic pigments such as calcined kaolin, talc, light calcium carbonate, and amorphous silica, and examples of organic fillers include polystyrene fillers, phenolic resin fillers, cellulose fillers, and the like.

The intermediate layer contains a binder, and examples of the binder include starch, casein, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, water-soluble polymers such as polyacrylic acid, and styrene-butadiene copolymers. Examples include various synthetic resin emulsions such as styrene/acrylic acid copolymers, acrylonitrile/butadiene copolymers, colloidal silica particle composite styrene/acrylic acid ester copolymers, acrylic acid copolymers, and the like.

In the middle layer, 5 to 5 parts by weight of binder is added to 100 parts by weight of filler.
It is preferable to mix it in a range of about 30 parts by weight in terms of adhesiveness and recording sensitivity. For example, if the binder content is higher than this range, the porosity of the intermediate layer will decrease, leading to a decrease in heat retention and the possibility of not being able to obtain the desired recording sensitivity, and the tendency for deposits on the thermal head to increase. There is. Also, if the amount of binder blended is less than the above range,
In some cases, the adhesion of the filler particles decreases, resulting in disadvantages such as generation of paper dust when cutting the recording medium.

In addition to the case where such an intermediate layer is composed of one layer, it can also be composed of multiple layers of two or more layers.

The intermediate layer coating solution is usually prepared by dispersing or dissolving the above components in water as a medium, and coating the intermediate layer on the support by applying and drying with various known coating machines such as an air knife coater or a blade coater. Form.

The amount of coating of the intermediate layer is not particularly limited, but the thickness of the intermediate layer is 5 to 40 tons! The dry coating amount is preferably about 3 to 35 g/rd.

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, regarding the combination of the coloring agent and the coloring agent contained in the recording layer, are not particularly limited, and any combination can be used as long as the two come into contact with each other due to heat and a coloring reaction occurs. For example, combinations of colorless or light-colored basic dyes and inorganic or organic acidic substances, combinations of higher fatty acid metal salts such as ferric stearate and phenols such as gallic acid, diazonium compounds, couplers, etc. 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 basic substance is combined.

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

In the heat-sensitive recording material of the present invention, various colorless or light-colored basic dyes constituting the recording layer are known, and the following are exemplified.

3.3-bis(p-dimethylaminophenyl) 6-dimethylaminophthalide, 3.3-bis(p-dimethylaminophenyl) phthalide, 3-(ρ-dimethylaminophenyl)-3-(1,2 dimethyl indole-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, 3,3-bis(9-ethylcarbazol-3-
yl)-6-dimethylaminophthalide, 3,3-bis(
2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-P-dimethylaminophenyl-3-
Triallylmethane dyes such as (1-methylpyrrol-3-yl)-6-dimethylaminophthalide, 4゜4'-bis-dimethylaminobenzhydrylbenzyl ether, N
-halophenyl-leucoauramine, N-2,4,5-
) Diphenylmethane dyes such as dichlorophenyl 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-benzyl-spirodinaphthopyran,
Spiro dyes such as 3-methyl-naphtho(6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzobilane, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (
Lactam dyes such as 0-chloroanilino)lactam, 3
-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chloro Fluoran, 3-diethylamino-6,7
-Simethylfluorane, 3-(N-ethyl-P-)luidino)7-methylfluorane, 3-diethylamino-7
-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-
diethylamino-7-dibenzylaminofluorane, 3
-diethylamino-7-(N-methyl-N-benzylamino)fluorane, 3-diethylamino-7-(N-chloroethyl-N-methylamino)fluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(
N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl P-)luidino)-6-methyl-7-(p-1luidino)fluorane, 3-diethylamino- 6-Methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl-7-
Phenylaminofluorane, 3-diethylamino-7-
(2carbomethoxy-phenylamino)fluorane, 3
-(N-ethyl-N-isoamyl)amino-6methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluorane, 3-pyrrolidino -6-Methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-quizyridinofluorane, 3-diethylamino-7-( o-chlorophenylamino)fluoran, 3-dibutylamino-7-(.

chlorophenylamino)fluoran, 3-(N-ethyl-N-tetrahydrofurfuryl)amino 6-methyl-7
-phenylaminofluorane, 3-(N-methyl-N-
n-propyl)amino-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-p-
Butylphenylaminofluorane, 3-(N-ethyl-
N-npropyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-isobutyl)
amino-6-methyl-7-phenylaminofluorane,
3-(N-methyl-N-n-hexyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-n-hexyl)amino-6-methyl-7-phenylaminofluoran Fluoran dyes such as orane, 3-(N-ethyl-N-cyclopentyl)amino-6-methyl-7-phenylaminofluorane, and the like. Of course, the dyes are not limited to these dyes, and two or more types of dyes can be used in combination.

In the present invention, the coloring agent constituting the recording layer of the heat-sensitive recording medium is not particularly limited, and the coloring agent has the property of liquefying, vaporizing, or dissolving with an increase in temperature, and the above-mentioned basic coloring agent Various substances are used that have the property of causing coloration upon contact with dyes. As a typical example,
Inorganic acidic substances such as activated clay, acid clay, acpulgite, bentonite, colloidal silica, aluminum silicate, 4-tert-butylphenol, 4-hydroxyphenoxide, α-naphthol, β-naphthol, 4
-Hydroxyacetophenol, 4-tertoctylcatechol, 2,2'-dihydroxydiphenol,
2.2'-methylenebis(4-methyl-6-tart-
isobutylphenol), 4゜4゛-isopropylidene bis(2-tert-butylphenol), 4.4'
-5ec-butylidenediphenol, 4-phenylphenol, 4,4゜isopropylidenediphenol, 2,
2°-methylenebis(4-chlorophenol), hydroquinone, 4.4-cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate, hydroxymonobenzyl ether, 4
-Hydroxy-4"-isopropyloxydiphenylsulfone, 3'-4'-tetramethylene-4-hydroxydiphenylsulfone, 4,4°-(1,3-dimethylbutylidene)bisphenol, 4,4'-(1-
phenylethylidene) bisphenol, 4,4°-(p
Phenolic compounds such as -phenylene diisopropylidene) diphenol, 4°4°-(m-phenylene diisopropylidene) diphenol, novolak type phenolic resin, phenol polymer, benzoic acid, p-tert-
Butylbenzoic acid, trichlorobenzoic acid, terephthalic acid,
3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-human convexoxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butyl Salicylic acid, 3-hensylsalicylic acid, 3-(α-methylhensyl)salicylic acid, 3-chloro-5-(α-methylbenzylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5-(α, α-dimethylbenzyl)
Aromatic carboxylic acids such as salicylic acid, 3.5-di-α-methylbenzyl salicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. Salts with polyvalent metals, and complexes of salts of polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel with organic compounds such as antipyrine, pyridine, and dimethylaminoantipyrine. Examples include organic acidic substances.

The proportion of the coloring agent and basic dye in combination is not necessarily limited, but is 100 to 700 parts by weight, more preferably 150 to 4 parts by weight, per 100 parts by weight of the basic dye.
00 parts by weight of coloring agent is blended. Incidentally, two or more types of coloring agents may be used in combination as necessary.

The heat-sensitive recording layer coating solution containing these is generally prepared by using water as a dispersion medium and dispersing dyes, coloring agents, etc. together or separately using a stirring/pulverizing machine such as a ball mill or attritor sand mill. be done.

Such coating liquids usually contain starches and binders as binders.
Hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. have a total solid content. It is blended in an amount of about 10 to 40% by weight, preferably about 15 to 30% by weight.

Furthermore, various auxiliary agents can be added to the coating liquid.
For example, dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, ultraviolet absorbers such as triazoles, and other antifoaming agents,
Examples include fluorescent dyes and colored dyes. In addition, dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. are added to prevent sticking of the heat-sensitive recording material due to contact with recording equipment or recording heads. You can also do that.

Further, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 1. Hindered phenols such as 1, 3-tris(2-methyl-4-hydroxy-5-merL-butylphenyl)butane, 1,2-bis(phenoxy)ethane, 1゜2-bis(4-methylphenoxy) ethane, 12
Various known thermofusible substances such as ethers such as -bis(3-methylphenoxy)ethane and 2-naphthol benzyl ether, dibenzyl terephthalate, and esters such as -hydroxy-2-naphthoic acid phenyl ester may also be used in combination. It is possible.

In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined resin, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay can be added to further improve the adhesion of residue to the recording head. .

In the present invention, there is no particular limitation on the method of forming the recording layer. For example, the recording layer is formed by applying a coating liquid onto the intermediate layer using a coating device equipped with a suitable coater head such as an air knife coulter blade coater, and drying it. be done. Furthermore, the amount of coating liquid to be applied is not particularly limited, and is usually 2 to 12 g/bo, preferably 3 to 10 g/bo, in terms of dry weight.
It is in the range of about 1000 yen.

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

゛Please note that after coating and drying the intermediate layer and/or recording layer,
If necessary, smoothing treatment such as super calendering can also be applied. Furthermore, 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 field of heat-sensitive recording materials can be added, such as providing a coating layer on the support. .

The heat-sensitive recording material of the present invention thus obtained has an intermediate layer having a specific composition between the support and the heat-sensitive recording layer, so that pixel reproducibility is improved in all regions from low density to high density. It is an excellent heat-sensitive recording material that has a high recording density, excellent whiteness, and does not generate paper dust during cutting.

"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.

Further, unless otherwise specified, parts and percentages in the columns indicate parts by weight and percentages by weight, respectively.

Example 1 [Preparation of intermediate layer coating liquid-1] Urea formalin resin filler (trade name: (J-PEA)
RL C-120, manufactured by Mitsui Toatsu Co., Ltd., oil absorption ff1300
ml/100 g, secondary particle size Lop) 80
Styrene-butadiene copolymer latex (solid content: 5
0%) 15 parts Polyvinyl alcohol aqueous solution 1 (10% solution) 2 parts The above formulation was dispersed in water so that the solid content concentration was 20%.

[Formation of intermediate layer]

The obtained intermediate layer coating liquid-1 was applied to high-quality paper with a basis weight of 50 g/rd using an air knife coater so that the coating amount after drying was 8 g/n'f.
(Thickness: 13 μm) and dried. middle N
The fluidity of the paint was not good, making it difficult to feed the paint, and it was also somewhat difficult to control the amount of coating applied in the intermediate layer.

[Preparation of recording layer coating liquid]

■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane
10 parts dibenzyl terephthalate
20 parts methylcellulose 5% aqueous solution 15 parts water 8.0
This composition was ground in a sand mill until the average particle size was 3 μm.

■ Preparation of B solution 4. 30 parts of 4'-isopropylidene diphenol 5% methyl cellulose soluble i 30 parts of water
70 parts of this composition was ground in a sand mill until the average particle size was 2.1/m.

125 parts of liquid A, 130 parts of liquid B, silicon oxide pigment (oil absorption 1
80 m1/100 g), 150 parts of a 20% oxidized starch aqueous solution, and 55 parts of water were stirred and mixed to prepare a recording layer coating liquid.

[Formation of recording layer]

The obtained recording layer coating liquid was coated on the intermediate layer using an air knife coater so that the coated amount after drying was 5 g/rd, and dried to obtain a heat-sensitive recording paper.

Example 2 80 parts of the urea formalin resin filler of Example 1 (manufactured by Mitsui Toatsu Co., Ltd., oil absorption M 300 ml/100 g) was mixed with urea formalin resin filler (manufactured by Nippon Kasei Co., Ltd., oil absorption amount 500 ml f1).
/loog) 40 parts and fired clay (oil absorption 180mj!/
100 g) A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 40 copies were used. The fluidity of the intermediate layer paint was not good, making it difficult to feed the paint, and it was also somewhat difficult to control the amount of paint applied to the intermediate layer.

Example 3 80 parts of the urea-formalin resin filler of Example 1 was replaced with urea-formalin resin filler (trade name: U-PEARL C).
-120, manufactured by Mitsui Toatsu Co., Ltd., oil absorption 300 mjl! /10
0g) 20 parts and amorphous silica (oil absorption 150mjl!/
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the amount was changed to 60 parts (100 g). Although the fluidity of the intermediate layer paint was not necessarily good and it was somewhat difficult to control the amount of paint applied to the intermediate layer, there were no problems with the feeding of the paint.

Example 4 80 parts of the urea-formalin resin filler of Example 1 was replaced with urea-pormarine resin filler (trade name: U-PEARL C).
-120, manufactured by Mitsui Toatsu Co., Ltd., oil absorption 300mlf1/10
0g) 5 parts and calcined gee (oil absorption 80ml/100g)
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the volume was changed to 95 parts. The fluidity of the intermediate layer paint was extremely good and the coating suitability was excellent.

Example 5 80 parts of the urea-formalin resin filler of Example 1 was replaced with urea-formalin resin filler (trade name: U-PEARL).
C-120, manufactured by Mitsui Toatsusha, oil absorption! 3゜Oml/100
g) 13 parts and amorphous silica (oil absorption 100ml/100
g) A thermosensitive recording paper was obtained in the same manner as in Example (2) except that the amount was changed to 87 parts. The fluidity of the intermediate layer paint was extremely good and the coating suitability was excellent.

Comparative Example A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the urea-formalin resin filler was replaced with amorphous silica (oil absorption: 150 ml/100 g).

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the urea-formalin resin filler was replaced with a polystyrene filler (manufactured by Mitsui Toatsu Co., Ltd.).

Comparative Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that the urea-formalin resin filler in Example 1 was replaced with hollow fine particles (trade name: oP-42M, manufactured by Rohm and Haus).

Each thermal recording paper thus obtained was printed on a thermal printer (SO
Using a NY video printer, model UP-701), recording was performed at printing pulse times of 3 ms and 8 ms, and the color density was measured using a Macbeth densitometer (manufactured by Macbeth Co., Ltd.).

The results are shown in Table 1. In addition, the reproducibility of printed pixels, cutting suitability, whiteness, and head residue were evaluated, and the results are also listed in Table 1.

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

◎...86% or more O...76-85% △...70-75% ×...69% or less Evaluation was made based on the generation of paper dust when cutting the recording part and white abrasive part with a cutter, and the evaluation criteria were as follows.

◎・・・・・・No generation of paper powder and no peeling of the recording layer.

Good: No paper dust was generated, but there was slight peeling of the recording layer.

Δ: Generation of paper powder and peeling of the recording layer, but no practical problems.

×: Paper dust was significantly generated, and the recording layer often peeled off.

The whiteness was measured using a Digital Hunter whiteness meter (manufactured by Toyo Seiki Co., Ltd.).

In addition, regarding head scraps, NEFAX-27 (NEFAX-27
(manufactured by Company C), and the state of head residue after copying 10 sheets at a printing rate of 100% was evaluated by visual judgment. The evaluation criteria are as follows.

○...No head residue is seen.

x: Significant occurrence of head debris.

Table 1 "Effects" As is clear from the results in Table 1, the heat-sensitive recording material obtained in the examples of the present invention has excellent reproducibility of printed pixels in any region from low density to high density. The recording material had a high recording density, excellent strength and printing suitability, and excellent whiteness and head dregs.

Claims (5)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive recording layer is provided on a support, there is an oil absorption amount (JISK5) between the support and the heat-sensitive recording layer.
101 method) is provided with an intermediate layer containing an amino resin filler having a content of 200 ml/100 g or more. (2) Oil absorption capacity of the middle layer (JISK5101 method) 200m
The heat-sensitive recording material according to claim 1, which contains an amino resin filler having an oil absorption of 1/100 g or more and an inorganic filler or an organic filler having an oil absorption of less than 200 ml/100 g. (3) Claim (1) wherein the amino resin filler is secondary particles.
) or the heat-sensitive recording material according to claim (2). (4) The heat-sensitive recording material according to claim (1) or claim (2), wherein the intermediate layer contains 0.5 to 30% by weight of an amino resin filler having an oil absorption of 200 ml/100 g or more. (5) The thermosensitive recording material according to claim (1) or claim (2), wherein the intermediate layer contains 1 to 20% by weight of an amino resin filler having an oil absorption of 200 ml/100 g or more.