JPH06247042A - Heat sensitive recording paper - Google Patents

Abstract

PURPOSE:To provide heat sensitive recording paper for the second original drawing which has little texture fog and is superior in keeping properties of a recording image. CONSTITUTION:Heat sensitive recording paper is obtained by providing a heat sensitive recording layer containing colorless or light-colored basic dyes and a coloration agent and a protective layer consisting mainly of water-soluble resin in order on a semitransparent substrate which is obtained by infiltrating styrene acrylic resin into stencil paper and has opaqueness not exceeding 55%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording paper for a second original drawing which utilizes the reaction between a colorless or light-colored basic dye and a color former.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording which utilizes a color reaction between a color-forming agent and a color-forming agent which develops color by contacting with the color-forming agent, by contacting both color-forming substances with heat to obtain a color-developed image. The body is well known. Since 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.

For example, as one of the fields of use thereof, CA
With the expansion of D and CAM systems, the use of thermal recording paper as the printer paper is increasing. However, generally available thermal recording paper cannot be used as the second original drawing paper for CAD and CAM because of its high opacity. A method of impregnating a base paper with an acrylic resin or a compound having an isocyanate group in order to obtain a heat-sensitive recording paper for a second original is disclosed in JP-A-61-108581 and JP-B-57-58.
Although it is described in Japanese Patent No. 16913, there are problems in the background fog and the preservability of recorded images.

[0004]

SUMMARY OF THE INVENTION The present invention provides a heat-sensitive recording paper for a second original image, which has less background fog and is excellent in preservability of recorded images.

[0005]

Means for Solving the Problems The inventors of the present invention have prepared a transparent or colorless basic dye on a semitransparent support having an opacity of 55% or less obtained by impregnating a base paper with a styrene-acrylic resin. By sequentially providing a thermosensitive recording layer containing a color former and a protective layer containing a water-soluble resin as a main component, a thermal recording paper for a second original image having less background fog and excellent storage stability of the recorded image can be obtained. This has led to the completion of the present invention.

[0006]

[Function] As the translucent base paper, there is glassine paper obtained by beating pulp to a high degree or chemically modifying it, in addition to the base paper impregnated with a resin dissolved in an organic solvent. Generally, the glassine paper has a weak paper strength and is curled, so that the paper is easily broken when the thermal recording layer is provided. Also, thermal recording paper using resin-impregnated base paper causes background fog and fading of recorded elephants depending on the type of resin, but those impregnated with styrene / acrylic resin can cause background fog and fading of recorded elephants. Was few.

The styrene-acrylic resin used in the present invention is a copolymer of styrene and an acrylic ester such as methyl methacrylate, methyl acrylate, butyl methacrylate, and butyl acrylate. It is more than 50%. When the ratio of the acrylic component is high, the storability of the recorded image is deteriorated. Those having a molecular weight of 5,000 to 12,000 are excellent as a clarifying agent. The base paper impregnated with the styrene / acrylic resin is not particularly limited, and examples thereof include high-quality paper, base paper made with a Yankee machine, single-sided glossy base paper, and double-sided glossy base paper. The basis weight is preferably ^{20 to} 150 g / m ² , and more preferably 30 to 100 g / m ² . In particular, when the basis weight exceeds 150 g / m ² , the amount of resin impregnated increases in order to obtain the desired opacity, and the workability deteriorates.

The amount of resin impregnated for making the opacity of the base paper 55% or less varies depending on the basis weight of the base paper, but is adjusted to a dry weight of ² to 20 g / m ^{2 on} one side or both sides of the base paper. Is desirable. After impregnating the resin, it is possible to further reduce the opacity by performing a smoothing treatment such as a super calendar. Further, if the opacity of the base paper impregnated with the resin exceeds 55%, the suitability for diazo copying as the second original drawing paper is deteriorated.

As the colorless or light-colored basic dye constituting the heat-sensitive recording layer provided on the support thus obtained, various types are known, and the following are exemplified. 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-3)
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindole-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- (1-methylpyrrol-3-yl) -6
-Triarylmethane dyes such as dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leukoauramine, N-2,4,5-trichlorophenylleucoaamine, etc. Diphenylmethane dyes, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and other thiazine dyes, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-
Phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-
Spiro dyes such as dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluorane, 3- Diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane,
3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Diethylamino-6,7-dimethylfluorane, 3-
(N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino- 7-dibenzylaminofluorane, 3-diethylamino-7-N
-Methyl-N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3- (N-ethyl-p-toluidino) −
6-methyl-7-phenylaminofluorane, 3- (N
-Ethyl-p-toluidino) -6-methyl-7- (p-
Toluidino) fluorane, 3-dimethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3
-Di-n-butylamino-6-methyl-7-phenylaminofluorane, 3-di-n-pentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-carbomethoxy -Phenylamino) fluorane, 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-
Xylidinofluorane, 3-diethylamino-7- (o
-Chlorophenylamino) fluorane, 3-di-n-butylamino-7- (o-chlorophenylamino) fluorane, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3- (N-methyl-) N-n-
Amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-amyl) amino-
6-methyl-7-phenylaminofluorane, 3- (N
-Ethyl-N-isoamyl) amino-6-methyl-7-
Phenylaminofluorane, 3- (N-methyl-Nn)
-Hexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-hexyl) amino-6-methyl-7-phenylaminofluorane, 3
-(N-ethyl-N-β-ethylhexyl) amino-6
-Methyl-7-phenylaminofluorane, 3- (N-
Ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-cyclopentyl) amino-6-methyl-7-phenylaminofluorane, 2,2-bis {4- [6'-
(N-Cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2 '
Fluorane dyes such as -ylamino] phenyl} propane. Of course, it is not limited to these dyes,
A combination of two or more dyes is also possible.

Various compounds are known as colorants used in combination with the above basic dyes, and the following are exemplified. 4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol,
4-tert-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,
4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol, hydroquinone, 4,
4'-cyclohexylidene diphenol, 4,4'-
(1,3-dimethylbutylidene) bisphenol, 2,
2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-dihydroxydiphenyl Sulfone, 2,4'-dihydroxydiphenyl sulfone,
4-hydroxy-4'-methyldiphenyl sulfone, 4
-Hydroxy-4'-methoxydiphenyl sulfone, 4
-Hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'-trimethylene diphenyl sulfone, 4-hydroxy-3', 4'-tetramethylene diphenyl sulfone, 3,4-dihydroxy-
4'-methyldiphenyl sulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 1,3-di [2-
(4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxy Benzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, 4-
Propyl hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, 4
-Phenyl hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-p- Chlorobenzyl, 4
-Hydroxybenzoic acid-p-methoxybenzyl, novolac type phenolic resin, phenolic compounds such as phenolic polymers, 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, salicylic acid, 3-isopropylsalicylic acid,
3-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3-phenyl −5- (α,
α-Dimethylbenzyl) salicylic acid, 3,5-di-α-
Aromatic carboxylic acids such as methylbenzyl salicylic acid, and organic acidic substances such as phenolic compounds, salts of aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel etc. Of course, the above-mentioned coloring agents can also be used as needed.
One or more species can be used in combination.

The use ratio of the basic dye and the color developing agent should be appropriately selected according to the types of the basic dye and the color developing agent to be used and is not particularly limited, but in general, the basic dye 1 is used.
About 100 to 700 parts by weight, preferably about 150 to 400 parts by weight, of the coloring agent is used with respect to 00 parts by weight.

It is preferable that the coating liquid containing them is generally made fine so as to have an average particle diameter of 1 μm or less by using water as a dispersion medium and a stirring / pulverizing machine such as a ball mill, an attritor or a sand mill. Also, the coating liquid is a basic dye,
It is prepared as a coating liquid having a solid content concentration of 20% by weight or more by dispersing a coloring agent, a binder and the like together or separately, and various auxiliary agents can be added to the coating liquid. , For example dioctyl sulfosuccinic acid sodium salt,
Examples thereof include dispersants such as sodium dodecylbenzenesulfonic acid salt, sodium lauryl alcohol sulfate / sodium salt and fatty acid metal salt, and other defoaming agents, fluorescent dyes, coloring dyes and the like.

Further, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, in order to improve dust adhesion to the recording head,
Inorganic pigments such as activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch particles can also be added. In addition, stearic acid, which prevents sticking due to contact with the recording equipment and recording head,
It is also possible to add a dispersion liquid or emulsion of polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax or the like.

Further, in the heat-sensitive recording material of the present invention, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide are used as long as the desired effects of the present invention are not impaired. , 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl) -4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-
Hindered phenols such as tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, p
-Benzylbiphenyl, p- (4-tolyloxy) biphenyl, 1,5-bis (4-methoxyphenoxy) -3
-Oxa-pentane, 1,2-bis (phenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane,
1,2-bis (3-methylphenoxy) ethane, 1-
Ethers such as (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 2-naphtholbenzyl ether, dibenzyl terephthalate, 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid Esters such as di (4-methylbenzyl) ester and oxalic acid di (4-chlorobenzyl) ester, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone It is also possible to use an ultraviolet absorber such as the above and various known heat-fusible substances together as a sensitizer. Among these heat-fusible substances, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (phenoxy) ethane, 1- (2-methylphenoxy) -2-
(4-methoxyphenoxy) ethane, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester, p-
Benzylbiphenyl, p- (4-tolyloxy) biphenyl, and 1,5-bis (4-methoxyphenoxy)-
3-Oxa-pentane is more preferable because it exhibits a particularly excellent sensitizing effect in relation to a specific storage stability improver.
The amount of the heat-fusible substance used is not particularly limited, but is generally 50 to 1000 parts by weight, preferably 100 to 500 parts by weight with respect to 100 parts by weight of the basic dye.
It is desirable to use it in the range of parts by weight.

As a binder in the coating liquid, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, arabic gum, carboxy modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol,
Silicon modified polyvinyl alcohol, fully saponified and partially saponified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer A salt, a styrene-butadiene copolymer emulsion or the like is used in an amount of 10 to 40% by weight, preferably 15 to 30% by weight, based on the total solid content.

The method of coating the recording layer is not particularly limited, and the coating liquid for the heat-sensitive recording layer is applied onto paper impregnated with resin, for example, an air knife coater, a rod blade coater,
Bar coater, gravure coater, curtain coater,
It is formed by a method such as coating and drying with a suitable coating device such as a short dwell coater. Moreover, the coating amount of the coating liquid is not particularly limited, and generally 2 to 2 in terms of dry weight.
10 g / m ² approximately, it is preferably adjusted in the range of about 3 to 6 g / m ^2.

According to the present invention, by providing a protective layer containing a water-soluble resin as a main component on the heat-sensitive recording layer, not only the preservation of chemicals of the recording image but also the effect of reducing opacity can be obtained. Specific examples of the water-soluble resin used in such a protective layer include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-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, urea resin, melamine resin, amide resin,
Examples thereof include polyurethane resins, and among them, acetoacetyl group-modified polyvinyl alcohol and carboxy-modified polyvinyl alcohol are particularly preferably used because they form a strong film and have excellent transparency.

A pigment may be added to the protective layer, if necessary, in order to further improve printability and sticking. Specific examples thereof include calcium carbonate,
Inorganic pigments such as zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea Examples include formalin resin fillers and organic pigments such as raw starch particles. It is generally desirable to adjust the amount used in the range of about 5 to 30 parts by weight with respect to 100 parts by weight of the binder component. If the amount of the pigment added exceeds 30 parts by weight, the copying ability for diazo copying is deteriorated.

Further, in the protective layer coating liquid, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, etc., and a surfactant (dispersion such as dioctyl sulfosuccinate) (dispersion), if necessary. Agent, wetting agent), defoaming agent,
Various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate may be appropriately added. Further, in order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, and an epoxy compound can be used in combination. The coating liquid for forming the protective layer is
Generally, water is used as the dispersion medium.

The coating solution for protective layer thus prepared is coated on the thermosensitive recording layer by an appropriate coating device. However, if the coating amount exceeds 10 g / m ² in dry weight, the recording sensitivity may decrease. Generally, it is desired to be adjusted in the range of 0.1 to 10 g / m ² , preferably 0.5 to 5 g / m ² .

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples represent parts by weight and% by weight, respectively.

Example 1 Preparation of Liquid A 10 parts of 3-di (n-butyl) amino-6-methyl-7-phenylaminofluorane, 15 parts of 1,2-bis (4-methylphenoxy) ethane, 5 parts of methylcellulose % Aqueous solution of 15 parts and water of 80 parts were pulverized with a sand mill until the average particle size became 1 μm.

Preparation of Liquid B A composition consisting of 30 parts of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 30 parts of a 5% aqueous solution of methylcellulose, and 70 parts of water was pulverized with a sand mill until the average particle diameter became 1 μm.

[0024] one surface of woodfree paper having formed a basis weight 58 g / m ² of a translucent paper, styrene copolymer of methyl methacrylate-butyl acrylate (molecular weight:
A solution of 9500) dissolved in a mixed solvent of toluene and methyl ethyl ketone in an amount of 30% was applied and dried to a dry weight of 5 g / m ^2, and then supercalendered to obtain semi-transparent paper.

Formation of Thermosensitive Recording Layer 120 parts of A liquid, 130 parts of B liquid, 50 parts of styrene-butadiene latex having a solid concentration of 45%, and 30 parts of water were mixed and stirred to obtain a coating liquid for the thermosensitive recording layer. Was coated and dried on the above semi-transparent paper so that the coating amount after drying was 5 g / m ² to form a heat-sensitive recording layer.

Formation of protective layer 300 parts of 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol, 15 parts of 30% dispersion of zinc stearate,
A coating solution for forming a protective layer obtained by mixing and stirring a composition comprising 50 parts of water and 5 parts of a 10% aqueous solution of glyoxal was coated on the thermosensitive recording layer to give a coating amount of 1.5 g after drying.
It was coated and dried so as to be / m ^2, and subjected to a super calendar treatment to obtain a heat-sensitive recording paper.

Example 2 In the formation of the semi-transparent paper of Example 1, a copolymer of styrene / methyl methacrylate / butyl acrylate (molecular weight:
A thermal recording paper was obtained in the same manner as in Example 1 except that a copolymer of styrene and methyl methacrylate (molecular weight: 11000) was used instead of 9500).

Comparative Example 1 In the formation of the semi-transparent paper of Example 1, a copolymer of styrene / methyl methacrylate / butyl acrylate (molecular weight:
9500) was dissolved in a mixed solvent of toluene and methyl ethyl ketone in an amount of 30%, and a styrene / maleic anhydride copolymer was added in a mixed solvent of toluene and methanol in an amount of 25%.
A heat-sensitive recording paper was obtained in the same manner as in Example 1 except that a solution in which the temperature was dissolved was used.

Comparative Example 2 Example 1 is the same as Example 1 except that the protective layer is not provided.
A thermosensitive recording paper was obtained in the same manner as in (1).

Comparative Example 3 In the formation of the semi-transparent paper of Example 1, a copolymer of styrene / methyl methacrylate / butyl acrylate (molecular weight:
9500, the proportion of styrene component in the copolymer is 60%)
Instead of, a polymer of methyl methacrylate (molecular weight: 90
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that (00) was used. The thus-obtained five types of heat-sensitive recording papers were subjected to quality evaluation by the following methods, and the results are shown in Table 1.

[Recording Density] A thermosensitive recording simulator [TH-PDM type manufactured by Okura Electric Co., Ltd.] was used to record under the condition of an applied head energy of 0.4 mJ / dot, and the density of the recorded image obtained was Macbeth density. Total [Macbeth RD9
14].

[Opacity] The opacity was measured according to JIS-P8138. [Preservation of Recorded Image] The thermosensitive recording paper after recording with a thermosensitive recording simulator was left to stand under the condition of 40 ° C.-90% RH for 48 hours, and the fog on the recording part and the background part was measured by a Macbeth densitometer. [Aptitude for diazo copying of thermosensitive recording paper] A thermosensitive recording paper recorded by a facsimile machine [Panafax UF5, manufactured by Matsushita Electric Transmission Co., Ltd.] is used as a master, and a diazo copying machine [manufactured by Ricoh Company, Recopy SUPER DRY]
100 type], and the resulting copy image and the density of the background part were measured with a Macbeth densitometer.

[0033]

[Table 1]

[0034]

As is clear from the results of Table 1, the thermosensitive recording paper of the present invention was a thermosensitive recording paper for the second original image which had less background fog and was excellent in preservability of recorded images.

Claims (1)

[Claims] 1. A heat-sensitive recording layer containing a colorless or light-colored basic dye and a coloring agent on a semitransparent support having an opacity of 55% or less obtained by impregnating a raw paper with a styrene-acrylic resin. A thermal recording paper comprising a protective layer containing a water-soluble resin as a main component in order.