JP2002178635A - Pressure sensitive copying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost pressure sensitive copying material excellent in the solubility and color forming performance of a color former by a method wherein a lower aromatic hydrocarbon solvent is employed. SOLUTION: The lower aromatic hydrocarbon solvent as a pressure sensitive copying material solvent is obtained through a process (1) for obtaining a low sulfur kerosene fraction having a sulfur content of 5 ppm or less through the desulfurization of a kerosene fraction having its boiling point lying in the range of 150 to 300 deg.C at 100 to 400 deg.C under the pressure of 1 to 20 MPa in the presence of a catalyst and then the removal of a gas-containing more volatile component, a process (2) for obtaining residual oil through the separation and recovery of normal paraffin from the low sulfur kerosene fraction obtained in the process (1) with a molecular sieve made of a synthetic zeolite and a process (3) for obtaining the lower aromatic hydrocarbon solvent having the total content of a monocycloalkane and a dicycloalkane of 40 mass % or more and the content of an aromatic hydrocarbon of 1 mass % or less through the nuclear hydrogenation of the residual oil obtained in the process (2) at 50 to 400 deg.C under the pressure of 1 to 20 MPa in the presence of a catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure-sensitive method using a low aromatic hydrocarbon solvent from which straight-chain paraffin is removed and the content of aromatic hydrocarbon is 1% by mass or less as a solvent for an electron-donating color former. Related to copying materials.

[0002]

2. Description of the Related Art Conventionally, a colorless electron-donating color forming agent (hereinafter referred to as "color forming agent") is incorporated in a microcapsule film in a solution state and applied on one surface of a paper, and then applied to another surface of another paper. An acidic inorganic material having a property of forming a color by reacting with the color forming agent, and an electron accepting substance such as carboxylic acid (hereinafter referred to as a "color developing agent") are applied, and these applied surfaces are opposed to each other when used. 2. Description of the Related Art A recording material of a type in which a copy record is obtained by superposing and superimposing and pressurizing, that is, a pressure-sensitive copying material is known. The copy recording mechanism of this type of recording material destroys the microcapsule film by pressure such as writing pressure, type pressure, etc.
The color developing solution is released, and the color forming agent comes into contact with the color developing agent applied to the surface of the paper placed opposite to the color forming agent to form a color.
Further, there is also known a recording material in which each coating material such as a microcapsule or a color developer having a coloring function of this kind is coated on one side of one sheet of paper. The coloring agent solution used in these recording materials is a solution in which an electron-donating coloring material is dissolved in one or more kinds of hydrophobic solvents. The hydrophobic solvent used here must satisfy the following requirements. That is, it has no toxicity. It has no unpleasant odor. It is colorless or very pale color. It has good solubility of the color forming agent and its solution is stable. It is easy to microencapsulate. Storage stability of microcapsules. The color development rate is high without hindering the color development reaction. The color development image is not blurred, and a clear color development image can be obtained even after long-term storage.

Conventionally, as a solvent for this type of recording material, an aromatic compound having a plurality of aromatic rings such as diarylalkanes such as phenylxylylethane and phenylethylphenylethane, alkylnaphthalenes, alkylbiphenyls and partially hydrogenated terphenyls has been known. Hydrocarbon oils or chlorinated paraffins are used. However, these solvents are expensive, and the color-forming performance of pressure-sensitive copying materials using these solvents is not always satisfactory. Further, a method using linear paraffin or an alicyclic hydrocarbon as a solvent for a pressure-sensitive copying material is disclosed in JP-A-2-47083, JP-A-2-47083.
No. 47084. According to these methods, although the performance such as the low-temperature coloring speed is improved, there are problems such as poor solubility of the coloring agent and poor operability in the production of microcapsules.

[0004]

SUMMARY OF THE INVENTION The present invention solves these problems of the conventional pressure-sensitive copying material, and provides an inexpensive pressure-sensitive copying material which is excellent in solubility and color-forming performance of a color former. It is.

[0005]

A first aspect of the present invention relates to a pressure-sensitive copying material characterized by using a low aromatic hydrocarbon solvent obtained in the following steps (1) to (3). . Step (1): A kerosene fraction having a boiling point in the range of 150 to 300 ° C in the presence of a catalyst at a temperature of 100 to 400 ° C and a pressure of 1
After desulfurization under the conditions of ２０20 MPa, a gas-containing light component is removed to obtain a low-sulfur kerosene fraction having a sulfur content of 5 ppm or less. Step (2): The above-mentioned step (2) is performed by a molecular sieve composed of synthetic zeolite. A step of separating and recovering linear paraffin from the low-sulfur kerosene fraction obtained in 1) to obtain a residual oil, and step (3): converting the residual oil obtained in step (2) to a temperature of 50 to 50 in the presence of a catalyst. By performing nuclear hydrogenation under the conditions of 400 ° C. and a pressure of 1 to 20 MPa, the total content of monocycloalkane and dicycloalkane is 40% by mass or more and the content of aromatic hydrocarbon is 1% by mass or less. A step of obtaining a certain low aromatic hydrocarbon solvent. A second aspect of the present invention is a pressure-sensitive copying material using an electron-accepting color developer and a color-forming agent solution obtained by dissolving an electron-donating color-forming agent that forms a color in contact with the developer in a solvent. The present invention relates to a pressure-sensitive copying material characterized in that the solvent contains an aromatic hydrocarbon having two or more non-condensed or condensed aromatic rings and the above-mentioned low aromatic hydrocarbon solvent. The third aspect of the present invention relates to the pressure-sensitive copying material according to the second aspect of the present invention, comprising a microcapsule containing the color former solution and a sheet-like support holding the microcapsule.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The low aromatic hydrocarbon solvent used in the present invention has a boiling point of 15
It is produced as follows using a kerosene fraction in the range of 0 to 300 ° C as a raw material. First, usually 200-
A sulfur content of about 1000 ppm is removed using a desulfurization catalyst. If these sulfur compounds remain, they have an adverse effect on subsequent steps. These poison the synthetic zeolite used as an adsorbent in the step of removing normal paraffin, and poison the hydrogenation catalyst used in the step of aromatic nuclear hydrogenation to shorten the catalyst life. Further, these sulfur compounds are unfavorable because they cause corrosion of equipment and piping. In the present invention, the sulfur content needs to be 5 ppm or less, preferably 1 ppm.
ppm or less.

As the desulfurization catalyst, any catalyst can be used as long as it has a capability of desulfurizing until the sulfur content in the raw material becomes 5 ppm or less, preferably 1 ppm or less. For example, as is conventionally known,
A material in which at least one component selected from a metal element belonging to Group VI or Group VIII and an oxide or sulfide thereof is supported on an inorganic oxide carrier can be used.
As the inorganic oxide carrier, alumina, silica, silica-alumina, crystalline aluminosilicate, zeolite, diatomaceous earth, activated carbon and the like can be used. As the Group VI metal, molybdenum, tungsten, and the like can be used. Nickel, cobalt, or the like can be used as the Group VIII metal. Group VI and VIII metals can also be used in mixtures.

As desulfurization conditions, the temperature is 100 to 400.
° C, pressure is 1-20MPa, LHSV is 0.1-10h
It can be selected from the range of r- ¹ . Outside of these conditions, desulfurization is not sufficient, which is not preferable. The gas and light components generated after desulfurization are separated and removed by an operation such as distillation. As described above, a low sulfur kerosene fraction having a sulfur content of 5 ppm or less can be obtained.

Next, at least a part of normal paraffins contained in the low sulfur kerosene fraction is separated and recovered using a molecular sieve made of synthetic zeolite. Normal paraffins must be removed as much as possible because the solubility of the coloring agent is low. It is preferably removed so as to be 20% by mass or less, more preferably 10% by mass or less.
The method of separating normal paraffins from a hydrocarbon mixture using a molecular sieve has been widely and industrially practiced as a method for producing normal paraffins. For example, using a molecular sieve made of synthetic zeolite having a large number of pores adjusted to 5 ° as a fixed bed, adsorption and desorption of normal paraffins are alternately performed in a liquid phase, and desorption of synthetic zeolite adsorbing normal paraffins Wash with low molecular weight paraffin to desorb normal paraffins,
There is a Molex method in which mixed low molecular weight paraffin is separated by distillation and recycled. In addition, normal paraffins are adsorbed in the gas phase using adsorption and desorption to a synthetic zeolite also having 5% pores, and the desorption is carried out by washing with low molecular weight paraffin, TSF method (Texaco Selective Finishing method). There is an iso-sieve method in which normal paraffins are absorbed and desorbed by alternately repeating pressurization and decompression using a synthetic zeolite having 5 ° pores. In addition, the adsorption of normal paraffins to synthetic zeolite with 5Å pores is performed continuously in the liquid state in the adsorber, and the desorption is performed in the regenerator by adsorption in the regenerator by a method combining vapor phase and liquid bed method. There is an Esso method in which the synthetic zeolite regenerated by operating at a high temperature is returned from the regenerating device to the adsorption device and circulated again. The separation and recovery of normal paraffins in the present invention can be performed by any of the above methods.
The residual oil from which at least a part of the normal paraffins has been removed is subjected to the next step.

Next, nuclear hydrogenation of aromatic hydrocarbons contained in the residual oil after the separation and recovery of normal paraffins is performed. Nuclear hydrogenation is carried out using a hydrogenation catalyst, but any type may be used as long as it allows nuclear hydrogenation of aromatic hydrocarbons, and is not particularly limited. For example, a material in which at least one component selected from metal elements belonging to Group VIII and oxides and sulfides thereof are supported on an inorganic oxide carrier can be used. As the inorganic oxide carrier, alumina, silica, silica-alumina, crystalline aluminosilicate, zeolite, diatomaceous earth, activated carbon and the like can be used. As the Group VIII metal, nickel, cobalt, platinum, rhodium, ruthenium, palladium, cobalt and a mixture thereof can be used.

As the hydrogenation conditions, the temperature is 50 to 400.
° C, pressure is 1-20MPa, LHSV is 0.1-30h
It can be selected from the range of r- ¹ . If the reaction conditions are too mild, the aromatic hydrogenation reaction does not proceed sufficiently and a large amount of the aromatic component remains. Conversely, if the reaction conditions are too severe, side reactions such as hydrogenolysis occur, which is not preferable. After the nuclear hydrogenation treatment, distillation may be appropriately performed.

The low aromatic hydrocarbon solvent obtained as described above mainly comprises components having a boiling point in the range of 150 to 300 ° C., and the total of monocycloalkanes and dicycloalkanes is 4%.
It is characterized in that it is 0% by mass or more and the aromatic content is 1% by mass or less. As described above, since there is little aromatic substance, there is little odor and it is excellent also in terms of improvement of working environment.

In the present invention, the above-mentioned low aromatic hydrocarbon solvent is used as a solvent for dissolving the electron-donating color former in the pressure-sensitive copying material, but can be used in combination with another solvent. When used together with an aromatic hydrocarbon solvent having two or more non-condensed or condensed aromatic rings, 5 to 50% by mass of a low aromatic hydrocarbon solvent having a boiling point of 2
50 to 95% by mass of an aromatic hydrocarbon solvent having at least two non-condensed or condensed aromatic rings at 60 ° C. or higher
It is preferred that When the amount of the aromatic hydrocarbon solvent exceeds 95% by mass, no improvement in coloring properties is observed, and no cost reduction effect is observed. If the amount is less than 50% by mass, the solubility of the color former is low, which is not preferable.

Examples of the hydrocarbon solvent having two or more non-condensed or condensed aromatic rings include phenylxylylethane, phenylethylphenylethane, phenylcumylethane and phenyl-sec-butylphenylmethane. Dialkylalkanes such as diarylalkane, diisopropylnaphthalene, alkylbiphenyl or dichloroalkylbiphenyl such as sec-butylbiphenyl and isopropylbiphenyl, and partially hydrogenated terphenyl.

The electron-accepting color developer used in the pressure-sensitive copying material of the present invention includes aromatic carboxylic acids, polymers thereof, metal salts thereof, polyvalent metallated carboxyl-modified terpene phenol resins, and derivatives thereof, and It is preferable to use a developer selected from the group consisting of these mixtures. Conventionally, novolak-type phenolic resins, which are generally used as a color developer of a copying material, especially a pressure-sensitive copying material, have a pressure-sensitive copying material having an excellent color-forming speed even if the solvent composition of the present invention is used. Paper is not available.

Here, the aromatic carboxylic acid as a color developer is an organic compound in which a carboxyl group is directly bonded to an aromatic ring (either monocyclic or polycyclic). A salicylic acid derivative such as 3,5-di- (α-methylbenzyl) salicylic acid,
(Α-methylbenzyl) -5- (α, α′-dimethylbenzyl) salicylic acid, 3- (4′-α, α′-dimethylbenzyl) phenyl-5- (α, α′-dimethylbenzyl) salicylic acid, , 5-Di-tert-butylsalicylic acid, 3,5-di-tert-octylsalicylic acid, 3-cyclohexyl-5- (α, α′-dimethylbenzyl) salicylic acid, 3-phenyl-5- (α, α′- Examples thereof include dimethylbenzyl) salicylic acid and 3,5-di- (α, α′-dimethylbenzyl) salicylic acid. Further, aromatic carboxylic acids to which styrenes are added, such as styrenated salicylic acid, are also included. Particularly preferred aromatic carboxylic acids are aromatic carboxylic acids having a total carbon number of 15 or more. However, when used as a co-condensation or copolymerization monomer described below, the number of carbon atoms is not particularly limited.

Also, a condensation or co-condensation resin using an aromatic carboxylic acid, particularly salicylic acid as a condensation monomer can be used. Examples of such a co-condensation resin include a co-condensation resin of salicylic acid and dialkoxyxylene, and a polymer of salicylic acid and aldehyde. To these, a trialkylbenzene or the like can be further added as a cocondensation monomer.

Further, metal salts of these aromatic carboxylic acids or polymers thereof can also be used. Examples of the metal salt include polyvalent metal salts such as zinc, aluminum, barium, tin, iron, calcium, and lead. As the polyvalent metallated carboxyl-modified terpene phenol resin or a derivative thereof, a product obtained by condensing a cyclic monoterpene and a phenol in the presence of an acidic catalyst and introducing a carboxyl group into the polyvalent metal terpene by a conventional method is used. And a polyvalent metallated carboxyl-modified terpene phenol resin. For example, as disclosed in JP-A-62-19486, phenol and α-pinene are condensed with a boron trifluoride catalyst, and then a co-condensation resin obtained by introducing carbon dioxide gas in the presence of metallic sodium is used. Carboxylated, and further polyvalent metalized with zinc chloride or the like, to produce a polyvalent metallated carboxyl-modified terpene phenol resin. Examples of the polyvalent metal in this case include zinc, aluminum, barium, tin, iron, calcium, and lead. Preferably it is zinc.

An aromatic carboxylic acid, a polymer thereof, a metal salt thereof, and a polyvalent metallated carboxyl-modified terpene phenol resin as a color developer can be used as a mixture. This mixing can be carried out in a solvent or a dispersion medium or by melt mixing.

As the electron-donating color former used in the pressure-sensitive copying material of the present invention, triarylmethane, diphenylmethane, xanthene, thiazine, spiropyran and the like can be used. Specifically, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone; hereinafter, referred to as “CVL”) as a triarylmethane-based color former;
3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl)-(1,2-
Dimethylindol-3-yl) phthalide, 3- (p-
Dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-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-ethylcarbazole-3- Yl) -5-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6
-ヂ methylaminophthalide and the like.

As the diphenylethane coloring agent, 4,
4'-bisdimethylaminobenzhydrin benzyl ether, N-halophenylleuco auramine, N-2,4,
5-trichlorophenylleuco auramine and the like.

Examples of the xanthene-based color former include rhodamine B-anilinolactam, rhodamine B (p-nitroanilino) lactam, and rhodamine B (p-chloroanilino).
Lactam, 3-dimethylamino-6-methoxyfluora-3-diethylamino-7-methoxyfluoran, 3-
Diethylamino-7-chloro-6-methylfluoran,
3-diethylamino-7- (acetylmethylamino) fluoran, 3-diethylamino-7- (dibenzylamino) fluoran, 3-diethylamino-7- (methylbenzylamino) fluoran, 3-diethylamino-7-
(Chloroethylmethylamino) fluoran, 3-diethylamino-7- (diethylamino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran and the like.

Examples of the thiazine-based color former include benzoyl leucomethylene blue and p-nitrobenzyl leucomethylene blue.

Examples of spiropyran-based coloring agents include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, and 3-benzyl-spiro-dinaphthopyran.
Methyl-naphtho- (3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzodipyran and the like.

A general method for producing the pressure-sensitive copying material of the present invention, for example, pressure-sensitive copying paper will be described. The color former is 1 to
A solution dissolved in the above solvent at a ratio of 10% by weight is emulsified and dispersed in a mixed aqueous solution of gelatin and arabic gum, and then a gelatin film is formed around oil droplets emulsified by a coacervation method to perform microencapsulation. . Recently, a method of microencapsulation with a synthetic resin film by an In-Situ polymerization method, an interfacial polymerization method, or the like has been widely used.

The capsule emulsion of fine oil droplets thus produced is applied to paper as a sheet-like support,
A pressure-sensitive copying material such as pressure-sensitive copying paper is manufactured by applying the color developer in a layer on the surface of the paper facing the coated surface or on the coated surface itself.

[0027]

The present invention will be described below with reference to examples. [Example of preparation of solvent] The raw kerosene was desulfurized and subjected to the Molex method (UO
After the normal paraffin-removed residual oil (raffinate) obtained by the P adsorption method) was subjected to nuclear hydrogenation treatment under the conditions shown in Table 1 using a Ni / diatomaceous earth catalyst, the reaction solution was distilled by a precision distillation apparatus to give a boiling point of 203. The fraction at ~ 220 ° C was used as a solvent in the following examples. Table 1 shows the properties of the obtained solvent.

[0028]

[Table 1]

[Solvent odor evaluation test] The low aromatic hydrocarbon solvent (solvent 1) obtained in the above solvent preparation example was compared with the hydrocarbon solvent not subjected to nuclear hydrogenation treatment in the above solvent preparation example as a comparative example. (Solvent 2) Men and women in good health 10
The odor was evaluated in five stages by name, and the average value was obtained. As shown in Table 2, the hydrocarbon solvent which was not subjected to nuclear hydrogenation (Solvent 2) had an odor, but the low aromatic hydrocarbon solvent (Solvent 1) used in the present invention was almost odorless, so the working environment was low. It is effective for improvement.

[0030]

[Table 2]

(Example 1) [Solubility test of coloring agent] 20% by mass of the low aromatic hydrocarbon solvent (solvent 1) obtained in the above solvent preparation example and phenylxylyl which is a bicyclic aromatic hydrocarbon Ethane “Nisseki Hisol SAS-296”, (trade name, Nippon Petrochemical Co., Ltd.)
5 g of crystal violet lactone (CVL), which is a color former for blue, in 20 g of a mixed solvent of 80% by mass).
After adding and heating and dissolving for 16 hours, the amount of dissolution was measured with a Fourier transform infrared spectrophotometer (FT-IR). In addition, it was represented by the dissolved amount g of the coloring agent dissolved per 100 g of the solvent. As a comparative example, normal paraffin H (trade name, manufactured by Nippon Petrochemical Co., Ltd.) as a straight-chain paraffin solvent and Isosol 400 (trade name, manufactured by Nippon Petrochemical Co., Ltd.) as an isoparaffin solvent were each used for Nisseki Hisol. The solvent mixed with SAS-296 was similarly evaluated. Table 3 shows the results. In the case of the present invention using the low aromatic hydrocarbon solvent (solvent 1), the solubility was excellent.

[0032]

[Table 3]

Example 2 Evaluation of Coloring Performance CVL was added to a mixed solvent of 20% by mass of the low aromatic hydrocarbon solvent (solvent 1) and 80% by mass of phenylxylylethane obtained in the above solvent preparation example. The solution in which 5% by mass was dissolved was subjected to In-S using urea and formalin.
Microcapsules were formed by the itu polymerization method, and a paste and a protective agent were added to the obtained microcapsule emulsion, and the resulting microcapsule was applied to a high-quality paper using a wire bar to obtain a top paper of pressure-sensitive copying paper. Also, a lower paper sheet coated with zinc 3,5-di (α-methylbenzyl) salicylate is prepared as a color developer, and the upper paper sheet and the lower paper sheet are placed so that the microcapsule-coated surface faces the color developer. And color development was performed at a low temperature (-3 ° C.) using an impact printing machine. 3 seconds to 1 after color development (after impact)
After 20 seconds, the reflectance of the lower paper was measured using a reflection spectrophotometer to determine the coloring intensity. In addition, as a comparative example, evaluation was similarly performed for a case where phenylxylylethane was used alone as a solvent. Table 4 shows the results. In the case of the present invention using a low aromatic hydrocarbon solvent, the initial color intensity is high at low temperature (−3 ° C.) as compared with the case of using phenylxylylethane alone, and the color intensity is high even in a short time, and the color temperature at low temperature is low. Are better.

[0034]

[Table 4]

[0035]

The low aromatic hydrocarbon solvent used in the pressure-sensitive copying material of the present invention has a low odor, is excellent in the solubility of a color former, and has excellent performance as a pressure-sensitive copying paper, in particular, is excellent in color forming speed. . That is, the low aromatic hydrocarbon solvent of the present invention has the following characteristics. 1) No toxicity. 2) It is cheap. 3) Fewer unpleasant odors. 4) The solubility of the color former is superior to other solvents. 5) For microencapsulation, form a stable microdispersion. 6) A microcapsule film can be formed on the surface of the dispersion. 7) Good storage stability of the microcapsules. 8) The microcapsule coating can be applied to the oil droplets to a uniform and desired thickness. 9) The color forming reaction between the color forming agent and the color developing agent is not hindered, and the color forming speed is high. 10) When it comes into contact with paper coated with a polymer material as a color developer, the polymer material can also be dissolved and the contact with the color former can be increased. 11) The color image has no bleeding and is clear. 12) A clear color image can be obtained even after long-term storage.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10G 67/06 B41M 5/12 110

Claims (3)

[Claims] 1. A pressure-sensitive copying material characterized by using a low aromatic hydrocarbon solvent obtained in the following steps (1) to (3): Step (1): a boiling point in the range of 150 to 300 ° C. A certain kerosene fraction is heated in the presence of a catalyst at a temperature of 100 to 400 ° C. and a pressure of 1
After desulfurization under the conditions of ２０20 MPa, a gas-containing light component is removed to obtain a low-sulfur kerosene fraction having a sulfur content of 5 ppm or less. Step (2): The above-mentioned step is performed by a molecular sieve made of synthetic zeolite. A step of separating and recovering linear paraffin from the low-sulfur kerosene fraction obtained in (1) to obtain a residual oil; and step (3): converting the residual oil obtained in step (2) to a temperature of 50 in the presence of a catalyst. By performing nuclear hydrogenation under the conditions of -400 ° C and pressure of 1-20 MPa, the total content of monocycloalkane and dicycloalkane is 40% by mass or more, and the content of aromatic hydrocarbon is 1% by mass or less. Obtaining a low aromatic hydrocarbon solvent. 2. A pressure-sensitive copying material using an electron-accepting color developer and a color-forming agent solution obtained by dissolving an electron-donating color-forming agent which forms a color in contact with the color developing agent in a solvent, wherein the solvent is A pressure-sensitive copying material comprising: an aromatic hydrocarbon having two or more non-condensed or condensed aromatic rings; and the low aromatic hydrocarbon solvent according to claim 1. 3. The pressure-sensitive copying material according to claim 2, comprising a microcapsule enclosing the color former solution and a sheet-like support holding the microcapsule.