JPH06183140A - Color developing sheet for pressure-sensitive recording - Google Patents

Abstract

PURPOSE:To enhance developed color density and a color forming speed by adding a metal salt of a salicylic acid derivative represented by a predetermined formula. CONSTITUTION:In a developing sheet for pressure-sensitive recording using an electron donating colorless dye and an electron acceptive compd., a metal salt of a salicylic acid derivative represented by predetermined formula (wherein R1 and R2 are a hydrogen atom, an alkyl group or an aralkyl group and may be the same or different and at least one of R1 and R2 is a 10 or more C straight chain alkyl group), for example, alkali metal 3-n-dodecylsalicylate is added. The metal salt of the salicylic acid derivative may be used together with a metal salt of 3,5-diaralkyl substituted salicylic acid derivative.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive recording material, and more particularly to a pressure-sensitive recording color-developing sheet having good light resistance of a color image and stability of a non-image area.

[0002]

Recording materials using an electron-donating colorless dye and an electron-accepting compound are already well known. For example, British Patent 2140449, US Patent 4480052,
No. 4,436,920, JP-A-62-144,989, and the like. In recent years, as pressure-sensitive recording materials, research has been earnestly conducted to improve characteristics such as (1) color density and color development speed, (2) fastness of a color developing material, (3) improvement of resistance under various use conditions. The present inventors have developed an electron-donating colorless dye,
For each electron-accepting compound and additive, pay attention to their properties such as oil solubility, water solubility, partition coefficient, pKa, substituent polarity, substituent position, crystallinity and solubility change when mixed. However, we have pursued the development of good recording materials and recording materials.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a color-developing color developing sheet having good color density and color developing speed.

[0004]

The object of the present invention has been solved by a pressure-sensitive recording color developing sheet containing a salicylic acid derivative represented by the following general formula (I). General formula (I)

[0005]

[Chemical 2]

In the formula, the groups represented by R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, an alkyl group or an aralkyl group. However, at least one of the groups represented by R ₁ or R ₂ represents a linear alkyl group having 10 or more carbon atoms.

The alkyl group represented by R ₁ or R ₂ is
Those having 1 to 12 carbon atoms are preferable, especially a methyl group,
Ethyl group, butyl group, hexyl group, octyl group, nonyl group and dodecyl group are preferred. The linear alkyl group having 10 or more carbon atoms represented by R ₁ or R ₂ is preferably an n-decyl group, an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group or an n-octadecyl group. The aralkyl represented by R ₁ or R ₂ is preferably an aralkyl having 7 to 12 carbon atoms, and particularly preferably a benzyl group, α-methylbenzyl group, α, α-dimethylbenzyl group.

Among the salicylic acid derivatives represented by the above general formula (I), 3-n-alkyl salicylic acid derivatives, 3-
n-Alkyl-5-alkylsalicylic acid, 3-n-alkyl-5-aralkylsalicylic acid, 3-alkyl-5-
N-alkylsalicylic acid or 5-n-alkylsalicylic acid is preferred.

The metal salt of the salicylic acid derivative according to the present invention includes zinc salt, magnesium salt, aluminum salt, nickel salt, calcium salt and the like. Among these, zinc salt and calcium salt are preferable.

The present invention showing specific examples of salicylic acid derivatives according to the present invention is not limited to these. 3-
n-dodecylsalicylic acid, 3-n-dodecyl-5-methylsalicylic acid, 3-n-dodecyl-5-ethylsalicylic acid, 3-n-dodecyl-5-t-butylsalicylic acid, 3
-N-dodecyl-5-t-octylsalicylic acid, 3-n
-Dodecyl-5-t-dodecyl salicylic acid, 3-n-dodecyl-5-α-methylbenzyl salicylic acid, 3-n-
Dodecylcyclododecyl-5-cumylsalicylic acid, 3-
Methyl-5-n-dodecyldodecylsalicylic acid, 3-ethyl-5-n-dodecylsalicylic acid, 5-α-methylbenzyl-5-n-dodecylsalicylic acid, 3-n-decylsalicylic acid, 3-n-decyl-5- Methyl salicylic acid,
3-n-tetradecyl-5-methylsalicylic acid, 3-n
-Hexadecyl-5-methylsalicylic acid, 3-n-octadecyl-5-methylsalicylic acid and the like.

The salicylic acid derivative metal salt according to the present invention can be obtained by reacting an alkali metal salt of the salicylic acid derivative with a polyvalent metal salt. The metal salt of the salicylic acid derivative is produced in water or a mixed solution of water and an organic solvent. When an organic solvent is used, the used organic solvent is preferably removed under normal pressure or reduced pressure.

When the metal salt of the salicylic acid derivative is produced using an organic solvent, the alkali metal salt of the salicylic acid derivative according to the present invention and the polyvalent metal compound are mixed in a mixture of water and an organic solvent having a boiling point of 200 ° C. or less. Obtained by reacting. The obtained metal salt of salicylic acid derivative is preferably used after adding a water-soluble polymer to emulsify and then removing the organic solvent in the emulsion while heating. It is preferable that the organic solvent used has a boiling point of 200 ° C. or less, a low solubility in water, and a high solubility of the metal salt of the salicylic acid derivative. It is particularly preferable that the solubility of the metal salt of the salicylic acid derivative is 5 or more at 25 ° C. The solubility here represents the weight of a solute dissolved in 100 g of the solvent, and can be measured by a conventional method. Specific examples include aromatic compounds, halides, esters, ketones, and the like, and examples thereof include toluene, xylene, trichlene, chlorobenzene, dichlorobenzene, ethyl acetate, propyl acetate, butyl acetate, ethyl isobutyl ketone, and the like. When removing after the reaction, those which are azeotropic with water are preferable, and those which have an azeotropic point with water of 100 ° C. or less and the amount of solvent in the azeotropic composition is 5% by weight or more are preferable in terms of handling. The reaction temperature for producing the metal salt is 10 to 100 ° C.
Is preferable, and 30 to 90 ° C is particularly preferable.

When a dispersion of a metal salt of a favorite salicylic acid derivative is subsequently produced from the metal salt prepared by this method,
The metal salt of the salicylic acid derivative dissolved in the organic solvent may be once separated and purified before the dispersion treatment, or may be continuously subjected to the dispersion treatment as it is. As the water-soluble polymer used in the emulsification, polyvinyl alcohol, maleic anhydride-isobutylene copolymer, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylamide, polyacrylic acid, acrylamide-alkyl acrylate copolymer, ether-modified polyvinyl alcohol ,
Synthetic or natural polymers such as cyanoethyl-modified polyvinyl alcohol, polyvinylpyrrolidone, starch, casein, gum arabic, and gelatin can be used. Further, a water-soluble polymer and a surfactant may be used in combination, and the surfactant is preferably an anionic surfactant. The emulsification method is preferably a method of emulsifying at high speed, a method of emulsifying at high pressure, or a method of emulsifying with ultrasonic waves, and these methods may be combined. In order to remove the organic solvent from the emulsion thus obtained, the solvent is distilled off under heating at normal pressure or reduced pressure. The heating temperature depends on the boiling point of the solvent used, but it is preferable to distill off at 100 ° C or lower.

The concentration of the electron-accepting compound in the dispersion is 10
% Or more, and when distilling off the organic solvent, it can be adjusted by distilling water or adding water if necessary. The dispersion liquid can be further treated with a disperser using a medium to improve the stability and homogeneity of the dispersion liquid. As the disperser, it is preferable to use a disperser such as a sand mill or a dyno mill that disperses using high-speed rotation and that can perform continuous processing.

The pressure-sensitive recording color-developing sheet according to the present invention further comprises a well-known phenol sheet other than the present invention.
Derivative, metal salt of aromatic carboxylic acid, acid clay, bentonite, novolak resin, metal-treated novolak resin,
You may use together, such as a metal complex. Examples of these are JP-B-40-9309, JP-B-45-14039, JP-A-52-140483 and JP-A-48-51510.
JP-A-57-210886, JP-A-58-870
89, JP-A-59-112286, JP-A-60-17.
No. 6795, JP-A No. 61-95988, and the like. Among these, the combined use with the metal salt of the 3,5-di-substituted salicylic acid derivative, particularly the combined use with the metal salt of the 3,5-diaralkyl-substituted salicylic acid derivative are preferable. Examples of 3,5-diaralkyl-substituted salicylic acid derivatives include 3,5
-Dibenzyl salicylic acid, 3,5-di-α-methylbenzyl salicylic acid, 3,5-di-α, α-dimethylbenzyl salicylic acid, 3,5-bis (α-methyl-α-tolylmethyl) salicylic acid and the like. .

Pressure-sensitive recording materials using the color developing sheet according to the present invention are disclosed in US Pat. Nos. 2,505,470 and 2,505.
505,471, 2,505,489, 2,5
48,366, 2,712,507, 2,73
0,456, 2,730,457, 3,10
3,404, 3,418,250, 4,01
It can take various forms as described in prior patents such as 0,038. Most commonly it consists of at least a pair of sheets containing separately an electron-donating colorless dye and an electron-accepting compound. A more preferred embodiment is a sheet comprising microcapsules containing an electron-donating colorless dye and a sheet coated with the electron-accepting compound according to the present invention.

Examples of the electron-donating colorless dyes include triphenylmethanephthalide compounds, fluorane compounds, phenothiazine compounds, indolylphthalide compounds, leuco-olamine compounds, rhodamin-lactam compounds, triphenylmethane compounds. , Triazene compounds, spiropyran compounds, fluorene compounds, and the like. Specific examples of the phthalides include US Reissue Patent Specification No. 23,024 and US Patent Specification No. 3,491,111.
Issue No. 3,491,112 Issue 3,491,11
No. 6, and No. 3,509,174, and specific examples of fluoranes are U.S. Pat. Nos. 3,624,107, 3,627,787, 3,641,011, and No. 3,462,828, No. 3,681,390,
No. 3,920,510, No. 3,959,571
No. 3, specific examples of spiro dipyrans are described in US Pat.
971,808, pyridine compounds and pyrazine compounds are described in US Pat.
No. 853,869, No. 4,246,318, and specific examples of fluorene compounds are described in Japanese Patent Application No. 61-240989.

In the color-developing sheet for pressure-sensitive recording according to the present invention, the electron-accepting compound is 50 to 5 of an electron-donating colorless dye.
It is preferable to use 000% by weight, and more preferably 100 to 2000% by weight.

Regarding the method for producing capsules, a method utilizing coacervation of a hydrophilic colloid sol described in US Pat. Nos. 2,800,457 and 2,800,458, and British Patent 867,797, 950,44
No. 3, 989,264, 1,091,076 and the like, or the interfacial polymerization method or US Pat.
There is a method described in No. 3,404. Generally, an electron-donating colorless dye is used alone or as a mixture, and a solvent (alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated ta-phenyl, chlorinated paraffin, etc., synthetic oil: cotton oil, castor oil, etc. Vegetable oil: animal oil: mineral oil or mixtures thereof)
By containing this in a microcapsule and applying it to paper, woodfree paper, plastic sheet, resin coated paper, etc., a color former sheet can be obtained.

On the other hand, the electron-accepting compound is mixed with an additive, if necessary, and dispersed in a binder such as styrene-butadiene latex or polyvinyl alcohol, and together with the pigment, paper, plastic sheet, resin coat. Forming a developer sheet by applying it to a support such as toted paper.

Examples of additives to be added to the electron-accepting compound as required include antioxidants, external beam absorbers, amide derivatives, urea derivatives, urethane derivatives and the like.

Examples of the water-soluble polymer include polyvinyl alcohol, maleic anhydride-isobutylene copolymer, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylamide, polyacrylic acid, acrylamide-alkyl acrylate copolymer, ether-modified polyvinyl alcohol, cyanoethyl. Synthetic or natural polymers such as modified polyvinyl alcohol, polyvinylpyrrolidone, starch, casein, gum arabic and gelatin can be used. As the pigment, zinc oxide, aluminum hydroxide, calcium carbonate, titanium oxide, magnesium carbonate, magnesium oxide, barium sulfate, kaolin,
Examples include activated clay and talc. Among them, it is particularly preferable to use calcium carbonate having an average particle size of 5.0 μ or less in an amount of 60% by weight or more based on all pigments. If the amount of calcium carbonate used is less than 60% by weight, sufficient performance cannot be obtained with respect to the light resistance of the color developing material and the yellowing of the color developing surface due to light. Further, unless calcium carbonate having an average particle size of 5.0 μ or less is used, sufficient color developing ability cannot be obtained. Average particle size 5.
Calcium carbonate of 0 μ or less is commercially available, for example,
Brilliant-15 and Brillia of Shiraishi Industry
nt-S15, Brilliant-30, PC, PC
X, Unibur-70 and the like. The electron accepting compound and the pigment are preferably used in a weight ratio of 1: 5 to 1:15. If the usage ratio of the pigment is higher or lower than this, sufficient color developing ability cannot be obtained. A part of the electron-accepting compound may be used together with a dispersant, a water-soluble polymer, and other additives in a dispersion liquid which is mechanically dispersed in an aqueous system by a ball mill, an attritor, a sand mill or the like.

The amount of the electron-accepting compound coated on the support is 0.1 g / m ^{2 to} 2.0 g / m ² , preferably 0.
2g / m ² ~1.0g / m ² are suitable. The amount of the electron-donating colorless dye used is desired coating thickness, pressure-sensitive recording paper form,
Since it depends on the capsule manufacturing method and other conditions, it may be appropriately selected according to the conditions. A person skilled in the art can easily determine this usage amount.

[0024]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. In the examples, unless otherwise specified, weight% is indicated.

Example-1 1) Preparation of an electron-donating colorless dye-containing capsule sheet 5 parts of a partial sodium salt of polyvinylbenzenesulfonic acid (VERSA, TL500 manufactured by National Starch Co., Ltd.) was dissolved in 95 parts of hot water. After cooling. An aqueous sodium hydroxide solution was added to this to adjust the pH to 4.0. On the other hand, 100 parts of diisopropylnaphthalene in which 4.5% of 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) phthalide, an electron-donating colorless dye, was dissolved It was emulsified and dispersed in 100 parts of a 5% aqueous solution of a partial sodium salt of polyvinylbenzenesulfonic acid to obtain an emulsion having a particle size of 4.0 μ in diameter. Separately 6 parts of melamine. 11 parts of 37% by weight formaldehyde aqueous solution. 30 parts of water was heated and stirred at 60 ° C., and after 30 minutes, a transparent aqueous solution of melamine formaldehyde prepolymer was obtained. This aqueous solution was mixed with the above emulsion. The pH was adjusted to 6.0 with a 2M phosphoric acid solution with stirring, the liquid temperature was raised to 65 ° C, and stirring was continued for 6 hours. The capsule solution was cooled to room temperature and adjusted to pH 9.0 with an aqueous sodium hydroxide solution. To this dispersion, 200 parts of a 10% by weight aqueous solution of polyvinyl alcohol and 50 parts of starch particles were added, and the mixture was hydrolyzed to have a solid content of 2
A 0% solution was prepared. This coating liquid was applied to an air knife coater so that a solid content of 5 g / m ² was applied to a base paper of 50 g / m ^2.
The coated sheet was dried with a coater and dried to obtain an electron-donating colorless dye-containing capsule sheet.

2) Preparation of electron-accepting compound sheet 100 parts of 3-n-dodecylsalicylic acid zinc salt was dissolved in 100 parts of xylene, and this solution was added with 0.5% sodium dodecyl sulfate to 4% polyvinyl alcohol (manufactured by Kuraray). PVA
-205) This was added to 500 parts of an aqueous solution and emulsified with a homogenizer (Nippon Seiki, AM-7 type) at 12000 rpm for 5 minutes to obtain an electron-accepting compound emulsion having an average particle size of 1.0 µ. This electron-accepting compound emulsion was heated to distill off xylene azeotropically to prepare an electron-accepting compound dispersion having a solid content concentration of 30%. Next, calcium carbonate (Shiraishi Kogyo Brilliant-15, average particle size 0.5 μ) 16
Using 0 part, 30 parts of activated clay, 5 parts of 40% sodium hexametaphosphate aqueous solution and 230 parts of water, a sand grinder was used to uniformly disperse the particles to an average particle size of 3 μm to obtain a pigment dispersion liquid. To 300 parts of this pigment dispersion is added 10% PVA.
-117 (manufactured by Kuraray Co., Ltd.) and 200 parts of an aqueous solution of the electron-accepting compound were added, and the solid content concentration was 20%.
To prepare a coating solution. Add this coating solution to 5
An electron-accepting compound sheet was obtained by bar coating so that a solid content of 5.0 g / m ² was coated on a base paper of 0 g / m ² and drying.

Example-2 In the same manner as in Example-1 except that 3-n-dodecyl-5-methylsalicylic acid zinc salt was used in place of 3-n-dodecylsalicylic acid zinc salt used in Example-1. An electron-accepting compound sheet was obtained. Example-3 An electron accepting property was performed in the same manner as in Example-1 except that 3-methyl-5-n-dodecylsalicylic acid zinc salt was used in place of the 3-n-dodecylsalicylic acid zinc salt used in Example-1. A compound sheet was obtained.

Example 4 Instead of the zinc salt of 3-n-dodecylsalicylic acid used in Example-1, 60 g of zinc salt of 3-n-dodecylsalicylic acid and 40 g of zinc 3,5-di-α-methylbenzylsalicylate.
An electron-accepting compound sheet was obtained in the same manner as in Example 1 except that was used.

Comparative Example-1 Example 1 was repeated except that zinc 3-n-dodecylsalicylic acid zinc salt used in Example 1 was replaced with zinc 3,5-bis (α-methylbenzyl) salicylic acid zinc salt. Similarly, an electron-accepting compound sheet was obtained.

An evaluation test as a pressure-sensitive recording sheet was conducted by combining each of the above-mentioned electron-accepting compound sheets and an electron-donating colorless dye-containing capsule sheet, and the results are shown in Table 1. The evaluation test was performed by the following method. The surface of the microcapsule sheet containing the electron-donating colorless dye was placed on the sheet of the electron-accepting compound, and a load of 300 kg / cm ² was applied to develop the color. After leaving this in the dark for 24 hours,
Densitometer of the color density of the color image (Macbeth
RD-514 type) and measured as Do. Next, another electron-accepting compound sheet is attached to a weather ometer (ATLAS).
(Ci65 type) for 16 hours, and then 300 kg overlapped with the microcapsule sheet surface containing the electron-donating colorless dye.
Color was applied by applying a load of / cm ² . The color density of the color developing material was measured and designated as D ₁ . D ₁ / D ₀ × 100 (%) was calculated as the color developing ability D after exposure of the color developing sheet. The larger the value of the color developing ability D after the development of the color developing sheet is, the better the color developing ability is.
On the other hand, the reflection density (Yellow) of the color-developing surface after processing for 16 hours with a weather odometer was measured with a densitometer (Model RD-514, Macbeth Co.). The larger the reflection density (Yellow) of the electron-accepting compound sheet, the greater the yellowing due to light. Next, the color density of the color developing body after the sample having the color density of Do was immersed in water for 24 hours was measured and defined as D ₁ . D ₁ / D ₀ × 100 (%) was determined as the residual rate of the water-resistant color-developing body of the color-developing body. The greater the residual value of the water-resistant color-developing body, the better the water resistance of the color-developing body.

[0031]

[Table 1]

[0032]

As shown in Table 1, the pressure-sensitive recording material using the color developing sheet according to the present invention is
It can be seen that the color-developing body has excellent water resistance and that the developed surface has little light yellowing.

Claims (2)

[Claims] 1. A pressure-sensitive recording color developing sheet comprising a metal salt of a salicylic acid derivative represented by the following general formula (I). General formula (I) In the formula, the groups represented by R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, an alkyl group or an aralkyl group. However, at least one of the groups represented by R ₁ or R ₂ represents a linear alkyl group having 10 or more carbon atoms. 2. A color developer for pressure-sensitive recording according to claim 1, which contains a metal salt of a salicylic acid derivative represented by the general formula (I) and a metal salt of a 3,5-diaralalkyl-substituted salicylic acid derivative. Sheet.