JPH058532A - Pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To obtain pressure sensitive recording sheet capable of reading with an optical character reader using near infrared rays without decomposition regardless of exposure to light by including specific divinylphthalide compound and ultraviolet absorbent in micro capsule. CONSTITUTION:In micro capsule of a pressure sensitive recording sheet which obtains a coloring image generated by reaction of nearly colorless electron donative dye and electron acceptive developer, divinylphthalide compound in formula I and ultraviolet absorbent are included. In the formula, the R1 and R2 represent alkyl group having 8 or less carbon atoms, 5-7C cyclo alkyl group, or benzyl group or phenyl group which may have halogen atom or alkyl group having 4 or less carbon atoms as substituent. The X expresses hydrogen atom, halogen atom, alkyl group or alkoxy group having 8 or less carbon atoms, or -NR3R4, the Y1-Y3 express hydrogen, halogen, alkyl group or alkoxy group having 8 or less carbon atoms, and the Z expresses hydrogen, chlorine, and bromine atoms.

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 sheet. In particular, the present invention relates to a pressure sensitive recording sheet suitable for reading optical characters.

[0002]

2. Description of the Related Art Recently, with the development of optical character reading devices (OCR) and bar code reading devices using near infrared rays, optical character reading has come to be applied to pressure-sensitive recording sheets. So far, in the case of a pressure-sensitive recording sheet, optical character reading has been performed only on the characters written on the upper leaf paper, and not on the characters formed by destroying the microcapsules.

Recently, as a color-forming agent capable of forming a dye having absorption in the near infrared region, Japanese Patent Publication No. 58-5940, JP-A-6-5940.
Various dyes have been proposed in JP-A No. 0-230890 and JP-A No. 59-199757, and by using these dyes, characters on all papers (up to 5 to 6) of a pressure-sensitive recording sheet can be read by an optical character reading device. However, these dyes are not suitable for practical use because they have the problems of being colored yellow, fog on the background, and poor color development. Further, a divinyl compound has recently been proposed in JP-A-62-243653 as a color-forming agent having absorption in the near infrared region without such a problem.

[0004]

By using the above-mentioned divinyl compound in microcapsules, it is possible to obtain a pressure-sensitive recording sheet in which characters on all papers can be read by an optical character reader using near infrared rays. However, the light resistance of the dye is poor, and when the microcapsule paper is exposed to light while it is in the microcapsules, the dye decomposes, the coloring is poor, and the optical read performance of the recorded characters is poor, making it difficult to read. Disappear.

Therefore, an object of the present invention is to use a divinyl compound (divinylphthalide compound) for reading characters of all papers with an optical character reader using near infrared rays without decomposing even when the microcapsule paper is exposed to light. It is to provide a possible pressure-sensitive recording sheet.

[0006]

As a result of various studies, the present inventor has found that the above object can be achieved by the present invention described below.

That is, the present invention relates to a pressure-sensitive recording sheet which obtains a color image by the reaction of an almost colorless electron-donating dye and an electron-accepting developer, and is represented by (a) the general formula (1) in a microcapsule. A pressure-sensitive recording sheet comprising a divinylphthalide compound (b) and an ultraviolet absorber (b).

General formula (1)

[0009]

[Chemical 2]

In the formula, R ₁ and R ₂ each have an alkyl group having 8 or less carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a halogen atom or an alkyl group having 4 or less carbon atoms as a substituent. It represents a benzyl group or a phenyl group, and R ₁ and R ₂ may combine with each other to form a ring with N.

X is a hydrogen atom, a halogen atom, an alkyl group having 8 or less carbon atoms, an alkoxy group having 8 or less carbon atoms, or --NR ₃ R ₄ (R ₃ and R ₄ have the same meanings as R ₁ and R ₂ above). ); Y ₁ , Y ₂ and Y ₃ are each a hydrogen atom, a halogen atom, an alkyl group having 8 or less carbon atoms or 8 carbon atoms.
The following alkoxy groups are represented and Z represents a hydrogen atom, a chlorine atom, or a bromine atom.

Further, in the present invention, a fluoran compound having an anilino group at the 2-position and a substituted amino group at the 6-position can be used together in the microcapsule as a black-coloring compound.

The present invention will be described in detail below. In the divinylphthalide compound represented by the above general formula, R ₁
And the ring formed by R ₂ (or R ₃ and R ₄ ) together with N is the following ring.

[0014]

[Chemical 3]

The divinylphthalide compound represented by the general formula (1) used in the present invention is described in JP-A-62-24365.
It contains some of the compounds disclosed in Japanese Patent Publication No. Specific examples of preferable compounds of the divinylphthalide compound represented by the general formula (1) are shown below, but the present invention is not limited thereto.

[0016]

[Chemical 4]

[0017]

[Chemical 5]

[0018]

[Chemical 6]

[0019]

[Chemical 7]

[0020]

[Chemical 8]

[0021]

[Chemical 9]

[0022]

[Chemical 10]

[0023]

[Chemical 11]

[0024]

[Chemical formula 12]

Preferred as the ultraviolet absorber used in the present invention is one having a spectral absorption at 270 to 380 mμ, such as phenyl salicylate and p-tert-.
Butylphenyl salicylate, p-octylphenyl salicylate and other salicylic acid type UV absorbers, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyl Oxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4 '
-Benzophenone-based UV absorbers such as dimethoxybenzophenone and 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2 (2'-hydroxy-5'-
Methylphenyl) benzotriazole, 2 (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-t
ert-butyl-phenyl) bendtriazole, 2
(2'-hydroxy-3'-tert-butyl-5'-
Methylphenyl) -5-chlorobenzotriazole, 2
(2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2
Benzotriazole-based UV absorbers such as (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2 (2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- There are cyanoacrylate-based UV absorbers such as ethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate. Among these, preferred is a benzotriazole type ultraviolet absorber.

Further, the compound represented by the following formula can also be preferably used as an ultraviolet absorber in the present invention.

[0027]

[Chemical 13]

The ultraviolet absorber is preferably used in an amount of 5 to 200% by weight, more preferably 10 to 100% by weight, based on the above divinylphthalide compound. In the present invention,
When the pressure-sensitive recording sheet is read by an optical character reader and the obtained record is to be read visually, it is preferable to use a fluoran compound in combination as a black color-developing agent.

Among the fluoran compounds used in the present invention, those represented by the following general formula are preferred.

[0030]

[Chemical 14]

(Wherein R ₁ , R ₂ and R ₃ have 1 to 10 carbon atoms)
The alkyl group, R ₄ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X represents an alkyl group or a chlorine atom number of 1 to 8 carbons. In the above general formula, the alkyl groups represented by R ₁ and R ₂ may form a ring and may further have a substituent. In the above general formula, a compound in which X is a methyl group or a chlorine atom is particularly preferable.
Examples of these colorless or light-colored electron-donating dye precursors include, but are not limited to, the following compounds.

2-anilino-3-methyl-6-dimethylaminofluorane, 2-anilino-3-methyl-6-N
-Methyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N- (iso-propyl) aminofluorane, 2-anilino-3-methyl-6
-N-methyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6
-Diethylaminofluorane, 2-anilino-3-chloro-6-dimethylaminofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-
N-isoamylaminofluorane, 2-anilino-3-
Chloro-6-diethylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-ethylaminofluorane, 2-anilino-3-chloro-6-N-methyl-
N- (iso-propyl) aminofluorane, 2-anilino-3-chloro-6-N-methyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-cyclohexylamino Fluoran, 2-anilino-3-methyl-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2- (p- Methylanilino) -3-methyl-6-dimethylaminofluorane, 2- (p-methylanilino) -3-methyl-6-
Diethylaminofluorane, 2- (p-methylanilino) -3-methyl-6-N-methyl-N-ethylaminofluorane, 2- (p-methylanilino) -3-methyl-6-N-methyl-N- ( iso-propyl) aminofluorane, 2- (p-methylanilino) -3-methyl-
6-N-methyl-N-pentylaminofluorane, 2-
(P-Methylanilino) -3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2- (p-methylanilino) -3-methyl-6-N-ethyl-N-pentylaminofluorane, 2- (P-methylanilino)
-3-Chloro-6-dimethylaminofluorane, 2-
(P-methylanilino) -3-chloro-6-diethylaminofluorane, 2- (p-methylanilino) -3-chloro-6-N-methyl-N-ethylaminofluorane,
2- (p-methylanilino) -3-chloro-6-N-methyl-N- (iso-propyl) aminofluorane, 2
-(P-methylanilino) -3-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2- (p-
Methylanilino) -3-chloro-6-N-methyl-N-
Pentylaminofluorane, 2- (p-methylanilino) -3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-furylmethylaminofuran Oran, 2-anilino-3-ethyl-6-N-methyl-N-furylmethylaminofluorane and the like.

The color former used in the present invention is dissolved in a solvent together with an ultraviolet absorber to be encapsulated and applied to a support. As the solvent, natural or synthetic oils can be used alone or in combination. Examples of the solvent include cottonseed oil, kerosene, paraffin, naphthene oil, alkylated biphenyl, alkylated tafel, chlorinated paraffin, alkylated naphthalene, diphenylalkane and the like.

As the method for producing the color-forming agent-containing microcapsules, an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, a coacervation method and the like are used. A water-soluble binder or a latex-based binder is generally used for preparing a coating liquid containing a color-forming agent-containing microcapsule. Further capsule protectant, for example, cellulose powder,
Denbun particles and talc are added to obtain a color developer-containing microcapsule coating solution.

Examples of the developer that reacts with the color former used in the recording sheet of the present invention include acidic clay, activated clay, attavalgite, zeolite, bentonite, clay substances such as kaolin, metal salts of aromatic carboxylic acid, and Examples include phenolic resins.

These color developers are coated on a support such as paper together with a binder such as styrene butadiene latex. The performance of the recording sheet of the present invention was tested using the developer sheet shown below. (Preparation of developer sheet) To 70 parts of water, 2 parts of zinc oxide, 18 parts of calcium carbonate and 4 parts of zinc 3,5-di-α-methylbenzylsalicylate were added and mixed, and then dispersed by an attritor for 30 minutes. 2.5 parts of carboxy-modified SBR latex in solid content and 12 parts of 10 wt% PVA (saponification degree 99% polymerization degree 1000) aqueous solution were added to the solution, and the mixture was uniformly stirred to obtain a coating solution. This coating solution was coated and dried by an air knife coating machine such that a solid content of 4 g / m ² was coated on a base paper of 50 g / m ² to obtain a color developer sheet.

[0037]

EXAMPLE An evaluation test as a pressure-sensitive recording sheet was conducted by combining the above-mentioned color developer sheet and color-forming agent-containing microcapsule sheet, and the results are shown in Table 1. The evaluation test was performed by the following method. (1) PCS (Print Contrast Sig)
Measurement of nal) value The microcapsule layer of the color-forming agent-containing microcapsule sheet was superposed on the color-developing agent sheet, and a load pressure of 300 kg / cm ² was applied to develop the color. After leaving this for 24 hours in a dark place, the reflectance of the developing surface of 380 nm to 1000 nm was measured with a spectrophotometer (Shimadzu UV-3100). The PCS value is calculated by the following formula.

PCS value = (Reflectance of white background−Reflectance of color former) ÷ (Reflectance of white background) (2) Light resistance test of microcapsule layer The microcapsule layer of the microcapsule sheet containing a color former is subjected to a fluorescent lamp fading test. Machine (33,000 lux) for 8 hours, then stack it on the developer sheet 300 kg / cm ²
Was applied to develop the color. After that, the PCS value was measured in the same manner as in (1). In addition, the degree of coloring of the microcapsule sheet was measured by a densitometer (Macbeth RD9
18 type). (3) OCR reading test The microcapsule layers of the fluorescent lamp-unirradiated and fluorescent lamp-irradiated color-forming agent-containing microcapsule sheets were overlaid on the developer sheet, and letters and numbers were printed in OCR-B font. This printed sample is an OCR reader (Toshiba V-301
0, using a blue fluorescent lamp). Example 1-1 4.4 of partial sodium salt of polyvinylbenzenesulfonic acid (average molecular weight 500,000) adjusted to pH 4
% Aqueous solution 100 parts (weight, the same applies hereinafter) as a color former, 3,3-bis [2- (p-dimethylaminophenyl)-
2- (p-methoxyphenyl) ethenyl] -4,5,
6,7-Tetrachlorophthalide 6 parts, 2-anilino-3
-Methyl-6-N-ethyl-N-isopentylaminofluorane 6 parts, 2-dibenzylamino-6-diethylaminofluorane 2 parts, benzoyl leuco methylene blue 1 part, 2 (2'-hydroxy- 5 '
4 parts of -methylphenyl) benzotriazole were dissolved in 100 parts of diisopropylnaphthalene. The color former oil was emulsified and dispersed to obtain an emulsion having a particle size of 4.5 μm in average particle size. Separately, 6 parts of melamine, 11 parts of 37% by weight aqueous formaldehyde solution, and 30 parts of water are heated and stirred at 60 ° C. for 30 minutes.
After a minute, a transparent mixed aqueous solution of melamine and formaldehyde and a melamine-formaldehyde initial condensation product was obtained. The pH of this mixed aqueous solution was 6.0 to 8.0. Hereinafter, this mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate is referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to and mixed with the above emulsified mixture, the pH was adjusted to 6.0 with a 3.6% by weight hydrochloric acid solution while stirring, and the liquid volume was raised to 65 ° C. for 360 minutes. Continued to stir. The capsule solution was cooled to room temperature and adjusted to pH 9.0 with 20% by weight sodium hydroxide.

To this capsule dispersion, 100 parts of a 10 wt% polyvinyl alcohol aqueous solution and 10 parts of carboxy-modified SBR latex in solid content, 50 parts of starch particles and 10 parts of calcium carbonate were added, and water was added to obtain a solid content concentration of 20. % To adjust the color developer-containing microcapsule coating solution.

This coating solution was added to a base paper of 50 g / m ² at 5 g /
A microcapsule sheet for pressure-sensitive copying was obtained by coating with an air knife coater so that the solid content of m ² was coated and drying. Example 1-2 2 (2'-hydroxy-3'-te as an ultraviolet absorber
A microcapsule sheet was obtained in the same manner as in Example 1-1, except that 4 parts of rt-butyl-5'-methylphenyl) -5-chlorobenzotriazole was used. Example 1-3 2 (2'-hydroxy-3 ', 5' as an ultraviolet absorber
A microcapsule sheet was obtained in the same manner as in Example 1-1, except that 4 parts of -di-tert-butylphenyl) -5-chlorobenzotriazole was used. Example 1-4 A microcapsule sheet was obtained in the same manner as in Example 1-1, except that 4 parts of 2-hydroxy-4-octoxybenzophenone was used as the ultraviolet absorber. Comparative Example 1 A microcapsule sheet was obtained in the same manner as in Example 1-1, except that the ultraviolet absorber was not used. Example 2-1 3,3-bis [2- (p-dimethylaminophenyl) -2- (p-methylphenyl) ethenyl] -as a color former
4,5,6,7-tetrachlorophthalide 6 parts, 2-anilino-3-methyl-6-diethylaminofluorane 5
Part and 2-anilino-6-N-ethyl-N-hexylaminofluorane 3 parts, and used as an ultraviolet absorber.
Same as Example 1-1 except that 4 parts of (2'-hydroxy-5'-methylphenyl) benzotriazole and 100 parts of 1-phenyl-1-xylylethane were used as a solvent for dissolving the color former and the ultraviolet absorber. To obtain a microcapsule sheet. Example 2-2 2 (2'-hydroxy-3 ', 5' as an ultraviolet absorber
2 (2 ′) in the same manner as in Example 2-1 except that 4 parts of -di-tert-amylphenyl) benzotriazole was used.
Example 2 except that 4 parts of -hydroxy-3 ', 5'-di-tert-amylphenyl] benzotriazole were used.
A microcapsule sheet was obtained in the same manner as in -1. Example 2-3 2 (2'-hydroxy-3'-te as an ultraviolet absorber
A microcapsule sheet was obtained in the same manner as in Example 2-1 except that 4 parts of rt-butyl-5'-methylphenyl) -5-chlorobenzotriazole was used. Comparative Example 2 A microcapsule sheet was obtained in the same manner as in Example 2-1 except that the ultraviolet absorber was not used.

[0041]

[Table 1]

As is clear from the results shown in Table 1, when the microcapsule sheet of the present invention was used, the PCS value after fluorescent lamp irradiation was higher, the coloration of the capsule was less, and the recorded character was smaller than that of the comparative example. OCR reading was possible. Example 3 In Example 1-1, 3,3-bis [2-
(P-Dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide exemplified compounds 11,12,17,2
Microcapsule sheets were obtained in the same manner using 5, 27 and 30, respectively, and the same test as above was conducted.
The same effect as in Example 1-1 was obtained.

[0043]

According to the present invention, by incorporating an ultraviolet absorber together with a divinylphthalide compound in the microcapsules, OCR readable recording can be performed even when the microcapsule sheet is exposed to ultraviolet rays.

Claims (1)

Claim: What is claimed is: 1. A pressure-sensitive recording sheet for obtaining a color-developed image by reacting a substantially colorless electron-donating dye and an electron-accepting developer, wherein (a) the general formula (1) is contained in a microcapsule. ) A pressure-sensitive recording sheet containing a divinylphthalide compound represented by the formula (4) and an ultraviolet absorber (b). General formula (1) In the formula, R ₁ and R ₂ each may have an alkyl group having 8 or less carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a halogen atom or a alkyl group having 4 or less carbon atoms as a substituent, benzyl. Represents a group or a phenyl group, R ₁
And R ₂ may combine with each other to form a ring with N. X is a hydrogen atom, a halogen atom, an alkyl group having 8 or less carbon atoms, an alkoxy group having 8 or less carbon atoms, or -NR ₃ R ₄
(R ₃ and R ₄ have the same meanings as R ₁ and R ₂ above); Y ₁ , Y ₂ and Y ₃ are each a hydrogen atom, a halogen atom, an alkyl group having 8 or less carbon atoms, or an alkoxy group having 8 or less carbon atoms. And Z represents a hydrogen atom, a chlorine atom, or a bromine atom.