JPH0761121A - Pressure-sensitive copy sheet for optical reading. - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a pressure-sensitive copying sheet for optical reading, which exhibits excellent optical reading performance. A pressure-sensitive copying sheet utilizing a color-forming reaction between an electron-donating color developing agent and an electron-accepting color developing agent, wherein the color-developed image has absorption in the wavelength region of 600 to 1000 nm and contains solid wax-encapsulated microcapsules. A pressure-sensitive copying sheet for optical reading, wherein a layer is provided on a support, and an electron-donating color former-containing microcapsule-containing layer is provided thereon.
Preferably, the melting point of the solid wax is 30 ° C. or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive copying sheet utilizing the color-forming reaction between an electron-donating color former and an electron-accepting color developer, and is particularly excellent for optical reading of OCR, bar codes and the like. The present invention relates to a pressure-sensitive copy sheet for optical reading.

[0002]

2. Description of the Related Art Pressure-sensitive copying sheets are also referred to as carbonless sheets, and are, for example, US Pat. Nos. 2,505,470, 2,505,489, 2,548,366, 2,550,471, 2712507 and 2,730,456. As described in Japanese Patent Publication Nos. 2730457, 3418250, 3418250, and 3672935, the electron-donating color developing agent (hereinafter, referred to as a color developing agent) is basically high. An upper sheet (referred to as CB) in which a coating layer which is dissolved in a solvent having a boiling point and which is encapsulated in microcapsules and coated with the microcapsules is coated on the back surface of a support, and an electron-accepting microscope that develops a color by reacting with the color former. A bottom sheet (referred to as CF) in which a coating layer containing a colorant (hereinafter, referred to as a developer) is applied to the surface of a support is superposed on each other. When you print in a switching pressure,
The color-developing agent flows out from the color-forming agent-containing microcapsules of the upper sheet and is transferred to the lower sheet, the developer layer is colored, and a copy image is obtained at the same time as printing.

Many methods for producing microcapsules containing a color former are known. Typical methods include the following various methods. A coacervation method using a polyion complex of gelatin-arabic gum (US Pat. No. 2800)
No. 457, No. 2800458, etc.). An interfacial polymerization method in which an insoluble film is formed at the interface between a hydrophilic liquid serving as a dispersion medium and a hydrophobic liquid to be included. Ins is carried out by adding a film resin initial condensate such as a melamine-formalin resin or a urea-formalin resin from the side of a hydrophilic liquid serving as a dispersion medium, and then encapsulating the resin.
in situ polymerization method (Japanese Patent Publication No. 36-9168, No. 47-).
23165, JP-A-48-57892, JP-A-51-9079, JP-A-54-25277, etc.)
etc. Among these, synthetic resin capsules are often used because of the cheap and stable supply of raw materials, the production of high-concentration microcapsule emulsions, and the simple manufacturing process.

In US Pat. No. 4,001,480, a method of encapsulating a lipid-soluble substance in a fungus having a lipid content of 40 to 60 wt% is introduced. Further, in JP-A-58-107189, as a method for increasing the lipid content of a growth microorganism, a growth microorganism having a lipid content of 10 wt% or more (for example, an oil-and-fat-forming yeast, a brewer's yeast, etc.) recovered from a medium is added to the lipid. A core substance soluble in these lipid-increasing organic substances after containing a liquid selected from use organic substances (eg, aliphatic alcohols, esters, aromatic hydrocarbons, hydrogenated aromatic hydrocarbons) Microbial microcapsules obtained by encapsulating a liquid to be used are listed. In addition, application of microbial microcapsules (in particular having yeast as a wall membrane) to a carbon-free pressure-sensitive copying sheet has been proposed (Japanese Patent Laid-Open Nos. 62-294079, 62-186937 and 63-63). -88033 publication).

When a large number of copies are desired, a medium-use sheet in which the developer-containing layer is coated on the surface of the support and the color-forming agent-containing microcapsule-containing layer is coated on the back surface is
Insert the required number of sheets between the upper and lower sheets. A self-coloring sheet (self) formed on the same surface of a support by laminating or mixing a color-capsule-containing microcapsule-containing layer and a color-developing agent-containing layer is also well known as one form of a pressure-sensitive copying sheet. There is. Further, as a technique for effectively using a color former in a general pressure-sensitive copying sheet, there is a proposal to provide a solid wax-encapsulating capsule-containing layer on a support and to provide a color-forming agent-encapsulating microcapsule-containing layer thereon. (JP-A-3-236990). And the demand for pressure-sensitive copy sheets has increased with the expansion of their applications.
Sales have grown significantly in a wide variety of fields, including general vouchers, shipping vouchers, unified vouchers, contract documents, computer paper, and so on.

On the other hand, with the development of the information processing industry, office automation is progressing, and the rationalization of office work is promoted. And as a method of rationalization, OCR
And OMR devices and barcode management have become popular,
In general companies, the main order slips, sales slips, shipping slips, purchase slips, input / output slips, etc. are OCR devices,
It has become necessary to provide a slip suitable for OMR devices, bar code printing and reading.

[0007]

A light source of an optical reading device such as an OCR or bar code uses a light emitting diode or a semiconductor laser, and the light source wavelength is generally in the near infrared region of 600 nm or more. is there. However,
The color-developed image of a normal pressure-sensitive copying sheet does not have sufficient absorption in the region of 600 nm or more, and is often unsuitable for optical reading. Therefore, the light absorption wavelength of the color image is 600
There is a strong demand for the development of a color former having a wavelength of at least nm, and many proposals have already been made. For example, the color-developing agents described in JP-A-60-8364 and JP-A-63-257680 have been developed, and by using them, a pressure-sensitive material having a better reading rate in the near infrared region than before. Copy sheets are becoming available. However, it is still difficult to say that the reading performance is sufficient, and in many cases unreadable or erroneous reading is performed, and it is an object of the present invention to improve this. still,
The above-mentioned color developer for optical reading has many reaction steps in the manufacturing stage and is complicated, so that it is an expensive material compared to the color developer used in general pressure-sensitive copying sheets. Further, in order to improve the reading performance, it is necessary to have a sufficient color forming density, and therefore it is necessary to apply a large amount of color forming agent on the support. Therefore, using a color former more effectively than before,
There has been a need for a technique for obtaining a sufficient optical reading performance with a small coating amount of the color developing agent.

[0008]

The present inventor has conducted extensive studies to solve the above problems, and as a result, it has been possible to obtain a color image of 600 to 100.
In a pressure-sensitive copying sheet for optical reading capable of being optically read in a wavelength region of 0 nm, a solid wax-containing microcapsule-containing layer is provided on a support, and a color former-containing microcapsule-containing layer is provided thereon. We succeeded in obtaining excellent optical reading performance and completed the present invention.

In the present invention, the color image is 600 to 1000.
A sheet which is suitable for a reading light source because it has absorption in the wavelength region of nm, and which is formed by applying the coloring agent and drying it (C
In B, CFB and self), an excellent optically readable pressure-sensitive copying sheet could be obtained by providing a solid wax-encapsulated microcapsule-containing layer on a support and a color-forming agent-encapsulated microcapsule layer thereon. . The melting point of the solid wax is preferably 30 ° C. or higher. More preferably, it is 40 ° C. or higher.

Solid wax plays an important role in the present invention. Wax (English name: wax) is, as described in "Chemical Encyclopedia" (published by Kyoritsu Shuppan), in a chemically strict sense, fatty acids and higher monohydric alcohols or dihydric alcohols unnecessary for water. And ester, which are classified into solid wax and liquid wax (eg, sperm whale oil, Tsuchi whale oil) by their properties, and by their origin, vegetable wax (eg, carnauba wax, cotton wax) and animal wax (eg: wax). Beeswax, wool wax). However, wax does not follow the above chemical composition formula. For example, fat with a high melting point such as wood wax is called wax, and montan wax or hydrocarbon-based ozokerite, which is naturally produced alone, There is petroleum wax produced by melting in crude oil. Petroleum wax is classified into paraffins, microcrystalline wax, and petrolatum according to the production route and properties. These have different chemical components from the animal and vegetable wax.

Solid waxes useful in the present invention are broadly defined waxes as exemplified above, excluding liquid waxes. Since wax is also called wax in Japan, so-called wax is the wax in the present invention. To encapsulate one or more of these solid waxes in microcapsules, they are heated above their melting point to form a liquid,
After emulsifying in warm water using a suitable emulsifier, microcapsulation operation is preferably performed. This operation is also usually carried out under heating, but the differential thermal analysis has shown that the wax solidifies in the microcapsules if it is cooled to room temperature after the operation.

Further, particularly when the solid wax has a high melting point, when the solid wax is heated to form a liquid, a small amount of a high boiling point solvent is added to facilitate liquefaction. The amount of solvent to be added must be within the range where the solid wax / solvent compatibilizer solidifies when cooled to room temperature. Experiments have shown that suitable solvent additions are generally less than or equal to the weight of solid wax. It should be noted that if more solvent is added than necessary, the fine lines of the pressure-sensitive recorded image will become thicker and the pressure resistance will decrease. The type of solvent is not particularly limited as long as it is immiscible with water, but aromatic, alicyclic, or aliphatic solvents having a boiling point of about 200 ° C. or higher are preferable, and they are used in the carbonless sheet industry. The high boiling point solvent for microcapsules can be used as it is.

In the present invention, solid wax-encapsulated microcapsules are provided on a support, and a color-encapsulating agent-encapsulated microcapsule-containing layer is provided on the support, so that the color development required for optical reading can be achieved with a significantly smaller amount of the color-developing agent applied. The concentration is obtained.

The support used in the present invention is preferably acidic paper or neutral paper mainly composed of cellulose fibers,
Synthetic paper and polyethylene film are also preferable. Other,
It is not particularly limited as long as it is a sheet.

In the present invention, examples of the color former which produces a color image having an absorption wavelength in the range of 600 to 1000 nm include:
Japanese Patent Publications No. 58-5940, No. 49-17489, No. 63-51113, No. 4-5064, No. 4-5065, and No. 4-5066.
No. 4-5068, No. 62-243652, No. 62-243653, and No. 62-25797.
No. 0, No. 62-288078, No. 63-10.
No. 2975, No. 63-37158, No. 63-
The following compounds as described in JP-A-154389, JP-A-63-185674, JP-A-4-173288, JP-A-5-32040 and the like can be mentioned.

3,3-bis [1,1-bis (4-dimethylaminophenyl) ethylene-2-yl] -4,5,
6,7-Tetrachlorophthalide, 3,3-bis [1,1
-Bis (2-methoxy-4-diethylaminophenyl)
Ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis (4-dimethylaminophenyl) ethylene-2-yl] -5-pyrrolidinophthali 3,3-bis [1,1-bis (4-dimethylaminophenyl) ethylene-2-yl] -5-azaphthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene -2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis (4
-Pyrrolidinophenyl) ethylene-2-yl] -5-ethoxyphthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -5-pyrrolidinophthalide, 3,3-bis [1,1-bis (4-piperidinophenyl) ethylene-2-yl] -4,5,6
7-tetrachlorophthalide,

3,3-bis [1,1-bis (4-morpholinophenyl) ethylene-2-yl] -4,5,6,7
-Tetrachlorophthalide, 3,3-bis [1,1-bis (2-methyl-4-pyrrolidinophenyl) ethylene-2
-Yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [1,1-bis (jurolidin-5-yl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3- [2- (P-dimethylaminophenyl) -2- (P-methoxyphenyl) ethenyl] 3-
[2- (P-pyrrolidinophenyl) -2- (P-methoxyphenyl) ethenyl] phthalide, 3,3-bis [2-
(P-Dimethylaminophenyl) -2- (P-methoxyphenyl) ethenyl] phthalide, 3,3-bis [2-
(P-Pyrrolidinophenyl) -2- (P-methoxyphenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [2- (P-pyrrolidinophenyl] ) -2- (P-Methylphenyl) ethylene-2
-Yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [2-P-dimethylaminophenyl) -2
-(P-Methoxyphenyl) ethylene-2-yl]-
4,5,6,7-Tetrachlorophthalide, 3,3-bis [2- (P-dimethylaminophenyl) -2- (P-methylphenyl) ethylene-2-yl] -4,5,6 7
-Tetrachlorophthalide,

3,6,6'-Trisdimethylamino-spiro (fluorene-9,3'-phthalide), 3,6,6
6'-trisdiethylamino-spiro (fluorene-
9,3'-phthalide), 3,6,6'-trisdi-n-
Propylamino-spiro (fluorene-9,3'-phthalide), 3-di-n-butylamino-6-dimethylamino-6'-diethylamino-spiro (fluorene-9,
3'-phthalide), 3,3-bis [2- (4-dimethylaminophenyl) -2- (4-methoxyphenyl) ethyl] 4,5,6,7-tetrachlorophthalide, 3,3-
Bis [2-2-bis (4-dimethylaminophenyl) ethenyl] 4,5,6,7-tetrachlorophthalide, 3,
3-bis [2-2-bis (4-dimethylaminophenyl) ethenyl] 5-pyrrolidinophthalide, 3,3-bis [2-2-bis (4-dimethylaminophenyl) ethenyl] 5-azaphthalide, 3 , 3-Bis [2- (p-methoxyphenyl) -2- (p-pyrrolidinophenyl) ethenyl] 4,5,6,7-tetrachlorophthalide, 3,3
-Bis [2- (p-methoxyphenyl) -2- (p-dimethylaminophenyl) ethenyl] 4,5,6,7-tetrachlorophthalide,

6 '-[{4- (4-anilino) anilino} anilino] -2'-chloro-3'-methylspiro [phthalide-3,9-xanthene] 3- (Np-tolyl-N-ethyl) Amino) -7- (N-phenyl-N-methyl) fluorane, 6 '-{4- (4-anilino) anilino} -2'-phenylamino-3'-methylspiro [phthalide-3,9-xanthene, 6 '-Diethylamino-2- {4- (4-anilino) anilino} -2'-phenylamino-3'-methylspiro [phthalide-3,9
-Xanthene], 3-3-bis (4'-dimethylamino-2-methoxyphenyl) -4-azaphthalide, 3-3
-Bis (4'-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-di (N-dimethylamino) -fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3- Diethylamino [a]
Examples thereof include (2,2-dimethyl-4-methyl) -pyridino-fluorane, but are not limited thereto.

As the color former (electron donating color former) used in the present invention, the following color formers known in the art can also be used in combination. (1) As a triarylmethane compound, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone),
3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,
2-dimethylindol-3-yl) phthalide, 3-
(P-Dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-3-
Yl) phthalide, 3,3-bis- (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide,
3,3-bis- (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis-
(9-Ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis- (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-
p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl-6-dimethyl-aminophthalide, etc.,

(2) As a diphenylmethane compound,
4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leuco auramine, N-
2,4,5-trichlorophenyl leuco auramine, etc.

(3) Rhodamine B-anilinolactam, rhodamine B-p-nitroanilinolactam, rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, as xanthene compounds. 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7-3,4-dichloroanilinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane , 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-
Methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- ( 4-nitroanilino) fluoran, etc.

(4) As thiazine compounds, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.,

(5) As spiro compounds, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methylnaphtho- ( 3-methoxy-benzo) -spiropyran,
3-propyl-spiro-dibenzopyran, etc.,

In addition, JP-A-63-230387 and "Dye for pressure-sensitive and heat-sensitive recording paper" (coloring material, 61 [5] P
292-302. 1988). Alternatively, mention may be made of a mixture thereof. These are determined by the application and the desired properties.

The color former as described above is usually encapsulated in a state in which it is dissolved in a hydrophobic medium, and the hydrophobic medium is not particularly limited as long as it is used in a general pressure-sensitive copying sheet. Specific examples include (a) aromatic hydrocarbons such as diarylethane, alkylbiphenyl, alkylterphenyl, alkylnaphthalene, triarylmethane, diphenylalkane, hydroanthracene, hydrophenanthrene, and dibenzyltoluene.

(B) As mineral oil, kerosene, paraffin,
Naphthenic oil, chlorinated paraffin, etc., (c) vegetable oil, cottonseed oil, corn oil, coconut oil, etc., (d) alcohol, oleyl alcohol, tridecyl alcohol, benzyl alcohol, 1-phenylethyl alcohol, glycerin, etc. e) Organic acids such as oleic acid,

As the ester (f), dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate,
Dioctyl phthalate, diethyl adipate, propyl adipate, di-n-butyl adipate, dioctyl adipate, etc., (g) as an organic phosphoric acid compound, tricresyl phosphate, tributyl phosphite, tributyl phosphite oxide, etc.,

(H) Ethers such as phenyl cellosolve, benzyl carbitol, polypropylene glycol, propylene glycol monophenyl ether, etc.
(I) N, N-dimethyllauramide as an amide,
N, N-dimethyl stearamide, N, N-dihexyl octyl amide, etc., (j) ketone as diisobutyl ketone, methyl hexyl ketone, etc., (k) alkyl carbonate as ethylene carbonate, propylene carbonate, etc., or a mixture thereof. I can name it. These are determined by the application and the desired properties.

When the color former is encapsulated in a microcapsule, it is possible to dissolve an ultraviolet absorbing substance in the inner phase, which is conventionally used, and a substance used for general pressure-sensitive copying sheets. If there is no particular limitation. It is also possible to add an ultraviolet absorbing substance to the solid wax microcapsules to the extent that the characteristics are not impaired. Specific examples of the ultraviolet absorbing substance include (a) salicylic acid-based phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like (b) benzophenone-based 2,4-dihydroxybenzophenone , 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4 , 4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, etc.,

(C) As a benzotriazole type, 2
(2'-Hydroxy-5'-methylphenyl) benzotriazole, 2 (2'-hydroxy-5'-tert-
Butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)
Benzotriazole, 2 (2'-hydroxy-3'-t
ert-Butyl-5'-methylphenyl) -5chlorobenzotriazole, 2 (2'-hydroxy-3 ', 5'
-Di-tert-amylphenyl) benzotriazole, 2 (2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like, as (di) cyanoacrylate-based, 2-ethylhexyl-2-cyano-3,3 '
-Diphenyl acrylate, ethyl-2-cyano-3,
Examples thereof include 3'-diphenyl acrylate and the like, or a mixture thereof. These are determined by the application and the desired properties.

When the color-forming agent is microencapsulated, it is possible to use a UV stabilizer dissolved in the internal phase as is conventionally used, and it is a substance used for general pressure-sensitive copying sheets. If there is no particular limitation. It is also possible to add a UV stabilizer to the solid wax microcapsules to the extent that the characteristics are not impaired. Specific examples of the UV stabilizer include (a) quenchers,
Nickel bis (octylphenyl) sulfide,
[2,2′-thiobis (4-t-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-t-butyl-4-hydroxybenzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate (B) A compound having a 2,2,6,6-tetramethyl-piperidine ring as a hindered amine light stabilizer (HALS): bis (2,2,6,6-tetramethyl-
4-piperidyl) sebacate and the like, or a mixture thereof can be mentioned. These are determined by the application and the desired properties.

When the color former is microencapsulated, an antioxidant can be dissolved in the internal phase as is conventionally used, and it is a substance used for general pressure-sensitive copying sheets. If there is no particular limitation. It is also possible to add an antioxidant to the solid wax microcapsules to the extent that the characteristics are not impaired. Specific examples of antioxidants include (a) monophenol-based
6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6, -di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate, etc.,
(B) As a bisphenol type, 2,2'-methylene-
Bis- (4-methyl-6-t-butylphenol),
2,2'-methylene-bis- (4-ethyl-6-t-butylphenol), 4,4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidene-bis- ( 3-methyl-6-t-butylphenol)
etc,

(C) As a high-molecular type phenol-based compound, 1,
1,3-tris- (2-methyl-4-hydroxy-5-
t-Butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-)
(Hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, tocopherols, and the like, and (d) sulfur-based dilaurylthiodipro Pionate, dimyristyl thiodipropionate, distearyl thiodipropionate, etc. As (pho) phosphoric acid type, triphenyl phosphite, diphenyl isodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6) -T-butylphenyl-di-
Tridecyl) phosphite, cyclic neopentanetetraylbis (octadecylphosphite), tris (nonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 10-decyloxy-9,10-dihydro-9-oxa-10- Examples thereof include phosphaphenanthrene and the like, or a mixture thereof. These are determined by the application and the desired properties.

The coloring agent having absorption in the wavelength region of 600 to 1000 nm is usually added in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the hydrophobic medium. The other color former is usually added in an amount of 0.1 to 30 parts by weight.

The microencapsulation method used in the present invention is not particularly limited, but the microcapsules obtained by the coacervation method using gelatin, gum arabic or the like generally breaks the film when mixed with latex. Interfacial polymerization method, in situ
It is preferable to use the u polymerization method or the microbe microencapsulation method. The emulsifier used for in situ polymerization encapsulation is preferably a polymer electrolyte. Specifically, styrene-maleic anhydride copolymer, styrene-benzyl methacrylate-maleic anhydride copolymer, α-alkylstyrene-maleic anhydride copolymer, nuclear monoalkyl-substituted styrene-maleic anhydride copolymer, Nuclear dialkyl-substituted styrene-maleic anhydride copolymer, styrene-maleic anhydride monoalkyl ester copolymer, ethylene-maleic anhydride copolymer, polystyrene sulfonic acid, polyacrylic acid, acrylic acid-acrylic acid ester copolymer Aqueous solutions such as, and mixed solutions of these are used. The emulsifier used for interfacial polymerization encapsulation is the above-mentioned in situ
In addition to encapsulation, an aqueous solution of polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, various (wheat, potato, corn, etc.) starch, etc.,
Alternatively, a mixed aqueous solution of these is also used. Incidentally, known substances having nonionic, cationic, and amphoteric surface-active substances may be added to the extent that no problem occurs in the encapsulation process and used in combination.

The size (average diameter) of the color-forming agent-containing microcapsules used in the present invention is preferably in the range of 0.1 to 20 μm, and particularly preferably in the range of 1 to 10 μm. For solid wax-encapsulated microcapsules, 0.1-10 μm
Is preferable, and a range of 0.5 to 4.0 μm is particularly preferable. The coating amount of the color forming agent is not particularly limited, but from the viewpoint of color forming performance, it is 5 to 2000 mg / m 2.
² , particularly preferably 20 to 300 mg / m ² .
The coating amount of the solid wax-encapsulated microcapsules is not particularly limited, but from the viewpoint of color development performance, the dry coating amount is 0.1 to 15 g / m ² , and particularly preferably 0.5 to
It is in the range of 5.0 g / m ² .

A water-based coating liquid is usually used for coating used in the present invention, and the coloring agent-containing microcapsule dispersion liquid and the solid wax-containing microcapsule dispersion liquid obtained by the above-mentioned method may be used as needed. Adjustment by adding various auxiliaries known in the art such as latex binder, water-soluble binder, capsule protector (stilt), white pigment, surfactant, defoaming agent, thickener, preservative, colorant, etc. To be done. The capsule content in the capsule coating liquid is usually adjusted within the range of 5 to 80 parts by weight with respect to 100 parts by weight (solid portion) of the coating liquid.

Specific examples of the latex type binder used in the present invention include styrene-butadiene type copolymer latex, acrylonitrile-butadiene type copolymer latex, vinyl acetate type, acrylic type latex and the like,
Examples thereof include alkali thickening type latex. Examples of the water-soluble binder include gelatin, albumin, casein, starch, pregelatinized starch, oxidized starch, etherified starch, esterified starch, sodium alginate, arabic gum, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid. Acrylamide, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, methylcellulose, etc. Examples thereof include molecular compounds. These can also be mixed and used. Usually, these are used in amounts of 5 to 100 parts by weight of dry solid microcapsules.
A range of 100 solids by weight is preferred. Particularly preferably,
It is in the range of 5 to 50 solid parts by weight.

The capsule protector (stilt) used in the present invention is preferably a known one such as wheat starch granules, corn starch granules, pea starch granules, various plastic pigments, pulp powders, etc., and its size (average diameter).
Is preferably in the range of 1 to 100 μm. Particularly preferably, the range is 5 to 30 μm. Examples of the white pigment include calcium carbonate, aluminum hydroxide, zinc oxide, titanium oxide, kaolin, talc and the like.
As a coating method, coating and drying are carried out by an ordinary coating machine (coater). As a specific coating machine, an air knife coater, a blade coater, a rod coater, a bar coater, a roll coater, a size press coater, a curtain coater or the like is used.

The receiving sheet having the color developer layer can be obtained by applying the color developer to the support as an aqueous or non-aqueous coating liquid, and an aqueous coating liquid is usually used. In addition to the color developer, the coating liquid is added with a binder, a pigment, and if necessary, various known auxiliaries such as a dispersant, a surfactant, an ultraviolet absorber, an optical brightener, a thickener, and a defoaming agent. Then, it is prepared and coated on a support using a coating machine as described above.

Examples of the electron-accepting color developer used in the present invention are not particularly limited, but compounds having a phenolic hydroxyl group, inorganic solid acid compounds, organic solid acid compounds, pressure-sensitive copying sheets and Examples include those used in the field of heat-sensitive sheets. Examples thereof include novolac type phenolic resins and polyvalent metal salts thereof, salicylic acid derivatives and polyvalent metal salts thereof, salicylic acid resins and polyvalent metal salts thereof, and the like. The novolac type phenol resin is produced by polycondensing various phenol derivatives and a lower aldehyde represented by formaldehyde as raw materials in the presence of an acidic catalyst. At this time, examples of the phenolic raw material used include unsubstituted phenol, alkyl group-substituted phenol (eg, cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, etc., mainly para-substituted), aralkyl group-substituted phenol (eg, , Para-benzylphenol, para-cumylphenol, etc.), aryl group-substituted phenol (eg, para-phenylphenol), halogen-substituted phenol (eg, para-chlorophenol), and the like.

The salicylic acid derivative is a compound having at least one aromatic substituent, specifically, 3-phenylsalicylic acid, 5-phenylsalicylic acid, 3-benzylsalicylic acid, 5-benzylsalicylic acid, 3- (α-methyl). Benzyl) salicylic acid, 5- (α-methylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) salicylic acid, 5- (α, α-dimethylbenzyl) salicylic acid, 3,5-diphenylsalicylic acid, 3,5-di (Α-
Examples thereof include methylbenzyl) salicylic acid, 3,5-dibenzylsalicylic acid, 3,5-di (α, α-dimethylbenzyl) salicylic acid, and 3,5-di (4-methylbenzyl) salicylic acid.

Further, polyvalent metal salt compounds composed of salicylic acids, rosins and polyvalent metal compounds disclosed in JP-A-2-563 can also be mentioned as preferable developers. Salicylic acids have a total carbon number of 8 or more,
In particular, a known salicylic acid compound having an alkyl group of 8 to 20 is used. As rosins, gum rosin,
Any of natural and modified rosins such as wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, polymerized rosin, maleated rosin, fumarized rosin, formaldehyde modified rosin and rosin phenol resin can be effectively used.

As the salicylic acid resin and its polyvalent metal salt, all of the above-mentioned compounds can be used, but as an example, the above salicylic acid derivative and styrene, o. m. p-
Examples of salicylic acid resins obtained by reacting styrene derivatives such as methylstyrene, α-methylstyrene, β-methylstyrene and the like at a molar ratio of 1: 0.5 to 10 with a Friedel-Crafts reaction in the presence of a strong acid catalyst are polyvalent metal salts. To be Examples of the polyvalent metal include Ca, Mg, Al, Zn, and Mn, but it is most preferable to use it as a zinc salt. These color developers may be used in combination of two or more kinds.

The coating amount of the color developer coating liquid on the support and the amount of the color developer mixed in the color developer coating liquid are not particularly limited, but usually the color developing performance and the economical efficiency are ² to 20 g / m ² from the surface, and more preferably ³ to 15 g / m ² .
m ² and ^{2 to} 80% by weight, more preferably 5 to 40% by weight.

Examples of pigments used in combination with the color developer include heavy calcium carbonate, light calcium carbonate, calcium sulfate, kaolin, calcined kaolin, talc, aluminum hydroxide, aluminum silicate, magnesium oxide,
Magnesium carbonate, magnesium sulfate, zinc oxide, activated clay, fine silicic acid, titanium oxide, calcium silicate, urea-
Examples include usual inorganic or organic white pigments such as formaldehyde resin. These developers and pigments are coated on a support together with an adhesive as needed, but an intermediate coating layer made of a pigment, an adhesive, etc. is formed on the support to form a developer layer. Is also good.

[0048]

EXAMPLES Next, the features of the present invention will be described in detail with reference to Examples and Comparative Examples. Of course, the present invention is not limited to the Examples, and therefore the substances used, production conditions, etc. are also included in the Examples. It is not limited to the description of. In the examples and comparative examples, unless otherwise specified, it is expressed as parts by dry solid.

Example 1 [Preparation of Microcapsules Encapsulating Coloring Agent] As a coloring agent,
3,3-Bis- (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide (4 parts) and 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3
4 parts of-(P-diethylaminophenyl) phthalide was mixed with a diarylethane solvent (Hisol SAS N-296:
A solution dissolved in 92 parts of Nippon Petrochemical Co., Ltd. was prepared.
To 220 parts of a 5% aqueous solution of styrene-maleic anhydride copolymer, 180 parts of the above hydrophobic liquid was gradually added with vigorous stirring, and stirring was continued until the 50% volume average diameter on a Coulter counter became 5 μm to emulsify. A liquid was obtained. Separately, 11 parts of melamine, 21 parts of 37% aqueous formaldehyde solution, and 28 parts of water were dissolved by heating to obtain an aqueous solution of melamine-formaldehyde initial condensate, which was added to the emulsion and stirred at a temperature of 70 ° C. for 2 hours. A microcapsule solution was obtained.

[Preparation of Solid Wax-Encapsulating Microcapsules] As the solid wax, paraffin wax having a melting point of 54 to 56 ° C. was maintained at 70 ° C. to be in a liquid state. To 220 parts of a 5% aqueous solution of styrene-maleic anhydride copolymer, 180 parts of the above paraffin wax liquid was gradually added with vigorous stirring and stirred until the 50% volume average diameter in a Coulter counter became 3.5 μm. Then, an emulsion was obtained. Separately, 11 parts of melamine, 37% formaldehyde aqueous solution 2
An aqueous solution of a melamine-formaldehyde initial condensate obtained by heating and dissolving 1 part and 28 parts of water was added to the emulsion, and 70
The mixture was stirred at a temperature of ° C for 2 hours to obtain a microcapsule liquid.

[Preparation of sheet coated with solid wax-encapsulated microcapsules]
15 parts of styrene-butadiene copolymer latex (manufactured by Japan Synthetic Rubber Co., Ltd.) was added to obtain a coating solution. The coating solution is applied by air knife coating method to 41 g / m ² of neutral cellulose fiber base paper so that the dry coating amount of the color developer coating solution is 3.0 g / m ² and dried, and solid wax-encapsulated microcapsule coating is applied. Got the sheet.

[Preparation of carbon-free upper sheet (CB)] 70 parts of wheat starch and 35 parts of styrene-butadiene copolymer latex (manufactured by Japan Synthetic Rubber Co., Ltd.) were added to 100 parts of the above-mentioned coloring agent-encapsulated microcapsules to form a coloring agent. A coating liquid was obtained. By the air knife coating method, the color developer coating solution was coated on the solid wax-containing microcapsule coating sheet at different coating amounts to obtain a carbon-free upper sheet (CB).

[Measurement of the coating amount of the carbonless top sheet (CB)] The carbonless top sheet (C obtained above)
A pressure of about 1000 kg / m ² was applied to B) to break the microcapsules, and the color former was extracted with acetone. Appropriate hydrochloric acid was added to develop color, and the coating amount of the color former was measured with a spectrophotometer.

[Preparation of carbonless lower sheet (CF)] (a) Synthesis of salicylic acid resin 3,5-di (4-methylbenzyl) salicylic acid 6.9 g
(0.02 mol), 50 ml of ethyl ether and 12 g of sulfuric acid as a catalyst were charged into a glass reactor and the temperature was maintained at 20 to 30 ° C. with stirring. Then, at the same temperature, 6.24 g (0.06 mol) of styrene was added dropwise over 8 hours for reaction. After dropping, the mixture was aged at the same temperature for 8 hours, warm water was added, the solvent was distilled off, and the deposited precipitate was filtered. This was vacuum dried to obtain 13.0 g of a white resin. The obtained resin has a weight average molecular weight of 1380 and a softening point of J
It was 62 ° C. when measured with a ring and ball softening point measuring device according to IS-K-2548.

(B) Synthesis of Salicylic Acid Resin Polyvalent Metal Salt 10 g of the resin obtained in (a) and 0.65 g of caustic soda were dissolved in 200 ml of hot water with stirring. Then, while maintaining the temperature of the solution at 30 to 35 ° C., 30 m of water was previously added.
3 g of an aqueous solution prepared by dissolving 2.5 g of zinc sulfate heptahydrate in 1
Dropped in 0 minutes. A white precipitate was deposited, and the mixture was stirred at the same temperature for 2 hours, filtered, washed with water, and dried.
10.5 g (yield quantitative) of white powder was obtained. This was a zinc salt of a salicylic acid resin, and the result of analyzing the zinc content was 4.82%.

(C) Preparation of Developer Dispersion Liquid The metal salt of salicylic acid resin obtained in (b) was used as a developer and dispersed with a sand grinding mill in the following composition to prepare a suspension. Developer 10 parts by weight 10% polyvinyl alcohol aqueous solution (Kuraray # 117) 3 parts by weight Water 22.5 parts by weight Next, a developer dispersion having the following composition was prepared using the suspension.

A color developer coating solution having the following composition was prepared and dried with an air knife coater so that the dry coating amount was 6 g / m ^2.
1 g / m ² of neutral cellulose fiber base paper was applied and dried to obtain a carbonless bottom (CF) sheet. (Combining developer coating liquid) Developer dispersion 35.5 parts by weight Sodium pyrophosphate 0.5 parts by weight Pigment (light calcium carbonate) 100 parts by weight 10% oxidized starch aqueous solution 150 parts by weight

[Printing of barcode] The above CB obtained
And CF are set, and dot printer YL-5545
A bar code was printed by (Yamada Industry Co., Ltd.). The barcode used was CODE-39.

[Evaluation of Copy Bar Code] With respect to the CF copy bar code, the bar code analysis rate, the standard deviation of the bar code analysis rate, and the PCS concentration are respectively determined by the bar code verifier LAS.
It was measured with ERCHEKII (manufactured by OLYMPUS-SYMBOL). The data was measured at 10 points on the bar-printed portion and averaged. Barcode analysis rate is LASERC
It is a value independently verified by HEKII, and the higher the value, the better the bar code reading performance. The reading wavelength is 6
70 nm and the PCS concentration is defined as the following Equation 1. In general, the higher the PCS value, the clearer the image identification and the higher the reading performance.

[0060]

## EQU1 ## PCS density = (A−B) / A A: Maximum reflectance of space portion (%) B: Minimum reflectance of bar portion (%)

The evaluation results of the CF bar code reading performance are summarized in Table 1.

Comparative Example 1 [Preparation of solid wax-containing microcapsule coated sheet] was not carried out in the above-mentioned Example 1. Similarly, in [Preparation of carbon-free sheet (CB)], 35 parts were substituted for 70 parts of wheat starch, and 18 parts were substituted for 35 for the styrene-butadiene copolymer latex. in addition,
The coloring agent coating solution was applied to a neutral cellulose fiber base paper of 41 g / m ² with a different coating amount and dried to obtain a coloring agent-containing microcapsule coated sheet (CB). The same procedure as in Example 1 was performed except for the above changes.

[0063]

[Table 1]

As is apparent from Table 1, the bar code analysis rate in Example 1 was 100%, and no fluctuation was observed in the measured value. On the other hand, in Comparative Example 1, the barcode analysis rate is lower than 100%, and the measured values vary.

[0065]

According to the present invention, a pressure-sensitive copying sheet for optical reading which exhibits excellent optical reading performance with a small amount of coloring agent applied is obtained.

Claims (2)

[Claims] 1. A pressure-sensitive copying sheet for optical reading capable of optically reading a color-developed image by a color-developing reaction between an electron-donating color developing agent and an electron-accepting color developing agent in a wavelength region of 600 to 1000 nm. A pressure-sensitive copying sheet for optical reading, comprising a solid wax-encapsulated microcapsule-containing layer provided on top of the electron-donating color-forming agent-encapsulated microcapsule-containing layer. 2. The pressure-sensitive copying sheet for optical reading according to claim 1, wherein the melting point of the solid wax is 30 ° C. or higher.