JPH05177927A - Pressure sensitive copying paper - Google Patents

Abstract

PURPOSE:To prepare pressure sensitive copying paper with controlled coloring fog, etc., by setting a layer containing synthetic polymer microcapsules having a specified average particle size and membrane thickness in which a specified phthalide derivative is sealed on a substrate. CONSTITUTION:A specified amount of a color coupler of a phthalide derivative represented by the formula I (R1: halogen atoms, C1-C4 alkyl groups, C1-C4 alkoxy groups, nitro groups, amino groups, etc.; R2: hydrogen atom, C1-C4 alkyl groups; R3-R6: hydrogen atom, C1-C6 alkyl groups, etc.; X, Y: hydrogen atom, C1-C4 alkyl groups; n: integer 0-4), a protecting agent, a water soluble binder, etc., are mixed to prepare a microcapsule coating solution. A substrate is coated with the microcapsule coating solution and dried to form a layer containing the microcapsules having an average particle size of 3-10mum and an average membrane thickness of 0.1-0.6mum. On the other surface of the substrate is formed a layer containing zinc salt of a salicylic acid derivative (an electron accepting developer) to obtain pressure sensitive copying middle paper.

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 paper utilizing a color-developing reaction between an electron-donating color former and an electron-accepting developer, and particularly when applied to an optical character reading (OCR) device. The present invention relates to a pressure-sensitive copying paper exhibiting excellent characteristics.

[0002]

2. Description of the Related Art Pressure-sensitive copying paper (so-called carbonless paper) is
Electron-donating color formers such as crystal violet lactone and benzoyl leuco methylene blue (hereinafter referred to as color formers) and electron-accepting developers such as activated clay, bentonite, phenolic resins, polyvalent metal salts of aromatic carboxylic acids (hereinafter, It is a copy paper that utilizes the color development reaction of a color developer), and is a top paper that is coated with microcapsules containing a color developer on the back side of the base paper, which are produced by methods such as phase separation, interfacial polymerization, and in-situ. And the lower paper on which the surface of the base paper is coated with the color developer so that the coated surfaces face each other, and the surface of the upper paper is written and pressure-printed with a typewriter to form a color image on the lower paper. It is a copy paper to be formed.

When it is desired to copy a large number of sheets, the number of sheets of the middle paper coated with the color developer on the front surface of the base paper and microcapsules on the back surface is required between the upper paper and the lower paper. Just inserted. Also, a so-called self-coloring paper in which the above-mentioned microcapsules and a color developer are formed on the same surface of the base paper as a laminated or mixed layer is well known as one form of pressure-sensitive copying paper. The demand for pressure-sensitive copying paper has expanded remarkably in a wide variety of ways, centering on general vouchers, delivery vouchers, unified vouchers, contract documents, computer paper, etc., along with the expansion of its applications.

On the other hand, office automation is advancing along with the development of the information processing industry, and the rationalization of office processing is promoted. And as a method of rationalization, OCR and O
MR devices have become widespread, and in general companies, it has become necessary to make order slips, sales slips, shipping slips, purchase slips, input / output slips, etc., which are the main slips, suitable slips for OCR devices and OMR devices. There is. Moreover, it is necessary to make many copies of these slips because of the necessity of the office system.

[0005]

Under such circumstances, there is an increasing demand for development of OCR slips using pressure-sensitive copying paper, but the PCS value in the infrared region of the color image of the pressure-sensitive copying paper is 0. O with a reading wavelength in the infrared region of about 15
There is a problem that the CR device functions as a dropout color and cannot be read. Also 600-70
Even for an OCR device having a reading wavelength in the visible region of 0 nm, there is a problem that the PCS value is only about 0.4 in black color development of pressure-sensitive copying paper and reading is uncertain. In addition, the color density of pressure-sensitive copying paper may change depending on the writing pressure (printing pressure), and color fog also occurs due to environmental factors such as unintentional pressure and heat and humidity. In the development of paper, these properties peculiar to pressure-sensitive copying paper have also been a development difficulty.

Therefore, the inventors of the present invention have conducted extensive studies to improve these difficulties, and as a result, use a color former having a specific structure as a color former and use it as a wall film material for microcapsules containing the color former. When a synthetic polymer material is used, its particle size and film thickness are specified, and when it is combined with a specific developer, an OCR device having a reading wavelength in the near infrared region of 600 to 800 nm can be obtained. The present inventors have completed the present invention by finding that a pressure-sensitive copying paper exhibiting extremely stable reading performance and having less color density change and color fog can be obtained.

[0007]

SUMMARY OF THE INVENTION The present invention is a pressure-sensitive copying paper utilizing a color-forming reaction between an electron-donating color former and an electron-accepting color developer. Containing a phthalide derivative represented by, the color former is encapsulated in synthetic polymer microcapsules, and the average particle diameter is 3 to 10 microns and the average film thickness is 0.1 to 10.
A pressure-sensitive copying paper having a size of 0.6 μm and using a zinc salt of a salicylic acid derivative as an electron-accepting developer.

[Chemical 1][In the formula, R₁Is a halogen atom, C₁~ C_FourThe alkyl
Base, C₁~ C_FourAlkoxy group, nitro group, amino group,
Represents a substituted amino group or an alicyclic amino group, R₂Is hydrogen
Child or C₁~ C_FourAlkyl group of R₃~ R₆Are each
Hydrogen atom, C₁~ C ₆Alkyl group of C₂~ C₆The al
Coxyalkyl group, C₆~ C_TenAryl group of C₇~ C
_TenAralkyl group of C_Five~ C₈The cycloalkyl group of
And R₃And R _Four, And R_FiveAnd R₆Are adjacent to each other
You may form a ring with an elementary atom. X and Y are hydrogen sources
Child, C₁~ C_FourAlkyl group of C₁~ C_FourThe alkoxy
Represents a group or a halogen atom. n represents an integer of 0 to 4
You ]

[0008]

[Function] As an index showing the degree of readability of OCR,
Since there is the above-mentioned PCS (Print Contrast Signal) value,
First, the PCS value will be described. That is, the PCS value is
It expresses the relative degree of darkness between the color print and the paper and is expressed by the following equation. PCS = (Rw-Rp) / Rw Here, Rw represents the maximum reflectance of the blank white paper portion in the target area, and Rp represents the maximum reflectance of printing at an arbitrary measurement point (P). And for general OCR paper, PCS
The higher the value, the clearer the identification of characters and the higher the readability.

However, when the pressure-sensitive copying paper is used as the OCR paper, even if the PCS value of the color image (printing) is sufficiently high, the change in the printing density due to the writing pressure and the discontinuity of the printing,
When printing blurring or the like occurs, readability is significantly reduced. Therefore, the suitability as an OCR sheet cannot be judged only by the PCS value. Further, changes in print density due to writing pressure, print discontinuity, print blurring, and the like tend to occur more easily in the case of copying a large number of sheets.

The inventors of the present invention have conducted extensive studies to improve these difficulties, and as a result, as described above, a color-forming agent having a specific structure is used as the color-forming agent, and a microcapsule containing the color-forming agent is incorporated. A pressure-sensitive copying paper having excellent reproducibility and excellent OCR aptitude by using a synthetic polymer material as a wall film material, defining its particle diameter and film thickness, and combining it with a specific developer. The present invention has been completed and the present invention has been completed.

A color image obtained by incorporating a phthalide derivative having a specific structure as a color developing agent and combining it with a zinc salt of a salicylic acid derivative as a color developing agent is 600 to 800 n.
It shows a high PCS value for an OCR device having a reading wavelength in the near infrared region of m. By specifying a synthetic polymer material as the wall film material of the microcapsules encapsulating the color-forming agent, the occurrence of color stains is suppressed, and the average particle size is limited to 3 to 10 microns. The non-uniformity or discontinuity of the color density due to the difference in pressure is eliminated, and the color stain caused by the unintended pressure is more significantly suppressed. Also, by specifying the average film thickness of the microcapsules to be 0.1 to 0.6 microns, color fog caused by environmental factors such as heat and humidity can be further improved, resulting in the formation of sharp and clear prints. Therefore, erroneous reading by the OCR device is completely prevented, and a pressure-sensitive copying paper for the OCR device having stable quality characteristics is obtained.

By the way, if a natural material is used as the wall film material of the microcapsules, the effect of preventing color stains becomes insufficient. If the average particle size of the capsules is less than 3 microns, the color density is lowered and the readability is deteriorated. If the average particle size exceeds 10 microns, color stains occur.
The average particle size of the capsule is adjusted in the range of 3 to 10 μm, preferably 5 to 8 μm. Further, if the average film thickness is less than 0.1 micron, unnecessary coloring stains increase, and if it exceeds 0.6 micron, the color developing sensitivity decreases, so the average film thickness of the capsule is 0.1 to 0.6. micron,
It is preferably adjusted in the range of 0.1 to 0.4 micron.

Specific examples of the phthalide derivative such as [Chemical Formula 1] used in the present invention include 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1-yl].
-6-Dimethylaminophthalide, 3- [2,2-bis (4-diethylaminophenyl) ethylene-1-yl]
-6-Dimethylaminophthalide, 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1-yl]
-6-diethylaminophthalide, 3- [2,2-bis (4-diethylaminophenyl) ethylene-1-yl]
-6-Diethylaminophthalide, 3- [2- (4-dimethylaminophenyl) -2- (4-diethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide, 3- [2- (4- Dimethylaminophenyl) -2
-(4-Diethylaminophenyl) ethylene-1-yl] -6-diethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-N-i-pentyl) aminophenyl] ethylene-1-yl } -6-Dimethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-Ni)
-Pentyl) aminophenyl] ethylene-1-yl}-
6-diethylaminophthalide, 3- {2,2-bis [4
-(N-ethyl-N-cyclohexyl) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide,

3- {2,2-bis [4- (N-ethyl-
N-cyclohexyl) aminophenyl] ethylene-1-
Il} -6-diethylaminophthalide, 3- {2,2-
Bis [4- (N-ethyl-N-p-toluidino) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-N
-P-toluidino) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-N-i-butyl) aminophenyl] ethylene-1- Il} -6-dimethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-Ni-
Butyl) aminophenyl] ethylene-1-yl} -6-
Diethylaminophthalide, 3- {2,2-bis [4-
(N-Ethyl-N-n-propyl) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3
-{2,2-bis [4- (N-ethyl-N-n-propyl) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- [2,2-bis (4-di-) n
-Butylaminophenyl) ethylene-1-yl] -6-
Dimethylaminophthalide, 3- [2,2-bis (4-di-n-butylaminophenyl) ethylene-1-yl]-
6-diethylaminophthalide,

3- {2,2-bis [4- (N-ethyl-
N-n-hexyl) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-N-n-hexyl) aminophenyl] ethylene- 1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-N-ethoxypropyl) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3 -{2,2-bis [4- (N-ethyl-N-ethoxypropyl) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N- Methyl-N
-Ethoxypropyl) aminophenyl] ethylene-1-
Il} -6-dimethylaminophthalide, 3- {2,2-
Bis [4- (N-methyl-N-ethoxypropyl) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-
N-cyclopentyl) aminophenyl] ethylene-1-
Il} -6-dimethylaminophthalide, 3- {2,2-
Bis [4- (N-ethyl-N-cyclopentyl) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide,

3- [2,2-bis (4-pyrrolidinophenyl) ethylene-1-yl] -6-dimethylaminophthalide, 3- [2,2-bis (4-pyrrolidinophenyl)
Ethylene-1-yl] -6-diethylaminophthalide,
3- [2,2-bis (4-piperidinophenyl) ethylene-1-yl] -6-dimethylaminophthalide, 3-
[2,2-bis (4-piperidinophenyl) ethylene-
1-yl] -6-diethylaminophthalide, 3- [1,
1-bis (4-dimethylaminophenyl) -1-propen-2-yl] -6-dimethylaminophthalide, 3-
[2,2-bis (4-dimethylaminophenyl) ethylene-1-yl] -6-pyrrolidinophthalide, 3- [2,
2-bis (4-pyrrolidinophenyl) ethylene-1-yl] -6-pyrrolidinophthalide, 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1-yl]
Phthalide, 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1-yl] -6-chlorophthalide,
3- [2,2-bis (4-pyrrolidinophenyl) ethylene-1-yl] -5-chlorophthalide, 3- [2,2-
Bis (4-diethylaminophenyl) ethylene-1-yl] -4,5,6,7-tetrachlorophthalide, 3-
[2,2-bis (4-diethylaminophenyl) ethylene-1-yl] -4,5,6,7-tetrabromophthalide, 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1 -Yl] -5-methoxyphthalide, 3
-[2,2-bis (4-dimethylaminophenyl) ethylene-1-yl] -5-nitrophthalide, 3- [2,2
-Bis (2-methoxy-4-dimethylaminophenyl)
Ethylene-1-yl] -6-dimethylaminophthalide,
3- [2,2-bis (2-methyl-4-diethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide, 3- [2,2-bis (2-chloro-4-diethylaminophenyl) Ethylene-1-yl] -6-dimethylaminophthalide, 3- [2,2-bis (N-ethyl-N-benzylaminophenyl) ethylene-1-yl]
Examples thereof include phthalide and 3- [2,2-bis (N-ethyl-N-phenylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide.

The above-mentioned phthalide derivative used in the present invention is a triarylmethane lactone, if necessary,
Spiropyrans, fluorans, diphenylmethanes,
In combination with ordinary basic color formers such as azines and azaphthalides, alkylated naphthalene, alkylated diphenyl,
Synthetic oils such as alkylated diphenylmethane and alkylated terphenyl, vegetable oils such as cotton oil and castor oil, animal oils, mineral oils, and the like, dissolved in a suitable solvent, interfacial polymerization method, in-situ method And the like, a synthetic polymer-based wall film material is included in the microcapsules. Then, by appropriately adjusting the encapsulation conditions at that time, a capsule having the above-mentioned specific average particle size and average film thickness is prepared.
Examples of the resin forming the wall film include aminoaldehyde resin, polyurea resin, polyurethane resin, polyamide resin and the like.

Capsules having a wall membrane of aminoaldehyde resin can be prepared, for example, from at least one amine such as urea, thiourea, alkylurea, ethyleneurea, acetoguanamine, benzoguanamine, melamine, guanidine, biuret and cyanamide, and formaldehyde, It is produced by an in-situ polymerization method using at least one aldehyde such as acetaldehyde, paraformaldehyde, hexamethylenetetramine, glutaraldehyde, glyoxal, and furfural, or an initial condensation product obtained by condensing them.

Polyurethane resin and polyurea resin wall membrane capsules use, for example, polyvalent isocyanate and water, polyvalent isocyanate and polyol, isothiocyanate and water, isothiocyanate and polyol, polyvalent isocyanate and polyamine, isothiocyanate and polyamine, etc. Manufactured by the interfacial polymerization method. The polyamide resin wall membrane capsule is manufactured by an interfacial polymerization method of acid chloride and amine. Polyurethane resin and polyurea resin wall membrane capsules are particularly preferable.

Capsules thus prepared which contain a specific color-forming agent and have a specific average particle size and average film thickness are protective materials such as starch granules and cellulose powders according to a conventional method,
A latex, a water-soluble binder and the like are appropriately mixed to prepare a capsule coating solution, which is used for producing upper paper, middle paper, self-coloring type pressure sensitive recording paper and the like. The coloring agent-containing layer used in combination with the microcapsule-coated surface of the upper or middle paper particularly contains a salicylic acid derivative zinc salt. Therefore, in the present invention, for example, in the case of top paper,
It is used in combination with a lower sheet or a middle sheet having a coloring layer containing a salicylic acid derivative zinc salt.

In the pressure-sensitive copying paper of the present invention, a salicylic acid derivative zinc salt is selectively used as a color developing agent. Specific examples of such a color developing agent include salicylic acid, 3-isopropylsalicylic acid, and the like. 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3-methyl-5
-(Α-Methylbenzyl) salicylic acid, 3-methyl-5
-(Α, α-Dimethylbenzyl) salicylic acid, 3,5-
Di-sec-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-di-tert-butyl-6-methylsalicylic acid, 3-tert-butyl-5-phenylsalicylic acid, 3,5-di- tert-amyl salicylic acid, 3,5-dicyclohexyl salicylic acid, 3-cyclohexyl-5-
(Α-Methylbenzyl) salicylic acid, 3-dodecylsalicylic acid, 3-methyl-5-dodecylsalicylic acid, 3-dodecyl-5-methylsalicylic acid, 3-dodecyl-6-methylsalicylic acid, 3-phenyl-5- (α-methyl Benzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, 3- (α-methylbenzyl) salicylic acid, 3- (α-methylbenzyl) -5-methylsalicylic acid, 3- (α-methyl) Benzyl) -5-phenylsalicylic acid, 3 (α, 4-dimethylbenzyl)-
5-methylsalicylic acid, 3,5-di (α, 4-dimethylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) -5-methylsalicylic acid, 3- (α, α-dimethylbenzyl) -6-methyl Salicylic acid, 3,5-di (α,
α-Dimethylbenzyl) salicylic acid, 3,5-di (α-
Methylbenzyl) salicylic acid, 3- (α-methylbenzyl) -5- (α, α-dimethylbenzyl) salicylic acid,
3- (α-methylbenzyl) -5-bromosalicylic acid,
3- (α-methylbenzyl) -4-methylsalicylic acid,
3- (α-methylbenzyl) -6-methylsalicylic acid,
3-nonylsalicylic acid, 3-nonyl-5-methylsalicylic acid, 3-nonyl-6-methylsalicylic acid, 3-nonyl-5-phenylsalicylic acid, 3-methyl-5-nonylsalicylic acid, 3,5-dinonylsalicylic acid, 5 Examples thereof include zinc salts such as-(4-mesitylmethylbenzyl) salicylic acid, pinened salicylic acid, and benzylated styrenated salicylic acid.

The developer coating liquid contains the above salicylic acid derivative zinc salt, if necessary, calcium carbonate, magnesium carbonate, kaolin, aluminum hydroxide, titanium oxide,
It is prepared by a method of dispersing in water with an inorganic pigment such as zinc oxide or activated clay, a binder and the like. Examples of binders include starches, celluloses, proteins, gum arabic, polyvinyl alcohol, and styrene.
A maleic anhydride copolymer salt, a vinyl acetate-maleic anhydride copolymer salt, a polyacrylic acid salt, a styrene-butadiene copolymer emulsion or the like is appropriately selected and used.

The method of applying the coating liquid is not particularly limited, and for example, an on-machine or off-machine coater equipped with a suitable coating device such as an air knife coater, roll coater, blade coater, rod coater, curtain coater, etc. Of about ² to 10 g / m ² is applied and dried on the support.

Regarding the pressure-sensitive copying paper, for example, US Pat. Nos. 2,505,470, 2,505,471, and 2,505,489 are used.
No., No. 2,548,366, No. 2,712,507, No. 2,730,456
No., No. 2,730,457, No. 3,418,250, No. 3,924,027
No. 4,010,038, etc., there are various forms, and the present invention can be applied to these various forms of pressure-sensitive copying paper. The support is not limited to paper, but synthetic paper,
A film or the like can also be used.

[0025]

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

Example 1 [Preparation of color developer dispersion] 100 g of 3,5-di (α-methylbenzyl) salicylate zinc was added to 100 g of toluene to give 70 parts.
A toluene solution was prepared by mixing and dissolving at ° C. Separately, 6 g of polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98%
Was added to a beaker made of stainless steel having an internal volume of 1000 cc, and the above toluene solution was added thereto while stirring a TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.) at 3000 rpm.

When the addition of the toluene solution was completed, the number of revolutions was increased to 10,000 rpm and the mixture was stirred for 2 minutes, and then the dispersion was mixed with a stirrer, a thermometer and a distillation port to obtain an internal volume of 1000.
Transferred to a cc hard glass three neck flask. The flask was heated while slowly rotating the stirrer so that toluene and water were distilled from the distillation port. When this operation was continued at 100 ° C. for about 1 hour, the dispersion liquid contained almost no toluene. This was cooled to obtain an aqueous dispersion containing about 33% of the color developer. The average particle size of the resulting developer dispersed particles is 1.
It was 0 micron.

Next, this water dispersion liquid was applied to a sand grinder (Model IOL, OSG-8G, manufactured by Igarashi Kikai Co., Ltd.) at 2 minutes per minute.
The dispersion was treated under the conditions of Kg to prepare a developer dispersion having an average particle size of 0.97 micron.

[Preparation of color developer coating liquid] 15 parts of 33% color developer dispersion obtained by the above treatment, calcium carbonate 70
Parts, 10 parts of zinc oxide and 100 parts of water are mixed and dispersed, and as a binder, 100 parts of a 10% aqueous solution of polyvinyl alcohol and 50% of 50% carboxy-modified SBR latex (trade name: SN-307, manufactured by Sumitomo Nogatak) 20 parts. , 200 parts of water were mixed and dispersed to prepare a developer coating liquid.

[Production of lower paper] 40 g of the above-mentioned color developer coating liquid
/ M ² of the base paper was coated and dried with an air knife coater so that the dry weight was 6 g / m ^2, and calendered to prepare a base paper for pressure-sensitive copying paper.

[Preparation of microcapsule dispersion] To a stirring and mixing container equipped with a heating device, 150 parts of a 3% aqueous solution of polyvinyl alcohol (trade name: PVA-117, manufactured by Kuraray Co., Ltd.) was added to prepare an aqueous medium for capsule preparation. And Separately, 100 parts of alkyldiphenylethane was used as 3- [2,
2-bis (4-diethylaminophenyl) ethylene-1
-Yl] -6-dimethylaminophthalide 8 parts were dissolved,
Furthermore, polymethylene polyphenyl isocyanate (trade name: Millionate MR400, manufactured by Nippon Polyurethane Industry Co., Ltd.) 5
Part and 2 parts of 2-isocyanatoethyl-2,6-diisocyanatohexanoate (trade name: T-100, manufactured by Toray Industries, Inc.) are used as a capsule core substance to obtain a solution of the above-mentioned aqueous medium for capsule preparation. 10 minutes per minute using TK homomixer
The emulsion was dispersed at 000 rpm for 1 minute.

Diethylenetriamine 1 was added to this emulsion dispersion.
Parts and after stirring for 30 minutes at room temperature, the system temperature was adjusted to 7
The temperature was raised to 0 ° C. and the reaction was continued for 3 hours while continuing stirring.
When the temperature is lowered to room temperature and the average particle size is 6.0 microns,
Polyurea resin with an average wall thickness of 0.21 micron /
A polyurethane resin wall membrane capsule was prepared.

[Preparation of microcapsule coating solution] To 100 parts (solid content) of the above-mentioned microcapsule dispersion, 80 parts of wheat starch and 15 parts of carboxy-modified SBR latex (solid content) were added to give a solid content concentration of 20%. Thus prepared, a microcapsule coating liquid was obtained.

[Production of Medium Paper] The microcapsule coating solution is applied to the opposite surface of the lower paper with an air knife coater so as to have a dry weight of 4 g / m ² and dried to prepare an intermediate paper for pressure-sensitive copying paper. did.

Example 2 Example 3 was repeated except that 3- [2,2-bis (4-dipyrrolidinophenyl) ethylene-1-yl] -6-diethylaminophthalide was used as the color former. A polyurea resin / polyurethane resin wall film capsule having the same average particle diameter and film thickness was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 1 below.

Example 3 In the same manner as in Example 1 except that 3- [2,2-bis (4-dimethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide was used as a color former. A polyurea resin / polyurethane resin wall film capsule having the same average particle diameter and film thickness was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 1 below.

Example 4 3- [2,2-bis (4-dimethylamino-2-methoxyphenyl) ethylene-1-yl] -6-as a color former
A polyurea resin / polyurethane resin wall film capsule having the same average particle size and film thickness was prepared in the same manner as in Example 1 except that dimethylaminophthalide was used. Created medium paper for paper.

Example 5 4 parts of 3- [2,2-bis (4-diethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide and 3- (N-ethyl-N-isoamyl) as color formers An average particle size of 6.1 was obtained in the same manner as in Example 1 except that 4 parts of amino-6-methyl-7-anilinofluorane was used.
A microurea polyurea resin / polyurethane resin wall membrane capsule with an average wall membrane thickness of 0.23 microns was prepared,
Thereafter, in the same manner as in Example 1, an intermediate paper for pressure-sensitive copying paper was prepared.

Example 6 An intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 except that zinc 3,5-dinonylsalicylate was used as the developer.

Example 7 In the microcapsule preparation step, the emulsification time of the capsule core substance and the aqueous medium for capsule preparation was from 1 minute to 30 minutes.
A polyurea resin / polyurethane resin wall film capsule having an average particle size of 9.8 microns and an average wall film thickness of 0.30 micron was prepared in the same manner as in Example 3 except that the time was changed. In the same manner as in Example 3, a pressure sensitive copying paper inner sheet was prepared.

Example 8 As in Example 3, except that the polymethylene polyphenyl isocyanate was reduced from 5 parts to 3 parts during the preparation of the microcapsule dispersion, the average particle size was 5.3 microns and the wall A polyurea resin / polyurethane resin wall membrane capsule having an average membrane thickness of 0.17 micron was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 below.

Example 9 In a stirring and mixing vessel equipped with a heating device, 100 parts of a 5% aqueous solution of α-methylstyrene-maleic anhydride copolymer was added and the pH of the system was adjusted to 4.5 to produce capsules. Used as an aqueous medium. Separately, in 100 parts of alkyldiphenylethane, 4 parts of 3- [2,2-bis (4-diethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide and 3- (N-ethyl-N-) were used as color formers. Isoamyl) amino-6-methyl-7-anilinofluorane (4 parts) was dissolved, and this was used as a capsule core substance in the above-mentioned aqueous medium for capsule production using a TK homomixer at a rate of 10,000 per minute.
The emulsion was dispersed for 1 minute by rotation.

To this emulsified dispersion was added 50 parts of a 30% aqueous solution of a commercially available melamine-formaldehyde initial condensate, and
After reacting at 0 ° C. for 2 hours while continuing stirring, the temperature was lowered to room temperature to obtain a melamine-formaldehyde resin wall membrane capsule having an average particle diameter of 6.0 microns and an average wall membrane thickness of 0.18 microns. Prepared. An intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 except that this capsule dispersion liquid was used.

Comparative Example 1 100 parts of activated clay as a developer was dispersed in 200 parts of water, and 50% of carboxy-modified SBR latex 30 was further added.
Part of the base paper of 40 g / m ² on one side with an air knife coater so that the dry weight is 6 g / m ^2, and then it is calendered to obtain a base paper for pressure-sensitive copying paper. Created. An intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 except that this lower paper was used.

Comparative Example 2 Average particle size was the same as in Example 1 except that 8 parts of 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane was used as the color former. A polyurea resin / polyurethane resin wall film capsule having a diameter of 5.9 μm and an average wall film thickness of 0.20 μm was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 1 below. ..

Comparative Example 3 3,3-bis (4-diethylamino-2-) as a color former
Ethoxyphenyl) -4-azaphthalide 4 parts and 3- (N
-Ethyl-N-isoamyl) amino-6-methyl-7-
A polyurea resin / polyurethane resin wall film capsule having an average particle size of 6.0 microns and an average wall film thickness of 0.20 micron, in the same manner as in Example 1 except that 4 parts of anilinofluoran was used. Was prepared and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 1 below.

Comparative Example 4 In the microcapsule preparation step, the emulsification time of the capsule core substance and the aqueous medium for capsule preparation was from 1 minute to 15 minutes.
A polyurea resin / polyurethane resin wall membrane capsule having an average particle size of 13.8 microns and an average wall membrane thickness of 0.41 microns was prepared in the same manner as in Example 3 except that the time was changed to 2 seconds. In the same manner as in Example 3, a pressure sensitive copying paper inner sheet was prepared.

Comparative Example 5 The procedure of Example 3 was repeated except that the amount of polymethylene polyphenyl isocyanate was reduced from 5 parts to 1 part during the preparation of the microcapsule dispersion, and the average particle size was 4.8 μm and the wall A polyurea resin / polyurethane resin wall membrane capsule having an average membrane thickness of 0.07 micron was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 below.

Comparative Example 6 100 parts of alkyldiphenylethane was added with 3-
[2,2-bis (4-diethylaminophenyl) ethylene-1-yl] -6-dimethylaminophthalide 4 parts and 3
4 parts of-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane were dissolved. Separately, 25 parts of pigskin gelatin having an isoelectric point of 8 as an encapsulating agent and 25 parts of arabic rubber were dissolved in 300 parts of warm water at 50 ° C.
The above-mentioned oil containing a color-forming agent was added to this gelatin-arabic gum mixed solution while stirring and emulsified and dispersed.

This emulsion was further diluted with 1000 parts of warm water, and acetic acid was gradually added dropwise to adjust the pH of the solution to 4 to 4.3. The encapsulating agent was deposited around the oil droplets and the sol was formed. A capsule was produced. After the capsule was cooled to about 10 ° C. and gelled, 10 parts of a 25% aqueous solution of glutaraldehyde was added to cure the capsule, and the average particle diameter was 6.1 μm and the average thickness of the wall film was 0.1 μm. A 38-micron gelatin-based wall membrane capsule was prepared, and an intermediate paper for pressure-sensitive copying paper was prepared in the same manner as in Example 3 below.

[Measurement of Capsule Particle Diameter] The average particle diameter of the capsules prepared in Examples and Comparative Examples was measured by a particle size measuring device (Coulter Counter, manufactured by Nikkaki Co., Ltd.), and the results are shown in the table.

[Measurement of Capsule Film Thickness] The average film thickness of the capsules prepared in Examples and Comparative Examples was measured by a tomographic electron micrograph (T-300, manufactured by JEOL Ltd.) of a medium paper for pressure-sensitive copying paper. The results are shown in the table.

[Quality comparison test]. OCR Readability A voucher was prepared by using four sheets of each of the pressure-sensitive copying paper medium sheets prepared in the examples and comparative examples as a set, and after printing with a dot printer, the fourth color image was formed on the OCR device (V-3050, (Made by Toshiba)
Then, the reading was performed at the reading wavelengths of 660 nm and 740 nm. The slips of 1000 sets were read, and the percentage of those that could be read correctly was listed in%.

.. Color fog test A slip was prepared by using 4 sheets of each of the pressure-sensitive copying papers prepared in Examples and Comparative Examples as one set, and 1000 sets of this slip were left for 7 days at 50 ° C., and then a dot printer was used. After printing, an OCR readability test was conducted in the same manner as above, and the results are shown in the table.

.. Contact Stain Resistance Test After stacking so that the capsule-coated surface and the developer-coated surface of the medium paper for pressure-sensitive copying paper prepared in Examples and Comparative Examples face each other, and after applying a load of 20 kg / cm ² for 1 minute. , The degree of color stain on the surface coated with the color developer is visually judged according to the following evaluation criteria,
The results are shown in the table. (Evaluation criteria) ○: Almost no stain. X: Remarkably soiled.

.. Rubbing and Staining Test The medium pressure-sensitive copy paper prepared in Examples and Comparative Examples were overlaid so that the capsule-coated surface and the developer-coated surface faced each other 5 times with a load of 4 kg / cm ² applied. After rubbing, the degree of color stain on the surface coated with the color developer was visually determined according to the following evaluation criteria, and the results are shown in the table. (Evaluation criteria)
◯: Almost no dirt. X: Remarkably soiled.

[0057]

[Table 1]

[0058]

As is clear from the results shown in the table, the pressure-sensitive copying papers obtained in the examples of the present invention are 600-80.
It was an excellent pressure-sensitive copying paper which had excellent readability for an OCR device having a reading wavelength in the near-infrared region of 0 nm and had little color density change or color fog.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

3- {2,2-bis [4- (N-ethyl-
N-cyclohexyl) aminophenyl] ethylene-1-
Il} -6-diethylaminophthalide, 3- {2,2-
Bis [4- (N-ethyl-N-p-toluidino ) phenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-Np] −
Toluidino ) phenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N
-Ethyl-N-i-butyl) aminophenyl] ethylene-1-yl} -6-dimethylaminophthalide, 3-
{2,2-bis [4- (N-ethyl-N-i-butyl)
Aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- {2,2-bis [4- (N-ethyl-Nn-propyl) aminophenyl] ethylene-1
-Yl} -6-dimethylaminophthalide, 3- {2,2
-Bis [4- (N-ethyl-N-n-propyl) aminophenyl] ethylene-1-yl} -6-diethylaminophthalide, 3- [2,2-bis (4-di-n-butylaminophenyl) ) Ethylene-1-yl] -6-dimethylaminophthalide, 3- [2,2-bis (4-di-n-butylaminophenyl) ethylene-1-yl] -6-diethylaminophthalide,

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8305-2H B41M 5/12 112

Claims (1)

[Claims] 1. An electron donative color former and an electron acceptor color developer
It is a pressure-sensitive copying paper utilizing a color-developing reaction and has an electron donating property.
As a color former, a phthalide represented by the following general formula [Chemical formula 1]
Contains a derivative and the coloring agent is a synthetic polymer microphone
It is encapsulated in capsules and has an average particle size of 3 to
10 micron with an average film thickness of 0.1-0.6 micron
And a salicylic acid derivative as an electron-accepting developer
A pressure-sensitive copying paper characterized by using a zinc salt. [Chemical 1][In the formula, R₁Is a halogen atom, C₁~ C_FourThe alkyl
Base, C₁~ C_FourAlkoxy group, nitro group, amino group,
Represents a substituted amino group or an alicyclic amino group, R₂Is hydrogen
Child or C₁~ C_FourAlkyl group of R₃~ R₆Are each
Hydrogen atom, C₁~ C ₆Alkyl group of C₂~ C₆The al
Coxyalkyl group, C₆~ C_TenAryl group of C₇~ C
_TenAralkyl group of C_Five~ C₈The cycloalkyl group of
And R₃And R _Four, And R_FiveAnd R₆Are adjacent to each other
You may form a ring with an elementary atom. X and Y are hydrogen sources
Child, C₁~ C_FourAlkyl group of C₁~ C_FourThe alkoxy
Represents a group or a halogen atom. n represents an integer of 0 to 4
You ]