JPH0532041A - Pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To obtain microcapsule paper wherein the characters of all of a plurality of microcapsule papers can be read by an optical character reading device, by adding a solution of a specific divinyl phthalide compound in a hydrophobic liquid to microcapsules set to a specific range in particle size distribution as a core substance. CONSTITUTION:A solution of a compound represented by formula I is added to the microcapsules of a pressure-sensitive recording sheet. In the formula I, R1 and R2 are a 8 or less C alkyl group, a 5-7C cycloalkyl group or a benzyl or phenyl group which may have a halogen atom or a 4 or less C alkyl group as a substituent, X is a hydrogen atom, a halogen atom, a 8 or less C alkyl group, an alkoxy group or -NR3R4Y1-3 are a hydrogen atom, a halogen atom, a 8 or less C alkyl group or an alkoxy group and Z is a hydrogen atom, a chlorine atom or a bromine atom. Further, the particle size distribution of the microcapsules is set to the range of 4.0mum<= D50<=10.0mum an D90/D10<=2.0 (D: cumulated 10 partical size).

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 and the like. So far, in the case of pressure-sensitive recording sheets, optical character reading has been performed only on characters written on top paper, and not on characters formed by destroying 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, it is difficult to read depending on the shape of the recorded characters and the like, and in particular, when the number of sheets increases, it may become impossible to read the recorded characters on the fourth and fifth sheets.

Therefore, an object of the present invention is to read microcapsule paper using a divinyl compound (divinylphthalide compound) on all the characters of a large number of developer sheets with an optical character reader using near infrared rays. 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 for obtaining a color image by the reaction of an almost colorless electron-donating dye and an electron-accepting color developer, and a general formula ( A pressure-sensitive recording sheet comprising a solution of a divinylphthalide compound represented by 1) as a core substance and having a microcapsule particle size distribution within the following range.

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.

Particle size distribution 4.0 μ ≦ D ₅₀ ≦ 10.0 μ D ₉₀ / D ₁₀ ≦ 2.0 In the above formula, D ₁₀ , D ₅₀ and D ₉₀ are percent particle sizes determined from the cumulative volume distribution.

D ₁₀ -cumulative 10 percent particle diameter D ₅₀ -cumulative 50 percent particle diameter D ₉₀ -cumulative 90 percent particle diameter In the present invention, it is preferable that the walls of the microcapsules are made of polyurethane resin.

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.

[0015]

[Chemical 3]

The divinylphthalide compound represented by the general formula (1) used in the present invention is described in the above-mentioned 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.

[0017]

[Chemical 4]

[0018]

[Chemical 5]

[0019]

[Chemical 6]

[0020]

[Chemical 7]

[0021]

[Chemical 8]

[0022]

[Chemical 9]

[0023]

[Chemical 10]

[0024]

[Chemical 11]

[0025]

[Chemical formula 12]

In the present invention, the particle size distribution of the microcapsules is within the following range. 4.0 μ ≦ D ₅₀ ≦ 10.0 μ D ₉₀ / D ₁₀ ≦ 2.0 The above-mentioned D ₅₀ represents a median diameter, but if D ₅₀ is less than 4.0 μ, sufficient color developability cannot be obtained. If it is larger than 0.0 μm, sufficient pressure resistance cannot be obtained, and the shape of the obtained image is not suitable for OCR reading. The preferable range of D ₅₀ is 6.5 to 8.5.

D ₉₀ / D ₁₀ represents how sharp the particle size distribution is, and the smaller the value of D ₉₀ / D ₁₀ , the sharper the particle distribution. The present invention has D ₅₀
Is in the above range and D ₉₀ / D ₁₀ is 2 or less, the recorded images (characters) on all sheets have a shape that can be OCR-readable even when recorded on a plurality of pressure-sensitive recording sheets. I found that.

Microcapsules having such a particle size distribution can be obtained by emulsification using a shear emulsification type double cylinder type emulsifying machine (cylindrical mill) having uniform gaps.

The polyurethane urea resin wall microcapsules preferably used in the present invention are prepared by emulsifying and dispersing in a hydrophilic liquid a solution prepared by dissolving a polyvalent isocyanate, a polyvalent hydroxy compound and a color former in a hydrophobic liquid. It is obtained by adding a polyvalent amine to the dispersion and coating the hydrophobic droplets with a polyurethane urea resin. Both the polyvalent hydroxy compound and the polyvalent amine may be used, or only one of them may be used.

Regarding the polyvalent isocyanate and polyvalent hydroxy compound used for the above purpose, JP-A-2-160
It is described in Japanese Patent No. 579. In addition, in the present invention, when it is desired to read the pressure-sensitive recording sheet with an optical character reader and to visually read the obtained record, 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.

[0032]

[Chemical 13]

(In the formula, 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, encapsulated and applied to a support. As the hydrophobic liquid (solvent), natural or synthetic oil 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 a 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, attabargite, zeolite, bentonite, clay substances such as kaolin, metal salts of aromatic carboxylic acid, and Examples include phenolic resins.

These 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 color developer sheet] (Preparation of dispersion) 15 parts of zinc 3,5-di-α-methylbenzylsalicylate, 120 parts of calcium carbonate, 30 parts of activated clay, 20 parts of zinc oxide, 1 part of sodium hensametaphosphate Using 200 parts of water, a sand grinder was used to uniformly disperse the particles so that the average particle diameter was 3 μm to obtain a dispersion liquid (A).

(Preparation of coating liquid) 10 parts of 10% PVA-203 (manufactured by Kuraray) aqueous solution and 10 parts of 400 parts of dispersion liquid (A) were prepared.
% PVA-117 (manufactured by Kuraray) and 100 parts of carboxy-modified SBR latex (SN-307, manufactured by Sumitomo Nogataff) (as solid content) were added, and water was prepared so that the solid content concentration was 20%. A coating liquid was obtained. [Application of color developer sheet] This coating solution was applied to an original paper of 50 g / m ^{2 with} an air knife coater so that a solid content of 5.0 g / m ² was applied and dried to obtain a color developer sheet. ..

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

[0041]

【Example】

Example 1 As a color former, 3,3-bis [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide 120 was used.
g, 2-anilino-3-methyl-6-N-ethyl-N-
100 g of isopentylaminofluorane, 40 g of 2-benzylamino-6-diethylaminofluorane and 20 g of bisindoylphthalide having the following structural formula were dissolved in 2000 g of 1-phenoxy-1-xylylethane.

[0042]

[Chemical 14]

Polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Company, trade name "Millionate MR200") was added to this oily liquid as a polyvalent isocyanate.
Biuret body of 60 g and hexamethylene diisocyanate (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name "Sumijour N3200") and alkylene oxide adduct of ethylenediamine as an alkylene oxide adduct of amine (additional number of butylene oxide to ethylenediamine: 16. 8 mol, molecular weight 1267) 64 g
Was dissolved to prepare a primary solution.

Next, 200 g of polyvinyl alcohol and 100 g of carboxymethyl cellulose were dissolved in 2800 g of water to prepare a secondary solution. While stirring the secondary solution at 800 rpm with a propeller blade stirrer having a blade diameter of 70 mm, the above primary solution was poured to form an oil-in-water emulsion to prepare a preliminary emulsion.

Next, this pre-emulsion was flown with a cylindrical mill at a flow rate of 0.3 kg / min and a clearance of 300.
The emulsion was obtained by processing under conditions of μ, rotation speed = 1300 rpm, and number of passes = 1. Next, 2000 g of water at 20 ° C. was added to this emulsion, the system temperature was gradually raised to 65 ° C., and this temperature was maintained for 90 minutes to obtain a capsule liquid.

When the particle size distribution of this capsule was measured with a Coulter Counter TA-II type, D ₅₀ = 6.6.
μ, D ₉₀ / D ₁₀ = 1.70. In the thus obtained capsule liquid, 2000 g of a 15% aqueous solution of polyvinyl alcohol, 600 g of carboxy-modified SBR latex in solid content, starch particles (average particle size 15 μ) 1200
g was added.

Then, water is added to adjust the solid content concentration to 20%.
And the coating solution was prepared. This coating solution was applied on 40 g / m ² base paper with an air knife coating solution so as to have a dry weight of 4.0 g / m ^2, and dried to obtain a microcapsule sheet. Example 2 In Example 1, the conditions for treating the preliminary emulsion with a cylindrical mill were as follows: flow rate = 0.4 kg / min, clearance = 500 μ, rotation speed = 1200 rpm, number of passes =
A microcapsule sheet was obtained in the same manner as in Example 1 except that the conditions were changed once.

The particle size distribution of this capsule was measured with a Coulter Counter TA-II type, and D ₅₀ = 8.0.
μ, D ₉₀ / D ₁₀ = 1.74. Comparative Example 1 While the secondary solution of Example 1 was stirred at 2000 rpm with a dissolver having a blade diameter of 100 mm, the primary solution of Example 1 was poured and stirring was continued for 1 minute to form an oil-in-water emulsion. Next, 2000 g of water at 20 ° C. was added to this emulsion, the temperature of the system was gradually raised to 65 ° C., and this temperature was maintained for 90 minutes to obtain a capsule liquid.

When the particle size distribution of this capsule was measured with a Coulter counter TA-II type, D ₅₀ = 6.7.
μ, D ₉₀ / D ₁₀ = 3.0. 2000 g of a 15% aqueous solution of polyvinyl alcohol, 600 g of carboxy-modified SBR latex as a solid content, and 1200 g of starch particles (average particle size 15 μ) were added to the thus obtained capsule liquid.
Was added.

Next, water is added to adjust the solid content concentration to 20%.
And the coating solution was prepared. This coating solution was applied to 40 g / m ² base paper so as to have a dry weight of 4.0 g / m ² by an air knife coating machine and dried to obtain a microcapsule sheet. Comparative Example 2 While stirring the secondary solution of Example 1 at 1500 rpm with a dissolver having a blade diameter of 100 mm, the primary solution of Example 1 was poured and stirring was continued for 1 minute to form an oil-in-water emulsion. Next, 2000 g of water at 20 ° C. was added to this emulsion, the temperature of the system was gradually raised to 65 ° C., and this temperature was maintained for 90 minutes to obtain a capsule liquid.

When the particle size distribution of this capsule was measured with a Coulter Counter TA-II type, D ₅₀ = 7.9.
μ, D ₉₀ / D ₁₀ = 4.3. 2000 g of a 15% aqueous solution of polyvinyl alcohol, 600 g of carboxy-modified SBR latex as a solid content, and 1200 g of starch particles (average particle size 15 μ) were added to the thus obtained capsule liquid.
Was added.

Then, water is added to adjust the solid content concentration to 20%.
And the coating solution was prepared. This coating solution was applied to 40 g / m ² base paper so as to have a dry weight of 4.0 g / m ² by an air knife coating machine and dried to obtain a microcapsule sheet. Example 3 As a color former, 3,3-bis [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide 100 was used.
g, crystal violet lactone 50 g, benzoyl leuco methylene blue 10 g, 3- [4- (dimethylamino) -2-ethoxyphenyl] -3- (2-methyl-1-ethyl-3-indolyl) -4-azaphthalide 4
0 g and 2-anilino-3-methyl-6-N-ethyl-
80 g of N-isopentylaminofluorane was dissolved in 2000 g of diisopropylnaphthalene.

200 g of ethyl acetate was added to this oily liquid,
Tolylene diisocyanate 3 as polyvalent isocyanate
320 g of mol / trimethylolpropane 1 mol adduct (manufactured by Dainippon Ink and Co., Ltd., trade name "Bernock D750")
Butylene oxide adduct of ethylenediamine as alkylene oxide adduct of amine and amine (the number of moles of butylene oxide added to ethylenediamine is 12 mol,
A primary solution was prepared by dissolving 80 g of a molecular weight of 924).

Next, 200 g of polyvinyl alcohol and 40 g of gum arabic were dissolved in 2800 g of water to prepare a secondary solution. While stirring the secondary solution at 800 rpm with a propeller blade stirrer having a blade diameter of 70 mm, the above primary solution was poured to form an oil-in-water emulsion to prepare a preliminary emulsion.

Next, this preliminary emulsified liquid was passed through a cylindrical mill (made by Tokushu Kika Kogyo Co., Ltd.) at a flow rate of 0.3 kg / min.
An emulsion was obtained by processing under the conditions of clearance = 300 μ, rotation speed = 1300 rpm, and number of passes = 1. Next, 2000 g of water at 20 ° C. and 7.2 g of diethylenetriamine as a polyvalent amine were added to this emulsion, and the mixture was stirred at room temperature for 10 minutes.
After stirring for 1 minute, the system temperature was gradually raised to 65 ° C. and kept at this temperature for 60 minutes.

When the particle size distribution of this capsule was measured with a Coulter Counter TA-II type, D ₅₀ = 7.1.
μ, D ₉₀ / D ₁₀ = 1.71. In the thus obtained capsule liquid, 1600 g of a 15% aqueous solution of polyvinyl alcohol, 400 g of carboxy-modified SBR latex in solid content, and starch particles (average particle size 15 μm) 1000
g was added.

Next, water is added to adjust the solid content concentration to 20%.
And the coating solution was prepared. This coating solution was applied to 40 g / m ² base paper so as to have a dry weight of 4.0 g / m ² by an air knife coating machine and dried to obtain a microcapsule sheet. Comparative Example 3 While the secondary solution of Example 3 was stirred at 2000 rpm with a dissolver having a blade diameter of 100 mm, the primary solution of Example 3 was poured and stirring was continued for 1 minute to form an oil-in-water emulsion.

Next, 2000 ml of water at 20 ° C. was added to this emulsion.
g and 7.2 g of diethylenetriamine as a polyvalent amine were added, and the mixture was stirred at room temperature for 10 minutes, then the temperature of the system was gradually raised to 65 ° C. and kept at this temperature for 60 minutes.

When the particle size distribution of this capsule was measured with a Coulter Counter TA-II type, D ₅₀ = 7.1.
μ, D ₉₀ / D ₁₀ = 3.3. In the thus obtained capsule liquid, 1600 g of a 15% aqueous solution of polyvinyl alcohol, 400 g of carboxy-modified SBR latex in solid content, and 1000 g of starch particles (average particle size 15 μ)
Was added.

Then, water is added to adjust the solid content concentration to 20%.
And the coating solution was prepared. This coating solution was applied to 40 g / m ² base paper so as to have a dry weight of 4.0 g / m ² by an air knife coating machine and dried to obtain a microcapsule sheet.

An evaluation test as a pressure-sensitive recording sheet was conducted by combining each of the above microcapsule sheets and a color developer sheet, and the results are shown in Table 1. The evaluation test was performed by the following method.

(1) Printing for OCR reading Three sheets of base paper of 50 g / m ² are covered with a color developer-containing high-capsule sheet underneath, and a developer sheet is overlaid thereunder, and a set of five letters and letters of the OCR-B font. Was printed.

(2) Unevenness of Line Edges The unevenness of the line edges of the printed sample of (1) was checked using a COL gauge and a magnifying glass to see if it was within the allowable range. (JIS
(X9004) (3) OCR reading test (1) The OCR reading device (Toshiba V-3
010, using a blue fluorescent lamp).

[0064]

[Table 1]

[0065]

As is apparent from the above results, the pressure-sensitive recording sheet according to the present invention is capable of OCR reading even when printing the bottom sheet of a set of five sheets.

Claims (1)

Claim: What is claimed is: 1. A pressure-sensitive recording sheet which obtains a color image by the reaction of an almost colorless electron-donating dye and an electron-accepting color developer. A pressure-sensitive recording sheet comprising a solution of a divinylphthalide compound represented by the formula (1) as a core substance and having a particle size distribution of microcapsules within the following range. 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 ); Y
₁ , Y ₂ and Y ₃ are each a hydrogen atom, a halogen atom,
It represents 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. Particle size distribution 4.0 μ ≦ D ₅₀ ≦ 10.0 μ D ₉₀ / D ₁₀ ≦ 2.0 In the above formula, D ₁₀ , D ₅₀ and D ₉₀ are percent particle sizes obtained from the cumulative volume distribution. D ₁₀ -Cumulative 10 percent particle diameter D ₅₀ -Cumulative 50 percent particle diameter D ₉₀ -Cumulative 90 percent particle diameter