JPH05177925A - Pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To prevent the bleeding and fading of a color coupler in the middle lamella paper or the lower lamella paper by setting a layer, which contains inorganic pigment and a binder and has substantially no developing power, on the opposite surface of the microcapsule coating layer of the upper lamella paper. CONSTITUTION:Microcapsules containing a color coupler is prepared by the interfacial polymerization, internal polymerization, etc., of a solution containing a desirable developer and a color coupler. The microcapsules are mixed with a water-soluble binder, a latex binder, cellulose powder and water to prepare a microcapsule coating liquid containing a color coupler. On the other hand, an inorganic pigment dispersion liquid is prepared by dispersing a specified amount of inorganic pigment including calcium carbonate in a suitable dispersion medium such as water and an organic solvent. The microcapsule coating liquid containing the color coupler is applied on the one surface of base paper, while the inorganic pigment dispersion liquid is applied on the other surface of the base paper, and the coated paper is dried to give the upper lamella paper. The upper, middle, and lower lamella paper sheets are conbimed to prepare a pressure sensitive recording sheet.

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. More specifically, the present invention relates to a bar code reading pressure-sensitive recording sheet in which a pigment layer is provided on the surface of top paper.

[0002]

2. Description of the Related Art Conventionally, a pressure-sensitive copying paper which is generally used has a form as follows. That is, an "upper paper" having a coating layer of microcapsules containing micro oil droplets in which an electron-donating organic color former is dissolved or dispersed is provided on one side of the substrate, and an electron-accepting colorant coating layer. There are "lower leaf paper" that has one side of the supporting base, "medium leaf paper" that has a coating layer of microcapsules on one side of the base body, and a coating layer of a coloring agent on the other side of the base body. When paper, middle-leaf paper, and lower-leaf paper are actually used, the upper-leaf paper and the lower-leaf paper are stacked so that their respective coating surfaces face each other, or when it is desired to obtain a large number of copies, the upper-leaf paper is used. Insert one or more sheets of middle leaf between the paper and the lower leaf. When a type or writing pressure is applied to the pressure-sensitive copy papers that are overlapped in this way to form a set, the microcapsules in the pressurizing section are destroyed and the color former inside is transferred to the colorant layer together with the oil to react.
A color image is obtained.

In recent years, bar codes have been used in various fields, and also in the field of pressure-sensitive recording sheets, bar codes are printed and utilized. The pressure-sensitive recording sheet composed of a combination of the upper leaf paper, the middle leaf paper and the lower leaf paper as described above is capable of simultaneously recording on a plurality of sheets, and is very important as a document requiring simultaneous recording. ing.

However, if a bar code is printed on such a known pressure-sensitive recording sheet and after printing, the upper leaf paper, the middle leaf paper, and the lower leaf paper are piled up, the middle leaf just below the upper leaf paper. There is a problem that the barcode (color development image) on the paper or the lower sheet causes blurring or color erasing, making it impossible to read the barcode.

[0005]

Therefore, the present inventors have found that
As a result of various studies to solve these problems, plasticizers, unsaturated aliphatic hydrocarbons, solvents, etc. contained in the ribbon used for barcode printing on the pressure-sensitive recording sheet permeated from the top paper. It was found that the bar code printed on the middle leaf or the lower leaf below it causes blurring and decolorization.

Therefore, an object of the present invention is to provide a pressure-sensitive recording sheet which does not cause color image bleeding and color erasing due to bar code printing.

[0007]

The above objects have been achieved by the present invention described below. That is, in a pressure-sensitive recording sheet composed of a combination of upper leaf paper, middle leaf paper and lower leaf paper, the upper leaf paper includes an inorganic pigment and a binder on the opposite surface to the surface having a coating layer of microcapsules and has a color development. A pressure-sensitive recording sheet, which is coated with a layer having substantially no ability.

That is, according to the present invention, the surface of the top paper opposite to the microcapsule coating layer, that is, the surface in contact with the ribbon, is
It applies a pigment layer containing an inorganic pigment as a main component,
This makes it possible to eliminate bleeding and decolorization of the colored image on the middle or lower paper just below the upper paper. Further, in the prior art, a pigment is used, in order to improve the writability and printability of the microcapsule coated surface of pressure-sensitive copying paper, inorganic solid particles are mixed and dispersed in the microcapsule dispersion liquid. A method of coating on a support or a method of overcoating inorganic particles on the upper part of a capsule coating layer (Japanese Patent Laid-Open No. Sho 5).
2-51215), a method of providing a second coating layer mainly composed of capsules on a first coating layer mainly composed of inorganic solid fine particles and an adhesive (JP-A-54-150210). It is known to be used on paper.

However, in the present invention, the microcapsule layer and the pigment layer are applied on different surfaces, not on the same surface as the capsule layer. Furthermore, the present invention not only successfully preserved the colored image of the middle paper or the lower paper,
It is satisfactory as a recording material capable of eliminating the smearing of the color image on the surface of the top paper coated with the pigment layer during bar code printing.

The present invention will be described in detail below. As the inorganic pigment used in the present invention, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, magnesium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
Examples thereof include magnesium silicate, aluminum silicate, kaolin, talc, zeolite, clay, calcined kaolin, silica, amorphous silica, fine shirasu, physically and chemically deactivated active clay.

In the present invention, the above-mentioned inorganic pigment is dispersed in a suitable dispersion medium such as water or an organic solvent, and applied to form a coating layer on a base paper by a conventional coating machine, size press or the like. However, a suitable binder is used so as to retain sufficient adhesion between the particles of the inorganic pigment or between the particles and the base paper surface. As such a binder, natural or synthetic adhesives such as casein, starch, arabic gum, methyl cellulose, carboxymethyl cellulose, gelatin, polyvinyl alcohol, carboxyl modified polyvinyl alcohol and various synthetic polymer latexes may be used alone or in combination. The amount used is appropriately adjusted according to the inorganic pigment, binder, etc. used, and is not particularly limited, but in general, inorganic pigment 1
It is used in the range of 2 to 50 parts by weight, preferably 5 to 30 parts by weight, relative to 00 parts by weight. Further, auxiliaries well known in the art of producing pressure-sensitive copying paper, for example, dispersants or viscosity modifiers such as sodium alginate and sodium polyacrylate, surfactants, defoaming agents and the like can be appropriately used.

The coating layer composed mainly of an inorganic pigment and a binder has a coating amount of 1 to 15 g / in terms of the coating amount of the inorganic pigment.
m ^2, but preferably is formed to be 3 to 8 g / m ^2, the upper limit of the coating amount is mainly selected appropriately in relation to the cost. In the present invention, as the electron-donating dye (color former),
Colorless or light-colored triallylmethane dyes, diphenylmethane dyes, spiro dyes, fluorane dyes, etc., which are conventionally used for pressure-sensitive recording sheets, are used, but especially for obtaining an image with a high reading rate with a barcode reader. As the electron-donating dye, the absorption maximum of the color image obtained by the reaction with the electron-accepting color developer is 620 to 720n.
It is preferable to use the phthalide compound, the azaphthalide compound, the diazaphthalide compound and the fluorane compound in m.

Specific examples of these compounds are shown in Tables A, B and C.

[0014]

[Chemical 1]

[0015]

[Table 1]

[0016]

[Chemical 2]

[0017]

[Table 2]

[0018]

[Chemical 3]

[0019]

[Chemical 4]

[0020]

[Table 3]

[0021]

[Table 4]

The color former used in the present invention is dissolved in a solvent, encapsulated and applied to a support. As the solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include kerosene, paraffin, naphthenic oil,
Examples thereof include alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylalkane, and phthalic acid ester.

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

Examples of the developer that reacts with the color former used in the pressure-sensitive recording sheet of the present invention include acidic clay, activated clay, attapulgite, zeolite, bentonite, clay substances such as kaolin, and metal of aromatic carboxylic acid. Examples thereof include salts and phenol formaldehyde resins. The performance of the recording sheet of the present invention was tested using the developer sheet shown below. [Preparation of 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 size was 3 μm, to obtain a dispersion (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 Nogatac) (as solid content) are added, and water is prepared to a solid content concentration of 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. ..

[0026]

EXAMPLES The pressure-sensitive recording sheet of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Example I-1 [Preparation of Microcapsule Liquid Containing Coloring Agent] 3.0 g of the specific example (A-2) of the compound shown in Table A and the specific example (C-1 of the compound shown in Table C as the color forming agent. ) 3.0g and 2
4.0 g of anilino-3-methyl-6-diethylaminofluorane are dissolved in 100 g of diisopropylnaphthalene. Carbodiimide-modified diphenylmethane diisocyanate (Mitsui Toatsu Co., Ltd., trade name "MDI-
LK ") and 5 g of hexamethylene diisocyanate isocyanurate (trade name" Coronate EH "manufactured by Nippon Polyurethane Co., Ltd.) and ethylenediamine butylene oxide adduct (number of moles of butylene oxide added to ethylenediamine: 16.8 mol, molecular weight: 126).
7) 3.0 g was dissolved to prepare a primary solution.

Next, 1 part of polyvinyl alcohol was added to 140 g of water.
A secondary solution was prepared by dissolving 0 g and 5 g of carboxymethyl cellulose. While vigorously stirring the secondary solution, the primary solution was poured to form an oil-in-water emulsion.
When the size of the oil droplet reached 6.0μ, the agitation was weakened, and then 10 mL of water at 20 ° C was added to the emulsion.
After adding 0 g and 2.0 g of tetraethylenepentamine, the system temperature was gradually raised to 80 ° C. and kept at this temperature for 90 minutes.

80 g of a 15% aqueous solution of polyvinyl alcohol, 15 g of carboxy-modified SBR latex as a solid content, and 40 g of starch particles (average particle size 15 μ) were added to the thus obtained capsule liquid. Next, water was added to adjust the solid content concentration to 20% to prepare a color developer-containing microcapsule liquid. [Preparation of Pigment Coating Liquid] Using 120 g of calcium carbonate, 1 g of sodium hexametaphosphate and 200 g of water, an inorganic pigment dispersion liquid obtained by atomizing with a sand mill was obtained.

To 300 g of this inorganic pigment dispersion, 9% PVA was added.
-117 (manufactured by Kuraray) and 200 g of carboxy-modified SBR latex (manufactured by Sumitomo Nogatak, SN-30)
7) Add 4 g (as solid content) to give a solid content of 20
To prepare a pigment coating liquid. The [upper lobe paper coating] the color former containing microcapsules solution on one surface of the base paper 40 g / m ^2, so that the solid content of 4.0 g / m ² is applied, the pigment coating solution on the other side 5.
Each was coated with an air knife coater so that a solid content of 0 g / m ² was coated, and dried to obtain top paper. Example I-2 An upper leaf paper was obtained in the same manner as in Example I-1, except that 120 g of aluminum hydroxide was used instead of 120 g of calcium carbonate in [Preparation of pigment coating solution] of Example I-1. .. Example I-3 A top leaf paper was obtained in the same manner as in Example I-1, except that 120 g of kaolin was used instead of 120 g of calcium carbonate in [Preparation of pigment coating solution] of Example I-1. Comparative Example I-1 A top leaf paper was obtained in the same manner as in Example I-1, except that the pigment coating liquid was not applied. Comparative Example I-2 [Coating of Top Paper] The above pigment coating solution was coated with an air knife coater so that a solid content of 5.0 g / m ² was coated on one surface of the base paper and dried.

On the pigment layer, the color-forming agent-containing microcapsule liquid was further coated with an air knife coater so that a solid content of 4.0 g / m ² was coated, and dried to obtain top paper. Comparative Example I-3 [Coating of Top Paper] The microcapsule solution containing the color former was coated on one side of the base paper with an air knife coater so that a solid content of 4.0 g / m ² was coated and dried. ..

On the microcapsule layer, the above pigment coating solution was further coated with an air knife coater so that a solid content of 5.0 g / m ² was coated, and dried to obtain top paper. Example II-1 [Preparation of microcapsule solution containing color former] 3.0 g of a specific example (B-2) of the compound shown in Table B as a color former and 2-anilino-3-methyl-6-N-methyl. -N-tetrahydrofurfurylaminofluorane 4.0 g and 3,3
-Bis (1-n-octyl-2-methylindole-3
2.0 g of -yl) phthalide are dissolved in 80 g of 1-phenyl-1-xylylethane and 20 g of isoparaffin. Polymethylene polyphenyl polyisocyanate (manufactured by Nippon Polyurethane Company, trade name "Millionate M
R200 ") and 8 g of hexamethylene diisocyanate biuret (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name" Sumijour N-3200 ") were dissolved to prepare a primary solution.

Next, 1 part of polyvinyl alcohol was added to 140 g of water.
A secondary solution was prepared by dissolving 0 g and 5 g of carboxymethyl cellulose. 1 above while vigorously stirring the secondary solution
The next solution was poured to form an oil-in-water emulsion. When the size of the oil droplet reached 8.0μ, the stirring was weakened, and then 100 mL of water at 20 ° C was added to this emulsion.
After adding g and 1.6 g of diethylenetriamine, the temperature of the system was gradually raised to 90 ° C. and kept at this temperature for 60 minutes. 80 g of a 15% aqueous solution of polyvinyl alcohol and carboxy-modified SB were added to the capsule liquid thus obtained.
15 g of R latex in solid content and 30 g of starch particles (average particle size 15 μ) were added. Next, water was added to adjust the solid content concentration to 20% to prepare a color developer-containing microcapsule liquid. [Preparation of Pigment Coating Liquid] Using 120 g of calcium carbonate, 20 g of kaolin, 1 g of sodium polyacrylate and 200 g of water, an inorganic pigment dispersion liquid obtained by atomizing with a sand mill was obtained.

A carboxy-modified SBR latex (manufactured by Sumitomo Nogatak, SN-3) was added to 300 g of this inorganic pigment dispersion.
07) 20 g (as solid content) was added and water was prepared so that the solid content concentration was 20% to obtain a pigment coating solution. The [upper lobe paper coating] the color former containing microcapsules solution on one surface of the base paper 40 g / m ^2, so that the solid content of 4.0 g / m ² is applied, the pigment coating solution on the other side 8.
Each was coated with an air knife coater so that a solid content of 0 g / m ² was coated, and dried to obtain top paper. Example II-2 A top leaf paper was obtained in the same manner as in Example II-1, except that 120 g of aluminum hydroxide was used instead of 120 g of calcium carbonate in [Preparation of pigment coating solution] of Example II-1. .. Comparative Example II A top leaf paper was obtained in the same manner as in Example II-1 except that the pigment coating liquid was not applied.

The above-mentioned top paper was evaluated as a bar code reading pressure-sensitive recording sheet, and the results are shown in Table I. The evaluation test was carried out by the following method. (1) Bar code printing The color developer-containing microcapsule sheet surface of the top leaf paper is overlaid on the color developer surface of the color developer sheet, and CO is printed with a dot impact printer (Oki Electric, MICROLINE 8340SV).
The number 8 digit of DE39 was printed. (2) Bar code reading The print sample obtained in (1) was printed 10 minutes after printing, and after printing for 2 weeks with the upper leaf paper and the developer sheet overlaid (23
After leaving it at (° C, RH 65%), a reading test was performed with a barcode reader (Nippon Denso, BHT-2061). (3) Discoloration by printer ribbon, evaluation of blurring,
Decoloring and bleeding of the bar code print after being left indoors in (2) were evaluated visually.

[0035]

[Table 5]

From the above results, Comparative Examples I-1, I-2,
If I-3 and II are left in a piled state, blurring or the like occurs and the barcode reading becomes impossible. On the other hand, in the present invention, the barcode can be read without causing blurring.

[0037]

EFFECTS OF THE INVENTION It is possible to provide a pressure-sensitive recording sheet that does not cause bleeding or decoloration of a colored image by bar code printing.

Claims (3)

[Claims] 1. A pressure-sensitive recording sheet comprising a combination of upper paper, middle paper and lower paper, wherein the upper paper contains an inorganic pigment and a binder on the surface opposite to the surface having the microcapsule layer. A pressure-sensitive recording sheet provided with a layer having substantially no color ability. 2. A phthalide compound, an azaphthalide compound, a diazaphthalide compound having an absorption maximum of 620 to 720 nm of a color image obtained by a reaction with an electron accepting developer as an electron donating dye in a microcapsule of each paper sheet. The pressure-sensitive recording sheet according to claim 1, which comprises at least one of fluoran compounds. 3. The pressure-sensitive recording sheet according to claim 1, wherein the pressure-sensitive recording sheet is for reading a barcode.