JPH0342592B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an improvement in a pressure-sensitive copying sheet containing microcapsules of an oil-based solution of a colorless reactive color-forming dye and a color developer that reacts with the dye to develop a color. Regarding.

(Prior Art) Pressure-sensitive copying sheets are generally used as pressure-sensitive copying paper consisting of a pair of upper and lower sheets. In this case, the top paper is made by dissolving a pigment-forming substance that undergoes a color reaction by donating electrons in an organic solvent, encapsulating it in microcapsules, and then applying it to the bottom surface of the paper. An electron-accepting substance is coated on the top surface of paper. When these papers are stacked so that the top and bottom faces face each other and pressure from a pen or typewriter is applied, the microcapsules on the bottom of the top paper are torn and the pigment-forming substance solution contained within is released onto the top of the bottom paper. It develops color when it comes into contact with an electron-accepting substance. In this case, between the upper paper and the lower paper, the upper surface is coated with an electron-accepting substance, and the lower surface is coated with a microcapsule of the above-mentioned pigment-forming substance dissolved in an organic solvent. You can also store as many sheets of paper as you need.

A method of using such a pressure-sensitive copy sheet in which a necessary form is created in advance by printing or other means, and then copies are made using pen pressure or printing pressure from a typewriter has become widespread, but recently there has been an increase in the number of printing methods used. Instead, a method of copying the necessary forms in advance using an electrophotographic copying machine such as a liquid development copying machine is attracting attention because it is easy and can be carried out at low cost. However, if you try to make a copy by passing a conventional pressure-sensitive copying sheet, which has the same level of smoothness as general PPC paper or general high-quality paper, through an electrophotographic copying machine such as a liquid development copying machine, the density of the copy will be low. , it was impossible to obtain a satisfactory copy image.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks and provide a pressure-sensitive copying sheet that can produce clear transferred images using an electrophotographic copying machine. Furthermore, even if a pressure-sensitive copying sheet is used for printing, the form can be created in advance by a wide range of means without having any adverse effect on the paper passing performance of the printing machine or the quality of the printing finish, and furthermore, it is possible to use a pressure-sensitive copying sheet for printing. The purpose of the present invention is to provide a pressure-sensitive copying sheet with a clear image.

(Means for Solving the Problems) As a result of intensive study, the present inventors found that when obtaining a transferred image on a pressure-sensitive copying sheet using an electrophotographic copying machine,
This problem does not occur with PPC paper or general high-quality paper, but if a pressure-sensitive copying sheet with the same smoothness as these is used, the effects of chemicals applied to the surface of the pressure-sensitive copying sheet will be affected. As a result, the efficiency and uniformity of transfer deteriorates, making it impossible to obtain sufficient copy quality, and it was discovered that the pressure-sensitive copying sheet must have a base smoothness of 90 seconds or more, and based on this knowledge, the present invention was developed. completed. That is, the present invention improves the smoothness of the front or back surface of a pressure-sensitive copying sheet in 90 seconds by coating or impregnating a color forming dye and a color developer layer on a conventional support, preferably a support with high smoothness. The above object is achieved by preferably setting the time to 120 seconds or more.
The desired smoothness can be obtained by calendering the paper during papermaking. Furthermore, the contact area between pressure-sensitive copying sheets is increased by setting the smoothness to 90 seconds or more, making copies made by pressure clearer and making it easier to make beautiful copies in large numbers.

Note that when copying by stacking sheets with a copying machine, double feeding is likely to occur when the contact area between the sheets increases when using general high-quality paper, but with the present invention, paper passing performance such as double feeding is It was good and warm. The reason for this has not been fully elucidated, but in the case of pressure-sensitive copying sheets, the surfaces coated with different materials are usually stacked so that they face each other, such as the surface coated with color-forming dye and the surface coated with color-developing material. Therefore, the coefficient of friction between the opposing surfaces is not as high as when they are made of the same material. It is thought that this is because different materials have different microparticle sizes on their surfaces, so the surface contact is good, and even if the smoothness becomes high, the coefficient of friction does not necessarily increase.

The main elements constituting the pressure-sensitive copying paper of the present invention will be specifically illustrated by giving examples, but these examples are not intended to limit the present invention.

(1) Oily solvent: For example, diethyl oxalate, di-n oxalate
-butyl, dipentyl oxalate, diethyl malonate, di-n-butyl malonate, diethyl glutarate, di-iso-propyl adipate, n-butyl adipate, -iso-butyl adipate, dioctyl adipate, Adipic acid di-
iso-decyl, di-n-butyl sebacate, dioctyl sebacate, dioctyl azelate, di-n-butyl maleate, dioctyl maleate, di-n-butyl fumarate, dioctyl fumarate, diethyl itaconate, itaconic acid Di-n-butyl.

(2) Phenol-formaldehyde novolak resin: For example, p-phenylphenol-formaldehyde resin, p-octylphenol-formaldehyde resin, p-tert-butylphenol-formaldehyde resin, p-methylphenol-formaldehyde resin, p-chloro Phenol-formaldehyde resin, etc.

(3) Ortho-hydroxyarylcarboxylic acids: For example, salicylic acid, 3-phenylsalicylic acid, 3-methyl-5-phenylsalicylic acid, 3
-tert-butylsalicylic acid, 3,5-di-tert
-butylsalicylic acid, 5-tert-octylsalicylic acid, 3-methyl-5-(α-methylbenzyl)salicylic acid, 3,5-di-(α-methylbenzyl)salicylic acid, 3,5-di-(α,α-
dimethylbenzyl) salicylic acid, 5-cumyl salicylic acid, etc.

(4) Organic carboxylic acids: For example, benzoic acid, naphthoic acid, formic acid, acetic acid, propionic acid, caprylic acid, stearic acid, oleic acid, lauric acid, lactic acid, citric acid, abietic acid, etc.

(5) Metals: zinc, magnesium, nickel, tin, titanium, zirconium, etc.

(6) Dye precursors include triphenylmethane lactone type compounds such as crystal violet lactone (CVL) and malachite green lactone, and 3-diethylamino-6-methyl-7-
Anilinofluorane and 3-diethylamino-7
-Fluorane-type compounds widely used in pressure-sensitive copying paper, such as methylfluorane, can be used.

The present invention will be explained below with reference to Examples and Comparative Examples.

Method for producing coating liquid (A) for capsule coated paper Dissolve 2 parts by weight of crystal violet lactone (CVL) in 98 parts by weight of dioctyl adipate,
To this, 20 parts by weight of pigskin gelatin (isoelectric point, PH=8) was dissolved in 160 parts by weight of water, and the mixture was emulsified into an aqueous gelatin solution whose pH was adjusted to 9. Next, a solution of 20 parts by weight of gum arabic dissolved in 1500 parts by weight of water was added, and the temperature was maintained at 50°C. While stirring, a 20% acetic acid aqueous solution was gradually added to adjust the pH to 4.2 to form a gelatin-gum arabic coacervate around the oil droplets. This was cooled to 10°C while stirring well, and 20 parts by weight of a 37% formalin aqueous solution was added and stirred well.

After stirring for an additional hour or more, a 10% aqueous sodium hydroxide solution was added to raise the pH to 9. This completed the production of microcapsules.

A coating liquid (A) was prepared by adding 30 g of wheat starch and 100 g of a 10% aqueous oxidized starch solution to 100 g of this capsule liquid.

Manufacturing method of coating liquid (B) for color developer paper p-phenylphenol-formalin condensation resin (manufactured by Sumitomo Jurates #26142, trade name) 66 parts by weight Zinc formate 33 parts by weight Sodium ligninsulfonate 6 parts by weight Water 144 parts by weight Above The mixture is ground and dispersed in a ball mill for 24 hours. Next, 178 parts by weight of the above dispersion, 100 parts by weight of kaolin, 17 parts by weight of sodium tripolyphosphate, and 333 parts by weight of water were mixed, and 186 parts by weight of a 20% aqueous phosphate starch solution and 50% styrene-butadiene were mixed. A coating liquid (B) was prepared by adding 85 g of polymerized latex.

Example 1 Polyvinyl alcohol (PVA) was applied to one smooth side of a commercially available pure white roll 30g/ ^m2 , and the coating amount after drying the coating liquid (B) prepared above using an air knife coater. After coating at a concentration of 4 g/m ² , calendering was performed to obtain a pressure-sensitive copying sheet with a surface smoothness of 120 seconds. Cut this sheet into A4 size and pass it through Ricoh DT1300.
When sheets were passed, no jamming occurred and the paper passing properties were good. The copy quality was also good.

Example 2 PVA was applied to one side of commercially available high-quality paper 52.3g/ ^m2 ,
On top of that, apply liquid (B) in an amount of 4 g/m ² , and apply liquid (A) in an amount of 4.5 g/m ² on the side opposite to the side coated with coating liquid (B).
After coating, a pressure-sensitive copying sheet with a surface smoothness of 130 seconds was obtained by calendering.

Ricoh DT1300 cuts the sheet into A4 size.
When 500 sheets were passed through the copier, there were no jams and the copy quality was good.

Example 3 Commercially available high-quality paper 52.3 g/m ² was supercalendered in advance to achieve a smoothness of 90 seconds, and coating liquids (A) and (B) were respectively applied in the same manner as in Example 2. A pressure-sensitive copying sheet with a smoothness of 120 seconds was obtained by calendering. When 500 sheets cut to A4 size were passed through a Ricoh DT1300 copier, there were no jams and the copy quality was good.

(Effects of the Invention) The present invention is a pressure-sensitive copying sheet whose front and back surfaces are smoothed to a smoothness of 90 seconds or more by calendering during paper making, making it possible to obtain clear images with an electrophotographic copying machine. It has the characteristics of clear pressure printing, good paper passing performance, and good printing finish.

Claims (1)

[Claims] 1. In a pressure-sensitive copying sheet having at least two supports and to which a toner image is transferred by an electrophotographic copying machine, a color forming dye is applied to the upper surface of one support,
The color developing material is applied or impregnated onto the lower surface of the other support, and at least two supports are stacked and pressure is applied so that the color developing material and the color developing material face each other. 1. A pressure-sensitive copying sheet on which recording is performed by reacting the color developing material with the color developing material, wherein the base smoothness of at least the opposing surface is 90 seconds or more.