JP2003054124A - Color developing sheet for pressure-sensitive copying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color developing sheet for pressure-sensitive copying which is excellent in low-temperature initial coloring properties and also in coloring density and the surface strength of a color developing layer. SOLUTION: In regard to pressure-sensitive copying recording which utilizes a coloring reaction of an electron-donating colorless dye and an electron- accepting color developing agent, the color developing layer constituted of an acrylonitrile-butadiene latex and/or an acrylic ester latex containing an electron-accepting organic compound and having a glass transition temperature of -5 to -50 deg.C is provided at least on either the surface or the rear of a substrate.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive copying paper, and more particularly, to a pressure-sensitive copying color developing sheet excellent in low-temperature initial color development. It is. 2. Description of the Related Art It has long been known to obtain a color image by a contact reaction between an electron-donating colorless organic compound (hereinafter referred to as a color former) and an electron-accepting organic compound (hereinafter referred to as a color developer). Known from. There is pressure-sensitive copying paper as a specific use of this phenomenon. [0003] Such pressure-sensitive copying paper is used for various kinds of slips,
It is widely used like tickets and computer paper, and is especially used for applications and contracts in the credit and insurance industries. In a mechanism for obtaining a color image by a contact reaction, the quality required of a color developing sheet provided with a color developing agent includes a high initial color developing speed, a high color density, and a reduction in stains. Less, good light resistance, chemical resistance, water resistance, etc. of the color image, good light resistance and nitrogen oxide resistance of the color developing layer, no decrease in color developer capacity during storage That the surface of the color developing layer further has good printability such as offset, letterpress, and flexo, and the like.In particular, it is desired that the initial color developing speed is high, and as a method for improving the initial color developing speed, the following method is used. It has been known. 1) A method of improving the transfer efficiency of an oily substance in which a color former has been dissolved to a color developing layer by adding a white pigment to the color developing layer. 2) A method of increasing the specific surface area by adding calcium carbonate having a small particle size as a pigment to improve the transfer efficiency of an oily substance in which a coloring agent is dissolved to a color developing layer. However, in the method of 1), in which the coloring rate is improved by increasing the compounding ratio of the pigment having high oil absorption, the binding force of the color developing layer is reduced by increasing the compounding ratio. When printing, problems such as powder dropping of the coating layer and pilling are likely to occur. On the other hand, when the amount of the binder is increased as a countermeasure against the decrease in the binding force, there is a problem that the coloring speed is reduced. In the method 2), since the binding strength of the coating layer is reduced when the amount of the binder is increased due to an increase in the specific surface area, the amount of the binder must be increased, and as a result, the color development speed is also increased. Can not be prevented. As described above, in the conventional method, there is a problem that the surface strength of the color developing layer is reduced due to the improvement of the color developing speed, so that the printability is reduced. An object of the present invention is to solve the above-mentioned problems and to provide a color developing sheet for pressure-sensitive copying excellent in low-temperature initial color development. [0010] The color-developing sheet for pressure-sensitive copying of the present invention, which has solved the above-mentioned problems, comprises a colorless electron-donating dye,
In a pressure-sensitive copy recording utilizing a color development reaction with an electron-accepting developer, at least one of the front and back surfaces of the support contains an electron-accepting organic compound, and has a glass transition temperature of -5 ° C to- A color developing layer comprising an acrylonitrile-butadiene-based latex and / or an acrylate-based latex at 50 ° C. is provided. Hereinafter, the present invention will be described in detail.
In the present invention, at least one of the support is provided with a color developing layer containing an acrylonitrile-butadiene-based latex and / or an acrylate-based latex having a glass transition temperature of −5 ° C. to −50 ° C., containing a color developer. Can be The developer contained in the color developing layer of the present invention can be selected from those usually used in the field of pressure-sensitive copying paper. That is, activated clay, acid clay, inorganic developer such as attapulgite, phenol-formaldehyde resin, polyvalent metal salt of salicylic acid derivative, polyvalent metal salt of terpene phenol resin, polyvalent metal salt of salicylic acid-containing copolymer, etc. However, the present invention is not limited thereto. Further, in the color developing layer of the present invention, various additives usually used in color developing sheets for pressure-sensitive copying can be used, if necessary, including pigments and binders. Specifically, inorganic pigments such as calcium carbonate, magnesium carbonate, kaolin, calcined kaolin, talc, barium sulfate, aluminum oxide (alumina), silicon oxide (silica), zinc oxide, satin white, titanium oxide, polystyrene, Organic pigments such as urea formaldehyde resin
As the binder, in combination with the above-mentioned acrylic latex, modified starches such as oxidized starch, enzymatic starch, urea phosphate starch, and alkylated starch; water-soluble proteins such as casein and gelatin; styrene-butadiene latex (SBR); Methacrylate-butadiene latex (MBR), vinyl acetate emulsion, acrylic emulsion, styrene-butadiene copolymer emulsion, polyvinyl alcohol, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, etc., semi-synthetic binders, other additives, An antifoaming agent, a foam inhibitor, a fluorescent brightener, a viscosity modifier, a dusting inhibitor, a lubricant, a waterproofing agent, an ultraviolet absorber, a preservative, and the like can also be used. The types and amounts of the color developer, pigment, binder, and other additives used in the present invention are determined according to the required quality of the coated paper, and are not particularly limited. In the present invention, the glass transition temperature is -5.
An acrylonitrile-butadiene-based latex and / or an acrylate-based latex at a temperature of from -50 ° C to -50 ° C are used for the color developing layer. In the present invention, the acrylonitrile-butadiene-based latex and / or the acrylate-based latex have a glass transition temperature of −5 ° C. to −50.
It needs to be in ° C. If the temperature exceeds -5 ° C, there is a problem that a sufficient low-temperature initial coloring speed cannot be obtained, and
If the temperature is lower than ℃, there is a problem that the stability of the paint is reduced. Acrylonitrile used in the present invention
Butadiene-based latex and acrylate-based latex have better adhesive strength and impact-peeling strength than other latexes, and good flexibility at low temperature. Because of its excellent properties,
It is considered that the low-temperature color developability of the developer can be improved. The developer layer coating solution applied to the support is appropriately adjusted by a conventionally known adjusting method. The adjusted coating liquid can be any of paper, synthetic paper, film, and the like, using a coater appropriately selected from known coaters such as a blade coater, an air knife coater, a bar coater, a roll coater, a curtain coater, and a guaia coater. And dried to obtain the desired color-developed sheet for pressure-sensitive copying. The amount of coating on the support varies depending on the type of developer used and the desired degree of color development, but is usually about 0.3 to 8 g / m ² . If the amount is too small, sufficient low-temperature color developability cannot be obtained, and if the amount is too large, the color developing layer becomes thick and the copying ability decreases. Therefore, it is necessary to determine in consideration of low-temperature color developability and copying ability. The color former used in the pressure-sensitive copying developer sheet of the present invention includes triphenylmethane compounds, diphenylmethane compounds, triarylmethane compounds,
Fluoran compounds, thiazine compounds, oxazine compounds, xanthene compounds, spiropyran compounds,
Lactam compounds and the like. As a specific example, for example,
There are crystal violet lactone, 3-diethylamino-6-methyl-7-anilinofluoran, benzoylleucomethylene blue and the like, but there is no particular limitation. These color formers are either dissolved in a solvent and encapsulated, or dispersed in a binder solution, and used in the present invention. As the solvent, natural or synthetic oils can be used alone or in combination. For example, alkylated naphthalene, alkylated biphenyl, hydrogenated terphenyl, alkylated diphenylmethane, kerosene, naphtha,
There are paraffin oil, chlorinated paraffin, soybean oil, cottonseed oil and the like, but there is no particular limitation. As the support, conventionally known fiber materials can be used, and paper is preferably made from wood pulp as a main material. Wood pulp may be a mixture of synthetic fibers and synthetic pulp. Examples of the wood pulp include hardwood bleached pulp (LBKP), softwood bleached pulp (NBKP), mechanical pulp (C-GP), waste paper pulp (DIP), and the like. The wood pulp may contain a paper strength agent, a dye, a pigment, a pH adjuster, a preservative, a fungicide,
Flame retardants and water retention agents can be used alone or in combination of two or more. In the use form of the present invention, a coating solution having a structure in which a color developer layer and a color former layer are combined on the same surface of a support, or a color developer containing a color developer and an encapsulated color former is used. And a self-coloring type pressure-sensitive copying sheet having a mixed color developing layer (so-called self-contained type). The present invention will now be described with reference to Examples and Comparative Examples, which by no means limit the present invention. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively, unless otherwise specified. [Example 1] [Preparation of developer coating solution]
100 parts of a 0% aqueous dispersion is prepared, and 20 parts of a 40% dispersion of a zinc salt of a salicylic acid copolymer and 20 parts of an oxidized starch are prepared.
% Aqueous solution and 10 parts of an acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) to obtain a developer coating solution. After applying the obtained coating liquid to a high-quality paper of 40 g / m ² using a blade coater so that the solid content becomes 5 g / m ² , the coating liquid is dried by heating under the conditions of 120 ° C. to 180 ° C. A color developer sheet was obtained. Example 2 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with an acrylate copolymer (glass transition temperature: -50 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Example 3 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with an acrylonitrile-butadiene copolymer (glass transition temperature: -5 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Example 4 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with an acrylate copolymer (glass transition temperature: -30 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Comparative Example 1 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with a styrene-butadiene copolymer (glass transition temperature: -10 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Comparative Example 2 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with an acrylate copolymer (glass transition temperature: -1 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Comparative Example 3 The procedure of Example 1 was repeated except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with the acrylonitrile-butadiene copolymer (glass transition temperature: −55 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. Comparative Example 4 The procedure of Example 1 was repeated, except that the acrylonitrile-butadiene copolymer (glass transition temperature: -20 ° C.) was replaced with the acrylonitrile-butadiene copolymer (glass transition temperature: -3 ° C.). Thus, a color-developed sheet for pressure-sensitive copying was obtained. The developed sheets for pressure-sensitive copying obtained in the above Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 1. [Test Method] <Coloring Speed and Coloring Density> The obtained pressure-sensitive copying developer sheet is overlapped with a commercially available upper paper so that the coated surface faces each other, and cooled at 5 ° C. for 1 hour. After that, a dot impact printer (manufactured by NEC: PC
-PR201 / 65) to form a print color.
The color density after 0 seconds was measured using a Macbeth densitometer (DM-620, manufactured by Dainippon Screen). Subsequently, these color-developed sheets were transferred under normal temperature (24 ° C.) conditions, and the color density after 24 hours was measured using a Macbeth densitometer (DM-620, manufactured by Dainippon Screen Co., Ltd.). (The higher the numerical value, the higher the color density). In addition, regarding the low-temperature initial color developability, it was determined that the low-temperature initial color developability was good if the color density was 0.4 or more under the above conditions. <Surface strength> Using a printing suitability tester (manufactured by Akira Seisakusho), offset printing ink of Toyo Ink Tack Value 26 was printed on the coated surface of the developed color sheet, and the picking state was visually determined. …: Picking hardly occurs, x: Picking slightly occurs. [Table 1] As is clear from the results in Table 1, Example 1
Nos. 4 to 4 are excellent in low-temperature initial color development speed, and also in color development density and surface strength of the color developing layer. On the other hand, Comparative Example 1 is an example in which a styrene-butadiene copolymer is used as a binder, and is remarkably inferior to Examples in low-temperature initial color development regardless of the glass transition temperature. In Comparative Example 2, the glass transition temperature was -1.
This is an example in which an acrylonitrile-butadiene copolymer at a temperature of ° C. is used. Comparative Example 4 is an example using an acrylonitrile-butadiene copolymer having a glass transition temperature of −3 ° C., but is inferior in low-temperature initial color development. Comparative Example 3 is an example in which an acrylic ester copolymer having a glass transition temperature of -55 ° C was used, but the stability of the paint was extremely low, and a color developing sheet could not be produced. The color-developing sheet for pressure-sensitive copying of the present invention is a color-developing sheet for pressure-sensitive copying excellent in low-temperature initial color development, and also in color density and surface strength of the color developing layer. .

Claims (1)

Claims: 1. In a pressure-sensitive copying recording utilizing a color-forming reaction between an electron-donating colorless dye and an electron-accepting developer, at least one of a front surface and a back surface of a support is provided with an electron. Glass transition temperature of -5 ° C to -5 containing receptive organic compound
A color developing sheet for pressure-sensitive copying, comprising a color developing layer made of acrylonitrile-butadiene type latex and / or acrylate type latex at 0 ° C.