JPH02266976A - Pressure sensitive recording developer sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a color developing sheet for pressure-sensitive recording.

More specifically, the present invention relates to a color developer sheet for pressure-sensitive recording, which is used over a dye sheet containing a substantially colorless dye and which develops the dye to form an image.

[Prior Art] Pressure-sensitive recording paper is also called carbonless paper, and usually includes an upper paper whose back surface is coated with microcapsules containing a substantially colorless dye, such as a leuco dye, which develops color when it comes into contact with an acidic substance; It consists of a sheet of paper coated with a color developer that develops the color when it comes into contact with the colorless dye. If necessary, one or more inner sheets coated with a color developer layer on the front side and a dye microcapsule layer on the back side may be inserted between the upper and lower sheets. By stacking the top, middle, and bottom sheets of paper and applying pressure from a pen or a printer, etc., the dye microcapsules are destroyed and the dye and color developer are brought into contact, forming a colored image on the color developer layer. By forming a large number of copies at once.

In general, the performance required of a color developer sheet for pressure-sensitive recording used as a base paper is high color density for colorless dyes, fast color development speed, light resistance of colored images, chemical resistance,
It has good water resistance, the color developer-containing layer does not yellow due to light or nitrogen oxides in the air, and there is no decrease in color development ability for colorless dyes during storage.
Furthermore, the developer layer has good suitability for offset printing, letterpress printing, flexo printing, etc.

Conventionally, inorganic color developers such as acid clay and abatalgite have been used as color developers for pressure-sensitive recording, but these have the disadvantage that colored images are easily faded by light or water. As a method to improve these drawbacks, a method of blending zinc oxide with an inorganic color developer (Special Publications Showa 4B-
9290) and a method of adding rhodanate (Japanese Patent Publication No. 12254/1983) are known. However, these improvement methods have not yielded satisfactory results.

Organic acid color developers have been developed as color developers that do not have the above-mentioned drawbacks of inorganic color developers. Polyvalent metal salts of derivatives (Japanese Patent Publication No. 51-25174, etc.), polyvalent metal salts of salicylic acid-containing copolymers (Japanese Patent Publication No. 62
-176875, 63-53092 63-186
No. 729, etc.), and polyvalent metal salts of terpene phenol resins (Japanese Patent Application Laid-open No. 82-19486, etc.) are known. However, these organic acid color developers have drawbacks such as slow color development speed, insufficient ink receptivity, and ink drying speed, which can easily cause problems during printing. have.

It has been known to add calcium carbonate as a white pigment to a color developing layer for pressure-sensitive recording paper. The normal particle forms of calcium carbonate are light calcium carbonate and heavy calcium carbonate, such as grain-like, spindle-like, spherical, and amorphous shapes. 58
It is said that calcium carbonate particles having a particle size distribution of 55% or more of 2- or less as described in Japanese Patent No. 38117 are useful. However, even when such calcium carbonate is used as a pigment for a color developing layer for pressure-sensitive recording, good results are not necessarily obtained.

[Problems to be Solved by the Invention] The present invention eliminates the above-mentioned drawbacks of organic acid color developers, provides high color density, fast color development speed, and eliminates uneven ink coverage and ink dropout during printing. The object of the present invention is to provide a color developer sheet for pressure-sensitive recording which has excellent recording and printability without causing troubles such as staining due to transfer.

[Means for Solving the Problems] As a result of extensive research into solving the above problems, the present inventors have developed a pressure-sensitive recording material containing a color developer containing an organic acidic substance or a polyvalent metal salt thereof. In the color developer layer of the color developer sheet,
The present invention has been completed based on the discovery that the problem can be effectively solved by incorporating aragonite acicular calcium carbonate aggregates having a specific average particle size into the color developing layer.

The present invention provides a color developer sheet for pressure-sensitive recording comprising a color developer layer containing a color developer made of an electron-accepting organic acidic substance, a white pigment, and a binder on a sheet-like support. 5 to 100% by weight of the white pigment in the color developing layer is made up of acicular calcium carbonate aggregates having an average particle size of 4 units or less, in which aragonitic acicular calcium carbonate secondary particles are irregularly intertwined in a three-dimensional manner. The present invention relates to a color developing sheet for pressure-sensitive recording, which is characterized by:

In the present invention, the calcium carbonate to be incorporated into the color developing layer is composed of aragonitic acicular calcium carbonate particles irregularly and three-dimensionally intertwined to form a sea urchin-like shape. This bundle usually has an average particle size of 4x or less. Calcium carbonate in such a shape has a higher bulk and a larger oil absorption amount than normal heavy or light calcium carbonate, and can efficiently absorb oil released from the microcapsules. Therefore, by including such calcium carbonate in the color developing layer, it is not only possible to obtain a color developing sheet with high color density and fast color development speed, but also with excellent ink absorption and water absorption. This makes it possible to achieve beautiful pressure-sensitive recording with excellent print finish and excellent suitability for offset printing.

In the present invention, it is possible to coexist a white pigment other than the acicular calcium carbonate aggregates in the color developing layer, but in any case, the amount of white pigment in the color developer should be 5 to 100% of the total weight of the white pigment in the color developer. % by weight of the acicular calcium carbonate aggregates.

Preferably, the amount is 10 to 50% by weight of the acicular calcium carbonate aggregate. If the amount is less than 5% by weight, the effect of incorporating the acicular calcium carbonate is not substantially observed. White pigments that can be used with acicular calcium carbonate bundles include anisotropic heavy and light calcium carbonate, kaolin, zinc oxide, titanium oxide, zinc hydroxide, aluminum silicate, calcium silicate, calcined kaolin, hydroxide. Common white pigments such as aluminum and talc can be used.

The content of the white pigment in the color developer layer is preferably 40 to 90% by weight based on the total solid weight of the color developer layer.

In the present invention, as the color developer to be included in the color developer layer, any organic acidic substance commonly known as an organic acid color developer can be used.
Novolak-type phenolic resins such as p-phenylphenol novolak resin and p-octylphenol novolac resin, modified phenol resins such as phenol-acetylene resin, and polyvalent metal salts thereof; Japanese Patent Publication No. 49-10856 Publication No., Special Publication No. 51
Benzoic acid, nitrobenzoic acid, etc. described in Japanese Patent Publication No. 25174 and Japanese Patent Publication No. 49-55410, etc.
p-tert-butylbenzoic acid, 4-methyl-3-nitrobenzoic acid, p-isopropylbenzoic acid, 2,5-dinitrobenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2-hydroxy-1 -benzyl-3-naphthoic acid, 1-benzoyl-2-hydroxy-3-naphthoic acid, 3-hydroxy-5-cyclohexyl-2-naphthoic acid, salicylic acid, 5-tart-butylsalicylic acid, 3-phenylsalicylic acid, 3-Cyclohexylsalicylic acid, 3-methyl-5-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 5-cyclohexylsalicylic acid, 3-methyl-5- Isoamyl salicylic acid, 3,
5-di-5ec-butylsalicylic acid, 3-phenyl-5
-(α,α-dimethylbenzyl)salicylic acid, 3-cyclohexyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-5-methylsalicylic acid, 3,5-dicyclo hexylsalicylic acid,
3.5-di(α-methylbenzyl)salicylic acid, 3.
5-di(α,α-dimethylbenzyl)salicylic acid, 3-
Aromatic carboxylic acids such as (α-methylbenzyl')-5-(α,α-dimethylbenzyl)salicylic acid and 4-methyl-5-cyclohexylsalicylic acid, and polyvalent metal salts of these organic acid compounds: JP-A Metal salts of oligobenzylated aromatic hydroxycarboxylic acids as described in JP-A-83-132857; JP-A-63-1
Polyvalent metal salts of carboxy-modified terpene phenol resins as disclosed in JP-A No. 9486; JP-A-48-8
Salicylic acid novolac resin disclosed in JP-A No. 215; or JP-A-62-176875, JP-A-6
Copolymers of salicylic acid with compounds such as alkoxyxylene, trialkylbenzene, and styrene derivatives, or polyvalent metal salts thereof, as disclosed in JP-A No. 3-53092 and JP-A No. 83-186729. etc. can be given. The color developer used in the present invention may be composed of only one type of the above acidic substances, or may be composed of two or more thereof.

Generally, the content of the color developer in the color developer layer is preferably 5 to 70% by weight based on the total solid weight of the color developer layer.

Examples of the binder contained in the color developing layer of the present invention include water-soluble ones such as carboxymethyl cellulose, gelatin, hydroxyethyl cellulose, oxidized starch, acetate starch, phosphate starch, hydroxyalkylated starch, polyvinyl alcohol, and polyacrylic acid. binder; and styrene-butadiene copolymer, methyl methacrylate
Latexes include butadiene copolymers, acrylic acid (methacrylic acid) ester polymers, vinyl acetate copolymers, and the like, and these may be used alone or in combination of two or more.

[Example] This research will be explained in more detail with reference to Examples below.

In the Examples and Comparative Examples below, a top paper (containing a dye capsule sheet) prepared by the method described below was used to form a colored image.

EXAMPLE 1 8 parts by weight of crystal violet lactone were dissolved in 200 parts by weight of alkylated naphthalene, which was encapsulated with a urea-formalin polymer wall membrane. 5 dye capsules
A dye capsule coating solution was prepared by adding lOO parts by weight of a 10% oxidized starch aqueous solution, 20 parts by weight of fine cellulose powder, and 1 part by weight of water to 100 parts by weight of an aqueous slurry containing a concentration of 0%. This coating liquid has a basis weight of 53g/rr! The coating amount after drying on one side of the base paper is 5.
g/rr? The paper was coated and dried to create the upper paper.

Examples 1 to 4 Amorphous heavy calcium carbonate dispersed in 20 parts by weight of water (NS-800 80% dispersion liquid, manufactured by Rochu Funka Kogyo Co., Ltd.)
and an aragonitic acicular calcium carbonate aggregate (
Callite 5A 50% dispersion (manufactured by Shiraishi Kogyo Co., Ltd.) was added in the proportions shown in Table 1.

To this dispersion, 25 parts by weight of a 40% p-phenylphenol resin emulsion was further added as a color developer while stirring. Next, 20 parts by weight of styrene-butadiene latex (solid content 50%) and 10 parts by weight of oxidized starch aqueous solution (solid content 15%) were added to this mixed solution as a binder to form a developer layer coating solution. Created. The amount of coating after drying this coating solution is 6
A developer sheet was prepared by coating one side of a base paper with a basis weight of 5 Bg/rrr so that the color was 100 g/rrr.

Comparative Examples 1-2 Color developing sheets were prepared by repeating the operations of Examples 1-4, except that the white pigments listed in Table 2 were used.

5: Extremely excellent.

4: Excellent.

3: Normal.

2: Fairly poor.

1: Defective.

The results are shown in Table 3.

The color developing sheets of Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to the following tests to evaluate their quality.

■ Color development density: The color development sheet combined with the upper paper was passed between pressurized rolls and then stored in a dark place, and the color density after 24 hours was measured using a Macbeth reflection densitometer.

■ Color development speed: The color development rate is the color development rate when the density (Dt) after 30 seconds of a color development sheet developed in the same manner as the color development density is measured using a Macbeth reflection densitometer, and the density after 24 hours (D24) is set as 100. Expressed in (%).

Color development rate (%) - (Dt/D24) xio.

■ Offset printing suitability: RI-II type printing tester (
(manufactured by Mei Seisakusho).

■ Ink receptivity: Ink receptivity was evaluated using Ni&N ink (manufactured by K&N).

■ Drivic test: lGT Pr1ntabilf
ty Te5ter was used to evaluate the required strength of the surface of the color developing layer during printing.

Offset printing suitability, ink receptivity and dry cleaning were evaluated on the following five scales.

[Effects of the invention] The color density and color development speed of a color developer sheet for pressure-sensitive recording obtained by incorporating aragonitic acicular calcium carbonate aggregates into a color developer layer containing a color developer made of an organic acidic substance , and printability can be significantly improved, and therefore, it has become possible to provide a color developer sheet for pressure-sensitive recording with excellent color development performance and printability.

Claims (1)

[Claims] 1. In a color developer sheet for pressure-sensitive recording comprising a color developer layer containing a color developer made of an electron-accepting organic acidic substance, a white pigment, and a binder on a sheet-like support, the color developer layer A texture characterized in that 5 to 100% by weight of the white pigment therein is made into acicular calcium carbonate aggregates having an average particle diameter of 4 μm or less, in which aragonitic acicular calcium carbonate primary particles are irregularly intertwined three-dimensionally. Color developer sheet for pressure recording.