JPS6367179A - Recording sheet - Google Patents

Abstract

PURPOSE:To improve the light resistance of a microcapsule layer in a recording sheet, by incorporating p-substituted aminophenyl indolylphthalide derivative and an ultraviolet absorbing agent into the microcapsule. CONSTITUTION:Preferably, a compound shown by formula I is employed as p-substituted aminophenylindolylphthalide compound which is employed as a color former. Preferably, benzotriazol ultraviolet ray absorbing agent having spectral absorption in the range of 270-380mmu is employed as an ultraviolet ray absorbing agent. When said derivative is contained by 30wt% or more of the entire quantity of color former, the rigidity of coloring material is improved, then said coloring material is dissolved together with the ultraviolet ray absorbing agent into a solvent and encapsulated so as to be applied onto a supporting material. The microcapsules are produced through interfacial polymerization, inner polymerization, phase separation, outer polymerization, coacervation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a recording sheet, and more particularly to a recording sheet that utilizes a color-forming reaction between a nearly colorless electron-donating dye and an electron-accepting compound.

(Prior art) Recording sheets using nearly colorless electron-donating dyes (hereinafter referred to as color formers) and electron-accepting compounds (hereinafter referred to as color developers) can be used for pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, and electrically conductive heat-sensitive paper. It is already well known as recording paper. For example, UK patent 2
/'IO≠≠ri, US patent l≠♂00!2, same≠4t3
t tacho 0, special public show tO-, 2j, 9.22, special public show 3
7-/7ri, 13t1 AO-/ko3. ! ! t, same 40
-/23°137 etc.

The performance that a recording sheet should have is (1) sufficient color density and color development sensitivity, (2) no fogging, (3) sufficient fastness of the color material, and (4) color development. The light resistance of the microcapsule layer containing the agent is sufficient.

It has already been proposed to use p-substituted aminophenylindolyl phthalide derivatives as color formers that provide color formers with extremely excellent fastness in these recording sheets (Japanese Patent Publication No. 1/-2-2). /32, Tokuko Akihirota / A72A, Tokuko Akihirota 1302, etc.).

However, the recording sheet containing this p-substituted aminophenylindolphthalide derivative in microcapsules is
It has a drawback that the light resistance of the microcapsule layer is not sufficient (the color development property decreases due to light irradiation of the microcapsule layer).

(Object of the Invention) An object of the present invention is to provide a recording sheet containing p-substituted aminophenylindolphthalide as a coloring agent in the microcapsules, in which the light resistance of the microcapsule layer is improved. .

(Structure of the Invention) An object of the present invention is to provide a recording sheet containing microcapsules containing an almost colorless electron-donating dye, wherein the microcapsules contain a p-substituted aminophenylindolphthalide derivative and an ultraviolet absorber. This was achieved by using a recording sheet that is characterized by the following.

Preferred ultraviolet absorbers are 270 to JIOm
Salicylic acid-based ultraviolet absorbers such as p-tert-7' tylphenyl salicylate, p-octylphenyl salicylate, co-hydroxybenzophenone, co-hydroxybenzophenone, etc. p-methoxybenzophenone, 2-
Hydroxy-≠-octoxybenzophenone, co-hydroxy-j-dodecyloxybenzophenone, 2.2'
-dihydroxy-≠-methoxybenzophenone, j,,
Benzophenone ultraviolet absorbers such as 2'-dihydroxyg, ≠'-dimethoxybenzophenone, λ-hydroxy≠-methoxy 3-sulfobenzophenone,
2(,?'-hydroxy-j'-methylphenyl)penztriazole, λ(2'-hydroxy-y'-te
rt-butylphenyl)benzotriazole, x(2'
-Hydroxy-J/, z/-G-tert-
butyl-phenyl)penztriazole, 2(J'-hydroxy-3'-tert-butyl-j'-methylphenyl)-J-chlorobenzotriazole, J(,2'
-Hydroxy-3/, z/-di-tert-butylphenyl)-S-chlorobenzotriazole, 2(
2'-hydroxy-3/, 3/-tert
-amylphenyl)penztriazole, 2(,2'-
Benzotriazole ultraviolet absorbers such as hydroxy-≠′-octoxyphenyl)benzotriazole,
Examples include cyanoacrylate ultraviolet absorbers such as coethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate. Among these, preferred are benzotriazole ultraviolet absorbers.

The amount of the ultraviolet absorber used is preferably 3 to 200% by weight, more preferably 10 to io, based on the p-substituted aminophenylindolphthalide derivative.

Weight%.

The p-substituted aminophenylindolphthalide compound used as the color former of the present invention is preferably one represented by the following general formula, in which x, y, and z are hydrogen atoms, halogen atoms, C1 to C8 an alkyl group, a C1-C12 alkoxy group, a C6-C18 aryloxy group, -yo- or a C7-C18 aralkyloxy group, W represents a hydrogen atom or a halogen atom, and R1 represents a hydrogen atom or a 72
R2 represents a hydrogen atom, a C1-C8 alkyl group, or a C6-C12 aryl group; , R3 and R4 are each independently a hydrogen atom or 7
represents an alkyl group, a C5-C7 cycloalkyl group, a benzyl group, or a phenyl group, which is unsubstituted or substituted with a halogen atom, a hydroxyl group, a cyano group, or a lower alkoxy group, having up to 2 carbon atoms;
Furthermore, -NR3R4 may form a pyrrolidinyl group.

Specific examples of preferred compounds as the p-substituted aminophenylindolphthalide compound represented by the above general formula are shown in Table 1.

-+- In addition to p-substituted aminophenylindolyl phthalide derivatives, color formers include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl azaphthalide compounds, and leuco auramine compounds. , rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, etc. may all be used in combination.

In this case, it is desirable to use the p-substituted aminophenylindolphthalide derivative of the present invention in an amount of 30% by weight or more based on the total amount of the color former from the viewpoint of the fastness of the color former.

The color forming agent used in the present invention is dissolved in a solvent together with an ultraviolet absorber, encapsulated, and applied to a support.

As a solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil, kerosene, halaffin, naphthenic oil, alkylated biphenyls, alkylated terfels,! Examples include hydrogenated paraffins, alkylated naphthalenes, diphenylalkanes, and the like.

As a method for manufacturing the color former-containing microcapsules, an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, a coacervation method, etc. are used.

In preparing a coating solution containing microcapsules containing a color former, a water-soluble binder or a latex binder is generally used. Further, a capsule protectant such as cellulose powder, Tenbun particles, talc, etc. is added to obtain a color former-containing microcapsule coating liquid.

Examples of color developers that react with the color forming agent used in the recording sheet of the present invention include acid clay, activated clay, attapulgite, zeolite, bentonite, clay materials such as kaolin, metal salts of aromatic carminic acids, and phenolic resins. can be given.

These color developers are applied to a support such as paper along with a binder such as styrene butadiene latex.

The performance of the recording sheet of the present invention was tested using the following color developer sheet.

[Adjustment of color developer sheet]

70 parts of water, 2 parts of zinc oxide, 1 part of calcium carbonate and 3 parts
．． ! 2.3 parts of solid content of carboxy-modified S 13 R latex and 7wt% PVA 72 parts of an aqueous solution (polymerization degree iooθ) was added and stirred uniformly to obtain a coating solution.
A developer sheet was obtained by coating and drying using an air knife coater capable of coating a solid content of r/m2.

(Example of the invention) The present invention will be specifically explained below using Examples.

The invention is not limited to the examples.

Examples/~10 and Comparative Examples/~3 μ, ≠ of partial sodium salt of polyvinylbenzenesulfonic acid (average molecular weight 200.θ00) adjusted to pH +
A color former oil prepared by dissolving the color former and ultraviolet absorber shown in Table 1 in 10 parts of diisopropylnaphthalene is emulsified and dispersed in 10 parts of the aqueous solution to obtain an average particle diameter of 1//- ≠,! An emulsion with a particle size of μ was obtained. Separately, 6 parts of melamine, 37 parts by weight/t% formaldehyde aqueous solution, and 30 parts of water were heated and stirred in zOoC, and after 30 minutes, a transparent mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate was obtained. The pH of this mixed aqueous solution was +, oa', and θ. Hereinafter, this mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate will be referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to and mixed with the above emulsified mixture, and while stirring, the pn was adjusted to t, o with a 3.6% by weight hydrochloric acid solution, and the liquid temperature was raised to ts 0c. Then, stirring was continued for EtO.

This capsule solution was cooled in a room temperature chamber, and the pH was adjusted to 0 with 20% by weight sodium hydroxide.

To this capsule dispersion, 700 parts of a 10-weight layer aqueous solution of ribinyl alcohol, 70 parts of carboxy-modified SBR latex as a solid content, 50 parts of starch particles and 10 parts of calcium/umium carbonate were added, and water was added to reduce the solid content. ,2
0 to prepare a coloring agent-containing microcapsule coating solution.

This coating solution was applied to a base paper of 0.0g/rrL2 using an air knife coater so that the solid content was coated with a toughness/m2, and dried to obtain a microcapsule sheet for pressure-sensitive copying.

Comparative test (1) Light resistance of microcapsule layer The microcapsule layer of the example and comparative microcapsule sheet was subjected to a fluorescent lamp fading tester (33, Oo o 1ux).
) After irradiating for g hours, layer it on a developer sheet and
Color was developed by applying a load pressure of kll/cm2. In the dark 2
After leaving the sample for a time of ≠, the spectral absorption curve of the chromophore was measured at a wavelength of 310 to 71 Onm, and the density at the thickest absorption was measured.

Separately, unirradiated Example and Comparative microcapsule sheets were stacked on a developer sheet, and 300 kl? /CrIL2 was applied to develop color. After leaving it in the dark for 2≠ hours,
The spectral absorption curve of the chromophore between wavelengths 31rO and 710nm was measured, and the concentration at the absorption maximum (fresh concentration) was determined.
Do)) was measured.

The measurement of the spectral absorption curve was carried out using Hitachi Color Analyzer 307.
Table 2 shows the light resistance values determined using the following formula using a mold.

The larger the original resistance value, the better the light resistance of the microcapsule layer.

As shown in Table 2, it can be seen that the microcapsule sheet of the present invention has better light resistance of the microcapsule layer than the comparative microcapsule sheet.

Claims (1)

[Claims] 1. A recording sheet containing microcapsules containing a substantially colorless electron-donating dye, characterized in that the microcapsules contain a p-substituted aminophenylindolphthalide derivative and an ultraviolet absorber.