JPS61160287A - Pressure-sensitive recording sheet - Google Patents

Abstract

PURPOSE:To markedly improve the light fastness of a microcapsule layer containing a color former and that of a developed color material, by containing a specific diphenylamine derivative in a microcapsule. CONSTITUTION:A diphenylamine derivative represented by general formula [I] (wherein R1 is an 1-8C alkyl group or a 6-12C aryl group, a 7-12 aralkyl group, R2 is a hydrogen atom, an 1-15C alkyl group a nitro group or a halogen atom and R3 is a hydrogen atom, an 1-12C alkyl group a 7-12C aralkyl group, a nitro group, a halogen atom or an 1-4C alkoxy group) is contained in a microcapsule containing an almost colorless electron donating dye. The use amount of the diphenylamine derivative is pref. 10-300% by wt. of a color former to be used.

Description

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

(Prior art) A pressure-sensitive recording sheet supports a microcapsule layer containing microcapsules made by dissolving a nearly colorless electron-donating dye (hereinafter referred to as a coloring agent) in an appropriate solvent and encapsulating oil droplets therein. A top paper coated on a support, a bottom paper coated with a developer layer containing an electron-accepting compound (hereinafter referred to as a developer) on another support, and in some cases one side of the support. A combination of paper sheets coated with a microcapsule layer on one side and a color developer layer on the other side, or a support containing the capsules and a color developer on the same side, or There are some that contain either the capsule or the color developer described above and are coated with the other.

These pressure-sensitive recording papers are disclosed in, for example, US Pat. 03, 4t♂ri issue, same co.

110, ≠ No. 71, same, 730. ≠No. 37, same! ,
! 111. ．． It is described in No. 2!0 etc.

However, these pressure-sensitive recording sheets have the following practically serious drawbacks.

(1) The light resistance of the microcapsule layer containing the color former is insufficient. ...The color development property decreases due to light irradiation of the microcapsule layer.

(2) The light resistance of the coloring material is insufficient. ...The density of the coloring body decreases when the coloring body is irradiated with light.

With regard to improving the light resistance of color formers for pressure-sensitive recording sheets, it is known to use hydrogen quinoline derivatives, p-phenylenediamine derivatives, and the like.

However, even when these compounds were used, the effect of improving the light resistance of the color former was insufficient. Furthermore, these metal compounds have little effect on improving the light resistance of the microcapsule layer.

(Object of the Invention) An object of the present invention is to provide a pressure-sensitive recording sheet in which the light resistance of the microcapsule layer containing a color former and the light resistance of a color former are significantly improved.

(Structure of the Invention) The object of the present invention is achieved by a pressure-sensitive recording sheet characterized by containing a diphenylamine derivative represented by the following general formula CI in microcapsules containing an almost colorless electron-donating dye. Ta.

(In the formula, R1 is an alkyl group having a carbon atom number/~t, an aryl group having a carbon atom number 6 to 7.2, or an aralkyl group having a carbon atom number/~t, or an aralkyl group having a carbon atom number/~t). R2 is a hydrogen atom, a carbon atom number/- /1 alkyl group,
The nitro group or halogen atom R3 is a hydrogen atom, an alkyl group having 7 to 7.2 carbon atoms, a nitro group, a halogen atom,
Or it represents an alkoxy group having carbon number/-1. ) In the above general formula [I], R1 is preferably a methyl group, an ethyl group, an isopropyl group, or a benzyl group, and R2 is preferably a methyl group, an ethyl group, an isopropyl group, or a chlorine atom, and R3 is a hydrogen atom, a methoxy group, a benzyloxy group, or A chlorine atom is preferred.

Specific examples of these compounds are (+) 2-methyl-goomethoxy diphenylamine (I+) -2-methyl-gooethoxy diphenylamine (Il+) 2-ethyl-l-methoxy diphenylamine (lv) +2-ethyl-l-ethoxy diphenylamine (v) -2-isopropyl-goomethoxy diphenylamine (vl) 2-isopropyl-goomethoxy diphenylamine (vli) -2-chloro-goomethoxy diphenylamine (vitD, 2-methyl-gooisopropoxy diphenylamine (iX) u-chloro-Hiro'- Methoxy diphenylamine (X) -2-methyl-V'-ethoxy diphenylamine (Xi) μmchloro-≠'-methoxy diphenylamine (xii) -2-methoxy diphenylamine (xlii)≠, ri'-dimethoxy Diphenylamine (XIV) 3-benzyloxy-≠'-methoxy diphenylamine (XV) μm methoxy diphenylamine (xvl)
p-ethoxy diphenylamine (xvil) 'I-
Impropoxy diphenylamine (xv+ii) 4
Examples include t-benzyloxy diphenylamine.

The preferred amount of the diphenylamine derivative used is 10 to 300% by weight of the color former used, more preferably 0 to 200% by weight of the color former.
Weight%.

The diphenylamine derivative can be added by dissolving it in an organic solvent solution of a color former, microcapsulating this solution, and applying it to a support.

The coloring agent used in the distribution sheet of the present invention is not particularly limited, but specific compounds of these coloring agents are as follows:
Examples include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, spiro compounds, and mixtures thereof.

These color formers are dissolved in a solvent, 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, paraffin, naphthenic oil, alkylated biphenyls, alkylated terphels, chlorinated 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, starch particles, talc, etc. is added to obtain a color former-containing microcapsule coating solution.

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

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

The performance of the microcapsule sheet for pressure-sensitive recording 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, 11 parts of calcium carbonate, and 3 parts of calcium carbonate.
．． ! - J parts of zinc di-alpha-methylbenzylsalicylate were added and mixed, and then the carboxy-modified SBR latex was added to the liquid, which was dispersed for 30 minutes using an attritor, at a solid content of 2.5
and 10 wt% PVA (degree of saponification 99% degree of polymerization 1000
) Aqueous solution/j part was added and stirred uniformly to prepare a coating liquid. Spread this coating liquid on the base paper of J OjE / 77L2.
/ rn2 solid content was coated using an air knife coater and dried to obtain a developer sheet.

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

The invention is not limited to the examples.

Examples 1 to 11 Part of polyvinylbenzenesulfonic acid adjusted to pH+) IJum salt (average molecular weight zoo, ).

OO) Spread, add one part of crystal/9 iolet lactone and one part of the diphenylamine derivative shown in Table 1 to one part of μ aqueous solution, and add one part of l-phenyl-7-xylylethane.
The color forming agent oil dissolved in the liquid was emulsified and dispersed, and the average particle size was 1. jμ
An O/W emulsion was obtained. Separately, 3 parts of melamine
71 parts of formaldehyde aqueous solution and 3 parts of water were added to
After heating and stirring at 0°C for 30 minutes, a transparent mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate was obtained. This mixed aqueous solution was added to the above emulsion and mixed, and the pH was adjusted to 4.0 with a 20% acetic acid aqueous solution while stirring. o, raise the liquid temperature to J, t'C and 30
The encapsulation was completed after holding for a minute.

To this liquid, 200 parts of a 17% aqueous solution of etherified starch,
Starch particles (average particle size goμ), guar parts and 10 parts of talc were added.

Then, water was added to adjust the solid content concentration to 20% to prepare a microcapsule liquid.

Dry this microcapsule liquid and weigh it! the law of nature/? 712
The mixture was coated onto ≠0R/rrL2 base paper using an air knife coater and dried to obtain a microcapsule sheet.

Comparative Example Instead of the color former oil in Example, 10 parts of crystal violet lactone was added to l-phenyl-l-xylylethane.
A comparative microcapsule sheet was obtained in the same manner as in the example except that a color former oil dissolved in 0 parts was used.

Comparative test (1) Light resistance of microcapsule layer Example and comparative microcapsule sheet (7)? Microcapsule layer was tested using a fluorescent lamp fading tester (33,0001ux)
) After irradiating for 1 hour, layer it on a developer sheet and J 0
A load pressure of 0 kg/cm2 was applied to develop color. In the dark 2
After the sample was left for a long time, the spectral absorption curve of the coloring body was measured at a wavelength of 310 to 710 nm, and the density at the maximum absorption was measured.

Separately, non-irradiated Example and Comparative microcapsule sheets were stacked on a color developer sort, and a load of 300/9/crn2 was applied to develop color. After leaving it in the dark for 2+ hours,
The spectral absorption curve of the chromophore between wavelengths 30 to 710 nm was measured, and the concentration at the absorption maximum (fresh concentration (Do)) was measured.
) was measured.

The measurement of the spectral absorption curve was carried out using Hitachi Color Analyzer 307.
Table 7 shows the light fastness values determined using the following formula using a mold.

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

(Z) Light resistance of color formers The microcapsule sheets of Examples and Comparative were stacked on a developer sheet and a load of JOOKg/crn2 was applied to develop color. After leaving it for 24 hours in a dark place, the wavelength of 310
The spectral absorption curve of the chromophore between 7rOnm and 7rOnm was measured, and the concentration at the absorption maximum (fresh concentration (Do)) was measured.

This coloring material is measured using a xenon fade meter (Suga Test Instruments,
After irradiating with FAT, -1tAX-HC type) for 1 hour, the spectral absorption curve of the color former was measured, and the concentration at the absorption maximum (
D) was measured.

The measurement of the spectral absorption curve was carried out using a Hitachi Color Analyzer Model 30, and the original durability values obtained using the following formula are shown in Table 1.

After xenon fade meter irradiation: Density at maximum absorption (D) Lightfastness value = Fresh density at maximum absorption (Do) The larger the lightfastness value, the better the lightfastness of the coloring material.

As shown in Table 1, it can be seen that the microcapsule sheet of the present invention is superior to the comparative microcapsule sheet in the light resistance of the microcapsule layer and the light resistance of the color former.

-l　dar

Claims (1)

[Scope of Claims] A pressure-sensitive recording sheet characterized by containing a diphenylamine derivative represented by the following general formula [I] in microcapsules containing an almost colorless electron-donating dye. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, R_1 is an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms R_2 is a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, a nitro group, or a halogen atom R_3 is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a nitro group, a halogen atom , or represents an alkoxy group having 1 to 4 carbon atoms.)