Fluoran compounds, intermediates and color forming recording mat

Details Fluoran compounds, intermediates and color forming recording mat Fluoran compounds, intermediates and color forming recording mat

1996-08-22

1998-04-14

Raymond, Richard L.

Record receiver having plural interactive leaves or a colorless

Having a colorless color-former, developer therefor, or...

Identified organic electron acceptor other than phenolic resin

503220, 503221, 503223, 546 15, 548407, 549225, C07D49310

Patent

active

057390789

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/JP95/02096, filed Oct. 13, 1995.


FIELD OF THE INVENTION

The present invention relates to fluoran compounds effectual as a color forming dyestuff to be used for color forming recording materials, such as thermal recording papers and pressure sensitive copying papers.


BACKGROUND ART

Today, the recording materials based on a color forming mechanism being composed of a reaction of a color former, which itself is colorless or with little color but forms color by reactions with a developer, and a developer to react with said color former to form color, have been widely used for pressure sensitive copying papers, thermal recording papers, etc. For such color forming dyestuffs, fluoran compounds have been mainly used, which can form various tones of color, such as black, green, red, blue, etc., respectively, depending upon the substituent contained in each of the fluoran compounds. Furthermore, some of the fluoran compounds can absorb even near infrared rays.
Recently, due to expanding use of thermal recording papers, opportunities to use thermal recording papers while exposing them to severe natural condition, has been increased. For this reason, an excellent property to preserve color-formed images on the papers and the background of the papers in good condition is requested for the fluoran compounds, however, there is no such compound capable of complying with such property. In case of thermal recording papers, therefore, the efficiency of the recording materials have been improved by using a composition added with a sensitizer for improving the sensitivity, an plasticity resistant agent for improving the preservability, an antioxidant, an ultraviolet rays absorbing agent, etc., other than the fluoran compound as the essential color former and the developer to react with the color former to form color. Furthermore, the means to improve the preservability of the papers by providing protective and intermediate layers to protect the color forming layer has been also carried out.
In Japanese Patent Laid-opened No. Sho 63-156790 Gazette, which has been filed by the applicant for the present invention, compounds having a chemical structure similar to the fluoran compounds of the present invention are disclosed, and the fluoran compounds of the present invention are contained in the scope of the claims of the said Gazette but are not specifically described therein.
For recording materials, particularly thermal and pressure sensitive recording papers, there is a problem in their photostability, namely the capability to preserve whiteness of the background of the papers after exposed them to light and the durability against discoloration of color-formed images thereon. In this respect, fluoran compounds previously known have disadvantages that those are unstable to light and decompose thereunder. Because of these disadvantageous properties, previous thermal recording papers tend to have problems that those do not form color even after giving heating or the density of color-formed images get very thin, when those have once been exposed to light. Therefore, it was obligatory to store such thermal recording papers in a dark place, since the color forming capability of such recording papers remarkably deteriorate in case those have once been exposed to light.
In the Japanese Patent Laid-opened No. Sho 63-156790 Gazette mentioned above, the recording material which has excellent photostability, particularly the one that does not result in discoloration of color-formed images on the materials due to light, is disclosed, however, there is no description therein on the color forming capability of the recording material after exposed it to light.
As described in the above, no fluoran compounds having satisfactory efficiency required for the color forming dyestuff has been found yet. Therefore, it is an object of the present invention to provide an recording material which has excellent properties in preservability to keep whiteness of the background of the recording material under light, in

REFERENCES:
patent: 4954631 (1990-09-01), Obitsu et al.

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