Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Having constituent defined in terms of melting temperature
Reexamination Certificate
2001-12-06
2004-06-15
Hess, B. Hamilton (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Having constituent defined in terms of melting temperature
C503S216000
Reexamination Certificate
active
06750174
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat sensitive recording material, and particularly to a heat sensitive recording material which has high degree of color formation and excellent storability.
2. Description of the Related Art
Heat sensitive materials, in which an image is recorded by, for example, a thermal head applying heat, are relatively inexpensive. Furthermore, image recording devices for such heat sensitive materials are simple, highly reliable, and need no maintenance. For these reasons, heat sensitive recording materials have been widely used in recent years.
There has thus been a strong demand recently for heat sensitive recording materials of higher performance such as higher image quality and improved storability in particular. Intensive research on the degree of color formation, image quality, and storability of the heat sensitive recording materials has been carried out.
For example, Japanese Patent Application Laid-Open (JP-A) No. 11-342676 discloses a heat sensitive recording body which contains 2,4-bis(phenylsulfonyl) phenol as a color agent (an electron accepting compound) causing color reaction with a leuko dye, is highly sensitive, and has excellent storability in recording portions (i.e., image portions). Although excellent in terms of storability (plasticizer resistance, water resistance, and oil resistance), the heat sensitive recording body has problems of storage stability (such as fog density and contrast of an image) in non-image portions (i.e., background portions).
As described above, at present, a heat sensitive recording material with which an image of high density is obtained, and which has excellent image storability (such as excellent plasticizer resistance, water resistance, and resistance to solvents) in image portions and excellent storage stability in non-image portions (background portions), has high whiteness, and can stably maintain an image of high contrast for a long period of time has not been provided.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described problems and achieve the following object.
Namely, an object of the present invention is to provide a heat sensitive recording material which has high sensitivity, high degree of color formation, and excellent storage stability (such as plasticizer resistance (resistance to solvents), water resistance, and heat resistance) in both image and non-image portions, has background portions of high whiteness, and can stably maintain an image of high contrast for a long period of time.
A first aspect of the present invention is a heat sensitive recording material which has, on a support, a heat sensitive color-forming layer having an electron donating colorless dye and an electron accepting compound, wherein at least one type of the electron accepting compound is 2,4-bis(phenylsulfonyl) phenol, and the heat sensitive color-forming layer also has 2-naphthylbenzyl ether and an amide compound as thermally fusible substances.
A second aspect of the present invention is a heat sensitive recording material wherein the content of an amide compound is 2 to 100 parts by mass with respect to 100 parts by mass of 2-naphthylbenzyl ether.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A heat sensitive recording material of the present invention has at least a heat sensitive color-forming layer on a support. The heat sensitive color-forming layer has 2,4-bis(phenylsulfonyl) phenol as an electron accepting compound, and 2-naphthylbenzyl ether and an amide compound as thermally fusible substances.
Hereinafter, the heat sensitive recording material of the present invention will be described in detail.
The heat sensitive recording material of the present invention has at least a heat sensitive color-forming layer on a support. The heat sensitive recording material may have a plurality of heat sensitive color-forming layers laminated on the support, and may have other layers such as an undercoat layer, or a protective layer, for example, as needed.
Heat Sensitive Color-Forming Layer
The heat sensitive color-forming layer has an electron donating colorless dye, an electron accepting compound, and thermally fusible substances. The heat sensitive color-forming layer may have other thermally fusible substances, image stabilizers and other such components as needed.
In the present invention, by the heat sensitive color-forming layer including 2,4-bis(phenylsulfonyl) phenol as the electron accepting compound, an image having high sensitivity and high degree of color formation is obtained. Further, by using 2-naphthylbenzyl ether and an amide compound which serve as the thermally fusible substances together with 2,4-bis(phenylsulfonyl) phenol, storage stability (including plasticizer resistance (resistance to solvents), water resistance, and heat resistance) in both image portions (i.e., color forming portions) and non-image portions (i.e., background portions) can be simultaneously improved. Accordingly, a high-density image can be obtained. Further, an image having excellent whiteness in background portions and having high contrast can be stably maintained for a long period of time.
Electron Accepting Compound
As described above, the heat sensitive recording material of the present invention contains 2,4-bis(phenylsulfonyl) phenol as an electron accepting compound which acts on the electron donating colorless dye to be described later, to form a color.
Other well-known electron accepting compounds may be used together with 2,4-bis(phenylsulfonyl) phenol as long as the effects of the present invention are not compromised.
The well-known electron accepting compounds can be appropriately selected in accordance with the purpose of the invention or the like. However, in order to suppress fog in background portions in particular, phenol compounds, or salicylic acid derivatives and salts of polyvalent metal thereof are preferable.
Examples of the phenol compounds include 2,2′-bis(4-hydroxyphenol) propane (bisphenol A), 4-t-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, 1,1′-bis(4-hydroxyphenyl) cyclohexane, 1,1′-bis(3-chloro-4-hydroxyphenyl) cyclohexane, 1,1′-bis(3-chloro-4-hydroxyphenyl)-2-ethyl butane, 4,4′-sec-isooctylidenediphenol, 4,4′-sec-butyrylene diphenol, 4-tert-octylphenol, 4-p-methyphenylphenol, 4,4′-methylcyclohexylidenephenol, 4,4′-isopentylidenephenol, and p-hydroxybenzyl benzoate.
Examples of the salicylic acid derivatives include 4-pentadecylsalicylic acid, 3-5-di(&agr;-methylbenzyl) salicylic acid, 3,5-di(tert-octyl) salicylic acid, 5-octadecylsalicylic acid, 5-&agr;-(p-&agr;-methylbenzylphenyl) ethylsalicylic acid, 3-&agr;-methylbenzyl-5-tert-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, and zinc, aluminum, calcium, copper, and lead salt thereof.
The total amount of the electron accepting compound is 50 to 500% by mass, and preferably 100 to 300% by mass, of the content (mass) of the electron donating colorless dye.
Further, when the well-known electron accepting compounds described above are used together with 2,4-bis(phenylsulfonyl) phenol in the present invention, the content of 2,4-bis(phenylsulfonyl) phenol according to the present invention is preferably 50% by mass or more, and particularly preferably 70% by mass or more, of the total amount of the electron accepting compounds.
The electron accepting compound is included in a coating solution for forming the heat sensitive color-forming layer. When the coating solution is prepared, the electron accepting compound is preferably used as a solid dispersion in a solvent.
In this case, the volume average particle diameter of the particles (i.e., the electron accepting compound) dispersed in a dispersion having the electron accepting compound is preferably 0.5 to 1.5 &mgr;m, and more preferably 0.5 to 1.0 &mgr;m. A volume average particle d
Mitsuo Hirofumi
Watanabe Tsutomu
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