Stock material or miscellaneous articles – Composite – Of polyamide
Patent
1991-12-12
1993-10-12
Ryan, Patrick J.
Stock material or miscellaneous articles
Composite
Of polyamide
428195, 428216, 4284735, 4284752, 4284774, 4284782, 428480, 428913, 428914, B32B 900
Patent
active
052524060
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a receiving support intended to receive, via transfer and thermal fixing, pigments such as those contained in electrostatic toners.
One uses, currently, for overhead projections transparent sheets of a flexible plastic material which may be prepared by various means, for example special pencils. It is also very desirable to be able to use electrostatic copying means. Sheets capable of being printed by electrostatic copying exist, but they are, most often, expensive and not universal, that is to say adapted to a given photocopier.
Another application in which one uses electrostatic toners, transferred and thermally fixed on a support, is magnetography. In this case, also, it may be desirable to have available a plastic material support on which the pigments can be transferred, for example to print bar codes.
In all the cases, these supports must have certain qualities: they must permit a good transfer of pigments; the latter must adhere firmly to the support; finally, in the case where one uses it for overhead projection, the support must maintain a transparent appearance.
The supports of prior art are, in general, constituted of a support film and a receiving layer formed of a hydrophobic material which may be chosen from among a wide range of polymers or copolymers.
U.S. Pat. No. 4,259,422 describes a transparent sheet containing a receiving layer formed of a hydrophilic material such as gelatin. This receiving layer contains, in addition, a hardener and matting beads and it adheres to the support via the intermediary of a sub. U.S. Pat. No. 3,549,360 described a transparent sheet of a polymeric material treated with a surface-active agent. The polymeric material support had undergone a prior polishing treatment which renders it shiny like a mirror.
Surface-active agents have been used in transparent sheets for electrostatic copying, like an antistatic agent, to prevent, in particular, the sheets from sticking to one and other upon stacking. Likewise, U.S. Pat. Nos. 4,071,362, 4,415,626 and 4,526,847 describe the use of such surface-active agents. They are always associated with polymeric receiving layers, or used as a backing layer as in the previously cited U.S. Pat. No. 4,259,422.
In all these documents, the surface-active agent is added in low quantities with respect to the binder of the receiving layer.
The present invention has as its subject-matter a support for thermal transfer of electrostatic toner pigments capable of being used in any system functioning with such pigments, such as electrophotography and magnetography; this support exhibits the characteristics of transfer, transparency and adhesive strength mentioned above, and is inexpensive.
One has found, surprisingly, that contrary to the receiving layers of prior art which always contains either hydrophilic or hydrophobic polymers, or their mixtures, with possibly a surface-active agent of which the concentration is lower than that of the polymer, one could obtain supports of excellent quality for pigment transfer, permitting a good fixing of the pigments, with altering the transparency, if that is desired, with a receiving layer constituted of a surface-active agent associated with a very low concentration of hydrophilic binder, the surface-active agent concentration being at least 2 times higher than that of the hydrophilic binder.
The present invention has as its subject-matter a support for thermal transfer of electrostatic toner pigments, constituted of a base and a receiving layer for the pigments, characterized in that the receiving layer is formed of a hydrophilic binder and of a surface-active agent, of which the concentration is at least 1 mg/dm.sup.2 and is at least 2 times higher than that of the hydrophilic binder.
In a preferred embodiment, the surface-active agent concentration is at least 5 times higher than that of the hydrophilic binder, and even more favorably, the surface-active agent concentration is more than 10 times higher than that of the hydrophilic binder.
It is advantageous that the
REFERENCES:
patent: 4168338 (1979-09-01), Kato et al.
patent: 4370379 (1983-01-01), Kato et al.
patent: 4956225 (1990-09-01), Malhotra
patent: 5055371 (1991-10-01), Lee et al.
Eid Bernard A.
Rigola Jeannine
Eastman Kodak Company
Krynski William
Montgomery Willard G.
Ryan Patrick J.
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