Method of forming a positive image through infrared exposure utilizing diazonaphthoquinone imaging composition
AssigneeKodak Polychrome Graphics LLC
InventorsEugene Lynn Sheriff, Ralph Scott Schneebeli
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Abstract
An infrared imaging composition contains two essential components, namely an infrared absorbing compound, and a phenolic resin that is either mixed or reacted with an o-diazonaphthoquinone derivative. These compositions are useful in positive-working elements such as lithographic printing plates that can be adapted to direct-to-plate imaging procedures. The weight ratio of infrared radiation absorbing compound to diazonaphthoquinone moiety is less than 1:14.
Claims20
A method of providing forming a positive image, the method comprising the steps of:
- A) without a prior or a simultaneous floodwise exposure, imagewise exposing with infrared radiation an imaging layer of an imaging element, and forming image areas in said imaging layer;
- and
- B) contacting said element with an aqueous developing solution and removing said image areas of said imaging layer;
- wherein:
- said imaging element comprises a support having thereon said imaging layer;
- said imaging layer comprises:
- a) (i) a mixture of a phenolic resin and an o-diazonaphthoguinone derivative,
- (ii) a reaction product of a phenolic resin and an o-diazonaphthoguinone reactive derivative, or
- (iii) a mixture of (i) and (ii);
- and
- b) a compound that absorbs infrared radiation, said compound having a maximum absorption wavelength greater than 750 nm;
- the dry weight ratio of said infrared absorbing compound b) to the o-diazonaphthoguinone moiety in said mixture (i) and in said reaction product (ii) is less than 1:14;
- and
- said imaging layer is the outermost layer of said element.
A method of forming a positive image, the method comprising the steps of:
- A) without a prior or simultaneous floodwise exposure, imagewise exposing with infrared radiation an imaging layer of an imaging element, and forming image areas in said imaging layer;
- and
- B) contacting said element with an aqueous developing solution and removing said image areas of said imaging layer;
- wherein:
- said imaging element comprises of a support having thereon said imaging layer;
- said imaging layer consists essentially of:
- a) (i) a mixture of a phenolic resin and an o-diazonaphthoquinone derivative,
- (ii) a reaction product of a phenolic resin and an o-diazonaphthoquinone reactive derivative, or
- (iii) a mixture of (i) and (ii);
- and
- b) a compound that absorbs infrared radiation, said compound having a maximum absorption wavelength greater than 750 nm;
- c) optionally, a non-photosensitive dissolution inhibitor compound having an inhibition factor of at least 0.5;
- and
- d) optionally, one or more components selected from the group consisting of colorants, sensitizers, stabilizers, exposure indicators, and surfactants;
- said imaging layer is the outermost layer of said element;
- the dry weight ratio of said infrared absorbing compound b) to the o-diazonaphthoquinone moiety in said mixture (i) and in said reaction product (ii) is less than 1:14;
- and
- there is no floodwise exposure between step A) and step B).
Dependencies are inferred from the claim text.