JP2000052669A - Thermosensitive image forming element for lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming element for manufacturing a lithographic printing plate for giving an excellent print with negative operability without necessity of dissolving. SOLUTION: The thermosensitive image forming element for a lithographic printing plate comprises a support, and a thermal switchable image forming layer containing hyrophilic binder formed as a hard film at an uppermost layer, the uppermost layer or a layer adjacent to the uppermost layer contains a compound for converting a light into a heat, and a thermally switchable polymer contains an aryldiazosulfonate unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION This invention relates to heat-sensitive imaging elements.

More specifically, the present invention relates to a heat-sensitive imaging element that does not require a dissolution treatment and that produces a wasteless image for making a lithographic printing plate.

[0003]

BACKGROUND OF THE INVENTION Lithographic printing is a method of printing from a specially made surface in which some areas can receive lithographic printing ink, while others do not receive the ink when wetted with water. It is. The ink receiving area defines the printed image area, and the ink-repellent area defines the background area.

In the field of photolithographic printing, photographic materials are image-wise oily or greasy on a hydrophilic background, in exposed areas (negative-working) or in unexposed areas (positive-working). Receptive to ink.

[0005] Surface lithographic printing plate (surface lit)
ho plates) or planographic printing plates (pl
ananographic printing plate
In the preparation of conventional lithographic printing plates, also referred to as s), a thin layer of the photosensitive composition is coated on a support that has an affinity for water or obtains such an affinity by chemical treatment. Coatings for that purpose include photopolymer layers containing diazo compounds, dichromate-sensitized hydrophilic colloids and various synthetic photopolymers. In particular, diazo-sensitized systems are widely used.

When the photosensitive layer is image-wise exposed, the exposed image areas become insoluble and the non-exposed areas remain soluble. The plate is then developed using a suitable solution to remove the diazonium salt or diazo resin in unexposed areas.

[0007] In another case, printing plates are known that contain a photosensitive coating that, when exposed imagewise, renders the exposed areas soluble. In that case, subsequent development removes the exposed areas. A typical example of such a photosensitive coating is a quinone-diazide based coating.

[0008] Typically, the above photographic material from which the printing plate is made is contacted and exposed through a photographic film containing the image to be reproduced in a lithographic printing process. Such work practices are cumbersome and labor intensive. On the other hand, however, the printing plates thus obtained are of excellent lithographic printing quality.

[0009] Thus, attempts have been made in the above process to eliminate the need for photographic film and in particular to obtain a printing plate directly from computer data representing the image to be reproduced. However, the above photosensitive coatings are not sensitive enough to be directly exposed to the laser.
It has therefore been proposed to coat a silver halide layer over the photosensitive coating. The silver halide can then be directly exposed using a laser under computer control. The silver halide layer is subsequently developed to leave a silver image on the photosensitive coating. The silver image then serves as a mask in the overall exposure of the photosensitive coating. After overall exposure, the silver image is removed and the photosensitive coating is developed. Such a method is, for example, JP
-A-60-61 752, but has the disadvantage of requiring complex development and the accompanying developer.

GB-1 492 070 discloses a method of providing a metal layer or a layer containing carbon black on a photosensitive coating. Next, the metal layer is ablated using a laser to obtain an image mask on the photosensitive layer. The photosensitive layer is then entirely exposed by UV-light through an image mask. After removing the image mask, the photosensitive layer is developed to obtain a printing plate. However, this method still has the disadvantage that the image mask must be removed by a cumbersome process before development of the photosensitive layer.

Furthermore, methods are known for making printing plates that involve the use of imaging elements that are heat-sensitive rather than light-sensitive. A particular disadvantage of the photosensitive imaging element as described above for the preparation of a printing plate is that it must be shielded from light. Furthermore, they have sensitivity problems in terms of storage stability, and they exhibit relatively low dot crispness. There is a clear trend in the market towards heat mode printing plate precursors.

EP-A-444 786, JP-63-
208036 and JP-63-274592 disclose photosensitive resin resists sensitized to near IR. To date, none has proven to be commercially viable and all require wet development to wash away unexposed areas. EP-A-514 145 is a laser addressed plate (laser addressed plate).
te), in which the heat generated by the laser exposure melts and fuses the particles in the coating of the plate, thus changing their melting properties. In this case also, wet development is required.

US-P-3 787 210, US-P
No. 3,962,513, EP-A-001 068 and JP-04-140191 disclose somewhat different methods. The heat generated by laser exposure of the donor sheet is used to physically transfer the resinous material from the donor to an acceptor held in close contact with the donor. If the receptor surface has suitable hydrophilicity, it can then be used as a printing plate. Although this method has the advantage of not requiring a wet process, a high power YAG (or similar) laser is required to achieve a practical write time, which has limited the usefulness of the method. Was.

On the other hand, polymer coatings whose surface properties change in response to exposure are known in the art. WO-92 / 09934 discloses an imaging element that includes a coating that becomes hydrophilic as a result of irradiation. The coating comprises an acid-sensitive polymer and a source of a strong photochemical acid, in which case the preferred acid-sensitive polymer is derived from a cyclic acetal ester of acrylic or methacrylic acid, such as tetrahydropyranyl (meth) acrylate.

WO-92 / 02855 blends an acid-sensitive polymer with a low-Tg polymer, which is initially non-tacky but phase separates when irradiated as a result of chemical conversion of the acid-sensitive polymer; It is disclosed that the resulting coating becomes tacky. The possibility of laser exposure is mentioned, but no details are given and there is no disclosure of IR-sensitivity, only UV / visible. However, the same material is 1993 IS

& T / SPIE Conference
e, Symposium on Electronic
"Advan," presented as paper 1912-36 in Science and Technology.
ces in Phototackificatio
n ", which is the subject of a photoacid generator.
It is further disclosed that or can be replaced by an IR dye, specifically a squarylium dye having thiopyrylium end groups, and that exposure can be performed using a diode laser device. The dyes in question are not known to have acid-forming properties. This method is the subject of U.S. Pat. No. 5,286,604.

WO-92 / 09934 discloses that acid-sensitive polymers can optionally be blended with one or more photoacid generators. U
After image-wise exposure to V / visible radiation, the exposed areas are preferentially wettable by water and the coating can act as a lithographic printing plate without the need for wet processing. There laser address (laser address)
There is no disclosure of s).

WO-92 / 2855 blends an acid-sensitive polymer with a low Tg polymer and is initially non-tacky, but when irradiated, undergoes phase separation as a result of chemical conversion of the acid-sensitive polymer, It is disclosed that the resulting coating has a positive effect. The possibility of laser exposure is mentioned but no details are given and there is no disclosure of IR-sensitization, only UV / visible. However, the same material is available in 1993 IS & T / SPIE Conferen.
ce, Symposium on Electroni
c "Adva, presented as paper 1912-36 in Science and Technology.
nces in Phototackificatio
n ", where the photoacid generator can be replaced by an IR dye (specifically a squarylium dye with thiopyrylium end groups), and the exposure can be performed using a diode laser device. It is further disclosed that the dyes in question are not known to be acid-forming.
This method is the subject of U.S. Pat. No. 5,288,604.

EP-A-652 483 discloses a lithographic printing plate which does not require a dissolution treatment, which comprises a substrate carrying a heat-sensitive coating, which coating becomes relatively more hydrophilic under the action of heat. Become. The system gives a positive working printing plate. A similar but negative working printing plate system is not known.

[0020] EP-A-507 008 provides homopolymers and copolymers containing aryldiazosulfonate units and having a maximum spectral sensitivity at or above 320 nm. These polymers are particularly suitable for making printing plates.

US Pat. No. 5,713,287 discloses a printing plate containing a hydrophobic polymer which, when heated, turns into a hydrophilic polymer in admixture with an infrared dye.

GB-A-1 195 841 is a heat-generating device comprising a support and at least one layer containing a radiation-to-heat converting substance and a thermally decomposable polymer containing recurring units linked by azo groups. An objective imaging element is disclosed.

[0023]

OBJECTS OF THE INVENTION It is an object of the present invention to provide an imaging element for the preparation of a lithographic printing plate which does not require a dissolution treatment and is negative-working.

It is also an object of the present invention to provide an imaging element for making a lithographic printing plate which requires no dissolution treatment, exhibits excellent ink absorption in exposed areas and has no scum in unexposed areas. That is.

Further objects of the present invention will become clear from the description hereinafter.

[0026]

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a support and a thermally switchable imaging layer containing a hardened hydrophilic binder and a thermally switchable polymer as a top layer,
A lithographic printing plate wherein the top layer or a layer adjacent to the top layer comprises a compound capable of converting light to heat; wherein the thermally switchable polymer is a polymer containing aryldiazosulfonate units. A heat-sensitive imaging element for providing is provided.

[0027]

DETAILED DESCRIPTION OF THE INVENTION Imaging layers that become more hydrophobic under the influence of heat include a heat-switchable binder, a compound capable of converting light to heat, and a hardened hydrophilic binder. Heat-switchable binders are polymers or copolymers that undergo a polarity change from hydrophilic to hydrophobic or vice versa under the influence of heat. According to the invention, a switchable binder is used that is hydrophilic before heating and becomes hydrophobic upon heating. This difference in surface polarity is sufficient for making classical offset printing plates. Switchable binders according to the present invention are polymers or copolymers containing aryldiazosulfonate units. The photosensitive polymer having aryldiazosulfonate units, also called aryldiazosulfonate resin, preferably has the formula:

[0028]

Embedded image [Wherein R ⁰ , ¹ and ² each independently represent hydrogen, an alkyl group, a nitrile or a halogen such as Cl, and L represents 2
And n represents 0 or 1, A represents an aryl group, and M represents a cation.] Is a polymer having an aryldiazosulfonate unit. L is preferably ^{_{:-( X) t -CONR 3 -,}} - (X) t -CO
O -, - X- and - (X) represents a divalent linking group selected from the group consisting of _t -CO-, wherein t represents 0 or 1, R ³ is hydrogen, an alkyl group or an aryl group X
Is an alkylene group, an arylene group, an alkylenoxy group, an arylenoxy group, an alkylenethio group, an arylenethio group, an alkyleneamino group, an aryleneamino group, oxygen,
Indicates a sulfur or amino group. A preferably represents an unsubstituted aryl group, for example an unsubstituted phenyl group or an aryl group substituted by one or more alkyl, aryl, alkoxy, aryloxy or amino groups, for example phenyl. M is preferably a cation or metal ion such as NH 4 ⁺ , for example Al, Cu, Z
n represents a cation of an alkaline earth metal or an alkali metal.

Polymers having aryldiazosulfonate units are preferably obtained by radical polymerization of the corresponding monomers. Suitable monomers for use in accordance with the present invention are EP-A-339 393 and EP-A-507 0
08. Specific examples are as follows.

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image Homopolymerizing an aryldiazosulfonate monomer as disclosed above or other aryldiazosulfonate monomers and / or vinyl monomers,
For example, (meth) acrylic acid or its ester, (meth) acrylamide, acrylonitrile, vinyl acetate,
It can be copolymerized with vinyl chloride, vinylidene chloride, styrene, alpha-methylstyrene and the like. However, in the case of copolymers, care must be taken not to impair the water solubility of the polymer. Preferably, the amount of aryldiazosulfonate-containing units in the copolymer related to the present invention is between 10 mol% and 60 mol%.

According to another embodiment related to the present invention,
For example, an aryldiazosulfonate-containing polymer can be produced by reacting a polymer having an acid group or an acid halide group with an amino- or hydroxy-substituted aryldiazosulfonate. Further details regarding this method can be found in EP-A-507008.

Preferably, the aryldiazosulfonate monomer is copolymerized with a monomer containing a reactive group capable of reacting with formaldehyde, glyoxal, polyisocyanate or hydrolyzed tetraalkylorthosilicate.

The image forming layer or a layer adjacent to the image forming layer contains a compound capable of converting light into heat. Suitable compounds capable of converting light to heat are preferably infrared absorbing components, but the wavelength of absorption is provided if the absorption of the compound used is within the wavelength range of the light source used for image-wise exposure. Is not particularly important. Particularly useful compounds are, for example, dyes and especially infrared absorbing dyes and pigments and especially infrared absorbing pigments. Examples of infrared absorbing dyes are EP-
A-97 203 131.4. Examples of infrared absorbing pigments are carbon black, metal carbides, borides, nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze family but without the A component, such as WO. _2.9 . Conductive polymer dispersions, such as those based on polypyrrole or polyaniline, can also be used. The compound capable of converting light to heat is preferably present in the top layer, but can also be included in the layers below.

The compound capable of converting light to heat is preferably present in the imaging element in an amount of from 1 to 2 times the total weight of the imaging layer.
It is present in an amount of 5% by weight, more preferably in an amount of 2 to 20% by weight of the total weight of the imaging layer.

Particularly suitable hardened hydrophilic layers can be obtained from hydrophilic binders which have been crosslinked with a crosslinking agent such as formaldehyde, glyoxal, polyisocyanate or hydrolyzed tetraalkyl orthosilicate. . The latter is particularly preferred.

As the hydrophilic binder, hydrophilic (co) polymers such as vinyl alcohol, acrylamide, methylolacrylamide, methylolmethacrylamide, acrylate acid, methacrylate acid,
Homopolymers and copolymers of hydroxyethyl acrylate and hydroxyethyl methacrylate or maleic anhydride / vinyl methyl ether copolymer can be used. The hydrophilicity of the (co) polymer or (co) polymer mixture used is preferably the same or higher than that of the polyvinyl acetate hydrolyzed to at least 60% by weight, preferably to the extent of 80% by weight.

The amount of crosslinker, especially tetraalkyl orthosilicate, is preferably at least 0.2 parts by weight, more preferably 0.5 to 5 parts by weight, most preferably 1.0 part by weight per part by weight of hydrophilic binder. ３3 parts by weight.

The cross-linked hydrophilic layer used according to this embodiment preferably also contains substances which improve the mechanical strength and porosity of the layer. Colloidal silica can be used for this purpose. The colloidal silica used can be in the form of any commercially available water-dispersion of colloidal silica having, for example, an average particle size of at most 40 nm, for example 20 nm. In addition, inert particles of larger dimensions than colloidal silica, for example J.I. Colloid a
nd Interface Sci. , Vol. 26,
Particles having an average diameter of at least 100 nm, which are silica or alumina particles or particles of titanium dioxide or other heavy metal oxides prepared according to StOEber as described in 1968, pages 62 to 69, can be added. The introduction of these particles gives the surface of the cross-linked hydrophilic layer a uniform rough texture consisting of microscopic hills and valleys, which serves as a storage for water in the background areas.

The image forming layer is preferably 0.1 to 5 g / m
In an amount of ^2, more preferably it is applied in an amount of 0.25~3g / m ^2.

The support can be a hydrophobic support as well as a hydrophilic support, and can be a rigid support as well as a flexible support.

In the imaging element of the present invention, the support can be anodized aluminum. A particularly preferred support is an electrochemically roughened and anodized aluminum support.

According to another embodiment related to this embodiment, the support is a flexible support such as paper or plastic film. It is particularly preferred to use a plastic film as the flexible support in connection with this embodiment, for example, a substrated polyethylene terephthalate film, a cellulose acetate film, a polystyrene film, a polycarbonate film, and the like. The plastic film support can be opaque or transparent.

It is particularly preferable to use a polyester film support provided with an adhesion promoting layer. Particularly suitable adhesion promoting layers for use in accordance with the present invention are EP-A-619.
524, EP-A-620 502 and EP-A-6
Including a hydrophilic binder and colloidal silica as disclosed in US Pat. Preferably the amount of silica in the adhesion improving layer is between m ² per 200Mg～m ² per 750 mg. Further, the ratio of silica to hydrophilic binder is preferably 1
Higher, the surface area of the colloidal silica is preferably at least 300 m ² per gram, more preferably at least 500 m ² per gram.

The imaging element can contain other layers between the support and the top layer, such as a subbing layer and an antihalation layer.

[0048] The imaging element can be manufactured by applying the various layers according to any known method. Alternatively, the imaging element can be manufactured on a printing press, using a support already on the printing press, with one or more coaters located in close proximity to the printing press.

Imaging in connection with the present invention is preferably laser, more preferably infrared or near infrared, ie 700-1.
It is performed using an image-wise scanning exposure that involves the use of a laser operating in the 500 nm wavelength region. Most preferred are laser diodes that emit in the near infrared. Exposure of the imaging element can be performed using a laser having a short pixel dwell time as well as a laser having a long pixel dwell time. Preferred are lasers having a pixel dwell time of 0.005 microseconds to 20 microseconds.

After exposure, the imaging element is ready to be used as a lithographic printing plate.

In another embodiment of the invention, the exposing of the imaging element can be performed using the imaging element already on the printing press. A computer or other source supplies graphics and text information to the printhead or laser via leads.

The printing plate of the present invention can be used in a printing method as a seamless sleeve printing plate. This cylindrical printing plate has a diameter such that it can be slid on the printing cylinder. See “G
rafiche Nieuws ”ed. Keesin
g, 15, 1995, page 4 to 6.

The printing plate of the present invention can be used in a printing method as a seamless sleeve printing plate. Instead of applying a classically produced printing plate in the classical way, this cylindrical printing plate having the diameter of the printing cylinder as the diameter is slid on the printing cylinder. See “G
rafiche Nieuws ”ed. Keesin
g, 15, 1995, page 4 to 6. Following the image-wise exposure, the image-wise exposed imaging element is mounted on the printing cylinder of a printing press using the back side of the imaging element (the side of the support opposite the side having the photosensitive layer). . According to a preferred embodiment, the printing press is then started and the dampening fluid roller and the ink roller supplying the dampening fluid are lowered while rotating the printing cylinder on which the imaging element is mounted.

The following examples illustrate the invention without limiting it. All parts and percentages are by weight unless otherwise indicated.

[0055]

EXAMPLES Example 1 Example 1: TiO2 of -21.5% (average particle size 0.3 to
To 11 g of a dispersion containing 0.4 μm) and 2.5% of polyvinyl alcohol in deionized water, 7.5 g of a solution containing 4% of glyoxal in water with stirring,
33.3 g solution containing 1% IR-1 in water, 6% diazosulfonate copolymer P2 in methanol
0 (20 mol% of diazosulfonate monomer and 80
12.95 g of a solution containing mol% methyl methacrylate) as well as 0.30 g of a 10% solution of the wetting agent were added continuously. PH of this mixture
Was adjusted to pH = 6.8. Coating the resulting dispersion on a polyethylene terephthalate film support (coated with a hydrophilic adhesive layer) to a wet coating thickness of 30 μm and drying at 30 ° C., followed by heating it to a temperature of 67 ° C. and 50% The film was hardened by subjecting to a relative humidity of 12 hours. -The plate is operated with a drum speed of 70 rpm and a laser power of 11 watts C
REO 3244 TRENDSETTER ^TM (Cre
(available from Co., Ltd.) at 2400 dpi. -After imaging, the plate is Va on a GTO 46 printing press
n Son Rubberbase ink and 2% T
Printing with Rotamatic having an ame as a dampening solution gave excellent prints, i.e., prints with excellent ink-absorption in exposed areas and no scum formation in non-exposed areas.

[0056]

Embedded image Example 2-21.5% TiO2 (average particle size 0.3-0.4μ)
m) and 22% dispersion containing 2.5% polyvinyl alcohol in deionized water.
6.05 g solution containing 4% tetramethylorthosilicate emulsion, 6 containing 1% IR-2 in water
0 g solution, 12.5 g solution containing 5% polyvinyl alcohol in water, 30.31 g solution containing 6% diazosulfonate copolymer P20 in methanol and 0.60 g of 10% solution of wetting agent Was added continuously. The pH of this mixture was adjusted to pH = 5.5. 30 μm of the resulting dispersion on an aluminum support
m to a wet coating thickness of 30 m
And then hardened by subjecting it to a temperature of 67 ° C. and 50% relative humidity for 12 hours. -CREO 3244 TRENDSET running this plate at a drum speed of 50 rpm and a laser power of 11 watts
2400 dpi on TER ^™ (available from Creo)
And an image was formed. -After image formation, the plate is GTO4
6. Printing on a printing press using Van Son Rubberbase ink and Rotamatic with 2% Name as dampening solution, excellent print, i.e. excellent ink-absorption in exposed areas, scum formation in non-exposed areas. No prints were obtained.

[0057]

Embedded image Synthesis of diazosulfonate-containing polymer P20 Synthesis of monomer A The azo group-containing material must be protected from light, for example, by darkening the chamber or wrapping the flask with aluminum foil. Reagents were obtained from Fluka and Aldrich and solvents were distilled before use. a) Preparation of three solutions 1 Dissolve 24 g of sodium sulfite and 40 g of sodium carbonate in 250 ml of water. 2 15.02 g p. -10 aminoacetanilides
Dilute in 0 ml of water and 36.8 ml of concentrated HCl (32%) and cool to 0-5 ° C. using a cooling bath. 3 Dilute 6.8 g of sodium nitrite in 15 ml of water.

While cooling (below 5 ° C.) solution 3
And then it is stirred for 10 minutes. After filtration
The solution is rapidly poured into solution 1 under vigorous stirring. The solution is then stirred for 30 minutes. The solution may be red at the start, but after a few minutes the color turns yellow. The solid product is filtered off from the solution and used without further purification. b) Dissolve the product in 150 ml of water and add 8 g of NaOH
And then heat the solution to 50 ° C. for 1 hour before
Cool to ° C. While still cooling, add 19.66 ml of concentrated HCl (32%) to the solution. Then 100ml
33.6 g in 1% picric acid and about 350 ml of water
Pour a solution of sodium carbonate into the mixture. The temperature of the solution must be reduced to below 5 ° C. before adding methacrylic chloride. From the dropping funnel, 15 ml of methacrylic acid chloride are dripped very slowly into the solution (very foaming). It is necessary to stir the mixture at 0-5 ° C. for 1 hour and then at room temperature for another hour. Then 30
0 ml of a saturated solution of sodium acetate is added and the solution is stored in a refrigerator (about 4 ° C.) overnight. The solid product is filtered and 5
Dry at 0 ° C. under vacuum for 17 hours. To remove inorganic salts, the product is dissolved in 150 ml of DMF, stirred at room temperature for at least 2 hours and filtered. The filtrate is poured into 2 l of diethyl ether for precipitation and then filtered. To achieve a very low moisture content (2.5%)
It is necessary to dry at 50 ° C. under vacuum for 3 days. Synthesis of Polymer P20 2.11 g of Monomer 1 are first diluted in 10 ml of water and 3.1 g of methyl methacrylate and 0.300 g of azo-bis-isobutyronitrile and 40 ml of dioxane are added. The solution must be degassed several times to remove oxygen. The solution (protected from light) is then stirred at 70 ° C. for 17 hours. The polymerization is stopped by adding a small amount of hydroquinone, the solvent is evaporated and the polymer is redissolved in 80 ml of methanol. The solution is added dropwise to 2 l of diethyl ether and then dried at 50 ° C. under vacuum over phosphorus pentoxide. After drying for 3 days, a polymer having a moisture content of 2.5% is obtained. The main features and aspects of the present invention are as follows.

1. A support and a thermally switchable imaging layer containing a hardened hydrophilic binder and a thermally switchable polymer as a top layer, wherein the top layer or a layer adjacent to the top layer converts light to heat. A heat-sensitive imaging element for providing a lithographic printing plate, characterized in that the thermally switchable polymer is a polymer containing aryldiazosulfonate units.

2. The above 1 wherein the amount of the aryldiazosulfonate unit in the polymer is 10 mol% to 60 mol%.
Item.

3. 3. The heat-sensitive image-forming element according to the above item 1 or 2, wherein the compound capable of converting light into heat is an infrared absorbing component.

4. 4. The heat-sensitive image-forming element according to the above item 3, wherein the infrared absorbing component is an infrared absorbing dye.

5. 4. The heat-sensitive imaging element according to claim 3, wherein the infrared absorbing component is an infrared absorbing pigment.

6. A heat-sensitive imaging element according to any of the preceding claims, wherein said top layer comprises a crosslinking agent selected from the group consisting of formaldehyde, glyoxal, polyisocyanate or hydrolyzed tetraalkyl orthosilicate.

7. The hydrophilic layer is selected from the group consisting of homopolymers and copolymers of vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylate acid, methacrylate acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, and maleic anhydride / vinyl methyl ether copolymer. A heat-sensitive imaging element according to any of the preceding claims, comprising a sexual binder.

8. The method of any of claims 1 to 7, wherein the aryldiazosulfonate monomer is copolymerized with a monomer containing a reactive group capable of reacting with formaldehyde, glyoxal, polyisocyanate or hydrolyzed tetraalkylorthosilicate. Thermosensitive imaging element.

9. A method for providing a lithographic printing plate comprising exposing a heat-sensitive imaging element according to any of the preceding claims.

10. -Exposing the heat-sensitive imaging element of any of the above items 1 to 8;-mounting the plate on a printing press;-applying ink and dampening solution on the plate; printing from the plate. Printing method including.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Houve van Aerto Belgium 2640 Malt Cell Septes Trat 27 Agfa-Gevuert na Mrose Fennoutjaps (72) Inventor Giyoan Belmercieu Belgium Bee 2640 Malt cell Septest Trat 27Agfa-Gevuert na Mrose Fennoutjap

Claims (3)

[Claims] 1. A heat-switchable imaging layer comprising a support and a hardened hydrophilic binder and a heat-switchable polymer as a top layer, wherein said top layer or a layer adjacent to said top layer is a top layer. A heat-sensitive imaging element for providing a lithographic printing plate comprising a compound capable of converting light to heat; wherein the thermally switchable polymer is a polymer containing aryldiazosulfonate units. 2. A method for providing a lithographic printing plate comprising exposing a heat-sensitive imaging element according to claim 1. 3. exposing the heat-sensitive imaging element of claim 1; mounting the plate on a printing press; applying ink and dampening solution onto the plate; printing from the plate. Printing method.