JPH11268443A - Lithographic printing plate provided by image forming element which is heat-sensitive and non-ablative, without wastes, and method for lithographic printing by using dampening solution containing water-insoluble compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a print from a lithographic printing plate which has an excellent in k accepting property in an image region, and does not have the ink accepting property in a non-image region. SOLUTION: For this printing method, a lithographic printing plate is manufactured by laser-exposing an image forming element containing a compound which can convert light into heat, also, containing a binder which can be thermally switched, as an uppermost layer on a supporting body, and having a heat-sensitive image forming layer which becomes further hydrophilic or further hydrophobic under the action of the laser-exposure along an image, and which is heat-sensitive and non-ablative, without wastes, along the image; and a printing element is loaded on a printing machine before or after the exposure, and a stage wherein a dampening solution and an ink are applied, is included. In this case, the dampening solution contains at least one kind of a water-insoluble compound being selected from a group comprising silica, almina, titanium oxide, tin oxide, china clay, smectic clay and zirconium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive non-ablation
On-abratable and waste-free (wast)
e) a lithographic printing plate provided by the imaging element and a lithographic printing method by using a dampening solution containing a water-insoluble compound.

[0002]

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 inks on a hydrophilic background in exposed areas (negative-working) or in unexposed areas (positive-working). Is receptive to

[0004] 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.

[0006] In another case, printing plates are known that contain a photosensitive coating that is made soluble in the exposed areas when exposed image-wise. In that case, subsequent development removes the exposed areas. A typical example of such a photosensitive coating is a quinone-diazide based coating.

[0007] Typically, the photographic material from which the printing plate is made is exposed in contact 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 quality.

Thus, attempts have been made to obtain printing plates directly from the computer data indicative of the image to be reproduced, excluding the need for photographic film in the above method, especially. However, the above photosensitive coatings are not sensitive enough to be directly exposed using a 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-
Although disclosed in A-60-61 752, it has the disadvantage of requiring complex development and 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 developing the photosensitive layer.

In addition, methods for making printing plates involving the use of imaging elements that are heat-sensitive rather than light-sensitive are known. 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 sensitive to near infrared. To date, none has been found to be commercially viable and all require wet development to wash away unexposed areas. EP
-A-514 145 describes a laser-addressed plate in which the heat generated by laser exposure causes the particles in the plate coating to melt and agglomerate, thus changing its melting properties. In this case also, wet development is required.

A somewhat different approach is described in US Pat.
7 210, US-P-3 962513, EP-A-
001 068 and JP-04-140191. Using the heat generated by laser exposure of the donor sheet, the resinous material is physically transferred from the donor to a receptor held in close contact with the donor. If the receptor surface has suitable hydrophilicity, it can then be used as a printing plate. This method has the advantage that no wet processing is required, but to achieve a realistic write time a high power YAG (or similar)
A laser is required, which has limited the usefulness of the method.

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, and WO-92 / 02855 discloses a coating that becomes tacky as a result of irradiation. In both cases, the coating comprises an acid-sensitive polymer and a photochemical source of a strong acid, the preferred acid-sensitive polymer in both cases being derived from a cyclic acetal ester of acrylic or methacrylic acid, such as tetrahydropyranyl (meth) acrylate. Is done.

WO-92 / 02855 combines an acid-sensitive polymer with a low-Tg polymer and is initially non-tacky, but upon irradiation, undergoes phase separation as a result of chemical conversion of the acid-sensitive polymer. , To provide a coating that becomes tacky. The possibility of laser exposure is mentioned but not detailed, there is no disclosure of IR-sensitivity, only UV / visible. However, the same material is available in 1993 IS & T / SPIE Confer.
ence, Symposium on Electro
nic Science and Technology
"Advances in Phototackifici, designated as Paper 1912-36 in US Pat.
The subject of the article entitled "Cation", in which the photoacid generator can further 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 not known that the dyes in question have acid-generating properties.
This method is the subject of U.S. Pat. No. 5,286,604.

WO-92 / 09934 discloses the incorporation of an acid-sensitive polymer, optionally with one or more photoacid generators. After image-wise exposure to UV / visible radiation, the exposed areas are preferentially wettable by water and the coating can function as a lithographic printing plate without the need for wet processing.
There is no disclosure of the laser address.

EP-A-652 483 discloses a lithographic printing plate which does not require a dissolution treatment and comprises a support having a heat-sensitive coating, the coating of which becomes relatively more hydrophilic under the action of heat. I have. The system gives a positive working printing plate. No special dampening solution is mentioned. A system that provides a similar but negative working printing plate has been disclosed by the same inventors on the same day.

DE-1 105 439 discloses a dampening solution for lithographic printing characterized by an amount of very finely dispersed silicon dioxide or a mixed oxide of very finely dispersed silicon dioxide and aluminum oxide. A liquid is disclosed.

[0018] EP-A-652 483 does not require a dissolution treatment and comprises a support having a heat-sensitive coating containing a photothermal conversion material, the coating being relatively hydrophilic under the action of heat. Version is disclosed.

GB-A-2 008 495 has the following (a)
Treatment liquid composition for treating the surface of a lithographic printing plate comprising at least one phosphoric acid, (b) nitric acid and / or at least one salt thereof, and (c) nitrous acid and / or at least one salt thereof Disclosure.

US-P-4 081 572 describes (a)
Providing a self-supporting master substrate, (b) providing a special hydrophilic polymer, (c) coating the substrate with the polymer, and (d) selectively and thermally hydrophobicizing the polymer in image form. Disclosed is a method for making a print master that includes converting to a neutral state.

[0021]

OBJECTS OF THE INVENTION It is an object of the present invention to provide a heat-sensitive, non-absorptive, heat-sensitive, non-absorbable layer having, as a top layer, an imaging layer which becomes more hydrophilic or more hydrophobic under the action of image-wise IR-laser exposure. Providing a print from a lithographic printing plate obtained by imagewise laser exposing a waste-free imaging element and having excellent ink receptivity in the image area and no ink receptivity in the non-image area It is.

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

[0023]

SUMMARY OF THE INVENTION In accordance with the present invention, light is converted to heat (tr
including a compound that can be referred to
Thermosensitive, non-ablationable, discarding having a heat-switchable binder as a top layer on a support and having a thermosensitive imaging layer that becomes more hydrophilic or more hydrophobic under the action of image-wise laser exposure Making a lithographic printing plate by imagewise laser exposing the solid imaging element; mounting the printing element on a printing press before or after exposure; applying a dampening solution and ink A lithographic printing method comprising:
A method is provided wherein the dampening solution comprises at least one water-insoluble compound selected from the group consisting of silica, alumina, titanium oxide, tin oxide, china clay, smectic clay and zirconium oxide.

[0024]

DETAILED DESCRIPTION OF THE INVENTION The number average size of the water-insoluble compound is preferably in the range of 0.005 .mu.m to 0.05 .mu.m.
The concentrated dampening solution is particularly preferably (preferenti
all) contains the water-insoluble compound in an amount of 1 g to 30 g, preferably 2.5 g / l to 20 g / l, per liter. A preferred water-insoluble compound is silica.

[0025] A concentrated or damping solution suitable for use in the present invention.
lutions) are aqueous solutions containing a water-soluble organic solvent. Examples of such water-soluble organic solvents include alcohols, polyhydric alcohols, ethers, polyglycols and esters.

Examples of alcohol include n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol,
2-methylpentanol-1, secondary hexyl alcohol, 2-ethylbutyl alcohol, secondary heptyl alcohol and heptanol-3,2-ethylhexyl alcohol.

Examples of polyhydric alcohols include ethylene glycol, hexylene glycol, octylene glycol, diethylene glycol and glycerol. Examples of ethers are ethylene glycol monoethyl ether,
Ethylene glycol mono-n-hexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethyl butyl ether, diethylene glycol monoethyl ether and diethylene glycol mono-n-hexyl ether are included.

Examples of the esters include diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate.

Examples of polyglycols are 400 to 2000
Polyethylene glycol having an average molecular weight of 400
Included are polypropylene glycol having an average molecular weight of ~ 2000 and block copolymers of ethylene glycol and propylene glycol.

The dynamic surface tension of the concentrated dampening solution is reduced by the addition of the organic solvent. The concentrated dampening solution of the present invention comprises Cahn
Co, U.S.A. S. A. NOW-INST manufactured by
ANT WILHELMY DYNAMIC SURF
Using ACE TENSION ACCESSORY,
It has a dynamic surface tension range, preferably at 25 ° C., of from 25 to 50 dynes / cm at 15 ° C., measured at most 1 * 10 −1 seconds after the surface of the solution has been formed on the surface of the printing plate.

The concentrated dampening solution used in the present invention is about 0.0
It can contain 5 to 30% by weight, preferably 0.1 to 25% by weight, more preferably 1 to 20% by weight of these water-soluble organic solvents.

According to the present invention, the concentrated dampening solution has a pH comprised between 3 and 6, more preferably between 4 and 6. Thus, the concentrated dampening solution contains a buffer salt, preferably a phosphate. The amount of buffer salt is preferably 3-30 g / l, more preferably 6 g / l.
２５25 g / l.

In order to further improve the stability of the concentrated dampening solution, citrate ions are also preferably contained in an amount of 0.5 mmol to 25 mmol, more preferably 1 mmol to 20 mmol, most preferably 1.5 mmol to Included at a total concentration of 15 mmol. The term "total concentration of citrate anions" refers to the sum of the concentrations of citric acid and its salts, regardless of their ionic charge.

The concentrated dampening solution is preferably polymethacrylic acid or one of its salts, polyacrylic acid or one of its salts,
It also includes one or more polymers selected from the group consisting of polydextran, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyvinyl sulfonic acid or one of its salts, and gum arabic. The polymer is used in an amount from 0.1 g / l to 5.0 g / l.

In order to improve the emulsification ratio in the ink, a surfactant can be added to the concentrated dampening solution. The content of these surfactants must be 1% by weight or less in consideration of foaming, and is preferably 0.0001 to
0.3% by weight.

The concentrated dampening solution used in the present invention can also contain a thickener. Examples of thickeners that can be used in the present invention include water-soluble cellulose derivatives, alginates and derivatives, rubber, water-soluble modifications of starch, and water-soluble high molecular weight homopolymers and copolymers. These compounds can be used alone or as a mixture of two or more thereof.

The concentration will vary depending on the type of thickener, but is preferably about 0.00005 based on the amount of the fountain solution composition.
１1% by weight.

In general, the concentrated dampening solution used in the present invention is:
Preservatives (combinations) are included so that the composition is effective in controlling various molds, bacteria and yeasts.

In addition to the above components, the concentrated dampening solution of the present invention preferably contains the chelating compound in an amount of 0.1% based on the amount of dampening solution.
The corrosion inhibitor can be contained in an amount of 00001 to 0.3% by weight and preferably in an amount of 0.000001 to 0.5% by weight.

The concentrated dampening solution is diluted with a sufficient amount of tap water or well water before being applied on the plate. The concentrated dampening solution is a dilution of 1: 100 to 10: 100, preferably 2:
Used on a printing press at a dilution of 100-6: 100.

The dampening solution can be used alone or in combination with a water-soluble organic solvent such as isopropanol or a substitute therefor.

The imaging layer, which becomes more hydrophobic or hydrophilic under the influence of IR radiation, contains a heat-switchable binder and optionally a compound capable of converting light to heat.
Heat-switchable binders are polymers or copolymers that change polarity from hydrophilic to hydrophobic or vice versa under the influence of heat.

In one embodiment, the heat-switchable binder shifts polarity from hydrophobic to hydrophilic. The polymer preferably has pendant hydrophobic groups that are converted to hydrophilic groups under the action of heat. More preferably, the pendant group is selected from the group consisting of t-alkyl carboxylate, t-alkyl carbonate, benzyl carboxylate and alkoxyalkyl ester. Further details are given in EP-A-652 483.

In a further preferred embodiment, the heat-switchable binder shifts polarity from hydrophilic to hydrophobic.

The imaging layer, which becomes more hydrophobic under the influence of heat, contains a heat-switchable binder and optionally a compound capable of converting light to heat. According to a preferred embodiment, 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. The switchable binder according to a preferred embodiment is preferably a polymer or copolymer containing pendant polar functional groups. These polar functional groups can be carboxylic acids, sulfonic acids, phosphonic acids and phenols or their salts. Sodium, potassium, ammonium or tetraalkylammonium ions can be used as counterions. Trace amounts of alkalis, such as trace amounts of triethylamine and pyridine, can also be used. These hydrophilic functional groups react with other functional groups under the influence of heat to form a hydrophobic structure.

A further preferred switchable binder according to a preferred embodiment is a maleic acid-containing binder, wherein the binder is hydrophilic and gives a maleic anhydride-containing binder under the influence of heat. The binder is hydrophobic. Still further preferred switchable binders according to the invention are fumaric acid, itaconic acid, 3- or 4
-Vinylphthalic acid, cis-1,2,3,6-tetrahydrophthalic acid or cis-5-norben-endo-2,3-
It is a binder containing a dicarboxylic acid. The acids can be mixed in one copolymer. Not only diacids but also monoalkyl esters and salts thereof are more preferred. Examples of such half-esters are monobutyl maleate copolymer, mono-isopropyl maleate copolymer, 2-butoxyethyl maleate copolymer, isobutyl maleate copolymer and isooctyl maleate copolymer. These half-esters can be used in combination with the corresponding dicarboxylic acid substances in one copolymer or they can be mixed with one another or with other dicarboxylic acids or salts to form one copolymer.

Not only copolymers obtained by copolymerization of maleic acid, but also polymer derivatives obtained, for example, by grafting maleic acid onto unsaturated polyolefins, are very suitable switchable polymers.

Preferably, the switchable binders according to a preferred embodiment are preferably acrylates, methacrylates, vinyl halides, vinyl esters, vinyl ethers such as n-butyl, isobutyl and 2-chloroethyl vinyl ether and olefins such as propylene , Isobutylene and 1-octadecene. Compounds selected from the group consisting of methyl vinyl ether copolymer, ethene copolymer and styrene copolymer are more preferred. Most preferably, the binder is a copolymer containing maleic acid and vinyl methyl ether.

The ratio of dicarboxylic acid monomer to comonomer can be from 100: 0 to 20:80 or the structure or state (ie, anhydride or other) is sufficient to affect the overall solubility of the top layer. Can be a ratio. The ratio is typically around 50:50 due to the tendency towards alternating copolymerization. The molecular weight is generally 5,
000-70,000 weight average molecular weight, preferably 1
It is between 0000 and 40,000 g / mol.

The imaging layer can contain more than one switchable polymer, but it is not preferred. The imaging layer can also include further binders to enhance the hydrophilicity or hydrophobicity of the layer.

As hydrophilic binders, hydrophilic (co) polymers such as acrylamide, methylolacrylamide, methylolmethacrylamide, homopolymers and copolymers of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride / vinylmethyl Ether copolymers 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. A preferred hydrophilic binder is polyvinyl alcohol.

Water-insoluble polymers such as cellulose esters, copolymers of vinylidene chloride and acrylonitrile, poly (meth) acrylates and polyvinyl chloride can be used as hydrophobic binders. Preferred hydrophobic binders are the usual positive or negative acting P
Hydrophobic binders used in the S-plate, such as novolak,
Polyvinyl phenols, carboxy-substituted polymers and the like. A typical example of these polymers is DE-A-4
007 428, DE-A-4 027 301 and D
EA-4445820.

The image-forming layer or the layer immediately below it preferably contains a compound capable of converting light to heat. Suitable compounds capable of converting light to heat are preferably infrared absorbing components,
The absorption wavelength is not particularly important as long as the absorption of the compound used is within the wavelength range of the light source used for image-wise exposure. 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.
Is disclosed. Examples of infrared absorbing pigments are carbon black, metal carbides, borides, nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze group but without the A component, such as WO _2.9 . is there. 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 in an amount of 1 to 25% by weight of the total weight of the image forming layer, more preferably in an amount of 2 to 20% by weight of the total weight of the image forming layer. Present in the imaging element. Compounds capable of converting light to heat are most preferably from 800 nm to 1
Present in the imaging element in an amount that provides an optical density of at least 0.35 at a wavelength of 100 nm.

Further, the image forming layer is preferably a visible light- and UV-light desensitizing layer. This preferably visible- or UV-light desensitized layer is between 250 nm and 650
It does not contain photosensitive components such as diazo compounds, photoacids, photoinitiators, quinonediazides, and sensitizers that absorb in the wavelength region of nm. In this way, daylight-stable printing plates can be obtained.

The image forming layer is preferably 0.1 to 10 g /
The amount of m ^2, more preferably is applied in an amount of 0.5 to 5 g / 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.

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

According to another embodiment related to the present invention,
The support is a flexible support such as, for example, paper or a plastic film. It is particularly preferable to use a plastic film, for example, a supported polyethylene terephthalate film, a cellulose acetate film, a polystyrene film, a polycarbonate film, or the like as the flexible support in connection with this embodiment. 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
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 higher than 1, and 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 between the support and the top layer can contain other layers such as subbing layers and antihalation layers.

[0062] Regardless of whether the imaging element contains a dye according to the present invention, the imaging element can optionally contain a reflective layer between the support and the top layer. The reflective layer can be any layer that reflects IR radiation, but is preferably aluminum having a high visual density, for example, vacuum deposited aluminum.

[0063] The imaging element can be manufactured by applying the various layers according to any known method. Alternatively, on a printing press, the imaging element can be manufactured using one or more coaters located in close proximity to the printing press, using the support already on the printing press.

For image formation in connection with the present invention, preferably infrared or near infrared, ie 700-1500 nm
An image-wise scanning exposure involving the use of a laser operating in the wavelength region of is used. 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 present invention, the exposure of the imaging element can be performed with the imaging element already on the printing press. A computer or other source supplies graphics and textual information to the printhead or laser via leads.

The printing plate of the present invention can be used as a seamless sleeve printing plate in a printing method. Instead of applying a classically formed printing plate in a classical way, this cylindrical printing plate having the diameter of the printing cylinder as a diameter is slid over the printing cylinder. Further details regarding the sleeve can be found in "Graish Nieuws" ed.
Kesing, 15, 1995, pages 4-6.

If the inking of the plate and the dampening solution can be carried out simultaneously, or if the inking of the plate can even precede the application of the dampening solution to the plate, the dampening solution is supplied before the inking of the plate. It is preferred to apply a solution.

The following examples illustrate the present invention, but the present invention is not limited thereto. Example 1
And 2 illustrate the use of the claimed method for an imaging element that becomes more hydrophobic when its imaging layer is exposed, and Examples 3 and 4 show that the imaging layer is exposed. And the use of the claimed method for imaging elements that become more hydrophilic. All parts and percentages are by weight unless otherwise specified.

[0070]

EXAMPLES Example 1 0.35 g of GANTREZ AN 139 BF.
(Vinyl methyl ether, copolymer of maleic acid and maleic anhydride, commercially available from GAF, USA) and 0.0365 g of IR-absorbing dye IR-1 in 44% THF, 34% methoxypropanol and 2%
Dissolve in 4.5 g of a solvent mixture consisting of 2% methyl ethyl ketone. The solution was placed on an aluminum support for 16μ.
m and a dried layer having a thickness of 1.15 g / m ² after drying. This image forming element is referred to as CREO 3244 Trendset.
ter (trade name of CREO, Canada)
It was run at a drum speed of 12 rpm and a laser power of 12 watts and was exposed at 2400 dpi. After exposing the imaging element, a printing plate is obtained, which is K +
E 800 ink (Kast und Ehringe
r trade name) and 5% of TAME EC7035
(A dampening solution containing no water-insoluble compound, ANCHO
R, commercially available from USA).
B Dick 360 printing press (AB Dick, USA
(Product name). Scum formation was observed in the non-exposed areas.

[0071]

Embedded image Example 2 A printing plate produced and imaged in the same manner as the printing plate from Example 1 was used with K + E 800 ink (Kast und
Ehringer trade name) and 5% G671c
AB Dick 3 using water containing (silica containing dampening solution from Agfa-Gevaert, Belgium).
It was used for printing on a 60 printing machine (AB Dick, trade name of USA). Excellent prints, i.e., prints with excellent ink absorption in exposed areas and no scum formation in unexposed areas were obtained.

Example 3 0.35 g of tetrahydropyranyl methacrylate / methacryloxypropyltrimethoxysilane by weight and a copolymer at a monomer ratio of 90:10 and 0.1%.
0365 g of IR-absorbing dye IR-1 are converted to 60% TH
4.5 g of F and 40% methoxypropanol
Dissolve in the solvent mixture of The solution was coated on an aluminum support to a wet coating thickness of 16 μm, resulting in a dried layer having a thickness of 1.15 g / m ² after drying. This image forming element is designated CREO 3244 Tre
ndsetter (trade name of CREO, Canada)
Above, it was operated at a drum speed of 40 rpm and a laser power of 12 watts and exposed at 2400 dpi. After exposing the imaging element, a printing plate is obtained,
K + E 800 ink (Kast und Eh)
ringer's trade name) and 5% TAME EC
7035 (fountain solution containing no water-insoluble compound, A
AB Dick 360 printing press (AB Dic) with water containing NCHOR, commercially available from USA
k, trade name of USA). Scum formation was observed in the exposed areas.

Example 4 The printing plate produced and imaged in the same manner as the printing plate from Example 3 was treated with K + E 800 ink (Kast und
Ehringer trade name) and 5% G671c
AB Dick 3 using water containing (silica containing dampening solution from Agfa-Gevaert, Belgium).
It was used for printing on a 60 printing machine (AB Dick, trade name of USA). Excellent prints, i.e., prints with excellent ink absorption in the non-exposed areas and no scum formation in the exposed areas were obtained. The main features and aspects of the present invention are as follows.

1. A heat-switchable binder,
A heat-sensitive, non-ablationable, waste-free imaging element having a heat-sensitive imaging layer, which becomes more hydrophilic or more hydrophobic under the action of image-wise laser exposure, as a top layer on a support is image-wise Preparing a lithographic printing plate by laser exposure;-mounting the printing element on a printing press before or after exposure;-applying a fountain solution and ink to the lithographic printing method, comprising: The dampening solution is silica, alumina, titanium oxide,
A method comprising at least one water-insoluble compound selected from the group consisting of tin oxide, china clay, smectic clay and zirconium oxide.

2. The dampening solution may further comprise one of polymethacrylic acid or one of its salts, polyacrylic acid or one of its salts, polydextran, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, one of polyvinyl sulfonic acids or one of its salts, and gum arabic. The lithographic printing method according to claim 1, comprising at least one polymer selected from the group consisting of:

3. 3. The lithographic printing method according to the above 1 or 2, wherein the dampening solution is applied before the ink is supplied to the plate.

4. A lithographic printing method according to any of the preceding claims, wherein the thermally switchable binder comprises a pendant hydrophobic group which is converted into a hydrophilic group under the action of heat.

5. 5. The lithographic printing method according to claim 4, wherein the pendant hydrophobic group is selected from the group consisting of t-alkyl carboxylate, t-alkyl carbonate, benzyl carboxylate and alkoxyalkyl ester.

6. A lithographic printing method according to any of the preceding claims, wherein the thermally switchable binder comprises a pendant hydrophilic group which is converted into a hydrophobic group under the action of heat.

7. 7. The lithographic printing method according to claim 6, wherein the hydrophilic group is selected from the group consisting of carboxylic acids, sulfonic acids, phosphonic acids, phenols and salts thereof.

8. The heat-switchable binder having pendant hydrophilic groups is maleic acid, fumaric acid, itaconic acid, 3- or 4-vinylphthalic acid, cis-1,2,2
3,6-tetrahydrophthalic acid, cis-5-norbene-
(Monomer) containing a monomer unit selected from the group consisting of endo-2,3-dicarboxylic acids and their half esters
Item 8. The lithographic printing method according to Item 7, which is a polymer.

9. Lithographic printing according to any of claims 6 to 8, wherein said heat-switchable binder having pendant hydrophilic groups is a copolymer further comprising a monomer unit selected from the group consisting of vinyl methyl ether, ethene and styrene. Method.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Giohan van Hunsell Belgium 2640 Maltsel Septes Trat 27 Agfa-Gevuert na Mrose Fennotsyajp (72) Inventor Giojan Belmercieu Belgium -Bee 2640 Maltcell Septes Trat 27-Agfa-Gevert na Mulose Fuennotsjap (72) Inventor Peter Hendricks Belgium-Bee 2640 Maltcell Septes Trat 27-Agfa-Gevert na Mulose Fuennautsjap Inside

Claims (1)

[Claims] 1. A heat-sensitive layer comprising as a top layer on a support a heat-sensitive imaging layer comprising a heat-switchable binder and becoming more hydrophilic or more hydrophobic under the action of image-wise laser exposure. Making a lithographic printing plate by image-wise laser exposing a non-absorptive, waste-free imaging element;-mounting said printing element on a printing press before or after exposure; And a lithographic printing method including the step of applying ink, wherein the dampening solution is silica, alumina, titanium oxide,
A method comprising at least one water-insoluble compound selected from the group consisting of tin oxide, china clay, smectic clay and zirconium oxide.