JPH10193824A - Heat-sensitive image forming element for manufacturing lithographic printing plate having improved transfer characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-sensitive image forming element for manufacturing a lithographic printing plate having an improved transfer characteristics. SOLUTION: This is an image forming element for manufacturing a lithographic printing plate including an ink repulsion layer containing a hydrophilic bonding agent closslinked and a heat-sensitive layer containing a hydrophobic thermoplastic polymer particle dispersed in the hydrophilic bonding agent on a flexible support. The utmost outside layer, which exists at an upper part of the image forming element and an opposite side of the support, contains at least a solid or a liquid lubricant in the hydrophilic bonding agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for making a lithographic printing plate comprising the use of a heat-sensitive imaging element. In particular, the invention relates to improvements in imageability by its surface in contact with a heat source having a particular composition.

[0002]

BACKGROUND OF THE INVENTION Lithographic printing is a method of printing from a surface that has been specially manufactured so that some areas are capable of receiving ink while others are not.

In lithographic technology, photographic materials which accept oily or greasy inks imagewise in exposed (negative working) or unexposed (positive working) areas on an ink-repellent background are described. Manufactured.

In the manufacture of common lithographic plates, also referred to as surface lithographic or planographic printing plates, a support having an affinity for water or obtaining such an affinity by chemical treatment is coated with a thin layer of a photosensitive composition. Have been. Coatings for this purpose include a photopolymer layer containing a diazo compound, a dichromate-sensitized hydrophilic colloid and a large amount of a synthetic photopolymer. In particular, diazo-sensitized systems are widely used.

With image-wise exposure of such a photosensitive layer, the exposed image areas become insoluble and the unexposed areas remain soluble. The plate is then developed with a suitable liquid to remove the diazonium salt or diazo resin in the unexposed areas.

[0006] On the other hand, methods for producing printing plates are known which involve the use of imaging elements which are heat-sensitive rather than light-sensitive. A particular disadvantage of the above-described photosensitive imaging elements for producing printing plates is that they must be shielded from light. The trend towards heat-sensitive printing plate precursors is clearly visible on the market.

[0007] For example, Research Disc of January 1992
Losure no. 33303 discloses a heat-sensitive imaging element comprising a crosslinked hydrophilic layer containing thermoplastic polymer particles and an infrared absorbing pigment such as carbon black on a support. . Image-wise exposure to infrared lasers causes the thermoplastic polymer particles to solidify image-wise, thereby rendering the surface of the imaging element ink-receptive in these areas without further development. A disadvantage of this method is that the resulting printing plate is easily damaged since the non-printing area may become ink-receptive when some pressure is applied to it. Further, under critical conditions, the lithographic performance of such printing plates may be poor, and thus such printing plates have a small lithographic printing latitude.

[0008] EP-A-514145 discloses a heat-sensitive imaging comprising a coating comprising a water-insoluble thermosoftening core component and a core-shell particle having a shell portion which is soluble or swellable in an aqueous alkaline medium. Disclosure of elements. A red or infrared laser beam image-directed to the imaging element at least partially coalesces the selected particles to form an image and the uncoalescing particles are then selectively treated by an aqueous alkaline developing agent. Removed. Thereafter, a baking step is performed. However,
The printing resistance of the plate thus obtained is low.

[0009] EP-A-599510 describes (i) (1)
A dispersed layer comprising a water-insoluble thermosoftening component A and (2) a binder, or a discontinuous layer comprising a component B which is soluble or swellable in an aqueous, preferably aqueous alkaline medium. Wherein at least one of components A and B contains a reactive group or a precursor thereof, so that insolubilization of the layer occurs at elevated temperatures and / or by exposure to actinic radiation. And (ii)
Disclosed is a thermosensitive imaging element comprising a substrate coated with a material that strongly absorbs radiation and thus transfers the energy obtained as heat to the disperse phase, resulting in at least partial coalescence of the coating. doing. After the image-wise irradiation of the imaging element and the development of the image-wise irradiated plate, the plate is heated and / or exposed to actinic radiation to render it insoluble. However, the printing resistance of the printing plate thus obtained is low.

Further, EP-A-952022871.
0, 952022872.8, 952022873.6 and 952022874.4 comprise (1) (i) hydrophobic thermoplastic polymer particles dispersed in a hydrophilic binder on a hydrophilic surface of a lithographic base. The image forming layer and (i
i) exposing a heat-sensitive imaging element comprising a compound capable of converting light contained in said imaging layer or adjacent layers to heat image-wise, and (2) obtaining in this way Disclosed is a method of making a lithographic printing plate comprising developing the image-wise exposed element with fresh water by rinsing. The thermal imaging system discussed above can also be used as a direct thermal imaging element for recording methods where the image is formed by the use of image-wise modulated thermal energy. . In this case, the presence of a compound capable of converting light into heat is not required in the image forming layer or in a layer adjacent thereto.

In this method, an image is formed by feeding a heat-sensitive imaging element onto a thermal head for forming an image. However, due to improper transport of the thermal imaging element over the thermal head, the image formed on the thermal imaging system is distorted, damaged and wiped away.
This latter wiping residue may occur as the thermoplastic particles melt during the heating process and are transferred in the printing direction. Furthermore, the thermal head is also contaminated.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide excellent transfer properties (tran
It is to provide a heat-sensitive imaging element suitable for imaging using a thermal head which has sporting properties and which can be developed in a simple ecological way.

It is another object of the present invention to provide a heat-sensitive imaging element that does not have a fouling or abrasion effect on the thermal head and does not show any wiping residue after the thermographic imaging step.

It is yet another object of the present invention to provide a method of producing a lithographic printing plate having excellent print quality and having no distortion in the direction of transport of the imaging element during imaging.

[0015] Other objects of the present invention will be apparent from the following description.

According to the present invention, on a flexible support,
(I) an ink repellent layer containing a cross-linked hydrophilic binder and (ii) a heat-sensitive layer comprising hydrophobic thermoplastic polymer particles dispersed in the hydrophilic binder. An imaging element for the manufacture of a lithographic printing plate, wherein the outermost layer is on top of said two layers of said imaging element, said outermost layer being at least in a hydrophilic binder. An imaging element is provided, which comprises a solid or liquid lubricant.

Furthermore, according to the present invention, (1) said image forming element is image-wise heated by a thermal head in said outermost layer, and (2) the image-wise heating thus obtained. There is provided a method of making a lithographic printing plate comprising developing the imaging element with water or an aqueous liquid.

[0018]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a lithographic printing plate is obtained which has good transportability of the imaging element on a thermal head and suitable dimensions using the imaging element described above. In addition, residual wiping of the image and fouling of the thermal head are avoided.

According to a preferred embodiment, the invention provides a thermal imaging method wherein the heat source is a thin or thick film thermal head.

According to the present invention, the lubricant may be liquid or solid. The solid lubricant may or may not be hot melt. Lubricants are referred to as hot-meltable when their melting points are below 200 ° C. A non-hot-meltable lubricant such as, for example, Teflon or inorganic particles can be added to the outermost layer. The addition of inorganic particles is particularly recommended. They can protrude through the surface of the outermost layer to reduce the growth of debris on the thermal head.

Inorganic particles such as silica or salts derived from silica such as talc, clay, clay, mica,
Chlorite, silica, or carbonates such as calcium carbonate, magnesium carbonate or calcium magnesium carbonate (dolomite) can be added to the outermost layer according to the invention.

It is highly preferred that the inorganic particles be added to the outermost layer having a Mohs hardness of less than 2.7.

Mixtures of talc and dolomite or talc and silica particles are highly preferred.

According to a preferred embodiment, the hot-melt lubricant has a melting point below 150 ° C. Solid lubricants having a melting point below 110 ° C. are preferred, and solid lubricants having a molecular weight below 1000 are particularly preferred. For purposes of the present invention, a solid lubricant is defined as a lubricant that is solid at 20 ° C.

Solid hot-melt lubricants which can be used in accordance with the present invention include polyolefin waxes such as polypropylene waxes, ester waxes such as fatty acid esters, polyolefin-polyether block copolymers, amide waxes such as Fatty acid amides, polyglycols such as polyethylene glycol, fatty acids, fatty alcohols, natural waxes and solid phosphate derivatives.

Suitable solid hot melt lubricants are selected from the group consisting of fatty acid esters, fatty acid amides and phosphate esters. Preferred fatty acid esters are glyceryl monostearate, glyceryl monopalmitate and mixtures of glyceryl monostearate and glyceryl monopalmitate. Suitable fatty acid amides are selected from the group consisting of ethylene bis stearamide, stearamide, oleamide, myristamide and erucamide.

Examples of suitable solid non-phosphate derivative lubricants according to the present invention, together with their melting points, are given below: Melting point (° C.) SL01: Ethylene bis stearamide (Ceridust from Hoechst AG) ) ^TM 3910) 141 SL02: myristamide 106 SL03: stearamide 104 SL04: glycerin monostearate 81 SL05: erucamide 80 SL06: oleamide 73 SL07: glycerin tristearate 55-73 SL08] Mobilcer ^TM Q (paraffin wax) SL09: glycerin monostearate (Henkel (Riranito from ^{HENKEL) (Rilnnito) TM GMS)} 55-60 SL10: (SPAN TM 60 from ICI PLC) sorbitan monostearate 55 SL11: Torisuteari Sorbitan (ICI SPAN ^TM 65 from PLC) 48-53 SL12: sorbitan monopalmitate (SPAN ^TM 40 from ICI PLC) 44-47 SL13: monostearate POE- (4) - sorbitan (ICI Tween from PLC (TWEEN) ^TM 61) 62 Suitable phosphoric ester derivative solid lubricants (P
Examples of SL) are given below with melting points: Melting point (° C.) PSL01: Servoxyl ^™ VPAZ100 from Servo Delden BV (mixture of monolauryl and dilauryl phosphate) 33 PSL02: Servo derden Servoxyl ^™ VPRZ100 50 (mixture of monocetyl and monostearyl phosphate) from Delden BV PSL03: Potassium alkyl phosphate (Crafol ^™ AP37 from Henkel AG) 62 Lubrication of liquids that can be used according to the invention Agents include silicone oils, functionalized silicone oils, silicone block polymers such as polyalkylene oxide-polysiloxane copolymers, glycerol esters, liquid phosphate derivatives, and the like. Liquid phosphate derivatives are preferred among the liquid lubricants.

Examples of suitable non-phosphate derivatives according to the invention are: LL01: glycerine trioleate LL02: anti-sorbitan monooleate (Henkel
kel) AG from SPAN ^™ 80) LL03: anti-sorbitan trioleate (Henkel
SPAN ^™ 85) LL04: Tegoglide ^™ ZG400 from TEGO-chemie Suitable phosphate derivative liquid lubricant (P) according to the present invention
Examples of LL) are: PLL01: Servoxil ^™ VPDZ 3 100 from Servo Delden BV {mono [isotridecyl polyglycol ether phosphate (3E)
O)} PLL02: Servoxil ^™ VPRZ 6 100 from Servo Delden BV {mono [isotridecyl polyglycol ether phosphate (6E)
O)} PLL03: Seroxyl ^™ VPRZ 7 100 from Servo Delden BV {mono [oleyl polyglycol ether (7EO) phosphate] PLL04: Sermul from Servo Delden BV ) ^TM EA224 (= Serboxil (Se
rvoxyl) ^™ VPFZ 7 100 {mono [oleyl polyglycol ether phosphate (7EO)} mixtures of solid and liquid lubricants are preferred. Mixtures of liquid and hot melt solid lubricants are particularly preferred.

According to the present invention, the outermost layer on top of the imaging layer of the imaging element comprises a hydrophilic binder.
Suitable hydrophilic binders for the outermost layer are, for example, gelatin, polyvinyl alcohol, cellulose derivatives or other polysaccharides, hydroxyethylcellulose, hydroxypropylcellulose, etc., with binders having a glass transition temperature higher than 100 ° C. Agents are preferred and polyvinyl alcohol is particularly preferred.

[0030] Other additives or fillers, for example colloidal particles such as colloidal silica, can also be added in the outermost layer.

Although curing of the binder may affect the water treatability of the imaging element, a lower degree of cure can improve the thermal stability of the outermost layer.

The thickness of the outermost layer on top of the imaging layer of the imaging element can be any thickness that provides sufficient protection of the image and thermal head. Preferably, the outermost layer has a thickness of 0.1-10 μm, more preferably 0.2-5 μm.
μm.

It is also possible to use an intermediate layer between the outermost layer and the heat-sensitive layer to improve the developing properties of the imaging element or to improve the adhesion between the outermost layer and the heat-sensitive layer. Good. The binder for the intermediate layer is preferably hydrophilic and the thickness of the layer may be between 0.05 and 5 [mu] m. Interlayers are particularly useful when a slightly cross-linked hydrophilic binder is used in the outermost layer.

In the present invention, a heat-sensitive composition comprising an image-forming layer comprising a hydrophobic thermoplastic polymer dispersed in a hydrophilic binder on a hydrophilic surface of a lithographic base. An imaging element is used. The hydrophilic binder in the imaging layer used in connection with the present invention is preferably uncrosslinked or only slightly crosslinked. The imaging element also includes a compound capable of converting light to heat. The compound is contained in the image forming layer or a layer adjacent thereto.

According to the invention, the lithographic base comprises a flexible support, for example a paper or plastic film, provided with a cross-linked hydrophilic layer. Particularly suitable crosslinked coarse hydrophilic layers are, for example, formaldehyde,
It is obtained from a hydrophilic binder cross-linked with a cross-linking agent such as glyoxal, polyisocyanate or, preferably, hydrolyzed tetraalkyl orthosilicate.

As the hydrophilic binder, a hydrophilic (co) polymer such as vinyl alcohol, acrylamide, methylolacrylamide, methylolmethacrylamide,
Acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride / vinyl methyl ether copolymer can be used.

The crosslinked hydrophilic layer on the flexible support used according to the invention is preferably a substance which increases the mechanical strength and the porosity of the layer, for example colloidal silica,
It contains. In addition, inert particles of larger dimensions than colloidal silica, such as those described by Stoeber in J. C.
olloid and Interface Sci., Vol. 26, 1968, pages62
Silica or alumina particles or particles of titanium dioxide or other heavy metal oxides having an average diameter of at least 100 nm can be added as described in US Pat. The incorporation of these particles gives the surface of the cross-linked hydrophilic layer a uniform and rough texture consisting of microscopic dimensional irregularities.

The thickness of the crosslinked hydrophilic layer is 0.2 to 0.2.
Can vary in the range of 25 μm and preferably 1-10 μM
It is.

Particular examples of cross-linked hydrophilic layers suitable for use according to the invention are EP-A 601 240, GB-
P-1419512, FR-P-2300354, US
-P-397660, US-P-4284705 and EP-A 514490.

As a flexible support for the cross-linked hydrophilic layer according to this embodiment, a plastic film such as a substrated polyethylene terephthalate film, polynaphthalate ethylene film, cellulose acetate film, polystyrene film, polycarbonate film, etc. is used. It is particularly preferred to do so. The plastic film support may be opaque or transparent.

It is particularly preferred to use a polyester film support provided with an adhesion improving layer. Particularly suitable adhesion improving layers for use according to the invention are EP-A 619.
524, EP-A 620502 and EP-A 619
525, comprising a hydrophilic binder and a colloid as disclosed in US Pat.

[0042] Optionally, one or more intermediate layers may be provided between the hydrophilic base and the image forming layer. The imaging layer according to the present invention comprises thermoplastic polymer particles dispersed in a hydrophilic binder.

Suitable hydrophilic binders for use in the imaging layer according to the present invention are water-soluble (co) polymers, such as synthetic homo- or copolymers, such as polyvinyl alcohol,
Poly (meth) acrylic acid, poly (meth) acrylamide, hydroxyethyl poly (meth) acrylate, polyvinyl methyl ether or natural binders such as gelatin, polysaccharides such as dextran, pullulan, cellulose, gum arabic, alginic acid.

The hydrophilic binder may be a water-soluble alkali-soluble or swellable resin having a phenolic hydroxy group and / or a carboxyl group.

Preferably, the water-insoluble alkali-soluble or swellable resin used in connection with the present invention comprises phenolic hydroxy groups. Water-insoluble alkali-soluble or swellable resins suitable for use in the imaging layers according to the present invention include, for example, synthetic novolak resins, such as ALNOVOL and Oxychem under the registered trademark of Reichold Hoechst. Durez, a registered trademark, and synthetic polyvinylphenols such as MARUKA LYNCUR M, a registered trademark of Dyno Cyanamid.

The hydrophilic binder of the imaging element used in connection with the present invention is preferably uncrosslinked or only slightly crosslinked.

The preferred thermoplastic polymer particles in the embodiment of the present invention are hydrophobic polymer particles. The hydrophobic thermoplastic polymer particles used in connection with the present invention have a freezing point above 50 ° C and more preferably above 70 ° C. Solidification results from the softening or melting of the thermoplastic polymer particles under the influence of heat. There is no specific upper limit for the solidification temperature of the thermoplastic hydrophobic polymer particles, but that temperature must be well below the decomposition temperature of the polymer particles. Preferably, the coagulation temperature is at least 10 degrees above the temperature at which the decomposition of the polymer particles occurs.
° C lower. When the polymer particles are subjected to temperatures above the coagulation temperature, they form hydrophobic agglomerates in the hydrophilic layer, at which point the hydrophilic layer becomes insoluble in fresh water or aqueous liquids.

Particular examples of hydrophobic polymer particles for use in connection with the present invention, preferably having a Tg of greater than 80 ° C., are polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyvinyl carbazole, and the like. Or a mixture thereof. Polystyrene, polymethyl methacrylate or copolymers thereof are most preferably used.

The weight average molecular weight of the polymer is from 5,000 to 1,000 as measured by GPC with respect to polystyrene standards.
It is in the range of 0,000 g / mol.

The hydrophobic particles can have a particle size between 0.01 μm and 50 μm, more preferably between 0.05 μm and 10 μm and most preferably between 0.05 μm and 2 μm.

The polymer particles are present as a dispersion in the aqueous coating liquid of the imaging layer and are disclosed in US Pat.
476,937. Another method which is particularly suitable for the production of aqueous dispersions of thermoplastic polymer particles comprises:-dissolving a hydrophobic thermoplastic polymer in a water-immiscible organic solvent;-dissolving the solution thus obtained. Dispersing in water or an aqueous medium, and-removing the organic solvent by evaporation.

[0052] The amount of hydrophobic thermoplastic polymer particles contained in the imaging layer is preferably at least 30% by weight and more preferably at least 45% by weight and most preferably at least 60% by weight.

The imaging layer can also comprise a crosslinking agent, but this is not necessary. Suitable crosslinking agents are low molecular weight substances comprising methylol groups, such as melamine-formaldehyde resins, glycolyl-formaldehyde resins, thiourea-formaldehyde resins, guanamine-formaldehyde resins, benzoguanamine-
It is a formaldehyde resin. Many of the melamine-formaldehyde and glycolyl-formaldehyde resins are available from CYMEL (Dyno Cyanamid Co., Ltd.) and NIKALAC (Sanwa Chemical Company.
Limited (Sanwa Chemical Co., Ltd.)).

The imaging element may further include a compound capable of converting light to heat. The compound is preferably included in the image forming layer, but may be provided in a layer adjacent to the image forming layer. Suitable compounds capable of converting light to heat are preferably infrared absorbing components. Particularly useful compounds are, for example, dyes and especially infrared dyes, carbon blacks, metal carbides, borides, nitrides, carbonitrides, oxides of bronze structure and oxides structurally related to the bronze family but lacking the A component. For example, WO _2.9 . Conductive polymer dispersion,
For example, conductive polymer dispersions based on polypyrrole or polyaniline can also be used. The light-to-heat conversion compound associated with the present invention is most preferably added to the imaging layer, but at least a portion of the light-to-heat conversion compound may be included in a nearby layer.

According to a particular embodiment of the present invention, the imaging layer may further comprise a diazonium salt, a diazo resin or an aryldiazosulfonate resin.
Such offers the advantage that print quality, especially ink absorption by the image areas, can be improved by applying global UV exposure to the developed imaging element after image-wise heating and development. However, such an implementation would be practical only in the case of off-line exposure and development, rather than in development on a printing press.

Examples of low molecular weight diazonium salts for use in the present invention include benzidine tetrazonium chloride, 3,3'-dimethylbenzidine tetrazonium chloride, 3,3'-dimethoxybenzidine tetrazonium chloride, 4,4'-diaminodiphenylamine tetrazonium chloride, 3,3'-diethylbenzidine tetrazonium sulfate, 4-aminodiphenylaminediazonium sulfate, 4-aminodiphenylaminediazonium chloride, 4-piperidinoanilinediazonium sulfate, 4-diethylaminoaniline Oligomeric condensation products of diazonium sulfate and diazodiphenylamine with formaldehyde are included.

Examples of diazo resins useful in the present invention include condensation products of aromatic diazonium salts as photosensitive materials. Such condensation products are known and are described, for example, in German Patent No. 1214086. They are generally prepared by the condensation of preferably substituted or unsubstituted diphenylamine-4-diazonium salts with a polynuclear aromatic diazonium compound and an active carbonyl compound, preferably formaldehyde, in a strong acid medium. You.

Examples of aryldiazole sulfonate resins are EP-A 339393 and EP-A 507008.
, The teachings of which are hereby incorporated by reference.

According to the method of the invention for obtaining a printing plate, the imaging element is heated with a thermal head, for example in a thermal printer, and subsequently developed with water or an aqueous solution.

According to a preferred method of the present invention for obtaining a printing plate, the imaging element is heated with a thermal head, for example in a thermal printer, and subsequently placed on the printing cylinder of a printing machine. According to a preferred embodiment, the printing machine is then started and the dampener roller supplying the dampening liquid is lowered onto the imaging element while the printing cylinder rotates with the imaging element mounted thereon and subsequently The ink roller descends there. Generally, about 1 of the printing cylinder
The first clean and useful print is obtained after 0 revolutions.

Suitable fountain solutions that can be used in connection with the present invention are aqueous solutions having an acidic pH and comprising an alcohol such as, for example, isopropanol. There is no particular limitation on the fountain solution useful in the present invention, and commercially available fountain solutions also known as fountain solutions can be used.

Wiping the imaging element with, for example, water-soaked cotton or sponge before placing the imaging element on the printing press or at least before starting up the printing press after the image-wise heating of the imaging element. May be advantageous. This may remove some non-image areas and / or outermost layers. However, it has the advantage that considerable contamination that can occur of the dampening system of the printing machine and of the ink used is avoided.

According to another method, the imaging element is first placed on the printing cylinder of a printing press and then heated directly image-wise on the printing press. After heating, the imaging element can be developed as described above. This embodiment offers the advantage that the thermal head is required to be incorporated into the printing machine and reduces the total processing time between the baking of the original (eg, computer generated) and the printing of the actual copy.

According to yet another method of the present invention,
The imaging element is heated image-wise and subsequently developed with fresh or aqueous liquid.

The invention will now be illustrated by the following examples, which are not intended to limit the invention. All parts are by weight unless otherwise indicated.

[0066]

【Example】

Example 1 Preparation of a lithographic base 21.5% TiO ₂ (average particle size 0.3-0.4 μm)
398 g of a dispersion containing 195 g of hydrolyzed tetramethyl orthosilicate and 12 g of a 10% solution of a wetting agent in 398 g of a dispersion containing 2.5% of vinyl alcohol in deionized water. Added continuously. To this mixture was added 395 g of deionized water and the pH was adjusted to pH = 4. The resulting dispersion is coated on a poly (ethylene terephthalate) film support (coated with a hydrophilic adhesive layer) to a wet coating thickness of 50 g / m ² and dried at 30 ° C.
It was subsequently cured for one week at a temperature of 57 ° C.

Preparation of the heat-sensitive layer The following coating composition was prepared and applied to the above lithographic base in an amount of 30 g / m ² (wet coating amount).
The heat-sensitive layer was prepared by coating at room temperature and drying it at 30 ° C. to produce a heat-sensitive layer.

Preparation of Coating Composition for Thermal Sensitive Layer Hostapal B (Hoechst) in deionized water
105 g of polymethyl methacrylate / polystyrene (80/20)
In a 20% dispersion of the copolymer (particle size of 100 nm),
While stirring, 20 g of Printex L6 (Degussa), stabilized with Ultravon (commercially available from Ciba-Geigy).
sa) a carbon black dispersion commercially available from
% Dispersion, 120 g of 98% hydrolyzed polyvinyl acetate having a weight average molecular weight of 200,000 (Hoechst
(MOWITOL) 5 commercially available from (Hoechst)
6-98) of a 5% solution in water and 10 g of a wetting agent in 10
% Solution was added continuously.

Preparation of the Outermost Layer The following coating composition was prepared and the most coated by coating it on the above heat-sensitive layer in an amount of 40 g / m ² (wet coating amount) and drying it at 30 ° C. The outer layer was manufactured.

Preparation of outermost layer coating composition 387.5 g of 20 was added to 535.6 g of water while stirring.
5% solution in water of 98% hydrolyzed polyvinyl acetate having a weight average molecular weight of 0000 g / mol (MOWITOL 56-98, commercially available from hoechst), 1.9 g of Servoxyl VPD
Z3 / 100 (commercially available from Servo Delden BV) and Gafac RM710
A 5% solution in water of 75 g of Rilanit GMS (commercially available from Henkel) stabilized with (commercially available from GAF) was added.

Manufacture of printing plates and making copies of the original.
00 DPI) (DRYST)
AR) A 2000 thermal printer (commercially available from Agfa) was printed (exposed) and the unexposed parts were then washed off manually or on a printing machine.

Printing was performed on an AB Dick 360 offset printing machine equipped with a VARN ^™ KOMPAC II dampening system. Vanson as ink
(VanSon) RB2329 ^™ and G671c (3% in water) commercially available from Agfa-Gevaert NV as dampening solution. Good printing was obtained, having suitable dimensions and no ink absorption in the non-image areas.

Example 2: The preparation of the lithographic base and the heat-sensitive layer was the same as described in Example 1.

Preparation of the Outermost Layer The following coating composition was prepared and the most coated by coating it on the above heat-sensitive layer in an amount of 40 g / m ² (wet coating amount) and drying it at 30 ° C. The outer layer was manufactured.

Preparation of Coating Composition for Outermost Layer In 366.5 g of water, with stirring, 18 g of Ultravon W-acidic form (Ciba-Geigy)
Geigy), a 5% solution in water, 454.
5 g of 9 having a weight average molecular weight of 90000 g / mol
8.5% hydrolyzed polyvinyl acetate (Wack
er) commercially available from POLYVIOL WX4
8/20) 5% solution in water, 2% Servoxil (Servo
xyl) VPDZ3 / 100 (Servo Delden
den) commercially available from BV) 2% cerboxil (S
ervoxyl) VPAZ100 (Servo Delden
den) commercially available from BV) 2.4% syloid (Sy
loid) 72 (commercially available from Grace GMBH), 1.2% Steamic 00S (commercially available from Talc de Luzenac) and 3% 98. 45 g of an aqueous dispersion containing 0.5% hydrolyzed polyvinyl acetate, having a weight average molecular weight of 90000 g / mol and stabilized with Gafac RM710 (commercially available from GAF); 80 g of Kieselsol 500F (Bayer
(Commercially available from Bayer) was added continuously.

Production of a printing plate and preparation of an original copy The imaging element described above was printed (exposed) in a DRYSTAR 2000 thermal printer (commercially available from Agfa) and then exposed. The missing parts were washed off manually or on a printing press. Burn (VARN)
AB equipped with ^TM Compaq (KOMPAC) II dampening system
Printing was performed on a Dick 360 offset printing machine. VanSon RB2329 ^™ as ink and Agfa-Gevaer as dampening solution
t) G671c (3% in water) commercially available from NV was used. Good printing was obtained, having suitable dimensions and no ink absorption in the non-image areas. No wiping residue of the image occurred.

Example 3 The preparation of the lithographic base and the heat-sensitive layer was the same as described in Example 1.

Preparation of the Outermost Layer The following coating composition was prepared and coated on the above-mentioned heat-sensitive layer in an amount of 40 g / m ² (wet coating amount) and dried at 30 ° C. The outer layer was manufactured.

Preparation of the Coating Composition for the Outermost Layer In 366.5 g of water, with stirring, 18 g of Ultravon W-acidic form (Ciba-Geigy)
Geigy) from Ultravon
W) 454.5 g of 98.5% hydrolyzed polyvinyl acetate having a weight-average molecular weight of 90000 g / mol (polyviol commercially available from Wacker (P
5% solution of OLYVIOL (WX48 / 20) in water, 2% Servoxyl VPDZ 3/100 (commercially available from Servo Delden BV), 2% Servoxyl VPAZ100 (Servo Delden) (Commercially available from (Servo Delden) BV) 2.4
% Syloid 72 (Grace GMBH
1.2% Steamic (commercially available from
c) 00S (Talc de Luzenac)
And 3% 98.5% hydrolyzed polyvinyl acetate, has a weight average molecular weight of 90000 g / mol, and has a Gafac RM710
(Commercially available from GAF) stabilized 45 g dispersion in water, as well as Gafac RM710 (GA
36 g of a 5% dispersion of Rilanit GMS (commercially available from Henkel), which had been stabilized with a commercially available product from H.F.

Production of a printing plate and preparation of an original copy The imaging element described above was printed (exposed) in a DRYSTAR 2000 thermal printer (commercially available from Agfa) and subsequently exposed. The missing parts were washed off manually or on a printing press. Burn (VARN)
AB equipped with ^TM Compaq (KOMPAC) II dampening system
Printing was performed on a Dick 360 offset printing machine. VanSon RB2329 ^™ as ink and Agfa-Gevaer as dampening solution
t) G671c (3% in water) commercially available from NV was used. Good printing was obtained, having suitable dimensions and no ink absorption in the non-image areas.

The main features and aspects of the present invention are as follows.

1. On a flexible support, (i) an ink repellent layer containing a cross-linked hydrophilic binder and (ii) a hydrophobic thermoplastic resin dispersed in the hydrophilic binder. An imaging element for the manufacture of a lithographic printing plate comprising a thermosensitive layer comprising coalesced particles, wherein the outermost layer is on top of said two layers of said imaging element, An imaging element wherein the outermost layer comprises at least a solid or liquid lubricant in a hydrophilic binder.

2. The imaging element of 1 above, wherein said lubricant is a heat fusible solid or liquid.

3. The imaging element of claim 1 wherein said outermost layer comprises a mixture of a hot melt solid lubricant and a liquid lubricant.

4. The imaging element of any of the preceding clauses wherein said solid lubricant is selected from the group consisting of fatty acid esters, fatty acid amides and phosphate ester derivatives.

5. The image-forming element according to any one of the above items 1 to 3, wherein the liquid lubricant is a phosphate derivative.

[0087] 6. The imaging element of any of the preceding clauses, wherein the outermost layer has a thickness between 0.1 and 10 μm.

7. The imaging element of any of the preceding clauses, wherein the outermost layer further comprises inorganic particles protruding from the surface of the outermost layer.

8. The imaging element of any of the preceding clauses wherein the outermost layer further comprises a colloidal filler.

9. (1) The image forming element of any of the above 1 to 8 is heated imagewise by a thermal head, and (2) The imagewise heated image forming element thus obtained is water or A method for producing a lithographic printing plate, comprising a step of developing using an aqueous liquid.

10. (1) Place the imaging element of any of the above 1 to 8 on a printing cylinder of a printing machine;
The imaging element is heated image-wise by means of a thermal head, and (3) the image-wise heated imaging element thus obtained is washed with an aqueous dampening solution and / or ink while rotating the printing cylinder. And developing the lithographic printing plate by supplying to the image forming layer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Geert Defeu Belgium B 2640 Maltcell Septes Trat 27 Agfa-Gevert Na Mrose Fennoutjaps (72) Inventor Marc van Dame Belgium B 2640 Maltcell Septes Trat 27, Agfa-Gevaert Na, in Mrose-Fennoutjap

Claims (3)

[Claims] 1. An ink-repellent layer containing (i) a cross-linked hydrophilic binder on a flexible support and (i)
i) an imaging element for making a lithographic printing plate comprising a thermosensitive layer comprising hydrophobic thermoplastic polymer particles dispersed in a hydrophilic binder, wherein the outermost layer is An imaging element which is on top of said two layers of the imaging element, said outermost layer comprising at least a solid or liquid lubricant in a hydrophilic binder. 2. An image-forming element according to claim 1, wherein the image-forming element is heated image-wise by a thermal head, and (2) the image-wise heated image-forming element thus obtained is water or an aqueous liquid. A method for producing a lithographic printing plate, comprising a step of developing using a lithographic printing plate. 3. An image-forming element according to claim 1, which is mounted on a printing cylinder of a printing machine, (2) the image-forming element is image-wise heated by a thermal head, and (3) The imagewise heated imaging element thus obtained is
While rotating the printing cylinder, an aqueous dampening solution and / or
Alternatively, a method for producing a lithographic printing plate, comprising a step of developing by supplying ink to the image forming layer.