Abstract: A method for making a heat-sensitive negative-working lithographic printing plate precursor is disclosed comprising the steps of (i) preparing a coating solution comprising hydrophobic thermoplastic polymer particles and a hydrophilic binder; (ii) applying said coating solution on a support having a hydrophilic surface or which is provided with a hydrophilic layer, thereby obtaining an image-recording layer; (iii) drying said image-recording layer; characterized in that said hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 63 nm, and that the amount of said hydrophobic thermoplastic polymer particles in the image-recording layer is at least 70% by weight relative to the dried image-recording layer.

Abstract: A method for making a heat-sensitive negative-working lithographic printing plate precursor is disclosed comprising the steps of (i) preparing a coating solution comprising hydrophobic thermoplastic polymer particles and a hydrophilic binder; (ii) applying said coating solution on a support having a hydrophilic surface or which is provided with a hydrophilic layer, thereby obtaining an image-recording layer; (iii) drying said image-recording layer; characterized in that said hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 63 nm, and that the amount of said hydrophobic thermoplastic polymer particles in the image-recording layer is at least 70% by weight relative to the dried image-recording layer.

Abstract: A method for making a lithographic printing plate is disclosed which comprises the steps of: (i) providing a negative-working, heat-sensitive lithographic printing plate precursor comprising a support having a hydrophilic surface or which is provided with a hydrophilic layer and a coating provided thereon, the coating comprising an image-recording layer which comprises hydrophobic thermoplastic polymer particles and a hydrophilic binder, wherein the hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 63 nm and wherein the amount of the hydrophobic thermoplastic polymer particles in the image-recording layer is at least 70% by weight relative to the image-recording layer; (ii) exposing the coating to heat or infrared light, thereby inducing coalescence of the thermoplastic polymer particles at exposed areas of the coating; (iii) developing the precursor by applying an aqueous, alkaline solution, thereby removing non-exposed areas of the coating from the support,

Abstract: A negative-working lithographic printing plate precursor is disclosed which comprises a grained and anodized aluminum support having a hydrophilic surface and a heat-sensitive coating provided on the hydrophilic surface, the coating comprising hydrophobic thermoplastic polymer particles which are capable of forming a hydrophobic phase in the coating by heat-induced coalescence of the polymer particles. The support is characterized by a surface roughness, expressed as arithmetical mean center-line roughness Ra, which is less than 0.45 ?m. The smooth surface enables to prepare a lithographic printing plate from the mentioned precursor, which is characterized by a high run length during printing.

Abstract: A heat sensitive lithographic printing plate precursor comprising in the order given (i) a lithographic base having a hydrophilic surface, (ii) an image recording layer comprising hydrophobic thermoplastic polymer particles and (iii) a contrast layer, wherein the precursor comprising an infrared absorbing compound present in at least one of said image recording layer or contrast layer and wherein the contrast layer further comprises a colorant capable of providing a visible image after exposure and development of the precursor and wherein the image recording layer is substantially free of the colorant. The printing plate formed after image-wise exposing and processing exhibits an improved image-contrast and reduced staining.

Abstract: A printing system making use of a lithographic printing plate has been disclosed, the system comprising the steps of image-wise exposing to infrared light a heat sensitive imaging element, the element being optionally present on the printing press before starting the image-wise exposing step to infrared light, wherein the element comprises, on a lithographic base with a hydrophilic surface thereupon, an image-forming layer including hydrophobic thermoplastic polymer particles and a hydrophilic polymer binder, and, optionally, an infrared absorbing compound, wherein the hydrophobic polymer particles contain more than 0.1 wt % of nitrogen and have an average particle size diameter in the range from 0.015 to 0.

Abstract: A negative-working lithographic printing plate precursor is disclosed which comprises a grained and anodized aluminum support having a hydrophilic surface and a heat-sensitive coating provided on the hydrophilic surface, the coating comprising hydrophobic thermoplastic polymer particles which are capable of forming a hydrophobic phase in the coating by heat-induced coalescence of the polymer particles. The support is characterized by a surface roughness, expressed as arithmetical mean center-line roughness Ra, which is less than 0.45 &mgr;m. The smooth surface enables to prepare a lithographic printing plate from the mentioned precursor, which is characterized by a high run length during printing.

Abstract: A method of making a lithographic printing plate is disclosed which comprises the steps of

Abstract: A printing system making use of a lithographic printing plate has been disclosed, said system comprising the steps of image-wise exposing to infrared light a heat sensitive imaging element, said element being optionally present on the printing press before starting said image-wise exposing step to infrared light, wherein said element comprises, on a lithographic base with a hydrophilic surface thereupon, an image-forming layer including hydrophobic thermoplastic polymer particles and a hydrophilic polymer binder, and, optionally, an infrared absorbing compound, wherein said hydrophobic polymer particles contain more than 0.1 wt % of nitrogen and have an average particle size diameter in the range from 0.015 to 0.

Abstract: According to the present invention there is provided a method for the preparation of a lithographic printing plate comprising the steps of exposing with IR light an imaging element comprising on a lithographic base with a hydrophilic surface a first layer including a polymer, soluble in an aqueous alkaline solution and a top layer on the same side of the lithographic base as the first layer which top layer is IR-sensitive and unpenetratable for or insoluble in an alkaline developer wherein said first layer and said top layer may be one and the same layer, said imaging element comprising a siloxane surfactant; developing said exposed imaging element with an alkaline solution; rinsing said developed imaging element with water or an aqueous solution; gumming said developed imaging element with a baking gum solution; subjecting said gummed imaging element to a thermal treatment at a temperature above 50° C.

Abstract: According to the present invention there is provided a heat-sensitive imaging element for providing a lithographic printing late, comprising a lithographic base with a hydrophobic oleophilic surface and a top layer comprising a compound capable of converting light into heat and a hydrophilic polymer, characterized in that said hydrophilic polymer is crosslinked.

Abstract: According to the present invention there is provided a method for making lithographic printing plates including the following steps:a) preparing a light sensitive imaging element having on a lithographic base with a hydrophilic surface a first layer including a polymer, soluble in an aqueous alkaline solution and a top layer on the same side of the lithographic base as the first layer which top layer is unpenetrable for an alkaline developer containing SiO.sub.2 as silicate;b) exposing imagewise said light sensitive imaging element to actinic light;c) developing said imagewise exposed light sensitive imaging element with said alkaline developer so that the exposed areas of the top layer and the underlying areas of the first layer are dissolved and the unexposed areas of the first layer remain undissolved characterized in that said top layer includes a diazonium salt and for at least 20% of its weight one or more non-proteinic hydrophilic film-forming polymers.

Abstract: According to the present invention there is provided an imaging element comprising on a support having a hydrophilic surface in the order given a photosensitive layer insoluble in an aqueous alkaline solution and capable of becoming soluble in said aqueous alkaline solution upon exposure with actinic light and a thermosensitive layer comprising a masking dye rendering said thermosensitive layer opaque to light for which said photosensitive layer has spectral sensitivity and said imaging element further comprising a compound A capable of converting light into heat comprised in said thermosensitive layer or a layer adjacent thereto, characterized in that said thermosensitive layer further comprises thermoplastic particles of a hydrophobic polymer.

Abstract: According to the present invention there is provided a method for making a lithographic printing plate comprising the steps of:(1) image-wise exposing an imaging element having on a support in the order given (i) a uniform ink-repellant layer comprising a hydrophilic binder cross-linked by means of a hydrolysed tetra-alkylorthosilicate and (ii) a photosensitive layer comprising a diazonium salt or a diazo resin;(2) and developing a thus obtained image-wise exposed imaging element by mounting it on a print cylinder of a printing press and supplying an aqueous dampening liquid and/or ink to said photosensitive layer.

Abstract: According to the present invention there is provided a method for making a lithographic printing plate comprising the steps of:(1) image-wise exposing an imaging element having of a flexible film support in the order given (i) a uniform ink-repellant layer comprising a cross-linked hydrophilic binder and (ii) a photosensitive layer comprising a diazonium salt or a diazo resin;(2) and developing a thus obtained image-wise exposed imaging element by mounting it on a print cylinder of a printing press and wiping it with a disposable absorbing tissue moistened with water or fountain solution.

Abstract: The present invention provides an imaging element comprising on a hydrophilic base a light-sensitive layer containing polyvinyl alcohol hydrolyzed to at least an extent of 95% by weight, a cationic surfactant and a diazo resin and/or a diazonium salt characterized in that the light-sensitive layer comprises metal-free phthalocyanine.The present invention also provides a method for obtaining an imaging element as defined in any of the claims 1 to 6 bypreparing a dispersion of metal-free phthalocyanine in water in the presence of a cationic surfactant in an amount ranging from 0.24 g/l to 24 g/l;preparing a light-sensitive composition by mixing said dispersion, polyvinyl alcohol hydrolyzed to at least an extent of 95% by weight and a diazo resin and/or a diazonium salt andcoating said light-sensitive composition on a hydrophilic base, characterized in that said dispersion comprises polyvinyl alcohol hydrolyzed to at least an extent of 95% by weight in an amount ranging from 4.0 g/l to 200 g/l.

Abstract: The present invention provides an imaging element comprising on a support a hydrophilic layer containing a hydrophilic (co)polymer or (co)polymer mixture and having been hardened with a hydrolysed tetraalkyl orthosilicate and a light sensitive layer containing a diazo resin and/or a diazonium salt characterized in that the light sensitive layer comprises at least one diazo resin or diazonium salt containing or being a diazonium salt of p-aminodiphenylamine containing as substituent an alkyl or alkoxy group and the weight percentage of said diazonium salt(s) and/or diazo resin(s) containing or being a diazonium salt of p-aminodiphenylamine containing as substituent an alkyl or alkoxy group versus the total amount of diazo resin and/or diazonium salt ranges from 22 to 40%.

Abstract: The present invention provides a method for obtaining a lithographic printing plate comprising the steps of (i) image-wise exposing an imaging element comprising on a hydrophilic surface of a support a light sensitive layer containing a diazo resin or a diazonium salt and a dispersed water-insoluble polymer with a melting point or glass transition temperature above 40.degree. C. and capable of coagulating when heated at or above its melting point or glass transition temperature, and (ii) subsequently removing the light sensitive layer in the non-exposed or insufficiently exposed areas of said imaging element by means of rinsing or washing said imaging element with plain water, characterized in that afterwards said developed image-wise exposed imaging element is heat-treated at a temperature at least equal to the glass transition temperature or melting point of said dispersed water-insoluble polymer.

Abstract: The present invention provides an imaging element comprising on a support in the order given a coated composition of at least two hydrophilic layers being in water permeable contact with each other and each containing a hydrophilic (co)polymer or (co)polymer mixture and having been hardened with a hydrolyzed tetraalkyl orthosilicate and a light sensitive layer containing a diazo resin or a diazonium salt characterized in that the ratio by weight in the top layer of said package of said hydrophilic (co)polymer or (co)polymer mixture versus said hydrolyzed tetraalkyl orthosilicate (expressed as silicon dioxide) is at least 1.1 and the ratio by weight in an underlying layer of said package of said hydrophilic (co)polymer or (co)polymer mixture versus said hydrolyzed tetraalkyl orthosilicate (expressed as silicon dioxide) is not higher than 0.9.

Abstract: The present invention provides an imaging element comprising on a hydrophilic support a light sensitive layer containing a diazo resin or a diazonium salt characterized in that said light sensitive layer contains pullulan. The obtained imaging element shows an improved storage stability.