JPH043320B2 - - Google Patents

Description

Claim 1 (A) At least one surface of aluminum or an aluminum-coated hydrophilic material comprising: 1 non-metallic inorganic particles; and 2 one or more phases of a dehydrated product of at least one monobasic phosphate. 1. A photosensitive article comprising: an aluminum or aluminum-coated substrate in the form of a film or sheet having a ceramic layer having a thickness of 0.3 to 10 microns; and (B) a photosensitive lithographic coating on the ceramic layer.

2. The photosensitive article of paragraph 1 above, wherein the article consists of metal oxide particles having an average particle size of from 1 x 10 ^-3 μm to 45 μm.

3. The photosensitive article of item 2 above, wherein the metal oxide particles are made of alumina.

4. The ceramic layer is between 0.2 μm and 15 μm thick, the substrate is aluminum in the form of a film or sheet, and the lithographic coating is in a polymerizable composition or binder. The photosensitive article of item 2 above, comprising either o-quinone diazide having a positive effect.

5. The ceramic layer contains a reaction product between aluminum and a monobasic phosphate, and a reaction product between at least one metal oxide other than alumina and a monobasic phosphate, and contains at least one reaction product of the monobasic phosphate. 2. The photosensitive article of item 2 above, wherein the metal oxide orthophosphate is insoluble in an aqueous solution having a pH of 6 to 12.

6 (A) A slurry of at least one monobasic phosphate and non-metallic inorganic particles is applied to at least one surface of an aluminum or aluminum-coated substrate in the form of a film or sheet, and at a temperature of at least 230°C. (B) producing a ceramic layer on the aluminum substrate or on the aluminum-coated surface of the substrate by firing the slurry to create a hydrophilic 0.3-10 micron thick ceramic coating on the aluminum or aluminum-coated surface; A method for producing a photosensitive substrate, comprising the steps of: coating the ceramic layer with a photosensitive lithographic organic layer.

7. The method of claim 6, wherein the particles consist of metal oxide particles having an average particle size of 1 x 10 ^-3 μm to 45 μm, and the metal oxides consist of reactive alumina particles.

8. The method of item 7 above, wherein the metal oxide particles further additionally comprise alpha-alumina particles.

9 The metal oxide particles consist of reactive alumina and metal oxide, and the orthophosphate of the oxide is PH
The method of item 7 above, wherein 6 to 12 are insoluble in an aqueous solution.

10 The slurry is comprised of from about 5% by volume to about 15% by volume of nonvolatile materials on calcination, with at least 35% by volume of the nonvolatile materials being from phosphate and reactive metal oxides and/or reactive metal oxides. 9. The method of item 9 above, wherein the matrix is a matrix consisting of:

11 Ceramic coating is 0.2μm
Items 6 and 7 above, having a thickness of between 15 μm;
The method of paragraph 8 or paragraph 9.

12. The method of item 10 above, wherein the monobasic phosphate is generated in situ during calcination by reaction of phosphoric acid and tribasic phosphate.

13. The method of item 7 above, wherein monobasic phosphate is generated in situ during calcination by reaction of phosphoric acid with alumina and/or aluminum hydroxide.

14. The method of paragraph 7 above, wherein the monobasic phosphate is formed in situ during calcination by reaction of a monobasic phosphate which does not consist essentially of aluminum phosphate with aluminum. .

15. The method of item 6 above, wherein the calcium-containing compound is included in the slurry.

16 On at least one surface of an aluminum or aluminum-coated substrate in the form of a film or sheet, a hydrophilic material having a thickness of 0.3 and comprising a polymorph of aluminum phosphate or a mixture of aluminum phosphates.
An article comprising an aluminum or aluminum-coated substrate with a ceramic coating of ~10 microns and a photosensitive lithographic organic layer on the ceramic coating.

17 Applying a layer of monobasic phosphate to at least one aluminum surface of an aluminum or aluminum-coated substrate in the form of a film or sheet, and then applying at least one layer of monobasic phosphate to at least one aluminum surface of the aluminum or aluminum-coated substrate
Aluminum or aluminum coating, fired at a temperature of 230°C to produce a hydrophilic ceramic coating with a thickness of 0.3 to 10 microns on the aluminum, and coating an organic photosensitive lithographic layer on the ceramic coating. How to coat a substrate.

18 No. 1 above, wherein at least one surface of the aluminum or aluminum-coated surface has microscopic, lithographically effective structures in the aluminum, and the coating has a thickness between 0.2 μm and 15 μm. Method of Section 17.

19. The method of paragraph 17 or paragraph 18 above, wherein the monobasic phosphate comprises aluminum phosphate and the calcination is carried out at a temperature of at least 260°C to produce a dehydrated coating.

BACKGROUND OF THE INVENTION Lithographic printing plates have been widely used for many years. One of the basic principles used in this technique is to create a wettability gap between the areas of the surface where the image is printed flat. To do this, the surface must be hydrophilic,
i.e., providing a substrate that can be wetted with water and that can be imaged (usually sensitive to visible light or radiation) and that can be developed;
Most commonly, the surface is coated with a grease-compatible (oleophilic), hydrophobic layer. After creating an image in this layer and developing it, the printing master exposes a hydrophilic surface and a hydrophobic surface for the image. If the plate is first moistened with water and then coated with a grease or oil-based printing ink, only the hydrophobic areas of the image will hold the ink and will not print against a receiving surface such as paper. This results in a dark transferred image.

With this lithographic printing method, it was possible to prepare a lithographic printing original plate that could be used to produce a small quantity of just a few hundred copies or a large quantity of several hundred thousand copies of the same printed matter. It is quite obvious that it would be desirable to be able to make a large number of identical prints from a single master plate. Although the operation of creating and developing the image must be performed only once, there is no need to stop the printing press during the operation to change the master.

The study of ways to extend the operating time of lithographic printing plates has been the focus of much research. Maintaining other desirable or essential properties of printing plates, such as speed of imaging, ease of development, non-staining chemicals, and shelf life, in order to provide a durable printing plate. It is also necessary to improve or improve it. Most research into providing long-running, durable lithographic printing masters has focused on the development of imageable, hydrophobic substrates on hydrophilic surfaces of substrates. This is a coating layer. The logic of the research direction is clear, since it is usually this layer that is the cause of failure in printing masters.

The substrates typically prepared as imageable layers are aluminum sheets that have undergone various cleaning, mechanical and chemical treatments to prepare them for coating. For example, aluminum surfaces are commonly cleaned to remove oil and other contaminants. This cleaning is followed by a mechanical or electrochemical granulation treatment, and finally an anodization treatment.

For example, US Pat. No. 3,963,594 discloses electrochemical etching of aluminum substrates using aqueous solutions of hydrochloric acid and gluconic acid. This method provides an aluminum substrate with a uniformly rough surface structure. The method of this patent allows the use of lower current densities than those found to be necessary when using only hydrochloric acid in the etching bath. The molten aluminum and other impurities formed in the etching bath were also complicated to handle. This increased the lifespan of the bath. A stain removal process was also demonstrated in conjunction with electrochemical etching.

British Patent No. 1,439,127 discloses an anodizing process on aluminum substrates in which anodizing is carried out in an aqueous sulfuric acid bath at a temperature above 50° C. and an anodizing current density of at least 70 Amp./sq.ft. . This treatment shortens the length of time for anodizing. Other etching solution compositions and electrical parameters are described in U.S. Pat.
4,072,589 and 4,052,275, as well as French Patent No. 2,322,015.

After electrochemically or mechanically etching the aluminum surface, an anodizing treatment is usually performed to make the aluminum surface corrosion and abrasion resistant. This is described in UK Patent No. 1,439,127 and US Pat. No. 4,131,518 mentioned above. The latter patent describes anodizing aluminum foil in continuous web form to reduce energy requirements and increase anodization rates, especially when the aluminum has a polymer coating on one side. Make it.

US Pat. No. 3,181,461 discloses an anodizing process in which a sulfuric acid anodizing step is followed by treatment with an aqueous sodium silicate solution. This treatment seals the pores in the oxide surface of the anode and creates a hydrophilic, ink-repellent surface layer.

DE 24 34 098 discusses the firing of a composition of aluminum phosphate and silicon carbide particles on metal surfaces to increase the wear resistance. However, the invention of German Patent No. 2434098 is not suitable for use in lithographic printing plates, and no coating is applied to the surface of aluminum.

Methods of treating lithographic aluminum substrates to increase surface area and enable anodic coatings are disclosed in U.S. Pat. It is well explained in the industry as in the book.

Although anodization has become the most common method of providing aluminum substrates into durable lithographic printing plates, and has slightly lowered energy requirements, this method still requires large amounts of electrical energy to operate. effluents are also generated which must be carefully disposed of to avoid environmental contamination.

A novel method for producing structured surfaces on aluminum master substrates for lithographic printing was disclosed in US Pat. No. 3,210,184. A layer of basestone (aluminum oxide-hydrate) is produced on an aluminum substrate by immersing the aluminum in hot water or steam in the presence of a weak organic base.
It has been shown that a printing original plate using a structured substrate can produce a much larger number of prints under similar conditions than a printing original plate using a mechanically roughened aluminum substrate.

US Patent Nos. 3,871,881 and 3,975,197 disclose other methods of enhancing the physical properties of aluminum surfaces. Various types of particulate materials are bonded to the aluminum surface with an in-situ generated aluminum hydroxyoxide binder. The use of reinforced aluminum articles as substrates for printing plates is proposed.

U.S. Pat. No. 4,319,924 discloses an aqueous coating composition consisting of dissolved phosphate, dissolved dichromate, dissolved aluminum, and dispersed particulate solid materials, preferably aluminum-containing materials, in coating-forming proportions. are doing. The composition can be heat cured at elevated temperatures to make it a water-insoluble material. The composition further contains diethanolamine in an amount sufficient to reduce the temperature at which it can be cured into a water-insoluble material.

The present description discloses that a novel method of processing lithographic quality aluminum foil can produce durable, continuously operable substrates for lithographic printing plate constructions. This method provides a new substrate capable of resisting the chemical effects of printing plate developers and press solvents. This new substrate also allows multiple image-forming photoreactive layers to be bonded to a treated aluminum substrate without the need for primers or other adhesion promoters.

SUMMARY OF THE INVENTION A method is disclosed for firing a solution of a monobasic phosphate, preferably aluminum phosphate, on an aluminum substrate or aluminum coated substrate surface. This method produces an aluminum sheet having on at least one surface a layer of a glass or polymorph of aluminum phosphate or a mixture of aluminum phosphate. This coating layer was found to be an excellent surface for adhesion of organic substances. In particular, the aluminum phosphate layer exhibits excellent adhesion to diasonium resins and photopolymerizable compositions used in the printing industry, especially in the lithographic printing industry.

Also disclosed is a method of firing a slurry of particles and phosphate binder. The particles are preferably weakly basic or amphoteric nonmetallic particles, and the composition is fired on an aluminum or aluminum-coated substrate. In this method, on at least one surface of the sheet, dehydration products of monobasic phosphates, such as salts of aluminum and/or magnesium, alone or in combination with the reaction products with some or all of the particles. An aluminum substrate or a surface-coated sheet with a structured layer of rigid particles bonded to each other in one or several water-resistant layers is produced. It has been found that this structured layer provides an excellent surface for adhesion of organic materials. In particular, phosphates strongly bind and adhere particles in certain layers in diazonium resins used in the printing industry, especially in the lithographic printing industry, and in particular have excellent adhesion to photopolymerizable compositions. Put it in. This adhesion is enhanced by the surface structure and improved chemical stability imparted by the particles.

[Detailed description of the invention]

The method according to the invention for making phosphate coatings on substrates provides certain improvements over prior art methods, particularly for producing substrates for photographic image-making elements in the continuous manufacture of substrates. It's on.
The coated substrates of the present invention not only have comparable or improved properties compared to prior art materials, but also exhibit significant economic advantages in manufacturing. The equipment used in the manufacturing process consists of fewer separate items of equipment, and therefore the required capital investment is less than in conventional methods of continuous substrate production. Important equipment that has been omitted includes anodizing equipment, which is inherently expensive due to its high energy requirements, and where the effluent must be safely disposed of.
Such equipment is preferably omitted from the substrate manufacturing chain because it is associated with electrochemical corrosion problems with other equipment in the same manufacturing chain. Coating layers produced according to the invention do not require etching or other structuring. Optionally, such further structuring can be used to impart additional properties to the surface. If such a structuring step is omitted, the cost will be further reduced. It has been found that the process can be easily carried out in a continuous process and gives substantially the same results as in a batch process.

A coating of a monobasic phosphate solution, or a monobasic phosphate solution slurried with metal oxide particles, is applied to the cleaned aluminum or aluminum-coated surface. This coating should be applied at least 450°C (230°C), preferably at least 500°C.
or fired at 550°C (260°C or 290°C) to produce a ceramic coating of phosphate glass. The presence of metal oxide particles and/or etching results in a structured coating. This coating, alone or in combination with reaction products with some or all particles,
consisting of nonmetal and especially metal oxide particles embedded in a glassy, water-resistant phase or phases of a dehydration product of a monobasic phosphate, such as a salt of aluminum and/or magnesium You can leave it there. Other acceptable monobasic phosphates include zinc, calcium, iron and beryllium salts. If the metal oxide is alumina, the bonding phase between the phosphate glass and alumina will likely be aluminum orthophosphate. Firing is at a temperature that ensures substantially complete dehydration of the coating;
It should be done for a long enough time. This can be done in as little as 3 seconds at the above temperatures, depending on the thickness and temperature of the coating and other parameters of the firing process. Ceramic surfaces can be further treated with etching to impart specific desired structure and properties to the surface, but the surface obtained by firing is already structured. This optional treatment is neither critical nor essential to the invention, and is a method of producing images that is optimized by silicate treatment of a substrate or other similar phase. (for example, a lithographic printing original plate) is most commonly used. For example, etching is
This can be done using known alkaline silicate solutions which simultaneously deposit silicate coatings. If silication is not required, or if the subsequently applied photosensitive composition is not compatible with the silicate surface, etching can be carried out, for example, in an alkaline phosphate or aluminate solution. . The surface of the aluminum or aluminum-coated substrate may first be structured such that etching of the ceramic coating exposes the structure through the ceramic coating. However, when implementing the invention,
This is unnecessary, as the structure will be generated naturally during the process. This natural structure is a microscopic structure that can be seen by light scattering or magnification, and is a physical structure to which a subsequently applied photosensitive coating composition can adhere.

The ability to remove any amount of dehydrated ceramic coating with an optional late firing etch is necessary to impart the required properties to the base structure. Small amounts as low as 5% by weight and 60% by weight
Even very large amounts of ceramic coating can be removed. The length of etching time is controlled by the temperature and pH of the etching environment.
The higher the temperature and the higher the pH level, the faster the etching. PH can be controlled with the addition of alkaline oxides such as sodium hydroxide. Replenishment solutions can be added during continuous processing operations to replenish any materials lost during etching, such as alkaline components. Because silicate etching has a broader range of action than phosphate or aluminate etching solutions, combined etching and silicate solutions are generally best suited for enhancing silicate treatments. The silicate used in the combined etching bath and silicate bath is preferably a commercially available material with a high silica content. Philadelphia Quartz Co.'s "Casile #1"
(Kasil #1)” or “S-35” or “S-
35'' and fine silica sol (for example, Nalco Chemical Co.'s Sol #1115 ((
Materials such as mixtures with Sol #1115))) are particularly effective when diluted with water to a solution of about 1% silica on a dry weight basis.

The substrate, which has become a ceramic-coated aluminum or a structure produced in a firing process on an aluminum-coated substrate, can then be coated with a photosensitive composition, either directly or with an intermediate sublayer. Preferably, an oligomeric diazonium resin and/or a negatively or positively acting photosensitive organic composition is applied to the surface of the structure.

A wide variety of photosensitive compositions with different fields of use are known to those of ordinary skill in the art. The types of photosensitive coatings useful in the practice of this invention are those commonly considered for use in the printing plate industry, particularly lithographic and letterpress compositions.
These compositions include both negative and positive acting lithographic compositions and negative acting letterpress compositions.

Negative effect compositions are typically made using photopolymerizable compositions that become less soluble and/or polymerize to a higher degree when exposed to actinic radiation in an image pattern. This typically includes binders, polymerizable substances (monomers, oligomers and polymerizables), photoinitiator catalysts for the polymerizable substances, sensitizers for the photocatalysts, and lipophilicity enhancers, pigments, surfactants, coating aids. and various other ingredients such as agents known in the art, and other ingredients known in the art. After exposing the image to actinic radiation, the unreacted, highly soluble regions of the coating composition are removed by washing with various solvents including water, aqueous alkaline solutions, and organic developers. Among the most common materials used to make negative effect lithographic compositions are ethylenically unsaturated monomers and photoinitiated free radical generators.

Although organic and methacrylic polymeric materials are the most frequently used components, other ethylenically unsaturated materials and copolymerizable components are all useful and known in the art. For example, US patent no.
Specification No. 4316949, Specification No. 4228232, No.
Specification No. 3895949, Specification No. 3887450, and No.
See specification No. 3827956.

Positive-acting lithographic compositions usually consist of a thermoplastic or partially cross-linked composition binder containing a positive-acting photosensitizer, which, when irradiated with light, , the sensitizer becomes more soluble in the selected solvent than a sensitizer that has not been exposed to light. The most common photosensitizers used in the industry are o-quinone diazide compounds and polymers. Acrylic resin, phenol formaldehyde resin (especially novolac), polyvinyl
Various binders such as acetal resins and cellulosic esters are also commonly known in the art for use with this type of photosensitizer.
For example, US Patent No. 4193797, No. 4189320
No. 4,169,732, and No. 4,247,616.

Negative effect letterpress compositions have a negative effect, except that the layers are fairly thick and when making letterpress images, molds and embossing are often used to print surface structures. It is processed in a manner similar to the planographic printing method.

Ceramic surfaces made on aluminum substrates have been shown to be highly water receptive and at least as hydrophilic as anodized aluminum. The surface has excellent adhesion to polymeric and oligomeric compositions. It has been found that the surface exhibits particularly good adhesion to positively acting photosensitive compositions such as compositions containing diazo oxides and diazo sulfides. The surface also showed good resistance to the generally highly alkaline developing solutions used.

The thickness of the ceramic coating can be easily varied as desired, for example between 0.2 μm and 15 μm. For use as a substrate for lithographic image printing masters, the coating layer should be 0.3 μm.
and 10μm, preferably between 0.5μm and
More preferably, it is between 5 μm.

The firing temperature used when carrying out the present invention is
Must be higher than 450〓 or 500〓 (230℃ or 260℃). Preferably it is at least 550°C (285°C). Temperatures higher than 700° C. (370° C.) increase the energy requirements of the process without exhibiting any significant advantage, and may distort or weaken the substrate. These temperatures relating to the surface temperature of the coating were measured by contacting the surface of the coating with the bare contacts of a thermocouple. Naturally, a large number of different types of furnaces with different control characteristics can be used to achieve the required surface temperature. The controlled temperature may in fact be substantially different from the surface temperature measured in the manner described above.

The particulate matter added to the monobasic phosphate to form the slurry can vary widely and can consist of virtually any non-metallic inorganic particles. Non-metallic means that the particles contain a sufficiently high proportion (25% by weight on the surface) that they may interfere with the lithographic printing composition.
This means that there should be no free metal.

It goes without saying that the term "particulate" used in the practice of the present invention includes particles within a wide range of particle sizes. Particles small enough to create colloidal dispersions, such as particles as small as 5×10 ⁻³ μm in average particle size, and preferably from no smaller than 1×10 ⁻³ μm up to 45 μm, are quite effective. The preferred particle size range is 10 ^-2 μm.
45μm, the most preferred range is between ^10-2 and
It is between 5 μm. If highly reactive particles are used, they will actually dissolve (in whole or in part) due to the reaction of the substances emitted from the surface of the particles. Thus, surprisingly, large particles can be used without being hindered by the physical properties of the surface. Agglomerates with particles of virtually large size that can be broken up during processing can also be used.

For example, metal oxides include alumina (α-, β-,
various phases such as θ- and γ-alumina), chromia, titania, zirconia, zinc oxide, stannous oxide, stannic oxide, beryllia, boria, silica, magnesium oxide, and the like. Certain oxides and certain phase-different oxides, or even mixtures thereof, may be used better than others. For example, the use of mixtures of certain reactive transition aluminas, such as alpha-alumina and theta-alumina and gamma-alumina, yields surfaces with improved properties over those obtained with single phase alumina particles. The presence of the alpha phase in the slurry results in a highly wear-resistant ceramic coating, while the presence of other phases or other metal oxide particles gives the surface a finer structure than alpha alumina alone. tend to occur. In "reactive",
This means that the oxide reacts with the monobasic phosphate during the firing conditions.

Particulate materials that react with acids or monobasic phosphates produce binder compositions that are highly alkaline resistant. If such materials are added in amounts above those that fully react with the phosphates, they will further contribute to the structure of the surface of the fired coating. If they are in a form that reacts slowly or not at all at room temperature, they will contribute to the consistency or viscosity of the slurry and may be particularly well suited to specific coating methods. Becomes a prescription product. Furthermore, some of these substances enhance or weaken the hydrophilicity of the phosphate coating in a controlled manner. In short, in this case,
hydrophilic and hydrophilic properties that maximize resistance to alkaline attack, maximize slurry solids fraction and slurry viscosity for a particular coating method, and are most compatible with the intended image coating method. A mixture of finely divided reactive materials can be added to the slurry, resulting in a microstructure.

The most preferred reactive inorganic material present is a magnesium compound. Magnesium carbonate, magnesium oxide, magnesium hydroxide, and magnesium phosphate were used, but in each case made a distinctive and favorable contribution to alkali resistance. Zinc oxide, zinc carbonate or zinc phosphate can be substituted for the magnesium compound, although the alkaline resistance provided by the zinc compound is slightly less than that provided by the magnesium compound.

The amount of magnesia, i.e. the amount of magnesium oxide or magnesium hydroxide that is generally added, is not sufficient to yield a completely tribasic (dehydrated) phosphate composition upon calcination, thus providing polyvalent cations. Addition of other substances that cause alkali resistance generally results in further alkali resistance. Hydrated or transitioned alumina, sols of many metal oxides, or mixtures of these materials can be added, generally together with magnesia, and generally in proportions to maximize coating as described above. . Supplier: Micro Abrasives Corp., Westfield, Mass., USA; GB2500
The γ-θ-grade alumina is produced by Aluminum Co. of America.
Hydral alumina supplied by Hydral
710, Condea Chemie, 2000 Hamburg 13, West Germany.
``Dispural'', a mostly boehmite product supplied by GMBH, West Germany, D-6000
Degussa Pigments in Frankfurt 1
Division)'s "Aluminum Oxide C"
(Aluminum Oxide C) and alumina, chromia, ittria, zirconia and ceria sols supplied by Nyacol Inc., Ashland, Mass., USA, were combined with the proposed magnesium compound. Examples of reactive substances that are effective as This catalog is intended to be indicative rather than exhaustive. Many other compounds are expected to be useful as reactive agents in sol or fine powder form. Titanium dioxide, calcium hydroxide, calcium oxide, calcium fluoride or calcium phosphate, beryllium oxide, ammonium fluorotitanate, and tungsten oxide have been suggested in the literature as effective components of phosphate glasses.

The resulting calcined slurry accepts moderate levels of alkali metal oxides, such as are generally acceptable for industrial grade materials; however, compounds containing major amounts of alkali metal cations are not recommended. When adding silica sol, special metal oxides to compensate should also be added to optimize alkali resistance.

In addition to reactive inorganic particulate materials, or some admixtures thereof, particles of hard, wear-resistant materials can be added with good results. Generally, these are expected to react with the phosphate binding substance only superficially, but are not expected to contribute substantially to insolubilization. "381200 Alundum" type α supplied by Norton Co., Troy, New York, USA
- grade alumina or "WSK 1200" white alumina supplied by Treibacher GMBH, Treibach, Austria, and various grades of "WCA" alumina supplied by Micro Abrasive. Useful. Some of these materials require furnace firing to burn off organic contaminants. Tin oxide of a grade supplied by Transelco, Inc., Penn Yan, New York, USA, was substituted or mixed with alumina in various proportions without sacrificing properties. fine-grade sands of other hard materials such as quartz, amorphous silica, cerium oxide, zirconia, zircon, spinel, aluminum silicate (mullite), and even hydrophobic particles such as silicon carbide ( Although less attractive in terms of cost and effectiveness as a tightly sized powder (compared to alumina), it is expected to perform well. The practice of the invention includes hydrophilic particles,
Particular preference is given to using metal oxides.

These hard particles contribute abrasion resistance and roughness to the fired coating. The amount and particle size to be added will vary with the desired image coating method to the extent that compatibility depends on roughness, which can be measured as the "Arithmetic Average Roughness" using a profilometer. depends on the development of optimal compatibility. An example of such an instrument is the one manufactured by Federal Products.
Products Corp.) ((Providence)
)), RI), and Bendix Co., Ann Arbor, Michigan ((
This is the ``Proficorder'' from Ann Arbor, Mich.))).

It is known that different methods of structuring lithographic substrates and variations in conditions within these methods result in different ranges of arithmetic mean roughness and different combinations of arithmetic mean roughness and specific surface area. The optimal combination of these properties depends on the type of use to be made of the final lithographic printing plate and the particular photosensitive composition added thereto. Important properties that must be considered in selecting the combination of these properties with a particular photosensitive composition include mechanical adhesion and release properties (e.g., developability) of the imaged coating. By adjusting the size, type, fractionation, and mixture of particles in the coating composition, the coating method of the present invention covers most of the range of roughness and special surface areas encountered in all prior art methods. A substrate can be provided. The method of the present invention is highly flexible and can be easily modified to provide substrates suitable for changing requirements.

It should be pointed out that the invention can be practiced by making aluminum phosphate or other acidic phosphates in situ during the calcination process.
This can be done, for example, by coating the aluminum or aluminum coated surface to be fired with a slurry of phosphoric acid and a stoichiometric excess of reactive alumina. Aluminum phosphate is formed during the initial firing period and, in the presence of a stoichiometric excess of alumina, particulate reactive alumina material remains in the reactive composition during the continuation of firing. This is sufficient to make a coating according to the present invention, and the production of aluminum phosphate or other aluminum phosphates or mixed phosphates of aluminum and other metals is within the scope of the practice of this invention. Because there is, it is done on the spot.

In addition to the above in situ production by reaction of excess metal oxide or hydroxide with phosphoric acid, stoichiometric equivalent amounts of reactive alumina, i.e. aluminum oxide or hydroxide, can be reacted with phosphoric acid or Formation of aluminum phosphate in situ, either by reaction with acidic phosphates of alkaline earths, such as phosphate-magnesium solutions, or mixing aluminum with other metals in situ. Phosphates can also be produced. The following equivalence shows that aluminum phosphate can be replaced with a reaction mixture containing alumina and phosphoric acid or an alkaline earth acid phosphate.

3Ca(H ₂ PO ₄ ) ₂ +Al ₂ O ₃ =2Al(H ₂ PO ₄ ) ₃ +3CaO 3Mg(H ₂ PO ₄ ) ₂ +Al ₂ O ₃ =2Al(H ₂ PO ₄ ) ₃ +3MgO Al(OH) ₃ +3H ₃ PO ₄ =Al(H ₂ PO ₄ ) ₃ +3H ₂ O Al ₂ O ₃ +6H ₃ PO ₄ =2Al(H ₂ PO ₄ ) ₃ +3H ₂ O The above reactions are not necessarily of practical importance.

Additionally, alkaline earth acid phosphates can be made as a solution by mixing the appropriate alkaline earth tribasic phosphate with phosphoric acid.
For example, Ca ₃ (PO ₄ ) ₂ +4H ₃ PO ₄ =3Ca(H ₂ PO ₄ ) ₂ Mg ₃ (PO ₄ ) ₂ +4H ₃ PO ₄ =3Mg(H ₂ PO ₄ ) ₂ Mg ₃ (PO ₄ ) ₂ +4H ₃ PO ₄ =3MgHPO ₄ The following reaction illustrates the process by which orthophosphate is produced during calcination with phosphoric acid and/or a suitable acidic phosphate starting material.

3H ₃ PO ₄ ＋Al ₂ O ₃ → △2AlPo ₄ ＋3H ₂ O Al(H ₂ PO ₄ ) ₃ ＋Al ₂ O ₃ → △ 3AlPO ₄ ＋3H ₂ O Al(H ₂ PO ₄ ) ₃ ＋3MgO → △ AlPO ₄ ＋Mg ₃ ( PO ₄ ) ₂ +3H ₂ O 3Mg(H ₂ PO ₄ ) ₂ +2Al ₂ O ₃ → △ 4AlPO ₄ +Mg ₃ (PO ₄ ) ₂ +6H ₂ O 6Ca(OH) ₂ +3Mg(H ₂ PO ₄ ) ₂ → △ 2Ca ₃ (PO ₄ ) ₂ +Mg ₃ (PO ₄ ) ₂ +12H ₂ O The addition of calcium-containing inorganic compounds to the slurry can lower the calcination temperature to produce a mixture that dehydrates effectively at slightly lower temperatures or in shorter times. We have found that there is less need for intensive monitoring. Addition of calcium is calcium hydroxide,
Preference is given to working in the form of calcium carbonate, calcium oxide, calcium phosphate or mixtures thereof. In order to obtain this effective result, it is still preferable to add the magnesium-containing compound as a soluble phosphate and the aluminum-containing compound in ultrafine and/or dissolved form.

The addition of calcium-containing inorganic compounds to the slurry contributes to the ability of the coating composition to be fired at lower temperatures or shorter times, while maintaining lithographic quality, which is not conventionally possible. It was also found that the thickness of the coating increased more than expected. The aluminum-containing compound may be, for example, fumed alumina produced by flame hydrolysis of anhydrous aluminum chloride and having a final average particle diameter of less than 20 nm. If all the components necessary to react to form a tightly dispersed, homogeneous phosphate phase are in the most rapidly reactive form commonly available as feed chemicals;
Better functional properties are obtained with shorter firing times and/or lower temperatures. Too much stoichiometric excess of reactive cation-donating materials over anion-donating materials, i.e., phosphates and silicates, tends to mechanically weaken the coating and
It should be pointed out that - ASTM tests C501-66 and D1044-76, or tests that combine some of the characteristics of each of the two standard tests, result in inferior abrasion resistance than the types described.

The slurry or solution generally contains between 85% and 95% (by volume) of the material that evaporates upon firing, with the actual amount being sufficient to provide sufficient coating weight and coverage for the selected coating technique. This is the amount required. A mixture of a 50% aqueous solution of aluminum phosphate and an equal weight of water easily falls within this range, as do slurries containing multiple additives.
The volatile substance is generally water, although substantial amounts of volatile substances that are miscible with water, such as alcohols, can be added. The volumes of volatiles mentioned above include both volatiles added as solvents or diluents and those generated in reactions such as thermal decomposition of organics or acid-base metathesis.

It may or may not exist, but
The second largest component of the slurry or solution is in the form of hard particles, such as the alpha-alumina mentioned above. These may consist of between 0% and 65% of the volume of the non-volatile part. The size, shape, volume and type of the hard particles will vary as necessary to suit the intended unique use of the ceramic coated material. Coatings containing more than 65% by volume of hard particles will shrink too much in the binder material so that the hard particles will not be tightly bound, and will leave no ink behind if the coating is used as a lithographic substrate. Ink tends to accumulate in the gaps between them in areas that need to be freed. The relatively predominant appearance of fired films containing 45% to 60% by volume of hard particles is rough. This type of surface is preferred for use in some image coatings. For fired films containing less than 50% by volume of hard particles,
The relative volume of the hard particles decreases, while the relative volume of the microfine particles increases, so that the surface has a pronounced microfine appearance. The ultra-fine appearance makes it more desirable for use in some image coatings. Sedimentation and agglomeration of hard particles may cause coating problems. When characterized by easy coating with simple equipment, the formulation preferably has a low volume or is completely free of coarse particles. It is believed that the hard particles contemplated for use in the present invention react so slowly with the phosphate solution that they undergo negligible reaction during calcination.

The remaining components of the slurry formulation are matrix or binding components. In its simplest form, it can be coated with just phosphoric acid and fired.
However, by using acidic phosphates such as aluminum phosphate and/or reactive particles such as alumina, effective properties are enhanced.

Greater chemical resistance than can be obtained with coatings derived from phosphoric acid used alone is necessary, or at least preferred. To further increase the chemical resistance, reactive particles that generate metal ions should be added to the phosphate solution in sufficient quantities to produce an orthophosphate or a mixture of orthophosphates upon calcination.

If the reactive particles are calcium ion producing species, approximately 0% of the amount that combines with available phosphate ions to produce calcium orthophosphate.
Amounts ranging from about 20% to about 20% are used. 20
If too much calcium is added, the slurry tends to agglomerate and reduce the acid resistance of the final article. Amounts ranging from about 4% to about 7% provide maximum reduction in firing temperature without significantly reducing acid resistance or slurry viscosity. Calcium content can be provided using a phosphate-calcium solution rather than particles that generate calcium ions.

When the reactive particles are magnesium ion producing species, amounts ranging from about 0% to about 35% of the amount that combines with available phosphate to produce magnesium orthophosphate are used. Amounts ranging from about 10% to about 20% are preferred. If magnesium-containing particles are added to the aluminum phosphate at levels greater than 35%, the resulting coating flakes off the aluminum substrate upon cooling down from the firing temperature. It can be seen that with amounts of magnesium lower than the 10% level, the contribution to alkali resistance is less than in the optimal case. MgO5.3% by weight
The amounts of magnesium and phosphate supplied in a commercially available magnesium phosphate-magnesium solution containing 32.6% by weight of P ₂ O ₅ and amount of
Since 19.1% of magnesium ions are added,
Can be used to supply magnesium ions.

The reactive particles that produce aluminum ions are
Amounts ranging from about 0% to about 200% of the amount that combine with all other metal ions and phosphate ions present or liberated during calcination to yield the stoichiometric amount of orthophosphate. Can be added. The preferred range is 100% to 150%. For example, if the amount of calcium-containing material in the phosphate solution slurry is 5% of the amount that yields calcium orthophosphate, and the amount of magnesium-containing material in the phosphate solution slurry is 15% of the amount that yields magnesium orthophosphate. In the case that
The preferred amount of aluminum ion-containing material to be added ranges from 80% to 130% of the amount yielding aluminum orthophosphate. If another reactive cation is present, provide sufficient additional aluminum ions in excess of 100% to 150% of the orthophosphate level to give the desired composition. (e.g., if the other cation is silica, sufficient additional aluminum ion-containing material must be provided to make aluminum orthosilicate). Aluminum contents lower than 100% result in coatings with poor chemical resistance, and aluminum contents higher than 150%, in combination with typical additions of hard particles, lead to a reduction in the abrasion resistance of the coating. The unreacted excess fine particles have utility as fillers or leveling agents, creating useful microstructures or chemical properties on the surface of the fired film. Increasing the overall fine aluminum reactive particle content to a range of 150% to 200% is believed to provide improved anchorage for the protective material to compensate for the loss of basic wear resistance. .

Dispersants such as gluconic acid can also be added to the slurry. Although alkaline dispersants such as sodium tripolyphosphate do not destroy the functionality of the present invention, they are not preferred. Pretreatment of the coarsest particles with colloidal silica provides a slurry that is more stable against settling.

Compositions useful in lithography can of course be coated onto ceramic surfaces. Such compositions include 1) an oligomeric diazonium resin;
2) Diazo oxides or esters with positive effects;
3) photopolymerizable organic compositions (such as ethylenically unsaturated materials, especially in the presence of free radical photoinitiators);
4) an oligomeric diazonium resin basecoat with a photopolymerizable organic composition overcoat, and 5) any of a variety of other well-known photosensitive compositions useful in lithographic printing.

These and other aspects of the invention will become apparent from the Examples below.

Example 1 Pre-cleaned aluminum foil was coated with a 50% by weight aqueous solution of phosphate-aluminum and dried below 100°C to a coating thickness of approximately 3 μm. The surface temperature of the coating was raised to 550㎓ (260°C) in 90 seconds in the oven and removed after 30 seconds at that temperature. US Patent No. 4247616
The positive acting photosensitive composition described in Example 3 of the above specification was coated onto the treated surface after it had been cleaned and dried. The composition adhered to the substrate and developed well after exposure.

Example 2 Pre-cleaned aluminum foil was mixed with 12% transitional alumina (usually γ-phase or θ-phase alumina with a diameter of 0.5 μm), 15% aluminum phosphate, and 0.75% magnesium oxide, by weight percentage.
(particle size less than 200 mesh) and 72.25% water. The coating dried to a thickness of approximately 3 μm.

The coated foil was placed in a furnace and the surface temperature of the coating was raised to 550㎓ (260℃) in 30 seconds. The residence time in the furnace was one and a half minutes. The coated foil was cooled, washed, dried, and then rolled up.

The rolled foil was then rolled out and coated with the positive acting photosensitive composition of the previous example.
The photosensitive layer adhered well to the substrate, and the development was clean without any undesirable undercuts in the halftone image. The extent to which the back area is easily corroded by alkaline developer is shown in Example 1.
It was less than the base of. The adhesion of the print was even better because there were fewer undercuts and the generated surface structure further increased the adhesion.

Example 3 The process of Example 2 was repeated, except that 1% zinc oxide was used instead of magnesium oxide, and a correspondingly small amount of water was used. Although the coated aluminum was found to have somewhat lower resistance to developer chemicals than the sheet of Example 2, it still showed excellent adhesion to the photosensitive layer and provided an effective printing plate surface.

Example 4 The process of Example 2 was repeated using the same coating composition as in Example 2, but with a firing time of 600
〓 (310℃). No differences were observed between the mechanical or chemical properties of the materials. Both appeared to be completely dehydrated.

Example 5 Reactive (e.g. θ-transition alumina) 8% alumina (nominally 0.5 μm diameter), 0.5% dead-burned magnesia (particle size 200 mesh or less), and 4.0% α-alumina (average diameter nominally 1.0 μm). The process of Example 2 was repeated using the coating composition containing: These were dispersed as a 30% raw solids slurry in a 0.5% aqueous solution of gluconic acid. Water and an aluminum phosphate solution were used to give the above weight percentages of metal oxide, and 15% by weight aluminum phosphate and 66% by weight water. Due to the α-alumina content, the calcined coatings were more abrasion resistant and the arithmetic mean roughness was higher. These additional properties are advantageous in many image coating systems.

Example 6 The calcined substrate of Example 2 was immersed for 21/2 minutes at 95° C. in a solution containing 5% by weight sodium silicate solution under the trademark "Star" of Quartz Corporation, Philadelphia, USA, and then Washed with deionized water spray and dried. This was coated with a negative oligomeric diazonium resin and a dry 8 μm coating of the negative photopolymerizable composition of Example 2 of US Patent Application No. 103,712, filed Dec. 14, 1979. The image was clearly developed with normal exposure and development. This produced thousands of well-inked impressions during a reduced abrasion test and was at least as good as the abrasion performance of the same imaging material on textured, anodized regular aluminum.

Example 7 Alpha of Norton's "#381200 Alundum" trademark
- 19.1% (by weight) alumina (cleaned by calcining overnight at 600°C in air before addition), 2.4% Alcoa's "Hydraul 710" alumina trihydrate;
Condea Hemy's "Despral 10/2" alumina hydrate 0.75%, Martin Marietta's "Mag Chem"
Chem) 10'' consisted of 0.36% magnesia and 14.4% 50% aluminum phosphate solution, and some surface-active substances were added thereto to prepare a slurry as described below. The dry powders were ground together as a 30% solids slurry. First, only α-alumina
A 30% slurry was milled for 1 hour in a solution containing all of the water and 2% by weight alumina as Nalco "Nalcoag 1115" colloidal silica.
Then add enough 50% gluconic acid to separate the aqueous phase.
Acidify to 0.5% and add the remainder of the dry solids;
And the grinding was continued for 12 hours. Add a weighed sample of the 30% slurry to a container containing enough additional distilled water and a 50% solution of aluminum phosphate to the proportions above, stir the formulation with a propeller stirrer, and mix the trisodium phosphate ( 3% solution at 160〓)
Roll coating, etching, cleaning, and cleaning of the aluminum alloy sheet
It was then decontaminated in 50% nitric acid, washed and dried. The coated sheet was air-dried in the air and fired for 2 minutes in a furnace with a circulating air temperature of 650° on a furnace control thermometer. (We had previously found that the surface temperature would be 550° during the last 30 seconds of this thermal exposure.) Cooling and positively acting images of the diazooxide-phenolic resin type known in the art. Upon coating with the composition, the resulting lithographic printing master was able to exhibit acceptable performance in terms of image contrast, developer resistance, and abrasion life as measured by a time-reduced abrasion test.

Example 8 The proportions were 17.8% of α-alumina with a grade of 1200, 3.2% of Alcoa's "Hydral 710", 0.7% of Condea's "Dispral 10/2", and 0.38% of MgO, and the grinding time was set to α-alumina in silica sol. against 30
minutes, 4 hours on total solids at 40% solids, phosphate addition is a 50% solution of phosphate-aluminum
A slurry was prepared, coated, and fired as in Example 7, except that it was 15.4%. The obtained slurry is etched,
It can be easily roll coated onto clean aluminum and is also a motor driven cylindrical “Scotch-brite” Type A
Oakite (150〓) was polished at the same time on pre-cleaned lithographic aluminum alloy.
Sprayed with a 3% solution of "#166" metal cleaner, then washed and air dried. The obtained lithographic original plate is Example 7
conformed to the standards set for

Example 9 Example 8 was applied to Bethlehem Steel Co.'s "Duraskin" sheet, which is a steel sheet plated with an aluminum-zinc-silicon alloy, with the second portion being aluminum.
The slurry was roll coated and rerolled to a thickness of 0.010 inch. The Duraskin sheet was pre-cleaned using the same Scotchi-Brite polishing technique as described in Example 8. The fired material works very well as a substrate for lithographic printing plates with either negative or positive action, long wear life, and Example 8.
No significant differences were observed in the contrast or resolution of the images or their abrasion characteristics between the lithographic masters.

Example 10 Illinois Minerals Co., Cairo, Ill., USA.
It is called "Imsil A-10".
Amorphous silica 19.05 with an average particle diameter of 2.2 μm
% (wt/wt), 0.65% "Aluminum, Oxide C", called by Degutsa Pigments Division, Frankfurt, Germany, with particles having an average diameter of 0.02 μm, 32.9% deionized water,
and Mobil Chemical
Co.) 50% solution of phosphoric acid-aluminum 47.4%
A slurry consisting of First the silica and colloidal alumina were mixed in water and then the phosphate solution was added. This slurry was coated on the substrate of Example 7, and fired in the same manner as in Example 7. This was then immersed for 25 seconds in a solution at 80° C. containing 4.8% by weight of potassium silicate solution "Kasil No. 1" available from Philadelphia Quartz, washed with deionized water, and air-dried. The resulting sheet was primed with a negatively acting diazo compound and protected with a negatively acting photopolymer of the type well known in the art. The resulting printing master was exposed to a test negative and exposed to a 3M Subtractive Developer.
Developer). Its photographic speed, contrast, resolution and print life were found to be commercially acceptable.

Example 11 Alpha of Norton's "#381200 Alundum" brand
- Alumina 15.08% (by weight) (cleaned by calcining overnight at 600°C in air before addition), 15% aqueous suspension of "Nalcoag 1115" colloidal silica 0.45
% (by weight), 50% aqueous solution of gluconic acid 0.45% (by weight), deionized water 62.12% (by weight) "Aluminum Oxide C" manufactured by Degutsa Pigments Division, Frankfurt, Germany 2.72
% (weight), Condair Hemy's "Despral 1"
0/2" Alumina Hydrate 0.96% (by weight), 50% Aluminum Phosphate, sold by Mobile Chemical Company
% aqueous solution 4.13% (by weight), commercially available magnesium phosphate solution 13.48% (by weight) containing 3.3% magnesium and 14.2% phosphorus sold by Mobile Chemical Company, and reagent calcium hydroxide 0.61% (by weight).
A slurry consisting of 325 this prescription product
The lithographic aluminum was coated with a coating weight ranging from 400 mg/sq. ft. to 400 mg/sq. ft. and baked at a temperature of about 550° C. for 1 minute. When cooled and coated with positive-acting compositions of the diazo oxide-phenolic resin type well known in the art, the resulting lithographic printing master has improved resolution, ink/water balance, and time reduction. It was able to show normal performance regarding the wear life measured in the wear test.

Example 12 Tribatsher “WSK” F1200 alumina (cleaned by calcining at 600°C before addition) 18.64%
(Weight), "Nalcoag 1115" Colloidal Silica 15
% aqueous suspension 0.56% (by weight), 50% of gluconic acid
Aqueous solution 0.44% (by weight), deionized water 58.64% (by weight), "Aluminum Oxide C" 4.21% (by weight) manufactured by Degutusa Pigments Division, Frankfurt, Germany, Mobile.
Magnesium 3.3% and phosphorus sold by Chemical Company
Commercial magnesium phosphate solution containing 14.2%
17.00%, and reagent calcium hydroxide 0.51%
A slurry consisting of (by weight) was produced. This formulation was coated onto lithographic aluminum at coating weights ranging from 325 mg/sq. ft. to 400 mg/sq. ft. and baked for 1 minute at a temperature of about 550°. Upon cooling and coating with a positive acting composition of the diazo oxide-phenolic resin type well known in the art, the resulting lithographic printing plate exhibits excellent resolution, ink/water balance, and time-reduced abrasion testing. Regarding the wear life measured in , normal characteristics could be shown.

Example 13 Pre-cleaned, grain-free aluminum foil was coated with a 25% by weight aqueous solution of phosphate-aluminum and dried at above 100°C to a coating thickness of approximately 3 μm. Raise the surface temperature of the coating to 550〓 (260℃) for 90 seconds in the oven.
It was left at that temperature for 30 seconds before being removed. The positive acting photosensitive composition described in Example 3 of US Pat. No. 4,247,616 was coated onto the treated surface after cleaning and drying. The composition adhered well to the substrate and gave clear development after exposure.

Example 14 Alumina (nominal diameter
0.5 μm) 12%, aluminum phosphate 15%, magnesium oxide (particle size 200 mesh or less) 0.75%,
and 72.25% water. The coating dried to a thickness of approximately 3 μm.

The coated film was placed in a furnace and the surface temperature of the coating was raised to 550㎓ (260℃) in 30 seconds. The residence time in the furnace was 1.5 minutes. The coated film was cooled, washed, dried and rolled up.

The foil was then rewound and coated with the positive acting photosensitive composition of the previous example. The photosensitive layer adhered well to the substrate, and there were no undesirable halftone cuts in the image, and the development was smooth.

Example 15 The process of Example 14 was repeated, except that 1% zinc oxide was used in place of magnesium oxide and a correspondingly lower amount of water was used. Although the coated aluminum was somewhat less resistant to developing chemicals than the sheet of Example 14, it still showed excellent adhesion to the photosensitive layer and provided an effective lithographic original surface.

Example 16 Same as the previous three examples, except that it was roughened with a rotating brush loaded with an abrasive slurry such as pumice to provide a surface structure useful for mechanically abraded lithography, which is well known in the art. A similar aluminum foil was coated with a 25% aqueous solution of phosphate-aluminum, dried at 300 °C for 1 minute in still air, then 1 minute at 300 °C in flowing air, and baked for 1 minute. The surface temperature was raised to 550〓. The coated film was then immersed for 90 seconds at 95° C. in a solution containing 4.8% by weight of Kasil #1 potassium silicate solution (Philadelphia Quartz), 0.03% potassium hydroxide, and the balance water. Silicate treated foil in deionized water spray
It was washed for 30 seconds, dried and coated with a negative acting photopolymerizable composition containing acrylate monomer and photosensitizer to a thickness of 12 μm. The master was split in half and the other half was a factory-made master with the same photopolymerized composition on aluminum with standard anodization, fixed side by side and processed through thousands of printing operations to create an aluminum phosphate coating. The original plates produced at least as much good printing as the factory-made anodized plates before they wore out.

Example 17 A sample prepared as in Example 16, phosphate coated, fired, and etched similarly except that a 5.25% by weight aqueous solution of Philadelphia Quartz S-35 sodium silicate was used. However, when coated with a layer capable of producing similar images and subjected to similar tests, the performance was still comparable to commercially available anodized master plates.

Example 18 A phosphate-coated, calcined and etched rough-surfaced aluminum was prepared as in Example 16, except that the same etching was carried out with a solution of sodium prophosphate at pH 10.4 at 70°C. The plates were coated with a positively acting photopolymerizable composition and tested in the same manner as on the factory master plates. Before it showed wear, it was able to print several times more than the Tartan 25 master, which had a roughened surface like the experimental master, but had no hard coating or anodization.

Example 19 "Nalco 680" manufactured by Nalco Chemical Company, prepared as in Example 16 except etching with a solution of sodium aluminate at pH 10.4, phosphate coated and calcined. A similar test was conducted using aluminum foil with a rough surface etched as described above. This allowed several times as many prints as the factory original before showing signs of wear.