The invention relates to particles with an opalescent effect, which have a particle size in the range from 5 xcexcm to 5000 xcexcm, comprising monodisperse spheres having a diameter of 50 nm to 2 xcexcm with a standard deviation of less than 5% in a packed and regularly ordered structure which is three-dimensional in terms of domains and is mechanically stabilized by physical or chemical modification.

The invention relates to pigments, especially interference pigments, which are characterized by a three-dimensional periodic arrangement of monodisperse spheres in the nanometer range.
Natural precious opals comprise monodisperse, regularly arranged silica gel spherules with diameters of 150-400 nm. The colour play of these opals comes about by Bragg-like scattering of the incident light at the lattice planes of the spherules, with their crystalline arrangement.
There has been no lack of attempts to synthesize white and black opals for jewellery purposes, using waterglass or silicone esters as starting material.
U.S. Pat. No. 4,703,020 describes a process for producing a decorative material comprising amorphous silica spherules in three-dimensional, arrangement with zirconium oxide or zirconium hydroxide in the interstices between the spherules. The spherules have a diameter of 150-400 nm. Production takes place in two stages. In a first stage, silica spherules are caused to sediment from an, aqueous suspension. The resulting composition is then dried in air and subsequently calcined at 800xc2x0 C.
In a second stage, the calcined material is introduced into the solution of a zirconium alkoxide, with the alkoxide penetrating into the interstices between the spheres and with zirconium oxide being precipitated by hydrolysis. This material is then calcined at 1000-1300xc2x0 C.
In comparison to a natural opal, the material obtained possesses zirconium dioxide in the voids between the individual spheres.
The material is given mechanical stability firstly by inclusion of the zirconium oxide and also, very substantially, by the calcining, which, as is known, modifies the physical and chemical structure of the material. The production process described here has the disadvantage that the material has to be calcined a number of times at high temperatures. It is, consequently, a very energy-consuming process.
It was an object of the present invention to avoid the abovementioned disadvantages. The intention was in particular to provide a particulate material which exhibits opalescent effects similar to those of natural opal while having sufficient mechanical stability. A further object of the invention was to provide a preparation process for such a material that allows defined particles suitable for use as pigments to be obtained with optimized energy consumption.
The present invention therefore first provides particles with an opalescent effect, which have a particle size in the range from 5 xcexcm to 5000 xcexcm, the particles comprising monodisperse spheres having a diameter of 50 nm-2 xcexcm with a standard deviation of less than 5% in a three-dimensional, regularly ordered structure which is closely packed in terms of domains and is mechanically stabilized by physical or chemical modification.
The present invention further provides a process for preparing particles, where, in one step
a) monodisperse spheres having a diameter of 50 nm to 2 xcexcm with a standard deviation of less than 5% are suspended in a liquid medium,
b) the suspension is applied to a surface, and
c) the liquid medium is removed.
The invention further provides for the use of the particles of the invention as pigments especially in paints, varnishes, printing inks, plastics, ceramic materials, glasses and cosmetic formulations. For this purpose they may also be used together with customary commercial pigments, examples being organic and inorganic absorption pigments, metal effect pigments and LCP pigments. Furthermore, the particles of the invention are also suitable for producing pigment preparations and for producing dry preparations, such as granules, for example.
With the particles of the invention, the three-dimensionally packed and regularly ordered structure is particularly important for achieving the opalescent effect. Normally, this three-dimensionally packed and regularly ordered structure is not a perfect order extending over the entire particle. For achieving the desired colour effects, it is sufficient for the particles of the invention to have individual domains within which there is a uniform arrangement. For the explanation of this structure, reference may be made in particular to FIGS. 1 and 2, which show precisely the presence of ordered domains of monodisperse spheres and yet at the same time show that in this case there is by no means close, let alone very close, spherical packing for the particle as a whole.
Also important for the particles of the invention with opalescent effect is the physical or chemical modification for mechanical stabilization, since without such stabilization the particles would not be fixed in their three-dimensional form. Nevertheless, the modification cannot be made by just any mode of mechanical stabilization, since otherwise the opalescent effect, as already explained above, would be impaired. The difference in refractive index between the spheres and the material in the interstices critically influences the optical properties of the particles. Therefore, preference is given to those physical or chemical modifications which make it possible to maintain an appropriate difference in refractive index. In principle, the effects according to the invention may be observed with differences in refractive index in the range from about 0.01 to about 2. The optimum difference in refractive index for opalescent pigments is in the range from about 0.1 to 0.6, although much smaller or even larger differences in refractive index are suitable for exhibiting opalescent effects. With small differences in refractive index, such as from about 0.01 to about 0.02, the particles-are substantially transparent and therefore show particularly pronounced opalescent effects owing to the many effective reflection planes. Because of the transparency, however, the intensity of these effects is weak.
The monodisperse spheres used, including any coatings that may be present, possess a diameter in the range from 50 nm to 2 xcexcm, preference being given to the use of spheres having a diameter of 150-1500 nm. Particular preference is given to using spheres in the range from 200-500 nm, since with particles in this order of magnitude the reflections of different wavelengths of visible light differ distinctly from one another and, accordingly, the opalescence occurs to a particularly pronounced extent in a variety of colours. In one variant of the present invention, however, it is also preferred to use multiples of this preferred particle size, which then result in reflections corresponding to the higher orders, and thus in a broad play of colour.
The monodisperse spheres may comprise almost any materials which are sufficiently transparent for the wavelengths of the desired light reflections, so that this light is able to penetrate several sphere diameters deep into the particle. Preferred spheres comprise metal chalcogenides, preferably metal oxides or metal pnictides, preferably nitrides or phosphides. Metals in the sense of these terms are all elements which may occur as an electropositive partner in comparison to the counterions, such as the classic metals of the transition groups and the main group metals of main groups one and two, but also including all elements of main group three and also silicon, germanium, tin, lead, phosphorous, arsenic, antimony and bismuth. The preferred metal chalcogenides and metal pnictides include, in particular, silicon dioxide, aluminum oxide, titanium dioxide, zirconium dioxide, gallium nitride, boron nitride and aluminum nitride and also silicon nitride and phosphorous nitride.
Starting material for the production of the particles of the invention preferably comprises monodisperse spheres of silicon dioxide which are obtainable, for example, by the process described in U.S. Pat. No. 4,911,903. The spheres are produced by hydrolytic polycondensation of tetraalkoxysilanes in an aqueous-ammoniacal medium, a sol of primary particles being produced first of all and then the SiO2 particles obtained being brought to the desired particle size by continuous, controlled addition of tetraalkoxysilane. With this process it is possible to produce monodisperse SiO2 spheres having average particle diameters of between 0.05 and 10 xcexcm with a standard deviation of 5%.
Further preferred starting material comprises SiO2 spheres coated with nonabsorbing metal oxides, such as TiO2, ZrO2, ZnO2, SnO2 or Al2O3, for example. The production of SiO2 spheres coated with metal oxides is described in more detail in U.S. Pat. No. 5,846,310, DE 198 42 134 and DE 199 29 109, for example. Coating with absorbing metal oxides, such as the iron oxides Fe3O4 and/or Fe2O3, also leads to particles which may be used in accordance with the invention.
As starting material it is also possible to use mondisperse spheres of nonabsorbing metal oxides such as TiO2, ZrO2, ZnO2, SnO2 or Al2O3 or metal oxide mixtures. Their preparation is described, for example, in EP 0 644 914. Furthermore, the process according to EP 0 216 278 for producing monodisperse SiO2 spheres may be transferred readily and with the same result to other oxides. To a mixture comprising alcohol, water and ammonia, whose temperature is set precisely using a thermostat to 30-40xc2x0 C., tetraethoxysilane, tetrabutoxytitanium, tetrapropoxyzirconium or mixtures thereof are added in one shot with intensive mixing and the resulting mixture is stirred intensively for a further 20 seconds, forming a suspension of monodisperse spheres in the nanometer range. Following a post-reaction period of from 1 to 2 hours, the spheres are separated off in a conventional manner, by centrifuging, for example, and are washed and dried.
Monodisperse polymer spheres as well, for example polystyrene or polymethyl methacrylate, may be used as starting material for the production of the particles of the invention. Spheres of this kind are available commercially. Bangs Laboratories Inc. (Carmel, USA) offer monodisperse spheres of a very wide variety of polymers.
Further suitable starting material for producing the pigments of the invention comprises monodisperse spheres of polymers which contain included particles, for example metal oxides. Such materials are offered by the company micro caps Entwicklungs- und Vertriebs GmbH in Rostock, Germany. In accordance with customer-specific requirements, microencapsulations are manufactured on the basis of polyesters, polyamides and natural and modified carbohydrates.
It is further possible to use monodisperse spheres of metal oxides coated with organic materials, for example silanes. The monodisperse spheres are dispersed in alcohols and modified with common organoalkoxysilanes. The silanization of spherical oxide particles is also described in DE 43 16 814.
The pigment particles produced from the monodisperse spheres and having an average particle size of 5 xcexcm-5 mm preferably possess a platelet-shaped structure.
A platelet-shaped particle of this kind is depicted in FIG. 1. In another preferred embodiment of the present invention, the particles possess a virtually spherical three-dimensional form, as shown in FIG. 2. Here as well, the average particle size is usually in the range from 5 xcexcm to 5 mm. This embodiment possesses the advantage that the pigments have no preferential direction. Consequently, when processed for example by polymer injection moulding, no streaks are formed as a result of preferential orientations of the pigments in the matrix.
The pigments of the invention may be produced in accordance with 2 alternative processes. In the case of the droplets process, the monodisperse spheres are suspended in a liquid medium in a concentration of preferably 1-35% by weight. The suspension is sprayed so that, on a surface, drops are formed.
Subsequently, the liquid medium is removed in such a way, preferably by drying under mild conditions, that the spheres order themselves partially.
In this context it is important that, on a smooth surface, the suspension is sprayed in such a way as to form individual drops which do not coalesce. Important for the shape of the particles formed is the wettability of the surface by the dispersion medium used. If the wetting tension is positive, i.e. the contact angle (regarding, the definition of the contact angle see, for example, Dxc3x6rfler, Grenzflxc3xa4chen- und Kolloidchemie, VCH 1994, page 34) is less than 90xc2x0, then the surface is said to be wetted by the liquid. In this case, the spherules in the drop are transported by capillary forces to the edge of the drop, resulting in the preferential formation of annular structures which are poorly suited to use as pigment particles. In order to form inventively preferred, compact, platelet-like, lens-shaped or seven spherical particles, however, the surface should not be wetted, or should not be completely wetted, i.e. the wetting tension is negative and the contact angle, therefore, is greater than 90xc2x0 (cf. FIGS. 1 and 2). The precise shape of the particles is also influenced by the concentration of the suspension, the initial drop diameter, the rate of drying, and the interaction between the suspended spherules and the surface.
Following the removal of the liquid medium in step c), the particles are then detached from the surface by a dry or wet method in a subsequent step d).
If the surface is smooth, particles having a preferential orientation are formed, in which identical reflection planes are at the same time in reflection position. Particularly intense reflections may be obtained in this way. Consequently, in one inventively preferred embodiment, the surface in question is a smooth surface.
Particles of particularly good quality may be obtained if the droplets are applied monodispersely. Dispersion media which may be used to disperse the monodisperse spheres include readily evaporable solvents, examples being alcohols, low alkanes, mixtures of organic solvents, and also water and solvent/water mixtures.
The preferably smooth surface onto which the droplets are sprayed may comprise glass, metal or plastic. A continuous strip of a heat-stable plastic or a metal, specifically stainless steel, is particularly suitable. Suitable plastics materials are polyethylene terephthalate, other polyesters, polyacrylates and, in particular, polytetrafluoroethylene.
As the spraying equipment it is possible, for example, to use modified ink-jet printers. The drops applied to the surface by spraying are dimensioned in accordance with the use of the pigment.
The drying of the droplets may be accelerated by supplying heat. Where a continuous strip is used, it is guided, together with the spray-applied drops, through a drying zone, which may comprise one or more sections. One preferred embodiment of the drying zone has a drying means in which drying is carried out using an IR dryer.
The individual particles formed, which are shown in FIG. 1 and FIG. 2 (recorded using a scanning electron microscope), may be separated from the smooth surface by means of a device. Separation may either be effected mechanically, by scrapers or brushes, or in a non-contact fashion by releasing a release layer or by means of ultrasound. Separation with a jet of liquid or of gas has proved to be advantageous.
An alternative process for producing the pigments of the invention with opal structure is continuous strip coating. A suspension of the monodisperse spheres, instead of being sprayed to form individual drops, is deposited in the form of a film of liquid on a support and, following sedimentation, drying and solidification, is comminuted into platelets of appropriate size. EP 0 608 388 describes the production of platelet-shaped pigments using a continuous strip process.
The process of the invention, especially in this embodiment, may also be used for the coating, and in particular the painting, of surfaces. Consequently, this use is also provided for by the present invention.
The continuous strip, which is guided over a system of rollers, passes through an application zone, where it is coated with a thin film of the dispersion of the monodisperse spheres in a solvent or water. The dispersion is applied in accordance with known methods by way of a roll system or a nozzle. This nozzle may be designed as a single-fluid or multi-fluid nozzle. In addition, in order to establish the thickness of the applied film, a variable diaphragm or an airbrush, in which a sharp jet of air is blown through a slit die, may be provided.
The coated strip is subsequently likewise passed through a drying zone. The coat which is formed is subsequently separated from the strip by means of a device. Separation may take place either mechanically by scrapers or brushes or contactlessly by release of a release layer, or by means of ultrasound. Separation using a liquid jet or gas jet has proved to be advantageous.
It is judicious to strengthen the opal structure by mechanically stabilizing the particles prior to their detachment from the surface, so as to ensure the required mechanical stability of the pigment particles. This stabilization may be carried out by means of the following physical and chemical measures.
The surface of the spheres is modified in order to effect crosslinking of the spheres during the formation of the opal structure or a better adhesion of the spheres to one another. To suspend the spheres in a liquid medium, it is possible preferably to add a compound which is hydrolysable in water and whose hydrolysis product deposits on the spheres in the course of the formation of the opal structure and brings about chemical bonding of the spheres to one another. In the case of silicon dioxide spheres, preferably tetraethyl orthosilicate is added to the suspension at temperatures of from 50 to 80xc2x0 C.; it hydrolyses to silicon dioxide and leads to chemical bonding of the spheres to one another. Alternatively, silicon tetrachloride may be used to treat the coated surface.
The particles of the invention may also be chemically stabilized by adding soluble silicates, examples being sodium silicate and/or polymerizable soluble aluminum compounds, to the suspension.
Stabilization, may also be achieved by treating the coated surface with soluble silicates. It is also possible to stabilize the particles physically by embedding them in transparent plastics or appropriate coating materials. In this case it is important that the embedding material is transparent and has a suitable refractive index which leads to an optimum difference in refractive index. For ease of processing of the embedding material, a coating material, for example, it is particularly advantageous for the material in question to be of low viscosity and to undergo little or no change in its volume in the course of curing. In one possible embodiment, the embedding material or its precursor is already present in the suspension in an appropriate volume fraction.
In a further embodiment of the strengthening of the opal structure, the surface of the spheres is modified with silanes which are then crosslinked with one another, during the formation of the opal structure, by means of heat or UV radiation. This crosslinking likewise leads to a strengthening of the opal structure. The silanization of monodisperse silicon dioxide spheres is described in more detail in DE 43 16 814.
The pigment of the invention may be used for pigmenting varnishes, powder coating materials, paints, printing inks, plastics and cosmetic formulations, such as lipsticks, nail varnishes, cosmetic sticks, compact powders, foundation, shampoos, and also loose powders and gels, for example.
The concentration of the pigment in the application system intended for pigmentation is generally between 0.1 and 70% by weight, preferably between 0.1 and 50% by weight, and in particular between 1.0 and 20% by weight, based on the total solids content of the system. It is generally dependent on the specific application.
Plastics comprise the pigment of the invention customarily in amounts of from 0.01 to 50% by weight, preferably from 0.01 to 25% by weight, in particular from 0.1 to 7% by weight, based on the mass of the plastic.
In the coatings sector, the pigment mixture is used in amounts of from 0.1 to 30% by weight, preferably from 1 to 10% by weight, based on the coatings dispersion.
In the case of the pigmentation of binder systems for paints, for example, and printing inks for gravure, offset or screen printing, or as a precursor for printing inks, for example in the form of highly pigmented pastes, granules, pellets, etc., pigment mixtures with spherical colorants, such as TiO2, carbon black, chromium oxide, iron oxide, and also organic colour pigments, for example, have proved to be particularly suitable. The pigment is generally incorporated in the printing ink in amounts of 2-35% by weight, preferably 5-25% by weight, and in particular 8-20% by weight. Offset printing inks may comprise the pigment in amounts of up to 40% by weight or more. The precursors for printing inks, in the form of granules, as pellets, briquettes, etc., for example, comprise in addition to the binder and additives up to 95% by weight of the pigment of the invention. The invention therefore additionally provides formulations which comprise the pigment of the invention.
The examples below are intended to illustrate the invention without limiting it.


A process for preparing yogurt takes advantage of the discovery that a form of modified whey characterized by a calcium content of at least 3%, protein content of from 10 to 20%, and a phospholipid content of at least 2%, has the ability to impart a creamy texture to yogurt while increasing its calcium content, Preferred products have calcium contents such that each serving contains from about 25 to about 50% of the Daily Value figure of 1000 mg per day.

The invention relates to preparation of creamy, calcium-fortified yogurt. In its more preferred aspects, it provides yogurt products having less fat than those prepared with whole milk, yet which have higher calcium contents and consistencies reminiscent of whole milk products.
Consumer interest in weight control and healthy eating is driving food processors to increase their offerings of foods having reduced fat contents and high nutritional value. Yogurt is perceived as a healthy food for a number of reasons. It is natural, contains calcium derived form milk and is associated with healthy digestion and other benefits. Typically, yogurt has a fat content only as high as cows milk, from which it is most often made. Even so, many health-conscious consumers would want even lower fat contents and even higher calcium contents. Unfortunately, the removal of fat decreases the smooth texture and nice color associated with yogurt, and the addition of calcium has caused a number of problems, including gritty mouthfeel and reduced protein heat stability.
While a number of efforts have been made to address these interrelated problems, the art is in need of effective solutions.
Yogurt has been prepared for centuries in essentially the same way. It was reportedly developed out of the need to preserve milk in warm climates like the Middle East. See, for example, Hui, Dairy Science and Technology Handbook, Vol. 2., Product Manufacturing, 1993, pp. 1-5. As originally developed, it has been considered a health food, but there is interest in reducing its fat content and/or increasing its calcium content. However, these modifications have proved to be significant technical challenges.
Yogurt is prepared by heating milk sufficiently to inactivate microorganisms in it, cooling from the high temperature, inoculating with a suitable culture (e.g., adding a small amount of a previous batch of yogurt), holding at a temperature near ambient or just above for long enough (e.g., 3 to 6 hours) for the active cultures to produce enough acid to coagulate the milk, and then cooling the resulting yogurt. A natural consequence of the culturing process is the production of lactic acid. The acid has several benefits, including creating a smooth, creamy texture, providing a clean, fresh taste and aiding preservation. If the yogurt is made with good manufacturing practices and cultured until the pH is less than about 4.6, the product should be stable for several weeks under refrigeration. Thus, maintaining the natural culturing process and results are important.
U.S. Pat. No. 5,449,523 to Hansen, et al., identifies a number of problems with adding calcium to yogurt. The patent indicates that some sources of calcium can cause grittiness and that others can cause the protein in milk to coagulate during heat treatment. Their solution to the problem involves adding chelating and/or alkaline agents, in addition to a calcium supplement, to maintain the pH above 6.7 prior to pasteurization. They were unable to identify any calcium supplement that did not require at least some change in the yogurt manufacturing procedure.
Attempts by the prior art to reduce fat in yogurt have also been met with technical challenges. By definition, yogurt must contain at least 8.25% milk-solids-non-fat before the addition of any bulky flavors. The milkfat content of regular yogurt must be at least 3.25%. (21 C.F.R. xc2xa7131.200) When either lowfat yogurt (21 C.F.R. xc2xa7131.203) or nonfat yogurt (21 C.F.R. xc2xa7131.206) is prepared, the fat content is reduced, thereby reducing the total solids and making the yogurt thin and watery. Various food additives have been identified to return the rheological properties and mouthfeel of these products to those of their full-fat counterparts. Widely used among these are whey and whey protein concentrates. Whey is the dried residue of the liquid obtained by the separation of curd in cheese making. Whey protein concentrate is a product obtained from whey wherein whey is xe2x80x9cmodified by partial or complete removal of lactose and or minerals, to increase the nonfat solids content of the foodxe2x80x9d (e.g., see 21 C.F.R. xc2xa7131.203(d)).
It is common for whey and/or whey protein concentrates to be employed along with other stabilizers such as gelatin, starch, vegetable and synthetic gums and the like. These materials as a group tend to increase the smoothness of the yogurt and decrease syneresis. An ideal stabilizer would yield a yogurt product which at the time of making and to the end of its shelf life, was the same in taste and texture as a full-fat, natural yogurt. The stabilizer should be easily mixed and should not adversely affect processing, flavor or texture. Stabilizers as currently available, however, do not significantly increase the calcium content.
There remains a need for a yogurt stabilizer and process for utilizing it that improves yogurt texture and increases the calcium content without adversely affecting taste, processing or product stability.
It is an object of the invention to provide a yogurt product with enhanced texture.
It is another object of the invention to provide a yogurt product with increased calcium content.
It is another object of the invention to provide a yogurt product having an enhanced smooth and creamy texture.
It is still another object of the invention to provide a yogurt-based product or ingredient with enhanced texture and/or calcium content.
It is another and more specific object of the invention to provide a process for preparing yogurt products having reduced fat contents, without sacrificing the viscosity and mouthfeel of yogurt prepared from whole milk.
It is yet another and more specific object of the invention to provide a process for preparing low-fat yogurt products exhibiting viscosity and mouthfeel reminiscent of yogurt prepared from whole milk.
It is another and more specific object of the invention to provide a process for preparing yogurt products having increased calcium contents, without causing processing, texture or stability problems.
It is yet another and more specific object of the invention to provide a process for preparing high-calcium, low-fat yogurt products exhibiting viscosity and mouthfeel reminiscent of yogurt prepared from whole milk.
These and other objects are achieved by the present invention, which provides a process for preparing a yogurt having an improved texture and containing active cultures, comprising: admixing milk with a modified whey characterized, on an as is basis, by a calcium content of at least 3%, protein content of from 10 to 20%, and a phospholipid content of at least 2% and a yogurt culture; holding the culture at a temperature and for a time effective to produce yogurt. The process is applicable to yogurt made from whole milk or meeting the standards for lowfat or nonfat products. The products prepared in the above manner are unique in composition and properties.
Many of the preferred aspects of the invention are described below.
Industrial Applicability
The following description will illustrate the preparation of preferred yogurt products according to the invention. The processing will be described in terms of the procedures effective for the materials employed in the various formulations.
The term xe2x80x9cyogurtxe2x80x9d is used herein to mean all of those products meeting the definition as set forth in 21 C.F.R. xc2xa7xc2xa7131.200, 131.203, and 131.206. Of the above sections, 21 C.F.R. xc2xa7131.203 specifically relates to lowfat yogurt and 21 C.F.R. xc2xa7131.206 specifically relates to nonfat yogurt. The invention improves the production of products of these types by providing better body and added calcium. For lowfat and nonfat products, the invention provides more of the body and mouthfeel of regular full-fat yogurt than has been achievable using ingredients described in the prior art.
The preferred products of the invention contain live and active cultures, as is required by the definition agreed to by the National Yogurt Association. Generally, these products are made by fermenting milk or a milk mix with a symbiotic blend of Streptococcus salvarius (e.g., subsp. Thermophilus) and Lactobacillus debruechii (e.g., subsp. Bulgaricus). See Hui, Dairy Science and Technology Handbook, Vol. 2., Product Manufacturing, 1993, pp. 1-55, and the references cited therein for a more detailed description, which is hereby incorporated by reference. The result is a semisolid fermented product having clean taste, a smooth texture and quick melting action in the mouth. Unlike prior art products, those of the invention contain more calcium and can be made with less fat while retaining a texture close to that desired of full-fat yogurt products.
Basic to all of the embodiments of the invention is a xe2x80x9cmodified wheyxe2x80x9d, which is defined as a whey fraction characterized, on an as is basis, by a calcium content of at least 3%, protein content of from 10 to 20% (more narrowly, 12 to 18%), and a phospholipid content of at least 2%. The calcium content is in highly soluble form and is homogeneously dispersed therein, as can be obtained by codrying a mixture containing the calcium, protein, fat and sugar components separated In these amounts to form the whey fraction. Calcium in this form is distinguished from calcium added as a salt that is simply mixed In dry form with whey. Preferred forms of modified whey are further characterized as conforming to the following analysis, based on a 100 gram sample.
This form of modified whey differs greatly from either sweet whey or whey protein concentrates and isolates, principally in the noted characterizing features set out above, and the ratios given directly below. Typical calcium to phosphorous ratios are within the range of from about 2:1 to about 10:1, e.g., about 5:2. Similarly, typical calcium to protein ratios are within the range of from about 1:4 to about 4:5, e.g., about 1:3. And, typical calcium to fat (essentially as phospholipid) ratios of from about 3:1 to about 10:1, e.g., about 4:1.
Products meeting these specifications can be prepared from whey by fractionation and drying to obtain the noted composition. Modified whey defined in this manner, derived from dairy products by fractionation, is believed to have its superior affects on yogurt prepared in accord with the invention because the high calcium content is complexed with other dairy components. Modified whey products of this type are commercially available, for example, under the trademark VersaPRO (e.g., grades B, C, D, E, M, N, S) from Davisco Foods International, Inc., Le Sueur, Minn.
A modified whey of this type is employed in an amount effective to improve the creaminess of the final yogurt. Preferred amounts will be at least about 0.25% based on the total weight of the formulation not counting bulky flavorings, and preferably within the range of from about 0.5 to about 2%. Preferred levels in lowfat and nonfat products are within the range of from abut 0.50 to about 1.25% on the same basis. Preferred products have calcium contents such that each serving contains from about 25 to about 50% of the Daily Value figure of 1000 mg per day.
The process of the invention entails treating milk containing the above form of modified whey to otherwise conventional processing. This is a surprising advantage of the invention. The milk is selected from any of the sources suitable and approved by the regulations, mixed with the modified whey and other additives such as flavors, sweeteners and stabilizers. The milk, or a milk mix containing other permitted ingredients, is heated under conditions effective to inactivate any organisms or enzymes. The milk or milk mix is then inoculated with a suitable culture (with a symbiotic blend of Streptococcus salvarius and Lactobacillus debruechii) and held for a time sufficient to develop the typical yogurt texture and taste. Holding at near 30 to 45xc2x0 C. for from 3 to 6 hours is typical. The final pH will typically be less than 5.0 (e.g., within the range of from about 4.2 to about 4.6). Following this step of culturing, the yogurt is cooled to slow down the culturing but not kill the culture.
The source of the milk can be any of those sources as by tradition, regulation or standard have come into favor. Principal among these are milk from cows, sheep, goats, buffalo, and the like. The milk can be fresh or in other forms permitted by regulation, including milk mixes with non-fat dry milk or the like. Various other materials can also be added to the milk mix prior to fermentation so long as they do not adversely affect the final quality of the yogurt or change its identity. For simplicity In description, the term xe2x80x9cmilkxe2x80x9d as used herein is also intended to include culturable milk mixes as permitted by regulation. The yogurt prepared according to the invention can be packaged plain or with sweeteners or flavors.
A sweetener is optional, but can be a sugar, sugary material or other sweetener, such as any of the high intensity sweeteners known to the art. The sweeteners can be employed directly in the milk or as part of a bulky flavoring that is added after fermentation. Bulky flavorings can be added to the bottom of individual containers in which the yogurt is cultured and ultimately distributed, or can be mixed into the yogurt following culturing. The bulky flavoring can be on the bottom of the container, sundae style, custard style or striped, as called for by the consumer interest desired.
Among the sugars are the mono-saccharides, di-saccharides and polysaccharides and their degradation products; e.g., pentoses, including aldopentoses, methylpentoses, keptopentoses, like xylose and arabinose; a deoxyaldose like rhamnose, hexoses and reducing saccharides such as aldo hexoses like glucose, galactose and mannose; the ketohexoses, like fructose and sorbose; disaccharides, like lactose and maltose; non-reducing disaccharides such as a sucrose and other polysaccharides such as dextrin and raffinose; and hydrolyzed starches which contain as their constituents oligosaccharides.
Among the intense sweeteners are acesulfame-K, aspartame, cyclamates, dihydrochalcone, saccharin, stevioside, thaumatin and the like. Also, low-intensity, low-calorie sweeteners such as sorbitol and erythritol can be employed.
Other ingredients may also be employed to impart their characteristic effects to the compositions of the present invention. Typical of such ingredients are flavoring agents, colorants, vitamins, minerals, and the like. Various flavors can be added directly to the milk prior to culturing if they do not interfere with the culturing process or afterwards if they would. Suitable flavoring agents can be employed to impart vanilla, cream, chocolate, coffee, maple, spice, mint, butter, caramel, fruit and other flavors.
When a bulky flavoring or sweetener is added to the yogurt after fermentation, the natural consistency of the yogurt is modified and it becomes necessary to add stabilizers of a type and in an amount sufficient to restore a natural yogurt-like texture. Stabilizers can also be added prior to naturally setting the yogurt for the purpose of enhancing smoothness and decreasing syneresis during long periods of storage. Typical of the stabilizers are proteinaceous materials such as gelatin, pectin, and whey protein concentrate, natural and synthetic hydrophilic colloids, such as carboxymethyl cellulose, vegetable gums such as locust bean gum, carob bean gum, guar gum, carggeenans and alginates and various starches and modified starches. The stabilizers are typically added prior to fermentation to assure thorough mixing with least affecting natural texture.
Tests have indicated that when bulky flavoring materials are to be mixed in with the yogurt subsequent to fermentation, the texture will be broken but can be essentially reestablished by utilizing effective amounts of stabilizers such as gelatin and/or starch, preferably before pasteurization. The starch and gelatin should be employed in amounts sufficient to restore a semisolid texture. It is an advantage of the invention that a very nice yogurt texture with a clean flavor can be achieved.
The following Examples are provided to further illustrate and explain a preferred form of the invention and are not to be taken as limiting in any regard, Unless otherwise indicated, all parts and percentages are by weight.


A method for the preparation of a negative working lithographic printing plate by means of ink jet printing is disclosed. This method uses a lithographic printing plate precursor comprising a lithographic support and an image forming layer containing a polymeric binder soluble in an aqueous alkaline developer. The precursor is image-wise printed by an ink jet fluid comprising a compound capable of reducing the solubility of the binder in the aqueous alkaline developer. After development a negative working printing plate is obtained.

The present invention relates to a method for the preparation of a lithographic printing plate by ink jet printing using a particular type of ink jet fluid.
Traditional techniques of printing include letterpress printing, gravure printing and offset lithography. All of these printing methods require a plate, usually loaded onto a plate cylinder of a rotary press for efficiency, to transfer ink in the pattern of the image. In letterpress printing, the image pattern is represented on the plate in the form of raised areas that accept ink and transfer it onto the recording medium by impression. Gravure printing cylinders, in contrast, contain series of wells or indentations that accept ink for deposit onto the recording medium.
In the case of traditional offset lithography the image to be printed is present on a plate as a pattern of ink accepting (oleophilic) areas on an ink repellent (oleophobic or hydrophilic) background. In the wet system the required ink repellency is provided by an initial application of a dampening (or xe2x80x9cfountain) solution prior to inking. Conventional presensitized lithographic printing plates bear a UV sensitive coating based on photopolymer or diazonium chemistry. The plates have to be UV-exposed through a mask carrying the image. The mask is a graphic arts film prepared by photographic techniques based on silver halide chemistry and involving exposure by a camera or by an image-setter, and further involving wet processing. Depending on the type of plate used (negative or positive) the non-image areas or the image areas are solubilized thereby differentiating the plate into oleophilic and hydrophilic areas. A disadvantage of this traditional method is the necessary cumbersome preparation of the photographic intermediate film involving wet processing. A further drawback is the wet processing of the printing plate itself.
With the advent of the computer in revolutionizing the graphics design process leading to printing, there have been extensive efforts to develop a convenient and inexpensive computer-to-plate system wherein a photographic intermediate is no longer required. In recent years some of these systems are introduced into the market based on different chemical systems and exposure methods. For instance, the SETPRINT material, trade mark of Agfa-Gevaert N.V. is based on silver halide DTR chemistry and consists of a polyethylene terephthalate base carrying a photographic coating which after photo-mode exposure and processing produces complementary oleophilic and hydrophilic areas. Another system based on photo-mode exposure but with a hydrophilic aluminum base is LITHOSTAR, trade mark of Agfa-Gevaert N.V. A system based on heat mode exposure by means of an intense infra-red laser is called THERMOSTAR, also a trade mark of Agfa-Gevaert N.V.
Many of the new computer-to-plate system are large, complex, and expensive. They are designed for use by large printing companies as a means to streamline the prepress process of their printing operations and to take advantage of the rapid exchange and response to the digital information of graphics designs provided by their customers. There remains a strong need for an economical and efficient computer-to-plate system for the many smaller printers who utilize lithographic printing. A number of electronic, non-impact printing systems have been investigated for use in making lithographic printing plates to satisfy the needs of these smaller printers. Foremost among these have been laser printing systems, for example as described in U.S. Pat. No. 5,304,443 and references therein. Another non-impact printing system which has received attention for economical and convenient computer-to-plate preparation for lithographic printing is thermal transfer printing, for example, as described in U.S. Pat. No. 4,958,564.
In recent years, ink jet printers have replaced laser printers as the most popular hard copy output printers for computers. Some of the competitive advantages of ink jet printers are low cost and reliability. The ink jet printing system is a relatively rapid image output system and has a simple construction because it does not require any complex optical system. In recent times, there have been some reports in the literature proposing the use of ink jet printers to make lithographic printing plates.
In Japanese Kokai 62-25081, an oleophilic liquid or fluid ink was printed by ink jet printing onto a hydrophilic aluminum surface of a lithographic printing plate. Titanate or silane coupling agents were present in the ink.
An ink jet printing apparatus to make lithographic printing plates is described in PCT WO 94/11191. It is directed to depositing hydrophobic or hydrophilic substances on hydrophobic printing plates.
In U.S. Pat. No. 5,501,150, a fluid ink and hydrophilic media set containing materials to produce a silver-reducible image by ink jet printing are used to make a metallic silver image which, following wet processing to make the silver image sufficiently hydrophobic, is said to provide a lithographic printing plate.
Ink jet printing wherein the ink is a solid or phase change type ink instead of a liquid or fluid type ink is described in U.S. Pat. No. 4,833,486 to deposit a hot wax on a surface of an offset plate. Upon cooling of the wax, it solidifies, thereby providing a printing plate. Solid ink jet printing has serious disadvantages for lithographic plates in that the wax or resin image has limited durability due to its thermoplastic, chemical, and adhesive properties and the amount and rounded shape of the solidified ink jet droplet on the media do not have the intrinsic image resolution properties found in liquid ink jet printing.
There is also prior art in the use of ink jet printing to apply an opaque image or mask pattern to a photosensitive lithographic printing plate blank, as for example, in Japanese.Kokai 63-109,052. The blank is then exposed through the ink jet imaged mask pattern and then processed by conventional means to provide a lithographic printing plate. This approach retains the materials and processing of conventional lithographic printing plates and only uses ink jet printing as an alternative for the photomask through which the conventional plates are exposed. Thus this approach adds to the complexity and expense of the platemaking process and does not depend on the ink jet ink image for the hydrophobic image of the plate. U.S. Pat. No. 5,495,803 describes a solid or phase change type of ink jet printing to form a photomask for a printing plate.
As a further example of the methods for preparing printing plates by using the ink jet printing system, Japanese Kokai Publication 113456/1981 proposes methods for preparing printing plates whereby ink-repelling materials (e.g. curable silicones) are printed on a printing plate by ink jet printing. The printing plate obtained by this method is an intaglio printing plate in which the ink-repelling material formed on the surface of the substrate serves as a non-image part. As a result, the resolution of the printed images at shadow area or reversed lines is not so good. Moreover, a large amount of ink is needed in this method because the ink-repelling material must be deposited on the whole non-image part which occupies most of the surface of the printing plate, thereby delaying the printing process.
U.S. Pat. No. 5,511,477 discloses a method for the production of photopolymeric relief-type printing plates comprising: forming a positive or a negative image on a substrate by ink jet printing with a photopolymeric ink composition, optionally preheated to a temperature of about 30xc2x0-260xc2x0 C., and subjecting the resulting printed substrate to UV radiation, thereby curing said ink composition forming said image. This is an obnoxious method due to the sometimes high vapour pressure and toxicity of said inks.
U.S. Pat. No. 5,312,654 discloses a method for making lithographic printing plates comprising: forming an image on a substrate having an ink absorbing layer and a hydrophilized layer between the substrate and the absorbing layer by ink jet printing using a photopolymerizable ink composition, and exposing it to an actinic light in the wavelength region with which said ink composition is sensitized to cure the image. The printing endurance of said printing plates is low.
Japanese Kokai Publication 69244/1992 discloses a method for making printing plates comprising the steps of forming a printed image on a recording material subjected to a hydrophilic treatment by ink jet printing using a hydrophobic ink containing photocurable components, and exposing the whole surface to actinic light. However, the surface of the substrate to be used for the lithographic plate is usually subjected to various treatments such as a mechanical graining, an anodizing or a hydrophilic treatment to obtain good hydrophilic property and water retention property. Therefore, even the use of an ink composition having a very high surface tension results in a poor image on the surface of the substrate because of ink spreading and low printing endurance.
EP-A-533 168 discloses a method for avoiding said ink spreading by coating the lithographic base with an ink absorbing layer which is removed after ink printing. This is an uneconomical and cumbersome method.
Research Disclosure 289118 of May 1988 discloses a method for making printing plates with the use of an ink jet wherein the ink is is a hydrophobic polymer latex. However said printing plates have a bad ink acceptance and a low printing endurance.
EP-A-003 789 discloses a process for the preparation of offset printing plates by means of an ink jet method with oleophilic inks. There is not indicated how said inks are made but from the examples it is clear that it concerns artificial latices, which are difficult to prepare.
JN-57/038142 discloses a method of preparing a printing plate by forming an ink image on a blank printing plate, and also by fixing this image thermally by making toner to adhere to this image-formed area. The composition of the ink is not mentioned, only the composition of the toners is disclosed.
JN-07/108667 discloses a plate-making method forming an ink image containing a hydrophilic substance on a conductive support whose surface layer is made hydrophilic according to an electrostatic attraction type ink set system to dry or cure the same, by applying bias voltage to the conductive support at the time of ink jet writing. This is a cumbersome process.
U.S. Pat. No. 5,213,041 discloses a method for preparing a reusable printing plate for printing, projecting an imaging deposit on the plate surface by jet printing using an ejectable substance containing a heat fusible component. The image forms an imaging deposit which is fused to the surface of the printing plate using a variable frequency and variable power induction heater.
According to WO 97/43122 a lithographic printing plate is manufactured by means of an ink jet fluid comprising reactive components selected from the group consisting of transition metal complexes and organic carbonyl compounds. In a preferred embodiment the reactive compound comprises one or more chromium complexes of an organic acid.
In WO 00/46034 a printable media is disclosed, including a substrate having a hydrophilic, porous layer on at least one surface, and an ink receptive, thermoplasic image layer adhered to the hydrophilic, porous layer, wherein the ink receptive layer contains a polymer having a low surface energy and a plurality of tertiary amine sites being at least partially neutralized with an acid. Further a method is disclosed wherein the polymer having tertiary amine sites is applied in a fluid by means of ink jet printing onto the hydrophilic porous layer. A similar fluid is disclosed in WO 00/46038.
In WO 97/39894 a heat-sensitive composition is disclosed and a method of making a lithographic printing form with it. On a lithographic base there is coated a complex of preferably a phenolic resin and a compound which forms a thermally frangible complex with the phenolic resin. This complex is less soluble in the developer solution than the uncomplexed phenolic resin. Further a laser absorbing material can be present. When the complex is image-wise heated, e.g. by high-power IR-irradiation, the complex breaks down so allowing the non-complexed phenolic resin to be dissolved in the developing solution. A positive working printing form is obtained. This teaching is further elaborated in WO 98/42507 wherein specific dissolution inhibitors are disclosed.
In EP 864420 there is provided a heat-sensitive imaging element for making positive working lithographic printing plates comprising on a lithographic base a layer comprising a polymer, soluble in an aqueous alkaline solution and an IR-sensitive top layer. Upon image-wise exposure the capacity of the aqueous alkaline solution to penetrate or solubilize the top layer is changed.
The lithographic printing plate precursors based on heat mode according to the above cited references show the drawback that they require a complicated and expensive platesetter apparatus equipped with an an expensive and short-living high power IR exposure unit. Furtheron their working mode is limited to positive working.
The presents invention provides an alternative to the teachings on heat-sensitive lithographic printing plate precursors.
It is an object of the present invention to provide a method for the preparation of a lithographic printing plate that is negative working.
It is a further object of the present invention to provide a is method for the preparation of a lithographic printing plate which is uncomplicated and requires only a relatively cheap ink jet printer.
It is still a further object of the present invention to provide a method for the preparation of a lithographic printing plate whereby the whole process can be performed in a daylight environment.
It is still a further object of the present invention to provide a method for the preparation of a lithographic printing plate which has the same plate and lithographic characteristics as a conventional printing plate.
The above mentioned objects are realised by providing a method for the preparation of a negative working lithographic printing plate, said method comprising the following steps, in order,
(1) providing a lithographic printing plate precursor comprising a lithographic support and an image forming layer containing a polymeric binder soluble in an aqueous alkaline developer,
(2) dispensing image-wise by means of ink jet printing droplets of a fluid onto the surface of said lithographic printing plate precursor, characterized in that said fluid comprises in a solvent carrier a dissolution inhibitor compound capable of reducing the solubility in said aqueous alkaline developer of said polymeric binder,
(3) drying the imaged lithographic printing plate precursor to at least partially remove the solvent carrier of the fluid,
(4) treating the dried imaged lithographic printing plate precursor with an aqueous alkaline developer thereby removing the non-imaged areas.
The final result is a negative working printing plate with the plate characteristics of a conventional plate. Preferentially the imaging layer does not contain photochemical compounds, which might influence the aqueous alkaline developer solubility of the binder upon UV-exposure. In that case the whole process can be carried in a daylight environment, without the need for safelight conditions.
The essential elements of the present invention being the composition of the ink jet fluid and of the printing plate precursor will now be explained in detail.
Composition of the Ink Jet Fluid
The novel ink jet fluid used in accordance with the present invention comprises a liquid carrier and at least one compound capable or reducing the solubility of the polymeric binder of the image forming layer in an aqueous alkaline developer. This compound will furtheron also be called xe2x80x98dissolution inhibitor compoundxe2x80x99. Such xe2x80x98dissolution inhibitor compoundsxe2x80x99 are known from e.g. WO 98/42507. These compounds have polar functionality that serve as acceptor sites for hydrogen bonding with hydroxyl groups on aromatic rings. The acceptor sites are atoms with high electron density, preferably selected from electronegative first row elements. Useful polar groups include keto groups (including vinylogous esters). Other groups may also be useful, such as sulfones, sulfoxides, thiones, phosphine oxides, nitrites, imides, amides, thiols, ethers, alcohols, ureas as well as nitroso, azo, azoxy, nitro and halo groups. In general, it is desired that such compounds have an xe2x80x9cinhibition factorxe2x80x9d of at least about 0.5, and preferably at least about 5 and more preferably, at least about 15. The higher this value is, the more useful is the compound in this invention.
Inhibition factors for given compounds can be readily measured using the procedure described by Shih et al, Macromolecules, Vol. 27, p. 3330 (1994). The inhibition factor is the slope of the line obtained by plotting the log of the development rate as a function of inhibitor concentration in the coated layer. Development rates are conveniently measured by laser interferometry, as described by Meyerhofer in IEEE Trans. Electron Devices, ED-27,921 (1980).
Representative compounds having the desired properties reported dissolution (inhibition factors listed in parentheses) include aromatic ketones including, but not limited to, xanthones (2.26), flavanones (6.80), flavones (18.3), 2,3-diphenyl-1-indenones (23.6), pyrones (including thiopyrones), and 1xe2x80x2-(2xe2x80x2-acetonaphthonyl)benzoate, and include such compounds as xcex1- and xcex2-naphthoflavone (49.1 and 46.6, respectively), 2,6-diphenyl-4H-pyran-4-one, 2,6-diphenylpyrone, 2,6-diphenylthiopyrone, 2,6-di-t-butylthiopyrone and 2,6-diphenyl-4H-thiopyran-4-one. The flavones and pyrones are preferred, including but not limited to, xcex1-naphthoflavone, 2,6-diphenyl-4H-pyran-4-one and 2,6-diphenyl-4H-thiopyran-4-one.
Other classes of dissolution inhibitor compounds are disclosed in WO/39894, also called xe2x80x9creversible insolubiliser compoundsxe2x80x9d, in this reference.
A useful class of reversible insolubiliser compounds are nitrogen-containing compounds wherein a least one nitrogen atom is either quaternized, incorporated in a heterocyclic ring or quaternized and incorporated in a heterocyclic ring. Examples of useful quaternized nitrogen containing compounds are triaryl methane dyes such as Crystal Violet (CI basic violet 3) and Ethyl Violet, Flexo Blue 630 (a commercially available triarylmethane dye from BASF AG) and tetraalkyl ammonium compounds.
More preferably the reversible insolubiliser compound is a nitrogen-containing heterocyclic compound. Examples of suitable nitrogen-containing heterocyclic compounds are quinoline and triazoles, such as 1,2,4-triazole.
Most preferably the reversible insolubiliser compound is a quarternized heterocyclic compound. Examples of suitable quarternized heterocyclic compounds are imidazolinium compounds, such as MONAZOLINE C, MONAZOLINE 0, MONAZOLINE CY and MONAZOLINE T, all trade names of Mona Industries, quinolinium compounds, such 1-ethyl-2-methyl quinolinium iodide and 1-ethyl-4-methyl quinolinium iodide, and benzothiazolium compounds, such as 3-ethyl-2-methyl benzothiazolium iodide, and pyridinium compounds, such as cetyl pyridinium bromide, ethyl viologen dibromide and fluoropyridinium tetrafluoroborate.
Usefully the quinolinium or benzothiazolium compounds are cationic cyanine dyes, such as Dye A (see formula below), Quinoldine Blue and 3-ethyl-2-[3-(3-ethyl-2(3H)-benzothiazolylidene)-2-methyl-1-propenyl]benzothiazolium iodide.
Dye A
A further useful class of reversible insolubiliser compounds are carbonyl functional group containing compounds. Examples of suitable carbonyl containing compounds are a-naphthoflavone, -naphthoflavone, 2,3-diphenyl-1-indeneone, flavone, flavanone, xanthone, benzophenone, N-(4-bromobutyl)phthalimide and phenanthrenequinone.
The reversible insolubilising compound may be a compound of general formula Q1S(0)nQ2, wherein Q1 represents an optionally substituted phenyl or alkyl group, n represents 0, 1 or 2, and Q2 represents a halogen atom or an alkoxy group. Preferably Q1 represents a C1-4 alkyl phenyl group, for example a tolyl group, or a C1-4 alkyl group. Preferably n represents 1 or, especially, 2. Preferably Q2 represents a chlorine atom or a C1-4 alkoxy group, especially an ethoxy group.
Another useful reversible insolubiliser compound is acridine orange base (CI Solvent Orange 15).
Other useful reversible insolubiliser compounds are ferrocenium compounds, such as ferrocenium hexafluorophosphate.
The xe2x80x9cdissolution inhibitor compoundxe2x80x9d may be present in the ink in an amount from 0.01 to 10, preferably from 0.01 to 8% by weight.
It is necessary that the xe2x80x9cdissolution inhibitor compoundxe2x80x9d be in the form of a homogeneous solution or a stable colloidal dispersion, so that it can pass through the jets of the printer head.
The liquid carrier is water or organic solvents or combinations thereof. Choice of the specific liquid carrier depends on the specific ink jet printer and its compatible with the ink jet printing head and cartridge being used for the ink jet printing. Both aqueous based and solvent based inks can be used in the present invention depending on the ink-jet technology that is being used: piezo, thermal, bubble jet or continuous ink jet.
The liquid carrier can be a solvent for the imaging layer or it can be a mixture of a solvent and a non-solvent. In order to get a good interaction between the insolubilizer and the polymer, soluble in the aqueous alkaline developer, the liquid carrier should at least partially contain a solvent capable of dissolving or swelling the imaging layer.
While water is the preferred medium for aqueous inks, the aqueous composition may comprise one or more water miscible solvents e.g. a polyhydric alcohol such as ethylene glycol, diethylene glycol, triethylene glycol or trimethylol propane. Such polyhydric alcohols function as so-called humectants preventing the ink from drying out in the orifices of the print head. The amount of aqueous carrier medium in the aqueous composition may be in the range from 30 to 99.995, preferably from 50 to 95% by weight. Also organic solvents may be used as a carrier medium for the ink e.g. alcohols, ketones or acetates.
As known for the ink jet technology, the jet velocity, separation length of the droplets, drop size and stream stability is greatly affected by the surface tension and the viscosity of the aqueous composition. Ink-jet inks suitable for use with ink-jet printing systems may have a surface tension in the range from 20 to 60, preferably from 30 to 50 dynes/cm. Control of surface tensions in aqueous inks may be accomplished by additions of small amounts of surfactants. The level of surfactants to be used can be determined through simple trial and error experiments. Several anionic and nonionic surfactants are known in the ink-jet art. Commercial surfactants include the SYRFINOL TM series, trade name from Air Products; the ZONYL TM series, trade name from DuPont; the FLUORAD TM series, trade name from 3M, and the AEROSOL TM series, trade name from Cyanamid.
Furthermore the ink may comprise one or more compounds which are able to increase the resistance towards the solubilizing effect of the aqueous alkaline developer. Such compounds may be selected from following classes:
(a) compounds which include a polyalkyleneoxide unit;
(b) siloxanes, and
(c) esters, ethers, and amides of polyhydric alcohols.
More details can be found in WO 99/21725.
The viscosity of the ink is preferably not greater than 20 mPa.s, e.g. from 1 to 10, preferably from 1 to 5 mPa.s at room temperature.
The ink may further comprise other ingredients. A biocide may be added to prevent unwanted microbial growth which may occur in the ink over time. Additional additives that may be optionally present in the ink include thickeners, pH adjusters, buffers, conductivity enhancing agents, drying agents, and defoamers.
In order to enhance the image contrast after jetting the image on a lithographic receiver, dyes can be added. Many dyes and pigments are known to be suited for the ink jet technology. Suitable dyes are further selected based on their compatibility in the carrier medium (i.e. aqueous based or solvent based) and on the compatibility with the oleophilizing agent i.e. they should not lead to coagulation. Especially favoured for aqueous inks are anionic dyes such as acid black.
Composition of the Lithographic Printing Plate Precursor
(a) The Lithographic Receiver
The support may be any support suitable for printing plates. Typical supports include metallic and polymeric sheets or foils. Preferably, a support having a metallic surface is used. Preferably, the metallic surface is oxidised. In a particularly preferred embodiment of the invention, a support having an anodised aluminium surface is employed. The support for the lithographic printing plate is typically formed of aluminium which has been grained, for example by electrochemical graining, and then anodised, for example, by means of anodising techniques employing sulphuric acid and/or phosphoric acid. Methods of both graining and anodising are very well known in the art and need not be further described herein. After writing the image the printing plate can be inked with printing ink in the normal way, and the plate can be used on a printing press. Before inking the plate can be treated with an aqueous solution of natural gum, such as gum acacia, or of a synthetic gum such as carboxymethyl cellulose, as it is well known in the art of printing.
According to another mode in connection with the present invention the lithographic base with a hydrophilic surface comprises a flexible support, such as e.g. paper or plastic film, provided with a cross-linked hydrophilic layer. A particularly suitable cross-linked hydrophilic layer may be obtained from a hydrophilic binder cross-linked with a cross-linking agent such as formaldehyde, glyoxal, polyisocyanate, melamine type cross-linkers, ammonium zirconyl carbonate, titanate crosslinkers, or a hydrolysed tetraalkylorthosilicate. The latter is particularly preferred. As hydrophilic binder there may be used hydrophilic (co)polymers such as, for example, homopolymers and copolymers of vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylate acid, methacrylate acid, hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride/vinylmethylether copolymers. The hydrophilicity of the (co)polymer or (co)polymer mixture used is preferably the same as or higher than the hydrophilicity of polyvinyl acetate hydrolyzed to at least an extent of 60percent by weight, preferably 80 percent by weight.
The cross-linked hydrophilic layer in a lithographic base used in accordance with the present embodiment preferably also contains substances that increase the mechanical strength and the porosity of the layer e.g. metal oxide particles which are particles of titanium dioxide or other metal oxides. It is believed that incorporation of these particles gives the surface of the cross-linked hydrophilic layer a uniform rough texture consisting of microscopic hills and valleys which serve as storage places for water in background areas. Preferably these particles are oxides or hydroxydes of beryllium, magnesium, aluminium, silicon, gadolinium, germanium, arsenic, indium, tin, antimony, tellurium, lead, bismuth, titanium or a transition metal. Particularly suitable inorganic particles are oxides or hydroxides of aluminum, silicon, zirconium or titanium, used in at most 75% by weight of the hydrophilic layer. The inorganic pigments may have a particle size ranging from 0.005xcexc to 10 xcexcm.
Particular examples of suitable cross-linked hydrophilic layers for use in accordance with the present invention are disclosed in EP-A-601 240, GB-P-1 419 512, FR-P-2 300 354, U.S. Pat. Nos. 3,971,660, U.S. Pat. No. 4,284,705 and EP-A-514 490.
As flexible support of a lithographic base in connection with the present embodiment it is particularly preferred to use a plastic film e.g. substrated polyethylene terephthalate film, substrated polyethylene naphthalate film, cellulose acetate film, polystyrene film, polycarbonate film etc. The plastic film support may be opaque or transparent.
(b) The Image Forming Layer
The image forming layer is applied by coating an image forming composition which will now be explained in more detail.
The polymer binders present in the image forming composition used in accordance with the present invention are water-insoluble but alkali-soluble polymers. Preferred are polymers comprising a functional group chosen from hydroxy, carboxylic acid, amino, amido, and maleiimide. Suitable classes of compounds include copolymers of (meth)acrylic acid with alkyl(meth)acrylates, (meth)acrylic acid nitrile and the like, copolymers of cronic acid with alkyl(meth)acrylates, (meth)acrylic acid nitrile and the like, copolymers of vinyl acetic acid with alkyl(meth)acrylates, copolymers of maleic acid anhydride with optionally substituted styrenes, esters of the copolymers of maleic acid anhydride, esters of hydroxyl group containing polymers with anhydrides of di- or polycarboxylic acids, copolymers of hydroxyalkyl(meth)acrylate with alkyl(meth)acrylates, (meth)acrylic acid nitrile and the like, copolymers of allyl alcohol with optionally substituted styrenes, copolymers of vinyl alcohol with alkyl(meth)acrylates or other polymerizable unsaturated compounds, polyurethanes, in so far as they have a sufficient number of free hydroxylic groups, epoxy resins, polyester, partially hydrolized vinyl acetate copolymers, polyvinyl acetals with free hydroxyl groups.
Other preferred compounds include copolymers of 4-hydroxystyrene with 3-methyl-4-hydroxystyrene or 4-methoxystyrene, copolymers of (meth)acrylic acid with styrene, copolymers of maleiimide e.g. with styrene, hydroxy or carboxy functionalized celluloses.
Especially suitable compounds however are phenolic resins including novolac resins, resole resins and polyvinyl compounds having phenolic hydroxy groups.
Novolac resins are the most preferred type. They are generally polymers that are produced by the condensation reaction of phenols and an aldehyde, such as formaldehyde, or aldehyde-releasing compound capable of undergoing phenol-aldehyde condensation, in the presence of an acid catalyst. Typical novolac resins include, but are not limited to, phenol-formaldehyde resin, cresol-formaldehyde resin, phenol-cresol-formaldehyde resin, p-t-butylphenol-formaldehyde resin, and pyrogallol-acetone resins. Such compounds are well known and described for example in U.S. Pat. Nos. 4,308,368, 4,845,008, 5,437,952 and U.S. Pat. Nos. 5,491,046, 5,143,816 and GB 1,546,633. A particularly useful novolac resin is prepared by reacting m-cresol or phenol with formaldehyde using conventional conditions.
Phenolic resins that are known as xe2x80x9cresole resinsxe2x80x9d, including, for example, condensation products of bis-phenol A and formaldehyde, are also useful in this invention.
Still another useful phenolic binder resin is a polyvinyl compound having phenolic hydroxyl groups. Such compounds include, but are not limited to, polyhydroxystyrenes and copolymers containing recurring units of a hydroxystyrene, and polymers and copolymers containing recurring units of halogenated hydroxystyrenes. Such polymers are described for example in U.S. Pat. No. 4,845,008 (noted above).
Other useful novolacs are described in U.S. Pat. Nos. 4,306,010 and 4,306,011. Still other useful phenolic resins are described in U.S. Pat. No. 5,368,977.
A mixture of the resins described above can be used, but preferably, a single resin, e.g. a novolac is present as the binder resin in the imaging composition of this invention.
Apart from the polymeric binder soluble in an aqueous alkali developer the image forming composition may contain various additives as occasion demands. For example, cyclic acid anhydrides, phenols, organic acids, and a sulfonyl compound can be used in order to improve the aqueous alkaline developability.
Examples of the cyclic acid anhydride include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endoxy-xcex944-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, xcex1-phenylmaleic anhydride, succinic anhydride, and pyromellitic anhydride, as described in U.S. Pat. No. 4,115,128.
Examples of the phenols include bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4xe2x80x2-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4xe2x80x2,4xe2x80x3-trihydroxytriphenylmethane, and 4,4xe2x80x2,3xe2x80x3,4xe2x80x3-tetrahydroxy-3,5,3xe2x80x2,5xe2x80x2-tetramethyltriphenylmethane, and the like.
Examples of the organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphates, and carboxylic acids, as described in, for example, JP-A Nos. 60-88,942 and 2-96,755. Concrete examples of these organic acids include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfin acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4,-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, bishydroxyphenylsulfone, methylphenylsulfone, diphenyldisulfone, and the like.
The amount of the cyclic acid anhydride, phenol, or organic acid contained in the image forming composition is preferably in the range of 0.05 to 20% by weight.
Furthermore the image forming composition may additionally comprise nonionic and/or amphoteric surfactants. Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether, and the like. Specific examples of the amphoteric surfactant include alkyldi(aminoethyl)glycine, hydrochloric acid salt of alkylpolyaminoethylglycine, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, N-tetradecyl-N,N-betaine, for example, AMOGEN K, trade name of Dai-ichi Kogyo Seiyaku Co., and the like.
Dyes can be added in a small amount to adjust the plate color. Specific examples of these dyes include Oil Yellow No. 101, Oil Yellow No. 103, Oil Pink No. 312, Oil Green BG, Oil Blue BOS, Oil Blue No. 603, Oil Black BY, Oil Black BS, Oil Black T-505 (all trade names of Chemical Industries, Co.,), Victoria Pure Blue, Crystal Violet (C.I. 42555), Methyl Violet (C.I. 42535), Ethyl Violet, Rhodamine B (C.I. 145170B), Malachite Green (C.I. 42000), Methylene Blue (C.I. 52015), and the like.
Further, if necessary, a plasticizer may be added to the negative-type image forming composition of the present invention in order to impart flexibility to the coated layer. Examples of the plasticizer include butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl~phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, an oligomer or a polymer of acrylic acid or methacrylic acid, and the like.
Further, if necessary, a compound which is decomposed by light, such as quinonediazides or diazo compounds, may be added to the image forming composition. The amount of the compound added to the composition is preferably in the range of 1 to 10% by weight based on the total weight of the solids of the composition.
In order to control the dot formation on the imaging layer an additional top receiving layer may be applied. This layer should not disturb the processing characteristics. Therefore the thickness of the layer should be less than 1 xcexcm, preferably less than 0.5 xcexcm. Any polymer capable of reducing the dot size of a water based ink jet ink can be used. Especially favoured are water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, dextranes, etc. Such polymers may also anionically or cationically modified. Both modifications are preferred over the non-modified compounds.
The Ink Jet Printing Process, and the Development
The image-wise ink jet printing step (2) of the present invention can be performed by any of the known ink jet techniques, as briefly explained hereinafter.
In ink jet printing tiny drops of ink fluid are projected directly onto an ink receptor surface without physical contact between the printing device and the receptor. The printing device stores the printing data electronically and controls a mechanism for ejecting the drops image-wise. Printing is accomplished by moving the print head across the paper or vice versa. Early patents on ink jet printers include U.S. 3,739,393, 3,805,273 and 3,891,121.
The jetting of the ink droplets can be performed in several different ways. In a first type of process a continuous droplet stream is created by applying a pressure wave pattern. This process is known as continuous ink jet printing. In a first embodiment the droplet stream is divided into droplets that are electrostatically charged, deflected and recollected, and into droplets that remain uncharged, continue their way undeflected, and form the image. Alternatively, the charged deflected stream forms the image and the uncharged undeflected jet is recollected. In this variant of continuous ink jet printing several jets are deflected to a different degree and thus record the image (multideflection system).
According to a second process the ink droplets can be created xe2x80x9con demandxe2x80x9d (xe2x80x9cDODxe2x80x9d or xe2x80x9cdrop on demandxe2x80x9d method) whereby the printing device ejects the droplets only when they are used in imaging on a receiver thereby avoiding the complexity of drop charging, deflection hardware, and ink recollection. In drop-on-demand the ink droplet can be formed by means of a pressure wave created by a mechanical motion of a piezoelectric transducer (so-called xe2x80x9cpiezo methodxe2x80x9d), or by means of discrete thermal pushes (so-called xe2x80x9cbubble jetxe2x80x9d method, or xe2x80x9cthermal jetxe2x80x9d method).
In the present invention the printing plate precursor is image-wise ink jet printed (step 2) with the particular fluid described.
It is a particular advantage of the present invention that only a relatively inexpensive ink jet apparatus is required instead of an expensive platesetter device for the heat-sensitive printing plate precursors.
After image-wise printing the printing plate precursor is dried (step 3) to at least partially remove the solvent carrier of the fluid. Then the printing plate precursor is treated with an aqueous alkaline developer (step 4). By aqueous alkaline developers is meant positive- and negative developers for conventional plates as known to the expert in the field. The pH may range from neutral (pH=7) to strong alkaline (pH=14). An example of a negative developer is OZASOL EN 223 (trade name of Agfa-Gevaert N.V.); examples of positive developers are OZASOL EP26, OZASOL EP 262A, OZASOL EP 240, and GB50 (all trade names of Agfa-Gevaert N.V.).
Due to the solubility of the polymeric binder in the aqueous alkaline developer the non-imaged areas are completely removed and the hydrophilic lithographic support is revealed. On the other hand, due to the action of the dissolution inhibitor the imaged areas are not at all or only partially removed so that they can function as ink-accepting areas in a printing process. After optional rinsing and gumming, the final result is a negative working printing plate with the plate characteristics of a conventional plate. Since the image forming layer does not contain photochemical compounds which might influence the aqueous alkaline developer stability of the binder upon UV-exposure the whole process can be performed in a daylight environment.
The present invention will now be illustrated by the following examples without however being limited thereto.

Method for the preparation of a negative working printing plate


A method and apparatus for configuration management for a computing device. The apparatus comprises an interface for providing available software to the computing device to be loaded onto the computing device. A processor executes a set of computer instructions to determine whether or not software resident in the computing device is authenticated or not. If the resident software is not authenticated, the processor loads the available software onto the computing device. If the resident software is authenticated, the processor loads the available software only if the available software is also authenticated.

I. Field of the Invention
The method and apparatus for configuration management relates generally to the field of software management and more particularly to a method and apparatus for providing configuration management of software used for a general computing device.
II. Description of the Related Art
In modern computing systems, it is often important to effectively manage a software configuration that is embodied within a computing system. Such computing systems include not only traditional computers found in businesses and homes, but also a wide variety of electronics, including wireless telephones, laptop computers, personal digital assistants (PDAs), automotive electronics, and so on. Such computing systems sometimes employ methods to ensure software compatibility by checking a current software version with that of a newer version of software to be loaded. However, these methods do not attempt to prevent an upgrade of existing software, or the introduction of new software, under certain conditions.
One example of a need to manage and control the type or version of software to be loaded onto a computing device can be found in security applications for such computing devices. For example, in a governmental organization where each person is given a wireless communication device, the organization might be segregated into different security levels. If a person having a lower security level were to acquire a wireless communication device belonging to a person having a higher security level, that person might try to load software onto the wireless communication device so that he might be able to access information that would be otherwise unavailable to him. In another aspect of this example, it would be desirable to only load authenticated software into the wireless communication device once the wireless communication device has been given to a person having a high security level. Authenticated software refers to software that has been distributed by a "trusted" source, and that it has not been altered.
Thus, there is a need for a method and apparatus to perform configuration management and control for software used in a computing device.

Method and apparatus for configuration management for a computing device