JPS5936731B2 - printing materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to materials having a photosensitive single layer film structure suitable as water-processable printing plates and other printing materials.

Many different photosensitive systems are known in the art for the manufacture and preparation of lithographic plates.

Of course, diazo compounds are frequently used as photosensitive components in such systems. The diazo compounds can be prepared with several desirable properties for use in this field, including low cost, long shelf life, solubility in water, and good photosensitivity. However, the ink receptivity of diazo compounds is greatly reduced upon contact with water, and the inherent durability of diazo resins is relatively low. Therefore, countermeasures for manufacturing and preparing printing plates using diazo compounds include using a lacquer developer or overcoating the diazo compound with a lacquer or other material that is UV transparent to overcome this problem. Ta. Although these methods have been successful in some respects, they impair the ease of water treatment of the diazo compound plates, and in some cases require longer exposure times. Additionally, diazo compounds lack sufficient bonding strength to smooth substrates, making it necessary to provide grained substrate surfaces to enhance the mechanical bonding of these photosensitive coatings in order to extend press run times to useful lengths. It was hot.
Another popular photosensitive system uses photosensitive resins that provide both high ink receptivity and durability.

However, these systems generally require special solvents for plate development, which adds to the complexity of the system compared to simple water treatment and poses ecologically undesirable waste problems. In an effort to overcome these problems and improve the performance characteristics of prior art photosensitive compositions used in the manufacture of printing plates and other printing materials, novel materials with unique but highly desirable properties have been developed. A photosensitive film structure was discovered.

The present invention is generally directed to a substrate having a single layer film structure consisting of a continuous phase and a discontinuous phase uniformly distributed throughout the structure.

This continuous phase is a photosensitive material that undergoes a change in solubility in the chosen solvent when exposed to light. The discontinuous phase consists of substances that are not photosensitive and are insoluble in the solvent.
It has been found that such photosensitive compositions can be rendered selectively transparent by imagewise exposure to light.

The film compositions of the present invention can then be used in a variety of applications where selective permeability to fluids is required or desired. It is therefore an object of the present invention to provide a photosensitive structure which is rendered selectively permeable to fluids when exposed to light.

It is another aspect of the present invention to provide a photosensitive structure in which the active photosensitive material occupies a relatively small proportion of the mass and volume of the structure, thereby providing considerable performance latitude and cost reduction. This is the purpose of

It is also an object of the present invention to provide photosensitive film structures that can be developed in water after imagewise exposure to light without the use of organic or inorganic solvents. It is a further object of the present invention to provide a photosensitive single layer film composition suitable for use in the manufacture of lithographic or offset printing plates. It is another object of the present invention to provide a lithographic printing plate in which the ink receptivity and durability of the imaged areas are relatively independent of exposure and development substances.

It is also an object of the present invention to provide unique photoresist materials. Furthermore, it is another object of the present invention to provide photosensitive film compositions having high bond strength to various surfaces.

The novel features considered characteristic of the invention are disclosed in the appended claims.

However, the invention itself, as well as its objectives and attendant advantages, will be best understood by reference to the following description taken in conjunction with the accompanying drawings.

However, the schematic representations in the drawings are merely for illustrating the structure and mechanism of the present invention and are not intended to limit the scope of the present invention. The photosensitive single layer film compositions of this invention consist of a continuous phase and a discontinuous phase uniformly dispersed throughout the composition.

The continuous phase is photosensitive and can vary in solubility in a given solvent.

The discrete phase is chosen to be non-photosensitive and relatively insoluble in the solvent relative to the continuous phase. However, the second aspect of the present invention
The concept of two phases 1 is related to the solvent used, i.e. the solvent acts selectively on the 6 continuous phases 1 of exposed or unexposed photosensitizers, while on the matrix of 6 discontinuous phases 1. must be relatively inert. The photosensitive single layer film compositions of this invention can best be described as gratings cast from emulsion-dispersions. Several microstructural figures or lattices formed from these emulsion monodispersions have been identified, each offering different performance characteristics. One microstructural feature embodying the concepts of the invention is schematically illustrated in FIG.

The grid is shown as being cast from a dispersion of substantially one-dimensional coated spheres and typically utilized as a coating on a suitable substrate. Thus, in this system, the photosensitive continuous phase is designed as a coating on the discontinuous phase matrix material. The continuous phase coating material selected to wet and coat the particles of the discrete phase is soluble in the selected solvent, while the discrete phase is insoluble in this solvent.

However, after exposure to chemical activation, the continuous phase also becomes insoluble. Thus, when a selected solvent is applied to the photosensitive structure after it has undergone image-wise exposure, the unexposed areas of the grating remain soluble in the solvent as the continuous phase coating in these areas remains soluble. It is then moistened and permeated. Importantly, the permeability of the grid allows materials, both continuous and discontinuous, to be physically removed from the substrate, such as by scraping or brushing. It is believed that the water wettability and diffusion properties of the substrate and the capillary pressure at the grid-substrate interface aid in this "development" process, thus providing additional control to the system.

Another example of a microstructural feature embodying the concepts of the invention is schematically illustrated in FIG.

In this lattice system, the interstices or void spaces of the spherical matrix material in the discontinuous phase are filled with the photosensitive material in the continuous phase. When the spheres are closely packed as shown in FIG. 2, the void volume is approximately 25% if the spheres are of substantially uniform size. This theoretical void space occurs regardless of the actual size of the sphere as long as uniform dimensions are maintained. According to this lattice structure, the void spaces of the matrix are filled with various photosensitive materials such as silver halide/gelatin, dichromate colloids, photosensitive resins, diazo-colloid systems, etc. Using this lattice system, image-wise exposure provides the exposed areas with an effective binding medium for the discontinuous phase matrix material, while the unexposed areas remain aqueous. Development is possible after the desired transparency has been achieved.

Other structural designs useful in practicing the invention have also been identified.

This lattice system, illustrated in FIG. 3, includes a continuous phase photosensitive material dispersed within a lattice of multidimensional spheres of discrete phase material as disclosed for the previously described systems. . As mentioned above, a matrix of one-dimensional spheres has approximately 25% void space.

The use of multidimensional spheres reduces this void space, thus allowing less continuous phase material to be used in the fabrication of the photosensitive structure. This, of course, would be highly desirable from a cost reduction perspective and also because the physical and chemical properties of the discontinuous phase can dominate the characteristics of the entire photosensitive structure. Photosensitive materials useful in the practice of this invention include any photosensitive compound that undergoes a change in solubility characteristics in a selected solvent upon exposure to electromagnetic radiation. The photosensitive compound is also selected to be chemically miscible with the matrix emulsion so that mixing with the matrix emulsion results in a macroscopically two-phase lattice system. Photosensitive compounds that can be used in the present invention include aromatic diazo compounds, photosensitive dyes, azo compounds, dichromates,
Contains photosensitive resins and silver halide-gelatin systems. Further useful continuous phase materials are disclosed in U.S. Pat. Nos. 2,063,631 and 2,679,478, and by authors J. KOsar
and publisher John Wiley & Sons (196
5) Light Sensitive Systems. Particularly preferred continuous phase materials include carbonyl compounds such as formaldehyde or paraformaldehyde and diazo compounds such as 4-diazo-1,1'-
Condensation products with diphenylamine are included. Such condensation products are available from FairmOntChemicalCO.
, Newark, NewJersey with product name Dia
zONO. 4 and DiazONO. It is commercially available as 4L. The discrete phase of the photosensitive structures of the present invention is a matrix material dispersed within the continuous phase.

The matrix material is the predominant component of the structure and is selected to suit the physical properties of the final product for the intended use. Among others, these properties include durability or physical toughness, ability to adhere to substrates, water repellency (and therefore ink receptivity), permeability,
These include solvent resistance, particle size, viscosity, solids content, heat healing properties, film forming properties, and molecular weight. Homopolymers and copolymers in the form of emulsion monodispersions suitable for forming the matrix structures of the invention include, inter alia, acrylic resins, copolymers of acetate and ethylene, copolymers of styrene and acrylate, Includes polyvinyl acetate and copolymers of vinyl acetate and acrylic esters.

Each of these can be used with or without protective colloids, wetting agents, plasticizers and other modifiers. According to a preferred embodiment of the invention, the photosensitive film structure is formed by casting an emulsion containing water, a suitable diazo compound and a PVA-acrylate emulsion as a self-supporting film or onto a suitable substrate. It can be formed by

Upon drying, the resulting film consists of a matrix of polymers in which the diazo compound is bonded to the PVA-
The acrylate spheres are coated and/or their gaps are filled. This matrix phase is known to form a film that is insoluble in water, whereas diazo compounds become insoluble in water only when exposed to light. The most important application of the invention is in the field of lithographic offset printing.
Offset printing plates can be produced by molding or casting the composition of the present invention as a film on the surface of a hydrophilic substrate such as aluminum silicate. The copolymer matrix of vinyl acetate and long chain acrylates described above provides a flexible, highly water repellent, non-remulsifiable film. Surprisingly, the addition of the diazo resin within the interstices of this polymer matrix provides the ability for a thin layer of the composition to be washed away from the substrate after imagewise exposure to light. The areas of the film that were exposed to light are not removed from the substrate during the washing/scrubbing process, while the portions of the film that were not exposed to light are removed. Additionally, the light-exposed areas exhibit desirable ink-receptive properties and exhibit effective bonding even to non-porous surfaces such as silicate ungrained aluminum. Imagewise exposure to light provides selective and discontinuous transmission conditions for a given solvent.

For example, in the case of a diazo-PVA/acrylate matrix composition, when exposed to a light image, the diazo becomes insoluble in the portion of the film exposed to the light, thus making the entire film in those portions insoluble in water. Becomes transparent. On the other hand, the diazo in the portion of the film that has not been exposed to light is still soluble in water, allowing water to pass through the PVA/acrylate matrix. Water permeation creates high internal stresses that cause the film to sever and fail, or simply provides access to the substrate, promoting adhesive failure. in this way,
The photosensitive film compositions of the present invention discussed herein are rendered selectively permeable to water through imagewise exposure to light. When such photosensitive structures are used with hydrophilic substrates to produce lithographic printing plates, the portions of the composition not exposed to light are easily removed during the water development step.

As mentioned above, it appears that the water-insoluble matrix can be peeled off from the substrate in part due to the action of water at the matrix/substrate interface; This interface is reached through permeability. Because the PVA-acrylate copolymer matrix is hydrophobic (i.e., lipophilic), the photosensitive film compositions of this invention are ideally suited for use in lithographic offset printing processes. Furthermore, since these matrix materials are not photosensitive and therefore unaffected by exposure to light and even by the development process, these matrices affect the ink receptivity of the resulting plate; Can be selected to optimize durability and bonding properties. Moreover, if even greater durability is desired, simply heating the treated plate causes ball-to-ball coalescence and substantially increases durability. Furthermore, by proper selection of matrix material, thickness and substrate, it is possible to create both hydrophobic and hydrophilic properties in the film composition, relatively independent of the properties of the substrate.

In such cases, after image-wise exposure, the photosensitive phase of the film remains soluble in the unexposed areas such that a porous surface is created by leaching with the chosen solvent. It will be done. By developing the film without scrubbing, the discontinuous phase matrix material retains substantial structural continuity on the substrate. Thus, the non-exposed porous regions can then be mechanically wetted with water, while the exposed regions exhibit non-porous and hydrophobic properties. This wettability difference on the film surface proves suitable for lithographic printing, thus leaving the manufacturer free to select and use any low cost substrate material. The improved photosensitive single layer film structure of the present invention has been exemplified above in connection with the manufacture and preparation of lithographic offset printing plates.

However, it should be understood that the scope of the invention is not limited in these aspects. The photosensitive film structure of the present invention can also be used in other applications where selective permeability to certain fluids or solvents is desired. For example, the photosensitive structures of the present invention can be cast into self-supporting films and then exposed to a light image and developed without destroying the structural integrity of the matrix. In this way, a skeletal template is obtained that is selectively permeable to certain fluids. These templates can then be used for any of a wide variety of purposes, including the imprinting of designs, patterns, or images on the lower surface with ink or other similar materials that are transparent to the template. The photosensitive structures of the present invention also enable many photoresist applications.

Of course, the matrix material can be chosen and adapted to the appropriate environment. Thus, the selection of a particular emulsion/dispersion system will be directed to one skilled in the art due to its resistance to certain acids and bases and the required dielectric constant for plating resist applications. Once selected, compatible photosensitive phases can be added to achieve the desired performance. The ease of development for the photosensitive structures of the present invention is proportional to the concentration of the material in the continuous phase, with the higher the concentration of the continuous phase, the easier the development. On the other hand,
It is often preferable to minimize the concentration of the continuous phase, since the discontinuous phase matrix material provides improved durability, bonding, and printing properties, which are important parts of the present invention.
Accordingly, the relative amounts of continuous phase materials and discontinuous phase materials used will depend on the properties desired in a given photosensitive structure. However, illustratively, the amount of diazo material in the continuous phase utilized in Example 3, detailed below, may range from 0.03 to 1 without appreciably affecting the final product.
0 weight can be a problem. The thickness of the photosensitive film composition also affects the development of the photosensitive structure, since with thicker films the solvent must penetrate a greater distance to reach the substrate.

Photosensitive films having a thickness of about 0.5 to 25 microns have generally been found to be suitable. However, the particle size of the matrix material used and the type of lattice structure can affect the limits of suitable film thickness for a given application. The photosensitive structures of the present invention also exhibit improved photosensitivity compared to many prior art systems.

For example, the photosensitive printing plates described herein can be activated by actinic radiation exposure about 3 to 5 times faster than conventional wipe-on diazo printing. This improved photoresponsiveness provides additional benefits. For example, because development efficiency is significantly affected by the wettability and permeability of the film surface, selective transmission and development can be achieved by short-term exposure to actinic radiation only at or near the surface level. It has been proven to be effective. These short exposure techniques may be particularly preferred where development is followed by heat, since in these cases the ink receptivity and durability of the fill structure is not dependent on exposure. It is. The following examples are not to be construed as limiting the scope of the invention, but rather are illustrative of methods and compositions for making the photosensitive structures of the invention.

Example 1 Rh0piexAC-388 (ROhm & Haas,
Philadelphia, Pa. Blend 100 grams of acrylic emulsion vehicle (commercially available from Yahoo! Co., Ltd.), 10 grams of water, and 2 grams of DlazO4 for about 5 minutes or until well mixed.

This mixture is loaded onto a roller coater and coated onto a brushed grained aluminum substrate to form a dry film approximately 5 microns thick. Air dry in about 2 minutes. The intensifier plate is then placed in vacuum contact with the film negative and exposed to the output of a 2 kW xenon source for 15 seconds. After exposure, the plate is developed with regular tap water and coated with rubber. The plate is then mounted on an offset press using conventional fountain solutions and inks. As a result, as many as 80,000 copies of high quality images can be obtained, and the deterioration of the image is kept to a minimum. Example 2 E1vace1875 (DuPOnt, Wilming
tOn, Del. 100 ml of acetate/ethylene copolymer aqueous emulsion, commercially available from Graf-COmCO., East On, 5 ml of water and DiazO (Graf-COmCO., East On,
Approximately 1 gram of photosensitive material (commercially available from Maryland, Inc.) is combined in a conventional stirring mixer in approximately two portions until well mixed.

The mixture is rubbed onto a brushed grained aluminum substrate and dried to a film thickness of approximately 2 microns. Air dry in about 1 minute. The intensifier plate was then placed in vacuum contact with the film negative and exposed to the output of a 2 kW xenon source for approximately 30 seconds. After exposure, the plate is developed in tap water and rubber-coated as usual. This plate was then offset pressed (
For example, 1250Address0graphAAu1t
igraph) and printed using conventional alkaline fountain solutions and inks. Thousands of copies were obtained. Example 3 GelvaTSlOO(MOn
santOCOrp. NewpOrtBeach, Ca
l. Water-based polyvinyl acetate commercially available from
long complex acrylate copolymer emulsion) 100m11
Blend 10 ml of water and 4 g of DiazO4L until well mixed.

This mixture is applied to an ungrained aluminum silicate substrate and dried to a thickness of about 5 microns. Air dry in about 2 minutes. The sensitized plate was then placed in vacuum contact with the film negative and exposed to the power of a 3 kW mercury vapor source for 5 seconds. After exposure, the plate is developed with regular tap water. After development, the plates are mounted on offset press soils and printed with conventional press materials. 6000 high quality copies are obtained with no apparent image wear. Example 4 GelvaTS30 and GelvaS52 (both MOn
santOCOrpuriNewpOrtBeach,Ca
Approximately 2 portions of 100 ml of aqueous polyvinyl acetate emulsion (commercially available from L.L.) and 2 g of DiazO are mixed.

This mixture is applied to a brushed grained aluminum substrate and dried to a film thickness of about 10 microns. The two intensifying plates made as described above were then placed in vacuum contact with the film negative and then exposed to the output of a 3 kW xenon source for 60 seconds. After exposure, the plate is developed with tap water and coated with rubber, then one plate is heated to 2500F (121.1℃).
) Place in a reflux oven set to 100°C for 2 minutes. Comparative tests show that the heated samples are significantly more durable and have higher ink receptivity. However, all these versions yield high quality copies. Approximately 50 for the unheated version
,000 copies were obtained, with 5 heated plates 20
Over 0,000 copies were obtained. Example 5 100mζ water 50ml of Ge1vaTS100 and Di
Mix azO4Llg until well mixed (about 1 minute) 5.

This mixture is applied to a tellurium-coated mylar substrate and dried to a film thickness of approximately 2 microns. Air dry in about 1 minute.
The sensitized plate is exposed for 10 seconds to the power of a 3 kW mercury vapor source in vacuum contact with the film negative. After exposure,
The print is immersed in an aqueous solution of NaOct and 4NaOH without scrubbing. When this board was inspected, it was found that the tellurium in the non-exposed areas was corroded by this solution. The membrane is completely intact. Thus, no withdrawal was occurring, but rather only selective infiltration. Example 6 50 ml of Ge1vaTS100, 50 ml of water and Di
Add 2g of azO until well mixed (about 2 minutes in a stirring mixer)
Blend.

This mixture is then applied to a ball grained, unsilicate aluminum substrate and dried to a film thickness of approximately 2 microns. Air dry in about 2 minutes. The sensitized plate was then placed in vacuum contact with a film negative and exposed to the output of a 2 kW xenon source for 30 seconds. After exposure, the plate is developed by briefly moistening and rinsing with tap water. I didn't scrub it and the coating remained completely intact. The plates are tested for wettability and ink adhesion by wetting them with conventional ink sump solutions and inking them with a cotton sponge and ink. Selective adhesion of ink was observed depending on the image, and it was confirmed that the non-exposed areas became porous due to leaching of diazo, thereby imparting wettability with water. Example 7 TS98 and TS3O (both MOnsantOCOrp
．． , NewpOrtBeachCal. Aqueous emulsion of polyvinyl acetate commercially available from
0m1! and 2 g of DlazO4L until well mixed (about 2 minutes in a conventional stirring mixer).

This mixture is applied to shallowly grained and deeply grained aluminum substrates. The film is dried in air for about 3 minutes to a thickness of about 8 microns. The sensitized plate was then brought into vacuum contact with the film negative and exposed to the power of a 3 kW xenon source for 90 seconds. After exposure, the plate is developed by rubbing gently with tap water and then coated with rubber. Both plates were heated at 250℃ (121.1
℃) for 2 minutes and then mounted on a commercially available web lithography press. No signs of image wear are observed after printing 150,000 plates on either the light grain or deep grain plates. It will be apparent to those skilled in the art that various changes and modifications can be made to the invention described herein.

Such changes and modifications may be made without departing from the spirit or scope of the invention or diminishing its associated advantages. For example, many modifications to the grid design described herein are possible while remaining within the spirit and scope of the invention. Additionally, filler materials (e.g. colorants such as Lowbon Black) may be used as an inert third phase to enhance color, improve shelf life, or provide special optical, magnetic or electrical properties. May be granted. Therefore, such changes and modifications are also included within the scope of the claims.

[Brief explanation of the drawing]

Figures 1, 2 and 3 are each an enlarged cross-sectional diagram illustrating a microstructural embodiment of the printing material of the present invention.

Claims (1)

[Scope of Claims] 1. Having a single layer of a photosensitive film structure on at least one side of the substrate, the structure being formed from an emulsion-dispersion and having a continuous phase and a uniform layer throughout the structure. a dispersed discontinuous phase, the continuous phase being a minor component of the structure and containing a photosensitive substance selected from the group consisting of diazo compounds, photosensitive resins, photosensitive dyes and dichromates; , whose solubility in a given aqueous developer is altered by electromagnetic irradiation, the discontinuous phase consists of a polymeric particulate material insoluble in the aqueous developer, and the structure has a maximum thickness of about 10 microns; a printing material which is selectively developable and which forms an image by dissolving and removing the soluble part of the continuous phase material by said aqueous developer after exposure. 2. The printing material according to item 1 above, wherein the photosensitive substance is a condensation product of a carbonyl compound and a diazo compound. 3 The photosensitive substance is a carbonyl compound and 4-diazo-1,
The above-mentioned first compound is a condensation product with 1'-diphenylamine.
Section printing materials. 4. Printing material according to paragraph 1, wherein the polymeric particulate material is selected from the group consisting of polyvinyl acetate, acrylic polymers and copolymers thereof. 5. Printing material according to item 1 above, wherein the photosensitive film structure is cast from an aqueous polymer emulsion-dispersion and the photosensitive substance is a water-soluble diazo compound rendered insoluble in water by actinic radiation. 6 The above-mentioned No. 1 in which the substrate is metal or synthetic plastic.
Section printing materials. 7. Printing material according to item 1 above, wherein the emulsion-dispersion contains a colorant. 8. The printing material according to item 7 above, wherein the colorant is carbon black. 9. The printing material according to item 1 above, wherein the substrate is a synthetic plastic and the photosensitive substance is a diazo compound. 10 The substrate is a synthetic plastic, the emulsion-dispersion contains carbon black, the photosensitive material is a diazo compound, and the polymeric particulate material is made of polyvinyl acetate, acrylic polymers and copolymers thereof. The printing material according to item 1 above, selected from the group consisting of: