Surface treatment apparatus for printing plate support

Abstract: An apparatus for continuously treating a surface of a support with steam includes a steam treating chamber for supplying the steam to the support and a bath containing a liquid disposed at at least one of an entrance section and an exit section of the steam treating chamber, the support passing through the bath while being supported by a roller provided in the bath.

Description: The present invention relates to an entrance section of an apparatus used for making surface treatment supports for printing plate, particularly, a support such as an aluminum plate on which an anodized film has been formed or which has been dyed. Conventionally, in the case where an aluminum (including aluminum alloy) plate is used as a support for a printing plate, an anodized film is formed on the aluminum plate. A surface treatment method is known in which, after an anodized film has been etched so as to act suitable adhesion between the support and a photosensitive layer, sealing with steam or hot water is used. (See USP 4,116,695 corresponding to Japanese Examined Patent Application No. 12518/1981). This method provides a photosensitive printing plate which has a good shelf-life stability, good development performance, and no staining in non-image areas. At an entrance section of such an apparatus which is used for continuous treatment of a support with steam, for carrying out the above method, it is necessary to provide some means for preventing leakage of steam. A conventional sealing apparatus is known in which rollers support the back of the plate, and an exhaust port is arranged against the surface of the plate with making a clearance as narrow as possible. (See Japanese Unexamined Patent Application No. 131470/1983). As shown in Fig. 1, an apparatus in which, for making the quantity of leaking steam as small as possible, use a seal section having a labyrinth structure 11 which does not touch the surfaces of the support 1 at the entrance is also known. However, both the above-described apparatuses have the following problems: 1. Precise seal structures are required at the entrance sections. 2. There is a limitation of the narrowness of the gap so as to prevent damage to the support due to the unavoidable vibration of the support during its advancing. Therefore, effective prevention of leakage is often difficult. 3. The apparatuses require the provision of an arrangement which allow the gap clearance increasing when portions such as the joint sections of old and new supports pass through the entrance, that is, where the thickness of the support varies and the travelling behavior of the support is unstable. Therefore, the apparatuses are necessarily complicated and of large scale. 4. A large amount of steam is required. Accordingly, an object of the invention is to eliminate the above problems and to provide a surface treatment apparatus for printing plate supports which has a entrance section which employs only the minimum amount of steam and which does not damage the support, irrespective of its thickness and vibration of the support. US-A-3 685 837 discloses a method and a device for sealing a continuous product wherein a liquid such as water is used to effect sealing between two zones with different pressures. Turbulences are created in the liquid to reduce the dimensions of the seal which is formed in a space between the zones. SUMMARY OF THE INVENTION The above and other objects of the present invention are achieved by an apparatus comprising the features set out in claim 1. According to a first embodiment of the invention, the sealing means comprises a bath which contains liquid and which is arranged at at least one of an entrance section and an exit section of the apparatus through which the support passes while being supported by rollers. The entrance section of the apparatus of the present invention is sealed by the liquid in the baths through which the support supported by the rollers passes. According to a second embodiment, the sealing means is a curtain of water flowing against the support. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional side elevational view showing a conventional entrance section of a labyrinth structure; Fig. 2 is a sectional side elevational view showing a preferred embodiment of a surface treatment apparatus for printing plate supports constructed according to the present invention; and Fig. 3 is a sectional side elevation view showing an alternate embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 2 is a sectional side elevational view showing a preferred embodiment of a surface treatment apparatus for printing plate supports according to the present invention. Fig. 2 depicts an apparatus of the present invention in which, for example, a support etched after an anodized film has been formed thereon enters a steam treatment apparatus 3 and is there treated with steam so as to seal the pores of the etched surface with steam blown from a steam-supplying nozzle 2. At the entrance section 4 and at the exit section 5, which connect the inside with the outside of the apparatus, respective baths 6 and 7 are arranged to seal the path between the inside and the outside of the apparatus by a liquid through which a support 1 passes while being supported by rollers 8. Fig. 3 shows a modification of the apparatus of Fig. 2 wherein a curtain of water is formed at an entrance section 4 along a wall 9 of the apparatus from a water-supplying nozzle 10, and a bath 6 contains liquid through which the support passes while being supported by the rollers 8. In this case, the bath 6 receives the flowing liquid. Otherwise, this embodiment is the same as that of Fig. 2 in that the entrance and exit of the steam treatment apparatus 3 are sealed by liquid. The preferred liquid used in the present invention is hot water, but water at room temperature may be used. Of course, pure water may be used; however, at least one of an organic solvent, amine compound, organic acid, phosphorous oxyacid or phosphorus oxysalt, sulfur oxyacid or sulfur oxysalt, and arsenic oxyacid and arsenic oxysalt may be used. Also, as to the printing plate support used with the present invention, a plate made of either pure aluminum or aluminum alloy can be used. For the case of a plate made of an aluminum alloy, various materials may be used for alloying purposes, for example, silicone, copper, manganese, magnesium, chrome, zinc, lead, bismuth, and nickel. Any oil, corrosion or dust of course should be removed from the aluminum plate, and a surface graining treatment should be applied as needed. The graining-treated aluminum plate is then etched and further etched after an anode-oxide film is formed. A suitable example of such a treatment is described in USP 4,116,695. The etching treatment may be omitted before and after formation of the anodized film. When a continuous treatment with steam is carried out using the present invention, the temperature of the treatment should be between about 80 and 200°C, and preferably between about 90 and 120°C. The time of treatment can be freely selected, for example, between 3 seconds and 30 minutes, but is preferably between 5 seconds and 10 minutes. The pH value of the liquid should be between about 2 and 11, and preferably is about 3 and 10. If the treatment is carried out using pressurized steam, the pressure is suitably between about 1 and 15 kg/cm² (absolute pressure), and preferably between about 1 and 5 kg/cm². The support for a printing plate according to the present invention attains a high surface wettability and good adhesion to the compound coated thereon, so that the support may be used as it is. However, the surface of the support may be treated, if desired, with an undercoating. USP 4,116,695 discloses suitable photosensitive compounds, etc ., that can be used with the invention. The present invention will be further explained with reference to a specific example thereof. Example of the Invention: An aluminium plate 0.0004m (0.4mm) thick and 1.5m (1500mm) wide was formed with an anodized film and etched. A surface hole-sealing treatment was applied thereto by steam using an apparatus as shown in Fig. 2. The conditions in the steam treatment (hole-sealing) apparatus 3 were a pressure of 19.6 · 10³Pa (0.2m (200mm) (Aq)) and a temperature of 98 - 102°C. Hot water at 70°C was filled in the baths 6 and 7, which had dimensions of 0.3m (300mm) by 1.8m (1800mm) in the bottom plane and 0.4m (400mm) in height. Steam was supplied at a rate of 150 kg/hr. With this apparatus, it was found that the leakage of steam was positively prevented at the entrance sections of the apparatus. Comparative Example: A labyrinth-type sealing apparatus shown in Fig. 1 was tested under the same conditions as the above example of the invention. The apparatus had a clearance 12 of the narrowest section in the labyrinth structure of 10 mm. With this apparatus, leakage of steam was often observed. Moreover, the quantity of steam used was 950 kg/hr, which is more than about six times that required in the above apparatus of the invention. Thus, the surface treatment apparatus according to the present invention attains the following advantages: (1) The leakage of the steam is prevented to decrease remarkably the quantity of the steam needed. (2) The construction of the entrance sections is simple in structure, thus reducing the cost of the apparatus. (3) No especially narrow clearance is required, making the manufacture of the apparatus easier. Moreover, soaking the support in the liquid in the bath effects a sufficient wetting treatment, enhancing the quality of the manufactured product and reducing its cost.

Claims: An apparatus for continuously treating the surface of a support (1) for a printing plate with steam, comprising: rollers (8) for supporting the support (1); steam treating means (3) for supplying steam to a surface of said continuously travelling support; and sealing means disposed at at least one of an entrance section and an exit section of said steam treating means (3) for sealing egress of steam from said steam treating means, characterized in that said sealing means comprises a bath (6, 7) and a roller (8) disposed in said bath (6, 7), said support passing through said bath (6, 7) while being supported by said roller (8) in said bath (6, 7). The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein one said bath (6) containing said liquid is disposed at said entrance section (4) and one said bath (7) containing said liquid is disposed at said exit section (5) of said steam treating means (3). The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein said sealing means further comprises means for providing at least one curtain of water flowing against said support (1). The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein said liquid is hot water. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein said liquid is water at room temperature. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein said liquid is pure water. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein said liquid comprises at least one of an organic solvent, amine compound, organic acid, phosphorous oxyacid or phosphorus oxysalt, sulfur oxyacid or sulfur oxysalt, and arsenic oxyacid and arsenic oxysalt. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein the temperature in said steam treating means is between about 80 and 200°C. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein the temperature in said steam treating means is between about 90 and 120°C. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein a time of treatment of said support (1) in said apparatus (3) is between 3 seconds and 30 minutes. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein a time of treatment of said support (1) in said apparatus (3) is between 5 seconds and 10 minutes. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein the pH value of said liquid is between about 2 and 11. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein the pH value of said liquid is between about 3 and 10. The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein a pressure of said steam is between about 1 and 15 kg/cm² (absolute pressure). The apparatus for continuously treating a surface of a support with steam according to claim 1, wherein a pressure of said steam is between about 1 and 5 kg/cm² (absolute pressure).

Inventors: KANEKO NOBUYOSHI, KANEKO, NOBUYOSHI, KANEKO, NOBUYOSHI, C/O FUJI PHOTO FILM CO.,LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1991
Main classification: B41N3
IPC codes: C25D11, B41N3