Abstract:
A method for the treatment of a wiping solution, characterized by including: adding a flocculant to a used wiping solution for flocculation of ink contained in said used wiping solution; filtering said used wiping solution for separation of said used wiping solution into sludge and a filtrate; heating said filtrate to produce distilled water and a concentrated solution; returning said distilled water for recycling to serve as a raw material of a wiping solution; and heating said concentrated solution for separation of said concentrated solution into steam and a solid residue. An apparatus for performing the method of the present invention is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for the treatment of a wiping solution which is employed for cleaning a wiping roller used for wiping off ink. 
     2. Background Art 
     A wiping roller for wiping off excess ink that adheres to intaglios placed around an intaglio cylinder of an intaglio printing press is partially immersed in a wiping solution contained in a wiping-solution tank, so that the ink adhering to the immersed portion is dispersed into the solution; and operation can continue for removal of excess ink from the intaglio cylinder. When such a wiping solution containing dispersed ink is disposed of without being subjected to any treatment, the solution may cause environmental problems. Therefore, a variety of means for the treatment of such a used wiping solution to enable recycling of the solution have already been proposed. 
     For example, Japanese Patent Application Laid-Open (kokai) No. 10-85789 discloses a method for the treatment of a used wiping solution. In the method, a used wiping solution is separated into a transparent solution and a residual solution by use of an ultrafiltration membrane (UF membrane), and the transparent solution is recycled as a raw material of a wiping solution; a flocculant (an alkali salt) is added to the residual solution for flocculation of ink components; the resultant solution is subjected to filtration to thereby produce a solid product and a filtrate; the solid product is disposed of as waste, and the filtrate is neutralized and then separated into a distilled water and a concentrated salt solution through distillation; and the distilled water is recycled as a raw material of the wiping solution, and a portion of the concentrated salt solution is recycled as the flocculant. 
     However, the method disclosed in Japanese Patent Application Laid-Open (kokai) No. 10-85789 involves the following problems: 
     (1) since a wiping solution concentrated into the form of slurry is subjected to filtration by use of a UF membrane, pores of the membrane tend to become clogged with the slurry, and thus the membrane must be changed frequently, resulting in laborious operation; and 
     (2) solutions which are treated in different ways to have different states—a transparent solution obtained through filtration by use of a UF membrane, distilled water, etc.—are employed as raw materials of a wiping solution, and thus it is difficult to produce a wiping solution having consistent properties. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, an object of the present invention is to provide a method and apparatus for the treatment of a wiping solution, which facilitate the treatment of a used wiping solution and enable the production of a wiping solution having consistent properties. 
     In order to solve the aforementioned problems, the present invention provides a method for the treatment of a wiping solution, which comprises adding a flocculant to a used wiping solution for flocculation of ink contained in the used wiping solution; filtering the used wiping solution for separation of the used wiping solution into sludge and a filtrate; heating the filtrate to produce distilled water and a concentrated solution; returning the distilled water for recycling to serve as a raw material of a wiping solution; and heating the concentrated solution for separation of the concentrated solution into steam and a solid residue. 
     In order to solve the aforementioned problems, the present invention also provides an apparatus for the treatment of a wiping solution, which comprises ink flocculation means for flocculating ink contained in a used wiping solution by the addition of a flocculant to the used wiping solution; solid-liquid separation means for separating, into sludge and a filtrate, the used wiping solution containing the ink which is flocculated by the ink flocculation means through filtration of the used wiping solution; distilled water production means for producing distilled water and a concentrated solution through heating of the filtrate which is separated by the solid-liquid separation means; water recycling means for recycling the distilled water which is produced by the distilled water production means as a raw material of a wiping solution; and post treatment means for separating the concentrated solution into steam and a solid residue through heating of the concentrated solution which is produced by the distilled water production means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features, and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood with reference to the following detailed description of the preferred embodiments when considered in connection with an accompanying drawings, in which: 
     FIG. 1 is a schematic representation showing an embodiment of the apparatus of the present invention for the treatment of a wiping solution; and 
     FIG. 2 is a quantity-balance flowchart of the Example of the method of the present invention for the treatment of a wiping solution. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An embodiment of the method and the apparatus of the present invention for the treatment of a wiping solution will next be described with reference to FIG.  1 . FIG. 1 is a schematic representation showing the apparatus for the treatment of a wiping solution. 
     As shown in FIG. 1, a wiping roller  11  which abuts an intaglio cylinder  100  of an intaglio printing press is immersed in wiping solution  1  in a wiping-solution tank  12 . The wiping solution  1  contains water  2  and a surfactant  3  predominantly containing sodium hydroxide (NaOH) and sulfonated castor oil (S.C.O), so as to facilitate dispersion of ink into the solution in accordance with the composition or amount of the ink. 
     The wiping-solution tank  12  is connected to an inlet port of an adjustment/circulation apparatus  13 . An outlet port of the adjustment/circulation apparatus  13  is connected to the wiping-solution tank  12 . A supply port of the adjustment/circulation apparatus  13  is connected, via a feed pump  14 , to a production tank  15  in which the water  2  and the surfactant  3  are mixed at a predetermined ratio, and stirred, to thereby produce the wiping solution  1 . A discharge port of the adjustment/circulation apparatus  13  is connected to a used-solution tank  16 . 
     The adjustment/circulation apparatus  13  maintains the temperature of the wiping solution  1  supplied from the wiping-solution tank  12  at 45-55° C., and measures the amount of the solution  1  and the concentration of a detergent or ink components contained in the solution  1 . When the amount of the wiping solution  1  in the apparatus  13  is insufficient, the feed pump  14  is operated, and then a fresh wiping solution  1  is supplied from the production tank  15  to the apparatus  13 . When the amount of a detergent component in the wiping solution  1  is small or when the amount of ink components in the solution  1  is large, the used wiping solution  1  circulating in the apparatus  13  is fed to the used-solution tank  16 , and a fresh wiping solution  1  is supplied from the production tank  15  to the apparatus  13 . 
     The used-solution tank  16  is connected, via a feed pump  17 , to a first flocculation tank  18  into which a first flocculant  4   a  such as calcium chloride (CaCl 2 ) is supplied. The first flocculation tank  18  is connected to a second flocculation tank  19  into which a second flocculant  4   b  such as ferric chloride (FeCl 3 ) is supplied. The second flocculation tank  19  is connected to a third flocculation tank  20  into which a filtration accelerator  4   c  is supplied. The third flocculation tank  20  is connected to a flocculated-solution tank  22  via a feed pump  21 . In the present embodiment, the thus-described feed pumps  17  and  21 , the first through third flocculation tanks  18 - 20 , and the flocculated-solution tank  22  constitutes the ink flocculation means. 
     The flocculated-solution tank  22  is connected, via a feed pump  23 , to a dehydration filter  24  of a pressure-type or a vacuum-type, which is employed for separating the wiping solution  1  which has undergone the flocculation treatment into sludge  5  and a filtrate  6 . A filtrate discharge port of the dehydration filter  24  is connected to a filtrate tank  25 . In the present embodiment, the thus-described feed pump  23 , the dehydration filter  24 , and the filtrate tank  25  constitutes the solid-liquid separation means. 
     The filtrate tank  25  is connected to a condenser (evaporator)  27  via a feed pump  26 . In the condenser  27 , the filtrate  6  which is supplied from the filtrate tank  25  is sprayed onto a heat-exchange tube through which a heating medium passes, and is then evaporated and cooled, to thereby produce distilled water  7 . A non-evaporated residue is repeatedly sprayed onto the heat-exchange tube, to thereby produce a concentrated solution (salt solution)  8 . A distilled water outlet port of the condenser  27  is connected to a distilled water tank  28 . A concentrated solution outlet port is connected to a concentrated-solution tank  29 . In the present embodiment, the distilled water production means comprises the thus-described feed pump  26 , the condenser  27 , the distilled water tank  28 , and the concentrated-solution tank  29 . 
     The distilled water tank  28  is connected to the production tank  15  via a feed pump  30 . The concentrated-solution tank  29  is connected to a dryer (drum dryer)  32  via a feed pump  31 . In the dryer  32 , the concentrated solution  8  which is supplied from the concentrated-solution tank  29  is blown through a sprayer  32   b  onto the surface of a drum  32   a , the inside of which is heated by steam, to thereby evaporate a liquid component and discharge steam  9  through an exhaust fan  32   d . A solid salt  10 , a solid residue which adheres to the surface of the drum  32   a , is scraped off the surface by use of a scraper  32   c  and is recovered. In the present embodiment, the water-recycling means includes the feed pump  3   0 ,and the post treatment means includes the feed pump  31  and the dryer  32 . 
     The method for the treatment of a wiping solution which employs the aforementioned apparatus will next be described. 
     Excess ink adhered to an intaglio on the intaglio cylinder  100  is wiped off by the wiping roller  11 , and then dispersed into the wiping solution  1  in the wiping-solution tank  12 . The wiping solution  1  containing the dispersed ink in the wiping-solution tank  12  is supplied to the adjustment/circulation apparatus  13 . In the apparatus  13 , the solution is maintained at a constant temperature, and the amount of the solution and the concentrations of the surfactant  3  and ink components are measured. When the amount of the wiping solution  1  in the wiping-solution tank  12  is small, the feed pump  14  is operated and a fresh wiping solution  1  in the production tank  15  is supplied to the apparatus  13  for replenishment. When the concentration of the surfactant  3  in the wiping solution  1  is low or when the amount of ink components present in the solution  1  is large, the wiping solution  1  in the wiping-solution tank  12  is fed to the used-solution tank  16 , and a fresh wiping solution  1  is supplied from the production tank  15  to the apparatus  13 , such that the concentrations of the surfactant  3  and the ink components contained in the wiping solution in the tank  12  fall within a predetermined range. 
     The wiping solution  1  which is fed to the used-solution tank  16  is supplied from the tank  16  to the first flocculation tank  18  through the feed pump  17 , and a first flocculant  4   a  such as calcium chloride (CaCl 2 ) is added thereto. Subsequently, the resultant solution is fed to the second flocculation tank  19 , and a second flocculant  4   b  such as ferric chloride (FeCl 3 ) is added. Thereafter, the mixture solution is fed to the third flocculation tank  20 , and a filtration accelerator  4   c  is added to the solution, and then the solution is fed to the flocculated-solution tank  22  through the feed pump  23 . Through the above procedure, the ink components contained in the wiping solution  1  is flocculated. It should be noted that the filtration accelerator  4   c  is added to the wiping solution  1  when an oily substance which is difficult to filter is produced through flocculation by the addition of the flocculants  4   a  and  4   b . Whether the filtration accelerator is added or not, or the amount of the accelerator added, is determined in accordance with the type of ink contained in the solution  1 . 
     The wiping solution  1  which has undergone the flocculation treatment is supplied from the flocculated-solution tank  22  to the dehydration filter  24  through the feed pump  23 , and then separated into the sludge  5  and the filtrate  6 . The sludge  5  is charged into drums or similar containers, and then disposed of. The filtrate  6  is fed to the filtrate tank  25 , and then fed to the condenser  27  through the feed pump  26 . 
     The filtrate  6  fed to the condenser  27  is sprayed onto the heat-exchange tube through which a heating medium passes, and then evaporated and cooled. The resultant water is recovered as the distilled water  7  (recovery ratio: about 80%). The non-evaporated residue is repeatedly sprayed onto the heat-exchange tube, to thereby produce a concentrated solution (salt solution)  8 . 
     The thus-produced distilled water  7  is stored temporarily in the distilled water tank  28 , and then fed as required to the production tank  15  through the feed pump  30 . The distilled water  7  is used as a raw material of a fresh wiping solution  1  after being mixed with water  2  and the surfactant  3  and stirred in the production tank. The concentrated solution  8  is fed to the concentrated-solution tank  29 , and then fed to the dryer  32  through the feed pump  31 . 
     The concentrated solution  8  fed to the dryer  32  is blown through the sprayer  32   b  onto the surface of the drum  32   a , the inside of which is heated by steam. On the surface of the drum, liquid components are evaporated and the steam  9  is discharged through the exhaust fan  32   d . The components of the steam  9  are similar to those of exhaust from a seawater evaporation system, and thus the steam rarely affects the environment detrimentally. The residual solid salt  10  which is adhered to the surface of the drum  32   a  is scraped off by use of the scraper  32   c , and then recovered into drums or similar containers. 
     Thus, the used wiping solution  1  is subjected to filtration after flocculation of ink components, and the resultant filtrate is heated and evaporated, to thereby produce distilled water  7 . Only the distilled water is recycled as a raw material of the fresh wiping solution  1 . 
     Therefore, clogging does not occur in the dehydration filter  24 , and a wiping solution having consistent properties can be easily produced in the production tank  15 . 
     Consequently, the used wiping solution  1  can be easily treated, and even when water contained in the used wiping solution is recycled, a wiping solution having consistent properties can be easily produced. 
     EXAMPLE 
     The method and apparatus for the treatment of a wiping solution of the present invention will next be described by way of example with reference to FIG.  2 . FIG. 2 is a quantity-balance flowchart of the method for the treatment of a wiping solution of the Example of the present invention. 
     As shown in FIG. 2, when four intaglio printing presses are employed, ink is dispersed in a wiping solution in an amount of 2,400 kg/day. When a wiping solution is employed in an amount of 21,600 kg/day, the concentration of ink contained in the wiping solution is 10 wt.%, and the amount of used wiping solution is 24,000 kg/day. 
     A flocculant is added to the used wiping solution to flocculate the ink, and then the resultant solution is subjected to filtration and separation into sludge (water content: 50%) (4,800 kg/day) and a filtrate (salt content: 2%) (19,200 kg/day). The filtrate is concentrated to 1/10, to thereby produce distilled water (17,280 kg/day) and a concentrated solution (salt content: 20%) (1,920 kg/day). 
     When the percentages of sodium hydroxide and sulfonated castor oil in a fresh wiping solution are set at 0.8 wt.% and the above-produced distilled water is recycled as a raw material of the wiping solution, the amounts of sodium hydroxide (30% aqueous solution) and sulfonated castor oil (50% aqueous solution), which are employed for producing the wiping solution, are 576 kg/day and 346 kg/day, respectively. In this case, the amount of water employed for replenishment is 3,398 kg/day. Therefore, water can be recycled at a recovery ratio of 80%. 
     When the concentrated solution is heat-dried, steam (1,440 kg/day) and a solid salt (480 kg/day) are produced. Consequently, the amount of waste containing the sludge and the solid salt is 5,280 kg/day; i.e., the amount of waste can be reduced. 
     In the method and apparatus for the treatment of a wiping solution of the present invention, the used wiping solution is subjected to filtration after flocculation of the ink components contained in the solution; the resultant filtrate is heated and evaporated to thereby produce distilled water; and only the distilled water is recycled as a raw material of a fresh wiping solution. Therefore, clogging does not occur during filtration, and a wiping solution having consistent properties can be easily produced. Consequently, the used wiping solution can be easily treated, and even when water contained in the used wiping solution is recycled, a wiping solution having consistent properties can be easily produced.