JP2009293112A - Pretreatment method of chelate resin for prolonging life of operation bath for trivalent chromium chemical conversion coating treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that trivalent chromium ion and cobalt ion being main constitutive components of a trivalent chromium chemical conversion coating treatment solution (operation bath) are removed when use of the solution is started, the composition of the solution becomes unstable, and the appearance, the heat resistance and the corrosion resistance of a chemical conversion coating are deteriorated when prolonging the life of the trivalent chromium chemical conversion coating treatment solution (operation bath) using a chelate resin. <P>SOLUTION: Trivalent chromium ion and cobalt ion are previously brought into contact as a solution with a chelate resin used for prolonging the life of the operation bath for trivalent chromium chemical conversion coating treatment so that the chelate resin is brought into such a state that each ion are adsorbed on the chelate resin in a saturated state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pretreatment method for a chelate resin used for extending the life of a trivalent chromium conversion coating treatment operation bath, a method for extending the operation bath lifetime, and a trivalent chromium conversion coating treatment method using the chelate resin. .

  The chromate treatment is widely used as a simple rust prevention and coating pretreatment for galvanized steel sheets, zinc-based, aluminum-based and magnesium-based products. Conventionally, a chromate solution containing hexavalent chromium has been used as a chromate treating agent. However, since hexavalent chromium is harmful to the human body, in recent years, a trivalent chromium conversion coating solution containing trivalent chromium as a main component. The transition to is progressing.

  However, the trivalent chromium conversion coating solution is more susceptible to metal ions eluted during the treatment than the hexavalent chromate solution. For example, when used for the treatment of galvanized steel sheets, iron (Fe) or zinc The allowable limit of (Zn) or the like is narrow, and it is necessary to frequently update the treatment liquid (operating bath). As a means for solving this problem, Patent Document 1 discloses that a trivalent chromium chemical conversion film treatment solution is a chelate having an iminodiacetic acid group in which the proportion of the carboxylic acid form exceeds 50 mol% among the carboxyl groups of the iminodiacetic acid group. A method for regenerating a trivalent chromium chemical conversion coating solution in which impurity metal ions are reduced by contacting with a resin is disclosed.

  In connection with such a method for regenerating a trivalent chromium conversion coating solution (longevity method), Patent Document 2 discloses that raw water containing heavy metal is passed through a chelate resin having an iminodiacetic acid group, In a method for removing heavy metals in raw water that generates reduced treated water, the iminodiacetic acid of the raw water is used as an indicator of a decrease in the rate of change in the pH of the treated water after the pH of the treated water reaches a steady state. A method for removing heavy metals in raw water that stops water flow to a chelate resin having a group is disclosed.

JP 2006-137987 A JP 2004-174418 A

  By means described in Patent Document 1, it is possible to extend the life of the trivalent chromium chemical conversion coating solution. Further, Patent Document 2 gives an end point management standard for implementing the means described in Patent Document 1. However, in the regeneration treatment and longevity treatment of the trivalent chromium chemical conversion coating solution, trivalent chromium ions and cobalt ions, which are main components of the treatment solution, are adsorbed on the chelate resin, particularly at the start of use of the chelate resin. Since it is removed from the treatment liquid, the composition of the trivalent chromium chemical conversion film treatment liquid (operating bath) becomes unstable, which causes a problem that the appearance, heat resistance, and corrosion resistance of the chemical conversion treatment film deteriorate. The technical means described in Patent Documents 1 and 2 do not solve the problem at the start of using such a chelate resin.

  The present invention extends the life of a trivalent chromium conversion coating solution (operating bath) that uses a chelate resin, and in particular, the main components of the trivalent chromium conversion coating solution (operating bath) at the start of use of the chelate resin. An object of the present invention is to solve the problem that the trivalent chromium ions and cobalt ions are removed from the treatment liquid, the composition becomes unstable, and the appearance, heat resistance, and corrosion resistance of the chemical conversion film are deteriorated.

  The pretreatment method of the chelating resin for extending the lifetime of the trivalent chromium chemical conversion film treatment working bath according to the present invention is based on the trivalent chromium ion and the chelating resin for extending the service life of the trivalent chromium chemical coating treatment used in advance. Cobalt ions are brought into contact as an aqueous solution to bring the chelate resin into a state in which the ions are adsorbed in a saturated state.

  In the pretreatment method, the chelating resin is previously brought into contact with an aqueous solution of a chemical for a building bath solution of a trivalent chromium conversion coating treatment operation bath or an aqueous solution of a component of a trivalent chromium conversion coating treatment operation bath. Can do.

  Utilizing each of the above inventions, it is possible to extend the life of the trivalent chromium chemical conversion film treatment operation bath. Moreover, a trivalent chromium chemical conversion film treatment can be performed.

  According to the present invention, in order to prolong the life of the trivalent chromium chemical conversion coating solution (operating bath) using a chelate resin, trivalent chromium ions and cobalt ions are removed from the treating solution immediately after the start of use of the chelate resin. The problem that the composition becomes unstable is solved, and the content and pH of main components of the treatment liquid are kept within a predetermined range over the entire period of use of the chelate resin, and the object to be treated over the entire period of treatment. Can maintain good corrosion resistance and appearance.

  The pretreatment method of the chelate resin of the present invention is applied to a chelate resin used for extending the life of a trivalent chromium chemical conversion film treatment operation bath. Here, the trivalent chromium chemical conversion film treatment operation bath refers to those used for the trivalent chromium chemical conversion film treatment of the object to be treated, and the surface treatment characteristics required after the composition and components of the object to be treated. Concentration and composition are determined accordingly.

  In general, this working bath is prepared by diluting the concentrated solution (stock solution) containing the necessary chemicals, and adding a component-adjusting chemical as necessary to make the bath solution, and injecting the bath solution into the treatment tank. To make a working bath. In general, the bathing solution contains cobalt ions and, if necessary, nitrate ions, sulfur compounds, phosphorus compounds, silica, organic acids, etc. in addition to trivalent chromium ions. For example, since galvanized automobile parts and household appliance parts are immersed, zinc ions, iron ions, copper ions and the like eluted from the object to be treated are contained as impurities in addition to the above-described building bath liquid components.

  When the content of impurities and the like increases, the appearance and corrosion resistance of the trivalent chromium chemical conversion film-treated product deteriorate. For example, as shown in FIG. A portion of the operation bath 4 is continuously extracted from the valence chromium conversion coating treatment tank 2 by the pump 3, and this is contacted with the chelate resin 6 packed in the ion exchange tower 5 to remove the impurities, and then the pipe 7 A life extension process is performed to return to the trivalent chromium chemical conversion film treatment tank 2. In the present invention, in this longevity treatment, the chelate resin 6 packed in the ion exchange tower 5 is previously brought into contact with trivalent chromium ions and cobalt ions as an aqueous solution, and the chelate resin is saturated with the respective ions. What was made the state adsorb | sucked to is used.

  2 and 3 show treatment liquids having compositions shown in Table 2 (having compositions corresponding to working baths) using a chelate resin having a macroporous structure polystyrene as a base and aminomethylphosphonic acid groups as functional groups. Relationship between the flow rate (BV) and treatment solution concentration (mg-Cr / l) (Fig. 2), flow rate (BV) and treatment solution concentration (mg-Co /) It is shown as a relation diagram (FIG. 3) of l). In each figure, a circle mark indicates the relationship when using a pre-treated chelate resin according to the present invention, and a x mark plot indicates an untreated chelate resin that has not been pre-treated according to the present invention. The relationship when using is shown. The pretreatment was carried out by converting the chelating resin into a hydrogen form and circulating the building bath solution having the composition shown in Table 1 through 3.5 BV equivalent, SV10 for 10 hours.

  2 and 3, when the pretreatment according to the present invention is performed on the chelate resin, the pretreatment is performed while no extreme fluctuations in Cr and Co concentrations are observed immediately after the start of liquid flow. If not, the Cr concentration is unstable up to about 25 BV and the Co concentration is unstable up to about 10 BV.

  FIG. 4 is a relationship diagram between the flow rate (BV) and the treatment solution pH showing the result of the column test when the treatment solution is passed under the same conditions as those obtained in FIGS. It can be seen from FIG. 4 that when the pretreatment according to the present invention is performed on the chelate resin, a decrease in pH at the initial stage of liquid passage is suppressed as compared with the case where the pretreatment is not performed.

  In the present invention, as described above, the trivalent chromium chemical conversion film treatment operation bath extending the life of the chelating resin is previously brought into contact with trivalent chromium ions and cobalt ions as an aqueous solution, and each of the ions is added to the chelating resin. It is characterized in that it is in a state of being adsorbed in a saturated state, and this is used as a chelating resin for extending the lifetime of a trivalent chromium chemical conversion film treatment operation, and there is no particular limitation on the structure, base and functional group of the chelating resin.

  For example, a cation exchange resin or a chelate resin capable of selectively removing impurities to be removed can be arbitrarily selected. As functional groups, iminodiacetic acid group, aminomethylphosphonic acid group, phosphonic acid group, phosphonic acid / sulfone It can be arbitrarily selected from those having acid groups, polyethylene polyamine groups, aminocarboxylic acid groups, polyamine groups, amidooxime groups, phosphoric acid groups, aminophosphoric acid groups, etc., and acrylic acid or polystyrene is selected as the base of the chelating resin can do. Moreover, as a structure of a chelate resin, a macroporous type or a gel type can be arbitrarily selected. Furthermore, the ionic form of the chelate resin can be freely selected to be in the hydrogen form or in the sodium form. For example, as a typical chelate resin used for extending the life of a trivalent chromium chemical conversion coating solution for a galvanized steel sheet, Sumika Chemtex, which has an aminomethylphosphonic acid group as a functional group and has a polystyrene-based macroporous structure Mention may be made of a chelate resin MC-960 manufactured by Co., Ltd.

  In practicing the present invention, it is necessary to bring the chelate resin into contact with at least trivalent chromium ions and cobalt ions so that these ions are adsorbed in a saturated state. These ions are all basic components of a trivalent chromium chemical conversion film treatment working bath, and the lack thereof causes damage to the corrosion resistance and appearance of the produced chemical conversion film.

  Whether other constituents of the trivalent chromium conversion coating treatment operation bath, such as nitrate ions, sulfur compounds, phosphorus compounds, silica, organic acids, etc., should be subject to pretreatment in relation to the resin used Can be determined. When these components are remarkably adsorbed, a pretreatment liquid is prepared so as to include these components, and these components may be adsorbed on the resin used.

  As the treatment liquid for performing the adsorption operation, for example, a building bath liquid can be used, but the treatment liquid is not limited thereto. For example, when only Cr and Co are adsorbed, an aqueous solution of these salts such as chromium chloride, chromium nitrate, and cobalt sulfate can be selected. In this case, the concentration may be selected so that these metal ions can be adsorbed in a saturated state in a short time as much as possible in relation to the chelate resin to be treated. It is also possible to make it approximately equal to the molar concentration in the bath solution.

  In the pretreatment method of the present invention, it is necessary to adsorb these metal ions until the resin is saturated. Although it is not necessary to specify the means for that purpose, for example, as shown in FIG. 5, an ion-exchange column 5 is filled with untreated chelate resin 8 and pre-treated liquid storage tank 9 is pumped by pump 10 in advance. This can be done by using a pretreatment facility for passing the treatment liquid 11. When this pretreatment equipment is used, the end point of the liquid flow for the pretreatment is measured at the inlet 12 and the outlet 13 of the ion exchange column 5 by the concentration of the components of the bath, for example, the concentration of trivalent chromium ions and cobalt ions. It may be performed by confirming that the density difference has disappeared. Alternatively, for each combination of the chelate resin and the pretreatment liquid to be used, the liquid passing amount (BV) until the trivalent chromium ions and cobalt ions are saturated is determined, and thus the pretreatment management can be performed. it can.

  Instead of the above, as shown in FIG. 6, a trivalent chromium chemical conversion film treatment tank 2 and an ion exchange tower 5 filled with untreated chelate resin are prepared, and the trivalent chromium chemical conversion film treatment tank 2 is prepared. Circulate the building bath solution or working solution of the trivalent chromium conversion coating solution from pump 3 through the pump 3 and pipe 7 to contact the untreated chelate resin for saturated adsorption, that is, to circulate and contact until reaching the concentration of the building bath solution. It can also be. In this case, compared with the case illustrated in FIG. 5, the pretreatment liquid storage liquid 9 can be omitted. Further, as soon as the completion of the pretreatment of the chelate resin is confirmed, the trivalent chromium conversion coating is performed as it is while extending the life. There is an advantage that it can be transferred to processing. In addition, there is an advantage that it is not necessary to separately provide a pretreatment facility.

  By performing the pretreatment as described above, the ion exchange column 5 is in a state in which the filled chelate resin has adsorbed trivalent chromium ions and cobalt ions in a saturated state. Since it can be used as the ion-exchange tower 4 for the operating bath, it can be used as it is for the service life extension of the operating bath.

  In the above, the pretreatment is performed by a method of circulating the pretreatment liquid through the ion exchange tower 5, but the pretreatment method of the present invention is not limited to this, and an unused chelate resin is used. And the pretreatment liquid may be brought into contact with each other, and the trivalent chromium and cobalt ions, and further the active ingredients contained in the building bath liquid may be adsorbed until saturated. For example, it is possible to take a measure in which an unused chelate resin is charged into a tank filled with a pretreatment liquid and these are sufficiently brought into contact with each other using an appropriate stirring device.

  According to the present invention, as shown in FIG. 2 and FIG. 3, even when a life extension process is performed using a chelate resin, from the start of use of a new chelate resin (immediately after replacement of the chelate resin) The level of trivalent chromium ions and cobalt ions can be stabilized, so that the appearance, corrosion resistance, etc. of the chemical conversion coating can be constantly maintained at a high level. Moreover, as shown in FIG. 4, the pH fluctuation at the initial stage of liquid flow can be reduced.

  In addition, the chelate resin used for the life extension treatment according to the present invention leads to breakthrough in which the adsorption no longer proceeds as the adsorption of impurities proceeds. When it is detected that such a state has been reached, the life extension process is stopped and the chelate resin regeneration process is performed. If this regenerated chelate resin is used as it is, it will adsorb trivalent chromium ions and cobalt ions at the start of use, and the composition of the trivalent chromium conversion coating treatment bath will become unstable. This causes the problem that the appearance, heat resistance, and corrosion resistance of the chemical conversion treatment film deteriorate. Therefore, the pretreatment according to the present invention must be performed when the chelate resin subjected to the regeneration treatment is reused.

  The present invention has been described above with respect to typical embodiments. However, the technical scope of the present invention is not limited to the above-described embodiments. For example, the pretreatment conditions according to the present invention can be appropriately controlled, or For example, the preprocessing conditions can be programmed and executed freely.

It is a layout diagram of the trivalent chromium chemical conversion film treatment equipment to which the present invention is applied. FIG. 3 is a relationship diagram between a liquid flow rate (BV) and a treatment solution concentration (mg-Cr / l) when performing a life extension treatment of a trivalent chromium chemical conversion film treatment working bath according to the present invention. It is a relationship figure of the liquid flow volume (BV) and process liquid density | concentration (mg-Co / l) when performing the lifetime extension process of the trivalent chromium chemical conversion film process operation | movement bath by this invention. It is a related figure of the amount of liquid flow (BV) and process liquid pH when the lifetime improvement process of a trivalent chromium chemical conversion film process operation bath is performed by this invention. It is a layout figure of the pre-processing equipment used for the present invention. It is a layout figure in case this invention is directly connected to a trivalent chromium chemical conversion film processing tank.

Explanation of symbols

1: Processed object
2: Trivalent chromium conversion coating treatment tank
3: Pump
4: Working bath
5: Ion exchange tower
6: Chelate resin
7: Piping
8: (untreated) chelate resin
9: Pretreatment liquid storage tank
10: Pump
11: Pretreatment liquid
12: Entrance (on ion exchange tower)
13: Exit (on ion exchange tower)

Claims (4)

  A trivalent chromium ion and a cobalt ion are previously brought into contact with an aqueous solution of a chelate resin for extending the lifetime of a trivalent chromium conversion coating treatment operation bath so that the ions are adsorbed in a saturated state. A pretreatment method of a chelate resin for extending the service life of a trivalent chromium chemical conversion film treatment, characterized by   The aqueous solution of the chemical | medical agent for the building bath liquid of a trivalent chromium chemical conversion film processing operation bath or the aqueous solution of the component of a trivalent chromium chemical conversion film process operation bath is contacted with the chelate resin in advance. A pretreatment method for a chelating resin for extending the service life of a trivalent chromium chemical conversion film treatment working bath.   A long life of a trivalent chromium conversion coating treatment working bath characterized by using the chelate resin treated by the pretreatment method of the chelating resin for extending the lifetime of trivalent chromium chemical conversion coating treatment operation bath according to claim 1 or 2. Method.   Use of a chelate resin treated by the pretreatment method of a chelating resin for extending the life of a trivalent chromium chemical conversion film treatment working bath according to any one of claims 1 to 3 to prolong a life of a trivalent chromium chemical conversion coating treatment operating bath A trivalent chromium chemical conversion film treatment method characterized by performing treatment.

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