Abstract:
A liquid-mixing device that minimizes solvent leakage and reduces creep of or damage to the component parts of said liquid-mixing device even at ultrahigh pressures of 100 MPa and up. Also, a liquid chromatography device using said quid-mixing device. Said liquid chromatography device is provided with a supply pump that supplies a plurality of different solutions, a liquid-mixing device that mixes the supplied solutions, a sample injection device that injects a sample into the mixture of solutions, a column that separates the components of the injected sample, and a detector that detects the separated components. The liquid-mixing device has an inlet-side connector through which the plurality of different solutions flow in, a liquid-mixing section in which said solutions are mixed, and an outflow-side connector through which the mixed solutions flow out. The inlet-side connector and the liquid-mixing section are directly bonded to each other via diffusion bonding, as are the liquid-mixing section and the exit-side connector.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a liquid mixing device for mixing liquids and a liquid chromatograph including the liquid mixing device. 
       BACKGROUND ART 
       [0002]    There is PTL 1 as a technology related to the invention. PTL 1 relates to a micro mixer and discloses a configuration having a heat exchanger structure by laminating/bonding plates in which a flow channel for mixing solvents is grooved and when attaching connectors for inflow/outflow of a mixed fluid and a heat exchange medium. 
       Citation List 
     Patent Literature 
       [0003]    PTL 1: JP-A-2006-281008 
       SUMMARY OF INVENTION 
     Technical Problem(s) 
       [0004]    As analysis using a liquid chromatograph, there is an analysis technique in which a plurality of solvents are mixed, which is called a gradient mode. In the gradient mode, a liquid mixing device for mixing a plurality of solvents to form a mobile phase is used. 
         [0005]    In recent years, a feed pressure of a fluid in a liquid chromatography apparatus has been increased in accordance with increase in speed of analysis and improvement in separation. In particular, an ultra high performance liquid chromatography analysis apparatus feeds a liquid at a pressure higher than 100 MPa. However, in a configuration of a liquid mixing device disclosed in PTL 1, analysis performed in a severe condition such as feeding a liquid at a high pressure described above is not considered. Therefore, in particular, a constituent member attached afterward cannot withstand a high pressure, and, for example, leakage of a liquid is caused due to deformation called creep or breakage. 
         [0006]    In a liquid mixing device for a liquid chromatograph, which has a configuration in which a member such as a resin seal packing is inserted between a connector portion connected to a pipe and a mixing portion for mixing liquids, the seal packing is deformed or falls out due to increase in pressure, which also results in leakage of a liquid in some cases. 
         [0007]    An object of the invention is to provide a liquid mixing device that is not deformed or broken and can reduce leakage of a liquid even in a condition of a high pressure of 100 MPa or more. 
       Solution to Problem (s) 
       [0008]    An embodiment for solving the above problem is a liquid mixing device for a liquid chromatograph, including: an inlet side connector portion to which a liquid is supplied; a liquid mixing portion having a groove for mixing the supplied liquid; and an outlet side connector portion from which the mixed liquid flows out, in which the inlet side connector portion and the liquid mixing portion are connected by diffusion bonding, and the outlet side connector portion and the liquid mixing portion are connected by diffusion bonding. 
       Advantageous Effects of Invention 
       [0009]    According to the invention, it is possible to provide a liquid mixing device for reducing creep and breakage of a constituent part and suppressing leakage of a solvent even in a condition of an ultra high pressure of 100 MPa or more and a liquid chromatography apparatus including the liquid mixing device. 
         [0010]    Problems, configurations, and effects other than those described above will be clarified by describing the following embodiments. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a whole configuration diagram of a liquid chromatography apparatus according to an embodiment of the invention. 
           [0012]      FIG. 2(A)  illustrates an example of a configuration of a liquid mixing device according to an embodiment of the invention. 
           [0013]      FIG. 2(B)  illustrates another example of the configuration of the liquid mixing device according to the embodiment of the invention. 
           [0014]      FIG. 2(C)  illustrates another example of the configuration of the liquid mixing device according to the embodiment of the invention. 
           [0015]      FIG. 3  illustrates an example (conventional of a liquid mixing device including a resin seal packing and the like. 
           [0016]      FIG. 4  illustrates a state before and after processing of a liquid mixing device according to an embodiment of the invention. 
           [0017]      FIG. 5  illustrates a problem that arises in processing of a liquid mixing device according to another embodiment. 
           [0018]      FIG. 6(A)  shows a processing flow of a liquid mixing device according to an embodiment of the invention. 
           [0019]      FIG. 6(B)  illustrates a structure of a liquid mixing device for performing the processing flow. 
           [0020]      FIG. 7  is a diagram for explaining pressure application processing according to an embodiment of the invention. 
           [0021]      FIG. 8  illustrates examples of a groove shape of a liquid mixing portion according to an embodiment of the invention. 
           [0022]      FIG. 9  illustrates examples of a laminated structure of a liquid mixing portion according to an embodiment of the invention. 
           [0023]      FIG. 10  illustrates a state of an external appearance of a liquid mixing device according to an embodiment of the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]    Hereinafter, embodiments of the invention will be described with reference to drawings. 
         [0025]      FIG. 1  is a whole configuration diagram of a liquid chromatography apparatus according to an embodiment of the invention. A liquid chromatography apparatus  100  includes a feed pump  101  for feeding a solvent  107 , a liquid mixing device (mixer)  102  for mixing the fed solvent, a sample injection device (autosampler)  103  for injecting a sample, a column oven  104  for keeping a separation column at a constant temperature, and a detector  105 . The solvent that has passed through the detector  105  is discharged as a waste liquid  106  into a tank. 
         [0026]    Although the liquid mixing device  102  is provided between the feed pump  101  and the sample injection device  103  in  FIG. 1 , the liquid mixing device  102  is also provided between the solvent  107  and the feed pump  101  in an analysis method called low-pressure gradient in some cases. 
         [0027]      FIGS. 2  illustrates a configuration of a liquid mixing device  200  according to an embodiment of the invention. The liquid mixing device  200  mainly includes an inlet side connector portion  201 , a liquid mixing portion  202 , and an outlet side connector portion  203 .  FIGS. 2(A), 2(B) , and  2 (C) illustrate examples of a positional relationship between the connector portions  201  and  203  and the liquid mixing portion  202 . In the case where a liquid is fed in a high pressure condition, it is desirable to have a configuration (A) in which no moment is applied to the liquid mixing portion  202  and only compressive/tensile stresses act thereon. 
         [0028]    Note that a shape of the inlet side connector portion  201  and a shape of the outlet side connector portion  203  may be the same or may be different depending on a condition of the device. 
         [0029]      FIG. 3  illustrates a configuration example of a conventional liquid mixing device including a seal packing. In this configuration, only a liquid mixing portion  302  having a complicated flow channel shape is bonded with a bonding method such as diffusion bonding. Only in the case of the liquid mixing portion  302 , it is easy to uniformly apply a pressure by using diffusion bonding or the like because the liquid mixing portion is generally configured by plane surfaces. However, because connector portions  301  and  303  are attached afterward, seal packing members  304  and  305  made of resin are generally used between the connector portions  301  and  303  and the liquid mixing portion  302 . This causes necessity of retightening and a problem such as creep. Further, in order to apply a pressure to the seal packing members  304  and  305 , a housing is needed in many cases, and therefore the number of constituent parts is increased, which results in high costs. Note that, although a creep amount is ignorable in a condition in which a pressure is not high (for example, 10 MPa or less), behavior as an elastic body becomes remarkable even at a room temperature in a high pressure condition (for example, 40 to 100 MPa), and therefore an influence of creep is not ignorable. A stage at which a deformation rate is high immediately after tightening is called primary creep (transient creep), and a few percent of extension generally occurs within about 10 hours. This increases a lead time in production, which is not preferable in terms of quality. 
         [0030]      FIG. 4  illustrates a state before and after processing of a liquid mixing device according to an embodiment of the invention. 
         [0031]    In a state before the processing, groove shapes  404  and  405  for connectors are not formed in an inlet side connector portion  401  and an outlet side connector portion  403 , and therefore a pressure is applied thereto at the time of diffusion bonding. Thus, the inlet side connector portion  401 , the outlet side connector portion  403 , and a liquid mixing portion  402  can be bonded to one another. When the inlet side connector portion  401 , the outlet side connector portion  403 , and the quid mixing portion  402  are bonded and are then considered to be in a bulk state, postprocessing of the inlet side connector portion  401  and the outlet side connector portion  403  are performed. Therefore, all parts are made of the same material such as metal including SUS, and thus a mixer is made of a material that suitably withstands a high pressure. That is, unlike the conventional structure illustrated in  FIG. 3 , a different material such as seal packing members does not need to be provided between the connector portions and the liquid mixing portion. Therefore, deformation, breakage, leakage of a liquid, and the like do not occur in a high pressure condition. Note that minor processing, such as prepared holes and marking for postprocessing in grooves of the inlet side connector portion  401  and the outlet side connector portion  403 , does not affect diffusion bonding or postprocessing of the connector portions in the invention. 
         [0032]      FIG. 5  illustrates a problem that arises in processing of a liquid mixing device according to another embodiment. In the case where groove (hollow) shapes  504  and  505  for connectors are processed before bonding, a pressure is riot applied to parts immediately below the connectors, i.e., the formed hollows, as compared with another region. Therefore, those parts are not subjected to diffusion bonding, and, because pressing is performed with several tons of force in the diffusion bonding, a region other than the hollows is slightly deformed by the diffusion bonding. Because of this slight deformation, in the case where a whole flow channel is formed in particular, a relationship between a female thread and a male thread cannot be secured in terms of connection with a pipe. There is another method in which a deformation amount is estimated in advance and then connectors are processed. However, in the case where a plurality of liquid mixing devices are simultaneously produced, it is difficult to have the same deformation amount in all the liquid mixing devices. 
         [0033]    It is also considered that a liquid mixing portion  502  is prepared in advance by diffusion bonding and then only an inlet side connector portion  501  and an outlet side connector portion  503  are bonded to a mixing portion by diffusion bonding. However, bonding is performed twice or more times, which results in high costs. Therefore, such method is not preferable. 
         [0034]    As described above, a liquid mixing device according to an embodiment of the invention is desired to be formed by the technique described with reference to  FIG. 4 . 
         [0035]      FIG. 6(A)  shows a processing flow of a liquid mixing device according to an embodiment of the invention.  FIG. 6(B)  illustrates a structure of a liquid mixing device for performing the processing flow. 
         [0036]    (a) A liquid mixing portion is formed to have various complicated shapes for mixing liquids. In this step, preprocessing of an inlet side connector portion  601  and an outlet side connector portion  603  is performed and a mixing portion prepared (Step  601 ). Herein, the preprocessing means that minor processing, such as grooves for marking and prepared holes, is performed in particular in upper portions of the inlet side connector portion  601  and the outlet side connector portion  603 , and the preprocessing is not necessarily performed. 
         [0037]    (b) As described above, the inlet side connector portion  601 , the liquid mixing portion  602 , and the outlet side connector portion  603 , which have been subjected to minimum preliminary processing, are bonded to one another by diffusion bonding (Step  602 ). 
         [0038]    (c) Thereafter, in the case where postprocessing of the connector portions is performed, a flow channel of the mixing portion is filled with sealing members  606  and  607  in order to prevent entry of chip powder and cutting oil (Step  603 ). The sealing members  606  and  607  do not need to be special members and may be members that can temporarily block the flow channel, such as a resin material, cotton, or paper. In particular, in order to prevent entry of even a small amount of cutting oil, a fitting sealing member whose allowance is specified may be used. Further, for example, a material melted at a high temperature, such as fixture metal, can be also used. Further, in the case of processing in which chip powder or cutting oil does not enter the flow channel of the mixing portion even when the sealing members  606  and  607  are not used, it is also possible to perform processing without filling the flow channel with the sealing members  606  and  607 . 
         [0039]    (d) After the above processing is performed, groove shapes for connectors are formed as postprocessing (Step  604 ). A liquid mixing device formed by the above processes is originally formed by diffusion bonding and therefore has an excellent pressure resistance property. No resin seal packing is used, and therefore it is unnecessary to consider occurrence of creep. The number of constituent parts is small, and therefore it is possible to suppress increase in costs. 
         [0040]      FIG. 7  is a diagram for explaining pressure application processing according to an embodiment of the invention. When a pressure is isotropically applied by using gas as a pressure medium to a liquid mixing device processed with the above method, in particular, a void in a liquid mixing portion  702  in which two or more layers are laminated is removed. As illustrated in  FIG. 7 , a lamination direction of the liquid mixing portion  702  may be in parallel to or vertical to a feed direction. 
         [0041]      FIG. 8  illustrates examples of a groove shape of a liquid mixing portion according to an embodiment of the invention. As illustrated in  FIG. 8 , it is possible to combine members on substrates having different groove shapes  801  to  808  as appropriate in accordance with an analysis condition or the like to thereby laminate the members. Mixing of a plurality of kinds of liquids is promoted by causing the liquids to pass through grooves having different shapes. 
         [0042]      FIG. 9  illustrates examples of a laminated structure of a liquid mixing portion according to an embodiment of the invention. Grooves  904  and  905  for connectors may be formed at the center of an inlet side connector portion  901  and an outlet side connector portion  903  as illustrated in  FIG. 9  or may be formed in end portions thereof in accordance with a laminated structure of a liquid mixing portion  902 . 
         [0043]      FIG. 10  illustrates a state of an external appearance of a liquid mixing device according to an embodiment of the invention. As illustrated in  FIG. 10 , connector shapes are formed as postprocessing in a state in which an inlet side connector portion  1001 , a liquid mixing portion  1002 , and an outlet side connector portion  1003  are bonded to one another by the above diffusion bonding. In this way, it is possible to provide a highly reliable liquid mixing device that has high pressure resistance and does not cause leakage of a liquid even in a high pressure condition in analysis using a liquid chromatograph. 
         [0044]    Note that the invention is not limited to the above examples and includes various modification examples. For example, the above examples have been described in detail to easily understand the invention, and therefore the invention is not necessarily limited to the examples having all the configurations described above. Further, a part of a configuration of a certain example can be replaced with a configuration of another example, and a configuration of another example can be added to a configuration of a certain example. Further, a configuration of another example can be added to, removed from, or replaced with a part of the configuration of each example. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100  . . . liquid chromatography apparatus 
           101  . . . feed pump 
           102 ,  200  liquid mixing device (mixer) 
           103  . . . sample injection device (autosampler) 
           104  . . . column oven 
           105  . . . detector 
           106  . . . waste liquid 
           107  . . . solvent 
           201 ,  301 ,  401 ,  501 ,  601 ,  701 ,  901 ,  1001  . . . inlet side connector portion 
           202 ,  302 ,  402 ,  502 ,  602 ,  702 ,  902 ,  1002  . . . liquid mixing portion 
           203 ,  303 ,  403 ,  503 ,  603 ,  703 ,  903 ,  1003  . . . outlet side connector portion 
           304 ,  305  . . . seal packing member 
           404 ,  405 ,  504 ,  505 ,  604 ,  605 ,  904 ,  905  . . . groove 
           606 ,  607  . . . sealing member 
           801 - 808  . . . groove shape