Patent Publication Number: US-2021170647-A1

Title: Manufacturing method of liquid ejection head

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a manufacturing method of a liquid ejection head. 
     Description of the Related Art 
     As a liquid ejection head that ejects liquid such as ink from an ejection port and records an image on a recording medium, there is a liquid ejection head of a page wide type that has length corresponding to the width of the recording medium and performs a recording operation on the conveyed recording medium in a state in which the liquid ejection head is fixed to an apparatus main body. The liquid ejection head of the page wide type can simultaneously record many images compared with a liquid ejection head of a serial type that performs a recording operation while moving in the width direction of a recording medium. Therefore, the liquid ejection head of the page wide type is often adopted in a liquid ejection apparatus for which high-speed recording is requested. 
     Japanese Patent Application Laid-Open No. 2018-083349 describes a method of manufacturing a flow path constituting member for supplying liquid to a plurality of ejection modules among members constituting a liquid ejection head of a page wide type. In this method, first, three members constituting a flow path constituting member are independently molded at different locations in a metal mold by injection molding of resin (primary molding). After mold opening, the metal mold is slid to perform alignment of the three members, a mold is clamped again to bring the three members into contact with one another, and melted resin is injected into a contacting portion of three members to join the three members (secondary molding). By adopting such a method, it is possible to highly accurately manufacture a flow path constituting member having a complicated hollow structure such as a liquid flow path on the inside. 
     SUMMARY OF THE INVENTION 
     In the manufacturing method explained above, since the flow path constituting member is a long member corresponding to the width of the recording medium, the number of joining portions during the secondary molding necessarily increases. In order to cope with this problem, it is necessary to increase the number of gates set in the metal mold. However, this leads to an increase in the size of the metal mold, leading to an increase in a molded article. On the other hand, in order to avoid such an increase in the size, it is conceivable to form, in the metal mold, an introduction path (a runner) for guiding resin ejected from the gate to the joining portion. However, the metal mold is complicated by setting the runner. Moreover, in particular, in the case of a long flow path constituting member, a filling property of the resin into the joining portion is deteriorated and a filling failure (shortage) is likely to occur. 
     Therefore, an object of the present disclosure is to provide a manufacturing method of a liquid ejection head that can manufacture a flow path constituting member, which is a resin molded article, with high reliability without causing an increase in the size and complication of a metal mold. 
     In order to achieve the object described above, a manufacturing method of a liquid ejection head of the present disclosure includes manufacturing a flow path constituting member for supplying a liquid to a plurality of an ejection module, the manufacturing a flow path constituting member including using a metal mold which is constituted of a fixed mold and a movable mold, and the ejection module being configured to eject the liquid, the manufacturing a flow path constituting member including: a first step of molding a first member, a second member, and a third member independently at locations different from each other in the metal mold by clamping the metal mold and injecting a resin to an inside of the metal mold, the first member, the second member, and the third member constituting the flow path constituting member; a second step of joining the first member and the second member by injecting a first sealing resin to a contacting portion, the contacting portion is formed by contacting the first member and the second member each other by clamping the metal mold after opening the metal mold and sliding the movable mold to a position at which the first member retained at the movable mold and the second member retained at the fixed mold are opposite to each other; and a third step of joining the second member and the third member by injecting a second sealing resin to a contacting portion, the contacting portion is formed by contacting the second member and the third member each other by clamping the metal mold after opening the metal mold and sliding the movable mold to a position at which the second member retained at the movable mold and the third member retained at the fixed mold are opposite to each other. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are perspective views of a liquid ejection head according to an embodiment. 
         FIGS. 2A, 2B, 2C, 2D, 2E, and 2F  are plan views illustrating front surfaces and rear surfaces of flow path members according to the embodiment. 
         FIG. 3A  is a perspective plan view of a flow path constituting member according to the embodiment. 
         FIG. 3B  is a sectional view of the flow path constituting member according to the embodiment. 
         FIGS. 4A, 4B, and 4C  are perspective views illustrating steps of a manufacturing method of a flow path constituting member according to the embodiment. 
         FIGS. 5A, 5B, and 5C  are sectional views illustrating the steps of the manufacturing method of the flow path constituting member according to the embodiment. 
         FIGS. 6A, 6B, and 6C  are sectional views illustrating the steps of the manufacturing method of the flow path constituting member according to the embodiment. 
         FIGS. 7A and 7B  are sectional views for explaining the manufacturing method according to the embodiment. 
         FIGS. 8A and 8B  are plan views for explaining a secondary molding step according to the embodiment. 
         FIGS. 9A and 9B  are sectional views for explaining the secondary molding step according to the embodiment. 
         FIG. 10  is a plan view for explaining a tertiary molding step according to the embodiment. 
         FIGS. 11A, 11B, and 11C  are sectional views for explaining the tertiary molding step according to the embodiment. 
         FIGS. 12A and 12B  are sectional views for explaining modifications of the tertiary molding step according to the embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present disclosure is explained below with reference to the drawings. However, the embodiment explained below does not limit the scope of the present disclosure. 
       FIGS. 1A and 1B  are perspective views of a liquid ejection head according to an embodiment of the present disclosure. 
     A liquid ejection head  3  is a liquid ejection head of a line type (a page wide type) having length corresponding to the width of a recording medium and includes fifteen recording element substrates  10  arrayed linearly (inline) in the longitudinal direction of the liquid ejection head. The recording element substrates  10  constitute an ejection module  200  in conjunction with a flexible wiring board  40  and are capable of ejecting inks of four colors of cyan (C)/magenta (M)/yellow (Y)/black (K). The liquid ejection head  3  is connected to a liquid supply system of a liquid ejection apparatus (not illustrated) via a liquid connection section  111  of a liquid supply unit  220 . Consequently, the inks of four colors of CMYK are supplied from the liquid supply system of the liquid ejection apparatus to the liquid ejection head  3  and collected in the liquid supply system of the liquid ejection apparatus through the liquid ejection head  3 . In this way, the inks of the colors are capable of circulating between the liquid ejection apparatus and the liquid ejection head  3 . 
     The liquid ejection head  3  includes a flow path constituting member  210  that supports a plurality of ejection modules  200 . The flow path constituting member  210  is constituted from first, second, and third flow path members  50 ,  60 , and  70 , each of which is formed in an elongated rectangular plate shape. The first, second, and third flow path members are stacked one on top of another and joined. The plurality of ejection modules  200  are joined to a joining surface  53  (see  FIGS. 2A to 2F ) of the first flow path member  50  by an adhesive. The flow path constituting member  210  is a member for supplying liquid to the plurality of ejection modules  200  that eject the liquid. That is, the flow path constituting member  210  includes, on the inside, a flow path for distributing ink supplied from the liquid supply unit  220  to the ejection modules  200  and returning the ink, which recirculates from the ejection modules  200 , to the liquid supply unit  220 . The flow path constituting member  210  is fixed to a liquid-ejection-unit supporting section  81  by screwing. 
     It is preferable that the first, second, and third flow path members  50 ,  60 , and  70  have sufficient corrosion resistance against liquid (ink) and are made of a material having a low coefficient of linear expansion. As such a material, a composite material including a resin material as a base material and added with an inorganic filler such as silica particulates or fiber. Examples of the resin material used as the base material include LCP (liquid crystal polymer), PPS (polyphenyl sulfide), PSF (polysulfone), and modified PPE (polyphenylene ether). As dimensions of the first, second, and third flow path members  50 ,  60 , and  70 , as an example, length in the latitudinal direction is approximately 30 mm, length in the longitudinal direction is approximately 260 mm (A4 width) to approximately 350 mm (A3 width) corresponding to a paper width of the liquid ejection head of the page wide type. 
       FIGS. 2A and 2B  are plan views illustrating a front surface and a rear surface of a first flow path member.  FIGS. 2C and 2D  are plan views illustrating a front surface and a rear surface of a second flow path member.  FIGS. 2E and 2F  are plan view illustrating a front surface and a rear surface of a third flow path member. In  FIG. 2A , a joining surface  53 , to which the ejection module  200  is joined, of a first flow path member  50  is illustrated. In  FIG. 2F , a surface, with which the liquid-ejection-unit supporting section  81  is brought into contact, of a third flow path member  70  is illustrated. 
     The first flow path member  50  and a second flow path member  60  are joined such that a surface illustrated in  FIG. 2B  and a surface illustrated in  FIG. 2C  are opposed. When the first and second flow path members  50  and  60  are joined, a plurality of individual flow paths  213  and  214  (see  FIGS. 3A and 3B ) are formed by individual flow path grooves  52  formed in the first flow path member  50  and the second flow path member  60 . The second flow path member  60  and the third flow path member  70  are joined such that a surface illustrated in  FIG. 2D  and a surface illustrated in  FIG. 2E  are opposed. When the second and third flow path members  60  and  70  are joined, eight common flow paths  211  and  212  (see  FIGS. 3A and 3B ) extending in the longitudinal direction of the flow path constituting member  210  are formed by common flow path grooves  62  formed in the second flow path member  60  and common flow path grooves  71  formed in the third flow path member  70 . Specifically, a pair of the common supply flow path  211  and the common collection flow path  212  are formed in the flow path constituting member  210  for each of the colors of the inks. 
     In the third flow path member  70 , a communication port  72  fluidly communicating with the liquid supply unit  220  is formed. A plurality of communication ports  61  are formed in the bottom surfaces of the common flow path grooves  62  of the second flow path member  60 . The communication ports  61  communicate with one end portions of the individual flow path grooves  52  of the first flow path member  50 . Communication ports  51  are formed at the other end portions of the individual flow path grooves  52  of the first flow path member  50 . The communication ports  51  fluidly communicate with the ejection module  200 . Flow paths can be integrated near the center in the latitudinal direction of the flow path constituting member  210  by the individual flow path grooves  52 . 
       FIG. 3A  is a perspective plan view enlarging and illustrating a part of the flow path constituting member and is a view from a side of a joining surface of the first flow path member.  FIG. 3B  is a sectional view taken along an E-E line of  FIG. 3A . 
     In the flow path constituting member  210 , as explained above, the common supply flow paths  211  ( 211   a ,  211   b ,  211   c , and  211   d ) and the common collection flow paths  212  ( 212   a ,  212   b ,  212   c , and  212   d ) extending in the longitudinal direction of the liquid ejection head  3  are provided for each of the colors of the inks. The common supply flow paths  211  of the colors are connected to, via the communication ports  61 , a plurality of individual supply flow paths  213  ( 213   a ,  213   b ,  213   c , and  213   d ) extending in a direction crossing the common supply flow paths  211 . The common collection flow paths  212  of the colors are connected to, via the communication ports  61 , a plurality of individual collection flow paths  214  ( 214   a ,  214   b ,  214   c , and  214   d ) extending in a direction crossing the common collection flow paths  212 . Further, the individual supply flow paths  213  and the individual collection flow paths  214  respectively fluidly communicate with the ejection modules  200  via the communication ports  51 . With such a flow path configuration, it is possible to intensively supply the inks from the common supply flow paths  211  to the recording element substrates  10  located near the center of the flow path constituting member  210  via the individual supply flow paths  213 . It is possible to collect the inks from the recording element substrates  10  to the common collection flow paths  212  via the individual collection flow paths  214 . 
     On a supporting member  30  and the recording element substrate  10  included in the ejection module  200 , flow paths for supplying the inks from the first flow path member  50  to recording elements (not illustrated) provided in the recording element substrate  10  are formed. Further, on the supporting member  30  and the recording element substrate  10 , flow paths for collecting (recirculating) a part or all of the inks supplied to the recording elements to the first flow path member  50  are also formed. In this way, in the liquid ejection head  3  in this embodiment, for each of the colors of the inks, a flow of the ink flowing to the common supply flow paths  211 , the individual supply flow paths  213 , the recording element substrate  10 , the individual collection flow paths  214 , and the common collection flow paths  212  in order is generated. 
     Subsequently, in particular, a manufacturing method of a flow path constituting member, which is a resin molded article, in the manufacturing method of the liquid ejection head in this embodiment is explained with reference to  FIGS. 4A to 7B . First, an overview of the manufacturing method of the flow path constituting member in this embodiment is explained with reference to  FIGS. 4A to 4C .  FIGS. 4A to 4C  are respectively perspective view illustrating steps of the manufacturing method of the flow path constituting member in this embodiment. 
     The flow path constituting member  210  in this embodiment is schematically manufactured by three steps using a metal mold formed from the fixed mold  282  (see  FIGS. 5A to 7B ) and the movable mold  283 . In a primary molding step (a first step), as illustrated in  FIG. 4A , melted resin is ejected into the inside of the metal mold from valve gates  284   a  to  284   c  to independently mold the first, second, and the third flow path members  50 ,  60 , and  70 . In a secondary molding step (a second step), as illustrated in  FIG. 4B , the first flow path member  50  and the second flow path member  60  are brought into contact with each other. Sealing resin (first sealing resin) for secondary molding is injected into a contacting portion of the first flow path member  50  and the second flow path member  60  from a valve gate  285  to join both the members  50  and  60 . In a tertiary molding step (a third step), as illustrated in  FIG. 4C , the second flow path member  60  and the third flow path member  70  are brought into contact with each other. Sealing resin (second sealing resin) for tertiary molding is injected into a contacting portion of the second flow path member  60  and the third flow path member  70  from a valve gate  286  to join both the members  60  and  70 . 
     Subsequently, details of the manufacturing method of the flow path constituting member in this embodiment are explained with reference to  FIGS. 5A to 7B .  FIGS. 5A to 7B  are sectional views illustrating the steps of the manufacturing method of the flow path constituting member in this embodiment and are respectively views from an A direction in  FIGS. 4A to 4C . Note that  FIG. 5A  corresponds to the primary molding step illustrated in  FIG. 4A ,  FIG. 6A  corresponds to the secondary molding step illustrated in  FIG. 4B , and  FIG. 7A  corresponds to the tertiary molding step illustrated in  FIG. 4C . 
     First, as illustrated in  FIG. 5A , a metal mold  280  formed by the fixed mold  282  and the movable mold  283  is clamped. Melted resin is ejected into the inside of the metal mold  280  from the valve gates  284   a  to  284   c . Consequently, the first, second, and third flow path members  50 ,  60 , and  70  are independently formed at different locations in the metal mold  280 . 
     When the primary molding step is completed in this way, as illustrated in  FIG. 5B , the movable mold  283  moves in a direction of an arrow K 1  and the metal mold  280  is opened. At this time, the first flow path member  50  is retained by a slide die  287  provided in the movable mold  283 . The second and third flow path members  60  and  70  are respectively retained by a die  288  (see  FIG. 9B ) and a die  289  (see  FIG. 11C ) provided in the fixed mold  282 . As illustrated in  FIG. 5C , in a state in which the movable mold  283  retains the first flow path member  50 , the movable mold  283  slides in a direction of an arrow K 2  to a position where the first flow path member  50  is opposed to the second flow path member  60 . 
     Subsequently, as illustrated in  FIG. 6A , the movable mold  283  moves in a direction of an arrow K 3  toward the fixed mold  282  and the metal mold  280  is clamped. At this time, the first flow path member  50  and the second flow path member  60  come into contact with each other. The individual flow paths  213  and  214  are formed in a contacting portion of the first flow path member  50  and the second flow path member  60 . Sealing passages in which the sealing resin (the secondary molding resin) for the secondary molding is filled are formed around the contacting portion. Secondary molding resin  291  is injected into the sealing passages from the valve gate  285 , whereby the first flow path member  50  and the second flow path member  60  are joined and integrated. 
     When the secondary molding step is completed in this way, as illustrated in  FIG. 6B , the movable mold  283  moves in the direction of the arrow K 1  again and the metal mold  280  is opened. At this time, the second flow path member  60  is retained by the movable mold  283  together with the integrated first flow path member  50 . As illustrated in  FIG. 6C , in a state in which the movable mold  283  retains the second flow path member  60  via the first flow path member  50 , the movable mold  283  slides in the direction of the arrow K 2  to a position where the second flow path member  60  is opposed to the third flow path member  70  retained by the fixed mold  282 . 
     Subsequently, as illustrated in  FIG. 7A , the movable mold  283  moves in the direction of the arrow K 3  toward the fixed mold  282  and the metal mold  280  is clamped. At this time, the second flow path member  60  and the third flow path member  70  come into contact with each other. The common flow paths  211  and  212  are formed in a contacting portion of the second flow path member  60  and the third flow path member  70 . Sealing passages for filling sealing resin (tertiary molding resin) for tertiary molding are formed around the contacting portion. As explained in detail below, the slide die  289  provided in the fixed mold  282  slides in a direction of an arrow K 4  and a space for injecting the tertiary molding resin is formed. Tertiary molding resin  292  is injected into the sealing passages from the valve gate  286  through this space, whereby the second flow path member  60  and the third flow path member  70  are joined and the integrated flow path constituting member  210  is manufactured. 
     When the tertiary molding step is completed in this way, as illustrated in  FIG. 7B , the movable mold  283  moves in the direction of the arrow K 1  again and the metal mold  280  is opened. At this time, the integrated flow path constituting member  210  moves in the direction of the arrow K 1  in a state in which the flow path constituting member  210  is retained by the movable mold  283 . Thereafter, the slide die  287  of the movable mold  283  slides in a direction of an arrow K 5  and the retaining of the first flow path member  50  is released. The flow path constituting member  210  is pulled out in a direction of an arrow K 6  and removed from the movable mold  283 . 
     In this way, with the manufacturing method in this embodiment, the secondary molding resin  291  and the tertiary molding resin  292  are respectively injected from different positions of the fixed mold  282 . Specifically, the secondary molding resin  291  is injected from the valve gate  285 , which is provided in the fixed mold  282 , in a position opposed to the second flow path member  60 . The tertiary molding resin  292  is injected from the valve gate  286 , which is provided in the fixed mold  282 , in a position opposed to the third flow path member  70 . Consequently, it is unnecessary to densely dispose gates in the fixed mold of the metal mold or dispose the gates via a runner. As a result, it is possible to avoid an increase in the size and complication of the metal mold. In particular, it is also possible to improve a filling property of the tertiary molding resin. 
     Incidentally, in molding of thermoplastic resin, when a metal mold is removed from a molded article, the temperature of the metal mold is higher than an environment temperature around the metal mold. Thereafter, when the metal mold is left untouched, the temperature of the metal mold drops to the environment temperature. However, at this time, the molded article is not fixed to the metal mold. Cooling of the molded article advances while residual stress being released. Accordingly, deformation such as a bend or undulation tends to occur in a molded article and particularly conspicuously tends to occur in a long molded article. For example, when deformation such as a bend or undulation occurs in a flow path constituting member, it is likely that relative position accuracy of a plurality of ejection modules is deteriorated when the ejection modules are bonded along the deformation in order to secure high bonding reliability. Consequently, there is a concern about deterioration in image quality. On the other hand, in order to secure the relative position accuracy of the plurality of ejection modules, it is necessary to adjust an amount of adhesive for each of the ejection modules according to deformation of the flow path constituting member. Consequently, it is likely that high bonding reliability cannot be secured and an ink leak occurs. 
     In contrast, in this embodiment, as illustrated in  FIGS. 5A to 7A , in the primary molding step to the tertiary molding step, the first flow path member  50  is retained in a state in which a joining surface  53 , to which the ejection module  200  is joined, is in contact with the movable mold  283 . Consequently, it is possible to increase a cooling time of the first flow path member  50  in the metal mold  280 . It is possible to suppress deformation such as a bend or undulation to obtain the flat joining surface  53 . It is also advantageous to suppress deformation of the joining surface  53  during a molding step that the first flow path member  50  is surely retained by the slide die  287  and temperature control for the movable mold  283  is easy because a heat source such as a valve gate is absent. In this way, in this embodiment, it is possible to achieve both of the high bonding reliability of the flow path constituting member  210  and the ejection module  200  and the securing of the relative position accuracy of the plurality of ejection modules  200 . 
     Subsequently, details of the secondary molding step in the manufacturing method of the flow path constituting member in this embodiment are explained with reference to  FIGS. 8A, 8B, 9A, and 9B .  FIG. 8A  is a plan view of the second flow path member and is a view illustrating an inflow route of the secondary molding resin.  FIG. 8B  is an enlarged view of a region surrounded by a broken line in  FIG. 8A .  FIG. 9A  is a sectional view taken along an F-F line in  FIG. 8B .  FIG. 9B  is a sectional view taken along a G-G line in  FIG. 8B . Note that, in  FIGS. 9A and 9B , the first flow path member and the second flow path member are illustrated. However, in  FIGS. 8A and 8B , illustration of the first flow path member is omitted for simplicity. 
     Five valve gates  285  for injecting the secondary molding resin are provided along the longitudinal direction of the second flow path member  60 . In the second flow path member  60 , sealing grooves  63  communicating from the valve gates  285  are formed. The sealing grooves  63  constitute, in conjunction with the first flow path member  50 , sealing passages in which the secondary molding resin is filled. Note that, in this embodiment, all the valve gates  285  are provided at one end portion in the latitudinal direction of the second flow path member  60 . A last filling section  66  to which the secondary molding resin flows out from the sealing passages is provided at the other end portion in the latitudinal direction of the second flow path member  60 . Consequently, since the secondary molding resin flows in one direction from the valve gates  285  to the last filling section  66 , it is possible to effectively allow gas in the secondary molding resin to escape. It is possible to obtain high joining reliability by suppressing occurrence of a filling failure. Further, since the last filling section  66  is intensively provided at the other end portion, simply by confirming the end portion, it is possible to easily inspect presence or absence of final filling of the secondary molding resin. A direction in which the secondary molding resin flows (a direction in which the sealing grooves  63  extend) is inclined with respect to the latitudinal direction of the second flow path member  60 . Therefore, compared with when the direction is parallel to the latitudinal direction, joining strength is improved because a projection area of the joining portion increases. It is possible to obtain higher joining reliability. In contrast, a direction in which the last filling section  66  extends is substantially parallel to the latitudinal direction of the second flow path member  60 . However, the vicinity of the last filling section  66  is unrelated to the joining of the flow path members  50  and  60 . Accordingly, after sealing of the circumferences of the individual flow paths  213  and  214  is completed, the secondary molding resin reaches the last filling section  66  at a shortest distance. It is possible to obtain effects such as a reduction of a resin capacity and a reduction of a molding cycle. 
     A wall section constituting the fine common flow path grooves  62  of the second flow path member  60  is thin. Therefore, it is likely that the wall section is deformed and broken by heat and pressure of the secondary molding resin  291  and the secondary molding resin  291  flows into the common flow path grooves  62 . However, during the secondary molding step, as illustrated in  FIG. 9B , the second flow path member  60  is joined to the first flow path member  50  in a state in which the second flow path member  60  is retained by the die  288  of the fixed mold  282 . Consequently, the thin wall section of the second flow path member  60  can be firmly pressed (backed up) by the die  288  of the fixed mold  282 . Even if the heat and the pressure by the secondary molding resin  291  are applied to the wall section, it is possible to suppress a leak of the resin. 
     Note that, as long as the secondary molding resin uniformly flows over the entire contacting portion of the flow path members  50  and  60 , the number of valve gates  285  and the disposition of the sealing grooves  63  are not limited to the illustrated examples and can be set as appropriate according to the shape of the individual flow paths  213  and  214 , performance of a molding machine in use, and the like. 
     Subsequently, details of the tertiary molding step in the manufacturing method of the flow path constituting member in this embodiment are explained with reference to  FIGS. 10 to 12B .  FIG. 10  is a plan view of the third flow path member and is a view illustrating an inflow route of tertiary molding resin.  FIGS. 11A and 11B  are sectional views taken along an H-H line in  FIG. 10 .  FIG. 11C  is a sectional view taken along a J-J line in  FIG. 10 .  FIGS. 12A and 12B  are sectional views illustrating modifications of the tertiary molding step in this embodiment and are respectively views corresponding to  FIGS. 11A and 11B . Note that, in  FIG. 10 , illustration of the second flow path member is omitted for simplicity. 
     Four valve gates  286  for injecting the tertiary molding resin are provided along the longitudinal direction of the third flow path member  70 . As explained above, the slide die  289 , which is a part of a die member of the fixed mold  282 , is provided near the valve gates  286 . The slide die  289  is capable of sliding between a closed position illustrated in  FIG. 11A  and an open position illustrated in  FIG. 11B . During the tertiary molding step, the slide die  289  slides from the closed position to the open position, whereby a space communicating with the valve gate  286  is formed. On the other hand, in the third flow path member  70 , sealing grooves  73  communicating with the space formed in this way are formed. The sealing grooves  73  constitute, in conjunction with the second flow path member  60 , sealing passages in which the tertiary molding resin is filled. With such a configuration, the valve gate  286  can be disposed substantially in the center in the latitudinal direction of the third flow path member  70 . It is possible to fill the tertiary molding resin in a well-balanced manner. The space formed by the slide die  289  of the fixed mold  282  extends in the latitudinal direction of the third flow path member  70 . The sealing passages (the sealing grooves  73 ) for filling the tertiary molding resin extend in the longitudinal direction of the third flow path member  70 . Therefore, the tertiary molding resin ejected from the valve gate  286  flows in the latitudinal direction of the third flow path member  70  first and is thereafter filled in the longitudinal direction. As a result, it is possible to substantially simultaneously fill, in a well-balanced manner, a plurality of sealing passages extending in the longitudinal direction. 
     The sealing passages in which the tertiary molding resin is filled are terminated as gas escape holes  76 , for example, at the end portion and the center in the longitudinal direction of the third flow path member  70 . However, a gas vent communicating with the gas escape holes  76  is formed in the die member of the fixed mold  282  that retains the third flow path member  70 . Consequently, it is possible to cause the sealing passages to communicate with the outside. It is possible to fill the tertiary molding resin in the sealing passages without causing gas to remain in the tertiary molding resin. 
     Note that, in the sealing passages in which the tertiary molding resin is filled, a risk of the tertiary molding resin leaking from the sealing passages is high in a part where the pressure of the tertiary molding resin is high, specifically, near the valve gate  286 , in particular, in a part adjacent to the space formed by the slide die  289 . In such a part, as illustrated in  FIG. 11C , the sealing passages face a die  290  of the fixed mold  282  that retains the third flow path member  70 . In addition, in portions among the sealing passages (the sealing grooves  73 ) in the die  290  of the fixed mold  282 , projections  293  extending in parallel to the sealing passages are formed to project toward the third flow path member  70 . Consequently, it is possible to suppress deformation of the third flow path member  70  by the pressure of the tertiary molding resin, a leak of the tertiary molding resin by the deformation, and the like. Note that, instead of the projections  293  being formed in the die  290  and recesses being formed in the third flow path member  70 , the formation of the projections  293  and the formation of the recesses may be opposite. However, from the viewpoint of suppressing deformation of the third flow path member  70 , it is preferable that the projections  293  are formed in the die  290  as in this embodiment. In order to improve the strength of the third flow path member  70  in a part where the pressure of the tertiary molding resin is high and suppress deformation, a portion adjacent to the valve gate  286  in the third flow path member  70  may be formed thicker than the other portions. 
     A method of forming the space into which the tertiary molding resin is injected is not limited to the method explained above. For example, as illustrated in  FIGS. 12A and 12B , the slide die  289  may be slid in an opening and closing direction of the metal mold  280  to form the space. Note that, whereas a setting position of the valve gate  286  is the center in the latitudinal direction of the third flow path member  70  in a configuration illustrated in  FIGS. 11A and 11B , the setting position is the end portion in the latitudinal direction in a configuration illustrated in  FIGS. 12A and 12B . Accordingly, it is preferable to adopt the configuration illustrated in  FIGS. 11A and 11B  when a filling balance of the tertiary molding resin is considered. However, in both the configurations, the tertiary molding resin is fed into the space formed by the slide die  289  of the fixed mold  282 . The slide die  289  of the fixed mold  282  at this time has relatively high temperature because of thermal influence of a hot runner. Accordingly, the tertiary molding resin  292  ejected from the valve gate  286  is filled without being suddenly cooled. The resin easily spreads to the entire sealing passages. As a result, a filling property of the resin is satisfactory. 
     Note that, in the illustration in the embodiment explained above, the flow path constituting member is constituted from the three members (the first to third flow path members). However, the present disclosure is not limited to this and is also applicable when the flow path constituting member is constituted from four or more members. The present disclosure is not limited to only the flow path constituting member of the liquid ejection head and is widely applicable to a long member mounted on an inkjet recording apparatus (a liquid ejection apparatus). 
     According to the present disclosure, it is possible to manufacture a flow path constituting member, which is a resin molded article, with high reliability without causing an increase in the size and complication of a metal mold. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2019-219561, filed Dec. 4, 2019, which is hereby incorporated by reference herein in its entirety.