Patent Publication Number: US-2019184085-A1

Title: End cap of dialyzer and fabricating method thereof, and dialyzer

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application serial no. 201711362480.6, filed on Dec. 18, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a dialyzer, and more particularly, to an end cap of a dialyzer and a fabricating method thereof. 
     Description of Related Art 
     Patients with renal failure would experience their kidney cannot filter waste accumulating in their body, such as protein-digested products, urea, creatinine, phosphate, or vitamin B12, and therefore require dialysis to compensate for the natural excretory function of the kidneys. A common dialysis includes, for instance, purifying the blood of the patients using a dialyzer to remove excess water and toxins from the blood. 
     SUMMARY OF THE INVENTION 
     The invention provides an end cap of a dialyzer and a fabricating method thereof, thereby effectively enabling reduction of production process and processing time. 
     The invention provides a dialyzer having improved liquid tightness. 
     The invention provides an end cap of a dialyzer including a main body and a sealing element. The main body has a blood port. The sealing element is integrally connected on an inner wall of the main body. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the inner wall of the main body can have a notch, a latch, a snap, or an inner thread. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the material of the main body is, for instance, polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polysulfone (PSU), polyethylene (PE), polyacrylonitrile (PAN), Nylon (such as Nylon 6), acrylonitrile butadiene styrene (ABS), or a combination thereof. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the material of the sealing element is, for instance, a rubber or an elastomer. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the elastomer is, for instance, a thermoplastic elastomer (TPE) or a thermoset elastomer. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the main body and the sealing element are integrally connected via, for instance, a double injection molding method. 
     According to an embodiment of the invention, in the end cap of the dialyzer, the shrinkage rate difference between the main body and the sealing element is, for instance, 1% or less. 
     The invention provides a fabricating method of an end cap of a dialyzer including the following steps. The main body and the sealing element are integrally formed using a double injection molding method. The main body has a blood port. The sealing element is integrally connected on an inner wall of the main body. 
     According to an embodiment of the invention, in the fabricating method of the end cap of the dialyzer, the main body can be injection-molded first, and then the sealing element is injection-molded. The softening point of the main body is, for instance, higher than the softening point of the sealing element. 
     According to an embodiment of the invention, in the fabricating method of the end cap of the dialyzer, the sealing element can be injection-molded first, and then the main body is injection-molded. The softening point of the sealing element is, for instance, higher than the softening point of the main body. 
     The invention provides a dialyzer including a housing, a sealant, a plurality of hollow fiber membranes, and two end caps. The housing has two openings opposite to each other. A dialysate inlet and a dialysate outlet are disposed on the housing. The sealant seals the two openings. The hollow fiber membranes disposed in the housing are secured by the sealant. 
     The end caps respectively cover two ends of the housing. Each of the end caps includes a main body and a sealing element. The main body has a blood port. The sealing element is integrally connected on an inner wall of the main body. 
     According to an embodiment of the invention, in the dialyzer, the material of the housing is, for instance, polypropylene (PP), polybutylene, polyethylene (PE), or a combination thereof. 
     According to an embodiment of the invention, in the dialyzer, the combining method of the housing and the end caps can include an engagement of corresponding recess and protrusion structures via jointing, clipping or screwing. 
     According to an embodiment of the invention, in the dialyzer, the outer wall of the housing can have a latch, a snap, a notch, or an external thread, and the inner wall of the main body can have a notch, a latch, a snap, or an inner thread correspondingly. 
     According to an embodiment of the invention, in the dialyzer, the combining method of the housing and the two end caps can further include performing ultrasonic welding after the jointing, clicking or screwing of the housing and the respective end caps. 
     According to an embodiment of the invention, in the dialyzer, the material of the main body is, for instance, polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polysulfone (PSU), polyethylene (PE), polyacrylonitrile (PAN), Nylon, acrylonitrile butadiene styrene (ABS), or a combination thereof. 
     According to an embodiment of the invention, in the dialyzer, the material of the sealing element is, for instance, a rubber or an elastomer. 
     According to an embodiment of the invention, in the dialyzer, the elastomer is, for instance, a thermoplastic elastomer (TPE) or a thermoset elastomer. 
     According to an embodiment of the invention, in the dialyzer, the forming method of the main body and the sealing element is, for instance, a double injection molding method. 
     According to an embodiment of the invention, in the dialyzer, the shrinkage rate difference between the main body and the sealing element is, for instance, 1% or less. 
     Based on the above, in the end cap of the dialyzer and the fabricating method thereof provided in the invention, the main body and the sealing element are integrally formed in a single piece. Therefore, the production process can be simplified, and production time can be effectively reduced. Moreover, in the dialyzer provided in the invention, since the sealing element is accurately positioned and integratedly secured on the main body beforehand, the dialyzer that includes the end caps and the housing combined together can have good liquid tightness. The conventional procedure of placing an additional sealing element in a structural gap or groove formed in an end cap is no longer required. As a result, the production steps and production time of the dialyzer can be effectively reduced. 
     In order to make the aforementioned features and advantages of the disclosure more comprehensible, embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  is a perspective view of an end cap of a dialyzer according to an embodiment of the invention. 
         FIG. 1B  is a perspective view of the end cap of the dialyzer shown in  FIG. 1A  from another viewing angle. 
         FIG. 2  is a perspective view of a dialyzer according to an embodiment of the invention, of which a housing and end caps are not combined. 
         FIG. 3  is a perspective view of the dialyzer shown in  FIG. 2 , of which the housing and the end caps are combined. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1A  is a perspective view of an end cap of a dialyzer according to an embodiment of the invention.  FIG. 1B  is a perspective view of the end cap of the dialyzer shown in  FIG. 1A  from another viewing angle. 
     Referring to both  FIG. 1A  and  FIG. 1B , an end cap  100  of a dialyzer includes a main body  102  and a sealing element  104 . Since the main body  102  and the sealing element  104  are integrally formed in a single piece, the production process of the end cap could be simplified, thereby effectively reducing the production time. 
     For instance, the end cap  100  can be fabricated via a double injection molding method to integrally form an integrated single-piece of the main body  102  and the sealing element  104 . In the double injection molding process, the shrinkage rates of the selected materials are respectively between 0.2% and 5%, and the difference in the shrinkage rate (i.e., shrinkage rate difference) between the two materials respectively used in the first injection molding and the second injection molding can be 0% to 4.8%. In an embodiment, the difference in the shrinkage rate between the main body  102  and the sealing element  104  can be 1% or less, and further can be 0.6% or less, such as 0.4%, so as to avoid a decrease in interface strength of the main body  102  and the sealing element  104 . During the double injection molding process, the materials of the main body  102  and the sealing element  104  undergo the respective injection molding, and the interface strength of the main body  102  and the sealing element  104  would be lessened with a huge difference in the shrinkage rate between the chosen materials. In the present embodiment, the definition of the shrinkage rate is the size difference between the mold cavity and the molded product at room temperature, which is then divided by the size of the mold cavity, wherein the shrinkage rate is defined by the thermal expansion and contraction as well as molding conditions of the materials themselves. 
     In the double injection molding process, the main body  102  can be injected first, and then the sealing element  104  is injected, wherein the softening point of the main body  102  might be higher than the softening point of the sealing element  104 . Accordingly, the profile of the main body  102  injected first is not deformed because of a melting washout phenomenon. Moreover, the melting temperature of the main body  102  is, for instance, higher than the melting temperature of the sealing element  104 . Specifically, the fabricating method of the end cap  100  can include, but not be limited thereto, the following steps. The material of the main body  102  is heated to a molten state, and the molten material is then injection-molded to form the main body  102 . The main body  102  is placed in another mold, and a secondary injection molding is performed to form the sealing element  104 . The secondary injection molding could be implemented by heating the material of the sealing element  104  to a molten state, and then injection-molding the molten material on the main body  102  and completing the engagement of the two materials at the same time. Therefore, a molten bonding layer  103  is further formed at the junction between the main body  102  and the sealing element  104 . In an embodiment, the molten bonding layer  103  could be a heterojunction of the main body  102  and the sealing element  104 , and the material thereof includes the material of the main body  102 , the material of the sealing element  104 , or a mixture thereof. The molten bonding layer  103 , for instance, combines the main body  102  and the sealing element  104  via the viscosity of at least one of the molten materials or chemical bonding, so as to provide an integrated one-piece structure. 
     In another embodiment, in the double injection molding process, the sealing element  104  can be injected first, and then the main body  102  is injected, wherein the softening point of the sealing element  104  is, for instance, higher than the softening point of the main body  102 . Therefore, the profile of the sealing element  104  injected first is not deformed by a melting washout phenomenon. Specifically, the fabricating method of the end cap  100  can include, but not be limited thereto, the following steps. The material of the sealing element  104  is heated to a molten state, and then the molten-state material is injection-molded to form the sealing element  104 . The sealing element  104  is placed in another mold, and a secondary injection molding is performed to form the main body  102 . The secondary injection molding could be implemented by heating the material of the main body  102  to a molten state, and then injection-molding the molten material on the sealing element  104  and completing the combination of the two materials at the same time. It is noted that the end cap  100  integrally formed in a single process, i.e., double injection molding, could facilitate the improved liquid tightness of the dialyzer using the same, while the production procedure and cost are reduced. 
     In contrast, in case a sealing ring, e.g., an O-ring, is not integrally formed with an end cap by double injection molding, the end cap would be designed to have an annular groove or a trapezoidal platform for accommodating the separate sealing ring to avoid blood leakage. The annular groove or trapezoidal platform is generally larger in dimensions than the O-ring to be placed thereinto, so that a gap exists between the end cap and the O-ring, thereby impacting the liquid tightness of the dialyzer. When the dialyzer having the end caps with the separate O-rings is utilized in hemodialysis, the ineffectiveness of the dialysis or poor dialyzing effect would occur owing to the deviation of the blood flow rate (QB) resulted from the varied pressure difference within the dialyzer. In addition, the arrangement of the separate O-rings would lead to extra space laid between the tubular housing and end caps of the dialyzer, and therefore, the yield would be reduced because of the increasing mis-positioning of the O-rings. Thus, the dialyzer without the integrally-formed end caps would suffer the poor dialyzing effect and lower liquid tightness. 
     Referring to  FIG. 1A  and  FIG. 1B , the main body  102  has a blood port  106 . The blood port  106  can be used as the blood input or blood output of the dialyzer. The inner wall of the main body  102  can have at least one notch, latch, snap (e.g., snap hook), or inner thread, each of which respectively functions as a recess or protrusion structure for the engagement. The main body  102  and the notch, the latch, the snap, or the inner thread can be integrally formed. The main body  102  can be combined with the tubular housing of the dialyzer via the engagement of the notch, the latch, the snap, or the inner thread on the inner wall of the main body  102  with the corresponding latch, snap, notch, or external thread on the outer wall of the housing. In the present embodiment, the inner wall of the main body  102  is exemplified by having a plurality of notches  108 . The material of the main body  102  is, for instance, a hard material such as polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polysulfone (PSU), polyethylene (PE), polyacrylonitrile (PAN), Nylon, acrylonitrile butadiene styrene (ABS), or a combination thereof. 
     The sealing element  104  is integrally connected on the inner wall of the main body  102 , instead of supplied separately. The sealing element  104  is, for instance, a sealing ring. The material of the sealing element  104  is, for instance, a soft material such as a rubber or an elastomer. The elastomer could be a thermoplastic elastomer (TPE), such as thermoplastic polyurethane (TPU), thermoplastic vulcanizate (TPV), or thermoplastic polyolefin (TPO). In an embodiment, the elastomer could be a thermoset elastomer, e.g., silicone, epoxy resin, or a combination thereof. 
     In the above end cap  100  of the dialyzer and the fabricating method thereof, since the main body  102  and the sealing element  104  are integrally formed in a single piece, the production process and time of the end cap  100  can be effectively reduced. 
       FIG. 2  is a perspective view of a dialyzer according to an embodiment of the invention, of which the housing and the end caps are not combined.  FIG. 3  is a perspective view of the dialyzer of  FIG. 2 , of which the housing and the end caps are combined. 
     Referring to  FIG. 1A ,  FIG. 1B ,  FIG. 2 , and  FIG. 3 , a dialyzer  10  includes a housing  110 , a sealant  112 , a plurality of hollow fiber membranes  114 , and two end caps  100 . The housing  110  has an opening  116  and an opening  118  opposite to each other that are, for instance, hollow tubular structures housing the hollow fiber membranes  114  therein. A dialysate inlet  120  and a dialysate outlet  122  are disposed on the housing  110 , wherein the dialysate inlet  120  is, for instance, close to the opening  116 , and the dialysate outlet  122  is, for instance, close to the opening  118 . The outer wall of the housing  110  can have at least one latch, snap (e.g., snap hook), notch, or external thread. The housing  110  and the latch, the snap, the notch, or the external thread can be integrally formed. In the present embodiment, the outer wall of the housing  110  is exemplified by having latches  124 . The material of the housing  110  is, for instance, polypropylene, polybutylene, polyethylene, or a combination thereof. 
     The sealant  112  seals the opening  116  and the opening  118  and secures the hollow fiber membranes  114  in the housing  110 . Moreover, the dialysate can flow into the housing  110  via the dialysate inlet  120 , and flow through a space defined by the sealant  112  located at the two ends of the housing  110 , and then flow out of the housing  110  via the dialysate outlet  122 . The material of the sealant  120  could be potting compounds such as polyurethane (PU). 
     The hollow fiber membranes  114  disposed in the housing  110  are secured by the sealant  112 . The openings at the two ends of the hollow fiber membranes  114  might not be covered or blocked by the sealant  112 , and therefore blood can flow into the hollow fiber membranes  114  through the opening at one end and then flow out through the opening at the other end. The hollow fiber membranes  114  are provided with permeaselectivity and could be semi-permeable membranes. The material of the hollow fiber membranes  114  is, for instance, cellulose acetate, polysulfone (PSU), polyethersulfone (PES), or polymethylmethacrylate (PMMA). In the present embodiment, to increase the compatibility between the hollow fiber membranes  114  and the human body, the hollow fiber membranes  114  can further include a hydrophilic polymer in addition to the main components above. The hydrophilic polymer is, for instance, poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), poly(ethylene oxide) (PEO), poly(ethylenimine) (PEI), or poly(acrylate) (PAA). In the present embodiment, the hollow fiber membranes  114  could be prepared by dry-wet spinning. The invention is not limited to the exemplary hollow fiber membranes  114  shown in  FIG. 2  and  FIG. 3 , and thus, those having ordinary skill in the art can adjust the quantity of the hollow fiber membranes  114  as needed. In an embodiment, the quantity of the hollow fiber membranes  114  can be 7000 to 12000. 
     The end caps  100  respectively cover the two ends of the housing  110 . Each of the end caps  100  includes the main body  102  with the blood port  106  and the sealing element  104 . The sealing element  104  is integrally connected on the inner wall of the main body  102 . Moreover, the two blood ports  106  of the respective end caps  100  can be used as the blood inlet and the blood outlet. In the present embodiment, the blood port  106  as the blood outlet can be set close to the dialysate inlet  120 , and the other blood port  106  as the blood inlet can be set close to the dialysate outlet  122 , such that the flow directions of the blood and the dialysate in the tube are opposite. As a result, a better dialysis effect can be obtained, but the invention is not limited thereto. 
     The combining method of the housing  110  and the end caps  100  can include jointing, clipping or screwing. In an embodiment, the housing  110  and the end caps  100  could be combined by engaging the corresponding recess and protrusion structures respectively configured on the housing  110  and end cap  100 . When the housing  110  and the end caps  100  are engaged together, assembly time can be reduced, and automated assembly can be facilitated. 
     For instance, the outer wall of the housing  110  can have a latch, a snap, a notch, or an external thread, and the inner wall of the main body  102  can have a notch, a latch, a snap, or an inner thread. The cross-section shapes of the latch and the notch can be, for instance, polygons (such as triangles or rectangles) or circles, but the invention is not limited thereto, and as long as the cross-section shapes of the latch and the notch are matching and allow the latch and the notch to be clicked together, the shapes are within the scope of the invention. 
     In an embodiment, when the outer wall of the housing  110  has a latch or a snap, the inner wall of the main body  102  can have a notch corresponding to the latch or the snap of the housing  110 , such that the housing  110  and the end caps  100  can be positioned and engaged together. Moreover, when the outer wall of the housing  110  has a notch and the inner wall of the main body  102  has a latch or a snap corresponding to the notch of the housing  110 , a similar combining effect can also be achieved. 
     In another embodiment, when the outer wall of the housing  110  has an external thread, the inner wall of the main body  102  can have an inner thread corresponding to the outer thread of the housing  110 , such that the housing  110  and the end caps  100  can be screwed together. 
     In the present embodiment, the combining method of the housing  110  and the end caps  100  is exemplified by the engagement of the corresponding recesses and protrusions. For instance, the outer wall of the housing  110  can have a latch  124 , and the inner wall of the main body  102  can have a notch  108 , and therefore the housing  110  and the end caps  100  can be engaged together via the latch  124  and the notch  108 . 
     Moreover, the combining method of the housing  110  and the end caps  100  can include performing ultrasonic welding after the jointing, clipping or screwing between the housing  110  and the end caps  100 , so as to further increase the liquid tightness of the dialyzer  10 . 
     The material, fabricating method, and efficacy of the end caps  100  are described in detail in the embodiments above and are therefore not repeated herein. In the dialyzer  10 , since the sealing element  104  is accurately positioned and integratedly secured on the main body  102 , additional procedure of placing a separate sealing element in a corresponding groove or gap of the end cap can be omitted. As a result, the production steps and production time of the dialyzer  10  can be effectively reduced. 
     Based on the above, in the end cap of the dialyzer, the fabricating method thereof, and the dialyzer according to the embodiments, the main body and the sealing element are integrally formed in a single piece. Thus, the production process of the end cap and the dialyzer can be simplified, and the production time thereof can be effectively reduced. 
     Although the invention has been described with reference to the above embodiments, it will be apparent to one of ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention is defined by the attached claims not by the above detailed descriptions.