CN219462091U

CN219462091U - Hemodialysis adsorber

Info

Publication number: CN219462091U
Application number: CN202223498921.4U
Authority: CN
Inventors: 李井龙; 牟倡骏; 于亚楠; 曲佳伟; 丛慧; 李祥鹏; 王晶
Original assignee: Shandong Weigao Blood Purification Products Co Ltd
Current assignee: Shandong Weigao Blood Purification Products Co Ltd
Priority date: 2022-12-15
Filing date: 2022-12-15
Publication date: 2023-08-04
Anticipated expiration: 2032-12-15

Abstract

The utility model discloses a hemodialysis adsorber, which relates to the technical field of blood purification and comprises the following components: a housing having a blood inlet and a blood outlet formed in a side portion thereof; the end covers are arranged at two ends of the shell, and are respectively provided with a dialysate inlet and a dialysate outlet; an adsorption resin member provided on the outer periphery of the hollow fiber membrane; a plurality of tubular hollow fiber membranes uniformly penetrate through the inner cavity of the shell; the two ends of the hollow fiber membrane are sealed in the shell through sealing glue, blood flows on the outer surface of the hollow fiber membrane, dialysate flows in the inner cavity of the hollow fiber membrane, and the blood and the dialysate flow in opposite directions. The device can meet the requirement of the large molecular toxin clearance capability and simultaneously remove the small molecular toxin so as to effectively make up the defect that the absorber and the dialyzer are used in series.

Description

Hemodialysis adsorber

Technical Field

The utility model relates to the technical field of blood purification, in particular to a hemodialysis adsorber.

Background

With the rapid development of the blood purification industry, the further amplification of the market capacity of the dialysis treatment and the continuous development of the clinical application field of the blood adsorption technology, the market capacity of the blood adsorption is huge and the prospect is unlimited. Wherein, the blood adsorption is a blood purification treatment method for leading the blood of a patient from the body into an extracorporeal circulation system and removing toxic substances, medicines and metabolites through the adsorption effect of an adsorbent in an adsorber. Clinical practice proves that the blood has the strongest ability of adsorbing and removing macromolecular toxins and protein-bound toxins. Therefore, it is widely used for acute drug and poison poisoning, liver diseases, inflammatory diseases, rheumatic immune diseases, nervous system diseases, hematopathy, intractable hypertension, drug poisoning, drug withdrawal, psoriasis, pemphigus and other diseases.

Blood adsorption technology is very excellent in removing macromolecular toxins and protein-bound toxins, but is quite inferior in removing small molecular toxins in renal failure patients, so that in order to improve the small molecular removal capacity, a mode of using a blood perfusion device and a dialyzer in series is often used for treatment clinically. However, this mode has several drawbacks: 1. the blood perfusion device can increase the removal of the middle and large molecular toxins, the blood flow of the blood perfusion device is generally less than 150ml/min, the blood dialyser can increase the removal rate of the middle and small molecular toxins, the blood flow of the blood perfusion device is generally more than 200ml/min, and the flow of blood flowing into the dialyser from the perfusion device can not meet the flow requirement of the dialyser after the blood perfusion device is used in series with the dialyser, so that the endotoxin removal capacity of the dialyser is reduced; 2. the serial connection of the blood perfusion device and the dialyzer can cause the serial connection structure to increase the volume of the device and the length of the pipeline, so that the residual quantity of blood in the extracorporeal device is too large and too long, and the hypotension of partial patients is easily caused; 3. the cost is high, and the popularization is difficult; 4. the operation is complicated, and the working pressure of nursing staff is high.

In summary, how to satisfy the clearance capability of macromolecular toxins and simultaneously remove small molecular toxins, and effectively make up the defect of serial connection of an adsorber and a dialyzer is a problem to be solved by those skilled in the art.

Disclosure of Invention

Therefore, the utility model aims to provide the hemodialysis adsorber, which can meet the removal capacity of macromolecular toxins and simultaneously remove micromolecular toxins so as to effectively overcome the defect that the adsorber and a dialyzer are used in series.

In order to achieve the above object, the present utility model provides the following technical solutions:

a hemodialysis adsorber comprising:

a housing having a blood inlet and a blood outlet formed in a side portion thereof;

the end covers are arranged at two ends of the shell, and the two end covers are respectively provided with a dialysate inlet and a dialysate outlet;

an adsorption resin member provided on the outer periphery of the hollow fiber membrane;

the hollow fiber membranes uniformly penetrate through the inner cavity of the shell;

the two ends of the hollow fiber membrane are sealed in the shell through sealing glue, blood flows on the outer surface of the hollow fiber membrane, dialysate flows in the inner cavity of the hollow fiber membrane, and the blood and the dialysate flow in opposite directions.

Preferably, the blood inlet and the blood outlet are provided on the same side.

Preferably, the blood inlet and the blood outlet are arranged on opposite sides and symmetrically distributed relative to the central axis of the shell.

Preferably, the sealing device further comprises sealing rings arranged at two ends of the inner cavity of the shell, the inner wall of the end cover and the surface of the sealing glue are attached to the sealing rings, and the end parts of the hollow fiber membranes are located in the inner ring space of the sealing rings.

Preferably, the adsorption resin member is provided on both an inner peripheral portion of the blood outlet and an inner peripheral portion of the blood inlet.

Preferably, the volume of the adsorption resin member is 100mL-800mL.

Preferably, the pore diameter of the membrane surface of the hollow fiber membrane is 1nm-6nm, the inner diameter of membrane wires of the hollow fiber membrane is 180-220 μm, and the thickness of the membrane wires of the hollow fiber membrane is 35-50 μm.

Preferably, the blood inlet and the blood outlet are both provided with filter screens.

Preferably, the end cap and the housing are both polycarbonate/polypropylene alloy pieces.

Preferably, the sealing glue is a polyurethane material piece.

When the hemodialysis adsorber provided by the utility model is used, the sealing glue can effectively separate the dialysate from the blood, and the dialysate is prevented from directly contacting with the blood. Therefore, the dialysate can enter the hollow fiber membrane through the dialysate inlet of the end cover, finally flows out from the dialysate outlet of the end cover, and the blood can sequentially pass through the blood inlet, the inner cavity of the shell and the blood outlet. In the flowing process, blood can flow on the outer surface of the hollow fiber membrane, dialysate can flow in the inner cavity of the hollow fiber membrane, and the blood and the dialysate flow, so that the mode that the blood can only flow in the hollow fiber membrane in the traditional sense is broken. Meanwhile, the phenomenon of bias flow generated by the dialysate during use is avoided, so that the adequacy of dialysis is improved, and the defect that the absorber and the dialyzer are used in series is overcome.

When the dialysate flows through the hollow fiber membrane, the hollow fiber membrane is distributed uniformly in the shell, so that the flow of the dialysate in the hollow fiber membrane is more uniform than that in the outside of the hollow fiber membrane, and meanwhile, the contact area of the blood and the dialysate on the surface of the hollow fiber membrane is more uniform, thereby being beneficial to the substance exchange between the blood and the dialysate. In addition, the dialysate flows in the hollow fiber membranes which are uniformly distributed, so that the phenomenon of turbulence generated when the dialysate flows outside the hollow fiber membranes can be avoided, the dialysate can not be blocked in the hollow fiber membranes, and the flow of the dialysate in the hollow fiber membranes can be properly reduced on the premise that the expected toxin removal effect can be achieved, and the use cost of the dialysate is reduced.

Because the blood of the device can be directly contacted with the adsorption resin piece, the adsorption resin piece is convenient for adsorbing toxins in the blood, and the toxin elimination efficiency is improved; blood can contact with the adsorption resin piece and the hollow fiber membrane simultaneously, and the collision between the adsorption resin piece and the hollow fiber membrane is convenient for diffuse in the shell of the adsorber in the flowing process of blood, so that the blood and the dialysate flow uniformly, and the device has good dialysis effect, is used in series with the dialyzer relative to the hemoperfusion apparatus, has lower blood chamber capacity, and can avoid the occurrence of hypotension of patients.

In conclusion, the hemodialysis adsorber provided by the utility model can be used for eliminating micromolecular toxins while meeting the requirement of the macromolecular toxin eliminating capability, so that the defect that the adsorber and the dialyzer are used in series is effectively overcome.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present utility model, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a graph showing the urea content variation provided by the present utility model;

FIG. 2 is a graph showing the variation of the beta 2-MG content provided by the present utility model;

FIG. 3 is a schematic view of a hemodialysis adsorber according to the present utility model;

FIG. 4 is a schematic view of another construction of a hemodialysis adsorber;

fig. 5 is a cross-sectional view of fig. 4.

In fig. 1-5:

the device comprises a dialysis liquid inlet 1, an end cover 2, a shell 3, a hollow fiber membrane 4, an adsorption resin piece 5, a sealing glue 6, a filter screen 7, a blood inlet 8, a sealing ring 9, a blood outlet 10, a dialysis liquid outlet 11, a height L1, a distance L2 and a diameter L3.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The utility model provides a hemodialysis adsorber, which can remove micromolecular toxins while meeting the removal capacity of macromolecular toxins so as to effectively overcome the defect that the adsorber and a dialyzer are used in series.

Please refer to fig. 1 to 5.

The present embodiment provides a hemodialysis adsorber comprising:

a housing 3 having a blood inlet 8 and a blood outlet 10 at the sides thereof;

end caps 2 provided at both ends of the housing 3, the two end caps 2 being provided with a dialysate inlet 1 and a dialysate outlet 11, respectively;

an adsorption resin member 5, the adsorption resin member 5 being provided on the outer periphery of the hollow fiber membrane 4;

a plurality of tubular hollow fiber membranes 4 uniformly penetrate through the inner cavity of the shell 3;

the two ends of the hollow fiber membrane 4 are sealed in the shell 3 through the sealing glue 6, blood flows on the outer surface of the hollow fiber membrane 4, dialysate flows in the inner cavity of the hollow fiber membrane 4, and the blood and the dialysate flow in opposite directions.

The hollow fiber membrane 4, the housing 3, and the end cap 2 may be filled with water for injection to ensure that the components do not affect the flow and transport of blood and dialysate. The adsorption resin member 5 may be provided in a microsphere structure provided with a plurality of mesh openings. The device is characterized in that the hollow fiber membrane 4 is implanted into the shell 3 of the adsorber, blood flows outside the hollow fiber membrane 4, and dialysate flows in the hollow fiber membrane 4 in opposite directions, so that the mode that blood can only flow inside the hollow fiber membrane 4 in the traditional sense is broken, a blood adsorber capable of carrying out hemodialysis is prepared, and the effect that a dialyzer and the adsorber are connected in parallel can be achieved. The device is also suitable for hemodialysis, hemodiafiltration, hemofiltration, blood adsorption and other situations.

The shape, structure, size, etc. of the housing 3, the hollow fiber membrane 4, the end cap 2, and the sealing compound 6 can be determined according to actual conditions and actual demands in the actual application process.

When the hemodialysis adsorber provided by the utility model is used, the sealing glue 6 can effectively separate the dialysate from the blood, and direct contact between the dialysate and the blood is avoided. Thus, the dialysate can enter the hollow fiber membranes 4 through the dialysate inlet 1 of the end cap 2 and finally flow out of the dialysate outlet 11 of the end cap 2, and the blood can pass through the blood inlet 8, the inner cavity of the housing 3 and the blood outlet 10 in order. In the flowing process, blood can flow on the outer surface of the hollow fiber membrane 4, dialysate can flow in the inner cavity of the hollow fiber membrane 4, and the blood and the dialysate flow in the same direction, so that the mode that the blood can only flow in the hollow fiber membrane 4 in the traditional sense is broken. Meanwhile, the phenomenon of bias flow generated by the dialysate during use is avoided, so that the adequacy of dialysis is improved, and the defect that the absorber and the dialyzer are used in series is overcome.

When the dialysate flows through the hollow fiber membranes 4, the hollow fiber membranes 4 are distributed uniformly in the shell 3, so that the flow of the dialysate in the hollow fiber membranes 4 is more uniform than that in the hollow fiber membranes 4, and meanwhile, the contact area of the blood and the dialysate on the surfaces of the hollow fiber membranes 4 is ensured to be more uniform, thereby being beneficial to the substance exchange between the blood and the dialysate. In addition, the dialysate flows in the hollow fiber membranes 4 which are uniformly distributed, so that the phenomenon of turbulence which occurs when the outside of the hollow fiber membranes 4 flows can be avoided, the dialysate can not be blocked in the hollow fiber membranes 4, and the flow of the dialysate in the hollow fiber membranes 4 can be properly reduced on the premise that the expected toxin removal effect can be achieved, and the use cost of the dialysate is reduced.

Because the blood of the device can be directly contacted with the adsorption resin piece 5, the adsorption resin piece 5 is convenient for adsorbing toxins in the blood, and the toxin elimination efficiency is improved; blood can contact with the adsorption resin piece 5 and the hollow fiber membrane 4 simultaneously, and the collision between the adsorption resin piece 5 and the hollow fiber membrane 4 is passed through to blood in the flow process, is convenient for diffuse in the inside of the shell 3 of adsorber for blood and dialysate flow are even, have dialysis effect good, and it is used in series with the dialyzer for the hemoperfusion ware, and the blood room capacity is lower, can avoid patient's hypotension to take place.

On the basis of the above embodiment, it is preferable that the blood inlet 8 and the blood outlet 10 are provided on the same side as shown in fig. 3 so that the blood flows through the entire inner cavity of the housing 3 to be sufficiently in contact with the hollow fiber membrane for replacement.

Preferably, the blood inlet 8 and the blood outlet 10 are provided on opposite sides and symmetrically distributed with respect to the central axis of the housing 3, as shown in fig. 4, so that the blood can flow through the entire inner cavity of the housing 3 and be sufficiently contacted with the hollow fiber membrane for the replacement operation.

Preferably, the dialysis device further comprises sealing rings 9 arranged at two ends of the inner cavity of the shell 3, the inner wall of the end cover 2 and the surface of the sealing glue 6 are attached to the sealing rings 9, and the end parts of the hollow fiber membranes 4 are located in the inner ring space of the sealing rings 9 so as to ensure that the sealing rings 9 can effectively prevent dialysis liquid from leaking out to the outside of the shell 3.

Preferably, the adsorbent resin member 5 is provided on both the inner peripheral portion of the blood outlet 10 and the inner peripheral portion of the blood inlet 8. The adsorption resin member 5 may be a polystyrene-divinylbenzene adsorption resin material.

Preferably, the volume of the adsorption resin member 5 is 100mL-800mL.

The hollow fiber membrane 4 is preferably a polymethyl methacrylate material, and the hollow fiber membrane 4 may be a polymer alloy material, and the material of the hollow fiber membrane 4 is not limited to the above.

Preferably, the pore diameter of the membrane surface of the hollow fiber membrane 4 is 1nm-6nm, the internal diameter of membrane wires of the hollow fiber membrane 4 is 180 μm-220 μm, and the thickness of the membrane wires of the hollow fiber membrane 4 is 35 μm-50 μm, so as to improve the dialysis effect of the dialysate in the hollow fiber membrane 4.

On the basis of the above embodiment, it is preferable that both the blood inlet 8 and the blood outlet 10 are provided with a filter screen 7 to preliminarily filter blood. And, can set up filter screen 7 as nylon material spare to improve the result of use of filter screen 7.

Preferably, both the end cap 2 and the housing 3 are made of polycarbonate/polypropylene alloy, so as to improve the service life of the end cap 2 and the housing 3.

Preferably, the sealing glue 6 is made of polyurethane, so as to ensure that the two ends of the hollow fiber membrane 4 are sufficiently fixed and avoid gaps at the joint of the end part of the hollow fiber membrane 4 and the sealing ring 9; moreover, the sealing ring 9 can be made of silica gel, so that the inner cavity of the shell 3 is fully sealed, and the phenomenon of dialysate extravasation is avoided. The preparation process of the end cover 2, the shell 3 and the sealing glue 6 is as follows:

1. the hollow fiber membranes 4 are arranged into a membrane bundle structure and are placed in the shell 3, and two ends of the hollow fiber membranes 4 are arranged on the shell 3 in a protruding mode;

2. sealing one end of the shell 3 by using the end cover 2;

3. the other end of the housing 3 is injected with a microsphere-shaped adsorption resin member 5, and the injection mode of the adsorption resin member 5 can be an ultrasonic mode or the like;

4. removing the end cover 2, sintering membrane bundles at two ends of the hollow fiber membrane 4, and sealing two ends of the shell 3 by using the end cover 2;

5. sealing glue 6 is used for sealing the two ends of the shell 3 and the hollow fiber membrane 4;

6. removing the end cap 2 and cutting the end face of the hollow fiber membrane 4;

7. the end cap 2 is screwed down.

In the above process, the end cap 2 may be replaced with a sealing film, which is not limited to a specific material, as long as it has a certain sealing property. If a sealing film is used, the sealing film can be melted directly during sintering. In step 5, the sealer 6 is centrifuged during the end-capping process of the two ends of the case 3. The centrifugation refers to the centrifugation of injecting glue and then cutting, in which the adsorption resin members 5 may be gathered at both ends of the bundle of the hollow fiber membranes 4, and then the adsorption resin members 5 at both ends may be cut off in the subsequent cutting process.

In order to avoid the above phenomenon, the end cover 2 adopted in the process has a binding function, namely, a hoop or other binding structure is adopted to bind and bind the inner positions of the two ends of the membrane bundle of the hollow fiber membrane 4, so that the hollow fiber membrane 4 and the adsorption resin piece 5 are prevented from being gathered at the two ends along with centrifugal glue injection. Therefore, the hollow fiber membrane 4 does not contain the adsorption resin member 5 in the subsequent cutting process.

In order to further illustrate the method of using the hemodialysis adsorber provided by the present utility model, an example will be described.

1. Preparation of simulation liquid

Fresh 5L of fresh pig blood is adopted for a simulated clinical test, 3.8% sodium citrate is adopted for anticoagulation, the volume ratio of anticoagulant to blood is 1:20, and a certain amount of urea and beta 2-microglobulin are respectively added into the blood according to the YY0053-2016 standard requirement to prepare a simulated liquid with the urea content of 35mmol/L and the beta 2-microglobulin content (beta 2-MG) of 10 MG/L.

2. Preparation before getting on machine

1 hemodialysis adsorber (test group) and adsorber (control group) having the same specification and amount of the adsorbent resin material 5 were each prepared, and the inside of the hemodialysis adsorber hollow fiber membrane 4 was pre-washed with physiological saline at a flow rate of 150mL/min, and with 100 mL/min.

3. Upper machine

Dividing the prepared 5L simulated liquid into two parts, and respectively using the two parts as a hemodialysis adsorber and a blood adsorber to carry out clinical simulation test, wherein the blood flow of the blood adsorber in the test circulation process is 150mL/min; the blood flow of the hemodialysis adsorber was 150mL/min, and the flow rate of the dialysate was 300mL/min.

4. Sampling

In the clinical simulation process, urea and beta 2-microglobulin content are sampled and tested at 0, 15min, 30min, 60min, 120min and 180min respectively, and the detection result is recorded, and each sample product can be repeatedly tested for 2 times.

5. Drawing urea and beta 2-microglobulin content change curve

The time t-urea/beta 2-microglobulin content c is recorded and plotted.

The hemodialysis adsorber may be configured to: diameter L3 is 7cm, height L1 is 17 cm's cylindric structure, and set up blood outlet 10 in 1cm department from casing 3 top, set up blood inlet 8 in 1cm department from casing 3 bottom, be equipped with the diameter size of the position of blood inlet 8 and blood outlet 10 slightly more than 7cm, blood inlet 8 and blood outlet 10's interval L2 is 15cm, and the top of casing 3 is equipped with dialysate import 1, the bottom of casing 3 is equipped with dialysate export 11, the structure is as shown in figure 3. In use, blood flows inside the housing 3 and outside the hollow fiber membranes 4, dialysate flows from the inside surfaces of the hollow fiber membranes 4, and blood flows in opposition to the dialysate.

The samples prepared according to the above procedure were subjected to performance tests, the test data are as follows:

table 1 test parameters

Table 2 test parameters

As can be seen from the above tables 1, 2 and FIGS. 1 and 2, the urea and beta 2-MG decrease rates in the test group were significantly higher than those in the control group, i.e., the hemodialysis adsorber provided in the present application had good small/large molecular toxin removal capacity. The device can lead the blood and the dialysate to flow uniformly, has good dialysis effect, and the adsorption resin piece 5 is filled in the blood chamber, the blood chamber capacity is low, the dialysate flows in the hollow fiber membrane 4, the consumption of the dialysate can be reduced, and the use cost is reduced; the device sets the dialyzer and the absorber into an integrated structure, so that the structure and the operation process of the device are simpler.

In addition, it should be further noted that the positional or positional relationship indicated by "top and bottom", "inside and outside", etc. in the present application is based on the positional or positional relationship shown in the drawings, and is merely for convenience of description and understanding, and does not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. Any combination of all the embodiments provided in the present utility model is within the protection scope of the present utility model, and will not be described herein.

The hemodialysis adsorber provided by the utility model is described in detail above. The principles and embodiments of the present utility model have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present utility model and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the utility model can be made without departing from the principles of the utility model and these modifications and adaptations are intended to be within the scope of the utility model as defined in the following claims.

Claims

1. A hemodialysis adsorber, comprising:

a housing (3) provided with a blood inlet (8) and a blood outlet (10) on the side;

end covers (2) which are arranged at two ends of the shell (3), wherein the two end covers (2) are respectively provided with a dialysate inlet (1) and a dialysate outlet (11);

an adsorption resin member (5), wherein the adsorption resin member (5) is provided on the outer periphery of the hollow fiber membrane (4);

the hollow fiber membranes (4) are uniformly penetrated through the inner cavity of the shell (3) and a plurality of tubular hollow fiber membranes (4);

the two ends of the hollow fiber membrane (4) are sealed in the shell (3) through sealing glue (6), blood flows on the outer surface of the hollow fiber membrane (4), dialysate flows in the inner cavity of the hollow fiber membrane (4), and the blood and the dialysate flow in opposite directions.

2. Hemodialysis adsorber according to claim 1, characterized in that the blood inlet (8) and the blood outlet (10) are arranged on the same side.

3. Hemodialysis adsorber according to claim 1, characterized in that the blood inlet (8) and the blood outlet (10) are arranged on opposite sides and are symmetrically distributed with respect to the central axis of the housing (3).

4. Hemodialysis adsorber according to claim 1, characterized in that it further comprises sealing rings (9) arranged at two ends of the inner cavity of the housing (3), the inner wall of the end cover (2) and the surface of the sealing glue (6) are attached to the sealing rings (9), and the end parts of the hollow fiber membranes (4) are located in the inner ring space of the sealing rings (9).

5. Hemodialysis adsorber according to claim 1, characterized in that the inner peripheral part of the blood outlet (10) and the inner peripheral part of the blood inlet (8) are both provided with the adsorption resin member (5).

6. Hemodialysis adsorber according to claim 5, characterized in that the volume of the adsorption resin member (5) is 100mL-800mL.

7. Hemodialysis adsorber according to any of claims 1 to 6, characterized in that the membrane surface pore size of the hollow fiber membranes (4) is 1nm-6nm, the membrane wire inner diameter of the hollow fiber membranes (4) is 180 μm-220 μm, and the membrane wire thickness of the hollow fiber membranes (4) is 35 μm-50 μm.

8. Hemodialysis adsorber according to any of claims 1 to 6, characterized in that the blood inlet (8) and the blood outlet (10) are each provided with a filter screen (7).

9. Hemodialysis adsorber according to any of claims 1 to 6, characterized in that the end cap (2) and the housing (3) are both polycarbonate/polypropylene alloy pieces.

10. Hemodialysis adsorber according to any of claims 1 to 6, characterized in that the sealing gel (6) is a polyurethane material.