KR20230080663A - Membrane and manufacturing method of the same - Google Patents

Abstract

A filtration membrane according to the present invention includes a fusion layer containing a fluorine-based resin heat-sealed between a first end and a second end of a filtration membrane sheet including a fluorine-based porous membrane and a mesh-like support provided on at least one surface of the porous membrane. characterized in that the thickness (T3) of the fusion bonded layer is 50 to 200 μm, and the melting point of the fusion bonded layer is 280 to 350° C. lower than the melting point of the filter membrane sheet material.

Description

Filter membrane and its manufacturing method {Membrane and manufacturing method of the same}

The present invention relates to a filtration membrane and a method for producing the same, and more specifically, to a filtration membrane when the filtration membrane is made of a fluoropolymer and a method for manufacturing the same.

BACKGROUND OF THE INVENTION Filtration membranes and filter products including filtration membranes are used to separate unwanted substances from useful substances in a fluid material. Exemplary filters are filters for water treatment or processing of ultrapure aqueous and organic solvent solutions for use in microelectronic devices and semiconductor processing, and filters used for water purification processes.

Examples of effective filtration membranes include porous structures having an average pore size that can be selected based on the purpose of the filter, i.e., the type of filtration performed by the filter.

The filtration membrane may be a cartridge filter in the form of a pleated or flat sheet as needed, and the filtration membrane is accommodated in a case and is convenient to replace. At this time, the filtration membrane is accommodated in the case so that the filtration fluid flows in through the inlet and passes through the outlet after passing through the filtration membrane.

At this time, in order to force the fluid to pass through the filtration membrane in the case of manufacturing the cartridge filter, the ends of the sheet-like filtration membrane are usually bonded to each other to form a cylindrical shape, and ultrasonic welding is mainly used for this purpose.

However, filtration membranes used in the semiconductor industry are often made of fluoropolymers, but due to the nature of fluoropolymers, it is difficult to bond them by ultrasonic welding.

Republic of Korea Patent Publication No. 10-2021-0101855

An object of the present invention is to provide a fluoropolymer filtration membrane having a fusion layer in which ends are joined by thermal fusion using a fluorine-based fusion material.

Another aspect of the present invention is to provide a method for manufacturing a fluoropolymer filtration membrane using a fluorine-based fusing material.

A filtration membrane according to an aspect of the present invention includes a fluorine-based resin heat-sealed between a first end and a second end of a filtration membrane sheet including a fluorine-based porous membrane and a mesh support provided on at least one surface of the porous membrane. It is a cylindrical structure including a junction with layers, the thickness (T3) of the fusion bonding layer is 50 to 200 μm, and the melting point of the fusion bonding layer is 280 to 350 ° C., which is lower than the melting point of the filter membrane sheet material. do.

At this time, it is preferable that the tensile strength at the time of tension of the joint is 2 kgf/mm ² or more, and the elongation at the time of tension is 360 to 380%.

In addition, it is preferable that the mesh-like support is provided on both sides of the porous membrane.

In addition, when the thickness of the porous membrane at the first end is T1, the thickness of one of the mesh-like supports is T2, and the thickness of the fusion layer is T3, the relationship between T1, T2 and T3 preferably satisfies the following formula 1 do.

(Equation 1) T3>T2>T1

At this time, the fusion layer may be PFA (Perfluoroalkoxy).

In addition, the overlapping length of the ends is preferably 30 mm or less.

A method for producing a filtration membrane according to another aspect of the present invention,

providing a filtration membrane sheet;

overlapping both ends of the filtration membrane sheet with a predetermined length, inserting a heat-sealing material between both ends, and positioning a release material outside the both ends;

Forming a junction by heating and heat-sealing the both ends, the heat-sealing material, and the release material with a hot plate; and

and cooling the junction with a cooling plate.

At this time, the melting point of the fusion material is preferably 280 to 350° C. lower than the melting point of the filtration membrane material.

Also, the release material may be polyimide.

In addition, it is preferable to include a step of folding the filtration membrane sheet to form pleats after the step of providing the filtration membrane sheet.

A cartridge filter according to another aspect of the present invention,

A cylindrical filtration membrane having a joint portion obtained by placing a fusion material between a first end and a second end of a sheet including a fluorine-based porous membrane and a mesh-shaped support provided on at least one surface of the porous membrane and heat-sealing the sheet; and

Including a case including the filtration membrane in the inner space,

The melting point of the fusion material is 280 to 350° C. lower than the melting point of the filtration membrane sheet.

The filtration membrane according to the present invention has an effect of efficiently bonding the junction of the end of the filtration membrane while having high chemical resistance and tensile strength by heat-sealing using a fluorine-based fusing material during the end joining process.

In addition, the manufacturing method of the filtration membrane according to the present invention not only bonds the junction, which is the end of the filtration membrane, with high chemical resistance and tensile strength, but also prevents the end from sticking to the jig during thermal fusion, and prevents heat shrinkage after bonding. It works.

1 is a perspective view showing an embodiment of a cartridge filter using a filtration membrane according to the present invention.
2 is a perspective view showing an embodiment of a cylindrical pleated filtration membrane used in a cartridge filter.
3 is a cross-sectional view of the filtration membrane of FIG. 2;

Prior to describing the present invention in detail below, it is understood that the terms used herein are intended to describe specific embodiments and are not intended to limit the scope of the present invention, which is limited only by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art unless otherwise specified.

Throughout this specification and claims, the terms "comprise", "comprise" and "comprising", unless stated otherwise, are meant to include a stated object, step or group of objects, and steps, and any other object However, it is not used in the sense of excluding a step or a group of objects or a group of steps.

On the other hand, various embodiments of the present invention can be combined with any other embodiments unless clearly indicated to the contrary. Any feature indicated as being particularly desirable or advantageous may be combined with any other features and characteristics indicated as being particularly desirable or advantageous.

In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. When describing the drawings as a whole, it is described from the observer's point of view, and when one component is said to be "above/below" or "above/below" another component, this is not only the case of being "directly above/below" another component. , including the case where there is another component in the middle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a perspective view showing an embodiment of a cartridge filter using a filtration membrane according to the present invention;

2 is a perspective view showing an embodiment of a cylindrical pleated filtration membrane used in a cartridge filter, and FIG. 3 is a cross-sectional view of the filtration membrane of FIG. 2 .

According to this, the cartridge filter 10 includes a case 100, a finishing material 200, and a filtration membrane 300. The case 100 is a hollow cylindrical shape and includes a filtration membrane 300 in the inner space between the outer case and the inner case (core).

The finishing material 200 is coupled to the end of the case while sealing the end of the filtration membrane. For example, the filtration membrane is sealed while imparting integrity and strength to the finishing material by thermal fusion or infrared fusion, and is also combined with the case. At this time, it is preferable that the finishing material is also provided with a polymer containing fluorine.

At this time, when fusing with infrared rays, an infrared ceramic heater can be used, and it is preferable to fuse in a non-contact manner.

The filtration membrane 300 is accommodated in the inner space of the case, and for this purpose, ends of the filtration membrane sheets are bonded to each other during manufacture to be accommodated in the inner space of the hollow case.

Therefore, the finished filtration membrane has a cylindrical shape in which the first end and the second end are joined to each other, and in the finished cylindrical filtration membrane, the end portion is called an end portion to distinguish it from the joined end of the filter membrane sheet before completion. At this time, the end portion of the filtration membrane is sealed and bonded to the finishing material 200 to function as a filter.

At this time, the filtration membrane sheet before joining the ends may have a flat shape or a pleated flat sheet, but a pleated shape is more preferable as shown in order to increase the filtration area. At this time, the wrinkle density is preferably 60 to 90%.

The filtration membrane 300 of this embodiment includes a porous fluoropolymer membrane 310 and mesh-type supports 320 and 330 . In the drawing, it is shown that the mesh-type support is provided on both sides, but it is also possible that the mesh-type support is supported on only one side according to the embodiment. The porous membrane 310 is made of a fluoropolymer, and for example, PTFE has good chemical resistance (pH 1 to 14) and heat resistance (-268 to 315 ° C), so it can be usefully used.

At this time, the porous membrane 310 preferably has an average pore diameter of 0.0001 to 1.0 μm and a thickness of 1 to 150 μm.

The mesh-type supports 320 and 330 are a pair of supports supporting the porous membrane on both sides. In this case, the filtration membrane has a three-layer laminated structure in which the porous membrane is sandwiched in the middle of the mesh-type support. The material of the mesh-type supports 320 and 330 may be PFA, PTFE, ETFE, PVDF, PEEK, PCTFE, CTFE, PVF, FEP, ECTFE, etc., and PFA may be preferably used in terms of tensile strength or melting temperature.

The mesh-type supports 320 and 330 may have an average pore diameter of 100 to 400 μm and a thickness of 30 to 100 μm. The mesh-like support does not become a flow (resistance) of the fluid during filtration, should have no problem in supporting the membrane, and is formed with a thickness that does not reduce the effective filtration area. The thickness of the mesh-like support on both sides is usually made to be the same thickness.

On the other hand, in order for the filtration membrane to act as a cartridge filter, both ends of the filtration membrane must be bonded to each other so that the inside and outside of the filtration membrane are disconnected from each other, which is called side seaming. Thus, the end of the filtration membrane manufactured in a cylindrical shape has a junction 350 overlapping and joined, and the junction is formed while being melted by heat.

At this time, the bonding portion includes a fluorine-based fusion layer having adhesive strength. That is, in order to join the ends of the filtration membranes containing fluorine to each other, a fluorine-based fusing material is used as a separate connecting material.

In the junction part 350, the first end (A) and the second end (B) overlap, and the fusion layer (C) is interposed between the first end (A) and the second end (B). At this time, each end is referred to as an end portion overlapping inside 30 mm on the filtration membrane sheet.

The fusion bonding layer (C) adheres the first end (A) and the second end (B) while being fused by heat, and the melting point of the fusion bonding material is preferably 280 to 350 ° C. because it does

Also, the thickness of the fused layer (C) is 50 to 200 μm, more preferably 50 to 125 μm. This is because, below the above range, the melting material is melted but the tensile strength is not secured, and when the range is exceeded, the melting material is not well bonded and the tensile strength is lowered.

An example of such a material for the fusion layer is preferably a resin containing fluorine, because chemical resistance must be provided in an environment in which a fluorine-based porous film is used depending on the application. As a preferred example, PFA (Perfluoroalkoxy) having tensile strength and bonding strength may be used.

Since the outer surface of the junction is a mesh-like support, the fusing material is interposed between the mesh-like supports of the first and second ends to fuse the first and second ends. At this time, the tensile strength of the junction is 2kgf/mm ² or more, preferably 2.5 to 5.5 kgf/mm ² , and the elongation at this time is preferably 360 to 380%.

Table 1 is a table summarizing the tensile strength and elongation measured by a tensile strength meter by varying the thickness of the welding material. The tensile strength tester used was TnDorf (Technology and Dorf. Inc) model name TD-U02, and the tensile strength was higher when PFA was used than when no welding material was used. In addition, when the thickness of the fusing material is too high, it can be confirmed that the tensile strength rather decreases.

sample name Tensile strength (kgf/mm ² ) Elongation (%) No welding material 1.198 190.93 PFA 50㎛ 2.548 378.46 PFA 100㎛ 3.373 378.02 PFA 125㎛ 4.386 365.92 PFA 200㎛ 5.298 360.58 PFA 250㎛ 1.567 112.66

On the other hand, when the thickness of the porous membrane at the first end of the manufactured filtration membrane is T1, the thickness of one mesh-like support is T2, and the thickness of the fusion material is T3, the relationship between T1, T2, and T3 is as shown in Equation 1.

(Equation 1)

T3>T2>T1

Next, a method for manufacturing a filtration membrane, which is another aspect of the present invention, will be described. The method for manufacturing a filtration membrane includes a step of manufacturing a filtration membrane sheet, a pleat formation step, an end fixing step, a heat fusion step, and a cooling step.

The step of providing a filtration membrane sheet is a step of providing a filtration membrane sheet, and in one embodiment, a filtration membrane having a three-layer structure in which mesh-type supports are attached to both sides of a porous membrane may be used.

The porous membrane is made of a fluoropolymer. In this case, the fluoropolymer is not limited when fluorine is included, but PTFE can be used more usefully.

At this time, the porous membrane 310 preferably has pores of 0.0001 to 1.0 μm and a thickness of 1 to 150 μm.

The mesh-type support is a support that supports the porous membrane on both sides, and in this case, the filtration membrane has a three-layer laminated structure with the porous membrane sandwiched in the middle. The material of the mesh-type support may be PFA, PTFE, ETFE, PVDF, PEEK, PCTFE, CTFE, PVF, FEP, ECTFE, or the like.

The mesh-type supports 320 and 330 may have an average pore diameter of 100 to 400 μm and a thickness of 30 to 100 μm.

The pleating step is a step of folding the filtration membrane sheet to form pleats in order to widen the filtration cross section of the filtration membrane, and the width of the pleats is not limited.

In the end overlapping step, portions of a predetermined length of both ends remaining after forming wrinkles on a flat sheet-type filtration membrane are overlapped, a fusion film is inserted as a fusion material between both ends, and a release material is placed on the outside of each end. It is a step to

The fusing material is a material that melts as a medium to fuse each end with heat, and preferably has a melting point of 280 to 350 ° C and a thickness of 50 to 200 μm.

As an example of the fusing material, PFA containing fluorine can be used. At this time, since the overlapping length of each end is preferably 30 mm or less, the length of the fusion material is also determined accordingly.

The release material is placed on the outside of each end to prevent the porous membrane component of the filtration membrane or the mesh-type support component from being pressed to the hot plate when the ends are heat-sealed. As the release material, a material having a higher melting point than a porous membrane component or a mesh-type support component is used, and a polyimide film may be used as an example. At this time, the thickness of the polyimide film is preferably 0.25 to 500 μm.

The release materials are placed in the thermal fusion step and then removed when the cooling step to be described later is completed. The fusion materials are inserted in the thermal fusion step and then fused to continuously bond the ends of the filtration membrane to form a part of the filtration membrane.

The heat-sealing step is a step of forming a junction by heating and heat-sealing both ends, a heat-sealing material, and a release material with a hot plate. The heat welding temperature is preferably 280 to 350° C. at which the melting material can be melted.

The cooling step is a step of cooling with a cooling plate so that the heat-sealed joint is not thermally contracted. This is to solve the problem of heat shrinkage occurring when the thermally fused joint is not pressed with a cooling plate, causing the joint to cry.

At this time, the cooling temperature is preferably 25 to 100 ℃. If it is less than 25 ℃, there is a problem of breaking due to increased crystallinity, and if it is more than 100 ℃, there is a problem that additional equipment and energy consumption increase by changing to a heat transfer medium other than the water used.

Then, the manufactured filtration membrane is placed between the core (inner case) and the outer case, and the end portion and case end of the filtration membrane are finished with a finishing material, respectively, to manufacture a cartridge filter. At this time, the finishing material is also preferably made of a fluorine-based resin, and the finishing material is bonded to the end portion of the filtration membrane and the end portion of the case by infrared rays in a non-contact manner.

Next, a side seaming device for a filtration membrane, which is another aspect of the present invention, will be described.

4 is a front view showing an embodiment of a side seaming device for a filtration membrane according to the present invention, and FIG. 5 is an enlarged view of FIG. 4 .

The filtration membrane side seaming device is a device for performing the thermal fusion step and the cooling step in the above-described filtration membrane manufacturing method, and bonds the ends of the filtration membrane.

To this end, the side seaming device 500 includes a transfer unit 510, a thermal fusion unit 520, and a cooling unit 530. The transfer unit 510 includes a transfer jig 511 and a material supply unit. The transfer jig 511 places the filtration membrane whose ends are not bonded and transfers it to the heat fusion unit 520 and the cooling unit 530. The transfer jig 511 is provided in a form in which the filtration membrane can be stably placed in consideration of the cylindrical shape of the filtration membrane.

The material supply unit supplies the fusion material to the inside of the joining portion of the filtration membrane to be joined, and supplies the release material to the outside. The fusion material and the release material are transported together with the filtration membrane to the heat fusion unit 520 and the cooling unit 530 by the transfer unit.

The thermal fusion part 520 includes a first upper jig 520a and a first lower jig 520b. The first upper jig and the first lower jig approach each other for thermal fusion when the filtration membrane, the fusion material, and the conveying material are transferred to the thermal fusion unit, and stand apart from each other when the thermal fusion is completed.

At this time, the first upper jig 520a has a hot plate pressed from the top, and the lower jig 520b has a hot plate pressed from the bottom. ) is provided.

The cooling unit 530 includes a second upper jig 530a and a second lower jig 530b. The second upper jig and the second lower jig approach each other for thermal fusion when the fused filtration membrane is transferred to the cooling unit, and are spaced apart from each other and stand by when the thermal fusion is completed.

At this time, the second upper jig 530a has a cooling plate pressed from the top, and the lower jig has a cooling plate pressed from the bottom, and each cooling plate is provided with a chiller 531 capable of cooling the temperature to 20 ° C. do.

Hereinafter, the operation of the side seaming device will be described. The filtration membranes whose ends are not bonded are seated on the transfer jig 511 of the transfer unit in order to bond the ends to each other. At this time, a fusing material is supplied to the inside of the joining portion of the filtration membrane, and a release material is supplied to the outside. The filtration membrane is first transferred to the heat-sealed part 520 by the transfer jig 511 . In the transferred heat-sealed portion, the junction of the filtration membrane is pressed between the hot plates connected to the upper and lower jigs, and heat is supplied to melt the fusion material, so that both ends of the filtration membrane are joined.

When the thermal fusion is completed, the upper and lower hot plates are separated from each other, and the transfer jig 511 transfers the filtration membrane to the cooling unit. In the transferred cooling unit 530, the junction of the filtration membranes is cooled while being pressed between the cooling plates connected to the upper and lower jigs 530a and 530b, thereby preventing shrinkage of both ends.

When the cooling is completed, the upper and lower cooling plates are spaced apart from each other, and the filtration membrane is returned to its initial position by the transfer jig.

The features, structures, effects, etc. illustrated in each of the above-described embodiments can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

10: cartridge filter
100: case
200: finishing material
300: filtration membrane
A: first end
B: 2nd end C: fusion material
500: side seaming device
510: transfer unit
520: heat fusion part
530: cooling unit

Claims (11)

Cylindrical shape including a joint portion provided with a fusion layer containing a fluorine-based resin heat-sealed between the first and second ends of a filtration membrane sheet including a fluorine-based porous membrane and a mesh-shaped support provided on at least one surface of the porous membrane structure, the thickness (T3) of the fusion bonding layer is 50 to 200 μm, and the melting point of the fusion bonding layer is 280 to 350° C. lower than the melting point of the filtration membrane sheet material. According to claim 1,
A filtration membrane having a tensile strength of 2 kgf / mm ² or more when the joint is tensile, and an elongation of 360 to 380% when tensile. According to claim 2,
The mesh-like support is provided on both sides of the porous membrane. According to claim 3,
When the thickness of the porous membrane at the first end is T1, the thickness of one of the mesh-like supports is T2, and the thickness of the fusion layer is T3, the relationship between T1, T2, and T3 satisfies the following formula 1. A filter membrane.
(Equation 1) T3>T2>T1 According to claim 4,
The fusion layer is a filtration membrane of PFA (Perfluoroalkoxy). According to claim 5,
The length of which the ends overlap is 30 mm or less of the filtration membrane. providing a filtration membrane sheet;
overlapping both ends of the filtration membrane sheet with a predetermined length, inserting a heat-sealing material between both ends, and positioning a release material outside the both ends;
Forming a junction by heating and heat-sealing the both ends, the heat-sealing material, and the release material with a hot plate; and
A method of manufacturing a filtration membrane comprising the step of cooling the junction with a cooling plate. According to claim 7,
The fusion material is 280 to 350 ° C. lower than the melting point of the filtration membrane material. According to claim 8,
The release material is a method for producing a filtration membrane of polyimide. According to claim 9,
A method of manufacturing a filtration membrane comprising the step of folding the filtration membrane sheet to form pleats after the step of providing the filtration membrane sheet. A cylindrical filtration membrane having a joint portion obtained by placing a fusion material between a first end and a second end of a sheet including a fluorine-based porous membrane and a mesh-shaped support provided on at least one surface of the porous membrane and heat-sealing the sheet; and
Including a case including the filtration membrane in the inner space,
The cartridge filter of claim 1 , wherein the melting point of the fusion material is 280 to 350° C. lower than the melting point of the filtration membrane sheet.

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